Energy performance of chillers with water mist assisted air-cooled condensers

This paper reports how the coefficient of performance (COP) of air-cooled chillers can be improved by adopting variable condensing setpoint temperature control and using mist evaporation to pre-cool ambient air entering the condensers to trigger a lower condensing temperature. Chiller models without and with water mist system were established, and the former was validated by using measured operating data of an installed screw chiller. With the validated model, the energy performance of air-cooled screw chillers with twin refrigeration circuits and water mist system serving a representative commercial building was studied. The results reveal that the chiller COP can be changed by various degrees from -0.3% up to +72% depending on the weather and load conditions, and the annual energy consumption can be reduced by 10.9% for a commercial building in subtropical climate.