DE4425891A1 - Mirror for utilisation of solar energy - Google Patents

Abstract

Mirror for reflecting solar energy has a reflecting part consisting of separate, overlapping and replaceable, reflective or metallised films which are tensioned on a network on which they rest by low pressure. They are bent to form a parabolic cylindrical surface. The network can be formed by a two-dimensional chain of rigid and flexible elements, the latter mfd. from rings twisted and coiled from a strong thread. Solar energy can be utilised by a spiral-shaped pipeline through which a salt nutrient soln. with microalgae, saturated with CO2, is passed.

Description

The invention relates to a mirror for the use of Solar energy is suitable. The mirror consists of interchangeable, reflective pieces of film that go together with a net on which they rest, against one against the other Resilient scaffolding with the help of the Are under pressure. With this tension, each forms Foil piece a parabolic cylinder surface, which the Solar radiation on a circular area with a diameter, comparable to the maximum film piece width is bundled. The radiation energy of the sun is used by two systems:

• - A part is converted into chemical energy of photosynthesis by microalgae and / or photobacteria. The microalgae flow in a nutrient solution through a spiral pipeline Fig. 3 and Fig. 7 Pos. 10, the tube of a material permeable to the solar spectrum, for. B. quartz.
• - The rest of the solar radiation spectrum is absorbed by the solar cells, which lie behind the spiral pipe on the above-mentioned circular area Fig. 3 and Fig. 7 item 9, so that the solar energy is partially converted into electrical energy.

A sun mirror

The present invention relates to a mirror a curved surface and offers a method to its manufacture with a calculation method.

The crooked bowl-like ones known from the past Mirrors are made of either coated materials such as Metal, glass, solid plastic or from a polished Metal. The execution of more precise Curvature in such materials requires an abundance of complicated and costly operations. But not only the manufacture itself but also the weight of such rigid constructions are economic obstacles. Of the Sense of solar energy use is lost when the energetic manufacturing expenditure the energetic gain surpass. Here one understands energetic Manufacturing expenditure all the amount of energy from the Raw material extraction up to the final stage as finished Product. Under the energetic gain one understands the Amount of energy gained from installation to Plant wear. This applies even if none radiation condensing devices such as the sun mirror available, and z. B. solar cells directly exposed to the sun are.

The presented invention seeks to be a mirror to provide, which has the disadvantages mentioned overcomes that it is not a rigid construction. Because of its resilience to the shock loads there is a way of making it extremely light and therefore to carry out material-saving structures. Of the economic effect is further increased by the fact that Converts solar energy into biochemical energy. The Production of microalgae, in vitro, offers an ideal Condition for gene manipulation and thus generation of valuable proteins in human medicine, such as Insulin or interferon.

The radiation of the sun in the presented invention is not concentrated on one point, but is compacted on a circular area, which further simplifies the system. To bundle the solar radiation, individual pieces of foil, overlapping and mirrored according to the type of tulip pos. 1, Fig. 4, are used, which together with a net on which they rest, are curved by negative pressure in the form of a parabolic cylindrical surface so that overall a concave surface is created. Between the overlapping pieces of film there is a viscous layer that is impermeable to air. The net with the pieces of film resting thereon is drawn over a structure which is flexible against the impact loads, so that there is a slight negative pressure in the interspace. The scaffold consists of an inflated, torus-related rotating body and individual supports item 5, Fig. 1, 2, which are supported on it.

From the comparison with the invention GB 2 000 319 A, in which also a reflective or mirrored and by negative pressure elastically deformed film is used here recognize the following advantageous features:

First: In contrast to GB 2 000 319 A, this is here used film from several mutually overlapping and pieces based on a web that are not in two but elastic in a kind of one-dimensional curvature are deformed. This results in a constructive one Simplification; you need a lower pressure difference to elastic deformation of the reflective part.

Second, there is the possibility of using Materials with much lower elasticity, such as B. with Metal coated paper or ceramic. Such materials but are essentially more resistant to the Ultraviolet radiation as polymer materials such as rubber or Plastic.

Third: The interchangeability of the reflective Pieces of film extend the availability of the mirror.

The invention GB 2 000 319 A is also a construction where a reflective film over rigid cylindrical structures is clamped under pressure difference and where but There is no compliance with the shock loads.  The presented invention offers a base of the The main component is to absorb shock loads is an inflated torus-related body. Meridional The curve of this body has a shape that is defined by the describes the following differential equation:

where "kr" and "l" are the constants.

This special shape satisfies the desire that the mesh covering the inflated body has been stretched almost exclusively in the direction of its meridional curve. The latitude tensions are on the polygonal ropes Pos. 21, 22, 23 ; Figures 1 and 2; transmitted from the spanning network. These ropes are relaxed when a negative pressure is generated in the room pos. 13. Fig. 3 and the voltage is transferred to the network carrying the reflective pieces of film.

The differential equation is compiled from the following considerations:
The definition of the curvature "K" of a meridional curve of an ideal, inflated rotating body, which in practice cannot be carried out due to instability, the wall of which is stretched exclusively in a meridional direction, is shown in Figure N1.

Where "Δt" or the image No. 1 corresponding to "Δtau" Direction angle change in radians and "ΔS on Arc piece of the curve or an elementary length of the route. On the other hand, as can be seen from picture no

because the same force of overpressure affects the same size elementary surface of the hose wall "ΔF"

According to the definition is too
If you set kr = K at x = 1

After integrating equation (7) we get:

from which

results
at y ′ = 0, kr * x² + 2 * l * C = 0 and

see picture N1
Then it will be:

If y ′ = ∞; then 4 * l²-kr² * (x²-m²) = 0; and (2 * l-kr * (x²-m²)) * (2 * l + kr * (x²-m²)) = 0; and 2 * l-kr * x² + kr * m² = 0 or 2 * l + kr * x²-kr * m² = 0; (8) and (9). In this case, according to picture no. 1, "x²min" once equal l.

From (9) we get:

and out of (8)

After eliminating "m" we get:

After a substitution x / l by ch (t), where ch (t) a Hyperbolic cosine of t, where x = l * ch (t) dx = l * sh (t) dt, and

we receive

This function cannot be integrated elementarily will. Therefore both integrands of the function are included Integrated row development help. Both rows and their integrals are convergent in the domain:

xmin <x <xmax.

There are other, simpler methods of calculation and if you break the meridional curve through a broken one Line, with a constant change in direction angle ".DELTA.t" and approximated with a variable path length "ΔS". The coordinates Xn + 1, Yn + 1 of every next break point of the Line are calculated from the following relations:

Xn + 1 = Xn-R * Xmin * Δt * sin (An) / Xn;
Yn + 1 = Yn + R * Xmin * Δt * cos (An) / Xn;
sin (An + 1) = sin (An) * cos (Δt) + cos (An) * sin (Δt);
cos (An + 1) = cos (An) * cos (Δt) -sin (Δt) * sin (An); (9)

Δt = pi / N; where N is an arbitrarily large integer.
sin (Δt) = Δt-Δt³ / 6; cos (Δt) = 1-Δt² / 2;

"R" is a radius of curvature when Xn = Xmin.
"On" is an angle of inclination of the elementary distance "ΔSn".
At the point where Xo = Xmin, Ao = pi / 2; and "ΔSo" = R * Δt;

Xmin or "l" and "R" are the parameters of the in picture N1 shown function.

There is a computer program where the recursive formula (9) is used for the design calculation.

The parameters of the individual sections of the meridional curve FIGS. 1a-b, bc, cd, de, ef and fa are determined by iteration. From this, the tensile force acting on individual, meridional elements of the net spanning the inflated body can be calculated.

For example, the pulling force "P" acting on the section "fa" is Fig. 1:

P (f-a) = ÜD * 2 * pi * l (f-a) * R (f-a); (10)

where "ÜD" is an overpressure inside the inflated body. On the section fa, Fig. 1 and Fig. 2 are 96 meridional network elements which are exposed to this force. The strength of these network elements is calculated from this. In addition, the stresses in all other network elements as well as in the polygonal tensioned ropes in the girders and in the network elements that carry the reflecting part can be calculated.

Embodiment

The accompanying drawings show:

Figure 1 is a representation of the inflated, torusverwandten body of the invention with him spanning network and supporting thereon 24 disks.;

Fig. 2 shows the same view; View from above;

Fig. 3 general side view;

Fig. 4 view from above and from below.

Fig. 5 node part of the network.

Fig. 6 piece of film of the inflatable tube.

Fig. 7 of the compressed solar radiation exposed circuit with the solar cells and a spiral pipe.

The sun mirror shown in Fig. 1 to 7 consists of a tube, which is composed of the overlapping pieces of film Fig. 6 and wrapped with a net by overpressure takes the form of a toroid-related hollow body. The forces from the spanning network are transmitted to the polygonal ropes 21 , 22 , 23 ( Fig. 1 and 2). In contrast to the ropes 22 and 23 , the forces on the ropes 21 stretched as a skewed polygon are transmitted from the network via the 24 beams 5 . At the negative pressure in space 13 ( Fig. 3), the ropes 21, 22 and 23 are relaxed, and the stresses are taken over by the network 3 ( Fig. 1 and 2) carrying the reflecting part. The circular disc ( FIG. 7, FIG. 3), which holds the solar cell 9 and the spiral pipeline 10 ( FIG. 7), is carried with the aid of telescopic column 15 ( FIG. 3) pushed apart by excess pressure 14 . The axis of the column 15 is directed with the aid of the ropes 11 , Fig. 3 so that it coincides with the mirror axis. The air from the vacuum chamber 13 ( FIG. 3) is pumped out with the aid of the ejector 12 ( FIGS. 3 and 4).

According to the calculation of the present example, the relation of the negative pressure 13 to the excess pressure 14 is approximately 0.0378. The lower power supply is provided with a suction cup 20 ( FIGS. 1 and 2), which is sucked onto an upper cover when the vacuum limit is reached. In this case, the ejector is switched off by a bistable diaphragm motor and until the negative pressure subsides.

The concertina 16 , which in turn is connected to the inflated body via the Magdeburg scissors 18, serves to change the angle of inclination between the surface of the earth and the mirror axis ( FIG. 3).

The mirror can rotate about an axis perpendicular to the surface of the earth, which runs through an anchor 17 ( FIG. 3). The mirror can be rotated by means of the chassis and the wheels equipped with stepper motors 7 .

Claims (11)

1. A mirror for non-sharp beam, characterized in that its reflecting part consists of individual, overlapping and interchangeable, elastically flexible, reflecting or mirrored pieces of film, which together with a network on which they rest, stretched by negative pressure and in the form of a parabolic cylindrical surface are curved so that a concave surface is formed. 2. A mirror according to claim 1, characterized in that the solar radiation it bundles falls on a circular surface of the cylindrical disk Pos. 9, Fig. 3. 3. A mirror according to claim 1, characterized in that between the overlapping pieces of film viscous, layer impermeable to air. 4. A mirror according to claim 1 and 3, characterized characterized that the network with resting on it Pieces of foil over a against the shock loads resilient framework, with a vacuum in the space rules, has moved. 5. A mirror according to claim 4, characterized in that the main component of the frame is an inflated, torus-related rotating hollow body with a meriadional curve, which is represented by the following equation: where Y and X are Cartesian coordinates, kr and l are constants. 6. A mirror according to claim 5, characterized in that the wall of the inflated body consists of individual, overlapping, elastic and interchangeable pieces of film ( Fig. 6, item 4) with a viscous layer in between, and with a network (item 2 , Fig. 1) is spanned. 7. A mirror according to claims 1 and 4, characterized in that the network carrying the reflecting or reflecting film pieces consists of two parts, the inner part directly with the inflated body, but the outer part via the carrier (item 5, Fig . 1, 2) is connected to it. 8. A mirror according to claims 1 and 7, characterized in that the network, in the form of a two-dimensional chain, made of fixed (item 6) and flexible (item 2) links ( Fig. 5). 9. A mirror according to claim 8, characterized in that the flexible chain links wound from a tensile thread and are twisted rings.   10. Plant for using solar energy, which includes a mirror described in claims 1 to 9, and is characterized in that on the according to claim 2, circular area (pos. 9, Fig. 3) a permeable to the solar spectrum, spiral Pipeline ( Fig. 7, Pos. 10) is located, through which a carbonated saturated salt solution with microalgae (especially Spirulina) is passed. 11. Plant according to claim 10, characterized in that the rest of the solar spectrum not usable by the microalgae is absorbed by the solar cells ( Fig. 7, item 9).