The study focuses on the design and testing of a centrifugal blower to be used for recirculating hot anode off-gas in solid oxide fuel cells (SOFC). SOFCs operate at high temperatures, even at 800 °C and typically, the anode off-gas is led out of the SOFC stack. However, nowadays it is commonly known that the efficiency of the SOFC system can be improved by recirculating the anode off-gas.
Up until recent years, the problem with the recirculation has been that there are no suitable blowers feasible enough to sustain the high temperature of the anode off-gas. In this study, a 500 W centrifugal blower having a design pressure ratio of 1.126 was designed and tested using a 50 kW SOFC application as a basis of the design, but the designs can also be applied to other applications, e.g. recirculation needs of hot air.
The blower was first tested using inlet air at room temperature and then using heated inlet air at about 300 °C. In the design phase, cooling was found one of the main challenges when hot inlet air is used. The results obtained from the test runs were well-matched with the design values.