Refrigerant pipe

Abstract

To make it possible to lengthen a pipe while restraining volatility of a refrigerant from the pipe.SOLUTION: A refrigerant pipe constitutes a cooling cycle in which a liquid refrigerant to be directly or indirectly brought into contact with a heat receiving part and a heat dissipating part is circulated. The refrigerant pipe comprises an outer pipe, and a plurality of inner pipes provided in the outer pipe, and in which the refrigerant is circulated. The refrigerant having received heat in the heat receiving part flows through at least one of the inner pipes. The refrigerant having dissipated heat in the heat dissipating part flows through at least another of the inner pipes. The outer pipe is constituted so that the amount of the refrigerant to be volatilized therein is smaller than that in the inner pipes.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to refrigerant piping. [Background technology]

[0002] Patent Document 1 discloses a flexible hose used as a refrigerant passage in a refrigeration cycle. This flexible hose has a double-tube structure with an outer hose and an inner hose made of rubber that is loosely inserted into the outer hose at a predetermined interval. The inside of the outer hose is configured as a low-pressure refrigerant passage that is connected to the compressor intake port of the refrigeration cycle. The inside of the inner hose is configured as a high-pressure refrigerant passage that is connected to the compressor discharge port of the refrigeration cycle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 1-126489 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, in liquid cooling systems used to cool the temperature rise caused by heat generation inside the housing of electronic devices such as personal computers, non-metallic pipes are often used for the refrigerant. Such non-metallic pipes have the problem that the refrigerant gradually evaporates from the surface of the pipe (in other words, pipe surface volatilization). Furthermore, this pipe surface volatilization becomes more noticeable the longer the pipe length.

[0005] On the other hand, the flexible hose of Patent Document 1, which is intended for gaseous refrigerant connected to a compressor, cannot use the outer pipe, which is made of a metal pipe that is weak against internal pressure, as a path for high-pressure refrigerant, and it is necessary to use the outer pipe as a path for low-pressure refrigerant and the inner pipe as a path for high-pressure refrigerant. This configuration has the characteristic that heat is easily transferred from the inner pipe to the outer pipe because the high-pressure, high-temperature refrigerant flowing through the inner pipe is adjacent only to the outer pipe through the inner hose. In other words, the flexible hose of Patent Document 1 makes use of this characteristic to consider the inclusion of liquid phase in the compressor by arranging the high-temperature flow path on the inside to exchange heat with low-temperature refrigerant as much as possible, thereby suppressing the low-temperature refrigerant in gas phase flowing through the outer pipe from becoming liquid phase.

[0006] However, if the refrigerant used in the flexible hose of Patent Document 1 is changed to a liquid and applied to the cooling cycle in the liquid cooling system described above, as the hose length increases, the amount of heat exchange between the inner and outer tubes increases, resulting in a problem that the heat absorption of the cooling cycle does not function properly.

[0007] The present disclosure has been devised in consideration of the above-mentioned conventional circumstances, and has an object to provide a refrigerant pipe that enables long piping while suppressing volatility of the refrigerant from the pipe. [Means for solving the problem]

[0008] The present disclosure provides a refrigerant piping that constitutes a cooling cycle in which a liquid refrigerant that directly or indirectly contacts a heat receiving section and a heat dissipating section circulates, the refrigerant piping comprising an outer tube and a plurality of inner tubes disposed within the outer tube and through which the refrigerant circulates, the refrigerant that has received heat at the heat receiving section flows into at least one of the inner tubes, and the refrigerant that has dissipated heat at the heat dissipating section flows into at least one other of the inner tubes, and the outer tube is configured such that the amount of refrigerant that evaporates is less than that of the inner tubes.

[0009] The present disclosure also provides a refrigerant piping that constitutes a cooling cycle in which a liquid refrigerant that directly or indirectly contacts a heat receiving part circulates, the refrigerant piping comprising an outer pipe and a plurality of inner pipes provided within the outer pipe and through which the refrigerant circulates, the refrigerant that has received heat at the heat receiving part flows into at least one of the inner pipes and returns to the heat receiving part at the other end side of the outer pipe opposite the heat receiving part through at least one other of the inner pipes, and the outer pipe is configured such that the amount of refrigerant that evaporates is less than that of the inner pipes. Effect of the Invention

[0010] According to the present disclosure, it is possible to suppress the volatility of refrigerant from the piping while enabling long piping. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is an external view showing a schematic configuration of an electronic device including a refrigerant pipe according to a first embodiment; [Diagram 2] FIG. 1 is a schematic diagram of a liquid cooling system in an electronic device having a refrigerant pipe according to a first embodiment. [Diagram 3] FIG. 1 is a schematic diagram of a refrigerant pipe according to a modified example filled with liquid; [Figure 4] Schematic diagram showing a cross section of an outer tube and an inner tube filled with liquid, taken along a direction perpendicular to the tube axis. [Diagram 5] A schematic diagram showing a cross section of a refrigerant pipe in which a high-temperature inner pipe and a low-temperature inner pipe are inserted into a hollow outer pipe, the cross section being perpendicular to the pipe axis. [Figure 6] FIG. 3 is a schematic diagram of a liquid cooling system according to a modification in which the position of the pump is different from that in FIG. 2; [Figure 7] Schematic diagram showing modified examples of the cross-sectional shape of the inner tube [Figure 8] Schematic diagram of a modified example in which the cross-sectional shape of the outer tube is elliptical. [Figure 9] Schematic diagram of a modified example in which the cross-sectional shape of the outer tube is rectangular. [Figure 10] Schematic diagram of a modified example in which a transmission line is provided inside the outer tube [Figure 11] Schematic diagram of a refrigerant pipe according to a modified example in which the outer pipe is corrugated. [Figure 12] FIG. 1 is a schematic diagram of a refrigerant piping according to a modified example that does not require a heat dissipation unit to be connected; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, with reference to the drawings as appropriate, an embodiment specifically disclosing the refrigerant piping according to the present disclosure will be described in detail. However, more detailed explanation than necessary may be omitted. For example, detailed explanation of already well-known matters or duplicate explanation of substantially the same configuration may be omitted. This is to avoid the following explanation becoming unnecessarily redundant and to facilitate understanding by those skilled in the art. Note that the attached drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0013] FIG. 1 is an external view showing a schematic configuration of an electronic device equipped with refrigerant piping 11 according to a first embodiment. Many electronic devices have a power supply unit and heat generating units such as a CPU. As described above, in a water-cooling system used to cool a personal computer, if a normal non-metallic piping is used to connect between a heat receiving unit (CPU) and a heat dissipating unit, pipe surface volatilization, in which the refrigerant gradually volatilizes from the surface of the piping, becomes an issue. In the first embodiment, a refrigerant piping 11 that enables long piping while suppressing the volatility of the refrigerant from the piping will be described.

[0014] The electronic device has a heat generating section 13 and a cooling section 15 connected to the heat generating section 13 by a refrigerant pipe 11 .

[0015] 2 is a schematic diagram of a liquid cooling system 17 in an electronic device including a refrigerant pipe 11 according to the first embodiment. The refrigerant pipe 11 according to the first embodiment connects a heat receiving section 19 for cooling a heat generating section 13 to a heat dissipation section 21 provided in a cooling section 15. The heat receiving section 19, the heat dissipation section 21, and the refrigerant pipe 11 constitute a liquid cooling system 17. The liquid cooling system 17 constitutes a cooling cycle in which a low-temperature refrigerant 23 is sent to the heat receiving section 19 by a pump 25, and the heat of the high-temperature refrigerant 23 is taken away (dissipated) by the heat dissipation section 21, thereby sending the low-temperature refrigerant 23 back to the heat receiving section 19. The pump 25 can be provided, for example, at the downstream end of an inner pipe 27 through which the low-temperature refrigerant 23 flows. The position of the pump 25 is not limited thereto.

[0016] In the refrigerant piping 11 according to the first embodiment, a liquid refrigerant 23 (or a mixture of liquid and gas) that directly or indirectly comes into contact with the heat receiving section 19 and the heat dissipating section 21 circulates. The refrigerant piping 11 includes an outer pipe 29 and a plurality of inner pipes 27 that are provided inside the outer pipe and through which the refrigerant 23 circulates. In the refrigerant piping 11, the refrigerant 23 that has received heat at the heat receiving section 19 flows in at least one of the inner pipes 27, and the refrigerant 23 that has dissipated heat at the heat dissipating section 21 flows in at least the other one of the inner pipes 27.

[0017] That is, in the refrigerant piping 11, the heat receiving section 19 and the heat dissipating section 21 are connected by a double pipe structure consisting of an outer pipe 29 and an inner pipe 27 inserted into the outer pipe. In addition, in this refrigerant piping 11, one end of the outer pipe 29 is connected to the heat receiving section 19, and the other end of the outer pipe 29 is connected to the heat dissipating section 21.

[0018] At least one inner pipe 27 of the refrigerant piping 11 serves as a high temperature side inner pipe 33 that forms a high temperature side flow path 31 on the inside. The upstream end of the high temperature side inner pipe 33 is connected to the refrigerant outlet of the heat receiving section 19, and the downstream end is connected to the refrigerant inlet of the heat radiating section 21. The other at least one inner pipe 27 of the refrigerant piping 11 serves as a low temperature side inner pipe 37 that forms a low temperature side flow path 35 on the inside. The upstream end of the low temperature side inner pipe 37 is connected to the refrigerant outlet of the heat radiating section 21, and the downstream end is connected to the refrigerant inlet of the heat receiving section 19. The outer pipe 29 is configured to evaporate less refrigerant 23 than the inner pipe 27.

[0019] In the refrigerant pipe 11, the refrigerant 23 flowing through the high-temperature side flow passage 31 has a temperature higher than the outside air. Also, the refrigerant pipe 11 is configured so that the amount of heat exchanged from the high-temperature side flow passage 31 to the low-temperature side inner tube 37 is smaller than the amount of heat released from the high-temperature side flow passage 31 to the outside air.

[0020] FIG. 3 is a schematic diagram of a refrigerant pipe 11 according to a modified example filled with liquid. Note that pump 25 is omitted from FIG. 3. Refrigerant pipe 11 may contain liquid between outer pipe 29 and multiple inner pipes 27. That is, refrigerant pipe 11 has inner pipe 27 disposed in outer pipe filled with liquid. This liquid may be refrigerant 23. Examples of refrigerant 23 include ethylene glycol and propylene glycol. These refrigerants 23 may be diluted with water. Therefore, the liquid filled in the outer pipe may be water.

[0021] 4 is a schematic diagram showing a cross section of the outer tube 29 and inner tube 27 filled with liquid, taken in a direction perpendicular to the tube axis. The high temperature side inner tube 33 and the low temperature side inner tube 37 inserted into the outer tube 29 are preferably arranged apart from each other. This makes it possible to suppress heat transfer via the liquid from the high temperature side inner tube 33 to the low temperature side inner tube 37 in the outer tube 29 filled with liquid. In other words, it is possible to suppress a decrease in cooling efficiency.

[0022] 5 is a schematic diagram showing a cross section of the refrigerant pipe 11 in a direction perpendicular to the pipe axis, in which the high-temperature side inner pipe 33 and the low-temperature side inner pipe 37 are inserted into the hollow outer pipe. The refrigerant pipe 11 may be hollow with no liquid inside the outer pipe. In this case, the outer pipe is filled with air 39. In the refrigerant pipe 11 in which the outer pipe is filled with air 39, if the high-temperature side inner pipe 33 and the low-temperature side inner pipe 37 are separated by a certain distance, the air 39 can act as a heat insulating layer compared to the refrigerant pipe 11 filled with liquid, and therefore the transfer of heat from the high-temperature side inner pipe 33 to the low-temperature side inner pipe 37 can be significantly reduced.

[0023] Fig. 6 is a schematic diagram of liquid cooling system 17 according to a modified example in which pump 25 is located at a position different from that in Fig. 2. In liquid cooling system 17, pump 25 does not have to be provided between heat radiating unit 21 and heat receiving unit 19. For example, the downstream end of outer pipe 29 may pass through heat radiating unit 21 and be connected to pump 25. Then, the upstream end of inner pipe 27 passing through heat radiating unit 21 may be connected to the discharge port of pump 25.

[0024] More specifically, the downstream end of the high-temperature side inner pipe 33 is connected to the refrigerant inlet of a heat radiation pipe (not shown) housed in the heat radiation section 21. The refrigerant outlet of this heat radiation pipe is connected to the upstream end of the high-temperature side extension pipe 41 in the high-temperature side inner pipe 33 that penetrates the heat radiation section 21. The downstream end of the high-temperature side extension pipe 41 is connected to the liquid inlet of the pump 25. The liquid outlet of the pump 25 is connected to the upstream end of the low-temperature side extension pipe 43. The low-temperature side extension pipe 43 penetrates the heat radiation section 21 and is connected to the upstream end of the low-temperature side inner pipe 37. According to the liquid cooling system 17 of this modification, the pump 25 can be further removed from the cooling section 15, and the cooling section 15 can be configured more compactly. In this configuration, the outer pipe 29 provided between the heat radiation section 21 and the pump 25 may be omitted.

[0025] In the refrigerant pipe 11, the inner pipe 27 is configured to have lower thermal conductivity than the outer pipe 29. In this case, the outer pipe 29 can be preferably made of a material with high thermal conductivity, such as metal. The inner pipe 27 can be preferably made of a material with lower thermal conductivity than metal, such as rubber. As a result, the refrigerant pipe 11 can be configured with the outer pipe 29 made of metal and the inner pipe 27 made of rubber or the like.

[0026] 7 is a schematic diagram showing a modified example of the cross-sectional shape of the inner pipe. In the refrigerant pipe 11, the cross-sectional shape of the inner pipe 27 may be a sector shape with a flat surface facing the other inner pipe 27. In this refrigerant pipe 11, the facing surfaces of the inner pipes 27 are flat surfaces. That is, for example, two opposing inner pipes 27 are sector-shaped (approximately semicircular) with their flat surfaces facing each other. The two sector-shaped inner pipes 27 have an approximately circular outer periphery by being arranged with their flat surfaces facing each other. This allows the refrigerant pipe 11 to reduce the space between the multiple inner pipes 27 and the outer pipe 29.

[0027] FIG. 8 is a schematic diagram of a modified example in which the cross-sectional shape of the outer pipe is elliptical. The cross-sectional shape of the outer pipe 29 in the direction perpendicular to the pipe axis may be elliptical or oval. For example, in a refrigerant pipe 11 having two inner pipes 27, the two inner pipes 27 can be accommodated side by side along the major axis direction of the outer pipe 29 formed in an elliptical shape. With this refrigerant pipe 11, the cross-sectional area of ​​the refrigerant pipe 11 can be made smaller than when the outer pipe 29 is a perfect circle. This allows the refrigerant pipe 11 to be reduced in weight and increased in flexibility. In particular, when the outer pipe is filled with liquid, the amount of liquid filled can be reduced.

[0028] FIG. 9 is a schematic diagram of a modified example in which the cross-sectional shape of the outer pipe is rectangular. The cross-sectional shape of the outer pipe 29 in the direction perpendicular to the pipe axis may be rectangular. For example, in a refrigerant pipe 11 having two inner pipes 27, the two inner pipes 27 can be housed side by side along the long side of the outer pipe 29 formed in a rectangular shape. With this refrigerant pipe 11, the cross-sectional area of ​​the refrigerant pipe 11 can be made smaller than when the outer pipe 29 is a perfect circle. This allows the weight of the refrigerant pipe 11 to be reduced. In particular, when the outer pipe is filled with liquid, the amount of liquid filled can be reduced.

[0029] 10 is a schematic diagram of a modified example in which a transmission path 45 is provided inside the outer pipe. The refrigerant pipe 11 may have the transmission path 45 inside the outer pipe. In this case, the transmission path 45 is preferably arranged between a plurality of inner pipes. Since the outer pipe 29 of the refrigerant pipe 11 has the transmission path 45, optical fibers and electric wires such as signal lines and power lines can be passed inside the pipe. Since the refrigerant pipe 11 has the transmission path 45 between the two inner pipes 27, the transmission path 45 can be used as a barrier when heat transfers from the high-temperature side flow path 31 to the low-temperature side flow path 35.

[0030] FIG. 11 is a schematic diagram of the refrigerant pipe 11 according to a modified example in which the outer pipe 29 is corrugated. Note that the pump 25 is omitted in FIG. 11. The outer pipe 29 of the refrigerant pipe 11 may be corrugated. For example, a corrugated tube may be used as the corrugated outer pipe 29. The corrugated tube is formed in a tubular shape with a plurality of large diameter portions and small diameter portions alternately connected. A concave outer circumferential groove is formed between adjacent large diameter portions sandwiching a small diameter portion. Each of the large diameter portion and the small diameter portion has flexibility by expanding and contracting in a direction along the axis in terms of material. In addition, the small diameter portion is more vulnerable to bending load than the large diameter portion, so that the structure is also flexible. In addition, the corrugated tube may be a spiral corrugated tube in which a peripheral groove is formed in a spiral shape on the outer periphery of the outer pipe 29, so that the large diameter portion and the small diameter portion are alternately connected. Examples of materials for the corrugated tube include resin and metal (iron, aluminum, SUS, copper). The corrugated portion may be provided in only a part of the outer pipe 29 .

[0031] FIG. 12 is a schematic diagram of the refrigerant pipe 11 according to a modified example in which the heat radiating section 21 is not required to be connected. In FIG. 12, the pump 25 is omitted. In this refrigerant pipe 47, a double pipe structure is formed between the heat receiving section 19 and the other end side of the outer pipe 29 opposite to the heat receiving section 19, which is composed of the outer pipe 29 and the inner pipe 27 inserted into the outer pipe. In this refrigerant pipe 47, at least one inner pipe 27 is the high temperature side inner pipe 33 that forms the high temperature side flow path 31 on the inside. In addition, in the refrigerant pipe 47, at least one other inner pipe 27 is the low temperature side inner pipe 37 that forms the low temperature side flow path 35 on the inside. The high temperature side inner pipe 33 has an upstream end connected to the heat receiving section 19 and a downstream end connected to the upstream end of the low temperature side inner pipe 37. The low temperature side inner pipe 37 has a downstream end connected to the heat receiving section 19.

[0032] In this refrigerant piping 47, the outer pipe 29 is closed at the other end opposite the heat receiving section 19. At the other end of the closed outer pipe 29, the downstream end of the high temperature side inner pipe 33 is turned back 180° in the flow direction by a U-bent pipe joint or the like and connected to the upstream end of the low temperature side inner pipe 37. Note that the turned back section 49 may be formed by directly bending the inner pipe 27.

[0033] In this liquid cooling system 17, the heat receiving section 19 transfers heat to the low-temperature refrigerant 23 flowing in from the downstream end of the low-temperature side flow passage 35, and sends the high-temperature refrigerant 23 to the upstream end of the high-temperature side flow passage 31. The high-temperature refrigerant 23 sent to the upstream end of the high-temperature side flow passage 31 flows into the upstream end of the low-temperature side inner pipe 37 while transferring (radiating) heat from the high-temperature side inner pipe 33 to the outer pipe 29. If there is a temperature difference between the refrigerant 23 flowing into the upstream end of the low-temperature side inner pipe 37 and the outside air, the refrigerant 23 reaches the downstream end of the low-temperature side inner pipe 37 while further transferring (radiating) heat from the low-temperature side inner pipe 37 to the outer pipe 29, and is returned to the heat receiving section 19 again. As described above, the outer pipe 29 is configured to evaporate less refrigerant 23 than the inner pipe 27, and to have higher thermal conductivity than the inner pipe 27.

[0034] In the refrigerant pipe 47 as well, liquid may be present between the outer pipe 29 and the multiple inner pipes 27, similar to the above-mentioned refrigerant pipe 11.

[0035] Also, at least one of the inner pipes 27 of the refrigerant pipe 47 may be made of metal. In this case, the high temperature side inner pipe 33 of the refrigerant pipe 47 is made of metal. That is, the refrigerant pipe 47 is configured such that the high temperature refrigerant 23 having received heat at the heat receiving section 19 flows through the high temperature side inner pipe 33 made of metal.

[0036] Next, the operation of the above-mentioned refrigerant piping will be described.

[0037] The refrigerant piping 11 in embodiment 1 constitutes a cooling cycle in which liquid refrigerant 23 circulates in contact with the heat receiving section 19 and the heat dissipation section 21 directly or indirectly, and comprises an outer pipe 29 and a plurality of inner pipes 27 provided within the outer pipe and through which the refrigerant 23 circulates, the refrigerant 23 that has received heat at the heat receiving section 19 flows into at least one of the inner pipes 27, and the refrigerant 23 that has dissipated heat at the heat dissipation section 21 flows into at least the other one of the inner pipes 27, and the outer pipe 29 is configured so that the amount of refrigerant 23 that evaporates is less than that of the inner pipe 27.

[0038] In the refrigerant piping 11 according to the first embodiment, the heat receiving section 19 and the heat dissipating section 21 are connected by a double pipe structure consisting of an outer pipe 29 and an inner pipe 27 inserted into the outer pipe. The heat receiving section 19 transfers heat to the low-temperature refrigerant 23 that has flowed in from the downstream end of the low-temperature side flow passage 35, and sends the high-temperature refrigerant 23 to the upstream end of the high-temperature side flow passage 31. The heat dissipating section 21 removes heat (dissipates heat) from the high-temperature refrigerant 23 that has flowed in from the downstream end of the high-temperature side flow passage 31, and sends the low-temperature refrigerant 23 to the upstream end of the low-temperature side flow passage 35.

[0039] That is, the refrigerant pipe 11, the heat receiving section 19, and the heat dissipating section 21 constitute a cooling cycle in which the refrigerant 23 is sealed and circulated in liquid form. A liquid mainly composed of water is used as the refrigerant 23 in the liquid cooling system 17 having this cooling cycle. In the liquid cooling system 17, the refrigerant 23 circulates in a liquid phase state. There are sensible heat that changes the temperature of an object and latent heat that changes the state of an object. The liquid cooling system 17 obtains a cooling effect by transporting heat (sensible heat) mainly using the liquid phase as a medium. That is, the cooling cycle of the liquid cooling system 17 is significantly different from the refrigeration cycle of an automobile air conditioner that uses the flexible hose of Patent Document 1, which transports heat by utilizing latent heat due to a state change between the gas phase and the liquid phase.

[0040] The standard refrigeration cycle defined in the refrigeration cycle used in the air conditioner for automobiles in Patent Document 1 has an evaporation temperature of -15°C, a condensation temperature of +30°C, the intake gas of the compressor is dry saturated steam or heated gas (for example, -10°C at a heating degree of 5°C), and the liquid temperature before the expansion valve is +25°C. In the refrigeration cycle, when the load is reduced, the intake gas temperature of the compressor decreases, and some of the refrigerant 23 may return to the compressor in liquid phase without evaporating in the evaporator. When the intake gas of the compressor contains a large amount of liquid-phase refrigerant 23, liquid compression occurs, which causes damage. Therefore, in the refrigeration cycle used in the air conditioner for automobiles in Patent Document 1, the intake gas temperature just before being drawn into the compressor is heated by heat exchange using a flexible hose with a double-pipe structure, and consideration is given to suppressing the liquid phase from being mixed into the compressor. In other words, the double pipe structure of the flexible hose of Patent Document 1 actively exchanges heat from the high-temperature, high-pressure gas discharged from the compressor and flowing through inner pipe 27 with the gas-phase refrigerant flowing through outer pipe 29, heating the gas-phase refrigerant and preventing it from liquefying.

[0041] In contrast, liquid cooling system 17, which does not need to transport heat by changing between gas and liquid phases, operates by a cooling cycle in which refrigerant 23 circulates in liquid form between heat receiving section 19 and heat dissipating section 21. Since the cooling cycle of liquid cooling system 17 does not need to compress and condense refrigerant 23, a compressor is not required, and instead a liquid circulation pump (pump 25) is required.

[0042] That is, in the liquid cooling system 17, since the compression process is unnecessary, the refrigerant pressure in the cooling cycle is an almost constant low pressure as long as the head is ensured. Since the refrigerant pipe 11 does not need to be connected to a compressor, there is no restriction that a metal pipe, which is vulnerable to internal pressure, must be used for the low-temperature, low-pressure side flow path. For this reason, the double-pipe structure refrigerant pipe 11 used in the liquid cooling system 17 can use a metal pipe for the outer pipe 29 regardless of the type of flow path.

[0043] When the temperature of the heat dissipation section 21 is lower than the temperature of the heat receiving section 19, the high-temperature refrigerant 23 that has received heat at the heat receiving section 19 flows through the high-temperature side flow path 31, and the low-temperature refrigerant 23 that has dissipated heat at the heat dissipation section 21 flows through the low-temperature side flow path 35.

[0044] The refrigerant pipe 11 having a double pipe structure used in the liquid cooling system 17 does not need to exchange heat between the refrigerant 23 flowing through the high-temperature side flow path 31 and the refrigerant 23 flowing through the low-temperature side flow path 35. In terms of cooling performance, it is preferable that the heat exchange rate between the high-temperature side flow path 31 and the low-temperature side flow path 35 is low.

[0045] In the liquid cooling system 17, it is more preferable that the refrigerant 23, which has absorbed heat from the heat receiving section 19 and become hot, dissipates heat before it reaches the heat dissipation section 21. That is, in the refrigerant pipe 11 with a double pipe structure used in the liquid cooling system 17, it is efficient that the heat of the refrigerant 23 passing through the high temperature side flow path 31 is transferred to the outer pipe 29 and then transferred from the outer pipe 29 to the outside air. This allows the refrigerant pipe 11 to obtain a pre-cooling effect before being cooled by the heat dissipation section 21.

[0046] In the refrigerant pipe 11, if heat of the refrigerant 23 is transferred to the outside air, which has a lower temperature than the high-temperature refrigerant 23 flowing through the high-temperature side flow path 31, a large cooling effect can be obtained, and length restrictions can be eliminated in terms of cooling performance. In this case, a material with high thermal conductivity, such as a metal, can be suitably used for the outer pipe 29.

[0047] On the other hand, in consideration of the thermal insulation between the high temperature side flow path 31 and the low temperature side flow path 35, a material with a lower thermal conductivity than metal, such as rubber, can be suitably used for the low temperature side inner pipe 37. As a result, the refrigerant piping 11 can be configured with an outer pipe 29 made of metal and a low temperature side inner pipe 37 made of rubber or the like. By using a low temperature side inner pipe 37 made of rubber or the like, the refrigerant piping 11 can be manufactured at lower costs than when both the outer pipe 29 and the low temperature side inner pipe 37 are made of metal, and can also have improved flexibility and ease of installation.

[0048] Furthermore, by using a material of the high temperature side inner pipe 33 of the inner pipe 27 having a higher thermal conductivity than the low temperature side inner pipe 37, such as a metal or polyethylene resin, the heat of the high temperature refrigerant 23 can be dissipated to the outside air, improving the cooling performance. Therefore, the refrigerant piping 11 can be constructed such that the outer pipe 29 and the high temperature side inner pipe 33 are made of metal, and the low temperature side inner pipe 37 is made of rubber or the like.

[0049] The permeability of refrigerant 23, which is mainly composed of water, is higher in rubber than in metal. In other words, refrigerant 23 may evaporate from a rubber tube. In contrast, evaporating does not occur in a metal tube. For this reason, even if refrigerant 23 flowing in the inner tube of refrigerant piping 11 permeates from the inner tube to the outer tube, the total amount of refrigerant circulating does not decrease because the cooling cycle of liquid cooling system 17 is sealed. This allows refrigerant piping 11 to maintain a constant amount of refrigerant filled over a long period of time.

[0050] Therefore, in the refrigerant pipe 11, it is possible to suppress the volatility of the refrigerant 23 from the pipe, while allowing the pipe to be long.

[0051] Furthermore, in the refrigerant pipe 11 , liquid is contained between the outer pipe 29 and the plurality of inner pipes 27 .

[0052] In this refrigerant pipe 11, liquid is contained between the outer pipe 29 and the multiple inner pipes 27. Liquid has a higher thermal conductivity than air 39. For this reason, in the refrigerant pipe 11 in which the outer pipe is filled with liquid, heat of the refrigerant 23 flowing through the high-temperature side flow passage 31 can be transferred to the outer pipe 29 via the liquid with high thermal conductivity, and then transferred (dissipated) from the outer pipe 29 to the outside air.

[0053] In this case, if the inner pipe 27 is made of a material such as rubber that has a lower thermal conductivity than the liquid, the heat transferred to the liquid in the outer pipe is less likely to transfer to the low-temperature side flow path 35 in the outer pipe. In other words, the liquid is effectively used as a heat transfer medium from the high-temperature side flow path 31 to the outside air. If this liquid is the refrigerant 23, the outer pipe will be filled with the refrigerant 23, and even if the refrigerant 23 permeates from the inner pipe to the outer pipe, the total amount of the refrigerant 23 filled in the refrigerant pipe 11 can be kept unchanged.

[0054] In the refrigerant piping 11, the inner pipe 27 is configured to have lower thermal conductivity than the outer pipe 29. In the refrigerant piping 11, the inner pipe 27 through which the refrigerant 23 that has received heat at the heat receiving section 19 flows is configured to have higher thermal conductivity than the inner pipe 27 through which the refrigerant 23 that has dissipated heat at the heat dissipation section 21 flows.

[0055] In this refrigerant pipe 11, the thermal conductivity of the inner pipe 27 is lower than that of the outer pipe 29. That is, the inner pipe 27 is less able to transmit heat than the outer pipe 29, and the outer pipe 29 is more able to transmit heat than the inner pipe 27. In this case, a material with high thermal conductivity, such as metal, can be suitably used for the outer pipe 29. A material with lower thermal conductivity than metal, such as rubber, can be suitably used for the inner pipe 27.

[0056] In the refrigerant pipe 11, heat moves from the high-temperature side flow passage 31 into the outer pipe. The heat that has moved from the high-temperature side flow passage 31 tries to move from inside the outer pipe to the outside air or the low-temperature side flow passage 35. At this time, since the thermal conductivity of the inner pipe 27 is configured to be lower than that of the outer pipe 29, the heat in the outer pipe moves more easily to the outside air than to the low-temperature side flow passage 35. Therefore, the refrigerant pipe 11 can obtain a large cooling effect if the outer pipe 29 directly or indirectly comes into contact with the outside air, which has a lower temperature than the high-temperature refrigerant 23 flowing through the high-temperature side flow passage 31. As a result, the refrigerant pipe 11 can be freed from length limitations in terms of cooling performance.

[0057] In the refrigerant pipe 11, heat moves from the high temperature side flow passage 31 into the outer pipe. The heat that has moved from the high temperature side flow passage 31 tries to move from inside the outer pipe to the outside air or the low temperature side flow passage 35. At this time, since the thermal conductivity of the high temperature side inner pipe 33 is configured to be higher than that of the low temperature side inner pipe 37, the heat in the outer pipe moves more easily to the outside air than to the low temperature side flow passage 35, and a large cooling effect is obtained. As a result, the refrigerant pipe 11 is free from length limitations in terms of cooling performance.

[0058] In the refrigerant pipe 11, the cross-sectional shape of the inner pipe 27 is a sector shape in which the surface facing the other inner pipes 27 is flat.

[0059] In this refrigerant pipe 11, for example, two opposing inner pipes 27 are fan-shaped (approximately semicircular) with their flat surfaces facing each other. The two fan-shaped inner pipes 27 have a substantially circular outer periphery by being arranged with their flat surfaces facing each other. The refrigerant pipe 11 can reduce the space between the multiple inner pipes 27 and the outer pipe 29. In other words, the refrigerant pipe 11 allows for a high-density pipe layout and can have a compact overall cross section.

[0060] This allows the refrigerant pipe 11 to have a small outer diameter and, in a configuration in which the outer pipe is filled with liquid, to be light in weight. Also, the refrigerant pipe 11 with a small outer diameter requires a smaller routing space and a smaller diameter of the wall-penetrating sleeve than a pipe with a large outer diameter, improving workability at the installation site.

[0061] Moreover, the refrigerant pipe 11 includes a transmission line 45 in the outer pipe, and the transmission line 45 is disposed between the multiple inner pipes.

[0062] In this refrigerant piping 11, the outer pipe 29 has a transmission line 45 therein. Since the outer pipe 29 has the transmission line 45, the refrigerant piping 11 can pass optical fibers and electric wires such as signal lines and power lines inside the pipe. This allows only laying one refrigerant pipe 11, eliminating the need for other wiring installation work, and thus significantly reducing construction costs.

[0063] In this case, the refrigerant pipe 11 has a transmission path 45 disposed between the multiple inner pipes 27. At least one of the inner pipes 27 of the refrigerant pipe 11 has a low-temperature side flow path 35, and the other at least one of the inner pipes 27 has a high-temperature side flow path 31. The transmission path 45 is disposed between these two inner pipes 27. The transmission path 45 serves as a barrier when heat transfers from the high-temperature side flow path 31 to the low-temperature side flow path 35. As a result, the insulation efficiency between the high-temperature side flow path 31 and the low-temperature side flow path 35 is improved, and a decrease in the cooling capacity of the refrigerant 23 flowing through the low-temperature side flow path 35 can be suppressed.

[0064] In addition, in the refrigerant pipe 11, the outer pipe 29 is corrugated.

[0065] In this refrigerant piping 11, the outer pipe 29 is formed in a corrugated shape. With the outer pipe 29 being corrugated, the surface area of ​​the refrigerant piping 11 is increased, and heat dissipation performance is improved. Also, the contact area is reduced, making it easier to install the outer pipe 29 and to insert the inner pipe 27. Furthermore, since the outer pipe 29 has a corrugated structure, good flexibility is obtained, which also improves workability at the installation site.

[0066] The refrigerant piping 47 constitutes a cooling cycle in which liquid refrigerant 23 that directly or indirectly comes into contact with the heat receiving section 19 circulates, and includes an outer pipe 29 and a plurality of inner pipes 27 provided within the outer pipe and through which the refrigerant 23 circulates. The refrigerant 23 that has received heat at the heat receiving section 19 flows into at least one of the inner pipes 27 and returns to the heat receiving section 19 through at least one of the other inner pipes 27 at the other end side of the outer pipe 29 opposite the heat receiving section 19. The outer pipe 29 is configured so that the amount of refrigerant 23 that evaporates is less than that of the inner pipe 27.

[0067] In this refrigerant piping 47, a double pipe structure is formed between the heat receiving section 19 and the other end side of the outer pipe 29 opposite the heat receiving section 19, the double pipe structure being made up of the outer pipe 29 and the inner pipe 27 inserted into the outer pipe. In this refrigerant piping 47, the outer pipe 29 is blocked at the other end side opposite the heat receiving section 19. The downstream end of the high temperature side inner pipe 33 is bent back 180° at the other end side of the blocked outer pipe 29 and connected to the upstream end of the low temperature side inner pipe 37.

[0068] That is, the refrigerant pipe 47 and the heat receiving part 19 constitute a cooling cycle in which the refrigerant 23 is sealed and circulated in liquid form. A liquid mainly composed of water is used as the refrigerant 23 in the liquid cooling system 17 having this cooling cycle. In the liquid cooling system 17, the refrigerant 23 circulates in a liquid phase state. There are sensible heat that changes the temperature of an object and latent heat that changes the state of an object. The liquid cooling system 17 obtains a cooling effect by transporting heat (sensible heat) using only the liquid phase as a medium. In other words, the cooling cycle of the liquid cooling system 17 is significantly different from the refrigeration cycle of an automobile air conditioner that uses a conventional flexible hose to transport heat by utilizing latent heat due to a change in state between the gas phase and the liquid phase.

[0069] The standard refrigeration cycle defined in the refrigeration cycle used in the air conditioner for automobiles in Patent Document 1 has an evaporation temperature of -15°C, a condensation temperature of +30°C, the intake gas of the compressor is dry saturated steam or heated gas (for example, -10°C at a heating degree of 5°C), and the liquid temperature before the expansion valve is +25°C. In the refrigeration cycle, when the load is reduced, the intake gas temperature of the compressor decreases, and some of the refrigerant 23 may return to the compressor in liquid phase without evaporating in the evaporator. When the intake gas of the compressor contains a large amount of liquid-phase refrigerant 23, liquid compression occurs, which causes damage. Therefore, in the refrigeration cycle used in the air conditioner for automobiles in Patent Document 1, the intake gas temperature just before being drawn into the compressor is heated by heat exchange using a flexible hose with a double-pipe structure, and consideration is given to suppressing the liquid phase from being mixed into the compressor. In other words, the double pipe structure of the flexible hose of Patent Document 1 actively exchanges heat from the high-temperature, high-pressure gas discharged from the compressor and flowing through inner pipe 27 with the gas-phase refrigerant flowing through outer pipe 29, heating the gas-phase refrigerant and preventing it from liquefying.

[0070] In contrast, liquid cooling system 17, which does not need to transport heat by changing between gas and liquid phases, operates by a cooling cycle in which refrigerant 23 circulates in liquid form between heat receiving section 19 and heat dissipating section 21. Since the cooling cycle of liquid cooling system 17 does not need to compress and condense refrigerant 23, a compressor is not required, and instead a liquid circulation pump (pump 25) is required.

[0071] That is, since the liquid cooling system 17 does not require a compression process, the refrigerant pressure in the cooling cycle only needs to ensure the head, and is therefore a nearly constant low pressure. Since the refrigerant piping 47 does not need to be connected to a compressor, there is no longer any restriction that requires the use of metal pipes that are vulnerable to internal pressure in the low-temperature, low-pressure side flow path. For this reason, the double-pipe structure refrigerant piping 47 used in the liquid cooling system 17 can use metal pipes for the outer pipe 29 regardless of the type of flow path.

[0072] In the refrigerant piping 47, when the temperature of the outside air is lower than the temperature of the heat receiving section 19, the high-temperature refrigerant 23 that has received heat at the heat receiving section 19 flows through the high-temperature side flow path 31, and heat is gradually transferred (radiated) to the outside air. As a result, the low-temperature refrigerant 23 that has radiated heat flows in the low-temperature side flow path 35. In the refrigerant piping 47, if there is a temperature difference between the outside air and the refrigerant 23, heat is gradually transferred (radiated) to the outside air even in the low-temperature side flow path 35.

[0073] The refrigerant piping 47 having a double pipe structure used in the liquid cooling system 17 does not need to exchange heat between the refrigerant 23 flowing through the high-temperature side flow passage 31 and the refrigerant 23 flowing through the low-temperature side flow passage 35. In terms of cooling performance, it is preferable that the heat exchange rate between the high-temperature side flow passage 31 and the low-temperature side flow passage 35 is low.

[0074] In the liquid cooling system 17, the refrigerant 23, which has absorbed heat from the heat receiving section 19 and become hot, dissipates heat while passing through the high-temperature side inner pipe 33 and reaching the other end of the outer pipe 29, which is opposite to the heat receiving section 19. In addition, even after the refrigerant 23 reaches the other end of the outer pipe 29 and flows from the high-temperature side inner pipe 33 into the low-temperature side inner pipe 37, if there is a temperature difference with the outside air, the refrigerant 23 reaches the downstream end of the low-temperature side inner pipe 37 while further transferring heat (dissipating heat) to the outer pipe 29, and is returned to the heat receiving section 19 again. In other words, the refrigerant piping 47 with a double pipe structure used in the liquid cooling system 17 makes the heat dissipation section 21 unnecessary and obtains the cooling effect of the refrigerant 23.

[0075] If the heat of the refrigerant 23 is transferred to the outside air, which has a lower temperature than the high-temperature refrigerant 23 flowing through the high-temperature side flow path 31, the refrigerant pipe 47 can obtain a large cooling effect, and the length restriction can be eliminated in terms of cooling performance. In this case, a material with high thermal conductivity, such as a metal, can be suitably used for the outer pipe 29.

[0076] On the other hand, in consideration of the heat insulation between the high temperature side flow passage 31 and the low temperature side flow passage 35, a material with a lower thermal conductivity than metal, such as rubber, can be suitably used for the low temperature side inner pipe 37. However, in the case of the refrigerant pipe 47, since the heat dissipation part 21 is absent, the material of the low temperature side inner pipe 37 needs to be selected depending on the temperature difference between the refrigerant 23 flowing through the low temperature side flow passage 35 formed in the low temperature side inner pipe 37 and the outside air. If the temperature difference between the refrigerant 23 flowing through the low temperature side inner pipe 37 and the outside air is small, it is preferable to select a material with a low thermal conductivity as the material of the low temperature side inner pipe 37 in order to suppress the transfer of heat from the high temperature side flow passage 31. On the other hand, if the temperature difference between the refrigerant 23 flowing through the low temperature side inner pipe 37 and the outside air is large, it is preferable to select a material with a high thermal conductivity as the material of the low temperature side inner pipe 37 in order to promote the transfer of heat from the low temperature side flow passage 35 to the outer pipe 29.

[0077] As a result, in consideration of the temperature difference between the refrigerant 23 flowing through the low-temperature side inner pipe 37 and the outside air, the refrigerant piping 47 can be constructed with the outer pipe 29 made of metal and the low-temperature side inner pipe 37 made of metal, rubber, or the like.

[0078] By using rubber or the like for the low-temperature side inner pipe 37 of the refrigerant piping 47, the manufacturing costs can be reduced compared to when both the outer pipe 29 and the low-temperature side inner pipe 37 are made of metal, and flexibility is improved, thereby improving the ease of installation and installation.

[0079] The permeability of refrigerant 23, which is mainly composed of water, is higher in rubber than in metal. In other words, refrigerant 23 may evaporate from a rubber tube. In contrast, evaporating does not occur in a metal tube. For this reason, even if refrigerant 23 flowing in the inner tube of refrigerant piping 47 permeates from the inner tube to the outer tube, the total amount of refrigerant circulating does not decrease because the cooling cycle of liquid cooling system 17 is sealed. This allows refrigerant piping 47 to maintain a constant amount of refrigerant filled for a long period of time.

[0080] Therefore, in the refrigerant pipe 47, it is possible to suppress the volatility of the refrigerant 23 from the pipe while allowing the pipe to be long.

[0081] Furthermore, in the refrigerant pipe 47 , liquid is contained between the outer pipe 29 and the multiple inner pipes 27 .

[0082] In this refrigerant pipe 47, liquid is contained between the outer pipe 29 and the multiple inner pipes 27. That is, in the refrigerant pipe 47, the inner pipe 27 is disposed inside the outer pipe filled with liquid. This liquid may be the refrigerant 23. Examples of the refrigerant 23 include ethylene glycol and propylene glycol. These refrigerants 23 may be diluted with water. Therefore, the liquid filled in the outer pipe may be water.

[0083] Liquid has a higher thermal conductivity than air 39. For this reason, in the refrigerant pipe 47 in which the outer pipe is filled with liquid, the heat of the refrigerant 23 flowing through the high-temperature side flow passage 31 can be transferred to the outer pipe 29 via the liquid with high thermal conductivity, and then transferred (dissipated) from the outer pipe 29 to the outside air.

[0084] In this case, if the inner pipe 27 is made of a material such as rubber that has a lower thermal conductivity than the liquid, the heat transferred to the liquid in the outer pipe is less likely to transfer to the low-temperature side flow path 35 in the outer pipe. In other words, the liquid is effectively used as a heat transfer medium from the high-temperature side flow path 31 to the outside air. If this liquid is the refrigerant 23, the outer pipe will be filled with the refrigerant 23, and even if the refrigerant 23 permeates from the inner pipe to the outer pipe, the total amount of the refrigerant 23 filled in the refrigerant pipe 47 can be kept unchanged.

[0085] In addition, at least one of the inner pipes 27 of the refrigerant pipes 47 is made of metal.

[0086] In this refrigerant piping 47, at least one of the inner pipes 27 is made of metal. It is preferable that the outer pipe 29 of the refrigerant piping 47 is made of metal in terms of increasing the heat dissipation efficiency and preventing the liquid from volatilizing. Meanwhile, the high temperature side inner pipe 33 and the low temperature side inner pipe 37 are inserted inside the outer pipe 29. The high temperature side inner pipe 33 is required to have heat dissipation properties. Meanwhile, the low temperature side inner pipe 37 is required to have heat insulation properties. Therefore, it is preferable that the inner pipe 27 made of metal is the high temperature side inner pipe 33. In contrast, the low temperature side inner pipe 37, which is required to have heat insulation properties, can be made of rubber.

[0087] That is, heat is transferred (dissipated) from the high-temperature refrigerant 23 flowing through the high-temperature side flow passage 31 to the outside air through the outer tube 29. On the other hand, the refrigerant 23 that has been cooled by heat dissipation flows through the low-temperature side flow passage 35, thereby preventing the heat transferred into the outer tube from being transferred back to the low-temperature refrigerant 23 flowing through the low-temperature side flow passage 35.

[0088] In addition, in the refrigerant pipe 47, the refrigerant 23 having received heat at the heat receiving portion 19 flows through at least one inner pipe 27 made of metal.

[0089] In this refrigerant piping 47, the refrigerant 23 that has received heat at the heat receiving section 19 flows through the metallic inner pipe 27. That is, the metallic inner pipe 27 is used as the high-temperature side inner pipe 33. Since the high-temperature side flow passage 31 is made of metal, heat is easily transferred from the high-temperature refrigerant 23 flowing through the high-temperature side flow passage 31 to the outer pipe. The heat transferred to the outer pipe is transferred (dissipated) from the metallic outer pipe 29 to the outside air. That is, the heat flowing through the high-temperature side flow passage 31 can be transferred with low thermal resistance through the metallic high-temperature side inner pipe 33 and metallic outer pipe 29, which have high thermal conductivity.

[0090] At this time, if the outer tube is filled with liquid, heat can be transferred (dissipated) more effectively than when the outer tube is filled with air 39. Even in this case, refrigerant 23 that has been cooled by heat dissipation flows through low-temperature side flow passage 35 formed by low-temperature side inner tube 37, which has low thermal conductivity, thereby preventing the heat transferred into the outer tube from being transferred back to the low-temperature refrigerant 23 flowing through low-temperature side flow passage 35. Therefore, refrigerant piping 47 has a double pipe structure that is suitable for realizing a cooling cycle with high heat dissipation efficiency and high cooling performance.

[0091] Therefore, refrigerant pipes 11 and 47 according to the first embodiment can suppress the volatility of refrigerant 23 from the pipes, while enabling long pipes.

[0092] Although the embodiments have been described above with reference to the accompanying drawings, the present disclosure is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications, corrections, substitutions, additions, deletions, and equivalents within the scope of the claims, and it is understood that these also belong to the technical scope of the present disclosure. In addition, the components in the above-mentioned embodiments may be arbitrarily combined within the scope of the invention. [Industrial Applicability]

[0093] INDUSTRIAL APPLICABILITY The present disclosure is useful as a refrigerant pipe that enables long piping while suppressing volatility of the refrigerant from the pipe. [Explanation of symbols]

[0094] 11 Refrigerant piping 19 Heat receiving part 21 Heat dissipation part 23 Refrigerants 27 Inner tube 29 Outer tube 33 High temperature side inner pipe (at least one of the inner pipes) 37 Low temperature side inner tube (at least one of the other inner tubes) 45 Transmission Line 47 Refrigerant piping

Claims

1. A refrigerant pipe constituting a cooling cycle in which a liquid refrigerant circulates in direct or indirect contact with a heat receiving part and a heat radiating part, an outer pipe; and a plurality of inner pipes provided inside the outer pipe and through which the refrigerant circulates; The refrigerant that has received heat at the heat receiving portion flows into at least one of the inner tubes, The refrigerant that has dissipated heat in the heat dissipation portion flows into at least one of the other inner tubes, The outer tube is configured to evaporate less of the refrigerant than the inner tube. Refrigerant piping.

2. A liquid is contained between the outer tube and the plurality of inner tubes. The refrigerant pipe according to claim 1.

3. The inner tube is configured to have a lower thermal conductivity than the outer tube.

3. The refrigerant pipe according to claim 1 or 2.

4. Among the inner pipes, the inner pipe through which the refrigerant that has received heat at the heat receiving portion flows is Among the inner pipes, the inner pipe through which the refrigerant that has radiated heat in the heat radiating portion flows is configured to have high thermal conductivity; 3. The refrigerant pipe according to claim 1 or 2.

5. The cross-sectional shape of the inner tube is a sector shape with a flat surface facing the other inner tube.

3. The refrigerant pipe according to claim 1 or 2.

6. a transmission path provided within the outer tube; the transmission line is disposed between the plurality of inner pipes; 6. The refrigerant pipe according to claim 5.

7. The outer tube is corrugated. The refrigerant pipe according to claim 3.

8. A cooling system that constitutes a cooling cycle in which a liquid refrigerant circulates in direct or indirect contact with the heat receiving part. A medium pipe, an outer pipe; and a plurality of inner pipes provided inside the outer pipe and through which the refrigerant circulates; the refrigerant that has received heat in the heat receiving portion flows into at least one of the inner tubes, and returns to the heat receiving portion through at least the other of the inner tubes at the other end side of the outer tube that is opposite to the heat receiving portion, The outer tube is configured to evaporate less of the refrigerant than the inner tube. Refrigerant piping.

9. A liquid is contained between the outer tube and the plurality of inner tubes.

9. The refrigerant pipe according to claim 8.

10. At least one of the inner tubes is made of metal.

10. The refrigerant pipe according to claim 8 or 9.

11. The refrigerant whose heat has been received by the heat receiving portion flows through the at least one metallic inner tube. Refrigerant piping according to claim 10.

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