Simulation And Experimental Study On Heat Pump Air Conditioning System For Pure Electric Vehicles

Compared with vehicles driven by gasoline engines, pure electric vehicles is a kind of new energy vehicles. The pure electric vehicles use a single electric heat source. Its structure is relatively simple and has the characteristics of environmental-protection and energy-efficiency. Due to the capacity of unit storage battery is too little, the vehicles driving distance will sharply decrease with the use of air conditioning system. For heating the general heat pump air conditioning system will occur following problems: the compressor discharge temperature too high, the outside heat exchanger under frosting, system performance attenuates seriously even stop. In order to reduce the discharge temperature and improve the heat transfer performance, a heat pump air conditioning system of low pressure hybrid gas has been designed. The system mathematical model is based on these following models, thermal state parameter model of refrigerant and wet air, and the main components models.The discharge temperature, heat transfer capacity and COP have been calculated under the cooling and heating mode of the heat pump air conditioning system. The errors are acceptable compared with experimental data. Analysis from the variable speed compressor, the outside ambient temperature and air volume, conclusions are drawn as follows: the heat pump air conditioning system of low pressure hybrid gas is more stable and efficient, and the system can meet the demand of electric vehicles in low temperature environment. At the same time, the model possesses a good precision and the results have a certain degree of guidance for the development and improvement of the whole system.Form the view of improving heat transfer capacity, the air side heat transfer coefficient and reducing air-side pressure drop, louver-pitch, fin-pitch and louver-angle were optimized based on the mathematical model of laminated heat exchanger. The results are LP=1 mm, FP= 1.5 mm, La=30 degree. Simulation results show the heat exchanger increased about 6.9% and refrigerant side pressure drop reduction rate reached 10%. These heat methods have reference to engineering practice for the design and optimization of heat exchanger and other components.