Heterogeneous Dual-Source Fuel-Cell Powertrain for Battery-Free Electric Aircraft: A Feasibility Simulation Study

Abstract

Hydrogen fuel-cell propulsion for regional aircraft is presently constrained by transient performance that falls short of what the application requires, at both stack and system level. This is commonly addressed by adding a battery or supercapacitor to absorb rapid load changes, though the additional mass and volume reduce the attractiveness of fuel-cell propulsion. This paper proposes an alternative: to employ two fuel-cell sources, one mainly for steady-state operation and a second specialised for transient loads, so that the powertrain follows load changes without additional stored energy. Such heterogeneity between sources does not appear to have been examined as a means of meeting flight transients. A simulation study is reported, comparing this dual-source powertrain against a single-source configuration sized to deliver the same aggregate nominal exchange current, neither of which uses a battery or other storage device. For a commanded load rise, the dual-source configuration reduces peak current in the primary fuel-cell source by 36% and requires 29% less total membrane area, while delivering 7.5% more peak propeller power at 7.0% higher mean efficiency. Peak current density in the primary source is unchanged; the relief is therefore not obtained by operating any part of the system harder. The auxiliary fuel-cell source sustains a rate of change of current density approximately 5.7 times that of the primary source, and leads it in phase, indicating a division of labour in timing as well as in magnitude. The advantage persists across repeated load events. These results are obtained from a single load profile, with parameters that are calibrated, not independently validated. They establish a precondition for flight capability, not a demonstration of it. Nevertheless, they indicate that heterogeneous parallel fuel cell sources merit further investigation as a route to battery-free fuel-cell aircraft.