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Research Papers

AIMFAST: An Alignment Tool Based on Fringe Reflection Methods Applied To Dish Concentrators

[+] Author and Article Information
Charles E. Andraka, Julius Yellowhair, Kirill Trapeznikov, Jeff Carlson, Brian Myer, Brad Stone, Kirby Hunt

 Sandia National Laboratories, P.O. 5800 Albuquerque, NM 87185-1127, USAceandra@sandia.govDepartment of Physics & Astronomy, CAP 231,  Appalachian State University, 525 Rivers St, Boone NC 28608, USAceandra@sandia.gov Stirling Energy Systems, 4800 N Scottsdale Road, Suite 5500 Scottsdale, AZ 82521, USAceandra@sandia.gov

J. Sol. Energy Eng 133(3), 031018 (Jul 28, 2011) (6 pages) doi:10.1115/1.4004357 History: Received January 17, 2011; Revised May 31, 2011; Published July 28, 2011; Online July 28, 2011

The proper alignment of facets on a dish engine concentrated solar power system is critical to the performance of the system. These systems are generally highly concentrating to produce high temperatures for maximum thermal efficiency so there is little tolerance for poor optical alignment. Improper alignment can lead to poor performance and shortened life through excessively high flux on the receiver surfaces, imbalanced power on multicylinder engines, and intercept losses at the aperture. Alignment approaches used in the past are time consuming field operations, typically taking 4–6 h per dish with 40–80 facets on the dish. Production systems of faceted dishes will need rapid, accurate alignment implemented in a fraction of an hour. In this paper, we present an extension to our Sandia Optical Fringe Analysis Slope Technique mirror characterization system that will automatically acquire data, implement an alignment strategy, and provide real-time mirror angle corrections to actuators or labor beneath the dish. The Alignment Implementation for Manufacturing using Fringe Analysis Slope Technique (AIMFAST) has been implemented and tested at the prototype level. In this paper we present the approach used in AIMFAST to rapidly characterize the dish system and provide near-real-time adjustment updates for each facet. The implemented approach can provide adjustment updates every 5 s, suitable for manual or automated adjustment of facets on a dish assembly line.

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Copyright © 2011 by American Society of Mechanical Engineers
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Figures

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Figure 1

AIMFAST physical layout with camera and target at the 2-f location. The solid black lines indicate the field of view of the camera, the dashed red lines indicate a typical reflected ray from the LCD screen to the camera.

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Figure 2

Fringe reflection method physical layout

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Figure 3

Mask image of dish showing key physical locations including OQS and two fiducials at the engine mount location

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Figure 4

Mirror tilt errors as determined by AIMFAST. The solid blue vectors represent the magnitude and direction of the mirror tilt away from the alignment strategy, anchored to the inner mirror mount. The red vectors indicate the magnitude of the outer mirror mount adjustments needed to resolve the error. An upward adjustment indicates a longer stud is needed, downward is shorter.

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Figure 5

CIRCE2 prediction of flux on a flat plate near the receiver tube location, based on AIMFAST measured facet position and shape. The flat target is at 6.91 m from the dish vertex.

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Figure 6

Fluxmap of the dish on a flat target at 6.91 m forms the dish vertex, in the pre-alignment condition

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Figure 7

CIRCE2 prediction of flux profile after mirror facets are analytically rotated the AIMFAST-prescribed amount

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Figure 8

CIRCE2-predicted flux profile on receiver tubes based on AIMFAST measurement of facet normals and deviations

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Figure 9

CIRCE2-predicted flux profile on receiver tubes after virtual re-alignment of the measured normals

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