NL1037574C2 - Energy conversion system. - Google Patents

Description

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Energy conversion system

TECHNICAL FIELD OF THE INVENTION

The present invention is in the field of energy conversion. The 5 present invention relates to an energy conversion apparatus, comprising a system for bundling radiation, means for converting radiation into heat and into electricity, and wherein the apparatus optionally comprises one or more of a system for energy transport, a transparent protection, an encasement system, a Source Tracking system, an energy storage system, and a buffer system. It further relates to a 10 construction element comprising the energy conversion apparatus, and to a method of energy conversion.

BACKGROUND OF THE INVENTION

In the field of energy conversion PV-systems are known. These systems generally use a PN-junction to convert solar energy to electricity.

15 A disadvantage of such a system is that the conversion is not very efficient, typically, for Si-solar cells, limited to 15%. Even using very advanced PV-cells, such as GaAs cells, the conversion is only about 25%. Inherently these systems are limited in their conversion.

Further these systems are expensive to manufacture. Typically 20 production costs are nowadays in the order of 1.5€/Wpeak. As such, the return on investment takes in the order of 10-15 years, and only if governments subsidizes these kind of systems.

Also these kinds of systems are visually unattractive.

Further, solar boilers are known. Therein water is heated by solar 25 radiation. The preheated water is then typically used for showering and possibly for central heating.

Also these systems are expensive to manufacture, not very efficient, and visually unattractive.

Further, parabolic trough power plants are known, using a curved 30 trough which reflects the direct solar radiation onto a pipe containing a fluid (also called a receiver, absorber or collector) running over the length of the trough, above the reflectors. The trough is parabolic in one direction and straight in the other. For change of position of the sun perpendicular to the receiver, the trough tilts so that the direct radiation remains focused on the receiver. However, a change of position 1037574

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2 of the sun parallel to the trough does not require adjustment of the mirrors, since the light is simply concentrated elsewhere on the receiver. Thus the trough design does not require tracking on a second axis.

The receiver may be enclosed in a glass vacuum chamber. The 5 vacuum significantly reduces convective heat loss.

A fluid (also called heat transfer fluid) passes through the receiver and becomes very hot. Common fluids are synthetic oil, molten salt and pressurized steam. The fluid containing the heat is transported to a heat engine where only a third (33%) of the heat is converted to electricity. The remainder is waste heat, and 10 can not be used further. Further, these systems rely on very sunny environments, in order to provide the conversion efficiency. Also these systems can not be applied on e.g. roofs of houses, and they are relatively expensive.

Thus there still is a need for improved energy conversion system, which system overcomes one or more of the above disadvantages, while at the 15 same time not jeopardizing other favourable aspects of energy conversion.

SUMMARY OF THE INVENTION

The present invention relates to an apparatus for conversion of radiation, wherein the radiation is preferably radiation emitted by the sun or reflected by the moon, characterized in that the apparatus is fixed on a surface, where the 20 apparatus it suited for receiving the radiation, wherein the apparatus comprises a system for bundling the radiation, means for converting 50% or more of radiation into heat and into electricity, and wherein the apparatus optionally comprises one or more of a system for energy transport, a transparent protection, an encasement system, a source tracking system, an energy storage system, and a buffer system.

25 The present apparatus as such is fixed on a surface and can rotate along a longitudinal axis thereof, i.e. rotate clockwise or anti-clockwise around said axis.

The present apparatus converts radiation into both heat and electricity, which heat and electricity are in a form to be used further, i.e reusable, 30 such as for heating and for providing electricity to e.g. household appliances. The amount of waste heat generated is less than 50%, or put in other words, the efficiency of the total system is more than 50%. Waste heat refers to heat produced by machines, electrical equipment and industrial processes for which no useful application is found, and is regarded as a waste by-product. When produced by 3 humans, or by human activities, it is a component of anthropogenic heat, which additionally includes unintentional heat leakage, such as from space heating. Thus the present invention is aimed at optimizing radiation conversion. In preferred embodiments the efficiency of the total system is more than 75%, in some cases 5 even more than 80%.

Various elements of the present apparatus as well as advantages will be discussed below in detail.

DETAILED DESCRIPTION OF THE INVENTION

In a first aspect the present invention relates to an apparatus for 10 conversion of radiation, wherein the radiation is preferably radiation emitted by the sun or reflected by the moon, characterized in that it comprises a system for energy transport, which system comprises a. a container for liquid transport, preferably a tube-like container, b. an insulation essentially surrounding the container having an 15 inner surface, c. optionally a cavity in between the insulation and the container, wherein the insulation comprises an opening to allow entrance of a bundle of radiation, preferably a non-parallel bundle of radiation, preferably an opening extending substantially over a length of the container, which opening is optionally 20 covered by a material transparent for the radiation, and wherein the opening is smaller than 50% of the total area of the inner surface of the insulation, preferably smaller than 30% thereof, even more preferably smaller than 20% thereof, even more preferably smaller than 15% thereof, even more preferably smaller than 10% thereof, most preferably smaller than 5% thereof.

25 The present apparatus is meant to convert radiation. In principle it may convert any type of radiation capable of heating a liquid, however its primary application is at present thought to be aimed at conversion of solar radiation or reflected solar radiation, such as from the moon. So typically radiation will comprise visible light, UV-light, IR-light etc. In a preferred embodiment the present apparatus 30 is for converting direct or reflected solar radiation.

The radiation is converted, in first instance into heat. The converted radiation, or the energy content thereof, is typically obtained in a location where it is not used, or where it is in a form not required, such as in the form of heat where in this example electric energy is required. Typically also the converted radiation needs 4 to be densified for transport, such as by converting it into electricity. Therefore the present apparatus comprises an energy transport system.

Such an energy transport system comprises a container for liquid transport. The container extends typically substantially over a length of the 5 apparatus. The container typically has a length being (much) larger than a width or height thereof. The container may have any shape, such as cubic, or have a cross-section being essentially square like, elliptical, rectangular, multigonal, such as hexagonal, or circular. It is preferably a tube-like container, as such a tube-like container offers a relative small surface/volume ratio, and is further easy to 10 manufacture. The container is made of a material that can withstand pressure to a certain extent, is relatively light, so that it can be handled easily and does not pose any unnecessary restrictions to a construction where the apparatus is placed. Further, the container is preferably of a dark colour, such as black, in order to absorb as much radiation as possible. Typical materials for the container are 15 polymers, metals, like alumina, etc. Further, the material should be durable over the life time of the apparatus.

With the term "liquid" any material is meant that at operating conditions, i.e. between -50 C and 500 C, is liquid, that is can flow, such as a gas, a liquid, a vapor etc. Important is that the liquid can flow and thereby transfer heat. 20 Water, comprising additives to lower the melting point and increase the boiling point thereof, such as a salt, is a preferred liquid. The liquid may be brought under pressure.

The energy transport system comprises an insulation essentially surrounding the container. This is an important feature, as it prevents leakage of 25 secondary radiation, such as radiation emitted by a so-called black body. The prior art has neglected isolation of containers fully or to a large extent. Typically the insulation has an inner surface, directed towards the container, and an outer surface, directed to the environment. The insulation should be thick enough and of a material or construction to prevent leakage of radiation emitted by the container. It 30 should also be durable, preferably be resistant to environmental conditions, such as UV-radiation, and operating conditions. In a preferred embodiment the insulation comprises an inner part and an outer part, wherein the inner part comprises a double walled pre-form, wherein the space in between the walls is filled with a medium with a low thermal conductivity (W/mK @ 293K), preferably lower or equal 5 to the thermal conductivity of air, such as vacuum or a noble gas, and wherein the outer part comprises one or more insulating components preferably selected from glass wool, PUR-foam, cellular plastic, silica aerogel, and glass fibre applications.

The insulation comprises an opening. The opening allows for 5 radiation to enter the insulation and transfer its energy to the container.

In a preferred embodiment the opening is located substantially over a length of the container. As such the amount of radiation that can enter the insulation and reach the container is increased.

In a preferred embodiment the opening is large enough to allow 10 entrance of a bundle of radiation, preferably a non-parallel bundle of radiation. Preferably a substantial part of a bundle of radiation formed by the present apparatus reaches the container, more preferably almost all of the radiation reaches the container, such as more than 90%, preferably more than 95%, such as more than 99%. The radiation reaching the container heats up the liquid therein. 15 Preferably the container allows for pressure built up within the container, such as up to pressures of at least a few times atmospheric pressure (i.e. up to 10000 kPa depending on the material). As such heat can be transferred or transported effectively and efficiently.

It is noted that in a preferred embodiment the heat is transported, 20 e g. by a tube system, to a turbine and to a heater, such as a central heating system in a home, in a building, in a green house, etc. As such, heat can also be stored, e.g. by pumping it into the earth, to be extracted at a later time when required.

The opening is optionally covered by a material transparent for the radiation. As such the container is protected from the environment. The covering 25 may be formed of glass, a transparent plastic, such as polycarbonate, and is preferably durable and light.

In a preferred embodiment the opening is smaller than 50% of the total area of the inner surface of the insulation, preferably smaller than 30% thereof, even more preferably smaller than 20% thereof, even more preferably smaller than 30 15% thereof, even more preferably smaller than 10% thereof, most preferably smaller than 5% thereof. As such most of the radiation can enter and is kept inside the insulation.

In a further preferred embodiment the bundle of radiation is concentrated as much as possible. A way to achieve this goal is bundle the radiation 6 entering the apparatus, thereby providing a very small concentrated bundle with a relatively small cross-sectional area, such that this cross-sectional area is smaller or equal to the opening of the insulation. An other way is to focus the bundle of radiation, such that a focal point thereof, or focus area thereof, is substantially 5 inside the insulation. In the latter case also the cross-sectional area of the bundle close to the opening of the insulation is as small as possible. Also a combination of the two above ways of bundling is possible. Assuming a perfect focus system a cross-sectional area of a bundle may be a point, or in the present case typically a line. Thus the opening could in such a case be extremely small, such as much less 10 than 1% of the total area of the insulation. However, due to practical reasons, such as tolerances in mass-production of the present system, an opening of around 1% is preferred. Further, due to a possible large concentration of radiation the opening may need to be a bit wider, in order to prevent burning thereof, such as 2%. It is noted that as the present apparatus relates to a system having a certain length and 15 not to a substantially circular system, the system typically has a focal line or line along which the radiation is bundled. Therefore, if applicable, the term focus point throughout this application may also relate to a focal line. As such the amount of radiation of the container, being a hot body emitting radiation, exiting the insulation is minimal. Preferably most or all of the radiation of the container is kept inside the 20 insulation. Preferably more than 50% of the radiation of the container is kept inside, more preferably 75%, even more preferably more than 90%, and móst preferably more than 95%, such as more than 98%. As a consequence the opening in the insulation is preferably as small as possible. By having the opening as small as possible also convection losses are kept to a minimum level. In a preferred 25 embodiment the inside of the insulation and/or the insulation may be of a material that reflects the radiation of the container to a large extent, such as being a metal, or a thin reflective coating. Also the outside of the insulation may comprise a reflective material, e.g. in order to prevent burning.

The energy transport system optionally comprises a cavity in 30 between the insulation and the container. Such a cavity functions as a further insulation, and allows for radiation to enter the insulation and transfer its energy to the container.

In a preferred embodiment the apparatus according to the invention comprises a container comprising an entrance substantially aligned with the opening 7 of the insulation, wherein the container comprises two or three substantially concentric walls, wherein the container preferably is a pre-form, wherein a space in between the walls is filled with the liquid, which liquid preferably has a high specific heat capacity (kJ/kgK), and/or which liquid has a melting point below - 10 C, 5 preferably below -50 C, and a boiling point above 50 C, preferably above 90 C.

The entrance of the container is substantially aligned with the opening of the insulation in order to maximize the amount of radiation entering the inner part of the container. Thereby the entrance, and the opening of the insulation, can be kept as small as possible, to comparable dimensions. The inner part of the 10 container is formed by the double-walls or three walls of the container. These walls are substantially oriented concentric with respect to each other. The double walls, or three walls respectively, enclose a space, which space is filled with a liquid for energy transport towards the present energy converter.

In a preferred embodiment the container is formed of three walls, 15 enclosing an inner and an outer space, each space in operation being filled with liquid. In operation in the inner space liquid flows in a first direction, whereas in the outer space liquid flows in a counter current direction. As such energy contained in the radiation entering the insulation is transferred efficiently from the liquid in the inner space towards the liquid in the outer space, and subsequently to the energy 20 converter.

In a preferred embodiment the inner part of the container substantially encloses a cavity, wherein the radiation enters. As such radiation is captured inside the container to a large extent, preferably to more than 75%, such as more than 90%, preferably more than 95%, such as more than 98%.

25 In a preferred embodiment the inner wall of the container comprises of a radiation absorbing material, is formed of a radiation absorbing material, is coloured, such as with pigment, such as being black, or a combination thereof. The radiation absorbing material is preferably capable of absorbing the radiation entering the apparatus as well as radiation emitted by the container.

30 The container is preferably a pre-form, for instance made my moulding or extrusion. Pre-forms can be made very precise and at relatively low costs. The container can be made of a suitable material, such as plastic, a suited polymer, glass, or a combination thereof.

The specific heat capacity of the liquid is preferably high, in order to 8 transport energy efficiently. Further, it is preferred that the liquid remains liquid or gas at operating conditions. In order to be operable at environmental conditions the liquid preferably does not freeze, i.e. has a freezing point lower than -50 C. Further, as the intensity of radiation can become very high, the boiling point of the liquid is 5 preferably also high, i.e. larger than 90 C, such as larger than 110 C.

In a preferred embodiment the apparatus further comprises a buffer system. The buffer system can e.g. be filled if environmental temperatures are so low that the liquid runs a risk of solidifying in the container. Even further, the buffer system may be filled if pressure and/or temperature of the liquid in the container 10 become too high. The buffer may be in the form of a secondary container, preferably being isolated. The buffer system and/or apparatus may comprise a pressure valve.

In a second aspect the present invention relates to an apparatus for conversion of radiation according to the invention, comprising a transparent protection, which protection comprises a curved element having a certain refractive 15 index, wherein an outer curve of the element is different from an inner curve of the element, such that a parallel bundle of radiation entering the protection at the outer curve thereof at a certain angle 0 exits the inner curve of the protection substantially parallel to the angle 6.

The term "transparent" is used in the present invention to indicate 20 that radiation in general, and solar radiation in particular, is substantially not hindered. That is substantially all of the radiation passes trough mirror, such as more than 90%. A transparent material or element therefore allows radiation to pass through, at least to a large extent.

Preferably the protection is made of a light material, such as a 25 polymer material, such as polycarbonate and polymethyl(meth)acrylate. Glass or a similar material is also suited. The material is further preferably durable for environmental influences, is preferably also strong enough to withstand hail, even large hail stones, preferably also durable for radiation, such as UV-radiation, and lasts preferably over the life time of the protection, or longer if the protection is 30 recycled, such as twice the life time.

As the radiation emitting object, i.e. the sun or the moon, is relatively located far away, radiation will be received as a parallel bundle. In order to obtain optimal efficiency of conversion of radiation the bundle of radiation needs to be focussed and/or densified or concentrated. Therefore in this embodiment the 9 parallel bundle preferably enters the internal part of present apparatus in parallel. Thus the protection is formed such that an outer curve of an element thereof is different from an inner curve thereof, such that a parallel bundle of radiation entering the outer curve of the element exits the inner curve of the element substantially 5 parallel. Thus, a parallel bundle entering the apparatus at a certain angle 6 remains parallel inside the protection under substantially the same angle 0. Of course, relative to the outer curve of the element an angle of entrance (or incidence) varies over the outer curve. Similar, relative to the inner curve of the element an angle of refraction varies over the inner curve.

10 In this application the term "curved" is meant to refer to a substantially convex or concave surface, which surface taken as a hole is circular-like or elliptical-like. Thereon functional undulations may appear, as is further detailed. Undulations may appear on the outer curve, on the inner curve, or on both. A preferred embodiment comprises undulations on the inner curve in view 15 of cleaning the outer curve.

In a preferred embodiment the outer curve of the element is being substantially circular and an inner curve is being elliptical-like, or vice versa. Also two elliptical like shapes, being different from each other are possible. Further, two elliptical shapes, or two circular shapes, having an off-set with respect to the or a 20 center of said shapes, are possible.

As a consequence a thickness of the protection material varies, being thinner at the edges thereof relative to the center thereof.

An advantage of the present protection is that the efficiency of the present apparatus is increased by some 20%, or in other words, losses are reduces 25 by some 20%.

A further advantage is that a curved protection offers more strength. It is expected that e.g. to climate change intensity of storms, frequency of hail and size of hail, increase. Therefore preferably a strong protection is provided, in order to minimize damage and extent life time of the present apparatus.

30 In a third aspect the present invention relates to an apparatus for conversion of radiation according to the invention, comprising a. a system for energy transport according to the present invention, comprising a container and an insulation, b. a system for bundling radiation comprising one or more parabolic 10 mirrors and/or one or more lens systems, and c. wherein the liquid in the container absorbs energy from the system for bundling radiation.

As mentioned above the bundle of radiation may be bundled. In a 5 preferred embodiment bundled radiation is directed towards the container, in order to absorb the energy thereof. Further the absorbed energy is transported by the present energy transport system. Preferably a focus point of the system for bundling radiation is located close to the container or in a preferred embodiment close to the center of the container, i.e. at a distance thereof of less than 0.5 times a diameter of 10 the container, more preferably at less than 0.2 times, more preferably less than 0.1 times of a diameter. Preferably the focus point is located inside the insulation, more precisely inside a hollow space in the insulation.

The system for bundling radiation comprises one or more concave or convex parabolic mirrors and/or one or more lens systems. Preferably the number 15 of mirrors and lenses is as small as possible, in order to reduce costs thereof and in order the reduce energy yield losses thereof. A system comprising one lens, or one concave and one convex parabolic mirror is preferred. The concave parabolic mirror is also referred to as a trough mirror. The system is preferably designed to bundle substantially all, or at least 90%, preferably 95%, most preferably 99% of the 20 radiation entering the apparatus, and further to direct substantially all of the bundled radiation towards the container in order to absorb the energy thereof. As such the energy conversion yield, that is the ratio of energy converted and energy in the form of radiation entering, is as high as possible, i.e. higher than 80%, preferably higher than 90%.

25 In a preferred embodiment the present apparatus for conversion of radiation comprises a concave parabolic mirror which is substantially directed towards the sun or moon for bundling radiation, wherein a focus area of the bundled radiation is substantially inside the insulation.

As mentioned above, the present focus system comprises a focal 30 line. The concave parabolic mirror has a central plane of symmetry, on which plane the focus line thereof is located, which central plane further comprises a vector perpendicular to the mirror, which vector is preferably oriented substantially parallel to azimuth angle of the bundle of radiation entering, that is having a deviation of less than 10 degrees, preferably less than 5 degrees, most preferably less than 1 11 degree, such as 0.1 degree. The present invention provides a system which allows for a deviation close to a tolerance of the manufacturer of the present system, i.e. virtually 0. The deviation is taken relative to an optimal orientation, i.e. perfectly aligned and the above vector parallel to the azimuth angle of the bundle of radiation.

5 As the present apparatus is typically fixed to a surface, such as a roof, it can not correct for the altitude of radiation entering. The above also holds if the present system comprises a lens system, such as a convex (positive) lens.

As mentioned above, a focus area of the bundled radiation is substantially inside the insulation.

10 As a consequence the present system provides for yields of absorption of radiation entering of more than 80%, typically more than 90%, such as 95% or even 99%. Such is much better than prior art systems, typically having a yield of (much) less than 50%, such as the through system.

In a further preferred embodiment the system further comprises a 15 convex parabolic mirror, wherein the convex mirror bundles radiation reflected from the concave mirror. The size of the second mirror is such that substantially all of the radiation bundled by the concave mirror is further bundled by the concave mirror. On the other hand, the convex mirror is as small as possible, as it hinders entrance of radiation.

20 Typically mirrors are moulded and made of a light material. Further, in a preferred embodiment the first concave mirror forms an integral part of a housing or encasement of the present apparatus. By moulding almost perfect concave mirrors, as well as lenses, can be made. The mirror may have a reflective coating, or may be made of a reflecting material, such as a metal. The material 25 and/or the construction of the mirror must be durable to environmental influences, such as weathering, aging, UV-radiation etc.

In a preferred embodiment the present apparatus for conversion of radiation comprises a transparent protection such that the protection functions as a lens.

30 As such the protection has also a function of bundling radiation entering the system. By combining various functions the present apparatus is easier to manufacture, e.g. in less steps and comprising less elements, and therefore costs are reduced, and above all efficiency of conversion is increased. Preferably radiation is reflected as less as possible, in order to reduce yield losses.

12

In a further preferred embodiment the protection comprises two or more transparent elements, such that the protection functions as a lens. An outer element can e.g. be made of glass, an inner element can e.g. be made of polymer, whereas an optional intermediate element can be air, water, a polymer etc. In a 5 preferred embodiment glass used for elements of the present apparatus exposed to environmental circumstances may be reinforced glass, being able to withstand impact of e.g. hail.

In a further preferred embodiment the protection comprises a curved element having a certain refractive index, wherein the protection has a 10 thickness varying stepwise over the curve thereof such that a minimal thickness dmln of the protection is larger than 0.1 * a maximal thickness dmax, such that a parallel bundle of radiation entering the protection at an outer curve thereof exits an inner curve being focussed. In a most preferred embodiment the minimal thickness dmin is almost equal to the maximal thickness dmax, that is from 0.90-0.99 * the maximal 15 thickness dmax. As such the amount of material used for the protection is minimal, whereas the lens function thereof still is acceptable. It is noted that the thickness relates to a radial thickness of the protection.

In designing the above protection applicant has taken into account reflection coefficients, transmission coefficients, and refractive index (n) of the 20 curved element and other material involved, such as air. Further, the form and thickness of the curved element have been optimized in terms of efficiency with respect to incidence angle of the radiation and refraction angle, taken relative to a normal (line) at a certain location (x,y,z) of the curved element. The curved element is designed such that radiation entering is focused to a focus point (or line). Even 25 further, in view of production and functional tolerance and costs, the thickness of the material may on the one hand not vary to much, that is a minimal thickness is preferably not much smaller than a maximal thickness, and further the minimal thickness is large enough to provide protection, as indicated above.

In a certain aspect the above protection relates to a coaxial lens. In 30 a preferred embodiment the protection relates to a lens which in certain aspects may be regarded as functioning as a curved Fresnel lens.

The efficiency, in terms of percentage of radiation entering being bundled, of the above lens is larger than 90%, typically larger than 92%, such as larger than 94%, mainly depending on the curvature thereof. It is noted that mainly 13 losses at the edges of the present apparatus occur.

The minimal thickness dmin of the protection is preferably in the order of 3-10 mm, depending on e.g. the material used, optical properties thereof, and strength thereof. It is preferably larger than 0.1 * a maximal thickness dmax being 5 preferably in the order of 3.1-25 mm. The maximal thickness is preferably not too large in view of weight of the protection. The minimal thickness is preferably large enough to provide strength to the protection.

In a fourth aspect the present invention relates to an apparatus for conversion of radiation according to the invention, comprises an encasement system 10 for containing the apparatus and elements thereof, comprising one or more of a cleaning system, such as a lens cleaning system, a sealing for the encasement, fixing means for the encasement system, means for rotating the apparatus around a longitudinal axis thereof substantially in the direction of the sun, at least one reflecting internal surface, and a support system.

15 The encasement system fixes the present apparatus to a surface.

The surface may be a roof, a wall, and the encasement system may be placed inside or outside. On the one hand the apparatus needs to be firmly attached to a surface if place outside, in order to withstand (strong) winds, storms etc. In a further aspect the apparatus preferably still is able to rotate around an axis thereof, in order to be 20 oriented towards the azimuth angle of the sun or moon. Preferably the rotation can be established using a relatively small force, such as force provided by a means for rotating, such as a servo-drive. Preferably the encasement also comprises a cleaning system. Preferably such a cleaning system is located on one or both (longitudinal) sides of the containment. An example is a scraper, such as a metal 25 scraper, which is firmly attached against the encasement. By rotating the encasement the encasement is cleaned at the same time. Preferably a cleaning system also cleans the lens and/or protection, if present. Thereby the clarity of the lens and/or protection is maintained during use.

If the encasement is used outside, preferably the encasement also 30 comprises a sealing system, or is a sealing system, thereby keeping moisture, such as rain, outside.

Preferably the encasement comprises fixing means for the encasement system, thereby fixing the encasement firmly to a surface.

In order the rotate the apparatus towards the sun it preferably 14 comprises means for rotating the apparatus around a longitudinal axis thereof substantially in the direction of the azimuth angle of the sun. Thereby the amount of radiation entering the apparatus is optimized, that is as the apparatus typically is fixed in a two-dimensional plane, which plane is per definition almost never located 5 perpendicular with respect to radiation emitted by e.g. the sun, optimization is limited to orienting the apparatus around an axis within said plane towards the sun. Such means can be a servo-motor, being attached to a simple bar-system, which bar-system is on its turn attached to the apparatus. As an alternative the servo-motor is attached to a belt driving a wheel, the wheel being attached to the 10 apparatus. One belt may be attached to a series of apparatuses. Preferably one servo-motor is attached to more than one apparatus, such as to two, five, or ten apparatuses, or to a complete construction element.

Preferably the present apparatus comprises an encasement having at least one reflecting internal surface, preferably at least two reflecting internal 15 surfaces. Thereby radiation not directly focussed towards the present container is reflected towards said container. Typically this radiation is a consequence of the altitude of e.g. the sun with respect to the present apparatus, which altitude is larger or smaller than an angle of the surface, with respect to the horizontal plane of the earth, the present apparatus is attached to, such as the angle of a roof with respect 20 to the surface of the earth. The at least one reflecting surface is therefore preferably located at one or both longitudinal ends of the present apparatus, which ends may be regarded as bottom and top part. The reflecting surface may be a metal (layer) or reflective coating.

Preferably the present apparatus comprises a support for attaching 25 the apparatus to a surface, such as a wall or roof. Preferably the support comprises means for fixing it to the surface and to the apparatus, such as screws or clamps, respectively. The support may also be glued.

In a fifth aspect the present invention relates to an apparatus for conversion of radiation according to the invention, comprising energy converters 30 selected from the group of a pressure to electricity converter, and one or more of a heater and a central heating system, and an energy management system.

In a preferred embodiment the apparatus comprises a mini turbine for converting solar radiation energy absorbed in the container into electricity. Such a mini turbine is well known per se to the person skilled in the hard. The turbine 15 converts pressurized liquid (liquid, vapor or gas) flow into electricity.

In a preferred embodiment the apparatus comprises a heater, preferably a heater for water. Heated water can be used for domestic and industrial applications, such as for showering, cleaning, central heating and process heating.

5 In a preferred embodiment the apparatus comprises a heat exchanger. Thereby heat can be upgraded in order to be used for domestic and industrial applications, such as for showering, cleaning, process heating and central heating. In a further preferred embodiment the apparatus comprises a central heating system.

10 Optional other energy converters are chemical energy converters, magnetic energy converters, etc.

In a preferred embodiment the apparatus comprises an energy management system. The energy management system optimizes the energy conversion in terms of amount of electricity and amount of heat generated through 15 conversion, in terms of optimal temperature of the liquid in the container, in terms of storage of optional surplus of energy in which ever form, in terms of shutting down the system when optional overheating might occur, etc.

The software for solar tracking and energy management takes into account common information, general information for determining start parameters, 20 household external costs and usage information, consumption of energy of a household, household market information for a specific country, such as the Netherlands (estimate 2009; underlying source: CBS), market information, System Cost information, System global layout information, system costs, purchase price, return on investment, WPeak costs, WPeak average absorbed and produced energy 25 on a year basis, system absorption ratio, coverage, available average energy per segment, per day, and per season (e.g. geographic position data: Uithoorn - The Netherlands), loss factors, efficiency factors, available average energy per year, calculated and available forms of energy on yearly basis, geometric unit definition, geometric element definition, thermodynamic energy and design data relative to 30 daily pattern, overview global element assembly, display system layout, and graphic overview results.

In a sixth aspect the present invention relates to an apparatus for conversion of radiation according to the invention, comprising a Source Tracking system comprising one or more of a servo drive, a positioning device, a computer, 16 and software.

The source tracking system is aimed at positioning the present apparatus towards the azimuth angle of the source of radiation, e.g. the sun or moon. As such it comprises a computer and software for calculating an optimal 5 position, rotating the apparatus using e.g. a servo drive towards said optimal position through a positioning device as described above. A servo drive may of course also be replaced by means having a similar function and output. As input the computer needs to know the time of day, the day of the year, the year, the angle of the apparatus relative to the surface of the earth (horizontal projection thereof), and 10 the angle of the surface, relative to e.g. north, south etc, or in other words the relative position of the apparatus with respect to the sun or to the moon. As output the computer positions the present apparatus optimally, e.g. in terms of azimuth angle, e.g. oriented towards the azimuth angle.

In a seventh aspect the present invention relates to an apparatus 15 for conversion of radiation according to the invention, comprising one or more energy storage systems selected from a storage system for heat, and a storage system for electricity.

As such surplus energy can be stored and used at a later time. Preferably an energy management system calculates optimal use and conversion 20 rate and form of energy. A storage system can e.g. be a battery, an earth warmth system, an optionally pressured container, etc.

In a eighth aspect the present invention relates to an apparatus for conversion of radiation according to the invention, in the form of one or more units wherein the one or more units can be removably attached to each other. When being 25 mutually attached the one or more units form a closed surface, that is substantially no moisture can penetrate through. Preferably the units have a unit length of 15-500 cm, preferably 50-100 cm, the unit length being preferably equal to, or a multiple of, conventional units used for forming a substantially water-tight surface, such as a roof.

30 As such the present apparatus can easily be attached to a surface, such as a roof. By using standard elements having dimensions similar to or largely the same as conventionally used elements, such as roof tiles, the present invention can easily replace or be used as these conventional elements. Preferably the apparatus has dimensions similar to roof tiles, such as 30 cm by 25 cm, or multiple 17 lengths thereof, such as 60 cm, 90 cm, 120 cm, 150 cm, etc.

In a ninth aspect the present invention relates to a construction element, such as a roofing, cladding, window, lighting, artistic application, comprising at least one apparatus for conversion of radiation according to the 5 invention.

Preferably the construction element is colored, such as in typical colors of a roof or cladding, in order to have an attractive appearance. Even more preferred the construction element is provided with visual elements providing e.g. a roof tile like structure. In the example horizontal visual elements would be provided.

10 The construction element can also be used as lighting, as artistic application etc. Further, it can be used as roofing in green houses, serving a purpose of heating and providing electricity, to the green house and optionally to neighboring houses or buildings.

In a preferred embodiment the present construction replaces a 15 traditional roof, or tile thereon, fully or to a large extent. As such, the present construction can be applied to a full area of a suited roof, or at least to a large part thereof. Even further, by using standardized dimensions, comparable or equal to those used for construction purposes, also element typically present on a roof, such as windows, do not form an objection for use of the present construction, as the 20 units can be mounted around these elements.

In a tenth aspect the present invention relates to a method of converting radiation into both electricity and heat, using an apparatus according to the invention. Advantages and details of such a method are described above.

The invention is further detailed by the accompanying figures, which 25 are exemplary and explanatory of nature and are not limiting the scope of the invention.

DESCRIPTION OF THE DRAWINGS / FIGURES

The invention although described in detailed explanatory context may be best understood in conjunction with the accompanying figures and 30 photographs.

Fig. 1 shows a perspective view of the present energy conversion system.

Fig. 2 shows a cross section of the present energy conversion system.

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Fig. 3 shows a cross section of a preferred embodiment of the present energy conversion system.

Fig. 4 shows a cross section of a preferred embodiment of the present energy conversion system.

5 Fig. 5 shows a cross section of a preferred embodiment of the present energy conversion system.

Fig. 6a-h show cross sections of preferred embodiments of the present energy conversion system and details thereof.

Fig. 7 shows a perspective view of a preferred embodiment of the 10 present energy conversion system.

Fig. 8 shows a perspective view of a preferred embodiment of the present energy conversion system.

Fig. 9 shows a roofing of a house comprising various units according to the invention.

15 Design of a preferred embodiment, the Solar Light Tube (SLT) system.

Overview and common components of the SLT system are shown in figures 1 and 2.

Generally, the SLT is designed for outdoor applications, for 20 bundling incoming radiation energy, absorbing this energy and transmitting this for further processing. It consist of the following four functional system parts as shown in figures 1 and 2: 1. An encasement including an upper lens (100), a lower bottom (110), a radiation insulation system (120), an absorption system (130) and an end 25 cap and/or an absorption system support device (140). Various design options for the encasement system exist of which 4 possible embodiments are explained further down 2. A mechanical support and location system for the encasement including support brackets (200) and clamping strips (210). Generally, the brackets 30 are mechanically fastened (e.g. bolted) or chemically fastened (e.g. glued) onto a base or may be part of that base. The clamping strips are mechanically clamped onto the brackets and permanently locates the encasement whilst at the same time allowing the encasement to rotate. An additional function of the clamping strip is to provide a weather seal between the encasement and clamping strip so that rain, 19 moisture and wind is prevented from passing through. A further function of the clamping strip is to provide a lens cleaning action by wiping along the encasement, scraping off any dirt, when it rotates along its longitudinal axis, while tracking the light source (sun or moon).

5 3. A fixed position energy medium transportation system (300) including a closed circuit piping system for transporting the converted radiation energy to a different location. The piping system is connected to the encasement rigidly or by means of a rotating coupling. The transportation system is designed to hold a high pressure and high temperature medium. Parts of it may be flexible in 10 order to allow it to follow the rotational movement forth and back of the encasement to which is it connected 4.A Radiation Source Tracking System (RSTS) including a drive system (400) for rotating the encasement and pointing the upper lens system towards the light source. The tracking system may consist of a computer based 15 servo-drive system or comparable drive system suitable for this purpose which, in turn, may drive a timing belt or other actuation mechanism which, in turn, rotate the encasement. More SLT's will rotate synchronic when connected to the drive system in line. Longitudinally, SLT's may be located in a stacked order whilst still be connected to the drive system. Other actuation systems, such as pneumatically or 20 hydraulically bases systems, may also be applicable. In case the position of the light source adheres to a known and cyclic pattern, such as the daily position of the sun relative to the position of the system location, the information necessary to control and actuate the tracking system can be calculated from the time-position information of the light source.

25 Design options for the encasement system: a. Solar Light Tube with single concave parabolic mirror (see figure 3);

Here, radiation is entering the curved upper half of the encasement system (100) to hit a concave parabolic shaped mirror (160) of which purpose it is to 30 reflect parallel incoming radiation into a focus-line at a certain distance above the mirror. The focus-line is entering an internal black coated absorption shape, preferable a tube. A purpose of the internal shape is to minimize blackbody radiation losses by re-deflecting the emission of blackbody radiation onto itself as much as possible. Heat is transferred through the inner wall and absorbed by a heat transfer 20 medium, like a fluid or similar (130). To further minimize energy radiation- and convection losses the surface area of this shape is encased by insulation (120).

Material thickness compensation for circular shaped curves:

Depending on component geometry and material refraction 5 properties the transmission of radiation is deflected at each change-over location of two transparent or partially transparent materials. For flat plate geometry of uniform thickness where geometry angles on either side of the material is equal, the direction of radiation at the point of exit will be equal to the direction of radiation at the point of entrance. However, for components with a curved geometry of equal 10 thickness this will not be the case because the material angle at the radiation exit location will be different from that of the radiation entrance location. Thus, for a circular curve of uniform thickness, parallel incoming radiation on the outer entrance side will leave the curve on the inner exit side in a diverge manner. Therefore, in order to obtain a parallel exit direction over the entire exit surface area 15 compensation is preferred in material thickness. For circular shaped curves this may be achieved by introducing an offset of the center point of the inner curve relative to that of the outer curve whereby the material becomes thinner as it approaches both ends of a parabolic mirror.

b. Solar Light Tube with primary concave and secondary parabolic 20 convex mirror (see figure 4);

Similar to a. above, the absorption element can be replaced by a secondary parabolic convex mirror (150) which purpose it is to reflect and further bundle the radiation into a focus-line through the bottom center of the primary parabolic mirror (160). Here the radiation bundle can be absorbed by an absorption 25 element similar to that described in a. above or, alternatively, hit externally a fully closed tubular element which is partially encased by insulation (130). Space may exist between the absorption element and the insulation (120). The material of the insulation encasing is such that the emission of blackbody radiation from the absorption element is partially being re-deflected onto itself by the insulation 30 encasing (125).

c. Solar Light Tube with Curved Internal Focus (CIF) coax lens (see figure 5);

The application of reflection mirrors as in design option a. en b. above limit the radiation catch-area, because secondary components are located in 21 the field of radiation (see figure 3 and 4) therefore limiting radiation absorption efficiency. To improve on this, any system of bundling and absorbing radiation energy is preferably located in-line instead of reflected and bundled by mirrors. To keep the in-line radiation focus-line within the envelope of the required geometry of 5 the encasing, the employment of a single homogenous transparent material lens would require a lot of bulk. This would make it both expensive and heavy to employ. The CIF coax lens design in this option offers a bundling of radiation energy by employing a system of stacked in-line lenses. Here, radiation passes a first stage curved transparent element (100), a second stage cheap en lightweight material, 10 fluid or gel with a refraction index well above 1 (170), and a third stage which may again be of similar material as stage one (180). An example may be the application of water in the second stage which also may include anti-freeze agents to prevent freezing of the fluid. After passing through the CIF coax lens system the focal-line enters an absorption element system as described in a. above (120) (130).

15 d. Solar Light Tube with CIF Fresnel lens (see figure 6);

To further improve on weight- and cost reduction the coax lens system as described in c. above can be replaced by a homogeneous transparent material CIF Fresnel type lens (100). Here, bulk material of the curved design that would otherwise be required to obtain a smooth lens design is removed in radial 20 direction at polar intervals. This staged or staggered design (Fresnel) causes, a staged deflection of an incoming parallel radiation bundle towards the focal-line. To obtain a combined focal-line result of all staged radiation bundles, the inner or exit curve of each stage need to be computer optimized with respect to the component geometry, the material refraction properties and the desired radiation flow pattern. 25 After passing through the CIF Fresnel lens system, the radiation focal-line enters an absorption element system as described in a. above (120) (130).

Generally, the geometry of the CIF Fresnel lens system is characterized by the incorporation of three convex curvatures as follows: " a smooth outer curve which may be parabolic, elliptical, circular, or 30 of any other suitable type of curvature " an intermediate curve which is similar to the outer curvature and which provides a minimal thickness of base material and identifies the start of the "Fresnel" shape " an inner curve which marks the end of the "Fresnel" shape.

22

The above geometry may also be inverted whereby the convex curvature is replaced by a concave curvature. Here, the outer curve identifies the start of the "Fresnel area", the intermediate curve the end thereof and the inner curve the provides the parabolic, elliptical, circular, or any other suitable type of 5 smooth curvature.

To fulfill material requirement, weight, material costs and build up, and keep radiation losses caused by material impurities as low as possible the curvatures should be located as close as practicable, i.e. the lens should be as thin as possible. Furthermore, the flatter the curvature the less radiation reflection losses 10 will be the result. Figure 6b shows an example of a slightly curved normal lens without the "Fresnel" design. This full material lens is bulky, heavy, expensive to manufacture and requires a high level of material purity. Figures 6c to 6h show CIF Fresnel lenses with increasing curvature where radiation losses increase from around 8% to respectively 10% 15 Thus figures 6a-6h show various curved lenses. Efficiencies of these lenses vary: | Lens 16a 6b I6c 6d 6e 6f 6g 6h [ Efficiency........................j "9Z41% [92.35% 92.35% l92.36% 92.26% 9ÊÖ9%- 90-60% [Diameter(mm)....... 500i 500~ 400~ 300 200 ~~ 175 145 20 !...................................................................-........................------------L----j------------------------------J-------------------------------------

Some fields of application;

Arrays of SLT's may be applied as roofing or cladding elements. Figure 7 shows an array of SLT's with a non-transparent lower encasement. Here, for esthetic reasons the lower half can have any desired color. Figure 8 shows an 25 array of SLT's with a fully transparent encasing. This design layout will transmit part of the radiation which is not absorbed by the system and may be applied anywhere where reduced transmission of light is needed (e.g. transparent roofing and cladding).

Figure 9 shows a roofing of a house comprising various units 30 according to the invention. The surface area of this construction element is about 35 m2. The construction element is more than sufficient to supply the energy requirement of an average family in the Netherlands.

1037574

Claims (18)

A radiation conversion device, wherein the radiation is preferably radiation emitted by the sun or reflected by the moon, characterized in that the device is fixed on a surface, the device being suitable for receiving radiation, wherein the device comprises a system for bundling radiation, means for converting radiation into heat and into electricity, and wherein the device optionally comprises one of more of an energy transport system, a transparent protection, and a housing system, a source tracking system, an energy storage system, and a buffer system. 2. Apparatus for converting radiation according to the preamble of claim 1, comprising an energy transport system, which system comprises a. A liquid transport container, preferably a tubular container, b. an insulation with an inner surface that substantially surrounds the container, c. optionally a cavity between the insulation and the holder, the insulation comprising an opening for receiving a beam of radiation, preferably a non-parallel beam of radiation, preferably an opening extending substantially over a length of the holder which opening is optionally covered with a material that is transparent to the radiation, and wherein the opening is smaller than 50% of the total surface of the inner surface of the insulation, preferably smaller than 30%, more preferably smaller than 20 % thereof, even more preferably less than 15%, more preferably less than 10%, most preferably less than 5%. 3. Device as claimed in claim 2, wherein the holder comprises an entrance which substantially coincides with the opening of the insulation, wherein the holder comprises two or three substantially concentric walls, the holder preferably being a preform, a space between the walls are filled with the liquid, the liquid preferably having a high specific heat capacity (kJ / kgK), and / or wherein the liquid has a melting point below -10 C, preferably below -50 C, and a boiling point above 50 C, preferably above 90 C. 1037574 4. Apparatus for the conversion of radiation according to the preamble of claim 1, comprising a transparent protection, which protection comprises a curved element with a certain refractive index, wherein an outer curvature of the element is different from that of an inner curvature of the element, such that an parallel beam of radiation entering the protection at the outer curvature at a certain angle 0 leaves the inner curvature of the protection substantially parallel to the angle 6. A radiation conversion device according to claim 4, comprising a transparent protection, with an outer curvature of the element 10 that is substantially circular and an inner curvature that is elliptical, or vice versa. 6. Apparatus for converting radiation according to the preamble of claim 1, comprising a. An energy transport system according to claim 2 or claim 3, comprising a holder and an insulation, b. a radiation bundling system comprising one or more parabolic mirrors and / or one or more lens systems, and c. wherein the liquid in the container absorbs energy from a radiation bundling system. The radiation conversion apparatus according to claim 6, wherein a hollow parabolic mirror is directed substantially toward the sun or moon for beaming radiation, wherein a focus area of the bundled radiation is substantially within the insulation. 8. Device as claimed in claim 6 or 7, further comprising a convex parabolic mirror, wherein the convex mirror bundles radiation reflected from the concave mirror. A radiation conversion device according to claim 6, comprising a transparent protection comprising two or more transparent elements, such that the protection functions as a lens. The radiation conversion apparatus according to the preamble of claim 1, comprising a transparent protection, which protection comprises a curved element with a specific refractive index, the protection having a thickness that varies stepwise over the curvature such that preferably a minimum thickness dmin of the protection is greater than 0.1 * a maximum thickness dmax, such that a parallel beam of radiation entering the protection at an outer curve leaves the inner curve in focus. A radiation conversion device according to the preamble of claim 1, comprising a housing system for holding the device 5 comprising one or more of a cleaning system, such as a lens cleaning system, a seal for the housing, fixing means for the housing system, means for fixing rotating the device about a longitudinal axis thereof substantially in the direction of the sun, at least one reflective internal surface, and a support system. The radiation conversion apparatus according to the preamble of claim 1, comprising energy converters selected from the group consisting of a pressure-to-electricity converter, and one or more of a heater, a process heater and a central heating system, and an energy management system. 13. Device as claimed in claim 12, comprising a mini turbine for conversion of solar radiation energy absorbed in the holder into electricity. The radiation conversion apparatus according to the preamble of claim 1, comprising a source tracking system comprising one or more of a servo drive, a positioning device, a computer, and software. 15. Apparatus for converting radiation according to the preamble of claim 1, comprising one or more energy storage systems selected from a heat storage system, and an electricity storage system. 16. Apparatus for converting radiation according to claim 1, in the form of one or more panels, preferably with a unit length of 15-500 cm, more preferably of 50-100 cm, wherein the one or more panels can be detachably connected to each other. to become. A building element, such as a roof covering, cladding, window, lighting, artistic application, comprising at least one radiation conversion device according to claim 1. 18. Method for converting radiation into electricity and heat, using a device according to claim 1. 1 03 75 74 J