WO2004042828A2 - Cooling assembly for light concentrator photovoltaic systems - Google Patents

Cooling assembly for light concentrator photovoltaic systems Download PDF

Info

Publication number
WO2004042828A2
WO2004042828A2 PCT/CA2003/001709 CA0301709W WO2004042828A2 WO 2004042828 A2 WO2004042828 A2 WO 2004042828A2 CA 0301709 W CA0301709 W CA 0301709W WO 2004042828 A2 WO2004042828 A2 WO 2004042828A2
Authority
WO
WIPO (PCT)
Prior art keywords
heat pipe
foot portion
cooling
cooling device
foot
Prior art date
Application number
PCT/CA2003/001709
Other languages
French (fr)
Other versions
WO2004042828A3 (en
Inventor
Alexander Sergeevich Osipov
George L. Rubin
Leonid B. Rubin
Original Assignee
Day4 Energy Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Day4 Energy Inc. filed Critical Day4 Energy Inc.
Priority to AU2003283110A priority Critical patent/AU2003283110A1/en
Publication of WO2004042828A2 publication Critical patent/WO2004042828A2/en
Publication of WO2004042828A3 publication Critical patent/WO2004042828A3/en

Links

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.

Abstract

A cooling assembly for light concentrator photovoltaic systems is described having one or an array of photovoltaic devices (PV cells or PV modules), wherein the cooling assembly is provided to be attached to a heat transfer surface of a PV device (1) or to the heat transfer surfaces of a plurality of neighboring PV devices (1). The cooling assembly comprises a heat pipe (8). Said heat pipe (8) comprises: an expanded foot portion (9) attached to said heat transfer surface of said PV device (1) to be cooled, a head portion (12), hollow on the inside, whose inside is in direct communication with the inside of said foot (9) and has a smaller cross-sectional size than said foot portion (9), so that a working fluid (10) inside said heat pipe (8) is kept in said foot portion (9) even in operating positions where said heat pipe (8) is maximally tilted from a vertical position in which said foot portion (9) is positioned in a position below said head portion (12), and a cladding (11) of open porous wick material covering at least those surface areas inside said foot portion (9) which can be contacted by said working fluid (10) during normal operation.

Description

Cooling assembly for light concentrator photovoltaic systems
Field of the invention
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.
Description of the prior art
Traditional photovoltaic systems having a plurality of cells and modules, which are operating under natural solar radiation and grouped in flat panels, can be operated without forced cooling. Therein, reductions in efficiency due to slightly increased operating temperatures are acceptable. In high-performance systems (such as G. Sala et al.: The EUCLIDES Prototype: An Efficient Parabolic Trough for PV Concentration
(http://www.users.globalnet.co.uk ~blootl/trackers/eucl.htm)) 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. On the surfaces or sides of the PV modules opposite the light- sensitive surfaces, 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. However, even using such cooling fins, the temperature of the PV mod- ules can only be reduced to a temperature difference of Δt = 30 to 35°C above the temperature of the ambient air. Due to the limited thermal conductivity of the metal of the cooling bodies and cooling fins, a further enlargement of their surface is no longer efficient and economical. Similar difficulties are encountered also with systems where the sunlight is focussed onto the light-sensitive surfaces of the PV modules using Fresnel lens arrangements. From US 5,660,644 A a cooling assembly of the kind described above and in the pre-characterizing portion of claim 1 is known for use in aerospace applications. Although US 5,660,644 does not contain any details on the performance of the heat pipe cooling assembly it claims that the heat pipe allows a particularly effective cooling of the
PV device(s), wherein the heat is radiated presumably from its outer surface.
It is therefore an object of the present invention to further improve, and in particular to further develop, a cooling assembly for PV devices in a way that allows effi- cient cooling of PV devices in each operating position throughout the day, for ground- based PV devices.
Summary of the invention
In a cooling assembly of the above mentioned type, 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.
From US 4,320,246 it is known per se to provide a cladding of a wick material inside a heat pipe of a fixed focussing photovoltaic system. It is essential for the dimensions of the head and foot portions as well as for the amount of the working fluid of the cooling assemblies of the present invention to be such that even when the heat pipe is maximally tilted during daily operation of the PV sun concentrator, the liquid portion of the working fluid always remains within the foot por- tion.
Preferably the entire inner surface of the heat pipe is provided with a lining or cladding. Herein, 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. When installing the system in higher latitudes, however, 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. Furthermore, 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).
In a further preferred embodiment, 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.
By the cooling assembly according to the invention, the cooling performance in adjustable (tracking) sun radiation focussing PV systems may be considerably improved.
It is also possible to retrofit the cooling assembly or to replace PV modules according to the invention to existing systems due to the detachable connection on the PV module to be cooled.
Brief description of the drawings
Exemplary embodiments of the cooling device according to the present invention will be described in the following with reference to the accompanying drawings, in which:
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; and 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.
Description of the preferred embodiments
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. In the exemplary embodiment shown here, discrete tubes (Fig. 4) are contemplated, which are in communication with the elongate foot portion and to which cooling fins are attached. 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.
If the inner surface of the tube-shaped head portion 12 is left free, the heat from the steam molecules of the working fluid is directly transferred to the tube wall and condensed fluid is falling down under gravity force. On the other hand, providing a lining 11 also on the surface of tube-shaped head portion 12 has the advantage that condensed molecules of the working fluid will flow down mainly along the walls and do not interfere with the upward movement of vaporized molecules. In the assembly shown in Fig. 1 the sunlight incident from above on a "concentrator" (not shown), i.e. on a parabolic mirror or an elongate Fresnel lens, is focussed on the light sensitive surface of PV module 1.
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.
Fig. 2 shows an alternative embodiment of the attachment: 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.
In both types of attachment, cooling assembly 8 may be detached from P V module 1 , so that the latter may be exchanged if necessary. Alternatively or additionally, 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.
From 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. For each foot portion of a heat pipe 8, 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. In a photovoltaic system of the type tracking the sun's position, 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. By the inventive design of the heat pipe the liquid component of working fluid 10 is always prevented from flowing from foot portion 9 into head portion 12. Even though in the extreme positions (Fig. 3, left and right) 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. On the other hand, even in these extreme positions, 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.
Near the equator, between the northern and the southern tropics (Tropic of Cancer and Tropic of Capricorn) 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. However, in farther northern or southern latitudes, the inclination of an array of photovoltaic modules 1 varies with the seasons and deviates strongly from the horizontal, so that the liquid portions of the working fluid flow together at one end of an elongate foot portion and uniform wetting of the heat transfer surface of foot portion 9 would not be ensured even using lining 11. Overheating would thus occur in places no longer sufficiently wetted with working fluid.
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 cm2 (465 in2) is achieved. Thus, with a PV module cooling assembly lenghth of 1 m (254 in), an overall fins heat dissipating surface area of 3,000 * 30 = 90,000 cm2 = 9 m2 (13,950 in2 / 10,76 square yards) is achieved. This is enough to keep the temperature of the PV module to Δt
? 20°C above the ambient temperature, even if the incident solar radiation is 1,200 W/m in no-wind conditions.
This means that by choosing the height of the tube-shaped head portion 12, 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. These abilities drastically improve the cooling performance and the possible adaptation to the required solar radiation concentration and specific operating conditions of the sun concentrator photovoltaic system.
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. In this design, the heat is dissipated from PV module 1 in the same way as de- scribed above. When installing the photovoltaic system in higher latitudes, cooling pipe 8 should also be subdivided as described with reference to Fig. 4.
Almost the same type of cooling assembly may be used with photovoltaic systems where parabolic mirrors are used for focussing the light.

Claims

Claims
1. A cooling device for light concentrator photovoltaic systems capable of tracking a light source, comprising one or an array of photovoltaic devices (PV cells or PV modules), said cooling device comprising a heat pipe (8) attached at a heat transfer sur- face of a P V device ( 1 ) or at the heat transfer surfaces of a plurality of neighboring P V devices (1), characterized in that said heat pipe (8) comprises: an expanded foot portion (9) attached to said heat transfer surface of PV device (1) to be cooled, a head portion (12), hollow on the inside, whose inside is in direct communi- cation with said foot (9) and has a smaller cross-sectional size than said foot portion (9), so that a working fluid (10) inside said heat pipe (8) is kept in said foot portion (9) even in operating positions where said heat pipe (8) is maximally tilted from a vertical position in which said foot portion (9) is positioned in a position below said head portion (12), and - a cladding (11) of open porous wick material covering at least those surface areas inside said foot portion (9) which can be contacted by said working fluid (10) during normal operation.
2. The cooling device according to claim 1 , characterized in that said cladding (1 1) covers said total inner surface of said heat pipe (8).
3. The cooling device according to claim 1, characterized in that at least the said foot portion (9) of said heat pipe (8) is subdivided into individual chambers in its longitudinal direction.
4. The cooling device according any of the preceding claims, characterized in that cooling fins (13) are attached on the outer surface of said head portion (12).
5. The cooling device according any of the preceding claims, characterized in that said head portion (12) of said heat pipe (8) is formed to be one or more pipes.
6. The cooling device according to claim 4, characterized in that said outer surface of a cooling fin (13) directly exposed to the sunlight has a reflecting layer (20) thereon.
7. The cooling device according to any of the preceding claims, characterized in that said heat pipe (8) is removably attached to said heat transfer surface of said PV device (1).
8. The cooling device according to claim 7, characterized in that the attachment of said heat pipe (8) to said PV device (1) is effected by means of a soldering layer (5) and/or by means of a screw-nut connection and/or by means of a clamp mechanism (7).
PCT/CA2003/001709 2002-11-05 2003-11-05 Cooling assembly for light concentrator photovoltaic systems WO2004042828A2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2003283110A AU2003283110A1 (en) 2002-11-05 2003-11-05 Cooling assembly for light concentrator photovoltaic systems

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE10251446.1 2002-11-05
DE10251446A DE10251446B4 (en) 2002-11-05 2002-11-05 Cooling arrangement for light-bundling photovoltaic systems

Publications (2)

Publication Number Publication Date
WO2004042828A2 true WO2004042828A2 (en) 2004-05-21
WO2004042828A3 WO2004042828A3 (en) 2005-01-13

Family

ID=32115227

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CA2003/001709 WO2004042828A2 (en) 2002-11-05 2003-11-05 Cooling assembly for light concentrator photovoltaic systems

Country Status (3)

Country Link
AU (1) AU2003283110A1 (en)
DE (1) DE10251446B4 (en)
WO (1) WO2004042828A2 (en)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1990582A1 (en) * 2007-05-07 2008-11-12 Electrolux Home Products N.V. Gas cooking appliance
WO2009111908A1 (en) * 2008-03-14 2009-09-17 Chen Jen-Shyan Solar cell device with high heat dissipation efficiency
WO2010128251A1 (en) 2009-05-06 2010-11-11 Commissariat A L'energie Atomique Et Aux Energies Alternatives Hybrid solar receiver, and concentrating solar system comprising the same
US7888168B2 (en) 2007-11-19 2011-02-15 Applied Materials, Inc. Solar cell contact formation process using a patterned etchant material
JP2012094596A (en) * 2010-10-25 2012-05-17 Kanai Educational Institution Light condensing power generator
US8183081B2 (en) 2008-07-16 2012-05-22 Applied Materials, Inc. Hybrid heterojunction solar cell fabrication using a metal layer mask
US8731139B2 (en) 2011-05-04 2014-05-20 Media Lario S.R.L. Evaporative thermal management of grazing incidence collectors for EUV lithography
US8746975B2 (en) 2011-02-17 2014-06-10 Media Lario S.R.L. Thermal management systems, assemblies and methods for grazing incidence collectors for EUV lithography
WO2015101692A1 (en) * 2013-12-31 2015-07-09 Abengoa Solar New Technologies, S.A. Hybrid system comprising a thermosolar parametric cylinder and a photovoltaic receiver
US20150318820A1 (en) * 2014-05-05 2015-11-05 David Timothy Dobney Rotating Furling Catenary Solar Concentrator

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102004043205A1 (en) * 2004-09-03 2006-03-09 Fischer, Georg Photo-voltaic unit for use in roof of e.g. industrial halls, has temperature control effecting cooling or heating of unit such that constant temperature is maintained, and cooling body designed as hollow body via which medium is supplied
DE102004055186B4 (en) * 2004-11-16 2012-07-19 Beck Energy Gmbh Photovoltaic module with submodules
DE102004055185A1 (en) * 2004-11-16 2006-05-24 Beck Energie Gmbh Photovoltaic module for an electronic device comprises photovoltaic cells arranged on a support plate below which is located a support element in a detachedly connected manner
DE102007028416A1 (en) * 2007-06-20 2008-12-24 Dracowo Forschungs- Und Entwicklungs Gmbh Coating and carrier materials for plants for photovoltaic- and solar thermal generation, are applied on roofs of light-weight construction halls
DE102009012720A1 (en) * 2009-03-11 2010-09-16 Meuleman, André, Dipl.-Ing. Cooling system for photovoltaic module that is utilized on e.g. roofs, for converting sunlight into electricity, has corrugated plate and chamber connected to each other by openings to form cooling circuit for photovoltaic module
DE102010036393A1 (en) * 2010-07-14 2012-01-19 Sunsail Energy Gmbh & Co. Kg Hybrid collector mounted in roof for solar-power generation, has collector module having circular transparent tube in which metallic carrier for heat-transferring is located with heat conducting pipe

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4200472A (en) * 1978-06-05 1980-04-29 The Regents Of The University Of California Solar power system and high efficiency photovoltaic cells used therein
US4320246A (en) * 1978-05-04 1982-03-16 Russell George F Uniform surface temperature heat pipe and method of using the same
US5660644A (en) * 1995-06-19 1997-08-26 Rockwell International Corporation Photovoltaic concentrator system

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10321890A (en) * 1997-05-15 1998-12-04 Hitachi Chem Co Ltd Solar battery cooling system

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4320246A (en) * 1978-05-04 1982-03-16 Russell George F Uniform surface temperature heat pipe and method of using the same
US4200472A (en) * 1978-06-05 1980-04-29 The Regents Of The University Of California Solar power system and high efficiency photovoltaic cells used therein
US5660644A (en) * 1995-06-19 1997-08-26 Rockwell International Corporation Photovoltaic concentrator system

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU2008248995B2 (en) * 2007-05-07 2011-06-30 Electrolux Home Products Corporation N.V. Gas cooking appliance
WO2008135140A2 (en) * 2007-05-07 2008-11-13 Electrolux Home Products Corporation N.V. Gas cooking appliance
WO2008135140A3 (en) * 2007-05-07 2009-04-30 Electrolux Home Prod Corp Gas cooking appliance
US8997731B2 (en) 2007-05-07 2015-04-07 Electrolux Home Products Corporation N.V. Gas cooking appliance
CN101663539B (en) * 2007-05-07 2013-01-30 伊莱克斯家用产品股份有限公司 Gas cooking appliance
EP1990582A1 (en) * 2007-05-07 2008-11-12 Electrolux Home Products N.V. Gas cooking appliance
US7888168B2 (en) 2007-11-19 2011-02-15 Applied Materials, Inc. Solar cell contact formation process using a patterned etchant material
WO2009111908A1 (en) * 2008-03-14 2009-09-17 Chen Jen-Shyan Solar cell device with high heat dissipation efficiency
JP2011512657A (en) * 2008-03-14 2011-04-21 ネオバルブ テクノロジーズ，インコーポレイテッド Solar cell device with high heat dissipation efficiency
US8183081B2 (en) 2008-07-16 2012-05-22 Applied Materials, Inc. Hybrid heterojunction solar cell fabrication using a metal layer mask
US8309446B2 (en) 2008-07-16 2012-11-13 Applied Materials, Inc. Hybrid heterojunction solar cell fabrication using a doping layer mask
CN102422440A (en) * 2009-05-06 2012-04-18 原子能与替代能源委员会 Hybrid solar receiver, and concentrating solar system comprising the same
FR2945376A1 (en) * 2009-05-06 2010-11-12 Commissariat Energie Atomique HYBRID SOLAR RECEIVER FOR THE PRODUCTION OF ELECTRICITY AND HEAT AND CONCENTRATED SOLAR SYSTEM COMPRISING SUCH A RECEIVER
WO2010128251A1 (en) 2009-05-06 2010-11-11 Commissariat A L'energie Atomique Et Aux Energies Alternatives Hybrid solar receiver, and concentrating solar system comprising the same
US9029684B2 (en) 2009-05-06 2015-05-12 Commissariat à l'énergie atomique et aux énergies alternatives Hybrid solar receiver and concentrating solar system comprising the same
JP2012094596A (en) * 2010-10-25 2012-05-17 Kanai Educational Institution Light condensing power generator
US8746975B2 (en) 2011-02-17 2014-06-10 Media Lario S.R.L. Thermal management systems, assemblies and methods for grazing incidence collectors for EUV lithography
US8731139B2 (en) 2011-05-04 2014-05-20 Media Lario S.R.L. Evaporative thermal management of grazing incidence collectors for EUV lithography
WO2015101692A1 (en) * 2013-12-31 2015-07-09 Abengoa Solar New Technologies, S.A. Hybrid system comprising a thermosolar parametric cylinder and a photovoltaic receiver
US20150318820A1 (en) * 2014-05-05 2015-11-05 David Timothy Dobney Rotating Furling Catenary Solar Concentrator
US9673751B2 (en) * 2014-05-05 2017-06-06 David Dobney Rotating furling catenary solar concentrator

Also Published As

Publication number Publication date
WO2004042828A3 (en) 2005-01-13
DE10251446A1 (en) 2004-05-19
AU2003283110A1 (en) 2004-06-07
DE10251446B4 (en) 2004-11-11

Similar Documents

Publication Publication Date Title
US4513732A (en) Passive integral solar heat collector system
WO2004042828A2 (en) Cooling assembly for light concentrator photovoltaic systems
US4686961A (en) Integrated solar thermal energy collector system
US20070272295A1 (en) Heat sink for photovoltaic cells
US7569764B2 (en) Solar modules with tracking and concentrating features
US20100186820A1 (en) Solar electricity generation with improved efficiency
Senthil et al. A holistic review on the integration of heat pipes in solar thermal and photovoltaic systems
US20100294266A1 (en) Concentrated solar thermal energy collection device
US4566434A (en) Solar energy collector
US11336224B2 (en) Solar receivers and methods for capturing solar energy
Kalogirou Nontracking solar collection technologies for solar heating and cooling systems
US10431705B2 (en) Cooling system for high performance solar concentrators
US4522193A (en) Solar collector device
JP6929972B2 (en) Condensing multifunctional solar energy system
US11575347B1 (en) Passive cooling method for high concentrating photovoltaic
US20100051088A1 (en) Photovoltaic solar concentrating power system
RU94316U1 (en) SOLAR PANEL
TWI360635B (en)
WO2009075611A2 (en) Heating panel
KR101088408B1 (en) Sunlight concentraing device for natural lighting capable of cooling without power supply
KR100779428B1 (en) Solar collector with reflector and double-sided coating to collect solar thermal
JPS6027312Y2 (en) solar heat collector
KR101001733B1 (en) solar heat collecting unit
CN108413632B (en) Tower type solar volumetric heat collector
TWI360636B (en)

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A2

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NI NO NZ OM PG PH PL PT RO RU SC SD SE SG SK SL SY TJ TM TN TR TT TZ UA UG US UZ VC VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A2

Designated state(s): BW GH GM KE LS MW MZ SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LU MC NL PT RO SE SI SK TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
122 Ep: pct application non-entry in european phase
NENP Non-entry into the national phase in:

Ref country code: JP

WWW Wipo information: withdrawn in national office

Country of ref document: JP