Study On The Performance Of Air-cooled Proton Exchange Membrane Fuel Cell

Air-cooled proton exchange membrane fuel cells（PEMFC）simplify the cooling and gas supply systems of conventional battery packs,effectively reducing additional energy consumption and improving portable performance.The air-cooled fuel cell’s gas supply method affects its output performance.An air-cooled PEMFC stack consisting of 19 single cells was assembled,and the effect of the gas supply method on the performance of the stack under different operating conditions was investigated.The results show that the cathode air inlet method with blow flow mode can improve the overall performance of the stack.The stack output voltage is increased by 7.3%,the average temperature is reduced by 0.6℃,and both voltage and temperature homogeneity are improved with standard deviations reduced by 43.0%and 23.9%,respectively.The results also show that the improvement in stack performance is more pronounced in blow flow mode at lower ambient temperatures because airflow enters the stack in blow flow mode through the high-speed fan,thus blowing the fan’s own heat into the stack and increasing the stack operating temperature,thus optimizing stack performance.When the ambient temperature is 15℃,the operating temperature of the stack increases by 10℃,and the output voltage of the stack increases by 5%at this time.It was also found that when the operating temperature of the air-cooled stack was high,selecting the blow flow mode improved the thermal stability of the stack.At 2-grade,the current density was increased to 500 m A·cm^-2（when the stack temperature reached50℃in the exhausted flow mode）,and the average stack temperature in the blow flow mode was 1.5℃lower than that in the exhausted flow mode,with a 27.2%reduction in the standard deviation of temperature homogeneity.The effects of different operating conditions on the dynamic response characteristics of the cell were also investigated.The experimental results show that the higher the ambient temperature,the lower the stack overshoot voltage.0.18174 V（37.8%）is reduced for the stack loading overshoot voltage and 0.11307 V（28.4%）is reduced for the load shedding overshoot voltage at 30℃ambient temperature compared to 15℃ambient temperature during the variable load between 15A and 60A current.The effects of anode gas pressure and cathode air flow rate on the dynamic response characteristics of the cathode open air-cooled stack were investigated.The experimental results show that the effect of anode gas pressure on the dynamic response of the cell is not significant,but with the increase of cathode air flow rate,the cell overshoot voltage decreases significantly.Under the variable load rate of 3A/s and anode gas pressure of70KPa,the overshoot voltage decreases by 11.9%,30.8%and 38%during the loading process,and 4%,8.9%and 11.3%during the decreasing load process,respectively,as the cathode air flow rate increases compared with the 1-grade cathode air flow rate during the variable load process between 15A and 60A current.Meanwhile,this paper investigates the dynamic response of the cell under different tailpipe emission intervals.The results show that the stack overshoot voltage rises with the tail gas emission interval,but the cell temperature overshoot phenomenon before and after the tail gas emission is not significant.The average cell temperature only decreased by 0.51%,0.55%,and 0.51%（0.25815℃,0.27926℃,and 0.25647℃）before and after exhausting at different exhaust emission intervals（1min,2min,and 3min）,respectively.