Two-phase flow in anode serpentine flow field of a direct methanol fuel cell

Fuel Cells have attracted much attention. Liquid fed direct methanol fuel cells (DMFCs), which have many important advantages over such as the easy storage and refilling of the aqueous methanol solution, are considered to be good choices for small mobile devices. Water and carbon dioxide are the sole fuel oxidized byproducts. The anode side of liquid fed DMFC is a two-phase system primarily consisting of methanol solution and carbon dioxide bubbles. In this paper, a transparent direct methanol fuel cell was designed and fabricated for investigations of two-phase flow characteristics in anode serpentine flow field. In situ observations of the carbon dioxide bubbles and two-phase flow patterns inside the flow field were made. The effects of cell current, methanol solution flow rate and methanol solution mole concentration on the flow patterns and cell performance were studied, respectively. Experimental results indicate that the electrochemical reaction and two-phase flow characteristics interacted each other. The mean size of CO2 bubbles and the gas void fraction increased with increase in current density. The typical flow patterns are bubbly flow and slug flow. At the upside down U type location of the serpentine channel, long slug bubbles easily formed and blocked the channel. The gas void fraction decreased with increase in methanol solution flow rate. The methanol solution mole concentration influences the two-phase flow slightly.