EP2102562A1 - Absorber for the conversion of solar rays into thermal energy - Google Patents

Absorber for the conversion of solar rays into thermal energy

Info

Publication number
EP2102562A1
EP2102562A1 EP06818771A EP06818771A EP2102562A1 EP 2102562 A1 EP2102562 A1 EP 2102562A1 EP 06818771 A EP06818771 A EP 06818771A EP 06818771 A EP06818771 A EP 06818771A EP 2102562 A1 EP2102562 A1 EP 2102562A1
Authority
EP
European Patent Office
Prior art keywords
absorber
absorber according
silicon carbide
heat
connector
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP06818771A
Other languages
German (de)
French (fr)
Inventor
Gerald Göbel
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
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Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of EP2102562A1 publication Critical patent/EP2102562A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S70/00—Details of absorbing elements
    • F24S70/10—Details of absorbing elements characterised by the absorbing material
    • F24S70/16—Details of absorbing elements characterised by the absorbing material made of ceramic; made of concrete; made of natural stone
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S23/00—Arrangements for concentrating solar-rays for solar heat collectors
    • F24S23/70—Arrangements for concentrating solar-rays for solar heat collectors with reflectors
    • F24S23/74—Arrangements for concentrating solar-rays for solar heat collectors with reflectors with trough-shaped or cylindro-parabolic reflective surfaces
    • 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
    • F24S80/70—Sealing means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S25/00—Arrangement of stationary mountings or supports for solar heat collector modules
    • F24S25/60—Fixation means, e.g. fasteners, specially adapted for supporting solar heat collector modules
    • F24S2025/6007—Fixation means, e.g. fasteners, specially adapted for supporting solar heat collector modules by using form-fitting connection means, e.g. tongue and groove
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S25/00—Arrangement of stationary mountings or supports for solar heat collector modules
    • F24S25/60—Fixation means, e.g. fasteners, specially adapted for supporting solar heat collector modules
    • F24S2025/601—Fixation means, e.g. fasteners, specially adapted for supporting solar heat collector modules by bonding, e.g. by using adhesives
    • 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

Definitions

  • the invention relates to an absorber for the conversion of solar radiation into heat energy, in particular for use in a solar collector, which is traversed by a heat-transporting medium.
  • Solar panels are used to convert solar energy into thermal energy and make it usable as such. They consist essentially of an absorber which is made of a material with a good thermal conductivity, e.g. Copper or steel, and a piping system through which a liquid or gas transports the absorbed energy from the absorber to an application site of the obtained thermal energy.
  • an absorber which is made of a material with a good thermal conductivity, e.g. Copper or steel
  • a piping system through which a liquid or gas transports the absorbed energy from the absorber to an application site of the obtained thermal energy.
  • optical systems such as e.g. Heliostats or parabolic troughs, are used to focus the sun's rays on the absorber.
  • Absorbers usually have a black surface, which is achieved by applying a black pigmented paint to ensure maximum solar energy absorption capacity.
  • a black pigmented paint to ensure maximum solar energy absorption capacity.
  • the absorber consists essentially of a non-porous ceramic made of dark material.
  • the central idea of the invention is namely to use instead of metal pipes with a dark, especially black paint or coating non-porous ceramic pipes, which are made of a dark material, which on the one hand has the advantage that the absorber is not extra on the other hand eliminates the need to prevent the entry of oxygen by encapsulation in vacuum tubes.
  • the use of ceramics also makes it possible to allow absorber temperatures of well above 400 ° C., in particular up to 800 ° C. or even higher, depending on the optical systems used.
  • the non-porous or dense ceramic is a non-oxide ceramic based on silicon carbide (SIC), in particular technical silicon carbide, which among other things has a high thermal conductivity and low thermal expansion and is also usable at very high temperatures .
  • SIC silicon carbide
  • Technical grade silicon carbide is dark colored (black to green) due to contamination present, with the degree of coloration decreasing as the degree of purity of the silicon carbide increases.
  • Especially suitable silicon carbide non-oxide ceramics have been found to be pressure-sintered silicon carbide (SSIC) and reaction bonded silicon-infiltrated silicon carbide (SISIC), although liquid phase sintered silicon carbide (LPSIC), hot pressed silicon carbide (HPSIC), and hot isostatic silicon carbide (HIPSIC). are usable.
  • SSIC Pressureless gesinteres silicon carbide
  • SSIC is produced from ground SIC very fine powder, the sintering additives to put in the ceramic customary shaping variants processed and sintered at 2000 to 2200 0 C under a protective gas.
  • SSIC is characterized by a high strength, which remains almost constant up to high temperatures of about 1600 0 C.
  • this material has a high thermal shock resistance, high thermal conductivity, high wear resistance and a diamond-like hardness.
  • reaction-bonded silicon-infiltrated silicon carbide comprises, for example, about 85 to 94% SIC and, correspondingly, 15 to 6% metallic silicon (Si).
  • SICIC has virtually no residual porosity. This is accomplished by infiltrating a silicon carbide and carbon mold with metallic silicon. The reaction between liquid silicon and the carbon results in an SIC bond matrix, with the remaining pore space being filled up with metallic silicon.
  • the advantage of this production technique is that, in contrast to the powder sintering techniques, the components do not undergo shrinkage during the siliconizing process. Therefore, extremely large or long absorber can be made with precise dimensions.
  • the field of application of the SISIC is indeed limited due to the melting point of the metallic silicon to about 1380 0 C, up to this temperature range, but has SISIC high strength and corrosion resistance coupled with good thermal shock resistance and wear resistance.
  • silicon carbides are characterized by properties such as high hardness, corrosion resistance even at high temperatures, high wear resistance, high strength even at high temperatures, oxidation resistance up to very high application temperatures, good thermal shock resistance, low thermal expansion and very high thermal conductivity.
  • the low thermal expansion is particularly advantageous if the absorber is tubular or, as provided in one embodiment of the invention, consists of a plurality of closely interconnected tubular elements.
  • Such absorbers are used in particular in solar power plants, which use parabolic internal collectors, which consist of curved mirrors, which focus the sunlight on an extending in the focal line absorber tube, which is fixed by brackets in the focal line of the collector.
  • the lengths of such collectors and thus also the length of the absorber tubes used can be between 20 and 150 meters, the individual interconnected tubular absorber elements usually having a length of approximately 2 to 4 meters.
  • the above-mentioned properties of silicon carbide allows a substantial abandonment of the measures provided for in the prior art for absorbing the elongation, supporting the weight and preventing the deformation at high temperatures of the absorber materials used.
  • connection of two tubular elements is effected by a plug connection.
  • This type of connection allows rapid assembly, but has the disadvantage that it is sensitive to longitudinal forces, which, however, occur only to a small extent by the inventive use of non-oxide ceramics with a low thermal expansion.
  • flange or screw for connecting two tubular elements.
  • metal clips are provided to secure a plug connection, which prevent longitudinal forces occurring in the absorber from disengaging the plug connections.
  • the individual tube segments can be made very accurately, which would even allow the individual tubular elements to be accurately and tightly interconnected without additional sealing , According to the invention, however, it can be provided that the sealing of the plug connections takes place by means of a silicone gasket, which is adapted to the tubular shape of the tubular elements, or that the sealing of the plug connection takes place by a refractory cement or adhesive.
  • SISIC reaction-bonded silicon-infiltrated silicon carbide
  • Liquid or gaseous heat transfer fluids such as water, liquid sodium, isobutane, thermal oil or superheated steam, etc. can be used as the heat-transporting medium.
  • thermal oil is used as a heat-transporting medium, temperatures of up to 390 0 C can be reached, which are used in a heat exchanger for steam generation and then fed to a conventional steam turbine.
  • superheated steam is used in direct steam generation, which does not require a heat exchanger, since the heated water vapor is produced directly in the absorber pipes and fed to a steam turbine, which allows temperatures above 500 ° C. when parabolic internal collectors are used.
  • the heat-transporting medium consists of silicone oil, which is characterized by a low volatility, low temperature coefficient of viscosity, fire safety and high resistance to acids and alkalis, but also has a high electrical resistance and a low surface tension.
  • silicone oil is odorless or tasteless and physiologically indifferent.
  • Figure 1 is a perspective view of a parabolic inner collector containing the absorber according to the invention
  • Figure 2 shows a cross section through the junction of two interconnected by a plug connection tubular absorber
  • Figure 3 is an enlarged view of the connector shown in Figure 2;
  • Figure 4 is an enlarged view of a connector according to another embodiment of the invention, similar to Figure 3;
  • FIG. 5 is an enlarged view of a connector according to another embodiment of the invention.
  • 1 shows a perspective view of a Parabolinnenkonverters 10.
  • the Parabolinnenkonverter 10 has an elongate reflector 12, which is usually made of glass, which is coated with silver and thus acts as a mirror.
  • the reflector 12 has the shape of a parabola, and in the focal line, not shown, of the reflector 12 is an existing of a plurality of individual absorber tube elements 16 elongated absorber 14, in which a heat-transporting medium, such as silicone oil, thermal oil or water vapor, circulated.
  • a heat-transporting medium such as silicone oil, thermal oil or water vapor
  • the reflector 12 constructed from a multiplicity of reflector elements 13 has a support structure 18, which consists essentially of a multiplicity of supports 20 fixed to the floor and a truss structure 22 attached thereto, which supports the individual reflector elements 13 in a manner free of deformation, as well as for the storage of Supporting elements 24 is used, with which the absorber tube 14 is always held in the focal line of the reflector 12.
  • rotary actuators are also provided which allow a pivoting movement of the truss structure 22 relative to the supports 20 on pivot bearings 26, one of which is shown.
  • a line system 32 which has an inlet 34, through which the heat-transporting medium is introduced into the absorber 14, and a drain 36, through which the heat-transporting medium is discharged.
  • a heat exchanger not shown, for steam generation, which is then fed to a conventional steam turbine, or if the superheated steam is generated directly in the absorber tubes, this directly fed to a steam turbine without the interposition of a heat exchanger.
  • FIG. 2 is a cross-section through a connection of two absorber tube elements 16, 16, which together form part of the absorber 14 in the present embodiment.
  • Each absorber tube element 16 is made of a non-porous / dense non-oxide ceramic based on silicon carbide, which is present in technical form and is dark.
  • the silicon carbide used has a very high hardness, corrosion resistance even at high temperatures, high wear resistance, high strength even at high temperatures, oxidation resistance up to high application temperatures, good thermal shock resistance, low thermal expansion, very high thermal conductivity and good tribulogical properties.
  • non-pressure sintered silicon carbide SSIC
  • reaction-bonded silicon-infiltrated silicon carbide SISIC
  • Si carbide has only a low thermal expansion
  • very long absorber 14 can be used with a corresponding number of individual absorber tube elements 16 without having to pay much attention to the axial extent of the absorber tube 14.
  • liquid phase sintered silicon carbide LPSIC
  • HPSIC hot pressed silicon carbide
  • HIPSIC hot isostatically pressed silicon carbide
  • the technical grade silicon carbide used is dark colored due to impurities present (light green / dark green, black, gray), depending on the degree of purity, so that it is not necessary to blacken the tubes extra, which also eliminates the need to prevent the ingress of oxygen by encapsulation in vacuum tubes, to prevent too rapid destruction of the absorber coating or dyeing, as in the state the technique is necessary.
  • the two absorber tubular members 16, 16 are connected by a plug-type connection in which a tip end 38 of an absorber tubular member 16 is inserted into the sleeve end 40 of an adjacent absorber tubular member 16, allowing for rapid assembly ,
  • the flow direction of the heat-transporting medium is shown in Figure 2 by an arrow 42 and extends from the socket end of a tubular element to its tip end.
  • the connector can be additionally secured by retaining clips, not shown, or retaining screws to prevent release of the connector.
  • Figure 3 shows an enlarged view of the connector of Figure 2, in which it can be seen that the connector is additionally sealed by a suitable ceramic or metal-ceramic adhesive 44 which contains no organic solvents, is not flammable and in temperature ranges well above 1000 0th C is usable.
  • a suitable ceramic or metal-ceramic adhesive 44 which contains no organic solvents, is not flammable and in temperature ranges well above 1000 0th C is usable.
  • other refractory adhesives or Dichtungskitte which have heat resistances up to 1700 0 C, or ceramic adhesives are used, which are introduced into the connection region of the two absorber tube elements in liquid form and after curing, the absorber tube elements 16 reliably connects ,
  • FIG. 4 shows an alternative embodiment of the invention in which two absorber tube elements 16, 16, as in FIG. 3, are connected to one another via a plug connection in which a tip end 38 of one absorber tube element 16 is inserted into the socket end 40 of the other absorber tube element. Tube member 16 is inserted.
  • a silicone gasket 46 is provided to seal the connector.
  • the tip end 38 of one absorber tube member 16 is provided with a phase 48 to facilitate insertion of the tip end 38 into the socket end 40 of the other absorber tube member 16 as well as a casserole aid for the Silicone seal 46 serve to not pinch this when inserting the tip end 38 in the socket end 40.
  • both the tip end 38 and the socket end 40 have a respective groove or recess 50 and 52, respectively, for receiving the silicone gasket 46 (shown as an O-ring in Figure 4) to provide additional fixation the two connected absorber tube elements 16, 16 to allow.
  • FIG. 5 shows a further embodiment of the invention in which two absorber tube elements 16, 16, as in FIG. 4, are connected to one another via a plug connection, in which a tip end 38 of one absorber tube element 16 is inserted into the socket end 40 of the other absorber tube element.
  • Tube member 16 is inserted, wherein the connector is sealed by a silicone seal 54.
  • this embodiment differs from the embodiment shown in Figure 4 in that the tip end 38 is not only phased, as shown in Figure 4, but with a bottle neck tapered tip end 38 and a correspondingly contrarotate formed trumpet-shaped sleeve end 40 is formed.
  • the elastomeric sleeve seal (silicone seal) 54 is not inserted in a groove or recess, but lies flat between the tip end 38 and the sleeve end 40 to seal the connection area.
  • the bottle-neck-like shape of the tip end 38 shown in FIG. 5 is chosen only by way of example and may be different depending on the sleeve seal used, for example with a longer or shorter neck, with different material thickness, etc.
  • this type of connector may additionally have a not shown retaining clip or retaining screw to be secured to prevent loosening of the connector.
  • sleeve ends 40 which is attached to one end of a respective absorber tube member 16 form these ends as tip ends and provide separate sleeves, which are pushed over the two pipe elements to be connected.
  • other types of compounds e.g. Flange or screw, depending on the material properties of the silicon carbide used in order to allow in this way higher pressures in the absorber.

Abstract

An absorber (14) for the conversion of solar rays into thermal energy, in particular for use in a solar collector (10), is proposed, said absorber (14) consisting of a non-porous dark ceramic and being flowed through by a heat-transporting medium.

Description

Absorber zur Umwandlung von Sonnenstrahlen in Wärmeenergie Absorber for converting sun rays into heat energy
Beschreibungdescription
Die Erfindung betrifft einen Absorber zur Umwandlung von Sonnenstrahlen in Wärmeenergie, insbesondere zur Verwendung in einem Sonnenkollektor, welcher von einem wärmetransportierenden Medium durchströmt wird.The invention relates to an absorber for the conversion of solar radiation into heat energy, in particular for use in a solar collector, which is traversed by a heat-transporting medium.
Sonnenkollektoren dienen dazu, Sonnenenergie in thermische Energie umzuwandeln und als solche nutzbar zu machen. Sie bestehen im Wesentlichen aus einem Absorber, welcher aus einem Material mit einer guten Wärmeleitfähigkeit, wie z.B. Kupfer oder Stahl, besteht, und einem Rohrleitungssystem, durch welches eine Flüssigkeit oder ein Gas die absorbierte Energie von dem Absorber zu einem Anwendungsort der erhaltenen Wärmeenergie transportiert. Zur Erhöhung der Betriebstemperatur eines Sonnenkollektors können zusätzlich optische Anlagen, wie z.B. Heliostate oder Parabolrinnen, eingesetzt werden, um die Sonnenstrahlen auf den Absorber zu fokussieren.Solar panels are used to convert solar energy into thermal energy and make it usable as such. They consist essentially of an absorber which is made of a material with a good thermal conductivity, e.g. Copper or steel, and a piping system through which a liquid or gas transports the absorbed energy from the absorber to an application site of the obtained thermal energy. To increase the operating temperature of a solar collector, optical systems, such as e.g. Heliostats or parabolic troughs, are used to focus the sun's rays on the absorber.
Absorber haben üblicherweise eine schwarze Oberfläche, was durch Aufbringen eines schwarz pigmentierten Lacks erreicht wird, um eine maximale Absorptionsfähigkeit von Sonnenenergie sicherzustellen. Nachteilig hierbei ist jedoch, dass dann, wenn der Absorber in einem Sonnenkollektor mit entsprechender Leistungsfähigkeit, wie z.B. einem solarthermischen Kraftwerk, verwendet wird, bei der großflächige optische Anlagen dazu verwendet werden, das einfallende Sonnenlicht auf den Absorber zu konzentrieren, um hohen Absorbertemperaturen zu erreichen, dies zu einer Zerstörung der Absorberbeschichtung bzw. Lackierung führen kann. Damit diese Beschichtung oder Lackierung und ihre Färbung nicht zu rasch zerstört wird, werden die Absorber daher ihrerseits in evakuierten Glasröhren gehalten, um einen Sauerstoffzutritt zu verhindern, was jedoch zum einen die Kosten erhöht und zum anderen eine regelmäßige Reinigung der evakuierten Glasröhren erfordert, da diese ansonsten selbst aufgeheizt und dadurch zerstört werden könnten, was jedoch eine Abschaltung der entsprechenden Anlage erforderlich machen kann.Absorbers usually have a black surface, which is achieved by applying a black pigmented paint to ensure maximum solar energy absorption capacity. The disadvantage here, however, that when the absorber is used in a solar collector with appropriate performance, such as a solar thermal power plant, be used in the large-scale optical systems to focus the incident sunlight on the absorber to achieve high absorber temperatures , this can lead to destruction of the absorber coating or painting. Thus, this coating or paint and their coloration is not destroyed too quickly, the absorbers are therefore in turn held in evacuated glass tubes to prevent oxygen access, but on the one hand increases the cost and on the other requires regular cleaning of the evacuated glass tubes, as these otherwise heated itself and thereby could be destroyed, but this may require a shutdown of the relevant system.
Demgegenüber ist es Aufgabe der Erfindung, einen von einem wärmetransportierenden Medium durchströmten Absorber zur Umwandlung von Sonnenstrahlen in Wärmeenergie bereitzustellen, insbesondere zur Verwendung in einem Sonnenkollektor, welcher auch bei Verwendung in Sonnenkollektoren hoher Leistung einen kostengünstigen und weitgehend wartungsfreien Einsatz erlauben.In contrast, it is an object of the invention to provide a traversed by a heat transport medium absorber for the conversion of solar radiation into heat energy, in particular for use in a solar collector, which allow a cost-effective and largely maintenance-free use even when used in solar panels high performance.
Diese Aufgabe wird erfindungsgemäß dadurch gelöst, dass der Absorber im Wesentlichen aus einer nicht-porösen Keramik aus dunklem Material besteht. Der zentrale Gedanke der Erfindung liegt nämlich darin, anstelle von Metallrohren mit einer dunklen, insbesondere schwarzen Lackierung oder Beschichtung nicht-poröse Keramikrohre zu verwenden, welche von Haus aus aus einem dunklen Material bestehen, was zum Einen den Vorteil hat, dass der Absorber nicht extra geschwärzt werden muss, und zum Anderen die Notwendigkeit beseitigt, den Sauerstoffzutritt durch Einkapseln in Vakuumröhren zu verhindern. Durch die Verwendung von Keramiken besteht darüber hinaus die Möglichkeit, Absorbertemperaturen bis weit über 400 0C, insbesondere bis 800 0C oder sogar darüber, abhängig von den verwendeten optischen Anlagen, zu erlauben.This object is achieved in that the absorber consists essentially of a non-porous ceramic made of dark material. The central idea of the invention is namely to use instead of metal pipes with a dark, especially black paint or coating non-porous ceramic pipes, which are made of a dark material, which on the one hand has the advantage that the absorber is not extra on the other hand eliminates the need to prevent the entry of oxygen by encapsulation in vacuum tubes. The use of ceramics also makes it possible to allow absorber temperatures of well above 400 ° C., in particular up to 800 ° C. or even higher, depending on the optical systems used.
Erfindungsgemäß wird dabei vorgeschlagen, dass die nicht-poröse bzw. dichte Keramik eine Nichtoxidkeramik auf der Basis von Siliciumcarbid (SIC) ist, insbesondere technisches Siliciumcarbid ist, welches u.a. eine hohe Wärmeleitfähigkeit und geringe Wärmeausdehnung besitzt und darüber hinaus auch bei sehr hohen Temperaturen einsetzbar ist. Technisches Siliciumcarbid ist wegen vorhandener Verunreinigung dunkel gefärbt (schwarz bis grün), wobei der Grad der Färbung mit Zunahme des Reinheitsgrads des Siliciumcarbids abnimmt. AIs besonders geeignete Nichtoxidkeramiken auf der Basis von Siliciumcarbid haben sich vor allem drucklos gesintertes Siliciumcarbid (SSIC) und reaktionsgebundenes siliciuminfiltriertes Siliciumcarbid (SISIC) herausgestellt, obwohl auch flüssigphasengesintertes Siliciumcarbid (LPSIC), heiß gepresstes Siliciumcarbid (HPSIC) sowie heiß isostatisch gespresstes Siliciumcarbid (HIPSIC) verwendbar sind.According to the invention it is proposed that the non-porous or dense ceramic is a non-oxide ceramic based on silicon carbide (SIC), in particular technical silicon carbide, which among other things has a high thermal conductivity and low thermal expansion and is also usable at very high temperatures , Technical grade silicon carbide is dark colored (black to green) due to contamination present, with the degree of coloration decreasing as the degree of purity of the silicon carbide increases. Especially suitable silicon carbide non-oxide ceramics have been found to be pressure-sintered silicon carbide (SSIC) and reaction bonded silicon-infiltrated silicon carbide (SISIC), although liquid phase sintered silicon carbide (LPSIC), hot pressed silicon carbide (HPSIC), and hot isostatic silicon carbide (HIPSIC). are usable.
Drucklos gesinteres Siliciumcarbid (SSIC) wird aus gemahlenem SIC- Feinstpulver hergestellt, das mit Sinteradditiven versetzt in den keramiküblichen Formgebungsvarianten verarbeitet und bei 2000 bis 2200 0C unter Schutzgas gesintert wird. SSIC zeichnet sich durch eine hohe Festigkeit aus, die bis zu hohen Temperaturen von ca. 1600 0C nahezu konstant bleibt. Dieser Werkstoff besitzt darüber hinaus eine hohe Temperaturwechselbeständigkeit, hohe Wärmeleitfähigkeit, hohe Verschleißbeständigkeit und eine diamantähnliche Härte.Pressureless gesinteres silicon carbide (SSiC) is produced from ground SIC very fine powder, the sintering additives to put in the ceramic customary shaping variants processed and sintered at 2000 to 2200 0 C under a protective gas. SSIC is characterized by a high strength, which remains almost constant up to high temperatures of about 1600 0 C. In addition, this material has a high thermal shock resistance, high thermal conductivity, high wear resistance and a diamond-like hardness.
Demgegenüber besteht reaktionsgebundenes siliciuminfiltriertes Siliciumcarbid (SISIC) beispielsweise zu ca. 85 bis 94 % aus SIC und entsprechend aus 15 bis 6 % metallischem Silicium (Si). Darüber hinaus besitzt SICIC praktisch keine Restporosität. Dies wird erreicht, indem ein Formkörper aus Siliciumcarbid und Kohlenstoff mit metallischem Silicium infiltriert wird. Die Reaktion zwischen flüssigem Silicium und dem Kohlenstoff führt zu einer SIC-Bindungsmatrix, wobei der restliche Porenraum mit metallischem Silicium aufgefüllt wird. Vorteil dieser Herstellungstechnik ist, dass im Gegensatz zu den Pulversintertechniken die Bauteile während des Silicierungsprozesses keine Schwindungen erfahren. Daher können außerordentlich große bzw. lange Absorber mit präzisen Abmessungen hergestellt werden. Der Einsatzbereich des SISIC ist zwar aufgrund des Schmelzpunktes des metallischen Siliciums auf ca. 1380 0C begrenzt, bis zu diesem Temperaturbereich besitzt SISIC jedoch eine hohe Festigkeit und Korrosionsbeständigkeit verbunden mit guter Temperaturwechselbeständigkeit und Verschleißbeständigkeit. Zusammenfassend zeichnen sich Siliciumcarbide somit durch Eigenschaften aus, wie hohe Härte, Korrosionsbeständigkeit auch bei hohen Temperaturen, hohe Verschleißfestigkeit, hohe Festigkeit auch bei hohen Temperaturen, Oxidationsbeständigkeit bis zu sehr hohen Anwendungstemperaturen, gute Temperaturwechselbeständigkeit, geringe Wärmedehnung und sehr hohe Wärmeleitfähigkeit. Insbesondere die geringe Wärmedehnung ist besonders vorteilhaft, wenn der Absorber rohrförmig ausgebildet ist oder, wie in einer Ausführungsform der Erfindung vorgesehen, aus einer Mehrzahl dicht miteinander verbundener rohrförmiger Elemente besteht. Derartige Absorber werden insbesondere bei Solarkraftwerken eingesetzt, welche Parabolinnenkollektoren verwenden, die aus gewölbten Spiegeln bestehen, die das Sonnenlicht auf ein in der Brennlinie verlaufendes Absorberrohr bündeln, welches über Halterungen in der Brennlinie des Kollektors fixiert ist. Die Längen solcher Kollektoren und damit auch die Länge der verwendeten Absorberrohre können je nach Bautyp zwischen 20 und 150 Metern betragen, wobei die einzelnen miteinander verbundenen rohrförmigen Absorberelemente üblicherweise eine Länge von etwa 2 bis 4 Metern besitzen. Darüber hinaus erlaubt die oben angeführten Eigenschaften von Siliciumcarbid einen weitgehenden Verzicht auf die beim Stand der Technik vorgesehenen Maßnahmen zur Aufnahme der Längendehnung, Abstützung des Gewichts und Verhinderung der Verformung bei hohen Temperaturen der verwendeten Absorbermaterialien .By contrast, reaction-bonded silicon-infiltrated silicon carbide (SISIC) comprises, for example, about 85 to 94% SIC and, correspondingly, 15 to 6% metallic silicon (Si). In addition, SICIC has virtually no residual porosity. This is accomplished by infiltrating a silicon carbide and carbon mold with metallic silicon. The reaction between liquid silicon and the carbon results in an SIC bond matrix, with the remaining pore space being filled up with metallic silicon. The advantage of this production technique is that, in contrast to the powder sintering techniques, the components do not undergo shrinkage during the siliconizing process. Therefore, extremely large or long absorber can be made with precise dimensions. The field of application of the SISIC is indeed limited due to the melting point of the metallic silicon to about 1380 0 C, up to this temperature range, but has SISIC high strength and corrosion resistance coupled with good thermal shock resistance and wear resistance. In summary, silicon carbides are characterized by properties such as high hardness, corrosion resistance even at high temperatures, high wear resistance, high strength even at high temperatures, oxidation resistance up to very high application temperatures, good thermal shock resistance, low thermal expansion and very high thermal conductivity. In particular, the low thermal expansion is particularly advantageous if the absorber is tubular or, as provided in one embodiment of the invention, consists of a plurality of closely interconnected tubular elements. Such absorbers are used in particular in solar power plants, which use parabolic internal collectors, which consist of curved mirrors, which focus the sunlight on an extending in the focal line absorber tube, which is fixed by brackets in the focal line of the collector. Depending on the type of construction, the lengths of such collectors and thus also the length of the absorber tubes used can be between 20 and 150 meters, the individual interconnected tubular absorber elements usually having a length of approximately 2 to 4 meters. In addition, the above-mentioned properties of silicon carbide allows a substantial abandonment of the measures provided for in the prior art for absorbing the elongation, supporting the weight and preventing the deformation at high temperatures of the absorber materials used.
Um eine einfache Verbindung einer Mehrzahl rohrförmig ausgebildeter Absorber zu einem einzigen Absorberelement zu ermöglichen, kann erfindungsgemäß vorgesehen sein, dass die Verbindung zweier rohrförmiger Elemente durch eine Steckverbindung erfolgt. Diese Art der Verbindung erlaubt eine schnelle Montage, hat jedoch den Nachteil, dass sie gegenüber Längskräften empfindlich ist, welche jedoch durch die erfindungsgemäße Verwendung von Nichtoxidkeramiken mit einer geringen Wärmedehnung nur in geringem Maße auftreten. Jedoch ist es auch denkbar, Flansch- oder Schraubverbindungen zur Verbindung zweier rohrförmiger Elemente zu verwenden.In order to enable a simple connection of a plurality of tubular absorbers formed to a single absorber element, it can be provided according to the invention that the connection of two tubular elements is effected by a plug connection. This type of connection allows rapid assembly, but has the disadvantage that it is sensitive to longitudinal forces, which, however, occur only to a small extent by the inventive use of non-oxide ceramics with a low thermal expansion. However, it is too conceivable to use flange or screw for connecting two tubular elements.
Zusätzlich kann jedoch auch vorgesehen sein, dass zur Sicherung einer Steckverbindung Metallklammern vorgesehen sind, welche verhindern, dass im Absorber auftretende Längskräfte die Steckverbindungen lösen.In addition, however, it can also be provided that metal clips are provided to secure a plug connection, which prevent longitudinal forces occurring in the absorber from disengaging the plug connections.
Aufgrund der Eigenschaften von Siliciumcarbid, beispielsweise reaktionsgebundenem siliciuminfiltriertem Siliciumcarbid (SISIC), welches während des Herstellungsprozesses keine Schwindungen erfährt, können die einzelnen Rohrsegmente sehr genau hergestellt werden, was es sogar ermöglichen würde, die einzelnen rohrförmigen Elemente ohne zusätzliche Abdichtung passgenau und dicht miteinander zu verbinden. Erfindungsgemäß kann jedoch vorgesehen sein, dass die Abdichtung der Steckverbindungen mittels einer Silikondichtung erfolgt, welche an die Rohrform der rohrförmigen Elemente angepasst ist, oder dass die Abdichtung der Steckverbindung durch einen feuerfesten Kitt oder Kleber erfolgt.Due to the properties of silicon carbide, such as reaction-bonded silicon-infiltrated silicon carbide (SISIC), which does not shrink during the manufacturing process, the individual tube segments can be made very accurately, which would even allow the individual tubular elements to be accurately and tightly interconnected without additional sealing , According to the invention, however, it can be provided that the sealing of the plug connections takes place by means of a silicone gasket, which is adapted to the tubular shape of the tubular elements, or that the sealing of the plug connection takes place by a refractory cement or adhesive.
Als wärmetransportierendes Medium können flüssige oder gasförmige Wärmeträgerfluide, wie Wasser, flüssiges Natrium, Isobutan, Thermoöl oder überhitzter Wasserdampf usw. zum Einsatz kommen. Wird Thermoöl als wärmetransportierendes Medium verwendet, sind Temperaturen von bis zu 390 0C erreichbar, die in einem Wärmetauscher zur Dampferzeugung genutzt werden und dann einer konventionellen Dampfturbine zugeführt werden. Überhitzter Wasserdampf hingegen wird bei der Direktdampferzeugung verwendet, welche ohne Wärmetauscher auskommt, da der erhitzte Wasserdampf direkt in den Absorberrohren erzeugt und einer Dampfturbine zugeführt wird, was Temperaturen über 500 0C ermöglicht, wenn Parabolinnenkollektoren verwendet werden. Wenn darüber hinaus der erfindungsgemäße Absorber bei Solarkraftwerken verwendet wird, bei dem die Sonnenstrahlung mithilfe hunderter bis tausender automatisch positionierter Spiegel (Heliostaten) auf einen zentralen Absorber konzentriert wird, sind maximale Temperaturen von ca. 1300 0C möglich.Liquid or gaseous heat transfer fluids, such as water, liquid sodium, isobutane, thermal oil or superheated steam, etc. can be used as the heat-transporting medium. If thermal oil is used as a heat-transporting medium, temperatures of up to 390 0 C can be reached, which are used in a heat exchanger for steam generation and then fed to a conventional steam turbine. By contrast, superheated steam is used in direct steam generation, which does not require a heat exchanger, since the heated water vapor is produced directly in the absorber pipes and fed to a steam turbine, which allows temperatures above 500 ° C. when parabolic internal collectors are used. In addition, when the absorber according to the invention is used in solar power plants, in which the solar radiation with the help of hundreds to thousands automatically If a positioned mirror (heliostat) is concentrated on a central absorber, maximum temperatures of about 1300 ° C. are possible.
Erfindungsgemäß kann zusätzlich vorgesehen sein, dass das wärmetransportierende Medium aus Silikonöl besteht, welches sich durch eine geringe Flüchtigkeit, kleinen Temperaturkoeffizienten der Viskosität, Feuersicherheit und hohe Resistenz gegenüber Säuren und Laugen auszeichnet, jedoch auch einen hohen elektrischen Widerstand und eine niedrige Oberflächenspannung besitzt. Zudem ist Silikonöl geruchs- oder geschmacksneutral sowie physiologisch indifferent. Durch die Verwendung des erfindungsgemäßen Absorbers mit einem auf Silikonöl basierenden wärmetransportierenden Medium lassen sich Temperaturen bis weit über 400 °C, insbesondere bis 800 0C, gelegentlich sogar darüber, realisieren.According to the invention may additionally be provided that the heat-transporting medium consists of silicone oil, which is characterized by a low volatility, low temperature coefficient of viscosity, fire safety and high resistance to acids and alkalis, but also has a high electrical resistance and a low surface tension. In addition, silicone oil is odorless or tasteless and physiologically indifferent. By using the absorber according to the invention with a medium based on silicone oil heat transporting temperatures up to well above 400 ° C, especially up to 800 0 C, sometimes even more realize.
Ausführungsbeispiele der Erfindung werden im Folgenden unter Bezugnahme auf die Figuren näher erläutert. Es stellen dar:Embodiments of the invention are explained in more detail below with reference to the figures. They show:
Figur 1 eine perspektivische Darstellung eines Parabolinnenkollektors, welcher den erfindungsgemäßen Absorber enthält;Figure 1 is a perspective view of a parabolic inner collector containing the absorber according to the invention;
Figur 2 einen Querschnitt durch die Verbindungsstelle zweier durch eine Steckverbindung miteinander verbundener rohrförmiger Absorber;Figure 2 shows a cross section through the junction of two interconnected by a plug connection tubular absorber;
Figur 3 eine vergrößerte Ansicht der in Figur 2 dargestellten Steckverbindung;Figure 3 is an enlarged view of the connector shown in Figure 2;
Figur 4 eine vergrößerte Ansicht einer Steckverbindung gemäß einer weiteren Ausführungsform der Erfindung, ähnlich der Figur 3; undFigure 4 is an enlarged view of a connector according to another embodiment of the invention, similar to Figure 3; and
Figur 5 eine vergrößerte Ansicht einer Steckverbindung gemäß einer weiteren Ausführungsform der Erfindung. Figur 1 zeigt eine perspektivische Darstellung eines Parabolinnenkonverters 10. Der Parabolinnenkonverter 10 besitzt einen langgestreckten Reflektor 12, der in der Regel aus Glas besteht, welches mit Silber beschichtet ist und somit als Spiegel wirkt. Im Querschnitt besitzt der Reflektor 12 die Form einer Parabel, und in der nicht dargestellten Brennlinie des Reflektors 12 befindet sich ein aus einer Vielzahl einzelner Absorber-Rohrelemente 16 bestehender langgestreckter Absorber 14, in dem ein wärmetransportierendes Medium, wie beispielsweise Silikonöl, Thermoöl oder Wasserdampf, zirkuliert. Der Wärmeträger und der Aufbau des Absorberrohrs 14 sind in Figur 1 nicht dargestellt.Figure 5 is an enlarged view of a connector according to another embodiment of the invention. 1 shows a perspective view of a Parabolinnenkonverters 10. The Parabolinnenkonverter 10 has an elongate reflector 12, which is usually made of glass, which is coated with silver and thus acts as a mirror. In cross-section, the reflector 12 has the shape of a parabola, and in the focal line, not shown, of the reflector 12 is an existing of a plurality of individual absorber tube elements 16 elongated absorber 14, in which a heat-transporting medium, such as silicone oil, thermal oil or water vapor, circulated. The heat transfer medium and the structure of the absorber tube 14 are not shown in FIG.
Der aus einer Vielzahl von Reflektorelementen 13 aufgebaute Reflektor 12 besitzt eine Tragstruktur 18, welche im Wesentlichen aus einer Vielzahl von am Boden befestigten Trägern 20 besteht und einer an diesen befestigten Fachwerkstruktur 22, welche sowohl die einzelnen Reflektorelemente 13 verformungsfrei abstützt, als auch zur Lagerung von Tragelementen 24 dient, mit denen das Absorberrohr 14 stets in der Brennlinie des Reflektors 12 gehalten wird. Um eine Nachführung des Reflektors 12 nach der Sonne zu ermöglichen, sind darüber hinaus nicht dargestellte Drehantriebe vorgesehen, welche eine Schwenkbewegung der Fachwerkstruktur 22 gegenüber den Trägern 20 an Schwenklagern 26, von denen eines dargestellt ist, erlauben.The reflector 12 constructed from a multiplicity of reflector elements 13 has a support structure 18, which consists essentially of a multiplicity of supports 20 fixed to the floor and a truss structure 22 attached thereto, which supports the individual reflector elements 13 in a manner free of deformation, as well as for the storage of Supporting elements 24 is used, with which the absorber tube 14 is always held in the focal line of the reflector 12. In order to enable a tracking of the reflector 12 to the sun, not shown rotary actuators are also provided which allow a pivoting movement of the truss structure 22 relative to the supports 20 on pivot bearings 26, one of which is shown.
An den entgegengesetzten Enden 28 und 30 des Absorbers 14 ist dieser mit einem Leitungssystem 32 verbunden, welches einen Zulauf 34 aufweist, durch den das wärmetransportierende Medium in den Absorber 14 eingeleitet wird, sowie einen Ablauf 36 aufweist, durch den das wärmetransportierende Medium abgeführt wird. Abhängig von dem verwendeten wärmetransportierenden Medium ist es darüber hinaus möglich, das wärmetransportierende Medium entweder zuerst einem nicht dargestellten Wärmetauscher zur Dampferzeugung zuzuführen, welcher dann einer konventionellen Dampfturbine zugeführt wird, oder wenn der überhitzte Wasserdampf direkt in den Absorberrohren erzeugt wird, diesen direkt einer Dampfturbine zuzuführen ohne Zwischenschaltung eines Wärmetauschers.At the opposite ends 28 and 30 of the absorber 14, this is connected to a line system 32, which has an inlet 34, through which the heat-transporting medium is introduced into the absorber 14, and a drain 36, through which the heat-transporting medium is discharged. Depending on the heat-transporting medium used, it is also possible to supply the heat-transporting medium either first a heat exchanger, not shown, for steam generation, which is then fed to a conventional steam turbine, or if the superheated steam is generated directly in the absorber tubes, this directly fed to a steam turbine without the interposition of a heat exchanger.
Figur 2 ist eine Querschnitt durch eine Verbindung zweier Absorber- Rohrelemente 16,16, die in der vorliegenden Ausführungsform gemeinsam Teil des Absorber 14 sind. Jedes Absorber-Rohrelement 16 besteht aus einer nicht-porösen/dichten Nichtoxidkeramik auf der Basis von Siliciumcarbid, welches in technischer Form vorliegt und dunkel ist. Das verwendete Siliciumcarbid besitzt eine sehr hohe Härte, Korrosionsbeständigkeit auch bei hohen Temperaturen, hohe Verschleißbeständigkeit, hohe Festigkeit auch bei hohen Temperaturen, Oxidationsbeständigkeit bis zu hohen Anwendungstemperaturen, gute Temperaturwechselbeständigkeit, geringe Wärmedehnung, sehr hohe Wärmeleitfähigkeit und gute tribulogische Eigenschaften.FIG. 2 is a cross-section through a connection of two absorber tube elements 16, 16, which together form part of the absorber 14 in the present embodiment. Each absorber tube element 16 is made of a non-porous / dense non-oxide ceramic based on silicon carbide, which is present in technical form and is dark. The silicon carbide used has a very high hardness, corrosion resistance even at high temperatures, high wear resistance, high strength even at high temperatures, oxidation resistance up to high application temperatures, good thermal shock resistance, low thermal expansion, very high thermal conductivity and good tribulogical properties.
Bevorzugt wird drucklos gesintertes Siliciumcarbid (SSIC) und reaktionsgebundenes siliciuminfiltriertes Siliciumcarbid (SISIC) verwendet, welches infolge seines Herstellungsverfahrens Bauteile ermöglicht, die während des Silicierungsprozesses keine Schwindung erfahren, wodurch außerordentlich große Bauteile mit präzisen Abmessungen hergestellt werden können. Da darüber hinaus Siliciumcarbid nur eine geringe Wärmedehnung besitzt, können auch sehr lange Absorber 14 mit entsprechend vielen einzelnen Absorber-Rohrelementen 16 verwendet werden, ohne der axialen Ausdehnung des Absorberrohrs 14 große Beachtung schenken zu müssen.Preferably, non-pressure sintered silicon carbide (SSIC) and reaction-bonded silicon-infiltrated silicon carbide (SISIC) is used which, as a result of its manufacturing process, allows components that do not shrink during the siliconization process, thereby allowing extremely large components to be manufactured to precise dimensions. In addition, since silicon carbide has only a low thermal expansion, very long absorber 14 can be used with a corresponding number of individual absorber tube elements 16 without having to pay much attention to the axial extent of the absorber tube 14.
Alternativ kann jedoch auch flüssigphasengesintertes Siliciumcarbid (LPSIC) oder heiß gepresstes Siliciumcarbid (HPSIC) sowie heiß isostatisch gepresstes Siliciumcarbid (HIPSIC) verwendet werden, welche auch zur Gruppe der dichten bzw. nicht-porösen Siliciumcarbide gehören.Alternatively, however, liquid phase sintered silicon carbide (LPSIC) or hot pressed silicon carbide (HPSIC) and hot isostatically pressed silicon carbide (HIPSIC) may also be used, which also belong to the group of dense or non-porous silicon carbides.
Das verwendete technische Siliciumcarbid ist aufgrund vorhandener Verunreinigungen dunkel gefärbt (hellgrün/dunkelgrün, schwarz, grau), abhängig vom Reinheitsgrad, sodass es nicht erforderlich ist, die Röhren noch extra zu schwärzen, womit auch die Notwendigkeit entfällt, den Sauerstoffzutritt durch Einkapseln in Vakuumröhren zu verhindern, um eine zu rasche Zerstörung der Absorberbeschichtung bzw. -färbung zu verhindern, wie es beim Stand der Technik notwendig ist.The technical grade silicon carbide used is dark colored due to impurities present (light green / dark green, black, gray), depending on the degree of purity, so that it is not necessary to blacken the tubes extra, which also eliminates the need to prevent the ingress of oxygen by encapsulation in vacuum tubes, to prevent too rapid destruction of the absorber coating or dyeing, as in the state the technique is necessary.
Wie in Figur 2 zu sehen ist, sind die zwei Absorber-Rohrelemente 16, 16 durch eine Steckverbindung verbunden, bei der ein Spitzenende 38 eines Absorber-Rohrelements 16 in das Muffenende 40 eines angrenzenden Absorber-Rohrelements 16 eingefügt wird, was eine schnelle Montage erlaubt. Die Strömungsrichtung des wärmetransportierenden Mediums ist in Figur 2 durch einen Pfeil 42 dargestellt und verläuft vom Muffenende eines Rohrelements zu seinem Spitzenende. Darüber hinaus kann die Steckverbindung zusätzlich über nicht dargestellte Halteklammern oder Halteschrauben abgesichert sein, um ein Lösen der Steckverbindung zu verhindern.As can be seen in Figure 2, the two absorber tubular members 16, 16 are connected by a plug-type connection in which a tip end 38 of an absorber tubular member 16 is inserted into the sleeve end 40 of an adjacent absorber tubular member 16, allowing for rapid assembly , The flow direction of the heat-transporting medium is shown in Figure 2 by an arrow 42 and extends from the socket end of a tubular element to its tip end. In addition, the connector can be additionally secured by retaining clips, not shown, or retaining screws to prevent release of the connector.
Figur 3 zeigt eine vergrößerte Darstellung der Steckverbindung der Figur 2, in welcher zu erkennen ist, dass die Steckverbindung zusätzlich durch einen geeigneten Keramik- oder Metallkeramikklebstoff 44 abgedichtet ist, welcher keine organischen Lösemittel enthält, nicht brennbar ist und in Temperaturbereiche bis weit über 1000 0C verwendbar ist. Alternativ können jedoch auch andere feuerfeste Klebstoffe oder Dichtungskitte, welche Temperaturbeständigkeiten bis 1700 0C besitzen, bzw. keramische Klebmassen verwendet werden, welche in den Verbindungsbereich der zwei Absorber-Rohrelemente in flüssiger Form eingebracht werden und nach dem Aushärten die Absorber-Rohrelemente 16 zuverlässig verbindet.Figure 3 shows an enlarged view of the connector of Figure 2, in which it can be seen that the connector is additionally sealed by a suitable ceramic or metal-ceramic adhesive 44 which contains no organic solvents, is not flammable and in temperature ranges well above 1000 0th C is usable. Alternatively, however, other refractory adhesives or Dichtungskitte which have heat resistances up to 1700 0 C, or ceramic adhesives are used, which are introduced into the connection region of the two absorber tube elements in liquid form and after curing, the absorber tube elements 16 reliably connects ,
Figur 4 zeigt eine alternative Ausführungsform der Erfindung, in welcher zwei Absorber-Rohrelemente 16, 16, wie in Figur 3, über eine Steckverbindung miteinander verbunden sind, bei der ein Spitzenende 38 des einen Absorber-Rohrelements 16 in das Muffenende 40 des anderen Absorber-Rohrelements 16 eingeführt ist. Zusätzlich ist jedoch bei dieser Ausführungsform eine Silikondichtung 46 vorgesehen, um die Steckverbindung abzudichten. In der in Figur 4 dargestellten Ausführungsform ist das Spitzenende 38 des einen Absorber-Rohrelements 16 mit einer Phase 48 versehen, um zum einen das Einführen des Spitzenendes 38 in das Muffenende 40 des anderen Absorber- Rohrelements 16 zu erleichtern, als auch als Auflaufhilfe für die Silikondichtung 46 zu dienen, um diese beim Einführen des Spitzenendes 38 in das Muffenende 40 nicht zu klemmen. Bei der dargestellten Ausführungsform weist sowohl das Spitzenende 38 als auch das Muffenende 40 eine jeweilige Nut bzw. Ausnehmung 50 bzw. 52 zur Aufnahme der Silikondichtung 46 (welche in Figur 4 als O-Ring dargestellt ist) auf, um auf diese Weise eine zusätzliche Fixierung der zwei miteinander verbundenen Absorber-Rohrelemente 16, 16 zu ermöglichen.FIG. 4 shows an alternative embodiment of the invention in which two absorber tube elements 16, 16, as in FIG. 3, are connected to one another via a plug connection in which a tip end 38 of one absorber tube element 16 is inserted into the socket end 40 of the other absorber tube element. Tube member 16 is inserted. In addition, however, this is Embodiment, a silicone gasket 46 is provided to seal the connector. In the embodiment shown in Figure 4, the tip end 38 of one absorber tube member 16 is provided with a phase 48 to facilitate insertion of the tip end 38 into the socket end 40 of the other absorber tube member 16 as well as a casserole aid for the Silicone seal 46 serve to not pinch this when inserting the tip end 38 in the socket end 40. In the illustrated embodiment, both the tip end 38 and the socket end 40 have a respective groove or recess 50 and 52, respectively, for receiving the silicone gasket 46 (shown as an O-ring in Figure 4) to provide additional fixation the two connected absorber tube elements 16, 16 to allow.
Figur 5 zeigt eine weitere Ausführungsform der Erfindung, in welcher zwei Absorber-Rohrelemente 16, 16, wie in Figur 4, über eine Steckverbindung miteinander verbunden sind, bei der ein Spitzenende 38 des einen Absorber-Rohrelements 16 in das Muffenende 40 des anderen Absorber- Rohrelements 16 eingeführt ist, wobei die Steckverbindung über eine Silikondichtung 54 abgedichtet ist. Jedoch unterscheidet sich diese Ausführungform gegenüber der in Figur 4 dargestellten Ausführungform dadurch, dass das Spitzenende 38 nicht nur angephast ist, wie in Figur 4 dargestellt, sondern mit einem flaschenhalsförmig verjüngenden Spitzenende 38 und einem entsprechend konträr ausgebildeten trompetenförmigen Muffenende 40 ausgebildet ist. Darüber hinaus ist bei dieser Ausführungform die elastomere Muffendichtung (Silikondichtung) 54 nicht in eine Nut bzw. Ausnehmung eingelegt, sondern liegt flächig zwischen dem Spitzenende 38 und dem Muffenende 40 an, um den Verbindungsbereich abzudichten.FIG. 5 shows a further embodiment of the invention in which two absorber tube elements 16, 16, as in FIG. 4, are connected to one another via a plug connection, in which a tip end 38 of one absorber tube element 16 is inserted into the socket end 40 of the other absorber tube element. Tube member 16 is inserted, wherein the connector is sealed by a silicone seal 54. However, this embodiment differs from the embodiment shown in Figure 4 in that the tip end 38 is not only phased, as shown in Figure 4, but with a bottle neck tapered tip end 38 and a correspondingly contrarotate formed trumpet-shaped sleeve end 40 is formed. Moreover, in this embodiment, the elastomeric sleeve seal (silicone seal) 54 is not inserted in a groove or recess, but lies flat between the tip end 38 and the sleeve end 40 to seal the connection area.
Bei der Montage der elastomeren Muffendichtung 54 wird diese "trocken" auf das Spitzenende 38 des einen (linken) Absorber-Rohrelements 16 gesteckt, dann außen mit einem Gleitmittel eingestrichen, desgleichen die Innenseite des Muffenendes 40 des anderen (rechten) Absorber- Rohrelements 16. Nun wird das (linke) Absorber-Rohrelement 16 mit der aufgesteckten Dichtung auf das Muffenende 40 des anderen (rechten) Absorber-Rohrelements 16 aufgesetzt und mitsamt der Muffendichtung 54 in das Muffenende 40 hineingedrückt, wobei sich das Spitzenende 38 durch die konische Form der Muffendichtung 54 in dem Muffenende 40 zentriert.When mounting the elastomeric sleeve seal 54, this is "dry" stuck to the tip end 38 of the one (left) absorber tube member 16, then coated on the outside with a lubricant, likewise the Inside the sleeve end 40 of the other (right) absorber tube member 16. Now, the (left) absorber tube member 16 is placed with the attached seal on the sleeve end 40 of the other (right) absorber tube member 16 and together with the sleeve seal 54 in the socket end 40, wherein the tip end 38 centered by the conical shape of the sleeve seal 54 in the sleeve end 40.
Die in der Figur 5 dargestellte flaschenhalsförmige Form des Spitzenendes 38 ist nur beispielhaft gewählt und kann abhängig von der verwendeten Muffendichtung andersartig ausgebildet sein, beispielsweise mit einem längeren oder kürzeren Hals, mit unterschiedlicher Materialstärke usw. Darüber hinaus kann auch diese Art von Steckverbindung zusätzlich über eine nicht dargestellte Halteklammer oder Halteschraube abgesichert sein, um ein Lösen der Steckverbindung zu verhindern.The bottle-neck-like shape of the tip end 38 shown in FIG. 5 is chosen only by way of example and may be different depending on the sleeve seal used, for example with a longer or shorter neck, with different material thickness, etc. In addition, this type of connector may additionally have a not shown retaining clip or retaining screw to be secured to prevent loosening of the connector.
Darüber hinaus ist es jedoch auch möglich, anstelle der Muffenenden 40, welche an einem Ende eines jeweiligen Absorber-Rohrelements 16 angebracht ist, diese Enden als Spitzenenden auszubilden und separate Muffen vorzusehen, welche über die zwei zu verbindenden Rohrelemente geschoben werden. Alternativ ist es jedoch auch möglich, andere Arten von Verbindungen, wie z.B. Flansch- oder Schraubverbindungen, zu verwenden, abhängig von den Materialeigenschaften des verwendeten Siliciumcarbids, um auf diese Weise höhere Drücke in dem Absorber zu ermöglichen. In addition, however, it is also possible, instead of the sleeve ends 40, which is attached to one end of a respective absorber tube member 16, form these ends as tip ends and provide separate sleeves, which are pushed over the two pipe elements to be connected. Alternatively, however, it is also possible to use other types of compounds, e.g. Flange or screw, depending on the material properties of the silicon carbide used in order to allow in this way higher pressures in the absorber.

Claims

Ansprüche claims
1. Absorber zur Umwandlung von Sonnenstrahlen in Wärmeenergie, insbesondere zur Verwendung in einem Sonnenkollektor (10), welcher von einem wärmetransportierenden Medium durchströmt wird, dadurch gekennzeichnet, dass der Absorber (14) im Wesentlichen aus einer nicht-porösen, dunklen Keramik besteht.1. absorber for the conversion of solar radiation into heat energy, in particular for use in a solar collector (10), which is traversed by a heat-transporting medium, characterized in that the absorber (14) consists essentially of a non-porous, dark ceramic.
2. Absorber nach Anspruch 1 , dadurch gekennzeichnet, dass die nicht-poröse Keramik eine Nichtoxidkeramik auf der Basis von Siliciumcarbid ist.2. An absorber according to claim 1, characterized in that the non-porous ceramic is a non-oxide ceramic based on silicon carbide.
3. Absorber nach Anspruch 2, dadurch gekennzeichnet, dass das Siliciumcarbid in technischer Form vorliegt.3. absorber according to claim 2, characterized in that the silicon carbide is present in a technical form.
4. Absorber nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass der Absorber (14) rohrförmig ausgebildet ist.4. Absorber according to one of the preceding claims, characterized in that the absorber (14) is tubular.
5. Absorber nach Anspruch 4, dadurch gekennzeichnet, dass der Absorber (14) aus einer Mehrzahl dicht miteinander verbundener rohrförmiger Elemente (16, 16) besteht.5. An absorber according to claim 4, characterized in that the absorber (14) consists of a plurality of closely interconnected tubular elements (16, 16).
6. Absorber nach Anspruch 5, dadurch gekennzeichnet, dass die Verbindung zweier rohrförmiger Elemente (16, 16) durch eine Steckverbindung erfolgt. 6. absorber according to claim 5, characterized in that the connection of two tubular elements (16, 16) takes place by a plug connection.
7. Absorber nach Anspruch 6, dadurch gekennzeichnet, dass zur Sicherung einer Steckverbindung Metallklammern vorgesehen sind.7. absorber according to claim 6, characterized in that metal clips are provided for securing a plug connection.
8. Absorber nach Anspruch 6 oder 7, dadurch gekennzeichnet, dass die Abdichtung der Steckverbindung mittels einer Silikondichtung (46) erfolgt.8. absorber according to claim 6 or 7, characterized in that the sealing of the connector by means of a silicone seal (46).
9. Absorber nach Anspruch 6 oder 7 , dadurch gekennzeichnet, dass die Abdichtung der Steckverbindung durch einen feuerfesten Kitt oder Kleber (44) erfolgt.9. absorber according to claim 6 or 7, characterized in that the sealing of the connector by a refractory cement or adhesive (44).
10. Absorber nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass ein Sonnenstrahlen auf den Absorber (14) reflektierender Spiegel (12) vorgesehen ist.10. An absorber according to one of the preceding claims, characterized in that a sun rays on the absorber (14) reflecting mirror (12) is provided.
11. Absorber nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass das wärmetransportierende Medium vorzugsweise aus Silikonöl besteht. 11. An absorber according to one of the preceding claims, characterized in that the heat-transporting medium is preferably made of silicone oil.
EP06818771A 2005-11-23 2006-11-23 Absorber for the conversion of solar rays into thermal energy Withdrawn EP2102562A1 (en)

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DE102005055858A DE102005055858A1 (en) 2005-11-23 2005-11-23 Absorber for conversion of solar radiation into thermal energy consists mainly of non-porous dark ceramic material
PCT/EP2006/011251 WO2007059972A1 (en) 2005-11-23 2006-11-23 Absorber for the conversion of solar rays into thermal energy

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EP (1) EP2102562A1 (en)
CN (1) CN101351674A (en)
AU (1) AU2006316742C1 (en)
DE (1) DE102005055858A1 (en)
EG (1) EG25698A (en)
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DE102005055858A1 (en) 2007-05-24
CN101351674A (en) 2009-01-21
US20110017204A1 (en) 2011-01-27
AU2006316742A1 (en) 2007-05-31
EG25698A (en) 2012-05-22
RU2008125102A (en) 2009-12-27
IL191607A0 (en) 2008-12-29
AU2006316742C1 (en) 2012-03-01
US20090114281A1 (en) 2009-05-07
IL191607A (en) 2014-09-30
AU2006316742B2 (en) 2011-09-22
WO2007059972A1 (en) 2007-05-31
ZA200805387B (en) 2009-10-28

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