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INVENTION
Russian Federation Patent RU2043582

Reflective element and its manufacturing method

Reflective element and its manufacturing method

Name of the inventor: Wolves ESTHER POLLARD .; Polivoda AI
The name of the patentee: State Research Institute of Energy Krzhizhanovsky
Address for correspondence:
Starting date of the patent: 1992.09.10

Use: in solar engineering, light engineering. The inventive reflective element is part parabollicheskoy surface having a reflecting surface formed into a thin curved sheet 1 coated with the layers 2, 3 of silver, copper or aluminum, respectively, and the adjacent fiber-reinforced layer 4, the foam structure.

DESCRIPTION OF THE INVENTION

The invention relates to reflective elements and methods of their manufacture can be used in solar energy, and in lighting technology, spectrophotometry, photonics and other fields.

Known reflective device constituting part of the surface parabolotsilindra from a thin metal sheet of high purity with stiffeners on the shady side, with the focus of the reflector is tubular absorber, and the reflector has a rigid surface frame fixed to two circular rims mounted on rollers, with driven by sun tracking system [1] The total reflectance of such mirrors reaches 0.75 to 0.5 but is reduced to six months due to atmospheric contamination.

Known lightweight aggregate concave mirror with a reflection coefficient 0.8, which in order to ensure the necessary rigidity and stability of the optical characteristics, especially the concentration ratio of solar energy is used as a sandwich structure with the axes of the honeycomb cells transverse surfaces made of thin sheets of organic material reinforced with carbon fibers, wherein the concave surface is adhered a thin glass sheet, which is applied by evaporation reflective coating to form a layer of aluminum, and over it a thin protective coating layer [2] The theoretical concentration factor of such mirrors depending on the aperture ratio and the focus a / F in the range of 100-200. Known silver reflective coatings are applied to evaporating it possible to obtain the solar energy reflectance to 0.95, which is 10-12% higher than an aluminum cover, are not widely used due to considerable consumption of silver and 10 g / m 2 and high cost.

Known reflective element, which is part of a parabolic surface strictly having a curved reflecting surface and the adjacent layer monolithic anisotropic foam structure consisting of sub-layers with a predetermined thickness by changing the density and strength [3]

Despite the high initial reflectance (0.8-0.9) surface-deposited mirror coatings, their disadvantage is gradually progressive destruction due microlayers corrosive chemical action of atmospheric pollution in combination with photochemical reactions, initiated by the sun's UV radiation. In just a few years of operation, the reflectance of the mirrors may be reduced to 0.4 or lower.

This drawback is partially deprived malirovannye glass mirrors, but they lack other peculiar roughness and waviness occurring at malirovanii that reduce optical-geometric characteristics including a concentration factor 100-200 to 70-40. In the thicker glass portion useless absorbed solar energy.

A significant disadvantage of the known proposals is the low impact mechanical strength of surface reflections due to inefficient distribution of the strength and density of the layers of material, lack of solidity and adhesion between the sandwich element facets. High impact resistance mirrored facets required for gradoustoychivosti and thus the reliability of the solar-power plants.

The disadvantage of the known methods for manufacturing parabolotsilindricheskih facet mirror is a low productivity of the process window malirovaniya, the complexity of the complexity of the production technology, but also a considerable flow of silver and 10 g per 1 m 2 of mirror facets.

The object of the invention to create such a reflective element and its manufacturing method, which would provide substantial improvement optikometricheskih characteristics for a long time, coupled with the mechanical strength.

This problem is solved in the reflecting element is a portion of a parabolic surface, comprising a rigid reflective surface and the adjacent layer of cast-in-anisotropic foam structure, consisting of sub-layers with a given change in the thickness of density and strength. According to the invention the reflecting surface is formed as a parabola curved transparent sheet on the back surface of which there are cast-adhesively associated with the bimetallic sheet layer composed of sublayer and sublayer silver copper or aluminum, and a layer of foam structure made of fiber-reinforced.

In a preferred embodiment, the thickness of the transparent glass sheet of 1 / 50-1 / 2000 the length of the parabola focus. the sheet material must be resilient enough and tough at the same time to ensure the retention of a predetermined shape of a parabola in the process of applying liquid deposited components. The borosilicate glass, transparent organic polymer film, polyethylene terephthalate (polyester) may be used as the sheet material, methacrylate, polystyrene, polyamide, urea, polyurethane.

The radius of curvature is chosen on the basis of the mechanical properties of the material. For example, glass with smaller radii without malirovaniya may break.

The thickness of the silver underlayer preferably 0.03-0.05 microns. In comparison with conventional coatings of the silver layer thickness is reduced in 10-100 times.

Similarly decreases and the copper layer. The thickness is 1-5 microns.

The invention consists in that first a thin transparent sheet of reflective surfaces successively applied chemically pure sublayer silver and sublayer of copper or aluminum, and then bending the reflective surface on it by the bimetal layer sequentially applied to the first dense sublayer unfoamed polyurethane composite foamed cellular second sublayer anisotropic foam and third outer sublayer.

Reflective element and its manufacturing method Reflective element and its manufacturing method

FIG. 1 shows the proposed reflective element; FIG. 2 the structure of bimetallic layer on a transparent sheet with a dense zone section on a larger scale; FIG. 3 is a graph of density distribution and strength across the thickness of the reflecting element.

The reflective member is a curved parabola transparent sheet 1, on the rear side of which is integrally adhesively bonded thereto bimetallic layer consisting of sublayers metallic silver 2 and the underlayer copper or aluminum 3, and the sheet 1 with bimetallic layer 2, 3 is part of fiber-reinforced dense zone 4 integral anisotropic foam structure 5, 6 with a predetermined change in density and strength. On the back side surface 6 of fastening elements 7 are arranged.

As an example, a reflecting unit may be formed as a parabolic surface with a total thickness Comprising thin rigid curved generatrix parabola on the transparent sheet 1, for example, glass, with an optical purity of surfaces with equal thickness focal length of the mirror with the focal parabolotsilindricheskogo band F, while on the back side of the sheet 1 is adhesively monolithic associated bimetallic layer consisting of metallic silver sublayers, and 0.02-0.03 mm thick copper underlayer 3 or thick aluminum 1- 5 microns, and the sheet 1 itself with bimetallic sublayers 2, 3 is part of a fiber-reinforced dense zone 4 integral anisotropic foam structure 5, 6 with the thickness given law of variation of the density and strength for example, the graph of FIG. 3. In Zone 6 at the back side of the element density the foam structure is increased to 1.5 kg / dm 3 with increasing strength to 3 MPa. In zone 5 cell diameter of 0.3-1.5 mm (Fig. 2).

EXAMPLE Example. Made reflective element 100 cm wide, 302 cm length of the chord, the axially symmetric half of the aperture A 600 cm parabolic module with focus F to 200 cm, with the permissible geometrical deviations of ± 3 '.

On a thin sheet 1 made of borosilicate glass density of 2.55-2.70 kg / dm 3, the size 100h302 cm, 1 mm thick, with a pass rate of at least 0.94, with an optical purity of surfaces with a vacuum or chemically precipitated chemically opaque underlayer 2 pure silver thick 0.02-0.03 microns at a rate of 0.3-0.5 mg / cm 2. Then, vacuum or chemically deposited underlayer 3 chemically pure copper or aluminum of a thickness of 1-5 microns. Next, create a spatial convex parabolotsil- indricheskoe field sizes up to 240 cm with a tolerance with an adjustable extension three rows vertically fixed supports four in a row with a pitch between 30 cm and then accurately put them in parabolic patterns with a tolerance of 0.05 mm from the rated parabola. On convex bimetallic sublayers field poles 2, 3 are laid out one sheet which is bent by its own weight on parabolotsilindricheskoy convex surface, the sheet width at 5.4 cm is suspended from poles, and length 25-35 cm. From the sides may It is constructed box-like casing.

On the sheet 1 is sprayed polyurethane layer 4 unfoamed composite 1.2 mm thick, density 1.0-0.8 kg / dm 3, the polyurethane layer 3 is applied with fiberglass reinforced with a density of 1.5-1.8 kg / dm 3. Then applied (sprayed or poured) intermediate cellular layer of polyurethane foam with a density = 0,5-0,08 kg / dm3 the cells with a diameter of 0.3-1.5 mm and a thickness of 20-70 mm. Applied to the outer zone 6 anisotropic reflective element with a density of 1-1.2 kg / dm3 possibly reinforced with fiberglass. Instead of the supports is possible to use a convex parabolotsilindricheskoy matrix.

The action of the reflecting element, for example, focus F at 200 cm and 600 cm aperture A is as follows. When installing parabolotsilindricheskogo element perpendicular to the solar beam E last is concentrated in the band F focal width of 1.86 cm in the theoretical absorption coefficient A m 0.05-0.07. Glass with a density of 1 2.6 kg / cm 3 and strength 4 MPa protects the reflective silver thick underlayer 2 0.02-0.03 microns from external damage and sublayer 3 (copper or aluminum) makes it possible, without reducing the silver with 0.95 coefficient of reflection, to ensure a minimum flow in the manufacture of its order of 0.3 g / m 2, and and ensures its protection against oxidation and mechanical connection with an area density of 4 1.8 kg / dm 3 and a strength about 3 MPa.

The proposed reflecting element ensures consistency of focus, significantly higher compared with mirrored glass malirovannymi.

If shock loads, such as the impact of hailstones weighing up to 0.3 kg at a speed of about 60-70 m / s the latter is destroyed into small pieces on the surface 1 without leaving a trace and without damaging reflecting bimetallic sublayers 2 and 3. Under these conditions, the known glass elements broken into pieces.

The proposed reflecting member may be made in the embodiments parabolotsilindricheskih convex and parabolodalnovraschatelnyh and surfaces.

The proposed element has a whole series of advantages. In particular, increases the reflection coefficient to 0.9, improves concentration ratio, reduced the loss in thickness of the walls, increases the mechanical strength of the shock, reduced consumption of silver, and a method of manufacturing dropped malirovaniya process, reducing the complexity and improving productivity for mass production items.

CLAIM

1. The reflective element as part of a parabolic surface strictly having a curved reflecting surface and the adjacent layer monolithic anisotropic foam structure consisting of sub-layers with a given change in thickness density and strength, characterized in that the reflecting surface is a parabolic curved transparent sheet on the back side of which is monolithic adhesive-bonded bimetallic layer consisting of silver and sublayer sublayer of copper or aluminum, and a layer of foam structure made of fiber-reinforced.

2. An element according to Claim. 1, characterized in that the transparent sheet is made of glass and has a thickness of 1/50 to 1/2000 focal length of the parabola.

3. An element according to claim 1, characterized in that the silver sublayer has a thickness of 0.03 0.05 microns.

4. An element according to claim 1, characterized in that the underlayer copper or aluminum has a thickness of 1 5 micrometers.

5. A method of manufacturing a reflecting member by bending a parabolic reflective surface and applying it sublayers foam structure, characterized in that first on a thin transparent sheet is applied sequentially reflecting surface sublayer chemically pure silver and copper or aluminum sublayer and a reflective surface after bending it with hand bimetallic layer sequentially applied to the first sub-layer dense non-foamed polyurethane composite foam cellular second sub-layer and an anisotropic third outer sublayer.

6. A method according to claim 5, characterized in that the underlayer coating of silver produced by chemical vapor deposition.

7. The method of claim. 5, characterized in that the deposition of the underlayer copper or aluminum produced by the vacuum.

8. The method of claim. 5, characterized in that the deposition of the underlayer copper or aluminum produced by chemical vapor deposition.

9. The method of claim 5, wherein the first sublayer is performed polyurethane composite thickness of 1 to 2 mm with a density of 1.0 0.8 kg / dm 3.

10. The method according to claim 9, characterized in that said first fiberglass reinforced underlayer thicker in the liquid reaction components in the process of curing or afterwards.

11. The method according to claim 5, characterized in that the first underlayer made of several layers of reinforced glass fiber having a density of 1.5 and 1.8 kg / dm 3 and gradually decreasing in a direction away from the reflective surface.

12. The method according to claim 5, characterized in that said second cellular underlayer formed by spraying and pouring liquid polyurethane reaction components operate upon curing and the thickness of 20 to 70 mm, a density of 0.05 to 0.08 kg / dm 3 with a diameter of 0.3 cells 1.5 mm.

13. The method of claim. 5, characterized in that the external sublayer 1 operate density 1.2 kg / dm3.

14. The method according to claim 5, characterized in that the outer glass fiber reinforced underlayer and operate a thickness of 1 to 8 mm, a density of 0.8 to 3 kg / dm 3.

print version
Publication date 12.01.2007gg