JP2015121401A - Heat exchange system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat exchange system having high heat exchanging efficiency, and capable of reducing labor and costs for construction, and saving energy.SOLUTION: A heat exchange system includes a piping system (La) and water storage equipment (150, GH) for soaking the piping system in water, and the piping system (La) is constituted to allow a heat medium to pass therein and has a function for exchanging heat with the water in the water storage equipment. The heat medium is carbon dioxide, heat is exchanged between vaporization heat of carbon dioxide and the water in the water storage equipment, and a temperature of carbon dioxide flowing in a region out from the water storage equipment in the piping system is determined to be 5°C-40°C to exchange between the vaporization heat of carbon dioxide and the water in the water storage equipment.

Description

The present invention relates to a heat exchange technique for recovering heat from water and / or discharging heat into water to be used for air conditioning, hot water supply, and other thermal loads.

In Japan, the underground temperature is about 15 ° C. throughout the year, the winter temperature in Japan is much lower than 15 ° C., and the summer temperature is much higher than 15 ° C.
From this, it can be considered that the temperature difference is effectively used for, for example, air conditioning, hot water supply, and other thermal loads.
For this reason, the inventor has conducted research on techniques for recovering and using geothermal heat.

In the prior art, the recovery of geothermal heat (or exhaust heat to the ground) is performed by passing a known liquid phase heat medium (brine) through a pipe buried in the ground, and the liquid phase heat medium and the geothermal heat. Heat exchange (so-called “sensible heat-sensible heat exchange”).
However, in order to secure an area necessary for the heat medium to exchange heat with geothermal heat, the diameter of the pipe through which the refrigerant flows is increased.
In addition, for example, in order to recover an amount of heat sufficient for an air conditioner to operate properly, a very long pipe must be buried deep in the ground.
And in order to embed large diameter piping to a deep underground area, there exists a problem that a lot of cost will be needed.

As another conventional technique, for example, a technique for storing underground heat using groundwater as a heat medium has been proposed (see Patent Document 1).
However, in the related art (Patent Document 1), it is necessary to drill a well hole, and when the amount of heat storage increases, the depth of the well must be increased, and thus the above-described problems cannot be solved.

JP 2010-38507 A

The present invention has been proposed in view of the above-described problems of the prior art, and aims to propose a heat exchange system that has high heat exchange efficiency and can save labor and cost for construction.

As a result of various studies, the inventor has recovered the heat from the water to the heat medium during the heating operation, rather than using geothermal heat, when using carbon dioxide (CO ₂ ) as the heat medium (or refrigerant). It was discovered that heat exchange efficiency is improved by discharging the heat from the heat medium into the water during operation. Then, the temperature of the heating medium carbon dioxide is (or refrigerant) (CO ₂₎ is the is 5 ° C. to 40 ° C., it was found that the heat exchange efficiency is very high.
The present invention has been proposed based on such knowledge.

According to the present invention, a water storage facility (150, GH) and a piping system having a function of exchanging heat with water in the water storage facility (150, GH) by being immersed in the water of the water storage facility (150, GH) ( La), the outdoor unit (1) connected to the piping system (La), the outdoor unit (1), the indoor unit (2), the compressor (4), and the four-way valve (V4) are interposed. In the heat exchange system comprising a first heat medium line (Lb) and a second heat medium line (Lc) connecting the indoor unit (2) and the air conditioner (3), the piping system (La) The heat medium flowing through the inside is carbon dioxide, and a pump (5) is provided in a region of the piping system (La) immersed in water, and the discharge port (5o) of the pump (5) is the first. The first valve (V1) is connected to the first valve (V1) via a line (La1) of the second line. Is connected to one connection port (11) of the outdoor unit (1) via a line (La2), and the other connection port (12) of the outdoor unit (1) is connected to a third line (La3). Connected to the second valve (V2), the vicinity of the first valve (V1) in the second line (La2) and the vicinity of the second valve (V2) in the third line (La3) The bypass line (La5) is connected to the bypass line (La5), bypassing the first and second valves (V1, V2) and the pump (5), and the compressor (4) and the pump ( 5) and a control unit (50) for switching between cooling and heating by controlling the first and second valves (V1, V2). The control unit (50) is provided with the first and second valves ( Close V1, V2) And, if the pump is stopped (5), opens the first and second valves (V1, V2) during cooling, and has a function of actuating the pump (5).

According to the present invention, the piping system (La) is provided with a discharge valve (Va) and a carbon dioxide supply amount adjustment valve (Vc), and has a control unit (50A). (50A) is a function that obtains the carbon dioxide circulation amount from the valve opening degree of the discharge valve (Va) and the carbon dioxide supply amount control valve (Vc), and whether or not the carbon dioxide circulation amount is appropriate compared with a predetermined amount. If the carbon dioxide circulation amount is appropriate, the valve opening degree of the discharge valve (Va) and the carbon dioxide supply amount control valve (Vc) is maintained, and the carbon dioxide circulation amount is excessive. Increases the valve opening of the discharge valve (Va) and / or decreases the valve opening of the carbon dioxide supply control valve (Vc), and if the carbon dioxide circulation amount is too small, the discharge valve (Va) Decrease valve opening and / or adjust carbon dioxide supply Preferably it has a function of increasing the valve opening degree of the (Vc).

And in this invention, it is preferable to set the temperature of the carbon dioxide which flows through the area | region which left the water storage equipment (150, GH) in the said piping system (La) to 5 to 40 degreeC.

Furthermore, in the present invention, when performing the cooling operation, the temperature difference between the temperature of carbon dioxide flowing in the area entering the water storage facility (150, GH) of the piping system (La) and the water storage facility (150, GH) is 60 degrees C or less is preferable.

And in this invention, when heating operation is performed, the temperature difference between the water temperature in the water storage facility (150, GH) and the carbon dioxide flowing through the region entering the water storage facility (150, GH) of the piping system (La) Is preferably 30 ° C. or lower.

In carrying out the present invention, the water storage facility can be constituted by a so-called water tank (150) or a reservoir (GH).
Moreover, it is also possible to comprise the said water storage installation by the underdrain and the groove | channel (or opening) which have the depth which the piping system (La) in which the heat medium flows has immersed.

According to the present invention having the above-described configuration, carbon dioxide is used as a heat medium, and the heat of vaporization (or condensation heat) of carbon dioxide and the water in the water storage facility (water tank 150, reservoir GH) Exchanges heat with sensible heat. That is, when recovering the amount of heat held by the water in the water storage facility (water tank 150, reservoir GH), the liquid phase carbon dioxide recovers the heat of vaporization from the water and discharges the heat to the water in the water storage facility. In this case, carbon dioxide in the gas phase is condensed by discharging heat of condensation into the water (G) in the water storage facility.
In other words, the latent heat of the heat medium composed of carbon dioxide and the sensible heat of the water in the water storage facility perform so-called “latent heat-sensible heat exchange”.
Here, “latent heat-sensible heat exchange” is a heat medium per unit amount that can recover or discharge a large amount of heat, compared to the so-called “sensible heat-sensible heat exchange”. Heat exchange efficiency is greatly improved.

Further, according to the present invention, the temperature of carbon dioxide flowing through the region exiting the water storage facility (150) is set to 5 ° C. to 40 ° C., and even if the pressure is increased by compressing carbon dioxide, the carbon dioxide is liquefied. It is set to a temperature in the vicinity of the critical point (31.1 ° C.), which is the temperature at which it stops. As will be described later, according to the inventor's experiment, if the temperature of carbon dioxide flowing through the region exiting the water storage facility (water tank 150, reservoir GH) is near the critical point (31.1 ° C.), carbon dioxide and Heat exchange efficiency with water is improved.
Here, when the temperature of the carbon dioxide flowing through the area exiting the water storage facility is too high (when the temperature is higher than 40 ° C.), the heat exchange efficiency is lowered during cooling. It is clear from the experiment.
On the other hand, when the temperature of the carbon dioxide flowing through the area exiting the water storage facility is too low (when the temperature is lower than 5 ° C.), the pressure of the heat medium in the piping system (La, 9) becomes low, This may be inconvenient when the medium (carbon dioxide) is naturally circulated.

In addition, in the present invention, carbon dioxide is used as a heat medium (refrigerant), and carbon dioxide has a larger heat capacity than that of brine used in the prior art.
Therefore, according to the present invention, the heat medium can efficiently recover the amount of heat from the water in the water storage facility, or can be efficiently discharged, so the piping system (La, 9) through which the heat medium flows can be shortened. Can be thinned. Moreover, the labor and cost for installing piping (La, 9) through which a heat medium flows can be reduced significantly.

Here, in the case of the prior art in which brine is used as the heat medium and heat exchange is performed with the heat medium and geothermal heat, the underground pipe through which the brine flows is arranged along the foundation pile or the foundation pile. The underground piping must be arranged in the ground, which causes extra costs when constructing foundation piles.
In addition, when the underground pipe through which the brine flows is not disposed in the vicinity of the underground pile, a well for burying the underground pipe has to be excavated, and costs for that are generated.
On the other hand, in the present invention, there is no need to embed the piping system (La, 9) in the ground (G), and the piping system (La, 9) can be shortened and thinned. The labor and cost in the prior art associated with the burial can be greatly reduced.

Furthermore, in the present invention, when the piping system (La) through which the heat medium flows is constituted by the double pipe (9), for example, when recovering the amount of heat held by the water in the water storage facility (heating operation) The liquid phase carbon dioxide sent from the heat exchanger (for example, the outdoor unit 1) descends the inner pipe (91) of the double pipe (9). Here, since the liquid phase carbon dioxide has a larger specific gravity than the gas phase carbon dioxide, the liquid phase carbon dioxide falls downward due to its mass.
On the other hand, when liquid phase carbon dioxide collects heat of vaporization from the water in the water storage facility and vaporizes, the vapor phase carbon dioxide has a lower specific gravity than the liquid phase carbon dioxide, and the heat exchanger (for example, outdoor The outer pipe (92) of the double pipe (9) is raised toward the machine 1).
Therefore, liquid phase carbon dioxide and gas phase carbon dioxide flow through the double pipe without providing external power.

In the present invention, if a plurality of piping systems (9D) in the water storage facility are provided, the amount of heat held by the water in the water storage facility can be efficiently recovered and the heat can be discharged to the water in the water storage facility.
Here, if the piping system in the water storage facility is arranged in a spiral shape (9E, 9F), the length in the circumferential direction is three times the diameter, so that the excavation depth is about 1/3 that of the prior art.

In the present invention, when cooling operation is performed, the temperature of carbon dioxide flowing in the area entering the water storage facility (150, GH) of the piping system (La, 9) (FIG. 26 (A), plot “◯” in FIG. 28) Temperature shown: temperature measured by temperature sensor 7 in FIG. 4) and water temperature in water storage facility (150, GH) (FIG. 26A, temperature indicated by dotted characteristic curve in FIG. 28: temperature sensor in FIG. If the temperature difference of the temperature measured by TW1 is 60 ° C. or less, the cooling operation can be performed without reducing the cooling efficiency.
This has been confirmed by the inventors' experiments.

Alternatively, in the present invention, when heating operation is performed, the water temperature in the water storage facility (150, GH) (the temperature indicated by the dotted characteristic curve in FIG. 27A): the temperature measured by the temperature sensor TW1 in FIG. ) And the temperature of carbon dioxide flowing through the area entering the water storage facility (150, GH) of the piping system (La, 9) (the temperature indicated by the plot “◯” in FIG. 27A: measured by the temperature sensor 6 in FIG. 3) If the temperature difference from the temperature is 30 ° C. or less, the heating operation can be performed without reducing the heating efficiency.
This has also been confirmed by the inventors' experiments.

It is a block diagram which shows the outline | summary of 1st Embodiment of this invention. It is the flowchart figure which showed the control which switches air_conditioning | cooling and heating in 1st Embodiment. In FIG. 1, it is a figure which shows the flow of the heat medium in the case of performing heating operation. In FIG. 1, it is a figure which shows the flow of the heat medium in the case of performing a cooling operation. It is a fragmentary sectional view which shows the flow of the heat medium at the time of heating operation, when piping is made into a double pipe. It is a fragmentary sectional view which shows the flow of the heat medium at the time of air_conditionaing | cooling operation, when piping is made into a double pipe. It is a block diagram which shows the structure of the lower end part of a double pipe. In FIG. 7, it is a figure which shows the case where heating operation is performed. In FIG. 7, it is a figure which shows the case where a cooling operation is performed. It is a block diagram which shows a double pipe upper end part. It is a block diagram which shows the modification of a double pipe upper end part. It is a cross-sectional view showing a first modification of a double tube. It is a longitudinal cross-sectional view which shows the 2nd modification of a double tube. It is a block diagram explaining the control in 1st Embodiment. It is a flowchart which shows the control in FIG. It is a figure which shows the modification of 1st Embodiment. It is a block diagram which shows the principal part of 2nd Embodiment of this invention. It is a block diagram which shows the principal part of 3rd Embodiment of this invention. It is a block diagram which shows the construction procedure in 3rd Embodiment. It is a block diagram which shows the construction procedure which continues in FIG. It is a block diagram which shows the construction procedure which continues in FIG. It is a block diagram which shows the principal part of 4th Embodiment of this invention. It is a block diagram which shows the principal part of 5th Embodiment of this invention. It is a block diagram which shows the principal part of 6th Embodiment of this invention. It is a block diagram which shows the experimental apparatus used in the experiment example. It is a characteristic view which shows the experimental result at the time of air_conditioning | cooling. It is a characteristic view which shows the experimental result at the time of heating. It is a characteristic view which shows the experimental result at the time of air_conditioning | cooling at the time of changing the operating condition in FIG. It is a block diagram explaining the control in 1st Embodiment. It is a flowchart which shows the control in FIG.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
In the illustrated embodiment, an air conditioning system is illustrated as an example of a heat exchange system.
In other words, in the illustrated embodiment, for example, the air conditioner 3 is connected as the thermal load.

1 to 16 show a first embodiment (including various modifications) of the present invention.
Here, FIG. 1, FIG. 3, and FIG. 4 show a part of the pipe (La) immersed in the water tank as a configuration different from the actual configuration in order to facilitate understanding of the operation. The configuration of the pipe (La) immersed in the water tank will be described later.
In addition, although the control system (control unit 50 grade | etc.) Of air-conditioning switching control is illustrated in FIG. 1, the said control system is abbreviate | omitting illustration in FIG. 3, FIG.
First, an outline will be described in the first embodiment with reference to FIG.

In FIG. 1, an air conditioning system (heat exchange system) generally indicated by reference numeral 100 includes a first heat exchanger (hereinafter referred to as “outdoor unit”) 1 and a second heat exchanger (hereinafter referred to as “indoor unit”). 2. Air conditioner 3 (including hot water floor heating) that is a thermal load, water tank 150 that is a water storage facility, piping system La that is immersed in water tank 150, first heat medium line Lb, 2 heat medium lines Lc.

The piping system La immersed in the water tank 150 is provided with a first heat exchanger 1, a pump 5, on-off valves V 1 and V 2, and temperature sensors 6 and 7. In the piping system La, liquid phase carbon dioxide or gas phase carbon dioxide (hereinafter, carbon dioxide is referred to as “CO ₂ ”) as a heat medium flows.
The piping system La has lines La1 to La5.
In order to measure the water temperature in the water tank 150, a temperature sensor (water temperature sensor) TW1 is disposed in the water tank 150.

The line La1 connects the discharge port 5o of the pump 5 and the valve V1.
The line La2 connects the valve V1 and the connection port 11 of the outdoor unit 1. In the line La2, a branch point B1 is provided in the vicinity of the valve V1, and a temperature sensor 6 is interposed in the vicinity of the connection port 11.
The line La3 connects the connection port 12 of the outdoor unit 1 and the valve V2. In the line La3, a branch point B2 is provided in the vicinity of the valve V2, and a temperature sensor 7 is interposed in the vicinity of the connection port 12.
The line La4 connects the valve V2 and the suction port 5i of the pump 5.
The line La5 is a bypass line that bypasses the pump 5 by connecting the branch point B1 and the branch point B2.

In FIG. 1, the piping system La is immersed in the water W in the water tank 150 except for a part of the line La2 and the line La3 on the outdoor unit 1 side of the piping system La. The configuration of the piping system La immersed in the water W in the water tank 150 will be described later with reference to FIGS.

In FIG. 1, the 1st heat-medium line Lb comprises the outdoor unit 1, the indoor unit 2, the compressor 4, the pressure-reduction valve V3, and the four-way valve V4, and has comprised the compression type air conditioner. And the primary brine (for example, Freon R134) which is a heat medium flows in the heat medium line Lb.
The first heat medium line Lb includes lines Lb1 to Lb5.

Line Lb1 connects discharge port 4o of compressor 4 and port Vp1 of four-way valve V4.
The line Lb2 connects the port Vp2 of the four-way valve V4 and the connection port 21 of the indoor unit 2.
The line Lb3 connects the connection port 22 of the indoor unit 2 and the connection port 13 of the outdoor unit 1. A pressure reducing valve V3 is interposed in the line Lb3.
Line Lb4 connects connection port 14 of outdoor unit 1 and port Vp3 of four-way valve V4.
A line Lb5 connects the port Vp4 of the four-way valve V4 and the suction port 4i of the compressor 4.

The second heat medium line Lc interposes the indoor unit 2 and the air conditioner 3. A secondary brine (for example, water) that is a heat medium flows through the heat medium line Lc.
The second heat medium line Lc has a line Lc1 and a line Lc2.
The line Lc1 connects the connection port 31 of the air conditioner 3 and the connection port 23 of the indoor unit 2. The line Lc2 connects the connection port 24 of the indoor unit 2 and the connection port 32 of the air conditioner 3.

As shown in FIG. 1, the heat exchange system 100 includes a control unit 50 that is a control means. The control unit 50 is connected to the compressor 4, the pump 5, and the on-off valves V1 and V2 via the control signal line So.

Next, with reference to FIG. 2, the switching control between cooling and heating when operating the air conditioner 3 of FIG. 1 will be described.
In step S1 of FIG. 2, the air conditioner 3 is operated by operating a control panel (not shown) including the control unit 50 by automatic control or manual operation.
In step S2, it is determined whether the heating operation or the cooling operation is performed by automatic control or manual operation, and the determined operation is performed.

If the heating operation is to be executed (“heating” in step S2), the control unit 50 closes the on-off valves V1, V2 of the piping system La immersed in the water tank 150, and is interposed in the piping system La. The pump 5 is stopped (step S3).
In step S4, the four-way valve V4 is switched to the heating side. When the four-way valve V4 is switched to the heating side, the port Vp1 and the port Vp2 of the four-way valve V4 communicate with each other, and the port Vp3 and the port Vp4 communicate with each other (see FIG. 3).

On the other hand, if the cooling operation is to be executed ("cooling" in step S2), the control unit 50 opens the on-off valves V1, V2 interposed in the piping system La, and the pump 5 interposed in the piping system La. Is operated (step S5).
Then, the process proceeds to step S6, and the four-way valve V4 is switched to the cooling side. When the four-way valve V4 is switched to the cooling side, the port Vp1 and the port Vp3 of the four-way valve V4 communicate with each other, and the port Vp2 and the port Vp4 communicate with each other (see FIG. 4).

When step S4 or step S6 is completed, the process proceeds to step S7, and the control unit 50 operates the compressor 4 interposed in the first heat medium line Lb to execute the heating operation or the cooling operation, and then performs step S8. Proceed to
In step S8, the control unit 50 determines whether or not an operation for ending the heating operation or the cooling operation has been performed. If the end operation has been performed (step S8 is YES), the control is ended.
On the other hand, if the end operation has not been performed (NO in step S8), the process returns to step S2, and step S2 and subsequent steps are repeated.

A case where the heating operation is performed will be described with reference to FIG.
In the heating operation shown in FIG. 3, as described above, the on-off valves V1 and V2 interposed in the piping system La are closed, and the pump 5 interposed in the piping system La is stopped.
Then, the four-way valve V4 interposed in the first heat medium line Lb is switched to the heating side, the port Vp1 and the port Vp2 of the four-way valve V4 are communicated, and the port Vp3 and the port Vp4 are communicated.
Then, the compressor 4 is operated, and the heat medium (for example, Freon R134) is compressed into high-temperature and high-pressure gas-phase Freon and discharged from the discharge port 4o of the compressor 4.

The high-temperature and high-pressure gas-phase Freon discharged from the compressor 4 passes through the line Lb1, the port Vp1, the port Vp2, and the line Lb2 of the four-way valve V4, and the heat of the indoor unit 2 from the first connection port 21 of the indoor unit 2. It flows into the exchange part 2h.
The high-temperature and high-pressure gas-phase Freon in the heat exchange part 2h of the indoor unit 2 flows through the second heat medium line Lc (the heat medium flowing into the indoor unit 2 from the air conditioner 3 via the line Lc1: water, for example, ) And heat exchange. By the heat exchange in the indoor unit 2, the water (heat medium) flowing through the heat medium line Lc is warmed, and the high-temperature and high-pressure gas phase freon loses heat of vaporization and condenses to become high-pressure liquid phase freon.
The water heated by the indoor unit 2 is sent to the air conditioner 3 from the line Lc2, and is radiated by a radiator (not shown) in the air conditioner 3 to heat the space where the air conditioner 3 is installed. After radiating heat with a radiator (not shown), water as a heating medium is sent again to the indoor unit 2 via the line Lc1.

On the other hand, the high-pressure liquid phase CFC condensed in the indoor unit 2 flows from the connection port 22 of the indoor unit 2 through the line Lb3 to the heat exchange unit 1h in the outdoor unit 1 from the connection port 13 of the outdoor unit 1. When the high-pressure liquid phase chlorofluorocarbon flows through the line Lb3, the pressure is reduced by the pressure reducing valve V3 to become low-pressure liquid-phase chlorofluorocarbon.
In the heat exchanging unit 1 h of the outdoor unit 1, the low-pressure liquid phase CFC exchanges heat with the vapor phase CO ₂ flowing through the piping system La immersed in the water tank 150. Then, in order to put the heat of condensation of the vapor phase CO ₂ to the low-pressure liquid phase Freon, a gas phase CO ₂ flowing through the piping system La condenses, the liquid phase CO _2. That is, in the heat exchange section 1h, the vaporization heat low pressure liquid phase flon and a gas phase CO ₂ is a latent heat exchanging heat condensation heat of the vapor phase CO _2, so-called - performing "latent latent heat exchange". As a result, the low-pressure liquid phase chlorofluorocarbon vaporizes and becomes low-pressure gas-phase chlorofluorocarbon.
The low-pressure gas phase CFC vaporized in the outdoor unit 1 flows into the inlet 4i of the compressor 4 via the connection port 14, the line Lb4, the ports Vp3 and Vp4 of the four-way valve V4, and the line Lb5. Then, it is compressed by the compressor 4 to become a high-temperature and high-pressure gas-phase chlorofluorocarbon and discharged from the discharge port 4o.

On the other hand, the liquid phase CO ₂ condensed in the outdoor unit 1 is discharged from the connection port 11 of the outdoor unit 1, flows through the line La2, and descends due to its own weight. When flowing through the line La2, the liquid phase CO ₂ is supplied with heat of vaporization by the water W in the water tank 150, and changes in phase to gas phase CO ₂ .
Since the on-off valves V1 and V2 are closed during the heating operation, CO ₂ flowing through the line La2 flows from the branch point B1 to the bypass La5 and flows from the branch point B2 to the line La3.

The CO ₂ flowing into the line La3 is vaporized by sufficiently supplying the heat held by the water W in the water tank 150.
Here, the liquid phase CO ₂ discharged from the outdoor unit 1 has a higher specific gravity than the gas phase CO ₂ . Therefore, gas-phase CO ₂ in line La3 rises through the line La3 as extruded in a liquid phase CO _2. Therefore, it is not necessary to operate the CO ₂ transport pump 5 during the heating operation.
The gas phase CO ₂ that has risen in the line La3 flows into the outdoor unit 1 from the connection port 12. Then, as described above, heat of condensation is introduced into the low-pressure gas-phase chlorofluorocarbon.

Next, with reference to FIG. 4, the case where the cooling operation is performed will be described.
In the cooling operation of FIG. 4, as described above, the opening / closing valves V1 and V2 interposed in the piping system La are opened, and the pump 5 interposed in the piping system La is operated at the same time.
In the piping system La, the liquid phase CO ₂ boosted by the pump 5 ascends the discharge port 5o, the line La1, the on-off valve V1, and the line La2. And it flows in into the heat exchange part 1h in the outdoor unit 1 via the connection port 11. FIG.

In the outdoor unit 1, the liquid phase CO ₂ exchanges the heat of vaporization with the high-pressure vapor phase CFC discharged from the discharge port 4 o of the compressor 4. The liquid phase CO ₂ to which the heat of vaporization is input becomes gas phase CO ₂ and flows into the suction port 5i of the pump 5 via the connection port 12, the line La3, the on-off valve V2, and the line La4.
Here, since the negative pressure of the suction port 5 i of the pump 5 acts on the line La 3, the vapor phase CO ₂ vaporized by the outdoor unit 1 descends toward the water tank 150 along the line La 3.
The gas phase CO ₂ is condensed by throwing away the heat of condensation into the water W in the water tank 150 while descending the line La3, and becomes liquid phase CO ₂ . Then, due to the negative pressure at the suction port 5 i of the pump 5, the liquid phase CO ₂ flows through the line La 4 without being branched into the line La 5 and is sucked into the suction port 5 i of the pump 5.

During the cooling operation, the four-way valve V4 interposed in the first heat medium line Lb is switched to the cooling side, the port Vp1 and the port Vp3 of the four-way valve V4 communicate, and the port Vp2 and the port Vp4 communicate.
The compressor 4 is activated, and the Freon R134, which is a heat medium, is compressed and discharged from the discharge port 4o as high-temperature and high-pressure gas-phase Freon.

The high-temperature and high-pressure gas-phase Freon discharged from the compressor 4 passes through the line Lb1, the port Vp1, the port Vp3, and the line Lb4 of the four-way valve V4 and from the connection port 14 of the outdoor unit 1 to the heat exchange section 1h of the outdoor unit 1. Flow into.
In the heat exchange section 1h of the outdoor unit 1, the high-temperature and high-pressure gas-phase Freon introduces heat of condensation into the liquid-phase CO ₂ flowing into the connection port 11 from the line La2 of the piping system La (conducts heat exchange) and condenses. It becomes a high-pressure liquid phase CFC. At that time, the liquid phase CO ₂ of the piping system La is vaporized.

The high-pressure liquid phase chlorofluorocarbon condensed in the outdoor unit 1 is discharged from the connection port 13 to the line Lb3, and is decompressed by the pressure reducing valve V3 interposed in the line Lb3 to become low-pressure liquid-phase chlorofluorocarbon. The low-pressure liquid phase freon flows into the heat exchanging part 2h of the indoor unit 2 from the connection port 22.
In the heat exchange part 2h, the low-pressure liquid phase CFC flowing through the first heat medium line Lb exchanges heat with water (hot water) flowing through the second heat medium line Lc, and heat of vaporization is input. It becomes a low-pressure gas phase CFC. At that time, the temperature of the water flowing through the second heat medium line Lc is lowered by the amount of heat supplied to the chlorofluorocarbon flowing through the first heat medium line Lb.
In other words, in the indoor unit 2, the sensible heat of water (heat medium) flowing through the second heat medium line Lc and the latent heat of chlorofluorocarbon flowing through the first heat medium line Lb are heat-exchanged (sensible heat). -Latent heat exchange).

The cold water discharged from the connection port 23 of the indoor unit 2 flows into the air conditioner 3 from the connection port 31 of the air conditioner 3 and cools the space where the air conditioner is installed. The refrigerant (water) cools the room air in the air conditioner 3 and is sent from the connection port 32 to the connection port 24 of the indoor unit 2 via the line Lc2.
On the other hand, the low-pressure gas phase CFC vaporized in the indoor unit 2 is sucked from the intake port 4i of the compressor 4 via the connection port 21 of the indoor unit 2, the line Lb2, the ports Vp2, Vp4 of the four-way valve V4, and the line Lb5. It is. And it compresses with the compressor 4 and is discharged from the discharge port 4o as a high pressure gaseous-phase Freon.

In the case of the heating operation shown in FIG. 3, the CO ₂ flowing through the piping system La circulated well including the region immersed in the water tank 150 without operating the pump 5.
On the other hand, in the case of the cooling operation shown in FIG. 4, as described above, CO ₂ flowing through the piping system La does not circulate in the piping system La unless the pump 5 is operated.
The pump 5 and the lines La1, La4, and La5 will be described later with reference to FIGS.
Here, in both the heating operation shown in FIG. 3 and the cooling operation shown in FIG. 4, in the outdoor unit 1, CO ₂ flowing through the piping system La and Freon flowing through the first heat medium line Lb exchange heat of vaporization. Then, since so-called “latent heat-latent heat exchange” is performed, a large amount of heat is exchanged, and the efficiency is increased.

In FIG. 1, FIG. 3, FIG. 4, the piping system La in the water tank 150 through which the heat medium flows is configured by a U-shaped tube in which a reciprocating path is configured separately. In the illustrated embodiment, You may comprise the piping in the water tank 150 which concerns on a double pipe.
Such a double tube will be described with reference to FIGS.
In FIG. 5, the double pipe 9 constituting the piping system La is composed of an inner pipe 91 and an outer pipe 92.
As shown in FIG. 5, during heating (see FIG. 3), the liquid phase CO ₂ sent from the outdoor unit 1 descends the inner pipe 91 of the double pipe 9.

Since the liquid phase CO ₂ has a higher specific gravity than the gas phase CO ₂ , it falls downward due to its weight.
When the liquid phase CO ₂ is supplied with heat of vaporization from the water in the water tank 150, the liquid phase CO ₂ is vaporized to become vapor phase CO ₂ . Since the vapor phase CO ₂ is the specific gravity is smaller than the liquid-phase CO _2, and raising the outer tube 92 of the double tube 9 toward the outdoor unit 1.
That is, at the time of heating in FIG. 3, the liquid phase CO _{2 to} be sent into the water W in the water tank 150 falls down due to its own weight in the inner pipe 91, and the gas phase CO ₂ returning from the water W in the water tank 150 is Since the outer pipe 92 is raised, there is no need to supply power from the outside for CO ₂ as a heating medium to flow through the double pipe 9.

At the time of cooling described with reference to FIG. 4, as shown in FIG. 6, the gas phase CO ₂ sent from the outdoor unit 1 moves down the outer tube 92 of the double tube 9. Then, CO ₂ in CO ₂ in the vapor phase and the heat of vaporization and condensed was poured into water W in the water tank 150 the liquid phase, towards the outdoor unit 1, to increase the inner tube 91 of the double pipe 9.
Here, unlike cooling, during heating, the vapor phase CO ₂ having a small specific gravity is lowered and the liquid phase CO ₂ having a small specific gravity is raised, so that power is required.

Therefore, as shown in Figure 7, the first on-off valve Vb1 on the bottom of the outer tube 92 of the double pipe 9 is provided with a pump 5 for CO ₂ recycled to the first.
A second on-off valve Vb2 is attached to the lower end of the inner pipe 91. Here, when the second opening / closing valve Vb2 is opened, the tip of the inner tube 91 communicates with the outer tube 92, and when the second opening / closing valve Vb2 is closed, the tip of the inner tube 91 is closed.
The discharge port of the pump 5 and the vicinity of the bottom of the inner pipe 91 are connected by a line 93, and a third on-off valve Vb 3 is interposed in the line 93.

At the time of heating, as shown in FIG. 8, the first on-off valve Vb1 and the third on-off valve Vb3 are closed, and the second on-off valve Vb2 is opened.
As described above, during heating, the liquid phase CO ₂ descending from the inner pipe 91 exchanges heat with the water W in the water tank 150 and is supplied with vaporization heat to become gas phase CO ₂ . Then, the gas phase CO ₂ flows into the vicinity of the bottom portion of the outer tube 92 via the second on-off valve Vb2, and ascends the outer tube 92 from the bottom portion of the outer tube 92. Here, even if gas phase CO ₂ and liquid phase CO ₂ are mixed and flow into the outer pipe 92 as a so-called “gas phase two-phase flow”, they exchange heat with the water W in the water tank 150, It becomes gas phase CO ₂ completely and rises to the outdoor unit 1 side.

Although not shown, when the liquid phase CO ₂ is not vaporized in the water W in the water tank 150, a mechanism (for example, a heating mechanism) that promotes vaporization can be provided.

At the time of cooling, as shown in FIG. 9, the second on-off valve Vb2 at the tip of the inner tube 91 is closed, the first on-off valve Vb1 and the third on-off valve Vb3 are opened, and the pump 5 is operated.
By operating the pump 5, a negative pressure acts in the outer pipe 92, so that gas phase CO ₂ having a small specific gravity falls.
The gas-phase CO ₂ that has descended the outer pipe 92 is condensed while discharging heat of vaporization into the water tank 150 in the middle of descending. Then, it is sucked into the pump 5 as a liquid phase CO _2. The liquid phase CO ₂ discharged from the pump 5 is pumped from the inner pipe 91 to the outdoor unit 1 via the line 93 and the third on-off valve Vb3.

As described with reference to FIGS. 5 to 9, whether the heating medium that exits the outdoor unit 1 and the heating medium that enters the outdoor unit 1 flows through the inner pipe 91 of the double pipe 9 during cooling and heating. The difference is whether it flows through the outer tube 92 of the double tube 9.
FIG. 10 schematically shows the configuration of the piping at the outdoor unit side end (upper end) of the double pipe 9.
10, the line La2 shown in FIGS. 1 to 3 is connected to the upper end of the inner pipe 91 in the double pipe 9, and the line La3 shown in FIGS. 1 to 3 is connected to the upper end of the outer pipe 92. ing.

Note that there are cases where the directions of flow of CO ₂ flowing through the piping system La and the flon flowing through the first heat medium line Lb are different from those shown in FIGS. 1 to 3 during cooling and heating.
In order to cope with such a case, as shown in FIG. 11, four valves Va1 to Va4 are interposed on the piping system La side, and the line La2 and the line La3 are connected to either the inner pipe 92 or the outer pipe 93. It is also possible to configure such that communication is possible.

In FIG. 11, a line La 2 that communicates with the connection port 11 of the outdoor unit 1 and a line La 3 that communicates with the connection port 12 of the outdoor unit 1 communicate with the outer tube 92. The line La2 is provided with an on-off valve Va1, and the line La3 is provided with an on-off valve Va2.
A line La6 branches from a branch point Ba2 of the line La2, and communicates with the inner pipe 91. Further, a line La7 branches from a branch point Ba3 of the line La3 and communicates with the inner pipe 91.
The line La6 is provided with an on-off valve Va3, and the line La7 is provided with an on-off valve Va4.

The 1st modification of the double tube 9 demonstrated with reference to FIGS. 5-11 is shown by FIG.
In the first modified example of FIG. 12, the outer tube 92A of the double tube 9A is uneven in the longitudinal direction (centerline CL direction). By forming such irregularities, the surface area is increased and the heat exchange efficiency is increased.
Although not shown, the inner tube 91A of the double tube 9A may also have irregularities in the longitudinal direction.

FIG. 13 shows a second modification of the double tube 9.
In the second modification of FIG. 13, the outer tube 92B of the double tube 9B is provided with irregularities in the circumferential direction, thereby increasing the surface area and increasing the heat exchange efficiency.
In the second modified example, although not shown, circumferential unevenness may be formed on the inner tube 91B of the double tube 9B.
Further, as a modification of the double pipe 9, although not shown, it is possible to provide fins on the outer pipe (or the outer pipe and the inner pipe) of the double pipe.

According to the first embodiment, CO ₂ is used as the heat medium, and the heat of vaporization (condensation heat) of CO ₂ is input to the heat medium by heat exchange with the water in the water tank 150, or the heat The water is discharged from the medium to the water in the water tank 150. Then, so-called “latent heat-sensible heat exchange” is performed by the latent heat of the CO ₂ heat medium and the sensible heat of the water W in the water tank 150.
Here, “latent heat-sensible heat exchange” is capable of recovering or discharging a large amount of heat per unit amount of heat medium as compared with “sensible heat-sensible heat exchange”. Become.

In addition, CO ₂ has a larger heat capacity than the brine used in the prior art.
Therefore, according to the first embodiment, the heat medium can efficiently recover the amount of heat held by the water in the water tank 150, or the heat can be efficiently discharged to the water W in the water tank 150. The piping system La (double tube 9) immersed in the water W in the water tank 150 can be shortened and made thinner.
Therefore, when the piping system La (double pipe 9) is immersed in the water W in the water tank 150, it is not necessary to excavate to a deep underground area, and a large space is not required for pipe embedding.

In the case of the conventional technology using geothermal heat using liquid phase brine as the heat transfer medium, the underground piping system through which the liquid phase brine flows is arranged along the foundation pile, or in the foundation pile. Middle pipes must be arranged, which causes extra costs when foundation piles are constructed.
In addition, if the underground piping through which the brine flows is not arranged in the vicinity of the underground pile, a well for burying the underground piping must be excavated to a deep underground region, and costs for that are generated. End up.
According to the first embodiment, the piping system La (double pipe 9) immersed in the water W in the water tank 150 can be shortened and thinned, so that the costs as described above do not occur.

In the first embodiment, the pipe system La to be immersed in the water W in the water tank 150 is constituted by the double pipe 9.
As described above, during the heating operation, the liquid phase CO ₂ having a large specific gravity descends the inner pipe 91 of the double pipe 9 and the amount of heat (vaporization heat) held by the water in the water tank 150 is input to vaporize the gas. Since the phase CO ₂ ascends the outer pipe 92 of the double pipe 9, no external power is required when the CO ₂ as the heat medium circulates in the piping system La.
Therefore, the operating cost during heating can be reduced.

FIG. 14 shows the control in the first embodiment.
According to the inventor's research and experiment, when the temperature of the heating medium (CO ₂ ) in the piping system from the water tank 150 is 5 ° C. to 40 ° C., the heating efficiency or the cooling efficiency is most improved. doing.
When the temperature of the carbon dioxide flowing through the area exiting the water storage facility is higher than 40 ° C., the heat exchange efficiency is lowered during cooling. On the other hand, when the temperature of the carbon dioxide flowing through the area exiting the water storage facility is lower than 5 ° C., the pressure of the heat medium in the piping system La becomes low, and the carbon dioxide that is the heat doubler is naturally circulated. In this case, it becomes difficult for carbon dioxide to circulate in the piping system La.

The temperature of CO ₂ sent from the outdoor unit 1 to the water W in the water tank 150 depends on the temperature (pressure) of CO ₂ at that time and the amount of the heat medium CO _{2 in} the entire system.
Therefore, in FIG. 14, in response to the temperature (pressure) of CO ₂ sent from the outdoor unit 1 to the water W in the water tank 150, the heat medium (CO ₂ ) in the piping system exiting from the water tank 150. as the temperature is 5 ° C. to 40 ° C., it illustrates a configuration for controlling the amount of CO ₂ in the overall system.
In FIG. 14, CO ₂ amount, a degree of opening of the interposed a flow regulating valve Vc to the inflow path (CO ₂ supply line) Lc from CO ₂ source 10 is connected to the piping system La9 in the water tank 150 It is controlled by the opening degree of the discharge valve Va (having a function as a flow rate adjusting valve) interposed in the discharge system Le.

Also in FIG. 14, the outdoor unit 1 and the piping system La9 in the water tank 150 are configured in a closed circuit by the piping La (La20, La30).
In FIG. 14, the CO ₂ piping system La9 immersed in the water of the water tank 150 is constituted by a single pipe, not a double pipe, and is expressed as a U-shaped pipe.
In FIG. 14, the pipe La is composed of a line La20 and a line La30. The line La20 connects the connection point Pa2 and the connection port 11 of the outdoor unit 1, and the line La30 connects the connection port 12 of the outdoor unit 1 and the connection point Pa3. In other words, the pipe La20 and the pipe La9 are connected at the connection point Pa2, and the pipe La9 and the pipe La30 are connected at the connection point Pa3.

The line La20 is provided with a discharge valve Va (flow rate adjusting valve).
In the line La20, a CO ₂ supply line Lc is connected to a region between the outdoor unit 1 and the discharge valve Va, and the CO ₂ supply line Lc communicates with the CO ₂ supply source 10.
The CO ₂ supply line Lc and CO ₂ supply amount regulating valve Vc is interposed, by controlling the opening degree of the CO ₂ supply amount regulating valve Vc, adjusting the supply amount of CO ₂ circulating piping system 9a is Is done.

In the line La20, a temperature sensor 6 (or a pressure sensor 40) is interposed in a region between the discharge valve Va and the connection point Pa2 in the pipe La9.
Here, in FIG. 14, the temperature sensor 6 (or the pressure sensor 40) is connected to the line La20. However, in an actual device, the CO ₂ that is the heat medium in the line La20 and the line La30 is the outdoor unit 1. It is inserted in the line of the side which flows out from.
If the line on the side where CO _{2 as the} heat medium flows into the outdoor unit 1 is switched between the heating operation and the cooling operation, the temperature sensor 6 (or the pressure sensor 4) is connected to the line La20 and the line La30. It is preferable to interpose both.

In FIG. 14, a control unit 50A, which is a control means, is provided.
The control unit 50A is connected to the temperature sensor 6 and the pressure sensor 40 via the input signal line Si.
The control unit 50A is connected to the exhaust valve Va and the CO ₂ supply amount adjusting valve Vc via the control signal line So.

Next, control of the CO ₂ supply amount will be described mainly with reference to FIG. 15 and also with reference to FIG.
In FIG. 15, in step S11, the temperature sensor 6 measures the temperature of CO ₂ flowing through the line La20 (for example, liquid phase CO ₂ during heating), or the pressure sensor 40 determines the CO ₂ pressure flowing through the line La20. Measurement is performed (step S12).

In step S13, the control unit 50A determines the opening degree of the discharge valve (flow rate control valve) Va.
Although not clearly shown, the control unit 50A has predetermined characteristics, that is, the CO ₂ temperature (or CO ₂ pressure) flowing through the line La20 and the water in the water tank 150 from the outdoor unit 1. The relationship (characteristics) with the amount of heat medium CO ₂ (hereinafter referred to as “predetermined amount of heat medium”) at which the temperature of the heat medium to be sent becomes a predetermined temperature is stored.
Further, the control unit 50A describes the amount of CO ₂ circulating through the piping system 9a at that time (hereinafter referred to as “CO ₂ circulation amount”) from the valve opening degree of the discharge valve Va and the CO ₂ supply amount adjusting valve Vc at that time. Have a function to request.
Further, the control unit 50A compares the CO ₂ circulation amount at that time with the valve openings of the discharge valve Va and the CO ₂ supply amount control valve Vc for setting the predetermined heat medium amount at that time, It has a function of determining the valve opening degree of the Va and CO ₂ supply amount adjusting valve Vc.

In the next step S14, the control unit 50A obtains the CO ₂ circulation amount from the valve openings of the discharge valve Va and the CO ₂ supply amount adjustment valve Vc at that time, and compares it with the predetermined heat medium amount or not. Determine whether.
If the CO ₂ circulation amount is appropriate (YES in step S14), the valve openings of the discharge valve Va and the CO ₂ supply amount adjustment valve Vc are maintained as they are (step S15), and the process proceeds to step S18.
If the CO ₂ circulation amount is too large (step S14 is “large”), the valve opening degree of the CO ₂ supply amount adjusting valve Vc is decreased and / or the valve opening degree of the discharge valve Va is increased (step S14). S16). Then, the process proceeds to step S18.
If the CO ₂ circulation amount is too small (step S14 is “small”), the valve opening degree of the CO ₂ supply amount adjusting valve Vc is increased and / or the valve opening degree of the discharge valve Va is decreased (step S14). S17). Then, the process proceeds to step S18.

In step S18, it is determined whether or not to end the operation of the system.
If the system operation is to be terminated (YES in step S18), the control is terminated.
If the operation of the system is to be continued (NO in step S18), the process returns to step S11, and steps S11 and after are repeated.
Other configurations and operational effects in FIGS. 14 and 15 are the same as those described with reference to FIGS.

In the first embodiment, as will be described later with reference to an experimental example, when performing a cooling operation, the temperature of carbon dioxide flowing in the region entering the water tank 150 of the piping system La (FIG. 26A, FIG. 28, the temperature indicated by the plot “◯”: the temperature measured by the temperature sensor 7 in FIG. 4) and the water temperature in the water tank 150 (FIG. 26A, the temperature indicated by the dotted characteristic curve in FIG. 28: FIG. The temperature difference of the temperature measured by the temperature sensor TW1 is set to 60 ° C. or less.
On the other hand, when performing the heating operation, the water temperature in the water tank 150 (the temperature indicated by the dotted characteristic curve in FIG. 27A: the temperature measured by the temperature sensor TW1 in FIG. 3) and the water in the piping system La The temperature difference from the temperature of carbon dioxide flowing through the region entering the tank 150 (the temperature indicated by the plot “◯” in FIG. 27A: the temperature measured by the temperature sensor 6 in FIG. 3) is 30 ° C. or less. .

Here, as described with reference to FIGS. 14 and 15, the temperature of CO ₂ sent from the outdoor unit 1 to the water tank 150 (FIG. 26 (A), FIG. 27 (A), FIG. The temperature indicated by “” depends on the temperature (pressure) of CO ₂ at that time and the amount of the heat medium CO _{2 in} the entire system.
Therefore, the water temperature in the water tank 1 (temperature measured by the temperature sensor TW1) and the temperature of the CO ₂ flowing in the area entering the water tank 1 of the pipe La (on the area side of the temperature sensors 6 and 7 entering the water tank 1). In order to control the temperature difference (measured temperature), the amount of CO _{2 in} the entire system 100 may be adjusted.

Regarding the first embodiment, when performing the cooling operation, the temperature difference between the temperature of carbon dioxide flowing through the region entering the water tank 150 of the piping system La and the water temperature in the water tank 150 is set to 60 ° C. or less, and the heating operation is performed. In order to reduce the temperature difference between the water temperature in the water tank 150 and the temperature of the carbon dioxide flowing through the region entering the water tank 150 of the piping system La to 30 ° C. or less, the amount of CO _{2 in} the entire system 100 The control for adjusting the frequency will be described with reference to FIGS. 29 and 30. FIG.
29, in order to adjust the amount of system 100 as a whole CO ₂ is, CO ₂ supply from the CO ₂ supply source 10 and, CO ₂ amount discharged through a discharge line Le that is connected to the piping La (CO ₂ emissions) may be controlled.
In order to control the CO ₂ supply amount from the CO ₂ supply source, for example, a flow rate adjusting valve Vc is provided in a piping system that connects the CO ₂ supply source and the piping La, and the valve of the flow rate adjusting valve What is necessary is just to control an opening degree. Further, in order to control the CO ₂ emission amount, for example, a discharge valve Va may be provided in the discharge system Le, and the valve opening degree of the discharge valve may be controlled.

That is, during the cooling operation, the temperature sensor 7 measures the temperature of carbon dioxide flowing through the region La30 entering the water tank 150 of the piping system La (the temperature indicated by the plot “O” in FIG. 26A and FIG. 28). The water temperature in the water tank 150 (the temperature indicated by the dotted characteristic curve in FIG. 26 (A) and FIG. 28) is measured by the temperature sensor TW1, and the measurement results of the temperature sensor 7 and TW1 are sent to the control unit 50B. The CO ₂ supply amount and the CO ₂ emission amount are adjusted so that the temperature difference in the measurement result of the temperature sensor 7 and TW1 is 60 ° C. or less by using the characteristic chart, characteristic formula, table, etc. stored in 50B.
On the other hand, during the heating operation, the water temperature in the water tank 150 (the temperature indicated by the dotted characteristic curve in FIG. 27A) is measured by the temperature sensor TW1, and the carbon dioxide flowing through the region La20 entering the water tank 150 of the piping system La. Is measured by the temperature sensor 6 and the measurement results of the temperature sensors TW1 and TW6 are sent to the control unit 50B and stored in the control unit 50B. The CO ₂ supply amount and the CO ₂ emission amount are adjusted so that the temperature difference in the measurement result of the temperature sensor 6 and TW1 is 30 ° C. or less by using the characteristic formula, the table, and the like.
The adjustment of the CO ₂ supply amount and the CO ₂ emission amount will be described with reference to FIG. 29 mainly based on FIG.

In step S11A in FIG. 30, CO ₂ temperature, or to measure the water temperature in the water tank 150 by the temperature sensor 7, TW1 during cooling operation, the heating operation, the water temperature or CO ₂ temperature in the water tank 150 by the temperature sensor TW1,6 Measure.
In step S13A, the system is controlled by the control unit 50B based on the temperature difference between the temperatures measured by the temperature sensors 7 and TW1 during the cooling operation and the temperature difference measured by the temperature sensors TW1 and TW during the heating operation. The total amount of CO ₂ or the valve openings of the exhaust valve Va and the CO ₂ supply amount adjusting valve Vc are determined. At the same time, the control unit 50B determines the amount of CO _{2 in} the entire system 100 at that time (control cycle) from the valve opening degree of the discharge valve Va and the CO ₂ supply amount adjusting valve Vc at that time (control cycle) , Described as “CO ₂ circulation amount”).

In step S14A, the control unit 50B includes a CO ₂ circulation rate at that time, the temperature difference (cooling at 60 ° C. or less, the heating time of 30 ° C. or less) and a predetermined CO ₂ circulation amount to the, the time (control cycle ) The amount of CO ₂ circulation in) is compared.
If the CO ₂ circulation amount is appropriate (YES in step S14A), the valve openings of the discharge valve Va and the CO ₂ supply amount adjustment valve Vc are maintained as they are (step S15A), and the process proceeds to step S18A.
If the CO ₂ circulation amount is too large (Step S14A is “large”), the valve opening degree of the CO ₂ supply amount adjusting valve Vc is decreased and / or the valve opening degree of the discharge valve Va is increased (Step S14A). S16A). Then, the process proceeds to step S18A.
If the CO ₂ circulation amount is too small (step S14A is “small”), the valve opening degree of the CO ₂ supply amount adjustment valve Vc is increased and / or the valve opening degree of the discharge valve Va is decreased (step S14A). S17A). Then, the process proceeds to step S18A.
In step S18, it is determined whether or not to end the system operation. If the system operation is to be continued (NO in step S18), step S11 and subsequent steps are repeated.
With the control described with reference to FIGS. 29 and 30, the temperature difference (60 ° C. or lower during cooling, 30 ° C. or lower during heating) can be maintained by adjusting the CO ₂ circulation amount of the system 100.
Other configurations and operational effects in FIGS. 29 and 30 are the same as those described with reference to FIGS.

FIG. 16 shows a modification of the first embodiment.
In FIG. 1 to FIG. 14, only the air conditioning load (second heat medium line Lc interposing the air conditioner 3) is supplied to the first heat medium line Lb as the thermal load via the indoor unit 2 (heat Connected).
On the other hand, in FIG. 16, a hot water supply load 8 is also connected (thermally) to the first heat medium line Lb as a thermal load.
In FIG. 16, a hot water supply load (for example, a hot water heater) 8 is interposed in a line Lb2 that connects the port Vp2 of the four-way valve V4 and the connection port 21 of the indoor unit 2 in the first heat medium line Lb.
Hot water supply by the water heater 8 is performed in the same heating operation as the heating operation of the first embodiment described in FIG.
Although not shown, it is possible to omit the air conditioning load and provide only the hot water supply load 8.
Other configurations and operational effects in the modified example of FIG. 16 are the same as those of the embodiment of FIGS.
In addition to this, although not shown, the four-way valve V4, the lines La1 and La4 in the water tank 150, and the pump 5 are omitted, and the first embodiment of FIGS. Is possible.
Even in such a case, a hot water supply load and an air conditioning load can be provided side by side or only a hot water supply load can be provided as in the modification of FIG.

FIG. 17 shows a second embodiment of the present invention.
In the first embodiment, only one system of CO ₂ piping is provided for heat exchange between the water W in the water tank 150 and the heat of vaporization (or condensation heat) of CO _{2 as} the heat medium.
However, in the second embodiment of FIG. 17, the CO ₂ piping is branched and two systems are provided, and in each of the two systems, the heat of vaporization (or heat of condensation) of CO ₂ that is a heat medium and the water tank 150 are provided. It is possible to exchange heat with the heat held by the water inside.

In FIG. 17, the CO ₂ pipe La circulating in the outdoor unit 1 is connected to the double pipe 9 </ _b > C in the vicinity of the upper edge of the water tank 150. A three-way valve V30 is interposed at the lower end of the double pipe 9C. Double pipes 9D and 9D having the same specifications are branched and connected to the three-way valve V30. Each of the double pipes 9D and 9D having the same specification is immersed in the water W of the water tank 150. The double tube 9D itself is the same as that shown in FIGS.
Here, in FIG. 17, so as not to affect thermally into CO ₂ mutually flowing through the double pipe 9D, or for heat exchange with CO ₂ to each other through the double tube 9D (double tube 9D The distance between the branched pipes 9D and 9D needs to be at least 1 m apart from each other so that the CO ₂ flowing through the pipes does not interfere with each other.

According to the second embodiment described above, since a plurality of piping systems 9D immersed in the water W of the water tank 150 are provided, the amount of heat held by the water in the water tank 150 can be efficiently recovered, or the water Heat can be discharged to the water W in the tank 150.
Other configurations and operational effects in the second embodiment of FIG. 17 are the same as those of the first embodiment of FIGS.

18 to 21 show a third embodiment of the present invention.
1 to 17, the CO ₂ piping system is immersed in the water W in the water tank 150. However, in the third embodiment of FIGS. 18 to 21, the CO ₂ piping system is immersed in the reservoir GH. The
In FIG. 18, the CO ₂ piping system La is connected to a spiral double pipe 9E. However, a straight double pipe 9C may be interposed, or the piping system La and the helical double pipe 9E may be connected.

In order to immerse the double pipe 9E, which is a CO ₂ piping system, in a spiral shape in the reservoir GH, the CO ₂ pipe (double pipe 9E) is made of a material having good flexibility. And it arrange | positions by inserting in the reservoir GH spirally.
Alternatively, when a CO ₂ pipe (double pipe 9E) is formed of a shape memory alloy, and the water temperature in the reservoir GH reaches 5 to 40 ° C., the spiral shape shown in FIG. 18 is obtained. What is necessary is just to memorize | store a shape and arrange | position in the reservoir GH in a spiral form.

According to the third embodiment of FIGS. 18 21, since the arranged pipe system 9E in the reservoir GH helically, circumferential length becomes three times the diameter, CO ₂ and water The depth direction dimension of the reservoir GH can be reduced to about 1/3 of that of the conventional one with a sufficient length necessary for heat exchange.
And as a result of the depth dimension of the reservoir GH decreasing, the cost for constructing the system is further reduced.
Here, CO ₂ flowing through each part in the spiral piping system 9E exchanges heat with each other (CO ₂ flowing through each part in the spiral piping system 9E has a thermal effect on each other. The helical pitch and diameter are preferably 1 m or more.

FIGS. 19-21 has shown the construction procedure of 3rd Embodiment.
In the construction of the third embodiment of FIGS. 19 to 21, first, as shown in FIG. 19, a vertical hole is excavated in the soil G, and the inner wall surface of the excavated vertical hole is covered with a binder or the like. , Prevent soil collapse. Therefore, the reservoir GH for arranging the piping system 9E is created. And as shown in FIG. 20, the helical piping system 9E is arrange | positioned in the reservoir GH.
Here, the pitch and diameter of the spiral piping system 9E are preferably 1 m or more and as small as possible. If the pitch and the diameter are 1 m or less, the CO ₂ flowing through each part in the spiral piping system 9E exchanges heat with each other (the CO ₂ flowing through each part in the spiral piping system 9E is mutually This is because if the pitch and diameter of the spiral piping system 9E are large, the diameter and depth of the reservoir GH must be increased.

After the spiral piping system 9E is arranged in the reservoir GH, the reservoir GH is filled with water W as shown in FIG.
Here, the water W may be groundwater. The temperature level of groundwater is comparable to that of soil G.
Other configurations and operational effects in the third embodiment of FIGS. 18 to 21 are the same as those of the embodiments of FIGS.

FIG. 22 shows a fourth embodiment of the present invention.
The fourth embodiment in FIG. 22 corresponds to a combination of the second embodiment in FIG. 17 and the third embodiment in FIGS.
In FIG. 22, the CO ₂ pipe La circulating through the outdoor unit 1 is connected to the double pipe 9C. A three-way valve V30 is interposed at the lower end of the double pipe 9C.
From the three-way valve V30, a double pipe 9D immersed in water and a spiral double pipe 9E are branched and connected.
The structure of the double tube 9D is the same as that described in FIGS. 5 to 13 of the first embodiment, and is the same use as the double tube 9C. On the other hand, the spiral double tube 9E is the same as the spiral double tube 9E of the third embodiment shown in FIGS.

According to 4th Embodiment of FIG. 22, the calorie | heat amount which the water in the water tank 150 hold | maintains can be collect | recovered more efficiently rather than each embodiment of FIGS.
Other configurations and operational effects in the fourth embodiment of FIG. 22 are the same as those of the embodiments of FIGS.

FIG. 23 shows a fifth embodiment of the present invention.
In the embodiment of FIG. 23, the double pipe branched from the three-way valve 3V is a spiral double pipe 9E as compared with the fourth embodiment of FIG.
Here, in order to prevent thermal interference between the spiral double pipes (CO ₂ pipes) 9E, at least 1 m needs to be separated in the closest part.

According to the fifth embodiment of FIG. 23, the amount of heat held by the water in the water tank 150 can be recovered more efficiently than in the fourth embodiment of FIG.

Other configurations and operational effects in the fifth embodiment of FIG. 23 are the same as those of the embodiments of FIGS.

FIG. 24 shows a sixth embodiment of the present invention.
In the sixth embodiment shown in FIG. 24, as in the fifth embodiment shown in FIG. 23, the double pipes branched from the three-way valve 3V are all arranged in a spiral shape. 9F is arrange | positioned so that the other spiral double tube 9E may be enclosed in the radial direction outer side of the other spiral double tube 9E (same as the double tube 9E of FIG. 23).
Even in this case, the spiral double pipes (CO ₂ pipes) 9E and 9F have a diametrical direction so that the spiral double pipes (CO ₂ pipes) 9E and 9F do not thermally interfere with each other. Is at least 1 m apart.
In addition, in each of the two spiral double tubes 9E and 9F, it is necessary to separate at least 1 m in the vertical direction (spiral pitch direction).

According to the sixth embodiment of FIG. 24, it is possible to reduce the space in the horizontal direction for arranging the branched double tubes 9E and 9F as compared with the fifth embodiment of FIG. Even if the length of the pipe 9F is shortened, the amount of heat recovered by the water in the water tank 150 can be maintained or increased.
Other configurations and operational effects in the sixth embodiment of FIG. 24 are the same as those of the embodiments of FIGS.

[Experimental example]
Next, an experimental example of the present invention will be described with reference to FIGS.
FIG. 25 shows an outline of the experimental apparatus used in the experimental example.
In FIG. 25, the experimental apparatus denoted as a whole by reference numeral 500 includes a first water tank 150, a heat pump HP, a second water tank 200, a first water tank 150, a piping system LaE communicating with the heat pump HP, a heat pump HP, and A piping system LcE communicating with the second water tank 200 is provided.
The second water tank 200 is provided as a thermal load corresponding to the air conditioner (including hot water floor heating) 3 shown in FIG. That is, the second water tank 200 indicates a thermal load.
Further, the heat pump HP in FIG. 25 corresponds to a compression type air conditioner having the outdoor unit 1, the indoor unit 2, the compressor 4, the pressure reducing valve V3, and the four-way valve V4 in FIG.

CO _{2 as a} heat medium flows in the piping system LaE, and a temperature sensor that measures the temperature of CO ₂ flowing through the piping system (see arrow Fa) from the heat pump HP to the first water tank 150. Ts1 is interposed. The temperature measured by the temperature sensor Ts1 is indicated by a plot “◯” in FIG. 26 (A), FIG. 27 (A), and FIG.
The piping system (see arrow Fb) from the first water tank 150 to the heat pump HP is provided with a temperature sensor Ts2 that measures the temperature of CO ₂ flowing therethrough. The temperature measured by the temperature sensor Ts2 is indicated by a plot “Δ” in FIG. 26 (A), FIG. 27 (A), and FIG.
In the 1st water tank 150, temperature sensor Ts3 for measuring the water temperature of the water stored there is provided. The water temperature in the water tank 150 measured by the temperature sensor Ts3 is indicated by a characteristic line indicated by a dotted line in FIG. 26 (A), FIG. 27 (A), and FIG.

In addition, a heat medium (for example, water) flows in the piping system LcE, and the heat medium (water) flowing therethrough is connected to the piping system (see arrow Fc) from the heat pump HP to the second water tank 200. A temperature sensor Ts4 for measuring the temperature is interposed. The temperature measured by the temperature sensor Ts4 is indicated by a plot “◯” in FIGS. 26 (B) and 27 (B).
The piping system (see arrow Fd) from the second water tank 200 toward the heat pump HP is provided with a temperature sensor Ts5 that measures the temperature of the heat medium (water) flowing therethrough. The temperature measured by the temperature sensor Ts5 is indicated by a plot “Δ” in FIGS. 26 (B) and 27 (B).

In the experimental example, the experimental device shown in FIG. 25 was operated, the temperature measured by the temperature sensors Ts1 to Ts5 was obtained, and the characteristics of the elapsed time from the start of the experimental device operation and the measured temperature were obtained.
FIGS. 26A to 26C, FIGS. 27A to 27C, and FIG. 28 show such characteristic curves of elapsed time-temperature characteristics.

FIG. 26 shows the experimental results regarding the cooling operation.
In FIG. 26, (A) shows the temperature characteristic of CO ₂ exiting the heat pump HP toward the first water tank 150 (time characteristic of the measurement result of the temperature sensor Ts1: plot “◯”), and the first water tank. The temperature characteristics of CO ₂ exiting 150 toward the heat pump HP (time characteristics of the measurement result of the temperature sensor Ts2: plot “Δ”), the condensation temperature of CO ₂ (characteristics indicated by a dark solid line), and the critical point of CO ₂ (Characteristics indicated by a thin solid line) and temperature characteristics in the water tank 150 (time characteristics of measurement results by the temperature sensor Ts3: characteristics indicated by dotted lines) are shown.

FIG. 26B shows the temperature characteristic of the heat medium (water) from the heat pump HP to the second water tank 200 (time characteristic of the measurement result of the temperature sensor Ts4: plot “◯”), and the second water tank. The temperature characteristic of the heat medium (water) returning from 200 to the heat pump HP (time characteristic of the measurement result of the temperature sensor Ts5: plot “Δ”) is shown.
26C shows the temperature of the heat medium (water) from the heat pump HP to the second water tank 200 in FIG. 26B (measurement result of the temperature sensor Ts4: plot “◯”), The characteristic of the temperature difference with the temperature of the heating medium (water) returning from the water tank 200 to the heat pump HP (measurement result of the temperature sensor Ts5: plot “Δ”) is shown, and was introduced into the second water tank 200 It shows the characteristics of heat quantity or cooling capacity.

FIG. 27 shows the experimental results regarding the heating operation.
In FIG. 27, the characteristic curves in (A) and (B) are the same as the characteristic curves in (A) and (B) of FIG.
FIG. 27C shows the characteristics of the heating capacity.

In (C) of FIG. 26 showing the cooling operation, the elapsed time (horizontal axis) is 2 min. In subsequent areas, the cooling capacity (vertical axis) is very high (22-23 kW).
Although not clearly shown in FIG. 26 (C), when a pipe with a diameter of 3 inches and a length of 50 m is buried underground and heat exchange is performed with geothermal heat, the cooling capacity is measured under the same conditions as in the experimental example. In this case, the cooling capacity was 5 kW. Compared with this value, it can be understood that the cooling capacity obtained in the experimental example is very high.

Similarly, in FIG. 27C illustrating the heating operation, the elapsed time (horizontal axis) is 30 min. In the area after exceeding, the heating capacity (vertical axis) has increased to a high value.
Although not explicitly shown in FIG. 27 (C), in the experiment of the inventor, a pipe having a diameter of 3 inches and a length of 50 m is buried underground and exchanged with geothermal heat under the same conditions as in the experimental example. When the heating capacity was measured, the heating capacity was 5 kW.
In FIG. 27C, the elapsed time (horizontal axis) is 30 min. The heating capacity in the region after exceeding the temperature reaches about 10 kW, and it is clear that the heating capacity is improved as compared with the case where heat exchange with geothermal heat is performed.
30 min. It is presumed that the heating capacity was also improved because the temperature of CO ₂ flowing in the water tank 150 was raised to the vicinity of the critical point and the specific heat of CO ₂ increased and the heat exchange efficiency was improved at the front and back stages.
From FIG. 26 (C) and FIG. 27 (C), according to this invention, it became clear that heat exchange efficiency improved and, as a result, cooling capacity and heating capacity improved.

In FIG. 26 (C) showing the cooling operation, 22 min. After a certain amount of time, the cooling capacity tends to decrease. The elapsed time is 54 min. Since then, the cooling capacity has dropped rapidly.
22 min. After a lapse of time, the temperature of CO ₂ flowing through the water tank 150 becomes higher than the critical point, and it becomes an area where the specific heat of CO ₂ decreases, and it is estimated that the heat exchange efficiency is lowered. And 54 min. When the time has elapsed, it is presumed that the temperature of CO ₂ flowing through the water tank 150 has further increased, and the specific heat has significantly decreased.
In the experimental apparatus shown in FIG. 25, the temperature of CO ₂ flowing in the water tank 150 cannot be detected, but the temperature of CO ₂ flowing into the water tank 150 (plot “◯”) and the outflow from the water tank 150 It is clear that if the temperature of CO ₂ (plot “Δ”) is higher than the critical point temperature (the thin solid line in FIG. 26A), the heat exchange efficiency is lowered and the cooling capacity is also lowered. It is.

On the other hand, in FIG. 27A showing the heating operation, 60 min. Even after the elapse of time, the temperature of CO ₂ flowing into the water tank 150 (plot “◯”) and the temperature of CO ₂ flowing out of the water tank 150 (plot “Δ”) are both critical point temperatures (FIG. 27). It is not separated from the thin solid line (A). For this reason, it is considered that the temperature of CO ₂ flowing in the water tank 150 is not separated from the critical point temperature.
Therefore, in FIG. 27C, the heat exchange efficiency of CO ₂ is not lowered, and the heating capacity is 60 min. It is presumed that high ability is maintained even after elapses.

26 and 27, it is clear that the cooling capacity and the heating capacity in the experimental apparatus do not decrease if the temperature of CO ₂ flowing out of the water tank 150 (plot “Δ”) is 40 ° C. or less.
Although not shown, the temperature of CO ₂ flowing into the water tank 150, the temperature of CO ₂ flowing out of the water tank 150, in a case where too temperature lower than the critical point temperature (5 ° C. or less), CO ₂ is In the case of natural circulation, it was found from the experiment using the experimental apparatus shown in FIG. 25 that the cooling capacity and the heating capacity decrease.
This is presumably due to the fact that the pressure of the heat medium in the piping system LaE has become low, and the circulation efficiency of the heat medium (CO ₂ ) in the piping system LaE has decreased.

FIG. 28 shows an experiment result during the cooling operation under an operating condition different from that in FIG. In other words, FIG. 28 is a characteristic diagram similar to FIG.
As shown in FIG. 28, during the cooling operation, the temperature between the water temperature in the water tank 150 (indicated by a dotted characteristic curve in FIG. 28) and the temperature of CO ₂ flowing into the water tank 150 (plot “◯”). The difference Δ is 60 ° C. or less.
Although not explicitly shown in FIG. 28, according to the inventor's experiment, during the cooling operation, the water temperature in the water tank 150 (shown by a dotted characteristic curve in FIG. 28) and the CO flowing into the water tank 150 are shown. It has been confirmed that when the temperature difference Δ with respect to the temperature of ₂ (plot “◯”) exceeds 60 ° C., the heating capacity decreases.
As a result, when performing the cooling operation, the temperature of CO ₂ flowing in the area entering the water storage facility (150, GH) of the piping system (La, 9) (FIG. 26 (A), plot “◯” in FIG. 28) Temperature shown: temperature measured by temperature sensor 7 in FIG. 4) and water temperature in water storage facility (150, GH) (FIG. 26A, temperature indicated by dotted characteristic curve in FIG. 28: temperature sensor in FIG. It was confirmed that the temperature difference of the temperature measured by TW1 should be 60 ° C. or less.

In FIG. 27A, during the heating operation, the water temperature in the water tank 150 (shown by a dotted characteristic curve in FIG. 27A) and the temperature of CO ₂ flowing into the water tank 150 (plot “◯”). ) And the temperature difference Δ is 30 ° C. or less.
Although not explicitly shown in FIG. 27, according to the inventor's experiment, during the heating operation, the water temperature in the water tank 150 (shown by the dotted characteristic curve in FIG. 27A) and the water tank 150 It has been confirmed that when the temperature difference Δ (see FIG. 27A) with the temperature of the inflowing CO ₂ (plot “◯”) exceeds 30 ° C., the heating capacity decreases.
As a result, when performing the heating operation, the water temperature in the water storage facility (150, GH) (the temperature indicated by the dotted characteristic curve in FIG. 27A: the temperature measured by the temperature sensor TW1 in FIG. 3), The temperature of CO ₂ flowing through the region entering the water storage facility (150, GH) of the piping system (La, 9) (the temperature indicated by the plot “◯” in FIG. 27A: the temperature measured by the temperature sensor 6 in FIG. 3) It was confirmed that the temperature difference from the above) should be 30 ° C. or less.

It should be noted that the illustrated embodiment is merely an example, and is not a description to limit the technical scope of the present invention.
In the illustrated embodiment, the water tank 150 and the reservoir GH are shown as the water storage facilities, but as the water storage facilities, a culvert or a groove (or open channel) with a depth enough to immerse the piping system through which the heat medium flows. It is also possible.

DESCRIPTION OF SYMBOLS 1 ... 1st heat exchanger / outdoor unit 2 ... 2nd heat exchanger / indoor unit 3 ... Air conditioner 4 ... Compressor 5 ... Pump 6, 7 ... Temperature sensor 8 ... water heater 9 ... double pipe 10 ... CO ₂ source 150 ... water tank

Claims (5)

A water storage facility (150, GH), a piping system (La) having a function of being immersed in water of the water storage facility (150, GH) and exchanging heat with water in the water storage facility (150, GH), and the piping An outdoor unit (1) connected to the system (La), a first heating medium line in which the outdoor unit (1), the indoor unit (2), a compressor (4), and a four-way valve (V4) are interposed. (Lb) and a second heat medium line (Lc) connecting the indoor unit (2) and the air conditioner (3), the heat medium flowing through the piping system (La) Is carbon dioxide, and a pump (5) is provided in the area of the piping system (La) immersed in water, and the discharge port (5o) of the pump (5) is connected to the first line (La1). To the first valve (V1) via the second line (La2). Then, it is connected to one connection port (11) of the outdoor unit (1), and the other connection port (12) of the outdoor unit (1) is connected to the second valve (La3) via a second valve (La3). V2) and the vicinity of the first valve (V1) in the second line (La2) and the vicinity of the second valve (V2) in the third line (La3) are bypass lines (La5) The bypass line (La5) bypasses the first and second valves (V1, V2) and the pump (5), and the compressor (4), the pump (5) and the first A control unit (50) for switching between cooling and heating by controlling the first and second valves (V1, V2) is provided, and the control unit (50) controls the first and second valves (V1, V2) during heating. Close and pump (5 The stops, heat exchange system, characterized in that opening the first and second valves (V1, V2) at the time of cooling, has the function of operating the pump (5). The piping system (La) is provided with a discharge valve (Va) and a carbon dioxide supply amount adjustment valve (Vc), and has a control unit (50A). The control unit (50A) has a discharge valve (Va). ) And the function of determining the carbon dioxide circulation amount from the valve opening degree of the carbon dioxide supply amount control valve (Vc), the function of determining whether the carbon dioxide circulation amount is appropriate by comparing the carbon dioxide circulation amount with a predetermined amount, If the carbon dioxide circulation amount is appropriate, the valve opening degree of the discharge valve (Va) and the carbon dioxide supply amount adjustment valve (Vc) is maintained, and if the carbon dioxide circulation amount is excessive, the valve of the discharge valve (Va). Increase the opening and / or decrease the valve opening of the carbon dioxide supply control valve (Vc), and if the carbon dioxide circulation is too small, decrease the valve opening of the discharge valve (Va) and / or Or increase the valve opening of the carbon dioxide supply control valve (Vc) Heat exchange system according to claim 1 which has a function of. The heat exchange system according to any one of claims 1 and 2, wherein a temperature of carbon dioxide flowing through a region exiting the water storage facility (150, GH) in the piping system (La) is set to 5C to 40C. In the case of performing cooling operation, the temperature difference between the temperature of carbon dioxide flowing through the region entering the water storage facility (150, GH) of the piping system (La) and the water storage facility (150, GH) is 60 ° C. or less. Item 3. The heat exchange system according to any one of Items 1 and 2. When performing the heating operation, the temperature difference between the water temperature in the water storage facility (150, GH) and the carbon dioxide flowing through the area entering the water storage facility (150, GH) of the piping system (La) is 30 ° C. or less. The heat exchange system according to claim 1.

Images