Concept and Design of a Velocity Compounded Radial Four-Fold Re-Entry Turbine for Organic Rankine Cycle (ORC) Applications

Philipp Streit (), Andreas P. Weiß, Dominik Stümpfl, Jan Špale, Lasse B. Anderson, Václav Novotný and Michal Kolovratník
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Philipp Streit: Centre of Excellence for Cogeneration Technologies, East-Bavarian Technical University of Applied Sciences Amberg-Weiden, Kaiser-Wilhelm-Ring 23, 92224 Amberg, Germany
Andreas P. Weiß: Centre of Excellence for Cogeneration Technologies, East-Bavarian Technical University of Applied Sciences Amberg-Weiden, Kaiser-Wilhelm-Ring 23, 92224 Amberg, Germany
Dominik Stümpfl: Centre of Excellence for Cogeneration Technologies, East-Bavarian Technical University of Applied Sciences Amberg-Weiden, Kaiser-Wilhelm-Ring 23, 92224 Amberg, Germany
Jan Špale: Czech Technical University in Prague, Faculty of Mechanical Engineering, Technicka 4, Praha 6, 16607 Prague, Czech Republic
Lasse B. Anderson: Department of Energy and Process Engineering, NTNU—Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
Václav Novotný: Czech Technical University in Prague, Faculty of Mechanical Engineering, Technicka 4, Praha 6, 16607 Prague, Czech Republic
Michal Kolovratník: Czech Technical University in Prague, Faculty of Mechanical Engineering, Technicka 4, Praha 6, 16607 Prague, Czech Republic

Energies, 2024, vol. 17, issue 5, 1-21

Abstract: The energy sector faces a pressing need for significant transformation to curb CO 2 emissions. For instance, Czechia and Germany have taken steps to phase out fossil thermal power plants by 2038, opting instead for a greater reliance on variable renewable energy sources like wind and solar power. Nonetheless, thermal power plants will still have roles, too. While the conventional multistage axial turbine design has been predominant in large-scale power plants for the past century, it is unsuitable for small-scale decentralized projects due to complexity and cost. To address this, the study investigates less common turbine types, which were discarded as they demonstrated lower efficiency. One design is the Elektra turbine, characterized by its velocity compounded radial re-entry configuration. The Elektra turbine combines the advantages of volumetric expanders (the low rotational speed requirement) with the advantages of a turbine (no rubbing seals, no lubrication in the working fluid, wear is almost completely avoided). Thus, the research goal of the authors is the implementation of a 10 kW-class ORC turbine driving a cost-effective off-the-shelf 3000 rpm generator. The paper introduces the concept of the Elektra turbine in comparison to other turbines and proposes this approach for an ORC working fluid. In the second part, the 1D design and 3D–CFD optimization of the 7 kW Elektra turbine working with Hexamethyldisiloxane (MM) is performed. Finally, CFD efficiency characteristics of various versions of the Elektra are presented and critically discussed regarding the originally defined design approach. The unsteady CFD calculation of the final Elektra version showed 46% total-to-static isentropic efficiency.

Keywords: turbine; radial; velocity compounded; re-entry; Elektra; ORC (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2024
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