A COMPUTATIONAL FLUID DYNAMICS ANALYSIS OF AIR FLOW THROUGH A TELECOM BACK-UP UNIT POWERED BY AN AIR-COOLED PROTON EXCHANGE MEMBRANE FUEL CELL

Proton exchange membrane fuel cells (PEMFC’s) are currently being commercialized for various applications ranging from automotive to stationary such as powering telecom back-up units. In PEMFC’s, oxygen from air is internally combined with hydrogen to form water and produce electricity and heat. This product heat has to be effectively removed from the fuel cell, and while automotive fuel cells are usually liquid-cooled using a secondary coolant loop similar to the internal combustion engines, stationary fuel cell systems as they are used for telecom back-up applications often rely on excessive air fed to the fuel cell cathode to remove the heat. Thereby, the fuel cell system is much simpler and cheaper while the fuel cell performance is substantially lower compared to automotive fuel cells.

This work presents a computational fluid dynamics analysis on the heat management of an air-cooled fuel cell powered commercial telecom back-up system produced by Dantherm Power A/S, Denmark. The analysis is carried out with the commercial CFD solver Fluent (ANSYS Inc.). The fuel cell stack is modeled as a porous medium to accurately match the pressure drop, and it includes a heat source to account for the product heat. An important result is the predicted distribution of the temperature over the fuel cell stack, and a comparison between the modeling results and experimental validation will be made. Finally, the effect of various operating parameters on the temperature distribution in the telecom back-up power box will be investigated.