Optimum load sharing strategy for multiple-chiller systems serving air-conditioned buildings

F. W. Yu, K. T. Chan

Research output: Contribution to journalArticlepeer-review

42 Citations (Scopus)


Many central cooling systems in air-conditioned buildings have multiple chillers to meet various cooling load requirements. This paper further develops optimum load sharing strategies for the chillers in order to maximize their aggregate coefficient of performance (COP). Based on the part load performance curves of air-cooled screw chillers, it is ascertained that for two equally sized chillers operating, one should carry a full load and the other should be partially loaded to meet the system load. When two chillers of different sizes are running, the larger chiller should be fully loaded and the smaller chiller should operate at part load in order that their combined capacity satisfies the system load. Such an uneven load sharing strategy for achieving maximum COP is independent of ambient conditions and the control of condensing temperature. The variable primary flow of chilled water should be applied to chillers in order to implement the strategy. The results of this paper are useful in developing low-energy chiller plants.

Original languageEnglish
Pages (from-to)1581-1593
Number of pages13
JournalBuilding and Environment
Issue number4
Publication statusPublished - Apr 2007


  • Air-cooled screw chiller
  • Multiple-chiller system
  • Optimum load sharing


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