Experimental study of plate type air cooler performances under four operating modes

Abstract

To reduce the chiller energy consumption in a central air-conditioning system, a heat exchanger, acting as an air cooler, can be installed before an air handling unit to pre-cool the fresh air by recovering cooling capacity from exhaust air. However, studies on evaluating the performances of air cooler under condensation condition are limited. Therefore, an experimental study was conducted to evaluate the plate type air cooler performance under four operating modes (dry/wet mode, low/high air humidity). Under dry operating mode, the air cooler serves as a traditional air cooler; while under wet operating mode, it works as an indirect evaporative cooler (IEC). The cooler dynamic performances during different operating mode transition were investigated. The steady performances under different parameter influence were also comparatively studied. The results show that wet operating improves the sensible and latent cooling capacities of air cooler significantly. Condensation takes place under high humidity inlet air, results in decreasing of sensible efficiency but increasing of latent efficiency and total heat transfer rate. The coefficient of performance (COP) of IEC is higher than that of traditional air cooler under the same testing configuration. The highest COP can reach 9.0 and achieved under wet operating mode with condensation.