Thermal Management Of Pulsating Heat Pipe For Application In Proton Exchange Member Fuel Cells

The development of the proton exchange membrane fuel cell technology is an important way to realize sustainable development strategy.A reasonable operating temperature within the proton exchange membrane fuel cell is an important factor to ensure good cell performance.The proton exchange membrane fuel cell generates a large amount of heat during operation,which needs to be dissipated in time to maintain a proper temperature.Commonly used heat dissipation methods include air cooling,liquid cooling and pulsating heat pipe cooling method.This paper focus on the pulsating heat pipe cooling method and compare it with air cooling method and liquid cooling method.Mathematical models are developed for the three cooling methods to study the thermal management characteristics of the proton exchange membrane fuel cell.First,the effects of natural convection air cooling without cooling channel and forced convection air cooling with serpentine cooling channel on the temperature,oxygen concentration,water content,and current density of the proton exchange membrane fuel cell were compared.The results show that the presence of the serpentine cooling channel reduces the cell temperature.The cell temperature gradually decreases with the increase of the cooling air inlet rate and the decrease of the inlet temperature.The index of uniform temperature decreases with the increase of the flow rate.The trend of the temperature and the index of uniform temperature decrease smoothly at the high inlet rate,and the index of uniform temperature is reduced by a maximum of 14.92%.For the liquid cooling method,the average temperature and the index of uniform temperature decrease with the cooling water inlet rate increases,and the temperature difference gradually decreases.When the inlet rate increases to 0.5 m/s,the index of uniform temperature stabilizes.The index of uniform temperature increases with the decrease of the inlet temperature.For the pulsating heat pipe cooling method,by calculating the equivalent thermal conductivity at the thermal stability of the pulsating heat pipe.The pulsating heat pipe is regarded as a solid with fixed thermal conductivity for heat dissipation of the proton exchange membrane fuel cell.The average temperature of the fuel cell decreases with the increase of the heat transfer coefficient of the condensing section of the pulsating heat pipe.But the index of uniform temperature gradually increases with the increase of the heat transfer coefficient of the condensing section of the pulsating heat pipe.The liquid cooling method and the pulsating heat pipe cooling method can effectively reduce the temperature of the proton exchange membrane fuel cell,and the index of uniform temperature of the cell is lower than that of the air cooling method.Comparing the three different cooling methods,it is found that pulsating heat pipe cooling method can lead to higher cell current density and exhibit good thermal management performance.Finally,based on the conventional pulsating heat pipe structure,the tapered nozzle type and divergent nozzle type pulsating heat pipes are proposed to analyze the flow and heat transfer characteristics of different working medium(deionized water,methanol,acetone)at different filling ratio(FR=40%,50%,60%).The results show that the presence of microgrooves in the nozzle type pulsating heat pipe causes semi-circular flow,vortex flow and increases the disturbance with the flow of the working medium in the tube.The thermal resistance of the divergent nozzle type pulsating heat pipe is smaller than that of both the conventional pulsating heat pipe and the tapered nozzle type pulsating heat pipe.However,the difference in thermal resistance between the two nozzle types of pulsating heat pipes is not large.And the effective thermal conductivity of nozzle type pulsating heat pipe is higher than that of the conventional pulsating heat pipe.