Numerical Modeling for Flow and Transport in a Micro-Channel Fuel Cell Reformer

The flow and performance for a micro-channel reformer of a fuel cell is studied numerically. Methanol with water flows into a micro-channel with catalyst layer and is reformed to provide hydrogen for the fuel cell. The channel length is varied from 800 to 6000 μm and the channel height varied from 50 to 400 μm. The inlet flow velocity varies from 0.00001 to 0.002 m/s, and the inlet temperature varies from 250 to 350 °C. The density (area fraction on the wall) of catalyst varies from 25 to 100%. A reference case is chosen to have 100 μm channel height, 0.0001 m/s inlet velocity, and 100% catalyst density. The results indicate that the higher the inlet velocity, the lower the methanol conversion mass fraction. The variation of the conversion ratio is almost linear with the flow rate. As expected, the higher the catalyst desity, the higher the conversion effieciency. However, the present results indicate that the reduction of the catalyst density by a half only sacrifices 5% performance. In addition, the conversion efficiency decreases with the increase of the channel height, but increases with the increase of the inlet temperature. The present results can provide design reference for fuel cells with a micro-channel reformer.