Study On Small PEMFC Stacks With Cathode Interdigital Flow-field

Proton exchange membrane fuel cell (PEMFC) because of its low operating temperature, short starting time, high power density, is taken the new generation of electric automobile power supply, the portable small source, the family and so on receive enterprise's the and so on, various countries' government and energy, automobile, electrical and other corporation give widespread attention, high take and vigorous support. Small power PEMFC has been a hotspot and attracts more and more governments and companis' interesting. Small power PEMFC wants to enter the market, the system must be minished. Self-humidified is the most ideal choice for small PEMFC system. This text designed a cathode interdigital flow field, the air in the adjoining channel flow vis-a-vis in the field. The reaction water masses in the back sect channel, and diffuse the adjoining channels. In this way it will humidify the cathode flow field. By mathematic model and Fluent software simulation analyzed the gas and water distribution in the interdigital flow field. Using this flow field, assembled a single cell and tested its performance. At the same time, some of conclusions had been summarized as following:(1) On the self-humidification condition ,the reaction water is more than the saturation exhaust gas contains, otherwise, The cell might be dry. The water exhaust gas contains increase with the exhaust gas increasing and the cell temperature. When the cell work on 60℃, the air stoichiometry does not exceed 3.45, the hydrogen stoichiometry does not exceed 6.84,. . When the temperature increases to 80℃, the air stoichiometry does not exceed 1.65, the hydrogen stoichiometry does not exceed 2.67.(2) Because the gas flow vis-a-vis in the interdigital flow field, there is pressure difference. The gas shot circuit occurs between the channels. The shot circuit relates to the channel parameter and gas diffuse layer parameter. To the flow-field designed in the paper, there is less than 16.8% gas leaks into the adjoining channel. The water distribution nephogram indicated that the water density in the zone between channels is higher. The most area of cathode flow field is nearly saturated. The water is decreasing severely along the thickness, in the anode, the most water density is only 1.79mol/m~3.(3) The test date indicates that on the condition which the temperature is 60℃,the air stoichiometry is 3.0 and the hydrogen stoichiometry is 1.5, the cell can run stably. The peak power density is 0.35W. When the temperature is 80℃,the performance decline serious; If humidify the hydrogen properly, the performance would increase. When the humidity is 50%, the peak power is 16.7W, when it increases 80%, the cell does not work stably.