Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
  • F24S10/00—Solar heat collectors using working fluids
  • F24S10/40—Solar heat collectors using working fluids in absorbing elements surrounded by transparent enclosures, e.g. evacuated solar collectors
  • F24S10/45—Solar heat collectors using working fluids in absorbing elements surrounded by transparent enclosures, e.g. evacuated solar collectors the enclosure being cylindrical
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
  • F24S20/00—Solar heat collectors specially adapted for particular uses or environments
  • F24S20/20—Solar heat collectors for receiving concentrated solar energy, e.g. receivers for solar power plants
• • 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
  • F24S80/30—Arrangements for connecting the fluid circuits of solar collectors with each other or with other components, e.g. pipe connections; Fluid distributing means, e.g. headers
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/40—Solar thermal energy, e.g. solar towers
  • Y02E10/44—Heat exchange systems

Definitions

• This invention relates to solar receiver tube with a low emissivity covering and a method for manufacturing the solar receiver tube. Additionally a use of the tube with the coat ⁇ ing on an inner side of the tube is presented. 2. Description of the Related Art
• a solar (thermal) receiver suffers from wasted energy emitted to the surroundings, i.e. heat loss.
• heat loss In order achieve as high as possible power generation there is fort to maximize the solar absorption (alpha) , and to mize heat losses by thermal emissivity (epsilon) .
• a next object of the invention is to provide a method for manufacturing the solar receiver tube.
• the solar receiver tube comprises with at least one area which should not be hit by concentrated sunlight.
• the area is covered by an emissivity inhibiting covering which inhibits an emissivity of infrared light of the tube.
• the solar receiver tube should be installed into a solar collector unit.
• the solar collector unit comprises a mirror for concentrating sunlight to a focal line of the mirror.
• the solar receiver tube In the focal line the solar receiver tube is in- stalled.
• An area which is averted to the mirror comprises the emissivity inhibiting covering.
• the area is built by a bellow of the solar re ⁇ ceiver tube.
• the low emissivity covering comprises preferably a necessary flexibility in order to fol ⁇ low movements of the bellow.
• the emissivity inhibiting covering comprises a low emissivity material .
• the low emissivity material comprises nanoparti- cles .
• the low emissivity material is selected from the group con- sisting of silver, gold, tungsten, molybdenum, aluminum and hafnium.
• the provided method for manufacturing the solar receiver tube comprises following steps:
• a use of a solar receiver tube in a solar thermal power plant is provided.
• the solar thermal receiver composes a stainless-in-glass two- tube configuration.
• the absorption of the solar radiation is carried out in the optical coating on the stainless steel tube that has a line of site with direct radiation of the sun and the indirect radiation reflected from the mirrors.
• thermal emissivity giving rise to heat loss, is radiated from every surface that has a high temperature (in comparison to the environment) .
• the figure shows a solar receiver tube based on the inven- tion.
• coating 100 of the non solar-relevant areas 11 of the tube with low emissivity coat ⁇ ings which will allow reducing the total emissivity of the solar receiver and hence reducing heat loss.
• the specific ar ⁇ eas to be coated with these coatings include the stainless steel bellows inside and outside, and the shaded parts of the steel tube (the parts that connect two tubes in the field and are under the bellows 111) .
• the total emissivity, and deduced heat loss, of the solar re ⁇ ceiver is a function of the thermal emissivity of each sur- face, the surface area, and the surface absolute temperature (see eq.l) .
• Current emissivity of the optical not-relevant areas, which are made from stainless steel, is -0.6, as re ⁇ ported in the literature.
• the bellows are stretched, exposing more surface to the environment, that further en ⁇ hance the heat loss from this surfaces. Coating these parts with low emissivity materials, e.g. 0.05-0.15, will effec ⁇ tively reduce the heat loss from these parts by 50%. Equation 1 :
• T - Absolute temperature Based on coating of the described areas the heat loss of the tube is expected to be lowered by -30-50 [w] .
• the coating can be applied by a variety of techniques includ ⁇ ing solution based dip/spray coating, brush painting, elec- trodeposition, electroless deposition, and vapor phase techniques such as physical vapor deposition (PVD) sputtering, chemical vapor deposition (CVD) , and atomic layer deposition (ALD) .
• PVD physical vapor deposition
• CVD chemical vapor deposition
• ALD atomic layer deposition
• Low emissivity metals e.g. silver, gold, tungsten, molybdenum, aluminum, and hafnium.
• Transparent conducting oxides e.g. indium tin oxide, cadmium tin oxide.
• Alternative solution might include insertion of low emissivity surfaces in-between the steel pipe and the glass tube, and/or applying a high polish treatment to the steel bellow parts .

Landscapes

• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Life Sciences & Earth Sciences (AREA)
• Sustainable Development (AREA)
• Sustainable Energy (AREA)
• Thermal Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Laminated Bodies (AREA)
• Lining Or Joining Of Plastics Or The Like (AREA)

Applications Claiming Priority (2)

Publications (2)

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Cited By (2)

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• 2013
  • 2013-03-06 WO PCT/EP2013/054459 patent/WO2013178370A2/fr not_active Ceased

Non-Patent Citations (1)

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