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Screening and analysis of potential filler materials for molten salt thermocline storages

Martin, Claudia and Breidenbach, Nils and Eck, Markus (2014) Screening and analysis of potential filler materials for molten salt thermocline storages. In: Proceedings of the 8th International Conference on Energy Sustainability. Web Portal ASME (American Society of Mechanical Engineers). 8th International Conference on Energy Sustainability, 30.Juni-02.July.2014, Boston, MA, USA. DOI: 10.1115/ES2014-6493 ISBN 978 079184586 8

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Official URL: http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleid=1920612&resultClick=3


Solar thermal power plants are a promising option for future solar electricity generation. Their main advantage is the possibility to utilize integrated thermal storage capacities, allowing electricity generation on demand. In state of the art solar thermal power plants, two-tank molten-salt thermal energy storages are used. Significant cost reductions are expected by using thermocline thermal energy storage by storing the liquid storage material inside a single tank when compared to a two tank storage system. By embedding a low cost solid filler material inside the storage tank further cost reductions can be achieved. In an earlier study [1, 2] several potential filler materials have been investigated. In this study quartzite turned out to be a promising candidate due to its satisfying thermal stability and availability. At a temperature of approx. 573°C the crystal structure of quartzite changes from trigonal α-quartz phase to the hexagonal β-quartz phase [3]. This quartz conversion results in a volume change [4] that may cause cracking of the quartzite crystals due to weight loads in a fill. Since these thermal tests of the study mentioned were limited to 500°C this dunting was not considered. One trend in today’s development of solar thermal power plants is to use molten salt as storage material and heat transfer fluid at operating temperatures of 560°C and above. Accordingly, the quartz inversion might limit the applicability of quartzite as a filler material at elevated operating temperatures. Due to this concern, an investigation has been started to investigate the utilizability of natural rocks as low cost filler materials. In the first phase of this investigation a comprehensive literature survey was conducted. Based on this study, magmatic and sedimentary rocks turned out to the most promising rock classes for this application. For the further investigation, basalt was chosen as a suited representative for magmatic and quartzite for sedimentary rocks. In lab-scale tests, these candidate materials were investigated with respect to their: • Calcite content • Thermal stability up to 900°C in air • Thermal stability up to 560°C in molten salt • Cyclic stability between 290°C and 560°C in molten salt • Specific heat capacity up to 600°C In this paper the results of these investigations are presented and future activities are outlined.

Item URL in elib:https://elib.dlr.de/89875/
Document Type:Conference or Workshop Item (Speech)
Title:Screening and analysis of potential filler materials for molten salt thermocline storages
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Martin, Claudiaclaudia.martin (at) dlr.deUNSPECIFIED
Breidenbach, Nilsnils.breidenbach (at) dlr.deUNSPECIFIED
Eck, Markusmarkus.eck (at) dlr.deUNSPECIFIED
Journal or Publication Title:Proceedings of the 8th International Conference on Energy Sustainability
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:No
DOI :10.1115/ES2014-6493
Publisher:Web Portal ASME (American Society of Mechanical Engineers)
ISBN:978 079184586 8
Keywords:thermocline molten salt storage, filler material, natural stones
Event Title:8th International Conference on Energy Sustainability
Event Location:Boston, MA, USA
Event Type:international Conference
Event Dates:30.Juni-02.July.2014
HGF - Research field:Energy
HGF - Program:Efficient Energy Conversion and Use (old)
HGF - Program Themes:Energy-efficient Processes (old)
DLR - Research area:Energy
DLR - Program:E EV - Energy process technology
DLR - Research theme (Project):E - Thermochemical Processes (old)
Location: Stuttgart
Institutes and Institutions:Institute of Engineering Thermodynamics > Thermal Process Technology
Deposited By: Martin, Claudia
Deposited On:22 Dec 2017 10:13
Last Modified:22 Dec 2017 10:13

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