Journal articleF1000Research · April 15, 2026
Modern scientific publishing struggles to give proper credit to the true originators of ideas. Plagiarism, deliberate or inadvertent, undermines academic integrity, while systemic pressures such as “publish or perish,” paper mills, guest authorship, ...
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Journal articleBio Systems · April 2026
This article uses two examples of mixing to demonstrate why the constructal law and the second law are distinct, self-standing laws. It begins with the definitions of two distinct phenomena: irreversibility versus design in nature (form in motion, configur ...
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Journal articleBio Systems · January 2026
This article makes an unexpected, counterintuitive theoretical step. Excessive inactive body mass (fat, carried load) has a negative impact on the efficiency of life movement to distances. Also negative is the impact of loss of body heat to the cold ambien ...
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Journal articleWind Engineering · January 1, 2026
The human urge to achieve power from nature has shaped the evolution of wind turbines, enabling the conversion of wind into useful energy. This article unveils the evolutionary aeroelastic design of wind turbines from the perspective of Constructal Law, th ...
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Journal articleInternational Communications in Heat and Mass Transfer · September 1, 2025
This research conducts an in-depth exploration of multi-objective optimization for a mini heat sink with fins using a genetic algorithm (GA). The objective is to reduce both thermal resistance and pump power consumption. The optimization problem consists o ...
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Journal articleInternational Communications in Heat and Mass Transfer · May 1, 2025
The roofs of houses look similar in profile, especially in villages and old settlements. Why? The question is about the common angle of inclination. The answer comes from heat transfer by natural convection. Inspired by the evolution of the sapiens toward ...
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Journal articleAip Advances · February 1, 2025
This article unveils the connection between design in nature and a classic mathematics problem from 1696 to 1697: the brachistochrone. Some flow designs seem to act as obstacles to flow (cataracts, waterfalls, and roll waves), in contradiction with the nat ...
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Journal articlePhysics of life reviews · September 2024
To clarify the place of time direction of change in nature (time arrow), the present article shows why Evolution and Irreversibility are two distinct phenomena. Their distinct laws of nature are the Constructal Law and the Second Law, respectively. The dem ...
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Journal articleBio Systems · September 2024
Freedom, safety, and ease of movement are innate human urges attributed to conscience along with many other preferences such as attractiveness (beauty), economy, and life. This article addresses the physics basis of the innate urge to have freedom. It unve ...
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Journal articleScientific reports · August 2024
Nature abounds in examples of evolutionary designs (bio and non-bio) that evolve freely into configurations that provide easier and greater access for movement. The present article considers three seemingly unrelated phenomena that appear to obstruct flow: ...
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Journal articleInternational Communications in Heat and Mass Transfer · June 1, 2024
Porous materials are usually thought of as amorphous mixtures of two or more things, solids, fluids, and voids. I was drawn to the nature absent from the amorphous: the structure, flow, configuration, design, purpose, and evolution. This article is a picto ...
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Journal articleBio Systems · January 2024
When a fluid accelerates as it sweeps a solid surface there are two consequences: the friction and the heat transfer (thermal contact) between fluid and solid increase simultaneously. This is known as the universal analogy between fluid friction and heat t ...
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Journal articleInternational Communications in Heat and Mass Transfer · October 1, 2023
The new direction traced in this article is to vary freely and simultaneously the fin and flow channel aspect ratios in the search for the complete high-density heat transfer flow architecture. We show that when the combined solid and fluid volume is speci ...
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Journal articlePhilosophical transactions. Series A, Mathematical, physical, and engineering sciences · August 2023
This article addresses the main research areas identified in the call for contributions to this special issue. With examples from published articles and books, the present article shows that all the identified areas are already covered by the universal pri ...
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Journal articleScientific reports · August 2023
This article addresses two questions, why certain animals (frogs, breaststroke swimmers, hovering fliers, jellyfish) push rapidly against the surrounding fluid and then reach forward slowly, and whether this rhythm of propulsion is a manifestation of the u ...
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Journal articleMed Phys · July 2023
PURPOSE: Computational abnormalities (e.g., lesion models) for use in medical imaging simulation studies are frequently generated using data collected from clinical images. Although this approach allows for highly-customizable lesion detectability studies ...
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Journal articleBio Systems · July 2023
The universal phenomenon of evolution consists of change after change in flow configuration in a time direction that is perceptible to the observer. This reality clashes with the doctrine of precise optima, minima, and maxima, now rigidly in place because ...
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Journal articleInternational Communications in Heat and Mass Transfer · December 1, 2022
This article reveals the thermodynamics of human sustainability on earth: (i) Production of power increases and, necessarily, the consumption of source energy increases (fuel, food, area covered by solar panels and windmills). Greater efficiency and energy ...
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Journal articleInternational Communications in Heat and Mass Transfer · November 1, 2022
This is a fundamental study of the periodic in & out flow through a single orifice into an enclosure. The purpose of the ‘breathing’ flow is to refresh the enclosure air. The injected air differs from the original enclosure air with respect to concentratio ...
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Journal articleBio Systems · June 2022
Evolution is a universal phenomenon of nature, bio, and non-bio. Evolution belongs in physics and general education. This step clarifies and enhances the transmission and retention of knowledge. Teaching and learning are the mental activity of grasping a n ...
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Journal articleInternational Journal of Thermal Sciences · April 1, 2022
Here we propose a heat transfer framework for how human-to-human interaction spreads everything on the landscape: disease, goods, knowledge, news, technology, science, language and culture. We show that the phenomenon of “human spreading” shares key featur ...
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Journal articleInternational Communications in Heat and Mass Transfer · March 1, 2022
This article sheds light on the fundamental physics that accounts for the similar behaviors of heat transfer and fluid friction as the configuration of the convective flow system changes. Three methods are used, and as the methods change so does the config ...
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Journal articleAIAA Journal · February 1, 2022
The uniform distribution of stresses in flying-wing aircraft improves the aeroelastic flight envelope. In this paper, we document the effect of wing cross-section configuration on the stress distribution and flutter characteristics of a flying-wing aircraf ...
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Journal articleASME Open Journal of Engineering · January 1, 2022
This article addresses the fundamental question of whether a flow system that has freedom to morph also exhibits the natural tendency to configure itself to provide greater access to its currents. The reason for questioning this evolutionary tendency in na ...
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Journal articleInternational Communications in Heat and Mass Transfer · November 1, 2021
This is a fundamental theoretical and numerical study of the evolution of tree-shaped flow on one side of the heat transfer surface of a ‘dendritic’ heat exchanger. The flow is shaped by step changes in the dimensions of the available openings. The archite ...
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Journal articleInternational Communications in Heat and Mass Transfer · June 1, 2021
The power and speed of computers processors have grown significantly, implying that a big amount of heat must be removed for better performance. A computational thermo-hydrodynamic analysis for six different non-conventional heat sinks with mini flow chann ...
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Journal articleInternational Communications in Heat and Mass Transfer · June 1, 2021
This is a study of the evolving design of a composite material with inserts that are free to be configured and distributed through the base material. Several classes of shapes of inserts are considered competitively: parallel plates, staggered plates, fork ...
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Journal articleInternational Journal of Thermal Sciences · May 1, 2021
This is a review of several key ideas and pioneers in the founding history of thermodynamics, fluid dynamics and heat transfer. Ideas treated in detail are the mechanical equivalent of heat, the difference between heat transfer and work transfer, the Navie ...
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Journal articleBiosystems · March 2021
Cells associated with an abnormal (cancerous) growth exchange flows, morph freely and grow hand-in-glove with their immediate environment, the extracellular matrix (ECM). The cell structure experiences two mass flows in counterflow. Flowing into the struct ...
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Journal articleApplied Sciences Switzerland · January 2, 2021
The emerging concept of smart buildings, which requires the incorporation of sensors and big data (BD) and utilizes artificial intelligence (AI), promises to usher in a new age of urban energy efficiency. By using AI technologies in smart buildings, energy ...
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Journal articleEnergies · January 2, 2021
This is a review of the concepts of purpose, direction, and objective in the discipline of thermodynamics, which is a pillar of physics, natural sciences, life science, and engineering science. Reviewed is the relentless evolution of this discipline toward ...
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Journal articleJournal of theoretical biology · January 2021
Flying animals morph and flex their wings during their flight. Their wings morph with the turbulent flow created around them. The wings of modern airplanes do not have this ability. In this study we show that the ability to flex the wings leads to greater ...
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Journal articleInternational Communications in Heat and Mass Transfer · January 1, 2021
The recorded history of technology and science and art shows that the evolutionary path of design is toward a greater number of dimensions, more degrees of freedom, and greater performance, efficiency and economy. Until now, designs have evolved in steps f ...
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Journal articleApplied Thermal Engineering · November 5, 2020
A novel heat exchanger architecture was investigated, in which each fluid partway transitions through the heat exchanger from tube-flow to shell-flow, or from shell-flow to tube-flow. The heat exchangers (HX) consisted of two plenums filled with tube bundl ...
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Journal articleInternational Communications in Heat and Mass Transfer · October 1, 2020
This article communicates a new problem and solution: Fluid is initially motionless in a rectangular space the shape of which is free to vary. A blade enters along one of the sides of the rectangle, moves at constant speed, and sets the fluid in motion by ...
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Journal articleEuropean Review · August 1, 2020
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Why are the rankings of universities not changing? Why is the demographic composition of top universities the same? In this review, these questions are addressed based on physics. Although size matters, higher ranks do not correlate with bigger sizes. The ...
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Journal articleBio Systems · July 2020
This is a review of recent work on how the physics of evolution accounts for the origin, changes and future of social systems. Evolution means the changes (spatial, temporal) that happen with discernible direction in time. Changes are everywhere because ph ...
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Journal articleBio Systems · July 2020
We are the human & machine species. The homo is just the inner part. The evolution of the human & machine species is oriented in time from the naked man to the man with progressively more powerful add-ons (artifacts, contrivances, devices, machines, scienc ...
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Journal articleInternational Journal of Energy Research · June 10, 2020
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This article shows that the sudden end of economic expansion (movement, wealth) emerges as a natural, physical feature of the spreading movement, which has access to power (money), freedom to morph, and power storage (savings) for future movement on even g ...
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Journal articleEnergies · May 1, 2020
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Thermodynamics is a discipline, with unambiguous concepts, words, laws and usefulness. Today it is in danger of becoming a Tower of Babel. Its key words are being pasted brazenly on new concepts, to promote them with no respect for their proper meaning. In ...
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Journal articleScientific reports · February 2020
This article unveils the geometric characteristics of boats with sails of many sizes, covering the range 102-105 kg. Data from one hundred boat models are collected and tabulated. The data show distinct trends of convergent evolution ...
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Journal articleHeat Transfer Asian Research · December 1, 2019
The constructal law was postulated in 1996 as the law of physics that accounts for the phenomenon of time evolution of configuration in all flow systems that have the freedom to morph: animate and inanimate, human made and not human made, social and indivi ...
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Journal articleInternational Communications in Heat and Mass Transfer · November 1, 2019
This paper illustrates the method of evolutionary design with freedom by considering the problem of determining the distribution of the thickness of a high-conductivity layer (heat spreader) installed on a conducting wall. Heating comes from a steady line ...
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Journal articleInternational Journal of Heat and Mass Transfer · July 1, 2019
This note offers a clear view of heat transfer fundamentals in terms of ‘heat tubes’, which are macroscopic architectures for the flow of energy through complex energy systems. The note focuses on heat tubes with conduction and convection, although heat tu ...
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Journal articleInternational Journal of Heat and Mass Transfer · June 1, 2019
With recent advancements in advanced manufacturing techniques, it is now possible to fabricate complex geometries that take advantage of well known principles of heat transfer. Therefore, unconventional configurations to enhance effectiveness beyond conven ...
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Journal articleApplied Physics Reviews · June 1, 2019
The literature reviewed in this article shows that the evolution of vehicles is in line with the evolution of animal locomotion and that it is predictable from the constructal law of design and evolution in nature. The evolution of ships and airplanes illu ...
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Journal articleEuropean Review · May 1, 2019
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Why does it feel that the time passes faster as we get older? What is the physical basis for the impression that some days are slower than others? Why do we tend to focus on the unusual (the surprise), not on the ever present? This article unveils the phys ...
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Journal articleProceedings of the Royal Society A Mathematical Physical and Engineering Sciences · March 1, 2019
Heat transfer is a mature science, and so is thermodynamics. They are almost 200 years old having developed largely independently until the 1980s. Maturity comes from the usefulness and success of the thermal sciences. This review uses the thermodynamics o ...
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Journal articleAIAA Journal · January 1, 2019
Body-freedom flutter characteristics of flying wing aircraft vary with engine placement. Here, we show why a certain design parameter (engine placement) influences the aeroelastic flight envelope of the aircraft. The approach is based on the constructal la ...
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Journal articleInternational Journal of Heat and Mass Transfer · November 1, 2018
Here we show that the morphology of a conducting wall can be ‘evolved’ by design so that its ability to enhance thermal contact with the ambient is maximized. Free to morph is the entire configuration of the conducting volume of the wall: the wall thicknes ...
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Journal articleInference: International Review of Science · October 19, 2018
Our nature is continuous and morphing, not infinitesimal, discrete, and still. With the law of evolution, physics accounts for form and the time direction in evolving macroscopic structures everywhere. ...
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Journal articleInternational Journal of Energy Research · October 10, 2018
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Why do individuals come to live (to move) together, to organize? Here, we propose that organization is a reflection of the physics reality (bio and nonbio) that it takes less power (useful energy, fuel, food, and exergy) to move 1 unit of mass in bulk than ...
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Journal articleEnergy · October 1, 2018
In this paper I use the example set by Prof. Jan Szargut as point of reference for a brief look at the current state of thermodynamics—the doctrine, its reach and importance. I start with my first encounter with Prof. Jan Szargut in 1979, and I show how hi ...
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Journal articleJ Radiol Prot · September 2018
As in any medical intervention, there is either a known or an anticipated benefit to the patient from undergoing a medical imaging procedure. This benefit is generally significant, as demonstrated by the manner in which medical imaging has transformed clin ...
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Journal articleScientific reports · August 2018
Here we show how the size of a body affects its maximum average speed of movement through its environment. The theoretical challenge was to predict that 'outliers' must exist, such as the cheetah for terrestrial animals and the jet fighter for airplanes. W ...
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Journal articleInternational Journal of Heat and Mass Transfer · April 1, 2018
In this paper, a novel geometry is proposed for evaporators that are used in Supercritical Organic Rankine Cycles. The proposed geometry consists of successive plenums at several length-scale levels, creating a multi-scale heat exchanger (HX). The channels ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 2018
Here we show the performance of a cooling system consisting of one stream that morphs while embedded in a square plate heated uniformly. Several configurations are considered in order to establish the evolutionary direction in which the thermal performance ...
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Journal articleScientific reports · September 2017
Urban heat dome flow, which is also referred to as urban heat island circulation, is important for urban ventilation and pollutant transport between adjacent cities when the background wind is weak or absent. A "dome-shaped" profile can form at the upper b ...
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Journal articleJournal of Applied Physics · August 14, 2017
The architecture of heat exchangers is a classical subject that has been studied extensively in the past. In this paper, we address the fundamental question of what the size of the heat exchanger should be, in addition to what architectural features it sho ...
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Journal articleJournal of Applied Physics · July 14, 2017
Here, we document the diversity of commercial aircraft models and bodies in use during the past five decades. Special emphasis is on the models that have moved humanity across the globe during the past three decades. The first objective is to show that the ...
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Journal articleJournal of Applied Physics · March 28, 2017
"Inequality" is a common observation about us, as members of society. In this article, we unify physics with economics by showing that the distribution of wealth is related proportionally to the movement of all the streams of a live society. The hierarchic ...
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Journal articleApplied Physics Reviews · March 1, 2017
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This review covers two aspects of “evolution” in thermodynamics. First, with the constructal law, thermodynamics is becoming the domain of physics that accounts for the phenomenon of evolution in nature, in general. Second, thermodynamics (and science gene ...
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Journal articleEuropean Review · February 1, 2017
Humans and technology are not in symbiosis. They are one species, not two. Humans, enveloped in artefacts of many kinds and ages (from writing, to airplanes), are evolving as one species, the 'human & machine species'. This evolution is visible and recorde ...
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Journal articleJournal of Applied Physics · January 28, 2017
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Why is size so important? Why are “economies of scale” a universal feature of all flow systems, animate, inanimate, and human made? The empirical evidence is clear: the bigger are more efficient carriers (per unit) than the smaller. This natural tendency i ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 2017
Obtaining accurate temperature distributions in living tissue related to hyperthermia skin cancer treatment without using an intruding sensor is a challenge. Here, we report a mathematical model that can accurately determine the temperature distribution in ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 2017
Here we explore the idea that the highest heat transfer rate between two fluids in a given volume is achieved when plate channel lengths are given by the thermal entrance length, i.e., when the thermal boundary layers meet at the exit of each channel. The ...
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Journal articleInternational Journal of Heat and Mass Transfer · August 1, 2016
Here we illustrate the free search for the optimal geometry of flow channel cross-sections that meet two objectives simultaneously: reduced resistances to heat transfer and fluid flow. The element cross section and the wall material are fixed, while the sh ...
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Journal articleInternational Journal of Heat and Mass Transfer · August 1, 2016
This paper illustrates the morphing of flow architecture toward greater performance in a counterflow heat exchanger. The architecture consists of two plenums with a core of counterflow channels between them. Each stream enters one plenum and then flows in ...
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Journal articleInternational Journal of Energy Research · August 1, 2016
Salt-gradient solar ponds (SGSPs) are water bodies that capture and accumulate large amounts of solar energy. The design of an SGSP field has never been analyzed in terms of studying the optimal number of solar ponds that must be built to maximize the usef ...
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Journal articleInternational Journal of Heat and Mass Transfer · August 1, 2016
This paper documents a numerical study of time-dependent melting dominated by natural convection in a cylinder filled with a phase change material. In accord with constructal design, the search is for effective heat-flow architectures. The volume-constrain ...
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Journal articleJournal of Applied Physics · July 7, 2016
Here, we show that during their half-century history, helicopters have been evolving into geometrically similar architectures with surprisingly sharp correlations between dimensions, performance, and body size. For example, proportionalities emerge between ...
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Journal articleJournal of Applied Physics · May 14, 2016
This article proposes "distributed energy storage" as a basic design problem of distributing energy storage material on an area. The energy flows by fluid flow from a concentrated source to points (users) distributed equidistantly on the area. The flow is ...
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Journal articleCommunicative & integrative biology · May 2016
What is evolution and why does it exist in the biological, geophysical and technological realms - in short, everywhere? Why is there a time direction - a time arrow - in the changes we know are happening every moment and everywhere? Why is the present diff ...
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Journal articleJournal of Applied Physics · March 7, 2016
Here we show that bodies of the same size suspended uniformly in space constitute a system (a "suspension") in a state of uniform volumetric tension because of mass-to-mass forces of attraction. The system "snaps" hierarchically, and evolves faster to a st ...
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Journal articleJournal of Applied Physics · February 21, 2016
Physics is concise, simple, unambiguous, and constantly improving. Yet, confusion reigns in the field especially with respect to complexity and the second law of thermodynamics. In this paper, we step back and take a look at these notions - their meaning a ...
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Journal articleScientific reports · February 2016
Here we report the discovery that even the simplest, oldest and most prevalent forms of evolutionary movement--rolling bodies and whirls of turbulence--exhibit the same body-size effect on life time and life travel as the evolutionary movement united by th ...
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Journal articleInternational Journal of Heat and Technology · January 1, 2016
Thermodynamics is brief, simple, unambiguous and improving. Yet, confusion reigns in the field. The word "entropy" is pasted on almost any new thing, without any respect for its proper definition in thermodynamics. Every author bows to his own maximum or m ...
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Journal articleAIAA Journal · January 1, 2016
The constructal theory of flight accounts not only for speed, body size, and medium density r but also for physical parameters that are an integral part of the derivation of these equations in their original sources. One parameter is the Reynolds number, w ...
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Journal articleEuropean Review · September 22, 2015
People like to say that energy and water are two problems, two vital commodities in short supply. Here I draw attention to the emerging literature and physics principle (constructal law) that provide the scientific foundation for sustainability. I show tha ...
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Journal articleInternational Journal of Heat and Mass Transfer · August 24, 2015
Rotating electric machines generate heat volumetrically, and are cooled by forced convection aided by the self-pumping effect. In this paper we focus on the fundamental relationship between the internal flow architecture of the gas cooled winding and its t ...
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Journal articleInternational Journal of Heat and Mass Transfer · July 6, 2015
Here we develop analytically the formulas for effective permeability in several configurations using the closed-form description of tree networks designed to provide flow access. The objective was to find the relation between the permeability and porosity ...
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Journal articleInternational Journal of Thermal Sciences · June 29, 2015
This paper documents the joint performance of heat pumps that are served by a common loop buried in the ground, and which operate simultaneously: one heat pump absorbs heat from the buried loop whereas the other one rejects heat. A background flow is circu ...
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Journal articleJournal of Applied Physics · June 14, 2015
Here, we report the numerical study of time dependent storage of energy by melting a phase change material. The heating is provided along invading lines, which change from single-line invasion to tree-shaped invasion. The numerical simulations show that th ...
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Journal articleInternational Journal of Energy Research · June 10, 2015
People like to say that we cannot witness evolution because it occurred over a timescale immensely greater than human experience. Here, we show that it is possible to witness, explain, and predict evolution by focusing on technology evolution. We review th ...
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Journal articleJournal of Heat Transfer · June 1, 2015
Here, I review the physics meaning of optimization, knowledge and design evolution, and why these concepts and human activities are profoundly useful for human life. A law of physics is a concise statement that summarizes a phenomenon that occurs in nature ...
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Journal articleJournal of the Royal Society, Interface · June 2015
The cerebral vascular network has evolved in such a way so as to minimize transport time and energy expenditure. This is accomplished by a subtle combination of the optimal arrangement of arteries, arterioles and capillaries and the transport mechanisms of ...
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Journal articleScientific reports · June 2015
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Here we see why humans unwittingly build fires that look the same: edifices of fuel, as tall as they are wide. The pile of fuel is permeable, air invades it by natural convection and drives the combustion. I show that the hottest pile of burning fuel occur ...
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Journal articleJournal of Applied Physics · March 28, 2015
Condensers are flow architectures needed to provide high rates of condensation (or cooling) per unit volume, in enclosures with fixed volume. Their design has not changed from configurations consisting of the banks of horizontal tubes. In this paper, we ou ...
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Journal articlePhysica A Statistical Mechanics and Its Applications · March 15, 2015
This paper demonstrates the fundamental relation that exists between the configuration of a three-dimensional living space and the time needed for the evacuation of all the inhabitants. The evacuation is treated as a physical flow system consisting of pede ...
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Journal article · February 20, 2015
AbstractThis chapter reviews three methods that account for much of the newer work in engineering thermodynamics and thermal design and optimization. The method of exergy analysis rests on thermodynamics alone. E ...
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Journal article · February 20, 2015
AbstractThis chapter reviews the first and second laws of thermodynamics and their implications in mechanical engineering. It reviews the analytical aspects (the formulas) of engineering thermodynamics primarily ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 2015
This paper documents the effect of thermal expansion on a vascularized plate that is heated and loaded mechanically. Vascular cooling channels embedded in a circular plate provide cooling and mechanical strength. The coolant enters the plate from the cente ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 2015
This paper reports a numerical and analytical study of time dependent storage of energy by melting a phase change material in a cylindrical tank. In the first part of the study the heater was a vertical spiral tube positioned coaxially with the tank. In th ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 2015
A picture is worth a thousand words. This article is about a picture known as "heatlines" since 1983, and "synergy" since 1998. Both concepts, heatlines and synergy, are about visualizing the physics of convection, which is the combination (superposition) ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 2015
Here we document the effect of flow configuration on the heat transfer performance of a helically shaped pipe embedded in a cylindrical conducting volume. The helix is wrapped on an imaginary cylinder. Several configurations of helices with fixed volume of ...
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Journal articleJournal of Applied Physics · September 21, 2014
This is a treatment of the phenomenon of energy storage by melting in an enclosure where the heating is provided by an invading line of higher temperature. We show that the melting process consists of two phases: "invasion" thermal diffusion along the inva ...
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Journal articleJournal of Applied Physics · July 22, 2014
The prevailing view is that we cannot witness biological evolution because it occurred on a time scale immensely greater than our lifetime. Here, we show that we can witness evolution in our lifetime by watching the evolution of the flying human-and-machin ...
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Journal articleInternational Journal of Heat and Mass Transfer · June 1, 2014
In this paper we determine the fundamental relation between global performance and flow configuration (constructal design) in the case of steam power generation with superheater and reheater placed in parallel in the same stream of hot gases of combustion. ...
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Journal articleJournal of Applied Physics · May 7, 2014
This paper is a proposal to embed tree-shaped vasculatures in a wall designed such that the wall withstands without excessive hot spots and peak stresses the intense heating and pressure that impinge on it. The vasculature is a quilt of square-shaped panel ...
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Journal articleJournal of Heat Transfer · May 1, 2014
Here, I show that "entransy" has no meaning in physics, because, at bottom, it rests on the false claim that in order to transfer heat to a solid body of thermodynamic temperature T, the heat transfer must be proportional to T. Entransy "dissipation" is a ...
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Journal articleScientific reports · April 2014
Turbulent curtains of smoke rise initially as flat plumes and, above a certain height, they become round plumes. The same evolution of cross-sectional shape is exhibited by jets issuing from flat nozzles. Here we predict based on principle that all such fl ...
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Journal articleInternational Journal of Energy Research · April 1, 2014
This paper reports the thermodynamic optimization of air conditioning systems with one or more evaporators, for one or more rooms. First, the paper shows that the minimization of the total power requirement leads to the same results as the minimization of ...
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Journal articleJournal of Solar Energy Engineering Transactions of the ASME · February 1, 2014
In this paper, we review the main advances made by our research group on the heat transfer performance of complex flow architectures embedded in a conducting solid. The immediate applications of this work include the design of ground-coupled heat pumps, se ...
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Journal articleScientific reports · February 2014
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Science holds that the arrow of time in nature is imprinted on one-way (irreversible) phenomena, and is accounted for by the second law of thermodynamics. Here I show that the arrow of time is painted much more visibly on another self-standing phenomenon: ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 2014
This paper documents the fundamentals of heat storage by melting a phase-change material inside a cylindrical enclosure with a vertical heated pipe on its axis. The phenomenon is studied analytically and numerically. The analysis consists of the scale anal ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 2014
In this paper we document the relationship between complex flow architecture and global performance for assemblies of heat pumps coupled thermally with the ground through a single U-shaped loop with circulating fluid. The assemblies vary according to heat ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 2014
Here we document the effect of flow configuration on the heat transfer performance of a spiral shaped pipe embedded in a cylindrical conducting volume. We considered several configurations with fixed volumes of fluid and solid. First, we optimized the geom ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 2014
In this paper we consider the fundamental problem of how to design the spacing between two plane and parallel tree structures buried in and transferring heat to a conducting medium. The Y and T tree-shaped structures are configured as two palms facing each ...
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Journal articleEcohydrology · January 1, 2014
Preferential flow in hillslope systems through subsurface networks developed from a range of botanical, faunal and geophysical processes have been observed and inferred for decades and may provide a large component of the bulk transport of water and solute ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 2014
In this paper we consider the complete thermofluid design and performance of a thermoelectric module. We increase the temperature difference that must be maintained across the module, and at the same time we reduce the pumping power required by the streams ...
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Journal articleInternational Journal of Energy Research · October 10, 2013
This paper documents the fundamental problem of designing a porous flow architecture that meets the requirements of facilitating flow access while storing and releasing heat to a flowing fluid. Examples of such designs are regenerators that operate cyclica ...
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Journal articleInternational Journal of Heat and Mass Transfer · September 9, 2013
In this paper we explore the opportunity to maximize the production of power in a steam-turbine power plant by properly configuring the hardware at the interface between the stream of hot gas produced by the furnace and the steam that circulates through th ...
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Journal articleInternational Journal of Heat and Mass Transfer · September 3, 2013
The present work shows how to minimize the global pressure drop in a comb-like channel network with self-healing and self-cooling functionalities implementing the concept of constructal design. A thick channel distributes the fluid flow to many thin channe ...
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Journal articleInternational Journal of Design and Nature and Ecodynamics · August 26, 2013
Here we show that the trends in four sports are united by the evolutionary constructal design of all animal locomotion. The trend is toward greater efficiency in the falling-forward movement of the body, and this is why the evolution of the throwing motion ...
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Journal articleInternational Journal of Design and Nature and Ecodynamics · August 26, 2013
The modern evolution of long distance running and swimming is documented statistically: body mass (M), height (H), slenderness (S), and winning speed (V). In long distance running (10,000 m), M, H, and S are decreasing: these trends contradict the trends i ...
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Journal articleInternational Journal of Heat and Mass Transfer · July 31, 2013
A heat pump that is coupled thermally with the ground extracts heat from the soil in winter, and discharges heat in the summer. The coupling is made through a buried heat exchanger. In this paper we explore the idea of using a single heat exchanger that se ...
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Journal articlePhysics of life reviews · June 2013
Gait is inherent to human life and hence its importance is often overlooked. But walking remains the most basic form of transportation and almost all journeys begin and end with a walk, regardless of the modes used in-between. Gaining a good understanding ...
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Journal articleJournal of Applied Physics · May 21, 2013
Here, we show how the performance of a paddle that pushes a fluid can be increased by making parallel slits through it. The slit spacing is varied to see its effect on the drag force and the maximum stress in the paddle. The effect of water speed and paddl ...
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Journal articleInternational Journal of Heat and Mass Transfer · May 20, 2013
Here we document and explain interactions between two thermodynamic trends that determine the optimum performance of refrigeration and heat pump systems. We show analytically why the performance of the system must increase with the size of the installation ...
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Journal articleInternational Journal of Heat and Mass Transfer · April 22, 2013
In this paper we consider the placement of buildings with ground coupled heat pumps on a densely populated area. The assemblies of pipes that constitute the ground heat exchangers occupy volumes that are shaped as parallelepipeds, the short dimension of wh ...
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Journal articleJournal of Applied Physics · April 1, 2013
This is a review of the theoretical and applied progress made based on the Constructal law of design and evolution in nature, with emphasis on the last decade. The Constructal law is the law of physics that accounts for the natural tendency of all flow sys ...
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Journal articleConvection Heat Transfer Fourth Edition · March 29, 2013
A new edition of the bestseller on convection heat transfer A revised edition of the industry classic, Convection Heat Transfer, Fourth Edition, chronicles how the field of heat transfer has grown and prospered over the last two decades. This new edition i ...
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Journal articleInternational Journal of Energy Research · February 1, 2013
Here, we show how to distribute multiple layers of insulation along a nonisothermal enclosure so that the total heat loss is minimal. The types and total amounts of insulation materials are fixed. Variables are the thicknesses of the insulation layers, the ...
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Journal articleArabian Journal for Science and Engineering · February 1, 2013
This is a review of the evolution of thermodynamics during the past four decades, from classical (engineering) thermodynamics, to thermodynamic optimization, entropy generation minimization, exergy analysis, and most recently the constructal law of design ...
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Journal articleJournal of Applied Physics · January 21, 2013
Pedestrian movement occurs in evolutionary patterns the effect of which is to facilitate the access of people into and out of living spaces (areas, volumes). In this paper, we rely on the philosophy of Constructal design as applied physics, in order to unc ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 15, 2013
This paper presents the development of the three-dimensional flow architecture of conjugate cooling channels in forced convection with internal heat generation within the solid for an array of circular cooling channels with different flow orientation. Thre ...
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Journal article · January 1, 2013
The constructal law of design evolution is the law of physics that expresses the natural tendency of all flow systems, bio and nonbio, to morph into configurations that provide greater flow access over time. River basins, animal locomotion and migratory ro ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 2013
Here we document comparatively the performance of three flow architectures for heat transfer between a buried flow structure and a conducting medium: trees with Y-shaped bifurcations, trees with T-shaped bifurcations, and classical U-shaped and serpentine ...
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Journal articleScientific reports · 2013
Here we show theoretically that the history of solid growth during "rapid" solidification must be S-shaped, in accord with the constructal law of design in nature. In the beginning the rate of solidification increases and after reaching a maximum it decrea ...
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Journal articleInternational Journal of Heat and Mass Transfer · December 1, 2012
Here we show that the heat transfer between a pipe assembly and the soil during the annual temperature cycle of a heat pump depends on the configuration of the flow system. We rely on constructal design to find the flow architecture (spacings, shapes) such ...
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Journal articleJournal of Applied Physics · October 15, 2012
Here, we show that a plate heated by a moving beam can be cooled effectively by fluid that flows through a vasculature of channels embedded in the plate. The vascular designs studied are radial, grid and hybrid (radial grid). The peak temperature of the pl ...
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Journal articleJournal of theoretical biology · September 2012
Here we show theoretically that swimming animals and athletes gain an advantage in force and speed by spreading their fingers and toes optimally. The larger force means larger body mass lifted and greater speed, in accord with the constructal theory of all ...
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Journal articleInternational Journal of Design and Nature and Ecodynamics · August 10, 2012
The power-law correlation between frequency and rank is a physics characteristic of natural flow systems (river basins, demography) in accordance with the constructal law. Here we show that this robust characteristic is a consequence of their design as are ...
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Journal articleInternational Journal of Heat and Mass Transfer · August 1, 2012
Here we determine the tree-shaped structure that facilitates heat transfer between it and the solid body in which it is embedded. The vascular design evolves toward configurations that provide progressively greater heat transfer per unit volume. Two solid ...
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Journal articleJournal of Applied Physics · May 15, 2012
Spreading and collecting flows are united by the flow design known as the S-curve: when plotted versus time, the size of the domain that is filled or emptied has a history that is shaped as an S. Here, we show that the fastest spreading or collecting (i.e. ...
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Journal articleJournal of Applied Physics · March 1, 2012
Here we show that the configuration of an inhabited area controls the time required by all the pedestrians to vacate the space. From the minimization of the global evacuation time emerges the optimal configuration of the area. This is a fundamental princip ...
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Journal articleJournal of Applied Physics · February 15, 2012
Here we document the effect of flow configuration on the heat transfer performance of a serpentine shaped stream embedded in a conducting solid. Several configurations with fixed volume of fluid are considered: U-shaped with varying spacing between the par ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 2012
Here we show the fundamental tradeoffs that underpin the design of a distributed energy system with two objectives: the production and distribution of electric power driven by solar heating, and desalinated water produced by consuming solar power. We show ...
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Journal articleInternational Journal of Heat and Mass Transfer · 2012
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Here we show that the main features of citations history (S-shaped curve, increasing h index, decreasing m quotient) are predictable with the constructal law of how an idea flows over a populated territory. It flows in two ways: fast and long, as "convecti ...
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Journal articleJournal of Applied Physics · January 1, 2012
This paper documents the time-dependent thermal interaction between a fluid stream configured as a plane tree of varying complexity embedded in a conducting solid with finite volume and insulated boundaries. The time scales of the convection-conduction phe ...
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Journal articleSci Rep · 2012
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Here we show that constructal-law physics unifies the design of animate and inanimate movement by requiring that larger bodies move farther, and their movement on the landscape last longer. The life span of mammals must scale as the body mass (M) raised to ...
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Journal articleAnalele Banatului Arheologie Istorie · December 1, 2011
The present study is aimed at bringing to the public and specialists' attention an archaeological discovery made in 2005, which is of great importance to the complex issue of Sarmatian settlement on the lower course of the Mureş river. The archaeological l ...
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Journal articlePhysics of life reviews · October 2011
The constructal law accounts for the universal phenomenon of generation and evolution of design (configuration, shape, structure, pattern, rhythm). This phenomenon is observed across the board, in animate, inanimate and human systems. The constructal law s ...
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Journal articleJournal of Applied Physics · September 15, 2011
In this paper, we show how vascular design controls the cooling and mechanical performance of a solid square slab heated uniformly and loaded with uniform pressure. The vascular structure is a combination of one grid and several peripheral trees. The desig ...
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Journal articleJournal of Applied Physics · July 15, 2011
This work documents the design method of allocating channels that serve as heat sources or heat sinks in a conducting body. First, we develop a numerical model to find the optimum channel spacing for specified properties of the surrounding medium, the time ...
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Journal articleInternational Journal of Heat and Mass Transfer · June 1, 2011
In this paper we explore the use of vascular design that provides cooling and mechanical strength at the same time. We illustrate the concept with a circular plate vascularized with embedded channels. The cooling fluid enters to the plate from the center o ...
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Journal articleInternational Journal of Energy Research · March 25, 2011
This study shows that the main features of a steam generator can be determined based on the method of constructal design. The generator is endowed with freedom to morph, and then is optimized by putting the right components in the right places. The number ...
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Journal articleInternational Journal of Heat and Mass Transfer · March 1, 2011
In this paper we use thermodynamics to show why larger flow systems are more efficient than smaller flow systems. This trend is visible across the board, from power generation and refrigeration, to vascular design and animal design. The reason is that larg ...
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Journal articleJournal of Applied Physics · 2011
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The S curve is one of the most common phenomena in nature: the spreading of populations, tumors, contaminants, innovations, economic activity. Here we show that this phenomenon can be predicted entirely by recognizing in it a flow. The flow is not by diffu ...
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Journal articleInternational Journal of Energy Research · January 1, 2011
Here we constructal design to determine the area size (or number of users N) to be allocated to a central refrigeration plant, and to configure the distribution network for the distributed cooling system. The main objective is to maximize the net cooling c ...
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Journal articleJournal of Heat Transfer · January 1, 2011
"Design in nature" is a topic of growing interest throughout science. The constructal law is the physics law of design generation and evolution in nature: "for a flow system to persist in time (to live), it must evolve such that it provides easier and easi ...
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Journal articleInternational Journal of Design and Nature and Ecodynamics · December 27, 2010
Movement on earth is effected by bodies (e.g. river channels, animals, vehicles) of seemingly random scales, large and small. Here we use the constructal law and the design of 'distributed energy systems' to show that the large must be few and the small ma ...
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Journal articleJournal of Applied Physics · December 15, 2010
Here we show that the production and use of heating on an area must be distributed in clusters organized such that the losses associated with centers of production are balanced by the losses associated with distribution lines. The energy needs increase in ...
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Journal articleInternational Journal of Thermal Sciences · December 1, 2010
Here we explore new vascular designs for volumetric bathing of smart structures with volumetric functionalities (cooling, self healing). One stream bathes the volume, and the vasculature is configured as two trees matched canopy to canopy. Several architec ...
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Journal article2010 14th International Heat Transfer Conference Ihtc 14 · December 1, 2010
This paper described numerical the procedure used to determine the optimum configuration of two rows of pin fins so that the total heat transfer rate is maximized. The heat transfer across the fins is by laminar forced convection bathed by a free-stream th ...
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Journal articleInternational Journal of Green Energy · November 1, 2010
In this paper, we show how to use constructal design to distribute solar chimney power production on available land area most efficiently. The solar chimney design is used as an example of solar-driven power plant. We found that the power generated per uni ...
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Journal articleInternational Journal of Heat and Mass Transfer · November 1, 2010
This paper shows how the configuration of a heat exchanger with fixed size controls the global performance. The cold-side fluid is driven by natural convection in vertical round tubes connected via two plenums. The hot-side fluid flows perpendicularly to t ...
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Journal articleInternational Journal of Heat and Mass Transfer · September 1, 2010
In this study, the hydrodynamic and thermal characteristics of new vascular designs for the volumetric bathing of the smart structures were investigated numerically by addressing three-dimensional continuity, momentum, and energy conservation as a conjugat ...
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Journal articleInternational Journal of Heat and Mass Transfer · July 1, 2010
Here we show that there is a complete analogy between the configuring of heat and fluid flow and the configuring of the "flow of stresses". The common principle is the avoidance of flow strangulations. This endows the flow systems (fluid, heat, stresses) w ...
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Journal articleJournal of Applied Physics · June 1, 2010
Here, we show that vascular design emerges naturally when a volume is bathed by a single stream in turbulent flow. The stream enters the volume, spreads itself to bathe the volume, and then reconstitutes itself as a single stream before it exits the volume ...
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Journal articleJournal of Applied Physics · June 1, 2010
Here we show that the configuration of a slender enclosure can be optimized such that the radiation heating of a stream of solid is performed with minimal fuel consumption at the global level. The solid moves longitudinally at constant rate through the enc ...
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Journal articleInternational Journal of Heat and Mass Transfer · June 1, 2010
In this paper we use constructal theory to determine the configuration of two rows of pin-fins so that the total heat transfer rate is maximized. The heat transfer across the fins is by laminar forced convection bathed by a free-stream that is uniform and ...
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Journal articlePhilosophical transactions of the Royal Society of London. Series B, Biological sciences · May 2010
Constructal theory is the view that (i) the generation of images of design (pattern, rhythm) in nature is a phenomenon of physics and (ii) this phenomenon is covered by a principle (the constructal law): 'for a finite-size flow system to persist in time (t ...
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Journal articleInternational Journal of Heat and Mass Transfer · April 1, 2010
In this paper we consider the fundamental problem of how to heat a stream to a specified exit temperature such that the overall fuel consumption is minimal. As illustration, we consider metal slabs that move at constant speed through a very slender enclosu ...
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Journal articleJournal of Applied Physics · March 15, 2010
When solid material is removed in order to create flow channels in a load carrying structure, the strength of the structure decreases. On the other hand, a structure with channels is lighter and easier to transport as part of a vehicle. Here, we show that ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 15, 2010
In this study, we describe the constructal-theory search for the geometry of a solar chimney. The objective is to increase the power production over the area occupied by the plant. The ratio height/radius, maximum mass flow rate and maximum power under the ...
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Journal articleAmerican Journal of Physics · 2010
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This paper shows that the emergence of body organs is predictable as an integral part of the design for moving animal mass more easily on Earth, in accord with the constructal law of design in nature: For a finite-size open system to persist in time (to li ...
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Journal articleInternational Journal of Design and Nature and Ecodynamics · 2010
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Here we explain a much avoided phenomenon in the evolution of speed sports for men and women: The world records in running tend to be set by black athletes and in swimming by white athletes. We show that this phenomenon is predictable from physics. Locomot ...
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Journal articleNumerical Heat Transfer Part A Applications · January 1, 2010
A mathematical model for skin burn injury induced by radiation heating, where the skin was considered to be a 3-D triple-layered structure with embedded three-level dendritic countercurrent vascular network, has been developed. Since there are up to seven ...
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Journal articleInternational Journal of Design and Nature and Ecodynamics · December 1, 2009
Here I show that the pattern of generation of science is in disaccord with the pattern of admission to the academy. The contrast between the two patterns is illustrated with two rankings: the most highly cited authors in all US engineering and the members ...
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Journal articleInternational Journal of Design and Nature and Ecodynamics · December 1, 2009
Shapes with length/height ratios (L/H) close to 3/2 are everywhere and give the impression that they are being 'designed' to match the golden ratio (φ = 1.618). Here I show that these shapes emerge as part of an evolutionary phenomenon that facilitates the ...
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Journal articleInternational Journal of Energy Research · December 1, 2009
This paper shows that the mass inventory for steam turbines can be distributed between high-pressure (HP) and low-pressure (LP) turbines such that the global performance of the power plant is maximal. This is demonstrated for two design classes. For an HP ...
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Journal articleInternational Journal of Thermal Sciences · November 1, 2009
Vascular flow architectures are proposed for controlling the temperature of walls that are subjected suddenly to intense heating from one side. After a short delay, single-phase coolant starts flowing from the other side, and fights off the heating effect. ...
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Journal articleJournal of Applied Physics · September 9, 2009
The generation of heat in high-density electronics is concentrated in spots, not uniform. Here we account for this fundamental aspect as a phenomenon of heat conduction in a flat body, from a concentrated heat source to surface dissipation of heat to an ex ...
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Journal articleInternational Journal of Heat and Mass Transfer · September 1, 2009
This paper is a proposal to embed tree-shaped vasculatures in a wall designed such that the wall withstands without excessive hot spots the intense heating that impinges on it. The vasculature is a quilt of square-shaped panels, each panel having a tree va ...
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Journal articleInternational Journal of Heat and Mass Transfer · September 1, 2009
Here we report the heat and fluid flow characteristics of counterflow heat exchangers with tree-shaped line-to-line flow channels. The flow structures of the hot and cold sides are sequences of point-to-line trees that alternate with upside-down trees. The ...
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Journal articleInternational Journal of Heat and Mass Transfer · September 1, 2009
Here we develop vasculatures for smart materials with volumetric cooling capability under time-varying conditions. The objective is for the vascularized composite to survive without coolant flow such that its peak temperature does not overshoot the maximum ...
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Journal articleThe Journal of experimental biology · August 2009
In the present study, we show that the fastest runners and swimmers are becoming not only faster but also heavier, taller and more slender. During the past century, the world record speeds for 100 m-freestyle and 100 m-dash have increased with body mass (M ...
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Journal articleInternational Journal of Heat and Mass Transfer · July 1, 2009
This paper reports an increase in the heat transfer rate density by using wrinkled entrance regions in ducts with laminar flow. The heat transfer rate density is increased by taking advantage of the presence of relative isothermal fluid in the entrance reg ...
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Journal articleInternational Journal of Energy Research · June 3, 2009
This essay traces the evolution of thermodynamics from its origins to ad hoc applications of thermodynamic optimization (entropy generation minimization) and the principle-based generation of flow configuration in nonequilibrium systems (constructal theory ...
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Journal articlePhysics of life reviews · June 2009
Here we show that the emergence of scaling laws in inanimate (geophysical) flow systems is analogous to the emergence of allometric laws in animate (biological) flow systems, and that features of evolutionary "design" in nature can be predicted based on a ...
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Journal articleJournal of Applied Physics · April 9, 2009
Here we report the transient cooling performance of a body vascularized with tree-shaped channels supplied with coolant, which flows from one side of the body to the other. The vasculature consists of trees that alternate with upside down trees. Heat is ge ...
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Journal articleInternational Journal of Heat and Mass Transfer · April 1, 2009
This paper shows that the architecture of a steam generator for a power plant can be deduced on the basis of the constructal law. According to constructal theory, the flow architecture emerges in time such that it provides progressively greater access to i ...
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Journal articleInternational Journal of Heat and Mass Transfer · March 1, 2009
The drive toward vascular smart materials calls for novel flow architectures that bathe and serve entire volumes and areas as uniformly as possible. Here, we show that vascular designs consisting of trees matched canopy to canopy can be configured so that ...
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Journal articlePhysica A Statistical Mechanics and Its Applications · March 1, 2009
Pattern formation and self-organization are phenomena that occur across the board, in animate and inanimate systems. In this paper, we rely on the constructal law to explain the generation of patterns (shapes, structures) in aggregates of organisms-pedestr ...
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Journal articleJournal of Porous Media · February 16, 2009
Constructal theory regards the generation of flow configuration as a natural (physics) phenomenon, and attributes this phenomenon to a physics principle (the constructal law): For a flow system to persist in time (to survive), it must evolve in such a way ...
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Journal articleInternational Journal of Heat and Mass Transfer · February 1, 2009
Vascularized materials are a new generation of smart-material concepts that offer novel volumetric functionalities such as self-cooling, self-healing, renewal, cleansing, and "designed" transport properties (permeability, effective thermal conductivity). I ...
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Journal articleInternational Journal of Thermal Sciences · February 1, 2009
A constructal tree-shaped microchannel network for maximizing the saturated critical heat flux in a disc-shaped planar body has been investigated. n0 radial channels touch the center and np channels touch the periphery. Designs with n ...
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Journal articleJournal of Hydraulic Engineering · January 29, 2009
This paper reports optimal bifurcation shapes (T and Y) in turbulent regime of tree-shaped flows. Unlike earlier studies of T and Y constructs, here the effect of pressure losses at the junction is taken into account, and the wall roughness and duct cross- ...
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Journal articleWit Transactions on Ecology and the Environment · January 1, 2009
In this paper the global design of energy production, distribution and sustainability is approached based on constructal theory. The global energy system is viewed as a conglomerate of flow systems morphing in time such that it provides greater and greater ...
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Journal articleAeronautical Journal · January 1, 2009
Vascular structures are contemplated for cooling the skins and leading surfaces of future high speed aircraft. This paper evaluates the proposal to cool with a flow architecture shaped as trees (dendritic) a parallelepipedic body that is heated uniformly. ...
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Journal articleASME International Mechanical Engineering Congress and Exposition Proceedings · January 1, 2009
Constructal theory complements the analysis of thermodynamic systems by focusing on the flow configuration of the system, and on the relationship between configuration (design) and global performance. The design progress made in this emerging field is revi ...
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Journal articleTransport in Porous Media · January 1, 2009
According to constructal theory, the "generation of flow configuration" is a universal phenomenon in physics. This phenomenon is covered by the constructal law: "For a finite-size flow system to persist in time (to live) it must evolve such that it provide ...
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Journal articleInternational Journal of Heat and Mass Transfer · December 1, 2008
This paper is a proposal to vascularize a solid wall with transverse tree-shaped channels with fluid flow from side to side. The purpose of the fluid flow is to intercept in counterflow the solid heat conduction caused by an intense heat flux that lands on ...
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Journal article10th Electronics Packaging Technology Conference EPTC 2008 · December 1, 2008
This paper reports original work on the development of vascular flow architectures for cooling flat bodies that are heated uniformly by electronics. This is the latest work in applying constructal theory to the conceptual development of architectures for h ...
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Journal articleInternational Journal of Design and Nature and Ecodynamics · December 1, 2008
"Empire building" is a phenomenon that dominates today's research landscape. Large groups, national priorities and research centers dwarf the spontaneous individual investigators. Administrators and the thirst for higher rankings encourage this trend. Yet, ...
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Journal articleInternational Journal of Heat and Mass Transfer · November 1, 2008
We modify the Pennes model by taking into account the thermal relaxation time of biological tissue. Specifically, we employ the Maxwell-Cattaneo thermal flux law, in conjunction with the fourth power law, to model the effects of high thermal radiation on s ...
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Journal articleJournal of theoretical biology · October 2008
Here, we show that the most basic features of tree and forest architecture can be put on a unifying theoretical basis, which is provided by the constructal law. Key is the integrative approach to understanding the emergence of "designedness" in nature. Tre ...
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Journal articleAip Conference Proceedings · September 26, 2008
This article reports an open discussion that took place during the Keenan Symposium "Meeting the Entropy Challenge" (held in Cambridge, Massachusetts, on October 4, 2007) following the short presentations - each reported as a separate article in the presen ...
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Journal articleAip Conference Proceedings · September 26, 2008
The laws of classical thermodynamics refer to systems as black boxes, without configuration. Nature is different: it has "designedness" everywhere and at all scales (pattern, configuration, rhythm). The generation of configuration is a phenomenon of all ph ...
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Journal articleAip Conference Proceedings · September 26, 2008
This article reports an open discussion that took place during the Keenan Symposium "Meeting the Entropy Challenge" (held in Cambridge, Massachusetts, on October 5, 2007) following the short, presentations - each reported as a separate article in the prese ...
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Journal article · September 9, 2008
This book shows how you can use the method of constructal theory to design human-made systems in order to reduce trial and error and increase the system performance. ...
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Journal articleDesign with Constructal Theory · August 28, 2008
Design course on the universal principle of configurations in nature and engineering-the constructal law. Design with Constructal Theory offers a revolutionary new approach based on physics for understanding and predicting the designs that arise in nature ...
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Journal articleJournal of Applied Physics · July 10, 2008
Nature shows that fluids bathe the animal body as trees matched canopy to canopy. The entering streams invade the body as river deltas and the reconstituted streams sweep and exit the body as river basins. Why should this be so? Why is animal vascularizati ...
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Journal articleInternational Journal of Heat and Mass Transfer · April 1, 2008
The vascularization of smart materials with self-healing functionality requires the distribution of fluids continuously and uniformly throughout the material volume. This paper shows how to configure the architecture such that the single stream that flows ...
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Journal articleAdvanced Materials Research · January 1, 2008
Here we draw attention to the development of smart materials with embedded vasculatures that provide multiple functionality: volumetric cooling, self-healing, mechanical strength, etc. Vascularization is achieved by using tree-shaped (dendritic) and grid-s ...
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Journal articleASME International Mechanical Engineering Congress and Exposition Proceedings · January 1, 2008
In this paper we describe a new concept for vascularizing the flow architectures of compact devices. Vascularization is achieved by using tree-shaped (dendritic) flow passages on both sides of the heat transfer surface. For each side, we propose to use an ...
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Journal articleInternational Journal of Design and Nature · December 1, 2007
In this article we rely on constructal theory to show that the hierarchy of universities is rigid, and that the explanation lies in the nature of education (science, news, information) as a natural flow system that bathes the globe most effectively. The ar ...
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Journal articleJournal of Enhanced Heat Transfer · December 1, 2007
This paper reports on three-dimensional geometric optimization of heat sinks and cooling channels where the objective is to maximize the global thermal conductance (minimize the thermal resistance), subject to two global constraints: fixed total volume and ...
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Journal articlePhysica A Statistical Mechanics and Its Applications · October 15, 2007
We investigate the multi-scale structure of a tree network obtained by constructal theory and we propose a new geometrical framework to quantify deviations from scale invariance observed in many fields of physics and life sciences. We compare a constructal ...
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Journal articleJournal of Physics D Applied Physics · August 8, 2007
Grid-shaped and tree-shaped flow architectures are being generated for use in vascularized materials with multiple functionality (self-healing, self-cooling, etc), based on the principle of the constructal law of evolutionary increase of flow access throug ...
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Journal articleInternational Journal of Heat and Mass Transfer · August 1, 2007
The vascularization of smart materials with the property of localized self-cooling is investigated here on the basis of a simple configuration. A solid body (slab) is subjected to intense heat flux from one side; temperatures are controlled by pumping a co ...
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Journal articleMechanical Engineering · July 1, 2007
The views of Adrian Bejan about the principles of the Second Law of Thermodynamics, discovered by Sadi Carnot, are discussed. The principle defines that everything flows one way, from high to low, such as water flows through a pipe from high pressure to lo ...
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Journal articleJournal of Applied Physics · May 21, 2007
This article describes the generation of dendritic flow architectures that provide maximum side-to-side flow access, across a vascularized body. The flow architecture consists of trees that alternate with upside-down trees (a,b,a,b,). If in tree " a " the ...
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Journal articleJournal of Fluids Engineering Transactions of the ASME · May 1, 2007
Conditionally-sampled boundary layer data for an accelerating transitional boundary layer have been analyzed to calculate the entropy generation rate in the transition region. By weighing the nondimensional dissipation coefficient for the laminar-condition ...
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Journal articleApplied Thermal Engineering · March 1, 2007
This paper is an introduction to a new trend in the conceptual design of energy systems: the generation of flow configuration based on the "constructal" principle that the global performance is maximized by balancing and arranging the various flow resistan ...
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Journal articleInternational Journal of Heat and Mass Transfer · 2007
In hyperthermia cancer treatments, a crucial problem is keeping the temperature of the normal tissue surrounding the tumor below a certain threshold so as not to cause damage to the tissue. Thus, obtaining a temperature field of the entire treatment region ...
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Journal articleInternational Journal of Green Energy · January 1, 2007
Constructal theory is the thought that the generation of flow configurations is a phenomenon of physics. Flow configuration, such as the trees of river basins, lungs and city traffic unite the natural with the engineered, and the animate with the inanimate ...
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Journal articleHydrology and Earth System Sciences · January 1, 2007
This review article shows that the occurrence of macroscopic flow configuration is a universal natural phenomenon that can be explained and predicted on the basis of a principle of physics (the constructal law): "For a flow system to persist in time (to su ...
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Journal articleJournal of Physics D Applied Physics · December 21, 2006
In this paper we focus on the application of the constructal theory in predicting the dendritic solid structure. First we analyse the marginal stability criterion from the perspective of the constructal principle. Having as a guiding principle the construc ...
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Journal articleInternational Journal of Heat and Mass Transfer · December 1, 2006
In this paper, we optimize the performance of several classes of simple flow systems consisting of T- and Y-shaped assemblies of ducts, channels and streams. In each case, the objective is to identify the geometric configuration that maximizes performance ...
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Journal articleJournal of Applied Physics · December 1, 2006
Natural porous structures are heterogeneous with multiple scales that are distributed nonuniformly. Few large pores (fissures, channels, and cracks) are accompanied by numerous finer channels. Can this type of flow architecture be attributed to a principle ...
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Journal articleProceedings of the ASME Turbo Expo · November 14, 2006
Accurate transition onset modeling is a fundamental part of modern turbomachinery designs, where bypass transition is the dominant mechanism of transition to turbulence. Despite this situation a range of transition onset models exist primarily based upon b ...
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Journal articleInternational Journal of Heat and Mass Transfer · November 1, 2006
The paper reports the performance of balanced two-stream parallel flow heat exchangers, in which each stream flows as a tree network through its allotted space. The two trees are in parallel flow, and are arranged like two palms pressed against each other. ...
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Journal articleJournal of Applied Physics · October 9, 2006
In this paper we develop flow architectures for "vascularizing" smart materials that have self-healing capabilities. The flow architectures are configured as two trees matched canopy to canopy. A single stream flows through both trees and bathes every subv ...
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Journal articleNumerical Heat Transfer Part A Applications · October 1, 2006
In recent years there has been interest in research related to hyperthermia combined with radiation and cytotoxic drugs to enhance the killing of tumors. When heating the tumor tissue, the crucial problem is keeping the temperature of the normal tissue sur ...
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Journal articleJournal of Applied Physics · September 11, 2006
Constructal theory is the view that the generation of flow configuration is a physics phenomenon that can be based on a physics principle (the constructal law): "For a finite-size flow system to persist in time (to survive) its configuration must evolve in ...
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Journal articleInternational Journal of Thermal Sciences · September 1, 2006
In this paper we report experimentally the hydraulic and thermal behavior of a balanced counterflow heat exchanger in which each stream flows through a tree-shaped structure covering a circular area. The tree structure is the same on both sides of the heat ...
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Journal articleInternational Journal of Heat and Mass Transfer · August 1, 2006
This paper is a fundamental study of the effect of junction losses on the optimized geometry of tree-shaped flows. Several classes of flows are investigated systematically in a T-shaped construct with fixed internal and external size: laminar with non-negl ...
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Journal article · July 19, 2006
Abstract. This review article shows that the occurrence of macroscopic flow configuration is a universal natural phenomenon that can be explained and predicted on the basis of a principle of physics (the constructal law): "For a flow system to pers ...
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Journal articleInternational Journal of Heat and Mass Transfer · July 1, 2006
In this paper we rely on the constructal law of maximization of flow access in order to construct a theory of geometry generation (selection, evolution) during molten droplet impact. We show that immediately after impact the liquid spreads inviscidly as a ...
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Journal articleInternational Journal of Heat and Mass Transfer · July 1, 2006
Tree-shaped networks are now being considered as small-scale architectures for high-densities in electronics cooling and fuel cells design. This paper documents the optimization of tree-shaped inserts of high thermal conductivity. The new feature is the pr ...
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Journal articleInternational Journal of Heat and Mass Transfer · June 1, 2006
The constructal law states that every flow system evolves in time so that it develops the flow architecture that maximizes flow access under the constraints posed to the flow. Earlier applications of the constructal law recommended it as a self-standing la ...
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Journal articleJournal of Physics D Applied Physics · May 21, 2006
In this paper we propose a constructal approach to understanding and predicting the morphology of agglomerates of aerosol particles and also to the design of air-cleaning devices. We show that particle agglomeration begins in spherical shape and switches t ...
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Journal articleJournal of Applied Physics · May 15, 2006
In recent years there has been interest in research related to hyperthermia combined with radiation and cytotoxic drugs to enhance the killing of tumors. When heating the tumor tissue, the crucial problem is keeping the temperature of the normal tissue sur ...
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Journal articleInternational Journal of Heat and Mass Transfer · May 1, 2006
In this paper we optimize the performance of several classes of simple flow systems consisting of T- and Y-shaped assemblies of ducts, channels and streams. In each case, the objective is to identify the geometric configuration that maximizes performance s ...
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Journal articleInternational Journal of Engineering Education · February 13, 2006
This paper outlines a new 4th-year undergraduate course on the generation of system configuration (geometry, architecture, and drawing) during the maximization of performance of flow systems. The configuration is free to morph. Real systems are destined to ...
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Journal articleAmerican Society of Mechanical Engineers, Advanced Energy Systems Division (Publication) AES · 2006
This is a fundamental study of how to discover the optimal flow architecture to vascularize a volume so that fluid flow and function (e.g. cooling, sensing, maintenance, repair, healing) reaches every point of the material. The presentation is made by disc ...
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Journal articleThermal Science · 2006
This is a brief introduction to an engineering theory on the origin and generation of geometric form in all flow systems: the animate, the in animate and the engineered. The theory is named constructal, and is based on the thought that it is natura ...
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Journal articleEnergy · January 1, 2006
This paper describes the optimization of the distribution of heat transfer (cooling) during the process of gas compression. The coolant is a stream of cold liquid. There is a fundamental tradeoff between the savings in compressor power, which are due to di ...
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Journal articleJournal of Applied Physics · 2006
This is a fundamental study of how to vascularize a self-healing composite material so that healing fluid reaches all the crack sites that may occur randomly through the material. The network of channels is built into the material and is filled with pressu ...
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Journal articleEnergy · January 1, 2006
This paper reviews recent constructal-theory advances: the optimal distribution of discrete heat sources cooled by laminar natural convection. Three scenarios are investigated: (i) many small heat sources mounted on a vertical wall, (i) a few small finite- ...
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Journal articleJournal of Physics D: Applied Physics · 2006
This paper reports the development of optimal vascularization for supplying self-healing smart materials with liquid that fills and seals the cracks that may occur throughout their volume. The vascularization consists of two-dimensional grids of interconne ...
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Journal articleAmerican Scientist · January 1, 2006
A thermodynamic approach is used to predict the complex features of animal design. Evidence is given that if evolution were rewound, and if runners, swimmers and fliers appeared again, the process should consistently produce the same types of speeds, and s ...
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Journal articleProceedings of 8th Biennial ASME Conference on Engineering Systems Design and Analysis Esda2006 · January 1, 2006
A 2-d rectangular slab, internally cooled by circular tubes of different diameters, is used as a benchmark to perform a numerical thermal optimization procedure on a heat transfer configuration obtained by "constructal" considerations. Three different geom ...
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Journal articleThe Journal of experimental biology · January 2006
Biologists have treated the view that fundamental differences exist between running, flying and swimming as evident, because the forms of locomotion and the animals are so different: limbs and wings vs body undulations, neutrally buoyant vs weighted bodies ...
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Journal articleHeat Transfer Engineering · December 1, 2005
This paper presents a theoretical, numerical, and experimental study to investigate the possibility of optimizing the configuration (geometry) of underground heat exchangers for maximum heat transfer. The first part of the study identifies a novel fundamen ...
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Journal articleAmerican Society of Mechanical Engineers Advanced Energy Systems Division Publication AES · December 1, 2005
This paper reviews recent progress on constructal theory and design. The emphasis is on the development of multi-scale, nonuniformly distributed flow structures that offer increased compactness (e.g., heat transfer density). Examples are counterflow heat e ...
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Journal articleInternational Journal of Thermal Sciences · December 1, 2005
This paper reviews recent progress on constructal theory and design. The emphasis is on the development of multi-scale, nonuniformly distributed flow structures that offer increased compactness (e.g., heat transfer density). Examples are counterflow heat e ...
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Journal articleJournal of Applied Physics · November 15, 2005
In this paper, we demonstrate that asymmetry in fluid distribution tree networks emerges from power requirement minimization, under global volume constraint. We have discovered several levels of asymmetry in optimal trees: different pipe lengths at the sam ...
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Journal articleNumerical Heat Transfer Part A Applications · November 1, 2005
This article is about novel applications of computational heat transfer and fluid dynamics: the optimization and design of complex tree-shaped flow structures for cooling high-density heat-generating volumes (e.g., electronics). The focus is on computation ...
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Journal articleInternational Journal of Heat and Mass Transfer · October 1, 2005
This paper shows that in a space filled with assemblies of cylinders cooled by natural convection the heat transfer density can be increased progressively by the use of cylinders of several sizes, and the optimal placement of each cylinder in the assembly. ...
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Journal articleInternational Journal of Heat and Mass Transfer · October 1, 2005
This paper describes a structured procedure to optimize the internal structure (relative sizes, spacings), single cells thickness, and external shape (aspect ratios) of a polymer electrolyte membrane fuel cell (PEMFC) stack so that net power is maximized. ...
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Journal articleInternational Journal of Energy Research · June 10, 2005
This is a review of recent progress on constructal design made in two directions: multi-scale flow structures, and multi-objective design. The first direction is associated with the maximization of heat transfer rate density in a fixed volume in the limit ...
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Journal articleInternational Journal of Heat and Mass Transfer · June 1, 2005
This paper details the generation of multi-scale flow structure in a package with heat sources. The model is based on abandoning two common assumptions (1) the assumption that there are many channels (components) in the package, which is traditionally made ...
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Journal articleThe Journal of experimental biology · May 2005
The constructal law is the statement that for a flow system to persist in time it must evolve in such a way that it provides easier access to its currents. This is the law of configuration generation, or the law of design. The theoretical developments revi ...
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Journal articleInternational Journal of Heat and Mass Transfer · April 1, 2005
In this paper we use the constructal method to determine the optimal distribution and sizes of discrete heat sources in a vertical open channel cooled by natural convection. Two classes of geometries are considered: (i) heat sources with fixed size and fix ...
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Journal articleInternational Journal of Energy Research · March 25, 2005
The constructal law of generation of flow structure is used to predict the main features of global circulation and climate. The flow structure is the atmospheric and oceanic circulation. This feature is modelled as convection loops, and added to the earth ...
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Journal articleInternational Journal of Heat and Mass Transfer · March 1, 2005
This paper reports a new concept for maximizing heat transfer density in assemblies of cylinders in cross-flow: the use of cylinders of several sizes, and the optimal placement of each cylinder in the assembly. The heat transfer is by laminar forced convec ...
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Journal articleInternational Journal of Refrigeration · March 1, 2005
This paper explores the application of constructal design to tree-shaped networks for cold storage. The objective is the maximization of ice production per unit volume, for specified operating conditions (temperature difference, pressure drop, storage time ...
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Journal articleInternational Journal of Heat and Fluid Flow · February 1, 2005
In this paper we investigate a new design concept for generating multi-scale structures in natural convection with the objective of maximizing the heat transfer density, or the heat transfer rate per unit of volume. The flow volume is filled with vertical ...
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Journal article · January 1, 2005
This is a review of the main features of current activity in engineering thermodynamics research. It starts with the fundamentals of why processes and devices are ineficient: irreversibility, entropy generation (as distinct from the property entropy), exer ...
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Journal articleInternational Journal of Thermal Sciences · January 1, 2005
In this paper the optimization of fluid networks is based on the minimization of pumping power requirement. The total pipe network volume is constrained. It is shown that only in special cases the minimization of pumping power leads to the same architectur ...
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Journal articleInt. J. Exergy (Switzerland) · 2005
This paper outlines the place occupied by the constructual law in thermodynamics, and provides a vision of the future development of energy engineering as a transdisciplinary science of systems of systems. Natural and man-made flow systems do not exist in ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 2005
Dendritic flow architectures are being contemplated for thermal designs that provide high heat transfer densities for the cooling of electronics. Optimized tree networks maximize the flow access between one point (source, sink) and an infinity of points (l ...
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Journal articleASME 2005 3rd International Conference on Fuel Cell Science Engineering and Technology Fuelcell 2005 · January 1, 2005
This paper develops a mathematical model and a structured procedure to optimize the internal structure (relative sizes, spacings) and external shape (aspect ratios) of a unit PEM fuel cell so that net power is maximized. The optimization of flow geometry i ...
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Journal articleJournal of Heat Transfer · December 1, 2004
This paper completes the description of geometry optimization in stacks of parallel plates that generate heat. The spacing between plates, or the number of plates in a fixed volume, has been maximized in two limits: pure natural convection and pure forced ...
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Journal articleInternational Journal of Thermal Sciences · December 1, 2004
This paper shows that in a space filled with heat generating parallel plates and laminar forced convection, the heat transfer density can be increased beyond the level known for parallel plates with optimal spacing. The technique consists of inserting in e ...
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Journal articleJournal of Applied Physics · November 15, 2004
We consider the problem of cooling a two-dimensional heat generating conducting volume with one heat sink, such that the smallest features of the internal structure are so small that the conventional description of conduction breaks down. The effective the ...
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Journal articleInternational Journal of Heat and Mass Transfer · September 1, 2004
This paper introduces a model and a structured procedure to optimize the internal structure (relative sizes, spacings) and external shape (aspect ratios) of a unit PEM fuel cell so that net power is maximized. The optimization of flow geometry is conducted ...
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Journal articleInternational Journal of Heat and Mass Transfer · September 1, 2004
This paper considers the fundamental problem of how to shape rectangular high-conductivity inserts (fins) that are mounted on the rim of and protrude into a disc-shaped body that generates heat. The objective is to minimize the global thermal resistance by ...
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Journal articleJournal of Applied Physics · August 1, 2004
The conceptual design and performance of balanced two-stream counterflow heat exchangers was discussed. The relationships between effectiveness and number of heat transfer units for several tree-counterflow configurations were developed. It was found that ...
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Journal articleInternational Journal of Heat and Mass Transfer · July 1, 2004
This paper addresses the fundamental problem of maximizing the heat transfer rate density in a fixed volume in the limit of decreasing length scales. In this limit boundary layers disappear, optimized channels are no longer slender, and existing results fo ...
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Journal articleMicroscale Thermophysical Engineering · July 1, 2004
The objective of the present article is to compare previous experimental data of Gao et al. to the predictions of Bejan and Sciubba's analysis on the optimal spacing for maximum heat transfer from a package of parallel plates. Experimental investigations o ...
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Journal articleInternational Journal of Heat and Mass Transfer · July 1, 2004
In this paper we develop an analytical and graphical formulation of the constructal law of maximization of flow access in systems with heat and fluid flow irreversibilities and freedom to change configuration. The flow system has global performance (e.g., ...
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Journal articleInternational Journal of Heat and Mass Transfer · July 1, 2004
This paper outlines a new direction for fundamental heat transfer: a multidisciplinary approach (combined heat transfer and strength of materials) in the conceptual design of structures that have two functions, mechanical strength and resistance (survival) ...
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Journal articleInternational Journal of Heat and Mass Transfer · June 1, 2004
In this paper we consider the optimization of the shape of a cavity that intrudes into a solid conducting wall. This intrusion may be regarded as a "negative fin", i.e., the outside-in version of a conductive fin the shape of which is to be optimized. The ...
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Journal articleInternational Journal of Thermal Sciences · May 1, 2004
This paper presents a three-dimensional numerical and experimental geometric optimization study to maximize the total heat transfer rate between a bundle of finned tubes in a given volume and external flow, for staggered arrangements of circular and ellipt ...
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Journal articleInternational Journal of Thermal Sciences · April 1, 2004
This paper addresses the fundamental problem of optimizing the geometry of an electromagnet by maximizing at the same time its magnetic performance and thermal performance. The solenoid has a cylindrical shape and a uniform current density. Cooling discs m ...
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Journal articleInternational Journal of Energy Research · March 25, 2004
This paper shows that the internal structure (relative sizes, spacings) of a fuel cell can be optimized so that performance is maximized at the global level. The optimization of flow geometry begins at the smallest (elemental) level, where the fuel cell is ...
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Journal articleNumerical Heat Transfer Part A Applications · January 16, 2004
In this article we show numerically that the entire flow geometry of a vertical diverging or converging channel with laminar natural convection can be optimized for maximal heat transfer rate density (total heat transfer rate per unit of flow system volume ...
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Journal articleInternational Journal of Exergy · January 1, 2004
Constructal theory is applied to the cooling of a disc where heat is uniformly generated. The disc size and the total volume occupied by the ducts (distributing the flow from the centre to the periphery) are constrained. It is shown that when the objective ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 2004
This work presents a numerical and experimental geometric optimization study to maximize the total heat transfer rate between a bundle of finned or non-finned tubes in a given volume and a given external flow both for circular and elliptic arrangements, fo ...
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Journal articleJ. Non-Equilib. Thermodyn. (Germany) · 2004
The concept of thermodynamic efficiency (ratio of real cycle efficiency by Carnot efficiency) is well-known. The concept of numbers of entropy-production and of exergy-loss proposed by A. Bejan are also known, but rarely used. The present study firstly evi ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 2004
This paper documents the fundamental relation between the maximization of global performance and the maleable (morphing) architecture of a flow system with global constraints. The example is the coaxial two-stream heat exchanger with flow through a porous ...
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Journal articleJ. Non-Equilib. Thermodyn. (Germany) · 2004
The radial flow between two parallel circular disks is investigated with the aim to determine the optimum convective heat transfer conditions at the external disk surfaces in order to minimize the intrinsic irreversibilities. A general situation is conside ...
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Journal articleAmerican Society of Mechanical Engineers, Advanced Energy Systems Division (Publication) AES · 2004
This paper brings to the attention of the AES community our experience with developing and trying out a new course that focuses on the generation of system configuration (geometry, architecture, and drawing) during the optimization of performance. The conf ...
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Journal articleInternational Journal of Heat and Technology · January 1, 2004
Tree-shaped networks provide maximum access for currents flowing between discrete points (sources, sinks) and infinite numbers of points (lines, areas, volumes). This is a growing area of research. The first part of this paper reviews the main features and ...
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Journal articleInternational Journal of Heat and Technology · January 1, 2004
This paper reviews the progress made on the development of constructal tree networks: step by step improvements in global performance (e.g., global flow resistance) subject to global constraints (e.g., size of flow territory, total tube volume). This leads ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 2004
This paper is an application of the constructal method to the discovery of the optimal distribution of discrete heat sources cooled by laminar natural convection. The global objective is to maximize the global conductance between the wall and the fluid, or ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 2004
In this paper constructal theory is applied to the fundamental problem of how to arrange discrete heat sources on a wall cooled by forced convection. The global objective is to maximize the conductance between the discrete heated wall and the fluid. This i ...
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Journal articleProceedings of the ASME Heat Transfer Fluids Engineering Summer Conference 2004 Ht FED 2004 · January 1, 2004
The present paper is a review of a new conceptual design for the maximization of heat transfer density (i.e., heat transfer rate per unit of volume) in channels installed in a fixed volume. The volume is filled optimally with parallel equidistant heated bl ...
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Journal articleASME 2004 2nd International Conference on Fuel Cell Science Engineering and Technology Fuelcell 2004 · January 1, 2004
The hydrogen economy is a possible alternative to the current oil based global economy. The technology to build and operate fuel cells is well advanced. However, cost is the reason why fuel cells are not being installed wherever there is a need for more po ...
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Journal articleInstitute of Physics Conference Series · December 1, 2003
Flows through porous media have been studied extensively during the past two decades. This lecture reviews an emerging body of work centered on the idea that the porous structure (spacings, arrangements) can be optimized such that the global flow system ac ...
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Journal articleInternational Journal of Thermal Sciences · October 1, 2003
This paper shows that the temporal and spatial structure of adsorption-desorption processes can be optimized for maximal packing of mass transfer into a fixed space, and for minimal overall pumping power. In the first part of the paper, simple models demon ...
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Journal articleInternational Journal of Thermal Sciences · September 1, 2003
This paper shows analytically and numerically how an originally uniform flow structure transforms itself into a nonuniform one when the objective is to minimize global flow losses. The flow connects one point (source, sink) to a number of points (sinks, so ...
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Journal articleInternational Journal of Energy Research · August 1, 2003
This article outlines the basic rules and promise of two of the simplest methods for solving problems of convection in porous media. First, scale analysis is the method that produces order-of-magnitude results and trends (scaling laws) for concrete and app ...
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Journal articleInternational Journal of Heat and Mass Transfer · July 1, 2003
This paper documents the strong relation that exists between the changing architecture of a complex flow system and the maximization of global performance under constraints. The system is a surface with uniform heating per unit area, which is cooled by a n ...
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Journal articleInternational Journal of Energy Research · July 1, 2003
This paper reviews some of the most basic flows that effect the dispersal of heat and mass in environmental configurations. Two important classes of environmental flows are discussed: free turbulent flows (shear layers, jets, plumes and wakes) and free flo ...
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Journal articleInternational Journal of Energy Research · June 25, 2003
In this paper, we review the fundamental problem of how to design a flow path with minimum overall resistance between one point (O) and many points situated equidistantly on a circle centred at O. This is a fundamental problem in energy engineering: the di ...
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Journal articleEnergy Conversion and Management · May 1, 2003
This paper describes an integral (macroscopic) approach to the evaluation and maximization of performance in the design of networks for the distribution of electric power. The method recognizes the hierarchical structure of tree shaped networks and account ...
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Journal articleEnergy Conversion and Management · April 1, 2003
In this paper, we extend to the design of electric power distribution networks the constructal method of deducing the multiple dimensions of the network from the maximization of global system performance. Unlike earlier constructal designs of tree shaped n ...
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Journal articleInternational Journal of Thermal Sciences · April 1, 2003
In this paper we show that the sizes (weights) of heat and fluid flow systems that function on board vehicles such as aircraft can be derived from the maximization of overall (system level) performance. The total weight of the aircraft dictates its fuel re ...
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Journal articleInternational Journal of Energy Research · March 25, 2003
This lecture reviews a series of recent results based on the geometric minimization of the resistance to flow between one point (source, sink) and a volume or an area (an infinity of points). Optimization is achieved by varying the geometric features of th ...
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Journal articleJournal of Aircraft · January 1, 2003
Attention is drawn to constructal theory and design, which relies on global maximization of performance in the pursuit of flow system architecture. Exergy analysis establishes the theoretical performance limit. Thermodynamic optimization (or entropy genera ...
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Journal articleEnergy · January 1, 2003
This paper addresses two basic issues in the thermodynamic optimization of environmental control systems (ECS) for aircraft: realistic limits for the minimal power requirement, and design features that facilitate operation at minimal power consumption. Fou ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 2003
This paper is a proposal to design flow structures with maximal heat transfer rate per unit volume, by shaping each duct so that it fits optimally on the body of the convective flow. Optimally shaped ducts can be assembled into larger constructs. Two examp ...
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Journal articleJournal of Electronic Packaging · January 1, 2003
This article is a principle-based review of a growing body of fundamental research that documents the opportunity for optimizing geometrically the cooling of spaces (e.g., electronics packages) that generate heat volumetrically. The chief result of geometr ...
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Journal articleActa Mechanica · January 1, 2003
This paper presents a new concept for generating the multi-scale structure of a finite-size flow system that has maximum heat transfer density-maximum heat transfer rate installed in a fixed volume. Laminar forced convection and parallel isothermal blades ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 2003
In this paper we develop the optimal tree-shaped flow paths for cooling a disc-shaped body by convection. Heat is generated uniformly over the disc area. The coolant enters through the center of the disc, and exits through ports positioned equidistantly al ...
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Journal articleAmerican Society of Mechanical Engineers Advanced Energy Systems Division Publication AES · January 1, 2003
In this paper we develop an analytical and graphical formulation of the constructal law of maximization of flow access in systems with heat and fluid flow irreversibilities and freedom to change configuration. The flow system has global objective (e.g., mi ...
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Journal articleInternational Conference on Microchannels and Minichannels · January 1, 2003
Experimental investigations of the flow and the associated heat transfer were conducted in two-dimensional microchannels in order to test possible size effects on the laws of hydrodynamics and heat transfer and to infer optimal conditions of use from the m ...
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Journal articleDesign and Nature · December 1, 2002
This paper draws attention to the 1996 constructal theory of the generation of geometric form in flow systems. Flow architecture can be reasoned on the basis of principle: the maximization of global performance subject to finite-size constraints. One examp ...
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Journal articleJournal of Heat Transfer · December 1, 2002
This paper considers the fundamental problem of optimizing the geometry of the interface between two conductive bodies, with the objective of minimizing the thermal resistance. The interface geometry is free to change. For simplicity, the geometry is assum ...
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Journal articleInternational Journal of Heat and Mass Transfer · December 1, 2002
In this paper we consider the fundamental problem of how to design a flow path with minimum overall resistance between one point (O) and many points situated equidistantly on a circle centered at O. The flow may proceed in either direction, from the center ...
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Journal articleInternational Journal of Heat and Mass Transfer · September 9, 2002
This paper describes the constructal route to the conceptual design of a two-stream heat exchanger with maximal heat transfer rate per unit volume. The flow structure has multiple scales. The smallest (elemental) scale consists of parallel-plates channels ...
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Journal articleRevista de Engenharia Térmica · June 30, 2002
This is a review of two new and important developments in thermal science. First, there exist fundamental optima in the constitution and operation of flow (nonequilibrium) systems, man-made and natural. These optima can be identified based on the s ...
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Journal articleInternational Journal of Energy Research · June 10, 2002
This paper outlines the fundamentals of the methods of exergy analysis and entropy generation minimization (or thermodynamic optimization-the minimization of exergy destruction). The paper begins with a review of the concept of irreversibility, entropy gen ...
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Journal articleInternational Journal of Heat and Mass Transfer · May 27, 2002
This paper addresses the fundamental problem of optimizing the internal structure of a vertical wall that must meet two requirements, thermal insulation and mechanical strength. The wall is a composite of solid material (e.g., brick) and parallel air caver ...
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Journal articleInternational Journal of Heat and Mass Transfer · May 27, 2002
This paper outlines a direct route to the construction of effective tree-shaped flow structures. Dendritic flow structures dominate the design of natural and engineered flow systems, especially in thermal and fluid systems. The starting point is the optimi ...
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Journal articleInternational Journal of Heat and Mass Transfer · February 18, 2002
This paper describes a hierarchical strategy to developing the optimal internal structure of a round heat-generating body cooled at its center with the help of optimally distributed inserts of high-conductivity material. The sequence begins with optimizing ...
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Journal articleASME International Mechanical Engineering Congress and Exposition Proceedings · January 1, 2002
This paper reports two new advances on constructal design, or the generation of flow architecture in the pursuit of global thermodynamic performance subject to constraints. This is thermodynamic optimization with an emphasis on its product: flow geometry, ...
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Journal articleInternational Journal of Heat and Mass Transfer · December 18, 2001
This paper describes the optimization of a tree-shaped system of insulated pipes for the distribution of a stream of hot water over an area. The area is covered uniformly by users who must receive the same flow rate of hot water. The network of pipes is de ...
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Journal articleStrojniski Vestnik Journal of Mechanical Engineering · December 1, 2001
This lecture outlines the basis for the entropy generation minimization method, and a series of key applications in power generation, refrigeration, and exergy conservation. The lecture begins with a review of the concept of irreversibility, entropy genera ...
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Journal articleInternational Journal of Heat and Fluid Flow · December 1, 2001
This paper shows that the main geometric features of a flow component can be deduced from the thermodynamic optimization of the global performance of the largest flow system that incorporates the component. This approach represents a departure from the usu ...
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Journal articleJournal of Heat Transfer · December 1, 2001
This paper addresses the fundamental problem of how to facilitate the flow of heat across a conducting slab heated from one side. Available for distribution through the system is a small amount of high-conductivity material. The constructal method consists ...
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Journal articleInternational Journal of Energy Research · October 25, 2001
In this paper, we show that many features of a heat transfer installation can be deduced from the maximization of the global performance of the greater system that employs the installation. The heat transfer installation is a series of two cross-flow heat ...
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Journal articleInternational Journal of Heat and Mass Transfer · September 18, 2001
Constructal tree designs are hierarchical high-conductivity paths that minimize the global resistance between an entire volume and one point. In past work, the structure was optimized as a sequence of building blocks (volume sizes), which started with the ...
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Journal articleInternational Journal of Heat and Mass Transfer · August 21, 2001
In this paper we propose to optimize the geometric configuration of a component by maximizing the global thermodynamic performance of the much larger system that contains the component. This "integrative" approach departs from current thermodynamic optimiz ...
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Journal articleJournal of Heat Transfer · August 1, 2001
This paper documents the process of determining the internal geometric configuration of a component by optimizing the global performance of the installation that uses the component. The example chosen is the crossflow heat exchanger used in the environment ...
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Journal articleRevista de Engenharia Térmica · June 30, 2001
This is a review of two new and important developments in thermal science. First, there exist fundamental optima in the constitution and operation of flow (nonequilibrium) systems, man-made and natural. These optima can be identified based on the ...
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Journal articleInternational Journal of Heat and Mass Transfer · June 19, 2001
This paper is a study of the optimal geometric layout of schemes for distributing hot water uniformly over an area. Constrained are the amount of insulation material, the volume of all the pipes, and the amount of pipe wall material. Unknown are the distri ...
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Journal articleInternational Journal of Energy Research · May 1, 2001
The solution to the problem of maximizing the extraction of exergy from a stream of hot gas showed that the hot stream must be cooled in a counterflow heat exchanger with optimal imbalance of capacity rates, i.e. with an optimal capacity rate on the cold s ...
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Journal articleJournal of Heat Transfer · April 1, 2001
This paper addresses the fundamental problem of maximizing the thermal contact between an entire heat-generating volume and a pulsating stream of coolant that bathes the volume. The coolant flows through an array of round and equidistant tubes. Two laminar ...
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Journal articleJournal of Non Equilibrium Thermodynamics · January 1, 2001
Recent developments in thermodynamic optimization are reviewed by focusing on the generation of optimal geometric form (shape, structure, topology) in flow systems. The flow configuration is free to vary. The principle that generates geometric form is the ...
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Journal articleEnergy · January 1, 2001
This paper shows that the internal geometric configuration of a component can be deduced by optimizing the global performance of the installation that uses the component. The example chosen is the counterflow heat exchanger that serves as condenser in a va ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 2001
Two parallel fluid streams in counterflow and in close thermal contact convect an energy current longitudinally, in the direction of the warmer stream. This paper describes the flow of convective heat currents through two identical tree networks superimpos ...
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Journal article8th Symposium on Multidisciplinary Analysis and Optimization · December 1, 2000
This paper draws attention to an emerging body of work that relies on exergy analysis and thermodynamic optimization in the pursuit of flow system architecture. Exergy analysis establishes the theoretical performance limit. Thermodynamic optimization (or e ...
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Journal articleInternational Journal of Heat and Mass Transfer · September 1, 2000
This paper describes the geometric optimization of the internal structure of a volume that generates heat at every point and is cooled by a single stream. According to the constructal method, the optimization of the cooling design is organized in a sequenc ...
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Journal articleEnergy Conversion and Management · September 1, 2000
This paper extends to economics the constructal theory of generation of shape and structure in natural flow systems that connect one point to a finite size area or volume. It is shown that by invoking the principle of cost minimization in the transport of ...
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Journal articleJournal of Heat Transfer · August 1, 2000
This lecture reviews a relatively recent body of heat transfer work that bases on a deterministic (constructal) principle the occurrence of geometric form in systems with internal flows. The same principle of global optimization subject to constraints allo ...
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Journal articleInternational Journal of Heat and Mass Transfer · June 15, 2000
This paper reports the geometric (constructal) optimization of T-shaped fin assemblies, where the objective is to maximize the global thermal conductance of the assembly, subject to total volume and fin-material constraints. Assemblies of plate fins and cy ...
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Journal articleEnergy · January 1, 2000
The optimum thermodynamic match between two streams at different temperatures is determined by maximizing the power generation (or minimizing the entropy generation) associated solely with the stream-to-stream interaction. Each stream experiences a change ...
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Journal articleApplied Energy · January 1, 2000
This paper extends to economics of the constructal theory of generation of shape and structure in natural flow systems that connect one point to a finite size area or volume. By invoking the principle of cost minimization in the transport of goods between ...
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Journal articleInternational Journal of Heat and Technology · January 1, 2000
This review draws attention to an emerging body of work that relies on global thermodynamic optimization in the pursuit of flow system architecture. Exergy analysis establishes the theoretical performance limit. Thermodynamic optimization (or entropy gener ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 2000
This paper considers the basic thermodynamic optimization problem of extracting the most power from a stream of hot exhaust when the contact heat transfer area is fixed. It shows that when the receiving (cold) stream boils in the counterflow heat exchanger ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 2000
In this paper, we extend the constructal optimization method to cylindrical assemblies of pin fins. The assembly is arranged as a tree with one stem and many radial branches. The optimization consists of maximizing the global conductance subject to fixed t ...
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Journal articleInternational Journal of Energy Research · 2000
This paper shows that the main architectural features of a counterflow heat exchanger can be determined based on thermodynamic optimization subject to volume constraint. It is assumed that the channels are formed by parallel plates, the two fluids are idea ...
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Journal articleApplied Energy · 2000
This paper extends to economics of the constructal theory of generation of shape and structure in natural flow systems that connect one point to a finite size area or volume. By invoking the principle of cost minimization in the transport of goods between ...
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Journal articleInternational Journal of Thermal Sciences · January 1, 2000
This paper presents a series of examples in which the global performance of flow systems is optimized subject to global constraints. The flow systems are assemblies of ducts, channels and streams shaped as T5, Y5 and crosses. In pure ...
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Journal articleJournal of Applied Physics · December 15, 1999
This article extends to three-dimensional heat flow the constructal method of minimizing geometrically the thermal resistance between a heat-generating volume and one point. Optimized is the geometry of each volume element, and the shape and distribution o ...
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Journal articleAmerican Society of Mechanical Engineers Advanced Energy Systems Division Publication AES · December 1, 1999
This paper outlines a newly emerging body of work that relies on exergy analysis and thermodynamic optimization in the design of energy systems for modern aircraft. Exergy analysis establishes the theoretical performance limit. The minimization of exergy d ...
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Journal articleInternational Journal of Heat and Mass Transfer · October 28, 1999
This paper considers the basic thermodynamic optimization problem of extracting the most power from a stream of hot exhaust when the contact heat transfer area is fixed. It shows that when the receiving (cold) stream boils in the counterflow heat exchanger ...
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Journal articleInternational Journal of Energy Research · October 25, 1999
This paper explores alternatives to the usual thermodynamic optimization formulation, where the thermodynamic performance of a system is improved subject to physical size constraints (e.g., entropy generation minimization). The alternative is to minimize t ...
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Journal articleInternational Journal of Heat and Mass Transfer · October 1, 1999
This paper extends to three dimensions and to convective heat transfer the constructal method of minimizing the thermal resistance between a volume and one point. In the first part of the paper, the heat flow mechanism is conduction, and the heat generatin ...
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Journal articleJournal of Applied Physics · July 15, 1999
In this article we show that the global thermal resistance to flow between a volume and one point can be reduced to unprecedented levels by shaping the external boundary of each volume element. This degree of freedom is optimized, next to internal features ...
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Journal articleInternational Journal of Heat and Mass Transfer · May 11, 1999
This paper documents two methods of improving the performance of volume-to-point tree networks for two-dimensional heat conduction. These improvements are offered relative to the design produced by the constructal method, in which optimized volume elements ...
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Journal articleEnergy · January 1, 1999
The Ranque-Hilsch vortex tube splits a single high pressure stream of gas into cold and warm streams. Simple models for the vortex tube combined with regenerative precooling are given from which an optimization can be undertaken. Two such optimizations are ...
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Journal articleJournal of Heat Transfer · January 1, 1999
This paper extends to the field of convective heat transfer the constructal theory of optimizing the access of a current that flows between one point and a finite-size volume, when the volume size is constrained. The volume is bathed by a uniform stream. A ...
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Journal articleEnergy · January 1, 1999
The first ever NATO Advanced Study Institute devoted to 'Thermodynamics and the Optimization of Complex Energy Systems' was held in July 1998 in Neptun, Romania. The ASI unified the field by bringing together leading researchers from engineering and physic ...
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Journal articleJournal of Heat Transfer · January 1, 1999
This paper shows that the geometry of the heat flow path between a volume and one point can be optimized in two fundamentally different ways. In the "growth" method of the original constructal theory the structure is optimized starting from the smallest vo ...
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Journal articleInternational Journal of Thermal Sciences · January 1, 1999
The constructal theory of the origin of geometrical form in natural flow (open) systems began with the discovery that, contrary to the established view, the tree network can be deduced from a single principle: the geometric minimization of resistance in vo ...
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Journal articleInternational Journal of Thermal Sciences · January 1, 1999
This is a theoretical and experimental study of the time-optimisation of condensation on a vertical wall when the film is removed periodically by a mechanical device. The objective is to fine-tune the periodic process so that the production of condensate a ...
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Journal articleJournal of Porous Media · January 1, 1999
This article reports a numerical study of the geometric minimization of the resistance to Darcy flow between a finite-size volume and one point. The volume is two dimensional and contains materials with several permeabilities. The optimization starts with ...
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Journal articleAmerican Society of Mechanical Engineers Heat Transfer Division Publication HTD · December 1, 1998
In this paper, "constructal theory" is used to predict the formation of geometric shape and structure in finite-size fluid systems subjected to heating from below. Two classes of systems are considered: (1) single-phase fluid layers and (2) fully developed ...
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Journal articleJournal of Applied Physics · September 15, 1998
This paper shows that the time needed to discharge a volume to a concentrated sink can be minimized by making appropriate changes in the geometry of the flow path. The time-dependent flow of heat between a volume and one point is chosen for illustration, h ...
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Journal articlePhysica A Statistical Mechanics and Its Applications · June 15, 1998
The geometric form of the tree network is deduced from a single mechanism. The discovery that the shape of a heat-generating volume can be optimized to minimize the thermal resistance between the volume and a point heat sink, is used to solve the kinematic ...
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Journal articleJournal of Heat Transfer · January 1, 1998
This paper extends to three-dimensional heat conduction the geometric "constructal" method of minimizing the overall thermal resistance between a finite-size volume and a small heat sink. The volume contains (i) low-conductivity material that generates hea ...
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Journal articleEnergy · January 1, 1998
Exergy analysis is applied to sudden thermal interaction between a molten metal (mm) and water (mw). The melt experiences cooling, solidification and subcooling. The water is pressurized at constant volume. It is found that the exerge ...
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Journal articleJournal of Solar Energy Engineering Transactions of the ASME · January 1, 1998
This note addresses the current debate on the correctness of power plant models and analyses of the type published by Curzon and Ahlborn (1975) among others. Such models are based on the highly questionable assumption that the heat input is freely availabl ...
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Journal articleNumerical Heat Transfer Part A Applications · January 1, 1998
This article describes numerically the time evolution of an expanding mixture of hot spherical particles, steam, and water. It is assumed that at time t = 0 the mixture components are distributed uniformly through Ike mixture volume. The mixture expands ag ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1998
This paper reports the solution to the fundamental problem of how to maximize the mechanical power extracted from a hot single-phase stream when the total heat transfer area bathed by the stream is constrained. It is shown that the optimization has two deg ...
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Journal articleRevue Generale De Thermique · January 1, 1998
This is a review of recent engineering developments in thermodynamic optimization, which shed light on a universal design principle that accounts for macroscopic organization in nature. It is shown that the optimal performance of a finite-size system with ...
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Journal articleFractals · January 1, 1998
This paper shows that the dendritic patterns formed by low-resistance channels in a river drainage basin are reproducible and can be deduced from a single principle that acts at every step in the development of the pattern: the constrained minimization of ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1998
The constructal theory of the origin of geometrical form in natural flow systems is used to predict the formation of crack patterns in solids subjected to volumetric cooling by convection. The approach is purely theoretical (deterministic), because it star ...
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Journal articleJournal of Heat Transfer · January 1, 1998
In this paper "constructal theory" is used to predict the formation of geometric shape and structure in finite-size fluid systems subjected to heating from below. Two classes of system are considered as tests: (i) single-phase fluid layers, and (ii) porous ...
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Journal articleJournal of Energy Resources Technology Transactions of the ASME · January 1, 1998
In this paper we show that the thermodynamic performance of a gas turbine power plant can he optimized by adjusting the flow rate and the distribution of pressure losses along the flow path. Specifically, we show that the power output has a maximum with re ...
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Journal articleEnergy Conversion and Management · January 1, 1998
This is a review of recent theoretical developments toward predicting macroscopic organization (the occurrence of shape and structure) in natural flow systems, animate and inanimate. The starting point is the question of how to optimize the access between ...
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Journal articleAmerican Society of Mechanical Engineers Advanced Energy Systems Division Publication AES · December 1, 1997
This paper outlines a series of recent developments that provide a theoretical basis for the formation of shape and structure in nonequilibrium (flow) systems subjected to overall constraints. It is shown that geometrical form can be deduced from a single ...
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Journal articleMechanical Engineering · October 1, 1997
Engineers simultaneously applied the principles of thermodynamics, fluid mechanics, and heat and mass transfer to construct models that account for the inherent irreversibility of processes executed by a system, natural or man-made, and its components. Thi ...
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Journal articleJournal of Applied Physics · July 1, 1997
This paper addresses the fundamental problem of how to connect a heat generating volume to a point heat sink by using a finite amount of high-conductivity material that can be distributed through the volume. The problem is one of optimizing the access (or ...
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Journal articleJournal of Heat Transfer · January 1, 1997
This paper describes an experimental and theoretical study of the periodic on and off heating of water on a horizontal surface. The heat transfer is effected by natural convection and isolated bubbles. The experiments cover the heat flux range 33-154 kW/m< ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1997
This paper reports the results of an experimental and numerical study of the optimal geometric arrangement of staggered parallel plates in a fixed volume with forced convection heat transfer. The objective of the geometric optimization effort is to maximiz ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1997
This paper develops a solution to the fundamental problem of how to collect and 'channel' to one point the heat generated volumetrically in a low conductivity volume of given size. The amount of high conductivity material that is available for building cha ...
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Journal articleRevue Generale De Thermique · January 1, 1997
The 'constructal theory' of formation of structure in nature is extended to fluid-flow systems. The fluid flow path between one point and a finite-size volume (an infinite number of points) is optimized by minimizing the overall flow resistance when the fl ...
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Journal articleFractals · January 1, 1997
The function of many natural flow systems is to connect by a fluid flow a finite-size volume and one point. This paper outlines a strategy for constructing the architecture of the volume-to-point path such that the flow resistance is minimal (constructal t ...
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Journal articleEnergy · January 1, 1997
When an amount of high-temperature molten material is suddenly and finely mixed within a body of liquid water, the ensuing mixture expands because of the volumetric generation of steam. At the same time, the expanding mixture is accelerated away from the s ...
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Journal articleJournal of Heat Transfer · January 1, 1997
This paper documents the geometric optimization of an assembly of staggered vertical plates that are installed in a fixed volume. The heat transfer is by laminar natural convection. The objective is to maximize the overall thermal conductance between the a ...
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Journal articleEnergy · January 1, 1997
We address the fundamental problem of determining the optimal history (regime of operation) of a battery so that the work output is maximum. The essential features of the problem are: (i) the life of the battery is constrained, (ii) the battery has an inte ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1997
This paper shows that thermodynamic optimization provides a common theoretical basis for the existence of the finely tuned frequencies of pulsating processes of animals. In respiration and circulation, the minimization of mechanical power consumption subje ...
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Journal articleJournal of Applied Physics · 1997
This paper addresses the fundamental problem of how to connect a heat generating volume to a point heat sink by using a finite amount of high-conductivity material that can be distributed through the volume. The problem is one of optimizing the access (or ...
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Journal articleJournal of Applied Physics · February 1, 1996
Entropy generation minimization (finite time thermodynamics, or thermodynamic optimization) is the method that combines into simple models the most basic concepts of heat transfer, fluid mechanics, and thermodynamics. These simple models are used in the op ...
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Journal articleJournal of Advanced Transportation · January 1, 1996
This paper outlines a completely deterministic("constructal") theory of why quasi-similar street patterns exist, how they form, and how they grow in time. The function of the street network is to connect a finite area to a single destination point. The new ...
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Journal articleJournal of Solar Energy Engineering Transactions of the ASME · January 1, 1996
This paper describes the thermodynamic optimization of a class of refrigerators without work input, which are driven by heat transfer from a solar collector. The model consists of a finite-size solar collector with heat loss to the ambient, and a refrigera ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1996
This is an experimental, numerical and analytical study of the optimal spacing between cylinders in cross-flow forced convection. The cylinder array occupies a fixed volume and is exposed to a free stream of given velocity and temperature. The optimal cyli ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1996
This paper extends to electrical machines the thermodynamics and heat transfer optimization approach that has been developed for heat engines. Four models of thermodynamically irreversible electrical motors with heat transfer to the ambient are proposed an ...
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Journal articleChemical Engineering Science · January 1, 1996
A swarm is a temporary structure formed when several thousand honey bees leave their hive and settle on some object such as the branch of a tree. They remain in this position until a suitable site for a new home is located by the scout bees. A continuum mo ...
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Journal articleJournal of Heat Transfer · January 1, 1996
This is an experimental numerical and theoretical study of the heat transfer on a pin-finned plate exposed to an impinging air stream. The pin fins are aligned with the air approach velocity. The base plate and the fin cross section are square. It is demon ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1996
This is an experimental and numerical study of natural convection and forced convection air cooling of plate finned heat sinks. The study documents quantitatively two effects: (1) the orientation of the fin array relative to the gravitational field in natu ...
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Journal articleNumerical Heat Transfer Part A Applications · January 1, 1996
This article presents a numerical study of the thermal and fluid flow interaction driven by the sudden contact between saturated liquid water (373 K) and a hot (2300 K) spherical or plane surface. It is shown that under these conditions the sudden contact ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1996
This paper describes several fundamental trade offs that govern the optimization of cooling techniques for heat generating electric devices. Five basic cooling configurations are optimized. It is shown that in forced air cooling above room temperature the ...
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Journal articleAmerican Journal of Physics · January 1, 1996
Chambadal, Novikov, Curzon and Ahlborn have shown that the efficiency of an irreversible heat engine at maximum power output is 1-(TL/TH)1/2. This article describes several heat engine models in which the same efficiency fo ...
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Journal articleInternational Journal of Heat and Fluid Flow · January 1, 1996
This is a study of a fundamental problem in electronic cooling; namely, conduction in a two-dimensional (2-D) domain cooled by one or more streams that make one or more passes. The fundamental objective is to determine the relation between the chosen cooli ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1996
The heat transfer principle of power maximization in power plants with heat transfer irreversibilities is extended to fluid flow. It is shown that when a stream flows between two pressure reservoirs (P1 > P2) across linear flow resist ...
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Journal articleJournal of Energy Resources Technology Transactions of the ASME · January 1, 1996
It is shown that to maximize the power output of a power plant is equivalent to minimizing the total entropy generation rate associated with the power plant. This equivalence is illustrated by using two of the oldest and simplest models of power plants wit ...
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Journal articleundefined · January 1, 1995
Reflecting real-life thermal engineering, this comprehensive text takes an interdisciplinary approach to the subject of heat transfer. The author stresses the relationship to other engineering disciplines, such as thermodynamics and fluid mechanics, and th ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1995
The heat transfer, friction and mechanical (elastic) interaction between an external laminar flow and a solid surface covered by a layer of fibers is investigated numerically. The flow is initially perpendicular to the surface, and the fibers can bend. The ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1995
In this paper we show that the production of ice by convection cooling followed by contact melting can be maximized by properly selecting the frequency of the intermittent freezing and removal cycle. In the first part of the paper, this principle is illust ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1995
This paper reports the thermodynamic optimization (or entropy generation minimization) of a heat-driven refrigeration plant, that is, a refrigerator without work input, which is driven by a heat source. The treatment accounts for the heat transfer irrevers ...
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Journal articleInternational Journal of Heat and Mass Transfer · 1995
This paper addresses the fundamental heat transfer augmentation question of how to arrange a stack of parallel plates (e.g. fins of heat sink, printed circuit boards) in a free stream such that the thermal resistance between the stack and the stream is min ...
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Journal articleInternational Journal of Refrigeration · January 1, 1995
This paper shows that the intermittent operation of a defrosting vapour-compression-cycle refrigerator can be optimized with respect to: (1) the frequency of on/off operation, and (2) the way in which the supply of heat exchanger surface is divided between ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1995
This is a theoretical, numerical and experimental study that shows how to optimize the performance of on and off pulsating heaters in forced convection. Scale analysis shows that there exists an optimal heat pulse interval or frequency that maximizes the o ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1995
This is a theoretical, numerical and experimental study of how to select the spacing (S) between horizontal cylinders in an array with laminar natural convection, such that the total heat transfer (q) between the array and the ambient is maximized. The vol ...
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Journal articleJournal of Heat Transfer · January 1, 1995
This is a theoretical, numerical, and experimental study of natural convection heat transfer from an immersed surface with intermittent uniform heat flux. Scale analysis predicts that the “on” time interval can be optimized such that the overall Nusselt nu ...
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Journal articleInternational Journal of Heat and Fluid Flow · January 1, 1995
The problem of mixed convection on a wedge in a saturated porous medium is analyzed using the Darcy flow formulation and three different methods of solution. Nonsimilar solutions are obtained for several wedge angles. The nonsimilarity technique is applied ...
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Journal articleInternational Journal of Heat and Fluid Flow · 1995
This paper addresses the question of how to cool a stack of parallel, heat-generating boards when the flow is impeded by electromagnetic screens placed upstream and downstream of the stack. Four separate designs are considered: (1) forced convection coolin ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1995
This paper shows that the power output of various power plant configurations can be maximized by properly dividing the fixed inventory of heat exchange equipment among the heat transfer components of each plant. This conclusion is built over a sequence of ...
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Journal article · January 1, 1995
Reflecting real-life thermal engineering, this comprehensive text takes an interdisciplinary approach to the subject of heat transfer. The author stresses the relationship to other engineering disciplines, such as thermodynamics and fluid mechanics, and th ...
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Journal articleWinter Annual Meeting of the American Society of Mechanical Engineers · December 1, 1994
An area that has received considerable attention is the time-dependent heat transfer between two surfaces placed suddenly in contact. Recently, an entirely new area is centered around the question of what happens when at least one of the surfaces is initia ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1994
This paper shows that the hot spot temperature of an electronic module with finned air heat sink can be reduced by allowing the fin thickness and height to increase in the flow direction x. The hot spot temperature decreases by about 15% if the thickness o ...
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Journal articleNumerical Heat Transfer Part A Applications · January 1, 1994
This paper shows numerically how to select the optimal spacing between boards mounted in a stack of specified volume, so that the overall thermai conductance between the stack and the forced coolant is maximum. Several configurations are considered: boards ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1994
This paper demonstrates the existence of an optimal on/off sequence for operating a household refrigerator that accumulates ice on its evaporator coils. Experimentally it is shown that the rate of ice formation is constant in time. The optimal (intermitten ...
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Journal articleHeat Transfer Engineering · January 1, 1994
This article presents the solutions to two fundamental problems in the design of the insulation for a refrigerator. The first problem is how to incorporate the new generation of non-CFC materials in a composite layer that also contains polyurethane foam. T ...
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Journal articleInternational Journal of Heat and Fluid Flow · January 1, 1994
The patterns of heatlines reported in this paper illustrate for the first time the true path of convective heat transfer through a saturated porous medium. Heatline patterns are reported for the following fundamental configurations: the boundary layer near ...
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Journal articleJournal of Heat Transfer · January 1, 1994
This paper describes the fundamentals of melting when a shell of phase-change material rides on a heated horizontal cylinder. In the first part of the paper, contact melting theory is used to predict the history of the melting process and, in particular, t ...
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Journal articleInternational Communications in Heat and Mass Transfer · January 1, 1994
This paper shows how to correlate the optimal sizes of bodies with specified external forced convection heat transfer, when the objective is to minimize 1) the total rate of entropy generation, or 2) the total cost. Specific results are reported for the cy ...
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Journal articleInternational Journal of Heat and Fluid Flow · January 1, 1994
This study documents the pressure drop and heat transfer through bundles of parallel cylinders in a domain that has been overlooked, namely, low Reynolds numbers, arrays that are long in the direction of flow such that the flow is hydraulically and thermal ...
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Journal articleInternational Journal of Heat and Mass Transfer · 1994
This paper shows that the hot spot temperature of an electronic module with finned air heat sink can be reduced by allowing the fin thickness and height to increase in the flow direction x. The hot spot temperature decreases by about 15% if the thickness o ...
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Journal articleAdvances in Heat Transfer · January 1, 1994
The subject of this chapter is the relatively recent work on melting and lubrication at the interface between two solid parts, one of which is at its melting point. It is an area of research that began in heat transfer, with studies of contact melting insi ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1993
In this paper we describe the thin-film melting of a block of solid phase-change material (the bearing) around a rotating cylinder (the shaft). We determine the relation between the force applied on the shaft and the speed with which the shaft migrates int ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1993
This is a numerical and theoretical investigation of natural convection in a two-dimensional square enclosure with one side cold and isothermal, and the other side heated with pulsating heat flux. It is shown numerically that the buoyancy induced circulati ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1993
This paper reports in closed form the similarity heatfunctions H for laminar boundary layer flow on a flat wall. Plots of the constant-H lines ('heatlines') show that the path of convection from a hot free stream to a cold wall is unlike the path of convec ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1993
In this paper, we show analytically how to optimize the spacing between heat generating boards in a stack cooled by single-phase laminar forced convection. The thickness of each board is not negligible. The theoretical results for optimal spacing and maxim ...
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Journal articleJournal of Heat Transfer · January 1, 1993
This paper reports the optimal geometry of an array of fins that minimizes the thermal resistance between the substrate and the flow forced through the fins. The flow regime is laminar. Two fin types are considered: round pin fins, and staggered parallel-p ...
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Journal articleInternational Journal of Heat and Fluid Flow · 1993
This paper addresses the fundamental question of how to position a heat-generating board inside a parallel-plate channel, where it is cooled by forced convection. It is shown that when the board substrate is a relatively good thermal conductor, the best bo ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1993
This paper shows that it is possible to distribute a finite amount of insulation in an optimal way that minimizes the overall heat transfer rate from a nonisothermal wall to the ambient. The optimal insulation thickness for a plane wall varies as the squar ...
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Journal articleJournal of Heat Transfer · January 1, 1993
Thermally active fabrics and insulations consist of fibers coated with phase-change materials and surrounded by air. This paper constructs a homogeneous porous medium model for melting and solidification in spaces filled with thermally active fibers. Three ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1993
This paper describes the water film that is formed as ice melts under a two-dimensional solid slider. The analysis is based on the contact melting theory, and accounts for the coupling between the heat transfer across the water film and the fluid mechanics ...
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Journal articleAmerican Society of Mechanical Engineers Heat Transfer Division Publication HTD · December 1, 1992
This invited paper reviews the current research on close-contact melting heat transfer, and the relevance of this work to understanding and predicting melt lubrication. Contact melting and lubrication is a relatively complicated phenomenon, because it comb ...
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Journal articleJournal of Energy Resources Technology Transactions of the ASME · January 1, 1992
This paper documents the relative merits of using more than one type of phasechange material for energy storage. In the case of two phase-change systems in series, which are melted by the same stream of hot fluid, there exists an optimal melting point for ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1992
This paper reports the results of a numerical study of the time-dependent removal of contaminant from a two-dimensional enclosure with one inlet and one outlet. The contaminant is generated beginning with the time t = 0 by a concentrated source located ins ...
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Journal articleInternational Communications in Heat and Mass Transfer · January 1, 1992
The melting rates due to close-contact heating of a block of phase-change material have been analyzed in the past based on thin-film lubrication theory in several internal and external configurations. The scale analysis of close-contact melting in a region ...
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Journal articleJournal of Heat Transfer · January 1, 1992
The heat transfer by natural convection and radiation in a two-dimensional cavity with one side heated, one side and bottom insulated, and the top open was investigated numerically. The first part of the study focused on natural convection alone, and concl ...
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Journal articleInternational Journal of Heat and Fluid Flow · January 1, 1992
It has been proposed to extract energy from the subterranean hot dry rock bed (HDR) by creating one or more narrow fractures in the rock and circulating cold water through the fractures. In time, the temperature of the rock region surrounding the crack dro ...
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Journal articleInternational Journal of Heat and Fluid Flow · January 1, 1992
This note focuses on Kladias and Prasad's claim that the critical Rayleigh number for the onset of Bénard convection in an infinite horizontal porous layer increases as the Prandtl number decreases, and argues that the critical Rayleigh number (Rac
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1992
This paper documents the conjugate heat transfer through a wall with nonuniform thickness, which is lined on one side by a boundary layer. In the first part, variational calculus shows that the total heat transfer rate is minimized w hen the wall thickness ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1992
This paper reports the optimal board-to-board spacing and maximum total heat transfer rate from a stack of parallel boards cooled by laminar forced convection. The optimal spacing is proportional to the board length raised to the power 1/2, the property gr ...
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Journal articleundefined · January 1, 1991
Experiments performed demonstrate the transition to turbulent flow of water jets discharging coaxially into a stream confined in a round duct. The critical Reynolds number is shown to be a strong function of velocity ratio. From the flow visualization it i ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1991
This study illustrates the thermodynamic information that is being routinely overlooked by a pure fluid mechanics analysis. The integral analysis of the two-dimensional turbulent jet is used as an example. It is shown that even when the temperature differe ...
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Journal articleInternational Communications in Heat and Mass Transfer · January 1, 1991
This paper describes the time evolution of the temperature and heat transfer in the vicinity of a flat wall embedded in a parallel flow through a saturated porous medium. The flow is uniform and steady, while the wall is suddenly subjected to heating or co ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1991
This paper reports the results of a fundamental study of the transient removal of a contaminant from a two-dimensional enclosure with one inlet and one outlet. The evolution of the flow and concentration fields are simulated numerically using Jones and Lau ...
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Journal articleJournal of Heat Transfer · January 1, 1991
This paper documents the thermal insulation effect of a screen installed inside a vertical rectangular enclosure (e.g., double-glazed window). The screen is a Venetian blind system made out of horizontal strips that can be rotated. The focus is on the “clo ...
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Journal articleJournal of Solar Energy Engineering Transactions of the ASME · January 1, 1991
This paper considers the question of whether the optimum phase-change temperature for maximum exergy storage is universally equal to the geometric mean of the heat source and environment temperature, Tm= (T∞, Te)1/2
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Journal articleInternational Journal of Heat and Fluid Flow · January 1, 1991
This note summarizes the results of a numerical study designed to question (i.e., refute or validate) Chao et al.'s1 and Bertin and Ozoe's2 conclusion that the critical Rayleigh number increases substantially as the Prandtl number bec ...
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Journal articleInternational Journal of Heat and Fluid Flow · January 1, 1991
Heat transfer through a vertical skin surface covered with perpendicular hair strands of uniform density is investigated numerically. The heat transfer rate is the result of (1) direct heat transfer to the air that makes contact with the skin and (2) the h ...
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Journal articleInternational Journal of Heat and Fluid Flow · January 1, 1991
In this paper the cooking of meat is modeled as a process of time-dependent conduction through a constant-property medium that shrinks as its temperature increases. The overall shrinkage is the integrated result of shrinking that is distributed volumetrica ...
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Journal articleNumerical Heat Transfer Part A Applications · January 1, 1991
The phenomenon of natural convection in a square enclosure heated and cooled in the horizontal direction was investigated numerically in the Prandtl number range 0.01-10 and the Rayleigh number range 102-1011. The numerical method ret ...
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Journal article · January 1, 1991
Experiments performed demonstrate the transition to turbulent flow of water jets discharging coaxially into a stream confined in a round duct. The critical Reynolds number is shown to be a strong function of velocity ratio. From the flow visualization it i ...
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Journal articleAmerican Society of Mechanical Engineers Fluids Engineering Division Publication FED · December 1, 1990
Experiments performed demonstrate the transition to turbulent flow of water jets discharging coaxially into a stream confined in a round duct. The critical Reynolds number is shown to be a strong function of velocity ratio. From the flow visualization it i ...
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Journal articleundefined · January 1, 1990
Experiments were performed to demonstrate the transition to turbulent flow of water jets discharging coaxially into a stream confined in a round duct. Experimental apparatus consisted of a storage tank, pump, constant head tank to minimize pump transients, ...
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Journal articleInternational Communications in Heat and Mass Transfer · January 1, 1990
Experimental observations of the shape of the laminar and transition sections of a confined coaxial jet show that the laminar length (L) is always approximately ten times greater than the wavelength of the first sinusoidal deformation of the flow (λ). This ...
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Journal article · January 1, 1990
Experiments were performed to demonstrate the transition to turbulent flow of water jets discharging coaxially into a stream confined in a round duct. Experimental apparatus consisted of a storage tank, pump, constant head tank to minimize pump transients, ...
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Journal articleInternational Journal of Heat and Mass Transfer · 1990
This is an experimental and theoretical study of the process of time-dependent solidification in an enclosed liquid cooled from the side. The form is on the effect of high Rayleigh number convection, and the convection-conduction interaction across the fre ...
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Journal articleInternational Journal of Heat and Fluid Flow · January 1, 1990
This article reports the results of a numerical study of heat transfer to the air permeating through hair strands covering a flat surface. First, the surface is modeled as isothermal, and second the surface is assumed covered with uniform heat flux. For bo ...
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Journal articleJournal of Heat Transfer · January 1, 1990
This paper describes the fundamental mechanisms of heat transfer through a surface covered with perpendicular hair strands of uniform density. An airflow parallel to the skin seeps through the spaces created between the hair strands. It is shown that the t ...
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Journal articleJournal of Solar Energy Engineering Transactions of the ASME · January 1, 1990
This paper describes the most basic thermodynamic aspects of the process of energy storage by melting of a phase change material when the energy source is a stream of hot single-phase fluid. The first part of the paper considers the melting process ruled b ...
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Journal articleInternational Journal of Heat and Fluid Flow · January 1, 1990
This article presents a theory of how the melt region advances as an intrusion layer along the top boundary of a solid phase-change material that is heated from the side. The phase-change material fills the pores of a solid matrix. We show that the thickne ...
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Journal articleJournal of Heat Transfer · January 1, 1990
This paper documents the convection heat transfer enhancement effect that is associated with theperiodic (timewise and spatial) longitudinal stretching of an infinite plane wall bathed by a semi-infinite fluid reservoir. It is shown that the flow field rea ...
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Journal articleJournal of Heat Transfer · January 1, 1990
This paper describes the flow and temperature distribution in the hourglass-shaped cavity formed between two rollers and two parallel runner surfaces. The cavity fluid is heated uniformly over the roller surfaces, and cooled along the two runners, which ar ...
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Journal articleAdvances in Heat Transfer · January 1, 1990
The chapter describes the combined heat and mass-transfer natural convection mechanisms, which are considered an important subfield in contemporary heat and mass-transfer research. This subfield essentially brings together the studies concerned with the co ...
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Journal articleAmerican Society of Mechanical Engineers Fluids Engineering Division Publication FED · December 1, 1989
This paper reports a numerical study of the natural convection flows that are induced by a finite source of heat and chemical constituent localized at the bottom wall of a horizontal porous layer. The focus is on the Darcy flow, and heat and mass transfer ...
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Journal articleMechanical Engineering · November 1, 1989
The author discusses how buckling flow has become a new area in fluid mechanics research because of numerous natural flow phenomena which exhibit geometric features which can be compared with classical buckling of solid elastic columns. The most striking f ...
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Journal articleMechanical Engineering · August 1, 1989
Building efficient energy systems means designing for less and less entropy. The engineer must balance the heat-transfer and fluid-flow irreversibilities in even the tiniest components of a system. The minimization of entropy generation is a design philoso ...
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Journal articleJournal of Heat Transfer · January 1, 1989
This paper addresses the fundamentals of the phenomenon of steady heat transfer by rolling contact between two bodies at different temperatures. The contact region is modeled according to the classical Hertz theory, by which the bodies undergo elastic defo ...
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Journal articleJournal of Heat Transfer · January 1, 1989
This paper reports a complete theory of the melting that occurs in a confined porous medium saturated with phase-change material and heated from the side. Darcy flow characteristics are assumed for the liquid phase. The solid phase is isothermal and at the ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1989
This paper reports a theoretical and experimental study of the effect of solid-side subcooling on the phenomenon of melting by natural convection at the vertical interface between a solid body and a pool of its own liquid. The first part of the study consi ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1989
This paper describes a two-part study of the time-dependent melting of an enclosed phasechange material heated at a constant rate from the side. The first part describes experimental measurements with n-octadecane conducted in a 74 cm tall enclosure. The h ...
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Journal articleInternational Journal of Heat and Fluid Flow · January 1, 1989
This paper reports theoretical solutions for the quasi-steady and time-dependent regimes of melting in the presence of natural convection in an enclosed phase-change material heated from the side. The first part consists of developing two boundary layer so ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1989
This study questions the view that the degree of thennodynamic imperfection (second law efficiency, η11) of the refrigeration and liquefaction plants that have been built does not depend on the refrigeration load temperature Tl. It is ...
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Journal articleJournal of Heat Transfer · January 1, 1989
This paper focuses on the phenomenon of melting and lubrication by the sliding contact between a phase-change material and a smooth flat slider. The first part of the study considers the limit in which the melting is due primarily to “direct heating, ”that ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1989
This paper describes analytically the process in which a body of glass is heated, softened and eroded ('melted' away) by direct contact with a solid surface of much higher temperature. This surface can slide relative to the body of glass. The glass is mode ...
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Journal articleAmerican Society of Mechanical Engineers Advanced Energy Systems Division Publication AES · December 1, 1988
The modern trends in the field of engineering thermodynamics are reviewed by focusing on six distinct areas: axiomatic formulations, graphic constructions, exergy analysis, thermodynamic design, the science of irreversible power plants, and the intermediat ...
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Journal articleMechanical Engineering · May 1, 1988
At first glance, engineering thermodynamics may appear to be a dead discipline, but closer examination reveals a remarkably lively field of study. Its axioms have recently been reformulated in terms of heat transfer instead of mechanics. New graphic constr ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1988
In the first part of the paper, Ernst Schmidt's intuitive argument for choosing the optimum fin shape for least material is translated into analysis using the method of variational calculus. It is shown that even when the thermal conductivity of the fin is ...
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Journal articleInternational Journal of Heat and Fluid Flow · January 1, 1988
This paper describes a numerical and theoretical study of the transient natural convection heating of a two-dimensional rectangular enclosure filled with fluid. The heating is applied suddenly along one of the side walls, while the remaining three walls ar ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1988
This study identifies the most basic scales and regimes of the phenomenon of melting with natural convection in an enclosure heated from the side. In the first part of the study the method of scale analysis is used to show that the phenomenon consists of a ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1988
This paper describes the fundamentals of the heat transfer melting process occurring in the narrow rolling contact region between a body of phase-change material and a solid body that acts as a heater. The theory is based on the following assumptions : (i) ...
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Journal articleJournal of Heat Transfer · January 1, 1988
As an alternative to the mechanistic point of view expressed in Caratheodory's axioms, it is shown that the laws and concepts of thermodynamics are covered also by two statements made from a purely heat transfer perspective: Axiom I'—The heat transfer is t ...
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Journal articleExperimental Thermal and Fluid Science · January 1, 1988
This paper describes an experimental study of transient natural convection heating and cooling of a 30 cm diameter horizontal cylinder filled with water or water-glycerol solutions. The Rayleigh number range covered by these experiments is 8 × 107
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1988
The observed degree of thermodynamic imperfection of existing power plants is explained based on a steady-state power plant model the irreversibility of which is due to three sources: the hot-end heat exchanger, the cold-end heat exchanger and the heat lea ...
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Journal articleInternational Communications in Heat and Mass Transfer · January 1, 1988
This paper draws attention to a series of misconceptions and misstatements regarding the origin and meaning of some of the most basic concepts of engineering thermodynamics. The six examples exhibited in the paper relate to the concepts of reversibility, e ...
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Journal articleJournal of Heat Transfer · January 1, 1988
The natural convection flow and heat transfer between two enclosures that communicate through a vertical opening is studied by considering the evolution of an enclosed fluid in which the left half is originally at a different temperature than the right hal ...
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Journal articleInternational Journal of Heat and Fluid Flow · January 1, 1988
This note contains a set of charts for the enthalpy change function Δh(T), the absolute entropy at atmospheric pressure s°(T), and the flow exergy at atmospheric pressure e°x(T) of 12 gases in the ideal-gas limit. The gases considered are CO, CO ...
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Journal articleAnnu Rev Numer Fluid Mech Heat Transfer · December 1, 1987
The objective of this review is to draw attention to recent advances in a relatively new subfield of fluid mechanics research, namely, the study of the buckling or meandering tendency exhibited by some flows at sufficiently high Reynolds numbers. Buckling ...
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Journal articleSolar Energy Utilization. Proceedings of the NATO Advanced Study Institute · 1987
The thermodynamics of solar thermal energy conversion installations is reviewed in the spirit of second law analysis. A review of the equilibrium thermodynamics of radiation as a photon gas system, and with an outline of benchmark reversible and irreversib ...
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Journal articleJournal of Solar Energy Engineering Transactions of the ASME · January 1, 1987
The discussion of the ideal conversion of enclosed thermal radiation revolves around three different theories, whose earliest proponents were Petela, Spanner, and Jeter, respectively. Each of these theories has been accused to be incorrect. The objective o ...
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Journal articleJournal of Heat Transfer · January 1, 1987
The phenomenon of natural convection caused by combined temperature and concentration buoyancy effects is studied analytically and numerically in a rectangular slot with uniform heat and mass fluxes along the vertical sides. The analytical part is devoted ...
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Journal articleInternational Communications in Heat and Mass Transfer · January 1, 1987
Diverse measurements of heat transfer by Benard convection in a fluid saturated porous layer are correlated by considering only the Darcy and Forschheimer asymptotes of the phenomenon. Scale analysis suggests that in the Forschheimer limit the Nusselt numb ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1987
This paper outlines a combined theoretical and numerical study of the mass transfer effected by high Rayleigh number Bénard convection in a two-dimensional saturated porous layer heated from below. The focus of this study is on the Darcy flow, heat transfe ...
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Journal articleInternational Communications in Heat and Mass Transfer · January 1, 1987
The parallel structure of the fields of natural convection in fluids and natural convection in porous media is reviewed in terms of the most basic scales of flow, heat and mass transfer. In each field, the review includes single vertical boundary layers, e ...
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Journal articleInternational Journal of Heat and Fluid Flow · January 1, 1987
This review article places in perspective the new work devoted both to the analysis of the thermodynamic irreversibility of heat and mass transfer components and systems and to the design of these devices on the basis of entropy generation minimization. Th ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1987
This is an analytical and numerical study of the buoyancy-driven horizontal spreading of heat and chemical species through a fluid-saturated porous medium. The buoyancy effect is due to both temperature and concentration gradients. It is shown that when th ...
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Journal articleundefined · January 1, 1987
The parallel structure of the fields of natural convection in fluids and natural convection in porous media is reviewed in terms of the most basic scales of flow, heat and mass transfer. In each field, the review includes single vertical boundary layers, e ...
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Journal articleNumerical Heat Transfer · January 1, 1986
This is a study of the flow driven by the buoyancy effect associated with the non-uniform volumetric absorption of a spatially uniform flux of thermal radiation that impinges on a body of fluid. The nonuniform absorption of radiation is due to the presence ...
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Journal articleJournal of Heat Transfer · January 1, 1986
The natural circulation of near-4°C water in a vertical cavity heated from the side was studied experimentally in a 0,74-m-tall enclosure. The results of a scale analysis were used in order to correlate the overall wall-to-wall heat transfer rate measured ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1986
This paper reports an analytical and numerical study of natural convection heat and mass transfer through a vertical porous layer subjected to uniform fluxes of heat and mass from the side. The flow is driven by the combined buoyancy effect due to temperat ...
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Journal articleInternational Journal of Heat and Fluid Flow · January 1, 1986
A series of numerical experiments concerning the phenomenon of natural convection in a two-layer composite system heated from below is reported. The composite system consists of a fluid layer bounded from below by a porous bed saturated by the same fluid. ...
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Journal articleundefined · December 1, 1985
This paper uses the scale analysis methodology in order to review the most basic features of natural convection phenomena driven by buoyancy associated with differential heating from the side. Because of its focus on the scale analysis of flows through por ...
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Journal articleundefined · December 1, 1985
The volume of natural convection results accumulated already in the heat transfer literature is discussed. This article discusses the methodology on which these results are based. The methods available to the problem solver in natural convection range all ...
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Journal articleJournal of Heat Transfer · January 1, 1985
This is a study of the single-cell natural convection pattern that occurs in a “stably heated” corner in a fluid-saturated porous medium, i.e., in the corner formed between a cold horizontal wall and a hot vertical wall situated above the horizontal wall, ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1985
This paper reports a fundamental study of the phenomenon of natural convection heat and mass transfer near a vertical surface embedded in a fluid-saturated porous medium. The buoyancy effect is due to the variation of temperature and concentration across t ...
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Journal articleJournal of Solar Energy Engineering Transactions of the ASME · January 1, 1985
This is an analytical and numerical study of the exergy that can be delivered by a solar collector installation with temporary energy storage capability. In the first part of the study, the method of variational calculus is used to show that under conditio ...
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Journal articlePhysics of Fluids · January 1, 1985
This is a fundamental study of the phenomenon of natural convection in the region formed by a vertical warm wall rising above a cold horizontal wall, or in the region between a cold vertical wall extending downward from a warm horizontal surface. The study ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1985
This paper describes a comprehensive study of the natural convection phenomenon occurring inside a porous layer with both heat and mass transfer from the side. The natural circulation is driven by a combination of buoyancy effects due to both temperature a ...
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Journal articleJournal of Heat Transfer · January 1, 1985
It is shown that the phenomenon of natural convection driven in a porous medium by a cold plate facing upward or by a warm plate facing downward consists of a finite-length boundary layer flow chopped off by the sharp edges of the plate. The heat and fluid ...
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Journal articleInternational Journal of Heat and Fluid Flow · January 1, 1985
This paper reports a fundamental study of laminar natural convection in a rectangular enclosure with heat and mass transfer from the side, when the bouyancy effect is due to density variations caused by either temperature or concentration variations. In th ...
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Journal articlePhysics of Fluids · January 1, 1985
An analytical and numerical study is reported of steady-state natural convection in a two-dimensional porous layer heated from the side. Contrary to previous investigations of the phenomenon, which were all based on the Darcy flow model, a vector generaliz ...
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Journal articleJournal of Fluids Engineering Transactions of the ASME · January 1, 1985
A linear stability analysis of the large-scale structure of a round jet surrounded by an annular shear layer is presented. The study is limited to the developing region near the jet nozzle in the limit Re → ∞, The radial dependence of the amplitudes of gro ...
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Journal articleTrans ASME J Fluids Engng · January 1, 1985
Uses a simple stability model to identify some of the global properties of large scale eddies, in particular the radial dependence of the amplitudes of growing disturbances in order to study the extent to which the disturbances penetrate the jet and its su ...
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Journal articleJournal of Fluids Engineering Transactions of the ASME · January 1, 1984
This paper reports a series of experiments concerning the buckling of a slender fluid layer in a state of longitudinal compression. The experiments consist of floating a layer of highly viscous oil on a pool of water and, manually, compressing the layer fr ...
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Journal articleJournal of Heat Transfer · January 1, 1984
This paper summarizes an analytical and numerical study of buoyancy-driven convection in a rectangular cavity filled with fluid. The new feature of this study, suggested by architectural applications of the convection phenomenon, is the presence of constan ...
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Journal articlePhysics of Fluids · January 1, 1984
A numerical study of two-dimensional natural convection in a horizontal water layer heated from below is reported. The density maximum associated with water at 3.98°C and atmospheric pressure occurs inside the layer, as the top surface is maintained at 0°C ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1984
This paper reports similarity solutions for vertical boundary layer natural convection near a solid wall adjacent to a fluid-saturated porous medium, in the case where the pore Reynolds number is high enough for the Darcy flow model to break down. Based on ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1984
This paper reports a series of numerical simulations and a scale analysis of the penetrative convection occurring along the unevenly heated horizontal wall of a semi-infinite porous medium. Modeling the problem as two-dimensional, and assuming that the hor ...
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Journal articleInternational Journal of Heat and Mass Transfer · 1984
The objective of the present study was to document numerically the characteristics of natural circulation in a porous layer heated from below, and in this way to verify the linear stability predictions regarding the onset of convection. Another objective o ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1984
This paper describes the heat transfer and fluid flow through a confined porous layer heated and cooled along one of the vertical side walls. In the first part of the study, consideration is given to the case when the side-heating effect is positioned abov ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1984
This paper reports a numerical study of two-dimensional natural convection in a horizontal porous layer heated from below and saturated with cold water. The density maximum of water at 3.98°C and atmospheric pressure occurs inside the layer, as the top sur ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1983
On décrit une étude expérimentale et analytique du phénomène de transfert thermique par convection naturelle dans une enceinte rectangulaire munie d’une cloison interne incomplète. Les expériences sont conduites avec une enceinte remplie d’eau avec des par ...
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Journal articlePhysics of Fluids · January 1, 1983
An experimental and theoretical study of the static buckling of a downward flowing stream surrounded by a highly flexible duct is reported. It is shown analytically that the stream buckles into a meandering shape that depends strongly on the flow velocity ...
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Journal articleJournal of Heat Transfer · January 1, 1983
This paper examines the interaction by natural convection between a fluid-saturated porous medium and a fluid reservoir separated by a vertical impermeable partition. The two fluid systems are maintained at different temperatures. The analysis is simplifie ...
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Journal articleJournal of Fluids Engineering Transactions of the ASME · January 1, 1983
This paper documents the sinuous flow of a vertical water column which impinges on a horizontal surface. It is shown experimentally that the solid obstacle buckles the column into a plane sinuous (static) shape whose wavelength scales with the local column ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1983
This paper is a Second-Law study of thermal insulation systems consisting of two 1-dim. insulations in parallel. It is shown that the parallel-insulation model applies to power and refrigeration systems exposed to large absolute temperature ratios. The ins ...
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Journal articlePhysics of Fluids · January 1, 1983
The focus of this paper is on the fundamentals of the transient mechanism responsible for the establishment of natural convection in a two-dimensional porous layer confined between isothermal vertical walls and insulated horizontal walls. In the first part ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1983
On étudie théoriquement et expérimentalement le mécanisme fondamental responsable de la transition dans la convection naturelle d’un panache. Théoriquement, la transition apparaît quand le temps de pénétration visqueuse normale au panache devient comparabl ...
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Journal articleJournal of Heat Transfer · January 1, 1983
Scaling arguments and numerical analysis are used to document the transient and steady-state regimes of natural convection in a triangular porous layer cooled from above (along the sloping wall). The numerical simulations are conducted in the high Rayleigh ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1983
Cette étude numérique concerne l’effet des obstructions de l’écoulement interne sur le transfert thermique à travers une couche poreuse bidimensionnelle chauffée latéralement. On considère trois types d’obstruction. Des partitions diathermales horizontales ...
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Journal articleInternational Journal of Heat and Fluid Flow · January 1, 1983
Hydrodynamic stability analysis of an inviscid wall jet shows that instability is possible above a characteristic disturbance wavelength which is proportional to the jet thickness. This scaling is the basis for an argument that transition occurs when the f ...
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Journal articleJournal of Fluid Mechanics · January 1, 1983
This paper reports a fundamental study of the fluid dynamics inside a triangular (attic-shaped) enclosure with cold upper wall and warm horizontal bottom wall. The study was undertaken in three distinct parts. In the first part, the flow and temperature fi ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1983
On étudie numériquement l’effet d’une perméabilité et d’une diffusivité thermique non uniformes pour un système poreux chauffé latéralement. La première partie de l’étude, section 2, s’intéresse aux systèmes composés de sous-couches verticales. On montre q ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1983
On donne une solution analytique et numérique de laconvection naturelle dans une couche poreuse rectangulaire chauffée et refroidie avec des flux uniformes le long des parois verticales. On montre analytiquement que, dans le régime de couche limite, l’épai ...
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Journal articleWarme Und Stoffubertragung · December 1, 1982
This paper reports a theory which explains the flickering motion of turbulent plumes as well as their large-scale sinuous structure. The theory is based on the fact that the inviscid region of the plume (the "plume column") possesses elastic properties ana ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1982
This paper considers the basic thermal design problem of cooling or heating an object using the minimum amount of working fluid. It is shown analytically that if the duration of the cooling or heating process is fixed, then there exists a unique operating ...
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Journal articleAdvances in Heat Transfer · January 1, 1982
This chapter discusses second-law analysis in heat transfer and entropy generation minimization in thermal design. It describes the derivation of the Gouy–Stodola theorem, the basis for entropy generation minimization in the conceptual design of heat trans ...
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Journal articlePhysics of Fluids · January 1, 1982
This paper reports an experimental study of the nonaxisymmetric flow of a fast liquid jet discharging into the atmosphere. The nonaxisymmetric shape of the jet was photographed and subjected to a wavelength analysis. The results of the wavelength analysis ...
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Journal articleJournal of Heat Transfer · January 1, 1982
This article reports an analytical study of natural convection in a wedge-shaped horizontal space filled with a fluid-saturated porous medium. The study focuses on the detrimental effect of natural convection on the insulation value of an atticshaped porou ...
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Journal articleInternational Journal of Heat and Fluid Flow · January 1, 1982
Maximization of energy delivery is the fundamental problem in solar collector thermal design. This paper examines the trade-off between the storage and the immediate use of solar exergy, with the objective of maximising the long-term exergy output from a s ...
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Journal articleGeophysical Research Letters · January 1, 1982
This paper advances a theoretical explanation for the lateral periodicity and geometric similarity of meanders observed in rivers of many sizes. Invoking the static equilibrium of a straight river bed, it is shown analytically that the equilibrium shape of ...
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Journal articlePhysics of Fluids · January 1, 1982
This paper discusses experimental observations of the meandering fall of light-weight tissue paper ribbons. The photographs show that the ribbons assume a sinusoidal shape with a unique wavelength which scales with the thickness of the airstream entrained ...
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Journal articleJournal of Heat Transfer · January 1, 1982
This paper establishes a theoretical framework for the minimization of entropy generation (the waste of exergy, or useful energy) in extended surf aces (fins). The entropy generation rate formula for a general fin is derived first. Based on this general re ...
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Journal articleJournal of Heat Transfer · January 1, 1982
This paper reports experimental observations on transient natural convection in enclosures at high Rayleigh numbers (1.28 × 109, 1.49 × 109) and low aspect ratios (0.0625, 0.112). The phenomenon consists of the establishment of thin i ...
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Journal articleEnergy Policy · January 1, 1982
Existing energy policy proposals are approached from a demand-side perspective to solve the immediate problem of meeting existing demands defined by existing technologies. However, a constructive forward-looking policy requires a supply-side perspective. T ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1981
The heat transfer through vertical partitions surrounded by thermally-stratified fluids is studied theoretically and experimentally. The theory is based on the Oseen linearization method. The analytical results show the effect of thermal stratification on ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1981
This article examines the buoyancy induced circulation occurring on both sides of a vertical impermeable partition separating two semi-infinite porous reservoirs maintained at different temperatures. The circulation is found to consist of two counterflowin ...
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Journal articleLetters in Heat and Mass Transfer · January 1, 1981
This letter outlines the analogy which exists between inviscid jets and elastic columns in axial compression. It is shown that straight inviscid jet columns possess the property of sinusoidal infinitesimal buckling. The buckling wavelength scales with the ...
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Journal articleJournal of Heat Transfer · January 1, 1981
The paper reports an experimental study of natural convection between two water reservoirs connected through a two-dimensional horizontal duct. The flow field was visualized and the velocities were measured using the thymol blue pH indicator method. The te ...
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Journal articleJournal of Fluid Mechanics · January 1, 1981
The paper summarizes results from an experimental study of buoyancy-induced motion and heat transfer in a horizontal rectangular cavity with the two vertical ends at different temperatures and the long horizontal walls adiabatic. The cavity height/ length ...
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Journal articleJournal of Solar Energy Engineering Transactions of the ASME · January 1, 1981
The second law of thermodynamics is used to analyze the potential for exergy conservation in solar collector systems. It is shown that the amount of useful energy (exergy) delivered by solar collector systems is affected by heattransfer irreversibilities o ...
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Journal articleJournal of Heat Transfer · January 1, 1981
This article illustrates the fundamental features of lateral penetration of natural convection into a horizontal porous layer in lateral communication with a heat reservoir. It is found that the important group governing the fluid mechanics of the phenomen ...
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Journal articleJournal of Fluid Mechanics · January 1, 1981
The paper presents a theoretical and experimental study of natural convection in a horizontal cavity which communicates laterally with a large reservoir. The cavity walls and the reservoir are at different temperatures. It is shown theoretically that the f ...
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Journal articleJournal of Environmental Economics and Management · January 1, 1981
Optimal development programs that explicitly account for the environment impacts of extracting energy resources are analyzed. Possibilities of storing the resources above ground once it has been extracted are examined When environmental disruption results ...
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Journal articleWarme Und Stoffubertragung · December 1, 1980
The paper reports a finite difference solution for the natural counterflow generated in a horizontal adiabatic duct with different end-temperatures. Ducts with circular and rectangular cross-section are considered. The natural counterflow is modeled as ful ...
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Journal articleEnergy · January 1, 1980
The second law of thermodynamics is used as a basis for evaluating the irreversibility (entropy generation) associated with simple heat transfer processes. In the first part of this paper, the irreversibility production is analyzed from the local level, at ...
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Journal articleLetters in Heat and Mass Transfer · January 1, 1980
This letter proposes to use entropy generation as a measure of the relative merit of heat transfer augmentation techniques relative to each other and to the heat exchange apparatus in which they may be incorporated. In this context, heat transfer augmentat ...
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Journal articleEnergy · January 1, 1980
The choice among available energy sources for a given task requires technical and economic tradeoffs on the part of the individual investor. From the national perspective, however, the effectiveness with which available energy sources are utilized may well ...
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Journal articleEnergy · January 1, 1980
We examine the potential of heat-transfer augmentation techniques to reduce irreversibility (entropy generation, destruction of available work) in equipment for heat exchange. A number of popular swirl flow-promoting techniques is investigated in detail. I ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1980
Le phénomène de convection naturelle dans un tube horizontal avec différentes températures d'extrémité est étudié expérimentalement dans une cavité cylindrique avec un rapport diamètre/longueur égal à 0,112. Le nombre de Rayleigh basé sur le diamètre varie ...
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Journal articleJournal of Heat Transfer · January 1, 1980
This paper describes an analytical study of laminar natural convection on both sides of a vertical conducting wall of finite height separating two semi-infinite fluid reservoirs of different temperatures. The countercurrent boundary layer flow formed on th ...
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Journal articleTopics in Catalysis · January 1, 1980
This note describes an experimental study of the damaging effect of hydrogen bubbles on the effectiveness of the thymol blue velocity measurement method. Specifically, we document the effect of flow velocity, cathode voltage, and cathode diameter on bubble ...
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Journal articleJournal of Fluid Mechanics · January 1, 1979
This paper develops an alternative approach to evaluating the arbitrary constants found in Gill's solution for the boundary-layer free-convection regime in a vertical rectangular enclosure. The new method consists of calculating the net upward flow of ener ...
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Journal articleLetters in Heat and Mass Transfer · January 1, 1979
The floating constants in Weber's boundary layer solution for free convection in a differentially heated vertical porous slab are reevaluated with a new approach. This approach uses Weber's solution to calculate the net vertical heat flux which is equated ...
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Journal articleJ Fluid Mech · 1979
This paper develops an alternative approach to evalating the arbitrary constants found in A. E. Gill's solution for the boundary-layer free-convection regime in a vertical rectangular enclosure. The new method consists of calculating the net upward flow of ...
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Journal articleEnergy · January 1, 1979
The second law of thermodynamics is used as a basis for evaluting the irreversibility (entropy generation) associated with simple heat transfer processes. In the first part of this paper, the irreversibility production is analyzed from the local level, at ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1979
The gravity-induced flow in a long horizontal space of annular cross-section insulated laterally and with the two ends maintained at different temperatures was studied analytically. The velocity and temperature distribution in the central portion of the sp ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1979
The paper proposes a conceptually new method for thermal insulation system optimization. The method, based on minimizing thermodynamic irreversibility, consists of externally controlling the variation of heat leak with temperature across the insulation. It ...
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Journal articleJournal of Heat Transfer · January 1, 1979
The effect of net longitudinal flow on natural convection in a horizontal cavity with different end temperatures is discussed. The flow is studied using an asymptotic expansion in the aspect ratio A « 1, the Grashof, Prandtl and Peclet numbers being arbitr ...
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Journal articleJournal of Heat Transfer · January 1, 1979
The second law aspects of heat transfer by forced convection are illustrated in terms of four fundamental flow configurations: pipe flow, boundary layer over flat plate, single cylinder in cross-flow, flow in the entrance region of a flat rectangular duct. ...
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Journal articleCryogenics · January 1, 1978
The growth or collapse of a local normal zone in a superconducting winding structure saturated with single phase liquid helium (composite superconductor) is studied analytically. The history of a given temperature disturbance is derived from the solution t ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1978
The temperature difference applied across the two ends of a horizontal duct generates a natural counterflow in which colder fluid flows along the bottom of the duct towards the warm end while a warmer stream flows in the opposite direction along the top. T ...
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Journal articleJournal of Heat Transfer · January 1, 1978
The heat transfer by free convection in a horizontal cavity with adiabatic horizontal walls and differentially heated end walls is studied analytically. The paper develops three models for explaining and predicting the heat transfer mechanism in a cavity w ...
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Journal articleJournal of Heat Transfer · January 1, 1978
This technical note develops an analytical result for heat transfer by laminar free convection in a long horizontal parallel-plate channel connecting two reservoirs containing the same fluid but kept at different temperatures. The analysis is based on the ...
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Journal articleJournal of Heat Transfer · January 1, 1978
Natural convection in a porous medium filling a slender horizontal space with an end-toend temperature difference is studied analytically. The end-to-end temperature difference gives rise to a horizontal counterflow pattern augmenting the heat transfer rat ...
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Journal articleJournal of Fluid Mechanics · 1978
The phenomenon of buoyancy-induced convection in an infinite porous medium with a concentrated heat source is studied analytically. The transient and steady-state temperature distribution and flow pattern around the source are deterined using a perturbatio ...
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Journal articleJournal of Heat Transfer · January 1, 1978
The paper presents a treatment of sensible heat energy storage units as systems intended to store useful work. An analysis of the thermodynamic irreversibilities associated with storing energy from a hot gas source as sensible heat in huge liquid baths poi ...
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Journal articleInternational Journal of Heat and Mass Transfer · January 1, 1978
The temperature difference applied across the two ends of a horizontal duct generates a natural counterflow in which colder fluid along the bottom of the duct towards the warm end while a warmer stream flows in the opposite dierection along the top. The pa ...
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Journal articleJournal of Fluid Mechanics · January 1, 1978
The phenomenon of buoyancy-induced convection in an infinite porous medium with a concentrated heat source is studied analytically. The transient and steady-state temperature distribution and flow pattern around the source are determined using a perturbati ...
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Journal articleAmerican Society of Mechanical Engineers (Paper) · August 15, 1977
Two approximate analytical techniques are developed to investigate the transient behavior of normal zones in superconducting composites. Based on these methods, similar theoretical criteria for the growth or collapse of normal disturbances are derived. The ...
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Journal articleAmerican Society of Mechanical Engineers Paper · January 1, 1977
Two approximate analytical techniques are developed to investigate the transient behavior of normal zones in superconducting composites. Based on these methods, similar theoretical criteria for the growth or collapse of normal disturbances are derived. The ...
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Journal articleJournal of Heat Transfer · January 1, 1977
The thermal design of counterflow heat exchangers for gas-to-gas applications is based on the thermodynamic irreversibility rate or useful power no longer available as a result of heat exchanger frictional pressure drops and stream-to-stream temperature di ...
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Journal articleIEEE Transactions on Magnetics · January 1, 1977
The MIT-EPRI 3 MVA superconducting alternator has undergone a number of successful electrical and mechanical tests. During these tests a great deal of information on the thermal performance of the rotor has been collected. This information has not been pre ...
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Journal articleTrans. ASME, C, J. Heat Transf. (USA) · 1977
The thermal design of counterflow heat exchangers for gas-to-gas applications is based on the thermodynamic irreversibility rate or useful power no longer available as a result of heat exchanger frictional pressure drops and stream-to-stream temperature di ...
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Journal articleCryogenics · January 1, 1977
Forced-cooled superconductors are viewed as a promising alternative in the development of high field superconducting magnets for future fusion devices. The high current density cable superconductor is protected against thermal instabilities by forcing (sin ...
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Journal articleJournal of Heat Transfer · January 1, 1977
The current supply cables of large superconducting magnet systems are cooled with an axial stream of cold helium vapor. If the flow of coolant is suddenly interrupted the current cables may overheat and burn up causing extensive damage to the entire system ...
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Journal articleIEEE Transactions on Magnetics · January 1, 1977
Refrigeration costs constitute an important aspect of the economics of force-cooled cable superconductors. The refrigerator power required to operate a forced cooled superconducting magnet is analyzed. The paper develops a simple method for estimating the ...
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Journal articleAmerican Society of Mechanical Engineers (Paper) · December 1, 1976
Forced-cooled superconductors are viewed as a promising alternative in the development of high field superconducting magnets for future fusion devices. The high current density cabled superconductor is protected against thermal instabilities by forcing (si ...
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Journal articleAmerican Society of Mechanical Engineers (Paper) · January 1, 1976
Forced-cooled superconductors are viewed as a promising alternative in the development of high field superconducting magnets for future fusion devices. The high current density cabled superconductor is protected against thermal instabilities by forcing (si ...
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Journal articleundefined · January 1, 1976
In the last two years the authors have developed a new concept of hollow superconductors able to recover from transient instabilities by virtue of on-going single phase cooling. The authors have been able to correlate results between an iterative computer ...
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Journal articleCryogenics · January 1, 1976
Superconducting magnets are energized through helium vapour-cooled cryogenic current leads operating at high ratios of current to mass flow. The high current operation where lead temperature, runaway, and eventual burn-up are likely to occur is investigate ...
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Journal articleCryogenics · January 1, 1976
The rotating superconducting windings of large ac machines must be supplied with enough refrigeration at an adequate temperature. The problems associated with bringing liquid helium to the rotating winding structure are analysed. Existing designs as well a ...
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Journal articleundefined · January 1, 1976
Within the last two years the authors have developed a new concept of cabled superconducting hollow conductors able to recover from transient instabilities by virtue of on-going, single-phase helium cooling. The authors have been able to correlate small sc ...
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Journal articleAdv Cryog Eng · January 1, 1975
The objective of this paper is to establish simple rules for use in the design of gas-cooled conducting supports. The rules should allow design for good thermal performance without unnecessary mechanical complexity. The concept of support of cooling the es ...
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Journal articleIEEE Transactions on Magnetics · January 1, 1975
Gas-cooled cryogenic electric current leads which are operating at high ratios of current to mass flow are commonly used to supply electric current to superconducting magnets. Loss of coolant flow under such operating conditions will result in destruction ...
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Journal articleCryogenics · January 1, 1974
The minimum theoretical refrigerator power for cooling mechanical supports for a cryogenic apparatus is determined with the calculus of variations. A mathematical approach is developed that can be used to evaluate the thermal performance of any mechanical ...
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Journal articleCryogenics · January 1, 1974
This report identifies properties to be considered when selecting materials used in construction of torque tubes for rotating superconducting field windings in electrical machinery. The main design requirements are stated and the groups of material propert ...
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Journal articleAdv Cryog Eng · January 1, 1974
A research group at the Massachusetts Institute of Technology, supported by the Edison Electric Institute, has been studying the application of superconductors to the rotating field windings of alternators since early in 1967. Two machines have been constr ...
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