A1D-3D Coupling Numerical Simulation For Vehicle Thermal Management System

Vehicle thermal management was proposed because of energy crisis, increasingly stringent emissions regulations and requirements to improve the automotive comfort. The work relies on the National Science and Technology Support Program,"Development of Commercial Vehicle Parallel Hybrid System" and school-enterprise cooperation projects "Calculation and Thermal Management Analysis of Commercial Vehicles and Hybrid Electric Bus Powertrain".In this paper, the performance of thermal management system is studied by1D-3D coupling calculation in an ambient temperature of38℃, when the vehicle works at the maximum power or maximum torque conditions in low range (block II) and full throttle for a bng time.The one-dimensional calculation is used to determine the geometry and arrangement mode of the main cooling components and provide the relevant boundary conditions for the3D calculation. The3D calculation could get the engine compartment temperature distribution and the flow field of the vehicle; ensure the flow and the heat transfer process of the thermal management system is reasonable; ensure the temperature of the ECU and other key components meet the design requirements. Three-dimensional calculations could provide the boundary conditions which is difficult to obtain for one-dimensional calculation. Due to the irrational structure of the original vehicle’s engine compartment, there is hot air reflow resulting in high-temperature region at the entrance of the radiator. The improved structures reduce the temperature and make it meet the requirements. Vehicle speed has little effect on the wind into the back-end cooling module when the fan is working.The method of improving the shorting of separate one-dimensional calculations or3D calculations is studied in this paper. The influence of import structure and fan can be simulated by turning the3D calculation result of pressure and velocity distribution into the resistance matrix. The influence of import and export’s temperature difference on heat transfer can be simulated by defining variable volume heat source of porous media through UDF. The coupling calculation can improve the accuracy of the vehicle thermal management simulation; make the simulation results c loser to the actual situation, which will provide a reference and guidance for the design of the thermal management system.