Field-based Analyses on Approach Temperatures for Performance Evaluation of Centralized Air Conditioning System in a Shopping Mall Building

Abstract

This paper presents field analyses on the influences of condenser and evaporator approach temperatures of water cooled air conditioning system for a shopping mall. The mall building comprises food and non-food retail stores and uses a centralized air conditioning (AC) system to condition the entire building. The AC system comprises three chillers with the same cooling capacity. Chillers' performance parameters included power consumption, condensing and evaporating temperatures, evaporator-condenser approach temperatures, pressure drop and cooling capacity parameters were hourly recorded for a period of one year. Performance characteristics of each chiller were evaluated at different condenser and evaporator approach temperatures and regression analyses were also established to examine the correlations and influences of the approach temperatures on the chillers' performance. The analyses results showed that the increase of condenser approach temperature could increase the power consumption and reduce the coefficient of performance (COP) of the chillers. While evaporator approach temperature was found to have insignificant effect to the chiller performance. The results also showed that for the investigated chillers with condenser and evaporator approach temperatures maintained below 2 K, the approach temperatures had negligible correlation to the power consumption and the overall performance of the chillers. At this operational conditions, the water cooled air conditioning systems could operate at their best possible performance.