Thermal Management Design,simulation And Optimization Of Full-power Fuel Cell Vehicle Power System

The heavy use of automobiles has exacerbated environmental pollution and global warming,which prompts people to find safe and efficient renewable energy.As an energy conversion device with high efficiency,no pollution and high reliability,fuel cell has received general attention from the automobile industry.The proton exchange membrane fuel cell has the advantages of high start-up speed and high power generation efficiency,so it is the most suitable power source for automobile.However,the fuel cell vehicle has many heating components,which procduce large heat,besides,the working temperature of the electric stack is low（60°C ～85°C）,these lead to the small temperature difference between the coolant temperature and the ambient temperature,the heat dissipation becomes more difficult.The performance of the thermal management system directly affects the dynamic,economic and comfort of the vehicle,so the thermal management problem is one of the main technical challenges for fuel cell vehicles.On the basis of the national key research and development plan,this paper designs,simulates and improves the thermal management system of the full-power fuel cell vehicle power system by using the one-dimensional/three-dimensional software joint simulation method,which lays a foundation for the pre-design and development of the automobile thermal management.The main contents are as follows:（1）Based on the principle of the proton exchange membrane fuel cell,the internal heat generation principle,the phenomenon of electrochemical reaction and polarization phenomenon are studied.On the basis of the theoretical calculation and empirical formula,the stack model with total parameters is established by Matlab/Simulink,then the experimental parameters provided by supplier are uesd to verify the correctness of the model.The results show that relative error of each output parameter is about 6%.（2）On the basis of the heating characteristics and temperature requirements of each heat source,this thesis reasonably designs the thermal management mode and system architecture.The main components of the thermal management system are modeled by using GT-COOL,then,using the experimental data of a 30 k W stack thermal management system to vertify this model,the relative error of each parameter is within 5.5%.Coupled stack model and system model,the effects of working temperature of stack and ambient temperature on the system working performance are studied.The heat dissipation capacity of the thermal management system under extreme working conditions is verified.（3）Simplifying the engine cabin model,build 3D simulation model.The porous media model of each heat exchanger,the multi-reference coordinate system model of fan and the heat source model are constructed.Then,this thesis uses STAR-CCM+ to simulate the flow field distribution in the cabin under high-speed and climbing conditions.According to the air intake calculated by 3D simulation,the 1D simulation results are corrected,and the heat dissipation and temperature distribution of the main components are analyzed,The results show that The suction effect of the fan cannot provide sufficient air intake for the cooling module,the flow field of the front cabin is more complicated,the temperature is higher and the heat dissipation is more difficult under the condition of climbing.（4）To improve the thermal environment of the cabin,this thesis studies the effect of cooling component arrangement on the heat dissipation performance.The effect of the distance between condenser and radiator and fan and radiator on the air intake of cooling module are studied.By analyzing the temperature field of the main cooling components,comparing the air intake of the cooling module under different arrangement schemes,the improved arrangement scheme is selected to make the comprehensive performance of the cooling module optimal.