NL1030369C2 - Solar heat absorbing device for e.g. greenhouse, includes reflector which is transparent to visible light but reflects infra=red radiation - Google Patents

Abstract

The device (20) comprises a reflector (30) with a reflective surface (31) for the incoming sun radiation (50) which is designed to be transparent for visible light (52) but reflects infra-red radiation (51). A collector (40) is provided for collecting the reflected infra-red radiation. The reflective surface is curved. Independent claims are also included for the following: Window panel (2) comprising the heat absorbing device and at least one transparent window pane (10); Roof for a building, e.g. greenhouse, comprising a cylindrical roof section and the heat absorbing device, the reflector being integrated into this roof section; Greenhouse with at least one of these window panels or this roof; and Energy generating apparatus, especially for generating electricity, comprising the heat absorbing device, the collector being connected to a machine such as a heat motor or heat circuit used to convert heat into another form of energy.

Description

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Title: Device for collecting infrared heat radiation from solar radiation

The present invention relates to a device for collecting infrared radiation from solar radiation.

Such a device is known in various embodiments. For example, in US 3 957 029 a device is shown which comprises a steel pipe for carrying liquid, which is provided on the outside with a black coating with a high absorption capacity for solar radiation. The steel pipe is arranged in an evacuated glass pipe of which an inner surface is provided with a coating of cadmium stannate. The device also comprises a parabolic reflector, and the system of the glass pipe and the steel pipe is arranged with respect to this reflector such that the steel pipe is located on the focal line of the reflector.

A special property of the cadmium stannate coating is that it is suitable for both transmitting solar radiation and reflecting infrared radiation as it is emitted by the black coating onto the steel pipe during operation of the device. This ensures that during operation of the device the solar radiation is transmitted to the steel pipe practically unhindered, whereby the solar radiation can end up directly on the steel pipe, or can be directed via the reflector on the steel pipe. The black coating on the steel pipe is heated under the influence of the sun's rays. Thereby heat is not only delivered to the liquid that flows through the steel pipe, but also to the space between the steel pipe and the glass pipe. However, this heat radiation is reflected back to the steel pipe through the coating of cadmium stannate that is located on the inner surface of the glass pipe. An advantageous consequence of this is that a loss of solar radiation that is not directly used to heat up the liquid flowing through the steel pipe 30 is contained.

Another device for collecting infrared radiation from sun rays is known from US 4 027 653. This device comprises, just like the device known from US 3 957 029, a steel pipe for carrying liquid, the steel pipe being in an air flow. An empty glass pipe is arranged, and comprises a forward and a return part, the forward part being straight and extending coaxially with respect to the glass pipe, and wherein the returning part is spiral-shaped and around the outgoing part is arranged. The parts of the steel pipe serve to absorb incident solar energy, and are arranged to transfer the absorbed energy to the liquid flowing through the pipe.

The device known from US 4 027 653 also comprises a curved reflector for reflecting infrared radiation, which is arranged in the interior of the glass pipe, and which serves to focus infrared energy on the parts of the steel pipe. A special feature of the reflector is that it is movably arranged, so that an optimum position of the reflector relative to the sun can be obtained at any time of the day, and as much as possible infrared radiation from collected solar radiation through the reflector to the parts of the steel pipe is bounced.

It is in particular an object of the present invention to provide a device which on the one hand is adapted to collect heat radiation from solar radiation in an efficient manner, and which on the other hand is adapted to transmit as much visible light as possible. Such a device is suitable, for example, for being placed on the roof of a greenhouse. The known devices described above are not suitable for such an application, because the design of these devices is not aimed at transmitting as much visible light as possible. In the device known from US 3,957,029, the visible light does not pass the reflective parabola. In a similar manner, with the device known from US 4 027 653, the visible light does not pass the reflector.

A greenhouse with a device for collecting infrared heat radiation from solar radiation is known from US 4,198,953. Only at the place where the device is situated is visible light being admitted into the greenhouse; the remaining part of the greenhouse is opaque. The device comprises a first lens positioned in the greenhouse roof 35 and a second lens disposed above the first lens, the second lens serving to focus and transmit sunlight onto the first lens. Under the first lens a so-called infrared filter trap is arranged, which is adapted to carry a liquid and to heat it up under the influence of the infrared part of the solar radiation, and to allow the 1030369 i (3 visible part of the solar radiation) to pass through The visible part of the solar radiation is collected by a convex curved reflector for scattering and reflecting the light in the greenhouse, as a result, plants arranged in the greenhouse are irradiated only with indirect light.

On the basis of the operation of the greenhouse described above, it is achieved that the energy losses remain limited, while just enough visible light is allowed in to allow the plants arranged in the greenhouse to grow. A drawback of the known greenhouse is that a system of lenses is required to ensure that sufficient light enters the greenhouse, and that lenses are relatively expensive. In addition, the amount of light that is let in this way will be insufficient for many types of plants.

In the case of a greenhouse, only the visible part of the solar radiation is of immediate importance, inter alia because this plays a role in promoting the growth of plants present in the greenhouse. The infrared heat radiation is often not desired in the warmer season. In practice, therefore, it regularly happens that windows of a greenhouse are opened to dissipate excess heat. However, it has an added value to provide the greenhouse with a device that is suitable for collecting infrared heat radiation, so that this part of the solar radiation can be used for a useful application such as the generation of electricity, and which is also suitable for transmitting visible light.

According to the present invention, a device for collecting infrared heat radiation from solar radiation is provided, which is extremely suitable for being used in a greenhouse, which does not alter the fact that many other applications of the device according to the present invention are also possible. The device according to the invention comprises a reflecting body with a reflector surface for receiving the solar radiation, the reflector surface being adapted to transmit visible light and to reflect infrared heat radiation; and a collector for collecting infrared heat radiation reflected from the reflector surface 35.

The device according to the present invention comprises a reflecting body with a reflector surface which is adapted to transmit visible light and to reflect infrared heat radiation. In a practical embodiment, the reflective body comprises, for example, a support made from a transparent plastic film, plate or glass, and which is provided with a spectrally selective coating for transmitting visible light and reflecting infrared heat radiation. In this connection, visible light means solar radiation with a wavelength in a range of approximately 300 nm to approximately 750 nm, while infrared radiation is understood to mean solar radiation with a wavelength in a range of approximately 750 nm to approximately 2500 nm. This infrared radiation is also referred to as near infrared radiation, to distinguish what is known as far infrared radiation that has large wavelengths. In a practical embodiment, the spectrally selective coating comprises a number of dielectric layers with transparent materials, the layers alternately having a high refractive index and a low refractive index. The number of dielectric layers can be between 5 and 200.

In some applications, in addition to the infrared heat radiation, part of the visible light can also be reflected. In this way the light intensity can be kept low, which may be desirable in connection with a greenhouse and crops disposed therein. For example, it is possible to use extra light shielding in clear weather, namely by using another foil, which also reflects a part of the visible light.

When, with an application of the device according to the present invention, solar radiation falls on the reflector surface, the visible light is transmitted, while the infrared radiation is reflected. The device also comprises a collector that serves to collect reflected infrared radiation. In the device according to the present invention, the arrangement of the collector relative to the reflector surface is therefore such that the collector is actually reflected by

30 infrared radiation can be achieved.

Any suitable embodiment is possible for the collector within the scope of the present invention. For example, the collector can include solar cells that directly convert infrared radiation into electricity, which are also known as TPV (thermal photovoltaic) cells. These can be, for example, Germanium cells, or GaSb semiconductor cells. The collector can also be provided in the form of a black plate with which heat is generated, or can be in the form of a vacuum collector. In such cases, the heat can be converted into electricity using a heat engine such as the Stirling engine or an acoustic engine, or through a Ranking process (also known as ORC (organic Rankine)). cycle)). In principle, the collector can transfer heat to any suitable destination, in particular any suitable heat engine and any suitable heat cycle process. The collector is preferably chosen to be as small as possible, so that the incidence of solar radiation in the device according to the present invention is hindered as little as possible by the collector itself.

The reflector surface is preferably curved, so that the reflected infrared radiation is focused. The collector is arranged with great advantage on the focal line of the curved reflector surface, so that an optimum collection of the reflected radiation is achieved. For the sake of completeness, it is noted that the term "focal line" is understood to mean the line on which the focus of the curved reflector surface lies, ie the line on which all radiation reflected by the reflector surface comes together. Since both the reflector and the collector have a certain length in a practical embodiment, it is less appropriate to use the better known term "focal point".

The curved reflector surface can, for example, be parabolic or have the shape of a circle segment. An advantage of using a reflective body with a reflector surface that is shaped as a circle segment over using a reflective body with a parabolic reflector surface 25 is that a reflector surface formed as a circle segment is easier and cheaper to manufacture.

Advantageously, at least one of the reflecting body and the collector is arranged movably. When the reflector surface is parabolic, then preferably both the reflective body and the collector are arranged movably. As a result, it is possible to always position the reflecting body relative to the incident solar radiation such that a normal line of the parabolic reflector surface coincides with the direction of the solar radiation. In this way, the focusing action of the parabolic reflector surface is optimally maintained for various positions of the sun. For the sake of completeness, it is noted that the normal line of the parabolic reflector surface is to be understood to mean an imaginary line which serves as the axis of symmetry of the parabolic shape, and therefore the apex of the parabolic shape perpendicularly 1030369

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6. It is also thereby possible to always position the collector on the focal line of the reflector surface.

When the reflector surface is shaped as a circle segment, it is possible that only the collector is arranged movably. Such a reflector surface has a good focussing effect at different angles of incidence of the sun's rays, and the collector can be arranged relative to the reflector surface in such a way that the collector receives as large an amount of reflected heat radiation as possible. In a preferred embodiment of the device according to the present invention, at least a portion of the collector is covered with a spectral selective filter for transmitting: infrared heat radiation and reflecting visible light.

Using such a spectral selective filter, which in practice is also known as the "cold mirror", it is achieved that the amount of visible light incident directly on the collector and absorbed by the collector is considerably reduced, and the transmission of visible light is maximum.

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The present invention further relates to a window panel with at least one window plate and at least one device according to the present invention. Preferably, a window plate located on the collector side is provided with means for reducing reflection of solar radiation on the window plate so that the amount of infrared heat radiation collected on the collector and the amount of visible light transmitted through the collector window panel is let through be optimal. The shape of a surface of the window plate which is on the side of the collector, which surface is directed away from the collector, can also be adapted to reduce reflection of solar radiation on the window plate. This surface can thus have a zigzag shape.

The present invention also relates to a greenhouse with at least one window panel according to the present invention, and to a device for generating energy, in particular electrical energy, on the basis of collected infrared heat radiation from solar radiation, comprising a device according to the present invention, i.e. a device with a reflecting body and a collector, and a device that is adapted to convert heat into another form of energy, such as a heat engine or a device for carrying out a heat cycle process, the latter being a device connected to the collector of the first-mentioned device.

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The present invention will be further elucidated with reference to the description below. Reference will be made herein to the drawing, in which like reference numerals indicate like or similar parts, and in which: figure 1 is a schematic side view of a window panel according to the present invention, comprising a device with a collector and a reflector with a parabolic reflector surface; Figure 2 is a schematic side view of a window panel according to the present invention, comprising a device with a relatively small collector and a reflector with a reflector surface that is shaped as a semicircle; Figure 3 is a schematic side view of a window panel according to the present invention, comprising a device with a relatively large collector and a reflector with a reflector surface 20 that is shaped as a semicircle; Figure 4 is a schematic perspective view of a window panel according to the present invention, comprising a number of devices with a relatively large collector and a reflector with a reflector surface formed as a semicircle; Figures 5a and 5b are schematic side views of a window panel according to the present invention, comprising a number of devices with a collector and a reflector with a parabolic reflector surface, showing different positions of the reflecting bodies; Figures 6a and 6b are schematic side views of a window panel according to the present invention, comprising a number of devices with a relatively small collector and a reflector with a reflector surface that is shaped as a quarter circle, showing different positions of the collectors; Figure 7 is a schematic perspective view of parts of a window panel according to the present invention, comprising a window plate with pyramid-shaped modules; Figure 8 is a perspective view of a single module of the window plate as shown in Figure 7 and a device disposed therein with a collector and a reflector; Fig. 9 is a perspective view of the device with a collector and a reflector as shown in Fig. 8; and Figure 10 is a schematic side view of a window panel according to the present invention, comprising a roof of a building 5 such as a greenhouse with a cylindrical roof part.

Figure 1 shows a first embodiment of a window panel I according to the present invention, which is particularly suitable for use as a covering for a building such as a greenhouse, and which is adapted to collect infrared heat radiation from solar radiation and visible light from the sun's rays. The window panel 1 comprises a window plate 10 and a device 20 with a reflector 30 and a collector 40. Below, the mutual cohesion of these components of the window panel 1 will be clarified, and the function and operation of these components will also be explained. explained.

The reflector 30 has a parabolic reflector surface 31 that faces the side of the window plate 10 with its concave side, which will hereinafter be referred to as inside 11. The collector 40 is arranged between the reflector 30 and the window plate 10 at a position which substantially corresponds to the position of the focal line 32 of the reflector surface 31.

The window plate 10 is made of a transparent material, for example glass, and is suitable for transmitting both the infrared part and the visible part of solar radiation. For a correct application of the window panel 1, the arrangement of the window panel 1 should be such that the inner side II of the window plate 10 faces away from the sun, and that an opposite side of the window plate 10, which will be indicated below, if outside 12 is facing the sun.

The reflector 30 comprises a support made of glass or plastic. A spectrally selective coating for transmitting visible light and reflecting infrared heat radiation is applied to the support. Such a coating is known per se, and will therefore not be further described.

The collector 40 as shown in Figure 1 comprises a black plate. Black plates are generally known to be particularly suitable for absorbing infrared heat radiation. Preferably the black plate used is a spectrally selective absorber 40 with a high absorption coefficient for short-wave radiation (with a wavelength up to 2500 nm) and a low emission coefficient for heat radiation (long-wave radiation with a wavelength greater than 2500 nm). It is not essential that the collector 40 include a black plate; instead of this plate any other suitable means can be used, for example special TPV (thermal photovoltaic) solar cells which are capable of converting collected heat radiation into electricity. When a black plate is used as collector 40, it is connected to an energy converter for converting heat into another form of energy, in particular electricity. Examples of such an energy converter are a Stirling engine and a Rankine system.

For the window panel 1 to function properly, it is important that the collector 40 is actively cooled, for example with the aid of water. This is the case both when the collector 40 comprises a black plate and when the collector 40 comprises solar cells. For the sake of completeness, it is noted that a device for cooling the collector 40 is not shown in Figure 1 for the sake of clarity.

The operation of the window panel 1 will be described below. Incident sunlight is transmitted through the window plate 10 and for the most part ends up on the reflector surface 31 of the reflector 30. In Figure 1, the incident solar radiation is schematically represented by means of a bundle of arrows 50. As a result of the operation of the spectrally selective coating which is located on the reflector surface 31, infrared heat radiation is reflected, and visible light is transmitted. In Figure 1, the reflected infrared heat radiation is represented by a number of dotted lines 51, and the transmitted visible light is represented by a number of dotted arrows 52.

Due to the parabolic shape of the reflector surface 31, the reflected infrared heat radiation 51 is focused on the focal line 32 of the reflector surface 31. Because the collector 40 is arranged on this focal line 32, it is ensured that the reflected infrared heat radiation 51 is on the collector 40 ends up. Under the influence of the incident heat radiation 51, the heat content of the collector 40 is increased, in other words, heat energy is transferred from the heat radiation 51 to the collector 40. This heat energy is further used, the way in which that happens is related to the nature of the collector 40 and the energy converter to which the collector 40 can be connected.

Figure 1 shows that the collector 40 has an elongated cross-section, with a longitudinal axis of this cross-section extending on the normal line of the parabolic reflector surface 31. Hereby is achieved that at various angles of incidence of the solar radiation 50 the infrared heat radiation 51 reflected from the reflector surface 31 is collected on the collector 40. This is important due to the fact that the position of the sun constantly changes over a day.

The collector 40 is advantageously provided with a spectral selective filter for transmitting infrared heat radiation 51 and reflecting visible light 52. This ensures that the collector 40 absorbs as little visible light 52 as possible.

The aforementioned fact that the window panel 1 is particularly suitable to be used as a greenhouse cover is related to the fact that the window panel 1 can be used to capture heat radiation 51 from solar radiation 50, virtually without the incidence of visible light. 52. In view of the growth of plants grown in a greenhouse, it is important that as much visible light as possible 52 enters the greenhouse. Furthermore, it is favorable that the heat radiation 51, which is certainly more in a warm period than is required for heating the greenhouse, is captured and used for useful purposes such as the generation of electricity.

Figure 2 shows a second embodiment of a window panel 2 according to the present invention, which broadly corresponds to the window panel 1 as shown in figure 1. However, the window panels 1, 2 differ in the shape of the reflector surface 31 from each other . Namely, the window panel 2 as shown in Figure 2 does not have a parabolic reflector surface 31, but a reflector surface 31 that is formed as a circle segment, in particular a semicircle.

A reflector 30 with a reflector surface 31 formed as a circle segment is easier to manufacture than a reflector 30 with a parabolic reflector surface 31. Therefore, it is not necessary that the reflector 30 of the window panel 40 according to the second embodiment comprises a relatively strong carrier .

1030369 to 11

Instead, the reflector 30 may be made, for example, on the basis of a film on which a spectrally selective coating for transmitting visible light 52 and reflecting infrared heat radiation 51 is applied.

The operation of the window panel 2 according to the second embodiment is essentially the same as the operation of the window panel 1 according to the first embodiment.

In the window panel 2 according to the second embodiment, the collector 40 is arranged movably relative to the reflector 30.

More in particular, the collector 40 is movable along a Circular Path, which is shown schematically in Figure 2 by means of a dotted line 45.

At different angles of incidence of the solar radiation 50, the infrared heat radiation 51 reflected from the reflector surface 31 is focused on different lines, which lines are located on a circular path 45. Because the collector 40 is movable along this circular path 45, the position of the collector 40 can be continuously adjusted to the position of the line on which the infrared heat radiation 51 is focused. Hereby is achieved that the collection of the infrared heat radiation 51 by the collector 40 is constantly optimal, for different positions of the sun.

There are various possibilities for determining an optimum position of the collector 40 relative to the reflector surface 31. A practically feasible possibility involves measuring the power delivered by the collector 40, wherein the position at which this power is maximum is determined. Use is made herein of any suitable arrangement for carrying out the measurements, interpreting the measurement results and positioning the collector 40.

An important advantage of the possibility of matching the position of the collector 40 to the current position of the line on which the infrared heat radiation 51 is focused is that the collector 40 can be relatively small. As a result, relatively little visible light 52 is intercepted by the collector 40. If the collector 40 comprises solar cells or similar elements, then the use of relatively few elements will suffice. Since solar cells are relatively expensive, that is an economic advantage.

103 0 3 69 12

Figure 3 shows a third embodiment of a window panel 3 according to the present invention. This window panel 3 broadly corresponds to the window panel 2 as shown in figure 2. An important difference between the window panels 2, 3 is that the window panel 2 according to the second embodiment has a relatively small collector 40, while the window panel 3 according to the third embodiment has a relatively large collector 40. Figure 3 shows a collector 40, the height of which is substantially equal to the radius of the reflector surface 31.

The window panel 3 according to the third embodiment is especially suitable for processing diffuse solar radiation 50, which is involved in cloudy conditions. By using a relatively large collector 40, the infrared heat radiation 51 reflected by the reflector surface 31 is optimally collected. In order to minimize the interception of visible light 52 by the relatively large collector 40, it is particularly advantageous in this embodiment of the window panel if the collector 40 is covered with a spectral selective filter for transmitting infrared heat radiation 51 and reflecting of visible light 20 52.

Within the scope of the present invention, a window panel comprising multiple devices 20 with a reflector 30 and a collector 40 is possible. Embodiments of such a window panel are shown in figures 4, 5a, 5b, 6a and 6b.

Figure 4 shows a fourth embodiment of a window panel 4 according to the present invention. This window panel 4 comprises a number of devices 20 with a reflector 30 and a collector 40. The number of devices 20 can be chosen freely within the scope of the invention.

The window panel 4 according to the fourth embodiment has a modular structure, wherein the reflectors 30 of the devices 20 extend next to each other, and wherein longitudinal axes of the reflector surfaces 31 extend substantially parallel to each other. In the example as shown in Figure 4, the devices 20 comprise a relatively large collector 40 and a reflector 30 with a reflector surface 31 that is formed as a semicircle. This does not alter the fact that the devices 20 could also comprise another collector 40 and / or another reflector 30.

In addition to an outer window plate 10 which is on the side of the collectors 40, the window panel 4 comprises an inner window plate 15 which is on the convex side of the reflectors 30. The devices 20 are, as it were, enclosed between these two window plates 10, 15. The window plates 10, 15 are made of a transparent material such as glass or plastic.

Figures 5a and 5b show a fifth embodiment of a window panel 5 according to the present invention. Like the window panel 4 as shown in Figure 4, this window panel 5 comprises a number of devices 20 with a reflector 30 and a collector 40, which are arranged between an outer window plate 10 and an inner window plate 15. The devices 20 of the window panel 5 according to the fifth embodiment comprise a reflector 30 with a parabolic reflector surface 31.

In the window panel 5 according to the fifth embodiment, the reflectors 30 are arranged rotatably, so that it is possible to have the normal line of the reflector surface 31 make different angles with the window plates 10, 15. The collectors 40 are thereby arranged movably.

Figures 5a and 5b show two of the possible positions of the reflectors 30 and the collectors 40. In both cases 25 the positions of the reflectors 30 are adjusted to the direction of the incident solar radiation, which is shown in figures 5a and 5b by means of one large arrow 50. In particular, the positions of the reflectors 30 are adjusted to the direction of the incident solar radiation 50 such that the normal lines of the reflectors 30 extend substantially in this direction. Furthermore, in both cases the position of each collector 40 is adjusted to the position of the associated reflector 30, the collectors 40 being positioned on the focal line 32 of the reflector surface 31 of the associated reflectors 30. Hereby is achieved that at 35 different positions of the sun the collection of solar radiation 50 is optimal, and that also the collection of infrared heat radiation 51 reflected from the reflector surface 31 of the reflectors 30 is optimal, both at a high position of the sun and the corresponding direction of the solar radiation 50 as schematically shown in figure 5a, as with a low position of the sun and the associated direction of the solar radiation 50 as schematically shown in figure 5b.

For determining an optimum position of the reflectors 30, i.e. a position in which the normal line of the reflectors 30 | 5 coincides with the direction of the solar radiation 50, and of an optimum position of the collectors 40 relative to the reflector surface 31 of the associated reflectors 30, i.e. a position in which the collectors 40 are on the focal line 32 of the associated reflectors 30 positioned, there are 10 different options. As with the window panel 3 according to the third embodiment, it is a real possibility to make power measurements in order to determine a position of the reflectors 30 and a position of the collectors 40 in which the power is optimal.

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Figures 6a and 6b show a sixth embodiment of a window panel 6 according to the present invention. This window panel 6 comprises a number of devices 20 with a reflector 30 and a collector 40, wherein the reflector 30 has a reflector surface 31 that is shaped as a quarter circle, and wherein the collector 40 is relatively small.

An important characteristic of the reflector surface 31 which is formed as a quarter circle is that at different angles of incidence j of the solar radiation, which is shown in Figs. 6a and 6b by means of one large arrow 50, a good focusing of the reflector surface through the reflector surface 31 reflected infrared heat radiation 51 is obtained. As a result, it is possible to generate a good yield of heat energy with the window panel 6, while the position of the reflectors 30 remains fixed, and the position of the collectors 40 relative to the associated reflectors 30 in dependence on the direction of the incident solar radiation 50 years is varied. It is thereby ensured that the collectors 40 are always positioned on the line on which the infrared heat radiation 51 reflected by the reflector surface 31 is focused.

Figure 6a schematically shows the incidence of solar radiation 50 at a high position of the sun, while figure 6b schematically shows the incidence of solar radiation 50 at a low position of the sun. In both situations shown, the position of the reflectors 40 is the same, while the position of the collectors 40 is different from the associated reflectors 30. Because the collectors 40 are constantly positioned on the lines on which the infrared heat radiation 51 is focused, the collectors 40 can be relatively small, without affecting the heat output of the window panel 6. Preferably, the collectors 40 are always held horizontally, so that a maximum view through the window panel 6 is guaranteed.

The optimum position of the collectors 40 relative to the associated reflectors 30 can be determined in any suitable manner 10 for various positions of the sun. Use is preferably made of the aforementioned possibility of making power measurements, wherein a position of the collectors 40 in which the power is optimal is determined.

It will be clear to a person skilled in the art that the scope of the present invention is not limited to the examples discussed above, but that various modifications and modifications thereof are possible without departing from the scope of the invention as defined in the appended claims. conclusions. For example, the reflectors 30 and collectors 40 shown in figures 4, 5a, 5b, 6a and 6b may also have a vertical arrangement instead of a horizontal arrangement.

With the window panels 1-6 shown, various measures can be applied to make the amount of visible light 52 that is being processed as large as possible. It is thus possible for the outside 12 of the window plate 10 of the devices 1-3 as shown in figures 1-3 to be provided with an anti-reflective coating. It is also possible, for example, for the shape of the outside 12 of the window plate 10 to be adjusted to reduce reflections and to catch as much sun radiation as possible. This is for instance the case when the outside 12 of the window plate 10 has a zigzag shape, wherein it is also possible that the entire window plate 10 has a zigzag shape. The aforementioned possibilities apply in a similar manner to the outer window plate 10 of the devices 4-6 as shown in figures 4, 5a, 5b, 6a and 6b.

Other embodiments of the reflector 30 are possible within the scope of the present invention than the embodiments shown with the parabolic reflector surface 31 and the reflector surface 31 formed as a circle segment. For example, it is possible that the reflector 30 is not formed as a whole, but comprises a number of sub-reflectors, each of the sub-reflectors having a curved surface that forms part of the total reflector surface 31.

In the foregoing it has been indicated that the window panels 1-6 according to the present invention are particularly suitable for use in greenhouses. This does not alter the fact that many other applications are conceivable for window panels 1-6. For example, window panels 1-6 are also suitable for use in swimming pools, 10 sports halls and light streets in industrial halls.

In the foregoing, window panels 1-6 have been described which are extremely suitable for use in a greenhouse. The window panels 1-6 comprise at least one window plate 10 and at least one device 20 with a reflector 30 and a collector 40.

The reflector 30 has a curved reflector surface 31 which is provided with a spectrally selective coating for transmitting visible light 52 and reflecting infrared heat radiation 51. Incoming sun radiation 50 is transmitted through the window plate 10 to the reflector 30. The infrared red part 51 of the solar radiation 50 is reflected by the reflector surface 31, and the visible part 52 of the solar radiation 50 is transmitted by the reflector 30. When the collector 40 is on the focal line 32 of the reflector surface 31, the collection of infrared heat radiation 51 by the collector 40 is optimal. Therefore, at least one of the reflector 30 and the collector 40 is preferably arranged movably, so that at various positions of the sun it can be ensured that the collector 40 extends on the line on which the infrared radiation 51 reflected by the reflector surface 31 is focused. .

Figure 7 shows parts of a seventh embodiment of a window panel 7 according to the present invention, namely a window plate 10 and a number of reflectors 30.

The window plate 10 of the window panel 7 comprises pyramid-shaped modules 13. In the example shown, the basis of the pyramid shape is a hexagon. The reflectors 30 are arranged distributed over the window plate 10, wherein in each module 13 a device 20 with one reflector 30 and an associated collector 40 is arranged. A single module 13 with a device 1 03 0 3 69 17 20 arranged therein with a reflector 30 and a collector 40 is shown in Figure 8, while the device 20 with the reflector 30 and the collector 40 is shown separately in Figure 9. For each reflector 30 holds that it has a parabolic reflector surface 31 that faces the inner side 11 of the window plate 10 with its concave side, and that it comprises a foil that reflects near infrared heat radiation 51 and at the same time is transparent to visible light 52 For each collector 40, it holds that it is preferably arranged to convert collected reflected heat radiation 51 into electrical energy.

The reflector 30 of each device 20 is arranged movably. In particular, during operation, the height of the reflector 30 and the angular displacement relative to a vertical axis are continuously adjusted to the position of the sun, the aim being to receive as much infrared heat radiation as possible 51.

For the sake of completeness, it is noted that the height of the reflector 30 is also indicated by the term "elevation", and that the angle at which the reflector 30 is located is also indicated by the term "azimuth".

In particular, the device 20 has a coupling element 71 which serves to connect the device 20 to the window plate 10. In the example shown, the coupling element 71 is annular, and the coupling element 71 is adapted to be placed in a highest point of a module 13. be fixed. The device 20 also comprises a central shaft 72 which, viewed from the coupling element 71, extends downwards in the vertical direction. The collector 40 is attached to the lower end of the central shaft 72. The reflector 30 is suspended from the central axis 72 via an arcuate suspension element 73.

For the purpose of adjusting an angular rotation of the reflector 30 about a vertical axis ("azimuth"), a first driving member 74 is provided for rotating the central axis 72. For the purpose of adjusting an angular rotation of the reflector 30 about a horizontal axis ("elevation"), a cable construction 75 is provided. This cable construction 75 comprises a cable 76 which is attached to the reflector 30 at two points 77. The cable 76 runs over a second drive member 78, which is located on the central shaft 72, and which is adapted to engage on the cable 76, and which is also adapted to feed through the cable 76. When the second actuator 78 is activated to feed the cable 76 over a certain length, the reflector 30 is lifted on one side and lowered on another side. In this way, an angular rotation of the reflector 30 about a horizontal axis is set. For controlling the actuators 74, 78 on the basis of the position of the sun, any suitable controller, processor or the like can be used, wherein the determination of the positions of the reflector 30 to be set can take place in any arbitrary manner.

During operation, infrared heat radiation 51 reflected from the reflector surface 31 of the reflector 30 remains focused on the associated collector 40. A factor that plays an important role here is the fact that the window plate 10 comprises the pyramid-shaped modules 13. Because these modules 13 comprise a number of triangular standing sides which extend in mutually different directions, it is possible to follow the sun with the reflector 30 for a whole day.

Figure 10 shows an eighth embodiment of a window panel 8 according to the present invention, comprising a hood 60 of a building such as a greenhouse with a cylindrical roof part 61. The cylindrical roof part 61 is made of cylindrical curved sheet material, the sheet being provided of a coating capable of reflecting infrared heat radiation 51 and transmitting visible light 52 as much as possible. Arranged on the focal line 32 of the cylindrical roof part 61 is a collector 40 for collecting infrared heat radiation 51 reflected from the roof part 61. This collector 40 is preferably adapted to convert the heat radiation 51 into electrical energy.

In order to ensure optimum collection of the infrared heat radiation 51, the position of the collector 40 is adjustable. For this purpose a suitable position control is used, which is adapted to adjust the position of the collector 40 to the position of sun, whereby the collector 40 is constantly brought to a place where most of the reflected heat radiation 51 can be collected.

In the eighth embodiment of the window panel 8 according to the present invention, the reflector 30 of the device 20 with the reflector 30 and the collector 40 is formed by the cylindrical roof part 61. An advantage of this window panel 8 is therefore that it has a minimum of parts which does not require a separate reflector 30 because it is integrated in the cap 60.

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Claims (21)

Apparatus (20) for collecting infrared heat radiation (51) from solar radiation (50), comprising: - a reflecting body (30) with a reflector surface (31) for collecting the solar radiation (50), the reflector Surface (31) is adapted to transmit visible light (52) and to reflect infrared heat radiation (51); and - a collector (40) for receiving infrared heat radiation (51) reflected from the reflector surface (31). The device (20) of claim 1, wherein the reflector surface (31) is curved. The device (20) of claim 2, wherein the collector (40) is arranged on the focal line (32) of the reflector surface (31). 15 The device (20) according to any of claims 1-3, wherein at least one of the reflective body (30) and the collector (40) is arranged movably. The device (20) according to claim 4, wherein the reflector surface (31) is parabolic, the reflective body (30) and the collector (40) being arranged movably. The device (20) according to claim 4, wherein the reflector surface (31) is formed as a circle segment, the reflective body (30) being fixedly arranged, and wherein the collector (40) is movably arranged. Device (20) according to any of claims 1-6, wherein the reflector surface (31) is provided with a spectrally selective coating suitable for transmitting visible light (52) and reflecting infrared heat radiation (51). 8. Device (20) according to claim 7, wherein the spectrally selective coating comprises a number of dielectric layers with transparent materials, the layers alternately having a high refractive index and a low refractive index. 1030369 The device (20) according to any of claims 1-8, wherein at least a portion of the collector (40) is covered with a spectral selective filter for transmitting infrared heat radiation (51) and reflecting visible light (52) ). 5 The device (20) according to any of claims 1-9, wherein the collector (40) comprises thermal photovoltaic cells, such as Germanium cells or GaSb semiconductor cells. Device (20) according to any of claims 1-9, wherein the collector (40) is designed as a vacuum collector. 12. Window panel (1, 2, 3, 4, 5, 6, 7), comprising at least one transparent window plate (10) and at least one device (20) according to any of claims 1-11. A window panel (4, 5, 6) according to claim 12, comprising at least two devices (20), wherein longitudinal axes of the reflector surfaces (31) of the reflecting bodies (30) of the devices (20) are substantially extend parallel to each other. 14. Window panel (4, 5, 6) according to claim 12 or 13, comprising two transparent window plates (10, 15), wherein the at least one device (20) is positioned between the two window plates (10, 15). A window panel (7) according to claim 12, wherein a window plate (10) located on the collector (40) side comprises pyramid-shaped modules (13), and wherein each module (13) has a reflective body (30). ) and a collector (40). 16. Window panel (1, 2, 3, 4, 5, 6, 7) according to any of claims 12-15, wherein a window plate (10) which is located on the side of the collector (40) is provided with means for reducing reflection of solar radiation (50) on the window plate (10). The window panel (1, 2, 3, 4, 5, 6, 7) according to any of claims 40 to 16, wherein the shape of a surface (12) of a 103 0 3 69 window plate (10) adhering to the side of the collector (40), which surface (12) is directed away from the collector (40), is adapted to reduce reflection of solar radiation (50) on the window plate (10). 5 A hood (60) for a building such as a greenhouse, comprising a cylindrical roof part (61) and a device (20) according to any of claims 1-11, wherein the reflector (30) of the device (20) is integrated in the roof part (61). 10 years A greenhouse, comprising at least one window panel (1, 2, 3, 4, 5, 6, 7) according to any of claims 12-17. A greenhouse, comprising a hood (60) according to claim 18., 15 Device for generating energy, in particular electrical energy, based on collected infrared heat radiation (51) from solar radiation (50), comprising a device (20) according to any of claims 1-11 and a device that is 20 arranged to convert heat into another form of energy, such as a heat engine or a device for carrying out a heat cycle, the latter device being connected to the collector (40) of the former device (20). 1 03 0 3 69