Development And Simulation Of Heat Pump Air Conditioning System For Pure Electric Vehicle

After comparing and analyzing the current heating methods of pure electric vehicle,this paper determined the heat pump air conditioning system with large energy efficiency ratio and low cost as the research object.At present,ordinary heat pump air conditioning system has many problems under low temperature conditions,such as severe reduction of heating capacity,high exhaust discharge temperature of the compressor,and frosting on the surface of the outdoor heat exchanger.In order to improve the heating performance of the system in low temperature environment,the main work includes:1.This paper proposed a new type of heat pump air conditioning system for pure electric vehicle with refrigerant R134 a,applying flash technology and combining driving motor coolant as additional heating source.Further,the overall design of the system was carried out,and the performance index was determined: 5200 W heating capacity can be generated in an environment of-15 ? to maintain a temperature of 20 ? in the vehicle interior,and the system COP can reach 1.5.At the same time,preliminary design and selection of main components such as compressors and heat exchangers were carried out,meanwhile the model and basic structural parameters were given.2.Using MATLAB to write the simulation program(M file)including the working medium and the main components in the system,verifying the correctness and reliability of each model through the experimental data(the relative errors between the simulation results and the experimental data of each model are within 15%),the user interface was designed with Simulink's function modules and subsystem functions,and a general simulation module library for the pure electric vehicle heat pump air conditioning system is established.3.Based on the sequential module method,the simulation algorithms of the common heat pump air conditioning system and the new heat pump air conditioning system are designed respectively.The heating performance of each heat pump under different working conditions was simulated.The results showed that the new heat pump air conditioning system has better performance under low temperature conditions.In particular,when the outdoor temperature is-15 ?,compared with the conventional heat pump air conditioning system,the discharge temperature of the compressor in the new heat pump air conditioning system is reduced by 16.9 ?,the heating capacity is increased by 14.2%,and system still has a COP value of 1.65.4.In order to improve the performance of the new heat pump air conditioning system under low temperature conditions,the compressor frequency conversion technology is used to increase the mass flow rate of the refrigerant in the system,and the influence of the compressor speed on the system performance was simulated and analyzed.The power increases as the speed increases.In particular,when the outdoor temperature is-15 ?,the heating capacity and input power increase by 19.45% and 18.77%,respectively,with the increase of the compressor speed by 1000r/min,which provides a basis for parameter matching of the system.