Design And Performance Simulation Of Heat Pump Air Conditioning System For Pure Electric Passenger Car

Since the beginning of the21st century, new energy vehicles such as the hybrid electricvehicle (HEV) and pure electric vehicles (EV), have started to enter the market and graduallyreplace the original pure internal combustion engine vehicles. Like all conventional cars, newenergy vehicles need a comfortable driving and riding environment, that is, an air conditioningsystem needs to be equipped to increase the comfort ability. As for the traditional internalcombustion engine vehicle, winter heating is provided by the engine cooling system and the PTCthermistor. However, for new energy vehicles, there isn’t enough heat provided by the enginecooling system or there’s no engine at all. They can only rely on the heat resistance of the PTC,which will consume30%to40%of the entire power. So it will be of great significance for newenergy vehicles such as HEV, EV and PEV to save energy and improve the battery life of vehiclemileage by developing a new efficient heating system.This article carried out principle analysis and parts selection, established the simulationmodel by using R744as the study object, and adds the motor cooling water, a possible heatsource, to overcome problems such as the low temperature of the air heat source outside the carin winter. Then this heat pump system is embedded in the vehicle simulation software ADVISOR,and by comparing with the heating effect of the PTC thermal resistance, the heating performanceof R744heat pump whose heat sources are electric vehicle driving motor cooling water and theair, its influencing factors and its impact on the vehicle performance can be verified.First of all, this investigation chooses R744heat pump whose heat sources are electricvehicles’ driving motor cooling water and the air as the study object on the basis of the researchinto the existing programme of new energy automobile’s air conditioning heating system homeand abroad and the combination of the characteristics of the pure electric vehicle itself.Then, acalculation of the working environment of the automobile’s air conditioner in winter and the heatload is carried out by taking a B-class car as the study object. Based on the calculating result ofthe heat load, the R744refrigerant thermodynamic cycle condition can be made certain. Next isto make selections and the matches of key parameters for key components of the heat pump systems---the electric compressor and internal and external heat exchanger. Simulation models oftheses devices are built in the MATLAB/SIMULINK environment and a fuzzy control strategy isdeveloped based on the temperature changes (Tc)and the temperature change rate(Tcs). Finally,by embedding the heat pump system in the vehicle simulation software ADVISOR, the originalvehicle drive motor model of cooling water is modified. A comparison of the heating effect andthe energy consumption with the thermal resistance of the PTC is made by the simulation ofurban conditions in the ambient temperature from0to-20℃. To study the effects of the motorcooling water on R744heat pump’s heating performance, a comparative analysis is done.Namely: if there is driving motor cooling water as the heat source or if not, what the heatingeffect of the heat pump system, the efficiency ratio COP of the electric compressor and theimpact on the vehicle energy consumption performance and the driving motor will separately be.Finally the advantages of R744heat pump air conditioning with electric vehicle driving motorcooling water and air as its heat sources is verified.The key point of the heat pump performance simulation for R744lies in the confirmation ofR744refrigerant thermodynamic cycle and the parameter matching for each component, whilethe innovative point lies in adding the motor cooling water which recycles part of the motor’sheat loss, improves the cooling efficiency of the drive motor and improves the thermal efficiencyof a heat pump air conditioning system.