Optimal design of a regenerative heat and mass exchanger for indirect evaporative cooling

Abstract

This article presents the optimal design of a regenerative heat and mass exchanger (RHMX) for indirect evaporative cooling. The room cooling capacity which is the product of the supply air mass flow rate, specific heat of the supply air and the difference between the supply air temperature and the comfort temperature, was considered as a criterion to evaluate the cooling performance of the RHMX. The air conditions throughout the RHMX were obtained by a heat and mass transfer model. The model was validated by comparing the modeled results with the existing experimental data. The simplified conjugate gradient method was used as an optimizer to obtain the optimal performance, and to adjust the design variables, i.e. product air flow rate and working-to-product air flow ratio. The effects of the exchanger’s parameters as well as the inlet air condition on the performance of the optimized RHMX and on the values of the design variables were discussed. It was concluded that the working-to-product air flow ratio is around 0.4 under various climatic and design conditions. Moreover, the channel length and the channel height should be selected between 0.4–0.6m and 0.004–0.006m, respectively, to have a high RCC with an acceptable fan power.