A Transit-Step Proton Fuel Cell Stack

The device examined here is a transit-step proton fuel cell stack intended for stationary backup power and auxiliary vehicle power. Its operating principle is that a proton-exchange stack in which the membrane is modelled with a transit-step conduction enhancement, raising the usable current density at a given cell voltage relative to an unmodified membrane. The design is computed from stated assumptions throughout; it is simulated, not measured, and no prototype results are reported. The headline result is a stack electrical output of 4.61e+03 W, obtained with hydrogen chemical power (lower heating value) of 8.02e+03 W with a computed efficiency or performance coefficient of 57.5 per cent where that measure applies, for a unit of mass 9 kg whose characteristic scale is a active area per cell of 0.02 m^2. A parameter sweep reported in the Results section shows how the output moves when the principal variable is changed, and the density of the working material, 1.5e+03 kg per cubic metre, sits about 54.8 orders of magnitude below the neutron-carrier density bound of 9.72e+57 kg per cubic metre, so the bound enters this design as a sizing ceiling and a margin statement rather than as an operating condition. The limitations are stated plainly: the enhancement is a membrane assumption; flooding and drying of the membrane remain the practical limits on sustained current density. Status: SIMULATED, NOT MEASURED.