Centrifugal Compressor Preliminary Design Optimization for a Hydrogen Pipeline Compression Station

Abstract As the demand for hydrogen is expected to increase in the coming years, infrastructure requirements for the transport and storage of hydrogen should follow this trend to reduce its cost for users. For example, the European Hydrogen Backbone (EHB) represents a milestone toward a more accessible hydrogen network of pipelines. New compressors will be necessary to feed those pipelines, and for the volumes of hydrogen considered, only centrifugal compressors would be an adequate solution. But centrifugal compressors for hydrogen are a complex matter. Many technical issues are still under ongoing research, such as leakage through bearings and seals or materials problems due to hydrogen embrittlement. This work introduces a method to optimize the preliminary design of a centrifugal compressor for hydrogen applications. This optimization is based on the variation of geometrical parameters of the impeller to minimize the energy required to power the compressor. This optimization can be applied for a steady state operation or for an unsteady set of operation. Furthermore, this optimization process of a centrifugal compressor stage extends to the optimization of multiple stages compressors, but also for the optimization of the arrangement in series and/or in parallel. This method is then applied to different case studies of a possible compression station pre-design for a hydrogen pipeline application. The compression station is tested under steady state conditions for a pressure ratio of 1.2 and a mass flow rate of 2.8 kg/s. Then it is tested on a transient flow, with variations of the mass flow rate of up to 10 percent.