Numerical simulation on mass transport in a passive vapor-fed direct methanol fuel cell operating with neat methanol

Abstract

A direct methanol fuel cell (DMFC) operating with neat methanol is a promising power candidate for electronic and portable devices because of its high specific energy. But complex mass transport continues to hinder the reliability of such a DMFC. In this work, a two-dimensional isothermal model for a passive vapor-fed DMFC operating with neat methanol is developed to explore the triple-phase (gas, liquid and dissolved phases) mass transport and phase change. The simulation results indicate that the addition of water management layer at the cathode effectively facilitates the water recovery to the anode, especially under lower relative humidity condition. The increase of the methanol vapor supply rate alleviates the concentration polarization at high current densities, but the aggravated methanol crossover by an excessive fuel supply decreases the cathode performance. The elevated operating temperature enhances the electrochemical kinetics and mass transport, while excessively high temperature leads to the degradation of the cell performance due to significant water loss. The present work provides an effective theoretical guidance for the design and operation of a passive vapor-fed DMFC operating with neat methanol.