Two-phase flow in the minichannels of proton exchange membrane fuel cells (PEMFC) flow field plates

This work focuses on the gas-liquid flows in the cathode plate, with the objective to observe their patterns, to understand their behavior, to estimate the pressure drops and eventually, to reduce clogging and its possible consequences in term of oxygen starvation downstream. A special emphasis is put on the effect of the channel section (typically between 0.5 and 1 mm2) and on the surface properties of the flow field plate materials. The experiments are performed ex-situ. The pressure drop is measured locally along the channel as well as globally between the inlet and outlet, which put forward the existence of clogging/unclogging sequences. The characteristic frequency of these sequences increases with the air flow rate. Two main flow patterns have been observed depending on the distance from the inlet. Finally, the results show that the ratio of pressure drops in two-phase flow to pressure drops in dry flow decreases with the air flow rate while it does not seem to depend on the channel size (within the tested range).