Analyzing leakage current in a direct methanol fuel cell

A mathematical model is developed to study the transient leakage current in a direct methanol fuel cell (DMFC) system. The DMFC is divided into five sections-the anode backing layer (ABL), anode catalyst layer (ACL), membrane, cathode catalyst layer (CCL), and cathode backing layer (CBL). The concentration of methanol across the five layers is evaluated as a function of time, methanol feed concentration, temperature, and methanol flow rate. The transient behavior of leakage current is studied as a function of flow rate and current density. Potential drop across the membrane is found to play a significant role in the leakage current. However, the effect of potential drop across the membrane on the overall performance of a DMFC seems to be very limited. Polorization curves are simulated as function of time, temperature, and input methanol flow rate. Modeling results are compared with experimental data (variation of polarization curves with temperature) and found to compare very well.