Decentralized cooling and dehumidification with a 3 stage LowEx heat exchanger for free reheating

This article presents the performance study of a novel decentralized ventilation system for hot and humid climates such as found in Singapore. Decentralized ventilation has a great potential for reducing pressure losses because of the short travel distances of the air. The combination of decentralized ventilation with high temperature radiant cooling offers the potential for a very energy efficient operation of buildings in hot and humid climates and to decrease their exergy destruction. Core of the ventilation system studied is a modified design of a decentralized ventilation unit incorporating a 3-stage heat exchanger. This particular heat exchanger setup ensures sufficient cooling capacity for dehumidification and offers free energy for reheating. In the process of the air treatment, the two heat exchangers' upstream takes the roles of pre-cooling and cooling/dehumidification while the third one covers the reheating process. The results show that with the studied ventilation unit outdoor air with temperatures around 30 °C and a humidity ratio of 20 g/kg can be chilled, dehumidified and reheated such that target conditions in the supply air of 14-15 °C and 8-9 g/kg are achieved. In addition, this novel decentralized ventilation system can save around 4-5% of total cooling energy demand due to free reheating.