Abstract

This paper focuses on the design, construction and the experimental testing of an anode recirculation blower (ARB) based on a turbo-compressor for PEM-FCs. The blower presented consists of a high-speed centrifugal compressor, driven by a so-called media-gap motor. Additionally it includes a droplet separator to eliminate liquid water from the anode loop. The aerodynamic design is based on 1D-correlations and 3D-numerical CFD simulations. Different gas compositions of hydrogen, nitrogen and water vapor are considered in the design, depending on the operating points of a PEM-FC. The gas composition has a significant influence on the achievable pressure ratio at constant compressor speeds, depending mainly on the specific heat capacity of the gas. Performance maps for different gas compositions are calculated using CFD for the designed ARB. A prototype is built and tested. The results validate the CFD predictions and show that the operating range of a PEM fuel cell can be covered with the present blower. In addition, it could be shown that an enthalpy-based approach using common characteristic numbers of turbomachines, allows converting performance maps — acquired with different gas compositions — into one another. This allows the performance map prediction for different gas compositions based on existing performance maps. This approach is illustrated by numerical and experimental results.

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