Study On Operation And Control Level Evaluation Method Of HVAC System Based On Analysis Of Energy-flow

The heating, ventilation and air conditioning (HVAC) systems iscomplex energy system. Its operation efficiency can be influenced by thecontrol strategies and system equipments characters. The object of evaluatingHVAC system operation is to detect the faults and the improvement potentialof its operating. So the research works about the operation and control levelevaluation method of HVAC system, it has very important and practicalsignificance to improve the operation efficiency of HVAC system.In this dissertation, a simulated model of an airport terminal’s HVACsystem is established for analyzing the operation performance of HVACsystem. A new model calibration method is presented. The virtual internalgains factor is set for increasing the calculateion accuracy of the simulationmodel by this method. According to the results of the energy efficiencyanalysis and correlation analysis between the system’s COP and the operationparameters, several optimal control strategies are presented for improving theoperation efficiency of HVAC system. The energy flow model of the HVACsystem is established based on the structural theory of thermoeconomics. Theunit exergy consumption, the object exergy efficiency and the exergy lossratio of each components of HVAC system are calculated by this energy flowmodel. According to analysis results of these parameters, the optimumpotential of each component is evaluated.Based on analysis results of energy flow, the deviation between the idealoperating level and the actual operating level of the HVAC system arecalculated and defined as control perfect index (CPI) of HVAC system. A newevaluation method is presented which setting ideal operating level as the criterion, using CPI to evaluate operation and control level of HVAC system.Based on this evaluation method, firstly, the ideal operating level undercentrain control conditions and restrain condtions are defined as “the idealoperating level (restrain conditions)”. The ideal operating level (restrainconditions) calculation model are established by the particle swarmoptimization (PSO) algorithm and energy flow model. The CPI of systemunder the ideal operating level (restrain conditions) are used to evaluate theoperation and control level of HVAC system based on different controlstrategies.Then, in order to better evaluate the operation and control level of HVACsystem and more accurately analyze the theoretical optimum potential ofHVAC system, the production frontier of HVAC system is established by dataenvelopment analysis (DEA) method. The ideal operating level based on theproduction frontier model is obtained and defined as “the ideal operating level(DEA)”. The CPI of system under the ideal operating level (DEA) is used toevaluate the operation and control level of HVAC system based on differentcontrol strategies. The theoretical maximum optimum potential of HVACsystem is obtained by this index.Furthermore, the multi-level performance evaluation model isestablished, it consists of energy flow model, the ideal operating level(restrain conditions) calculation model, the production frontier based on DEAmethod. Evaluation to the operation and control level of HVAC system isdiveide into three levels, they include the system level evaluation, subsystemlevel evaluation and component level evaluation. The evaluation model isvalidated by simulation model. The optimum potential of components, theCPI of HVAC system, and the optimum potential of each subsystem can becalculated and evaluated by this multi-level performance evaluation model.And the evaluation results can be used to give the direction to improveoperation efficiency of HVAC system.