Design Of Performance Analysis Platform For Electric Vehicle Heat Pump Air Conditioning System

With the development of social economy and the improvement of environmental requirements,the auto industry has entered a period of unprecedented change.Electrification,intelligence,networking,sharing and internationalization have become main developing trend.There is a great difference between the power source of electric vehicles and that of conventional cars.In order to adapt the changes that results from the replacement of power source,the automotive air conditioning system also needs to make changes in form.The thesis designs a set of heat pump air conditioning system with multi-working modes such as cabin cooling and heating,battery cooling and heating,demisting,defrosting and PTC heating modes based on the functional requirements of electric vehicle air conditioning system.The system has better cabin thermal comfort in defrosting mode.Now most studies on the heat pump air conditioning system are mainly based on the first law of thermodynamics.To remedy that the exergy analysis of heat pump air conditioning system is carried out,and the optimization direction of heat pump air conditioning system is summarized in the thesis.In order to save the time and costs spent on analyzing the system performance,a heat pump air conditioning system performance simulation platform is designed and built,which can be used to analyze the system performance in different working modes.The main research contents are as follows:(1)Set up simulation model of heat pump air conditioning system main components,including scroll compressor,parallel-flow condenser,parallel-flow evaporator,plate evaporator,expansion valve model,then the RBF neural network model is established for compressor efficiency prediction.The accuracy of parallel-flow condenser,parallel-flow evaporator and plate evaporator simulation model is verified by experiments,the errors of model are within the allowed range.The performance analysis of parallel-flow evaporator and parallel-flow condenser in alterative operating conditions is carried out.The research indicates that air velocity,inlet air temperature and refrigerant mass flow have a significant impact on the performance of parallel-flow heat exchanger.The performance analysis of plate evaporator in alterative operating conditions is carried out.The research indicates that the heat transfer of plate evaporator increases with the increment of coolant flow rate,but when it increases to a certain degree,the improvement effect will weaken.(2)The experiments of heat pump air conditioning system designed in the thesis in cabin cooling mode,battery cooling mode,cabin and battery mixed cooling mode and cabin heating mode are carried out and the exergy analysis of experiment results is carried out.The results indicate that the compressor is always the main source of system exergy loss.The exergy loss distribution of heat pump air conditioning system is almost the same when the battery thermal management system integrated into the heat pump air conditioning system in cabin and battery mixed cooling mode.The performance of heat pump air conditioning system is better than that of PTC heater in cabin heating mode.The degree of exergy efficiency improvement of the alternative mode is discussed at all operating conditions in cabin heating mode.The results indicate that the optimization effect using heat pump air conditioning system to replace PTC heater is obvious at the lower compressor speed,lower surrounding temperature and higher internal condenser air flow rate.(3)Build heat pump air conditioning system simulation model in single evaporator mode and dual evaporator mode based on the component simulation model and establish electric vehicle heat pump air conditioning system designed in the thesis performance simulation platform by MATLAB.The platform can analyze the heat pump air conditioning system performance in cabin cooling mode,battery cooling mode,cabin and battery mixed cooling mode and cabin heating mode,and the experiment results are used to verify the model accuracy.The results show that the maximum error range between experiment and simulation of compressor power,heat transfer and system COP is 0.34%?10.09% in different working modes,which meets the accuracy requirements and can be used in the research of heat pump air conditioning system.The platform is also used to analyze the performance of heat pump air conditioning system in alterative operating conditions.