Matching Design And Performance Optimization Of Engine Cooling System

As an important engine subsystem,cooling system plays a significant role in the improvement of engine performance.In recent years,the heat load of cooling system is becoming higher and higher because vehicle engines tend to have more power and are combined with new technologies such as turbo-charging technology and etc.,which puts forward more stringent requirements on the design and development of cooling system.Aiming at the problem of high cost and long development cycle of traditional cooling system,one cooling system of a commercial vehicle is introduced in this paper and its matching design and performance optimization is implemented in the method of numerical simulation.Based on the relevant parameters of the engine,the radiator,the cooling fan and the water pump are selected and four matching schemes are proposed according to the design and matching principle of cooling system.Then radiator heat dissipation and temperature difference between liquid and gas under the maximum torque condition are calculated and checked.Thus,four schemes are evaluated and the optimal one is obtained.In order to verify the cooling performance of the chosen cooling system,1D simulation and 1D/3D joint simulation model are established by using one-dimensional thermal management simulation software KULI and three-dimension simulation software ANSYS CFX.The thermal equilibrium state of the cooling system is numerically simulated under three operation conditions including climbing condition,high-speed condition and idling condition.The results show that the water temperature at outlet of the engine equipped with this cooling system is within the limit and can meet the designed requirements.Besides,the simulation results are compared with the cabin thermal management tests.It is found that the joint simulation model is more reliable than the 1D simulation.Aiming at the problem that outlet water temperature is slightly higher under climbing condition,the relative position of cooling module components is optimized.Based on Latin hypercube test design,a high-accuracy approximation model is constructed to describe the relationship between the engine outlet temperature and the position parameters of each component,and the accuracy of the approximation model is verified by cross validation.Taking the minimum outlet water temperature as the optimization target,the continuous quadratic programming algorithm is used to solve the approximate model and the optimal relative position is obtained.The results show that the optimized outlet water temperature decrease by 4?,which can effectively improve the cooling performance.The matching design and performance optimization involved in this paper can provide guidance for the design and development for the engine cooling system of the same type.