Operational characteristics of a passive methanol catalytic combustor assisting vapor generation for direct methanol fuel cells

• A passive methanol catalytic combustor is developed as a heat provider for DMFCs.
• A pervaporation membrane is used as a methanol vaporizer for combustion reaction.
• Operational characteristics of the combustor are experimentally investigated.
• Results validate the advantage of pervaporation operation at a lower air feed rate.
• The effects of air feed rate on the catalyst temperature are explored in detail.

Searching for a passive method to provide heat for a vapor-feed direct methanol fuel cell (DMFC) is still a challenging technical issue before it is put into practical use. This work develops a passive methanol catalytic combustor based on a pervaporation membrane, which is intended to be used as an assistant heat source for a vapor-feed DMFC. To validate the effectiveness of this method, a traditional bubbling-based system is prepared for comparison. Results show that the pervaporation operation outperforms the bubbling mode and facilitates self-ignition at a lower air feed rate (AFR). The increase of AFR promotes a higher permeation flux of methanol vapor, but may inversely cause heat loss because the enhanced air flow is apt to bring more heat away from the combustor. The AFR has dual effects on the processes of vapor generation and heat dissipation, which must be optimized to realize a balance between these two factors. The dynamic responses of catalyst temperature to the variation of AFR are also investigated in this work.