Analysis And Optimization On The Engine-cabin Thermal Management In One Passenger Car

As an important part of an automobile,the engine is highly integrated and works in a harsh environment with high heat dissipation.With the application of various new technologies to enhance engine power,the airflow status and thermal environment in the cabin become more complex.Excessive cabin temperature can cause heat-sensitive parts to fail or even spontaneous combustion,so the design and analysis of engine cabin thermal management at the R&D stage is extremely important.This paper takes an SUV model as the research object,combines the actual SUV model development project and relevant theoretical knowledge,and carries out cabin thermal management analysis optimization and test verification for this SUV model.The main work is carried out in the following aspects.1.Performance evaluation of key components in the cooling system.By matching the design principles and combining with the actual engineering requirements,evaluate whether the performance of the key components in the cooling system meets the engine heat dissipation requirements.2、Build a three-dimensional vehicle numerical calculation model and perform cooling flow field calculation.Obtain the flow field distribution in the initial model cabin,obtain the air speed,air volume and internal airflow characteristics of the cabin through the radiator,condenser and intercooler and other related data,so as to lay the foundation for the subsequent analysis of the impact of the air speed,air flow and flow field characteristics on the cooling performance in the cabin.3、Applying the joint simulation method of 1D and 3D,the equilibrium water temperature of the engine under the two operating conditions of idle speed and low and medium speed climbing is analyzed,and the temperature of the air outlet after the heat exchanger is obtained for3 D heat flow field calculation,and the risk of heat damage in the nacelle is predicted by analyzing the temperature field and flow field of important sections in the nacelle.The simulation results show that the engine water temperature is high at low and medium speed climbing conditions,and heat-sensitive parts such as fan motor,battery and starter are at risk of heat damage.Comprehensive analysis of the characteristics of the flow and temperature fields in the nacelle determines that the high engine water temperature is mainly due to the low air intake into the nacelle,and the risk of thermal damage is due to the influence of thermal radiation and local heat accumulation of heat source components.4.To address the problems of high water temperature and heat damage in the nacelle,optimization schemes such as improving fan performance or radiator performance,increasing grille opening ratio and adding deflector plates are proposed.The automatic optimization platform is established,and the approximation model and genetic algorithm are applied to optimize the heat dissipation performance of the nacelle.The length and tilt angle of the deflector are used as the optimization variables,and a suitable range of variables is selected according to the cabin space,and the adaptive mesh method is used to parameterize the variables.The data collection of sample points is completed by using the optimal Latin superlift method,and the structural characteristics of the deflector are optimized by combining the approximate model method and genetic algorithm.After optimization,the optimal deflector structure for each heat exchanger intake is obtained.On this basis,the engine water temperature is calculated to meet the permitted requirements,the risk of heat damage in the cabin is reduced,and thermal protection optimization measures are added to the components that still have heat damage.The establishment of an automatic optimization platform based on the adaptive grid method will largely shorten the computational solution time of the optimization work and provide a fast and effective way for the optimization work.5.Conduct the heat balance test of the prototype vehicle,obtain the engine balance water temperature and key heat-sensitive parts temperature test results under idling and low and medium speed climbing conditions,compare the simulation results with the test test test data and error analysis,the simulation accuracy of the cooling system is calculated to reach 3.15%,and the simulation accuracy of heat damage in the cabin reaches 10.33%.The results show that the optimized engine water temperature meets the requirements of safe use,the whole vehicle has good thermal balance capability,the optimization scheme is effective,and the simulation calculation results have high accuracy.