Two-way Operations of a DMFC with aￂ Vapor Feed and With a Liquid Feed

Using a cell module with a porous carbon plate, two-way operations of a specific direct methanol fuel cell (DMFC) with a vapor feed (VF) of neat methanol and a liquid feed (LF) of a dilute methanol solution were conducted, and the cell performances were compared to each other in order to clarify which condition produced the better performance. The comparison was conducted at different air humidities, i.e., 30, 60, 90 and 100%, and cell temperatures, i.e., 313, 323 and 333 K. As a result, about a 10% higher power density was obtained by the LF-DMFC, whereas about a 2% higher efficiency was obtained by the VF-DMFC at the optimum air humidity and 323 K. These performances were achieved by significantly different mass transports through the membrane.