Research On Multidimensional Coupling Simulation Model Of Fuel Cell Vehicle Thermal Management System

In recent years,with the development of fuel cell technology,commercial fuel cell vehicles(FCV)have gradually emerged.But FCV technology is still developing.And there are still many problems that need to be resolved.Due to the characteristics of lowtemperature fuel cells,the development of FCV technology puts forward high requirements for the thermal management system.The optimum operating temperature of PEM fuel cell is between 60-80℃.Therefore,the thermal management system needs to maintain the temperature of the battery stack within this range.At the same time,it is necessary to reduce the temperature fluctuation as much as possible to improve the temperature uniformity.In this paper,the engine and thermal management system of FCV are modeled.The engine system mainly consists of PEM fuel cell stack,intake and exhaust system and thermal management system.The thermal management system model mainly includes thermostat,water pump,fan and radiator.The model was simulated under the New European Driving Cycle(NEDC).The results show that the stack temperature is controlled between 60-80℃,but the maximum temperature reaches 77℃.And the temperature fluctuation range is large.In order to improve the accuracy of one-dimensional loop,the heat transfer and flow characteristics of the key cooling modules in the thermal management system are studied.The 3D model of radiator is built.Porous media mode is used in the unit parallel flow radiator.Firstly,the local fin model is simulated.After obtaining the parameters needed to establish the porous media model.Using porous media model instead of real fins to calculate three-dimensional flow field and temperature field.Compared with the experiment,the error range of the heat dissipation is [-3.7%,8.3%],and the error range of the pressure drop is [-0.2%,7.9%].The radiator is optimized by changing the fin size.The best heat transfer performance is achieved when the opening angle of the shutter is 23°.The one-dimensional thermal management system and three-dimensional components are coupled and analyzed.On this basis,the loop of FCE thermal management system is optimized.By adding thermostat and fan control system to improve the temperature control ability of thermal management system,the limit temperature and temperature fluctuation range under high load are reduced.Under the NEDC cycle,the temperature fluctuation of stack is around 65℃,and the maximum temperature is 67℃.The heat transfer performance of the optimized circuit has been significantly improved.The FCV power consumption model is introduced.And the thermal performance of the optimized FCE circuit under different driving conditions is analyzed.The results show that the loop can adapt to different driving conditions.Finally,the three components of the FCV thermal management system,FCE thermal management,PCU thermal management,and air conditioning refrigeration circuit were integrated and analyzed.The thermal characteristics of the air conditioning refrigeration circuit were analyzed.The spatial distribution of the three heat exchangers in the front cabin was analyzed.The advantages and disadvantages of heat transfer characteristics under different schemes are compared.By introducing evaluation criteria,it is concluded that the second scheme is the best.