CONCEPT OF IRREVERSIBILITY IN HEAT EXCHANGER DESIGN: COUNTERFLOW HEAT EXCHANGERS FOR GAS-TO-GAS APPLICATIONS.
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 differences. The irreversibility (entropy production) concept establishes a direct relationship between the heat exchanger design parameters and the useful power wasted due to heat exchanger nonideality. The paper presents a heat exchanger design method for fixed or for minimum irreversibility number of entropy generation units N//S. In contrast with traditional design procedures, the amount of heat transferred between streams and the pumping power for each side become outputs of the N//S design approach. To illustrate the use of this method, the paper develops the design of regenerative heat exchangers with minimum heat transfer surface and with fixed irreversibility N//S.