Critical control volume sizing for improved transient thermal modeling of PEM fuel cells

In this paper, the necessity of multiple thermal control volumes (CVs) in the cathode channel is investigated to address the spatial gradients. A method to improve the thermal modeling accuracy near the cathode inlet of the fuel cell stack by using un-evenly spaced CVs to represent the channel is presented. Analysis is performed starting with the 1D heat transfer equation for the cathode channel. By using scaling arguments to remove extraneous terms, a simplified 1D solution for the temperature profile in the cathode channel is developed. From this result, the necessary CV sizes to remain within a critical band of the actual spatial temperature profile can be calculated.