Three-Dimensional Simulations of Liquid Feed Direct Methanol Fuel Cells

Recent research indicates that performance and design of a liquid feed direct methanol fuel cell (DMFC) is controlled not only by electrochemical kinetics and methanol crossover but also by water transport and by their complex interactions in the design regime for portable electronics applications. In this paper, a three-dimensional (3D), two-phase model is presented for DMFCs, in particular considering water transport and treating the catalyst layer explicitly as a component rather than an interface without thickness. Other features of the model are similar to an earlier version published in 2003. The DMFC model is based on the multiphase mixture formulation and encompasses all components in a DMFC using a single computational domain. A flow solver, Fluent, is employed to simultaneously solve flow, species, and charge-transport equations. Numerical simulations in 3D are carried out to explore mass transport phenomena occurring in DMFCs for portable applications as well as to reveal an interplay between the local current density and methanol crossover rate. Numerical results also indicate that the anode flow field design and methanol feeding concentration are two key parameters for optimal cell performance.