Research On Water And Heat Management And Performance Of Proton Exchange Membrane Fuel Cell Based On Channel Design And Optimization

Currently,the issue of global warming and the energy shortage is attributed to continuous exploitation of fossil fuels,which have attracted much attention.It’s an effective method to alleviate the problem by developing sustainable green energy utilization technology.Proton exchange membrane fuel cell(PEMFC),as a high energy density,green and safe energy utilization technology,can be used to convert hydrogen energy into electricity and simultaneously produce water.However,the water and heat problem in PEMFC will lead to the corrosion or even destruction of catalyst(CL),which restricts its commercial development due to the cell-life and performance is reduced.This work takes the cathode side channel structure as the research object,proposes a novel channel structure that couples the cooling channel and the reaction channel for solving the water and heat problem in PEMFC.There are three parts of research is performed,including channel structure parameters,operating characteristics and channel optimization.The specific research content and conclusions are as follows:(1)Firstly,the hole parameters for coupling cooling channel and reaction channel were studied based on the validated numerical model,including the dimension,position and hole numbers.The research demonstrated that the optimal single hole parameters are 0.4mm long,0.5mm wide and 20mm position which can maximum the PEMFC’s current density output.Moreover,increasing the hole numbers at the end of cathode channel can improve the oxygen mass fraction in cathode GDL/CL interface and decrease the water concentration.It can effectively relieve the water flooding.(2)Secondly,the effect of the operating condition of this novel channel structure on the fuel cell performance was studied,including the relative humidity,temperature and stoichiometry of cathode side inlet.The study results show that the change of air humidity and temperature at the cathode inlet has little effect on the current density of PEMFC.Under low cathode stoichiometry,compared with conventional channels,the current density of PEMFC with five-hole(H5)channel structure is improved.At 2.4 cathode stoichiometry,H5 has 37.1%reduction in maximum water saturation compared with conventional channels.However,the performance enhancement amplitude of the new channel battery under high stoichiometry is limited.(3)Finally,two optimizations were proposed to strengthen the water and heat management capabilities of fuel cell that is the cooling channel to be inclined and the middle partition to be leave an half,respectively.And then,investigate its influence on the water and heat distribution inside the fuel cell.The cooling channel is designed to be inclined with a slope angle,which enhances PEMFC’s water removal capacity.In comparison with the conventional channels at 1.8 cathode stoichiometry,the H5 withθ=0.20~°in maximum water saturation aspect reduces 43.10%.In addition,the current density of H5 increased by 12.54%compared with that of the conventional channel atθ=0.20~°.What’s more,the novel channel structure hardly increases pressure drop versus the conventional channels.The optimization based on the middle partition shows that in the reaction channel,the water diffusion near the outlet is significantly increased,and the water transportation near the inlet is accelerated.The distribution uniformity of the temperature and oxygen has significantly improved.Comparative analysis found that the optimization based on the middle partition can reduce the maximum water saturation by about 60%.