Comparison of Efficient Boosting Technologies for Fuel Cell Applications

Authors

Dr. A. H. Taylor  PhD, BMTS Technology US Corp, Plymouth; P. Naik, S. Nibler, Dr. N. S. Al-Hasan, BMTS Technology GmbH, Stuttgart:

Year

2023

Print Info

Production/Publication ÖVK

Summary

An air compressor is a necessary component on fuel cell electric generators as fuel cells do not pull in air without an external aspiration. There are many fuel cell air compression options, each with their own benefits and drawbacks, such as roots-style screw compressors, radial e-compressors, e-turbos with wastegate, and e-turbos with a variable geometry turbine (VTG). In this paper, three different turbine stages are compared to a baseline compressor without a turbine: A low mass flow capacity wastegate turbine stage designed for a road load operating point at constant vehicle speed, a high mass flow capacity wastegate turbine stage optimized for rated power and a VTG capable of supporting both operating points. This study shows that an optimized VTG turbine stage improves PEMFC efficiency at rated power by 3%, 1.5%-points, compared to the electrically driven centrifugal compressor without turbine. The turbine optimized for the road load operating point must open the wastegate at rated power, which means it is not possible to utilize the entire exhaust gas enthalpy. The turbine optimized for rated power builds up too little backpressure at the road load operating point, thus the backpressure valve is partially closed, and the turbine power output is low. Shaft power is higher for the VTG than both the wastegate large and the small turbines. In addition, the backpressure valve can be omitted when using a VTG.

ISBN

978-3-9504969-2-5