energy flow analysis, DEA, HVAC system, evaluation method, control perfect index
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 least exergy loss of HVAC system under certain operation condition, which is defined as the near-optimum operation level. DEA method is then applied to obtain the benchmarking frontier of near-optimum operation levels, and the frontier will illustrate the ideal operation level under overall operation conditions. 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 air temperature reset strategy (SAT Strategy) and optimal load allocation control strategy are implemented to validate this evaluation method. Test’s results show that optimal load allocation control strategy can improve the operation performance of the system more greatly than the SAT 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.