Development of a centrifugal fan with increased part-load efficiency for fuel cell applications

Abstract Centrifugal fans are suitable for the air supply of fuel cells because of their relatively high efficiency and low power consumption. Fuel cells are operated over a broad range of current densities, which is proportional to the air mass flow rate, i.e., the air supply system needs to provide high efficiencies over a wide range of mass flow. To achieve this target, a centrifugal fan equipped with a diffuser and volute with variable cross-sectional area is developed based on numerical simulations (CFD), laser-optical flow measurements (PIV) and performance measurements of the centrifugal fan. The geometrical variability is achieved by a movable backplate of the diffuser and the volute. The variable cross-sectional area of the diffuser and volute allows maintaining high efficiencies and pressure ratios for operating points at off-design. A small diffuser width is suitable for low mass flow rates, and a large diffuser width for high mass flow rates. Thus, efficiency of the centrifugal fan can be increased at part-load operation by up to 7.1% points by appropriately adjusting the diffuser width. As a result the parasitic power consumption of the air supply system is reduced and hence the overall efficiency of the fuel cell system increases.

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