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Evaluation and assessment of gravity load on mirror shape of parabolic trough solar collectors

Meiser, Siw and Schneider, Simon and Lüpfert, Eckhard and Schiricke, Björn and Pitz-Paal, Robert (2015) Evaluation and assessment of gravity load on mirror shape of parabolic trough solar collectors. Energy Procedia. Elsevier. ISSN 1876-6102.

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Official URL: http://www.elsevier.com/locate/procedia

Abstract

In order to achieve high optical collector and therefore high solar field efficiencies parabolic trough concentrators in concentrating solar power plants need to maintain their parabolic shape during operation. Additional to shape deviation already induced by the manufacturing process, deformation due to gravity load is an inevitable factor influencing shape accuracy in all types of parabolic trough collectors. This paper characterizes and quantifies the effect of gravity load on mirror shape and resulting slope and focus deviation values. One inner and one outer ideally parabolic shaped mirror of RP3 geometry mounted onto different support structures are evaluated in finite element analyses for all collector angles relevant for operation. The different support structures include two idealized support structures (ideal and elastic case) and one structure including relevant parts of EuroTrough type collectors (cantilever case). Constructional design and stiffness of the support structure significantly determine characteristic and magnitude of deformation. If compared to non-deformed shape, resulting rms values are as high as SDx = 1.7 mrad and FDx = 6.3 mm (inner mirror, elastic case) and SDx = 1.1 mrad and FDx = 5.6 mm (outer mirror, cantilever case). Depending on the type of support structure, minimum and maximum values occur at different collector angles. If compared to 0° (zenith) collector angle, resulting rms slope and focus deviation values are on average smaller than if compared to non-deformed mirror shape. This implies optimizing mirror shape for 0° (zenith) collector angle. However, it has to be considered that support structures for shape accuracy assessment in laboratory as well as support structures used in collector might differ significantly in design and stiffness, thus making it difficult to find one optimum shape for all types of mirror and collector.

Item URL in elib:https://elib.dlr.de/98972/
Document Type:Article
Title:Evaluation and assessment of gravity load on mirror shape of parabolic trough solar collectors
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Meiser, SiwSiw.Meiser (at) dlr.deUNSPECIFIED
Schneider, Simonsimon.schneider (at) dlr.deUNSPECIFIED
Lüpfert, EckhardEckhard.Luepfert (at) dlr.deUNSPECIFIED
Schiricke, Björnbjoern.schiricke (at) dlr.deUNSPECIFIED
Pitz-Paal, Robertrobert.pitz-paal (at) dlr.deUNSPECIFIED
Date:2015
Journal or Publication Title:Energy Procedia
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:No
Publisher:Elsevier
ISSN:1876-6102
Status:Published
Keywords:parabolic trough; mirror shape; shape accuracy; deformation; finite element modeling;
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 - Qualification (old)
Location: Köln-Porz
Institutes and Institutions:Institute of Solar Research > Qualifizierung
Deposited By: Kruschinski, Anja
Deposited On:04 Nov 2015 14:31
Last Modified:06 Sep 2019 15:22

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