Cooling system

Abstract

A cooling system according to one embodiment is provided with: a sealed container (10) that contains a first outlet (11) and an inlet (13) and that stores a liquid refrigerant; a decompression device (20) that is connected to the first outlet (11) and that adjusts the pressure within the sealed container (10) to a pressure lower than atmospheric pressure by suctioning gas from the sealed container (10) through the first outlet (11); and a refrigerant circulation device (30) that includes a refrigerant flow path (31) connected to the pressure reducing device (20) and the inlet (13), and that causes a liquid refrigerant, which is obtained by liquefying a gas sucked from the sealed container (10) by the pressure reducing device (20), to flow into the sealed container (10) through the inlet (13).

Description

Technical Field

[0001] An embodiment of the present invention relates to a cooling system utilizing a temperature drop of a refrigerant caused by decompression. Background Art

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

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

[0004] The refrigerant used in the vapor compression refrigeration device is generally a fluorine-based refrigerant. Fluorine-based refrigerants are greenhouse gases and sometimes flammable, but they have various advantages such as enabling highly efficient operation.

[0005] On the other hand, considering the impact of fluorine-based refrigerants on the environment, the development of fluorine-based refrigerants for steam compression that can suppress the global warming potential (GWP) to a low level has been ongoing. In addition, HFO-based refrigerants for steam compression with very low GWP have been put into practical use. Specifically, for example, HFO-based refrigerants with a GWP of less than 10 have been put into practical use. However, this refrigerant is in a state where the safety of flammability and toxicity may not be fully ensured. Therefore, the development of steam compression refrigerants that can ensure low GWP and safety is also popular now.

[0006] In addition, the compressor used in the steam compression refrigeration device is in operation for a long time. Therefore, it is necessary to lubricate the driving parts such as the rotating parts with lubricating oil. However, there is a problem of the lubricating oil flowing out to the refrigerant side. In addition, due to the outflow of the lubricating oil, sometimes the oil in the compressor is cut off, and sometimes the stability of the operation of the compressor is impaired. In addition, since the lubricating oil is retained in the evaporator, the cooling efficiency of the evaporator is sometimes impaired. Therefore, there is room for improvement in the use of compressors in steam compression refrigeration devices.

[0007] On the other hand, as a cooling device that does not use a compressor, for example, boiling cooling devices disclosed in JP2011-142298A, WO2017 / 119113A1, and JP2021-162195A are known.

[0008] When the boiling cooling device makes the liquid exchange heat with the temperature control object, it can efficiently cool the temperature control object by absorbing heat based on latent heat by vaporizing the liquid. In addition, a pump is usually required to circulate the liquid or its vaporized gas, but the pump does not require lubricating oil or even if it needs lubricating oil, it can be a small amount. In addition, 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 boiling cooling devices, the temperature of the circulating liquid is usually near the boiling point under atmospheric pressure, and cooling cannot be performed in a temperature range significantly below 0°C, for example, and the cooling temperature and temperature control object are very limited. Therefore, it is difficult to ensure high refrigeration capacity in a low or ultra-low temperature range using boiling cooling devices. Summary of the invention

[0010] In recent years, HFO-based refrigerants have been developed as described above, and on the other hand, antifreeze liquids with low environmental load have also been developed. Moreover, HFO-based solvents that are low in GWP and non-flammable and can be used as antifreeze liquids have been put into practical use. Such solvents have a boiling point of, for example, 70°C or more at atmospheric pressure, and are therefore not suitable for vapor compression refrigeration devices. However, if such HFO-based solvents can be used to achieve a heat cycle, it is possible to achieve a cooling system that can ensure the low environmental load, high safety, and high refrigeration capacity that are strongly required now.

[0011] Therefore, the inventors of the present application have conducted in-depth research to realize a new cooling system that can use HFO-based solvents such as the above-mentioned as refrigerants for heat cycles. More generally, in order to realize a new cooling system that can convert a range of substances different from the range of refrigerants that can be used in a vapor compression refrigeration device into a refrigerant that can be used in a heat cycle, in-depth research has been conducted. And, it was found that the above-mentioned cooling system can be realized by a structure in which the heat absorbed by the refrigerant is released at atmospheric pressure after the temperature of the refrigerant is lowered by reducing the pressure, and the refrigerant is cooled, thereby completing the present invention.

[0012] That is, an object of the present invention is to provide a cooling system capable of using a substance that has not been used in conventional refrigeration methods as a refrigerant for a heat cycle or capable of expanding the range of substances that can be used as a refrigerant for a heat cycle.

[0013] One embodiment of the present invention relates to the following aspects “1” to “18”.

[0014] [1] A cooling system comprising: a container including an outflow port and an inflow port, the container storing a liquid refrigerant; a pressure reducing device connected to the outflow port, which adjusts the pressure in the container to a pressure lower than the atmospheric pressure by sucking gas from the container through the outflow port; and a refrigerant circulation device including a refrigerant flow path connected to the pressure reducing device and the inflow port, so that the liquid refrigerant obtained by liquefying the gas sucked from the container by the pressure reducing device flows into the container through the inflow port, and the temperature control object is cooled by the refrigerant in the container.

[0015] [2] According to the cooling system described in [1], the pressure reducing device includes: a gas flow path connected to the outflow port; a gas suction pump arranged in the gas flow path and sucking the gas from the container to the gas flow path; and a storage tank connected to the gas flow path and storing the gas flowing out of the gas flow path and / or the liquid refrigerant obtained by liquefying the gas, and the refrigerant flow path is connected to the storage tank.

[0016] [3] The cooling system according to [2], wherein the pressure in the storage tank is higher than the pressure in the container, and the storage tank liquefies at least a portion of the gas flowing out of the gas flow path into the liquid refrigerant and stores the liquid refrigerant.

[0017] [4] The cooling system according to [2] or [3], wherein the refrigerant circulation device further includes a circulation pump, which is arranged in the refrigerant flow path and introduces the liquid refrigerant from the storage tank into the refrigerant flow path.

[0018] [5] The cooling system according to any one of [2] to [4], wherein the decompression device further includes a cooling unit that cools a portion of the gas flow path on the downstream side of the gas suction pump and / or the storage tank.

[0019] [6] A cooling system according to any one of [2] to [5], wherein the refrigerant circulation device further includes a buffer container, which is arranged in the refrigerant flow path in a manner to form a part of the refrigerant flow path, and stores the liquid refrigerant, and the liquid refrigerant introduced into the refrigerant flow path from the storage tank flows into the container after passing through the buffer container.

[0020] [7] A cooling system according to [6], wherein the cooling system further comprises a heat exchanger connected to the refrigerant flow path for cooling the liquid refrigerant flowing in the refrigerant flow path, and the buffer container is disposed in a portion of the refrigerant flow path that is closer to the upstream side than a portion connected to the heat exchanger.

[0021] [8] The cooling system according to [6] or [7], wherein the storage tank is arranged above the buffer container.

[0022] [9] A cooling system according to any one of [2] to [8], wherein the gas suction pump is configured to suck the gas by rotating a motor, and the gas suction pump adjusts the rotation speed of the motor according to the temperature in the container, the pressure in the container, the temperature of the heat medium after being cooled by the refrigerant, or the temperature of the temperature control object.

[0023]

[10] A cooling system according to any one of [2] to [9], wherein a flow control valve is provided in the gas flow path on the upstream side or downstream side of the gas suction pump, and the flow control valve controls the flow rate of the gas flowing in the gas flow path by adjusting the opening degree, and the opening degree of the flow control valve is adjusted according to the temperature in the container, the pressure in the container, the temperature of the heat medium after being cooled by the refrigerant, or the temperature of the temperature control object.

[0024]

[11] A cooling system according to any one of [2] to

[10] , wherein the cooling system also has a gas supply device for supplying gas into the container, and the gas supply device adjusts the amount of the gas supplied into the container according to the temperature in the container, the pressure in the container, the temperature of the heat medium after being cooled by the refrigerant, or the temperature of the temperature control object.

[0025]

[12] A cooling system according to any one of [1] to

[11] , wherein the cooling system also has a heat exchanger connected to the refrigerant flow path for cooling the liquid refrigerant flowing in the refrigerant flow path, the refrigerant circulation device includes a three-way valve, the three-way valve is arranged in a portion of the refrigerant flow path that is downstream of a portion connected to the heat exchanger, and includes a first port, a second port, and a third port, the three-way valve is capable of regulating a flow rate of the refrigerant flowing into the first port and flowing out of the second port and a flow rate of the refrigerant flowing into the first port and flowing out of the third port, the three-way valve constitutes a portion of the refrigerant flow path through the flow path between the first port and the second port, and the third port is connected to a portion of the refrigerant flow path that is upstream of the portion connected to the heat exchanger via a bypass flow path.

[0026]

[13] A cooling system according to

[12] , wherein, when the liquid level of the liquid refrigerant in the container exceeds a specified height, the three-way valve reduces the flow rate of the refrigerant flowing into the first port and flowing out of the second port, and increases the flow rate of the refrigerant flowing into the first port and flowing out of the third port; and when the liquid level of the liquid refrigerant in the container is lower than a specified height, the three-way valve increases the flow rate of the refrigerant flowing into the first port and flowing out of the second port, and reduces the flow rate of the refrigerant flowing into the first port and flowing out of the third port.

[0027]

[14] A cooling system according to

[12] , wherein, when the liquid level of the liquid refrigerant in the container exceeds a specified height, the three-way valve cuts off the flow of the refrigerant flowing into the first port and flowing out of the second port, and allows the flow of the refrigerant flowing into the first port and flowing out of the third port; and when the liquid level of the liquid refrigerant in the container is lower than a specified height, the three-way valve allows the flow of the refrigerant flowing into the first port and flowing out of the second port, and cuts off the flow of the refrigerant flowing into the first port and flowing out of the third port.

[0028]

[15] According to the cooling system described in any one of [1] to

[14] , the cooling system also has a heat medium circulation device, the heat medium circulation device includes a heat medium flow path for circulating the heat medium, the heat medium flow path includes a heat exchange part, the heat exchange part is arranged in the container, and the heat medium and the refrigerant exchange heat, the heat medium flow path transports the heat medium from the outside of the container to the heat exchange part, and the heat medium that has undergone heat exchange in the heat exchange part is transported to the outside of the container.

[0029]

[16] The cooling system according to any one of [1] to

[15] , wherein the refrigerant is a substance having a boiling point of 30° C. or higher under atmospheric pressure.

[0030]

[17] The cooling system according to any one of [1] to

[16] , wherein the GWP of the refrigerant is 10 or less.

[0031]

[18] The cooling system according to any one of [1] to

[17] , wherein the refrigerant is HFO-1336mzz-Z.

[0032] According to the present invention, it is 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a diagram schematically showing a cooling system according to the first embodiment.

[0034] Figure 2 It shows the composition Figure 1 Block diagram of the functional structure of the controller of the cooling system.

[0035] Figure 3 yes Figure 1 PH diagram of an example of a refrigerant used in a cooling system.

[0036] Figure 4 It is a diagram schematically showing a cooling system according to a second embodiment.

[0037] Figure 5 It is a diagram schematically showing a cooling system according to a third embodiment.

[0038] Figure 6 It is a diagram schematically showing a cooling system according to a fourth embodiment. DETAILED DESCRIPTION

[0039] Hereinafter, each embodiment will be described.

[0040] <First Embodiment>

[0041] Figure 1 This is a schematic diagram of the cooling system S1 according to the first embodiment. First, the configuration of the cooling system S1 will be described.

[0042] (Cooling system structure)

[0043] like Figure 1 As shown, the cooling system S1 of the first embodiment includes a sealed container 10 , a decompression device 20 , a refrigerant cycle device 30 , a heat exchanger 40 , a heat medium circulation device 50 , a gas supply device 60 , and a controller 100 .

[0044] In the cooling system S1, a liquid refrigerant is stored in a sealed container 10. The decompression device 20 is a device connected to the sealed container 10, and decompresses the pressure in the sealed container 10 by sucking the gas existing in the sealed container 10 or the gas vaporized in the sealed container 10. Then, the refrigerant circulation device 30 is connected to the decompression device 20, and the liquid refrigerant obtained by liquefying the gas sucked from the sealed container 10 by the decompression device 20 is circulated, and it flows into the sealed container 10 and returns. In addition, the refrigerant circulation device 30 is connected to the heat exchanger 40 outside the sealed container 10. Thus, the refrigerant circulating through the refrigerant circulation device 30 circulates between the sealed container 10 and the heat exchanger 40. In addition, the cooling system S1 cools the heat medium circulating in the sealed container 10 through the heat medium circulation device 50, and the heat medium circulation device 50 transports the cooled heat medium to the temperature control object T. In addition, the refrigerant circulation device 30 releases the heat absorbed by the refrigerant from the heat medium from the heat exchanger 40. Furthermore, in the present embodiment, the decompression device 20 also releases heat from the cooling unit 25 described later. Thereby, the heat medium is continuously cooled.

[0045] In the cooling system S1, as described later, the pressure in the sealed container 10 is reduced by the pressure reducing device 20 to a pressure lower than the atmospheric pressure. On the other hand, the refrigerant circulation environment in the refrigerant circulation device 30 outside the sealed container 10 and the refrigerant circulation environment of the heat exchanger 40 are at a pressure greater than the pressure in the sealed container 10, for example, set to atmospheric pressure. In such an environment, when the refrigerant flows from the heat exchanger 40 into the sealed container 10, the refrigerant expands and the temperature of the refrigerant drops in the sealed container 10. Thus, the refrigerant after the temperature is reduced in the sealed container 10 can be used to cool the heat medium. At this time, the refrigerant evaporates by heat exchange with the heat medium. In this case, the heat medium can be effectively cooled by the latent heat of vaporization of the refrigerant. In addition, the above-mentioned evaporated refrigerant is in a gaseous state and is sucked by the pressure reducing device 20.

[0046] The refrigerant circulating through the refrigeration cycle device 30 is not particularly limited, and is, for example, a substance that becomes liquid at atmospheric pressure and at a standard ambient temperature (e.g., 25°C), and a substance that becomes below -5°C when expanded from this state, for example, in an environment of 0.1 atmospheric pressure, and preferably becomes below -30°C when expanded in an environment of 0.01 atmospheric pressure. When such a substance is used as a refrigerant, it can be cooled to a low temperature region. In addition, in this specification, atmospheric pressure refers to 1 atmosphere, in other words, 0.1 MPa (Abs). The following describes each part of the cooling system S1 in detail.

[0047] The sealed container 10 includes a first outflow port 11, a second outflow port 12, an inflow port 13, a gas receiving port 14, a heat medium inlet 15, and a heat medium outlet 16, and is a container that prevents gas and liquid from flowing out and leaking out of the parts other than these ports (11 to 16). The sealed container 10 is a so-called vacuum insulation container that is configured to maintain its shape when the internal pressure is reduced.

[0048] The maintenance of the shape of the sealed container 10 during decompression also depends on the internal pressure of the decompression, but for example, when the pressure is reduced to 0.1 atmospheric pressure, the outer shell of the sealed container 10 is preferably formed by a hard metal with a large thickness. However, the specific structure of the sealed container 10 is not particularly limited as long as it is appropriately determined according to the degree of prescribed decompression. In addition, the sealed container 10 may also include a container body with an opening and a lid for opening and closing the opening. In this case, it is necessary to ensure sufficient airtightness and sealing when closing the lid.

[0049] The sealed container 10 stores liquid refrigerant, the symbol Lf represents the accumulation of liquid refrigerant, and the symbol Gf represents the gas phase. That is, in the present embodiment, the sealed container 10 forms the gas phase Gf and stores the liquid refrigerant. The pressure reducing device 20 described later reduces the pressure in the sealed container 10 by sucking the gas in the sealed container 10. Here, when the gas phase Gf is formed, the liquid refrigerant can be prevented from entering the pressure reducing device 20, and the operating state of the pressure reducing device 20 can be stabilized. In addition, the failure of the pressure reducing device 20 can be suppressed.

[0050] An environment in which the liquid refrigerant and the gas phase portion Gf coexist in the sealed container 10 can be formed by controlling the operations of the decompression device 20 , the refrigerant circulation device 30 , and the gas supply device 60 .

[0051] The first flow outlet 11 is connected to the pressure reducing device 20 and is an opening for allowing gas to flow out. Therefore, it is preferably opened in the gas phase part Gf of the sealed container. In addition, it is preferred that the gas receiving port 14 is connected to the gas supply device 60 as described later, and the gas receiving port 14 is also opened in the gas phase part Gf of the sealed container 10 in the same manner as the first flow outlet 11. The first flow outlet 11 and the gas receiving port 14 are preferably arranged on the upper wall or the upper part of the side wall of the sealed container 10. In the example shown in the figure, the first flow outlet 11 and the gas receiving port 14 are formed on the upper wall of the sealed container 10.

[0052] The second outflow port 12 is an opening for discharging the liquid refrigerant in the sealed container 10. The inflow port 13 is an opening for receiving the liquid refrigerant circulating through the refrigeration cycle device 30. The second outflow port 12 and the inflow port 13 are preferably opened in the liquid phase portion of the sealed container 10, and are preferably arranged at the lower part of the bottom wall or the side wall of the sealed container 10. In the example shown in the figure, the second outflow port 12 is formed on the bottom wall of the sealed container 10, and the inflow port 13 is formed at a position lower than the middle position of the side wall of the sealed container 10 in the up and down direction. In addition, the heat medium inlet 15 and the heat medium outlet 16 are preferably opened in the liquid phase portion of the sealed container 10, and in the example shown in the figure, the heat medium inlet 15 and the heat medium outlet 16 are formed on the bottom wall of the sealed container 10.

[0053] The decompression device 20 is connected to the first outlet 11, and sucks gas from the sealed container 10 through the first outlet 11, thereby adjusting the pressure in the sealed container 10 to a pressure lower than the atmospheric pressure. In detail, the decompression device 20 in this embodiment includes: a gas flow path 21, which is connected to the first outlet 11; a gas suction pump 22, which is provided on the gas flow path 21, and sucks gas from the sealed container 10 to the gas flow path 21; and a storage tank 23, which is connected to the downstream end 21B of the gas flow path 21, and stores the gas flowing out from the downstream end 21B.

[0054] The gas flow path 21 includes an upstream end 21A connected to the first outlet 11 and a downstream end 21B connected to the storage tank 23. The gas suction pump 22 is provided in the gas flow path 21 between the upstream end 21A and the downstream end 21B.

[0055] The form of the gas suction pump 22 is not particularly limited, but it is preferably a dry vacuum pump from which lubricating oil does not flow out or hardly flows out to the suction path (gas flow path 21). The dry vacuum pump may be a diaphragm dry vacuum pump, a swing piston dry vacuum pump, a rotary vane dry vacuum pump, a scroll dry vacuum pump, etc., which are different from the above examples. However, the gas suction pump 22 may also be a wet vacuum pump.

[0056] The gas suction pump 22 in this embodiment is a dry vacuum pump. Moreover, the gas suction pump 22 includes a motor 22M controlled by an inverter, such as an AC motor or a brushless DC motor. In addition, the gas suction pump 22 adjusts the suction amount of the gas by adjusting the rotation speed of the motor 22M, thereby being able to adjust the pressure in the sealed container 10. In detail, the rotation speed of the motor 22M is adjusted by adjusting the frequency of the AC current supplied to the motor 22M using an inverter not shown in the figure.

[0057] In addition, in the present embodiment, a flow control valve 24 is provided in the gas flow path 21, and the pressure in the sealed container 10 can be adjusted by adjusting the opening of the flow control valve 24. The flow control valve 24 can adjust the flow rate of the gas flowing in the gas flow path 21 by adjusting its opening. Thus, the suction amount of the gas is adjusted, and thus the pressure in the sealed container 10 can be adjusted.

[0058] The gas suction pump 22 and the flow control valve 24 can also be operated simultaneously to adjust the pressure in the sealed container 10. In addition, the operating state of the gas suction pump 22 can be maintained constant and the opening of the flow control valve 24 can be adjusted, or the opening of the flow control valve 24 can be maintained constant and the operating state of the gas suction pump 22 can be controlled.

[0059] The flow control valve 24 is provided in the gas flow path 21 upstream of the gas suction pump 22 in this embodiment, but may be provided downstream of the gas suction pump 22. The flow control valve 24 is constituted by a butterfly valve, for example, but is not particularly limited.

[0060] The gas suction pump 22 and the flow control valve 24 are electrically connected to the controller 100 and controlled by the controller 100. In the present embodiment, the gas suction pump 22 is electrically connected to the controller 100 via an inverter not shown. The flow control valve 24 may be a valve that adjusts the opening of the valve core by an electric motor such as a stepping motor or a servo motor. In this case, the controller 100 is electrically connected to the electric motor. In addition, the flow control valve 24 may also be an electromagnetic proportional valve or the like.

[0061] The pressure in the storage tank 23 is higher than the pressure in the sealed container 10, and is set to, for example, atmospheric pressure. Thus, the storage tank 23 liquefies at least a portion of the gas flowing out from the downstream end 21B of the gas flow path 21 into a liquid refrigerant, and the liquid refrigerant can be easily stored. In order to suppress the power consumption of the gas suction pump 22 when the pressure rises, for safety reasons, and also for the filling or replenishment of the refrigerant, the storage tank 23 may also have, for example, a lid that can be opened and closed. That is, the storage tank 23 may also include a container body having an opening and a lid for opening and closing the opening. In this case, it is necessary to ensure sufficient airtightness and sealing when the lid is closed.

[0062] In the present embodiment, the decompression device 20 further includes a cooling unit 25 for cooling a portion of the gas flow path 21 on the downstream side of the gas suction pump 22. As a result, the liquefaction of the gas flowing out from the downstream end 21B of the gas flow path 21 is promoted, so that, for example, the pressure rise in the storage tank 23 can be suppressed. The cooling unit 25 is composed of a cooling fan, for example. However, the structure of the cooling unit 25 is not particularly limited, and it may also be a heat exchanger or the like. In addition, the cooling unit 25 may also cool the storage tank 23. In this case, the cooling unit 25 may cool the inside of the storage tank 23 or the outside.

[0063] The refrigerant circulation device 30 includes: a refrigerant flow path 31 connected to the decompression device 20 and the inlet 13; and a circulation pump 32 provided in the refrigerant flow path 31 to introduce the liquid refrigerant in the storage tank 23 into the refrigerant flow path 31. Specifically, the refrigerant flow path 31 is connected to the storage tank 23 in the decompression device 20. The refrigerant circulation device 30 circulates the liquid refrigerant received from the storage tank 23 and flows into the sealed container 10 from the inlet 13.

[0064] In addition, the refrigerant cycle device 30 in the present embodiment further includes a buffer container 33 and a three-way valve 34 provided in the refrigerant flow path 31. In the present embodiment, the circulation pump 32, the buffer container 33, and the three-way valve 34 are provided in the refrigerant flow path 31 so as to constitute a part of the refrigerant flow path 31. The circulation pump 32 is arranged on the downstream side of the buffer container 33, and the three-way valve 34 is arranged on the downstream side of the circulation pump 32, but such an arrangement is not particularly limited.

[0065] The refrigerant flow path 31 includes an upstream end 31A connected to the storage tank 23 and a downstream end 31B connected to the inlet 13. The upstream end 31A is connected to the bottom wall of the storage tank 23 and communicates with the storage tank 23. The circulation pump 32, the buffer container 33 and the three-way valve 34 are respectively provided in the refrigerant flow path 31 between the upstream end 31A and the downstream end 31B.

[0066] The form of the circulation pump 32 is not particularly limited, and it can be a non-displacement pump or a displacement pump. The circulation pump 32 includes, for example, a motor 32M controlled by an inverter, such as an AC motor or a brushless DC motor. In addition, the circulation pump 32 adjusts the amount of liquid introduced by adjusting the rotation speed of the motor 32M, thereby being able to adjust the flow rate of the refrigerant circulating in the refrigerant flow path 31. In detail, the rotation speed of the motor 32M is adjusted by adjusting the frequency of the AC current supplied to the motor 32M using an inverter not shown.

[0067] In addition, when the refrigerant passes through the circulation pump 32, the pressure of the refrigerant is increased. When the refrigerant pressure is increased, the temperature of the refrigerant rises. The heat exchanger 40 is connected to the refrigerant flow path 31, and the heat exchanger 40 is connected to the refrigerant flow path 31 on the downstream side of the circulation pump 32. Thus, the heat exchanger 40 can efficiently cool the refrigerant.

[0068] The buffer container 33 includes a receiving port 33A for receiving the refrigerant introduced from the storage tank 23 and a discharge port 33B for allowing the refrigerant to flow out. Thus, the liquid refrigerant introduced from the storage tank 23 into the refrigerant flow path 31 flows from the receiving port 33A through the discharge port 33B, passes through the buffer container 33, and then flows into the sealed container 10.

[0069] The buffer container 33 stores a certain amount of liquid refrigerant. The buffer container 33 of the present embodiment stores the liquid refrigerant in a manner that fills the storage space. The storage space of the buffer container 33 may not be filled with the liquid refrigerant. However, the more liquid refrigerant occupies the storage space of the buffer container 33, the smoother the refrigerant can be discharged from the discharge port 33B. From this point of view, it is preferred that the storage space of the buffer container 33 is filled with liquid refrigerant. Even if this is not the case, the amount of liquid refrigerant stored in the storage space of the buffer container 33 may be 50% or more in proportion to the volume of the storage space, and may be 70% or more, 80% or more, or 90% or more.

[0070] In the present embodiment, the discharge port 33B is provided at the lower portion of the side wall of the buffer container 33. Thus, the refrigerant can smoothly pass through the buffer container 33.

[0071] The buffer container 33 receives the liquid refrigerant from the receiving port 33A, but in the present embodiment, by arranging the storage tank 23 above the buffer container 33, the liquid refrigerant stored in the storage tank 23 can be smoothly transported to the buffer container 33 by its own weight. The receiving port 33A is provided at the upper portion of the buffer container 33, specifically, at the upper wall, thereby reducing the length of the piping between the storage tank 23 and the buffer container 33 in the refrigerant flow path 31.

[0072] The buffer container 33 basically receives liquid refrigerant from the receiving port 33A, but sometimes receives gas including non-liquefied gasified refrigerant. Here, there is a case where the temperature of the liquid refrigerant or gas received by the buffer container 33 is relatively high, but when the liquid refrigerant or gas from the storage tank 23 flows into the buffer container 33 storing the liquid refrigerant, it is possible to suppress the temperature of the refrigerant circulating through the refrigerant cycle device 30 from being unexpectedly disturbed. That is, even when the temperature of the liquid refrigerant or gas received by the buffer container 33 is relatively high, the refrigerant or gas can flow out of the buffer container 33 after mixing with the liquid refrigerant already stored in the buffer container 33, so it is possible to suppress the temperature of the refrigerant circulating on the downstream side of the buffer container 33 from being unexpectedly disturbed.

[0073] The three-way valve 34 is provided in a portion of the refrigerant flow path 31 that is downstream of a portion connected to a heat exchanger 40 described later. The three-way valve 34 includes a first port 341, a second port 342, and a third port 343. The three-way valve 34 can adjust the flow rate of the refrigerant that flows into the first port 341 and flows out from the second port 342 and the flow rate of the refrigerant that flows into the first port 341 and flows out from the third port 343.

[0074] The three-way valve 34 forms a part of the refrigerant flow path 31 by the flow path between the first port 341 and the second port 342. In addition, the third port 343 is connected to a portion of the refrigerant flow path 31 that is upstream of the portion connected to the heat exchanger 40 through the bypass flow path 38. In detail, the bypass flow path 38 is connected to the buffer container 33. Therefore, in the present embodiment, the three-way valve 34 can deliver part or all of the refrigerant cooled by the heat exchanger 40 in the refrigerant flow path 31 to the buffer container 33, instead of delivering it to the sealed container 10.

[0075] The amount of liquid refrigerant stored in the sealed container 10 can be increased or decreased according to the operating state of the cooling system S1. When the amount of liquid refrigerant stored in the sealed container 10 becomes excessive, the risk of the decompression device 20 sucking the liquid refrigerant increases. For example, in such a case, the three-way valve 34 reduces or cuts off the flow rate of the refrigerant flowing to the sealed container 10 side, thereby avoiding the situation where there is too much liquid refrigerant in the sealed container 10.

[0076] The three-way valve 34 in this embodiment is a proportional three-way valve. The three-way valve 34 may also be a valve that adjusts the opening of the valve core by an electric motor such as a stepping motor or a servo motor, in which case the electric motor is electrically connected to the controller 100. However, the three-way valve 34 may be an electromagnetic proportional three-way valve or a two-position three-way valve.

[0077] In addition, as described above, the second outflow port 12 in the sealed container 10 is an opening for discharging the liquid refrigerant in the sealed container 10, but in the present embodiment, the second outflow port 12 is connected to the refrigerant flow path 31 through the exhaust flow path 28, and more specifically, is connected to the buffer container 33. In addition, an exhaust control valve 29 is provided in the exhaust flow path 28. The exhaust flow path 28 enables the liquid refrigerant in the sealed container 10 to flow directly into the buffer container 33 by opening the exhaust control valve 29. The exhaust control valve 29 may also be opened when the amount of liquid refrigerant stored in the sealed container 10 is excessive.

[0078] The heat exchanger 40 is connected to a portion of the refrigerant flow path 31 downstream of the circulation pump 32 and upstream of the three-way valve 34. As described above, the cooling system S1 cools the heat medium that flows through the heat medium circulation device 50 in the sealed container 10. In addition, the refrigerant circulation device 30 releases the heat absorbed by the refrigerant from the heat medium from the heat exchanger 40. That is, the heat exchanger 40 cools the liquid refrigerant that flows in the refrigerant flow path 31.

[0079] The heat exchanger 40 in this embodiment is a liquid-cooled heat exchanger, and is connected to a cooling water flow path 44 through which cooling water for cooling the refrigerant flows. The cooling water may be water or other liquids. Alternatively, the heat exchanger 40 may be an air-cooled heat exchanger.

[0080] The heat medium circulation device 50 includes a heat medium flow path 51 for circulating the heat medium, a heat exchange unit 52 provided in the heat medium flow path 51, and a pump 53. In the heat medium circulation device 50 of the present embodiment, the heat exchange unit 52 and the pump 53 are provided between the upstream end 51A and the downstream end 51B of the heat medium flow path 51, and the upstream end 51A and the downstream end 51B of the heat medium flow path 51 are connected to the temperature control object T. Thus, the heat medium circulation device 50 circulates the heat medium through the temperature control object T.

[0081] In detail, the heat medium flow path 51 of the present embodiment enters the sealed container 10 from the heat medium inlet 15 of the sealed container 10, and then extends to the outside of the sealed container 10 from the heat medium outlet 16. In addition, the upstream end 51A, the downstream end 51B and the temperature control object T of the heat medium flow path 51 are located outside the sealed container 10. In addition, in the heat medium circulation device 50 of the present embodiment, the heat exchange part 52 is provided in the portion of the heat medium flow path 51 located inside the sealed container 10, that is, the heat exchange part 52 is arranged inside the sealed container 10. Thus, the heat medium flow path 51 transports the heat medium from the outside of the sealed container 10 to the heat exchange part 52, and transports the heat medium that has undergone heat exchange in the heat exchange part 52 to the outside of the sealed container 10.

[0082] The heat medium is not particularly limited, and in the present embodiment, it is an antifreeze liquid. The heat medium may also be the same as the refrigerant circulating between the sealed container 10 and the heat exchanger 40. That is, the heat medium is a substance that becomes below -5°C when it is expanded from a state of a standard ambient temperature (e.g., 25°C) under, for example, atmospheric pressure, and under, for example, an environment of 0.1 atmosphere pressure, and preferably becomes below -30°C when it is expanded under, for example, an environment of 0.01 atmosphere pressure. When the refrigerant is the same as the heat medium, it is advantageous in terms of manufacturing efficiency and cost. However, the heat medium may also be water or the like.

[0083] The heat exchange unit 52 exchanges heat between the circulating heat medium and the refrigerant in the sealed container 10. The heat exchange unit 52 may be composed of a heat exchanger such as a finned tube, or may be composed of a pipe material and form a shell-and-tube structure together with the sealed container 10. In addition, the heat exchange unit 52 may also be a structure in contact with the outer surface of the sealed container 10. In this case, the entire heat medium circulation device 50 is arranged outside the sealed container 10.

[0084] The pump 53 is provided in a portion of the heat medium flow path 51 that is located outside the sealed container 10. The form of the pump 53 is not particularly limited, and it may be a non-positive displacement pump or a positive displacement pump. The pump 53 includes, for example, a motor 53M controlled by an inverter, such as an AC motor or a brushless DC motor. In addition, the pump 53 adjusts the amount of liquid introduced by adjusting the rotation speed of the motor 53M, thereby being able to adjust the flow rate of the refrigerant circulating in the heat medium flow path 51. In detail, the rotation speed of the motor 53M is achieved by adjusting the frequency of the AC current supplied to the motor 53M using an inverter not shown.

[0085] In addition, in the present embodiment, the upstream end 51A and the downstream end 51B of the heat medium flow path 51 are connected to the temperature control object T. However, the heat medium circulation device 50 may be configured to include a temperature control unit that connects the upstream end 51A and the downstream end 51B of the heat medium flow path 51, and to perform heat exchange between the temperature control unit and the temperature control object T. In addition, the heat medium circulation device 50 may be configured to discharge the heat medium from the downstream end 50B.

[0086] The gas supply device 60 is connected to the gas receiving port 14 of the sealed container 10, and can supply gas into the sealed container 10. The gas supply device 60 is provided, for example, to suppress a rapid drop in pressure in the sealed container 10. In detail, the gas supply device 60 can adjust the amount of gas supplied into the sealed container 10 according to the temperature in the sealed container 10, the pressure in the sealed container 10, the temperature of the heat medium after being cooled by the refrigerant, or the temperature of the temperature control object T.

[0087] In detail, the gas supply device 60 includes a gas flow path 61, a gas flow control valve 62 provided in the gas flow path 61, and a gas source 63 connected to the upstream end of the gas flow path 61 and supplying gas to the gas flow path 61. The gas flow control valve 62 is electrically connected to the controller 100 and controlled by the controller 100. The gas flow control valve 62 may also be a valve that adjusts the opening of the valve core by an electric motor such as a stepping motor or a servo motor. In this case, the controller 100 is electrically connected to the above-mentioned electric motor. In addition, the gas flow control valve 62 may also be an electromagnetic proportional valve or the like.

[0088] The gas stored in the gas source 63 is nitrogen in this embodiment. However, the gas stored in the gas source 63 may also be an inert gas such as neon or argon. When the supplied gas is supplied into the sealed container 10, it is preferably controlled to the same temperature as the refrigerant in the sealed container 10.

[0089] In addition, the cooling system S1 also has: a refrigerant temperature sensor 71 for detecting the temperature inside the sealed container 10; a pressure sensor 72 for detecting the pressure of the sealed container 10; a liquid level sensor 73 for detecting the liquid level of the liquid refrigerant in the sealed container 10; and a heat medium temperature sensor 74 for detecting the temperature of the heat medium cooled by the refrigerant in the sealed container 10 and flowing out to the outside of the sealed container 10.

[0090] The refrigerant temperature sensor 71 detects the temperature of the liquid refrigerant in the sealed container 10 and determines the detected temperature as the temperature in the sealed container 10. However, the refrigerant temperature sensor 71 may also detect the temperature of the gas phase in the sealed container 10 and determine it as the temperature of the refrigerant in the sealed container 10.

[0091] The pressure sensor 72 detects the pressure of the gas phase part Gf in the sealed container 10, and determines the detected pressure as the pressure in the sealed container 10. The liquid level sensor 73 is an optical sensor such as a laser displacement meter, which irradiates light from the upper wall of the sealed container 10 to the liquid surface of the refrigerant, receives the reflected light, and calculates the height of the liquid surface. However, the liquid level sensor 73 can also be a float type sensor. The heat medium temperature sensor 74 detects the temperature of the heat medium flowing on the downstream side of the heat exchange part 52 in the heat medium flow path 51 and outside the sealed container 10. Each sensor (71~74) is electrically connected to the controller 100, and the detection result of each sensor is sent to the controller 100.

[0092] The controller 100 is electrically connected to the above-mentioned sensors (71-74), and is electrically connected to the gas suction pump 22, the flow control valve 24, the circulation pump 32, the three-way valve 34, and the gas flow regulating valve 62. The controller 100 may also be composed of a computer having a CPU, a ROM, etc. In this case, various processes are performed according to the program stored in the ROM. In addition, the controller 100 may also be composed of other processors, circuits (such as FPGA (Field Programmable Gate Alley)).

[0093] (Functional structure of controller)

[0094] Figure 2 is a block diagram showing the functional structure of the controller 100. Figure 2 As shown, the controller 100 includes a sensor information acquisition unit 101, a circulation pump adjustment unit 102, a bypass amount adjustment unit 103, a rotation speed adjustment unit 104, a valve opening adjustment unit 105, and a gas supply amount adjustment unit 106. In addition, the controller 100 may be composed of, for example, one computer or a plurality of computers. In the case of being composed of a plurality of computers, the plurality of functional units may also be distributed to the plurality of computers.

[0095] The sensor information acquisition unit 101 is a part that acquires the detection results of the refrigerant temperature sensor 71, the pressure sensor 72, the liquid level sensor 73, and the heat medium temperature sensor 74. The sensor information acquisition unit 101 provides one or more of the information related to the acquired detection results to the bypass amount adjustment unit 103, the rotation speed adjustment unit 104, the valve opening adjustment unit 105, and the gas supply amount adjustment unit 106.

[0096] The circulation pump regulator 102 is electrically connected to the circulation pump 32 and is a part that controls the operation of the circulation pump 32. Specifically, the circulation pump regulator 102 is connected to the motor 32M in the circulation pump 32 via the inverter. The circulation pump regulator 102 adjusts the flow rate of the refrigerant flowing in the refrigerant flow path 31 by adjusting the frequency of the AC current supplied from the inverter to the motor 32M.

[0097] The circulating pump regulator 102 inputs and maintains a target flow rate of the refrigerant, for example, through an input device (not shown), and adjusts the rotation speed of the motor 32M of the circulating pump 32 so that the flow rate of the refrigerant matches the target flow rate.

[0098] The bypass amount adjustment unit 103 is electrically connected to the three-way valve 34 and is a part that controls the operation of the three-way valve 34. Specifically, in the bypass amount adjustment unit 103, for example, a target height of the liquid level of the liquid refrigerant in the sealed container 10 is input and maintained through an input device not shown. In addition, the bypass amount adjustment unit 103 controls the three-way valve 34 using the detection result from the liquid level sensor 73 to maintain the liquid level of the liquid refrigerant in the sealed container 10 at the above-mentioned target height as a predetermined height. That is, the three-way valve 34 is controlled based on the difference between the detection result from the liquid level sensor 73, that is, the liquid level and the target height.

[0099] Specifically, in the present embodiment, according to the instruction from the bypass amount adjustment unit 103, when the liquid level of the liquid refrigerant in the sealed container 10 exceeds a predetermined height, the three-way valve 34 reduces the flow rate of the refrigerant flowing into the first port 341 and flowing out from the second port 342, and increases the flow rate of the refrigerant flowing into the first port 341 and flowing out from the third port 343. In addition, when the liquid level of the liquid refrigerant in the sealed container 10 is lower than a predetermined height, the three-way valve 34 increases the flow rate of the refrigerant flowing into the first port 341 and flowing out from the second port 342, and reduces the flow rate of the refrigerant flowing into the first port 341 and flowing out from the third port 343.

[0100] Furthermore, the three-way valve 34 may also cut off the flow of the refrigerant flowing into the first port 341 and flowing out of the second port 342 when the liquid level of the liquid refrigerant in the sealed container 10 exceeds a predetermined height, and allow the flow of the refrigerant flowing into the first port 341 and flowing out of the third port 343. On the other hand, the three-way valve 34 may also allow the flow of the refrigerant flowing into the first port 341 and flowing out of the second port 342 when the liquid level of the liquid refrigerant in the sealed container 10 is lower than a predetermined height, and cut off the flow of the refrigerant flowing into the first port 341 and flowing out of the third port 343.

[0101] The speed regulator 104 is electrically connected to the gas suction pump 22 and is a part that controls the operation of the gas suction pump 22. Specifically, the speed regulator 104 is connected to the motor 22M in the gas suction pump 22 via the inverter. In addition, the speed regulator 104 adjusts the flow rate of the gas flowing in the gas flow path 21 in the decompression device 20 by adjusting the frequency of the alternating current supplied from the inverter to the motor 22M.

[0102] In the speed adjustment unit 104, for example, the target temperature of the heat medium circulating through the heat medium circulation device 50 is input and maintained through an input device not shown, and the speed adjustment unit 104 adjusts the speed of the motor 22M of the gas suction pump 22 so that the temperature detected by the heat medium temperature sensor 74 coincides with the target temperature, thereby reducing the pressure in the sealed container 10. That is, the gas suction pump 22 may be controlled based on the difference between the temperature of the heat medium as the detection result from the heat medium temperature sensor 74 and the target temperature.

[0103] It should be noted that, in the control example described above, the gas suction pump 22 of the pressure reducing device 20 is controlled in such a manner that the temperature of the heat medium is consistent with the target temperature, but instead, the rotational speed of the motor 22M may be adjusted in such a manner that the temperature inside the sealed container 10 (the detection result of the refrigerant temperature sensor 71), the temperature of the temperature control object T (the detection result of a temperature sensor not shown) or the pressure inside the sealed container 10 are consistent with their respective target values.

[0104] The valve opening adjustment unit 105 is electrically connected to the flow control valve 24 and controls the operation of the flow control valve 24. The valve opening adjustment unit 105 adjusts the flow rate of the gas flowing through the gas flow path 21 in the decompression device 20 by adjusting the opening of the flow control valve 24.

[0105] The valve opening adjustment unit 105 can also adjust the opening of the flow control valve 24 according to the temperature in the sealed container 10 (the detection result of the refrigerant temperature sensor 71), the pressure in the sealed container 10 (the detection result of the pressure sensor 72), the temperature of the heat medium after being cooled by the refrigerant (the detection result of the heat medium temperature sensor 74), or the temperature of the temperature control object T (the detection result of the temperature sensor not shown). In this embodiment, such control of the flow control valve 24 can also be performed after controlling the gas suction pump 22 in a manner that makes the temperature of the heat medium consistent with the target temperature and maintaining the operating state of the gas suction pump 22 constant. If the cooling action actually starts, the temperature or pressure of the refrigerant in the sealed container 10 sometimes changes. In such a case, the opening of the flow control valve 24 can also be adjusted according to the temperature in the sealed container 10, the pressure in the sealed container 10, the temperature of the heat medium after being cooled by the refrigerant, or the temperature of the temperature control object T to be consistent with the target temperature or target pressure.

[0106] In addition, the gas suction pump 22 and the flow control valve 24 may also be operated simultaneously. In addition, the operating state of the gas suction pump 22 may be maintained constant and the opening of the flow control valve 24 may be adjusted, or the opening of the flow control valve 24 may be maintained constant and the operating state of the gas suction pump 22 may be controlled.

[0107] The gas supply amount regulator 106 is electrically connected to the gas flow rate regulator 62 and controls the operation of the gas flow rate regulator 62. The gas supply amount regulator 106 regulates the amount of gas supplied into the sealed container 10 by regulating the opening of the gas flow rate regulator 62.

[0108] The gas supply device 60 can also control the gas flow regulating valve 62 by the gas supply quantity regulating unit 106, thereby adjusting the amount of gas supplied to the sealed container 10 according to the temperature inside the sealed container 10 (the detection result of the refrigerant temperature sensor 71), the pressure inside the sealed container 10 (the detection result of the pressure sensor 72), the temperature of the heat medium after being cooled by the refrigerant (the detection result of the heat medium temperature sensor 74) or the temperature of the temperature control object T (the detection result of the temperature sensor not shown).

[0109] (Refrigerant Structure)

[0110] Next, the refrigerant circulating in the cooling system S1 is described. As described above, in the present embodiment, the refrigerant is, for example, a substance that becomes liquid at atmospheric pressure and at a standard ambient temperature (e.g., 25°C), and is a substance that becomes below -5°C when expanded from this state, for example, in an environment of 0.1 atmospheric pressure, and preferably becomes below -30°C when expanded in an environment of 0.01 atmospheric pressure. In addition, the refrigerant is preferably a low environmental load refrigerant with a global warming potential (GWP) of 10 or less.

[0111] Specifically, in this embodiment, HFO-1336mzz-Z, which has a GWP of 2 and is non-flammable, can be preferably used as the refrigerant. In this case, the heat medium circulated through the heat medium circulation device 50 can also be HFO-1336mzz-Z. More specifically, the refrigerant can be OpteonSF33 (TM) manufactured by Chemours-Mitsui Fluoroproducts Co., Ltd.

[0112] Figure 3 This is the pH line diagram of HFO-1336mzz-Z. HFO-1336mzz-Z is decompressed from a state (St1) of about 0.100MPa near atmospheric pressure and about 33°C close to room temperature to 0.0149MPa, thereby cooling to about -10°C (St2). In addition, by decompressing to 0.001MPa, the temperature is lowered to below about -50°C. Then, if heat is absorbed to a certain extent from the state St2 where the temperature is lowered to about -10°C, it evaporates (St3). If it expands from this state St3 to about 0.100Mpa near atmospheric pressure, it is heated to about 50°C (St4) higher than room temperature in the gas phase. Then, by cooling at room temperature from state St4, it is condensed into a gas-liquid mixed phase and cooled to about 33°C.

[0113] Such HFO-1336mzz-Z is cooled by the heat exchanger 40 and transferred to the above-mentioned state St1, and then, it can be transferred to the state St2 by flowing into the sealed container 10 and being decompressed. In addition, HFO-1336mzz-Z can be transferred from the state St2 to the state St3 by exchanging heat with the heat medium, and then, it can be transferred from the state St3 to the state St4 by flowing out of the sealed container 10 to the outside of the decompression device 20. Therefore, HFO-1336mzz-Z can be appropriately used in the cooling system S1.

[0114] There are various other refrigerants that can be used in the cooling system S1, such as water and ethanol.

[0115] (action)

[0116] Hereinafter, an example of the operation of the cooling system S1 will be described.

[0117] First, in the cooling system S1, the target temperature of the heat medium circulating through the heat medium circulation device 50 is input and maintained. Then, after the sealed container 10, the storage tank 23, and the buffer container 33 are filled with a predetermined amount of liquid refrigerant, the circulation pump 32 of the refrigerant circulation device 30 and the pump 53 of the heat medium circulation device 50 are driven. At this time, the three-way valve 34 and the exhaust control valve 29 are controlled in such a way that the liquid level of the liquid refrigerant in the sealed container 10 becomes a predetermined height. Then, after the liquid level of the liquid refrigerant in the sealed container 10 becomes consistent with the predetermined height, the three-way valve 34 cuts off the circulation of the refrigerant flowing into the first port 341 and flowing out from the second port 342, and allows the circulation of the refrigerant flowing into the first port 341 and flowing out from the third port 343. That is, a state is formed in which the liquid refrigerant does not flow from the refrigerant circulation device 30 into the sealed container 10.

[0118] After that, the pressure reducing device 20 is driven, and the pressure in the sealed container 10 is reduced by the pressure reducing device 20 to a pressure lower than the atmospheric pressure. The pressure reducing device 20 adjusts the rotation speed of the motor 22M of the gas suction pump 22 until the temperature detected by the heat medium temperature sensor 74 is consistent with the target temperature. And, after the temperature detected by the heat medium temperature sensor 74 is consistent with the target temperature, at least one of the rotation speed of the motor 22M of the gas suction pump 22, the opening of the flow control valve 24, and the opening of the gas flow regulating valve 62 of the gas supply device 60 is controlled in order to maintain the target temperature. Through the above steps, the start-up operation is completed. In the state where the rotation speed of the motor 22M of the gas suction pump 22 is adjusted so that the temperature detected by the heat medium temperature sensor 74 is consistent with the target temperature, the pressure in the sealed container 10 is reduced by the pressure reducing device 20 to a pressure lower than the atmospheric pressure, and the refrigerant circulation environment in the refrigerant circulation device 30 outside the sealed container 10 and the refrigerant circulation environment of the heat exchanger 40 are set to a pressure greater than the pressure in the sealed container 10, for example, set to atmospheric pressure. However, the refrigerant circulation environment in the refrigerant cycle device 30 and the refrigerant circulation environment in the heat exchanger 40 may not be strictly at atmospheric pressure, and may be at a pressure slightly lower than atmospheric pressure.

[0119] Then, the heat medium flowing through the heat medium circulation device 50 changes to a state of cooling the temperature control object T. The refrigerant flows out of the sealed container 10, is cooled by the cooling unit 25 and the heat exchanger 40, and then flows again into the sealed container 10. Thus, the heat medium is continuously cooled by the refrigerant.

[0120] That is, when using Figure 3When explaining the operation state of the cooling system S1, the refrigerant that has absorbed the heat of the heat medium flows out of the sealed container 10, is cooled by the cooling unit 25 and the heat exchanger 40, and then flows out of the sealed container 10. Figure 3 The state St4 is transferred to the state St1. After that, the refrigerant is depressurized by flowing into the sealed container 10 and transferred to the state St2. Then, the refrigerant exchanges heat with the heat medium in the sealed container 10, thereby transferring from the state St2 to the state St3. After that, the refrigerant flows out of the sealed container 10 to the outside of the decompression device 20, thereby transferring from the state St3 to the state St4. Then, the refrigerant is cooled by the cooling part 25 and the heat exchanger 40, and transferred from the state St4 to the state St1. Thus, the heat medium is continuously cooled by the refrigerant.

[0121] The cooling system S1 of the first embodiment described above comprises: a sealed container 10, which includes a first outflow port 11 and an inflow port 13, and stores liquid refrigerant; a pressure reducing device 20, which is connected to the first outflow port 11, and adjusts the pressure in the sealed container 10 to a pressure lower than the atmospheric pressure by sucking gas from the sealed container 10 through the first outflow port 11; and a refrigerant circulation device 30, which includes a refrigerant flow path 31 connected to the pressure reducing device 20 and the inflow port 13, so that the liquid refrigerant obtained by liquefying the gas sucked from the sealed container 10 by the pressure reducing device 20 flows into the sealed container 10 through the inflow port 13, and the temperature control object T is cooled by the refrigerant in the sealed container 10.

[0122] According to such a cooling system S1, a substance that has not been used in a conventional refrigeration method can be used as a refrigerant for a heat cycle, or the range of substances that can be used as a refrigerant for a heat cycle can be expanded.

[0123] That is, as described above, in the present embodiment, as an example, as a refrigerant, a substance that becomes liquid at atmospheric pressure and at a standard ambient temperature (e.g., 25° C.) and becomes below -5° C. when expanded from this state, for example, in an environment of 0.1 atmospheric pressure can be used. In contrast, if the above-mentioned substance is used in a vapor compression refrigeration cycle that has been popularized so far, for example, the compressor will compress the liquid, so the compressor cannot function properly, and the substance will not evaporate in the evaporator. Therefore, in the vapor compression refrigeration cycle, the above-mentioned refrigerant is not suitable. In contrast, the cooling system S1 does not utilize compression, and can cool the heat medium by reducing the pressure of the above-mentioned refrigerant in the sealed container 10, and can release the heat of the heat medium from the cooling unit 25 and the heat exchanger 40, so that a heat cycle can be realized. Therefore, according to the present embodiment, a substance that has not been used in the previous refrigeration method can be used as a refrigerant for a heat cycle, or the range of substances that can be used as a refrigerant for a heat cycle can be expanded. In addition, in the present embodiment, the decompression device 20 has a cooling unit 25, so that heat is dissipated in the cooling unit 25 and the heat exchanger 40. On the other hand, a configuration may be adopted in which the heat exchanger 40 is not provided and the heat is radiated only by the cooling unit 25 , or a configuration may be adopted in which the heat exchanger 40 is not provided and the heat is radiated only by the cooling unit 25 .

[0124] Furthermore, as described above, the cooling system S1 can use, for example, HFO-1336mzz-Z, which has a GWP of 2 and is non-flammable, as a refrigerant. Thus, in a vapor compression refrigeration cycle, a cooling action with low GWP and ensuring safety, which is not possible in the current situation, can be achieved. Such a cooling system S1 with low GWP, small environmental load, and ensuring safety is unknown, including other cooling methods. Therefore, the realization of such a cooling system S1 has the potential to make a significant contribution to the protection of the global environment. In addition, since a compressor is not used in the cooling system S1, it is also beneficial to suppress the outflow of lubricating oil to the refrigerant side.

[0125] In addition, in this embodiment, there are various designs for operating the cooling system S1 economically and stably.

[0126] For example, the decompression device 20 includes: a gas flow path 21 connected to the first outlet 11; a gas suction pump 22 provided in the gas flow path 21 to suck gas from the sealed container 10 to the gas flow path 21; and a storage tank 23 connected to the downstream end 21B of the gas flow path 21 to store the gas flowing out from the downstream end 21B. Thus, it is easy to gasify the gas in the storage tank 23, and the refrigerant in the gas state is suppressed from returning to the sealed container 10 through the refrigerant circulation device 30.

[0127] In particular, in the present embodiment, the pressure in the storage tank 23 is higher than the pressure in the sealed container 10, and the storage tank 23 liquefies at least a portion of the gas flowing out from the downstream end 21B of the gas flow path 21 into a liquid refrigerant and stores the liquid refrigerant. Thus, the gaseous refrigerant can be effectively prevented from returning to the sealed container 10 through the refrigerant circulation device 30.

[0128] In addition, the refrigerant cycle device 30 further includes a buffer container 33, which is provided in the refrigerant flow path 31 so as to form a part of the refrigerant flow path 31 and stores a liquid refrigerant. Then, the gas stored in the storage tank 23 or the liquid refrigerant obtained by liquefying at least a part of the gas flows into the buffer container 33. In this structure, the gas or liquid refrigerant from the storage tank 23 can flow out of the buffer container 33 after mixing with the liquid refrigerant stored in the buffer container 33. As a result, it is possible to suppress the temperature of the refrigerant flowing on the downstream side of the buffer container 33 from being unexpectedly disturbed.

[0129] In addition, the refrigerant cycle device 30 includes a three-way valve 34, which is provided in a portion of the refrigerant flow path 31 that is downstream of a portion connected to the heat exchanger 40, and includes a first port 341, a second port 342, and a third port 343. The three-way valve 34 constitutes a portion of the refrigerant flow path 31 by a flow path between the first port 341 and the second port 342. In addition, the third port 343 is connected to a portion of the refrigerant flow path 31 that is upstream of a portion connected to the heat exchanger 40 (in this embodiment, the buffer container 33) through a bypass flow path 38.

[0130] Thus, the cooling system S1 can be operated stably, and the accuracy of temperature control can be improved. For example, when the amount of liquid refrigerant stored in the sealed container 10 becomes excessive, the risk of the pressure reducing device 20 sucking the liquid refrigerant increases. In this case, there is a risk that the operation of the pressure reducing device 20 becomes unstable or the pressure reducing device 20 is damaged. For example, in such a case, the three-way valve 34 reduces or cuts off the flow rate of the refrigerant flowing to the sealed container 10 side, thereby avoiding the situation where there is too much liquid refrigerant in the sealed container 10.

[0131] <Second Embodiment>

[0132] Next, refer to Figure 4 A cooling system S2 according to the second embodiment will be described. Note that the same components as those of the first embodiment are denoted by the same reference numerals, and duplicate descriptions are omitted.

[0133] This embodiment is different from the first embodiment in that the exhaust flow path 28 connecting the sealed container 10 and the buffer container 33 and the exhaust control valve 29 on the exhaust flow path 28 are not provided. According to the cooling system S2 of the second embodiment, the same effect as that of the first embodiment can be obtained. Moreover, according to this embodiment, the device structure can be simplified.

[0134] <Third Embodiment>

[0135] Next, refer to Figure 5 A cooling system S3 according to a third embodiment will be described. In addition, the same reference numerals are given to the same components as those of the first and second embodiments, and duplicate descriptions are omitted.

[0136] In the present embodiment, the refrigerant cycle device 30 does not include the circulation pump 32 and the three-way valve 34. In addition, a heat exchanger 40 is disposed inside the buffer container 33. In addition, the heat exchanger 40 may be a structure in contact with the outer wall of the buffer container 33, or may be connected to a portion on the upstream side or downstream side of the buffer container 33 in the refrigerant flow path 31.

[0137] In addition, in the present embodiment, a return amount regulating valve 80 is provided in the refrigerant flow path 31. The return amount regulating valve 80 is a valve for regulating the flow rate of the liquid refrigerant flowing from the storage tank 23 into the sealed container 10. In detail, the return amount regulating valve 80 is controlled by the controller 100, for example, to regulate the flow rate of the liquid refrigerant flowing into the sealed container 10 in such a manner that the liquid level of the liquid refrigerant in the sealed container 10 is maintained at a predetermined height. The return amount regulating valve 80 may be an on-off valve or a proportional valve.

[0138] An example of the operation of the cooling system S3 will be described below.

[0139] First, in the cooling system S3, the target temperature of the heat medium circulating through the heat medium circulation device 50 is input and maintained. And, after the sealed container 10, the storage tank 23 and the buffer container 33 are filled with a prescribed amount of liquid refrigerant, the pump 53 of the heat medium circulation device 50 is driven. At this time, the return amount regulating valve 80 is controlled in such a way that the liquid level of the liquid refrigerant in the sealed container 10 becomes a prescribed height. In the present embodiment, when the return amount regulating valve 80 is opened, the liquid refrigerant naturally flows into the sealed container 10 due to its own weight, but a circulation pump 32 may also be provided. Then, after the liquid level of the liquid refrigerant in the sealed container 10 matches the prescribed height, the return amount regulating valve 80 is closed.

[0140] After that, the pressure reducing device 20 is driven, and the pressure in the sealed container 10 is reduced by the pressure reducing device 20 to a pressure lower than the atmospheric pressure. The pressure reducing device 20 adjusts the rotation speed of the motor 22M of the gas suction pump 22 until the temperature detected by the heat medium temperature sensor 74 is consistent with the target temperature. And, after the temperature detected by the heat medium temperature sensor 74 is consistent with the target temperature, at least one of the rotation speed of the motor 22M of the gas suction pump 22, the opening of the flow control valve 24, and the opening of the gas flow regulating valve 62 of the gas supply device 60 is controlled in order to maintain the target temperature. Through the above steps, the start-up operation is completed. In the state where the rotation speed of the motor 22M of the gas suction pump 22 is adjusted so that the temperature detected by the heat medium temperature sensor 74 is consistent with the target temperature, the pressure in the sealed container 10 is reduced by the pressure reducing device 20 to a pressure lower than the atmospheric pressure, and the refrigerant circulation environment in the refrigerant circulation device 30 outside the sealed container 10 is set to a pressure greater than the pressure in the sealed container 10, for example, set to atmospheric pressure. However, the refrigerant circulation environment in the refrigerant cycle device 30 does not need to be strictly at atmospheric pressure, and may be at a pressure slightly lower than atmospheric pressure.

[0141] Then, the heat medium flowing through the heat medium circulation device 50 changes to a state of cooling the temperature control object T. The refrigerant flows out of the sealed container 10, is cooled by the cooling unit 25 and the heat exchanger 40, and then flows again into the sealed container 10. Thus, the heat medium is continuously cooled by the refrigerant.

[0142] According to the cooling system S3 of the third embodiment, the same effects as those of the first embodiment can be obtained, and the device structure can be simplified.

[0143] <Fourth Embodiment>

[0144] Next, refer to Figure 6 A cooling system S4 according to a fourth embodiment will be described. Note that the same components as those of the first to third embodiments are denoted by the same reference numerals, and duplicate descriptions are omitted.

[0145] This embodiment removes the buffer container 33 from the refrigerant cycle device 30 in the third embodiment and also does not use the heat exchanger 40, thereby achieving further simplification. The cooling system S4 can operate in the same manner as described in the third embodiment. Such an embodiment is useful in simplifying the device.

[0146] As mentioned above, although each embodiment of the present invention has been described, the present invention is not limited to the above-described embodiment, and various further changes can be added to the above-described embodiment.

Claims

1. A cooling system comprising: A container including an outflow port and an inflow port, wherein the container stores a liquid refrigerant; a decompression device connected to the outflow port, which adjusts the pressure in the container to a pressure lower than the atmospheric pressure by sucking gas from the container through the outflow port; and a refrigerant circulation device including a refrigerant flow path connected to the decompression device and the inlet, so that the liquid refrigerant obtained by liquefying the gas sucked from the container by the decompression device flows into the container through the inlet, The temperature control object is cooled by the refrigerant in the container.

2. The cooling system according to claim 1, wherein: The pressure reducing device comprises: a gas flow path connected to the outflow port; a gas suction pump disposed in the gas flow path and sucking the gas from the container into the gas flow path; and a storage tank connected to the gas flow path and storing the gas flowing out of the gas flow path and / or the liquid refrigerant liquefied from the gas, The refrigerant flow path is connected to the storage tank.

3. The cooling system according to claim 2, wherein: The pressure in the storage tank is higher than the pressure in the container, and the storage tank liquefies at least a portion of the gas flowing out of the gas flow path into the liquid refrigerant and stores the liquid refrigerant.

4. The cooling system according to claim 3, wherein: The refrigerant circulation device further includes a circulation pump provided in the refrigerant flow path and introducing the liquid refrigerant from the storage tank into the refrigerant flow path.

5. The cooling system according to claim 3, wherein: The decompression device further includes a cooling unit that cools a portion of the gas flow path on a downstream side of the gas suction pump and / or the storage tank.

6. The cooling system according to claim 3, wherein: The refrigerant cycle device further includes a buffer container, which is provided in the refrigerant flow path so as to form a part of the refrigerant flow path and stores the refrigerant in a liquid state. The liquid refrigerant introduced from the storage tank into the refrigerant flow path flows into the container after passing through the buffer container.

7. The cooling system according to claim 6, wherein: The cooling system further includes a heat exchanger connected to the refrigerant flow path and configured to cool the liquid refrigerant flowing in the refrigerant flow path. The buffer tank is provided at a portion of the refrigerant flow path that is upstream of a portion connected to the heat exchanger.

8. The cooling system according to claim 6, wherein: The storage tank is arranged above the buffer container.

9. The cooling system according to claim 2, wherein: The gas suction pump is configured to suck the gas by rotating a motor. The gas suction pump adjusts the rotation speed of the motor according to the temperature in the container, the pressure in the container, the temperature of the heat medium cooled by the refrigerant, or the temperature of the temperature control object.

10. The cooling system according to claim 2, wherein: A flow control valve is provided in the gas flow path at the upstream side or downstream side of the gas suction pump, and the flow control valve controls the flow rate of the gas flowing in the gas flow path by adjusting the opening degree. The opening degree of the flow control valve is adjusted according to the temperature in the container, the pressure in the container, the temperature of the heat medium cooled by the refrigerant, or the temperature of the temperature control object.

11. The cooling system according to claim 10, wherein: The cooling system further comprises a gas supply device for supplying gas into the container. The gas supply device adjusts the amount of the gas supplied into the container according to the temperature in the container, the pressure in the container, the temperature of the heat medium cooled by the refrigerant, or the temperature of the temperature control object.

12. The cooling system according to claim 1, wherein: The cooling system further includes a heat exchanger connected to the refrigerant flow path and configured to cool the liquid refrigerant flowing in the refrigerant flow path. The refrigerant circulation device includes a three-way valve, which is provided at a portion of the refrigerant flow path that is downstream of a portion connected to the heat exchanger and includes a first port, a second port, and a third port. The three-way valve is capable of adjusting the flow rate of the refrigerant flowing into the first port and flowing out of the second port and the flow rate of the refrigerant flowing into the first port and flowing out of the third port. The three-way valve forms a part of the refrigerant flow path through the flow path between the first port and the second port. The third port is connected to a portion of the refrigerant flow path upstream of a portion connected to the heat exchanger through a bypass flow path.

13. The cooling system according to claim 12, wherein: When the liquid level of the liquid refrigerant in the container exceeds a predetermined height, the three-way valve reduces the flow rate of the refrigerant flowing into the first port and flowing out of the second port, and increases the flow rate of the refrigerant flowing into the first port and flowing out of the third port. When the liquid level of the liquid refrigerant in the container is lower than a specified height, the three-way valve increases the flow rate of the refrigerant flowing into the first port and flowing out of the second port, and reduces the flow rate of the refrigerant flowing into the first port and flowing out of the third port.

14. The cooling system according to claim 12, wherein: When the liquid level of the liquid refrigerant in the container exceeds a predetermined height, the three-way valve blocks the flow of the refrigerant flowing into the first port and flowing out of the second port, and allows the flow of the refrigerant flowing into the first port and flowing out of the third port. When the liquid level of the liquid refrigerant in the container is lower than a specified height, the three-way valve allows the flow of the refrigerant flowing into the first port and flowing out of the second port, and cuts off the flow of the refrigerant flowing into the first port and flowing out of the third port.

15. The cooling system according to claim 1, wherein: The cooling system further includes a heat medium circulation device including a heat medium flow path for circulating the heat medium. The heat medium flow path includes a heat exchange portion, which is arranged in the container and allows the heat medium to exchange heat with the refrigerant. The heat medium passage transports the heat medium from the outside of the container to the heat exchange portion, and transports the heat medium having undergone heat exchange in the heat exchange portion to the outside of the container.

16. 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.

17. The cooling system according to claim 16, wherein: The GWP of the refrigerant is 10 or less.

18. The cooling system according to claim 17, wherein: The refrigerant is HFO-1336mzz-Z.

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