JP6861965B2 - Solar heat collector - Google Patents

Description

The present invention relates to a natural circulation type solar heat collector using a refrigerant composed of a supercritical fluid.

In the prior art, _{a solar heat collector using a refrigerant composed of supercritical CO 2} is known (see, for example, Patent Document 1).
This solar heat collector has a refrigerant inlet and outlet and is exposed to the sun, a heat exchanger having a heat transfer tube having a refrigerant inlet and outlet, and a heat collector outlet. And the first pipeline through which the refrigerant flows inside, and the second conduit through which the refrigerant flows inside by connecting the heat exchanger's inlet and the heat exchanger's outlet and the heat exchanger inlet. , And forms a closed circuit of the refrigerant consisting of a collector, a first conduit, a heat exchanger and a second conduit.

Further, a height difference is provided so that the suction port side of the heat transfer tube of the heat exchanger is higher than the discharge port side, and at least of the heat collector tubes of the heat collector, the CO ₂ of the liquid phase flowing into the heat collector tube is heated. The portion from the start to the supercritical state is arranged so as to have an upward gradient toward the downstream side in the flow direction of the _{supercritical CO 2.
Further, a detector for detecting the presence or absence of the supercritical state of supercritical CO 2} in the heat collector is provided, a flow rate control valve is provided in the closed circuit, and the flow rate control valve is controlled based on the detection value of the detector. A controller is provided.

Then, while the supercritical CO ₂ flows in the heat collector, the phase changes from the liquid phase to the supercritical state due to solar heat, while it is cooled by the heat recovery fluid while flowing in the heat transfer tube of the heat exchanger. The phase changes from the supercritical state to the liquid phase. In this case, _{the density of supercritical CO 2 in} the supercritical state is about 1/5 smaller than that in the liquid phase state, so that the supercritical CO ₂ naturally flows from the inlet side to the outlet side on the collector side. On the other hand, in the heat transfer tube of the heat exchanger, it descends from the suction port side toward the discharge port side. In this way, supercritical CO ₂ naturally circulates between the collector and the heat exchanger while changing the phase between the supercritical state and the liquid phase.

In this way, _{the solar heat absorbed and retained by the supercritical CO 2} in the heat collector is recovered by the heat recovery fluid in the heat exchanger.
According to this solar heat collector, there is no need for a means for forcibly circulating the refrigerant using external electric power such as a compressor, the device can be simplified and the cost can be reduced, and energy saving can be achieved. ..
However, on the other hand, in this solar heat collector, there is a problem that a sufficient circulating flow rate of the refrigerant cannot be obtained, and therefore the heat recovery rate of the device is low.

Japanese Patent No. 4607232

Therefore, an object of the present invention is to improve the heat recovery rate of a natural circulation type solar heat collector using a supercritical fluid.

In order to solve the above problems, according to the present invention, a heat collector having a refrigerant inlet and outlet made of a supercritical fluid and receiving solar irradiation, a refrigerant supply port, a refrigerant suction port, and a refrigerant discharge port are provided. The ejector, the outlet of the heat collector, and the refrigerant supply port of the ejector are connected, the first pipeline through which the refrigerant flows, and the inlet of the heat collector and the refrigerant discharge port of the ejector are connected. A heat exchanger that includes a second conduit through which the refrigerant flows, a heat transfer tube having a refrigerant inlet and a refrigerant outlet, and recovers heat from the refrigerant flowing through the heat transfer tube, and the first tube. A third conduit connecting the path and the refrigerant inlet of the heat transfer tube of the heat exchanger, and a third conduit connecting the refrigerant outlet of the heat transfer tube of the heat exchanger and the refrigerant inlet of the ejector . 4 conduits, a flow control valve arranged in at least one of the first to fourth conduits, and at least one of the first to fourth conduits, said. A detector for detecting the phase change state of the refrigerant and a control unit for controlling the flow control valve are provided, the outlet of the heat collector is arranged at a position higher than the inlet, and the heat exchanger is provided. The refrigerant inlet of the heat transfer tube is arranged at a position higher than the refrigerant outlet, and the first and third conduits are arranged at a position higher than the second conduit. The flow of the refrigerant is urged by the ejector, the flow control valve is controlled based on the detection value of the detector, and the refrigerant is heated by solar heat while flowing in the collector. While flowing from the liquid phase to the supercritical state, it is cooled while flowing in the heat transfer tube of the heat exchanger, and the space between the heat collector and the heat exchanger is changed so as to change from the supercritical state to the liquid phase. A solar heat collector is provided, which is characterized in that it naturally circulates while changing its phase.

According to a preferred embodiment of the present invention, the refrigerant flow path in the heat collector extends inclined from the inlet side toward the outlet side, or extends vertically from the inlet side toward the outlet side. The heat transfer tube of the heat exchanger extends inclined from the refrigerant inlet side toward the refrigerant outlet side, or extends vertically from the refrigerant inlet side toward the refrigerant outlet side.

According to another preferred embodiment of the present invention, the solar heat collector further comprises a bypass line connecting the first and second lines, a heater arranged in the bypass line, and the above. The bypass pipeline includes another flow rate control valve arranged on the upstream side and the downstream side of the heater, respectively, and the other flow rate control valve is controlled by the control unit.

According to yet another preferred embodiment of the present invention, the solar heat collector is further arranged in another bypass line connecting the second and fourth lines and in the other bypass line. Further, another flow rate control valve is provided, and the further flow rate control valve is controlled by the control unit.

According to yet another preferred embodiment of the present invention, the detector comprises a temperature detector and a pressure detector respectively arranged in the first and second pipelines.
According to yet another preferred embodiment of the present invention, the supercritical fluid is supercritical CO ₂ .

According to the present invention, the outlet of the heat collector and the refrigerant supply port of the ejector are connected by the first pipeline, the inlet of the heat collector and the refrigerant discharge port of the ejector are connected by the second pipeline, and heat is generated. The refrigerant inlet of the heat transfer tube of the exchanger and the first conduit are connected by the third conduit, the refrigerant outlet of the heat transfer tube and the refrigerant inlet of the ejector are connected by the fourth conduit, and further, the collection is performed. The outlet of the heat exchanger is located higher than the inlet, the refrigerant inlet of the heat transfer tube of the heat exchanger is located higher than the refrigerant outlet, and the first and third conduits are arranged in the second tube. It is located higher than the road. Further, a flow control valve and a detector for detecting the phase change state of the refrigerant are arranged in at least one of the first to fourth pipelines, and the flow control valve is controlled based on the detection value of the detector. ..

Then, while the refrigerant composed of the supercritical fluid is passed through the heat collector, the phase is changed from the liquid phase to the supercritical state by the solar heat, and a part of the refrigerant in the supercritical state is passed through the first conduit of the ejector. While flowing into the refrigerant supply port, the remaining portion is allowed to flow into the refrigerant inlet of the heat transfer tube of the heat exchanger through the third conduit.

The refrigerant flowing into the heat exchanger (heat transfer tube) is cooled while passing through the heat exchanger (heat transfer tube) to change the phase from the supercritical state to the liquid phase. On the other hand, the refrigerant flowing into the refrigerant supply port of the ejector is ejected from the nozzle of the ejector to the mixing portion and expanded under reduced pressure to change the phase from the supercritical state to the liquid phase. At the same time, the liquid phase refrigerant in the heat transfer tube is sucked into the mixing portion of the ejector through the fourth conduit, and the liquid phase refrigerant is sucked from the refrigerant discharge port (diffuser) of the ejector into the second pipe. Discharge to the road. The liquid phase refrigerant discharged from the ejector flows into the inlet of the heat collector through the second pipeline.

In this case, the density of the supercritical fluid in the supercritical state is about 1/5 smaller than that in the liquid phase state, so that the supercritical fluid naturally rises from the inlet side to the outlet side in the heat collector. In the heat transfer tube of the heat exchanger, the refrigerant naturally descends from the refrigerant inlet side toward the refrigerant outlet side, and the refrigerant undergoes a phase change between the supercritical state and the liquid phase between the collector and the heat exchanger. However, it circulates naturally. In this way, the solar heat absorbed and retained in the _{supercritical CO 2} in the heat collector is recovered in the heat exchanger.
Further, the flow of the circulating refrigerant can be urged by the ejector, thereby increasing the flow rate of the circulating refrigerant in the apparatus and greatly improving the heat recovery rate.

It is the schematic which shows the basic structure of the solar heat collector according to 1 Example of this invention. It is a perspective view of the heat collector of the solar heat collector of FIG. It is a graph which shows the result of simulating the heat collection efficiency of the heat collector of the solar heat collector of FIG. It is a graph which shows the result of simulating the heat recovery rate of the heat exchanger of the solar heat collector of FIG. It is the schematic which shows the basic structure of the solar heat collector according to another embodiment of this invention.

Hereinafter, the configuration of the present invention will be described with reference to the accompanying drawings, based on preferred embodiments.
FIG. 1 is a schematic view showing a basic configuration of a solar heat collector according to an embodiment of the present invention.
With reference to FIG. 1, according to the present invention, a heat collector 1 having an inlet 1a and an outlet 1b of a refrigerant and receiving sunlight irradiation is provided.

FIG. 2 is a perspective view of the heat collector. With reference to FIG. 2, the collector 1 comprises a known vacuum tube solar collector in this embodiment. The heat collector 1 has a hollow rectangular parallelepiped-shaped casing 2 having an opening at one end, so that the casing 2 has an opening at one end facing upward and one of a pair of opposing side walls is higher than the other. Is placed in.

The heat collector 1 is also arranged in parallel with the upper and lower headers 3a and 3b provided at the upper and lower ends inside the casing 2 at intervals inside the casing 2, respectively, and the upper and lower headers 3a, It has a plurality of heat collecting tubes 4 for connecting 3b.

The outer periphery of the heat collecting tube 4 is surrounded by a transparent glass tube 4a having a sealed structure, and the inside of the glass tube 4a is maintained in a vacuum state to prevent heat conduction from the heat collecting tube 4 and heat radiation due to heat convection. ing. Further, a parabolic reflector 5 is arranged below the glass tube 4a.
Then, the opening of the casing 2 is irradiated with the sun, and the sunlight is reflected by the reflector 5 and collected in the heat collecting tube 4.
Although not shown, a heat insulating material made of glass wool or the like is arranged under the reflector 5.

The heat collector 1 is further connected to a lower header 3b at one end, a lower collecting pipe 6a extending downward through the lower side wall of the casing 2, and one end is connected to the upper header 3a, and the casing 2 is further connected. It has an upper collecting pipe 6b that penetrates the upper side wall and extends upward. The other end opening of the lower collecting pipe 6a forms the inlet 1a of the heat collector 1, and the other end of the upper collecting pipe 6b forms the outlet 1b of the heat collector 1.

According to the present invention, it also includes an ejector 7 composed of a nozzle 7a, a mixing portion 7b, and a diffuser 7c. The base end opening of the nozzle 7a of the ejector 7 forms the refrigerant supply port 7d, the tip opening of the diffuser 7c forms the refrigerant discharge port 7e, and the refrigerant suction port 7f communicates with the mixing portion 7d.

Then, the outlet 1b of the heat collector 1 and the refrigerant supply 7d of the ejector 7 are connected by the first pipe line 8, and the inlet 1a of the heat collector 1 and the refrigerant discharge port 7e of the ejector 7 are connected to the second pipe line. It is connected by 9.
In this case, the first pipeline 8 is arranged at a higher position than the second pipeline 9.

According to the present invention, there is also provided a heat exchanger 11 including a heat transfer tube 10 having a refrigerant inlet 10a and a refrigerant outlet 10b, and recovering heat from the refrigerant flowing through the heat transfer tube 10.
In this embodiment, the heat exchanger 11 extends in the vertical direction, the refrigerant inlet 10a of the heat transfer tube 10 is located at the upper end of the heat exchanger 11, and the refrigerant outlet 10b is located at the lower end of the heat exchanger 11.
The outer periphery of the heat transfer tube 10 is surrounded by the heat recovery fluid flow path 12, and the heat recovery fluid inlet 12a is provided at the lower part of the flow path 12, while the heat recovery fluid outlet 12b is provided at the upper part of the flow path 12. Has been done.

Further, the first pipe line 8 and the refrigerant inlet 10a of the heat transfer tube 10 of the heat exchanger 11 are connected by the third pipe line 13, and the refrigerant outlet 10b of the heat transfer tube 10 of the heat exchanger 11 and the ejector 7 are connected. The refrigerant suction port 7f is connected by the fourth pipeline 14.
In this case, the third pipeline 13 is arranged at a higher position than the second pipeline 9.

Further, a first flow rate control valve 15, a first temperature detector 16, and a first portion extend between the connection portion between the heat collector 1 and the third pipeline 13 of the first pipeline 8. The pressure detector 17 of 1 and the first mass flow meter 18 are arranged. Further, a second temperature detector 19 and a second pressure detector 20 are arranged in the second pipeline 9.

The first and second temperature detectors 16 and 19 and the first and second pressure detectors 17 and 20 function as detectors for detecting the state of phase change of the refrigerant.
Then, the first flow control valve 15 is controlled based on the measured values of the first and second temperature detectors 16 and 19, the first and second pressure detectors, and the first mass flow meter 18. It is controlled by the unit 28.
The first mass flow meter 18 is arranged as needed.

Further, the heat recovery fluid supply pipe 21 is connected to the inlet 12a of the heat recovery fluid flow path 12 of the heat exchanger 11, and the heat recovery fluid discharge pipe 22 is connected to the outlet 12b. Further, a pump 23 is arranged in the heat recovery fluid supply pipe 21, and a third temperature detector 24 and a second mass flow meter 25 are arranged on the downstream side of the pump 23 in the heat recovery fluid supply pipe 21 to generate heat. A second flow control valve 26 is arranged in the recovery fluid discharge pipe 22, and a fourth temperature detector 27 is arranged on the downstream side of the second flow control valve 26 in the heat recovery fluid discharge pipe 22.
The pump 23 and the second flow control valve 26 are controlled by the control unit 28 based on the measured values of the third and fourth temperature detectors 24 and 27 and the second mass flow meter 25.

In this way, it is formed from the heat collector 1, the first line 8, the ejector 7, the second line 9, the third line 13, the heat transfer tube 11 of the heat exchanger 11, and the fourth line 14. The closed pipeline system is filled with a refrigerant composed of a supercritical fluid.
In this case, various known supercritical fluids can be appropriately used, but from the viewpoint of ease of handling, safety, environmental protection, etc., CO ₂ (critical temperature = 31.1 ° C., critical pressure) = 7.38 MPa) is preferably used.

Further, the heat recovery fluid is supplied to the flow path 12 of the heat exchanger 11 through the heat recovery fluid supply pipe 21, flows in the flow path 12 in a countercurrent manner, and then flows from the flow path 12 through the heat recovery fluid discharge pipe 22. It is discharged.
In this embodiment, water is used as the heat recovery fluid.

Then, while the refrigerant flows through the heat collector 1 (heat collector tube 4), it is heated by the solar heat and the phase changes from the liquid phase to the supercritical state. Then, a part of the refrigerant in the supercritical state flows into the refrigerant supply port 7d of the ejector 7 through the first conduit 8, while the remaining portion flows through the third conduit 13 of the heat transfer tube 10 of the heat exchanger 11. It flows into the refrigerant inlet 10a.

The refrigerant that has flowed into the heat exchanger 11 (heat transfer tube 10) is cooled by water (heat recovery fluid) while passing through the heat exchanger 11 (heat transfer tube 10), and the phase changes from a supercritical state to a liquid phase ( Water (heat recovery fluid) is heated to become hot water). On the other hand, the refrigerant flowing into the refrigerant supply port 7d of the ejector 7 is ejected from the nozzle 7a of the ejector 7 to the mixing portion 7b, and at that time, the phase changes from the supercritical state to the liquid phase by decompression and expansion. At the same time, the liquid phase refrigerant in the heat transfer tube 10 is sucked into the mixing portion 7b of the ejector 7 from the refrigerant suction port 7f through the fourth conduit 14, and the liquid is sucked from the refrigerant discharge port 7e (diffuser 7c) of the ejector 7. The phase refrigerant is discharged into the second conduit 9. The liquid phase refrigerant discharged from the ejector 7 flows into the inlet 1a of the heat collector 1 through the second conduit 9.

In this case, the density of the supercritical fluid in the supercritical state is about 1/5 smaller than that in the liquid phase state, so that the supercritical fluid naturally flows from the inlet 1a side to the outlet 1b side in the heat collector 1. On the other hand, in the heat transfer tube 10 of the heat exchanger 11, it naturally descends from the refrigerant inlet 10a side toward the refrigerant outlet 10b side, and the refrigerant is supercritical between the heat collector 1 and the heat exchanger 11. It circulates naturally with phase changes between state and liquid phases. In this way, the solar heat absorbed and held by the refrigerant in the heat collector 1 is recovered in water (heat recovery fluid) in the heat exchanger 11.
Further, the flow of the circulating refrigerant is urged by the ejector 7, whereby the flow rate of the circulating refrigerant in the apparatus is increased, and the heat recovery rate is greatly improved.

In this embodiment, the heat recovery fluid supply pipe 21 and the heat recovery fluid discharge pipe 22 of the heat exchanger 11 are connected to the hot water supply tank, and the hot water supply tank, the heat recovery fluid supply pipe, the heat exchanger, and the heat recovery fluid discharge If a closed pipeline system consisting of pipes is formed, it can be used as a solar heat water heater.

Next, a simulation was performed in order to investigate the actual heat collection efficiency and heat recovery efficiency of the solar heat collector of the present invention. The contents of the simulation are as follows.

(Simulation 1)
In the device configuration in which the first flow control valve 15 is removed from the pipeline system shown in FIG. 1, the amount of solar radiation (heat input) to the heat collector 1 is 1300 W, and _{the pressure of CO 2 in} the supercritical state is 7.5 MPa. _{Further, it is assumed that the mass flow rate of the supercritical CO 2} flowing out from the heat collector 1 (measured value of the first mass flow meter 18) increases 1.2 times as much as the case where the ejector 7 is not provided. _{The mass flow rate of the supercritical CO 2} flowing out of the vessel 1 (measured value of the first mass flow meter 18) was changed in a plurality of stages, and the heat collection efficiency of the heat collector 1 was calculated for each mass flow rate. The results are shown in the graph of FIG.

In the graph of FIG. 3, the vertical axis represents the thermal collection efficiency, and the horizontal axis represents the mass flow rate (kg / h) of _{supercritical CO 2.} Further, the graph connecting the points indicated by "□" is for the device configuration including the ejector 7, and the graph shown by the broken line is for the device configuration not including the ejector 7.
From the graph of FIG. 3, it was confirmed that the heat collection efficiency was improved by providing the ejector 7.

(Simulation 2)
Similar to the case of the simulation 1, _{the mass flow rate of the supercritical CO 2} flowing out from the heat collector 1 (measured value of the first mass flow meter 18) is changed in a plurality of stages, and the heat exchanger 10 is changed for each mass flow rate. The heat recovery rate of was calculated. The results are shown in the graph of FIG.

In the graph of FIG. 4, the vertical axis represents the heat recovery rate, and the horizontal axis represents the mass flow rate (kg / h) of _{supercritical CO 2.} Further, the graph connecting the points indicated by "□" is for the device configuration including the ejector, and the graph shown by the broken line is for the device configuration without the ejector.

From the graph of FIG. 4, it was confirmed that the heat recovery rate was improved by providing the ejector 7 when the mass flow rate of the _{supercritical CO 2 was in the range of 10 to 18 kg / h.} When the ejector 7 is provided, if _{the mass flow rate of supercritical CO 2} exceeds 18 kg / h, the heat recovery efficiency does not increase because the diversion between the first pipeline 8 and the third conduit 13 Is considered to have an effect.

FIG. 5 is a diagram similar to FIG. 1 showing a basic configuration of a solar heat collector according to another embodiment of the present invention.
The embodiment of FIG. 5 is obtained by adding another configuration requirement to the embodiment of FIG. Therefore, in FIG. 5, the same components as those shown in FIG. 1 are assigned the same number, and detailed description thereof will be omitted below.

With reference to FIG. 5, in this embodiment, first, a first bypass line 29 connecting the first and second lines 8 and 9 and a heater 30 arranged in the first bypass line 29 And the third and fourth flow control valves 31 and 32 arranged on the upstream side and the downstream side of the heater 30 in the first bypass line 29, respectively.
The heater 30 and the third and fourth flow control valves 31 and 32 are controlled by the control unit 28.

According to this added configuration, for example, when the solar heat collector of the present invention is used as a solar water heater, the solar irradiation amount is reduced due to rainy or cloudy weather, or the solar irradiation amount is increased at night. Even when it becomes zero, a constant hot water temperature can be obtained by operating the heater 30 to adjust the opening degrees of the third and fourth flow control valves 31 and 32 and heating the refrigerant by the heater 30.
Further, the heater 30 is operated to adjust the opening degrees of the third and fourth flow rate control valves 31 and 32, and the refrigerant is heated to promote the phase change from the liquid phase to the critical state. Can function as a kind of pump to urge the flow of refrigerant in the device.
In addition, the solar heat collector of the present invention can be operated more efficiently by predicting the daily solar irradiation amount, temperature, etc. based on meteorological big data and controlling the heater 30 based on the predicted values. Can be done.

Further, a second bypass line 33 connecting the second and fourth lines 9 and 13 and a fifth flow control valve 34 arranged in the second bypass line 33 are provided. The fifth flow rate control valve 34 is controlled by the control unit 28.
According to this added configuration, the amount of refrigerant flowing into the inlet 1a of the heat collector 1 can be rapidly increased or decreased by adjusting the opening degree of the fifth flow rate control valve 34.

Although the configuration of the present invention has been described above based on some preferred examples, the configuration of the present invention is not limited to the above examples, and various modifications are made within the scope of the configuration described in the claims of the present application. Needless to say, we can come up with an example.
For example, in the above embodiment, only one flow control valve is arranged on the downstream side of the connection portion of the first pipeline 8 with the third pipeline 13, but in addition to that, the first pipeline 8 Another flow rate control valve may be arranged on the upstream side of the connection portion with the third pipeline 13, and in addition, another flow rate control valve may be arranged on the third pipeline 13. However, in addition to that, another flow rate control valve may be arranged in the fourth pipeline 14.
Further, for example, in the above embodiment, the heat exchanger 11 is composed of the heat transfer tube 10 and the flow path 12 of the heat recovery fluid surrounding the outer periphery of the heat transfer tube 10, but the heat exchanger 11 is composed of the heat transfer tube 10. , And a blower that directly air-cools the heat transfer tube 10.

1 Heat collector 1a Inlet 1b Outlet 2 Casing 3a Upper header 3b Lower header 4 Heat collecting pipe 4a Glass pipe 5 Reflector plate 6a Lower collecting pipe 6b Upper collecting pipe 7 Ejector 7a Nozzle 7b Mixing part 7c Diffuser 7d Fluid supply port 7e Fluid discharge port 7f Nozzle suction port 8 1st pipe 9 2nd pipe 10 Heat transfer pipe 10a Refrigerator inflow port 10b Refrigerator outflow port 11 Heat exchanger 12 Heat recovery fluid flow path 12a Inlet 12b Outlet 13 Third pipeline 14th 4 Pipe line 15 First flow control valve 16 First temperature detector 17 First pressure detector 18 First mass flow meter 19 Second temperature detector 20 Second pressure detector 21 Heat recovery fluid Supply pipe 22 Heat recovery fluid discharge pipe 23 Pump 24 Third temperature detector 25 Second mass flow meter 26 Second flow control valve 27 Fourth temperature detector 28 Control unit 29 First bypass line 30 Heater 31 Third flow control valve 32 Fourth flow control valve 33 Second bypass line 34 Fifth flow control valve

Claims (6)

A heat collector that has an inlet and an outlet for a refrigerant composed of supercritical fluid and receives solar irradiation,
An ejector having a refrigerant supply port, a refrigerant suction port, and a refrigerant discharge port,
A first pipeline that connects the outlet of the heat collector and the refrigerant supply port of the ejector and allows the refrigerant to flow inside, and
A second pipeline that connects the inlet of the heat collector and the refrigerant discharge port of the ejector and allows the refrigerant to flow inside, and
A heat exchanger that includes a heat transfer tube having a refrigerant inlet and a refrigerant outlet and recovers heat from the refrigerant flowing through the heat transfer tube.
A third line connecting the first line and the refrigerant inlet of the heat transfer tube of the heat exchanger, and a third line.
A fourth pipeline connecting the refrigerant outlet of the heat transfer tube of the heat exchanger and the refrigerant suction port of the ejector, and
A flow control valve arranged in at least one of the first to fourth pipelines,
A detector arranged in at least one of the first to fourth pipelines to detect the phase change state of the refrigerant, and
A control unit that controls the flow control valve is provided.
The outlet of the heat collector is arranged at a position higher than the inlet, and the refrigerant inlet of the heat transfer tube of the heat exchanger is arranged at a position higher than the refrigerant outlet, and the first. And the third conduit is located higher than the second conduit.
The flow of the refrigerant is urged by the ejector, the flow control valve is controlled based on the detection value of the detector, and the refrigerant is heated by solar heat while flowing in the collector. While flowing from the liquid phase to the supercritical state, the heat exchanger is cooled between the heat exchanger and the heat exchanger so that the heat exchanger changes from the supercritical state to the liquid phase. A solar heat collector characterized by naturally circulating while changing phases. The refrigerant flow path in the heat collector extends inclined from the inlet side toward the outlet side, or extends vertically from the inlet side toward the outlet side.
The heat transfer tube of the heat exchanger extends inclined from the refrigerant inlet side toward the refrigerant outlet side, or extends vertically from the refrigerant inlet side toward the refrigerant outlet side. The solar heat collector according to claim 1, wherein the solar heat collector is provided. Bypass pipelines connecting the first and second pipelines,
With the heater arranged in the bypass pipeline,
It is provided with separate flow control valves arranged on the upstream side and the downstream side of the heater in the bypass pipeline, respectively.
The solar heat collector according to claim 1 or 2, wherein the other flow rate control valve is controlled by the control unit. With another bypass line connecting the second and fourth lines,
With yet another flow control valve located in the other bypass line,
The solar heat collecting device according to any one of claims 1 to 3, wherein the further flow rate control valve is controlled by the control unit. The detector
The solar heat collector according to any one of claims 1 to 4, wherein the temperature detector and the pressure detector are arranged in each of the first and second pipelines. The solar heat collector according to any one of claims 1 to 5, wherein the supercritical fluid is supercritical CO _2.

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