Closed solar thermal collection system

Abstract

To provide a closed-type solar heat collection system which can suppress the evaporation of a heat medium by a simple constitution, and can use a coagulation which is heated by the heat medium.SOLUTION: When a heat medium temperature T1 is equal to or lower than a medium prescribed temperature α, and a storage water temperature T2 is equal to or lower than a storage water prescribed temperature β, a control part 10 heats a heat medium by receiving sun light by making the sun light permeate by a light control film 3 by bringing about an application state that a voltage from a power supply 11 is applied to the light control film, and on the other hand, when the measured heat medium temperature T1 is higher than the medium prescribed temperature α, or when the measured storage water temperature T2 is higher than the storage water prescribed temperature β, the control part does not heat the heat medium by a heat collector by reducing a permeation amount of the sun light by using the light control film more than that in the application state by bringing about a non-application state that the voltage from the power supply 11 is not applied to the light control film 3.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a closed solar thermal collection system. [Background technology]

[0002] A closed solar thermal collection system receives sunlight and heats a heat medium, and then receives heat from the heated heat medium to heat stored water, which is then used in a bath or the like at home (see, for example, Patent Document 1).

[0003] If the heat transfer medium continues to be heated by sunlight and exceeds its boiling point, the heat transfer medium may vaporize, causing the pressure inside the system to rise, which may exert a large force on each component of the system. Furthermore, the heat transfer medium may deteriorate due to the vaporization of the heat transfer medium. Furthermore, if the vaporized heat transfer medium is released from the system to prevent the pressure inside the system from rising, the capacity of the heat transfer medium inside the system will decrease, requiring the system to be replenished with heat transfer medium.

[0004] Therefore, some conventional closed solar heat collecting systems are provided with a pressure sensor that detects the pressure inside the system and a cooling device or radiator that cools the heat medium.

[0005] When the pressure sensor detects an increase in pressure inside the system, the control unit sends the heat medium to a cooling device or radiator, and cools the heat medium in the cooling device or radiator, thereby preventing the heat medium from evaporating. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 60-207855 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in a closed solar heat collection system, if a cooling device or a radiator for cooling the heat medium is provided to suppress evaporation of the heat medium, there is a problem that the system becomes complicated.

[0008] The present invention has been made in consideration of the above circumstances, and aims to provide a closed solar thermal collection system that can suppress evaporation of the heat transfer medium with a simple configuration and can utilize storage heated by the heat transfer medium. [Means for solving the problem]

[0009] In order to solve the above problems, the closed solar heat collecting system of the present invention includes a heat collector having a heat collection tube that temporarily stores a heat medium and receives sunlight to heat the heat medium stored in the heat collection tube, a light control film that is provided on the heat collector and intervenes between the sun and the heat collection tube and changes the amount of sunlight transmitted in response to application of voltage from a power source, a tank that stores stored water and has a heat exchanger that receives heat from the heat medium heated in the heat collector and heats the stored water, a pump that circulates the heat medium between the heat collector and the heat exchanger, a first temperature sensor that measures the temperature of the heat medium in the heat collector, and The device is equipped with a second temperature sensor that measures the temperature of the stored water in the tank, and a control unit that controls the driving and stopping of the pump and controls the voltage applied to the light control film based on the detection results of the first temperature sensor and the second temperature sensor, and when the measured heat medium temperature is equal to or lower than a predetermined medium temperature and the measured stored water temperature is equal to or lower than a predetermined stored water temperature, the control unit applies a voltage from the power source to the light control film, thereby transmitting the sunlight through the light control film and receiving the sunlight to heat the heat medium, and when the measured heat medium temperature is The aforementioned If the temperature of the medium is greater than the predetermined temperature, or if the measured temperature of the stored water is The aforementioned When the temperature of the stored water is higher than a predetermined temperature, the light-control film is placed in a non-voltage state where no voltage is applied from the power source, thereby reducing the amount of sunlight transmitted through the light-control film compared to when voltage is applied, and the heat medium is not heated in the solar collector. [Effects of the Invention]

[0010] The closed solar heat collecting system according to this embodiment has the above-described configuration, and therefore can suppress evaporation of the heat medium with a simple configuration, and can utilize stored water heated by the heat medium. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram that schematically shows the configuration of a closed solar heat collecting system according to this embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view of a heat collector provided in the closed solar heat collecting system according to this embodiment. [Figure 3] FIG. 3 is a cross-sectional view of the heat collector. [Figure 4] FIG. 4 is a schematic cross-sectional view of a light control film provided in the closed solar heat collecting system according to this embodiment. [Figure 5] FIG. 5 is a flow diagram of the closed solar heat collecting system according to this embodiment. [Figure 6] FIG. 6 is an explanatory diagram showing the predetermined medium temperature α, the predetermined stored water temperature β, and the predetermined temperature difference γ in a closed solar heat collecting system according to a modified example.

[0012] Hereinafter, an embodiment of a closed solar heat collecting system according to the present invention will be described with reference to the drawings. Note that the present invention is not limited to this embodiment. Furthermore, the components in the following embodiments include those that can be easily imagined by a person skilled in the art or those that are substantially the same. DETAILED DESCRIPTION OF THE INVENTION

[0013] [Embodiment] Fig. 1 is a block diagram showing a schematic configuration of a closed solar thermal heat collecting system 1 according to this embodiment. Fig. 2 is a schematic cross-sectional view of a heat collector 2 provided in the closed solar thermal heat collecting system 1 according to this embodiment. Fig. 3 is a cross-sectional view of the heat collector 2. Fig. 4 is a schematic cross-sectional view of a light control film 3 provided in the closed solar thermal heat collecting system 1 according to this embodiment. Fig. 5 is a flow diagram of the closed solar thermal heat collecting system 1 according to this embodiment.

[0014] The closed solar thermal collection system 1 of this embodiment comprises a solar collector 2, a light control film 3, a first temperature sensor S1, a storage tank (tank) 4, a second temperature sensor S2, a circulation pump (pump) 5, a pipe member 6, an expansion tank 7, a safety valve 8, a heat medium filling device 9, a control unit 10, and a power supply 11.

[0015] The solar collector 2 is installed on the roof of a house, for example. The solar collector 2 shown in Fig. 2 includes, for example, a heat collection plate 20, a housing 21, a plurality of heat collection pipes 22, a branch pipe 23, a junction pipe 24, a heat insulating material 26, and a light control cover 27. The solar collector 2 has the heat collection pipes 22 that temporarily accommodate a heat medium, and heats the heat medium accommodated in the heat collection pipes 22 by receiving sunlight.

[0016] The heat medium is, for example, water or synthetic oil, and transfers the heat collected by the solar light in the heat collector 2 to the heat exchanger 41 that the storage tank 4 has.

[0017] The heat collection plate 20 has two rectangular plates 20a and 20b, which are formed by bonding together. The plates 20a and 20b can be made of thin stainless steel plates with a thickness of, for example, about 0.2 to 0.4 mm.

[0018] The heat collection plate 20 has heat collection tubes 22 that temporarily store a heat medium, branch pipes 23 that allow the heat medium to flow into each heat collection tube 22, and a junction pipe 24 that allows the heat medium to flow out from each heat collection tube 22.

[0019] Each heat collection tube 22 is a flow path for circulating a heat medium inside the heat collection plate 20, and is configured, for example, by forming both of the two plates 20a, 20b into a corrugated shape so that they are spaced apart from each other. Note that each heat collection tube 22 may also be configured by forming either one of the two plates 20a, 20b into a corrugated shape. The multiple heat collection tubes 22 are arranged parallel to each other. Each heat collection tube 22 is installed so as to be inclined with respect to the vertical direction.

[0020] The heat collection pipe 22 contains a heat medium, and one end in the length direction is connected to the branch pipe 23, and the other end in the length direction is connected to the junction pipe 24.

[0021] One end of the branch pipe 23 is connected to an end of a first pipe member 61 that connects the circulation pump 5 and the heat collector 2. The other end of the branch pipe 23 is connected to a plurality of heat collection pipes 22.

[0022] One end of the junction pipe 24 is connected to an end of a second pipe member 62 that connects the heat collector 2 and the heat exchanger 41. The other end of the junction pipe 24 is connected to the plurality of heat collection pipes 22.

[0023] The housing 21 includes a case 21a having an opening 21o and a cover 21b formed of a light-transmitting material that closes the opening 21o. The heat collector 2 has an accommodation space 21s formed by the case 21a and the cover 21b. The light-transmitting material is formed of, for example, glass or a transparent synthetic resin.

[0024] The light control film 3 is provided on the solar collector 2 and is interposed between the sun and the heat collection tube 22. More specifically, the light control film 3 is disposed on the outer surface of the cover 21b. As shown in FIG. 4, the light control film 3 includes a liquid crystal layer 31, a pair of transparent electrodes 32a and 32b, and a pair of transparent protective layers 33a and 33b. The liquid crystal layer 31 contains a large number of liquid crystal molecules. When a DC voltage is applied from the power source 11 via the pair of transparent electrodes 32a and 32b, the liquid crystal molecules are arranged perpendicular to the surface of the liquid crystal layer 31, thereby allowing light to pass through the liquid crystal layer 31. On the other hand, when no voltage is applied from the power source 11 via the pair of transparent electrodes 32a and 32b, the liquid crystal layer 31 is in a non-voltage state, where a large number of liquid crystal molecules are arranged in a disordered manner, thereby reducing the amount of sunlight transmitted through the liquid crystal layer 31 compared to when a voltage is applied. In other words, the light control film 3 changes the amount of sunlight transmitted depending on the voltage applied from the power source 11 in response to commands from the control unit 10. More specifically, when the control unit 10 is in an applied state where a voltage is applied from the power source 11, the control unit 10 increases the amount of sunlight transmitted, whereas when the control unit 10 is in a non-applied state where no voltage is applied from the power source 11, the control unit 10 decreases the amount of sunlight transmitted compared to the applied state. When the light control film 3 is in an applied state, the sunlight transmission rate is, for example, 60 to 95%, whereas when the light control film 3 is in a non-applied state, the sunlight transmission rate is, for example, 5 to 40%. Note that a sunlight transmission rate of 100% means that sunlight is transmitted without attenuation when passing through an object. Furthermore, a sunlight transmission rate of 0% means that all sunlight is blocked when passing through an object. Furthermore, when the light control film 3 is in an applied state and the amount of sunlight transmitted is increased, the sunlight heats the heat medium, whereas when the light control film 3 is in a non-applied state and the amount of sunlight transmitted is reduced, the heat medium is cooled.

[0025] The pair of transparent electrodes 32a, 32b are arranged in the thickness direction of the liquid crystal layer 31, sandwiching the liquid crystal layer 31. Of the pair of transparent electrodes 32a, 32b, one transparent electrode 32a is electrically connected to, for example, the positive electrode of the power source 11, while the other transparent electrode 32b is electrically connected to, for example, the negative electrode of the power source 11. The pair of transparent electrodes 32a, 32b apply a DC voltage from the power source 11 to the liquid crystal layer 31.

[0026] The pair of transparent protective layers 33a, 33b are disposed in the thickness direction of the liquid crystal layer 31, sandwiching the pair of transparent electrodes 32a, 32b between them. The pair of transparent protective layers 33a, 33b protect the liquid crystal layer 31 and each of the transparent electrodes 32a, 32b from the outside.

[0027] The light control cover 27 is made of a transparent synthetic resin, and is disposed on the surface of the light control film 3, opposite the cover 21b, to protect the light control film 3 from the outside.

[0028] The first temperature sensor S1 is, for example, a thermocouple or a resistance temperature detector, and measures the heat medium temperature T1 in the heat collector 2. A predetermined medium temperature α, which will be described later, is, for example, 90°C.

[0029] The storage tank (tank) 4 stores water and has a heat exchanger 41 that heats the water by receiving heat from the heat medium heated in the heat collector 2. The water stored in the storage tank 4 is used as hot water for baths and the like in the house.

[0030] The second temperature sensor S2 is, for example, a thermocouple or a resistance temperature detector, and measures the temperature T2 of the stored water in the storage tank 4. A predetermined temperature β of the stored water, which will be described later, is, for example, 80°C.

[0031] The circulation pump (pump) 5 circulates the heat medium between the solar collector 2 and the heat exchanger 41. That is, the circulation pump 5 sends the heat medium heated in the solar collector 2 to the heat exchanger 41, and also sends the heat medium cooled by heat exchange with water in the heat exchanger 41 to the solar collector 2. In other words, the circulation pump 5 circulates the heat medium in a heat medium circulation device 12, which will be described later.

[0032] The pipe member 6 is formed in a cylindrical shape and contains a heat medium. The closed solar heat collecting system 1 according to this embodiment includes a first pipe member 61, a second pipe member 62, and a third pipe member 63.

[0033] The first pipe member 61 connects the circulation pump 5 and the heat collector 2. The second pipe member 62 connects the heat collector 2 and the heat exchanger 41. The third pipe member 63 connects the heat exchanger 41 and the circulation pump 5.

[0034] In the closed solar heat collecting system 1, the heat medium circulating device 12 is configured by the above-mentioned heat collector 2, storage tank 4, circulation pump 5, piping member, expansion tank 7, and safety valve 8.

[0035] The expansion tank 7 absorbs the expanded volume when the heat medium contained in the heat medium circulator 12 expands due to a temperature rise or the like. The expansion tank 7 is provided midway through the third pipe member 63.

[0036] In an emergency situation where the heat medium evaporates because the amount of sunlight transmitted through the heat collector 2 cannot be reduced due to a malfunction of the light control film 3, for example, the safety valve 8 releases the evaporated heat medium from inside the closed solar heat collecting system 1. The safety valve 8 is provided, for example, midway through the second pipe member 62, which will be described later.

[0037] The heat medium charging device 9 is used to replace the heat medium circulating in the heat medium circulation device 12 after the heat medium circulation device 12 has been operated for a certain period of time. The heat medium charging device 9 includes a reserve tank 91, a heat medium charging pump 92, and an inflow control valve 93. The heat medium charging device 9 is also used to replenish the heat medium that has decreased in the heat medium circulation device 12 by releasing the vaporized heat medium after an emergency situation in which the temperature rise of the heat medium cannot be suppressed due to some kind of malfunction and the heat medium has evaporated.

[0038] The reserve tank 91 stores the heat medium to be filled or replenished in the heat medium circulating device 12 when the heat medium in the heat medium circulating device 12 is replaced or replenished.

[0039] The heat transfer medium filling pump 92 is driven when the heat transfer medium stored in the reserve tank 91 is to be filled or replenished into the heat transfer medium circulation device 12, and by being driven, the heat transfer medium stored in the reserve tank 91 is to be filled or replenished into the heat transfer medium circulation device 12.

[0040] The inflow control valve 93 controls the heat medium flowing from the heat medium charging device 9 into the heat medium circulation device 12, and is configured to be switchable between a closed state and an open state. When switched to the closed state, the inflow control valve 93 restricts the heat medium flowing from the heat medium charging device 9 into the heat medium circulation device 12. On the other hand, when switched to the open state, the inflow control valve 93 allows the heat medium stored in the reserve tank 91 to be charged and replenished into the heat medium circulation device 12. The inflow control valve 93 is normally switched to the closed state, and is switched to the open state after an emergency or when the heat medium is to be replaced.

[0041] The control unit 10 comprehensively controls each unit of the closed solar heat collecting system 1. More specifically, the control unit 10 controls the driving and stopping of the circulation pump 5 and the heat medium charging pump 92, and also controls the voltage applied to the light control film 3 based on the detection results of the first temperature sensor S1 and the second temperature sensor S2.

[0042] Next, the flow of the closed solar thermal heat collecting system 1 having the above-described configuration will be described with reference to Fig. 5. First, the control unit 10 determines whether the measured stored water temperature T2 is equal to or lower than the predetermined stored water temperature β (step S01). If the measured stored water temperature T2 is equal to or lower than the predetermined stored water temperature β, the control unit 10 proceeds to step S02 (step S01: Yes). On the other hand, if the measured stored water temperature T2 is higher than the predetermined stored water temperature β, the control unit 10 proceeds to step S03 (step S01: No).

[0043] Next, the control unit 10 determines whether the measured heat medium temperature T1 is equal to or lower than the predetermined medium temperature α (step S02). If the measured heat medium temperature T1 is equal to or lower than the predetermined medium temperature α, the control unit 10 proceeds to step S05 (step S02: Yes). On the other hand, if the measured heat medium temperature T1 is higher than the predetermined medium temperature α, the control unit 10 proceeds to step S03 (step S02: No).

[0044] Next, the control unit 10 puts the light control film 3 in a non-applied state where no DC voltage is applied from the power source 11 to the light control film 3, thereby reducing the amount of transmitted sunlight, and proceeds to step S04 (step S03).

[0045] Next, the control unit 10 stops the circulation pump 5 (step S04), and then returns to step S01.

[0046] Next, the control unit 10 applies a DC voltage from the power source 11 to the light control film 3, increases the amount of sunlight transmitted, and proceeds to step S06 (step S05).

[0047] Next, the control unit 10 determines whether the temperature difference ΔT between the measured heat medium temperature T1 and the measured stored water temperature T2 is equal to or less than a predetermined temperature difference γ (step S06). If the temperature difference ΔT between the measured heat medium temperature T1 and the measured stored water temperature T2 is equal to or less than the predetermined temperature difference γ (step S06: Yes), the control unit 10 proceeds to step S07. If the temperature difference ΔT between the measured heat medium temperature T1 and the measured stored water temperature T2 is greater than the predetermined temperature difference γ (step S06: No), the control unit 10 proceeds to step S08. The predetermined temperature difference γ is, for example, 5°C.

[0048] Next, the control unit 10 stops driving the circulation pump 5 (step S07) and returns to step S01. When the driving of the heat medium pump is stopped, the heat medium is not circulated in the heat medium circulator 12. When the temperature difference ΔT between the heat medium temperature T1 and the stored water temperature T2 is small, it is difficult to raise the stored water temperature T2 using a high-temperature heat medium. In this state, driving the circulation pump 5 to circulate the heat medium results in unnecessary energy consumption. Therefore, in the closed solar thermal collection system 1 according to this embodiment, when the temperature difference ΔT between the heat medium temperature T1 and the stored water temperature T2 is small, the circulation pump 5 is stopped and the heat medium is not circulated. Therefore, the closed solar thermal collection system 1 according to this embodiment can prevent unnecessary energy consumption and can restrict the movement of the heat medium to prevent a decrease in the temperature of the heat medium.

[0049] Next, the control unit 10 drives the circulation pump 5 (step S08) and returns to step S01. When the temperature difference ΔT between the heat medium temperature T1 and the stored water temperature T2 is large, it is possible to raise the stored water temperature T2 by using a heat medium with a higher temperature. Therefore, the control unit 10 drives the circulation pump 5 to circulate the heat medium between the solar collector 2 and the storage tank 4. Then, in the closed solar thermal collection system 1, the temperature of the heat medium rises in the solar collector 2 when exposed to sunlight, and the temperature of the stored water rises in the storage tank 4 when exposed to the heat of the heat medium, making hot water available in the house.

[0050] The closed solar thermal collection system 1 according to this embodiment has the following configuration. When the measured heat medium temperature T1 is equal to or lower than the predetermined medium temperature α and the measured stored water temperature T2 is equal to or lower than the predetermined stored water temperature β, the control unit 10 switches the light control film 3 to an applied state, thereby increasing the amount of sunlight transmitted through the light control film 3 and heating the heat medium with the received sunlight. When the measured heat medium temperature T1 is higher than the predetermined medium temperature α or when the measured stored water temperature T2 is higher than the predetermined stored water temperature β, the control unit 10 switches the light control film 3 to a non-applied state, thereby reducing the amount of sunlight transmitted through the light control film 3 compared to the applied state and preventing the heat medium from being heated in the solar collector 2. Therefore, according to the closed solar thermal collection system 1 according to this embodiment, when the heat medium temperature T1 is equal to or lower than the predetermined medium temperature α and the stored water temperature T2 is equal to or lower than the predetermined stored water temperature β, the amount of sunlight transmitted through the light control film 3 is increased and the received sunlight heats the heat medium, allowing the stored water heated by the heat medium to be used. Furthermore, with the closed solar thermal collection system 1 according to this embodiment, when the heat medium temperature T1 is higher than the predetermined medium temperature α, or when the stored water temperature T2 is higher than the predetermined stored water temperature β, the light control film 3 reduces the amount of sunlight transmitted and suppresses heating of the heat medium, thereby suppressing evaporation of the heat medium. Moreover, the closed solar thermal collection system 1 according to this embodiment directly lowers the temperature of the heat medium by controlling the light control film 3 interposed between the sun and the heat collection tube 22 in the heat collector 2, thereby reducing the amount of transmitted sunlight. Therefore, evaporation of the heat medium can be suppressed with a simpler configuration than, for example, when the system is provided with a radiator or cooling device to indirectly lower the temperature of the heat medium.

[0051] The closed solar thermal collection system 1 according to this embodiment has the following configuration. When the temperature difference ΔT between the measured heat medium temperature T1 and the measured stored water temperature T2 is equal to or less than a predetermined temperature difference γ, the control unit 10 stops driving the circulation pump 5 and does not circulate the heat medium. Furthermore, when the temperature difference ΔT between the measured heat medium temperature T1 and the measured stored water temperature T2 is greater than the predetermined temperature difference γ, the control unit 10 drives the circulation pump 5 to circulate the heat medium. Therefore, the closed solar thermal collection system 1 according to this embodiment can drive the circulation pump 5 to use heated stored water when the temperature difference ΔT between the heat medium temperature T1 and the stored water temperature T2 is large. Furthermore, in the closed solar thermal collection system 1 of this embodiment, for example, when the temperature difference ΔT between the heat medium temperature T1 and the stored water temperature T2 is low at the time of starting up the system and the heat of the heat medium cannot be used for the stored water, the operation of the circulation pump 5 can be stopped to prevent unnecessary energy consumption, and the movement of the heat medium can be regulated to prevent the temperature of the heat medium from dropping.

[0052] The closed solar thermal heat collecting system 1 according to the embodiment described above has been described as having the light control film 3 provided between the cover 21b of the housing 21 and the light control cover 27. However, the closed solar thermal heat collecting system 1 according to the present embodiment is not limited to this, and the light control film 3 may be attached to the inner surface of the cover 21b, and the light control cover 27 may not be provided. In other words, the light control film 3 may be provided inside the housing 21.

[0053] [Modification of the embodiment] Next, a modified example of the above-described embodiment will be described. Fig. 6 is an explanatory diagram showing the predetermined medium temperature α, the predetermined stored water temperature β, and the predetermined temperature difference γ in a closed solar thermal heat collecting system 1 according to a modified example. The control unit 10 in the above-described embodiment has been described as one in which the predetermined medium temperature α at which the light control film 3 is in an applied state is the same as the predetermined medium temperature α at which the light control film 3 is in a non-applied state.

[0054] On the other hand, in the closed solar thermal collection system 1 according to the modified example, as shown in FIG. 6, the predetermined medium temperature α1 at which the light control film 3 is in an applied state is different from the predetermined medium temperature α2 at which the light control film 3 is in an unapplied state. More specifically, the control unit 10 sets the predetermined medium temperature α2 at which the light control film 3 is in an unapplied state lower than the predetermined medium temperature α1 at which the light control film 3 is in an applied state. For example, when the predetermined medium temperature α2 reaches 85°C, the control unit 10 sets the light control film 3 in an unapplied state to reduce the amount of sunlight transmitted, while keeping the light control film 3 in an applied state to increase the amount of sunlight transmitted until the predetermined medium temperature α1 reaches 90°C. In other words, the predetermined medium temperature α according to the modified example has a certain range.

[0055] In the closed solar thermal collection system 1 according to the modified example, the predetermined medium temperature α2 at which the amount of sunlight transmitted through the light control film 3 is reduced is set lower than the predetermined medium temperature α1 at which the amount of sunlight transmitted through the light control film 3 is increased. Therefore, the closed solar thermal collection system 1 according to the modified example reduces the amount of sunlight transmitted at the low predetermined medium temperature α2, and can further suppress evaporation of the heat medium.

[0056] Furthermore, the control unit 10 of the above-described embodiment has been described as one in which the predetermined temperature β of the stored water at which the light control film 3 is in an applied state is the same as the predetermined temperature β of the stored water at which the light control film 3 is in a non-applied state.

[0057] On the other hand, in the closed solar thermal collection system 1 according to the modified example, the predetermined stored water temperature β1 when the light control film 3 is in an applied state is different from the predetermined stored water temperature β2 when the light control film 3 is in a non-applied state. More specifically, the control unit 10 sets the predetermined stored water temperature β2 when the light control film 3 is in a non-applied state to be lower than the predetermined stored water temperature β1 when the light control film 3 is in an applied state. For example, when the predetermined stored water temperature β2 reaches 75°C, the control unit 10 sets the light control film 3 in a non-applied state to reduce the amount of sunlight transmitted, while keeping the light control film 3 in an applied state to increase the amount of sunlight transmitted until the predetermined stored water temperature β1 reaches 80°C. In other words, the predetermined stored water temperature β according to the modified example has a certain range.

[0058] In the closed solar thermal collection system 1 according to the modified example, the predetermined stored water temperature β2 at which the amount of sunlight transmitted through the light control film 3 is reduced is set lower than the predetermined stored water temperature β1 at which the amount of sunlight transmitted through the light control film 3 is increased. Therefore, the closed solar thermal collection system 1 according to the modified example reduces the amount of sunlight transmitted at the low predetermined stored water temperature β2, and can further suppress evaporation of the heat medium.

[0059] Furthermore, in the control unit 10 of the above-described embodiment, the predetermined temperature difference γ at which the circulation pump 5 is driven and the predetermined temperature difference γ at which the driving of the circulation pump 5 is stopped are the same.

[0060] On the other hand, in the closed solar thermal heat collecting system 1 according to the modified example, the predetermined temperature difference γ1 at which the circulation pump 5 is stopped is different from the predetermined temperature difference γ2 at which the circulation pump 5 is driven. More specifically, the control unit 10 sets the predetermined temperature difference γ2 at which the circulation pump 5 is stopped to be lower than the predetermined temperature difference γ1 at which the circulation pump 5 is driven. For example, the control unit 10 stops the circulation pump 5 when the temperature difference ΔT reaches the predetermined temperature difference γ2 of 3°C, and drives the circulation pump 5 when the temperature difference ΔT reaches the predetermined temperature difference γ1 of 5°C. In other words, the predetermined temperature difference γ according to the modified example has a certain width.

[0061] In the closed solar thermal collection system 1 according to the modified example, the predetermined temperature difference γ2 at which the circulation pump 5 is stopped is set smaller than the predetermined temperature difference γ1 at which the circulation pump 5 is driven. Therefore, the closed solar thermal collection system 1 according to the modified example can prevent the circulation pump 5 from being driven immediately after the circulation pump 5 is once stopped. As a result, the closed solar thermal collection system 1 according to the modified example can prevent the circulation pump 5 from being repeatedly driven and stopped, and can reliably prevent wasteful energy consumption.

[0062] The closed solar heat collecting system 1 according to the above-described embodiment and modified example has been described as including the heat collection plate 2 formed by bonding two plates 20a, 20b together as the heat collector 2. However, the closed solar heat collecting system 1 according to this embodiment is not limited to this, and may use a heat collection plate of another structure or a well-known heat collector. [Explanation of symbols]

[0063] 1. Closed solar thermal collection system 11 Power supply 2 Heat collector 22 Heat collection tube 3. Light-controlling film 4 Storage Tank (Tank) 41 Heat exchanger 5 Circulation pump (pump) 10 Control Unit S1 First temperature sensor S2 Second temperature sensor T1 Heat medium temperature T2 Storage water temperature α Predetermined temperature of medium β Reserved water temperature γ Predetermined temperature difference ΔT temperature difference

Claims

1. a heat collector having a heat collection tube that temporarily accommodates a heat medium, the heat collector receiving sunlight and heating the heat medium accommodated in the heat collection tube; a light control film that is provided on the heat collector and intervenes between the sun and the heat collection tube, and that changes the amount of sunlight transmitted in response to application of a voltage from a power source; a tank that stores stored water and has a heat exchanger that receives heat from the heat medium heated in the heat collector and heats the stored water; a pump that circulates the heat medium between the heat collector and the heat exchanger; a first temperature sensor for measuring a temperature of the heat medium in the heat collector; a second temperature sensor for measuring the temperature of the water stored in the tank; a control unit that controls the driving and stopping of the pump and controls the voltage applied to the light control film based on the detection results of the first temperature sensor and the second temperature sensor; Equipped with The control unit When the measured temperature of the heat medium is equal to or lower than a predetermined medium temperature and the measured temperature of the stored water is equal to or lower than a predetermined stored water temperature, a voltage is applied to the light-control film from the power source, whereby the light-control film transmits the sunlight and receives the sunlight to heat the heat medium; When the measured heat medium temperature is higher than the predetermined medium temperature, or when the measured stored water temperature is higher than the predetermined stored water temperature, a non-voltage application state is established in which no voltage is applied from the power source to the light control film, thereby reducing the amount of sunlight transmitted through the light control film compared to the voltage application state, and not heating the heat medium in the heat collector. A closed solar heat collection system.

2. The control unit When the temperature difference between the measured temperature of the heat medium and the measured temperature of the stored water is equal to or less than a predetermined temperature difference, the operation of the pump is stopped to stop the circulation of the heat medium, When the temperature difference between the measured temperature of the heat medium and the measured temperature of the stored water is larger than the predetermined temperature difference, the pump is driven to circulate the heat medium.

10. The closed solar thermal collection system of claim 1.

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