Flow Resistance Characteristic And Visualization Experiment Of Direct Methanol Fuel Cell

Direct methanol fuel cell (Direct Methanol Fuel Cell,DMFC) has many important attributes: low market price of methanol, quick refueling, low temperature and pressure operation etc. It has been considered as highly promising power sources. A variety of research groups have been active in the design and optimization of fuel cell configuration. Especially, the fluid mechanic and pressure drop behavior of DMFC should be considered, because the fluid mechanic and pressure drop behavior of DMFC flow field have important influence on the distribution of reactants, resultant drainage and the whole efficiency of fuel cell system.This paper is mainly made of these parts. First, a 3×3cm2 MEA is made, a visualization research and the flow resistance experiment about the cathode of direct methanol fuel cell(DMFC) in room temperature and ambient pressure; a visualization research and the flow resistance experiment about the anode of direct methanol fuel cell(DMFC). The main results as follows:①The effect of pressure difference between anode and cathode, oxygen flow rate, oxygen temperature on the performance of DMFC and water transport in cathode are studied respectively. The emergence, enlarging, coalesce and movement of water droplet in cathode are observed. The results show that the droplets always emerge from the corners formed by channel and the gas diffusion layer. Increasing the pressure difference between anode and cathode can improve the performance of DMFC; we can get from the visualization picture and the performance curve, the water droplets in the channels and the"flooding"decrease as increasing the oxygen flow rate, the performance of DMFC improved. Improving the oxygen temperature can improve the performance of fuel cell.②In the flow resistance experiment about the cathode, the parallel flow field , the serpentine flow field and the interdigitated flow field are respectively taken as the cathode flow field ,the influence of the flow rate, inlet temperature, current density, flow field configuration on the pressure drop between inlet and the outlet are considered. the result show that increasing the flow rate can improve the pressure drop, the pressure drop decreased when the inlet temperature is increased, the pressure drop decrease with the increase current density; the interdigitated flow field can improve the pressure drop between inlet and outlet relative to the parallel flow field and the serpentine flow field, The pressure drop between inlet and outlet of anode decrease when the width or the depth of the flow field increase.③In the flow resistance and visualization experiment about the cathode, the parallel flow field , the serpentine flow field and the interdigitated flow field are respectively taken as the anode flow field, the effect of the flow rate, inlet temperature, current density, flow field configuration, methanol solution concentration on the pressure drop between the inlet and the outlet of anode are studied respectively, the results showed the pressure drop is improved with the flow rate increase, the pressure drop of parallel flow field is increased with the improved temperature, the pressure drop of serpentine flow field is decreased until it reached 50℃,then the pressure drop increased. with higher temperature, the fuel cell performance become better, improving the current density can enhance the pressure drop, the pressure drop in the interdigitated flow field is the biggest, the fuel cell performance with the interdigitated flow field is the best among the three kinds of flow fields; Pressure drop between inlet and outlet of anode decrease when the width or the depth of the flow field increased. Higher methanol solution concentration result in the smaller pressure drop, the methanol concentration should not be too high and the better methanol concentration was 1.5mol/L; the pressure drop between the inlet and the outlet of the anode changes regularly with the emergence, coalesce, expelling of CO2 bubble.