PEMFC system incorporating a methanol electrolytic reformer

Slow rate of methanol oxidation and its crossover are two major challenges for direct methanol fuel cells(DMFC). The sluggish kinetics can be relieved by elevating cell temperature which, however, leads to other problems like membrane dehydration. To solve these problems, it is proposed that a methanol electrolytic reformer(MER)is combined with polymer electrolyte membrane fuel cell(PEMFC)system. Working at elevated temperature, the MER provides hydrogen for the PEMFC and is driven by power provided by the PEMFC. Essential components included in this system are described and flows of mass, enthalpy and exergy are presented. Thermodynamic analysis shows that exergy destructions occur in main components, i. e., PEMFC and MER. The voltage of MER is an important parameter influencing the efficiency of the system. Rising temperature in MER, MER voltage required significantly decreases, but exergy losses caused by heat dissipation and heat transfer increase exponentially due to the intensified evaporation of methanol solution. To mitigate evaporation, low methanol concentration and high pressure could be necessary. When MER works at higher methanol concentration, higher pressure is required for efficient operation. The overall performance and efficiency of this system is much better than that of a DMFC. Without carbon monoxide in hydrogen generated, comparing with a competitive system in which a thermal methanol steam reformer is incorporated, this system has potentials to be built simplier.