Otto, Henning und Naumann, Clemens und Odenthal, Christian und Cierpka, Christian (2023) Unsteady Inherent Convective Mixing in Thermal-Energy-Storage Systems during Standby Periods. PRX Energy, 2 (4). American Physical Society. doi: 10.1103/PRXEnergy.2.043001. ISSN 2768-5608.
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Kurzfassung
Recent studies on the flow phenomena in stratified thermal-energy-storage (TES) systems have shown that heat conduction from the hot upper fluid layer through the vertical tank sidewall into the lower cold fluid layer leads to counterdirected wall jets adjacent to the vertical sidewalls. It was shown that these phenomena destroyed half of the total exergy content in less than a tenth of the storage time constant of a 2-m3 stratified TES system. This paper investigates short-term fluctuations of the wall jets since these fluctuations can potentially mix the hot and cold zones of the thermal stratification that are separated by the thermocline region. Using particle-image velocimetry measurements in two regions of a TES model experiment (near-wall region and far-field region) and analyzing the frequency content of the velocity fields revealed characteristic oscillations for different regions. In the near-wall region, observed fluctuations agreed well with an adjusted boundary layer frequency from the literature, showing that the wall jet is transitioning from laminar to turbulent flow. In the far-field region, the oscillations are related to the Brunt-Väisälä frequency. It is shown that the fluctuations from the boundaries of the thermocline region are most dominant and propagate into deeper regions of the thermocline. A comparison to data from the large-scale test facility for thermal energy storage in molten salt at the German Aerospace Center in Cologne showed good agreement. The consensus between the two experiments proves firstly that a small-scale model experiment with water as a storage liquid can be used to analyze the physical phenomena of large-scale molten salt storage facilities and secondly that these fluctuations are relevant for exergy destruction in real-scale TES.
elib-URL des Eintrags: | https://elib.dlr.de/198762/ | ||||||||||||||||||||
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Dokumentart: | Zeitschriftenbeitrag | ||||||||||||||||||||
Titel: | Unsteady Inherent Convective Mixing in Thermal-Energy-Storage Systems during Standby Periods | ||||||||||||||||||||
Autoren: |
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Datum: | 2 Oktober 2023 | ||||||||||||||||||||
Erschienen in: | PRX Energy | ||||||||||||||||||||
Referierte Publikation: | Nein | ||||||||||||||||||||
Open Access: | Ja | ||||||||||||||||||||
Gold Open Access: | Nein | ||||||||||||||||||||
In SCOPUS: | Nein | ||||||||||||||||||||
In ISI Web of Science: | Nein | ||||||||||||||||||||
Band: | 2 | ||||||||||||||||||||
DOI: | 10.1103/PRXEnergy.2.043001 | ||||||||||||||||||||
Verlag: | American Physical Society | ||||||||||||||||||||
ISSN: | 2768-5608 | ||||||||||||||||||||
Status: | veröffentlicht | ||||||||||||||||||||
Stichwörter: | TESIS, thermal energy storage, free convection | ||||||||||||||||||||
HGF - Forschungsbereich: | Energie | ||||||||||||||||||||
HGF - Programm: | Energiesystemdesign | ||||||||||||||||||||
HGF - Programmthema: | Digitalisierung und Systemtechnologie | ||||||||||||||||||||
DLR - Schwerpunkt: | Energie | ||||||||||||||||||||
DLR - Forschungsgebiet: | E SY - Energiesystemtechnologie und -analyse | ||||||||||||||||||||
DLR - Teilgebiet (Projekt, Vorhaben): | E - Energiesystemtechnologie | ||||||||||||||||||||
Standort: | Köln-Porz | ||||||||||||||||||||
Institute & Einrichtungen: | Institut für Technische Thermodynamik > Thermische Prozesstechnik | ||||||||||||||||||||
Hinterlegt von: | Odenthal, Dr. Christian | ||||||||||||||||||||
Hinterlegt am: | 19 Dez 2023 17:25 | ||||||||||||||||||||
Letzte Änderung: | 21 Dez 2023 09:37 |
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