| Conventional proton exchange membrane fuel cell(PEMFC)consists of a membrane electrode assembly(MEA)and bipolar plates.Among them,the bipolar plates are an important part of the fuel cell.However,due to the existence of ribs and channels on the bipolar plate,the reactant concentration and temperature are not evenly distributed on the MEA,thus the catalyst cannot be better used in this kind of structure.Therefore,porous metal material flow field is considered as a potential candidate to improve the defects of conventional flow field in a fuel cell.In this study,we developed a new type of multi-tooth tool and a cutting device for the fabrication of metal fiber using copper wire.The porous metal fiber sintered sheet is used as porous flow field in PEMFC.The conductivity,diffusivity and corrosion resistance of porous flow field were studied,and the performance of porous flow field fuel cell was experimentally studied.The main contents are as follows:(1)A cutting device for the fabrication of metal fiber using copper wire was developed,and then the cutting mechanism of copper fiber was discussed and analyzed by using a FEM software.Besides,the effect of processing parameters on the equivalent diameter and surface morphology of copper fiber was investigated in detail through experiments and simulations.Finally,the feasibility of metal fiber processing is verified and the processing efficiency of metal fiber is improved.(2)The porous metal fiber sintered sheets with different porosities were fabricated by low-temperature solid-phase sintering technology,and their characterization and forming mechanism were analyzed.Meanwhile,the model of the porous metal fiber sintered plate was established by Rhino software and its plug-in Grasshopper,and the forming mechanism of porous metal fiber sintered plates with different porosities was studied.(3)The pressure and flow velocity distribution of the reaction gas inside the flow field were analyzed by using the Fluent simulation software,revealing the uniformity of pressure distribution and velocity distribution of reaction gas in porous flow field.At the same time,the effect of different humidification temperature and cell temperature on the performance of porous flow field fuel cell was investigated,and the optimal humidification temperature of cathode and anode and cell temperature were obtained.In addition,the effect of porous flow field with different porosities on the performance of fuel cell was studied.(4)To optimize the porous flow field,a mixed flow field was proposed.The porous copper fiber sintered sheet with the optimal porosity was used as the substrate of flow field,and combined with the copper mesh.Therefore,a porous flow field was mixed and sintered,which was applied to proton exchange membrane fuel cell.The influence of different operating conditions and different mesh numbers of copper mesh on the performance improvement of fuel cell was systematically explored,which made the porous flow field fuel cell obtain better performance. |
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