Cathode Air Feeding Strategy And Thermal Analysis Of Air-Cooled Proton Exchange Membrane Fuel Cell Stack

Proton Exchange Membrane Fuel Cell(PEMFC)is considered one of the most promising power generation systems to replace fossil fuels in the future.Compared with liquid-cooled PEMFC,the more severe working conditions and more complex waterthermal management of air-cooled PEMFC hinder further improvement of its performance and working stability.This paper aims at the problem of poor uniformity of temperature distribution of air-cooled PEMFC,and based on a self-made air-cooled PEMFC stack,carries out the following research on the cathode air feeding of the air-cooled PEMFC stack through computational fluid dynamics simulation calculation:Based on the self-made air-cooled PEMFC stack,a simulation model of the fan system of axial fan combined with fuel cell stack was developed and comparative experiments were carried out to verify the correctness of the model.It is found that there is a separation of boundary layers in the outlet airflow of the fan,and the separated low-speed airflow forms a backflow at the hub of the fan,resulting in the fan system working in the blowing mode,the uneven distribution of cathode air in the battery stack,and the phenomenon of local high temperature in the central area.In order to obtain the internal hydrothermal distribution characteristics of air-cooled PEMFC,a multi-physical model of air-cooled PEMFC single cell is established based on the actual structural parameters of the experimental stack single cell.It is found that along the air flow direction,the temperature in the battery film and the water mass fraction at the GDL-CL interface of the battery gradually increase,and perpendicular to the air flow direction.Based on the multi-physical model of air-cooled PEMFC single cell,the influence of cathode air feeding operating parameters on the hydrothermal distribution and output performance of the cell was analyzed.It is found that when the cathode and anode air feeding direction is reverse cross flow and the cathode air feeding speed is in the range of7m/s to 10.5m/s,and the cell will obtain better hydrothermal distribution and output performance.Uneven air feeding will reduce the uniformity of hydrothermal distribution inside the cell.Aiming at the problem of uneven cathode air feeding of the stack,based on the simulation model of axial flow fan combined with fuel cell stack fan system,the distribution of cathode gas and temperature in the stack under different gas feeding modes was studied to solve the problem of uneven cathode air feeding in the stack,and a cathode air feeding strategy to improve the distribution of cathode gas and temperature in the stack was proposed.It is found that the conductivity mode and the suction mode can effectively improve the uniformity of the air flow distribution of the stack cathode and reduce the temperature gradient inside the stack.For the suction mode,the cathode gas and temperature distribution are relatively uniform,which will be more conducive to long-term stable operation of the PEMFC.