Effect of gas flow-field design in the bipolar/end plates on the steady and transient state performance of polymer electrolyte membrane fuel cells

In this work the effect of gas flow-field design in the bipolar/end plates on the steady and transient state performance of the polymer electrolyte membrane fuel cell (PEMFC) is presented. Simulations were performed with different flow-field designs, viz. (1) serpentine; (2) parallel; (3) multi-parallel; and (4) discontinuous. The steady-state voltage at fixed current density of 5000 A m−2 was highest for discontinuous design. For studying the transient response, the average current density was increased suddenly from 5000 to 8000 A m−2. It was seen that when the load level was increased, the voltage level suddenly dropped and then with time leveled off to a value slightly higher than the dropped value. This time for serpentine, parallel, multi-parallel and discontinuous flow-fields were 9.5, 7.5, 8.0 and 16.5 s, respectively. While it was seen that the steady-state performance of the discontinuous type of design was the maximum, its transient response was slow. On the other hand in case of parallel type of design the steady-state performance was low, but the transient response was high. The multi-parallel design offers a unique advantage of both of these properties, viz. high steady-state performance with good transient response, and therefore should perform better than the other designs chosen in this study.