Matching Design And Optimization Of Commercial Vehicle Cooling System

Commercial vehicles are mainly used to transport goods.Most commercial vehicles are equipped with diesel engines,which have a large torque output.Diesel vehicles have the advantages of large load-bearing mass and good climbing performance.The cooling system is used to control the temperature of the engine.In recent years,the power of the engine has gradually increased.Affected by cost reduction and weight reduction,the space in the engine compartment has become increasingly compact.Therefore,the performance requirements of the cooling system of the whole vehicle are getting higher and higher.Improper matching of the main cooling elements and unreasonable airflow in the engine room will result in insufficient cooling system performance.In severe cases,the radiator will have "pot boiling" problems.Under the condition of limited space,the development of a high-efficiency and energy-saving cooling system with reasonable airflow makes its design more and more difficult.Therefore,in the early stage of product development,focus should be placed on the research of engine room thermal management.This article is based on a newly developed commercial vehicle as the research object,and based on the current design experience and theoretical calculations,the preliminary design of the cooling system is carried out.According to simulation calculation,the outlet water temperature of the engine of the original scheme exceeded the standard,so a special project team was set up to optimize and upgrade the cooling system.The main research content is introduced below:（1）Design and model building of cooling system.The matching and selection of the key components of the cooling system of the vehicle is carried out initially,the bench test of the engine and the key cooling components and the test parameters are introduced,and the digital model of the whole vehicle and the cooling system is finally built.（2）Simulation analysis of cooling performance.First,using STAR-CCM+simulation analysis,it is found that the unreasonable gas flow direction in the engine room and the high temperature of the cooling module are the main reasons that affect the insufficient cooling performance.Then the KULI one-dimensional simulation calculation is performed.The simulation results show that the engine outlet water temperature at the maximum power point is 108.9℃,which exceeds the design target requirement by 105℃;the maximum torque point engine water outlet temperature is 112.9℃,which exceeds the design target requirement by 108℃.The original plan does not meet the requirements.（3）Optimize the cooling system plan and simulate analysis.Compare and analyze the cooling performance of different core thicknesses of the radiator,different opening areas of the air intake grille,different backflow prevention baffles for the radiator,whether to increase the radiator baffle,condenser baffle,and different structure windshields,etc.on the cooling performance Impact.Through the simulation results,it is found that increasing the thickness of the radiator core,increasing the opening area of the air intake grille,optimizing the backflow prevention baffle,adding the radiator,condenser baffle,and optimizing the wind shield can significantly improve the performance of the cooling system.After the project team reviewed and formed the final optimization plan,and then performed one-dimensional simulation calculation on the optimization plan,the engine outlet water temperature at the maximum power point was 101.2℃,and the engine outlet temperature at the maximum torque point was 100.5℃.The optimization plan met the requirements.（4）Prototype test verification.The trial-produced sample car was subjected to a thermal balance test,and the optimized solution was at the maximum power point of engine water temperature of 99.1℃;the maximum torque point of engine water temperature was 96.7℃.The heat balance capacity of the whole vehic le met the design requirements,and the optimized program had obvious effects.Comparing and analyzing the test results and simulation results of the optimization scheme,the engine outlet water temperature deviates 2.1%at the maximum power point and 3.9%at the maximum torque point.The deviation between the prototype test results and the simulation results is less than 5%,which proves that the simulation analysis method adopted in this paper is reliable and can be used to guide the development and design of subsequent models.