Numerical Simulation Study On Self-breathing Fuel Cell

With the rapid development of electronic industry, the demand for micro-poweris increasing. Microfluidic fuel cell is considered to be the advanced power sourcewhich has small volume, light weight and high theoretical capacities. Therefore,theresearch on Microfluidic fuel cell stacks and design of microfluidic fuel cell withhigh working performance is valueable.The main objective of this research is (1)to find reasonable suructures ofchannel for fabrication of all-vanadium microfluidic fuel cell stacks.(2) comparisonresearch on the working performance of vanadium air self-berathing microfluidicfuel cell and vanadium dissolved oxidant microfluidic fuel cell, as well as theworking performance of vanadium air self-berathing microfluidic fuel cell undervarious working conditions.(3) the working performance of zinc air fuel cell undervarious working conditions.Firstly, three suructures of channel for all-vanadium microfluidic fuel cellstacks were proposed.And its working performance was researched.Single cell of thecell stacks with bilateral inlets has maximum velocity with even distribution.its hasgood working performance.but the fuel utilization is only6.92%. The velocity in thechannel of single cell of the cell stacks with bilateral inlets is uneven distribution.Itsworking performance is better than the cell stacks with ipsilateral inlets. the fuelutilization is32.93%. the working performance of the cell stacks with opposite inletsis worse.and fuel utilization is low. Channel with opposite inlets doesn’t used forall-vanadium microfluidic fuel cell stacks.Secondly,vanadium air self-bearthing microfluidic fuel cell was first proposedand researched.Oxygen in air is used as oxidant.And the oxidant directly diffused toGDE. Oxygen in air is free.Vanadium air self-breathing microfluidic fuel cell andvanadium dissolved oxygen microfluidic fuel cell was researched. Vanadium dissolved oxygen microfluidic fuel cell is limited by the mass transfer ofoxygen.Oxygen can’t diffuse to cathode in time.Working performance and fuelutilization was very poor. Oxygen in cathode channel can diffuse to anode channel.And there is no self-discharge. Vanadium air self-bearthing microfluidic fuel cell canovercome the limitations of the mass transfer of oxygen.This type of cell has highworking performance and high fuel utilization.there is low an oxygen level inchannel.Thirdly,an exhaustive research on working performance of vanadium airself-breathing microfluidic fuel cell was did by us.There were some results asfollows.(1). Catalyst in cathode affected the performance of vanadium air self-breathingmicrofluidic fuel cell, significantly. Activation of voltage loss of the cell withcatalyst was low. In the case of the same discharge current,the cell had highervoltage.Its maximum power density can be increased by more than8times.(2). The amount of catalyst and the size of the catalyst can also improveperformance of the cell. When the amount of catalyst increased from0.055mg/cm2to0.55mg/cm2, the maximum power density increased about7mW/cm2.When thesize of the catalyst decreasesed from5nm to0.5nm, the maximum power densityincreased about8mW/cm2.In order to reduce cost,The best way to improve cellperformance is reduction in catalyst volume.(3). The workplace has an effect on the working performance of vanadium airself-breathing microfluidic fuel cell,but it is little effect.So the cell has good workingstability in different places.(4). The open-circuit voltage of the cell and the oxygen diffusion coefficientincreases with increasing environmental temperature.And the cell has the betterworking performance.Finally, in this article,a one-dimensional multiphysics modeling of zinc airself-bearthing fuel cell was builded.There were some result as follows.(1). The voltage of the cell increases with increasing oxygen concentration,appreciably.So this way to increase the voltage is not worthy. (2). the voltage of the cell decreases linearly with the increase of the dischargecurrent density.And the working time of the cell decreases exponentially with theincrease of the discharge current density.(3). The voltage of the zinc air self-bearthing fuel cell increases with increasingenvironmental temperature by comparing with the working performance of the cellin different temperature(273K,298K,303K).(4). Hydroxide ions don’t participate in the overall redox reaction,but itsconcentration at the cathode and the anode varies because of half-reachtion.Sohydroxide ion can influence the working performance of the cell to a certain extent.The working time and voltage of zinc air self-bearthing fuel cell increases withincreasing hydroxide ions concentration(2100mol/m3,3500mol/m3,8000mol/m3).(5). The working time and voltage of zinc air self-bearthing fuel cell increaseswith decreasing the size of the particles of zinc.