Experimental Characterization of an Adaptive Supersonic Micro Turbine for Waste Heat Recovery Applications

Tobias Popp, Andreas P. Weiß, Florian Heberle, Julia Winkler, Rüdiger Scharf, Theresa Weith and Dieter Brüggemann
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Tobias Popp: Chair of Engineering Thermodynamics and Transport Processes (LTTT), Center of Energy Technology (ZET), University of Bayreuth, 95440 Bayreuth, Germany
Andreas P. Weiß: Center of Excellence for Cogeneration Technologies, Technical University of Applied Sciences Amberg-Weiden, 92224 Amberg, Germany
Florian Heberle: Chair of Engineering Thermodynamics and Transport Processes (LTTT), Center of Energy Technology (ZET), University of Bayreuth, 95440 Bayreuth, Germany
Julia Winkler: DEPRAG SCHULZ GMBH u. CO., 92224 Amberg, Germany
Rüdiger Scharf: DEPRAG SCHULZ GMBH u. CO., 92224 Amberg, Germany
Theresa Weith: Chair of Engineering Thermodynamics and Transport Processes (LTTT), Center of Energy Technology (ZET), University of Bayreuth, 95440 Bayreuth, Germany
Dieter Brüggemann: Chair of Engineering Thermodynamics and Transport Processes (LTTT), Center of Energy Technology (ZET), University of Bayreuth, 95440 Bayreuth, Germany

Energies, 2021, vol. 15, issue 1, 1-20

Abstract: Micro turbines (<100 kW el ) are commercially used as expansion machines in waste heat recovery (WHR) systems such as organic Rankine cycles (ORCs). These highly loaded turbines are generally designed for a specific parameter set, and their isentropic expansion efficiency significantly deteriorates when the mass flow rate of the WHR system deviates from the design point. However, in numerous industry processes that are potentially interesting for the implementation of a WHR process, the temperature, mass flow rate or both can fluctuate significantly, resulting in fluctuations in the WHR system as well. In such circumstances, the inlet pressure of the ORC turbine, and therefore the reversible cycle efficiency must be significantly reduced during these fluctuations. In this context, the authors developed an adaptive supersonic micro turbine for WHR applications. The variable geometry of the turbine nozzles enables an adjustment of the swallowing capacity in respect of the available mass flow rate in order to keep the upper cycle pressure constant. In this paper, an experimental test series of a WHR ORC test rig equipped with the developed adaptive supersonic micro turbine is analysed. The adaptive turbine is characterized concerning its off-design performance and the results are compared to a reference turbine with fixed geometry. To create a fair data basis for this comparison, a digital twin of the plant based on experimental data was built. In addition to the characterization of the turbine itself, the influence of the improved pressure ratio on the energy conversion chain of the entire ORC is analysed.

Keywords: organic Rankine cycle; thermodynamic evaluation; waste heat recovery; cantilever turbine; supersonic turbine; adaptive turbine (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: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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