The maximization of an alkaline membrane fuel cell (AMFC) net power output

Abstract

This study optimizes numerically the relative sizes, spacings (internal structure), and aspect ratios (external configuration) of a single alkaline membrane fuel cell for maximum net power. The alkaline membrane fuel cell (AMFC) cellulosic membrane brings new light to the possibility of having alkaline fuel cells that are nontoxic and asbestos free as compared with static electrolyte cells that use an asbestos separator and ammonium-based alkaline anion-exchange membranes. A dimensionless dynamic mathematical model is utilized in the process, and the results are presented in normalized charts for generality. Two degrees of freedom are considered as follows: (i) the relative thicknesses of two reaction and diffusion layers and the membrane space (internal structure); and (ii) the external aspect ratios of a square section plate that contains all single alkaline membrane fuel cell components (external configuration). The optimized internal and external configurations result from the optimal balance between electrical power output and pumping power to supply fuel and oxidant to the AMFC. A third level of optimization is found, that is, the KOH mass fraction in the electrolyte that leads to a 3-way-maximized net power output. A sixfold variation in AMFC net power output is observed as the internal and external configurations, and KOH mass fraction are changed. Such effect stresses the importance of pinpointing the optimal AMFC configuration in order to avoid poor performance. New algebraic correlations are derived to indicate in dimensionless form, the optimal configurations for the internal and external structure, and resulting maximum net power output, which are important for scaling up and down the AMFC design with ease, without having to perform new simulations. Copyright © 2016 John Wiley & Sons, Ltd.