Water Crossover Experiments in an Open-Cathode Direct Methanol Fuel Cell

Abstract

A direct methanol fuel cell (DMFC) that does not require an external water feed or a powered water-recovery system has potential for wide application in portable electronic devices. This paper provides experimental data for the water recovery rate in a novel DMFC design featuring a hydrophobic cathode gas-diffusion layer that allows for passive water recovery. Water and methanol crossover rates were experimentally characterized by measuring the water vapor and carbon dioxide concentration at the cathode exit with an infrared sensor. The result showed that the mass-transport parameter of water vapor, increases linearly with increasing cell temperature and remains invariant with respect to the cell current density. Water neutrality of the DMFC stack was achieved while the cell operated close to 50 °C and 150 mA/cm2 with a 1M methanol solution. A comprehensive empirical equation based on the experimental results is presented, along with system-level insights into the controllability of water management in designing an open cathode DMFC system.

Comprehensive mass transport modeling technique for the cathode side of an open-cathode direct methanol fuel cell

“…Consistent with prior work carried out in our laboratory facilities [41,54,55], the independently manipulated operating variables are the following: the methanol feed concentration at the anode fuel inlet, the anode fuel flow rate, the operating temperature, and the load current density. These experimental factors are adjusted as shown in Table 4.…”

“…The air flow rate in the cathode flow channels is adjusted using a controller to maintain the operating cell temperature at a specified set point. Further details of the setup are given in the literature [41,54,55].…”

“…The second reason follows from the fact that, at very high currents, the resistance to diffusive oxygen transport in the LDL increases significantly. In fact, note that Equation (50) along with (52) and (54) indicate that the diffusive mass transport coefficient of oxygen through the gaseous phase in the LDL depends on the quantity 1 À s LDL [ . Given that Fig.…”