Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F22—STEAM GENERATION
  • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
  • F22B1/00—Methods of steam generation characterised by form of heating method
  • F22B1/006—Methods of steam generation characterised by form of heating method using solar heat
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
  • F03G—SPRING, WEIGHT, INERTIA OR LIKE MOTORS; MECHANICAL-POWER PRODUCING DEVICES OR MECHANISMS, NOT OTHERWISE PROVIDED FOR OR USING ENERGY SOURCES NOT OTHERWISE PROVIDED FOR
  • F03G6/00—Devices for producing mechanical power from solar energy
  • F03G6/06—Devices for producing mechanical power from solar energy with solar energy concentrating means
  • F03G6/065—Devices for producing mechanical power from solar energy with solar energy concentrating means having a Rankine cycle
• • 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
  • F24S10/25—Solar heat collectors using working fluids having two or more passages for the same working fluid layered in direction of solar-rays, e.g. having upper circulation channels connected with lower circulation channels
• • 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
  • F24S10/00—Solar heat collectors using working fluids
  • F24S10/80—Solar heat collectors using working fluids comprising porous material or permeable masses directly contacting the working fluids
• • 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
  • F24S10/90—Solar heat collectors using working fluids using internal thermosiphonic circulation
  • F24S10/95—Solar heat collectors using working fluids using internal thermosiphonic circulation having evaporator sections and condenser sections, e.g. heat pipes
• • 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
• • 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
  • F24S23/80—Arrangements for concentrating solar-rays for solar heat collectors with reflectors having discontinuous faces
• • 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
  • F24S80/50—Elements for transmitting incoming solar rays and preventing outgoing heat radiation; Transparent coverings
  • F24S80/52—Elements for transmitting incoming solar rays and preventing outgoing heat radiation; Transparent coverings characterised by the material
• • 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
  • F24S80/50—Elements for transmitting incoming solar rays and preventing outgoing heat radiation; Transparent coverings
  • F24S80/54—Elements for transmitting incoming solar rays and preventing outgoing heat radiation; Transparent coverings using evacuated elements
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
  • F24S80/00—Details, accessories or component parts of solar heat collectors not provided for in groups F24S10/00-F24S70/00
  • F24S80/60—Thermal insulation
• • 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
  • F24S2023/85—Micro-reflectors
• • 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
  • F24S2025/01—Special support components; Methods of use
  • F24S2025/011—Arrangements for mounting elements inside solar collectors; Spacers inside solar collectors
• • 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
• • 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
  • Y02E10/46—Conversion of thermal power into mechanical power, e.g. Rankine, Stirling or solar thermal engines

Definitions

• Embodiments of the invention relate to devices and methods to harness solar radiation as an energy source.
• Solar collectors are devices designed to convert solar radiation into heat that can foe used to perform work
• the flat plate solar collector includes a housing 100 comprising a transparent cover plate glass 102, In use, solar radiation enters the housing 100 through the cover plate glass 102 and strikes an absorption plate 110 located within the housing 100.
• the absorption plate 110 may be coated with a material capable of absorbing solar radiation and converting the solar radiation into heat.
• the fiat- plate collector includes a pipe array 106, which is bonded to the absorber plate 110 such that a heat transfer fluid entering the array 106 at entry point 104, is subsequently heated, and emerges at exit, point 108 at a higher temperature .
• the space between cover plate glass 102 and the absorber plate 110 is usually filled with air.
• the space below the absorber plate- 110 is usually filled with an insulating material 112.
• the performance of the flat plate collector in terms of maximum achievable output temperature of the heat transfer fluid is limited to a large extent by thermal losses. These losses can occur via radiation from the pipe array 106 and from the absorber plate 110» The thermal losses can also occur via convection, through the air disposed between the absorption plate 110 and the cover plate glass 102. Finally, the thermal losses can occur via conduction through the insulating material 112. The dominant losses are via convection and conduction. Typical maximum operational temperatures reached by the heat transfer fluid after thermal losses are about 120 °C.
• FIG. 2 of the drawings Another design for a solar collector is known as an evacuated, tube array.
• the evacuated, tube array comprises a collection of evacuated tubes 202, one of which is shown in cross-section.
• each tube 202 comprises an outer transparent shell 210, which surrounds an inner absorbing shell 212.
• solar radiation passes through the outer shell 210 and impinges on an inner absorbing shell 212 where it is absorbed and converted to heat.
• the inner shell 212 and the outer shell 210 are separated .by a vacuum and have no internal supports with the exception of a mechanical support at one end of the tube.
• Heat is transferred via a heat transfer fluid circulating through an internal pipe 214.
• Each of the internal pipes of the individual tubes 202 within the evacuated tube array is connected such that heat transfer fluid entering at entry point 204, collects heat fro ail of the tubes 202 and emerges at a higher teiftperature at exit point 206,
• evacuated tubes 202 The performance of evacuated tubes 202 is also limited by thermal losses. In this case, however, the losses are not dominated by convection or conduction because of the presence of a vacuum, and the small number of heat conducting internal supports, instead, thermal losses in t . h.e evacuated tubes 202 evacuated tube array design are dominated by radiation losses from the evacuated tubes 202. These losses increase as the
• temperatures of the heat transfer fiuid for the evacuated tube arra design are about 200°C. smm Y
• a solar collector comprising:
• a solar collector body defining a housing with at least one window to permit solar radiation to enter the solar collector body?.
• a heat transfer component positioned within the solar collector body and comprising:
• a heat transfer core positioned within the heat transfer component housing and having a light absorption
• a fluid transfer element comprising ah aerogel with voids shaped and dimensioned to support passive pumping of the heat transfer finid therethrough;
• heat transfer fluid is transferred from the at least one ingress conduit into the heat transfer core by the fluid transfer element, undergoes heating in the heat transfer core with heat generated through the absorption of light by the light absorption element, and is released into the egress
• FIG. 1 of the drawings is prior art showing a
• FIG, 2 of the drawings is prior art showing an evacuated tube solar collector.
• FIG. 3 of the drawings is an exploded and asserabied schematic diagram of a monolithic evacuated flat plate solar flux converter, in accordance with one embodiment of the inventi n ,
• FIG. of the drawings are two diagrams illustrating the solar spectrum, and the light absorption characteristics of water .
• FIG. S of the drawings is a diagram showing detailed operation of the solar flux converter, in accordance with one embodiment of the invention.
• FIG. 6 of the drawings illustrates a micro-optical Concentration array coupled to a heat transfer core
• FIG. 7 of the drawings illustrates plana and tubular solar flux converters with internal cavities, in accordance with one embodiment of the invention.
• FIG. 8 of the drawings illustrates a herm l energy conversion system incorporating s solar flux converter, in accordance with one embodiment of the invention.
• FIG, 9 of the drawings shows a cut way diagram, of a simplified solar flux conversion module, in accordance with one embodiment of the invention.
• FIG. 3 shows exploded and assembled views of the solar collector, in accordance with one embodiment .
• the solar collecto includes a face sheet 300 of glass or some other material.
• the face sheet 300 is transparent to visible and near infrared light / and is non-permeable.
• the face sheet 300 may thus be capable of supporting a vacuum.
• the face sheet 300 say include anti-r flectioii coatings 302 and 304 applied to Its outer and inner surfaces. These coatings 302 and 304 minimize reflective losses that normally occu when light is transmitted through glass.
• the solar collector may also include a micro- optic array 306, which serves to concentrate solar radiation from a. wide collection angle to impinge on. a heat, transfer component (to be described) .
• th micro-optic array 306 is in the form of a thin replicated light concentrating array.
• the micro- optic array 306 may comprise multiple elements in the form of compound parabolic concentrating elements though it may comprise one or more other optical structures.
• the micro-optic array 306 may be molded or formed irons a transparent plastic material though glass like materials that can be molded and fired at an elevated temperature may suffice.
• the material Is low out gassing, that is to say it emits little or no
• a standoff structure array 308 and 310 provides physical standoffs between the micro-optic array 306, and a heat transfer component cover sheet 312. Similar standoffs are described in OS Patent Application No. 12/336, 336, which is hereby incorporated by reference, The function of the standoffs is to provide mechanical support between the micro-optic array 306 and the heat transfer component cover sheet 312, while minimising thermal losses via conduction. As such the standoffs are designed to have minimal contact area at the point where they touch the surfaces of the micro-optic array 306 and/or the heat transfer component cover sheet 312.
• the standoffs may be mad from a material with low thermal conductivity including but not limited to glass, oxides, and polymeric materials,, and is ideally transparent to visible light and near infrared light.
• a material with low thermal conductivity including but not limited to glass, oxides, and polymeric materials, and is ideally transparent to visible light and near infrared light.
• FIG. f the standoff structures 308 and 310 are shown to
• the standoffs 308 are in the form of microscopic spheres that can be made from silicon dioxide or other oxides or perhaps olym rs. Because of their spherical shape, the size of the surface contact area is mini ized and determined fey the. flatness and rigidity of the two surfaces being separated, viz. the micro-array optic 3G € and the heat transfer component 31.2. This reduces thermal losses via conduction. The low thermal conductivity of silicon dioxide reduces these losses even f rther,
• the standoffs 310 are in the form of micro-maehined or micro-molded high aspect ratio posts or pillars.
• Sigh aspect ratio refers to the fact that their height, i.e. the assembled distance between the micro-optical array 306 and the cover sheet 312, is much larger than their lateral dimensions.
• Material choice for the standoff 310 may be made based on the availability of appropriate machining or molding techniques and the ⁇ suitability of candidate lo thermal
• the heat transfer component cover sheet 312 may also include a combination of anti-reflection, low emissivity, or heat mirror coatings 316 and 318, on its opposed surfaces .
• the heat transfer com onent comprises a heat transfer core 320, heat transfer core cover sheet 312, heat transfer core back sheet 324, and support, posts 322 on either side of the heat- transfer core 320»
• the support posts may not be required in some embodiments .
• the support posts 322 physically separate the heat transfer core 320 from the heat transfer core cove sheet 312 thereby to create a fluid flow conduit 313 there betw en.
• the support posts 322 physically separate the heat transfer core 320 from the heat, transfer core back sheet 322 thereby to create a fluid flow conduit 315 there between,
• the heat transfe core 320 m be regarded as having two functional elements, viz , a fluid
• the aforesaid functional elements may be provided by the same physical or structural component or they may be provided by different physical components. In one
• the heat transfer core 320 may foe defined by
• porous planar element comprising a numbe of materials including bat not limited to metallic or graphite foams, sintered metals or ceramics, or another material medium with high thermal conductivity and whose porosity can be defined during their manufacture, or through micr ⁇ machining or other micro- fabrication techniques.
• the fluid transfer element of the heat transfer core 320 may include a myriad of. microscopic voids which, are connected so that fluids and/or gasses may pass ther through.
• the voids are shaped, dimensioned, and sized, in certain embodiments, to encourage, facilitate, or otherwise support the passive transport of liquids or gasses through the heat transfer core 320, In one embodiment this passive transport trtay be accomplished via a wicking phenomenon.
• the porosity of the heat transfer core 320 is designed such that light which, strikes it upper surface cannot pass through the entire body of the heat transfer core 320.
• the fluid transfer element of the heat transfer core 320 may comprise aerogel in particulate or granular form, or aerogel in the form of rectangular slabs or other pre ⁇ molded monolithic geometric forms which are uniform in structure.
• the manuf cturing process may comprise: th creation of a. colloidal gel within a mold using processes and precursors which are well known and established in the art of making aerogel. The process may further involve air drying or
• the process may also include the formation of a rapidl solidifying mixture, by gel formation, which is directly atomized by a gaseous medium via a nozzle in a falling tower, the resulting droplets solidifying during the failing time into aerogel particles, or variations of this process which are known by those skilled in the art of aerogel manufacture .
• the aerogel may be hydroscopic or hydrophobic. If the final form of the aerogel is particulate then this form may be achieved directly during the manufacturing process, or by making monolithic forms which are subsequently broken and ground into a particulate form.
• the aerogel particles may be formed or molded into solid shapes by a process which binds the particles together.
• a process which binds the particles together.
• Such a process xaay include the application of heat and pressure in the presence of a gas or gasses, such as air or other organic or inorganic gasses, whose composition is controlled to enhance the binding of the particles together.
• the aerogel may comprise organic aerogel,, inorganic aerogel ⁇ e.g. metal oxides) or a mixture thereof,
• th aerogel i of an organic form it is preferably selected from the group based on derived f om or consisting of resorcinol- formaldehyde, meland e-formaIdehyde, and combinations thereof.
• the aerogel is inorganic it is preferably selected from the group based on derived from or consisting of metal oxides such as -silica-, titania, almaina and combinations thereof with silica being the preferred material.
• the upper surface areas of the heat transfer core 320 which are exposed to incident light, may be coated with one or more light absorbing films. These films are designed to maximize the amount of light absorbed and minimise the amount of heat radiated. Thus, the aforesaid films serve the light absorption function of the core 320. Many such coatings exist including metallic oxynitrides, black chrome, and induced absorber optical stacks. Their design and preparation are well known by those skilled in the art of solar absorption coatings.
• the upper surface areas may also be machined o molded so that it is non ⁇ pianar, that is to say said upper surfaces may include features such as depressions, slots, or voids which penetrate partially into the heat transfer core 320. These features may have a variety of different, geometries and
• the overall thickness of the heat transfer core may also vary in such a way so that its thickness is greater at the end of the collector opposite the region where heat transfer fluid enters. This may be necessary in order to accommodate a higher heat transfer fluid flow which, can occur at the fluid inlet region of the collector and will decrease gradually as more of the fluid is absorbed into the heat transfer core as the fluid propagates from the fluid inlet region to the end of the collector.
• Support posts 322 are defined on the exterior surfaces of heat transfer core 320, during the process of its f brication, though it is possible that these structures may foe added at a later stage.
• the support posts 322 serve to provide mechanical coupling
• Back sheet 324 does not have to transmit light f therefore it may comprise one of a variety of materials including glass, ceramics, metals, metal foils, or special polymeric materials.
• the material is that it be capable- of: supporting a vacuum.
• Standoff array 326 performs a similar function to that of standoff array 308/310, As such it may take a similar form and utilize simila materials as already described. In this case the array 326 provides mechanical support between heat transfer core, back sheet 324, and collector housing plate 328, while minimizing thermal losses through conduction,
• a collecto housing plate 328 serves to protect the internal components from environmental elements, and to maintain a vacuum internally,
• the collector housing plate 328 dees not have to transmit light and thus may be fabricated from a wider variety of materials including but not limited to glass, metals, ceramics,, metallic foils, and special polymeric materials. he primary requirement of the material is that it can endure exposure to outside environments, and is non-permeable to gasses thereby to support a vacuum,
• Coating 330 is a film or stack of thin films whose function is to reflect all infrared radiation emitted by the internal components of the collector.
• the coating 330 may be comprised of a simple coating of gold, or a mo
• Getter 334 is a material whose function is to absorb any residual gasses that remain after the manufacturing process or that develop during the course of the operation of the module. It is generally a solid and can be selected from a variety of materials including but not limited to barium, zeolite compounds, or other appropriate material which are well known to those skilled in the art.
• Heat transfer fluid inflow/outflow tubes 336 provide an inlet/outlet for heat ransfe fluids and gasses betwee the internal components and external system components to which heat is being transferred. [0033] All of the above described components are aligned, laminated, and/or bonded to produce ' the assembled solar
• the combination of the cover sheet 312 , the heat transfer core 320, and the back sheet 324 forms hermetically sealed laminate which is referred to herein as the heat transfer component.
• the combination of the components 300, 328, and 330 forms a body defining a housing for the heat transfer component In one embodiment the heat transfer component resides within a vacuum to be established between the face sheet 300, and the housing plate 328»
• Lamination and bonding techniques may invoice some combination of low out gassing adhesives, low temperature soldering between similar or dissimilar materials, heat driven glass frit sealing processes, and anodic bonding techniques. Other lamination and bonding techniques may be applicable as will be understood by those skilled in the art.
• the solar collector 338 receives incident light 340 from the sun. Host of this light is transmitted through the intervening components where it strikes the heat transfer core 320 and is converted into heat. Heat transfer fluid 344.
• Heat transfer fluid 344 may also be in the form of a gas or a combination of gasses including but not limited to air, argon, krypton and xenon.
• the heat transfer fluid 344 may also foe pressurised at a pressure which, is at or slightly above atmospheric pressure or as low as one tenth to one hundredth of normal atmospheric pressure.
• the fluid is either pumped in via an external pump through inflow plpe : 342, or drawn in via a passive process that is supported by or facilitated by the pore geometry of the fluid transfer element . kicking effects within the heat transfer core 320 may provide this function.
• the heat transfer fluid From the inflow pipe 342 which, defines an inlet to the collector 338, the heat transfer fluid enters the fluid conduit 313.
• the fluid conduit 313 thus defines an ingress conduit.
• the heat transfer fluid undergoes heating by absorbing some of the incident light, but primarily through contact with the heat transfer core 320.
• the temperature of the heat transfer fluid will rise to the point of evaporation as it flows through the heat transfer core 320. At what temperature this occurs depends on the properties of the heat transfer fluid, the internal pressure of the heat transfer core 320, and the physical properties of the heat transfer core 320.
• a result of the aforementioned heating of the heat transfer fluid is a heat transfer vapor 348 which flows into the fluid flow conduit 315,
• the heat transfer vapor 348 transports heat from the heat transfer core 320 in the process of evaporating.
• the resulting thermal energy can thus be extracted via outflow pipe 350 which / defines an outlet for the collector 338.
• the fluid flow conduit 315 thus defines an egress conduit via which the heat flow vapor 348 is extracted.
• Chart 400 of FIG , 4 shows the spectrum of radiation emitted by the sun that strike the earth' surface. In general it is useful to absorb and convert as much of this energy as possible.
• Chart 400 illustrates that the bulk of the received energy froTS th sun resides between the wavelengths of 200 nm to 2400 nm.
• Chart 402 illustrates the absorption spectrum of water, which is one candidate heat transfer fluid. As can be seen, water is extremely transparent to light in the wavelengths from 200 nm to 1000 nm. As the wavelength Increases, the absorption of incident light increases dramatically. This property may be used to advantage,,- and there is evidence to suggest that other heat transfer fluids exhibit similar performance.
• FIG. 5 illustrates how the: absorption characteristics of the heat transfer fluid are exploited, by the solar collector of the present invention in order to eliminate or at least reduce radiation losses.
• reference numeral 500 indicates an embodiment of the solar collector of the present invention as seen froxa the perspective of the solar light source.
• the errshodiment 500 includes a heat transfer core 502 and heat transfer core standoffs 504, as described.
• the heat transfer core standoffs provide mechanical support betwee the heat transfer cor 502 and the intervening heat transfer core cover sheet.
• Reference numeral 506 indicates the same embodiment of the solar in cross-sectional view. As will be seen the heat transfer core standoffs 514 provide the aforementioned
• Spacer balls 510 provide mechanical support between heat transfer core cover sheet 512 and face sheet 508.
• a vacuum resides between sheet 508 and 512. .
• Some portion of the incoming light 524 is absorbed by heat transfer fluid 518 while the bulk is absorbed by the heat transfer core 516. If there were no flow of the heat transfer fluid 518, then over time the heat transfer core 516, the heat transfer fluid 518, and the heat transfer core cover sheet 512, would all rise to the same temperature .
• the solar collector utilizes what is known as two phase heat transfer approach. That is to say that the heat transfer fluid 518 flows into the solar collector in the form of a liquid phase, and emerges from the collector in a vapor phase. This has the advantage of minimizing the- amount of liquid that must be pumped in orde to achieve a certain heat flow rate . It also makes it possible to eliminate external
• the solar collector may also he operated using single phase heat transfer in the form of a liquid phase only. This requires more power to be utilized on pumping the heat transfer fluid, but may result in a simpler heat transfer network connecting the solar collector to other system components,
• FIG. 6 shows a micro-optical array 600, which is
• the micro- optical array is a collection of 2D (two dimensional) compound parabolic concentrators ⁇ CPCs ⁇ .
• CPCs are well understood optical components that fall into the class of non-imaging optics. Their function and design are described in detail in the book entitled “Nonimaging Optics” by Roland Winston et. al . In general CPCs can act as concentrators of incident light where the degree of concentration is inversely proportional to the acceptance angle of the incoming light.
• CPC 606 is shown concentrating incident light rays 604 for coupling with heat transfer core 608,
• the CPCs are made fro a transparent material, whose index of refraction is higher than that of the environment, thus rays 604 are internally reflected via total internal eflection.
• concentration is to increase the intensity f the incident flux at a gx ⁇ en ' location in order to achiev greater temperatures.
• the exposed surface area of the absorber or heat transfer core 608 must be decreased to accommodate the output of the concentrator. This consequently reduces the volume of the core 608 that must be heated,
• the geometry of the heat transfer core 608 is designed to conform to the output of the 6PG. This is
• transfe core 60 is a transfe core 60 .
• the micro-optical arrays can be formed using a variety of techniques including molding and replication wherein a moid is created of the inverse shape of the final optic and that moid is used to stamp or replicate copies of the optic into various materials such & polymers or cast glassy materials.
• the array resides within, the evacuated portion of the solar collector and has optical materials that are low out gassing. It is possible that the micro-optical array could reside within the heat transfer core component where it would be exposed to the heat transfer fluid. This may mitigate issues with outgassing, but will have implications from a thermal expansion point of view, and will require that the array be compatible with the heat transfe fluid. :
• Molded standoffs 612 ar shown providing mechanical support and thermal isolation between heat transfer core cover sheet 610 heat transfer core 608, whic are bonded, and 2D CPC optic 606, 3D CPC designs are also possible.
• 3D CPC optic 614 is shown coupled to n appropriately formed heat transfer core pillar 616. 3D concentrators can provide even higher levels of concentration with further
• Arrays of such optics can also be formed via the aforementioned micro-replication techniques.
• One 3D CPC optic array? array 618, is shown coupled to heat transfer core 620, via heat transfer cor pillars 622.
• Other replicated optical, components, variations of CPC and combinations thereof may also be incorporated into the module in a similar fashion.
• the features in both heat transfer cores 602 and 620 may be formed in a molding process or via machining or microroachining means ,
• FIG, 7 illustrates the operation of a modified solar collector 702.
• the collector 702 differs from the one
• heat transfer core 704 has been fabricated such that there is an internal cavity or fluid flow conduit 706 in addition to a first, ingress conduit 707 and a second ingress conduit 709.
• heat transfer fluid 714 flows into the collector 702 via the ingress conduits 707 and 709 along the paths indicated by arrows 708 and 710, Incident fl x 700 is absorbed by heat transfer cor 704,. and subsequently converted to heat .
• the internal cavity 706 is engineered so that the resulting vapor flows within it. in the direction of arrows 712, where it and the neat it. contains can be extracted via outflow pipe 716.
• the collector 702 exhibit further
• FIG. 7 also llustrates an alternative geometry for a solar collector in the form of tubular converter 718.
• Converter 71:8 comprises a transparent outer shell 720, and a: transparent inner shell 722, A vacuum is established between the two shells to eliminate thermal losses through convection.
• Anti-reflection, low emissivity, and heat mirror coatings may also be applied to the inner and outer surfaces : o£ the shells in orde be maximize light transmission and minimize thermal radiation out of the device- Heat transfer core 724, is fashioned from the same raaterials and using the same techniques as those used to
• the collector 718 also has an internal cavity. Solar radiation 726 is transmitted through the shells 720, 722 to strike heat transfer core 724 where it is absorbed and converted into heat. Heat transfer fluid 72.8 and 730, flows into the converter along the path indicated by the solid arrows. When transfer fluids 728, 730 come into contact with the heat transfer core 724 evaporation occurs. The resulting vapor and the heat it carries are
• the heat transfer fluid also serves to mitiimiz the amount of heat radiated from, the heat transfer core thus increasing the maximum attainable temperature and the overall conversion efficiency
• the heat transfer core may comprise a fluid transfer element and a light absorption element positioned such that sunlight passes through the fluid transfer element, along with the heat transfer fluid, before striking the light absorption element.
• FIG, 8 illustrates a thermally driven energy
• thermal transfer network that could, comprise an array of thermal connectors such as heat pipes, insulated conduits which guide the flow of a heat
• Solar collector 800, thermal source 802, and thermal storage unit 804 provide heat to thermal consoiidator 806.
• Thermal source 802 may be one or more sources of heat including but not limited to the direct combustion of fossil fuels, waste heat from, ind.ust.riai processes or boilers, or via the indirect combustion of fossil fuels producing an exhaust heat source from a reciprocating engine, a. turbine or other heat engine.
• Thermal 802 consoiidator comprises one or more heat exchangers and associated heat transfer connections and heat transfer switches, and its overall function is to aggregate all the heat sources in a way that can be directed by a control system to optimize the quality, quantit and temperature of the heat which it supplies to the system.
• a heat transfer switch could include, for
• a valve which directs the flow of a heat transfer fluid from one conduit to another .
• Heat supplied by the consoiidator is transferred via thermal connector 808, to a ankine or othe heat engine 810.
• the engine converts some portion of this heat into mechanical energy that ca foe subsequently used to drive : a generator to produce electricity 820.
• the engine may comprise an organic rankine cycle wherein the working fluid of the heat engine does not comprise water.
• Waste heat from this process is transferred via thermal connector 812 to heat rejector 816, which rejects the heat to the environment or some other suitable heat sink.
• a portion of the heat going to heat engine 810 may be extracted and used fay cooling unit 818 .
• This unit is a thermally driven cooling system which could rely on absorption,, adsorptien. / steam ejection cooling, or any one of a number of eat driven
• the output is in the form of a cooled thermal medium that can be used to cool buildings or other facilities which can utilize this function, Heat extracto unit 814, can use some portion of the heat to be rejected to provide a heated medium 822 that, may also find use withi a building or other facility for space heating, water heating or other uses.
• the heat for this purpose may also come directly om thermal consoiidator 806 via a path not shown. he location of the cooling unit, the heat engine, and heat extractor may be
• the aforementioned control system is an electronic module with a central processor or processors and interface circuitry, a communications interface, and a variety of sensors to detect the state of the energy generation system as 3 ⁇ 4ell as the energy consumer and the environment, and outputs which are able to control the state of the system and in particular the real time mixture of hea sources supplied to the consumer .
• the state of the generation system could included a variety of characteristics such as the temperature and output of heat from the various sources listed above, the amount of sunlight
• the state of the consumer could include the internal temperature of a household or the heat needs of an industrial process depending on what " Rind, of consumer.
• This sensor information could foe combined with additional information from the communications system which could include weather predictions, and therefore available sunlight, or stored
• control system In general the goal of the control system is to insure that heat is
• the system can adapt to a variety of circumstances during which one or more of the heat sources is unavailable for reasons such as weather, lack of sun at night or an inefficient mix of
• FIG. 9 a cutaway drawing of
• Housing 902 is similar to collector housing plate 328 of FIG. 3 in both function and material composition. It is hermetically sealed to facesheet 904 which, is similar in function and. material
• Facesheet 904 may also have anti-reflection coatings on one. or both of its
• Sunlight 906 is transmitted through facesheet 904 and propagates through fluid transfer element 910, 912 and is ultimately incident on light absorption element 014,
• Light absorption element 914 may be in the form of a sheet of metal, glass, plastic or a fabric made from these materials, or other materials in planar form. It may also foe a porous medium made of the same materials. Th material must be capable of withstanding temperatures as high as several hundred degrees centigrade or more without degradation. In either case the surface on to which light ⁇ 06 is incident is coated or otherwise treated so that it is highly absorbing to visible and near infrared light and has a low emissivity for frequencies longer than the near infrared.
• fluid transfer element 910,912 comprises two different materials wherein fluid transfer element 910 may be an aerogel material in a form and composition as described for the embodiment of FIG, 3, and fluid transfer element 912 may be a material such as fiberglass, rock wool, a vacuum insulating panel, or some other material or component with low thermal conductivity. In this embodiment it is possible that no fluid is transferred through fluid transfer element 912 and all of the fluid to be heated passes through fluid transfer element 914.
• light absorption element 914 is suspended by mechanical mounts not shown, which may foe in the form of support rods, struts,
• tensioned fibers or wires, or othe elements which are connected to the collector housing 902 are designed, via their construction or material composition or both, to minimize the amount of heat, which is conducted from the light absorption element to the housing,
• Ingress conduit 918 provides a means to admit a heat transfer fluid 920, into the interio of the housing 902 wher it flows in the space between the interior surface of the housing 902 and the exterior of fluid transfer element 910,912. The heat
• transfer fluid 920 subsequently flows through the "porous surface of fluid transfer element 910 and 912, if fluid transfer element 912 is porous.
• the heat transfer fluid follows generally along the path of the arrows 922 r and propagates through: the fluid transfer element where it subsequently comes into contact with light absorption element 914, This causes the temperature of the heat transfer fluid to rise and the resulting heated fluid 924 exits the collector housing 902 via egress conduit 926.

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• 2016
  • 2016-04-20 WO PCT/US2016/028521 patent/WO2016172266A1/en active Application Filing
  • 2016-04-20 EP EP16783805.1A patent/EP3286506A4/de not_active Withdrawn

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