Pelz, Peter F. ; Lemmer, Jan ; Schmitz, Christian B. (2024)
Misled by Betz and unsteady flow – review on turbine arrays falsely deemed ‘optimal’.
In: International Marine Energy Journal, 2022, 5 (3)
doi: 10.26083/tuprints-00026558
Artikel, Zweitveröffentlichung, Verlagsversion
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Kurzbeschreibung (Abstract)
A turbine array is an adjustable flow resistance R placed in a tidal channel. Ideally, it is designed and operated to maximise energy yield. Garrett & Cummins (2005), using optimal control theory applied to the RCelement channel (R) and basin (C), showed: the energy extraction from the flow P_T + P_D is maximised when the flow rate is slowed down by a factor of 1/√3. This result is independent of the ratio of the extracted mechanical power P_T to the total power extraction including the power loss P_D due to the mixing of the bypass flows within the turbine field. The optimisation task for turbine arrays is maximising P_T. This objective raises two questions: ”What is the maximum power P_T that can be extracted, and what is the optimal design (size, topology) and operation to achieve this output?” When addressing them, the literature still uses the Betz ‘limit’ as a reference. The work presented highlights two major problems. First, the Betz ’limit’ is not a constant upper bound for open channel flow. This problem has been discussed and solved by the first author (2011, 2020). Second and more importantly, the presented paper points out the misconception under which several research studies referred to array topologies as ‘optimal’ with regard to design and operation. Hereby, the presented paper contributes to the advancement of tidal power on an axiomatic basis. The misleading by Betz and overvaluing of transient effects is made transparent in a scientific discourse.
| Typ des Eintrags: | Artikel |
|---|---|
| Erschienen: | 2024 |
| Autor(en): | Pelz, Peter F. ; Lemmer, Jan ; Schmitz, Christian B. |
| Art des Eintrags: | Zweitveröffentlichung |
| Titel: | Misled by Betz and unsteady flow – review on turbine arrays falsely deemed ‘optimal’ |
| Sprache: | Englisch |
| Publikationsjahr: | 26 September 2024 |
| Ort: | Darmstadt |
| Publikationsdatum der Erstveröffentlichung: | 2022 |
| Ort der Erstveröffentlichung: | Southampton |
| Verlag: | European Wave and Tidal Energy Conference |
| Titel der Zeitschrift, Zeitung oder Schriftenreihe: | International Marine Energy Journal |
| Jahrgang/Volume einer Zeitschrift: | 5 |
| (Heft-)Nummer: | 3 |
| Kollation: | 9 Seiten |
| DOI: | 10.26083/tuprints-00026558 |
| URL / URN: | https://tuprints.ulb.tu-darmstadt.de/26558 |
| Zugehörige Links: | |
| Herkunft: | Zweitveröffentlichungsservice |
| Kurzbeschreibung (Abstract): | A turbine array is an adjustable flow resistance R placed in a tidal channel. Ideally, it is designed and operated to maximise energy yield. Garrett & Cummins (2005), using optimal control theory applied to the RCelement channel (R) and basin (C), showed: the energy extraction from the flow P_T + P_D is maximised when the flow rate is slowed down by a factor of 1/√3. This result is independent of the ratio of the extracted mechanical power P_T to the total power extraction including the power loss P_D due to the mixing of the bypass flows within the turbine field. The optimisation task for turbine arrays is maximising P_T. This objective raises two questions: ”What is the maximum power P_T that can be extracted, and what is the optimal design (size, topology) and operation to achieve this output?” When addressing them, the literature still uses the Betz ‘limit’ as a reference. The work presented highlights two major problems. First, the Betz ’limit’ is not a constant upper bound for open channel flow. This problem has been discussed and solved by the first author (2011, 2020). Second and more importantly, the presented paper points out the misconception under which several research studies referred to array topologies as ‘optimal’ with regard to design and operation. Hereby, the presented paper contributes to the advancement of tidal power on an axiomatic basis. The misleading by Betz and overvaluing of transient effects is made transparent in a scientific discourse. |
| Freie Schlagworte: | Betz limit, blockage, coefficient of performance, optimisation, quasi-steady flow, tidal array, tidal fence, turbine array |
| Status: | Verlagsversion |
| URN: | urn:nbn:de:tuda-tuprints-265584 |
| Zusätzliche Informationen: | Section EWTEC 2021 Special issue papers (Part 3) |
| Sachgruppe der Dewey Dezimalklassifikatin (DDC): | 600 Technik, Medizin, angewandte Wissenschaften > 620 Ingenieurwissenschaften und Maschinenbau |
| Fachbereich(e)/-gebiet(e): | 16 Fachbereich Maschinenbau 16 Fachbereich Maschinenbau > Institut für Fluidsystemtechnik (FST) (seit 01.10.2006) |
| Hinterlegungsdatum: | 26 Sep 2024 12:47 |
| Letzte Änderung: | 01 Okt 2024 13:40 |
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| Suche nach Titel in: | TUfind oder in Google |
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