Fresh Air Pre-cooling and Energy Recovery by Using Indirect Evaporative Cooling in Hot and Humid Region – A Case Study in Hong Kong

Evaporative cooling (EC) is an energy efficient and environmental friendly technology which uses water evaporation to absorb the heat from surroundings and produce cooling air. EC has limited application cases in hot and humid regions because of the relatively low cooling capacity. In recent years, the study on hybrid EC and traditional mechanical cooling becomes the trend to break the region limitation of the technology. This paper carries out a case study for applying the Regenerative Indirect Evaporative Cooling System (RIECS) to an all-fresh-air hybrid air-conditioning system of a wet market in Hong Kong. The condense water from an air-handling unit (AHU) is collected and used as cooling medium sprayed onto the heat exchanger of an IEC equipment. At the same time, the contaminative and exhausted air from the wet market returns to the IEC equipment to cool the intake fresh air, so that the fresh air pre-cooling before it enters to the AHUs is realized. The energy saving and economic efficiency were analyzed and compared among RIECS, rotating heat recovery wheel system and the A/C system without heat recovery. The results show that RIEC system has the largest annual energy saving potential with a payback period of 2.9 years, which shows a great potential of its application in Hong Kong.