Flow loss mechanism of a novel co-rotating scroll hydrogen recirculation pump for fuel cell systems

The hydrogen recirculation pump is a key component of fuel cell systems. The aerodynamic performance of a novel co-rotating scroll hydrogen recirculation pump with the array scroll structure was investigated in this study. The performance differences between the co-rotating and orbiting scroll pumps were obtained via computational fluid dynamics approach. The flow loss mechanism of the co-rotating scroll pump was revealed by the entropy production analysis and omega vortex identification. The results show that compared with the orbiting scroll pump, the co-rotating one has a better over-compression consistency between adjacent working chambers, and a higher isentropic efficiency with a lower direct dissipation entropy production. Main flow losses of co-rotating scroll pump originate from the turbulent and direct dissipations in scroll chambers, and mainly occur in the discharge process. The large-scale omega vortices flow is responsible for the pump flow losses. The strengthened large-scale omega vortex expands the area of high entropy production in central discharge region. The suction flow losses increase due to the strengthened suction flow separations. The total area of omega vortex in the surrounding and central regions contrarily change with the pump isentropic efficiency. The smallest area of omega vortex represents the minimum flow loss of the co-rotating scroll pump at 7500 r·min⁻¹.