Characterising PEM fuel cell performance using a current distribution measurement in comparison with a CFD model

The characterisation of a proton exchange membrane (PEM) fuel cell with a straight channel flow field design is performed. Spatially resolved current distribution measurements, at different air flow rates, are compared to numerical simulation results. The numerical model is validated by agreement of the measured and simulated current distribution. The test cell is segmented. It is operated at steady state conditions and the gas flow rates and cell temperature are controlled. The numerical simulation is realised with a PEM fuel cell model based on FLUENT(exp TM) computational fluid dynamics (CFD) software. It accounts for mass transport in the gaseous phase, heat transfer, electrical potential field and the electrochemical reaction. It provides three-dimensional distributions of, e.g., current densities, reactant concentrations and temperature

Investigation of fractal flow-fields in portable proton exchange membrane and direct methanol fuel cells

The flow-field design can have great influence on the operating performance of both proton exchange membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs). Inhomogeneous transport of reactants to and products from the active area of these low-temperature fuel cells result in loss of power. Newly designed fractal structures are tested as flow-fields in PEMFCs and DMFCs for portable applications. To achieve a uniform fluid distribution and simultaneously minimize energy demand for mass transport (pressure loss), a computer algorithm is developed to provide a given area with a multiple ramified fluid network. By virtue of the self-similarity, the structures of such a network are called fractals. These are investigated and compared with common serpentine and parallel flow-fields. For both PEMFCs and DMFCs fractal flow-fields show similar performance to parallel designs. The most stable and highest power output is reached with the serpentine flow-field