PEMFC Storage And Start In Low Temperature

Proton exchange membrane fuel cells(PEMFC)should have certain environmental adaptability,and the cathode undergoes an oxygen reduction reaction and produces water to form ice in a subzero environment.However,this inherent feature severely constrains the commercialization of PEMFC.Because when the fuel cell is in a sub-zero environment,the main effect of water freezing is to block the micropores,flow fields and gas flow channels of the porous electrode,prolong the startup time of the fuel cell,and accelerate the fuel cell attenuation.Based on the existing literature reports,there has been sufficient research on how to make the fuel cell start up quickly,but the research on the energy consumption and utilization rate of heat transfer and start-up in the low-temperature start-up process is scarce.In this paper,we will compare and study the cold start process of catalytic reaction of metal plate PEMFC and composite plate PEMFC,and explore the influence of catalytic reaction on the start-up of different materials and its attenuation mechanism.Firstly,a five-section metal plate PEMFC with an active area of 270 cm2 and a five-section composite plate PEMFC with an active area of 312 cm2 were assembled.The specific heat capacity was obtained by the law of conservation of heat.Based on this,during the low-temperature start-up of the fuel cell,the heat absorption,heat dissipation and heat taken away by the gas were investigated.The calculation shows that the heat generated by the catalytic reaction is much larger than the heat required for the temperature rise of the fuel cell,indicating the feasibility of the catalytic reaction method applied to the low temperature start of the PEMFC.Secondly,the influence of different mixture gas ratios on the low temperature start of catalytic reaction was investigated by the control variable method.The results show that when air/H2=1/4,the fuel cell starts faster,and under this condition,the metal plate fuel cell started successfully at-35? and composite board fuel cell started successfully at-36?.Through the comparison of the two,it is found that the metal plate fuel cell has a faster heat transfer and a faster start-up speed.With the decrease of the ambient temperature,the temperature difference between the various sections of the fuel cell during the start-up process is large.After multiple starts,the fuel cell exhibits varying degrees of physical damage;composite plate fuel cell heat transfer is slow,start-up speed is slow,but the temperature difference between the various sections of the fuel cell during startup is small,after the multiple starts,the fuel cell has no attenuation.Finally,the cold-start method using exhaust gas was designed.The starting conditions of metal plate PEMFC and composite plate PEMFC at different temperatures and hydrogen utilization rate were investigated,at the same time,the attenuation test of 20 times-20?start-up were carried out respectively.The experimental results show that the cold-start method using exhaust gas can greatly shorten the startup time and the temperature difference during startup is small,the hydrogen utilization rate is effectively improved,tends to 10%,the energy consumption is significantly reduced,and multiple starts does not affect the fuel cell performance..