直接甲醇燃料电池阴极水淹过程实验研究

EXPERIMENTAL RESEARCH ON THE CATHODE FLOODING OF A DMFC

对自制可视化直接甲醇燃料电池单体阴极流场内液滴生长特性、氧气流量和氧气进气温度对流场水淹及电池性能的影响进行了实验研究。结果表明:平行流场中首个液滴大多在流场右上区域冒出;流场中新液滴的出现具有瞬间涌出特性,并优先在流场板和扩散层交界的夹角处及扩散层表面碳纤维束交叉处产生;液滴生长过程具有非连续性,与流道边壁相接触的液滴和液柱的生长速度均大于未接触流道边壁的液滴生长速度,而且液柱有逆气流方向反向生长现象。氧气流量及氧气进气温度的升高,均导致阴极流道内液态水和流场中大液滴数量及形成液柱的长度减少,促使电池性能提高。

Visual experiments were conducted for studying the dynamic behaviors of liquid droplets and the effects of inlet oxygen flow rate and inlet oxygen temperature on the cathode flooding and cell performance for the parallel cathode flow field of an in-house fabricated direct methanol fuel cell （DMFC）. The results show that the first droplet usually emerged at the up-right region of parallel flow field and most liquid droplets easily appeared at the downstream of channels. The growth of new droplets has the instant effusing character and the pores around the corner of the channel ribs and the intersection of the carbon cloth fibres were favored sites for the emergence of liquid droplets. The droplets has the character of pulsed growth, the land-touching droplets developing on each side of the channel and water columns grow faster than those exhibiting no contact with the channel wall, and some water columns growth direction reversed the oxygen flow direction. Both a higher oxygen flow rate and a higher inlet oxygen temperature can accelerate the removal of the water in the flow channels and lower the fraction of coverage that enhanced the mass transfer of the oxygen and improve the cell performance.