Cooling device

Abstract

This cooling device (100) comprises a tank (1), a pump (2), an evaporator (3), and a condenser (4). In a gas phase portion (1a) of the tank, filler gas (6) is sealed, and a volume change unit (7) that adjusts the evaporation temperature of the refrigerant (101) by changing the volume of the gas phase portion and thereby changing the pressure of the filler gas and the pressure of a refrigerant (101) is provided.

Description

Technical Field

[0001] The present invention relates to a cooling device.

Background Art

[0002] Conventionally, a cooling device including an evaporator and a condenser has been disclosed. Such a cooling device is disclosed, for example, in Terushige Fujii, et al., "Research on Temperature Control by Steam Valve Operation of a Latent Heat Utilization Fluid Loop Type Waste Heat System," National Aerospace Laboratory Contract Report, National Aerospace Laboratory, October 29, 2004, JAXA-CR-04-002 (hereinafter simply referred to as "Non-Patent Document 1").

[0003] In Non-Patent Document 1, a cooling device including a pump, an evaporator, a condenser, and a valve is disclosed. In Non-Patent Document 1, the refrigerant sent out from the pump evaporates by absorbing a heat load in the evaporator and condenses in the condenser. Further, the condensed refrigerant returns to the pump and is sent out again to repeat the cycle. In Non-Patent Document 1, the valve is provided between the evaporator and the condenser, and by changing the opening degree, the pressure of the refrigerant inside the evaporator and the evaporation temperature of the refrigerant are changed. In Non-Patent Document 1, the evaporation temperature of the refrigerant is adjusted by operating the valve opening degree between the evaporator and the condenser, thereby adjusting the temperature of the evaporator surface (i.e., the cooling temperature).

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the cooling device described in Non-Patent Document 1 above, in order to adjust the evaporation temperature of the refrigerant by operating the valve opening degree between the evaporator and the condenser, there is a disadvantage that the pressure increase amount (pressure increase) of the refrigerant by the pump increases due to the pressure loss in the valve. In this case, since the pump becomes larger, there is a problem that the cooling temperature cannot be adjusted while reducing the size of the pump.

[0006] This invention has been made to solve the above problems, and one object of this invention is to provide a cooling device capable of adjusting the cooling temperature while reducing the size of the pump in two-phase cooling using the phase change when the refrigerant changes from a liquid to a gas.

Means for Solving the Problems

[0007] To achieve the above object, a cooling device according to one aspect of this invention includes a tank for storing a liquid refrigerant, a pump for discharging the liquid refrigerant stored in the tank, an evaporator for cooling a cooling target by evaporating the liquid refrigerant discharged from the pump, and a condenser for condensing the gaseous refrigerant evaporated in the evaporator. An enclosed gas is enclosed in the gas phase portion of the tank, and a volume change portion is provided for changing the pressure of the enclosed gas by changing the volume of the gas phase portion, thereby changing the pressure of the refrigerant and adjusting the evaporation temperature of the refrigerant.

Effects of the Invention

[0008] In the cooling device according to the above first aspect, an encapsulating gas is encapsulated in the gas phase portion of the tank. As a result, the pressure of the refrigerant can be increased by the pressure (partial pressure) of the encapsulating gas encapsulated in the gas phase portion of the tank. Therefore, the amount of pressure increase (pressure increase amount) of the refrigerant by the pump can be reduced by the pressure (partial pressure) of the encapsulating gas, and as a result, the pump can be miniaturized. Further, a volume change portion for adjusting the evaporation temperature of the refrigerant by changing the pressure of the encapsulating gas by changing the volume of the gas phase portion is provided in the gas phase portion of the tank. Thereby, the cooling temperature can be adjusted by adjusting the evaporation temperature of the refrigerant by the volume change portion and the encapsulating gas. As a result, in two-phase cooling using the phase change when the refrigerant changes from a liquid to a gas, the cooling temperature can be adjusted while miniaturizing the pump. When using a refrigerant (such as carbon dioxide) with a large rate of increase in saturation pressure with respect to temperature rise, the amount of pressure increase of the refrigerant by the pump tends to be large. Therefore, this configuration is particularly effective when using a refrigerant such as carbon dioxide with a large rate of increase in saturation pressure with respect to temperature rise.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments embodying the present invention will be described with reference to the drawings.

[0011] With reference to FIGS. 1 to 4, the configuration of a cooling device 100 according to an embodiment will be described.

[0012] (Configuration of the Cooling Device) As shown in FIG. 1, the cooling device 100 is a two-phase cooling device that performs two-phase cooling using the phase change when the refrigerant 101 changes from a liquid to a gas. Specifically, the cooling device 100 includes a tank 1, a pump 2, an evaporator 3, and a condenser 4. The refrigerant 101 is not particularly limited, but for example, carbon dioxide, which is a natural refrigerant, can be adopted. Also, the cooling device 100 is not particularly limited, but for example, it can be applied to the cooling of space equipment and manufacturing devices for machine parts, etc.

[0013] The tank 1 is made of metal and is configured to store the liquid refrigerant 101. Also, the tank 1 is connected to the pump 2 via the refrigerant pipe 5a.

[0014] The pump 2 is configured to suck in the liquid refrigerant 101 stored in the tank 1 and discharge the sucked liquid refrigerant 101 toward the evaporator 3. The pump 2 is not particularly limited, but for example, a positive displacement or centrifugal pump can be adopted. Also, the pump 2 is connected to the evaporator 3 via the refrigerant pipe 5b.

[0015] The evaporator 3 is configured to cool the object to be cooled 200 by evaporating the liquid refrigerant 101 discharged from the pump 2. The object to be cooled 200 is a heat-generating body such as an electronic device. The evaporator 3 functions as a heat exchanger that exchanges heat between the object to be cooled 200 and the refrigerant 101. That is, the evaporator 3 is configured to receive heat from the object to be cooled 200 and evaporate the refrigerant 101. Also, the evaporator 3 is connected to the condenser 4 via the refrigerant pipe 5c. Note that in the refrigerant pipe 5c, the refrigerant 101 is in a state of a gas-liquid two-phase flow in which the liquid refrigerant 101 and the gas refrigerant 101 are mixed.

[0016] Further, a preheater 3a is provided upstream of the evaporator 3. The preheater 3a is configured to preheat the liquid refrigerant 101 flowing into the evaporator 3. By preheating the liquid refrigerant 101, the preheater 3a is configured to promote the evaporation of the refrigerant 101 in the evaporator 3.

[0017] Also, a temperature sensor 3b for detecting the temperature of the evaporator 3 or the temperature of the refrigerant 101 in the evaporator 3 is provided in the evaporator 3. The temperature sensor 3b is configured to output the detected temperature of the evaporator 3 or the temperature of the refrigerant 101 in the evaporator 3 to a control unit 10 described later.

[0018] The condenser 4 is configured to condense the gaseous refrigerant 101 evaporated in the evaporator 3. The condenser 4 functions as a heat exchanger that exchanges heat between the brine 4b of the refrigerator 4a and the refrigerant 101. That is, the condenser 4 is configured to transfer heat to the brine 4b and condense the refrigerant 101. Further, the condenser 4 is connected to the tank 1 via a refrigerant pipe 5d.

[0019] The cooling device 100 is configured to cool the object to be cooled 200 by repeating a circulation cycle in which the refrigerant 101 sent out from the tank 1 flows in the order of the pump 2, the evaporator 3, and the condenser 4 and returns to the tank 1 again. Also, the cooling device 100 is configured to adjust the evaporation temperature of the refrigerant 101 by adjusting the pressure of the refrigerant 101, thereby adjusting the temperature of the object to be cooled 200.

[0020] Here, in the present embodiment, as shown in FIGS. 1 and 2, an enclosed gas 6 is enclosed in the gas phase portion 1a of the tank 1, and by changing the volume of the gas phase portion 1a, the pressure of the enclosed gas 6 is changed to change the pressure of the refrigerant 101, and a volume change portion 7 for adjusting the evaporation temperature of the refrigerant 101 is provided. The enclosed gas 6 is an inert gas that does not react with the refrigerant 101 and does not condense due to the volume change of the gas phase portion 1a by the volume change portion 7. The evaporation temperature of the enclosed gas 6 is lower than the evaporation temperature of the refrigerant 101 at the same pressure. In the present embodiment, the enclosed gas 6 is nitrogen. Further, the volume change portion 7 is provided in the ceiling portion 1c of the tank 1 avoiding the liquid phase portion 1b in which the liquid refrigerant 101 is stored. In FIG. 2, for ease of understanding, the enclosed gas 6 present in the gas phase portion 1a is shown by a hatched circle, and the gaseous refrigerant 101 (conveniently referred to as refrigerant 101a) present in the gas phase portion 1a is shown by a white circle.

[0021] Also, in the present embodiment, the volume change portion 7 is configured to change the volume by expanding and contracting with the volume change gas 8, thereby changing the volume of the gas phase portion 1a. Specifically, the volume change portion 7 is deformed to expand and the volume increases when the volume change gas 8 is supplied from the gas source 9 into the volume change portion 7, thereby changing the volume of the gas phase portion 1a so that the volume of the gas phase portion 1a decreases. At the same time, when the volume change gas 8 is discharged from the inside of the volume change portion 7 to the outside, the volume change portion 7 is deformed to contract and the volume decreases, thereby changing the volume of the gas phase portion 1a so that the volume of the gas phase portion 1a increases. The volume change portion 7 is configured to expand and contract within the range of the gas phase portion 1a (a range that does not contact the liquid level of the liquid refrigerant 101). Also, the maximum volume (the volume at the maximum elongation) of the volume change portion 7 is smaller than the volume of the tank 1. Although it depends on the scale of the cooling device 100, for example, a volume change portion 7 with a maximum volume of 4 liters can be provided for a tank 1 with a volume of 6 liters.

[0022] In this embodiment, the gas 8 for volume change is nitrogen. In this case, as the gas source 9, a nitrogen gas cylinder filled with nitrogen gas, a nitrogen gas supply device that extracts and supplies nitrogen gas from air, or the like can be adopted.

[0023] Here, let the volume of the gas phase portion 1a in the state where the volume change portion 7 is contracted be V A and let the pressure (partial pressure) of the enclosed gas 6 in the gas phase portion 1a at that time be P A . Also, let the volume of the gas phase portion 1a in the state where the volume change portion 7 is extended be V B and let the pressure (partial pressure) of the enclosed gas 6 in the gas phase portion 1a at that time be P B . Moreover, since the amount of the enclosed gas 6 in the gas phase portion 1a is constant, according to Boyle's law, P A ×V A =P B ×V B holds. Therefore, when the volume change portion 7 changes from the contracted state to the extended state, and the volume of the gas phase portion 1a decreases from V A to V B , the pressure (partial pressure) of the enclosed gas 6 increases from P A to P B . Note that when the volume change portion 7 changes from the contracted state to the extended state, the refrigerant 101a in the gas phase portion 1a condenses and changes into the liquid refrigerant 101. Therefore, the pressure (partial pressure) of the refrigerant 101a does not change.

[0024] Also, the increase in the pressure (partial pressure) of the enclosed gas 6 from P A to P B means increasing the amount of pressure applied to the liquid refrigerant 101 in the tank 1 by the enclosed gas 6. Therefore, when the pressure (partial pressure) of the enclosed gas 6 increases from P A to P B , the pressure of the refrigerant 101 can be increased, and the evaporation temperature of the refrigerant 101 that changes corresponding to the pressure can be increased. Although detailed description is omitted, when the pressure (partial pressure) of the enclosed gas 6 decreases from P B to P A , the evaporation temperature of the refrigerant 101 can be decreased.

[0025] In addition, in this embodiment, the volume change portion 7 is a bellows made of metal. Specifically, as shown in FIG. 3, the volume change portion 7 is a hollow tubular member having a corrugated (bellows-shaped) tube wall 7a that repeats mountain folds and valley folds. The tube wall 7a is attached to the ceiling portion 1c of the tank 1 so as to be stretchable along the vertical direction. Further, one end portion 7b of the volume change portion 7, which is a fixed end, is attached to the ceiling portion 1c of the tank 1, and the other end portion 7c, which is a movable end, is provided so as to be movable along the vertical direction inside the tank 1. Further, the other end portion 7c is formed in a plate shape and is provided so as to close the other end side of the tube wall 7a. The inside of the volume change portion 7 partitioned by the tube wall 7a and the other end portion 7c and the inside of the tank 1 are separated by the tube wall 7a and the other end portion 7c so that fluid (liquid and gas) does not flow through.

[0026] Further, an opening 1d for supplying the volume change gas 8 from the gas source 9 to the inside of the volume change portion 7 and an opening 1e for exhausting the volume change gas 8 from the inside of the volume change portion 7 to the outside are provided in the ceiling portion 1c of the tank 1. The volume change portion 7 is connected to the gas source 9 via an opening 1d that communicates the inside of the volume change portion 7 with the air supply pipe 9a and the air supply pipe 9a connected to the gas source 9. Further, in the middle of the air supply pipe 9a, a regulator 9aa for adjusting the pressure of the volume change gas 8 supplied from the gas source 9 and an air supply valve 9ab for controlling the supply of the volume change gas 8 from the gas source 9 to the volume change portion 7 are provided. The air supply valve 9ab is configured to open and close under the control of the control unit 10. Further, when the air supply valve 9ab opens and the volume change gas 8 is supplied from the gas source 9 to the inside of the volume change portion 7, the tube wall 7a of the volume change portion 7 deforms so as to extend and the volume of the volume change portion 7 increases. If the pressure of the volume change gas 8 after being adjusted by the regulator 9aa is not sufficient to change the volume of the volume change portion 7, a pressure boosting mechanism such as a compressor may be provided on the downstream side of the regulator 9aa in the air supply pipe 9a.

[0027] Further, the volume change section 7 is connected to the outside (atmosphere) via an opening 1e that communicates the inside of the volume change section 7 with the exhaust pipe 9b and the exhaust pipe 9b connected (opened) to the outside (atmosphere). Also, an exhaust valve 9ba for controlling the exhaust of the volume change gas 8 from the volume change section 7 to the outside (atmosphere) is provided in the middle of the exhaust pipe 9b. The exhaust valve 9ba is configured to open and close under the control of the control section 10. When the exhaust valve 9ba opens, the pipe wall 7a of the volume change section 7 is deformed so as to contract by the internal pressure of the gas phase section 1a of the tank 1, and the volume change gas 8 inside the volume change section 7 is exhausted, reducing the volume of the volume change section 7.

[0028] Also, in the present embodiment, the volume change section 7 is configured to change the volume of the gas phase section 1a by changing the volume with the volume change gas 8 so that the temperature of the evaporator 3 or the temperature of the refrigerant 101 in the evaporator 3 reaches the target temperature, thereby adjusting the evaporation temperature of the refrigerant 101. Specifically, the control section 10 is configured to adjust the opening degrees of the air supply valve 9ab and the exhaust valve 9ba based on the temperature of the evaporator 3 detected by the temperature sensor 3b or the temperature of the refrigerant 101 in the evaporator 3 so that the temperature of the evaporator 3 or the temperature of the refrigerant 101 in the evaporator 3 reaches the target temperature. Thereby, the volume change section 7 changes its volume with the volume change gas 8 so that the temperature of the evaporator 3 or the temperature of the refrigerant 101 in the evaporator 3 reaches the target temperature.

[0029] For example, when the temperature of the evaporator 3 detected by the temperature sensor 3b or the temperature of the refrigerant 101 in the evaporator 3 is lower than the target temperature, the control unit 10 performs control to increase the evaporation temperature of the refrigerant 101 by opening the air supply valve 9ab. As a result, since the evaporation temperature of the refrigerant 101 increases, the temperature of the evaporator 3 or the temperature of the refrigerant 101 in the evaporator 3 can be increased, so that the temperature of the evaporator 3 or the temperature of the refrigerant 101 in the evaporator 3 can be brought closer to the target temperature. Also, for example, when the temperature of the evaporator 3 detected by the temperature sensor 3b or the temperature of the refrigerant 101 in the evaporator 3 is higher than the target temperature, the control unit 10 performs control to decrease the evaporation temperature of the refrigerant 101 by opening the exhaust valve 9ba. As a result, since the evaporation temperature of the refrigerant 101 decreases, the temperature of the evaporator 3 or the temperature of the refrigerant 101 in the evaporator 3 can be decreased, so that the temperature of the evaporator 3 or the temperature of the refrigerant 101 in the evaporator 3 can be brought closer to the target temperature.

[0030] FIG. 4 is a graph showing the change in the saturation vapor pressure with respect to the temperature of the refrigerant 101. In the graph of FIG. 4, the horizontal axis represents the temperature and the vertical axis represents the pressure. Also, in the graph of FIG. 4, P0 represents the saturation pressure of the refrigerant 101 at the temperature T0 cooled by the refrigerator 4a, and P A represents the pressure (partial pressure) of the enclosed gas 6 in the gas phase portion 1a in the state where the volume change portion 7 is contracted (see FIG. 2), and P1 in represents the pressure P A of the enclosed gas 6, and the pressure at the inlet of the pump 2 of the refrigerant 101 pressurized by the enclosed gas 6 (P1 in =P0 + P A ), and P1 out represents the pressure at the outlet of the pump 2 of the refrigerant 101 that has entered the pump 2 at the pressure P1 in , and T1 represents the evaporation temperature of the refrigerant 101 at the pressure P1 out . As shown in FIG. 4, in the cooling device 100, since the refrigerant 101 is pressurized by the enclosed gas 6 at the pressure P A , when the evaporation temperature of the refrigerant 101 is set to T1, the pressure increase amount (P1 out -P1 in ) of the refrigerant 101 by the pump 2 can be reduced.

[0031] Also, in the graph of FIG. 4, P B represents the pressure (partial pressure) of the enclosed gas 6 in the gas phase portion 1a in the state where the volume change portion 7 is extended (see FIG. 2), and P2 in represents the pressure P B of the refrigerant 101 pressurized by the enclosed gas 6 at the inlet of the pump 2 (P2 in =P0 + P B ), and P2 out represents the pressure at the outlet of the pump 2 of the refrigerant 101 that has entered the pump 2 at the pressure P2 in , and T2 represents the evaporation temperature of the refrigerant 101 at the pressure P2 out . As shown in FIG. 4, in the cooling device 100, since the refrigerant 101 is pressurized by the enclosed gas 6 at the pressure P B , when the evaporation temperature of the refrigerant 101 is set to T2, the pressure increase amount (P2 out -P2 in ) of the refrigerant 101 by the pump 2 can be reduced.

[0032] (Effects of the present embodiment) In the present embodiment, the following effects can be obtained.

[0033] In the present embodiment, as described above, the cooling device 100 includes a tank 1 that stores the liquid refrigerant 101, a pump 2 that discharges the liquid refrigerant 101 stored in the tank 1, an evaporator 3 that cools the object to be cooled 200 by evaporating the liquid refrigerant 101 discharged from the pump 2, and a condenser 4 that condenses the gaseous refrigerant 101 evaporated in the evaporator 3. In the gas phase portion 1a of the tank 1, the enclosed gas 6 is enclosed, and a volume change portion 7 is provided that changes the volume of the gas phase portion 1a to change the pressure of the enclosed gas 6 and thereby change the pressure of the refrigerant 101 to adjust the evaporation temperature of the refrigerant 101.

[0034] As described above, the enclosed gas 6 is enclosed in the gas phase portion 1a of the tank 1. As a result, the pressure of the refrigerant 101 can be increased by the pressure (partial pressure) of the enclosed gas enclosed in the gas phase portion 1a of the tank 1. Therefore, the amount of pressure increase (pressure increase amount) of the refrigerant 101 by the pump 2 can be reduced by the amount of the pressure (partial pressure) of the enclosed gas 6. As a result, the pump 2 can be miniaturized. Further, as described above, a volume change portion 7 for adjusting the evaporation temperature of the refrigerant 101 by changing the pressure of the enclosed gas 6 by changing the volume of the gas phase portion 1a is provided in the gas phase portion 1a of the tank 1. As a result, the cooling temperature can be adjusted by adjusting the evaporation temperature of the refrigerant 101 by the volume change portion 7 and the enclosed gas 6. As a result, in the two-phase cooling using the phase change when the refrigerant 101 changes from a liquid to a gas, the cooling temperature can be adjusted while miniaturizing the pump 2. When a refrigerant 101 (such as carbon dioxide) having a large rate of increase in saturation pressure with respect to temperature rise is used, the amount of pressure increase of the refrigerant 101 by the pump 2 tends to be large. Therefore, this configuration is particularly effective when using a refrigerant 101 such as carbon dioxide having a large rate of increase in saturation pressure with respect to temperature rise.

[0035] In addition, in order to adjust the evaporation temperature of the refrigerant 101, it is conceivable to adjust the pressure of the refrigerant 101 by pressurizing the refrigerant 101 with an accumulator. In this case, however, the accumulator needs to pressurize the liquid refrigerant 101. This is because even if the gaseous refrigerant 101 is pressurized by the accumulator, the refrigerant 101 cannot be changed from gas to liquid to adjust the pressure of the refrigerant 101. Further, when pressurizing the liquid refrigerant 101, the size of the accumulator as a pressurizing mechanism tends to increase. On the other hand, as described above, a volume change part 7 is provided in the gas phase part 1a of the tank 1 to change the pressure of the enclosed gas 6 by changing the volume of the gas phase part 1a, thereby changing the pressure of the refrigerant 101 and adjusting the evaporation temperature of the refrigerant 101. Thereby, since the volume change part 7 changes the volume of the gas phase part 1a to change the pressure of the enclosed gas 6 and thereby change the pressure of the refrigerant 101, compared with the case where the liquid refrigerant 101 is directly pressurized by the volume change part 7, the size of the volume change part 7 as a pressurizing mechanism can be reduced.

[0036] In addition, in order to adjust the evaporation temperature of the refrigerant 101, it is also conceivable to adjust the pressure of the enclosed gas 6 by taking in and out the enclosed gas 6 in the tank 1. In this case, however, it is difficult to take in and out the enclosed gas 6 independently of the refrigerant 101. On the other hand, as described above, a volume change part 7 is provided in the gas phase part 1a of the tank 1 to change the pressure of the enclosed gas 6 by changing the volume of the gas phase part 1a, thereby changing the pressure of the refrigerant 101 and adjusting the evaporation temperature of the refrigerant 101. Thereby, since it is not necessary to take in and out the enclosed gas 6 in the tank 1 in order to adjust the evaporation temperature of the refrigerant 101, it is possible to suppress the refrigerant 101 from going out together with the enclosed gas 6, which is different from the case of taking in and out the enclosed gas 6 in the tank 1.

[0037] In addition, in the above-described embodiment, by configuring as follows, the following further effects can be obtained.

[0038] That is, in the present embodiment, as described above, the volume change part 7 is configured to change its volume by expanding and contracting with the volume change gas 8, thereby changing the volume of the gas phase part 1a. As a result, by simply expanding and contracting the volume change part 7 with the volume change gas 8, the volume of the gas phase part 1a can be changed, and the evaporation temperature of the refrigerant 101 can be adjusted with a simple configuration.

[0039] Further, in the present embodiment, as described above, when the volume change gas 8 is supplied from the gas source 9 into the volume change part 7, the volume change part 7 deforms to expand and its volume increases, thereby changing the volume of the gas phase part 1a so that the volume of the gas phase part 1a decreases. Also, when the volume change gas 8 is discharged from the inside of the volume change part 7 to the outside, the volume change part 7 deforms to contract and its volume decreases, thereby changing the volume of the gas phase part 1a so that the volume of the gas phase part 1a increases. As a result, when the volume change gas 8 is supplied from the gas source 9 into the volume change part 7, the pressure of the enclosed gas 6 and the pressure of the refrigerant 101 can be increased, and the evaporation temperature of the refrigerant 101 can be easily increased. Also, when the volume change gas 8 is discharged from the inside of the volume change part 7 to the outside, the pressure of the enclosed gas 6 and the pressure of the refrigerant 101 can be decreased, and the evaporation temperature of the refrigerant 101 can be easily decreased.

[0040] Further, in the present embodiment, as described above, the volume change part 7 is configured to change the volume of the gas phase part 1a by changing the volume with the volume change gas 8 so that the temperature of the evaporator 3 or the temperature of the refrigerant 101 in the evaporator 3 reaches the target temperature, thereby adjusting the evaporation temperature of the refrigerant 101. As a result, the evaporation temperature of the refrigerant 101 can be adjusted by the volume change part 7 according to the target temperature, so that the temperature of the evaporator 3 or the temperature of the refrigerant 101 in the evaporator 3 can be easily and surely adjusted to the target temperature.

[0041] Also, in the present embodiment, as described above, the volume change portion 7 is a bellows made of metal. As a result, compared with the case where the volume change portion 7 is a rubber balloon or the like, it can easily withstand high pressure, so that the pressure can be easily adjusted even with the high-pressure refrigerant 101. Further, since the volume change portion 7 is a bellows made of metal, unlike the case where the volume change portion 7 is constituted by a piston and a cylinder, a seal structure provided between the piston and the cylinder is not required, and thus the volume change portion 7 can be configured with a simple structure.

[0042] Also, in the present embodiment, as described above, the enclosed gas 6 is an inert gas that does not react with the refrigerant 101 and does not condense due to the volume change of the gas phase portion 1a by the volume change portion 7. As a result, the enclosed gas 6 can be stably arranged in the gas phase portion 1a of the tank 1, and the amount of the enclosed gas 6 does not change (does not condense) due to the volume change of the gas phase portion 1a by the volume change portion 7. Therefore, even if the volume of the gas phase portion 1a changes due to the volume change portion 7, the action of the pressure of the enclosed gas 6 can be surely exhibited.

[0043] Also, in the present embodiment, as described above, the enclosed gas 6 contains nitrogen. As a result, it is possible to easily realize the enclosed gas 6 that does not react with the refrigerant 101 and does not condense due to the volume change of the gas phase portion 1a by the volume change portion 7.

[0044] Also, in the present embodiment, as described above, the volume change portion 7 is provided on the ceiling portion 1c of the tank 1. As a result, the volume change portion 7 can be easily arranged at a position avoiding the liquid phase portion 1b of the tank 1, so that the volume of the gas phase portion 1a of the tank 1 can be easily changed by the volume change portion 7.

[0045] [Modification Example] It should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is shown not by the description of the above-described embodiments but by the claims, and further includes all changes (modification examples) within the meaning and scope equivalent to the claims.

[0046] For example, in the above embodiment, an example where the refrigerant is carbon dioxide was shown, but the present invention is not limited thereto. In the present invention, the refrigerant may be a chlorofluorocarbon refrigerant, or may be a natural refrigerant such as ammonia other than carbon dioxide.

[0047] Also, in the above embodiment, an example where the enclosed gas is nitrogen was shown, but the present invention is not limited thereto. In the present invention, the enclosed gas may be argon.

[0048] Also, in the above embodiment, an example where the gas for volume change is nitrogen was shown, but the present invention is not limited thereto. In the present invention, the gas for volume change may be a gas other than nitrogen.

[0049] Also, in the above embodiment, an example where the volume change part is a bellows made of metal was shown, but the present invention is not limited thereto. In the present invention, the volume change part may be a bellows other than made of metal. Further, the volume change part may be a rubber balloon that can expand and contract by the gas for volume change, and a cylinder structure in which a piston moves in the cylinder by the gas for volume change. However, from the viewpoint of pressure resistance, the volume change part is preferably a bellows made of metal rather than a rubber balloon. Also, from the viewpoint of simplifying the structure, the volume change part is preferably a bellows made of metal rather than a cylinder structure that requires a sealing structure between the piston and the cylinder.

[0050] Also, in the above embodiment, an example where the volume change part is provided in the ceiling part of the tank was shown, but the present invention is not limited thereto. In the present invention, the volume change part may be provided on the side surface part of the tank.

[0051] Also, in the above embodiment, an example where an air supply valve for supplying the gas for volume change to the volume change part and an exhaust valve for exhausting the gas for volume change from the volume change part are respectively provided was shown, but the present invention is not limited thereto. In the present invention, a supply and exhaust valve for supplying the gas for volume change to the volume change part and exhausting the gas for volume change from the volume change part may be provided.

[0052] [Aspect] Those skilled in the art will understand that the above-exemplified embodiments are specific examples of the following aspects.

[0053] (Item 1) A tank for storing a liquid refrigerant, A pump for discharging the liquid refrigerant stored in the tank, An evaporator for cooling a cooling target by evaporating the liquid refrigerant discharged from the pump, A condenser for condensing the gaseous refrigerant evaporated in the evaporator, and An enclosed gas is enclosed in the gas phase portion of the tank, and a volume change portion is provided for changing the pressure of the enclosed gas by changing the volume of the gas phase portion, thereby changing the pressure of the refrigerant and adjusting the evaporation temperature of the refrigerant. Cooling device.

[0054] (Item 2) The cooling device according to Item 1, wherein the volume change portion is configured to change its volume by expanding and contracting with a volume change gas, thereby changing the volume of the gas phase portion.

[0055] (Item 3) The volume change portion is configured such that when the volume change gas is supplied from a gas source into the volume change portion, it deforms to expand and its volume increases, thereby reducing the volume of the gas phase portion, and the volume change gas is discharged from the inside of the volume change portion to the outside. The cooling device according to Item 2, wherein the volume of the gas phase portion is changed so that the volume of the gas phase portion increases by deforming to contract and the volume decreases.

[0056] (Item 4) The volume change part is configured to adjust the evaporation temperature of the refrigerant by changing the volume of the gas phase part by changing the volume of the volume change gas so that the temperature of the evaporator or the temperature of the refrigerant in the evaporator reaches the target temperature. The cooling device according to item 2 or 3.

[0057] (Item 5) The volume change part is a bellows made of metal. The cooling device according to any one of items 1 to 4.

[0058] (Item 6) The enclosed gas is an inert gas that does not react with the refrigerant and does not condense due to the volume change of the gas phase part by the volume change part. The cooling device according to any one of items 1 to 5.

[0059] (Item 7) The enclosed gas contains at least one of nitrogen and argon. The cooling device according to item 6.

[0060] (Item 8) The volume change part is provided on the ceiling part of the tank. The cooling device according to any one of items 1 to 7.

Explanation of Signs

[0061] 1 Tank 1a Gas phase part 1b Ceiling part 2 Pump 3 Evaporator 4 Condenser 6 Enclosed gas 7 Volume change part 8 Volume change gas 9 Gas source 100 Cooling device 101 Refrigerant 200 Object to be cooled

Claims

1. A tank for storing a liquid refrigerant; A pump for discharging the liquid refrigerant stored in the tank; An evaporator for cooling a cooling target by evaporating the liquid refrigerant discharged from the pump; A condenser for condensing the gaseous refrigerant evaporated in the evaporator, comprising: A volume change part is provided in the gas phase part of the tank, in which an enclosed gas is enclosed, and by changing the volume of the gas phase part, the pressure of the enclosed gas is changed to change the pressure of the refrigerant to adjust the evaporation temperature of the refrigerant. Cooling device.

2. The volume change part is configured to change its volume by expanding and contracting with a volume change gas, thereby changing the volume of the gas phase part. The cooling device according to claim 1.

3. The volume change part is deformed to expand by supplying the volume change gas from a gas source into the volume change part, so that the volume increases, thereby reducing the volume of the gas phase part, and the volume change gas is discharged from the inside of the volume change part to the outside. The cooling device according to claim 2, wherein the volume of the gas phase part is changed so that the volume of the gas phase part increases by deforming and shrinking so that the volume decreases.

4. The volume change part is configured to change the volume of the gas phase part by changing the volume with the volume change gas so that the temperature of the evaporator or the temperature of the refrigerant in the evaporator becomes a target temperature, thereby adjusting the evaporation temperature of the refrigerant. The cooling device according to claim 2.

5. The volume change part is a bellows made of metal. The cooling device according to claim 1.

6. The enclosed gas is an inert gas that does not react with the refrigerant and does not condense due to the volume change of the gas phase part by the volume change part. The cooling device according to claim 1.

7. The enclosed gas contains at least one of nitrogen and argon. The cooling device according to claim 6.

8. The volume change part is provided on the ceiling part of the tank. The cooling device according to claim 1.

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