Research On Evaluation Model And Application Of Heat Pump Air Conditioning System With Waste Heat Recovery For Pure Electric Vehicle

Heat pump air conditioners have been widely used in the field of electric vehicles due to their high efficiency and energy saving advantages.By using the waste heat of the vehicle drive system,waste heat recovery technology can effectively improve the low temperature performance of the heat pump air conditioner while improving the energy efficiency of the vehicle.At present,there are various schemes for heat pump air-conditioning systems with waste heat recovery.The traditional Coefficient of Performance(COP)evaluation index does not consider the power consumption of other parts of the system and the influence of weight,and it is impossible to evaluate the system in terms of cost and carbon emissions.In this paper,a comprehensive evaluation model of heat pump air conditioning system with waste heat recovery is proposed and applied.The main research contents and result are as follows:First,designed a heat pump air conditioning system with waste heat recovery consisting of a heat pump subsystem and a waste heat recovery subsystem.Build a COP model according to the thermal load of the cabin and the power consumption of the compressor.Build a comprehensive COP model according to the power consumption of the system components and the power consumption of the vehicle caused by the weight of the system;build a comprehensive cost model according to the one-time input cost of the system components and the power consumption cost of the system operation process;build a life cycle carbon emission model according to the stages of system manufacturing,transportation,operation,recycling and scrapping.Verify the accuracy of the heat pump air conditioning system model.Secondly,explore the impact of main operating parameters such as ambient temperature,waste heat,and average daily driving time on the comprehensive evaluation index.The results show that: as the ambient temperature rises and the waste heat increases,the system’s comprehensive COP increases,the comprehensive cost and the life cycle carbon emission decrease;as the average daily driving time increases,the comprehensive COP remains unchanged,the comprehensive cost and the life cycle carbon emission increase significantly.Compared with the traditional COP index,the comprehensive evaluation index has wider evaluation dimensions and more comprehensive evaluation content.Next,a comprehensive evaluation of several typical waste heat recovery schemes is carried out.The results show that: when the ambient temperature is low and the waste heat is small,the comprehensive evaluation result of the condenser side waste heat recovery scheme is the best;when the ambient temperature is high and the waste heat is large,the comprehensive evaluation result of the refrigerant side waste heat recovery scheme is the best;the comprehensive evaluation result of the refrigerant side waste heat recovery scheme is better under different average daily driving hours.Finally,to improve the performance of the system in a low temperature environment,a new type of waste heat recovery scheme is proposed,and the waste heat recovery control strategy is formulated.Compare the carbon emissions of the new waste heat recovery scheme and the refrigerant side waste heat recovery scheme in three cities with typical climates under Worldwide Light-duty Test Cycle(WLTC).And take Harbin as an example to further carry out the comprehensive evaluation research of the new waste heat recovery scheme.The results show that the new waste heat recovery scheme has better low temperature adaptability than the refrigerant side waste heat recovery scheme.The new waste heat recovery scheme has an average annual comprehensive COP increase of 18.9%,a 2.1% increase in comprehensive cost,and a 14.7% reduction in life cycle carbon emissions compared to the refrigerant side waste heat recovery scheme.