WO2016098107A2 - Système permettant d'améliorer l'efficacité d'un panneau solaire et son procédé d'utilisation - Google Patents

Système permettant d'améliorer l'efficacité d'un panneau solaire et son procédé d'utilisation Download PDF

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Publication number
WO2016098107A2
WO2016098107A2 PCT/IL2015/051214 IL2015051214W WO2016098107A2 WO 2016098107 A2 WO2016098107 A2 WO 2016098107A2 IL 2015051214 W IL2015051214 W IL 2015051214W WO 2016098107 A2 WO2016098107 A2 WO 2016098107A2
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WO
WIPO (PCT)
Prior art keywords
heat
solar panel
capacitor
thermal energy
pcm
Prior art date
Application number
PCT/IL2015/051214
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English (en)
Other versions
WO2016098107A3 (fr
Inventor
Nicolas David MUNERMAN
Yuval LEMBERG
Niv Cohen
Original Assignee
Leos Space Systems Ltd.
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Publication date
Application filed by Leos Space Systems Ltd. filed Critical Leos Space Systems Ltd.
Publication of WO2016098107A2 publication Critical patent/WO2016098107A2/fr
Publication of WO2016098107A3 publication Critical patent/WO2016098107A3/fr

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Classifications

    • 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
    • F28D20/00—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00
    • F28D20/02—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using latent heat
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64G—COSMONAUTICS; VEHICLES OR EQUIPMENT THEREFOR
    • B64G1/00—Cosmonautic vehicles
    • B64G1/22—Parts of, or equipment specially adapted for fitting in or to, cosmonautic vehicles
    • B64G1/42—Arrangements or adaptations of power supply systems
    • B64G1/44—Arrangements or adaptations of power supply systems using radiation, e.g. deployable solar arrays
    • B64G1/443—Photovoltaic cell arrays
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64G—COSMONAUTICS; VEHICLES OR EQUIPMENT THEREFOR
    • B64G1/00—Cosmonautic vehicles
    • B64G1/22—Parts of, or equipment specially adapted for fitting in or to, cosmonautic vehicles
    • B64G1/46—Arrangements or adaptations of devices for control of environment or living conditions
    • B64G1/50—Arrangements or adaptations of devices for control of environment or living conditions for temperature control
    • 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
    • F24S60/00—Arrangements for storing heat collected by solar heat collectors
    • F24S60/10—Arrangements for storing heat collected by solar heat collectors using latent heat
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S60/00—Arrangements for storing heat collected by solar heat collectors
    • F24S60/20—Arrangements for storing heat collected by solar heat collectors using chemical reactions, e.g. thermochemical reactions or isomerisation reactions
    • 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
    • F28D20/00—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00
    • F28D20/02—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using latent heat
    • F28D20/023—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using latent heat the latent heat storage material being enclosed in granular particles or dispersed in a porous, fibrous or cellular structure
    • 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
    • F28D20/00—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00
    • F28D2020/0004—Particular heat storage apparatus
    • F28D2020/0008—Particular heat storage apparatus the heat storage material being enclosed in plate-like or laminated elements, e.g. in plates having internal compartments
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F13/00—Arrangements for modifying heat-transfer, e.g. increasing, decreasing
    • F28F2013/005—Thermal joints
    • F28F2013/008—Variable conductance materials; Thermal switches
    • 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
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/14—Thermal energy storage
    • 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
    • Y02E70/00—Other energy conversion or management systems reducing GHG emissions
    • Y02E70/30—Systems combining energy storage with energy generation of non-fossil origin

Definitions

  • the present invention in some embodiments thereof, relates to a system for enhancing solar panel efficiency and, more particularly, but not exclusively, to a system to be used in a space environment.
  • the daily cycle of a satellite consists of one orbit of the satellite around the earth. Some cycles contain approximately 60 minutes of daylight (being directly exposed to the sun) and 40 minutes of night while the sun is obscured by the earth. Other cycles vary from the 60/40 ratio.
  • a solar panel in space in daylight operates at a temperature of approximately 340 Kelvin, while at night its temperature can go as low as 130 Kelvin or even lower.
  • One consequence of the high temperature during operation is its efficiency is significantly decreased.
  • United States Pat. App. Pub. 20120060896 describes a device for cooling solar cells by a flowing cooling medium.
  • the cooling medium is in direct or indirect thermal contact with at least one solar cell and with an external cooling unit.
  • the cooling medium at least partially includes a phase transition material. Further, a method for cooling solar cells is provided.
  • United States Pat. No. 7,077,124 the contents of which are incorporated herein by reference, describes a wall integrated thermal solar collector with heat storage capacity including a transparent layer and a solar radiation absorption layer, that is separated by an air gap from the transparent layer.
  • a heat storage layer of phase changing material is positioned in close contact with the solar radiation absorption layer to facilitate heat transfer.
  • a structural panel of thermally insulating material is positioned adjacent to the heat storage layer.
  • United States Pat. No. 6,478,257 the contents of which are incorporated herein by reference, describes Systems and methods that employ a phase change material to provide thermal control of electric propulsion devices (thrusters).
  • a spacecraft is configured to have an electric propulsion thruster.
  • the electric propulsion thruster is surrounded with a phase change material.
  • Suitable phase change materials include high- density polyethylene (HDPE), waxes, paraffin materials, and eutectic salts.
  • HDPE high- density polyethylene
  • the spacecraft is launched into orbit.
  • the electric propulsion thruster is fired for a predetermined period of time. Heat generated by the electric propulsion thruster is absorbed and stored in the phase change material while the thruster is firing. The stored heat is dissipated into space after the thruster has stopped firing.
  • United States Pat. No. 6,107,564 the contents of which are incorporated herein by reference, describes an ultraviolet and infrared reflecting coating with a wide transmission band and a solar cell cover on which the coating has been deposited.
  • the coating contains a multilayer bandpass filter, and some of the layers of this filter are comprised of mixed materials which have a selectable index of refraction.
  • the design can be optimized by varying the index or refraction of at least one of the layers of mixed material.
  • the solar cell includes a multi-junction solar cell structure and a notch filter designed to reflect solar energy that does not contribute to the current output of the multi -junction solar cell.
  • the notch filter allows the solar cell to run cooler (and thus more efficiently) yet it still allows all junctions to fully realize their electrical current production capability.
  • phase change material including multiple phase change materials of different formulations, placed in heat transfer association with an electronics enclosure (e.g., a sealed enclosure) deployed in an environment that causes the electronics and the phase change material to experience periods of heating and periods of cooling.
  • an electronics enclosure e.g., a sealed enclosure
  • the phase change material absorbs heat and changes at least partially from a first state to a second state to maintain the temperature of the electronics at a desirable level.
  • the phase change material reverts at least partially back to the first state for future heat absorption.
  • the phase change material is cooled by a thermally cooler body such as the night sky.
  • the electronics enclosure and phase change material may be placed in a second enclosure covered with a paint having a paint additive that reflects solar radiation.
  • the solar power generation and heat storage device comprises a solar panel assembly, a current condenser and a heat accumulator.
  • the solar panel assembly comprises a solar panel layer, a net- shaped fixing layer, a fireproof heat preservation base plate and heat transfer tubes, wherein the solar panel layer is fixed to the net- shaped fixing layer in an adhesion mode through adhesives, the fireproof heat preservation base plate is installed at the bottom of the net-shaped fixing layer, the heat transfer tubes are installed between the fireproof heat preservation base plate and the net- shaped fixing layer, the solar panel layer is connected with the current condenser through a wire, and the solar panel assembly is connected with the heat accumulator through the heat transfer tubes.
  • An aspect of some embodiments of the invention relates to providing a system and methods to increase the efficiency of a satellite's solar panel system by decreasing its operating temperature.
  • the system absorbs some of the heat from the solar panel during the day, and emits it during the night, to even out the temperature of the solar panel over the course of a cycle.
  • extreme radiation conditions such as solar flares and laser attacks, the large amount of heat accumulated in a short time during the extreme condition is capacitated by the same mechanisms used for temperature control, in an embodiment of the invention.
  • a system for enhancing efficiency of a solar panel comprising: a heat capacitor configured to store and discharge solar panel thermal energy conducted to and from the capacitor; and, a heat removal mechanism configured to reduce the overall thermal energy in the system by discharging thermal energy delivered to the heat removal mechanism.
  • the system further comprises a heat conductance mechanism configured to at least one of shunting thermal energy throughout the system and conducting thermal energy away from the solar panel.
  • system further comprises a controller configured to automatically control at least one of the heat conductance mechanism, the heat capacitor and the heat removal system.
  • the controller is configured to automatically command the heat conductance mechanism to transfer thermal energy to the heat capacitor to absorb thermal energy from the solar panel.
  • the controller is configured to automatically control the heat conductance mechanism to transfer thermal energy from the heat capacitor to the heat removal mechanism for thermal energy discharge.
  • the controller is configured to automatically at least one of the heat conductance mechanism, the heat capacitor, a heat engine and the heat removal system to transfer thermal energy depending on a day and night cycle in which the solar panel operates and/or other operative conditions such as battery charge status.
  • the controller adjusts system control based on at least one of a day and night cycle, battery charge condition, thermal conductivity, thermal cycle, filtering, and goal temperature differential between components.
  • the solar panel is a component of a satellite.
  • the controller is configured to control at least one of satellite altitude and orientation.
  • the at least one of the heat conductance mechanism, the heat capacitor and the heat removal system are embedded in the solar panel.
  • the heat conductance mechanism conducts thermal energy from and across a surface of the solar panel.
  • the system further comprises a heat prevention mechanism configured to reduce the amount of thermal energy absorbed by the system.
  • the heat prevention mechanism utilizes at least one of shading, spectral filtering, varying system geometry and varying reflection coefficient.
  • the system is configured with a flat heat capacitor that abuts and lies parallel to the solar panel.
  • the system is configured with a heat capacitor comprising a plurality of coins.
  • the system is configured with a heat capacitor comprising at least one heat capacitor container operatively connected to at least one of a plurality of heat pipes and conducting materials in thermal connection to the solar panel.
  • the system further comprises at least one switch configured to enable or disable thermal energy flow to at least one the solar panel, the heat capacitor and the heat removal mechanism.
  • the system further comprises a heat engine to generate electricity using a temperature difference between at least two of the solar panel, the heat capacitor and the heat removal system.
  • the system further comprises a heat engine configured to generate a temperature difference between at least two of the solar panel, the heat capacitor and the heat removal system by receiving electrical energy.
  • the heat removal mechanism comprises a first radiator.
  • the radiator is curved.
  • a second radiator is configured with a radiation power distribution based on direction of radiation.
  • the second radiator is configured to radiate away from the solar panel.
  • the second radiator is curved.
  • the heat capacitor is configured with a plurality of partitions to at least one of reduce sloshing and turbulence and increase rigidity.
  • system further comprises at least one sensor in communication with the controller.
  • the heat capacitor is configured to maintain a volume or pressure range by providing at least one of a sponge, a pressurized gas and a counterpart material which exhibits volume change characteristics inverse to a material used in the heat capacitor.
  • the heat capacitor is flexible and/or not rigid.
  • At least one of magnetic and electrical forces are used to maintain a volume or pressure within the heat capacitor, alternatively or additionally to at least one of a sponge, a pressurized gas and a counterpart material.
  • the performance of the heat capacitor is adjusted by adding materials into the heat capacitor.
  • the performance that is adjusted includes at least one of critical temperature, chemical equilibrium and number of nucleation sites.
  • the heat capacitor includes at least one of a part of a satellite, a phase change material, a chemical reaction, and a material with high heat capacity.
  • the heat capacitor is configured with a cold finger to prevent super cooling of the capacitor.
  • the heat removal mechanism is the solar panel.
  • the system is configured to conduct extreme radiation bursts, such as solar flares and laser attacks, to at least one of the heat capacitor and heat removal mechanism from the solar panel.
  • the controller is configured to control conducting, storing and discharging in a cycle.
  • the cycle is no more than 2 hours long.
  • the cycle is based on day and night solar exposure on the solar panel.
  • a method of enhancing the efficiency of a radiator comprising curving the surface of the radiator.
  • the method further comprises adjusting the power of the radiator's radiation as a function of the direction of the radiation.
  • the radiator radiates with no or low power towards directions which should not be heated and where the radiator radiates with high power towards directions where heating is acceptable.
  • a method for using a system for enhancing efficiency of a solar panel comprising: at least one of storing thermal energy in and discharging thermal energy from a heat capacitor, the thermal energy conducted to the capacitor from the solar panel; and, reducing the overall thermal energy in the system by delivering the thermal energy to a heat removal mechanism and discharging the thermal energy.
  • the method further comprises shunting thermal energy throughout the system using a heat conductance mechanism.
  • the method further comprises at least moderating the temperature variation of the solar panel in order to reduce solar panel degradation.
  • a system for enhancing efficiency of a solar panel comprising: a heat capacitor configured to store and discharge solar panel thermal energy conducted to and from the capacitor; and, a heat removal mechanism configured to reduce the overall thermal energy in the system by discharging thermal energy delivered to the heat removal mechanism, where at least one of the heat capacitor and heat removal mechanism are configured to conduct, store, and discharge thermal energy in a cycle.
  • the cycle is no more than 2 hours long.
  • all technical and/or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains.
  • methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the invention, exemplary methods and/or materials are described below. In case of conflict, the patent specification, including definitions, will control.
  • the materials, methods, and examples are illustrative only and are not intended to be necessarily limiting.
  • Implementation of the method and/or system of embodiments of the invention can involve performing or completing selected tasks manually, automatically, or a combination thereof. Moreover, according to actual instrumentation and equipment of embodiments of the method and/or system of the invention, several selected tasks could be implemented by hardware, by software or by firmware or by a combination thereof using an operating system.
  • a data processor/controller such as a computing platform for executing a plurality of instructions.
  • the data processor includes a volatile memory for storing instructions and/or data and/or a non-volatile storage, for example, a magnetic hard-disk and/or removable media, for storing instructions and/or data.
  • a network connection is provided as well.
  • a display and/or a user input device such as a keyboard or mouse are optionally provided as well.
  • FIG. 1 is a block diagram of a system for enhancing solar panel efficiency, in accordance with an exemplary embodiment of the invention
  • FIG. 2 is a partial perspective view of a flat system for enhancing solar panel efficiency, in accordance with an exemplary embodiment of the invention
  • FIG. 3 is a partial perspective view of a coin system for enhancing solar panel efficiency, in accordance with an exemplary embodiment of the invention
  • FIG. 4A is a partial top view of a spider system for enhancing solar panel efficiency, in accordance with an exemplary embodiment of the invention.
  • FIG. 4B is a partial side view of a spider system for enhancing solar panel efficiency, in accordance with an exemplary embodiment of the invention.
  • FIG. 5 is a graphic depiction showing a way to segment a solar panel to calculate heat conduction, in accordance with an exemplary embodiment of the invention
  • FIG. 6 is a diagram showing a near worst case scenario for calculating heat conductance in a capacitor of a flat system, in accordance with an exemplary embodiment of the invention.
  • FIG. 7 is a diagram showing a near worst case scenario for calculating heat conductance in a capacitor of a coin system, in accordance with an exemplary embodiment of the invention.
  • FIG. 8 is a diagram showing a "Cold Finger” technique for avoiding supercooling of a capacitor, in accordance with an exemplary embodiment of the invention.
  • FIG. 9A is a perspective view of a coin in the coin system configured to accommodate capacitor volumetric change, in accordance with an exemplary embodiment of the invention.
  • FIG. 9B is a top view of the coin of FIG. 9A, in accordance with an exemplary embodiment of the invention.
  • FIGs. 10A and 10B are schematic diagrams showing systems for increasing the salinity of a PCM container, in accordance with exemplary embodiments of the invention.
  • FIG. 11 is a partial schematic view of a modified radiator, in accordance with an exemplary embodiment of the invention.
  • FIG. 12 schematically shows a system with a switch and component configuration for controlling the temperature of at least one of a solar panel, a radiator and a PCM, in accordance with an exemplary embodiment of the invention
  • FIG. 13 schematically shows a system with a switch and component configuration with an added heat engine mechanism, in accordance with an exemplary embodiment of the invention
  • FIG. 14 shows a system with a switch and component configuration configured for transferring energy from the PCM to the radiator and/or solar panel, including an optional cooling mechanism, in accordance with an exemplary embodiment of the invention
  • FIG. 15 shows a schematic of a solar panel configured with a heat conductance mechanism to shunt heat away from the solar panel, in accordance with an exemplary embodiment of the invention
  • FIG. 16 shows a schematic of the basic operation of a system for enhancing solar panel efficiency during the day, in accordance with an exemplary embodiment of the invention
  • FIG. 17 shows a schematic of the basic operation of a system for enhancing solar panel efficiency during the night, in accordance with an exemplary embodiment of the invention.
  • FIG. 18 shows a schematic of the basic operation of a system for enhancing solar panel efficiency using a heat engine to generate electricity, in accordance with an exemplary embodiment of the invention.
  • the present invention in some embodiments thereof, relates to a system for enhancing solar panel efficiency and, more particularly, but not exclusively, to a system to be used in a space environment.
  • systems and methods to increase the efficiency of a satellite's solar panel system by decreasing its average operating temperature are provided.
  • the system absorbs some of the heat from the solar panel during the day, and emits it during the night, to even out the temperature of the solar panel over the course of a hot/cold and/or more exposure/less exposure cycle, for example during the day and night.
  • the system operates on a faster cycle, for example a no more than a two hour cycle.
  • Increased solar panel efficiency allows more power to be generated for the same size panel.
  • enhancement of solar panel efficiency allows smaller panels to be used to achieve the same amount of power generation.
  • Smaller solar panel surface area results in lower drag on the satellite.
  • a lower drag on the satellite allows for placement of the satellite in a lower orbit or for placement of the satellite in the original (before these innovations are incorporated into the design) orbit for a longer period of time and/or with less fuel consumed to keep it there.
  • lowering the drag increases the lifetime of the satellite.
  • smaller solar panels can reduce satellite mass and moment of inertia, improving satellite performance during the launch phase, in attitude control, in kinematic lifetime, deployment, reduces the solar panel' s vibrations magnitude and others.
  • Increased solar panel efficiency also translates to wholesale satellite redesign where power consuming systems are concerned, for example electrical propulsion (which also improves either the orbit allowed to orbit or the lifetime in given orbit, acting synergistically with the other orbit/lifetime considerations described herein) and sensors.
  • electrical propulsion which also improves either the orbit allowed to orbit or the lifetime in given orbit, acting synergistically with the other orbit/lifetime considerations described herein
  • the same system can be used to lessen the impact of extreme radiation events or bursts, such as solar flares or laser attacks, in some embodiments of the invention.
  • system 100 contains some or all of the following three main components, as shown in FIG. 1:
  • the heat conductance mechanism is used to conduct thermal energy, from a solar panel absorbing it, to a heat capacity/removal mechanism (described in more detail below).
  • the heat conductance mechanism 102 transports thermal energy at a rate sufficient to maintain an equilibrium temperature (relatively small difference of temperature between the solar panel and the capacitor) of the solar panel. Table 1, below lists exemplary values for various relevant heat conductance parameters:
  • Heat capacitor 104 * A typical solar panel is assembled from a plurality of layers of materials, often different materials with different thermal conductance characteristics, the value used is an approximate average value, and for simplicity, the panel is calculated as behaving as a single uniform layer. II) Heat capacitor 104:
  • the heat capacitor 104 is used to store thermal energy accumulated during daylight, if any.
  • the heat capacitor 104 is constructed of a material with a high heat capacity for a mass and volume unit, and/or high latent heat for a heat transfer that the material is undergoing, within the relevant temperatures, in an embodiment of the invention.
  • an endothermic/exothermic chemical reaction is used as a heat capacitor.
  • an existing part of the satellite itself is used as the heat capacitor.
  • One option is to use the satellite fuel tank, which already contains a large amount of material which can capacitate heat.
  • Another option is to conduct to the satellite mechanical infrastructure, which is massive and has a high heat capacity.
  • parts of the satellite that are used for heat capacitance are pre-configured during satellite manufacture to enhance their heat capacitance.
  • the heat removal and/or prevention component 106 is used to decrease the amount of absorbed heat and dispose the heat that was absorbed.
  • the system 100 can decrease the amount of absorbed heat by at least one of the following methods: spectral filtering, varying system geometry and/or varying reflection coefficient.
  • heat removal is achieved by at least one of the following methods: black body radiation of the solar panel and radiator and/or conducting the heat to other mechanisms. These methods are optionally optimized by varying the radiating body geometry, emissivity and temperature.
  • other design considerations include (values listed are examples only and are variable depending on mission objectives and/or operating conditions): minimizing system mass (1-12 kg per area unit of one meter square, or less or more), maximizing reliability (15 years or longer life), enhancing fail safes and/or eliminating single points of failure, minimizing degradation (10% or less EOL degradation as compared to BOL performance, both of the solar panel and the heat capacitor, conductance, removal, prevention mechanisms), maximizing heat conductance to reduce temperature variances in the system (variances no greater than 10°C), launch tolerance and/or survivability (able to withstand acceleration up to 60m/s and ⁇ 1 g sinusoidal frequency accelerations for longitudinal and lateral frequencies between 5 - 100 Hz), and/or resistance to effects on the system due to external temperature factors (temperatures in storage, at the launch site, in the launch vehicle, in space, etc.).
  • Exemplary System Configurations include (values listed are examples only and are variable depending on mission objectives and/or operating conditions): minimizing system mass (1-12 kg per area unit of one
  • the system 100 there are many different embodiments of the system 100 which, while configured differently, function to enhance the efficiency of solar panels in operation in space.
  • the three different main configurations described herein include the flat system, shown in FIG. 2, the coin system, shown in FIG. 3, and the spider system, shown in FIGS. 4A-4B.
  • at least one of a group of phase change materials (PCM) is used as a construction material of the heat conductance mechanism 102 and/or the heat capacitor 104 components in the system 100.
  • the heat removal and/or prevention component 106 embodiments described herein are usable with any of the flat, coin and/or spider systems.
  • FIG. 2 is a partial perspective view of a flat system 200 for enhancing solar panel efficiency, in accordance with an exemplary embodiment of the invention.
  • the flat system 200 is configured with a PCM panel 202 which abuts an inner surface of a solar panel 204 such that the PCM panel 202 is in thermal communication with the solar panel 204.
  • heat which accumulates on the solar panel 204 during the day from solar radiation 206 is transferred to the PCM panel 202, reducing the operating temperature of the solar panel 204 and raising the temperature of the PCM panel 202.
  • Table 3 includes exemplary physical characteristics of the system 200:
  • the container (PCM panel) is only one sided since in some configurations the 1mm or greater thickness of an attached polyimide PCB (or other material composing the control panel PCB) is at least sufficiently rigid to function as the other container side.
  • the system is configured to disable water from directly touching the panel without needing additional adaptation to hold a thick layer for rigidity purposes.
  • FIG. 3 is a partial perspective view of a coin system 300 for enhancing solar panel efficiency, in accordance with an exemplary embodiment of the invention.
  • a plurality of PCM containers 302 are used as contact points to the solar panel 304 (in the heat conductance 102 role) and/or for heat storage (in the heat capacitor 104 role).
  • heat which accumulates on the solar panel 304 during the day from solar radiation 306 is transferred to the PCM containers 302, reducing the operating temperature of the solar panel 304 and raising the temperature of the PCM containers 302.
  • each PCM container 302 is cylindrically shaped, like a coin, hence the name. It should be understood that other container 302 shapes could be used, for example cubes, rectangular prisms, and the like. Alternatively, additionally and/or optionally, not all of the PCM containers 302 are the same shape and/or size. In an embodiment of the invention, not all of the PCM containers 302 are evenly spaced apart from each other. Table 4, below, includes exemplary physical characteristics of the system 300:
  • FIG. 4A is a partial top view of a spider system 400 for enhancing solar panel efficiency, in accordance with an exemplary embodiment of the invention.
  • one or more PCM containers 402 (“spiders") are used for thermal storage (in the heat capacitor 104 role) and/or for at least some of the heat conductance through direct thermal communication from the solar panel 404 in the system 400.
  • each of the PCM containers 402 in the spider system 400 are larger than the PCM containers 302, in an embodiment of the invention.
  • the heat conductance mechanism 102 function is enhanced by the use of heat pipes or tubes 406 (the "spider legs") which spread out from the PCM containers 402, abutting the solar panel 404, and siphon thermal energy from the solar panel 404 surface and shunt the thermal energy to the PCM containers 402.
  • the PCM containers 402 are cubic, but as with other embodiments they can take any and/or multiple shapes depending on the intended use and/or mission objectives and/or operating conditions. Table 5, below, includes exemplary physical characteristics of the system 400:
  • FIG. 4B is a partial side view of the spider system 400 for enhancing solar panel efficiency, in accordance with an exemplary embodiment of the invention, showing the PCM container 402 abutting the solar panel 404.
  • 0.1mm of aluminum is optionally used as one side of the container, taking the solar panel itself as the other face of it.
  • 0.4mm of titanium could be used for each of the two faces of a flat container.
  • Other materials that can be used for the container are carbon based materials such as XN-80 and also metals and alloys of titanium, aluminum, nickel cobalt and magnesium.
  • 2 Weight may vary if a different material is used for the radiator, for example a carbon-carbon radiator. supports enhanced rigidity, needing less or no PCB.
  • the manufacturing method may include CNC, 3-D printing, metal rolling, welding, and/or gluing, as examples.
  • Methods for attaching the PCM to the container optionally include welding after filling, gluing, and/or use of a friction fitting cork or a screwing based cork.
  • the height in the direction normal to the panel can be as low as a few millimeters or can be as high as several centimeters. Due to the increase in the solar panel efficiency, the total surface of the panel can optionally decrease causing less drag and providing for a simpler stowing and deployment of the solar panel.
  • the heat conductance mechanism 102 is configured to shunt sufficient thermal energy from heat generating structures to heat storing and/or dissipating structures to maintain a "small" temperature difference (no greater than 10°K) within and/or between parts of the system.
  • focus is placed on temperature difference across the solar panel, the temperature difference between the solar panel and the heat capacitor and/or the temperature differences inside of the capacitor or capacitors, if there is more than one.
  • the heat conductance mechanism 102 is a function of the number and/or surface area of the contact points between the PCM containers 302, 402 and/or the heat pipes 406 (in the case of the spider system 400) and the solar panel.
  • FIG. 5 is a graphic depiction of a way to segment a solar panel 502 to calculate heat conduction and/or to determine how many PCM containers 302, 402 and/or how much heat piping 406 should be used, in accordance with an exemplary embodiment of the invention.
  • the solar panel 502 surface is divided into segments 504, where each segment 504 corresponds to a PCM container 506 in thermal communication with the segment 504.
  • each PCM container 302, 402 wholly, or almost completely, absorbs the thermal energy received from solar radiation 508 on its corresponding segment 504.
  • a second method is by using heat pipes which are located adjacent to the solar panel, such as in the spider system, to transfer thermal energy from the solar panel to at least one PCM container. Additionally and/or optionally, the PCM container is also located adjacent to the solar panel such that thermal transfer can occur directly between the PCM container and the solar panel.
  • heat pipes are used which weigh about 2gr for 10cm of length. In some embodiments of the invention, it has been determined that around 200 contact points are used for every lm of solar panel, where each contact
  • solid state thermal conductivity is used to transmit thermal energy from remote areas of the solar panel to the PCM container instead of heat pipes.
  • a conductive material such as graphite, is used to transmit sufficient thermal energy to the PCM container per second according to the equation:
  • FIG. 15 shows a schematic 1500 of a solar panel 1502 configured with a heat conductance mechanism 1504 to shunt heat away 1506 from the solar panel 1502, regardless of where or how evenly thermal energy is accumulated by the solar panel 1502.
  • the heat conductance mechanism 1504 comprises wires and/or heat pipes.
  • a design consideration is that heat should transfer into the capacitor at a rate at least equal to the rate that heat is accumulated by the solar panel segment immediately adjacent to the heat capacitor and/or which is delivered to the capacitor by heat pipes, in an embodiment of the invention. It should be understood that by matching the rate of heat transfer into the capacitor to the rate of heat generation and/or transport to the capacitor, the temperature differential between the different parts of the system can be narrowly constrained. In order to design for proper heat absorption by the capacitor, various physical and/or performance characteristics of the capacitor are tweaked, in some embodiments of the invention. In an embodiment of the invention, physical characteristics of the PCM container agree withM pcm , which determines the PCM total volume.
  • the heat transfer rate through the panel is the total amount of heat that must be transferred per unit time by the PCM containers and/or the heat pipes, and using the following equation: ⁇ Aunlt)
  • heat conductance within the capacitor is calculated differently to meet the desired performance characteristics, in some exemplary embodiments of the invention.
  • FIG. 6 is a diagram showing this near worst case scenario for calculating heat conductance in a capacitor 600 of the flat system, in accordance with an exemplary embodiment of the invention. This scenario can be represented with the following equation:
  • dQ/dt is used because it is assumed the heat is transferred to the radiator not through the PCM, but via other conducting mechanisms, such as heat pipes or the PCM container itself. In addition to the PCM already being nearly all liquid, it is assumed that heat conduction is achieved through only one side of the panel, as heat flow of the container surface may not be sufficient. h req is the required height of the adjacent PCM in order to have sufficient thermal conductance.
  • the upper bound for h req is calculated to be about 0.004m.
  • the PCM container contains a honeycomb shaped conductor, the PCM container is partitioned, it contains heat pipe conductive tubes, and/or the PCM is enhanced (e.g. increased conductance) in any other way.
  • the coin system where the coins cover a negligible portion of the panel back surface area, it only needs to conduct into it the accumulated heat, dQ/dt.
  • the heat radiated by the radiator also needs to be conducted, dQ t0 _ the ⁇ ack /dt_ ⁇ 0 meet this objective, the PCM's conductivity is enhanced in the manner described in the "Flat" system.
  • both sides of the PCM container are approximately the same temperature:
  • FIG. 7 is a diagram showing a near worst case scenario for calculating heat conductance in a capacitor 700 of a coin system, in accordance with an exemplary embodiment of the invention, where most of the PCM is in a liquid state.
  • heat transfer occurs on both sides of the coin, which gives a factor of ⁇ on the length of the capacitor along which the heat is conducted and also a factor- 2 on the heat transfer since each of the sides conducts the same amount of heat.
  • Heat capacitor 104 (or PCM) design considerations range from PCM container geometry and heat storage capacity, to problems with PCM like super cooling, degradation and material stability. Additional considerations include material properties that vary from PCM to PCM, and which in some cases are adaptable, and alternative capacitors which are available and/or are usable in the system 100. Each of these considerations are discussed in turn, below, although it should be understood that specific embodiments which are described are by way of example only.
  • the PCM container geometry is designed to sustain a preselected level of pressure within the container vessel to provide better control of the solid-liquid phase change.
  • the PCM container internal pressure is adjusted, for example by injecting gas therein to increase pressure.
  • a gas like helium or argon is used.
  • the heat capacitor 104 is configured to avoid super cooling.
  • the PCM container 802 is imbued with a small defect 804 in a method called the "Cold Finger” technique.
  • FIG. 8 is a diagram showing a "Cold Finger” technique for avoiding super cooling of the heat capacitor, in accordance with an exemplary embodiment of the invention.
  • the PCM near the defect 804 (the "Finger) will be cooled down faster than the rest of the PCM, thereby during periods of low temperature causing some solidification of the PCM around the "Cold Finger" which acts to insulate the rest of the PCM from the super cooling.
  • another method for avoiding super cooling of the PCM includes adding nucleators or impurities into the PCM.
  • additional PCM mass is added to always have some of the PCM in a solid state, to avoid super cooling of the PCM.
  • phase separation due to gravity is irrelevant due to the lack of gravity in space. However, phase separation may occur if a material is used which melts incongruently. For example, solidification of a water-salt solution may cause pure ice creation on the PCM container's surface and the remaining water-salt solution would be left with a higher salt concentration in the center of the PCM container. In an embodiment of the invention, water-salt eutectic type PCMs are used and super cooling is avoided. Another problem with some PCMs is volumetric change. Some materials such as eutectic water-salt have a higher density as liquids in comparison to when they are solid. This causes a volumetric change of 5%-10%, which can cause mechanical instability.
  • the PCM container size is fitted to the low density state of the PCM phase to allow for volumetric change. That is, the PCM container is made about 10-15% larger than the high density state of the PCM, and the empty space is pressurized, for example being filled with gas, in order to maintain substantially constant pressure levels within the PCM container.
  • the PCM 902 is encased within a sponge 904, such as shown in FIG. 9A which is a perspective view of a coin 906 in the coin system 900 configured to accommodate capacitor volumetric change, in accordance with an exemplary embodiment of the invention and, in FIG. 9B which is a top view of the coin 906 of FIG. 9A.
  • the sponge 904 is embedded in a conductive material 908 to avoid thermal isolation by the sponge. Additionally, alternatively and/or optionally, elastic materials are used.
  • a material is used as a counterpart to the PCM which exhibits volume change characteristics inverse to those of the PCM at similar temperatures in order to maintain approximately a constant volume.
  • the material used can act as a counterpart in at least two ways: a phase change with a reverse volumetric change or a chemical reaction caused by Le Chatelier' s effect.
  • ammonia can be placed in the PCM's container so when the water is in liquid phase and is occupying a lower percentage of the container volume, the ammonia will be mostly gas, and when the water freezes it will pressurize the ammonia, there by rendering much of the ammonia into a liquid state, keeping the total volume of the two materials approximately the same without a significant increase in pressure inside the container.
  • the heat capacitor is flexible and/or not rigid.
  • a flexible container is potentially lighter than a more rigid one, where weight is always an important consideration in spacecraft design, deployment and performance.
  • At least one of magnetic and electrical forces are used to maintain a volume or pressure within the heat capacitor, alternatively or additionally to at least one of a sponge, a pressurized gas and a counterpart material.
  • eutectic water-salt solutions are used as the PCM.
  • Some PCMs are corrosive, for example water- salt eutectic solutions are corrosive to certain metals.
  • the PCM container is constructed of a non-corrosive material and/or is coated to prevent corrosion and/or corrosion inhibitors are used.
  • the PCM container is constructed of a relatively light material which can withstand the rigors of launch and can also withstand the pressure changes and/or maintenance of pressure within the container to control
  • the PCM container is constructed of titanium, aluminum, stainless steel and/or is carbon-fiber based.
  • PCM that is, using the heat capacitor to capacitate some of the heat as PCM and the rest of the heat in regular specific heat of both the capacitor, container and solar panel
  • the liquid-gas phase change is performed using ammonia, which has a latent heat of 1369 KJ/Kg and it condensates at the relevant temperatures within reasonable container pressures.
  • the ammonia container can also include a similar amount of helium, in order to minimize the relative pressure change in the container while the ammonia changes its phase.
  • the mass of the PCM will be around lkg/m A 2.
  • an enhanced PCM which has a higher thermal conductance over its non-enhanced variant is used.
  • the PCM has conductive material inside it.
  • the heat capacitor container can be integrated into the solar panel's PCB which supports the photovoltaic cells, and thereby, it could be treated as a single component.
  • thermal energy or heat has been accumulated in the heat capacitor 104 of the system 100, it is released, in an embodiment of the invention. In some embodiments of the invention, some thermal energy is prevented from entering into the system 100 in the first place. Exemplary methods and apparatuses for heat removal and/or prevention are described in this section.
  • the primary heat removal mechanism 106 is the solar panel itself, since during nighttime at least some of the stored thermal energy will flow from the capacitor 104 to the solar panel through the same heat conductance mechanism 102 used earlier for cooling (i.e. for transporting the thermal energy from the panel to the capacitor).
  • a first radiator is placed on the back of the solar panel.
  • the radiator has a different emissivity coefficient than the solar panel. Explicitly the emissivity coefficient can increase by about 10%-20%.
  • different emissivity coefficients for different wavelength may be chosen, such that the radiation absorbed to the radiator directly is reduced.
  • the radiator is provided with an increased surface area, so that it will emit more radiation according to the Stefan- Boltzmann law.
  • the first, most compact way to do it in an embodiment of the invention, is to curve the radiator such that the additional surface will cause no additional volume.
  • the solar panels suffer from thermal radiation emitted from the satellite's own body, self -radiation.
  • at least a portion of the satellite's body is covered with a second, modified radiator (the "first" radiator being described with respect to the solar panel above).
  • the modified radiator comprises a curved and/or angled radiator, where the curve is designed such that thermal radiation which normally would have been radiated towards the solar panels is radiated away from them.
  • the modified radiator is comprised of a plurality of surfaces which may vary in height, size, material and/or angle of incidence to the satellite body, but are optionally arranged in at least a vaguely periodic manner.
  • FIG. 11 is a partial schematic view of a modified radiator 1100, in accordance with an exemplary embodiment of the invention.
  • the surface of the radiator is increased by deploying additional surfaces, with different angles to the solar panel.
  • a mechanism to improve radiation is placed at the front of the solar panel, for example a silica glass in a shape that enhances radiation which is radiated from the solar panel.
  • spectral filtering is used to control system thermal energy absorption and/or radiation. It should be understood that certain solar panels have different efficiencies for different wavelengths of light. For example, in the infrared portion of the spectrum, and above, there is virtually no conversion of those waves into energy. Thus, only a portion of the incoming spectrum of light will actually convey heat or thermal energy into the system (about 1200-2250nm). In some embodiments of the invention, at least a part of the spectrum which does impart heat to the system is filtered out, while optionally still allowing the system to radiate or remove heat. In some embodiments of the invention, notch filters are used to perform spectral filtering, blocking a thermal power of about 250 W/m when directly facing the sun.
  • FIGS. 10A and 10B are schematic diagrams 1000, 1050 showing systems for increasing the salinity of a PCM container, in accordance with exemplary embodiments of the invention.
  • material or materials can be added to or taken out of the heat capacitor.
  • the PCM is a solution of water and salt
  • the salinity of the PCM can be increased by adding salt to the PCM container.
  • a salt container 1002 is operatively connected to the PCM container 1004 such that when a valve 1006 is opened, the salinity of the PCM container is increased by placing it in fluid communication with the salt container.
  • a plurality of salt containers are used, each containing a known amount and the number of which are used can be used to control the amount of salt which is added to the PCM container.
  • the valve is controlled to allow only a portion of a salt container into the PCM container.
  • the salt container is pressurized.
  • salt is added to the PCM container using pellets or pills which contain a known amount of salt, to allow for control of the addition of salt to the PCM container.
  • the pellet cover is soluble in water.
  • the pellet cover is insoluble in water and instead opens upon command by the system operator.
  • the salt container 1052 resides in the PCM container 1054, is insoluble in water, and is remotely opened by the system operator to allow its contents 1056 into the PCM container.
  • Critical temperature of the PCM can also be adjusted, in an embodiment of the invention, by changing the pressure within the PCM container.
  • additional matter and/or changing the container volume are performed to alter the pressure with the objective of altering the critical temperature of the PCM.
  • changes in pressure and/or volume of the PCM container are used to control critical temperature.
  • a pressurizing mechanism including a canister of pressurized gas (or low pressure vacuum to reduce PCM container pressure) is placed in fluid communication with the PCM container, wherein an optionally and/or selectively one-way valve is opened between them to increase the pressure of the PCM container while substantially preventing pressure loss in the PCM container itself while the valve is open (except in embodiments where pressure is being reduced in the PCM container and/or where a vacuum canister is being used).
  • a container with a pressurized gas when the PCM liquid state is denser than its solid state, the PCM in liquid state may not touch the container surfaces creating a gas layer which acts as thermal isolator.
  • the container's inner surface is configured with structures which increase the capillarity forces of the container's inner surface, which in turn keeps the liquid in touch with it, thus keeping a good heat conductance between the PCM and the container.
  • the volume of the PCM container is changed, for example using a piston attached to moveable walls of the PCM container to enhance or reduce the overall total volume of the PCM container.
  • conductance between the solar panel and the PCM is controlled (i.e. can be switched on and off). It can be useful, in some embodiments of the invention, to disable the conduction between the solar panel and the PCM, for example where the battery is nearly full and the highest possible efficiency of the solar panel is not needed.
  • the switch is configured as a mechanical system which attaches and/or detaches two conductors, for example where there are two ends of a heat conductor, which leads to two different mechanisms and where the switch is between them.
  • the conductance of a conductor such as a heat pipe, is enabled and/or disabled, for example in the instance of a heat pipe stopping the flow of liquid inside the pipe to disable its conductance.
  • FIG. 12 schematically shows a system 1200 with a switch 1208 and component configuration for controlling the temperature of at least one of a solar panel 1202, a radiator 1204 and the PCM 1206, in accordance with an exemplary embodiment of the invention.
  • FIG. 13 schematically shows a system 1300 with a switch and component configuration with an added heat engine mechanism 1302, in accordance with an exemplary embodiment of the invention. The arrows represent the direction and path of the heat flow from the solar panel 1304 being radiated by solar energy.
  • the switches 1306 in the system 1300 are used to control heating of the solar panel 1304, the radiator 1308, the heat engine 1302 and/or the PCM 1310, depending on which switches 1306 are open or closed.
  • FIG. 12 schematically shows a system 1200 with a switch 1208 and component configuration for controlling the temperature of at least one of a solar panel 1202, a radiator 1204 and the PCM 1206, in accordance with an exemplary embodiment of the invention.
  • FIG. 13 schematically shows a system 1300 with a switch and
  • FIG. 13 shows an embodiment where the radiation from the solar panel 1304 is used to heat the PCM 1310. It should be understood that the switches could be arranged differently, for example having a switch between the radiator 1308 and the heat engine 1302. Referring back to FIG. 13, in some embodiments of the invention, as heat is passed from the radiator 1308 to the PCM 1310, electricity is generated by the heat engine 1302.
  • FIG. 18 shows a schematic of the basic operation of a system for enhancing solar panel efficiency using a heat engine to generate electricity, in accordance with an exemplary embodiment of the invention.
  • the solar panel is provided with a mechanism which obscures at least some of the panel, on demand.
  • An advantage would be that during low power demand times part or all of the solar panel can be effectively disabled, lowering the electrical power generated and also lowering the heat absorbed by the solar panels from the sun radiation (without dependency on the attitude the solar panels).
  • the temporarily and/or partially disabled solar panel is replaced by a radiator which absorbs less radiation from the sun and radiates more blackbody heat resulting in less heat accumulated on the PCM, and enabling a lower temperature solar panel. This embodiment will result in higher efficiency when needed and when the obscuration is off.
  • the radiator replacement is a white body in certain wavelengths, for example corresponding to solar radiation and radiated blackbody heat.
  • Another technique for avoiding solar radiation by the solar panels is by adjusting the satellite and/or solar panel attitude, for example so instead of facing the sun, the solar panels and/or the satellite are perpendicular to the sun.
  • the system is configured to utilize temperature differences between system components to generate electricity. For example, when different components of the system are at different temperatures, they can be used as heat sinks.
  • a free piston Stirling engine and/or a thermoelectric generator is used to generate energy from the temperature differential.
  • these devices are used in combination with the switch described above.
  • FIG. 14 shows a system 1400 with a switch 1402 and component configuration configured for transferring energy from the PCM 1404 to the radiator 1406 and/or solar panel 1408, including an optional cooling mechanism 1410, in accordance with an exemplary embodiment of the invention.
  • the cooling mechanism is the same component as the heat engine 1302, converting electricity to heat difference or vice versa.
  • a thermoelectric generator/cooler or a Stirling engine could be used.
  • the thermal energy may be transferred directly to the radiator and not to the
  • an angular filter is used to reflect radiation from a particular direction, for example the earth.
  • a spectral filter which has an emissivity coefficient which is different for earth radiation and panel thermal radiation.
  • the system is provided with a controller, or some form of control loop (active, reactive or passive), used to adjust components, such as the heat conductance mechanism, the heat capacitor, a heat engine and the heat removal system, and/or operational characteristics of the system, such as thermal conductivity, thermal cycle, filtering, goal temperature differential between components, etc.
  • a controller or some form of control loop (active, reactive or passive) used to adjust components, such as the heat conductance mechanism, the heat capacitor, a heat engine and the heat removal system, and/or operational characteristics of the system, such as thermal conductivity, thermal cycle, filtering, goal temperature differential between components, etc.
  • the controller is a physical component dedicated to control the solar panel, its condition and/or the mechanisms influencing it, or software that runs on the satellite's computer which does the same, or a combination of both.
  • the controller has an autonomous logic, and/or it receives information about the solar panel's condition and/or other information such as the battery and/or other electrical supply components, the satellite's attitude, the satellite's orbit detail, the satellite's mission requirements and/or command file, the state of the PCM and/or the state of the different related mechanisms (for example, the heat removal mechanisms).
  • the autonomous logic will process the information and/or send commands to components such as the obscuration mechanism, the switch and other similar mechanisms and/or to send a status to the satellite's main computer.
  • the computer optionally uses this information for planning ahead its mission execution, estimate its power budget and/or stored heat budget.
  • the controller operates its heat removal mechanisms and/or sends telemetry to the ground station.
  • the controller operations and its influence over the satellite's computer can also affect the whole satellite's attitude or the solar panel's attitude (in satellites where the solar panel has its own attitude control mechanisms).
  • the satellite will maneuver so that solar panel will be in an angle to the sun so that the radiation on solar panel is sufficient for the satellite's current power needs and not beyond that. This is in order to avoid an unnecessary heat absorption in the system.
  • Another consideration in this maneuver is to optimize the angle such that also the radiation from earth is kept to a minimum. Therefore, the total heat absorbed from both the sun and the earth will be the minimal amount possible, while still supplying the necessary amount of energy to the satellite.
  • the controller can also act based on a known or a preprogrammed plan or mission profile. For example, if the battery is nearly full, and the mission dictates that in the near future the satellite would be in an attitude such that the solar panel would face the sun in an angle that would produce more energy than that is required to operate, system optionally selects one of the advantageous angles mentioned herein so that the battery would discharge at least a little. This is, knowing that the future attitude would compensate for the missing electrical energy, resulting in less heat accumulated by the system.
  • the controller can maneuver the satellite during the night to face the hot side towards the earth's radiation in order to maintain a temperature difference.
  • the angle chosen is such that the panels receive the radiation necessary/desired while the earth radiation comes from an angle that is blocked by the filter.
  • active angular filters are used which can vary the angle in which they filter the undesired radiation. In that case, the controller would be in charge of the filters' state.
  • the controller is optionally in operative communication with at least one sensor to monitor different aspects and/or different components of the system and/or satellite. It can also have mission critical self-survival mechanisms, such as pyrotechnics to separate dysfunctional units where needed.
  • the system 100 is mounted to the panel using screws, an adhesive and/or is embedded within the solar panel itself.
  • the spider system is optionally, separated into two different mounting modules, the heat conductance mechanism, which is adjacent to the solar panel, and the heat capacitor which could theoretically be located remotely (perhaps even within the satellite body), or at least not in direct contact with the solar panel.
  • the PCM is embedded into the solar panel material, for example within the PCB.
  • the system 100 can be expected to be subjected to significant physical stresses during the launch. However, this is not regarded as a substantial problem since more fragile systems such as the optics or the solar panel itself are going to undergo similar stresses and will be expected to survive. Nevertheless, in some embodiments of the invention, structural rigidity is maintained, either by using a low mass support structure such as metal or carbon and/or by attaching it to the solar panel and using the panel to provide rigidity to the system 100 assembly.
  • a low mass support structure such as metal or carbon
  • the solar panel gains rigidity from the system (e.g. from the spider legs), allowing for a more lightweight and/or less expensive design for the solar panel.
  • the PCM is separated into a few different partitions to help avoid accumulated pressures and/or to change the eigenfrequencies.
  • the partition is within the PCM container.
  • each rigid part of the solar panel has its own system 100, in order to make deployment as simple as possible.
  • the system 100 starts with a cold PCM and includes a mechanism to initialize PCM contact with the solar panel immediately after deployment, so that the solar panel can operate at a high efficiency immediately.
  • the system is configured to behave as a rigid body within a good approximation and without vibration due to sloshing and/or turbulence, since the satellite may need to maneuver quickly and accurately.
  • the PCM is configured in such a way that sloshing and/or turbulence effects are limited. For example, small partitions are provided to the PCM container. When using many small containers instead of a one large container, the slosh and turbulence effects will be smaller: The smaller distance between the fluid inside the container and the container walls would reduce the possible velocity and position difference of the materials inside the container.
  • a sufficient number of partitions are used in the PCM container so that surface tension effects help to attach the PCM to the partitions, substantially reducing the sloshing.
  • a PCM soaked sponge is used to suppress sloshing. The capillary forces between the sponge and PCM inside it will suppress the turbulence and the slosh as the sponge will behave more like a solid. Also, when using small enough container, capillarity forces can also help to hold the fluid in a constant position.
  • additives are provided to the PCM to increase its viscosity.
  • compositions, method or structure may include additional ingredients, steps and/or parts, but only if the additional ingredients, steps and/or parts do not materially alter the basic and novel characteristics of the claimed composition, method or structure.
  • a compound or “at least one compound” may include a plurality of compounds, including mixtures thereof.
  • various embodiments of this invention may be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the invention. Accordingly, the description of a range should be considered to have specifically disclosed all the possible subranges as well as individual numerical values within that range.

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Abstract

L'invention concerne un système permettant d'augmenter l'efficacité d'un panneau solaire, comprenant : un condensateur de chaleur conçu pour stocker et décharger l'énergie thermique d'un panneau solaire dirigée en direction du condensateur et à partir de ce dernier; et un mécanisme d'évacuation de la chaleur conçu de manière à réduire l'énergie thermique globale dans le système en évacuant l'énergie thermique fournie au mécanisme d'évacuation de la chaleur.
PCT/IL2015/051214 2014-12-14 2015-12-14 Système permettant d'améliorer l'efficacité d'un panneau solaire et son procédé d'utilisation WO2016098107A2 (fr)

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