Truck Thermal Management Research And Improvement By Applying Joint 1D/3D And Coupled Thermal Simulation

In the engine compartment,the engine powertrain,cooling system,intake and exhaust system,electrical and electronic systems are all core components of the car.To sufficiently cool and effectively run the heating components,it is necessary to match the engine cooling system and the intake grille as well as the arrangement of the components in the cabin in an optimal way.The process is called thermal management of the engine compartment.In this paper,the one-dimensional / three-dimensional coupling method was put forward to obtain the heat dissipation characteristics of the engine compartment,which was used to analyze the cooling system of a commercial truck engine with different operating conditions.Coupled heat transfer analysis was used to get the cabin temperature distribution considering the factors such as the convective heat transfer,radiation and conduction.The main research work and conclusions are as follows:(1)Based on STAR-CCM + software,the simulation model of vehicle and engine compartment flow was established,and the flow heat dissipation inside the engine compartment was simulated.By using the method of wrapping and mesh reconstruction,the polyhedron mesh is adopted to reduce the preprocessing time,reduce the number of grids and save the computing resources.(2)The one-dimensional / three-dimensional coupling analysis method was used to analyze the engine cooling system.Firstly,the one-dimensional heat transfer analysis model of the engine cooling system is established.Then,the three-dimensional flow field calculation results are taken as the flow boundary of the one-dimensional model.The cooling system under different working conditions are analyzed to provide thermal boundaries for the subsequent heat transfer analysis.Finally,the airflow of the heat exchanger obtained by one – dimensional method,CFD method and coupling method is compared and analyzed,and the feasibility of the analytical method is verified.(3)Based on STAR-CCM + and RADTHERM software,the coupling heat transfer analysis model is established.Firstly,the initial fluid temperature field of the engine compartment is calculated on the basis of STAR-CCM + three-dimensional flow field simulation.The results of temperature field are taken as the boundary conditions of RADTHERM three-dimensional heat transfer model by data mapping.Then the calculation results are taken as the temperature boundary of the three-dimensional flow field.The stable convergence result is obtained by several iterations.Finally,the influence of the number of iterations on the calculation results is studied.The results show that the results converge after three iterations.(4)Based on the coupled heat transfer analysis model of the engine compartment,the flow and heat dissipation characteristics of the engine compartment under different working conditions are analyzed.The results show that the cooling air above the radiator is not fully utilized,and exist edge leakage problems.In the lower area of the intercooler,there are serious reflow under different working conditions that will affect the cooling performance of the intercooler.High-speed conditions 4 is the highest heat load conditions,and oil tubing,drying tank,compressor are overheating.(5)In order to solve the above problems,some improvement measures are puts forward,analyzed and validated.By installing the baffle at the top of the radiator and below the intercooler,strengthening the cooling front end seal,the problem of hot air reflow under the intercooler is solved according to the results.The radiator and the intercooler air flow increased by 2.88% and 15.38% compared with the original program,so the engine compartment heat dissipation performance has been improved.