Water Recuperation from Hydrogen Fuel Cell during Aerial Mission

A water recuperation system (WRS) from an open-cathode proton exchange membrane fuel cell (PEMFC) is designed to increase the energy density of hydrogen production by hydrolysis of metal hydrides. WRS may significantly reduce the water weight in the carried fuel. The design is based on circulating the humid air through the PEMFC stack in a closed dome. To ensure oxygen supply to the PEMFC, the WRS has a ventilation inlet and an exhaust outlet. The required conditions for ventilation flow are developed theoretically and examined experimentally in a WRS prototype with a commercial PEMFC at 20–100 W. The experimental system includeds a closed dome, an edge cooling system for the PEMFC, a controllable ventilation air inlet, and an exhaust port. The humid exhaust air was cooled down to the ambient temperature to improve vapor condensation. Results show high efficiency (80% recuperated water from prediction), with a potential to achieve gravimetric hydrogen storage capacity (GHSC) of >6 wt% at an ambient temperature of 27 °C. The described principle may be applied for small fixed-wing drones where the cold ambient air may be utilized both for providing oxygen supply and for thermal management of the PEMFC and the humid exhaust, thus allowing higher GHSC.