Development of a stretched-membrane dish

Technical Report · Mon Jul 01 00:00:00 EDT 1991

DOI:https://doi.org/10.2172/5494221· OSTI ID:5494221

Solar Kinetics, Inc., successfully designed and constructed the optical element of a 7-meter diameter stretched-membrane dish as Task 2 of the second phase of a contract directed by Sandia National Laboratories. Earlier work on this project defined the configuration of the optical element and demonstrated the membrane-forming process on 1.4- and 3.7-meter diameter membranes. In Task 2, the membrane-forming process was successfully scaled to 7-meters in diameter, and an innovative hub-and-spoke structure optical element was fabricated. The slope error, as measured with Solar Kinetics' laser-ray-trace system, was within 3.6 mrad of a perfect parabola. Four major technical issues were successfully addressed in this work: (1) The technique of large-scale membrane forming was shown to be predictable, accurate, and repeatable. Three 7-meter membranes were formed without any contoured tooling. (2) A tensioned hub-and-spoke structure was demonstrated to be practical to fabricate. This innovative structure, like a bicycle wheel, was shown to be very stiff. Optical effects from ring distortion were not apparent. (3) The use of field-replaceable, unattached polymer reflective membrane was demonstrated. This approach allows for the practical field replacement of the reflective membrane when it has degraded due to weathering. (4) A technique was developed and demonstrated to ship the formed membranes from the factory to the dish-installation site. This allows the critical forming of the membrane to be performed in a controlled factory environment, and the membrane then to be shipped using standard-dimension shipping containers. This development further reduces manufacturing and installation costs of the completed dish. This effort indicates that the stretch-membrane dish concept is a promising approach for solar concentration. The prototype optical element is a significant step in the development of the complete, full-sized dish. 9 refs., 53 figs., 2 tabs.

• Research Organization: Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Solar Kinetics, Inc., Dallas, TX (United States)
• Sponsoring Organization: USDOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 5494221
• Report Number(s): SAND90-7036; ON: DE91016499
• Country of Publication: United States
• Language: English

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