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Title: Performance evaluation of oil-free chillers for building energy performance improvement
Authors: Yu, FW 
Chan, KT 
Sit, RKY 
Yang, J 
Keywords: Coefficient of performance
Data envelopment analysis
Oil-free chillers
Issue Date: 2015
Publisher: Elsevier
Source: Procedia engineering, 2015, v. 121, p. 975-983 How to cite?
Journal: Procedia engineering 
Abstract: This paper investigates how to improve the energy performance of central air-conditioning systems by using oil-free chillers. Three conventional water-cooled centrifugal chillers of equal capacity were replaced by three oil-free chillers of the same capacity in an existing system. Operating data for performance evaluation were logged at 1-hr intervals for over one year before and after the replacement. The superior coefficient of performance (COP) of oil-free chillers with variable speed control brought an energy saving of 9.6% in the total electricity consumption of a shopping arcade when they operated for a wide range of system cooling demands. Results of data envelopment analysis gave an average technical efficiency of 0.6 which ascertains an opportunity for performance enhancement. The system COP can be further improved by tightening the control in the temperature of supply chilled water and implementing even load sharing among chillers to meet the overall system capacity.
Description: 9th International Symposium on Heating, Ventilation and Air Conditioning, ISHVAC 2015 Joint with the 3rd International Conference on Building Energy and Environment, COBEE 2015, 12-15 July 2015
ISSN: 1877-7058
DOI: 10.1016/j.proeng.2015.09.065
Rights: © 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (
The following publication Yu, F. W., Chan, K. T., Sit, R. K. Y., & Yang, J. (2015). Performance evaluation of oil-free chillers for building energy performance improvement. Procedia engineering, 121, 975-983 is available at
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