Real-time visualization of oxygen partial pressures in straight channels of running polymer electrolyte fuel cell with water plugging

Abstract

Visualization inside polymer electrolyte fuel cells (PEFCs) for elucidating the reaction distributions is expected to improve the performance, durability, and stability. An oxygen-sensitive film of a luminescent porphyrin was used to visualize the oxygen partial pressures in five straight gas-flow channels of a running PEFC with liquid-water blockages formed at the end of the channels. The blockage greatly lowered and unstabilized the cell voltage. The oxygen partial pressure decreased nearly to 0 kPa in the blocked channel. With a water

Visualization of Oxygen Partial Pressure and Numerical Simulation of a Running Polymer Electrolyte Fuel Cell with Straight Flow Channels to Elucidate Reaction Distributions

“…The gas flow rate of air and H 2 was 0.200 L min −1 . The power generation continued stably, as reported in a previous paper . For comparison, a reference cell was used, which had carbon bipolar plates on both cathode and anode sides and no dye film on the GDL with the same design of flow channels (•, Figure ).…”

“…At the inlet, was nearly 13 kPa, regardless of , different from the results obtained on the upper flow channel (Figure a); at higher , the oxygen consumption ratio at the GDL surface became higher, and therefore, the pressure loss observed on the upper flow channel (Figure a) should have been compensated by the higher oxygen consumption. Near the inlet between 0 and 2 mm along the channel length with no catalyst layer (Figure b), was already seen to decrease by the oxygen consumption in the catalyst‐coated region (2–52 mm) . In the catalyst‐coated region, decreased smoothly and showed no indication of water saturation, similar to the case for the upper flow channel.…”

“…At the open‐circuit voltage with no power generation ( =0 %), was 13 kPa in all channels (Figure a, left). The pressure loss was very small compared with that in the serpentine channels . Upon operating the cell at =15 % (0.111 L min −1 ), was seen to decrease gradually along the channels from the inlet to the outlet, and this confirmed uniform power generation on the catalyst layer.…”

“…Upon operating the cell at =15 % (0.111 L min −1 ), was seen to decrease gradually along the channels from the inlet to the outlet, and this confirmed uniform power generation on the catalyst layer. At approximately 50 mm along the channel length, began to increase (Figure b), because there was no catalyst layer between 52 and 54 mm . At =30 % (0.055 L min −1 ), was still seen to decrease gradually along the channel, but with a larger incline than that at 15 %.…”

“…In channels 1 and 5, was higher than that in the other channels at the same channel length. The difference among the channels can be explained by the geometry of the reaction area . To examine the visualized images in detail, was plotted from the inlet to the outlet along the center channel (channel 3) at different (Figure b).…”