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Slope Measurements of Parabolic Dish Concentrators Using Color Codified Targets

Ulmer, Steffen and Heller, Peter and Reinalter, Wolfgang (2008) Slope Measurements of Parabolic Dish Concentrators Using Color Codified Targets. Journal of Solar Energy Engineering, Volume (Issue ).

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Abstract

A new fast and highly accurate method for measuring the slope errors of parabolic dish concentrators has been developed. This method uses a flat target with colored stripes placed close to the focal plane of the concentrator and a digital camera located at an observation point on the optical axis at some distance from it. A specially developed image analysis algorithm detects the different colors of the images of the reflection of the target in the concentrator and assigns them their known position on the color target. This information, along with the geometry of the measurement setup and the theoretical parabolic shape of the concentrator, is used to calculate the normal vectors of the concentrator surface. From these normal vectors the radial and tangential slopes can be calculated and compared to the design values of the concentrator. The resulting slope errors not only give the total concentrator error for general characterization of the dish, but also indicate systematic errors from fabrication and installation with a high spatial resolution. In order to verify the quality of the results obtained, a ray-tracing code was developed that calculates the flux distribution on planes perpendicular to the optical axis. Measured slope errors of a 8.5m dish concentrator are presented and the calculated flux distributions are compared to measured flux distributions. The comparison shows excellent agreement in the flux distribution on the absorber plane. This verifies the promising potential of this fast and highly precise new method for measuring imperfections in dish concentrator shape.

Document Type:Article
Title:Slope Measurements of Parabolic Dish Concentrators Using Color Codified Targets
Authors:
AuthorsInstitution or Email of Authors
Ulmer, SteffenUNSPECIFIED
Heller, PeterUNSPECIFIED
Reinalter, WolfgangUNSPECIFIED
Date:February 2008
Journal or Publication Title:Journal of Solar Energy Engineering
Volume:Volume
Status:Published
Keywords:Parabolic Dish, Slope Error, Distant Observer, Color Target, Ray-tracing, Optical Measurement, Shape Measurement
HGF - Research field:Energy
HGF - Program:Renewable Energies
HGF - Program Themes:E SF - Solar research (old)
DLR - Research area:Energy
DLR - Program:E SF - Solar research
DLR - Research theme (Project):E - Qualifizierung (old)
Location: other
Institutes and Institutions:Institute of Technical Thermodynamics > Solar Research
Deposited By: Dr.-Ing. Steffen Ulmer
Deposited On:18 Feb 2008
Last Modified:12 Dec 2013 20:29

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