Xin Xu

Evaporation involving multiple parallel thin sheets is common in many engineering and natural drying processes. In this study, a configuration is considered in which wet sheets are arranged with equal spacing inside a confined space to enhance the overall drying rate. The spacing between neighboring sheets plays a key role, as it controls the balance between local mass transfer on each sheet and the effective use of the available space. An evaporative mass transfer model is developed using asymptotic analysis by examining two extreme cases: near-zero spacings and wide spacings. The dependence of the total mass transfer rate on the spacing length is obtained for the two regimes, and an optimal spacing that maximizes the drying rate per unit volume is derived. Finite element simulations are performed to validate the theoretical predictions and match well with the analytical results. The results provide physical insight into spacing effects in evaporation-dominated systems and may be useful for the design of mass transfer processes involving arrays of parallel sheets, such as textile and paper drying, food dehydration, and solvent removal from substrates.