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Stratified Flow Phenomena in Parabolic Trough Systems

Hirsch, Tobias and Ebert, Miriam and Eck, Markus and Eickhoff, Martin and Janotte, Nicole and Keller, Lothar and Meyen, Stephanie and Meyer-Grünefeld, Mirko and Munini, Michael and Nanz, Lisa and Prahl, Christoph and Röger, Marc and Wittmann, Michael (2012) Stratified Flow Phenomena in Parabolic Trough Systems. In: Proceedings. SolarPACES 2012, 11.-14. Sept. 2012, Marrakesch, Marokko.

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Abstract

Parabolic trough power plants today represent the state of the art in solar thermal electricity generation. A large number of plants have been realized in Spain based on the same principle as the first systems in the U.S. back in the 1980s. The market today is characterized by a strong need for cost reduction as competing technologies like PV showed remarkable improvements in terms of economics. For solar thermal power plants, several paths to higher profitability are open. Line focusing systems with either direct steam generation (DSG) or molten salt as a heat transfer fluid aim at higher process temperatures and thus better cycle efficiency. The same motivation holds for the activities in solar tower plants. Along with these “big” technological innovations it is important to optimize the performance of each single component. Detailed knowledge of physical effects is essential to identify potential for improvement. This paper focuses on the topic of flow stratification in horizontal tubes. Since the diameter to length ratio of absorber tubes in parabolic trough or Linear Fresnel systems is very small, a common assumption is that the temperature and flow are equally distributed over the cross section. In many cases, this assumption is appropriate to simplify calculation procedures. Nevertheless, there are applications for which this assumption is not valid any more. The paper will describe two such examples observed at DLRs test facilities. The first one deals with accurate measurement of the temperature rise within a collector efficiency test bench. It is shown how temperature stratification in the absorber tubes could lead to severe errors in the temperature measurement. The second example is a collector test facility for direct steam generation. During the start-up procedure we observed a damage of two absorber tube glass covers which was caused by large temperature gradients over the pipe cross section.

Item URL in elib:https://elib.dlr.de/79064/
Document Type:Conference or Workshop Item (Speech, Paper)
Title:Stratified Flow Phenomena in Parabolic Trough Systems
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Hirsch, TobiasDLR Institut für SolarforschungUNSPECIFIED
Ebert, MiriamDLR Institut für SolarforschungUNSPECIFIED
Eck, MarkusDLR Institut für Technische ThermodynamikUNSPECIFIED
Eickhoff, MartinDLR Institut für SolarforschungUNSPECIFIED
Janotte, NicoleDLR Institut für SolarforschungUNSPECIFIED
Keller, LotharDLR Institut für SolarforschungUNSPECIFIED
Meyen, StephanieDLR Institut für SolarforschungUNSPECIFIED
Meyer-Grünefeld, MirkoDLR Institut für SolarforschungUNSPECIFIED
Munini, MichaelDLR Institut für SolarforschungUNSPECIFIED
Nanz, LisaDLR Institut für SolarforschungUNSPECIFIED
Prahl, ChristophDLR Institut für SolarforschungUNSPECIFIED
Röger, MarcDLR Institut für SolarforschungUNSPECIFIED
Wittmann, MichaelDLR Institut für SolarforschungUNSPECIFIED
Date:September 2012
Journal or Publication Title:Proceedings
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:Solar Kraftwerk Simulation Strömung Schichtung Infrarot Kontas Real DISS Direktverdampfung
Event Title:SolarPACES 2012
Event Location:Marrakesch, Marokko
Event Type:international Conference
Event Dates:11.-14. Sept. 2012
HGF - Research field:Energy
HGF - Program:Renewable Energies
HGF - Program Themes:Concentrating Solar Systems (old)
DLR - Research area:Energy
DLR - Program:E SF - Solar research
DLR - Research theme (Project):E - Qualifizierung (old), E - Linienfokussierende Systeme (old)
Location: other , Stuttgart
Institutes and Institutions:Institute of Solar Research > Linienfokussierende Systeme
Deposited By: Hirsch, Dr.-Ing. Tobias
Deposited On:06 Dec 2012 15:06
Last Modified:12 Dec 2013 21:52

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