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
  • F24S70/12—Details of absorbing elements characterised by the absorbing material made of metallic material
• • 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
  • 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
  • F24S80/20—Working fluids specially adapted for solar heat collectors
• • 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
  • F24S10/70—Solar heat collectors using working fluids the working fluids being conveyed through tubular absorbing conduits
• • 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
  • F24S2080/03—Arrangements for heat transfer optimization
  • F24S2080/05—Flow guiding means; Inserts inside conduits
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F1/00—Tubular elements; Assemblies of tubular elements
  • F28F1/10—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses
  • F28F1/40—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being only inside the tubular element
• • 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

• linear solar energy collector and collector refers to a linear collector and a collector comprising said linear collector, formed by a tube or conduit through which a heat transfer fluid that absorbs solar radiation circulates, the linear collector being of the type intended to capture the concentrated solar rays by a system of reflective surfaces of the parabolic cylindrical collector type or of the Fresnel type.
• linear collector refers to a linear collector of the type that uses thermal oil or molten salts as heat transfer fluid intended to freeze in the collector tube or conduit in the absence of solar radiation, and thaw when such radiation re-exists.
• the scope of the present invention is part of the technical sector of solar energy, and in particular it is applicable in parabolic cylindrical thermo-solar plants that use thermal oil or molten salts as heat transfer fluid, when such fluid is allowed to freeze in absence of solar radiation
• linear solar energy collectors which comprise heat transfer oils or molten salts.
• Said linear sensors can be used in single reflection or double reflection collectors.
• a reflective surface directs the solar rays on one side of the linear collector
• the latter have a first reflective surface that directs a portion of the solar rays directly on the collector while another portion of the solar rays is directed towards a second reflective surface located at the rear and on the sides of the sensor, thus achieving that the rays strike the entire surface of the sensor and not only on one of its sides.
• the linear collector usually consists of a hollow cylindrical steel tube through which the heat transfer fluid circulates whose mission is to absorb heat from the radiation to transport it to heat exchangers where the heat transfer fluid loses heat generating water vapor that drives a turbine and is in turn a generator that produces energy.
• Said sensors can also be encapsulated in a vacuum glass tube or with little reactive gases and with reduced convention effect, such as argon.
• Linear collectors use molten salts that increase their temperature to 560 ° C or oils that increase their temperature to 400 ° C.
• the use of molten salts is convenient since allowing a greater increase in temperature allows an increase in the performance in the steam cycle.
• both types of fluids but especially molten salts, present the problem that they freeze at temperatures above ambient; in the case of salts, at an approximate temperature of 270 ° C, when there is no longer solar radiation. This freezing causes that the next day to start the plant it is necessary to defrost or melt the salts as quickly as possible to maximize the hours of solar radiation. That is, in practice, the salts are frozen at night and heated in the morning to melt or melt said salts.
• the fluid takes time to melt or melt for up to two hours. which is a lot of time considering that the annual average daily hours of usable radiation is around 10 hours.
• the present invention therefore describes a linear solar energy collector that makes it possible to work with a daily freeze-melt cycle, since it allows the working fluids to melt or melt in a shorter time through a uniform and faster distribution of the radiation. Said decrease in the time to melt or melt the fluids is achieved on the one hand due to:
• the solar collectors formed by at least one parabolic element and a linear duct or collector, have a turning mechanism to aim at the sun and capture the radiation, so that the collector follows the path described by the sun at the adapted speed to that of the movement of the sun, so that the collector always points to the sun.
• a linear solar energy collector has as its object a linear solar energy collector for the collection of solar radiation in solar thermal plants in which the heat transfer fluid freezes in the absence of radiation, that is, at dusk and at night the heat transfer fluid remains frozen.
• Said heat transfer fluid is preferably a molten salt.
• the present invention relates to a solar collector, formed by a linear collector or tube and at least one parabolic element in charge of capturing the solar radiation and diverting it to concentrate it on the collector or tube.
• Said collector has a device or mechanism that allows the assembly formed by the linear collector and the parabolic element to be rotated, so that the parabolic element is located between the sun and the collector, thus preventing radiation from reaching the collector or tube. Therefore, the object of the present invention is, according to claim one, a linear solar energy sensor comprising a longitudinal structure inside the conduit forming the linear sensor, whose function is to facilitate the transmission of heat from the surface from the sensor to the heat transfer fluid contained inside. Through this longitudinal structure, it is possible to melt or melt the frozen heat transfer fluid in a shorter time, thus increasing the performance of the solar plant.
• the linear collector is composed of a hollow duct or tube and a longitudinal structure inside the duct that facilitates the transmission of heat captured by the duct surface into the duct through the structure, achieving a heat distribution in the inside the duct and therefore in the faster and more effective heat transfer fluid by making better use of the thermal conductivity of the preferably metallic material of the inner structure.
• the conduit or tube containing the heat transfer fluid may, in turn, be concentrically included in a vacuum glass conduit or tube or with a gas, preferably argon, inside, that is, between the conduit containing the heat transfer fluid and the glass tube.
• the collector object of the present invention facilitates the defrosting or melting of the fluid without the stresses at any point of the material exceeding the admissible.
• the linear sensor can have different constructions, all of them based on the arrangement of a hollow duct and a longitudinal structure located inside the duct.
• Said longitudinal structure is preferably formed by a core comprising a section with a central core and at least one radial projection, preferably four, which divides the interior of the conduit into separate spaces through which the heat transfer fluid circulates.
• Said soul can have its hollow central core, so that inside it will also circulate the heat transfer fluid, and the plates that make up the radial projections in section can have holes to communicate the spaces between projections.
• Said longitudinal structure and conduit can form a single piece of the same material manufactured by extrusion, or on the contrary it can be composed of two pieces, the conduit and the longitudinal structure joined together, being able in this case to be made of the same material or different materials
• the Manufacturing materials preferably will be high thermal conductivity steel or aluminum alloys, which can also be combined with each other, the collector being able to have a steel conduit and a longitudinal structure of extruded aluminum alloy.
• the section of the duct may vary depending on the optical arrangements of the reflection system, which can be said sensor of circular or non-circular section, in which case it could be ovoidal, elliptical or polygonal.
• the duct and the longitudinal structure make up a single piece, the longitudinal structure or core being determined by different independent ducts through which the heat transfer fluid circulates.
• the collector formed by a linear collector or tube and at least one element with a curved surface, preferably parabolic, is completed by providing it with a device that modifies the operation of the pointing or directing mechanisms of the collectors towards the sun, by allowing the conuint to rotate in order to arrange the parabolic element between the sun and the collector or tube, producing a controlled fan effect that prevents the temperature gradients in the tube from exceeding the acceptable limits for the material from which try, that is, the turning mechanism allows you to aim or not at the sun depending on the temperature needs while the fluid is thawing.
• the collector allows the tube or collector to be within reach of the sun's rays depending on the required heating of both the tube and the heat transfer fluid, thus allowing to regulate the temperature of the assembly formed by both.
• the collector can have two curved surface elements, preferably parabolic, in order to achieve a double reflection on the collector.
• Figure number 1a shows a section of the sensor of the section shown in the figure 1 b.
• Figure 1b shows a sectional view of a preferred embodiment of the sensor object of the present invention.
• Figures 2 to 5 show preferred embodiments of collector sections formed by a duct and different longitudinal structures.
• Figure 6 shows a sensor in which the duct and the longitudinal structure form a single piece.
• Figures 7 and 8 show two alternatives of linear sensors in which the duct does not have a circular section.
• Figure 9 shows a diagram of a solar collector formed by the elements with curved or parabolic surfaces and the turning mechanism.
• Figure 1 shows a cross section of a sensor 10, formed by a conduit or tube 1 1 and an internal longitudinal structure 12, formed in turn by a core with a core 13 and four radial projections 14 that determine four spaces 15 arranged between the core 13, the projections 14 and the duct 11.
• the heat transfer fluid which can be oil or salt, preferably molten salt.
• the outer surface of the duct 11 captures the solar radiation and transmits the heat to the molten salt which, after being cooled in a heat exchange, generates steam for the movement of turbines and thus generates electrical energy.
• the molten salt works at a temperature of up to 560 ° C, but in the absence of heat it freezes at 170 ° C.
• the salt is frozen and it is desired to defrost or melt with the same elements used to capture solar radiation, said melting or defrosting is slow, forcing the plant to stand still until the salt is melted instead of generating electricity.
• the internal longitudinal structure of the collector object of the present invention has the task of defrosting the molten salt as quickly as possible once it has been frozen. without any additional energy input and with the same means used to capture radiation.
• the present sensor is designed for use in solar plants in which the heat transfer fluid, be it oil or molten salt, freezes in the absence of radiation.
• Figure 1 b shows a longitudinal section AA of the sensor of Figure 1 a, and in it the duct 11, the core 13 of the internal structure and holes 16 arranged in the plates 17 forming the projections 14 are shown to allow the circulation of the heat transfer fluid between the different spaces 15.
• These plates 17 and projections 14 allow the heat captured by the surface of the conduit 1 1 to be easily transmitted inside the frozen fluid, preferably salt, accelerating its defrosting.
• the internal structure 12 and the conduit 1 1 are independent elements manufactured in the same material or in different materials.
• Figure 2 shows an alternative construction of a sensor 20 according to the present invention, which presents a longitudinal structure 22 of extruded aluminum with a cross-shaped core inside a steel duct 21 with circular section, determining four spaces between the projections of the longitudinal structure that may or may not be connected to each other through which the heat transfer fluid circulates.
• Figure 3 shows another alternative construction of a sensor 30 according to the present invention, which has a longitudinal structure 32 of extruded aluminum with a cross-shaped core and hollow central core 33, inside a steel conduit 31 with circular section, determining four spaces between the projections of the longitudinal structure that may or may not be connected to each other and the central recess 33, through which the heat transfer fluid circulates.
• Figure 4 shows yet another alternative construction of a sensor 40 according to the present invention, which presents a longitudinal structure 42 of steel with a cross-shaped core inside a conduit 41 also made of steel and with circular section, determining four spaces between the projections of the longitudinal structure that may or may not be joined together for the circulation of the heat transfer fluid.
• Figure 5 shows another alternative construction of a sensor 50 according to the present invention, which has a longitudinal structure 52 of alloyed aluminum type A with a core with four radial projections and a hollow central core 53, inside a conduit 51 of a type B aluminum alloy, determining four spaces between the projections of the longitudinal structure 52 that may or may not be connected to each other and the central recess 53, through which the heat transfer fluid circulates.
• Figure 6 shows a sensor 60 object of the present invention in which the circular duct and the longitudinal structure form a single piece 61 by means of an alloy of extruded steel comprising several inner ducts 63 through which the heat transfer fluid circulates.
• Figures 7 and 8 show sensors 70, 80 in which the section of the duct is not circular and are formed by ducts and internal structures that make up a single piece 71, 81 with ducts 73, 83 inside for the circulation of the heat transfer fluid .
• Figure 9 shows a collector that presents a turning mechanism to allow the collector to point or not to the sun depending on the limitations of power contribution to the linear tubes or collectors during the melting process of the heat transfer fluid, avoiding gradients of excessive temperature in the linear sensor.
• a first curved element 90 preferably parabolic, provided with a rotation mechanism 91 that allows rotation B of the assembly when turning A along a rotation axis 92.
• the fan movement A of the pointing or turning mechanism 91 It produces several successive sequences of focus-blur, alignment-misalignment, between the sun and the collector, thus varying the thermal power reached by the pickup tube so that the thermal gradients are kept within acceptable limits.
• Said manifold thus comprises a linear sensor or tube 10, 20, 30, 40, 50, 60, 70, 80, a first parabolic element 90 with a device 91 for rotating the linear sensor 10, 20, 30, 40, 50, 60, 70, 80 and a second parabolic element 93.
• Said first parabolic element 90 may or may not point to the sun to limit the power input to the pickup tubes 10, 20, 30, 40, 50, 60, 70, 80, during the melting process of the heat transfer fluid, avoiding excessive temperature gradients in the linear collector.
• Said second parabolic element 93 is included for double reflection collectors.

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• 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)
• Engine Equipment That Uses Special Cycles (AREA)
• Optical Elements Other Than Lenses (AREA)

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Cited By (1)

Citations (5)

• 2012
  • 2012-03-30 ES ES201230496A patent/ES2427848B1/es not_active Expired - Fee Related
• 2013
  • 2013-03-25 WO PCT/ES2013/070195 patent/WO2013144406A1/fr not_active Ceased

Patent Citations (5)

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