Thermal performances comparison between dry-coil and wet-coil indirect evaporative cooler under the same configuration

Abstract

The indirect evaporative cooling (IEC) is an energy efficiency and environmental friendly air-conditioning device which cools the air by water evaporation. In the market, there're two kinds of IEC units, namely dry-coil IEC and wet-coil IEC. The only differences between them lie in the sequence of air humidification process and heat exchange process. In dry-coil IEC, the two processes are separated. The working air firstly being humidified and then proceed sensible heat exchange with the fresh air; while in wet-coil IEC, the two processes are simultaneous. The different arrangement may result in distinction of thermal performance. The paper presents the analytical models for dry-coil IEC and wet-coil IEC and compares their supply air temperature and cooling efficiency under the same configuration. The condensation and non-condensation statuses for both IEC types were discussed by simulation under a wide range of fresh air inlet parameters. The results show that the wet-coil IEC owns a higher efficiency and can provide lower temperature supply air either in condensation or non-condensation statuses. Besides, the efficiency of both types of IEC will be lowered once condensation occurs.