DE2506905A1 - Parabolic mirror assembly for sunlight concentration - has mirror coated plastics foil and rigid annular edge structure - Google Patents

Abstract

The parabolic mirror assembly is intended for concentration of sunlight for energy recovering by devices utilising light or heat, such as directly converting semi-conductor solar cells. The mirror (1) consists of a plastics foil for laminated plastics tissue, provided on one side with a mirror coating and having a shape of a paraboloid. The latter edge is connected to a rigid annular structure (3) supporting the mirror. The paraboloid is maintained in its shape by differences in air or gas pressure. Preferably a transparent foil or plate (12) is clamped in front of the mirror opening, which may be divided into smaller sectors by a support net. The annular structure is preferably mounted inside the parabolid edge.

Description

Parabolic mirror arrangement for generating energy from sunlight The invention assumes a parabolic mirror arrangement to concentrate the sunlight for the generation of energy through light or heat using devices - esp.

Direct converting semiconductor solar cells - in concentrated luminous flux.

Such arrangements are known. For example, in Odeillo / PyrenRen a high-performance high-performance mirror system for technical heat evaluation economically Experiments have also been made with electricity-generating solar cells and concave mirrors using mirror formats from radar technology Mirrors and solar cells fail because of the huge mirror structures that are required In addition, the terrestrial use of solar energy is based on storage technologies reliant. In Central Europe there are only about 600 hours of sunshine per year.

Apart from the fact that the electricity industry for network planning reasons likes to see works of gigawatt capacity, the spread of solar use stands against a considerable prejudice by state and economic bodies that it arises less engineering-like, but rather aue already in atomic energy investments made and political constraints can be explained.

Despite the comparatively minimal requirement of solar technology are here However, breakthroughs have been made that may be very encouraging.

Since the creation of latent heat storage systems, heat storage technology has exceeded cfidenen mixtures of hydrates, chlorides and fluorides with their crystallization thresholds are used (Laing, Schröder) the lead accumulator in the energy capacity twenty times.

for a new type of GaAs / GaAlAs cell, the manufacturer gives a voltage of 1 V. the efficiency of 25%. The prerequisite is favorable and strong sunlight, where 1cm2 of the cell delivers 40W in a 1000-2000-fold concentrated luminous flux That results in the following relations s with regard to different Hohispiegoidurohesser Mirror opening area Cell area output (1/2000 opening area) Output m m² cm² kW 2 5 15 0.63 6 28 140 5.6 10 78.5 393 12 20 314 1570 60 40 1255 6000 250 80 5000 2.5. 104 1000 (11w) Even if you only get a third of this yield for Central Europe This technology produces quite useful numerical values If mirrors and storages can be built economically, such systems are both for individual consumers as well as for communities and for industry interesting and There could be a further increase in electricity consumption on both the environmentally friendly and the future generations will not be absorbed in a burdensome way.

The object of the invention is to create a low-cost mirror, which is better suited than conventional mirrors for the purposes mentioned and which is merely has the focusing accuracy, as it is when using utility equipment in one Above all, a parabolic mirror that automatically is adjusted to the sun.

This task is solved by the fact that at the beginning of the year Device of the mirror from a one-sided mirrored plastic film or a tunetstoff-fabric layer material, which at least closely approximated Paraboloid shape possesses that the paraboloid at its edge with a rigid, the Mirror-bearing ring construction is connected, and that it is by air or gas pressure difference in its Shape is held.

This maintenance of the shape is advantageously carried out in that a translucent film or plate is stretched in front of the mirror opening, which hermetically sealed against the paraboloid edge, which may be supported by a supporting net is divided into smaller sectors that the ring construction is preferably within of the paraboloid edge is arranged and that between said cover and an air or gas overpressure is maintained in the mirror paraboloid.

A more advantageous embodiment of the construction provides that especially for large-scale use, the back of the paraboloid of is enclosed by a shell structure connected in a gastight manner with its edge - in particular of a spherical segment construction made of steel or fiberglass - and the load-bearing Ring constructions lies within the paraboloid rim or, in particular, Wurch the edge of the spherical segment opening is formed and between the paraboloid and shell structure a negative pressure is maintained.

The paraboloid shape is advantageously made of plastic in its final form Dimensions and their spherical shape using a model shape by contractors, Centrifugal, blowing or deep drawing produced, possibly one in the inflated Final state occurring elastic deformation is taken into account and the mirroring of the rarabololde takes place according to its shape.

gravel more suitable and special machines for series production The required paraboloid is particularly advantageous for lower numbers of items replaces the fact that the raraboloid is made up of precalculated or constructed elements flat mirror film - especially made of PVC - is glued or welded together, so that after applying the water pressure difference the Faraboloidform is approximated.

This construction is based on an advantageous development in the manner of an umbrella or parachute of a multitude of the same, flat triangular segments which, under the influence of the water pressure, become spherical triangular surfaces shape, the rorm of the flat segments is chosen so that in the spatial state the longitude-like edges, which are reinforced by the adhesive or weld seams, the correspond to the preselected true parabolic course according to the desired nominal spot position.

It is useful that the supporting ring structure that is within of the sand of the earaboloids, from a full round or curved round circle Tube profile, in particular made of fiberglass or light metal.

This advantageously allows the dispute segments that for the purpose of their shape calculation or geometric construction as flat segments of a polygon with mutually meridian-like intersecting segments from the spatial shape of the respective underlying parabola are assumed iorm, are cut without overlap and that the planar segments in the constructed or calculated planar form, expediently with a two-part pressing device whose two parts are severed in the final parabolic shape and one can also be used for the precise cutting of the segments, butt-butted with an overlaid nand are glued or welded and that in the raraboloidbeheitelpunkt Cut out a small circular area and replace it with a rigid plate - possibly as a valve support - is replaced.

After a favorable further education, the narrow side is the one mentioned Segments btw. dimension the ring construction circumference so that the segments Circumferential polygon of the polyhedron formed rsehmal sides - i.e. the scope of the plan of the screen structure on which the construction is based - a ring construction of this type encloses that under consideration Inspection of the permissible elaotiechen Stretching of the sheet material creates a cyclone-like contact line between the inner one Paraboloid edge and the ring construction results, in the area of which both parts are to be glued tightly and then the protruding blunt corners of the screen structure be cut off parallel to the ring and one that protrudes beyond this adhesive strip Edge glued a little further around the ring construction, making notches is.

The roll that covers the parabolic opening is turned with the front the ring construction and possibly also glued to the last-mentioned edge part and outside along the seam between the cover and the paraboloid edge along the ring construction An elastic band is glued on with a slight pull to connect the two parts.

Brackets and bearing elements for azimuthal and vertical pivoting of the mirror image are advantageous with the ring construction under corresponding Sealing screwed) a sun sensor and corresponding electronic equipment take care of the tracking of the mirror via drives.

It is useful to choose the basic parabola of the paraboloid so that that the focal point comes to lie within the upper pressure space and the utility apparatus is suspended from the ring structure via a rod or rope structure and in particular, the parabolic shape is chosen so that on the front and back of the utility apparatus approximately the same luminous flux falls and the shape of this apparatus - especially the Bodies to be covered with solar cells - the directions of incidence of the reflected luminous flux is adapted.

In mesh skins it is finely tuned by choosing the appropriate parabola Laying the focal point outside the cover foil, and possibly advantageously in the cover foil a round serpentine made of low-loss glass, especially quartz glass, with the diameter of the reflected light rons present there, with the application apparatus is arranged on bars in front of the cover.

In this way the 1st focal point can be handled and it becomes a excessive heating of the film ggi. prevented.

For large mirror openings and the construction without an aboedF film - it would then become too strong - and with a shell construction, an advantageous further development of the subject matter of the invention provides that the shell, designed as a guge segment, is floating in a body of water in such a way that the ball is over one surrounding platform or a bollard ring and corresponding rollers or balls, the floating ball bearing the mirror can be adjusted to the sun and a stable basic position is given by internal ballast.

It is advantageous to use the mirror for use in moderate latitudes overdimensioning with regard to the mean focal spot concentration to be achieved and to increase the Brennileck light density when the sun is near the horizon or an intentional during the duration of covers of the sun in full sunlight The paraboloid is focussed due to its shape in the direction of a spherical orm by a slight and justifiable within the framework of the material properties of the piaboloid Overpressure or underpressure increase can be achieved by sensors in the focal point takes place automatically controlled and within certain limits an almost constant Luminous flux in the focal spot area is maintained.

Such a defocusing can also be achieved by driving the nut apparatus can be achieved along the axis of symmetry of the paraboloid.

The subject matter of the invention will now be exemplified with reference to the figures It shows: Fig. 1 The geometric construction of a lateral surface for Assembling a paraboloid-like body from flat segments Fig. 2 Perspective view of an imaginary inflated one pulled onto the support ring and paraboloids composed of segments Fig. 3 Details at the edge of the Parabolic plugs produced according to the invention with a translucent cover Fig. 4 A complete mirror in one design for small and medium diameters Fig. 5 A construction as in Fig. 4, but not arranged outside the cover Focal spot Fig. 6 A mirror arrangement without cover and support structure for large mirror openings and for floating anchoring in a body of water1 Die Embodiments according to Figures 1-5 relate to a construction in which between the paraboloid 1 made of favorably-priced polie and a translucent, luit-tight one the mirror opening closing cover 12 by a pump 24 an overpressure is maintained automatically controlled.

In Fig. 1 a way is indicated, such as a paraboloid-like polyhedron , which is composed of flat segments, can be constructed geometrically Construction as well as a corresponding calculation have long been state of the art, so far they only concern the multifaceted.

It is assumed that suitable for the solution of the problem Mirror foils have a certain elasticity, and in a small ready ph are deformable without adverse effects occurring. Even at low temperatures can be expected with a small elasticity of PVC, for example. with a sufficiently small subdivision of the paraboloid into meridian-like cut Segments 4 both at the edge of the chord length 8 over a load-bearing ring 3, and later through the flat segments 4 Iutt or gas pressure so tu form spherical triangular surfaces that a paraboloid shape arises, the allows the sunlight to be focused with sufficient accuracy.

The number of segments 4 depends on the properties of the film to be judged, which are to be determined in each case by experiment or specification in Figure 1 there are 14 segments, a number that is generally sufficient.

The method of composing the paraboloid from flat segments as in Figure 1 is especially for smaller quantities.

Of course, greater accuracy is achieved by the factory-made production of paraboloids from layered material in the manner of a radome, but the mirroring in particular is more complex here. In this latter case, a small residual elasticity is desirable and also achievable, especially for the deliberate defocusing of the mirror to be described later, and can also be achieved. The relationships can also be seen that result from the too short parabola in the middle of a segment (e.g. lying on the line of symmetry in FIG As indicated under 6a, this too short parabola is folded into the elevation plane and results in the dashed course 9. With the position of ring 3 as indicated in Fig be compensated by the fact that the ring or the segments are dimensioned eo that the paraboloid casing over the ring within the scope of the foil elastic ity is tensioned, as is also indicated in Fig. 2 and that finally the air pressure also causes a similar deformation of the other planes of the paraboloid when the pressure difference is applied. slls labeled 10 Ban places (Wce the true parabola 9 is only insignificant.

The processing and sounding procedure indicated in FIG Auiriß to determine the true flat shape of spatially curved surfaces known from elementary descriptive geometry. In elevation, 4a represents the true Represent dimensions of a flat subsegment.

At 7, the line of contact is indicated, which arises approximately when the composite film body is pulled over the ring 3. As a result of this occurring tension - which must be controlled when bonding both parts - is this in reality - as is desirable for the gluing - a band-shaped Area of the indicated shape.

FIG. 2 shows that after the parts 1 have been pulled on and glued together and 3 a protruding edge remains. This becomes blunt tips at the joints the outgoing edge is cut off parallel to the ring 3 so that a kest of the edge after making notches, still wrinkle-free over a small angle of the profile 3 can be glued, as indicated in FIG.

In the apex of the paraboloid, an iron surface is advantageously cut out and replaced by a round plate 11 made of foil or reflective sheet metal in order to achieve the numerous seams in this area to create defined relationships.

In Figure 3 it is shown how the transparent cover 12 also glued with ring 3 and with paraboloid 4 by an elastic, under tension over the Seam bonded tape 16 is connected, which also protects the outer edge mechanically.

13 and 15 are a fitting part held by the screws 14 and a bearing pin with which the very light Spiebelgebild can be pivoted vertically Ring construction 3 can be stored with mirror openings of a few m advantageously made of fiberglass, which has the advantage over aluminum of being light to be shaped into a fairly exact circle Be held together piece of pipe, which is let in that ring 3 always the same Has strength.

The trimming of the segment parts 4a is advantageously carried out with an auxiliary device, which has the shape of the selected Para and has an electrically heated sheet metal strip, with which the segments can be precisely cut out.

An auxiliary device is also required for gluing the strip 10 on adjacent segments. If it is also possible to make the segments larger and gluing and welding overlapping, it is easier to make the segments to prepare exactly in their constructed or hardened outline form and between them two with a dampening coating, cut apart exactly according to the shape of the desired parabola To glue or weld boards together with the tape 10.

In Fig. 4 is a finished smaller one -for example for a garage roof more suitable - mirror. It is represented by an electronic one not shown in detail Device via drives 22, 23 and ring gears 21 - preferably made of plastic - the Sun adjusted, with rollers and rails 20,28, the latter also advantageous like Rin 3 made of fiberglass, and the bearings 15 vertical and azimuthal depiction to back up.

12 is the translucent cover optionally subdivided by a mesh, the advantageously consists of a tough and very clear PVC copolymer. 18 represents a Bracing of the ring 3, which may already be necessary because of the bracket 17, the if necessary, if elastic, pulls on the ring. A toothed rack segment is advantageous on bracket 17 21 for vertical control. Pump 23 and drives 22 can be connected to a collector can easily be supplied by the mirror itself if the evaluation apparatus 34 (on linkage 27 hanging) electricity generated and not liquefied in 34 melts should. Finally, 25 is a cable that leads to the storage facility.

In Fig.5 is a system with a flatter mirror and with a focal point in front of the cover. Here the light has to pass the cover twice, which without significant loss of energy, especially with a round window 35 in the cover 12th This window is preferably made of thin Quartz glass to also recycle the UV components, which is also recommended because of the high light density near the focal point, especially when the cover is dirty I would like to heat a film inadmissibly. Furthermore, it is not recommended to use the To make the mirror too flat and to put the focal point far outwards, there next to it mechanical problems then also lead to accuracy problems with the paraboloid result.

In Figure 6, a construction according to the invention is shown, which is not Has bearings and no suspension and without cover 12 with negative pressure between the shell 30 and Paraboloid 1 works. Such a system is suitable for large-scale Use and is as an electricity or heat supplier especially for the heat demand of Municipalities and cities are suitable, especially latent heat storage.

The ball 30 is advantageously screwed together from reinforced fiberglass segments, they can also be welded from sheet steel, using ballast, it is placed inside a platform or a bollard ring, which are in contact with it via rollers, in a central one Normal position stabilized. The control takes place via the rollers or balls the sun. Safety ropes 29 are rolled in trestles 31 on reels and are at Adjustment movements tracked accordingly. The control of the drives and Reeling takes place via gear motors depending on signals from a sun sensor Safety ropes also measure the wind forces that act on the system.

At 32 ends a rain gutter from which rainwater is drained Care can be taken to ensure that the Mirror opening level by means of appropriate control of the ball is vertical and So that no rainwater can get into the mirror. An apron 33 can in this position prevent waves from reaching the mirror.

Such large systems have not yet been built, but since they are comparative are problem-free and cheap - the solar cells mentioned at the beginning only cost one vanishing proportion of the common in space travel - and no energy sources either its totalization makes sense from a technical point of view.

In contrast to atomic plants, the plants described last can also be settled in quarry ponds, gravel pits, reservoirs and industrial waters, whereby no radiation or heat contamination occurs and the balls are also used as brutal structures @@@@@ @@@@@.

Of course, they cannot use locally concentrated power plant blocks replace as such, but many solar systems with latent heat storage systems scattered across the country (they can nowadays be built so that they are ideally insulating and can be called up in a metered manner) can be another Cope with the increase in the already stagnating electricity consumption in an environmentally friendly way eo make the beneficial atomic technology superfluous.

Smaller systems that fit on a garage roof can be combined With battery packs a cheap operation of at least small electric vehicles.

Claims (15)

Protection burst out 1. Parabolic mirror arrangement for concentrating sunlight for Devices that use light or heat to generate energy - in particular direct converting semiconductor solar cells - in concentrated luminous flux, d a d u It is noted that the mirror (1) consists of a one-sided mirrored Plastic film or a plastic fabric Schlchtmaterial consists of at least strongly approximated Paraboloidiorm possesses that the paraboloid (1) at its edge with a rigid ring construction supporting the mirror) and that it is connected by Luit or gas pressure difference is kept in its shape. 2. Arrangement according to Al, d a d u r c h e k e n n -z e i c h n e t that a translucent film or plate (12) stretched in front of the mirror opening is that ggi. is divided into smaller sectors by a support network and that the ring construction (3) is preferably arranged within the paraboloid edge and that between the said cover (12) and the mirror paraboloid (1) an air or gas overpressure aurrecht is true 3. Arrangement according to claim 1, d a d u r c h g e k 0 n n -Z e i c h n e t that the back of the paraboloid (1) from one with its edge shell structure connected in a gastight manner, in particular a spherical segment shell (30), made of steel or fiberglass, is enclosed, the ring construction in particular is formed only by the edge of the spherical segment opening and between paraboloid (1) and shell (30) a negative pressure is maintained. 4. Arrangement according to one of the preceding claims, d a * d u r c h g e k e n n n n e i c h n e t that the paraboloid (1) is made of plastic or plastic layer material in its spherical shape using a model device by Application, centrifugation, blowing or deep drawing is made, with a possibly slight deformation resulting in the inflated state is taken into account and the reflection is then applied. 5. disorder according to one of claims 1-3, d a d u r c h g e k e It is not stated that the paraboloid is made up of precalculated or preconstructed Segments (4,4a) of a flat mirror film - in particular consisting of PVC - glued together or welded, eo that after applying the Druekuntersehleds approximated the Paraboloidiorm arises. 6. Arrangement according to claim 5, d a d u r c h g e k e n nz e i e n e t that the paraboloid (1) is composed of a large number of flat strip segments which under the influence of pressure form into spherical triangular surfaces (4) and the shape of the segments eo is chosen so that in the spatial state both of them are meridian or Long sides similar to longitudes, which after joining by ele. or welds are amplified, correspond to the respectively preselected parabola lost to. 7. Arrangement according to claim 6, d a d u r c h g e k e n n -drawn, that the ring structure (3) arranged within the paraboloid edge consists of one Round or tubular profile bent into a circle, especially made of fiberglass or aluminum or light metal. 8. Arrangement according to claim 7, d a d u r c h g e k e n n -z e i c h n e t that for the geometric construction of the unrolled, flat true form of the segments 4 these as peripheral surfaces of an umbrella-like polyhedron (Fig. 1) are considered, whose meridian-like seams (9) the spatial shape of each underlying parabola, the segments preferably without overlap are tailored that the segments expediently in a two-part Pressvorriohtung whose both parts in the final jewel pzrabeldor are duroheparted, butted to one another. Bend Dit an overlaid tape (10) are glued and in the paraboloid apex a Small circular area left out and with a @@@ @ plate made of foil or mirror sheet -possibly. used as a valve carrier - is closed (11). 9. Arrangement according to claim 8, d a d u r e h g e k e n n -z e i c h n e t that the melting sides of the segments (4a) 60 or the ring are dimensioned (3) eo is dimensioned that the structure formed from the segment narrow sides underlying circumference polygon of the polyhedron surround the ring construction in this way can that taking into account the permissible elastic elongation of the film material a cycloid-like contact band (7) between the paraboloid edge and the ring (3) itself shows in which area these parts are glued 10, arrangement according to claim 9, that the cover (12) with the front side the ring construction (3) and possibly with the edge of the paraboloid fixed there airtight is glued and over both parts along the edge or the Ringkonstr.3 below Well an elastic band (16) is glued. or a previous one, 11. Arrangement according to claim 10, characterized g e k e n nzeich that on the ring construction bracket or. Bearing fittings for azimuthal and vertical pivoting of the mirror are attached under sealing and these devices (13,19,15,20,28) of the follow-up movement of the mirror serve according to the control signals of a sun sensor. 12. Arrangement according to one of the preceding claims, d a -d u r c h g e k e n n n n n e i c h n e t that the basic parabola is chosen so that the focal point comes to lie within the overpressure rams and the utility apparatus (34) via a Rod or attachment structure (27) is attached to the ring (3) and in particular the same Luminous flux falls on a front and a rear side of the utility apparatus (34) Shape is adapted to the directions of incidence of light. 13. Arrangement according to one of the preceding claims, except Claim 3, d a d u r c h g e k e n n t e i o hnet that by appropriate basic parabola selection the focal point comes to lie in front of the cover (12) and possibly in this cover a round window made of low-loss glass (35), in particular quartz glass, is used, which has the diameter of the reflected luminous flux present there, and that the Apparatus (34) is fixed to rods on the ring (3). 14. Arrangement according to claim 3, d a d u r c h g e k e n n -z e i c h n e t that for large-scale application the one designed as a spherical segment Shell (30) welded together from steel segments, inebes. but made of reinforced fiberglass-plastic segments is put together and is fixed floating in a body of water, with bottom ballast or counterweight and ropes fixed on reels on land provide a stable basic alignment and readjustment is ensured and the ball in the opening of a stationary one Platform or within a ring of bollards is set so that over Rolling or balls or the like a readjustment of the ball is possible 15. Arrangement according to one of the preceding claims, d a -d u r c h g e k e n n z e 1 c h n e t that the mirror is oversized with regard to the achievable light concentrate ion is and that in normal operation in strong sunlight an intentional focussing due to increased upper or lower pressure) or adjusting the utility apparatus is maintained along the axis of symmetry of the paraboloid and continues to search sun radiation - automatically controlled by focal point sensors - optimal Focusing on the utility apparatus (34) takes place. ) for slight deformation of the paraboloid in the direction of a Spherical shape L e r s e i t e