Numerical Simulation of Direct Methanol Fuel Cells (DMFC)

Abstract

A detailed reaction network for the Catalytic Wet Air Oxidation of phenol on a CuO/ c-Al 2 O 3 catalyst is proposed. The experimental data was obtained from a continuous trickle bed reactor, using air as oxidant, three reaction temperatures (120, 140 and 160 C) and three oxygen partial pressures (6, 9 and 12 bar). The kinetic modelling was designed in terms of the detected compounds without lumping, as usually done. The reaction pathway considers 8 compounds, 8 different reactions and up to 38 parameters. Simple power law as well as Langmuir±Hinshelwood expressions accounting for adsorption effects were checked in the modelling of the reaction network. The incorporation of Langmuir±Hinshelwood expressions significantly improved predictions for all intermediates. Model parameters were simultaneously evaluated by means of a robust stochastic non-linear multiparameter estimation approach called Simulated Annealing.A DMFC model has been developed which is geometrically defined in a one-or two dimensional domain with a boundary described by a closed polygon. The modelling comprises the water and gas transport in the diffusion and catalyst layers using a two-phase flow model including capillary pressure effects in wettable and nonwettable pores. The gas transport follows the multicomponent Stefan-Maxwell equation. For the first time, a detailed description of the electrochemical reaction kinetics is involved in a DMFC model. The cell simulation reveals the irreversible cathode kinetics caused by the methanol transport through the cell together with the wettability the cathodic diffusion layer to be responsible for the performance losses.

Efficient Parallel Simulation of Direct Methanol Fuel Cell Models

“…Siebke et al [6] presented a mathematical model and a numerical simulation to examine the influence of the different physical and electrochemical phenomena in the multi-layer structure of the membrane-electrode assembly of the liquid feed DMFC. Divisek et al [7] developed a model which is geometrically defined in a one-or twodimensional domain with a boundary described by a closed polygon. Dohle et al [8] presented a model to describe the heat and…”