WO2009101586A2 - Collecteur et système d'énergie solaire - Google Patents

Collecteur et système d'énergie solaire Download PDF

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Publication number
WO2009101586A2
WO2009101586A2 PCT/IB2009/050561 IB2009050561W WO2009101586A2 WO 2009101586 A2 WO2009101586 A2 WO 2009101586A2 IB 2009050561 W IB2009050561 W IB 2009050561W WO 2009101586 A2 WO2009101586 A2 WO 2009101586A2
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WO
WIPO (PCT)
Prior art keywords
energy
solar energy
temperature
fluid
heat
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Application number
PCT/IB2009/050561
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English (en)
Other versions
WO2009101586A3 (fr
Inventor
Jacobus Christiaan Faure Du Toit
Adriaan Nicholaas Schutte
Original Assignee
Jacobus Christiaan Faure Du Toit
Adriaan Nicholaas Schutte
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Application filed by Jacobus Christiaan Faure Du Toit, Adriaan Nicholaas Schutte filed Critical Jacobus Christiaan Faure Du Toit
Publication of WO2009101586A2 publication Critical patent/WO2009101586A2/fr
Publication of WO2009101586A3 publication Critical patent/WO2009101586A3/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S23/00—Arrangements for concentrating solar-rays for solar heat collectors
    • F24S23/30—Arrangements for concentrating solar-rays for solar heat collectors with lenses
    • F24S23/31—Arrangements for concentrating solar-rays for solar heat collectors with lenses having discontinuous faces, e.g. Fresnel lenses
    • 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
    • F24S10/20—Solar heat collectors using working fluids having circuits for two or more working fluids
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S20/00—Solar heat collectors specially adapted for particular uses or environments
    • F24S20/20—Solar heat collectors for receiving concentrated solar energy, e.g. receivers for solar power plants
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S20/00—Solar heat collectors specially adapted for particular uses or environments
    • F24S20/20—Solar heat collectors for receiving concentrated solar energy, e.g. receivers for solar power plants
    • F24S20/25—Solar heat collectors for receiving concentrated solar energy, e.g. receivers for solar power plants using direct solar radiation in combination with concentrated radiation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S20/00—Solar heat collectors specially adapted for particular uses or environments
    • F24S20/40—Solar heat collectors combined with other heat sources, e.g. using electrical heating or heat from ambient air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S23/00—Arrangements for concentrating solar-rays for solar heat collectors
    • F24S23/70—Arrangements for concentrating solar-rays for solar heat collectors with reflectors
    • F24S23/74—Arrangements for concentrating solar-rays for solar heat collectors with reflectors with trough-shaped or cylindro-parabolic reflective surfaces
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S60/00—Arrangements for storing heat collected by solar heat collectors
    • F24S60/30—Arrangements for storing heat collected by solar heat collectors storing heat in liquids
    • 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

Definitions

  • This invention relates to a solar energy collector and system for its use, which allows for the utilisation of solar energy as a holistic distributed energy source.
  • renewable energy sources With the increase in costs of current energy sources as well as the negative environmental effects of these sources, a renewed interest is shown in renewable energy sources.
  • Renewable energy systems cover a large variety of sources and the aim is to harness the energy opportunities locked into these.
  • Major sources are wind, wave, hydro, geothermal and solar.
  • This invention focuses on solar energy, since it is the most abundant form of renewable energy on the planet, its harnessing may have the least negative environmental impact of the renewable energy sources, and it provides the most scope for improvement over current systems.
  • renewable sources Energy produced from renewable sources is typically substantially more costly when compared to traditional sources such as fossil fuels and nuclear reactions. This is mostly due to the fact that the energy density of renewable sources (that is the amount of power that can be generated per volume of space of the collection / conversion equipment) is very low when compared to traditional sources. Thus, for an equivalent output a renewable power plant is many times the physical size of a fuel fired power plant and therefore typically considerably more expensive.
  • renewable resources Another consequence of the low energy density of renewable resources is the relatively low efficiency of the means to convert the input power to useful forms such as electricity. This is true for photovoltaic panels, but is especially relevant to the conversion of solar energy by means of a heat engine. Since the incident solar energy density is low, it is difficult to attain the high working fluid temperatures that are encountered in traditional plants, even through concentration. This results in a substantial fraction of the input energy having to be rejected as heat to the surrounding environment. Renewable energy is presently most often collected in a large installation from where it is 'transported' to the point of use. Examples of these are heliostat, parabolic trough and wind farm installations, where the renewable energy is converted to electrical energy in a centralized facility and 'transported' to users via an electrical distribution network.
  • This centralized generation scheme prevents the further utilization of potentially useful forms of energy that are by-products of the electrical generation process, e.g. rejected heat from a solar fired heat engine. Due to the low temperatures involved, the heat rejected is typically several times greater than the useful energy produced.
  • renewable energy is expensive to collect and only a small fraction of it can be converted to a form that is easily transportable over long distances, resulting in the bulk of the collected energy having to be discarded to the surrounding environment.
  • solar energy suffers from at least two further negative aspects.
  • the first is that the energy is only available between sunrise and sunset, and the solar output is influenced by seasonal variations, weather and so forth.
  • the second is that in most concentrator systems, when the sunlight is diffused by clouds, the energy level falls to almost zero. In systems that try to combine concentration with the ability to handle diffused energy, the concentration level is low and the overall system efficiency tends to be low.
  • a solar energy collector comprising an optical solar radiation concentrator operable to direct incident solar radiation to a primary solar energy collector and a secondary solar energy collector configured to collect at least some solar energy from diffuse solar radiation not directed to the primary solar energy collector.
  • the optical solar radiation concentrator to comprise a trough reflector, preferably a parabolic trough reflector, alternatively a circular or similar shaped trough reflector, having a focal line for reflected solar radiation, for the primary energy collector to be configured to collect solar energy from direct solar radiation concentrated along the focal line, and for the secondary energy collector to be configured to collect solar energy from diffuse solar radiation in a plane extending at least partly between the reflector and the focal line.
  • the primary collector to comprise a line receiver or a series of point receivers arranged in a line
  • the secondary collector to comprise a plate receiver or a series of line receivers arranged in a plane to form a plate receiver.
  • At least one of the line receivers in the plate receiver to comprise a series of point receivers arranged in a line.
  • line or point receivers forming the primary collector each to comprise a fluid conduit which presents fluid to the focal line and to be configured to heat the fluid, preferably to a first or a second temperature, alternatively a first and second temperature; and for the plate, line or point receivers forming the secondary collector each to comprise a fluid conduit which presents fluid to the plane of the secondary collector and to be configured to heat the fluid, preferably to a third temperature; wherein the first temperature is greater than the second temperature, and the second temperature is greater than the third temperature.
  • the primary and secondary energy collectors include photovoltaic cells configured to generate electrical energy and transfer collected solar energy to the fluid conduit associated with it.
  • the secondary energy collector is still further provided for the secondary energy collector to extend in a plane between the focal line and the bottom of the trough, and preferably to extend in a plane above the focal line.
  • the fluid in the fluid circuits to comprise a gas, liquid or a vapour.
  • optical solar radiation concentrator comprises a Fresnel lens.
  • a solar energy system which includes at least a solar energy collector, preferably as defined above, any one or more of a high temperature fluid circuit for fluid at about the first temperature, a medium temperature fluid circuit for fluid at about the second temperature, and a low temperature fluid circuit for fluid at about the third temperature, wherein the high and medium temperature circuits are connected to high or medium temperature heat sinks to operatively utilize heat from the high or medium temperature fluid circuits, alternatively or in addition to a heat engine to operatively generate electricity, and the low temperature circuit is connected at least to a low temperature heat sink to operatively utilize heat from the low temperature fluid circuit.
  • fluid to be collected from the output side of the heat engine at a temperature lower than the first temperature and to be introduced into the medium or low temperature circuits.
  • the high temperature circuit to include a high temperature energy storage device, including a fluid or alternative energy storage medium, including salt, device, alternatively or in addition to a high temperature backup energy generator, and for the backup energy generator to convert a fuel to heat or alternative energy storage media which is used to heat the fluid in the high temperature circuit, and preferably for the backup energy generator to utilize a gas fuel and to comprises a heat engine.
  • a high temperature energy storage device including a fluid or alternative energy storage medium, including salt, device, alternatively or in addition to a high temperature backup energy generator, and for the backup energy generator to convert a fuel to heat or alternative energy storage media which is used to heat the fluid in the high temperature circuit, and preferably for the backup energy generator to utilize a gas fuel and to comprises a heat engine.
  • the high temperature heat sinks to include one or more of cooking, baking and drying apparatus
  • the medium temperature heat sinks to include one or more of refrigeration, space cooling and dehumidifying apparatus
  • the low temperature heat sink to include one or more of space eating and water heating apparatus, including but not limited to swimming pool water heating.
  • the medium temperature circuit to include a medium temperature energy storage device, including a fluid or alternative energy storage medium, including salt, device, and for the low temperature circuit to include a low temperature energy storage device, including a fluid or alternative energy storage medium, including salt, device, alternatively or in addition to a medium temperature backup energy generator, and for the medium temperature backup energy generator to convert a fuel to heat or alternative energy storage media which is used to heat the fluid in the medium temperature circuit, and preferably for the medium temperature backup energy generator to utilize a gas fuel and to comprises an internal combustion engine.
  • the system includes electrical energy storage devices, including batteries and capacitance storage devices.
  • the system to include solar radiation tracking means and control and drive means configured to track the sun and manipulate the orientation of the optical solar radiation concentrator in respect of the sun to optimise the collection of solar energy.
  • control means for the respective heat sinks including valves, thermostats and pumps, the valves including control and shut-off valves and the pumps including positive displacement pumps; and for the system to include an optional heat dissipater.
  • control means to balance the pressure in the high, medium and low temperature circuits
  • control means to include pressure and flow regulators utilizing pressure, flow and temperature data, and more preferably for the pressure in the system to be controlled by measuring temperature in the system and using feedback control to the various circuits thereby balancing energy flow in the system, and including pressure accumulators to control sudden pressure changes in the system.
  • the system to include communication means configured to allow the system to communicate with a remote controller, for the system to be configured to at least receive data in respect of energy availability and current and expected energy consumption data for a predetermined geographical area within which the system is located from the remote controller, to process the data and manage the energy utilization of the system accordingly, and preferably for the system to also transmit data in respect of energy availability and current and expected energy consumption of the system to the remote controller for incorporation in the data available from the remote controller.
  • the communication means comprises a communication channel utilizing any one or more of the Internet, cellular phone technology (GSM, 3G, HSDPA, etc), land line telephony systems, radio communication systems or communication through electrical power networks.
  • GSM Global System for Mobile communications
  • an energy supply system comprising an electricity supply network in respect of a predefined geographical area, which includes a plurality of electricity consumers of which at least one consumer, and preferably a plurality of consumers, has a solar energy system as defined above installed and operational at its premises, wherein the energy supply system receives data from the solar energy system in respect of at least its current usage requirements and the energy supply system utilizes this data to make a determination of the total current energy requirement of the electricity supply network in respect of the geographical area.
  • the solar energy system to include in the data provided to the energy supply system data with respect to expected usage requirements and current and expected energy surpluses, and for the energy supply system to obtain surplus energy from the solar energy system.
  • Figure 1 shows an end view of a first embodiment of a solar collector according to the invention, having an elongate parabolic reflector
  • Figure 2 shows an end view of a second embodiment of a solar collector according to the invention, having an elongate circular cross sectional reflector
  • Figure 3 shows a perspective view of third embodiment of a solar collector according to the invention
  • Figure 4 is a schematic diagram showing the holistic distributed solar energy system ;
  • Figure 5 detail of sections 000 to 200 of Figure 4;
  • Figure 6 detail of sections 250 to 400 of Figure 4;
  • the solar collector (10) comprises a solar concentrator in the form of an elongate parabolic reflector (12), a primary solar absorber (14) positioned on the focal line (12.1 ) of the reflector (12) co-axial to the primary solar absorber (14), and a secondary solar absorber (16) positioned in the plane of symmetry of the reflector (12) in line with the focal line (12.1 ).
  • solar radiation indicated as lines 20 to 33 falls onto the reflector (12), is reflected from it, and is focussed on the focal line (12.1 ).
  • the focussing of the radiation onto the focal line (12.1 ) is a function of the shape of the parabolic reflector (12).
  • the reflected radiation will advantageously fall onto the secondary absorber (16).
  • the radiation (20 to 33) may be dispersed causing it to be focussed at another point distal from the focal line (12.1 ). In this event the reflected solar radiation will also fall onto the secondary absorber (16).
  • the primary solar absorber (14) is in the form of a high density photo voltaic collector and the secondary solar absorber (16) is in the form of a fluid cooled heat collector.
  • the photo voltaic absorber e.g. a heat absorbing fluid filled tube
  • the fluid cooled heat absorber e.g. a photo voltaic panel
  • a solar collector (48) which comprises an elongate, circular cross sectional solar reflector (46) and a combined primary and secondary solar absorber (70) positioned in the focal plane (46.1 ) of the concentrator, which is in the plane of symmetry of the solar collector (48).
  • solar radiation indicated as lines 50 to 68 falls onto the reflector (46), is reflected from the reflector (46), and is focussed onto the focal plane (46.1 ) which is co-planar with the combined primary and secondary solar absorber (70).
  • the focussing of the radiation onto the focal plane (46.1 ) is a function of the circular cross sectional reflector (46). It is to be appreciated that any type of reflector that approximates a parabolic reflector will reflect incident radiation onto a so called focal plane. However, it is further to be appreciated that the radiation will not necessarily be collimated to a point or line. The term "focus" is therefore used in the context of directing light onto a plane or line and not limited to collimating the light onto a particular plane, line or point.
  • the combined primary and secondary solar absorber (70) is in the form of a fluid cooled heat collector.
  • any other type of solar collector can be used in the place of the heat collector.
  • FIG 3 a collector similar to the collector shown in Figure 1 is shown in perspective view. Same reference numerals have been used for the same components. However an additional secondary collector (18) is shown in a plane (18.1 ) which is located in the plane of symmetry above the focal line (12.1 ). The secondary solar collector (16) is shown in a plane (16.1 ) which is located in the plane of symmetry below the focal line (12.1 ).
  • the second part of the invention has been divided into modular sections which may be omitted or included in a practical system depending on several factors including, but not limited to, where the system is to be used, what loads will be supplied, the system budget, etc. Thus any combination of the system sections may be used, although some combinations will be more practical than others. In addition, some sections may be relocated to different positions in the system. This will be discussed after the system description. Not all combinations are discussed in this invention, but are still provided for.
  • Some components may be omitted from individual sections without significantly affecting the operation of the system. Furthermore, many components, arrangements and sections may be duplicated to provide additional performance and/or functionality, without affecting the basic operation of the system.
  • Receivers may be of plate type, in which case they are to be used without any concentrating means or with low-concentration optics. Receivers may also be of line (tube) or point (cavity) types, in which case they are used with means to concentrate solar radiation onto the receiver (e.g. parabolic or cylindrical troughs and dishes, Fresnel lenses, heliostats, etc.). Plate receivers are capable of receiving both direct and diffuse radiation, while concentrating receivers are typically capable of only receiving direct solar radiation.
  • the present invention uses one or more solar radiation receivers capable of receiving direct and/or diffuse radiation.
  • the type and number of receivers is a function of where the system will be located, and what loads will be supplied.
  • the diagram in Fig 5 shows a typical system with two receivers, one a high-concentration ratio receiver (000) for direct radiation and a low-concentration ratio receiver (050) for diffuse radiation (the low- concentration receiver would also include the case of no concentration). In practice any combination and number of receivers may be used.
  • the invention makes provision to utilise a solar receiver such as shown in Figures 1 to 3, in addition to other types of receivers. If any of the receivers discussed in Figures 1 to 3 is used it would combine the high and low concentration receivers in one unit and any number of these could be utilised.
  • Heat transfer fluids are used to conduct absorbed solar energy from the receivers.
  • the receivers may first convert the radiation to some other useful form of energy (e.g. photovoltaic cells generating electricity) before the heat is conducted away by the transfer fluid, or the received radiation may be directly converted to heat and conducted away by the fluid.
  • Different fluids may be used to conduct the heat from different receivers, and the fluid may either be in liquid or gas/vapour form.
  • Means of establishing flow of heat transfer fluid through the receivers are provided, and the flow through each receiver is controlled to provide flow of heat transfer fluid of approximately constant temperature after the receiver output. This will cause the flow through the receiver to be approximately proportional to the solar input power.
  • the flow is established through two speed-controllable pumps (010, 060), although any means for establishing and controlling a flow through the receivers may be used (e.g. a single pump with proportional valves, gravity, etc.).
  • the high concentration ratio receivers are capable of producing heated fluid of high temperature, typically in the order of hundreds of degrees Celsius, while non- or low- concentration receivers will typically produce medium temperatures of less then 100 degrees Celsius.
  • sources may be any type of fuel, or alternative sources including but not limited to nuclear and geothermal sources.
  • sources may be any type of fuel, or alternative sources including but not limited to nuclear and geothermal sources.
  • One or more heat exchangers are used to transfer heat from the sources to the heat transfer fluid. Again means of establishing and controlling flows through the heat exchangers is provided in the form of pumps (1 10 and 160), so that the fluids exit the exchangers at approximately constant temperature. The flow through the exchangers is again approximately proportional to the heat delivered by the sources.
  • the diagram shows a fuel-fired boiler (100) and associated heat exchangers which augment the output of the solar receivers.
  • a single source is used to heat both the very high and low temperature fluids, although any number of sources may be used to heat the fluids to desired temperatures.
  • the use of backup sources may be minimized by storing excess thermal energy.
  • This excess thermal energy is stored at high temperature and could be used in the system when supply is lower than demand.
  • These storage devices (200) accept heated fluid and store this energy either by directly storing the heated fluid, or by transferring the heat of the fluid to other substance(s) and storing it as sensible, latent or chemical energy within those substance(s) or system(s).
  • a means of establishing and controlling a reversible flow through the storage device is provided.
  • high temperature heat transfer fluid is conducted through the storage device by running the pump (210) in reverse, thereby storing energy in the device.
  • the pump is run forward so that cold transfer fluid enters the device and high temperature fluid is made available to the remainder of the system.
  • the flow does not necessarily need to be reversed to extract energy from the storage device; any arrangement may be used where cold fluid is passed through the device so that it exits at a high temperature.
  • any means of establishing the flow through the storage device(s) may be used.
  • the high temperature conduit pressure can be used as an indication of the heat energy supply and demand relationship.
  • the pressure in the high temperature conduit will rise and the pump (210) must be operated in reverse in order to store energy in the storage device (200).
  • the pump (210) must be operated in the forward mode in order to supply heated fluid to the sinks (see Section 250 below).
  • the pump (210) is controlled via pressure sensor (PT230) so that the function of the pump (210) is to balance the flow of energy between the energy sources and sinks.
  • An accumulator (230) is provided to prevent sudden pressure fluctuations in the high temperature fluid conduit, which makes the system more controllable.
  • heat sinks are user devices which accept heated fluid at high temperature. Examples include ovens, stoves and other cooking devices, dish washers, tumble driers ironing devices and so forth.
  • each sink is controlled by a thermostat (262, 272), pump or any other means to ensure that the sink receives the amount of heat required.
  • the diagram shows two high temperature sinks (261 , 271 ), although the system may contain any number of high temperature sinks, including none.
  • Solenoid valves (260, 270) are provided to switch the sinks in and out of the circuit. This would then also allow for low-priority heat sinks to be switched off when energy input is low. These solenoids are shown in the diagram before the heat sinks, but could be placed at the low temperature side of the sinks to reduce their operating temperature. Section 300: Working Fluid Exchanger - Figure 6
  • a heat transfer fluid is used to conduct energy from the solar receivers, backup heat sources or storage devices, it may be necessary to transfer the heat to a working fluid for use in a heat engine in order to generate mechanical or electrical energy. This may however not be necessary with all types of heat engines, e.g. Stirling cycle engines.
  • the diagram shows, in section 400, a Rankine cycle engine (400), which requires steam as working fluid.
  • the working fluid heat exchanger (300) boils the engine's working fluid using the heated transfer fluid, and makes it available to this engine.
  • a feed pump (310) is used to establish a flow or working fluid through the exchanger. As working fluid is boiled off, the level of the fluid in the tank will drop. The pump (310) is therefore controlled to keep an approximately constant fluid level within the heat exchanger (300) by means of the level transmitter (LT300).
  • Fig. 5 No means for energy dissipation in the high temperature circuit is shown in Fig. 5. Although this can be provided for by duplication section 600 (see Fig 7) for the high temperature circuit, it would be more economical to move the solar collectors away from the sun and thereby reduce the input power. It is however expected that the maximum solar input power would always be desired, so that the heat engine may always produce electricity at the maximum rate possible. Any excess electrical energy that cannot be used or stored could be sold back into the mains electrical grid. Excess heat from the heat engine condenser would be dissipated in section 600 (Fig 7) once the medium and low temperature storage devices have reached their capacity. If the grid supply is not available, the solar collectors can be moved away from the sun.
  • Section 400 Main Generation - Figure 6
  • a heat engine (400) is used to convert the input heat to useful mechanical and/or electrical energy.
  • a Rankine cycle engine is shown in the diagram, but any heat engine or cycle may be used. This includes, but is not limited to, phase change cycles, gas only cycles and liquid only cycles and includes but is not limited to Steam, Stirling and Brayton engines.
  • Vapour exhaust from the expander is condensed in a condenser (450) and stored in a tank (440), which may be insulated. Heat extracted through condensation is transferred to a heat transfer fluid in the condenser (450) for use in the remainder of the system. Flow of the heat transfer fluid in the condenser (450) is established by a pump (460).
  • backup generation of electrical or mechanical power and heat may be included after the main generation heat engine. This can be performed by an engine of any thermodynamic cycle, in which heat is generated as a by-product of the mechanical / electrical power generation. Typically, an internal combustion engine using petrol, diesel or LPG / Natural Gas may be used.
  • the diagram shows an engine (500) connected to a generator (530). Heat transfer fluid is circulated through the engine or auxiliary heat exchanger(s) in order to extract combustion heat from the engine.
  • a pump (510) establishes this flow and it is controlled so that the engine (500) and the fluid output are at approximately constant temperature.
  • the exhaust gas of the engine may be passed through a further heat exchanger (550), in order to extract additional heat from the combustion process.
  • the low temperature fluid may also be passed through the exhaust by means of another pump (560).
  • a heat exchanger (600) is provided.
  • the heat exchanger is shown to dissipate heat to the atmosphere, but heat can be dissipated into water (e.g. swimming pool, Jacuzzi, ocean, river and so forth), into the ground, into an industrial process, or any other useful sink.
  • water e.g. swimming pool, Jacuzzi, ocean, river and so forth
  • a diverter valve (620) is controlled by a temperature sensor (TT620), which diverts some or all of the cold fluid return through the heat exchanger if the temperature of the fluid is above the preset value.
  • the diverter valve and controller may either be proportional or on/off type.
  • the pressure in this circuit will rise and the pump (710) from the Medium Temperature Storage (see Section 700) would typically be run in reverse. This will reduce the pressure in the medium temperature circuit and store the heat in the energy storage device. If the storage device cannot store this energy (i.e. it is full), the outlet through the pump (710) would be at elevated temperature. The hot fluid would then report directly to the cold fluid return, at which point the dissipater would initiate operation to ensure that the cold fluid return is at an acceptable temperature for the condenser and engine cooling requirements. This scheme will ensure that excess hot fluid always passes through the storage device, thereby ensuring that its temperature is kept as high as possible.
  • the solar collector(s) could be rotated away from the sun to reduce the energy input.
  • Section 700 Medium Temperature Storage - Figure 7
  • Section 200 (apart from the fact this is for medium temperature and Section 200 for high temperature), and will not be repeated in such detail.
  • medium temperature heat transfer fluid is stored in a storage device (700).
  • This storage device accepts heated fluid and stores this energy either by directly storing the heated fluid, or by transferring the heat of the fluid to other substance(s) and storing it as sensible, latent, chemical or nuclear energy within those substance(s).
  • Sections 200 and 700 are identical to that of Sections 200 and 700 (apart from the fact this is for low temperature).
  • the storage device is indicated as 750 in the diagram.
  • Section 800 Medium Temperature Heat Sinks - Figure 8
  • the diagram shows one medium temperature sink (841 ) linked directly to the cold return conduit.
  • the system may contain any number of medium temperature sinks, including none.
  • the flow through each sink is controlled by a thermostat (842), pump or any other means to ensure that the sink receives the amount of heat required.
  • the sink can also be switched out of the circuit by valve (840). The same principle is applied to all sinks.
  • medium temperature heat sinks e.g. absorption chillers
  • absorption chillers require fluid input at elevated temperature, while their output is still at a temperature that might be useful for low temperature sinks.
  • a cascaded system of sinks is provided for where the medium temperature sinks (821 , 831 ) first extract heat from the fluid, and their output is then fed to the low temperature sinks.
  • the diagram shows two cascaded medium temperature sinks, although the system may contain any number of medium temperature sinks, including none.
  • the cascaded medium temperature sinks provides, together with the low temperature conduit, the energy input to the low temperature sinks (Section 900).
  • a pressure reducing valve 800
  • additional heated fluid is admitted to the low temperature bus to satisfy the demand.
  • the thermostat (850) would however stop the flow in the cascaded system if the temperature on the cold side of the cascaded medium temperature sinks drop below a pre-set value. This will prevent cold fluid being passed to the low temperature heat sinks. In this situation, energy from the low temperature storage device will be used to satisfy the demand in the low temperature circuit.
  • a pressure relief valve (810) will open when the flow of the medium temperature sinks are higher than the low temperature sinks, so that the low temperature fluid conduit pressure exceeds a preset value. Heated fluid is then dumped directly to the cold fluid return. The energy of the heated fluid will not be lost, since an increase in temperature of the cold fluid return will lead to an increased flow rate in the medium temperature conduit. If the thermostat (850) closes due to low medium temperature heat sink outlet temperature, the relief valve (810) will also most probably open and admit the fluid to the cold return conduit.
  • Solenoid valves (820, 830) are provided to switch the sinks in and out of the circuit. This would then also allow low-priority heat sinks to be switched off when energy input is low. These solenoids are shown in the diagram before the heat sinks, but could also be placed after the sinks to reduce their operating temperature.
  • Section 900 Low Temperature Sinks - Figure 8
  • These heat sinks (921 , 931 , 941 ) accept heated fluid at low temperature. Examples include space and water heaters.
  • the flow through each sink is controlled by a thermostat (922, 932, 942), pump or any other means to ensure that the sink receives the amount of heat required.
  • the diagram shows three low temperature sinks (921 , 931 , 941 ), although the system may contain any number of low temperature sinks, including none.
  • Solenoid valves (920, 930, 940) are provided to switch the sinks in and out of the circuit. This would then also allow low-priority heat sinks to be switched off when energy input is low. These solenoids are shown in the diagram before the heat sinks, but could also be placed after the sinks to reduce their operating temperature.
  • Section 1000 Electrical and Control - Figure 9 and 10
  • Figures 9 and 10 show a typical electrical and control line diagram for the system.
  • power electronic converters (1510 to 1560) control the power sourced from all electrical-generating components in the system.
  • the sourced energy is placed onto a bus.
  • Electrical energy storage devices in this instance as batteries (1000 - 1004) are attached to these.
  • Power flow between the common DC bus and the mains grid is controlled by a multidirectional DC-AC converter (1230) and a duplication thereof (1240). More than one multi-directional AC/DC converter (1230, 1240) is used to optimise efficiency. The second converter (1240) and further duplications of 1230 are optional if increased AC load capacity is required. These converters (1230, 1240) allow bi-directional power flow between the mains grid (1200) and the common DC bus, although separate inverters and chargers can also be used.
  • a disconnect relay (1210) is provided, so that the system can continue supplying power to the user's loads when a power failure occurs without attempting to power off-premises equipment also connected to the grid. High power AC user equipment is connected before the disconnect relay, since the system will not be able to supply very large loads, especially not for extended periods of time. However, a configuration could be utilised that supply these high loads as well, but is not shown.
  • the remainder of the user's AC equipment (1250 to 1270 in Figure 9) is arranged in groups according to their priority to the user (1250 - High, 1260 - Medium, 1270 - Low). This allows the system to switch off low priority equipment (1270) when the system is low on stored electrical energy.
  • the user's DC loads at 48V and 12V are also grouped according to priority and connected to relays (1710 - High, 1720 - Medium, 1730 - Low, in Figure 10).
  • the system makes provision to inform the user of the switching to ensure the safe switching and intelligent equipment could be 'warned' of the eminent switching of the power.
  • converter (1570) provides regulated power (typically 24V) to the control system.
  • Controller (2000) accepts all measurements and data, calculates the required flows and controls the pump motors, solenoids, and other actuators in the system.
  • the individual components in the system are controlled so that the net flow of energy into and out of each conduit is on average zero.
  • Various control algorithms could be employed and a particular one is briefly discussed here.
  • the flow through the heat exchangers/receivers of all energy sources is regulated so that the fluids exit the exchangers at an approximate constant specified temperature.
  • the inflow of heated fluids into the system is controlled by the sun and atmospheric conditions for the solar receivers, and by the rate of fuel burn for the backup sources.
  • the system does not have direct control over the flow in the input heat exchangers.
  • the system does have indirect control over the heat input, for example by tracking the sun or tilting the solar collectors away from the sun, or by commanding a fuel flow rate.
  • the flows through the sinks are not normally determined by the system, but by the requirements of the end function the sinks are to perform.
  • the system may have full control over the flows of some sinks (e.g. sinks used for dissipation of surplus energy), but for most sinks the system will only be able to switch the sinks on and off according to their priority to the user.
  • the system controller (2000, Fig 10) does have full control over the flow through the storage devices (200, 700, 750).
  • the storage devices are primarily used to balance the flow from the sources and sinks. If the sources of a specific circuit produce more flow than the sources accept, the relevant storage device is used to store the excess energy. Similarly, if the sinks consume more flow than the sources can provide, the storage device is used to provide additional energy to the sinks.
  • the pressure of such circuit is monitored.
  • a rise in circuit pressure means excess energy, and a drop in system pressure a shortage of energy.
  • the accumulators are provided as means to dampen pressure fluctuations in the system and thereby aid controllability. The same is true for the electrical sources and sinks.
  • the common DC bus voltage is used to indicate the amount of energy available in the system, and the batteries are used as storage buffer.
  • the individual circuits (high, medium and low temperature) in the system are interconnected through heat exchangers, resulting in the circuits being sinks or sources for each other.
  • the heat engine circuit is a sink for the high temperature circuit
  • the high temperature circuit is a source for the heat engine circuit.
  • the storage elements can be seen as buffers that decouple the energy inputs and outputs of the circuits from each other. This will enable, for example, the heat engine to continue to generate power, even if no solar or alternative energy sources are available.
  • This invention describes the use of a trough concentrator which focuses the sun energy on a line-receiver for direct sunlight and on a plate receiver when the sunlight is diffused.
  • Other semi-focusing systems are well described in the literature and could also be utilised in the holistic distributed solar energy system.
  • the holistic distributed system would need more electric power to facilitate the operation of a small factory, small village, a hostel or any type of mass housing scheme. In such a case it might make sense to utilise the concept derived in the invention to include the option to install a heliostat type system for the increased electrical load.
  • Photo voltaic system can be implemented in both the high and low concentrated solar systems as well as in the non concentrated receiver system.
  • the cooling of the PVs would be used to drive the rest of the system as described in the invention.
  • flow establishing and controlling devices may be shared between Sections 000 and 100 to reduce costs.
  • pump 010 may supply both receiver 000 as well as heat exchanger 100 through a diverter valve. In this way, pumps 1 10, 160, 510 and 560 may be eliminated.
  • the cold return conduit and the transfer return conduit may be combined into one conduit.
  • Section 100 or Section 500 could be eliminated, as these two sections fundamentally perform the same function of providing additional electrical/mechanical power and heat during periods of low solar output or high demand.
  • Sections 100 and 200 may be interchanged. Boiler 100 and heat exchanger 300 may then be combined into a single device.
  • Some heat engines directly accept the high temperature heat transfer fluid from the receivers, boilers and storage devices, for example a Stirling heat engine.
  • section 300 Heating Exchanger
  • section 300 is not required and may be eliminated, thereby directly connecting the heat engine and high temperature conduits., as well as the heat engine return and transfer return conduits.
  • Section 300 Heating Exchanger
  • the working fluid of the heat engine may be boiled directly in receiver 000 and boiler 100. Sections 200 and 300 could then be completely eliminated. Pumps 010 and 1 10 would then act as feed pumps for the heat engine, and the high temperature conduit would conduct vapour directly to the steam accumulator. Again this will directly connect the heat engine and high temperature conduits, as well as the heat engine return and transfer return conduits.
  • the temperature sensors TTOOO and TT100 will then be replaced or supplemented with level sensors, and their attached pumps (or other flow establishment devices) controlled so that an approximately constant fluid level is maintained in the receivers and boilers.
  • Some heat engines as discussed in 3.4 accept the high temperature heat transfer fluid from the receivers, boilers and storage devices. In these cases sections 200 and 300 can be eliminated and boiler 100 is reduced to a fluid heating device with a lower operating pressure. The only pressure required is for control purposes.
  • the backup generator and the main heat engine may share the same mechanical to electrical converter.
  • some arrangement is provided for by which both the main heat engine and the backup combustion engine is connected to the mechanical to electrical converter. This can take the form of clutches, hydraulics or any other power transmission means. 4 Medium and Low temperature circuits
  • the heat dissipater is placed before the medium and low temperature storage devices, since this allows heated fluid to flow through the storage device to the dissipater when excess energy is available. This ensures that the storage devices will always be at maximum temperature while the dissipater is in operation.
  • such device(s) may be replaced with a pressure relief valve or a controlled solenoid valve that will allow dumping of hot fluid directly to the cold return.
  • this valve must be actuated so that the heat dissipater can dissipate the excess energy.
  • each cascaded heat sink may be fitted with its own cascade thermostat (850) and pressure relief valve (810). This will ensure that the maximum amount of energy be transferred to the low temperature circuit.
  • Low temperature fluid may be used as pre-heated fluid for high temperature exchangers/receivers, to increase efficiency. This is not shown in the diagram.
  • This invention provides for as many different temperature circuits as would optimise the overall efficiency and cost effectiveness of the system.
  • Flow establishment and control devices e.g. pumps 010, 060, 1 10, 160, etc. may be placed anywhere in the fluid conduit they service. However, to increase their reliability and extend the range of devices suitable for use, they are normally placed on the low temperature side of the heat receivers and exchangers.
  • the pumps associated with storage devices may be subjected to high temperatures when operated in reverse and the storage device is full. To prevent this, heat dissipation devices may be included between the storage device and the pump.
  • Non-return valves on pumps are provided to prevent reverse leakage through the pumps when they are not operational. If positive displacement pumps are used, non-return valves are normally not required.
  • the basic system could be improved substantially by linking the system to the Outside world', giving it information regarding the expected weather in the area and also the local or national energy conditions etc. This information could be utilised to enhance the overall operating condition of the system.
  • control system could be linked to an outside data source / higher level control system through the means of utilising current and future technologies of communication. Examples of current available communication opportunities are:
  • the invention was based on a control philosophy to use the pressure as the basic means of controlling the energy flow in the system.
  • Space cooling as currently known is based either on water evaporative systems or normal heat pump air conditioning systems.
  • the water evaporative systems make use of the principle that when a liquid evaporates that the temperature drops. These systems have a low energy requirement but lack performance in a high humidity environment.
  • This invention provides for an air condition system that is heat driven.
  • the technology is mature, but it is not usually deployed in typical house/small building applications where electricity is available.
  • the proposed air conditioning system utilises the absorption or adsorption based refrigeration principle. Heat is supplied as the energy source for the process.
  • the benefit derived from this is the fact that in the distributed system, as provided for in this invention, the heat does not need to be converted to electricity before it is utilised to drive a cooling process. Two process steps are eliminated (heat engine and electricity generation) and this results in savings on capital as well as an increase in overall efficiency. Apart from the conversion benefits, the storage of heat is much less capital intensive and would further reduce the capital outlay.
  • the invention would provide the heat requirements of the refrigerators and freezers which would also be based on the absorption or adsorption process as described in the previous section. The same benefits are applicable.
  • This invention provides for the heat to be derived from the solar system's high temperature circuit.
  • the heat can be in either the steam based system or in the high temperature liquid based system as discussed.
  • the high temperature circuit would provide high enough temperatures to drive a frying process.
  • This invention provides for heat to be utilised in a baking process.
  • ovens are either electrically or gas driven.
  • the heat from the solar system is utilised to drive the energy requirements of an oven.
  • the high temperature circuit of the invention is utilised for supplying the energy requirements. Again the conversion processes are eliminated and this results in capital and efficiency enhancements.
  • a dish washing machine utilises electrical elements to heat the water as well as to provide heat for the drying process.
  • This invention provides for the optimisation of dish washers to utilise solar energy systems as the heat source for the heating of the water and the drying process. The dish washer would still utilise electricity for the other operations.
  • this invention provides for the heat source of the tumble dryer to be sourced directly from the heat circuits of the distributed solar energy system.
  • the invention provides for the swimming pool to be heated by the holistic distributed solar energy system.
  • the pool could further be utilised as a heat drain for some of the processes that requires a fairly stable low side temperature source. It could also be utilised as an energy drain when the controller determine that the system has excess heat that needs to be dissipated. In this instance the maximum temperature of the pool as programmed in the controller would be used to determine the heat dissipation capacity of the pool.
  • the invention provides for the take off points for steam driven machinery.
  • the steam would be produced from the high temperature circuit.
  • the holistic distributed solar energy system provides for the utilisation of desiccant materials in a system to achieve this.
  • the dehumidifier works by blowing the humid air over the desiccant material which would absorb the water from the humid air, when the desiccant material is close to saturation, the system provides for heated air to be blown over the desiccant material which would remove the water from the desiccant material. This process is repeated and the required dehumidification takes place.
  • the energy for the heated air would be supplied by the solar system.
  • the fans and control would still be electrically operated.
  • the invention provides for the production of water from the atmosphere.
  • water could condensate from the atmosphere.
  • the condensate could be purified by a reverse osmosis process or by other filtering methods which is well established.

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Abstract

L'invention concerne un système d'énergie solaire comportant un concentrateur de rayonnement solaire optique permettant de diriger un rayonnement solaire incident sur un collecteur d'énergie solaire primaire et un collecteur d'énergie solaire secondaire configuré pour collecter au moins une partie de l'énergie solaire provenant d'un rayonnement solaire diffus non dirigé vers le collecteur d'énergie solaire primaire. L'invention concerne également un système d'énergie solaire holistique et un système d'alimentation en énergie.
PCT/IB2009/050561 2008-02-11 2009-02-11 Collecteur et système d'énergie solaire WO2009101586A2 (fr)

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2990499A1 (fr) * 2012-05-14 2013-11-15 Andre Jean Marie Philippe Cabarbaye Dispositif de concentration solaire uniformement repartie
US9726155B2 (en) 2010-09-16 2017-08-08 Wilson Solarpower Corporation Concentrated solar power generation using solar receivers
US9951756B2 (en) 2014-01-24 2018-04-24 Basf Se Pipeline system for a solar power plant
US10371126B2 (en) 2015-04-01 2019-08-06 Gina Tibbott Solar power collection systems and methods thereof
US10876521B2 (en) 2012-03-21 2020-12-29 247Solar Inc. Multi-thermal storage unit systems, fluid flow control devices, and low pressure solar receivers for solar power systems, and related components and uses thereof
NO20200447A1 (en) * 2020-04-14 2021-10-15 Kyoto Group As Thermal Energy Storage Device

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US4166446A (en) * 1976-12-03 1979-09-04 Bbc Brown Boveri & Company Limited Solar collector
FR2446447A1 (fr) * 1978-12-05 1980-08-08 Comp Generale Electricite Capteur solaire a miroir de concentration
US4220136A (en) * 1978-09-13 1980-09-02 Penney Richard J Solar energy collector
US4326502A (en) * 1975-04-07 1982-04-27 Ljubomir Radenkovic Solar energy collecting system
WO2005090873A1 (fr) * 2004-03-23 2005-09-29 Menova Engineering Inc. Capteur solaire

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Publication number Priority date Publication date Assignee Title
US4326502A (en) * 1975-04-07 1982-04-27 Ljubomir Radenkovic Solar energy collecting system
US4166446A (en) * 1976-12-03 1979-09-04 Bbc Brown Boveri & Company Limited Solar collector
US4220136A (en) * 1978-09-13 1980-09-02 Penney Richard J Solar energy collector
FR2446447A1 (fr) * 1978-12-05 1980-08-08 Comp Generale Electricite Capteur solaire a miroir de concentration
WO2005090873A1 (fr) * 2004-03-23 2005-09-29 Menova Engineering Inc. Capteur solaire

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9726155B2 (en) 2010-09-16 2017-08-08 Wilson Solarpower Corporation Concentrated solar power generation using solar receivers
US10280903B2 (en) 2010-09-16 2019-05-07 Wilson 247Solar, Inc. Concentrated solar power generation using solar receivers
US11242843B2 (en) 2010-09-16 2022-02-08 247Solar Inc. Concentrated solar power generation using solar receivers
US10876521B2 (en) 2012-03-21 2020-12-29 247Solar Inc. Multi-thermal storage unit systems, fluid flow control devices, and low pressure solar receivers for solar power systems, and related components and uses thereof
FR2990499A1 (fr) * 2012-05-14 2013-11-15 Andre Jean Marie Philippe Cabarbaye Dispositif de concentration solaire uniformement repartie
WO2013171385A1 (fr) * 2012-05-14 2013-11-21 Cabarbaye Andre Dispositif de concentration solaire uniformément répartie
US9951756B2 (en) 2014-01-24 2018-04-24 Basf Se Pipeline system for a solar power plant
US10371126B2 (en) 2015-04-01 2019-08-06 Gina Tibbott Solar power collection systems and methods thereof
US11085424B2 (en) 2015-04-01 2021-08-10 Gina Anne Tibbott Solar power collection system and methods thereof
NO20200447A1 (en) * 2020-04-14 2021-10-15 Kyoto Group As Thermal Energy Storage Device

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