Elucidation of Degradation Factor Distribution in a Same Electrode on PEFC

Abstract

Our proposal diagnostics evaluates the PEFC’s transient response with a resistance polarization, an activation polarization and a diffusion polarization, and derives diagnostics parameters by analyzing this transient response. Because we have already clarified that this diagnostics system was able to diagnose the 25cm2 PEFC single cell, we tried to elucidate the degradation factor distribution in the same electrode by applying it to the quadrisection separator. As a result, our diagnostics was able to judge the difference of the degradation factor in each section in the same electrode such as the resistance polarization is the highest at the gas upper stream, the activation polarization is the lowest at the middle section and the diffusion polarization is the highest at the gas downstream.

Improvement of Algorithm of Diagnostics for PEFC Performance

“…(4) was discretized by the difference method, and was converted into Eq. (5). Finally, the model Eq.…”

“…(6) was obtained by simplifying Eq. (5). Each parameter (a, b, c) was obtained by fitting the transient response by Eq.…”

“…The conventional diagnostics shows that A 1 parameter of the MEA with large amount of platinum is smaller than that with a little platinum under the standard operating condition, and t 1 parameter of the MEA with large amount of platinum is larger than that with a little platinum because an increase in the produced water by the brisk cell reaction increases the diffusion polarization. Therefore, the conventional diagnostics can diagnose the difference non-heating/humidifying conditions is larger than that under the standard condition though both A 1 parameters are almost same because of the same MEA use, the conventional diagnostics can also diagnose the difference of the diffusion polarization [5].…”

“…Especially, this tendency is remarkable in the condition without heating and humidifying. However, the difference of the parameter between the division cells is small though the difference of the humidifying conditions is greatly reflected in each parameter [5].…”

“…Additionally, this diagnostic system was applied to a PEFC short stack and the four segmented separator as shown in Figs. 1 and 2 respectively, and it found the deteriorating cell in the stack and clarified the deteriorating distribution in the same cell [4,5]. However, enough analytical time is necessary if the 356TD was applied to the stack composed of more than 200 cells, and it is expensive as a maintenance equipment.…”