Research On Heating Performance Of Pure Electric Vehicle Heat Pump Air Conditioning System Based On R1234yf

Nowadays,more and more people recognize the necessity of low carbon living,the problem of traditional vehicles occupying a lot of energy and polluting the environment is becoming more and more serious.The important measure to solve the above problems about to the development of electric vehicles.In the electric vehicle system,the air conditioning system as an integral part of it is also receiving more and more attention.At the same time,the refrigerant commonly used in automotive air conditioning will cause a greenhouse effect on the environment.And the new environmentally friendly refrigerant R1234 yf can be solved.It is of great significance to study the energy-saving,efficient and environment-friendly operation of electric vehicle air conditioner with environment-friendly refrigerant R1234 yf.For pure electric cars,a set of pure electric vehicle heat pump air conditioning system based on R1234 yf is designed and built,which solves the problem of poor operation efficiency of pure electric vehicle air conditioning in winter.Based on the principle of quasi two-stage compression cycle,the system is equipped with low-pressure and medium pressure air replenishment system.The refrigerant adopts environment-friendly refrigerant R1234 yf.The heating experiment is carried out with different parameters as variables,and the data are analyzed and recorded.The experimental results show that under the working condition of the compressor,the exhaust heat of the compressor will increase,and the cop will decrease with the increase of the exhaust temperature of the compressor;Increase the air supply volume of the fan of the heat exchanger inside the vehicle,and the heating capacity and COP of the system will increase;The fan in the vehicle has little impact on the system;The overheating degree of electronic expansion valve is too low or too high,which will cause the decrease of heating capacity and COP of the system;The lower the ambient temperature outside the vehicle,the lower the heating capacity and COP of the system.After the system adopts low-pressure and medium pressure air supply system,the heating capacity and COP are improved.When the ambient temperature outside the vehicle is low,the improvement effect of low-pressure and medium pressure air supply technology is more obvious.The analysis of the experimental data shows that the heating performance of the experimental system is better when the compressor speed is set to 3600r/min,the air supply volume of the in vehicle fan is set to 100%of the rated air volume,the air supply volume of the out of vehicle fan is 90%,the set value of the main expansion valve is 5K and the set value of the make-up expansion valve is 10 K.When the ambient temperature is-7? and the interior temperature is set to 20?,the heating capacity of the heat pump air conditioning system is 2.824 k W and the COP is 1.994 under the condition of low-pressure air replenishment,which is 8.2% and 7.8% higher than that without air replenishment respectively;Under the medium pressure air supply condition,the heating capacity of the heat pump air conditioning system is 3.223 k W and the COP is 2.024,which is14.6% and 9.4% higher than that without air supply respectively,which can meet the heating demand of pure electric vehicles in low temperature environment in winter.