Improved energy performance of air-cooled chiller system with mist pre-cooling Mist improvement on air-cooled chillers

This study investigates how to lower the dry bulb temperature of outdoor air via mist pre-cooling to enhance the coefficient of performance (COP) of an air-cooled chiller system. Based on standard chiller models in commercial simulation software DOE-2E, a modified model was made to analyse how the chiller COP varies under two different condensing temperature controls with mist pre-cooling of air entering the air-cooled condenser. Drawing on the model calibrated by manufacturer and operating data, it was estimated that around 18% decrease in the electricity consumption could be achieved by coupling floating condensing temperature control with an optimal mist generation rate, with regard to a chiller system serving a hotel in a sub-tropical climate. Remarks have been made on how optimal mist control can be implemented to maximize electricity savings while reducing surplus mist carrying over the condenser coil. (C) 2010 Elsevier Ltd. All rights reserved.