Centrifugal Compressor for Fuel Cells

 

The objective of this centrifugal compressor test rig is the experimental verification of a system efficiency-optimally designed fuel cell turbocharger while maintaining Reynolds number similarity.

 

Construction

The test rig is driven by means of a 900 kW asynchronous motor, with the rotating drive shaft being radially fixed by means of plain bearings. Speeds of over 50,000 rpm can be achieved by means of an interposed planetary gear.

Turbochargers used to supply air in fuel cell systems must achieve a comparatively high stage pressure ratio at extremely low air flows. The former characteristic means that the dimensions of the turbocharger are generally small.

In most cases, it is then no longer possible to visualize the flow, since even the smallest probes can no longer be immersed in the flow channels or cause too strong an influence on the flow to be measured.

In order to nevertheless obtain detailed measurements of the flow, which is strongly dominated by viscous effects, scaling in the sense of enlarging the turbocharger is necessary. The measurement results are then used to verify numerical simulation methods. In order to ensure comparability of the scaled geometries, it is imperative that Reynolds and circumferential Mach number similarity be maintained. The air circuit of the present test rig is designed as a closed system that can be operated in negative pressure up to 0.25 bar. In this way, the desired detailed measurements can be carried out on the scaled fuel cell turbocharger.

 

Research Purposes

Aerodynamics

It is planned to measure the flow of the compressor in detail. This will allow the design methodology developed at the same time to be validated.