The Experiment And Performance Analysis Of Dual Source Heat Pump In Electric Vehicles

Under the background of global environmental degradation and serious energy crisis,Electric vehicle has become a hotspot due to its advantages of low noise,low emission and high energy efficiency.It also presents a new challenge for the research and development of the air conditioning in electric vehicle.Compared to the traditional fuel vehicles,There is no engine waste heat in electric vehicles and the two-way heat pump air-conditioning system is needed;At the same time the battery needs cooling to control in the appropriate temperature range;At last,because of the relationship to mileage,energy efficiency ratio is more valued in electric vehicle heat pump system.The main research contents and results are as follows:(1)The temperature characteristic of the battery and motor is studied,and the relationship between the heat dissipation rate of the battery and motor to the vehicle speed was fitted.(2)Numerical simulation for air flowing through given heat exchangers was carried out under variable car speed and fan speed.It turns out that speed and fan speed can significantly increase the amount of ventilation of two radiators,the radiator which closes to the fan is more not uniform than that closes to the entrance of the radiating body.At the same time,there will be a vortex in the air inlet,and a sharp rise in wind speed at the air outlet.(3)The steady state simulation model of the main components and the system of the dual heat source heat pump system for electric vehicles is established.Compared with the experimental results,the error of the heating capacity is less than 15%,which proves that the model can be used for the prediction and performance analysis of the system.(4)The experiments in both cooling and heating are carried out including the charge test,the expansion valve opening test,the variable speed test,performance test with simulated heat,temperature rise test.It shows that the optimal charge amount of dual heat source system is 800 g,and there is an optimal expansion valve opening to obtain the optimal COP;the heat pump system can significantly improve the heat and efficiency of the automobile heat pump.The heating capacity increases significantly with the increase of the speed of the vehicle,the power of the compressor is reduced,and the COP is greatly increased.In 35 ?rated refrigerating condition,the cabin temperature can stable to 29.76 ? in 300s;in 7? rated heating condition,the cabin temperature can stable to 25.10? in 300 s.(5)The exergy analysis showed that in 2 ?and 35?,The compressor accounts for the most ratio of exergy loss which reaches to 46.04%-50.07%.And condenser reaches to 30.09%-33.40%.the efficiency improvement of the system should be focused on the compressor and condenser.