Research And Optimization Design On Plateau Cooling System Of Construction Machinery

With the further development of the western development strategy and the Silk Road re-proposed,automotive and construction machinery and other vehicle equipment will be further flourishing in the western region.However,the unique plateau environment in the western region hinders the efficient operation of vehicle equipment and even affects the normal operation of vehicle equipment.The main reason is that the air density and pressure are reduced by altitude,and it eventually leads to insufficient cooling capacity and the high engine outlet water temperature under the same cooling condition.At the same time,the change of altitude also result in the decrease of boiling temperature of coolant,and the engine is very easy to be overheated,which can caused great damage to the engine.Therefore,this paper reveals the heat transfer law and design criterion of highland type vehicle by analyzing the thermophysical relationship and working mechanism of the plateau cooling system and the influence factors and sensitivity characteristics of the cooling system,to achieve the re-design of different altitude and plateau cooling system,and realized its comprehensive applications in the plateau vehicle.The main work is as follows:Firstly,the vehicle cooling system test platform was built,and the measurement and control software was developed based on C#language.The reliability and stability of the control program were tested by several experiments,which met the measurement and control requirements of the vehicle cooling system test platform.At the same time,the experimental study of the cooling system was carried out under different speed and flow conditions.The average deviation between the experimental results and the numerical simulation results is less than 10%,which verifies the accuracy and reliability of the numerical simulation.Secondly,the key component tubular radiator in the cooling system was studied,and its simulation program for was developed in Matlab.After verifying the correctness of the simulation program,the air-side and water-side outlet temperatures,the air-side pressure drop,the air-side heat transfer coefficient and the heat dissipation of radiators with four common fins(namely louver,straight,wavy and serrated fins)were calculated under different thermal physical conditions at different altitudes.Then,the cooling capacity of different radiator fins were analyzed under the influence of various altitudes.Also,the heat transfer performance and the wind resistance performance of different radiator fins at various altitudes were compared.The final results show that the louver fin radiator owns more integrated heat dissipation performance and can further be optimized.Thirdly,in order to study the heat dissipation performance of louvered fin radiator,taking the fin mass as the constraint variable and taking the thickness of fins,fin spacing,fin width,louver spacing,louver angle as target variables,the Pareto optimal solutions and the sensitivity of five parameters to the pressure drop and the heat dissipation were obtained by using the genetic algorithm to optimize the fins in ANSYS Workbench under the reliability of numerical simulation method.The final optimization results show that the air pressure drop is reduced by 18.04%and the heat dissipation is increased by 9.92%when the external dimensions of the radiator are constant.Finally,the flow and heat transfer characteristics of the engine cooling system with multi-fan arrangement were studied.The simulation model of the multi-fan cooling system was established based on the CFX software,combined the actual experimental data to ensure the correct simulation results.The distribution and variation of the temperature field of the engine cooling system were calculated and compared at different altitudes.By changing the center of the fan and the position of the air inlet,the effect of different optimization schemes on the thermal performance of the multi-fan cooling system was compared.This research can provide reference for the optimization design and the adaptability of plateau of engineering machinery cooling system.