Research On Key Techniques Of Dual Loops Cooling System For Wheel Loader

Compared with traditional road vehicles,wheel loaders have the characteristics of complicated working conditions,harsh working environment and long continuous working time,which makes the performance and reliability of the cooling system of wheel loaders more stringent than traditional road vehicles.With the increasing emphasis on energy saving and emission reduction in the country,the problem of pollutant emissions from wheel loaders and other non-road mobile machinery has attracted much attention.In order to deal with the new emission standards for off-road vehicles,it is urgent to improve the performance of the cooling system of wheel loaders.In this paper,based on the project of National Science and Technology Supporting Plan," Research and development of integrated intelligent engineering equipment for energy conservation and security ",the dual loops cooling system of 50 loaders is studied.Based on the theories of engineering thermodynamics,heat transfer and gas dynamics,the following researches have been conducted on the key technologies of the dual loops cooling system of wheel loaders through numerical analysis combined with experimental verification:(1)The numerical analysis method of heat transfer performance of a plate fin engine turbocharged air cooler(charge air cooler)is studied.The influence of the boundary and geometric conditions of the simulation model on the resistance coefficient is analyzed.Through the study of the transverse flow characteristics of the offset strip fins,the transverse drag coefficient is solved,and the transverse drag coefficient is introduced into the porous medium model to improve the accuracy of numerical simulation of the heat transfer performance of the plate fin heat exchanger.(2)Based on the compressibility of turbocharged high-speed air flow,a compressible air flow model of charge air cooler is built up,which improves the accuracy of the simulation of the charge air cooler under large flow conditions.Performance evaluation of water cooled and air cooled charge air cooler with entropy production unit number of heat exchanger.Use charge air cooler controls the performance of the engine by controlling the state of intake air.The results show that reasonable control of intake air temperature and pressure can reduce the emission of engine pollutants and improve the engine's dynamic performance.(3)Optimization of noise reduction for large diameter cooling fans of non-road mobile machinery by taking the cooling fan of wheel loader as the research object.Combined with irregular characteristics,a new irregular surface cooling fan is established.The flow field and sound field of power cabin are simulated by CFD virtual wind tunnel model.(4)To improve the heat transfer efficiency of the wheel loader cooling system and reduce energy consumption,a radiator mathematical model is constructed based on the theory of effectiveness-NTU method,and the mathematical model is used to solve and analyze the effects of different working conditions and size structures of the radiator on its performance,and based on it,dual loops cooling system cooling module to carry out research.By comparing the performance of the cooling system simulation with series and parallel radiator modules,it is concluded that the series radiator module works better under actual operating conditions.(5)Through field tests,the performance of the dual loops cooling system radiator module was verified.The results show that the dual loops cooling system can meet the heat balance requirements of the wheel loader.Compared with the original cooling system,the dual loops cooling system has lower energy consumption,and the radiator module has different degrees of improvement in the uniformity of air flow,compactness of the volume,and effective pressure loss of the air flow.