Investigation on voltage loss mechanism for direct methanol fuel cell

Abstract

Direct methanol fuel cell (DMFC) is a device which converts chemical potential energy into electrical energy through the electrochemical reaction that involves oxidation of methanol. This study investigates the underlying voltage loss mechanism and determines how a change in process conditions will affects the resulting voltage loss, through the development of a one-dimensional mathematical DMFC model in software (MATLAB). The one-dimensional mathematical model has adopted a modelling approach that is simple and relatively easy to be constructed, thus providing a method for simple yet accurate estimation of the DMFC voltage loss curve. The study is conducting in three stages, which include the construction of preliminary model, model parameter fitting and model simulation. Based on the developed DMFC model, the polarization curve of a DMFC are dividing into three regions, including activation polarization-controlled region, ohmic drop controlled region and concentration polarization-controlled region. In each of these regions, one of the voltage loss mechanisms is the dominant mechanism that causes the greatest voltage loss. Voltage loss from all three mechanisms are finding to be reduced at higher temperature. The simulated DMFC can operate at a maximum power density of 0.15 W/cm2, with a voltage efficiency of 33.9%. This model operates at temperature of 343K and uses 2M methanol concentration.