Analytic approach for the evaporative cooling performance of flat membrane cells

Owing to improvements in the quality of life, the importance of devices for controlling indoor temperatures is increasing. However, devices based on current technology cause environmental problems, and there has been a growing global awareness regarding the requirement of innovative changes in cooling systems. Among such systems, those based on evaporative cooling have been widely studied considering their high performance and eco-friendliness. Here, we propose an evaporative cooling system with hydrophobic porous membrane sheets that enhance cooling performance. In the experiments, we prepare a unit cell with an air channel and a water reservoir placed in parallel and separated by the flat membrane sheet. Compressed air is used to evaporate water through the pores, which cools the air flowing out of the cell. To investigate the parametric dependency, we alter the flow rates and the channel gap size of the cell. Considering the mechanism, we establish analytical solutions that predict the evaporative cooling rate and the temperature drop. For all cases, the experimental results show good agreement with the theoretical values. In addition, another system on a bench scale is designed and manufactured to estimate the practical applicability of the theory. Similar to the previous case, the experimental performance is also well predicted by the same theory. Given that no existing theory can delineate the effects of key parameters, flow rate and channel gap size on the cooling performance, the findings of this study are important as they can establish new avenues for research on evaporative cooling systems in the future.