Chilled water circuit designs for in situ chiller performance measurement

Determining the full- and part-load performance of chillers through short-term in situ measurements requires complicated arrangements. It will take a long time if consistently logged performance data under normal plant operation are used instead. Chilled water circuit designs that allow the full- and part-load performance of chillers to be measured conveniently and expeditiously are presented in the paper. The circuit designs require just minor extra provisions, including the installation of supplementary pipes and fittings, and a few additional control devices. Besides making it possible to conduct full-load tests on chillers at most of the time in the year, simulation results based on a building model in Hong Kong show that part-load performance data that cover the entire capacity range of chillers can be captured in less than 2 weeks, both in hot and cold months.

Practical application: With the proposed chilled water circuit designs, the time and effort required for measuring the full- and part-load performance of new or existing chillers can be largely reduced. The method will work provided that each chiller is connected in series with a dedicated chilled water pump and the return chilled water will flow from one end of the main return pipe to another with connections to all chiller branches in between. The circuit design can be incorporated easily into new plant designs. For existing buildings, the required pipe modification work will interrupt plant operation.