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Conversion of parabolic trough mirror shape results measured in different laboratory setups

Meiser, Siw and Lüpfert, Eckhard and Schiricke, Björn and Pitz-Paal, Robert (2015) Conversion of parabolic trough mirror shape results measured in different laboratory setups. Solar Energy, 111, pp. 396-406. Elsevier. DOI: DOI: 10.1016/j.solener.2014.09.021 ISSN 0038-092X

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Official URL: http://www.sciencedirect.com/science/article/pii/S0038092X14004514

Abstract

Shape accuracy of mirror panels for parabolic trough solar collectors has a significant impact on the optical performance of the collectors in a solar power plant and is therefore carefully assessed by test laboratories and manufacturers. Relevant deformation is induced by gravity or mounting forces, so that shape accuracy data measured in different setups cannot be compared. This paper presents a method for conversion of shape measured in a vertical laboratory setup into data for a horizontal laboratory setup. Characteristic deformation matrices for parabolic trough mirror panels of RP3 geometry are determined by deflectometric shape measurements on various mirror panels and by validated finite element analyses (FEA). The resulting root mean square (rms) of measured slope deviation difference (i.e. the gravity induced deformation) between vertical and horizontal setup is on average 2.4 mrad for inner mirrors and 1.25 mrad for outer mirrors loosely positioned on a frame. Measured data from vertical setup, transformed by such characteristic deformation matrices into horizontal shape results, differ by less than 0.2 mrad in rms slope deviation value from data measured in horizontal setup. Whereas the presented approach to convert shape accuracy measurement results is suitable for the calculation of rms values, some of the analyzed mirror samples show differences in local slope deviation values larger than the deflectometric measurement uncertainty. The amount of deviation depends on details of the accuracy of the positioning of the mirrors on the measurement frame and is affected by the fixation and associated mounting forces at the pads.

Item URL in elib:https://elib.dlr.de/91771/
Document Type:Article
Title:Conversion of parabolic trough mirror shape results measured in different laboratory setups
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Meiser, SiwSiw.Meiser (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:Solar Energy
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:111
DOI :DOI: 10.1016/j.solener.2014.09.021
Page Range:pp. 396-406
Publisher:Elsevier
Series Name:El Sevier
ISSN:0038-092X
Status:Published
Keywords:Parabolic trough; Mirror shape; Deflectometry; Finite element analysis
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:11 Nov 2014 13:35
Last Modified:31 Jul 2019 19:49

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