Application of frequency inverter in pump control to increase Chiller system efficiency: Theoretical research, experiment and practical implementation in Vietnam

Abstract

This paper presents the results of using frequency converters for chilled water pumps to improve the efficiency of the Chiller system. Through experiments conducted on the Chiller system at Ho Chi Minh City University of Technology, the results show that when reducing the power frequency supplied to the pump, the coefficient of efficiency (COP) of the Chiller system increases significantly, from COP = 1.987 at 50Hz to COP = 2.451 at 30Hz, corresponding to an increase of 23.4%. Theoretical calculations also confirm this trend with the theoretical COP at 30Hz reaching 6.421, while this coefficient at 50Hz is COP = 4.977, which is an increase of about 29% when changing the frequency from 50Hz to 30Hz. In addition, the experimental results of applying inverters to the actual chiller water pump and cooling pump system at the Palace Hotel in Ho Chi Minh City showed that the average power consumption decreased from 3.586 kWh/room/day to 3.074 kWh/room/day, corresponding to a savings of 15.37%. The results showed that the reduction in average power consumption not only helps save operating costs but also reduces the amount of CO2 emitted into the environment, in line with the trend of sustainable development. This study shows a great potential in applying inverter technology to old Chiller systems that do not use inverters to save energy without having to invest in purchasing an entire new Chiller system.