Performance evaluation of centrifugal chillers in an air-conditioning plant with the building automation system (BAS)

Abstract

A thermodynamic model with a novel method of describing the performances of centrifugal chillers for air-conditioning is presented. It is based on the first and second laws of thermodynamics which captures the overall entropy change due to non-isentropic compression and expansion of the thermodynamic cycle. The model gives the fundamental relation between the coefficient of performance (COP) and the cooling rates (Qe) for (a) the modulating and (b) the throttling actions of the inlet guide-vanes of the compressor. The usefulness and the accuracy of the model are demonstrated here by analysing the in situ performance of two commercial, installed centrifugal chillers of an air-conditioning plant as well as comparing the available performance data of another chiller in the literature.