扩散层孔隙率对平行流场 PEMFC 性能影响研究

为了研究扩散层孔隙率对质子交换膜燃料电池的性能影响,采用计算流体动力学商业软件 ANSYS Fluent在不同扩散层孔隙率(0. 3、0. 5、0. 7)的条件下,对传统平行流场和斜坡平行流场的性能曲线、气体浓度分布、液态 水分布进行数值模拟分析;结果表明:在高电位下各案例对应的性能差异较小,在中低电位性能差异较大,随着扩散层孔隙率越大,质子交换膜燃料电池性能越好,且孔隙率在 0. 3~ 0. 5 时电流密度增长率最大,最大可达 9. 03%;当扩散层孔隙率较高时,有利于反应气体穿过扩散层,使得催化层氧气浓度增大,促进了燃料电池内部的电化学反应;随着扩散层孔隙的增大,能够更有效地促进反应气体的传输,流道内水含量越高,越有利于液态水的排出;相比传统平行流场,斜坡平行流场电池性能更好,氧气分布更均匀,流道中气体流速更大,排水效果更好,且孔隙率为0. 7 时电流密度增长率最大,最大可达 28. 79%。

Influence of Diffusion Layer Porosity on PEMFC Performance in Parallel Flow Field

In order to study the effect of diffusion layer porosity on the performance of proton exchange membrane fuel cell the performance curves gas concentration distribution and liquid water distribution of traditional parallel flow field and slope parallel flow field were numerically simulated and analyzed by using computational fluid dynamics commercial software ANSYS Fluent under the conditions of different diffusion layer porosity 0. 3 0. 5 and 0. 7 . The results showed that the performance difference of each case was small at high potential and the performance difference was large at medium and low potential. The greater the porosity of the diffusion layer the better the performance of proton exchange membrane fuel cell. When the porosity was 0. 3~0. 5 the maximum growth rate of current density was 9. 03%. When the porosity of the diffusion layer is high it is conducive for the reaction gas to pass through the diffusion layer which increases the oxygen concentration in the catalytic layer and promotes the electrochemical reaction in the fuel cell. With the increase of the pores in the diffusion layer it can more effectively promote the transmission of reaction gas. The higher the water content in the channel the more conducive to the discharge of liquid water. Compared with the traditional parallel flow field in the slope parallel flow field the cell performance is better the oxygen distribution is more uniform the gas flow rate in the flow channel is greater the drainage effect is better and the current density growth rate is the largest at a porosity of 0. 7 up to 28. 79%.