Cooling system

Abstract

To provide a cooling system capable of using substances that have not been used in a conventional refrigeration method as a refrigerant in a thermal cycle or expanding a range of substances that can be used as the refrigerant in the thermal cycle.SOLUTION: A cooling system according to one embodiment includes: a refrigerant flowing device 10 having a refrigerant flow passage 11 for causing a refrigerant to flow and a control valve 14 provided in the refrigerant flow passage 11 and controlling flowing of the refrigerant; and a decompression device 20 having an introduction port 20A connected to a downstream end 11D of the refrigerant flow passage 11 and sucking gas from the refrigerant flow passage 11 and an outflow port 20B connected to an upstream end 11U of the refrigerant flow passage 11 and causing the gas sucked from the introduction port 20A to flow from the upstream end 11U of the refrigerant flow passage 11 into the refrigerant flow passage 11. The refrigerant flowing device 10 causes the refrigerant included in the gas flowing in from the decompression device 20 to flow. The refrigerant flowing device 10 includes a temperature control section 16 that cools a temperature control target by using the refrigerant on the downstream side of the control valve 14 in the refrigerant flow passage 11.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE The present invention relates to a cooling system that utilizes reduced pressure to reduce the temperature of a refrigerant. [Background technology]

[0002] Vapor compression refrigeration systems are widely used in many fields.

[0003] In a vapor compression refrigeration system, the refrigerant is compressed in the compressor, and the refrigerant flowing out of the compressor is cooled in the condenser. The refrigerant flowing out of the condenser is expanded in the expansion valve, and the refrigerant flowing out of the expansion valve exchanges heat with a temperature-controlled object in the evaporator. The refrigerant cools the object by absorbing heat from the temperature-controlled object in the evaporator. The refrigerant flowing out of the evaporator circulates to the compressor, and then releases heat in the condenser.

[0004] The refrigerants used in vapor compression refrigeration systems are usually fluorinated refrigerants, which are greenhouse gases and may be flammable, but have various advantages, such as the ability to achieve highly efficient operation.

[0005] On the other hand, in consideration of the impact of fluorine-based refrigerants on the environment (greenhouse effect), development of fluorine-based refrigerants for vapor compression systems that can keep the global warming potential (GWP) low has been underway. HFO-based refrigerants for vapor compression systems with very low GWP have already been put to practical use. Specifically, for example, HFO-based refrigerants with a GWP of 10 or less have been put to practical use. However, it cannot be said that these refrigerants are sufficiently safe in terms of flammability and toxicity. Therefore, development of refrigerants for vapor compression systems that can ensure low GWP and safety is still being actively carried out.

[0006] In addition, the compressor used in the vapor compression refrigeration system operates for a long period of time. Therefore, it is necessary to lubricate the driving parts such as rotating parts with lubricating oil. However, there is a problem with the lubricating oil leaking into the refrigerant side. This leakage of the lubricating oil may cause the compressor to run out of oil, which may impair the stability of the compressor's operation. In addition, the retention of the lubricating oil in the evaporator may impair the cooling efficiency of the evaporator. Therefore, the vapor compression refrigeration system has room for various improvements in terms of the use of the compressor.

[0007] On the other hand, as cooling devices that do not use a compressor, boiling cooling devices as disclosed in Patent Documents 1-3, for example, are known.

[0008] The boiling cooling device can efficiently cool the temperature control object by absorbing heat due to latent heat by vaporizing the liquid when exchanging heat between the liquid and the temperature control object. Usually, a pump is required to circulate the liquid or the gas produced by vaporizing the liquid, but the pump does not require lubricating oil, or only a small amount is required. Furthermore, the energy consumption of the pump is relatively small. Therefore, the boiling cooling device can be said to be a device with excellent environmental performance.

[0009] However, in a boiling cooling device, generally, cooling at a temperature range significantly below 0°C is not possible, and the cooling temperature and temperature control targets are very limited. Therefore, it is difficult for the boiling cooling device to ensure high refrigeration capacity in low or ultra-low temperature ranges. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2011-142298 A [Patent Document 2] International Publication No. 2017 / 119113 [Patent Document 3] Patent Publication No. 2021-162195 Summary of the Invention [Problem to be solved by the invention]

[0011] In recent years, while the development of refrigerants with low environmental impact, such as HFO refrigerants, has been progressing as described above, the development of antifreezes with low environmental impact has also been progressing. HFO solvents that have low GWP and are non-flammable and can be used as antifreezes have been put to practical use. Such solvents have a boiling point of, for example, 70°C or higher under atmospheric pressure, and are therefore not suitable for vapor compression refrigeration devices. However, if a heat cycle can be realized using such HFO solvents, it may be possible to realize a cooling system that can ensure low environmental impact, high safety, and high refrigeration capacity, which are currently strongly required.

[0012] Therefore, the present inventors conducted intensive research to realize a new cooling system that can use, for example, HFO-based solvents as described above as refrigerants in a heat cycle. More generally, they conducted intensive research to realize a new cooling system that can shift a range of substances that are different from the range of refrigerants that can be used in a vapor compression type refrigeration device to a refrigerant that can be used in a heat cycle. As a result, they found that the above cooling system can be realized by a structure in which the temperature of the refrigerant is lowered by reducing the pressure, the refrigerant is used to cool a temperature control target, and then the heat absorbed by the refrigerant is released under atmospheric pressure, which led to the invention of the present invention.

[0013] In other words, the object of the present invention is to provide a cooling system that enables a substance that has not been used in conventional refrigeration methods to be used as a refrigerant in a heat cycle, or that can expand the range of substances that can be used as refrigerants in a heat cycle. [Means for solving the problem]

[0014] One embodiment of the present invention relates to the following aspects "1" to "10".

[0015] [1] A refrigerant flow device including a refrigerant flow path through which a refrigerant flows, and a control valve provided in the refrigerant flow path to control the flow of the refrigerant; a pressure reducing device including an inlet connected to a downstream end of the refrigerant flow path and for drawing in gas from the refrigerant flow path, and an outlet connected to an upstream end of the refrigerant flow path and for allowing the gas drawn in from the inlet to flow into the refrigerant flow path from the upstream end of the refrigerant flow path, the refrigerant flow path allows the refrigerant contained in the gas flowing in from the pressure reducing device to flow; The refrigerant flow device includes a temperature control unit, which is located downstream of the control valve in the refrigerant flow path and cools a temperature-controlled object with the refrigerant.

[0016] [2] The cooling system described in [1], wherein the refrigerant flow device is provided with a gas-liquid separator downstream of the temperature control unit in the refrigerant flow path, which separates the gas phase portion and the liquid phase portion of the refrigerant that has passed through the temperature control unit so that the gas phase portion and the liquid phase portion flow downstream of the liquid phase portion.

[0017] [3] The refrigerant flow device includes a reservoir tank located upstream of the control valve in the refrigerant flow path, the reservoir tank storing the refrigerant that has changed from the gas phase to a liquid phase after flowing from the pressure reducing device into the refrigerant flow path, The cooling system according to [1] or [2], wherein the control valve controls the flow of the liquid phase refrigerant flowing in from the reservoir tank.

[0018] [4] The cooling system described in [3], wherein the reservoir tank has a cooler that cools the gas flowing in from the pressure reducing device and liquefies the refrigerant from the gas.

[0019] [5] The refrigerant flow device includes a two-phase flow separator between the control valve and the temperature control unit in the refrigerant flow path, The two-phase flow separator includes an inlet through which the refrigerant from the control valve flows in, and an outlet located below the inlet and through which the refrigerant flowing in from the inlet flows out.

[0020] [6] A cooling system described in any of [1] to [5], wherein a portion of the refrigerant flow path between the control valve and the temperature control unit and a portion of the refrigerant flow path downstream of the temperature control unit constitute an internal heat exchanger that enables the refrigerants flowing through each of them to exchange heat with each other.

[0021] [7] A cooling system described in any of [1] to [6], wherein the operation of the pressure reducing device and the throttling state of the control valve create a condition in which the internal pressure of the portion of the refrigerant flow path downstream of the control valve is lower than the internal pressure of the portion of the refrigerant flow path upstream of the control valve.

[0022] [8] The cooling system according to any one of [1] to [7], wherein the refrigerant is a substance having a boiling point of 30°C or higher under atmospheric pressure.

[0023] [9] The cooling system according to any one of [1] to [8], wherein the refrigerant has a GWP of 10 or less.

[0024]

[10] The cooling system of any of [1] to [9], wherein the refrigerant is HFO-1336mzz-Z. Effect of the Invention

[0025] According to the present invention, it becomes possible to use a substance that has not been used in conventional refrigeration systems as a refrigerant in a heat cycle, or to expand the range of substances that can be used as a refrigerant in a heat cycle. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is a schematic diagram of a cooling system according to an embodiment. [Diagram 2] 2 is a block diagram showing a functional configuration of a controller constituting the cooling system of FIG. 1. [Diagram 3] FIG. 2 is a pH diagram of an example of a refrigerant used in the cooling system of FIG. 1. [Figure 4]2 is a schematic diagram of a plasma etching apparatus including the cooling system of FIG. 1 as an application example of the cooling system. [Diagram 5] 2 is a schematic diagram of a cooking appliance including the cooling system, which is an application example of the cooling system of FIG. 1. [Figure 6] 2 is a schematic diagram of a molding device including the cooling system of FIG. 1 as an application example of the cooling system. [Figure 7] FIG. 2 is a schematic diagram of a refrigerated warehouse equipped with the cooling system, which is an application example of the cooling system of FIG. 1. [Figure 8] FIG. 13 is a diagram illustrating a cooling system according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] An embodiment will be described below.

[0028] 1 is a schematic diagram of a cooling system S according to an embodiment. First, the configuration of the cooling system S will be described.

[0029] (Cooling system configuration) As shown in FIG. 1, the cooling system S includes a refrigerant flow device 10, a pressure reducing device 20, and a controller 30.

[0030] The refrigerant flow device 10 has a refrigerant flow path 11 through which a refrigerant flows. The refrigerant flow path 11 includes an upstream end 11U and a downstream end 11D. The pressure reducing device 20 includes an inlet 20A connected to the downstream end 11D of the refrigerant flow path 11 to draw gas from the refrigerant flow path 11, and an outlet 20B connected to the upstream end 11U of the refrigerant flow path 11 to allow the gas drawn from the inlet 20A to flow from the upstream end 11U into the refrigerant flow path 11.

[0031] The refrigerant flow device 10 has, from upstream to downstream, a reservoir tank 12, a dryer 13, a control valve 14, a two-phase flow separator 15, a temperature control unit 16, a gas-liquid separator 17, and a butterfly valve 18, which are provided in this order in a refrigerant flow path 11. That is, the refrigerant flow path 11 is configured by connecting the reservoir tank 12, the dryer 13, the control valve 14, the two-phase flow separator 15, the temperature control unit 16, the gas-liquid separator 17, and the butterfly valve 18 in this order with piping members.

[0032] When the cooling system S is in operation, the control valve 14 in the refrigerant flow path 11 is controlled to a state in which its opening degree is narrowed. In this state, the pressure reducing device 20 sucks gas present in the refrigerant flow path 11 or gas evaporated in the refrigerant flow path 11 from the downstream end 11D of the refrigerant flow path 11. In this way, the pressure reducing device 20 reduces the pressure inside the portion of the refrigerant flow path 11 downstream of the control valve 14, or maintains it in a reduced pressure state.

[0033] As described above, the pressure reducing device 20 sucks gas from the refrigerant flow path 11, and thereby the pressure inside the portion of the refrigerant flow path 11 downstream of the control valve 14 is reduced to a pressure lower than atmospheric pressure. On the other hand, the pressure inside the portion of the refrigerant flow path 11 upstream of the control valve 14 is higher than the pressure inside the portion of the refrigerant flow path 11 downstream of the control valve 14, and is set to, for example, atmospheric pressure.

[0034] The gas sucked by the pressure reducing device 20 from the downstream end 11D of the refrigerant flow passage 11 flows into the inside of the refrigerant flow passage 11 from the upstream end 11U of the refrigerant flow passage 11. The refrigerant flow device 10 flows the refrigerant contained in the gas flowing from the pressure reducing device 20 through the refrigerant flow passage 11. The refrigerant flow device 10 liquefies the refrigerant as much as possible before the refrigerant reaches the control valve 14 in the refrigerant flow passage 11. The liquefied refrigerant is depressurized and lowered in temperature when it flows into a portion of the refrigerant flow passage 11 downstream of the control valve 14. This allows the temperature control unit 16 arranged downstream of the control valve 14 in the refrigerant flow passage 11 to flow a low-temperature refrigerant. The refrigerant and the temperature control target exchange heat with each other in the temperature control unit 16, so that the temperature control target can be cooled by the refrigerant.

[0035] The refrigerant that exchanges heat with the temperature control target in temperature control unit 16 can evaporate by absorbing the heat of the temperature control target. In this case, the refrigerant can efficiently cool the temperature control target by the latent heat of vaporization. The evaporated refrigerant is in a gaseous state and is sucked by pressure reducing device 20. Here, the gaseous refrigerant sucked by pressure reducing device 20 absorbs heat from the temperature control target. In this embodiment, the heat absorbed by the refrigerant is released to the outside mainly in reservoir tank 12 in refrigerant flow path 11. This allows the temperature control target to be continuously cooled.

[0036] The refrigerant circulated by the cooling system S is not particularly limited, but is, for example, a substance that becomes liquid under atmospheric pressure and at a standard environmental temperature (e.g., 25°C) and that becomes -5°C or lower when expanded from this state in an environment of, for example, 0.1 atmospheric pressure, and is preferably a substance that becomes -30°C or lower when expanded in an environment of 0.01 atmospheric pressure. When such a substance is used as a refrigerant, cooling to a low temperature range is possible. In this specification, atmospheric pressure means 1 atmospheric pressure, or in other words, 0.1 MPa (Abs).

[0037] The refrigerant flow device 10 and the pressure reducing device 20 that constitute the cooling system S will be described in detail below.

[0038] The reservoir tank 12 in the refrigerant flow device 10 stores the refrigerant that has turned from gas into liquid phase after flowing from the pressure reducing device 20 into the refrigerant flow path 11. As described above, the internal pressure of the portion of the refrigerant flow path 11 upstream of the control valve 14 is greater than the internal pressure of the portion of the refrigerant flow path 11 downstream of the control valve 14. Therefore, the gas that has flowed from the pressure reducing device 20 into the refrigerant flow path 11 is pressurized and heated. At this time, the refrigerant contained in the gas is also pressurized from the gas phase, heated, and attempts to liquefy.

[0039] The refrigerant contained in the gas flowing in from the pressure reducing device 20 may become at least partially liquid before reaching the reservoir tank 12. The reservoir tank 12 can store the refrigerant that has naturally become liquid in this way. However, it may be difficult to liquefy all of the gas-phase refrigerant flowing in from the pressure reducing device 20 before reaching the reservoir tank 12. Therefore, the reservoir tank 12 in this embodiment has a cooler 12A that cools and liquefies the gas-phase refrigerant. The cooler 12A is provided in the reservoir tank 12 and mainly cools the gas that flows into the reservoir tank 12 from the pressure reducing device 20. As a result, most of the refrigerant in the gas flowing in from the pressure reducing device 20 can be liquefied in the reservoir tank 12, and the liquid-phase refrigerant can be stored. The cooler 12A may be provided outside the reservoir tank 12, and may be configured to cool, for example, a portion of the refrigerant flow passage 11 upstream of the reservoir tank 12.

[0040] The reservoir tank 12 has a gas inlet 12i at its top and an outlet 12e at its bottom for discharging the liquid phase refrigerant downstream. In detail, the reservoir tank 12 includes a container body 12B having an opening and a lid 12C for opening and closing the opening, and the inlet 12i is provided at the top of the container body 12B and the outlet 12e is provided at the bottom of the container body 12B. However, the positions of the inlet 12i and the outlet 12e are not particularly limited. In addition, in the reservoir tank 12, by opening the lid 12C, for example, it is possible to avoid a pressure rise in the reservoir tank 12 and to reduce the power consumption of the pressure reducing device 20. In addition, by opening the lid 12C, it is possible to fill or replenish the refrigerant.

[0041] The dryer 13 adsorbs moisture and foreign matter contained in the liquid-phase refrigerant from the reservoir tank 12. The dryer 13 may be configured, for example, by housing a porous material in a canister (container). In this case, the porous material may be a molecular sieve, activated alumina, a mixture of these, or the like.

[0042] The control valve 14 controls the flow of the refrigerant flowing in from the dryer 13. More specifically, the control valve 14 controls the flow of the refrigerant mainly in the liquid phase flowing in from the dryer 13. When the cooling system S is in operation, the control valve 14 narrows its opening to limit the flow of the refrigerant as soon as the suction operation of the pressure reducing device 20 starts, thereby controlling the inside of the portion downstream of the control valve 14 in the refrigerant flow path 11 to a desired reduced pressure state. In addition, the control valve 14 can adjust the flow rate of the refrigerant flowing out from the control valve 14 to the downstream side, thereby adjusting, for example, the temperature or cooling capacity of the refrigerant flowing through the temperature control unit 16.

[0043] As described above, the pressure inside the portion of the refrigerant flow path 11 upstream of the control valve 14 is greater than the pressure inside the portion of the refrigerant flow path 11 downstream of the control valve 14. Therefore, the refrigerant passing through the control valve 14 is depressurized and its temperature decreases when it flows into the portion of the refrigerant flow path 11 downstream of the control valve 14. In other words, the refrigerant passing through the control valve 14 is expanded and its temperature decreases when it flows into the portion of the refrigerant flow path 11 downstream of the control valve 14. Therefore, the control valve 14 also has a function similar to that of an expansion valve in a refrigeration circuit, which expands the liquid phase refrigerant.

[0044] The refrigerant flowing out of the control valve 14 may be partially vaporized by expansion. Therefore, the refrigerant flowing out of the control valve 14 may flow downstream in a gas-liquid mixed phase state. However, the refrigerant flowing out of the control valve 14 may also flow downstream in liquid phase. In either case, the refrigerant is depressurized (expanded), and therefore its temperature decreases. The type of the control valve 14 is not particularly limited, but in this embodiment, it is an electrically operated proportional control valve. The control valve 14 is electrically connected to a controller 30. The control valve 14 is controlled by the controller 30.

[0045] The two-phase flow separator 15 includes an inlet 15A through which the refrigerant from the control valve 14 flows in, and an outlet 15B that is provided below the inlet 15A and through which the refrigerant flowing in from the inlet 15A flows out. In the portion downstream of the control valve 14 in the refrigerant flow passage 11, the temperature of the refrigerant located in the downstream region is basically lower than the temperature of the refrigerant located in the upstream region. The temperature of the refrigerant immediately after flowing out of the control valve 14 is usually higher than the temperature of the refrigerant already present in the downstream region. In addition, the refrigerant immediately after flowing out of the control valve 14 flows so as to be drawn rapidly downstream. Therefore, the two-phase flow separator 15 is provided to suppress the high-temperature phase of the refrigerant flowing out of the control valve 14 from flowing out rapidly downstream.

[0046] That is, in two-phase flow separator 15, inlet 15A is provided above outlet 15B, so that the high-temperature phase of the refrigerant is less likely to flow straight toward outlet 15B. Also, the high-temperature phase of the refrigerant tends to flow upward relatively more than the lower-temperature phase, so that it is less likely to flow straight toward outlet 15B. As described above, two-phase flow separator 15 prevents the high-temperature phase of the refrigerant that has flowed into two-phase flow separator 15 from flowing straight toward outlet 15B, thereby preventing the high-temperature phase from suddenly flowing out downstream.

[0047] Specifically, the two-layer flow separator 15 has a vessel body 15C that defines an internal space so as to form a flow path cross-sectional area larger than the flow path cross-sectional area of ​​the piping member that connects the inlet 15A and the control valve 14. The inlet 15A is provided at the upper part of the side wall of the vessel body 15C (a part above the center in the vertical direction of the side wall), and the outlet 15B is provided at the bottom wall of the vessel body 15C. In this embodiment, the inlet 15A and the outlet 15B do not overlap in the horizontal direction. The inlet 15A and the outlet 15B are relatively far apart in the vertical direction. In this configuration, the high-temperature phase of the refrigerant flowing out of the control valve 14 is unlikely to reach the outlet 15B. However, the positions of the inlet 15A and the outlet 15B are not particularly limited. The state in which the inlet 15A and the outlet 15B do not overlap in the horizontal direction means that when the inlet 15A is projected horizontally toward the outlet 15B, the two do not overlap at all. However, the positions of the inlet 15A and the outlet 15B are not limited to this embodiment.

[0048] 1, the inside of the two-phase flow separator 15 is depicted in different colors, indicating that the part of the refrigerant depicted in a darker color (the upper part in the drawing) has a lower temperature than the part of the refrigerant depicted in a lighter color (the lower part in the drawing).

[0049] The temperature control unit 16 allows the refrigerant flowing out from the two-phase flow separator 15 to flow, and cools a temperature-controlled object (not shown) with this refrigerant. The temperature control unit 16 may be formed, for example, in a serpentine shape, a spiral shape, or a curved shape. The configuration of the temperature control unit 16 is not particularly limited, and the temperature control unit 16 may be formed, for example, by a fin-tube type heat exchanger or the like, or may include a plate-shaped heat transfer body.

[0050] The gas-liquid separator 17 separates the refrigerant that has passed through the temperature control unit 16 into a gas phase portion and a liquid phase portion. More specifically, the gas-liquid separator 17 separates the gas phase portion and the liquid phase portion so that the gas phase portion of the refrigerant that has passed through the temperature control unit 16 flows downstream of the liquid phase portion. When the temperature control unit 16 exchanges heat with the refrigerant with a temperature control target, a part of the refrigerant may evaporate and become gas. Therefore, the refrigerant flowing from the temperature control unit 16 to the gas-liquid separator 17 may include a gas phase portion and a liquid phase portion. The gas-liquid separator 17 separates the gas phase refrigerant and the liquid phase refrigerant of the refrigerant that has passed through the temperature control unit 16 into gas and liquid, and functions to flow the gas phase refrigerant upward.

[0051] The gas-liquid separator 17 includes an inlet 17A through which the refrigerant from the temperature control unit 16 flows in, and an outlet 17B that is provided above the inlet 17A and through which the refrigerant that flows in from the inlet 17A flows out. In detail, the gas-liquid separator 17 has a container body 17C that defines an internal space so as to form a flow path cross-sectional area larger than the flow path cross-sectional area of ​​the piping member that connects the inlet 17A and the temperature control unit 16. The inlet 17A is provided on the bottom wall of the container body 17C, and the outlet 17B is provided on the top wall of the container body 17C. The positions of the inlet 17A and the outlet 17B are not particularly limited, but it is preferable that the inlet 17A and the outlet 17B are far apart in the vertical direction. In this case, since the gas phase tends to flow upward more than the liquid phase, the gas phase portion of the refrigerant that flows downstream in the gas-liquid separator 17 is easily discharged downstream from the outlet 17B. In addition, the situation in which the liquid phase refrigerant is sucked into the pressure reducing device 20 is suppressed.

[0052] The portion of the gas-liquid separator 17 that is depicted in a dark color indicates the liquid phase portion, and the portion above it indicates the gas phase portion. In the gas-liquid separator 17, it is preferable to introduce a liquid phase refrigerant so that a gas phase is always formed in the upper portion. The environment in which the liquid phase refrigerant and the gas phase portion coexist in the gas-liquid separator 17 can be formed by controlling the operation of the pressure reducing device 20, the control valve 14, and the like. The gas-liquid separator 17 is configured to have a structure that can maintain its shape when the internal pressure is reduced, and may be configured as a so-called vacuum insulated container. The maintenance of the shape of the gas-liquid separator 17 during reduction in pressure depends on the internal pressure to be reduced, but when the pressure is reduced to, for example, 0.1 atm, it is preferable that the outer shell portion of the gas-liquid separator 17 is formed of a hard metal or the like having a large thickness. However, the specific structure of the gas-liquid separator 17 may be appropriately determined according to the expected degree of reduction in pressure, and is not particularly limited.

[0053] In this embodiment, the gas-liquid separator 17 and the reservoir tank 12 are disposed at the same or approximately the same position in the vertical direction. As a result, in this embodiment, when the operation is stopped, the refrigerant flows so that the liquid level of the liquid phase refrigerant in the gas-liquid separator 17 is the same as the liquid level of the liquid phase refrigerant in the reservoir tank 12. By creating such a state, the next operation can be started smoothly.

[0054] The butterfly valve 18 is a valve that controls the amount of gas sucked into the refrigerant passage 11 by the pressure reducing device 20. The butterfly valve 18 may be configured to control the opening degree by, for example, an electric motor. The butterfly valve 18 is electrically connected to the controller 30. The butterfly valve 18 is controlled by the controller 30.

[0055] In this embodiment, the portion between the control valve 14 and the temperature control unit 16 in the refrigerant flow path 11 and the portion downstream of the temperature control unit 16 in the refrigerant flow path 11 constitute an internal heat exchanger 19 that allows the refrigerants flowing therethrough to exchange heat with each other. The portion between the control valve 14 and the temperature control unit 16 in the refrigerant flow path 11 is, in detail, the portion downstream of the control valve 14 and the two-layer flow separator 15 in the refrigerant flow path 11, and is upstream of the temperature control unit 16. In this embodiment, the portion downstream of the temperature control unit 16 in the refrigerant flow path 11 is, in detail, the portion between the temperature control unit 16 and the gas-liquid separator 17 in the refrigerant flow path 11. By configuring such an internal heat exchanger 19, the refrigerant flowing through the portion between the control valve 14 and the temperature control unit 16 in the refrigerant flow path 11 can be cooled. The refrigerant flowing through the portion between the temperature control unit 16 and the gas-liquid separator 17 in the refrigerant flow path 11 can be heated.

[0056] The refrigerant flow device 10 also includes a first temperature sensor 101, a second temperature sensor 102, a third temperature sensor 103, a first pressure sensor 104, a second pressure sensor 105, a first liquid level sensor 106, and a second liquid level sensor 107.

[0057] The first temperature sensor 101 detects the temperature of the refrigerant flowing through the temperature control unit 16. The second temperature sensor 102 detects the temperature of the refrigerant flowing through a portion of the refrigerant flow path 11 between the two-layer flow separator 15 and the temperature control unit 16. The third temperature sensor 103 detects the temperature of the refrigerant flowing through a portion of the refrigerant flow path 11 between the temperature control unit 16 and the gas-liquid separator 17 (a portion upstream of the internal heat exchanger 19). The first pressure sensor 104 detects the pressure of the refrigerant flowing through a portion of the refrigerant flow path 11 between the two-layer flow separator 15 and the temperature control unit 16. The second pressure sensor 105 detects the pressure of the refrigerant flowing through a portion of the refrigerant flow path 11 between the temperature control unit 16 and the gas-liquid separator 17 (a portion upstream of the internal heat exchanger 19).

[0058] The first liquid level sensor 106 detects the level of the liquid-phase refrigerant stored in the reservoir tank 12. The second liquid level sensor 107 detects the level of the liquid-phase refrigerant stored in the gas-liquid separator 17. The first liquid level sensor 106 and the second liquid level sensor 107 may be configured as an optical sensor such as a laser displacement meter, in which case light is irradiated onto the liquid level from above and the reflected light is received to calculate the liquid level. However, the first liquid level sensor 106 and the second liquid level sensor 107 may be configured as a float type sensor.

[0059] Each of the sensors (101 to 107) is electrically connected to the controller 30, and the detection results of each sensor are sent to the controller 30.

[0060] The pressure reducing device 20 has a gas suction pump 22 that sucks gas from the refrigerant flow path 11. The gas suction pump 22 sucks gas from the refrigerant flow path 11 through an inlet 20A connected to a downstream end 11D of the refrigerant flow path 11, and causes the gas sucked from the inlet 20A to flow into the refrigerant flow path 11 through an outlet 20B connected to an upstream end 11U of the refrigerant flow path 11. The inlet 20A and the outlet 20B may be formed in the gas suction pump 22, or may be formed in a piping portion connected to the gas suction pump 22.

[0061] The type of the gas suction pump 22 is not particularly limited, but it is preferable that the gas suction pump 22 is a dry vacuum pump in which the lubricating oil does not flow out or hardly flows out to the suction path side. The dry vacuum pump may be a diaphragm type dry vacuum pump, a rocking piston type dry vacuum pump, a rotary vane type dry vacuum pump, a scroll type dry vacuum pump, or the like, or may be a pump of a type different from the above examples. However, the gas suction pump 22 may be a wet type vacuum pump.

[0062] The gas suction pump 22 in this embodiment is a dry vacuum pump. The gas suction pump 22 includes a motor controlled by an inverter, such as an AC motor or a brushless DC motor. The gas suction pump 22 adjusts the rotation speed of the motor to adjust the amount of gas suctioned, thereby adjusting the internal pressure of the portion of the refrigerant flow path 11 downstream of the control valve 14.

[0063] The gas suction pump 22 is electrically connected to the controller 30 and controlled by the controller 30. In this embodiment, the gas suction pump 22 is electrically connected to the controller 30 via an inverter 40. The rotation speed of the motor is adjusted by the controller 30 adjusting the frequency of the AC current supplied to the motor using the inverter 40.

[0064] The controller 30 is electrically connected to the above-mentioned sensors (101 to 107), and is also electrically connected to the control valve 14, the butterfly valve 18, and the gas suction pump 22. The controller 30 may be configured, for example, as a computer having a CPU, a ROM, and the like. In this case, the controller 30 performs various processes according to the programs stored in the ROM. Note that the controller 30 may be configured with other processors and electric circuits (for example, an FPGA (Field Programmable Gate Alley), etc.).

[0065] (Controller function configuration) Fig. 2 is a block diagram showing the functional configuration of the controller 30. As shown in Fig. 2, the controller 30 has a sensor information acquisition unit 31, a rotation speed adjustment unit 32, and a valve opening adjustment unit 33. Note that the controller 30 may be configured, for example, by one computer or by multiple computers. When configured by multiple computers, the multiple functional units may be distributed among the multiple computers.

[0066] The sensor information acquisition unit 31 is a part that acquires the detection results from the above-mentioned first temperature sensor 101, second temperature sensor 102, third temperature sensor 103, first pressure sensor 104, second pressure sensor 105, first liquid level sensor 106, and second liquid level sensor 107. The sensor information acquisition unit 31 provides one or more pieces of information relating to the acquired detection results to the rotation speed adjustment unit 32 and the valve opening adjustment unit 33.

[0067] The rotation speed adjustment unit 32 is electrically connected to the gas suction pump 22 and controls the operation of the gas suction pump 22. More specifically, the rotation speed adjustment unit 32 is connected to the motor in the gas suction pump 22 via an inverter 40. The rotation speed adjustment unit 32 adjusts the frequency of the AC current supplied from the inverter 40 to the motor, thereby adjusting the flow rate of the gas sucked by the pressure reducing device 20 from the refrigerant flow path 11.

[0068] The rotation speed adjustment unit 32 receives and holds a target temperature of the refrigerant in the temperature control unit 16 or before it flows into the temperature control unit 16, for example, by an input device (not shown), and adjusts the rotation speed of the motor of the gas suction pump 22 so that the temperature detected by the first temperature sensor 101 or the second temperature sensor 102 coincides with the target temperature. In other words, the gas suction pump 22 may be controlled according to the difference between the temperature of the refrigerant detected by the first temperature sensor 101 or the second temperature sensor 102 and the target temperature.

[0069] In the control example described above, the gas suction pump 22 of the pressure reducing device 20 is controlled so that the temperature of the refrigerant matches the target temperature. Alternatively, the motor rotation speed may be adjusted so that the pressure of the refrigerant in the refrigerant flow path 11 matches the target value.

[0070] The valve opening adjustment unit 33 is electrically connected to the control valve 14 and the butterfly valve 18, and controls the operation of the control valve 14 and the butterfly valve 18. The valve opening adjustment unit 33 adjusts the opening of the control valve 14 to adjust the flow rate of the refrigerant flowing through the refrigerant flow path 11. The valve opening adjustment unit 33 also adjusts the opening of the butterfly valve 18 to adjust the amount of gas sucked in by the pressure reducing device 20.

[0071] The valve opening adjustment unit 33 receives and holds a target temperature of the refrigerant in the temperature control unit 16 or before it flows into the temperature control unit 16, for example, by an input device (not shown), and adjusts the opening of the control valve 14 or the opening of the butterfly valve 18 so that the temperature detected by the first temperature sensor 101 or the second temperature sensor 102 coincides with the target temperature. Such control of the opening of the control valve 14 or the butterfly valve 18 may be performed after the gas suction pump 22 is controlled so that the temperature of the refrigerant coincides with the target temperature and the operating state of the gas suction pump 22 is maintained constant.

[0072] (Refrigerant composition) Next, the refrigerant circulated in the cooling system S will be described. As described above, in this embodiment, the refrigerant is a substance that becomes liquid at atmospheric pressure and at a standard environmental temperature (for example, 25°C), and when expanded from this state in an environment of, for example, 0.1 atmospheric pressure, the temperature becomes -5°C or lower, and preferably when expanded in an environment of 0.01 atmospheric pressure, the temperature becomes -30°C or lower. In addition, the refrigerant is preferably a low-environmental-load refrigerant with a global warming potential (GWP) of 10 or lower. In the case of a substance with a boiling point of 30°C or higher under atmospheric pressure, the substance becomes liquid at atmospheric pressure and at a standard environmental temperature (for example, 25°C). The boiling point of the refrigerant used under atmospheric pressure may be 50°C or higher, 60°C or higher, or 70°C or higher.

[0073] Specifically, in this embodiment, the refrigerant may be preferably HFO-1336mzz-Z, which is non-flammable and has a GWP of 2. More specifically, the refrigerant may be Opteon SF33™ manufactured by Mitsui-Chemours Fluoroproducts, Inc.

[0074] FIG. 3 is a pH diagram of HFO-1336mzz-Z. When HFO-1336mzz-Z is depressurized from a state (St1) of about 33°C close to room temperature at about 0.100 MPa, which is close to atmospheric pressure, to 0.0149 MPa, its temperature drops to about -10°C (St2). When it is depressurized to 0.001 MPa, its temperature drops to about -50°C or lower. Then, when it absorbs a certain amount of heat from the state St2 where it has been cooled to about -10°C, it evaporates (St3). When it expands from this state St3 to about 0.100 MPa, which is close to atmospheric pressure, its temperature rises to about 50°C, which is higher than room temperature, while remaining in the gas phase (St4). Then, when it is cooled from state St4 to room temperature, it condenses into a gas-liquid mixed phase and is cooled to about 33°C.

[0075] Such HFO-1336mzz-Z is cooled, for example, by the cooler 12A in the reservoir tank 12, and transitions to the above-mentioned state St1, and then is depressurized by flowing out of the control valve 14, and can transition to, for example, state St2. The HFO-1336mzz-Z can transition from state St2 to state St3 by exchanging heat with a temperature control target in the temperature control unit 16, and then transitions from state St3 to state St4 by flowing out of the gas-liquid separator 17 to the outside of the decompression device 20. Therefore, the HFO-1336mzz-Z can be suitably used in the cooling system S.

[0076] There are various other refrigerants that can be used in the cooling system S, such as water and ethanol.

[0077] (operation) An example of the operation of the cooling system S will now be described.

[0078] First, in the cooling system S, a desired flow rate of refrigerant is stored in the refrigerant flow path 11 from the reservoir tank 12 to the gas-liquid separator 17. Then, for example, a target temperature of the refrigerant flowing through the temperature control unit 16 is input and held. Then, the pressure reducing device 20 is driven, and the pressure inside the portion downstream of the control valve 14 in the refrigerant flow path 11 is reduced to a pressure lower than atmospheric pressure by the pressure reducing device 20. At this time, the control valve 14 may be closed or may be narrowed to a small opening. Then, the pressure reducing device 20 adjusts the rotation speed of the motor of the gas suction pump 22 until the temperature detected by the first temperature sensor 101 coincides with the target temperature.

[0079] After the temperature detected by the first temperature sensor 101 coincides with the target temperature, at least one of the rotation speed of the motor of the gas suction pump 22, the opening degree of the control valve 14, and the opening degree of the butterfly valve 18 is controlled to maintain the target temperature. This completes the start-up operation. In the state after the rotation speed of the motor of the gas suction pump 22 is adjusted so that the temperature detected by the first temperature sensor 101 coincides with the target temperature, the pressure inside the part downstream of the control valve 14 in the refrigerant flow path 11 is reduced to a pressure lower than atmospheric pressure by the pressure reducing device 20, and the pressure inside the part upstream of the control valve 14 in the refrigerant flow path 11 is set to be higher than the pressure inside the part downstream, for example, atmospheric pressure. However, the pressure inside the part upstream of the control valve 14 in the refrigerant flow path 11 does not have to be strictly atmospheric pressure, and may be a pressure slightly lower than atmospheric pressure.

[0080] Thereafter, the state is shifted to one in which the temperature control target is cooled by temperature control unit 16. After the refrigerant exchanges heat in temperature control unit 16, the gas phase portion is sucked by pressure reducing device 20 and flows again into refrigerant flow path 11 from upstream end 11U of refrigerant flow path 11, and after being cooled on the way to control valve 14, it passes through control valve 14 and flows again into temperature control unit 16. In this way, the temperature control target is continuously cooled by the refrigerant.

[0081] That is, the operating state of the cooling system S will be described with reference to FIG. 3. The refrigerant that absorbs the heat of the temperature control target in the temperature control unit 16 flows from the downstream end 11D of the refrigerant flow path 11 through the pressure reducing device 20 into the upstream end 11U of the refrigerant flow path 11, and is cooled by the cooler 12A and the like before reaching the control valve 14, and transitions from state St4 to state St1 in FIG. 3. Then, the refrigerant flows out of the control valve 14, and is depressurized in the downstream portion of the control valve 14 in the refrigerant flow path 11, and transitions to state St2. Then, the refrigerant transitions from state St2 to state St3 by exchanging heat with the temperature control target in the temperature control unit 16. Then, the refrigerant transitions from state St3 to state St4 by flowing from the pressure reducing device 20 into the upstream portion of the control valve 14 in the refrigerant flow path 11. Then, the refrigerant is cooled before reaching the control valve 14, and transitions from state St4 to state St1. As a result, the temperature control target is continuously cooled by the refrigerant.

[0082] The cooling system S according to the first embodiment described above includes a refrigerant flow device 10 including a refrigerant flow path 11 for flowing a refrigerant and a control valve 14 provided in the refrigerant flow path 11 for controlling the flow of the refrigerant, and a pressure reducing device 20 including an inlet 20A connected to a downstream end 11D of the refrigerant flow path 11 for drawing gas from the refrigerant flow path 11 and an outlet 20B connected to an upstream end 11U of the refrigerant flow path 11 for allowing the gas drawn from the inlet 20A to flow into the refrigerant flow path 11 from the upstream end 11U of the refrigerant flow path 11. The refrigerant flow path 11 allows the refrigerant contained in the gas flowing in from the pressure reducing device 20 to flow. The refrigerant flow device 10 includes a temperature control unit 16 downstream of the control valve 14 in the refrigerant flow path 11 for cooling a temperature control target with the refrigerant.

[0083] Such a cooling system S makes it possible to use substances that have not been used in conventional refrigeration methods as refrigerants in a thermal cycle, or to expand the range of substances that can be used as refrigerants in a thermal cycle.

[0084] That is, as described above, in this embodiment, as an example, a substance that becomes liquid under atmospheric pressure and at a standard environmental temperature (for example, 25°C) and becomes -5°C or lower when expanded from this state in an environment of, for example, 0.1 atmospheric pressure can be used as the refrigerant. On the other hand, if the above-mentioned substance is used in a vapor compression refrigeration cycle that has been widespread up to now, for example, the compressor compresses the liquid, so that the compressor does not function properly and the substance does not evaporate in the evaporator. Therefore, the above-mentioned refrigerant is not suitable for the vapor compression refrigeration cycle. On the other hand, the cooling system S does not use compression, but reduces the pressure of the above-mentioned refrigerant in the downstream part of the control valve 14 in the refrigerant flow path 11, thereby making it possible to cool the temperature control target, and the heat of the temperature control target can be released from the upstream part of the control valve 14 in the refrigerant flow path 11, thereby realizing a heat cycle. Therefore, according to this embodiment, it becomes possible to use a substance that has not been used in a conventional refrigeration method as a refrigerant for a heat cycle, or to expand the range of substances that can be used as a refrigerant for a heat cycle.

[0085] As described above, the cooling system S can use, for example, HFO-1336mzz-Z, which has a GWP of 2 and is non-flammable, as a refrigerant. This allows for a cooling operation with low GWP and safety that is not currently possible with a vapor compression refrigeration cycle. No other cooling system S is known that has such a low GWP, low environmental impact, and ensures safety. Therefore, the realization of such a cooling system S has the potential to greatly contribute to protecting the global environment. In addition, since the cooling system S does not use a compressor, the situation in which lubricating oil flows out into the refrigerant is suppressed, which is also beneficial in this respect.

[0086] Furthermore, the cooling system S includes a gas-liquid separator 17 downstream of the temperature control unit 16 in the refrigerant flow path 11, which separates the gas phase and liquid phase of the refrigerant that has passed through the temperature control unit 16 so that the gas phase portion flows downstream of the liquid phase portion. This configuration suppresses a situation in which the liquid phase refrigerant is sucked into the pressure reducing device 20 from the downstream end 11D of the refrigerant flow path 11. This allows the pressure reducing device 20 to operate in a stable state, improving the stability of the operation of the cooling system S.

[0087] Furthermore, the refrigerant flow device 10 includes a reservoir tank 12, upstream of the control valve 14 in the refrigerant flow path 11, for storing the refrigerant that has changed from a gas state to a liquid state after flowing from the pressure reducing device 20 into the refrigerant flow path 11. The control valve 14 controls the flow of the liquid-phase refrigerant that flows in from the reservoir tank 12. In this configuration, the refrigerant in a gas phase, which has a relatively high temperature, among the refrigerant that has flowed from the pressure reducing device 20 into the refrigerant flow path 11, is prevented from flowing to the downstream side of the control valve 14 in the refrigerant flow path 11. This allows the temperature control unit 16 to perform desired cooling.

[0088] The refrigerant flow device 10 also includes a two-phase flow separator 15 between the control valve 14 and the temperature control unit 16 in the refrigerant flow passage 11. The two-phase flow separator 15 includes an inlet 15A through which the refrigerant from the control valve 14 flows in, and an outlet 15B that is provided below the inlet 15A and through which the refrigerant that flows in from the inlet 15A flows out. In this configuration, the high-temperature phase of the refrigerant that flows into the two-phase flow separator 15 is prevented from suddenly flowing out downstream. This allows the temperature control unit 16 to perform desired cooling.

[0089] In this embodiment, the portion of the refrigerant flow path 11 between the control valve 14 and the temperature control unit 16 and the portion of the refrigerant flow path 11 downstream of the temperature control unit 16 constitute an internal heat exchanger 19 that allows the refrigerants flowing therethrough to exchange heat with each other. In this configuration, the refrigerant flowing through the portion of the refrigerant flow path 11 between the control valve 14 and the temperature control unit 16 can be cooled. The refrigerant flowing through the portion of the refrigerant flow path 11 between the temperature control unit 16 and the gas-liquid separator 17 can be heated. This causes the temperature of the refrigerant flowing into the temperature control unit 16 to be further lowered, and the refrigerant flowing into the gas-liquid separator 17 to be more easily vaporized. Therefore, the cooling system S can be operated in a desired state.

[0090] <Application Examples> Application examples of the cooling system S according to the above-described embodiment will be described below with reference to Fig. 4 to Fig. 7. The cooling system S in the application examples described below includes the same components as those in the above-described embodiment unless otherwise specified.

[0091] (Application example 1) FIG. 4 is a schematic diagram of a plasma etching apparatus 200 including a cooling system S. The plasma etching apparatus 200 includes an electrostatic chuck 201. The electrostatic chuck 201 includes a plate-shaped base plate 202, and adsorbs and holds a wafer W on the surface of the base plate 202. The base plate 202 and the temperature control unit 16 of the cooling system S are connected so that the temperature control unit 16 passes through the inside of the base plate 202. The temperature control unit 16 can cool the base plate 202 and the wafer W by absorbing heat from the base plate 202. In this example, the first temperature sensor 101 of the cooling system S is configured to detect the temperature of the base plate 202. The base plate 202 also includes a built-in heater 203. The plasma etching apparatus 200 can cool and heat the wafer W. The cooling system S in FIG. 4 includes a fan 120 for cooling a portion of the coolant flow passage 11 upstream of the reservoir tank 12. This promotes liquefaction of the refrigerant that has flowed from the pressure reducing device 20 into the refrigerant flow passage 11. Such a fan 120 can also be applied to the cooling system S in the above-described embodiment and the following application example.

[0092] (Application example 2) 5 is a schematic diagram of a cooking appliance 210 equipped with a cooling system S. The cooking appliance 210 is a so-called cold plate, and is equipped with a cooking plate 211 cooled by a temperature control unit 16 of the cooling system S. The temperature control unit 16 is connected to the cooking plate 211 in a state where it passes through the inside of the cooking plate 211. In this example, a first temperature sensor 101 of the cooling system S is configured to detect the temperature of the cooking plate 211.

[0093] (Application example 3) 6 is a schematic diagram of a molding apparatus 220 equipped with a cooling system S. The molding apparatus 220 is equipped with a mold 221 cooled by a temperature control unit 16 of the cooling system S. The temperature control unit 16 is connected to the mold 221 in a state where it passes through the inside of the mold 221. In this example, a first temperature sensor 101 of the cooling system S is configured to detect the temperature of the mold 221.

[0094] (Application example 4) FIG. 7 is a schematic diagram of a refrigerated warehouse 230 equipped with a cooling system S. The refrigerated warehouse 230 includes a warehouse body 231 and a duct 232 connected to the warehouse body 231. The duct 232 is connected to the warehouse body 231 at both ends, draws in gas from the warehouse body 231 at one end, and allows the drawn gas to flow into the warehouse body 231 from the other end. A fan 233 is disposed in the duct 232, and a temperature control unit 16 of the cooling system S is also disposed in the duct 232. By rotating the fan 233, gas is drawn in from the warehouse body 231, and the gas is cooled by the temperature control unit 16. As a result, the cooled gas flows into the warehouse body 231 from the duct 232. In the example shown in FIG. 7, the first temperature sensor 101 for detecting the temperature of the temperature control unit 16 is not provided, but the first temperature sensor 101 may be provided.

[0095] Although the embodiment of the present invention has been described above, the present invention is not limited to the embodiment described above, and various modifications can be made to the above-described embodiment. Furthermore, the cooling system S can be used for various purposes other than the application examples exemplified above.

[0096] Hereinafter, a cooling system Sv according to a modified example will be described with reference to Fig. 8. In this cooling system Sv, the temperature control unit 16 and the gas-liquid separator 17 are integrated, and the temperature control unit 16 is not provided between the control valve 14 and the two-phase flow separator 15 as in the above-mentioned embodiment. The gas-liquid separator 17 is configured to cool a temperature-controlled object with a liquid-phase refrigerant therein. In the example of Fig. 8, the temperature-controlled object is a heat medium flowing through a heat medium piping member 240. The heat medium piping member 240 is connected to the gas-liquid separator 17 so as to pass through the inside of the gas-liquid separator 17.

[0097] The cooling system Sv also includes a dryer 13, a control valve 14, a two-phase flow separator 15, a temperature control unit 16, a gas-liquid separator 17, a butterfly valve 18, and an internal heat exchanger 19, which are similar to those in the above-described embodiment. Each of these components is similar to those in the above-described embodiment. In the cooling system Sv, the temperature control target is cooled by a liquid-phase refrigerant inside the gas-liquid separator 17, but cooling may also be performed by a gas-phase refrigerant. The cooling system Sv may also be configured to perform cooling on the outer surface of the gas-liquid separator 17. [Explanation of symbols]

[0098] S…Cooling system 10…Refrigerant flow device 11... Coolant flow path 11U...Upstream end 11D…Downstream end 12…Reservoir tank 12A…Cooler 14...Control valve 15…Two-layer flow separator 16...Temperature control unit 17... Gas-liquid separator 18…Butterfly valve 19...Internal heat exchanger 20...Decompression device 20A…Inlet 20B…Outlet 30…Controller

Claims

1. a refrigerant flow device including a refrigerant flow path through which a refrigerant flows and a control valve provided in the refrigerant flow path to control the flow of the refrigerant; a pressure reducing device including an inlet connected to a downstream end of the refrigerant flow path and for drawing gas from the refrigerant flow path, and an outlet connected to an upstream end of the refrigerant flow path and for allowing the gas drawn from the inlet to flow from the upstream end of the refrigerant flow path into the refrigerant flow path, the refrigerant flow path allows the refrigerant contained in the gas flowing in from the pressure reducing device to flow; The refrigerant flow device includes a temperature control unit, located downstream of the control valve in the refrigerant flow path, that cools a temperature-controlled object with the refrigerant.

2. 2. The cooling system of claim 1, wherein the refrigerant flow device is provided with a gas-liquid separator downstream of the temperature control section in the refrigerant flow path, which separates the gas phase portion and the liquid phase portion of the refrigerant that has passed through the temperature control section so that the gas phase portion and the liquid phase portion flow downstream of the liquid phase portion.

3. the refrigerant flow device includes a reservoir tank located upstream of the control valve in the refrigerant flow path, the reservoir tank storing the refrigerant that has changed from the gas phase to a liquid phase and that has flowed into the refrigerant flow path from the pressure reducing device, The cooling system according to claim 1 , wherein the control valve controls the flow of the liquid-phase refrigerant flowing from the reservoir tank.

4. The cooling system according to claim 3 , wherein the reservoir tank includes a cooler that cools the gas flowing in from the pressure reducing device and liquefies the refrigerant from the gas.

5. the refrigerant flow device includes a two-phase flow separator between the control valve and the temperature control unit in the refrigerant flow path, 2. The cooling system of claim 1, wherein the two-phase flow separator includes an inlet through which the refrigerant from the control valve flows, and an outlet located below the inlet and through which the refrigerant flowing in from the inlet flows out.

6. 2. The cooling system according to claim 1, wherein a portion of the refrigerant flow path between the control valve and the temperature control unit and a portion of the refrigerant flow path downstream of the temperature control unit constitute internal heat exchangers that enable the refrigerants flowing through each of the portions to exchange heat with each other.

7. 2. The cooling system of claim 1, wherein the operation of the pressure reducing device and the throttling state of the control valve create a condition in which the pressure inside the portion of the refrigerant flow path downstream of the control valve is lower than the pressure inside the portion of the refrigerant flow path upstream of the control valve.

8. The cooling system according to claim 1 , wherein the refrigerant is a substance having a boiling point of 30° C. or higher under atmospheric pressure.

9. The cooling system of claim 8 , wherein the refrigerant has a GWP of 10 or less.

10. 10. The cooling system of claim 9, wherein the refrigerant is HFO-1336mzz-Z.

11. The cooling system according to claim 1 , wherein the pressure reducing device reduces the pressure in a portion of the refrigerant flow path downstream of the control valve to a pressure lower than atmospheric pressure.

12. The cooling system according to claim 1 , wherein the pressure reducing device is a dry vacuum pump or a wet vacuum pump.

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