Development and validation of an all-metal scroll pump for PEM fuel cell hydrogen recirculation

Hydrogen recirculation is essential for maintaining fuel efficiency and durability in Proton Exchange Membrane Fuel Cell (PEMFC) systems, particularly in automotive range extender applications. This study presents the design, simulation, and experimental validation of a dry, all-metal scroll pump developed for hydrogen recirculation in a 5 kW PEMFC system. The pump operates without oil or polymer seals, offering long-term compatibility with dry hydrogen. Two prototypes were fabricated: SP1, incorporating PTFE-bronze tip seals, and SP2, a fully metallic seal-free design. A fully deterministic one-dimensional (1D) model was developed to predict thermodynamic performance, including leakage and heat transfer effects, and validated against experimental results. SP1 achieved higher flow rates due to reduced axial leakage but experienced elevated friction and temperature. In contrast, SP2 provided improved thermal stability and lower friction, with slightly reduced flow performance. The pump demonstrated a maximum flow rate of 50 l/min and an isentropic efficiency of 82.2 % at 2.5 bar_a outlet pressure. Simulated performance showed strong agreement with experimental results, with deviations under 5 %. The findings highlight the critical role of thermal management and manufacturing tolerances in dry scroll pump design. The seal-free, liquid-cooled scroll architecture presents a promising solution for compact, oil-free hydrogen recirculation in low-power fuel cell systems.