Experience of using a chilled water circuit design to expedite in situ chiller performance measurement

Abstract

A chilled water circuit design that can facilitate expeditious in situ chiller performance measurement has been adopted in a chiller plant and its effectiveness has been demonstrated. Before chiller tests commenced, the measurement accuracies of the sensors in the plant were checked by simple measurements and an analysis of the plant operation records. The analysis unveiled that the chilled water flow rate through the chillers was lower than the design flow rate and the chilled water return temperature often stayed below the design level due to excessive flow rate demand, which would hinder full load tests on the chillers. After the causes of the problems were diagnosed and the problems resolved as far as possible, measurement of the full- and part-load performance of the newly installed chillers was successfully conducted. This work demonstrated that the chilled water circuit design is effective in facilitating expeditious in situ chiller performance measurement but its use requires a properly functioning chilled water system. Practical applications: As the results presented in the paper show, the proposed chilled water circuit design is effective in reducing the time and effort required for measurement and verification of the full- and part-load performance of water chillers. This, in turn, allows more frequent chiller performance measurements to be made for detecting system or sensor faults and deterioration in chiller performance, which would help upkeep chiller energy efficiency and reliability. Described in the paper includes also several practical methods for verification of sensor accuracy and some common problems with chilled water systems where fan-coil units with on/off control are adopted.