Volume 7: Urban Energy Systems: Building, Transport, Environment, Industry, and Integration

On-Site Testing of Exhaust Air Heat Recovery for an All-Fresh-Air A/C System in Hong Kong Yunran Min, Yi Chen*, Hongxing Yang*

Abstract

Application of heat recovery units in building HVAC systems can significantly save the energy consumed by conditioning fresh air. The indirect evaporative cooler (IEC), used as a pre-cooling device for fresh air in the hot-humid area, recovers both latent and sensible energy from the exhaust air. In this paper, a year-around on-site performance test was carried out in a wet market located in Hong Kong. The energy performance of the two A/C systems with exhaust air heat recovery units was analyzed and compared: an IEC coupled to an AHU; a traditional heat recovery wheel (HRW) coupled to an AHU. The heat recovery of IEC and HRW were collected under typical summer operation conditions. The results show that the HRW has better dehumidification performance than IEC, but the IEC can largely reduce the fresh air temperature by handling the sensible cooling load. During the whole year, the difference in the total heat recovery between IEC and HRW is within 2%. In cooling seasons, the energy efficiency of the two systems with IEC and HRW for exhaust air heat recovery can be improved by 27.6% and 25.7% respectively.

Keywords Fresh air, indirect evaporative cooler, heat recovery wheel, air-conditioning system, building energy efficiency