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PCM-Graphite Composites for High Temperature Thermal Energy Storage

Bauer, Thomas und Tamme, Rainer und Christ, Martin und Öttinger, Oswin (2006) PCM-Graphite Composites for High Temperature Thermal Energy Storage. In: Tenth International Conference on Thermal Energy Storage. Ecostock 2006, 2006-05-31 - 2006-06-02, Pomona, NJ (USA).

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Offizielle URL: http://intraweb.stockton.edu/eyos/page.cfm?siteID=82&pageID=29

Kurzfassung

Latent thermal energy storage systems use the heat absorbed during melting and released during solidification of phase change materials (PCMs). From an energy efficiency point of view, PCM storage systems have the advantage that they operate with a small temperature difference between charging and discharging of the storage. Also, these storage systems have high energy densities compared to sensible heat storages assuming such energy efficient operation. PCMs considered for temperatures between 100 and 300°C are mainly anhydrous salts. Applications include industrial process heat utilisation and solar power generation using direct steam technology. However, there are heat transfer limitations on the storage design due to the low thermal conductivity of the salts. Major approaches to overcome this inadequate heat transfer are the enlargement of the heat exchanger surface or the use of composite latent heat storage materials (CLHSM). This work selects the latter, where the properties of the high latent heat of the PCM and the good thermal conductivity of graphite are combined. As a PCM, this work uses the equimolar composition of potassium nitrate (KNO3) and sodium nitrate (NaNO3) with a melting temperature of about 220°C. There is a variety of potential preparation routes for CLHSM and these processes have a decisive impact on the interconnectivity of the graphite. Generally a highly interconnected graphite matrix is desirable in order to achieve a high effective thermal conductivity. We present in this paper the preparation of CLHSM from graphite and the eutectic KNO3-NaNO3 by the compression and the infiltration route using natural graphite flakes, ground expanded graphite particles and compressed expanded graphite plates. This results in composites with a different level of interconnectivity of the graphite. The composites are characterized in terms of their effective thermal conductivity as a function of temperature using the laser-flash method. The impact of thermal cycling on the effective thermal conductivity, segregation, form stability and expansion of the CLHSM is also discussed. The CLHSM show a considerable enhancement of the thermal conductivity compared with those of the single PCM.

elib-URL des Eintrags:https://elib.dlr.de/46656/
Dokumentart:Konferenzbeitrag (Vortrag, Paper)
Titel:PCM-Graphite Composites for High Temperature Thermal Energy Storage
Autoren:
AutorenInstitution oder E-Mail-AdresseAutoren-ORCID-iDORCID Put Code
Bauer, ThomasNICHT SPEZIFIZIERTNICHT SPEZIFIZIERTNICHT SPEZIFIZIERT
Tamme, RainerNICHT SPEZIFIZIERTNICHT SPEZIFIZIERTNICHT SPEZIFIZIERT
Christ, MartinNICHT SPEZIFIZIERTNICHT SPEZIFIZIERTNICHT SPEZIFIZIERT
Öttinger, OswinNICHT SPEZIFIZIERTNICHT SPEZIFIZIERTNICHT SPEZIFIZIERT
Datum:31 Mai 2006
Erschienen in:Tenth International Conference on Thermal Energy Storage
Referierte Publikation:Ja
Open Access:Nein
Gold Open Access:Nein
In SCOPUS:Nein
In ISI Web of Science:Nein
Status:veröffentlicht
Stichwörter:storage, thermal, graphite, expanded, salt, nitrate, high temperature, phase change material, PCM, composite, direct steam, KNO3, NaNO3, effective thermal conductivity
Veranstaltungstitel:Ecostock 2006
Veranstaltungsort:Pomona, NJ (USA)
Veranstaltungsart:internationale Konferenz
Veranstaltungsdatum:2006-05-31 - 2006-06-02
Veranstalter :Richard Stockton College of New Jersey
HGF - Forschungsbereich:Energie
HGF - Programm:Erneuerbare Energie, Rationelle Energieumwandlung (alt)
HGF - Programmthema:E SF - Solarforschung (alt), E VG - Verbrennungs- und Gasturbinentechnik (alt)
DLR - Schwerpunkt:Energie
DLR - Forschungsgebiet:E SF - Solarforschung, E VG - Verbrennungs- und Gasturbinentechnik
DLR - Teilgebiet (Projekt, Vorhaben):E - Solare Hochtemperatursysteme (alt), E - Thermische Energiespeicher (alt), E - Wärmetauscher (alt)
Standort: Stuttgart
Institute & Einrichtungen:Institut für Technische Thermodynamik
Hinterlegt von: Bauer, Dr.phil. Thomas
Hinterlegt am:15 Mai 2007
Letzte Änderung:12 Dez 2013 20:22

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