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Proceedings Paper

Shape control of solar collectors using torsional shape memory alloy actuators
Author(s): Don W. Lobitz; Tom M. Rice; James W. Grossman; James J. Allen; Chen Liang; Frank M. Davidson
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Paper Abstract

Solar collectors that are focused on a central receiver are designed with a mechanism for defocusing the collector or disabling it by turning it out of the path of the sun's rays. This is required to avoid damaging the receiver during periods of inoperability. In either of these two cases a fail-safe operation is very desirable where during power outages the collector passively goes to its defocused or deactivated state. This paper will be principally concerned with focusing and defocusing the collector in a fail-safe manner using shape memory alloy actuators. Shape memory alloys are well suited to this application in that once calibrated the actuators can be operated in an on/off mode using a small amount of electric power. Also, in contrast to other smart materials that were investigated for this application, shape memory alloys are capable of providing enough stroke at the appropriate force levels to focus the collector. In order to accommodate the large, nonlinear deformations required in the solar collector plate to obtain desired focal lengths, a torsional shape memory alloy actuator was developed that produces a stroke of 0.5 inches. Design and analysis details presented, along with comparisons to test data taken from an actual prototype, demonstrate that the collector can be repeatedly focused and defocused within accuracies required by typical solar energy systems.

Paper Details

Date Published: 1 May 1996
PDF: 10 pages
Proc. SPIE 2721, Smart Structures and Materials 1996: Industrial and Commercial Applications of Smart Structures Technologies, (1 May 1996); doi: 10.1117/12.239151
Show Author Affiliations
Don W. Lobitz, Sandia National Labs. (United States)
Tom M. Rice, Sandia National Labs. (United States)
James W. Grossman, Sandia National Labs. (United States)
James J. Allen, Sandia National Labs. (United States)
Chen Liang, San Diego State Univ. (United States)
Frank M. Davidson, San Diego State Univ. (United States)


Published in SPIE Proceedings Vol. 2721:
Smart Structures and Materials 1996: Industrial and Commercial Applications of Smart Structures Technologies
C. Robert Crowe, Editor(s)

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