Transient analysis of passive direct methanol fuel cells with different operation and design parameters

By developing a transient multiphase model for passive direct methanol fuel cell (DMFC), the effects of operating current density, voltage, micro-porous layer (MPL) and methanol feeding condition are comprehensively investigated for the whole operating processes (fuel tank from full to empty). It is found that for all the operating conditions, it is necessary to operate at Moderate current density or voltage to limit the methanol crossover and ensure the energy conversion efficiency. The MPL in anode is needed to provide sufficient flow resistance at the MPL/gas diffusion layer (GDL) interface to improve the fuel efficiency. Although the cathode MPL can strengthen the convective transport of methanol from cathode to anode, its effect on reducing methanol crossover is less significant than the anode MPL. If the energy density is the most important factor, it is suggested to operate with sufficiently high methanol feeding concentration; and if the fuel and energy efficiencies have the priority, the methanol feeding concentration needs to be moderate. Increasing the size of fuel tank generally improves the energy density, but has negligible effect on the fuel and energy efficiencies. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.