Modeling Methanol Crossover by Diffusion and Electro‐Osmosis in a Flowing Electrolyte Direct Methanol Fuel Cell

Abstract

A CFD model is created to analyze methanol transport in a flowing electrolyte direct methanol fuel cell (FE‐DMFC) by solving the 3D advection‐diffusion equation, with consideration of electro‐osmosis. The average methanol flux at the anode and cathode surfaces is simulated and compared to equivalent direct methanol fuel cells. Methanol crossover is defined as methanol flux at the cathode surface, and the results reveal that methanol crossover can be drastically reduced by the flowing electrolyte. The performance of the FE‐DMFC at peak power current density is evaluated, and diffusion is shown to be the dominant contribution, although electro‐osmosis increases with current density. The power consumption of the electrolyte pump is shown to be negligible compared to the cell power output. This indicates that thin electrolyte channels with high flow rates could further improve the efficiency.

Sequential flow membraneless microfluidic fuel cell with porous electrodes

“…Many microfabricated fuel cells use membrane-based architectures which are essentially small versions of full scale fuel cell systems [2][3][4][5][6][7][8][9]. Both full scale and miniature fuel cells that use PEM membranes have significant technical challenges including water management [7,10,11], membrane degradation [12][13][14][15][16], and crossover of liquid reactants [17][18][19][20][21][22]. Some small-scale microfluidic fuel cells use flowing liquid electrolytes as a replacement for polymer electrolyte membranes (PEM) [23,24].…”

One-dimensional steady state algebraic model on the passive direct methanol fuel cell with consideration of the intermediate liquid electrolyte

“…(13) across the CD in combination with Eqs. ((4), (11), (14), (15) and (17), at the presumption of zero water saturation at CD/air interface.…”

“…Kordesch and co-workers [11,12] designed a flowing electrolyte DMFC to reduce the methanol crossover. It was simulated by Kjeang et al [13,14] that wide liquid electrolyte channel and high flow rate are required for the minimization of methanol crossover. Although their model shows that methanol crossover is effectively reduced once liquid electrolyte (LE) is incorporated, the cell polarization behavior was not revealed.…”

A membraneless microfluidic fuel cell stack

“…Miniaturized polymer membrane fuel cells that use fuels present a small scale and portable solution with high fuel conversion efficiency [5][6][7][8][9][10][11][12][13][14]. However, like their full scale counterparts, miniaturized fuel cells suffer from complications with membrane and electrode durability [15][16][17][18][19][20][21][22], water management at the cathode [23][24][25], and reactant crossover [26][27][28][29]. Such challenges increase the overall cost and maintenance and reduce the system's reliability.…”