A passive fuel delivery system for portable direct methanol fuel cells

Abstract

A passive device is utilized for transferring methanol into water through a wick material. The wick material preferentially has a higher wicking capability with respect to methanol than water, and operates in a siphon fashion with the intake end in contact with methanol and the discharge end in contact with water. Due to the difference of wicking capabilities, a net amount of methanol is pumped into water. The device described above is used as a fuel delivery component for a liquid-feed fuel cell system, such as a direct methanol fuel cell (DMFC), which directly utilizes a liquid fuel without an intermediate reforming process. In the present experimental study, methanol and water are stored separately in two containers and a wick is positioned between the containers as a siphon, with the aqueous methanol solution communicating with the anode of the DMFC. Methanol is siphoned from the methanol container to the water container in situ when the methanol in the water is consumed during the operation of the fuel cell. Through a proper selection of the wick and the containers, the methanol concentration near the anode of the DMFC was maintained within a preferred range.