Computational Modelling of the Flow Field of An Electrolyzer System using CFD

AbstractA bipolar plate is one of the primary components in a Polymer Electrolyte Membrane (PEM) electrolyzer which contributes to its hydrogen production efficiency. Its primary function is to distribute the flow of a fluid, in this case water, evenly over the active area of an electrolyzer cell. A well designed and optimized bipolar plate is required to produce an efficient and cost effective PEM electrolyzer stack. In this paper optimal flow plate design and computer models of several available flow plate designs were constructed, and then run through a numerical simulation to evaluate both the hydrodynamic properties they exhibited, the velocity field and pressure gradients. Results indicate that under the specified conditions, the pressure gradient decreases diagonally along the bipolar plate, from the inlet to the outlet. However, the sharpness, or evenness of the pressure gradient varies depending on the design of the bipolar plate. The velocity fields also follow the same general trend, only that they increase in magnitude as they approach the outlet rather than decrease. However, the magnitude of their velocity in the middle of the plates, especially in some of the designs, such as in the multi-pass serpentine designs, varies randomly within a certain range rather than decreasing or increasing evenly, it is only at the outlet that the velocity gradient becomes more consistent. However, of all the designs evaluated the parallel flow field stands out as a very suitable design for use, due to its ability to maintain operational pressures above 1MPa through its entire flow field and also, due to its ability to maintain a stable flow velocity between 3-5m/s, both characteristics which were not displayed by the other two designs. In addition, the parallel flow field design was also able to maintain a average Reynolds number close to the critical value or RE=4000, thus minimizing its internal turbulence