The Study Of Water Management In Bionic Flow Field Structure For PEMFC

Development of new energy becomes more and more important in company withenergy crisis and environmental pollution. Proton exchange membrane fuel cell(PEMFC) is becoming the ideal hydrogen energy device as its high-efficiency andpotential and the research and application of PEMFC are being paid more and moreattention to. How to improve the performance of PEMFC has became one of theresearch hotspots and difficulties.Water is one of the most important factors significantly influencing theperformance of fuel cell among the many. Water management which is to keep thebalance of water in cells is one of the difficult issues in the research. The flow field isthe flow channel of reaction gases and water discharge channel in PEMFC, itsstructure has a directly important influence on the performance of PEMFC. Based onthe flow field of PEMFC, this article studied and analyzed the improving effect of thewater management of bionic flow field.In this paper, the result is based on the simulation data which comes from thePEMFC simulations model built by the CFD. In comparison with the tradition flowfield(parallel flow field and serpentine flow field),the bionic flow field perform muchbetter considering the data such as I~V curve, power density, pressure loss, thedistribution of the reactants and products, heat distribution and water content inmembrane from the simulation models under the circumstance of high power output.The water management issue on the condition of high current and low current is alsodiscussed in this article. Water is more easily to discharge in bionic flow field at thehigh current density when the vast amounts of water is generated while when the cellperforms at low current density where water scarcity usually occurs,the distributionof water and gases in bionic flow field can be more uniform due to the betterdiffusion.The water management and the performance of cell will change as the changingof the operation condition. In this article, the output performance get better with increasing humidity, the decreasing temperature of inlet gas and the increasingpressure of the inlet gas. Humidity, temperature and pressure have much impact onthe water management of bionic flow field. The greater relative humidity, the moremoisture of membrane, and the more water in the flow field and the lower reactiongas concentration on the surface of catalyst layer. At the same time, when theoperation temperature get lower, the more moisture of membrane, the gasesconcentration on the electrode will decrease. With the operation pressure increasing,the moisture of membrane increase. In the meantime this will block water diffusionfrom cathode to anode to some extent, which will lead to the water in anode get lessand much more in cathode.