WO2010080059A1 - Corps en aérogel de silice utilisé comme isolation dans un collecteur de chaleur solaire - Google Patents

Corps en aérogel de silice utilisé comme isolation dans un collecteur de chaleur solaire Download PDF

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Publication number
WO2010080059A1
WO2010080059A1 PCT/SE2010/050003 SE2010050003W WO2010080059A1 WO 2010080059 A1 WO2010080059 A1 WO 2010080059A1 SE 2010050003 W SE2010050003 W SE 2010050003W WO 2010080059 A1 WO2010080059 A1 WO 2010080059A1
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WO
WIPO (PCT)
Prior art keywords
male
female
silica aerogel
halfpipe
long side
Prior art date
Application number
PCT/SE2010/050003
Other languages
English (en)
Inventor
Leif Gullberg
Christer Westlund
Original Assignee
Ab Airglass
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ab Airglass filed Critical Ab Airglass
Publication of WO2010080059A1 publication Critical patent/WO2010080059A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S80/00—Details, accessories or component parts of solar heat collectors not provided for in groups F24S10/00-F24S70/00
    • F24S80/60—Thermal insulation
    • F24S80/65—Thermal insulation characterised by the material
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L59/00—Thermal insulation in general
    • F16L59/10—Bandages or covers for the protection of the insulation, e.g. against the influence of the environment or against mechanical damage
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C01B33/14—Colloidal silica, e.g. dispersions, gels, sols
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C01B33/14—Colloidal silica, e.g. dispersions, gels, sols
    • C01B33/157—After-treatment of gels
    • C01B33/158—Purification; Drying; Dehydrating
    • C01B33/1585—Dehydration into aerogels
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K5/00—Heat-transfer, heat-exchange or heat-storage materials, e.g. refrigerants; Materials for the production of heat or cold by chemical reactions other than by combustion
    • C09K5/08—Materials not undergoing a change of physical state when used
    • C09K5/14—Solid materials, e.g. powdery or granular
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L59/00—Thermal insulation in general
    • F16L59/02—Shape or form of insulating materials, with or without coverings integral with the insulating materials
    • F16L59/021—Shape or form of insulating materials, with or without coverings integral with the insulating materials comprising a single piece or sleeve, e.g. split sleeve, two half sleeves
    • F16L59/024—Shape or form of insulating materials, with or without coverings integral with the insulating materials comprising a single piece or sleeve, e.g. split sleeve, two half sleeves composed of two half sleeves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L59/00—Thermal insulation in general
    • F16L59/06—Arrangements using an air layer or vacuum
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S10/00—Solar heat collectors using working fluids
    • F24S10/40—Solar heat collectors using working fluids in absorbing elements surrounded by transparent enclosures, e.g. evacuated solar collectors
    • F24S10/45—Solar heat collectors using working fluids in absorbing elements surrounded by transparent enclosures, e.g. evacuated solar collectors the enclosure being cylindrical
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S20/00—Solar heat collectors specially adapted for particular uses or environments
    • F24S20/20—Solar heat collectors for receiving concentrated solar energy, e.g. receivers for solar power plants
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/10—Solid density
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/40—Solar thermal energy, e.g. solar towers
    • Y02E10/44—Heat exchange systems

Definitions

  • the present invention relates to a silica aerogel body as the insulation unit of a solar thermal collector system, to such an insulation unit comprising a protective casing and to a solar receiver tube for a high temperature solar thermal collector system.
  • the method is carried out by hydrolysis of tetraalkoxysilane, preferably tetrametoxysilane, in an alcohol, preferably methanol, in the presence of a catalyst preferably ammonia, to the formation of an alcogel, the aging for about 10 days and washed with alcohol to remove water. After that the alcogel subsequently is treated in an autoclave by temperature increase to over alcohol critical point, isotherm pressure drop through the discharge of alcohol vapour, and temperature drop.
  • SE 422045 The method is energy-intensive as it is implemented at comparatively high temperatures, such as e.g. final heat treatment at between 500 0 C and 75O 0 C. Furthermore, the process of implementation of the method is not quite easy to keep secure because the removal of the solvent from alcogel and finally out of the autoclave is carried out at relatively high pressures and temperatures, such as for the preferred solvent methanol at about 90 bar and at a final temperature of 275 0 C. Finally, the material produced according to SE 422045 is not optimal for various uses. An example of this is that the heat conductivity specified in SE 422 045 is 0.021 W / (m * K) for the obtained aerogel material after evacuation.
  • Hybride aerogel mate- rials are materials that include aerogels and other materials.
  • the material described in WO2007011988 A2 is not meant to serve as insulation material in applications where light have to be able to penetrate, which is evident when material include for example polymers, monomers or oligo-isomers. This means that the material is not high-transparent and also not particularly heat resistant or fire resistant.
  • none of the material according to WO2007011988 A2 is super-insulating, and may not be made super-insulating. All of these built in features means that the material according to WO2007011988 A2 is not appropriate as super insulating material in applica- tions where the light penetration is of importance.
  • WO2007146945 A2 describes flexible aerogel foam composites which includes at least one open cell foam component and at least one aerogel matrix.
  • the material according to WO2007146945 A2 includes at least one component that is not an aerogel type. In this way the material can be made flexible. To make an aerogel material flexibility is virtually impossible without the involvement of other types of material, as shown in WO2007146945 A2. This also involves completely different effects. Even in this case, as in the case of WO2007011988 A2, the material can never be high-transparent, heat-resistant or made super-insulating. It is also known to use silica aerogel as a thermal insulating material in a solar collector.
  • a solar heat collector panel unit in which a heat collector panel and tubes for heat medium is associated with a transparent insulating material.
  • the transparent insulating material may for example be a silica aerogel material obtained by supercritical drying of a wetgel obtained from alkoxysilanes by hydrolysis and polyconden- sation.
  • an adhesions procedure for integrating a silica aerogel with the heat collecting plate and tubes, which are coated with a selective absorption film is implemented.
  • a solgel for further manufacturing of a wetgel.
  • Ammonium hydroxide is added as a catalyst to the alkoxysilane, which e.g.
  • silica aerogel produced according to EP 1 707 897 A1 , is in rectangular blocks in which the collector and its collector wing and pipes related thereto are contained in the block.
  • the design of the solar collector system is that which is typical for low temperature solar collector systems and typically used for smaller systems, for example as for individual households.
  • One aim of the present invention is to provide an improved silica aerogel material for use as an insulation unit of a solar thermal collector system, especially for high temperature solar thermal collector systems where heating of the media is between 15O 0 C and 500 0 C.
  • Another aim of the present invention is to provide an insulation unit for high temperature solar thermal collector systems comprising the improved silica aerogel material according to the invention. Summary of invention
  • the first stated purpose above is achieved through a body for use as insulation in a solar thermal collecting system, wherein the body is composed of a silica aerogel material which:
  • - has a heat conductivity ⁇ of less than 0.020 W / (m * K) when measured at a density of 150 kg/m 3 and a temperature of around 2O 0 C, and
  • - has a sunlight transmittance which is at least 90% at a material thickness of 15 mm.
  • the silica aerogel material according to the present invention has a very low heat conductivity.
  • the heat conductivity coefficient of thermal con- ductivity
  • SE 422 045 the aerogel material described in SE 422 045
  • the latter in itself measured at a higher density of 240 kg/m 3 but yet in evacuated state (free from air in the pores), which in itself implies a much lower heat conductivity than in the non- evacuated state.
  • FIG. 1 shows a cross section of a solar receiver tube according to the present invention with two symmetrical halfpipe-shaped bodies of silica aerogel material insulating an absorber pipe and each enclosed by a protective transparent glass casing.
  • Figure 2 shows a cross section of a solar receiver tube according to the present invention with a symmetric halfpipe-shaped body of silica aerogel material as insulation at the bottom, i.e. on the shadow side, while the part where the rays of the sun is to penetrate only is covered with transparent protective outer glass casing.
  • Figure 3 shows a cross section of a solar receiver tube according to the present invention, with a symmetric halfpipe-shaped body of silica aerogel as insulation on the shadow side and a non-symmetric halfpipe-shaped body of silica aerogel material as insulation on the sunny side, which bodies each are enclosed by a protective transparent glass casing.
  • the material according to the present invention may have different properties depending on the solar collector application which the material is intended for. When the material is supposed to have a location where sunlight penetrates, which is most common, the material in accordance with the present invention must have a high transmittance of sunlight.
  • the body because of this has a sunlight transmittance of at least 90% at a material thickness of 15 mm, such as for example 90-95%, for example at least 92%.
  • Transmittance is, meant in this case, permeability of the entire solar spectrum, i.e. all the light wave lengths the sunlight is composed of.
  • the trans- mittance is measured by dividing the intensity of outgoing light through the intensity of incoming light.
  • a value of the transmittance is to be associated with a certain thickness, since transmittance depends on this.
  • the material is merely to act as insulation it does not need to have this high transmittance, but may for example be translucent or even opaque by adding other components, such as fiber materials to increase the mechanical strength.
  • Carbon fiber material is for example possible to ad.
  • the adding of polymers, such as according to WO2007011988 A2 means that the material loses heat resistance and the possibility of high transparency or translucency. In addition, such materials can never be super-insulating.
  • silica aerogel material according to the present invention In the same way for the materials according to WO2007146945 A2, in which components are added to make the material flexible, this implies that the material cannot be transparent or translucent and that it likewise cannot be made super-insulating.
  • An intrinsic possible property of silica aerogel material according to the present invention is, however, the high transmittance of the material. Since silica aerogel material according to the present invention should be used as insulation in solar thermal collector systems, this is an important property if the material should be placed on the so called sunny side where the sunlight will penetrate through the insulating material. Due to the material's potential high transmittance and low heat conductivity, i.e. high insulation value, the material according to the present invention therefore is suitable as insulation of collectors of various solar thermal collector systems.
  • the evacuation of the material which means that essentially all the air left in the pores of the material are driven out, is a possible method wherein heat conductivity of the present material can be further improved.
  • the body is evacuated and is super-insulating and has a heat conductivity ⁇ which is 0.007 W / (m * K) or less when measured at a density of 150 kg/m 3 and temperature of about 20 ° C. This is a value for the heat conductivity that is much lower than for both the vacuum and the material described in SE 422 045.
  • the density of the silica aerogel material according to the present invention can be between 100 and 250 kg/m3, such as between 120 and 230 kg/m 3 , but in a number of applications the desired density is between 100 and 200 kg/m 3 , such as in the range of 125-175 kg/m 3 , for example at about 150 kg/m 3 .
  • the materials according to WO2007011988 A2 or WO2007146945 A2 are not possible to evacuate and make super-insulating.
  • To evacuate mate- rial, such as the present invention means that the material is enclosed between for example a pair of plates, such as glass plates, and that the air in the material is sucked out. Since the material according to WO2007011988 A2 not is solid but more as a kind of felt carpet it is not possible to carry out an evacuation of the material in this way. Would such an evacuation be carried out, this would flatten the material enormously. The same applies to the material according to WO2007146945 A2.
  • the material according to the present invention is however just a solid and therefore withstand very high widely spread pressures.
  • the body according to the present invention can also be enclosed in a surrounding transparent material.
  • a transparent material therefore is surrounding the body, such as when the material is evacuated as described above.
  • the transparent enclosing material is selected from the group consisting of transparent glass materials. If this enclosure is surrounding the body completely, also an evacuated material can be enclosed so that it can be maintained evacuated.
  • body according to the present invention is meant a geometric body. What type of geometric body that is wanted in the present invention will naturally depend on the type of solar thermal collector it is supposed to be an isolating unit in.
  • the body is a panel-shaped body.
  • a panel according to the present invention is referred to further geometrical shapes, where length and width is greater than the thickness. According to the present invention completely different thicknesses, lengths and widths are possible.
  • the shapes of bodies described according to the present invention is different from the blocks of silica aerogel described in EP 1 707 897.
  • the blocks according to EP 1 707 897 are meant for another type of use than the silica aerogel bodies according to the present invention.
  • the blocks under EP 1 707 897 shall surround a collector unit with its collector-wings and tubes to this collector unit, which is typical of devices in a low temperature solar thermal collector system, such as for household use.
  • the panels according to the present invention is however not intended for such solar thermal collector systems, but find use as insulation in larger units in which the media also typically are heated to above 15O 0 C.
  • a low temperature solar thermal collector system is performed a concentrating of the sunlight and its energy. This is performed by means of mirrors, such as e.g. parabola mirrors and/or secondary mirrors, which reflects the sunlight so that it hits a proposed collector area.
  • a low temperature solar thermal collector system allows the sunlight to hit directly on the collector and its collector-wings. This implies that in such a system the energy supply of sunlight is relatively not as high, reckoned per area unit, and partly because of that the warming of the used media are at a comparatively lower temperature.
  • a panel according to the present invention thus finds use in certain types of solar thermal collector systems. These solar thermal collector sys- terns can be very different in appearance, but common to them is that they require isolation of the space in which the collector unit are to receive solar energy. This isolation is today often only of e.g. glass which houses an air space where the collector unit is placed. This means that the heat conductivity is comparatively high because the air itself is around 0.026 W / (m * K) at room temperature, which in turn leads to energy losses. By placing a silica aerogel panel according to the present invention inside the glass energy losses can be reduced when the conductivity for the silica aerogel material is at least below 0.020 W / (m * K) at about 20 ° C.
  • the body according to the present invention is a halfpipe-shaped body.
  • This variant finds use as insulation of absorber tubes in high temperature solar thermal collector systems. These solar thermal collector systems are as mentioned designed by some form of mirrors reflecting or directing sunlight or sunrays, in this case against an absorber tube which captures the sun heat, thus warming up the medium which flows inside the absorber tube.
  • the present invention provides an alternative to the vacuum tubes to remedy the above problems.
  • halfpipe-shaped silica aerogel bodies according to the present invention as isolation of absorber tubes in high temperature solar thermal collector systems, the heat conductivity can be kept at a very low level.
  • the halfpipe-shaped silica aerogel bodies according to the present invention is suitable for use as isolation of absorber tubes in high temperature solar thermal collector systems in which the media is heated to above 15O 0 C, often up to and above 400°C-500°C.
  • the material according to the present invention is heat resisting and can stand at least 400 0 C, for example at least 500 0 C.
  • the material according to the present invention has according to a specific embodiment for example a heat resistance of 600 0 C. Also this property is something that distinguishes the material according to the present invention substantially from the materials according to WO2007011988 A2 and WO2007146945 A2.
  • the thickness of the bodies according to the present invention may be important to optimize the thickness of the bodies according to the present invention. This is because a thicker body insulates better, but lets on the other side less light to pass or lowers the transmitted light intensity in comparison to a thinner body. This means that light transmittance decreases. This also means that both the insulation ability and the transmittance have to be looked over simultaneously when an optimized system according to the present invention is designed for a certain application.
  • the halfpipe- shaped variant can, for example a non-symmetrical variation be possible according to the present invention, where the body is thinner in some places where a lot of sunlight is to penetrate, i.e. at the sun side, while thicker where good insulation is the only important characteristic, namely the shadow side.
  • an opaque material according to the present invention can be used on the shadow side in combination with glass on the sun side, as isolation of an absorber tube in a high temperature solar thermal collector system.
  • the present invention also describes the use of silica aerogel bodies as described above for the isolation of a collector unit in a solar thermal collector system.
  • a halfpipe-shaped body of silica aerogel material for the isolation of a collector unit, such as an absorber tube, in a solar thermal collector system.
  • a collector unit such as an absorber tube
  • a halfpipe-shaped body of silica aerogel material as insulating by direct contact and enclosure of an absorber tube in a high temperature solar collector system.
  • the absorber tube can be enclosed by silica aerogel bodies according to the present invention in different ways.
  • one of these halfpipe-shaped bodies can be non-symmethcally shaped so that it is thinner on the sunny side, where sunlight is to penetrate.
  • Such a halfpipe-shaped body with non-symmetrical cross section should also be considered as a halfpipe-shaped body according to the present invention.
  • the sunny side can be completely free of insulation according to the present invention so that only the remaining part of the absorber tube, i.e. the part not struck by sunlight, is insulated by the material of the present invention.
  • the material does not need to be transparent and in this case, insulating and mechanical strength should be optimized so that the heat conductivity is as low as possible and the material becomes sustainable.
  • fibers can be added to the material according to the present invention. In an application as described above transparent glass is placed on the sunny side.
  • the present invention also refers to use of a panel-shaped body of silica aerogel material, for insulating a space surrounding a collector unit of a solar thermal system.
  • the panel according to the present invention is in this case placed as insulation in a position where sunlight will pass through and reach the receiver or sun light collector unit.
  • the panel according to the present invention can be evacuated and enclosed in a transparent material. Thereby the panel can be evacuated and enclosed by glass on all sides. By evacuation, a material with extremely good insulating ability is achieved.
  • the present invention also describes an insulation unit for a high temperature solar thermal collector system, where the insulation unit includes a halfpipe-shaped body of silica aerogel material according to the invention that at the outside is surrounded by a matching halfpipe-shaped protective casing of a transparent material.
  • This unit is one half of the insulation to an absorber tube.
  • the protective casing may for example be made of a transparent glass material, such as for example a borosilicate glass.
  • the protective casing may also have a female or male along one long side and a female or male along the other long side, the female or male along the long side and the female or male along the other long side can be brought together and locked with a male or female respectively male or females with a further insulation unit with protective casing.
  • a protective casing for an insulation unit according to the present invention may have a female along one long side and a male along the other long side, as shown in the figures, but may also have a female along the long side and also a similar female along the other long side.
  • a protective casing according to the present invention has a male along the long side and a male along the other long side.
  • Other possible equivalent designations of the protective casing according to the present invention could for example be "suspension casing", “attachment casing” or "supporting casing”.
  • the supporting casings according to the present invention for example in the form of glass halves, is not only a protection, but keeps the insulating halfpipes in place by holding the glass halves together by suitable clips, seals, etc.
  • the present invention therefore also is referred to the use of two insulation units as above, for the enclosure of an absorber tube in a high temperature solar thermal collector system, wherein two halfpipe- shaped bodies of silica aerogel material bear against each other to form a symmetric or non-symmetric cylinder-shaped body of silica aerogel material which encloses and insulates the absorber tube, and wherein the female or the male along the long side and the female or male along the other long side of a protective casing are connected with the male or female along one long side respectively the male or the female along the other long side of another protective casing.
  • Female or male in one protective casing, and male or female on the other protective casing, can also be security connected to each other using a clamp, such as a metal clip, on both sides of the insulation unit.
  • these silica aerogel materials usually are not evacuated because they will be in contact with air prior to mounting on a absorber tube. This means consequently that these halves will come as modules and be placed in position around absorber tubes when assembling. It would, according to the invention, however, be possible to produce modules that include evacuated silica aerogel material. These halves are then fully enclosed by glass. The advantage is obviously that it would be possible to obtain very low heat conductivity rates for the silica aerogel material, even as low as down to below 0.007 W / (m * K), at a density of 150 kg/m 3 and temperature of about 2O 0 C. On the other hand, it requires a lot of glazing material and handling of this material as well as welding thereof.
  • the present invention also describes a solar receiver tube for high temperature solar thermal collector systems, comprising: - one absorber tube for enclosure of a heating medium;
  • protective casings can of course include a female or male along one long side and a female or male along the other long side, wherein a female or male respectively a female or male of a protective casing is attached to a male or female respectively a male or female of the second protective casing and with each connection of male and female furthermore security connected using a clamp, such as a metal clamp.
  • a clamp such as a metal clamp.
  • said heating medium are steam, oil or overheated water.
  • silica aerogel material can be performed in many different ways. Below is an example of such a production and this should be seen only as an example and not limiting the scope of the present invention. The scope is defined by the claims.
  • the starting point for this particular example is that a mixture is performed by at least one silane compound and a solvent in the form of an alcohol such as methanol, ethanol or propanol, and that a catalyst is added, for example titanium lactate or ammonia.
  • a catalyst for example titanium lactate or ammonia.
  • This is performed under temperature control to form a so-called solgel which by polymerization grows into a wetgel.
  • the wetgel then is further processed through a casting procedure, and extraction in an autoclave where the alcohol is driven out by using supercritical or liquid carbon dioxide.
  • a silica aerogel material is formed which by further heating at for example above 200 0 C can be even more free of alcohol admixture.
  • a solgel is, by definition, a suspension consisting of a solvent and a sol which then may polymerize and aggregate to form a gel. Polymerization above implies joining to longer chains by chemical reaction and not by any polymer being added to the material.
  • the solvent in this case, for example, methanol, ethanol or propanol, can then be boiled away and the result is a porous material.
  • silane compound used may be tetramethylortosilicate (TMOS), also known as tetramethoxysilane, or tetraethylortosilicate (TEOS), the latter also known as tetraethoxysilane, or mixtures thereof.
  • TMOS tetramethylortosilicate
  • TEOS tetraethylortosilicate
  • the procedure may be run according to basic as well as acid method.
  • acid In the acid case are possible alternatives HF, HCI and H 2 SO 4 , but where HF is the least desirable.
  • basic catalysts such as e.g. ammonia or titaniumlactate.
  • titaniumlactate catalyst An example of a commercially available titaniumlactate catalyst which can be used in the present procedures, are furthermore TYZOR ®. Among other things, this also differs in comparison with EP 1 707 897 A1 in which ammonium hydroxide is added as a catalyst to the alkoxysilane.
  • the mould For the manufacture of halfpipe-shaped bodies according to the present invention the mould must have a form adapted to this shape in order to obtain this shape. It will of course be the same case if panels are to be produ- ced.
  • the material shrinks slightly and this is something that should be taken into account in terms of how production is carried out, such as the choice of type of mould and size of mould to obtain silica aerogel material halfpipes that fit around a specific absorber tube. It is also entirely possible that the moulding is made directly into the glass tubes, which then will form the protective casing in insulation units.
  • the shrinkage is again something you have to take into consideration and some adjustment may be needed to the readily polymerized silica aerogel material to get the shape to fit perfectly into the insulation units. This can for example be done by adding bits of silica aerogel material after polymerization so that the design will be complete.
  • An example of a material for a mould in this case, is for example glass, but there are other materials that are equally possible.
  • Figure 1 shows a solar receiver tube 7 according to the present invention, seen in cross section.
  • the absorber tube 2 is insulated by each one halfpipe-shaped body 1 of silica aerogel material according to the present invention, the bodies 1 located flush against each other, thus forming a symmetrical cylinder-shaped insulation around the absorber tube 2.
  • Respective halfpipe-shaped body 1 is enclosed by a protective casing 4 which is of a transparent glass material.
  • the body 1 and its protective casing 4 together form an insulation unit 3 to the absorber tube 2.
  • the locking can for example be made by means of a clamp, such as for example a metal clamp, which is not shown in Figure 1.
  • each protective casing 4 has a female 5 along one long side and a male 6 along the other long side.
  • the casings 4 need not to be designed in this way according to the present invention.
  • a protective casing 4 very well can have a female 5 along the long side and also a female 5 along the other long side.
  • Such a protective casing 4 would then be connected, brought together and/or locked with a protective casing 4 which has a male 6 along its one long side and a male 6 along the other long side.
  • the upper protective casing 4 of the two casings has a female 5 along the long side and a female 5 along the other long side.
  • This upper protective casing 4 can then be connected, brought together and/or locked with a lower protective casing 4 which has a male 6 along its one long side and another male 6 along its other long side.
  • a design according to the present invention could be a useful option when the external cleaning of the solar receiver tube 7 is essential at regular intervals, reflecting that when water is flushed from the top, it runs along the females 5 without any great risk of water entering between the female 5 and male 6 where these are connected to each other.
  • Figure 2 also shows a solar receiver tube 7 according to the present invention, wherein only the bottom, i.e. the shadow side, has a similar halfpipe-shaped body 1 as in Figure 1.
  • the shadow side On the sunny side pieces of material are only inserted at the sides below the top protective casing 4 while the area where the sunlight is to penetrate are completely free of insulating silica aerogel material.
  • the halfpipe-shaped body 1 on the shadow side does not need to be transpa- rent provided that sunlight will not penetrate in this place. This means that optimization of the material in this case can be made only on insulating ability as high transmittance is not important for this part.
  • a solar receiver tube 7 is shown in the same way as in Figure 1 and Figure 2, but in this case the upper halfpipe-shaped body 1 is non-symmetrical and as such thinner where sunlight is to penetrate.
  • This is a form according to an embodiment according to the present invention, which as well can cause very high sunlight transmittance and high insulating ability by a low heat conductivity.
  • bodies of silica aerogel material according to the present invention in high temperature solar thermal collector systems makes it possible to obtain very good insulating ability by means of the energy losses being low.
  • a high sunlight transmittance can be obtained.
  • half- pipe-shaped bodies according to the present invention are useful for insulation of absorber tubes in high temperature solar thermal collector systems instead of today's vacuum tubes. Examples of how this can be done in accordance with the present invention are shown in Figure 1-3.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Dispersion Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Inorganic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Silicon Compounds (AREA)
  • Thermal Insulation (AREA)

Abstract

La présente invention concerne un corps à utiliser comme isolation d'un collecteur de chaleur solaire, lequel corps est composé d'un matériau à base d'aérogel de silice présentant une densité dans la gamme de 100-250 kg/m3 et une conductivité thermique λ inférieure à 0,020 W/(m*K), mesurée à une densité de 150 kg/m3 et une température d'environ 200 °C. On décrit entre autres un tube récepteur solaire 7 pour collecteur de chaleur solaire à haute température comprenant un tube absorbeur 2 contenant un milieu chauffant, deux corps en forme de demi-tube 1 en aérogel de silice selon l'invention qui s'appuient l'un contre l'autre pour former une isolation de forme cylindrique symétrique ou non, laquelle isolation repose contre le tube absorbeur 2 et deux enveloppes protectrices 4 en verre transparent, chacune de ces enveloppes renfermant un corps en forme de demi-tube 1 en aérogel de silice, et les enveloppes protectrices 4 étant reliées l'une à l'autre.
PCT/SE2010/050003 2009-01-08 2010-01-04 Corps en aérogel de silice utilisé comme isolation dans un collecteur de chaleur solaire WO2010080059A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE0950004A SE533058C2 (sv) 2009-01-08 2009-01-08 Silikaaerogelkropp som isolering i ett solfångarsystem
SE0950004-2 2009-01-08

Publications (1)

Publication Number Publication Date
WO2010080059A1 true WO2010080059A1 (fr) 2010-07-15

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SE (1) SE533058C2 (fr)
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2417454A1 (es) * 2013-05-29 2013-08-07 Alberto Miguel RETANA PENDON Accesorio para el aislamiento termico de tubos y conexiones en una instalacion de aprovechamiento termico de la energia solar e instalacion con dicho accesorio
ES2431470R1 (es) * 2011-05-13 2013-12-04 Termo Fluids S L Captadores solares termicos con aislamiento transparente
CN106032948A (zh) * 2015-03-17 2016-10-19 中国电力工程顾问集团华北电力设计院有限公司 槽式太阳能集热管的保温***

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4327065A (en) * 1979-04-30 1982-04-27 Dardel Guy Von Method of preparing silica aerogel
EP1707897A1 (fr) * 2003-12-03 2006-10-04 Dynax Corporation Panneau solaire
WO2007011988A2 (fr) * 2005-07-18 2007-01-25 Aspen Aerogels, Inc. Composites d'aerogel a geometries complexes
WO2007146945A2 (fr) * 2006-06-12 2007-12-21 Aspen Aerogels, Inc. Composites d'aérogel et de mousse

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4327065A (en) * 1979-04-30 1982-04-27 Dardel Guy Von Method of preparing silica aerogel
EP1707897A1 (fr) * 2003-12-03 2006-10-04 Dynax Corporation Panneau solaire
WO2007011988A2 (fr) * 2005-07-18 2007-01-25 Aspen Aerogels, Inc. Composites d'aerogel a geometries complexes
WO2007146945A2 (fr) * 2006-06-12 2007-12-21 Aspen Aerogels, Inc. Composites d'aérogel et de mousse

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2431470R1 (es) * 2011-05-13 2013-12-04 Termo Fluids S L Captadores solares termicos con aislamiento transparente
ES2417454A1 (es) * 2013-05-29 2013-08-07 Alberto Miguel RETANA PENDON Accesorio para el aislamiento termico de tubos y conexiones en una instalacion de aprovechamiento termico de la energia solar e instalacion con dicho accesorio
CN106032948A (zh) * 2015-03-17 2016-10-19 中国电力工程顾问集团华北电力设计院有限公司 槽式太阳能集热管的保温***
CN106032948B (zh) * 2015-03-17 2017-11-28 中国电力工程顾问集团华北电力设计院有限公司 槽式太阳能集热管的保温***

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SE0950004A1 (sv) 2010-06-15
SE533058C2 (sv) 2010-06-15

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