| Popis: |
Uneven current density distribution in a proton exchange membrane fuel cell (PEMFC) can decrease the reactant and catalyst utilization, reduce the energy conversion efficiency of the whole fuel cell, and even lead to a shortened cell life. Therefore, studying current density distribution has a critical role in the research and development of PEMFC. To investigate the distribution of the proton exchange membrane fuel cells' local current density under different operating conditions, a single cell using the segmented cell technique consisting of 36 zones was designed. The results show that the maximum current density first appears at the outlet and then moves to the inlet. In addition, when the cell output is stable, the most negligible current density appears in the cell's middle area. The current density distribution was improved when the cell temperature was 50 °C. Compared with other operation temperatures (without cooling, 40 °C, 60 °C), the current density is decreased by 14.0 %, 9.8 %, and 40.6 %, respectively. At the same time, the cell voltage is increased by 10 %, 6.45 % and 22.22 %, respectively. Higher gas pressure is more favourable to improving cell performance and the uniformity of current density distribution. However, when the cathode gas pressure exceeds that of the anode, the reverse inverse current is pronounced in the middle of the cell at the starting process. The reverse duration of the 50 °C cell is reduced by 30 s (25.4 %) compared to the cell without cooling. |
