Numerical investigation of the heat and mass transfer process within a cross-flow indirect evaporative cooling system for hot and humid climates

Abstract

This paper presents an investigation on the process of heat and mass transfer within an indirect evaporative cooling (IEC) system with a cross-flow arrangement for hot and humid climates. For this purpose, a numerical model based on energy and mass balance within IEC has been developed that predicts condensation from the primary air. The numerical model is validated employing numerical and experimental data from the literature with a perfect agreement. Precise simulations are executed to observe and investigate the condensation cases, including (non, partial, and full condensation) in the dry channel. The performance of the IEC system is evaluated under variable operating conditions, including primary and secondary air velocity, inlet temperature, humidity ratio, and wettability factor. The results noted that the three condensation states in the primary air channel depend on operating conditions such as humidity ratio, inlet temperature, velocity, and wettability factor. Besides, the wettability factor greatly affects the condensation and cooling process; when the factor is reduced to 0.5, condensation is delayed; and the amount was reduced to 0.52 g/kg instead of 1.32 g/kg when the factor is 1. Also, the average temperature at the outlet increased from 20.2 °C to 23.4 °C when the factor was reduced from 1 to 0.5, respectively. Furthermore, increasing the secondary air inlet velocity enhances the condensation process as the state changes from non-condensing to condensing and the humidity ratio decreased from 14.65 g/kg to 13.7 g/kg; besides, the temperature difference and cooling capacity are also improved.