BG65247B1 - Optical concentration system - Google Patents

Abstract

The optical concentration system is intended to concentrate parallel light beams in several ways. It can be folded in a passive position and unfolded in an operating position. The system is built up of a number of identical or similar elements consisting of reflection surfaces shaped as a concentration parabola (1) and a functional curve executed as a collimation parabola (2) or concentration hyperbola (3). To the functional curve (2, 3), an additional dissipation area (4, 5) is provided having a form that allows the system to be folded in a collected form. A closed space (6) can be shaped between the area (4, 5), the concentration curve (1) and the functional curve (2, 3), which can be used for forced cooling.

Description

Technical field

The invention relates to a modular optical concentrating system designed to concentrate in several ways parallel light rays and to be used in solar power plants and other optical systems.

BACKGROUND OF THE INVENTION

When it comes to large optical concentrating systems, the following basic systems are used:

A stationary, very precisely made hub-shaped hub composed of parts with a spherical or parabolic reflecting surface that provides accurate focusing. Multiple heliostats (flat or slightly concave mirror surfaces) that cover a large area direct the rays that fall on them to this dish. The disadvantages of this system are the need for complex management of the whole system, the large unusable area, the mutual overlapping of heliostats, as well as the difficult protection against adverse conditions due to the nature and size of the structure.

Another solution is a large dish in the focus of which is placed a receiver that converts the concentrated light into useful energy. The problems here are mainly the mass of the receiver that has to move along with the dish, the closure of the concentrator by the receiver in question, the need for moving pipelines that carry the heat carrier. Of course, there is the difficulty of preventing inclement weather.

Attempts have been made to overcome the need for movable pipelines, with the receiver fixed, and a large system of very precisely designed and directed heliostats reflecting the light incident on them. The problems here are again in complex management, the large unusable area, the mutual overlap, and the very difficult protection against adverse conditions.

US 4,293,192 [Allen Bronstein] is known for the folding and portable construction of an optical hub. A flexible sheet of material with a high reflectance is fixed to two elements of the same parabolic shape, located exactly opposite each other. The elements are spaced apart as the sheet stretches and adopts its shape. The convenience of this technology is only in the initial installation, after which problems arise as with the aforementioned large optical concentrating systems.

RU 2 000 524 describes a large optical concentrating system of identical sets of lenses and prisms, at an angle to the optical axis that concentrates the incoming parallel beams. The disadvantage of this system is that the deflected rays are not parallel to each other, which can hardly provide the required concentration for large optical concentrating systems.

US 5,054,466 uses a paraboloid surface that concentrates the incoming parallel rays beyond the boundaries of the paraboloid itself (offset reflector). This avoids shading from the receiver. The concentrating paraboloid surface is made of elements whose reflecting surfaces are different parts of the paraboloid. This example shows how difficult it is to design a large optical concentrating system from a single monolithic paraboloid surface.

US 4,439,020 describes an optical concentrating system of cylindrical parabolic reflectors and collimating lenses with common focal lines. The output beam of concentrated parallel beams is directed in the desired direction through a system of flat mirrors. With this system, the problem of cooling all the optical elements after the first parabolic concentrator is very large.

In U.S. Pat. No. 4,690,355, photoconverter cells are mounted on the back of a concentrating cylindrical parabolic reflector. In this case, the reflectors are secured by cables in such a way that the whole structure can be folded and unfolded repeatedly. However, in this way, large optical concentrating systems cannot be built.

In WO 1997/013104, parabolic mirrors with a common focus or focus line are used to concentrate the input parallel rays into an output beam of parallel rays. An additional flat mirror is used to deflect the output beam at an angle other than 0 ° or 90 °. In practice, the space in front of the collimating parabola is unusable, it needs cooling, as well as the additional flat mirror. Both parabolic mirrors are made monolithic, which makes it very difficult to protect the system from adverse conditions.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a modular optical concentrating system, hereinafter referred to as merely a system, to overcome the aforementioned disadvantages. First, to create a structure that allows the construction of systems of technically relatively easily executable identical or similar elements. Second, do not interfere with each other. Third, to address the temperature problems cited above. Finally, the design allows for easy folding and unfolding when needed without compromising the optical properties of the system.

In accordance with the stated task, the proposed system is made up of a plurality of identical or similar elements having reflecting surfaces in the form of a concentrating parabola and a functional curve. According to the invention, the reflective surface in the form of a functional curve of each element is positioned behind that of the concentrating parabola in such a way that the incoming parallel rays pass unobstructed to the latter and the formed output bundles reach their final destination without hindrance.

In one embodiment of the invention, the functional curve is a collimating parabola whose focus coincides with that of its corresponding concentrating parabola. In this case, the reflecting surfaces in the form of the two corresponding parabola may be so arranged that the output bundles are parallel to each other and are perpendicular to the incoming beams. It is also possible to position the two parabolic reflecting surfaces such that the output bundles are at an angle other than 90 ° from the input bundles.

In another embodiment, the concentrating and corresponding collimating parabolic reflecting surfaces are arranged such that the output bundles are collected sideways or behind the area system, the minimum of which is in the order of the area of a single output bundle.

The parameter and arrangement of the collimating parabola may be such that the surface of the reflecting surface, with its shape, is a function of the heat dissipated by it, while maintaining the degree of concentration. In addition, the concentrating and corresponding counter-collimating parabolic surfaces can form a module.

Again in accordance with the invention, said functional curve may be performed as part of a hyperbola, one of which focuses on that of its respective concentrating parabola, and the output rays concentrate in its second focus, which is common to the whole system and can be sideways or behind it.

Here, too, the parameters and the location of the hyperbolically shaped reflecting surface may be such that its surface is a function of the heat dissipated by it while maintaining the degree of concentration and its second focus being at the side or behind the system.

It is also contemplated that an additional scattering surface may be added to the reflective surface in the shape of a functional curve, made as a collimating parabola or hyperbola, to allow the system to be folded in the assembled state. In addition, the additional scattering surface and functional curve and concentrating parabolic surfaces can form a closed-space module65247 for forced cooling.

The same or similar elements described above, made up of reflecting surfaces in the form of a concentrating parabola and a functional curve, enable the system constructed by them to be folded and unfolded in working position. The working position of the elements is ensured by the supports located on the supports, corresponding to the number of elements.

Short description of the figures

In the figures shown, all rays are indicated by a dotted line and the inputs are from right to left. In all figures, the principles of the invention are illustrated by cross-sections showing the shape and location of the reflecting surfaces.

FIG. 1 and 2 show a classical mirror system for concentrating the incoming parallel beams of size a into an output beam of parallel beams (hereinafter referred to as only the output beam) of size b. In FIG. 1, the output beam is perpendicular, and in FIG. 2 - parallel to the incoming beams, the collimating parabolic surface 2 being opposite to the incoming beams.

In FIG. 3 and 4 show a typical Cashegrain structure consisting of reflecting surfaces in the form of a concentrating parabola 1 and a hyperbola 3. One hyperbola focus on surface 3 coincides with that of the surface 1 parabola and the other is common to the system Fo. In FIG. 4, the output rays concentrate behind the structure, and in FIG. 3 - away from it. The incoming parallel beams of size a focus in the general focus of the Fo system.

FIG. 5 shows a system of two identical elements arranged in such a way that the input parallel rays of size 2a are converted into an output bundle of parallel rays of size 2b.

FIG. 6 is an embodiment of the system of FIG. 5, wherein the output bundles are also parallel to one another, but are rotated at an angle other than 90 ° to the inlet bundles. The incoming parallel rays of size 2a are converted back into an output beam of size 2b.

FIG. 7 is an embodiment of FIG. 6, wherein the output bundles are assembled in one place. Input rays of size 2a (or larger) are collected side by side from the system to an area the size of a single output bundle b.

FIG. 8 is an embodiment of FIG. 7, except that the output bundles are collected behind the system and the collimating parabolic surfaces 2 are located opposite to the incoming beams. Here again, the incoming parallel rays of size 2a (or larger) concentrate on an area of size b.

FIG. 9 is similar in function to FIG. 1, but the collimating parabolic surface 2 is of area a commensurate with that of the aperture of the concentrating parabolic surface 1. The incoming parallel rays of size a shrink into an output bundle of size b.

FIG. 10 shows a system consisting of those shown in FIG. 9 elements which converts the incoming parallel beams of size 2a into an output beam of size 2b.

FIG. lie similar to FIG. 10, except that the angle of departure of the output bundles is different from 90 °. The incoming parallel beams of size 2a are converted into an output beam of size 2b.

FIG. 12 shows an embodiment of FIG. 11, whereby a greater concentration of output rays is obtained: the incoming parallel rays of size 2a (or larger) are concentrated in an area of size b.

FIG. 13 is a system of elements with parabolic 1 and hyperbolic 3 reflecting surfaces that have a common focus (focal line) of concentrating Fo, without interfering with each other, and the thermal load of the hyperbolic part 3 being absorbed by the much larger area of the covering parabolic part 1.

FIG. 14 shows an embodiment of FIG. 4, the area of the hyperbolic reflecting surface 3 is commensurate with that of the aperture a of the concentrating parabolic surface 1.

FIG. 15 is a system of elements shown in FIG. 14, with an overall Fo focus for the whole system.

FIG. 16 shows how the problem of precise positioning in the working (unfolded) position is solved in principle and what the system looks like in the folded (safe) state.

Examples of carrying out the invention

The one shown in FIG. 1 and 2 the classic mirror system consists of a concentrating parabolic surface 1, the focus (the focal line in the case of a cylindrical surface) F on which coincides with that of a collimating one. 1 fall on the reflecting surface of the concentrating parabola 1 and concentrate in focus (focus line)

F. By varying the parameter of collimating parabola 2, the degree of concentration a / b of the output beam of parallel beams is changed. By rotating the collimating parabolic reflecting surface 2 around the focus (focus line) F, only the direction of the output beam is changed, without practically changing the concentrations of the parallel beams. There are two problems with this known system. The first is the cooling of the collimating surface 2, which is generally much smaller than the concentrating 1. It can be solved without forced cooling by connecting the thermal collimating 2 with the concentrating 1 parabolic surfaces, and also by providing additional cooling surface 4, as shown in FIG. 6. The problem can also be solved by increasing the area of the collimating surface 2 to a size that allows the heating to remain within acceptable limits, as shown in FIG. 9-12. Another problem is the closure of part of the concentrating parabolic reflecting surface 1, in which part of the incoming beams is lost and the collimating surface 2 is further heated. As can be seen from the statement below, this problem can also be solved.

In FIG. 5 shows a system composed of two identical pairs of parabolic reflecting surfaces with common focus (s) Fi. The collimating parabolic surface 2 with focus F1 is mounted on the back (invisible to the incoming beams) side of the concentrating parabolic surface 1 with focus F2. This arrangement gives great freedom to the location and size of the collimating parabolic reflecting surface 2 (respectively of the hyperbolic 3) as well as the addition of additional cooling areas. The output bundles are parallel to each other and practically touch, i.e. add up. In this way, the input rays of size 2a are converted into a beam of size 2b. The heat to be dissipated from the small collimating parabolic surface 2 is taken up by the many times the concentrating parabolic surface 1, which is larger than the area. 6) without disturbing the functionality of the system. Moreover, it is possible to design a closed-space module 6 which allows forced cooling in case of need (for example, by further concentrating bundles of already concentrated parallel beams).

In this manner, an unlimited size optical concentrating system of uniform elements can be made, which shrinks when necessary, as shown in FIG. 16. This approach is also followed in all other proposed structures.

FIG. 6 shows an embodiment of the system of FIG. 5, wherein the pairs of concentrating and collimating 2 parabolic reflecting surfaces with common focuses (focal lines) Fi are arranged in pairs on one axis, the collimating parabolic reflecting surfaces 2 being rotated about their respective focuses (focal lines) Fi at a certain angle on this axis. In this way, the output bundles are diverted at an angle other than 0 ° or 90 °. The collimating parabolic reflection surface is again hidden behind and connected to the large concentrating parabolic surface 1. The output bundles are also parallel to each other and almost touch, i.e. are added up. However, they may also overlap in the workplace to varying degrees depending on the concentration required, with the maximum shown in FIG. 7. In this case, the output bundles of the whole system shall be collected in one area of size b equal to the area of one separate output bundle. In this construction, the concentrating parabola 1s have the same parameters, the collimating 2s also, but with different rotation angles around their respective focus Fi. The other options listed above are also possible.

FIG. 9 shows an embodiment of FIG. 1, wherein the collimating parabolic surface 2 has an area a commensurate with that of the aperture of the concentrating parabolic surface

1. In this case, in order to obtain the same concentration of the incoming beams as in FIG. 1, it is necessary that the parameter of collimating parabola 2 be much smaller than that of FIG. 1. Thus, the heating of the collimating parabolic reflecting surface 2 is practically commensurate with that of the concentrating parabolic surface 1 of FIG. 1. If necessary, the area of the collimating surface 2 may further increase depending on the required dissipative heat output. The advantages described above are complemented by the increased heat dissipation capacity and also the ability to be used in full internal reflection systems. The construction permits such arrangement of the collimating surface 2 so that it is sufficiently distant from the caustic point (line) F. If the collimating surface 2 is positioned opposite to the incident beams, the pair may be constructed as a module. This ensures the accuracy of the mutual arrangement of the two parabolic surfaces during the production process. In addition, it allows the enclosure 7 (Fig. 12) to be closed to provide forced cooling in case of need. As with all the structures offered so far, a system can be constructed that folds as needed.

FIG. 10 shows a system similar to FIG. 5, but consisting of those shown in FIG. 9 items. The collimating parabolic surfaces 2 do not interfere with the concentrating 1 as well as the adjacent output bundles. The advantages of a system configured in this way over that of FIG. 5, are: 1. The collimating surface 2 does not exert additional stress on the concentrating surface 1; 2. The precision of the relative position of the two parabolic reflecting surfaces can not be much easier to produce.

Referring to FIG. 11 and 12, the advantages of FIGS. 9 and 10.

FIG. 13 shows an even greater concentration at the point (line) Fo outside the range of the receiving structure. The known Casgrain type configuration shown in FIG. 3 and 4, usually made of monolithic surfaces. In our case, the hyperbolic reflecting surface 3 is mounted on the back (invisible to the incoming beams) side of the concentrating parabolic surface 1 of the previous pair of hyperbola. Thus, it is possible to design a large optical concentrating system according to the invention with all the advantages described above. The cost of high concentration is due to the fact that hyperbole 3 has different parameters.

In FIG. 14 the heating of the hyperbolic surface 3 is commensurate with that of the parabolic surface 1 of FIG. 4.

FIG. 15 shows the possibility of forming a large optical concentrating system of the elements shown in FIG. 14, wherein the concentrating parabolas 1 are the same and the hyperbolas 3 are of different parameters so that all the input rays are focused at one point Fo.

The requirements for design accuracy, like any optical system, are very high. Therefore, folding and unfolding the structure seems impossible. But if you look at FIG. 16, it can be seen that this can in principle be solved, especially for cylindrical surfaces. The elements having reflecting surfaces in the form of concentrating 1 and collimating parabola 2 are secured to the movable part 9, which can move freely on the guides 8. And the positioning can be accomplished with great precision by stops 10 and

11. The lugs 10 and 11 are mounted on the supports 13 in the required place with the required precision, which does not change when the respective parts are moved. When the part in question is to be positioned, it simply has to be pressed to its proper stop with the necessary force and its position is guaranteed with the required accuracy.

The construction is protected from shock by the dampers 12. Similarly, elements containing reflecting surfaces with the profile of all other pairs of curves mentioned above can be arranged.

Claims

Claims (15)

An optical concentrating system made up of a plurality of identical or similar elements, consisting of reflecting surfaces in the form of a concentrating parabola (1) and a functional curve, characterized in that the reflecting surface in the form of a functional curve is located behind the reflecting surface in the form of a concentrating parabola (1) in such a way that the incoming parallel rays pass unimpeded to the concentrating parabola (1) and the formed output bundles seamlessly reach their final destination. Optical concentrating system according to claim 1, characterized in that the functional curve is a collimating parabola (2) whose focus coincides with that of its corresponding concentrating parabola (1). Optical concentrating system according to claim 2, characterized in that the concentrating (1) and collimating (2) paraboles are arranged such that the output bundles of rays are parallel to each other, are arranged perpendicular to the input bundles rays. Optical concentrating system according to claim 3, characterized in that the outgoing bundles of rays are at an angle other than 90 ° with respect to the incoming bundles of rays. Optical concentrating system according to claim 2, characterized in that the concentrating (1) and collimating (2) paraboles are arranged so that the output bundles of rays are collected sideways or behind the concentrating system in an area of at least the order of the area of an elementary sheaf. Optical concentrating system according to claims 3,4 and 5, characterized in that the parameters and arrangement of the collimating parabola (2) are such that its area is a function of the energy dissipated by it while maintaining the degree of concentration. Optical concentrating system according to claim 6, characterized in that the concentrating (1) and collimating (2) paraboles form a module. Optical concentrating system according to claim 1, characterized in that the reflecting surface of the functional curve is part of the hyperbola (3), one of the focuses coinciding with that of its respective concentrating parabola (1) and the output rays concentrate in its second focus (Fo), which is common to the whole system and can be sideways or behind it. Optical concentrating system according to claim 8, characterized in that the parameters and the location of the hyperbola (3) are such that its area is a function of the heat dissipated by it at-. preserving the degree of concentration. Optical concentrating system according to claims 2, 3, 4, 5 and 8, characterized in that an additional scattering surface (4) is added to the functional curve (2,3). Optical concentrating system according to claim 10, characterized in that the additional scattering surface (4) added is of a shape that allows the system to be folded in the assembled state. Optical concentrating system according to claims 2, 3, 4, 5, 8 and 9, characterized in that the concentrating parabola (1), the thermally coupled functional curve and the added additional scattering surface (5) form a closed module space to be used for forced cooling while maintaining the other functions of the system. Optical concentrating system according to claim 7, characterized in that a similarly shaped scattering surface is added to the module, thereby creating a closed space (7) between them, which can be used for forced cooling while maintaining the other functions of the system. Optical concentrating system according to claim 1, characterized in that it is composed of identical or similar elements, consisting of reflecting surfaces (1, 2 or 3), which can be folded and occupied. Optical concentrating system according to claim 14, characterized in that the positioning of the reflecting surfaces (1, 2 and 3) in the working position is ensured by the supports (10) located on the supports (13).