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Title: A replaceable reflective film for solar concentrators

Abstract

The 3M Company manufactures a silvered acrylic film called ECP-305 that is regarded as the preferred reflective film for use on stretched-membrane heliostats. However, ECP-305 will degrade in time, due to both corrosion of the silver layer and delamination at the film's silver-to-acrylic interface, and will eventually need to be replaced. 3M uses a very aggressive adhesive on this film, and once it is laminated, replacement is very difficult. The purpose of this investigation was the development of a replaceable reflector, a reflective film that can be easily removed and replaced. A replaceable reflector was successfully configured by laminating ECP-305 to the top surface of a smooth, dimensionally stable polymer film, with a removable adhesive applied to the underside of the polymer film. Several stages of screening and testing led to the selection of a 0.010-inch thick polycarbonate (GE 8030) as the best polymer film and a medium tack tape (3M Y-9425) was selected as the best removable adhesive. To demonstrate the feasibility of the replaceable reflector concept and to provide a real-time field test, the chosen construction was successfully applied to the 50-m{sup 2} SKI heliostat at the Central Receiver Test Facility at Sandia National Laboratories in Albuquerque. 4more » refs., 13 figs., 7 tabs.« less

Publication Date:
Research Org.:
Sandia National Labs., Albuquerque, NM (United States); Industrial Solar Technology, Denver, CO (United States)
Sponsoring Org.:
USDOE; USDOE, Washington, DC (United States)
OSTI Identifier:
5109102
Report Number(s):
SAND-91-7006
ON: DE92002936
DOE Contract Number:
AC04-76DP00789
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; FILMS; ADHESION; REMOVAL; REFLECTIVE COATINGS; FEASIBILITY STUDIES; ADHESIVES; DESIGN; HELIOSTATS; MEMBRANES; POLYACRYLATES; POLYCARBONATES; POLYESTERS; POLYETHYLENES; POLYSTYRENE; PVC; SILVER; SOLAR CONCENTRATORS; CARBON COMPOUNDS; CARBONATES; CHLORINATED ALIPHATIC HYDROCARBONS; COATINGS; ELEMENTS; EQUIPMENT; ESTERS; HALOGENATED ALIPHATIC HYDROCARBONS; MATERIALS; METALS; ORGANIC CHLORINE COMPOUNDS; ORGANIC COMPOUNDS; ORGANIC HALOGEN COMPOUNDS; ORGANIC POLYMERS; OXYGEN COMPOUNDS; PETROCHEMICALS; PETROLEUM PRODUCTS; PLASTICS; POLYMERS; POLYOLEFINS; POLYVINYLS; SOLAR EQUIPMENT; SYNTHETIC MATERIALS; TRANSITION ELEMENTS; 141000* - Solar Collectors & Concentrators; 360603 - Materials- Properties; 360601 - Other Materials- Preparation & Manufacture

Citation Formats

Not Available. A replaceable reflective film for solar concentrators. United States: N. p., 1991. Web. doi:10.2172/5109102.
Not Available. A replaceable reflective film for solar concentrators. United States. doi:10.2172/5109102.
Not Available. Sun . "A replaceable reflective film for solar concentrators". United States. doi:10.2172/5109102. https://www.osti.gov/servlets/purl/5109102.
@article{osti_5109102,
title = {A replaceable reflective film for solar concentrators},
author = {Not Available},
abstractNote = {The 3M Company manufactures a silvered acrylic film called ECP-305 that is regarded as the preferred reflective film for use on stretched-membrane heliostats. However, ECP-305 will degrade in time, due to both corrosion of the silver layer and delamination at the film's silver-to-acrylic interface, and will eventually need to be replaced. 3M uses a very aggressive adhesive on this film, and once it is laminated, replacement is very difficult. The purpose of this investigation was the development of a replaceable reflector, a reflective film that can be easily removed and replaced. A replaceable reflector was successfully configured by laminating ECP-305 to the top surface of a smooth, dimensionally stable polymer film, with a removable adhesive applied to the underside of the polymer film. Several stages of screening and testing led to the selection of a 0.010-inch thick polycarbonate (GE 8030) as the best polymer film and a medium tack tape (3M Y-9425) was selected as the best removable adhesive. To demonstrate the feasibility of the replaceable reflector concept and to provide a real-time field test, the chosen construction was successfully applied to the 50-m{sup 2} SKI heliostat at the Central Receiver Test Facility at Sandia National Laboratories in Albuquerque. 4 refs., 13 figs., 7 tabs.},
doi = {10.2172/5109102},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Sep 01 00:00:00 EDT 1991},
month = {Sun Sep 01 00:00:00 EDT 1991}
}

Technical Report:

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  • Materials for highly reflective surfaces for use in parabolic dish solar concentrators are discussed. Some important factors concerning performance of the mirrors are summarized, and typical costs are treated briefly. Capital investment cost/performance ratios for various materials are computed specifically for the double curvature parabolic concentrators using a mathematical model. The results are given in terms of initial investment cost for reflective surfaces per thermal kilowatt delivered to the receiver cavity for various operating temperatures from 400 to 1400 C. Although second surface glass mirrors are emphasized, first surface, chemically brightened and anodized aluminum surfaces as well as second surface,more » metallized polymeric films are treated. Conventional glass mirrors have the lowest cost/performance ratios, followed closely by aluminum reflectors. Ranges in the data due to uncertainties in cost and mirror reflectance factors are given.« less
  • A system for the vacuum deposition of atomic-oxygen durable coatings for reflective solar dynamic power systems (SDPS) concentrators was designed and demonstrated. The design issues pertinent to SDPS were developed by the Government Aerospace Systems Division of the Harris Corporation and are described in NASA-CR-179489. Both design and demonstration phases have been completed. At the time of this report the deposition system was ready for coating of facets for SDPS concentrators. The materials issue relevant to the coating work were not entirely resolved. These issues can only be resolved when substrates which are comparable to those which will be usedmore » in flight hardware are available. The substrates available during the contract period were deficient in the areas of surface roughness and contamination. These issues are discussed more thoroughly in the body of the report.« less
  • Materials for highly reflective surfaces for use in parabolic dish solar concentrators are discussed. Some important factors concerning performance of the mirrors are summarized, and typical costs are treated briefly. Although much of the data given are general and applicable to flat or curved solar reflectors, capital investment cost/performance ratios for various materials are computed specifically for the double curvature parabolic concentrators using a mathematical model. The results are given in terms of initial investment cost for reflective surfaces per thermal kilowatt delivered to the receiver cavity for various operating temperatures from 400 to 1400/sup 0/C. Although second-surface glass mirrorsmore » are emphasized, first-surface, chemically brightened and anodized aluminum surfaces as well as second-surface, metallized polymeric films are treated. Conventional glass mirrors have the lowest cost/performance ratios, followed closely by aluminum reflectors. Also, ranges in the data due to uncertainties in cost and mirror reflectance factors are given.« less
  • The objectives of this project were as follows: To develop and evaluate promising low-cost dielectric and polymer-protected thin-film reflective metal coatings to be applied to preformed continuously-curved solar reflector panels to enhance their solar reflectance, and to demonstrate protected solar reflective coatings on preformed solar concentrator panels. The opportunity for this project arose from a search by United Solar Technologies (UST) for organizations and facilities capable of applying reflective coatings to large preformed panels. PNL was identified as being uniquely qualified to participate in this collaborative project.
  • Candidates for reflector panel design concepts, including materials and configurations, were identified. The large list of candidates was screened and reduced to the five most promising ones. Cost and technical factors were used in making the final choices for the panel conceptual design, which was a stiffened steel skin substrate with a bonded, acrylic overcoated, aluminized polyester film reflective surface. Computer simulations were run for the concentrator optics using the selected panel design, and experimentally determined specularity and reflectivity values. Intercept factor curves and energy to the aperture curves were produced. These curves indicate that surface errors of 2 mradmore » (milliradians) or less would be required to capture the desired energy for a Brayton cycle 816 C case. Two test panels were fabricated to demonstrate manufacturability and optically tested for surface error. Surface errors in the range of 1.75 mrad and 2.2 mrad were measured.« less