Experimentally Validated Improvements Of A Cathode Air Compressor For Pem Fuel Cells By Fixed Diffuser Vanes

This study presents first-time experimental investigations of an electric turbocharger for the fuel cell air supply with different range-extending features in the centrifugal compressor. Experiments show the potential of pivoting the diffuser vanes: The surge margin of the compressor increases by up to 44.7 percentage points. This can be used to adapt the compressor map to the operating range requirements of an automotive fuel cell. However, due to efficiency losses, the compressor power consumption increases when the fuel cell is operated at full-load. Further experiments with different leading edge angles of the diffuser vanes demonstrate that the map of the centrifugal compressor can be shifted towards lower mass flow rates even by a fixed-geometry diffuser. While the original compressor can only cover 68 percent of the total fuel cell's operating range with a surge margin of 20 percent, a compressor with adapted leading edge angles of the diffuser vanes covers over 75.7 percent. By linearly reducing the leading edge angle over the vane height, the compressor power consumption decreases over the entire operating range of the fuel cell. A reduced power consumption of up to 6.3 percent is achieved at part-load.