Fuel concentration and operating temperature effects on critical amounts of catalysts added to the fuel channels of direct methanol fuel cell

This study modifies the geometry of fuel channel corners in order to reduce the hydroresistance of the fuel within the channels, and investigates fuel concentration and operating temperature effects on the loading weight percentages of catalysts added to the fuel channels. The intent of the study is to further improve the output efficiency of DMFCs (direct methanol fuel cells). In this study, different proportions of catalysts, including active carbon and selenium (Se), were coated onto anode and cathode channels composed of PDMS (polydimethylsiloxane) to promote a fuel decomposition reaction in the fuel channels. The output of the DMFCs was measured under different operational temperatures and different supply fuel concentrations in order to find suitable catalyst loading values under different operational conditions. The experimental results indicate that under identical operating conditions, the performances of DMFCs can be greatly boosted using rounded channel turns rather than right angle turns. Furthermore, the results indicate that critical catalyst loading values exist for each catalyst under different operating temperatures. Suitable coating weight percentages for each catalyst are recommended for different operating temperatures. It was found that under lower operating temperatures and lower fuel supply concentrations, the effect of adding catalysts to fuel channels on the performance enhancement of DMFC is more apparent than for cases with higher operating temperatures and fuel supply concentrations. We also found that the fuel concentration effect on the performance of DMFCs was not apparent for a range of fuel concentrations investigated under the same operating temperature. In other words, while the fuel cells are under operation, even the supplied fuel concentrations vary, although not beyond operational concentration limitations. The effects of concentration variations on the performance of DMFCs with catalysts added to the channels can therefore be neglected.