Exploration of interactive thermal influence characteristics of power and air conditioning system based on 1D/3D coupling calculation in electric vehicle underhood

•The underhood thermal interaction problems of EVs are serious.•The underhood thermal management system framework with the modeling process is built.•A 1D/3D coupling model for underhood thermal interaction system is established.•The thermal interaction is studied by varying loads of HVAC and power system.•The thermal interaction characteristics include different heat exchanger layouts. The thermal problems in the underhood are serious in the integrated thermal management of electric vehicles. The interaction of the heat dissipation components in the underhood affects the heat exchange and working performance, which affects its driving range and safety. This paper takes the interactive thermal influence into consideration between the battery, motor and air conditioning system, builds an underhood thermal management system framework of electric vehicles, and establishes a 1D/3D coupling model for the integrated systems. Only the components in the underhood are studied in 3D. The impact of load change of the air conditioning system and power system on heat transfer performance of another system is studied under different heat exchanger layouts. The results show that the cooling effect of the power system decreases with the load of the air conditioning system increasing when the condenser is placed in front of the radiators. When the condenser is behind the radiators, the air conditioning system load change has no significant effect on the heat dissipation effect of the power system. For both arrangements, the load change of the power system has an evident influence on the refrigeration process of the air conditioning system. The dissipated heat of the condenser decreases as the power system load increases, and the COP increases gradually. At the same time, the cooling performance number is introduced to evaluate the heat dissipation capacity of the power system and the air conditioning system. The smaller the cooling performance number, the stronger the heat dissipation capability of the system, and vice versa, the worse the heat dissipation capability. So it can further optimize the cooling characteristics and safety of the entire electric vehicle by comprehensively considering the arrangement or the targeted optimization of the heat exchangers to improve the integrated thermal management system of EVs.