ITMI20122162A1 - SOLAR ABSORBER INCLUDING TAB2 - Google Patents
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- ITMI20122162A1 ITMI20122162A1 IT002162A ITMI20122162A ITMI20122162A1 IT MI20122162 A1 ITMI20122162 A1 IT MI20122162A1 IT 002162 A IT002162 A IT 002162A IT MI20122162 A ITMI20122162 A IT MI20122162A IT MI20122162 A1 ITMI20122162 A1 IT MI20122162A1
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- tab2
- solar absorber
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- absorber
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- 239000006096 absorbing agent Substances 0.000 title claims description 39
- 101000674728 Homo sapiens TGF-beta-activated kinase 1 and MAP3K7-binding protein 2 Proteins 0.000 title 1
- 102100021227 TGF-beta-activated kinase 1 and MAP3K7-binding protein 2 Human genes 0.000 title 1
- 239000000463 material Substances 0.000 claims description 13
- JEUVAEBWTRCMTB-UHFFFAOYSA-N boron;tantalum Chemical compound B#[Ta]#B JEUVAEBWTRCMTB-UHFFFAOYSA-N 0.000 claims description 11
- 229910052751 metal Inorganic materials 0.000 claims description 6
- 239000002184 metal Substances 0.000 claims description 6
- 239000000919 ceramic Substances 0.000 claims description 5
- 229910010293 ceramic material Inorganic materials 0.000 claims description 5
- 238000005516 engineering process Methods 0.000 claims description 5
- 150000001875 compounds Chemical class 0.000 claims description 3
- 239000011148 porous material Substances 0.000 claims description 3
- 229910021332 silicide Inorganic materials 0.000 claims description 3
- 230000003746 surface roughness Effects 0.000 claims description 3
- 150000004767 nitrides Chemical class 0.000 claims description 2
- FVBUAEGBCNSCDD-UHFFFAOYSA-N silicide(4-) Chemical compound [Si-4] FVBUAEGBCNSCDD-UHFFFAOYSA-N 0.000 claims 1
- XTDAIYZKROTZLD-UHFFFAOYSA-N boranylidynetantalum Chemical compound [Ta]#B XTDAIYZKROTZLD-UHFFFAOYSA-N 0.000 description 25
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 10
- 229910010271 silicon carbide Inorganic materials 0.000 description 10
- 238000002835 absorbance Methods 0.000 description 7
- 230000003287 optical effect Effects 0.000 description 6
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 5
- 238000002360 preparation method Methods 0.000 description 5
- 230000005855 radiation Effects 0.000 description 5
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 4
- 230000004907 flux Effects 0.000 description 4
- 229910052726 zirconium Inorganic materials 0.000 description 4
- 229910052735 hafnium Inorganic materials 0.000 description 3
- VBJZVLUMGGDVMO-UHFFFAOYSA-N hafnium atom Chemical compound [Hf] VBJZVLUMGGDVMO-UHFFFAOYSA-N 0.000 description 3
- 150000001247 metal acetylides Chemical class 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 239000012071 phase Substances 0.000 description 3
- 238000001228 spectrum Methods 0.000 description 3
- -1 AIN or SI3N4 0 BN Chemical class 0.000 description 2
- 229910026551 ZrC Inorganic materials 0.000 description 2
- OTCHGXYCWNXDOA-UHFFFAOYSA-N [C].[Zr] Chemical compound [C].[Zr] OTCHGXYCWNXDOA-UHFFFAOYSA-N 0.000 description 2
- 239000011358 absorbing material Substances 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 239000012925 reference material Substances 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 229910052715 tantalum Inorganic materials 0.000 description 2
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- 238000002834 transmittance Methods 0.000 description 2
- 229910003862 HfB2 Inorganic materials 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 229910007948 ZrB2 Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- VWZIXVXBCBBRGP-UHFFFAOYSA-N boron;zirconium Chemical compound B#[Zr]#B VWZIXVXBCBBRGP-UHFFFAOYSA-N 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000004320 controlled atmosphere Methods 0.000 description 1
- 229910003460 diamond Inorganic materials 0.000 description 1
- 239000010432 diamond Substances 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- WHJFNYXPKGDKBB-UHFFFAOYSA-N hafnium;methane Chemical compound C.[Hf] WHJFNYXPKGDKBB-UHFFFAOYSA-N 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000000985 reflectance spectrum Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 239000007790 solid phase Substances 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 230000001131 transforming effect Effects 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- 150000003624 transition metals Chemical class 0.000 description 1
- 239000011215 ultra-high-temperature ceramic Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
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- 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
- F24S70/00—Details of absorbing elements
- F24S70/20—Details of absorbing elements characterised by absorbing coatings; characterised by surface treatment for increasing absorption
- F24S70/225—Details of absorbing elements characterised by absorbing coatings; characterised by surface treatment for increasing absorption for spectrally selective absorption
-
- 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
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
- F24S70/00—Details of absorbing elements
- F24S70/30—Auxiliary coatings, e.g. anti-reflective coatings
-
- 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
- F24S80/10—Materials for heat-exchange conduits
-
- 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
Description
DESCRIZIONE DESCRIPTION
“Assorbitore solare comprendente TaB2” "Solar absorber including TaB2"
La presente invenzione si riferisce ad un assorbitore solare comprendente boruro di tantalio (TaB2), in grado di assorbire efficacemente la radiazione solare e di trasformarla in energia termica. The present invention relates to a solar absorber comprising tantalum boride (TaB2), capable of effectively absorbing solar radiation and transforming it into thermal energy.
Stato de arte State of the art
La tecnologia solare termica è considerata una promettente risorsa per l'ottenimento di energia sfruttando il calore e l’energia solare. In pratica, mediante l’utilizzo di ricevitori o collettori solari termici è possibile trasformare l’energia del sole in calore, che può essere convenientemente utilizzato ad esempio per riscaldare l’acqua o altri fluidi o come integrazione al riscaldamento di abitazioni o strutture industriali. In pratica, negli impianti termici solari comunemente utilizzati, la radiazione solare viene assorbita dall’assorbitore e convertita in energia termica che può essere quindi trasferita dall’assorbitore, ad esempio, ad un fluido e successivamente utilizzata per la generazione di energia elettrica. Solar thermal technology is considered a promising resource for obtaining energy by exploiting heat and solar energy. In practice, through the use of receivers or solar thermal collectors it is possible to transform the energy of the sun into heat, which can be conveniently used for example to heat water or other fluids or as a supplement to the heating of homes or industrial structures. In practice, in commonly used solar thermal systems, solar radiation is absorbed by the absorber and converted into thermal energy which can then be transferred from the absorber, for example, to a fluid and subsequently used for the generation of electricity.
Tuttavia, per ottenere un ciclo termodinamico di trasformazione efficiente è necessario avere un assorbitore solare in grado di avere ottime proprietà ottiche ad elevate temperature, associate ad una minima perdita di energia, il che implica sfide notevoli soprattutto per quanto riguarda la scelta dei materiali assorbitori utilizzati per la trasformazione della radiazione assorbita in energia termica. Pertanto, l'assorbitore solare ideale dovrebbe essere realizzato con un materiale in grado non solo di assorbire la luce solare in modo efficace (cioè avere un’alta assorbanza) mantenendo bassi valori di perdite energetiche secondarie (cioè avere una bassa emittanza), ma anche essere in grado di trasferire in modo efficace l’energia termica assorbita (cioè avere buone proprietà termiche). Inoltre, poiché l’efficienza aumenta con l’aumentare della temperatura di esercizio, l’assorbitore solare deve presentare anche un’elevata resistenza alle alte temperature. However, to obtain an efficient thermodynamic transformation cycle it is necessary to have a solar absorber capable of having excellent optical properties at high temperatures, associated with a minimum loss of energy, which implies considerable challenges, especially as regards the choice of the absorbing materials used. for the transformation of the absorbed radiation into thermal energy. Therefore, the ideal solar absorber should be made with a material capable not only of absorbing sunlight effectively (i.e. having a high absorbance) while maintaining low values of secondary energy losses (i.e. having a low emittance), but also be able to effectively transfer absorbed thermal energy (i.e. have good thermal properties). Furthermore, since efficiency increases with increasing operating temperature, the solar absorber must also have a high resistance to high temperatures.
A questo proposito, è noto nell’arte l’utilizzo di materiali ceramici quali carburi o boruri di zirconio o di afnio, per la preparazione di assorbitori per l’utilizzo nel campo della tecnologia termica solare. In particolare, E. Sani et al. (Scripta materialia 65 (2011), 775-778) divulgano l’utilizzo del carburo di zirconio (ZrC) per la preparazione di assorbitori solari in grado di operare a temperature intorno ai 1000° C. Ancora, E. Sani et al. in Journal of Renewable and sustainable Energy, 3, 063107 1-6, 2011 ed in Journal of Renewable and sustainable Energy 4, 033104, 2012, descrivono l’utilizzo di alcuni materiali ceramici in forma di carburi, quali ad esempio carburo di afnio e di tantalio, come assorbitori solari con alte prestazioni in termini di assorbanza ed emittanza. Infine, D. Sciti et al. ( Solar Energy Materials and Solar Cells 109, pp. 8-16 (2013) divulgano l’utilizzo del boruro di zirconio e afnio per la preparazione di assorbitori solari. In this regard, the use of ceramic materials such as carbides or borides of zirconium or hafnium is known in the art, for the preparation of absorbers for use in the field of solar thermal technology. In particular, E. Sani et al. (Scripta materialia 65 (2011), 775-778) disclose the use of zirconium carbide (ZrC) for the preparation of solar absorbers capable of operating at temperatures around 1000 ° C. Still, E. Sani et al. in Journal of Renewable and sustainable Energy, 3, 063107 1-6, 2011 and in Journal of Renewable and sustainable Energy 4, 033104, 2012, describe the use of some ceramic materials in the form of carbides, such as hafnium carbide and of tantalum, as solar absorbers with high performance in terms of absorbance and emittance. Finally, D. Sciti et al. (Solar Energy Materials and Solar Cells 109, pp. 8-16 (2013) disclose the use of zirconium boride and hafnium for the preparation of solar absorbers.
Ulteriori miglioramenti sono stati recentemente raggiunti a livello di laboratorio per ricevitori ad alta temperatura (si veda e.g. Kribus et al. Solar Energy Engineering, voi. 123, pp. 10-17), ma la maggior parte del lavoro di ricerca e sviluppo fatto negli anni recenti ha riguardato ricevitori solari comprendenti materiali ceramici che tuttavia non consentono il raggiungimento di elevate prestazioni per temperature superiori ai 1000° C. Further improvements have recently been achieved at the laboratory level for high temperature receivers (see e.g. Kribus et al. Solar Energy Engineering, vol. 123, pp. 10-17), but most of the research and development work done in the recent years has concerned solar receivers including ceramic materials which, however, do not allow the achievement of high performance for temperatures above 1000 ° C.
Resta quindi il bisogno di trovare un assorbitore solare in grado di avere ottime proprietà ottiche in termini di assorbanza, emittanza e conduttività, associate ad un’elevata resistenza a temperature anche superiori a 1000° C. A questo proposito, la Richiedente ha ora trovato che il diboruro di tantalio (TaB2) può essere vantaggiosamente utilizzato come materiale assorbitore per la realizzazione di ricevitori solari, utili nel campo della tecnologia termica solare, impiegabili anche a temperature superiori a 1000°C. The need therefore remains to find a solar absorber capable of having excellent optical properties in terms of absorbance, emittance and conductivity, associated with a high resistance to temperatures even above 1000 ° C. In this regard, the Applicant has now found that tantalum diboride (TaB2) can be advantageously used as an absorber material for the construction of solar receivers, useful in the field of solar thermal technology, which can also be used at temperatures above 1000 ° C.
Descrizione delle figure Description of the figures
Figura 1 : spettro di riflettanza di un campione di TaB2, rispetto ad una campione di SiC (carburo di silicio) e Al203(ossido di alluminio), misurata alle lunghezze d’onda dello spettro solare. Figure 1: reflectance spectrum of a sample of TaB2, compared to a sample of SiC (silicon carbide) and Al203 (aluminum oxide), measured at the wavelengths of the solar spectrum.
Figura 2: andamento dell’emittanza di un campione di TaB2, rispetto ad un campione di SiC, in funzione della temperatura. Figure 2: Emittance trend of a sample of TaB2, compared to a sample of SiC, as a function of temperature.
Descrizione dell’invenzione Description of the invention
Pertanto, la presente invenzione si riferisce, in un primo aspetto, ad un assorbitore solare comprendente diboruro di tantalio (TaB2). Therefore, the present invention relates, in a first aspect, to a solar absorber comprising tantalum diboride (TaB2).
In un successivo aspetto, l’invenzione si riferisce all’uso del TaB2nel campo della tecnologia termica solare, e ad un ricevitore solare contenente l’assorbitore dell’invenzione. In a subsequent aspect, the invention refers to the use of TaB2 in the field of solar thermal technology, and to a solar receiver containing the absorber of the invention.
Vantaggiosamente, l’assorbitore solare dell’invenzione permette la realizzazione di ricevitori solari in grado di operare sia in aria che in atmosfera controllata, garantendo elevate proprietà ottiche in termini di assorbanza, riflettanza ed emittanza, associate ad una stabilità alle alte temperature migliorata rispetto a materiali assorbitori noti ne arte e comunemente utilizzati per tale scopo. L' assorbitore dell'invenzione, infatti, presenta valori di emittanza e di assorbanza solare che ne permettono l'utilizzo anche a temperature fino a circa 1500° C, con ottimi risultati in termini di resistenza all’ossidazione e stabilità nel tempo. Inoltre, il diboruro di Tantalio risulta vantaggioso per l’applicazione solare in confronto agli altri diboruri presenti in letteratura (ZrB2e HfB2) grazie all'emittenza significativamente più bassa, come dimostrato ad esempio dalla figura 2 allegata. Advantageously, the solar absorber of the invention allows the realization of solar receivers capable of operating both in air and in a controlled atmosphere, guaranteeing high optical properties in terms of absorbance, reflectance and emittance, associated with an improved stability at high temperatures compared to absorbing materials known in the art and commonly used for this purpose. The absorber of the invention, in fact, has solar emittance and absorbance values that allow it to be used even at temperatures up to about 1500 ° C, with excellent results in terms of resistance to oxidation and stability over time. In addition, Tantalum diboride is advantageous for solar application in comparison to the other diborides present in the literature (ZrB2 and HfB2) thanks to the significantly lower emissivity, as shown for example by the attached figure 2.
Il TaB2è un materiale ceramico così detto ad “ultra alta temperatura” (UHTC), disponibile in commercio e facilmente reperibile. TaB2 is a so-called “ultra high temperature” (UHTC) ceramic material, commercially available and easily available.
Con il termine “emittanza” si intende indicare il rapporto fra il potere emissivo della superficie ed il potere emissivo di un corpo nero alla stessa temperatura. The term "emittance" is intended to indicate the relationship between the emissive power of the surface and the emissive power of a black body at the same temperature.
Con il termine “assorbanza” si intende indicare il logaritmo dell’inverso della trasmittanza. The term "absorbance" means to indicate the logarithm of the inverse of the transmittance.
Per “trasmittanza” si indica il rapporto tra l’intensità del flusso radiante trasmesso attraverso il materiale e l’intensità del flusso radiante incidente. Con il termine “riflettanza” si intende indicare il rapporto tra l’intensità del flusso radiante riflesso e l’intensità del flusso radiante incidente. By "transmittance" we indicate the relationship between the intensity of the radiant flux transmitted through the material and the intensity of the incident radiant flux. The term "reflectance" refers to the relationship between the intensity of the reflected radiant flux and the intensity of the incident radiant flux.
In una forma di realizzazione, il presente assorbitore solare volumetrico può comprendere TaB2sia in forma di materiale denso, cioè sostanzialmente privo di pori, che in forma di materiale poroso. In one embodiment, the present volumetric solar absorber can comprise TaB2 both in the form of a dense material, i.e. substantially free of pores, and in the form of a porous material.
Detta porosità viene preferibilmente ottenuta durante il processo di preparazione del materiale, ad esempio mediante una parziale sinterizzazione, e/o grazie all’aggiunta di agenti porizzanti, secondi metodi noti al tecnico del ramo. Said porosity is preferably obtained during the material preparation process, for example by partial sintering, and / or thanks to the addition of porous agents, according to methods known to those skilled in the art.
In un’ulteriore forma di realizzazione, l’assorbitore solare dell’invenzione comprende TaB2ed inoltre una fase secondaria comprendente almeno un metallo o un composto ceramico. Esempi di composti ceramici sono: nitruri metallici, quali AIN o SÌ3N4 0 BN, carburi, quali B4C, WC, siliciuri, ad esempio di metalli di transizione. Esempi di ceramici preferiti sono siliciuri metallici, ancor più preferibilmente scelti tra: molibdeno, tantalio e zirconio. Quando presente, la fase secondaria, è utilizzata in quantità compresa tra 0 e 50% in volume rispetto al TaB2,preferibilmente in quantità minore del 15%. Per percentuale in volume si intende il volume occupato dalla fase secondaria rispetto all’intero volume occupato dal materiale composito. Il presente assorbitore comprendente TaB2può essere preparato mediante tecniche note nell’arte che prevedono, la sinterizzazione a caldo sotto pressione della polvere, eventualmente in miscela con una fase solida secondaria (si veda ad esempio in Silvestroni et al. J. Eur. Ceram. Soc. 32, 97 (2012). In una forma di realizzazione preferita, l’assorbitore dell’invenzione può avere forma di piano, cilindro, parallelepipedo, mattonella, sfera o simili. In un’ulteriore forma di realizzazione, l’assorbitore solare dell’invenzione comprende TaB2avente una rugosità superficiale media compresa tra 0.01 micron e 10 micron, dove per rugosità superficiale media si intende il valore medio aritmetico degli scostamenti (presi in valore assoluto) del profilo reale della superficie rispetto alla linea media. Detta rugosità può essere ottenuta mediante una lavorazione superficiale con tecniche note al tecnico del ramo tra le quali elettroerosione, rettifica mediante mole diamantate o lavorazione laser. In un’ulteriore forma di realizzazione, il presente assorbitore comprende TaB2in forma di strato sottile (coating), depositato su un materiale di supporto (ad esempio metallico o ceramico) ad elevata conduttività termica, cioè preferibilmente superiore a 100 W/mK. In a further embodiment, the solar absorber of the invention comprises TaB2 and also a secondary phase comprising at least a metal or a ceramic compound. Examples of ceramic compounds are: metal nitrides, such as AIN or SI3N4 0 BN, carbides, such as B4C, WC, silicides, for example of transition metals. Examples of preferred ceramics are metal silicides, even more preferably selected from: molybdenum, tantalum and zirconium. When present, the secondary phase is used in an amount comprised between 0 and 50% by volume with respect to TaB2, preferably in an amount less than 15%. By volume percentage we mean the volume occupied by the secondary phase with respect to the entire volume occupied by the composite material. The present absorber comprising TaB2 can be prepared by techniques known in the art which provide for the hot sintering of the powder under pressure, optionally in admixture with a secondary solid phase (see for example in Silvestroni et al. J. Eur. Ceram. Soc 32, 97 (2012). In a preferred embodiment, the absorber of the invention can have the shape of a plane, cylinder, parallelepiped, tile, sphere or the like. In a further embodiment, the solar absorber of the The invention includes TaB2 having an average surface roughness between 0.01 micron and 10 micron, where by mean surface roughness is meant the arithmetic average value of the deviations (taken as an absolute value) of the real profile of the surface with respect to the average line. by means of surface processing with techniques known to those skilled in the art, including electro-erosion, grinding by means of diamond wheels or laser processing. In a further embodiment, the present absorber comprises TaB2 in the form of a thin layer (coating), deposited on a support material (for example metal or ceramic) with high thermal conductivity, ie preferably higher than 100 W / mK.
Come dimostrato dalle qui accluse Figure 1 e 2, l’assorbitore solare dell’invenzione ha proprietà ottiche sorprendentemente migliori rispetto ai materiali noti nell’arte quali SiC e AI2O3, anche a temperature superiori a 1000° C. In particolare, dalla Figura 1 si evince che TaB2mostra una riflettanza decisamente migliore di quella dei due materiali di riferimento, cioè SiC e AI2O3. In particolare, SiC è caratterizzato da valori di riflettanza compresi tra 20% e 10% fino ad una lunghezza d’onda di 10 μm , mentre a circa 12 μm è presente un picco di riflettanza, il cui valore (circa 85%) è comunque confrontabile con la riflettanza del TaB2alla stessa lunghezza d’onda. Oltre il picco, i valori di riflettanza del SiC decrescono nell'intervallo di lunghezza d’onda investigato, risultando considerevolmente minori di quelli del TaB2.As shown by the attached Figures 1 and 2, the solar absorber of the invention has surprisingly better optical properties than the materials known in the art such as SiC and AI2O3, even at temperatures above 1000 ° C. In particular, from Figure 1 it is possible to deduces that TaB2 shows a much better reflectance than that of the two reference materials, ie SiC and AI2O3. In particular, SiC is characterized by reflectance values between 20% and 10% up to a wavelength of 10 μm, while at about 12 μm there is a reflectance peak, whose value (about 85%) is in any case comparable with the reflectance of TaB2 at the same wavelength. Beyond the peak, the SiC reflectance values decrease in the investigated wavelength range, resulting considerably lower than those of TaB2.
AI2O3, invece, mostra una riflettanza molto alta (80-90%) alle lunghezze d’onda in cui vi è la maggior parte di radiazione dello spettro solare (0.2-2,5 micron, con la maggior parte dell’energia nell'intervallo 0,2-1 ,5 micron) che ne limita molto la possibilità di assorbimento della radiazione stessa. La riflettanza di TaB2invece presenta un andamento “a scalino” passando da valori intorno al 30% in media tra 0,2 e 1 ,5 micron, nella banda dello spettro solare, a valori alti di riflettanza (70-80%) alle lunghezze d’onda dell’emissione termica. La Figura 1 dimostra quindi che TaB2non solo possiede un’assorbanza solare superiore di quella di AI2O3, ma anche un’emittanza termica minore di quella dei due materiali di riferimento. L’emittanza è stata misurata utilizzando una camera sotto vuoto dotata di un radiometro sensibile alla lunghezza d’onda compresa tra 0,65 e 40 μm . In Figura 2, invece sono indicate le emittanze di TaB2e SiC in funzione della temperatura. Come si può notare, l’emittanza di TaB2è considerevolmente minore di quella del SiC, dimostrando in questo modo che il TaB2può essere convenientemente utilizzato come assorbitore solare, grazie alle sue proprietà ottiche ed alle minime perdite di energia riscontrabili durante il riscaldamento con luce solare. In particolare, nell’intervallo di temperatura che va da circa 800° C a circa 1200° C, SiC mostra valori di emittanza compresi fra 0,6 e 0,8. TaB2invece mostra valori di emittanza che vanno da circa 0,2 a circa 0,3 per temperature comprese fra circa 1000° C e circa 1200° C. I valori di emittanza di TaB2risultano vantaggiosi anche quando confrontati con l’emittanza dei diboruri di Zirconio e Afnio, come riportata ad esempio in D. Sciti et al., Solar Energy Materials & Solar Cells, voi. 109, p. 8 (2013). Tale fonte riporta infatti, per i due materiali citati, valori di emittanza maggiori o uguali a 0,4 per temperature sopra i 1000° C circa, mentre emittenza del TaB2secondo la presente invenzione, si mantiene compresa fra 0,2 e 0,3. Come qui descritto e dimostrato nel dettaglio, l’assorbitore solare comprendente TaB2secondo la presente invenzione può essere convenientemente utilizzato per la preparazione di ricevitori solari stabili alle alte temperature ed in grado di operare anche per valori superiori a 1000°C, garantendo ottime proprietà ottiche ed efficienza. AI2O3, on the other hand, shows very high reflectance (80-90%) at wavelengths where there is most of the solar spectrum radiation (0.2-2.5 microns, with most of the energy in the range 0.2-1.5 microns) which greatly limits the possibility of absorption of the radiation itself. The reflectance of TaB2instead presents a "step" trend passing from values around 30% on average between 0.2 and 1.5 microns, in the solar spectrum band, to high reflectance values (70-80%) at lengths d wave of thermal emission. Figure 1 therefore demonstrates that TaB2 not only has a higher solar absorbance than that of AI2O3, but also a lower thermal emittance than that of the two reference materials. The emittance was measured using a vacuum chamber equipped with a radiometer sensitive to the wavelength between 0.65 and 40 μm. In Figure 2, instead, the emittances of TaB2e SiC are shown as a function of the temperature. As can be seen, the emittance of TaB2 is considerably lower than that of SiC, thus demonstrating that TaB2 can be conveniently used as a solar absorber, thanks to its optical properties and the minimum energy losses found during heating with sunlight. In particular, in the temperature range from about 800 ° C to about 1200 ° C, SiC shows emittance values between 0.6 and 0.8. TaB2 instead shows emittance values ranging from about 0.2 to about 0.3 for temperatures between about 1000 ° C and about 1200 ° C. The emittance values of TaB2 are also advantageous when compared with the emittance of Zirconium diborides and Hafnium, as reported for example in D. Sciti et al., Solar Energy Materials & Solar Cells, vol. 109, p. 8 (2013). In fact, this source reports, for the two materials cited, emittance values greater than or equal to 0.4 for temperatures above about 1000 ° C, while the emittance of TaB2 according to the present invention remains between 0.2 and 0.3. As described and demonstrated in detail here, the solar absorber comprising TaB2 according to the present invention can be conveniently used for the preparation of solar receivers stable at high temperatures and capable of operating even for values higher than 1000 ° C, guaranteeing excellent optical and efficiency.
Claims (13)
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IT002162A ITMI20122162A1 (en) | 2012-12-18 | 2012-12-18 | SOLAR ABSORBER INCLUDING TAB2 |
| PCT/IB2013/061076 WO2014097165A2 (en) | 2012-12-18 | 2013-12-18 | SOLAR ABSORBER COMPRISING TaB2 |
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| Application Number | Priority Date | Filing Date | Title |
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| IT002162A ITMI20122162A1 (en) | 2012-12-18 | 2012-12-18 | SOLAR ABSORBER INCLUDING TAB2 |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4292081A (en) * | 1979-06-07 | 1981-09-29 | Director-General Of The Agency Of Industrial Science And Technology | Boride-based refractory bodies |
| EP1184480A2 (en) * | 2000-09-01 | 2002-03-06 | Premark RWP Holdings, Inc. | Polishing of press plates coated with titanium diboride |
| WO2009051595A1 (en) * | 2007-10-18 | 2009-04-23 | Midwest Research Institue | High temperature solar selective coatings |
| WO2009140051A2 (en) * | 2008-05-14 | 2009-11-19 | Ausra, Inc. | Methods and compositions for coating devices |
| EP2341038A1 (en) * | 2008-10-20 | 2011-07-06 | Abengoa Solar New Technologies, S.A. | Selective solar absorbent coating and manufacturing method |
-
2012
- 2012-12-18 IT IT002162A patent/ITMI20122162A1/en unknown
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2013
- 2013-12-18 WO PCT/IB2013/061076 patent/WO2014097165A2/en active Application Filing
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4292081A (en) * | 1979-06-07 | 1981-09-29 | Director-General Of The Agency Of Industrial Science And Technology | Boride-based refractory bodies |
| EP1184480A2 (en) * | 2000-09-01 | 2002-03-06 | Premark RWP Holdings, Inc. | Polishing of press plates coated with titanium diboride |
| WO2009051595A1 (en) * | 2007-10-18 | 2009-04-23 | Midwest Research Institue | High temperature solar selective coatings |
| WO2009140051A2 (en) * | 2008-05-14 | 2009-11-19 | Ausra, Inc. | Methods and compositions for coating devices |
| EP2341038A1 (en) * | 2008-10-20 | 2011-07-06 | Abengoa Solar New Technologies, S.A. | Selective solar absorbent coating and manufacturing method |
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| WO2014097165A3 (en) | 2014-10-30 |
| WO2014097165A2 (en) | 2014-06-26 |
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