Influence of asynchronous demand behavior on overcooling in multiple zone AC systems

The cooling demands of different zones in an air conditioning (AC) system are different (with large discrepancies) even at the same moment, and the degree of variance changes with time. This asynchronous behavior of demand greatly influences the overcooling degree in multiple zone AC systems. This paper describes the asynchronous demand quantitatively and reveals its relationship with the overcooling degree in a multiple zone AC system. The Lorenz curve and Gini index are introduced in this study and used to describe the demand characteristics. Two typical multiple zone AC systems, namely, constant air volume (CAV) and variable air volume (VAV) systems, are considered as examples, and their overcooling degree under different demand profiles are analyzed. Under different asynchronous demands, the overcooling degree in the CAV system changes from 1 to 3.5, while that in the VAV system changes from 1 to 1.5. In this paper, the influence of the regulation ability of the AC system on energy consumption is also discussed. This paper presents a new perspective to study the demand pattern and explores the method to reduce the overcooling phenomenon in multiple zone AC systems. (C) 2016 Elsevier Ltd. All rights reserved.