The Evaluation method of HVAC System’s operation performance based on Energy Flow Analysis and DEA

An energy flow model of an airport terminal’s HVAC system is established in this paper. Based on energy flow model, the exergy efficiency, exergy loss and exergy cost distribution ratio of each component are calculated and analyzed by the energy flow model. Optimization method and exergy balance equations are used to calculate the lowest exergy loss of HVAC system under different operation conditions. Data envelopment analysis (DEA) method is then applied to obtain the benchmarking frontier of lowest exergy loss of HVAC system, and the frontier line illustrates the optimum operation performance which the system can reach, namely the ideal operation level. In order to measure the gap between actual operation level and ideal operation level, a new index—control perfect index (CPI) is defined by the ratio between the actual exergy loss and exergy loss of ideal operation level of HVAC system, and it can reflect control influences on operation performance of HVAC system. Thus, a new evaluation method is presented which regards ideal operation level as the benchmark and uses CPI to evaluate actual operation performance of HVAC system. Two kinds of control strategies, optimal supply chilled water temperature reset strategy (CHW Strategy) and optimal load allocation control strategy (Load Allocation Strategy) are implemented to validate this evaluation method. Test’s results show that Load Allocation Strategy can improve the operation performance of the system more greatly than the CHW Strategy. This evaluation method not only can evaluate the operation performance of HVAC system, but also can indicate the direction of optimal control of HVAC system.