空气抽吸式甲醇燃料电池传热与传质特性

Heat and mass transfer characteristics in ducted air-breathing direct methanol fuel cells

空气抽吸式直接甲醇燃料电池不仅具有被动式燃料电池的优点,同时又便于将其串联成电堆提高输出电压。建立以阴极为管道抽吸式结构的直接甲醇燃料电池的三维、两相、非等温稳态数值模型,研究了质子交换膜性能、供给甲醇浓度以及电堆规模对电池性能及燃料利用率的影响。对于保温较好的大电堆,采用低甲醇穿透的改性质子交换膜能同时提升燃料利用率和比功率;此类电堆若采用穿透率低的改性膜,则2 mol/L的甲醇浓度就能保证电池在较大的电流密度区间内维持较高的功率与效率。作为影响电池运行温度的重要因素,电堆规模的大小将直接影响质子交换膜种类与甲醇浓度等关键参数的设计与选择。

Ducted air-breathing direct methanol fuel cells （DMFC） not only has the advantages of passive fuel cells, but also can be assembled in series easily to raise the output voltage. A three dimensional, steady state, non-isothermal and steady numerical model has been developed for the ducted air-breathing DMFC. The effects of proton exchange membrane （PEM） properties, supplying methanol concentration and the size of cell stack on both the fuel efficiency and cell performance were investigated. The numerical results indicate that using the modified PEM with low methanol crossover, for large cell stack with good thermal insulation, can improve fuel efficiency and power density. High fuel efficiency and power density of such cell stack with modified PEM can be maintained in a wide current density range while using 2 mol/L methanol. As a key factor in determining cell temperature, stack size has great impact on designing and selecting other important param- eters, such as PEM properties and methanol concentration.