Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
  • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
  • H01L31/052—Cooling means directly associated or integrated with the PV cell, e.g. integrated Peltier elements for active cooling or heat sinks directly associated with the PV cells
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
  • F28D15/00—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
  • F28D15/02—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
  • F28D15/0266—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes with separate evaporating and condensing chambers connected by at least one conduit; Loop-type heat pipes; with multiple or common evaporating or condensing chambers
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
  • F28D15/00—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
  • F28D15/02—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
  • F28D15/0275—Arrangements for coupling heat-pipes together or with other structures, e.g. with base blocks; Heat pipe cores
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
  • F28D15/00—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
  • F28D15/02—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
  • F28D15/04—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes with tubes having a capillary structure
  • F28D15/046—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes with tubes having a capillary structure characterised by the material or the construction of the capillary structure
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
  • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
  • H01L31/052—Cooling means directly associated or integrated with the PV cell, e.g. integrated Peltier elements for active cooling or heat sinks directly associated with the PV cells
  • H01L31/0521—Cooling means directly associated or integrated with the PV cell, e.g. integrated Peltier elements for active cooling or heat sinks directly associated with the PV cells using a gaseous or a liquid coolant, e.g. air flow ventilation, water circulation
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
  • F24S40/00—Safety or protection arrangements of solar heat collectors; Preventing malfunction of solar heat collectors
  • F24S40/50—Preventing overheating or overpressure
  • F24S40/55—Arrangements for cooling, e.g. by using external heat dissipating means or internal cooling circuits
• • 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
  • Y02E10/50—Photovoltaic [PV] energy

Definitions

• Cooling assembly for light concentrator photovoltaic systems
• the present invention relates to a cooling assembly for light, in particular for sun concentrator photovoltaic systems capable of tracking a moveable light source and having one or an array of photovoltaic devices (PN cells or PV modules), the cooling assembly comprising a heat pipe attached at a heat transfer surface of a photovoltaic (PV) device or at the heat transfer surfaces of a plurality of neighboring PV devices.
• PN cells or PV modules photovoltaic devices
• the sunlight is concentrated by means of an elongate parabolic mirror, on the light-sensitive surfaces of a great number of P V modules arranged in series. It is obvious that intensive solar radiation induces substantial heating of PV cells and PV modules and therefore they cannot be operated without efficient cooling.
• cooling bodies usually of metal, such as aluminum, are mounted, their cooling fins serving to transfer the heat to the ambient air due to convection and radiation.
• the surface area of the cooling fins is several times larger than the surface area of the PV modules.
• PV device(s) wherein the heat is radiated presumably from its outer surface.
• the object is achieved ac- cording to the present invention by the heat pipe comprising: an expanded foot portion attached to said heat transfer surface of the PV device to be cooled, a head portion, hollow on the inside, whose inside is in direct communication with the foot and has a smaller cross-sectional size than the foot portion, - so that a working fluid inside the heat pipe is kept in the foot portion even in operating positions where the heat pipe is maximally tilted from a vertical position in which the foot portion is positioned in a position below the head portion, and a cladding of open porous wick material covering at least those surface areas inside the foot portion which can be contacted by the working fluid during normal opera- tion.
• the entire inner surface of the heat pipe is provided with a lining or cladding.
• liquid working fluid is always held in the lining of the head portion so that the liquid and gaseous components of the working fluid do not impede each other's movement.
• Adjustable (tracking) sun concentrator PV systems are usually arranged parallel to the ground, in a north-south orientation, which poses no problems near the equator.
• it may be suitable to provide the entire system with a capability of being pivoted about its horizontal axis so that it can track the azimuth of the sun according to the change of the seasons. In particular in very long systems, this would lead to the working fluid collecting at one end of the heat pipe, so that safe cooling cannot be ensured. This is why in a preferred embodiment, at least the foot portion of the heat pipe is subdivided into individual chambers in its longitudinal direction.
• the head portion of the heat pipe preferably has cooling fins.
• the outermost cooling fin i.e. the surface directly facing the sunlight in operation, is preferably pro- vided with a reflective coating.
• the head portion is preferably formed in the shape of one or more tubes, wherein the cooling fins are attached on the outer surface(s) of the tube(s).
• the heat pipe is detachably connected to the heat transfer surface of the PV device.
• the connection can comprise a solder metal layer, a nut-and-bolt connection and/or a clip mechanism. Combinations of these attachment mechanisms are also conceivable.
• the cooling performance in adjustable (tracking) sun radiation focussing PV systems may be considerably improved.
• Fig. 1 is a longitudinal sectional view of a cooling assembly according to the invention attached to a PV module
• Fig. 2 is a longitudinal sectional view of a cooling assembly having a modified attachment
• Fig. 3 is a schematic representation of the cooling assembly at different times of day
• Fig. 4 is a schematic isometric view of an array of a plurality of cooling devices arranged in series
• Fig. 5 is a schematic view of a sun concentrator photovoltaic system comprising a cooling assembly according to the invention, in which the sun concentrator element is designed as a Fresnel lens.
• Fig. 1 shows a cooling assembly according to the present invention, having a heat exchange pipe 8, consisting of a foot portion 9 with an expanded cross section and a head portion 12 with a cross-sectional area (each cross section being in a plane parallel to the surface of PV module 1 , see below) which is considerably smaller than that of foot por- tion 9.
• Head portion 12 may comprise an elongate fin as known from US 5,660,644 A, to which preferably external cooling fins are attached.
• discrete tubes Fig. 4
• the hollow insides of foot portion 9 and head portion 12 are in direct communication with each other.
• the outer wall of heat pipe 8 is of a material with excellent thermal conductivity, such as copper. Other materials like stainless steel or anodized aluminum may be used as well.
• the expanded foot portion 9 is here shown to have the shape of a flat cuboid. Other shapes, e.g. elongate pear shaped or pyramid shaped, are also possible. The essentially triangular cross-sectional shape of the heat pipe known from US 5,660,644 A would also be suitable. It is always essential that the liquid working fluid does not flow out of the foot portion 9 into the head portion 12 in any of the possible operating positions.
• the inner surface of at least the expanded foot portion 9 is provided with a lining or cladding 11 of an open cell material providing a wicking action as well as having a good thermal conductivity, such as a metal, a sintered ceramic material, carbon or ceramic fibers, metal mesh, felt or a combination of said materials. It is also possible to arrange axial capillary grooves at the inner wall of heat pipe 8. It is essential for the liquid working fluid to wet the material of lining 11 , so that it can penetrate the pores or cavities of the lining and be held there by adhesive (capillary) forces.
• cooling fins 13 On the outer surface of tube-like head portion 12, there are metal cooling fins 13, the topmost thereof directly exposed to the sunlight being provided with a reflective layer 20. The lower surface of said cooling fin 13 as well as the surfaces of the remaining cooling fins 13 and heat pipe 8 are blackened.
• Fig. 1 further shows the attachment of the cooling assembly thus formed on a photovoltaic module 1.
• the surface thereof, facing downwards in the drawing, is exposed to sunlight.
• the top surface is provided with a heat conductive adhesive layer 3, connecting PV module 1 to an intermediate metallic plate 4.
• Cooling assembly 8 is attached to intermediate metallic plate 4 by means of spring clips 7 attached to foot portion 9.
• cooling assembly 8 is additionally attached to intermediate metallic plate 4 by means of an additional heat conductive adhesive layer 3 while the opposite side of intermediate metallic plate 4 is attached to the PV module by means of the heat conductive adhesive layer 3 or a solder layer 5.
• cooling assembly 8 may be detached from P V module 1 , so that the latter may be exchanged if necessary.
• cooling assembly 8 may be attached to intermediate metallic plate 4 by means of a nut- and-bolt connection (not shown). It would also be possible to bore threaded holes in intermediate metallic plate 4 so that a corresponding thread engaging connection means could be directly screwed into intermediate metallic plate 4.
• the height of foot portion 9 may be as much as a few centimeters.
• the width and/or the length of foot portion 9 corresponds to the width and length, respectively, of the heat transfer surface of one or of a plurality of neighboring PV devices 1. In the embodiment shown here its width is somewhat larger than that of PV module 1.
• the heat is transferred via the thermally conductive layer 3 and intermediate metallic plate 4 directly to the bottom of foot portion 9 (Fig. 1) or via the additional heat conductive adhesive layer 3 or solder layer 5 (Fig. 2). Due to the effect of the incoming heat, working fluid 10 on and in lining 11 is heated and evaporated. The vapor always flows to the coolest part of heat pipe 8 in tube-shaped section 12, where it condenses and transfers its latent evaporation heat to the wall of tube 12, from where the heat is dissipated to the atmosphere from cooling fins 13 by means of radiation and convection. The condensed working fluid 10 flows to foot portion 9 of heat pipe 8 by the effect of gravity, thereby closing the cycle.
• the inner diameter of tube 12 may be between 1 and 3 cm (about 0.4 to 1.2 in); it should be optimized in such a way that the counter flows from the gaseous and condensed working fluid counteract each other as little as possible.
• a plurality of tubes 12 may be provided; their total number per foot portion 9 is determined by the cooling performance required in the specific operating conditions of the sun concentrator photovoltaic system.
• Fig. 3 illustrates the functional purpose of the design of heat pipe 8 having a wide foot portion 9 and narrow upper tube 12.
• the cooling assembly passes from a nearly horizontal position in the morning (Fig. 3, on the left) via a vertical position (at noon) to an opposite, also nearly horizontal postion (Fig. 3, on the right) in the evening.
• the liquid component of working fluid 10 is always prevented from flowing from foot portion 9 into head portion 12.
• working fluid may be collected against the side surfaces of foot portion 9 while in the extreme positions (Fig. 3, left and right) it cannot flow into head portion 12.
• an efficient cooling performance is continued, since lining 11 evenly spreads the working fluid over the heat absorbing bottom surface of the expanded foot portion 9.
• a PV module and even a long series of PV modules together with their associated heat pipes 8 may be arranged parallel to the ground. It is thus ensured even with a heat pipe 8 covering a multitude of PV modules that working fluid 10 is spread reasonably evenly over the bottom of foot portion 9. With certain limitations this is true even when the photovoltaic system is adjusted with the seasons, i.e. the array of PV modules is slightly inclined or pivoted with respect to the horizontal position.
• a foot portion 9 of an elongate heat pipe 8 it is therefore necessary in such systems for a foot portion 9 of an elongate heat pipe 8 to be subdivided into individual chambers by partition walls, each chamber having at least one tubular head portion 12, or to provide shorter transfer tubes 8, as schematically shown in Fig. 4.
• Each foot portion 9 of a heat pipe 8 only covers the length of one PV module 1. Still shorter units are not possible since the heat dissipation would be in- sufficient at the abutment between neighboring foot portions 9.
• the height of tube-shaped head portion 12 of heat pipe 8 having cooling fins 13 attached thereto determines the size of the overall heat dissipating surface and therefore the attainable cooling performance of the radiator (Fig. 4). With the neighboring cooling fins 13 spaced in intervals of 1 cm (0.4 inches) on the outer cooling surface of tube 12, and with as much as thirty cooling fins 13 having a thickness of 1 mm (0.04 in) and a width of 15 cm (5.9 in), a heat dissipating surface area of 3,000 cm 2 (465 in 2 ) is achieved.
• the available cooling performance may be increased almost infinitely.
• the number of tube- shaped head portions 12 may also be increased with respect to the surface area of foot portion 9, in turn increasing the surface area of the individual cooling fins.
• the cooling assembly according to the invention may not only be used with new photovoltaic systems, but may also be retrofitted to existing and operating sun concentrator photovoltaic systems.
• Fig. 5 schematically shows a sun concentrator photovoltaic system in which an elongate Fresnel lens 19 positioned normal to the drawing plane is used as a sunlight concentrator.
• the cooling assembly linked via a rotary axis 17 to a foot 14, comprises a centrally expanded foot portion 9 and tubes 12 symmetrically extending upwards having metallic cooling fins 13 attached thereto.
• the cooling assembly is fitted to PV module 1 and is held in place by spring clips 7 (see also Fig. 1, 2).
• the inner walls of the cooling device are coated with a lining 11 of a porous material, and specially formed, i.e. H- shaped, walls and linings of porous material 15 lift the working fluid up from the bottom of expanded foot portion 9 to thermally contact PV module 1 via intermediate metallic plate 4.
• the heat is dissipated from PV module 1 in the same way as de- scribed above.
• cooling pipe 8 should also be subdivided as described with reference to Fig. 4.
• cooling assembly may be used with photovoltaic systems where parabolic mirrors are used for focussing the light.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Life Sciences & Earth Sciences (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Thermal Sciences (AREA)
• Sustainable Development (AREA)
• General Physics & Mathematics (AREA)
• Power Engineering (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Computer Hardware Design (AREA)
• Electromagnetism (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• Photovoltaic Devices (AREA)

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Cited By (10)

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• 2002
  • 2002-11-05 DE DE10251446A patent/DE10251446B4/de not_active Expired - Fee Related
• 2003
  • 2003-11-05 AU AU2003283110A patent/AU2003283110A1/en not_active Abandoned
  • 2003-11-05 WO PCT/CA2003/001709 patent/WO2004042828A2/en not_active Application Discontinuation

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