US20160273807A1 - Solar heat collecting system - Google Patents
Solar heat collecting system Download PDFInfo
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- US20160273807A1 US20160273807A1 US15/008,604 US201615008604A US2016273807A1 US 20160273807 A1 US20160273807 A1 US 20160273807A1 US 201615008604 A US201615008604 A US 201615008604A US 2016273807 A1 US2016273807 A1 US 2016273807A1
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- 230000005855 radiation Effects 0.000 claims abstract description 152
- 239000012530 fluid Substances 0.000 claims abstract description 44
- 241001424688 Enceliopsis Species 0.000 claims abstract description 42
- 238000010438 heat treatment Methods 0.000 claims abstract description 7
- 230000005494 condensation Effects 0.000 claims description 13
- 238000009833 condensation Methods 0.000 claims description 13
- 238000011144 upstream manufacturing Methods 0.000 claims description 8
- 230000007423 decrease Effects 0.000 description 35
- 238000005338 heat storage Methods 0.000 description 31
- 238000010586 diagram Methods 0.000 description 8
- 230000008901 benefit Effects 0.000 description 7
- 230000006866 deterioration Effects 0.000 description 7
- 238000005259 measurement Methods 0.000 description 7
- 238000000034 method Methods 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 230000003203 everyday effect Effects 0.000 description 5
- 239000011521 glass Substances 0.000 description 5
- 239000000126 substance Substances 0.000 description 4
- 238000010248 power generation Methods 0.000 description 2
- 239000013535 sea water Substances 0.000 description 2
- 230000002528 anti-freeze Effects 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 238000010612 desalination reaction Methods 0.000 description 1
- 230000008034 disappearance Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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Classifications
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- F24J2/38—
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
- F24S50/00—Arrangements for controlling solar heat collectors
- F24S50/20—Arrangements for controlling solar heat collectors for tracking
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
- F24D19/00—Details
- F24D19/10—Arrangement or mounting of control or safety devices
- F24D19/1006—Arrangement or mounting of control or safety devices for water heating systems
- F24D19/1051—Arrangement or mounting of control or safety devices for water heating systems for domestic hot water
- F24D19/1057—Arrangement or mounting of control or safety devices for water heating systems for domestic hot water the system uses solar energy
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- F24J2/12—
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- F24J2/24—
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
- F24S10/00—Solar heat collectors using working fluids
- F24S10/40—Solar heat collectors using working fluids in absorbing elements surrounded by transparent enclosures, e.g. evacuated solar collectors
- F24S10/45—Solar heat collectors using working fluids in absorbing elements surrounded by transparent enclosures, e.g. evacuated solar collectors the enclosure being cylindrical
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- 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
- F24S50/00—Arrangements for controlling solar heat collectors
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/40—Solar thermal energy, e.g. solar towers
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/40—Solar thermal energy, e.g. solar towers
- Y02E10/44—Heat exchange systems
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/40—Solar thermal energy, e.g. solar towers
- Y02E10/47—Mountings or tracking
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Sustainable Development (AREA)
- Sustainable Energy (AREA)
- Thermal Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Heat-Pump Type And Storage Water Heaters (AREA)
- Engine Equipment That Uses Special Cycles (AREA)
Abstract
In one embodiment, a solar heat collecting system includes a heat collector configured to heat a heat medium by a sunray, a heating device configured to heat a heat utilizing fluid by heat of the heat medium, and a heat medium flow path configured to circulate the heat medium between the heat collector and the heating device. The system further includes a controller configured to control circulation of the heat medium in the heat collector in accordance with an amount of solar radiation of the sunray, or in accordance with a temperature difference between a first temperature of the heat medium at a first position and a second temperature of the heat medium at a second position located downstream of the first position with respect to the heat medium.
Description
- This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2015-56449, filed on Mar. 19, 2015, the entire contents of which are incorporated herein by reference.
- Embodiments described herein relate to a solar heat collecting system.
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FIG. 11 is a schematic diagram showing a first example of a configuration of a conventional solar heat collecting system. - The solar heat collecting system in
FIG. 11 includes aheat collector 1, apump 2, a heatmedium flow path 3, aheater 4, an on-offvalve 5 and a heat utilizingfluid flow path 6, and collects solar heat from sunrays. Arrows X and Y indicate horizontal directions that are perpendicular to each other. An arrow Z indicates a vertical direction. - A
heat medium 11 in the heatmedium flow path 3 is transferred by thepump 2 to flow into theheat collector 1. Theheat medium 11 is heated by sunrays in theheat collector 1. The heatedheat medium 11 flows out from theheat collector 1 and flows into theheater 4 to heat aheat utilizing fluid 12 in theheater 4 by heat exchange. - The
heat utilizing fluid 12 flowing out from theheater 4 flows into a heat utilizing destination (not illustrated) through the heat utilizingfluid flow path 6. An example of the heat utilizing destination is a heat utilizing facility. For example, when the heat utilizing destination is a hot water supply facility, water as theheat utilizing fluid 12 is heated in theheater 4 and supplied as hot water. Another example of the heat utilizing destination is a power generation facility. For example, when the heat utilizing destination is a turbine power generation facility of a Rankine cycle, a turbine operating medium as theheat utilizing fluid 12 is heated in theheater 4. Another example of the heat utilizing destination is a water treatment facility. For example, when the heat utilizing destination is a seawater desalination facility, seawater as theheat utilizing fluid 12 is heated in theheater 4. - Heat of the
heat utilizing fluid 12 is utilized by the heat utilizing destination, so that the temperature of theheat utilizing fluid 12 decreases and theheat utilizing fluid 12 then flows out from the heat utilizing destination. In this way, theheat utilizing fluid 12 circulates between theheater 4 and the heat utilizing destination via the heat utilizingfluid flow path 6. The heat utilizingfluid flow path 6 is provided with the on-offvalve 5. On the other hand, heat of theheat medium 11 is utilized by theheater 4, so that the temperature of theheat medium 11 decreases and theheat medium 11 then flows out from theheater 4. In this way, theheat medium 11 circulates between theheat collector 1 and theheater 4 via the heatmedium flow path 3. -
FIGS. 12 and 13 are a perspective view and a sectional view showing a structure of theconventional heat collector 1. - Types of the
heat collector 1 include a condensation type and a non-condensation type. Examples of the condensation-type heat collector 1 include a trough type, a Fresnel type and a tower type.FIGS. 12 and 13 illustrate an example of the trough-type heat collector 1. - As illustrated in
FIG. 13 , theheat collector 1 includes a reflectingmirror 21, aheat collecting pipe 22, asupport 23 and aglass pipe 24, and is provided on the ground G. - The reflecting
mirror 21 has a curved shape that is long in a horizontal direction. A section perpendicular to the longitudinal direction of the reflectingmirror 21 is a parabola. Theheat collector 1 rotates and drives the reflectingmirror 21 so as to make an axis K (a straight line connecting a focal point and an apex) of the parabola parallel to the sunrays S1. That is, thereflecting mirror 21 tracks the sun according to the altitude of the sun. Reference character S2 denotes a reflected light of sunray S1 reflected by thereflecting mirror 21. - The
heat collecting pipe 22 is arranged at the focal point of the parabola. Theheat collector 1 may adjust the rotation center of the reflectingmirror 21 to the focal point of the parabola or may adjust the rotation center of the reflectingmirror 21 to a point different from the focal point. InFIG. 13 , the rotation center is the end of thesupport 23 and the reflectingmirror 21 rotates in a direction of an arrow A1. The reflectingmirror 21 has a structure connected and integrated with theheat collecting pipe 22. Theheat collecting pipe 22 rotates in a direction of an arrow A2 in response to the rotation of the reflectingmirror 21 in the arrow A1. The rotation center of theheat collecting pipe 22 is same as that of the reflectingmirror 21. Accordingly, from a viewpoint of a phase in the peripheral direction of theheat collecting pipe 22, rotation of the reflectingmirror 21 has no influence in a surface area of theheat collecting pipe 22 that is nearest to the reflectingmirror 21. -
FIG. 14 is an enlarged sectional view showing the structure of theconventional heat collector 1. - The
heat collecting pipe 22 is a pipe arranged in parallel with the horizontal axes of the reflectingmirrors 21. The sunrays S1 are reflected by thereflecting mirrors 21 to become the reflected lights S2 and the reflected lights S2 are condensed to theheat collecting pipe 22. Theheat medium 11 flows through theheat collecting pipe 22. Theheat medium 11 flows in from one end of theheat collecting pipe 22 and flows out from the other end of theheat collecting pipe 22. - Only a portion of the
heat collecting pipe 22 where the reflected lights S2 are condensed is in thetransparent glass pipe 24. Theheat collecting pipe 22 is a metal pipe, for example. A space between theheat collecting pipe 22 and theglass pipe 24 is preferably avacuum 13. However, air may exist between theheat collecting pipe 22 and theglass pipe 24 depending on a sealing structure between theheat collecting pipe 22 and theglass pipe 24. Theheat medium 11, which is oil, for example, is heated by the condensed reflected lights S2. -
FIG. 15 is a schematic diagram showing a second example of the configuration of the conventional solar heat collecting system. In the descriptions onFIG. 15 , descriptions on the components same as those in the first example are omitted. - The solar heat collecting system in
FIG. 15 includes aheat storage tank 7 instead of theheater 4. The solar heat collecting system inFIG. 15 further includes an on-offvalve 8 that is provided with the heat utilizingfluid flow path 6 in the vicinity of the exit of theheat storage tank 7 in addition to the on-offvalve 5 that is provided with the heat utilizingfluid flow path 6 in the vicinity of the entrance of theheat storage tank 7. During a heat storage operation, theheat medium 11 in the heatmedium flow path 3 is transferred by thepump 2 to flow into theheat collector 1. Theheat medium 11 is heated by sunrays in theheat collector 1. The heatedheat medium 11 flows out from theheat collector 1 into theheat storage tank 7 and heats a heatstorable substance 14 in theheat storage tank 7 by heat exchange. - At that time, the on-off
valves heat utilizing fluid 12 does not circulate. - During a heat utilizing operation, the on-off
valves heat utilizing fluid 12 in the heat utilizingfluid flow path 6 flows into theheat storage tank 7 and is heated by heat exchange with the heatstorable substance 14. In this way, heat of theheat medium 11 in the present system is given to theheat utilizing fluid 12 via the heatstorable substance 14. Theheat utilizing fluid 12 flowing out from theheat storage tank 7 flows into a heat utilizing destination (not illustrated). Heat of theheat utilizing fluid 12 is utilized by the heat utilizing destination, the temperature of theheat utilizing fluid 12 decreases, and theheat utilizing fluid 12 flows out from the heat utilizing destination. At that time, thepump 2 stops and theheat medium 11 does not circulate. -
FIG. 16 is a schematic diagram showing a third example of the configuration of the conventional solar heat collecting system. In the descriptions onFIG. 16 , descriptions on the components same as those in the first and second examples are omitted. - Similarly to the solar heat collecting system in
FIG. 15 , the solar heat collecting system inFIG. 16 includes theheat storage tank 7 and the on-offvalve 8. However, theheat storage tank 7 inFIG. 16 includes no heatstorable substance 14. - During a heat storage operation, the
heat medium 11 in the heatmedium flow path 3 is transferred by thepump 2 to flow into theheat collector 1. Theheat medium 11 is heated by sunrays in theheat collector 1. Theheated heat medium 11 flows out from theheat collector 1 into theheat storage tank 7 and increases the temperature in theheat storage tank 7. At that time, the on-offvalves heat utilizing fluid 12 does not circulate. - During a heat utilizing operation, the on-off
valves heat utilizing fluid 12 in the heat utilizingfluid flow path 6 flows into theheat storage tank 7 and is heated by heat exchange with theheat medium 11 in theheat storage tank 7. Theheat utilizing fluid 12 flowing out from theheat storage tank 7 flows into a heat utilizing destination (not illustrated). Heat of theheat utilizing fluid 12 is utilized by the heat utilizing destination, the temperature of theheat utilizing fluid 12 decreases, and theheat utilizing fluid 12 flows out from the heat utilizing destination. At that time, thepump 2 stops and theheat medium 11 does not circulate. -
FIG. 17 is a schematic diagram illustrating a fourth example of the configuration of the conventional solar heat collecting system. In the descriptions onFIG. 17 , descriptions on the components same as those in the first to third examples are omitted. - The
heat collector 1 inFIG. 17 is a non-condensation type and does not track the sun. The solar heat collecting system inFIG. 17 is a hot water supply system with theheat collector 1 installed on a rooftop of a house. - During a heat storage operation, the
heat medium 11 in the heatmedium flow path 3 is transferred by thepump 2 to flow into theheat collector 1. Theheat medium 11 is antifreeze, for example. Theheat medium 11 is heated by sunrays in theheat collector 1. Theheated heat medium 11 flows out from theheat collector 1 into theheat storage tank 7 and heats theheat utilizing fluid 12 in theheat storage tank 7 by heat exchange. At that time, the on-offvalves 5 and 8 (not illustrated) are closed and theheat utilizing fluid 12 does not circulate. Theheat utilizing fluid 12 is water, for example. - During a heat utilizing operation, the on-off
valves heat utilizing fluid 12 in theheat storage tank 7 flows out from theheat storage tank 7 into a heat utilizing destination (not illustrated). Heat of theheat utilizing fluid 12 is utilized by the heat utilizing destination, the temperature of theheat utilizing fluid 12 decreases, and theheat utilizing fluid 12 flows out from the heat utilizing destination. At that time, thepump 2 stops and theheat medium 11 does not circulate. -
FIG. 1 is a schematic view showing a configuration of a solar heat collecting system of a first embodiment; -
FIG. 2A and 2B are graphs showing an example of an amount of direct solar radiation and an amount of acquired heat in the solar heat collecting system of the first embodiment; -
FIG. 3 is a schematic view showing a configuration of a solar heat collecting system of a second embodiment; -
FIG. 4 is a schematic view showing a configuration of a solar heat collecting system of a third embodiment; -
FIGS. 5A and 5B are graphs showing an example of the amount of direct solar radiation and the amount of acquired heat in a solar heat collecting system of a fourth embodiment; -
FIG. 6 is a schematic view showing a configuration of a solar heat collecting system of a sixth embodiment; -
FIG. 7 is a schematic view showing a configuration of a solar heat collecting system of a ninth embodiment; -
FIG. 8 is a sectional view for explaining the operation of a heat collector of a thirteenth embodiment; -
FIG. 9 is a sectional view for explaining the operation of a heat collector of a fourteenth embodiment; -
FIG. 10 is a sectional view for explaining the operation of a heat collector of a fifth embodiment; -
FIG. 11 is a schematic diagram showing a first example of a configuration of a conventional solar heat collecting system; -
FIG. 12 is a perspective view showing a structure of a conventional heat collector; -
FIG. 13 is a sectional view showing the structure of the conventional heat collector; -
FIG. 14 is an enlarged sectional view showing the structure of the conventional heat collector; -
FIG. 15 is a schematic diagram showing a second example of the configuration of the conventional solar heat collecting system; -
FIG. 16 is a schematic diagram showing a third example of the configuration of the conventional solar heat collecting system; -
FIG. 17 is a schematic diagram showing a fourth example of the configuration of the conventional solar heat collecting system; -
FIGS. 18A and 18B are graphs showing a first example of the amount of direct solar radiation and an amount of collected heat in the conventional solar heat collecting system; -
FIGS. 19A and 19B are graphs showing a second example of the amount of direct solar radiation and the amount of collected heat in the conventional solar heat collecting system; and -
FIGS. 20A and 20B are graphs showing a third example of the amount of direct solar radiation and the amount of collected heat in the conventional solar heat collecting system. - Embodiments will now be explained with reference to the accompanying drawings.
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FIGS. 18A and 18B are graphs showing a first example of an amount of direct solar radiation and an amount of collected heat in the conventional solar heat collecting system. -
FIG. 18A shows an example of change in the amount of direct solar radiation with time in the vicinity of theheat collector 1. The amount of direct solar radiation is an amount of heat received per unit time and per unit area by a plane whose normal line is parallel to an incident direction of sunrays. -
FIG. 18B shows change in the amount of collected heat by theheat collector 1 with time with respect to the amount of direct solar radiation inFIG. 18A . The amount of collected heat inFIG. 18B shows the amount of collected heat that theheat medium 11 in the vicinity of the exit of theheat collector 1 has collected from the entrance to the exit of theheat collector 1 from sunrays. - During the time indicated by the abscissa in
FIG. 18B , change in incident angles of sunrays to theheat collector 1 can be ignored. - In
FIG. 18A , the sun is behind a cloud from time t1 to time t3, and the sun appears from a cloud before time t1 and after time t3. Time t2 is a time between time t1 to time t3. Time t4 is a time after time. t3. When the sun disappears behind a cloud at time t1, the amount of direct solar radiation drops suddenly to reach zero. When the sun appears from a cloud at time t3, the amount of direct solar radiation rises suddenly to return to the value before the time t1. - In
FIG. 18B , when the amount of direct solar radiation becomes zero at time t1, the amount of collected heat gently decreases to be a negative value from time t1. The reason why the amount of collected heat gently decreases is that theheat medium 11 flowing out from theheat collector 1 is heated by sunrays before time t1. Time t5 represents a time when the amount of collected heat reaches zero. Time t6 represents an example of a time when the amount of collected heat is a negative value. When the amount of direct solar radiation becomes a value other than zero at time t3, the amount of collected heat gently increases from time t3 to return to the value before time t1. The reason why the amount of collected heat gently increases is that theheat medium 11 flowing out from theheat collector 1 is not heated by sunrays before time t3. - The amount of collected heat by the
heat collector 1 is a value obtained by subtracting an amount of radiation from theheat collector 1 to the air from an amount of received heat from sunrays. In a time period when the amount of collected heat is a negative value, the amount of direct solar radiation and the amount of received heat are zero but the amount of radiation is not zero. As a result, the amount of collected heat in this time is negative. -
FIGS. 19A and 19B are graphs showing a second example of the amount of direct solar radiation and the amount of collected heat in the conventional solar heat collecting system.FIG. 19A shows an example of change in the amount of direct solar radiation with time in the vicinity of theheat collector 1.FIG. 19B shows change in the amount of collected heat by theheat collector 1 with time with respect to the amount of direct solar radiation inFIG. 19A . - In
FIG. 19A , the sun repeatedly appears from a cloud and disappears behind a cloud from time t1 to time t3. For example, the sun is behind a cloud from time t1 to time t2 and appears from the cloud again at time t2. Accordingly, a time period in which the amount of direct solar radiation remains zero is shorter than that inFIG. 18A . Since the amount of direct solar radiation gently decreases, an integrated amount of collected heat is a positive value from time t1 to time t2. This is repeated multiple times between time t1 and time t2. Consequently, the integrated amount of collected heat from time t1 to time t3 is a positive value. -
FIGS. 20A and 20B are graphs showing a third example of the amount of direct solar radiation and the amount of collected heat in the conventional solar heat collecting system.FIG. 20A shows an example of change in the amount of direct solar radiation with time in the vicinity of theheat collector 1.FIG. 20B shows change in the amount of collected heat by theheat collector 1 with time with respect to the amount of direct solar radiation inFIG. 20A . - In
FIG. 20A , the sun repeatedly appears from a cloud and disappears behind a cloud from time t1 to time t3. The repetition frequency of the appearance and disappearance is higher than that inFIG. 19A . A time period in which the amount of direct solar radiation remains zero is shorter than those inFIGS. 18A and 19A . As a result, from time t1 to time t3, the amount of collected heat is smaller than that before time t1 but does not reach a negative value. - On the basis of the descriptions of
FIGS. 18A and 18B to 20A and 20B , an amount of direct solar radiation and an amount of collected heat in a conventional solar heat collecting system will be described. - In a time period in which the amount of collected heat by the
heat collector 1 is a negative value, the amount of radiation is larger than the amount of received heat. As such a time period is longer, an integrated amount of collected heat by theheat collector 1 from sunrise to sunset decreases. Further, power consumed by thepump 2 in this time period is wasted. Accordingly, as this time period in the solar heat collecting system is longer, an amount of acquired energy, which is obtained by subtracting an energy consumption amount from an energy amount acquired from sunrays, considerably decreases. - When the solar heat collecting system includes the
heat storage tank 7 as inFIGS. 15 to 17 , variation in the amount of collected heat is large in a view point of a time or a variation width but variation in the amount of heat to heat theheat utilizing fluid 12 in thestorage tank 7 is small and is generally kept not to reach a negative value. However, in a time period in which the amount of collected heat is a negative value, no heat is supplied to theheat storage tank 7, and further, heat is radiated from the surface of theheat collector 1 to the air. Accordingly, as such a time period is longer, the amount of stored heat in theheat storage tank 7 from sunrise to sunset decreases. Further, power consumed by thepump 2 in this period is wasted. As such a time period in the solar heat collecting system is longer, the amount of acquired energy in the solar heat collecting system considerably decreases. - In
FIGS. 1 to 10 , components same as or similar to those inFIGS. 11 to 20 are denoted by same reference characters as those inFIGS. 11 to 20 , and descriptions overlapping with those inFIGS. 11 to 20 are omitted. - In one embodiment, a solar heat collecting system includes a heat collector configured to heat a heat medium by a sunray, a heating device configured to heat a heat utilizing fluid by heat of the heat medium, and a heat medium flow path configured to circulate the heat medium between the heat collector and the heating device. The system further includes a controller configured to control circulation of the heat medium in the heat collector in accordance with an amount of solar radiation of the sunray, or in accordance with a temperature difference between a first temperature of the heat medium at a first position and a second temperature of the heat medium at a second position located downstream of the first position with respect to the heat medium.
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FIG. 1 is a schematic view showing a configuration of a solar heat collecting system of a first embodiment. - Similarly to the system in
FIG. 16 , the solar heat collecting system inFIG. 1 includes theheat collector 1, thepump 2, the heatmedium flow path 3, the on-offvalve 5, the heat utilizingfluid flow path 6, theheat storage tank 7 and the on-offvalve 8. Thestorage tank 7 in the present embodiment corresponds to thestorage tank 7 inFIG. 16 . However, thestorage tank 7 in the present embodiment may be replaced with theheater 4 inFIG. 11 , theheat storage tank 7 inFIG. 15 , or theheat storage tank 7 inFIG. 17 . Each of theheater 4 and theheat storage tanks 7 is an example of a heating device. Theheat collector 1 in the present embodiment may be a condensation type or may be a non-condensation type. Theheat collector 1 in the present embodiment is a trough type, for example. The solar heat collecting system inFIG. 1 further includes a directsolar radiation meter 31 and acontroller 32. - The direct
solar radiation meter 31 is arranged at a position at which the amount of direct solar radiation from sunrays can be measured, for example, at a position in the vicinity of theheat collector 1. The directsolar radiation meter 31 measures the amount of direct solar radiation from sunrays and transmits the measurement result of the amount of direct solar radiation to thecontroller 32. - The
controller 32 controls circulation of theheat medium 11 in theheat collector 1 in accordance with the amount of direct solar radiation received from the directsolar radiation meter 31. For example, thecontroller 32 controls stop of the circulation of theheat medium 11, restart of the circulation of theheat medium 11, adjustment of the flow rate of theheat medium 11 and the like. Thecontroller 32 in the present embodiment can control the circulation of theheat medium 11 by controlling the on/off and operation speed of thepump 2. Thecontroller 32 may further control operations of theheat collector 1, theheat storage tank 7, the on-offvalves - Hereinafter, operations of the
controller 32 in the present embodiment will be described. - The
controller 32 continuously monitors an amount of direct solar radiation using the directsolar radiation meter 31 and periodically compares the amount of direct solar radiation with a predetermined value that is determined in advance. The predetermined value is stored in a memory or storage of thecontroller 32, for example. The predetermined value is 0 W/m2 or a value close to 0 W/m2, for example. - In the case where the
pump 2 operates and theheat medium 11 circulates in theheat collector 1, when the amount of direct solar heat is larger than the predetermined value, thecontroller 32 continues the operation of thepump 2. Thereby, circulation of theheat medium 11 in theheat collector 1 continues. On the other hand, in the case where thepump 2 operates and theheat medium 11 circulates in theheat collector 1, when the amount of direct solar heat becomes smaller than the predetermined value, thecontroller 32 stops thepump 2. Thereby, circulation of theheat medium 11 in theheat collector 1 stops. - When the amount of direct solar radiation is equal to the predetermined value, the
controller 32 may continue circulation of theheat medium 11 or may stop circulation of theheat medium 11. However, in the case where the predetermined value is set to 0 W/m2, when the amount of direct solar radiation is equal to the predetermined value, circulation of theheat medium 11 stops. In this case, circulation of theheat medium 11 is continued when the amount of direct solar radiation is not 0 W/m2, circulation of theheat medium 11 stops when the amount of direct solar radiation is 0 W/m2. - In this way, when the amount of direct solar radiation is smaller than the predetermined value, the
controller 32 stops thepump 2 to stop circulation of theheat medium 11 in theheat collector 1. Subsequently, thecontroller 32 continues to monitor the amount of direct solar radiation. - In the case where the
pump 2 stops and circulation of theheat medium 11 stops, when the amount of direct solar radiation is smaller than the predetermined value, thecontroller 32 keeps thepump 2 stopped. Thereby, stop of circulation of theheat medium 11 continues. On the other hand, in the case where thepump 2 stops and circulation of theheat medium 11 is stopped, when the amount of direct solar radiation becomes larger than the predetermined value, thecontroller 32 restarts the operation of thepump 2. Thereby, circulation of theheat medium 11 in theheat collector 1 restarts. - In the present embodiment, the predetermined value for restarting the operation of the
pump 2 is same as the predetermined value for stopping thepump 2. However, these values may differ from each other. -
FIG. 2A and 2B are graphs showing an example of the amount of direct solar radiation and an amount of acquired heat in the solar heat collecting system of the first embodiment.FIG. 2A shows an example of change in the amount of direct solar radiation measured by the directsolar radiation meter 31 with time. A solid line inFIG. 2B shows change in the amount of acquired heat by theheat collector 1 with time with respect to the amount of direct solar radiation inFIG. 2A . The amount of acquired heat inFIG. 2B shows the amount of heat transferred to the exit of theheat collector 1, based on the assumption that theheat medium 11 in theheat collector 1 circulates. The total amount of acquired heat by theheat medium 11 is identical with the total amount of heat collected by theheat medium 11 in the heat collector 1 (shown by a dotted line inFIG. 2B ). - The amount of direct solar radiation in
FIG. 2A decreases to 0 W/m2 at time t1. Accordingly, when the predetermined value is 0 W/m2, thepump 2 stops at time t1. Thereafter thepump 2 is kept stopped until time t3. On the other hand, the amount of direct solar radiation inFIG. 2A increases from 0 W/m2 at time t3. Accordingly, the operation of thepump 2 restarts at time t3. - When the amount of direct solar radiation becomes zero, the amount of received heat by the
heat collector 1 decreases to zero. However, theheat collector 1 radiates heat even when the amount of received heat by theheat collector 1 becomes zero. Accordingly, when the amount of direct solar radiation becomes zero, the amount of acquired heat by theheat collector 1 becomes a negative value, as shown inFIG. 2B . InFIG. 2B , the amount of direct solar radiation becomes zero at time t1 so that the amount of acquired heat by theheat collector 1 is a negative value after time t5. - The above phenomenon can be seen also in
FIG. 18B . However, the absolute value of the negative value inFIG. 2B is smaller than that inFIG. 18B . The reason for this is that thepump 2 stops when the amount of direct solar radiation becomes zero in the present embodiment. Since theheat medium 11 is not transferred during stop of thepump 2, the amount of heat carried out from theheat collector 1 by theheat medium 11 is zero (for this reason, the amount of collected heat during stop of thepump 2 is zero). Accordingly, the absolute value of the negative value inFIG. 2B is smaller than that inFIG. 18B (the more detailed reason will be given later). Therefore, according to the present embodiment, an amount of wasted radiation from theheat collector 1 when the amount of direct solar radiation is zero can be reduced. - In the present embodiment, when the amount of direct solar radiation becomes zero, the
pump 2 is stopped. If thepump 2 continues to operate after the amount of direct solar radiation becomes zero, thepump 2 operates even in a period when the amount of collected heat is a negative value. In this case, no energy can be acquired from sunrays in this period but the operation of thepump 2 consumes power. Accordingly, wasteful consumption of energy becomes large and the amount of acquired energy in the system considerably decreases. However, according to the present embodiment, when the amount of direct solar radiation becomes zero, thepump 2 is stopped. Accordingly, such wasteful consumption of energy can be reduced and decrease in the amount of acquired energy in the system can be suppressed. - When circulation of the
heat medium 11 stops, heat transfer between the inner wall surface of theheat collector 1 and theheat medium 11 is not forced-convection heat transfer and the heat transfer coefficient between the inner wall surface of theheat collector 1 and theheat medium 11 is reduced. Accordingly, when circulation of theheat medium 11 stops, an amount of radiation from theheat medium 11. to the air through theheat collector 1 is reduced. As a result, the amount of collected heat from sunrise to sunset increases. This also contributes to increase in the amount of acquired energy in the present embodiment. - Circulation of the
heat medium 11 may be stopped by a method other than stop of thepump 2. For example, circulation of theheat medium 11 may be stopped by fully closing an on-off valve (not illustrated) provided with the heatmedium flow path 3. In this case, when this on-off valve is opened, circulation of theheat medium 11 can restart. Thecontroller 32 controls the operation of this on-off valve. - As described above, in the present embodiment, circulation of the
heat medium 11 in theheat collector 1 is controlled in accordance with the amount of solar radiation from sunrays. - Therefore, according to the present embodiment, decrease in the amount of acquired energy in the solar heat collecting system caused by variation in the amount of collected heat by the
heat collector 1 can be suppressed. -
FIG. 3 is a schematic view showing a configuration of a solar heat collecting system of a second embodiment. - The solar heat collecting system in
FIG. 3 includesthermometers FIG. 1 . However, inFIG. 3 , illustration of the directsolar radiation meter 31, thepump 2, the on-offvalve 5, the heat utilizingfluid flow path 6, theheat storage tank 7 and the on-offvalve 8 is omitted. - The
thermometer 33 is arranged on the heatmedium flow path 3 in the vicinity of the entrance of theheat collector 1 and measures the temperature (an entrance temperature) of theheat medium 11 at the entrance of theheat collector 1. The entrance of theheat collector 1 is an example of a first position. The entrance temperature of theheat collector 1 is an example of a first temperature. Thethermometer 33 transmits the measurement result of the entrance temperature of theheat collector 1 to thecontroller 32. - The
thermometer 34 is arranged on the heatmedium flow path 3 in the vicinity of the exit of theheat collector 1 and measures the temperature (an exit temperature) of theheat medium 11 at the exit of theheat collector 1. The exit of theheat collector 1 is an example of a second position located downstream of the first position with respect to the heat medium. The exit temperature of theheat collector 1 is an example of a second temperature. Thethermometer 34 transmits the measurement result of the exit temperature of theheat collector 1 to thecontroller 32. - The
controller 32 controls circulation of theheat medium 11 in theheat collector 1 in accordance with a temperature difference between the entrance temperature received from thethermometer 33 and the exit temperature received from thethermometer 34. More specifically, when thepump 2 operates and theheat medium 11 circulates in theheat collector 1, thecontroller 32 stops thepump 2 in accordance with the temperature difference to stop circulation of theheat medium 11. In the present embodiment, the temperature difference is a value obtained by subtracting the entrance temperature from the exit temperature. When the temperature of theheat medium 11 increases in theheat collector 1, the temperature difference is positive. When the temperature of theheat medium 11 decreases in theheat collector 1, the temperature difference is negative. - The
controller 32 controls circulation of theheat medium 11 in theheat collector 1 in accordance with the amount of direct solar radiation received from the directsolar radiation meter 31. More specifically, when thepump 2 stops and circulation of theheat medium 11 stops, thecontroller 32 restarts the operation of thepump 2 in accordance with the amount of direct solar radiation to restart circulation of theheat medium 11. - Hereinafter, the operation of the
controller 32 in the present embodiment will be described. - The
controller 32 continuously monitors the above temperature difference using thethermometers controller 32, for example. The first predetermined value is 0° C. or a value close to 0° C., for example. When the first predetermined value is 0° C., the comparison result between the temperature difference and the first predetermined value indicates whether the temperature of theheat medium 11 increases or decreases in theheat collector 1. - The
controller 32 continuously monitors the amount of direct solar radiation using the directsolar radiation meter 31 and periodically compares the amount of direct solar radiation with a predetermined value (a second predetermined value). Similarly to the first predetermined value, the second predetermined value is stored in the memory or storage of thecontroller 32, for example. The second predetermined value is 0 W/m2 or a value close to 0 W/m2, for example. - In the case where the
pump 2 operates and theheat medium 11 circulates in theheat collector 1, when temperature difference is larger than the first predetermined value, thecontroller 32 continues the operation of thepump 2. Thereby, circulation of theheat medium 11 in theheat collector 1 continues. On the other hand, in the case where thepump 2 operates and theheat medium 11 circulates in theheat collector 1, when the temperature difference becomes smaller than the first predetermined value, thecontroller 32 stops thepump 2. Thereby, circulation of theheat medium 11 in theheat collector 1 stops. When the temperature difference is equal to the first predetermined value, thecontroller 32 may continue circulation of theheat medium 11 or may stop circulation of theheat medium 11. - In this way, when the temperature difference becomes smaller than the first predetermined value, the
controller 32 stops thepump 2 to stop circulation of theheat medium 11 in theheat collector 1. The amount of collected heat by theheat collector 1 is generally proportional to the temperature difference. For this reason, at a time when the temperature difference is 0° C., the amount of collected heat is zero. Time t5 inFIGS. 2A and 2B is an example of such a time. When the predetermined value is 0 W/m2 in the first embodiment, thepump 2 stops at time t1 at which the amount of direct solar radiation becomes 0 W/m2. On the other hand, when the first predetermined value is 0° C. in the second embodiment, thepump 2 stops at time t5 at which the temperature difference becomes 0° C. and the amount of collected heat becomes zero. - In the case where the
pump 2 stops and circulation of theheat medium 11 stops, when the amount of direct solar radiation is smaller than second predetermined value, thecontroller 32 keeps thepump 2 stopped. Thereby, circulation of theheat medium 11 is kept stopped. On the other hand, in the case where thepump 2 stops and circulation of theheat medium 11 stops, when the amount of direct solar radiation becomes larger than the second predetermined value, thecontroller 32 restarts the operation of thepump 2. Thereby, circulation of theheat medium 11 in theheat collector 1 restarts. - In this way, in the present embodiment, the temperature difference is used for determination to stop the
pump 2 and the amount of direct solar radiation is used for determination to restart the operation of thepump 2. The reason for this is that when thepump 2 stops, the amount of collected heat from sunrays cannot be evaluated from the temperature difference. - As described above, in the preset embodiment, circulation of the
heat medium 11 in theheat collector 1 is controlled in accordance with the temperature difference between an entrance temperature and an exit temperature. Therefore, according to the present embodiment, as in the first embodiment, decrease in the amount of acquired energy in the solar heat collecting system caused by variation in the amount of collected heat by theheat collector 1 can be suppressed. - In the case shown in
FIGS. 20A and 20B , the amount of direct solar radiation inFIG. 20A becomes zero multiple times while the amount of collected heat inFIG. 20B is kept positive. In this case, thepump 2 stops at these times if the solar heat collecting system is that of the first embodiment. The stop and restart of thepump 2 are repeated at short intervals. If the stop and restart are repeated many times every day, the unfavorable serious deterioration of thepump 2 is caused. In contrast, in the solar heat collecting system of the second embodiment, thepump 2 does not stop even at these times. This is the advantage of the second embodiment. On the other hand, the first embodiment has an advantage that a time lag (for example, a time lag between time t1 and time t3) until the amount of direct solar radiation influences the temperature difference can be prevented from having an influence on control of circulation of theheat medium 11. -
FIG. 4 is a schematic view showing a configuration of a solar heat collecting system of a third embodiment. - The solar heat collecting system in
FIG. 4 includesthermometers FIG. 3 . However, inFIG. 4 , illustration of the directsolar radiation meter 31, thepump 2, the on-offvalve 5, the heat utilizingfluid flow path 6, theheat storage tank 7 and the on-offvalve 8 is omitted. - The
heat collector 1 in the present embodiment includes first to third heat collecting modules (heat collecting units) 1 a to 1 c. The firstheat collecting module 1 a and the secondheat collecting module 1 b are arranged in parallel with each other with respect to theheat medium 11. The thirdheat collecting module 1 c is arranged in series with the first and secondheat collecting modules heat medium 11. Each of the first to thirdheat collecting modules 1 a to 1 c in the present embodiment has a same structure as theheat collector 1 illustrated inFIGS. 12 and 13 . - The first to third
heat collecting modules 1 a to 1 c are connected with one another via the heatmedium flow path 3. The heatmedium flow path 3 includes afirst flow path 3 a provided with the firstheat collecting module 1 a, asecond flow path 3 b provided with the secondheat collecting module 1 b, and athird flow path 3 c provided with the thirdheat collecting module 1 c. The heatmedium flow path 3 braches off into the first andsecond flow paths second flow paths third flow path 3 c. - The
thermometer 35 is arranged on thefirst flow path 3 a in the vicinity of the exit of the firstheat collecting module 1 a and measures the temperature (a first exit temperature) of theheat medium 11 at the exit of the firstheat collecting module 1 a. Thethermometer 35 transmits the measurement result of the first exit temperature to thecontroller 32. The temperature (a first entrance temperature) of theheat medium 11 at the entrance of theheat collecting module 1 a is measured by thethermometer 33. The first entrance temperature corresponds to the entrance temperature of theheat collector 1. - The
thermometer 36 is arranged on thethird flow path 3 c in the vicinity of the entrance of the third heat collecting module is and measures the temperature (a third entrance temperature) of theheat medium 11 at the entrance of the thirdheat collecting module 1 c. Thethermometer 36 transmits the measurement result of the third entrance temperature to thecontroller 32. The temperature (a third exit temperature) of theheat medium 11 at the exit of the thirdheat collecting module 1 c is measured by thethermometer 34. The third exit temperature corresponds to the exit temperature of theheat collector 1. - The
controller 32 controls circulation of theheat medium 11 in theheat collector 1 in accordance with the temperature difference between the entrance temperature received from thethermometer 33 and the exit temperature received from thethermometer 34. More specifically, when thepump 2 operates and theheat medium 11 circulates in theheat collector 1, thecontroller 32 stops thepump 2 in accordance with this temperature difference to stop circulation of theheat medium 11. - In another embodiment, the
controller 32 controls circulation of theheat medium 11 in theheat collector 1 in accordance with the temperature difference between the first entrance temperature from thethermometer 33 and the first exit temperature from thethermometer 35. In still another embodiment, thecontroller 32 controls circulation of theheat medium 11 in theheat collector 1 in accordance with the temperature difference between the third entrance temperature from thethermometer 36 and the third exit temperature from thethermometer 34. In these cases, a method of calculating the temperature difference and a method of setting the first predetermined value may be same as that used when the entrance temperature from thethermometer 33 and the exit temperature from thethermometer 34 are used. - The
controller 32 controls circulation of theheat medium 11 in theheat collector 1 in accordance with the amount of direct solar radiation received from the directsolar radiation meter 31. More specifically, when thepump 2 stops and circulation of theheat medium 11 stops, thecontroller 32 restarts the operation of thepump 2 in accordance with the amount of direct solar radiation to restart circulation of theheat medium 11. - According to the present embodiment, as in the first and second embodiments, decrease in the amount of acquired energy in the solar heat collecting system can be suppressed.
- The number of the
heat collecting modules 1 a to is in theheat collector 1 inFIG. 4 is three. However, the number may be two, four or more. - A solar heat collecting system of a fourth embodiment has a configuration illustrated in
FIG. 4 . - When the
pump 2 operates and theheat medium 11 circulates in theheat collector 1, thecontroller 32 in the present embodiment stops circulation of theheat medium 11 in accordance with the temperature difference between the entrance temperature received from thethermometer 33 and the exit temperature received from thethermometer 34. The exit temperature from thethermometer 34 may be replaced with the first exit temperature from thethermometer 35. Similarly, the entrance temperature from thethermometer 33 may be replaced with the third entrance temperature from thethermometer 36. Furthermore, when thepump 2 stops and circulation of theheat medium 11 in theheat collector 1 stops, thecontroller 32 in the present embodiment restarts circulation of theheat medium 11 in accordance with the amount of direct solar radiation from the directsolar radiation meter 31. The above operations are same as those in the third embodiment. - However, when the
heat medium 11 circulates in theheat collector 1, thecontroller 32 in the present embodiment continues the operation of thepump 2 as long as a time period in which the temperature difference is smaller than the first predetermined value shorter than predetermined time. On the other hand, when theheat medium 11 circulates in theheat collector 1 and a time period in which the temperature difference is smaller than the first predetermined value lasts longer than the predetermined time, thecontroller 32 stops thepump 2. Thereby, circulation of theheat medium 11 in theheat collector 1 stops. When a time period in which the temperature difference is smaller than the first predetermined value lasts for the predetermined time, thecontroller 32 may continue circulation of theheat medium 11 or may stop circulation of theheat medium 11. The predetermined time is stored in the memory or storage of theheat controller 32, for example, similarly to in the first and second predetermined values. -
FIGS. 5A and 5B are graphs showing an example of the amount of direct solar radiation and the amount of acquired heat in the solar heat collecting system of the fourth embodiment.FIG. 5A shows an example of change in the amount of direct solar radiation measured by the directsolar radiation meter 31 with time.FIG. 5B shows change in the amount of acquired heat by theheat collector 1 with time with respect to the amount of direct solar radiation inFIG. 5A . - In
FIG. 5B , since the temperature difference becomes 0° C. at time t5, the amount of acquired heat becomes zero at time t5. Furthermore, inFIG. 5B , since the temperature difference is kept below 0° C. after time t5, the amount of acquired heat is kept negative after time t5. Accordingly, when the first predetermined value is 0° C. and a time period in which the temperature difference is smaller than 0° C. lasts longer than predetermined time after time t5, thepump 2 stops. Time t6 inFIG. 5B represents a time at which a time period in which the temperature difference is smaller than 0° C. reaches the predetermined time. As a result, the amount of acquired heat inFIG. 5B increases at time t6. Thereafter, thepump 2 is kept stopped until time t3. The amount of acquired heat inFIG. 5B represents an amount of heat transferred to the exit of theheat collector 1 based on the assumption that theheat medium 11 in theheat collector 1 circulates. - According to the present embodiment, as in the first to third embodiments, decrease in the amount of acquired energy in the solar heat collecting system can be suppressed.
- In the first embodiment, when the amount of direct solar radiation becomes zero and a positive value repeatedly as shown in
FIG. 19A , the stop and restart of thepump 2 are repeated multiple times. Similarly, in the second and third embodiments, when the temperature difference becomes a positive value and a negative value repeatedly, the stop and restart of thepump 2 are repeated multiple times. This is generally undesirable for thepump 2. In contrast, in the present embodiment, even when the temperature difference becomes a positive value and a negative value repeatedly, it can be avoided that the stop and restart of thepump 2 are repeated multiple times. - A solar heat collecting system of a fifth embodiment has a configuration illustrated in
FIG. 4 . - When the
pump 2 operates and theheat medium 11 circulates in theheat collector 1, thecontroller 32 in the present embodiment stops circulation of theheat medium 11 in accordance with the temperature difference between the entrance temperature received from thethermometer 33 and the exit temperature received from thethermometer 34. The exit temperature from thethermometer 34 may be replaced with the first exit temperature from thethermometer 35. Similarly, the entrance temperature from thethermometer 33 may be replaced with the third entrance temperature from thethermometer 36. Furthermore, when thepump 2 stops and circulation of theheat medium 11 stops, thecontroller 32 in the present embodiment restarts circulation of theheat medium 11 in accordance with the amount of direct solar radiation from the directsolar radiation meter 31. The above operations are same as those in the third and fourth embodiments. - However, during stop of circulation of the
heat medium 11, thecontroller 32 in the present embodiment keeps thepump 2 stopped as long as a time period in which the amount of direct solar radiation is larger than the second predetermined value is shorter than predetermined time. On the other hand, when circulation of theheat medium 11 stops and a time period in which the amount of direct solar radiation is larger than the second predetermined value lasts longer than the predetermined time, thecontroller 32 restarts the operation of thepump 2. Thereby, circulation of theheat medium 11 in theheat collector 1 restarts. When a time period in which the amount of direct solar radiation is larger than the second predetermined value lasts for the predetermined time, thecontroller 32 may keep circulation of theheat medium 11 stopped or may restart circulation of theheat medium 11. Similarly to the first and second predetermined values, the predetermined time is stored in the memory or storage of thecontroller 32, for example. - When the method of stopping circulation in the fourth embodiment and the method of restarting circulation in the fifth embodiment are combined, the value of the predetermined time for restarting circulation may be same as or may be different from the predetermined time for stopping circulation. The method of restarting circulation in the fifth embodiment can be combined with the method of stopping circulation in the first or second embodiment.
- According to the present embodiment, as in the first to fourth embodiments, decrease in the amount of acquired energy in the solar heat collecting system can be suppressed. Furthermore, according to the present embodiment, even when the amount of direct solar radiation becomes zero and a positive value repeatedly, it can be avoided that stop and restart of the
pump 2 are repeated many times. -
FIG. 6 is a schematic view showing a configuration of a solar heat collecting system of a sixth embodiment. - The solar heat collecting system in
FIG. 6 has a configuration that is obtained by eliminating the thirdheat collecting module 1 c, thethird flow path 3 c, and thethermometers FIG. 4 and adding athermometer 37 and on-offvalves heat collecting module 1 a and the secondheat collecting module 1 b are arranged in parallel with each other with respect to theheat medium 11. - The
thermometer 37 is arranged on thefirst flow path 3 a in the vicinity of the entrance of the firstheat collecting module 1 a and measures the temperature (the first entrance temperature) of theheat medium 11 at the entrance of the firstheat collecting module 1 a. Thethermometer 37 transmits the measurement result of the first entrance temperature to thecontroller 32. - The
thermometer 35 is arranged on thefirst flow path 3 a in the vicinity of the exit of the firstheat collecting module 1 a and measures the temperature (the first exit temperature) of theheat medium 11 at the exit of the firstheat collecting module 1 a. Thethermometer 35 transmits the measurement result of the first exit temperature to thecontroller 32. - The on-off
valve 41 is arranged on thesecond flow path 3 b upstream of the entrance of the secondheat collecting module 1 b. The on-offvalve 42 is arranged on thesecond flow path 3 b downstream of the exit of the secondheat collecting module 1 b. In the present embodiment, the on-offvalves controller 32. When the on-offvalves pump 2, theheat medium 11 circulates in the secondheat collecting module 1 b. When the on-offvalves pump 2, circulation of theheat medium 11 in the secondheat collecting module 1 b stops. In this way, while the operation and stop of thepump 2 can be used to control circulation of theheat medium 11 in theentire heat collector 1, opening/closing of the on-offvalves heat medium 11 in a part of theheat collector 1. - The
controller 32 controls circulation of theheat medium 11 in theheat collector 1 in accordance with the temperature difference between the first entrance temperature from thethermometer 37 and the first exit temperature from thethermometer 35. More specifically, in the case where thepump 2 operates and theheat medium 11 circulates in theheat collector 1, when the temperature difference is larger than the predetermined value, thecontroller 32 keeps the on-offvalves pump 2 operates, when the temperature difference becomes smaller than the predetermined value, thecontroller 32 fully closes the on-offvalves heat medium 11 in the firstheat collecting module 1 a is kept while circulation of theheat medium 11 in the secondheat collecting module 1 b stops. Accordingly, the amount of radiation from theheat collector 1 is reduced. - In this case, the
controller 32 closes the on-offvalves pump 2. As a result, the flow rate of theheat medium 11 in theheat collector 1 after the on-offvalves valves heat collector 1 is further reduced. This is also true in seventh and eighth embodiment, which will be described later. The firstheat collecting module 1 a is an example of the first portion. The secondheat collecting module 1 b is an example of the second portion. - In the case where the on-off
valves heat medium 11 in the secondheat collecting module 1 b stops, when the temperature difference is smaller than the predetermined value, thecontroller 32 keeps the on-offvalve valves controller 32 opens the on-offvalves heat medium 11 in the secondheat collecting module 1 b restarts so that theheat medium 11 circulates in the first and secondheat collecting modules - In this case, the
controller 32 opens the on-offvalves pump 2. For example, thecontroller 32 returns the flow rate in thepump 2 to a value before the on-offvalves heat medium 11 in theheat collector 1 after the on-offvalves valves - As described above, in the present embodiment, stop and restart of circulation of the
heat medium 11 in a part of theheat collector 1 and the flow rate of theheat medium 11 in theheat collector 1 are controlled in accordance with the temperature difference between the entrance temperature and the exit temperature. Accordingly, power consumption in thepump 2 can be reduced, and the amount of radiation can be also reduced. If the solar heat collecting system inFIG. 6 does not include the directsolar radiation meter 31 and circulation of theheat medium 11 in both the first and secondheat collecting modules heat medium 11. However, in the present embodiment, the temperature difference that is obtained by using thethermometers FIG. 6 does not include the directsolar radiation meter 31, power consumption in thepump 2 can be reduced. Furthermore, even if the flow rate in thepump 2 is not reduced, the amount of radiation from the firstheat collecting module 1 a can be reduced. Therefore, according to the present embodiment, decrease in the amount of acquired energy in the solar heat collecting system caused by variation in the amount of collected heat by theheat collector 1 can be suppressed. - According to the present embodiment, restart of circulation of the
heat medium 11 can be controlled in accordance with temperatures so that the directsolar radiation meter 31 can be omitted. - Depending on the starting characteristic of the solar heat collecting system, circulation of the
heat medium 11 is desired to be kept for the entire system in some cases. In this case, to reduce power consumption in thepump 2, it suffices that circulation of theheat medium 11 stops only in a part of the system. Even if the flow rate in thepump 2 is not reduced, it is possible to decrease the amount of radiation from the second heat collecting module 11 b in which circulation of theheat medium 11 stops. - The number of the
heat collecting modules heat collector 1 inFIG. 6 are two, but may be three or more. In this case, valves similar to the on-offvalves controller 32 can control stop and restart of circulation of theheat medium 11 in the two or more heat collecting modules. - A solar heat collecting system of the seventh embodiment has the configuration illustrated in
FIG. 6 . - The
controller 32 in the present embodiment controls circulation of theheat medium 11 in theheat collector 1 in accordance with the temperature difference between the first entrance temperature from thethermometer 37 and the first exit temperature from thethermometer 35. More specifically, when thepump 2 operates and theheat medium 11 circulates in theheat collector 1, thecontroller 32 keeps the on-offvalves pump 2 operates and a time in which the temperature difference is smaller than the predetermined value lasts longer than the predetermined time, thecontroller 32 fully closes the on-offvalves heat medium 11 in the firstheat collecting module 1 a is kept, circulation of theheat medium 11 in the secondheat collecting module 1 b stops. - When the on-off
valves heat medium 11 in the secondheat collecting module 1 b stops, thecontroller 32 keeps the on-offvalves valves controller 32 opens the on-offvalves heat medium 11 in the secondheat collecting module 1 b restarts and theheat medium 11 circulates in the first and secondheat collecting modules - According to the present embodiment, as in the sixth embodiment, decrease in the amount of acquired energy in the solar heat collecting system can be suppressed. Furthermore, according to the present embodiment, restart of circulation of the
heat medium 11 can be controlled in accordance with temperatures so that the directsolar radiation meter 31 can be omitted. - In the case shown in
FIGS. 20A and 20B , the amount of direct solar radiation inFIG. 20A becomes zero multiple times while the amount of collected heat inFIG. 20B is kept positive. - In this case, the
pump 2 stops at these times if the solar heat collecting system is that of the first embodiment. However, in the seventh embodiment, the operation and stop of thepump 2 is replaced with opening and closing of the on-offvalves valves - Opening and closing of the on-off
valves valves valves - A solar heat collecting system of an eighth embodiment has the configuration illustrated in
FIG. 6 . - The
controller 32 in the present embodiment controls circulation of theheat medium 11 in theheat collector 1 in accordance with the amount of direct solar radiation from the directsolar radiation meter 31. More specifically, when thepump 2 operates and theheat medium 11 circulates in theheat collector 1, thecontroller 32 keeps the on-offvalves pump 2 operates and a time in which the amount of direct solar radiation is smaller than the predetermined value is longer than the predetermined time, thecontroller 32 fully closes the on-offvalves heat medium 11 in the firstheat collecting module 1 a is kept, circulation of theheat medium 11 in the secondheat collecting module 1 b stops. - When the on-off
valves heat medium 11 in theheat collecting module 1 b stops, thecontroller 32 keeps the on-offvalves valves controller 32 opens the on-offvalves heat medium 11 in the secondheat collecting module 1 b restarts and theheat medium 11 circulates in the first and secondheat collecting modules - According to the present embodiment, as in the sixth and seventh embodiments, decrease in the amount of acquired energy in the solar heat collecting system can be suppressed. In the present embodiment, instead of comparing a time in which the amount of direct solar radiation is smaller or larger than the predetermined value with the predetermined time, the amount of direct solar radiation and the predetermined value may be compared to control circulation of the
heat medium 11. - Depending on the starting characteristic of the solar heat collecting system, circulation of the
heat medium 11 is desired to be kept for the entire system in some cases. In this case, to reduce power consumption in thepump 2, it suffices that circulation of theheat medium 11 stops only in a part of the system. Even if the flow rate in thepump 2 is not reduced, it is possible to decrease the amount of radiation from the secondheat collecting module 1 b in which circulation of theheat medium 11 stops. - In the case shown in
FIGS. 20A and 20B , the amount of direct solar radiation inFIG. 20A becomes zero multiple times while the amount of collected heat inFIG. 20B is kept positive. In this case, thepump 2 stops at these timings if the solar heat collecting system is that of the first embodiment. However, in the eighth embodiment, the operation and stop of thepump 2 is replaced with opening and closing of the on-offvalves valves valves valves valves -
FIG. 7 is a schematic view showing a configuration of a solar heat collecting system of a ninth embodiment. - The solar heat collecting system in
FIG. 7 has a configuration that is obtained by eliminating the secondheat collecting module 1 b and thethermometers FIG. 4 and adding on-offvalves 41 to 44 thereto. The firstheat collecting module 1 a and the thirdheat collecting module 1 c are arranged in series with respect to theheat medium 11. Thesecond flow path 3 b in the present embodiment can be used as a bypass flow path in which theheat medium 11 flows to bypass the firstheat collecting module 1 a. - The on-off
valve 41 is arranged in the vicinity of the entrance of thesecond flow path 3 b. The on-offvalve 42 is arranged in the vicinity of the exit of thesecond flow path 3 b. The on-offvalve 43 is arranged on thefirst flow path 3 a upstream of the entrance of the firstheat collecting module 1 a. The on-offvalve 44 is arranged on thefirst flow path 3 a downstream of the exit of the firstheat collecting module 1 a. The on-offvalves 41 to 44 are opened/closed under control by thecontroller 32. - When the on-off
valves valves pump 2, theheat medium 11 circulates in the first and thirdheat collecting modules valves valves pump 2, circulation of theheat medium 11 in the firstheat collecting module 1 a stops and theheat medium 11 circulates only in the thirdheat collecting module 1 c. At this time, theheat medium 11 bypasses the firstheat collecting module 1 a to circulate in thesecond flow path 3 c. In this way, while the operation and stop of thepump 2 can be used to control circulation of theheat medium 11 in theentire heat collector 1, opening/closing of the on-offvalves 41 to 44 can be used to control circulation of theheat medium 11 in a part of theheat collector 1. - The
controller 32 controls circulation of theheat medium 11 in theheat collector 1 in accordance with the temperature difference between the third entrance temperature from thethermometer 36 and the third exit temperature from thethermometer 34. More specifically, in the case where thepump 2 operates and theheat medium 11 circulates in theheat collector 1, when the temperature difference is larger than the predetermined value, thecontroller 32 keeps the on-offvalves valves pump 2 operates, when the temperature difference becomes smaller than the predetermined value, thecontroller 32 opens the on-offvalves valves heat medium 11 in the thirdheat collecting module 1 c is kept, circulation of theheat medium 11 in the firstheat collecting module 1 a stops so that the amount of radiation from theheat collector 1 is reduced. - In this case, the
controller 32 closes the on-offvalves pump 2. As a result, the flow rate of theheat medium 11 in theheat collector 1 after the on-offvalves valves heat collector 1 is further reduced. This is also true in tenth and eleventh embodiments, which will be described later. The thirdheat collecting module 1 c is an example of the first portion. The firstheat collecting module 1 a is an example of the second portion. - In the case where the on-off
valves heat medium 11 in the firstheat collecting module 1 a stops, when the temperature difference is smaller than the predetermined value, thecontroller 32 keeps the on-offvalves valves valves controller 32 fully closes the on-offvalves valves heat medium 11 in the firstheat collecting module 1 a restarts and theheat medium 11 circulates in the first and thirdheat collecting modules valves second flow path 3 b is released. - In this case, the
controller 32 opens the on-offvalves pump 2. For example, the flow rate in thepump 2 is returned to a value before the on-offvalves heat medium 11 in theheat collector 1 after the on-offvalves valves - As described above, in the present embodiment, stop and restart of circulation of the
heat medium 11 in a part of theheat collector 1 and the flow rate of theheat medium 11 in theheat collector 1 are controlled in accordance with the temperature difference between the entrance temperature and the exit temperature. Therefore, according to the present embodiment, decrease in the amount of acquired energy in the solar heat collecting system caused by variation in the amount of collected heat by theheat collector 1 can be suppressed. - According to the present embodiment, restart of circulation of the
heat medium 11 can be controlled in accordance with temperatures so that the directsolar radiation meter 31 can be omitted. - The number of the
heat collecting modules 1 a and is inFIG. 7 are two, but may be three or more. In this case, valves similar to the on-offvalves - Thereby, the
controller 32 can control stop and restart of circulation of theheat medium 11 in the two or more heat collecting modules. - Depending on the starting characteristic of the solar heat collecting system, circulation of the
heat medium 11 is desired to be kept for the entire system in some cases. In this case, to reduce power consumption in thepump 2, it suffices that circulation of theheat medium 11 stops only in a part of the system. Even if the flow rate in thepump 2 is not reduced, it is possible to decrease the amount of radiation from the firstheat collecting module 1 a in which circulation of theheat medium 11 stops. - A solar heat collecting system of a tenth embodiment has the configuration illustrated in
FIG. 7 . Thecontroller 32 in the present embodiment controls circulation of theheat medium 11 in theheat collector 1 in accordance with the temperature difference between the third entrance temperature from thethermometer 36 and the third exit temperature from thethermometer 34. More specifically, when thepump 2 operates and theheat medium 11 circulates in theheat collector 1, thecontroller 32 keeps the on-offvalves valves pump 2 operates and a time in which the temperature difference is smaller than the predetermined value lasts longer than the predetermined time, thecontroller 32 opens the on-offvalves valves heat medium 11 in the thirdheat collecting module 1 c is kept, circulation of theheat medium 11 in the firstheat collecting module 1 a stops. - When the on-off
valves heat medium 11 in the firstheat collecting module 1 a stops, thecontroller 32 keeps the on-offvalves valves valves controller 32 fully closes the on-offvalves valves heat medium 11 in the firstheat collecting module 1 a restarts and theheat medium 11 circulates in the first and thirdheat collecting modules valves second flow path 3 b is released. - According to the present embodiment, as in the ninth embodiment, decrease in the amount of acquired energy in the solar heat collecting system can be suppressed. Furthermore, according to the present embodiment, restart of circulation of the
heat medium 11 can be controlled in accordance with temperatures so that the directsolar radiation meter 31 can be omitted. - Depending on the starting characteristic of the solar heat collecting system, circulation of the
heat medium 11 is desired to be kept for the entire system in some cases. In this case, to reduce power consumption in thepump 2, it suffices that circulation of theheat medium 11 stops only in a part of the system. Even if the flow rate in thepump 2 is not reduced, it is possible to decrease the amount of radiation from the first heat collecting module 11 a in which circulation of theheat medium 11 stops. - In the case shown in
FIGS. 20A and 20B , the amount of direct solar radiation inFIG. 20A becomes zero multiple times while the amount of collected heat inFIG. 20B is kept positive. In this case, thepump 2 stops at these times if the solar heat collecting system is that of the first embodiment. However, in the tenth embodiment, the operation and stop of thepump 2 is replaced with opening and closing of the on-offvalves 41 to 44 and the on-offvalves valves 41 to 44 are repeated at short intervals. If such opening and closing are repeated many times every day, the unfavorable serious deterioration of the on-offvalves 41 to 44 is caused. In contrast, in the solar heat collecting system of the tenth embodiment, the on-offvalves - A solar heat collecting system of an eleventh embodiment has the configuration illustrated in
FIG. 7 . - The
controller 32 in the present embodiment controls circulation of theheat medium 11 in theheat collector 1 in accordance with the amount of direct solar radiation from the directsolar radiation meter 31. More specifically, when thepump 2 operates and theheat medium 11 circulates in theheat collector 1, thecontroller 32 keeps the on-offvalves valves pump 2 operates and a time period in which the amount of direct solar radiation is smaller than the predetermined value lasts longer than the predetermined time, thecontroller 32 opens the on-offvalves valves heat medium 11 in the thirdheat collecting module 1 c is kept, circulation of theheat medium 11 in the firstheat collecting module 1 a stops. - When the on-off
valves heat medium 11 in the firstheat collecting module 1 a stops, thecontroller 32 keeps the on-offvalves valves valves controller 32 fully closes the on-offvalves valves heat medium 11 in the firstheat collecting module 1 a restarts and theheat medium 11 circulates in the first and thirdheat collecting modules valves second flow path 3 b is released. - According to the present embodiment, as in the ninth and tenth embodiments, decrease in the amount of acquired energy in the solar heat collecting system can be suppressed. In the present embodiment, instead of comparing a time in which the amount of direct solar radiation is smaller or larger than the predetermined value with the predetermined time, the amount of direct solar radiation and the predetermined value may be compared to control circulation of the
heat medium 11. - Depending on the starting characteristic of the solar heat collecting system, circulation of the
heat medium 11 is desired to be kept for the entire system in some cases. In this case, to reduce power consumption in thepump 2, it suffices that circulation of theheat medium 11 stops only in a part of the system. Even if the flow rate in thepump 2 is not reduced, it is possible to decrease the amount of radiation from the firstheat collecting module 1 a in which circulation of theheat medium 11 stops. - In the case shown in
FIGS. 20A and 20B , the amount of direct solar radiation inFIG. 20A becomes zero multiple times while the amount of collected heat inFIG. 20B is kept positive. In this case, thepump 2 stops at these times if the solar heat collecting system is that of the first embodiment. However, in the eleventh embodiment, the operation and stop of thepump 2 is replaced with opening and closing of the on-offvalves 41 to 44 and the on-offvalves valves 41 to 44 are repeated at short intervals. If such opening and closing are repeated many times every day, the unfavorable serious deterioration of the on-offvalves 41 to 44 is caused. In contrast, in the solar heat collecting system of the eleventh embodiment, the on-offvalves - The operation of the
heat collector 1 in a twelfth embodiment will be described with reference toFIG. 13 . Theheat collector 1 in the present embodiment is installed in the solar heat collecting system of any one of the first to eleventh embodiments. This is also true for theheat collector 1 in thirteenth to fifteenth embodiments, which will be described later. - When the
heat medium 11 circulates in theheat collector 1, theheat collector 1 in the present embodiment operates to condense sunrays to theheat collecting pipe 22, as illustrated inFIG. 13 . Also when circulation of theheat medium 11 stops in all or part of theentire heat collector 1, theheat collector 1 in the present embodiment operates to condense sunrays to theheat collecting pipe 22. That is, the reflecting mirrors 21 in the present embodiment continues to rotate to adjust the focal point of sunrays to theheat collecting pipe 22 both when theheat medium 11 circulates and when circulation of theheat medium 11 stops. Theheat collector 1 rotates the reflectingmirror 21 to track the altitude of the sun. Accordingly, sunrays can be condensed to theheat collecting pipe 22. - According to the present embodiment, even when circulation of the
heat medium 11 stops, theheat collector 1 continues to condense lights. Consequently, when circulation of theheat medium 11 restarts, theheat collector 1 can restart to collect heat immediately. - When the
heat collector 1 in the twelfth embodiment includes a plurality of heat collecting modules as inFIGS. 4, 6 and 7 , control of rotation of the reflectingmirror 21 that has been described in the twelfth embodiment can be performed for each heat collecting module. -
FIG. 8 is a sectional view for explaining the operation of theheat collector 1 of a thirteenth embodiment. - When the
heat medium 11 circulates in theheat collector 1, theheat collector 1 in the present embodiment operates to condense sunrays to the heat collecting pipe 22 (seeFIG. 13 ). However, when circulation of theheat medium 11 stops in all or part of theheat collector 1, theheat collector 1 in the present embodiment operates not to condense sunrays to theheat collecting pipe 22, as illustrated inFIG. 8 . That is, circulation of theheat medium 11 stops, the reflectingmirror 21 in the present embodiment is rotated and moved to a position not to adjust the focal point of sunrays to theheat collecting pipe 22. When circulation of theheat medium 11 in theheat collector 1 restarts, theheat collector 1 in the present embodiment operates to restart condensation of sunrays to theheat collecting pipe 22. - According to the present embodiment, condensation of lights by the
heat collector 1 is stopped during stop of circulation of theheat medium 11 so that deterioration of theheat medium 11 in theheat collecting pipe 22 caused by a high temperature can be prevented. When the sun suddenly appears from a cloud, the amount of direct solar radiation is sufficient but the flow rate in thepump 2 may be sufficiently low or zero depending on the starting characteristic of thepump 2. At that time, when the focal point of sunrays is adjusted to theheat collecting pipe 22, the temperature of theheat medium 11 becomes locally high and theheat medium 11 in this local area is deteriorated. However, when the focal point of sunrays is not adjusted to theheat collecting pipe 22 as in the present embodiment, such deterioration can be prevented. The operation of the present embodiment is efficient, for example, when the flow rate of theheat medium 11 is zero or low during stop of circulation of theheat medium 11 or after restart of circulation of theheat medium 11. - When the
heat collector 1 in the thirteenth embodiment includes a plurality of heat collecting modules as inFIGS. 4, 6 and 7 , control of rotation of the reflectingmirror 21 that has been described in the thirteenth embodiment can be performed for each heat collecting module. -
FIG. 9 is a sectional view for explaining the operation of theheat collector 1 of a fourteenth embodiment. - When circulation of the
heat medium 11 stops in all or part of theheat collector 1, theheat collector 1 in the present embodiment turns the convex surface of the reflectingmirror 21 to the upstream side of a wind W and moves the reflectingmirror 21 to the upstream side of the wind W upstream of theheat collecting pipe 22. InFIG. 9 , since the wind W blows in the -X direction, the convex surface of the reflectingmirror 21 is directed to the +X direction. When circulation of theheat medium 11 in theheat collector 1 restarts, theheat collector 1 in the present embodiment rotates the reflectingmirror 21 to restart condensation of sunrays to theheat collecting pipe 22. The reflectingmirror 21 is an example of a light condensing panel. Theheat collecting pipe 22 is an example of a portion where heat is collected by condensation of lights. - According to the present embodiment, the flow rate of the wind W (an air flow) blowing to the
heat collecting pipe 22 can be reduced by the reflectingmirror 21. Therefore, according to the present embodiment, the forced-convection heat transfer coefficient from theheat collecting pipe 22 to the air can be reduced and the amount of radiation from theheat collecting pipe 22 can be reduced. - When the
heat collector 1 in the fourteenth embodiment includes a plurality of heat collecting modules as inFIGS. 4, 6 and 7 , control of rotation of the reflectingmirror 21 that has been described in the fourteenth embodiment can be performed for each heat collecting module. -
FIG. 10 is a sectional view for explaining the operation of theheat collector 1 of a fifth embodiment. - When circulation of the
heat medium 11 stops in all or part of theheat collector 1, theheat collector 1 in the present embodiment turns the convex surface of the reflectingmirror 21 upward (to the +Z direction) and moves the reflectingmirror 21 to a position above theheat collecting pipe 22. When circulation of theheat medium 11 in theheat collector 1 restarts, theheat collector 1 in the present embodiment rotates the reflectingmirror 21 to restart condensation of sunrays to theheat collecting pipe 22. - When the wind W is sufficiently small, the amount of forced-convection heat transfer from the
heat collecting pipe 22 to the air is small. When the amount of natural-convection heat transfer from theheat collecting pipe 22 to the air is reduced, the amount of radiation from theheat collecting pipe 22 is reduced. - Accordingly, in the present embodiment, the convex surface of the reflecting
mirror 21 is turned upward to suppress the air flow directly above theheat collecting pipe 22. Therefore, according to the present embodiment, the amount of natural-convection heat transfer from theheat collecting pipe 22 to the air can be reduced and the amount of radiation from theheat collecting pipe 22 can be reduced. - When the
heat collector 1 in the fifteenth embodiment includes a plurality of heat collecting modules as inFIGS. 4, 6 and 7 , control of rotation of the reflectingmirror 21 that has been described in the fifteenth embodiment can be performed for each heat collecting module. - While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
Claims (15)
1. A solar heat collecting system comprising:
a heat collector configured to heat a heat medium by a sunray;
a heating device configured to heat a heat utilizing fluid by heat of the heat medium;
a heat medium flow path configured to circulate the heat medium between the heat collector and the heating device; and
a controller configured to control circulation of the heat medium in the heat collector in accordance with an amount of solar radiation of the sunray, or in accordance with a temperature difference between a first temperature of the heat medium at a first position and a second temperature of the heat medium at a second position located downstream of the first position with respect to the heat medium.
2. The system of claim 1 , wherein the controller stops the circulation of the heat medium in all or part of the heat collector in accordance with the amount of solar radiation or the temperature difference.
3. The system of claim 2 , wherein the controller stops the circulation of the heat medium in all or part of the heat collector, when the amount of solar radiation is smaller than a predetermined value, when a time period in which the amount of solar radiation is smaller than the predetermined value lasts longer than predetermined time, when the temperature difference is smaller than a predetermined value, or when a time period in which the temperature difference is smaller than the predetermined value lasts longer than predetermined time.
4. The system of claim 1 , wherein the controller restarts the circulation of the heat medium in accordance with the amount of solar radiation or the temperature difference, when the circulation of the heat medium in all or part of the heat collector stops.
5. The system of claim 4 , wherein the controller restarts the circulation of the heat medium in the heat collector during the stop of the circulation of the heat medium in all or part of the heat collector, when the amount of solar radiation is larger than a predetermined value, when a time period in which the amount of solar radiation is larger than the predetermined value lasts longer than predetermined time, when the temperature difference is larger than a predetermined value, or when a time period in which the temperature difference is larger than the predetermined value lasts longer than predetermined time.
6. The system of claim 1 , wherein
the heat collector includes a plurality of heat collecting modules, and
the controller controls the circulation of the heat medium in at least one of the heat collecting modules in accordance with the amount of solar radiation or the temperature difference.
7. The system of claim 6 , wherein
the heat collector includes heat collecting modules arranged in parallel with respect to the heat medium, and
the controller stops the circulation of the heat medium in the at least one of the heat collecting modules, when the amount of solar radiation is smaller than a predetermined value, when a time period in which the amount of solar radiation is smaller than the predetermined value lasts longer than predetermined time, when the temperature difference is smaller than a predetermined value, or when a time period in which the temperature difference is smaller than the predetermined value lasts longer than predetermined time.
8. The system of claim 6 , wherein
the heat collector includes heat collecting modules arranged in parallel with respect to the heat medium, and
the controller restarts the circulation of the heat medium in the at least one of the heat collecting modules during stop of the circulation of the heat medium in the at least one of the heat collecting modules, when the amount of solar radiation is larger than a predetermined value, when a time period in which the amount of solar radiation is larger than the predetermined value lasts longer than predetermined time, when the temperature difference is larger than a predetermined value, or when a time period in which the temperature difference is larger than the predetermined value lasts longer than predetermined time.
9. The system of claim 6 , wherein
the heat collector includes heat collecting modules arranged in serial with respect to the heat medium, and
the controller uses a bypass flow path in which the heat medium flows to bypass the at least one of the heat collecting modules, when the amount of solar radiation is smaller than a predetermined value, when a time period in which the amount of solar radiation is smaller than the predetermined value lasts longer than predetermined time, when the temperature difference is smaller than a predetermined value, or when a time period in which the temperature difference is smaller than the predetermined value lasts longer than predetermined time.
10. The system of claim 6 , wherein
the heat collector includes heat collecting modules arranged in serial with respect to the heat medium, and
the controller releases, during use of a bypass flow path in which the heat medium flows to bypass the at least one of the heat collecting modules, the use of the bypass flow path, when the amount of solar radiation is larger than a predetermined value, when a time period in which the amount of solar radiation is larger than the predetermined value lasts longer than predetermined time, when the temperature difference is larger than a predetermined value, or when a time period in which the temperature difference is larger than the predetermined value lasts longer than predetermined time.
11. The system of claim 1 , wherein
the heat collector includes first and second portions that circulate the heat medium, and
when the circulation of the heat medium in the first portion is to be kept and the circulation of the heat medium in the second portion is to be stopped, the controller reduces a flow rate of the heat medium in the heat collector after the stop of the circulation to be lower than a flow rate of the heat medium in the heat collector before the stop of the circulation.
12. The system of claim 1 , wherein the heat collector is configured to collect heat by condensing the sunray during stop of the circulation of the heat medium.
13. The system of claim 1 , wherein
the heat collector is configured to collect heat by condensing the sunray,
during stop of the circulation of the heat medium, the heat collector does not condense the sunray to a portion of the heat collector holding the stopped heat medium, and
after restart of the circulation of the heat medium, the heat collector restarts the condensation of the sunray.
14. The system of claim 1 , wherein
the heat collector includes a light condensing panel configured to track an altitude of the sun, and
during stop of the circulation of the heat medium, the heat collector moves the light condensing panel provided in a portion of the heat collector holding the stopped heat medium, to a position at an upstream side of wind from a portion at which heat is collected by condensation of light, and
after restart of the circulation of the heat medium, the heat collector moves the light condensing panel to a light condensing position.
15. The system of claim 1 , wherein
the heat collector includes a light condensing panel configured to track an altitude of the sun, and
during stop of the circulation of the heat medium, the heat collector moves the light condensing panel provided in a portion of the heat collector holding the stopped heat medium, to a position above a portion at which heat is collected by condensation of light, and
after restart of the circulation of the heat medium, the heat collector moves the light condensing panel to a light condensing position.
Applications Claiming Priority (2)
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JP2015056449A JP6548925B2 (en) | 2015-03-19 | 2015-03-19 | Solar heat collection system |
JP2015-056449 | 2015-03-19 |
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US20160273807A1 true US20160273807A1 (en) | 2016-09-22 |
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Family Applications (1)
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US15/008,604 Abandoned US20160273807A1 (en) | 2015-03-19 | 2016-01-28 | Solar heat collecting system |
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US (1) | US20160273807A1 (en) |
EP (1) | EP3093581B1 (en) |
JP (1) | JP6548925B2 (en) |
AU (1) | AU2016200464B2 (en) |
ES (1) | ES2871675T3 (en) |
Cited By (1)
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US20190148946A1 (en) * | 2017-11-13 | 2019-05-16 | Hitachi, Ltd. | Energy management system, and energy management method |
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CN110926041A (en) * | 2019-12-18 | 2020-03-27 | 珠海格力电器股份有限公司 | Hot water system and control method thereof |
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- 2016-01-27 ES ES16153030T patent/ES2871675T3/en active Active
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Also Published As
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JP2016176631A (en) | 2016-10-06 |
EP3093581B1 (en) | 2021-05-05 |
AU2016200464B2 (en) | 2018-02-01 |
JP6548925B2 (en) | 2019-07-24 |
EP3093581A1 (en) | 2016-11-16 |
AU2016200464A1 (en) | 2016-10-06 |
ES2871675T3 (en) | 2021-10-29 |
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