Circulation device for two-phase cooling system and refrigerant circulation method in circulation device for two-phase cooling system

Abstract

A circulation device (100) for a two-phase cooling system comprises: an inlet-side connection portion (41) and an outlet-side connection portion (42); and a bypass flow path (75) that branches downstream of a pump (10) and upstream of the inlet-side connection portion and allows a refrigerant to flow to a condenser (20) without passing through the inlet-side connection portion or the outlet-side connection portion, wherein in a state in which an evaporator (80) is not connected to the inlet-side connection portion and the outlet-side connection portion, the refrigerant is circulated through the bypass flow path without passing through the inlet-side connection portion and the outlet-side connection portion.

Description

Circulation device for two-phase cooling system and refrigerant circulation method in the circulation device for two-phase cooling system

[0001] The present invention relates to a circulation device for a two-phase cooling system and a refrigerant circulation method in the circulation device for a two-phase cooling system, and more particularly to a circulation device for a two-phase cooling system that constitutes a two-phase cooling system that circulates a refrigerant by connecting a detachable evaporator, and a refrigerant circulation method in the circulation device for a two-phase cooling system.

[0002] A two-phase cooling system has been known in the art, in which a refrigerant is circulated by connecting a removable evaporator to a connecting part. Such a circulation device for a two-phase cooling system is disclosed, for example, in Japanese Patent Application Laid-Open No. 2003-179375.

[0003] Japanese Patent Application Publication No. 2003-179375 discloses a cooling device (two-phase cooling system) including multiple cooling modules that can be selectively attached to an electronic equipment cabinet. Each cooling module is composed of an evaporative cold plate having an evaporation channel, a condenser having a condensation channel, a vapor line, and a liquid line. A working fluid flows through the cooling module sequentially through the evaporation channel, the vapor line, the condensation channel, and the liquid line, thereby forming a pressure-fed two-phase cooling cycle. Japanese Patent Application Publication No. 2003-179375 discloses that the connection between the evaporative cold plate inlet and the liquid line, and the connection between the evaporative cold plate outlet and the vapor line, are advantageously connected by detachable connecting means. That is, Japanese Patent Application Publication No. 2003-179375 discloses a cooling device in which the evaporative cold plate (evaporator) is detachable from a structure including the condenser, the vapor line, and the liquid line.

[0004] Japanese Patent Application Laid-Open No. 2003-179375

[0005] In the cooling device disclosed in JP 2003-179375 A, the working fluid circulates through the evaporative cold plate, the vapor line, the condenser, and the liquid line. Therefore, if the evaporative cold plate is removed from the structure including the condenser, the vapor line, and the liquid line, the working fluid cannot be circulated. In this case, the working fluid does not flow into the condenser. If the working fluid is circulated at a temperature much lower than the ambient temperature, the temperature of the working fluid will rise due to heat input from the temperature outside the cooling device. Therefore, immediately after the evaporative cold plate is removed and then reinstalled, the working fluid circulates at an elevated temperature, preventing the cooled working fluid from flowing into the evaporative cold plate. Therefore, the evaporative cold plate cannot immediately cool the cooling target immediately after reinstalling the evaporative cold plate. Therefore, it is desirable that even after an evaporative cold plate (evaporator) is removed and then reconnected, a cooled working fluid (refrigerant) can be flowed into the evaporative cold plate (evaporator), and that the object to be cooled can be immediately cooled by the evaporative cold plate (evaporator).

[0006] The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to provide a circulation device for a two-phase cooling system and a refrigerant circulation method in a circulation device for a two-phase cooling system, which is capable of flowing cooled refrigerant at a low temperature into the evaporator even immediately after the detachable evaporator is removed and then reconnected, and which is capable of immediately cooling the object to be cooled by the evaporator.

[0007] A circulation device for a two-phase cooling system in a first aspect of the present invention constitutes a two-phase cooling system that circulates a refrigerant by connecting a detachable evaporator, and includes a pump that pumps the refrigerant, an inlet-side connector that is provided downstream of the pump and connected to the refrigerant inlet of the evaporator, and an outlet-side connector that is connected to the refrigerant outlet, a condenser that is provided downstream of the outlet-side connector and cools the refrigerant, and a bypass flow path that branches downstream of the pump and upstream of the inlet-side connector and allows the refrigerant to circulate to the condenser without passing through the inlet-side connector and the outlet-side connector, and when at least the evaporator is not connected to the inlet-side connector and the outlet-side connector, the refrigerant circulates via the bypass flow path without passing through the inlet-side connector and the outlet-side connector.

[0008] In a second aspect of the present invention, a refrigerant circulation method in a circulation device for a two-phase cooling system is a method for circulating a refrigerant in a circulation device for a two-phase cooling system that constitutes a two-phase cooling system in which a refrigerant is circulated by connecting a detachable evaporator, and includes the steps of: circulating the refrigerant through a bypass flow path that circulates the refrigerant without passing through the inlet side connection and the outlet side connection when at least the evaporator is not connected to an inlet side connection connected to a refrigerant inlet of the evaporator and an outlet side connection connected to a refrigerant outlet; and cooling the refrigerant that has flowed through the bypass flow path and flowed into the condenser.

[0009] In a first aspect of the present invention, the circulation device for a two-phase cooling system includes a bypass flow path that branches downstream of the pump and upstream of the inlet connection and allows refrigerant to flow to the condenser without passing through the inlet connection and the outlet connection. When at least the evaporator is not connected to the inlet connection and the outlet connection, the refrigerant circulates through the bypass flow path without passing through the inlet connection and the outlet connection. This allows refrigerant to circulate through the bypass flow path even when the removable evaporator is not connected to the inlet connection and the outlet connection, allowing the condenser to continuously cool the refrigerant. Therefore, even when the removable evaporator is removed from the inlet connection and the outlet connection and then immediately reconnected, cooled refrigerant at a low temperature can flow into the evaporator, and the evaporator can immediately cool the object to be cooled.

[0010] A second aspect of the present invention provides a refrigerant circulation method for a two-phase cooling system, comprising the steps of: circulating a refrigerant through a bypass flow path that bypasses the inlet and outlet connections when at least the evaporator is not connected to the inlet connection connected to the refrigerant inlet and the outlet connection connected to the refrigerant outlet of the evaporator; and cooling the refrigerant that flows through the bypass flow path and enters the condenser. As in the first aspect, this allows refrigerant to circulate through the bypass flow path even when the removable evaporator is not connected to the inlet and outlet connections, thereby allowing the condenser to continuously cool the refrigerant. Therefore, even when the removable evaporator is removed from the inlet and outlet connections and then reconnected, cooled refrigerant can be introduced into the evaporator, allowing the evaporator to immediately cool the object to be cooled.

[0011] FIG. 1 is a schematic diagram showing the configuration of a circulation device for a two-phase cooling system with an evaporator connected according to the first embodiment. FIG. 2 is a schematic diagram showing the configuration of a circulation device for a two-phase cooling system with an evaporator not connected according to the first embodiment. FIG. 3 is a schematic diagram showing the configuration of a circulation device for a two-phase cooling system with an evaporator not connected according to the first embodiment. FIG. 4 is a schematic diagram showing the configuration of a circulation device for a two-phase cooling system with an evaporator not connected according to the first embodiment. FIG. 5 is a schematic diagram showing the configuration of a circulation device for a two-phase cooling system with an evaporator not connected according to the first embodiment. FIG. 6 is a schematic diagram showing the configuration of a circulation device for a two-phase cooling system with an evaporator not connected according to the first embodiment. FIG. 7 is a schematic diagram showing the configuration of a circulation device for a two-phase cooling system with an evaporator not connected according to the second embodiment. FIG. 8 is a block diagram showing the control configuration of a circulation device for a two-phase cooling system with an evaporator not connected according to the second embodiment.

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.

[0013] First Embodiment (Overall Configuration of a Circulation Device for a Two-Phase Cooling System) The overall configuration of a circulation device 100 for a two-phase cooling system according to a first embodiment will be described with reference to FIG. 1 . FIG. 1 illustrates the circulation device 100 for a two-phase cooling system with a removable evaporator 80 connected thereto. The circulation device 100 for a two-phase cooling system constitutes a two-phase cooling system 200 that circulates a refrigerant by connecting the removable evaporator 80. The state in which the removable evaporator 80 is connected refers to, for example, a normal operating state in which the evaporator 80 is attached to the circulation device 100 for a two-phase cooling system and cools a heat source 81 (a cooling target). The circulation device 100 for a two-phase cooling system according to the first embodiment is a portable circulation device. Here, the term "detachable" means that the evaporator 80 directly attached to the circulation device 100 for a two-phase cooling system can be removed from the circulation device 100 for a two-phase cooling system, or the same evaporator 80 or another evaporator can be directly attached to the removed evaporator 80. Two-phase cooling is cooling using a gas-liquid mixture fluid, utilizing the heat of vaporization that occurs when a liquid changes into a gas.

[0014] In the drawing, liquid refrigerant 1 is represented by hatching from the upper right to the lower left, and gas-liquid mixture refrigerant 2 is represented by hatching from the upper left to the lower right. The refrigerants move in the directions indicated by the arrows in the circulation device 100 for a two-phase refrigeration system.

[0015] As shown in FIG. 1 , the circulation device 100 for a two-phase cooling system includes a pump 10, a condenser 20, a reservoir 30, an inlet-side connection 41, an outlet-side connection 42, an inlet-side opening / closing valve 51, an outlet-side opening / closing valve 52, a flow rate regulator 60, and a refrigerant flow path 70. The refrigerant flow path 70 includes a first refrigerant flow path 71, a second refrigerant flow path 72, a third refrigerant flow path 73, a fourth refrigerant flow path 74, and a bypass flow path 75. A removable evaporator 80 is also connected to the circulation device 100. The "inlet side" of the inlet-side connection 41 refers to the inlet side of the evaporator 80, and the "outlet side" of the outlet-side connection 42 refers to the outlet side of the evaporator 80. The "inlet side" of the inlet-side opening / closing valve 51 refers to the inlet side of the evaporator 80, and the "outlet side" of the outlet-side opening / closing valve 52 refers to the outlet side of the evaporator 80.

[0016] The first refrigerant flow path 71 has one end connected to the outlet of the pump 10 and the other end connected to the inlet-side connector 41. A branch section 76 is formed between one end and the other end of the first refrigerant flow path 71. The second refrigerant flow path 72 has one end connected to the outlet-side connector 42 and the other end connected to the inlet of the condenser 20. A junction section 77 is formed between one end and the other end of the second refrigerant flow path 72. The third refrigerant flow path 73 has one end connected to the outlet of the condenser 20 and the other end connected to the inlet of the storage section 30. The fourth refrigerant flow path 74 has one end connected to the outlet of the storage section 30 and the other end connected to the inlet of the pump 10.

[0017] The bypass flow path 75 branches from the first refrigerant flow path 71 to the second refrigerant flow path downstream of the pump 10 and upstream of the inlet connector 41 in the first refrigerant flow path 71, and is configured to allow the refrigerant to flow to the condenser 20 without passing through the inlet connector 41 and the outlet connector 42. The bypass flow path 75 branched from the first refrigerant flow path 71 is connected to the second refrigerant flow path 72 downstream of the outlet connector 42 and upstream of the condenser 20. In the first embodiment, one end of the bypass flow path 75 is connected to a branching portion 76 formed in the first refrigerant flow path 71, and the other end is connected to a junction portion 77 formed in the second refrigerant flow path 72.

[0018] The coolant flow passage 70 is made of a metal material, such as stainless steel, aluminum, or copper, and is shaped like a pipe.

[0019] The pump 10 is configured to pump a liquid-phase refrigerant 1. The pump 10 is operated at a predetermined output. The pump 10 is configured to pump the refrigerant to the evaporator 80 via the first refrigerant flow path 71. The pump 10 is configured to pump the refrigerant to the condenser 20 via the first refrigerant flow path 71, the bypass flow path 75, and the second refrigerant flow path 72. The refrigerant flows into the pump 10 from the reservoir 30 via the fourth refrigerant flow path 74. The pump 10 is provided downstream of the reservoir 30 in the fourth refrigerant flow path 74 and upstream of the evaporator 80 in the first refrigerant flow path 71. Here, "upstream of the pump 10" refers to a portion upstream of the pump 10 and does not include the pump 10. Furthermore, "downstream of the pump 10" refers to a portion downstream of the pump 10 and does not include the pump 10. The same applies to the upstream and downstream sides of the condenser 20, the upstream and downstream sides of the storage section 30, and the upstream and downstream sides of the evaporator 80.

[0020] The pump 10 takes in the liquid-phase refrigerant 1 from the inlet of the pump 10 and discharges the liquid-phase refrigerant 1 from the outlet of the pump 10. The pump 10 is a centrifugal pump. However, the pump 10 is not limited to a centrifugal pump. The pump 10 may be a mixed-flow pump, an axial-flow pump, or another known pump. The pump 10 may also be a positive displacement pump.

[0021] When the evaporator 80 is connected to the condenser 20, the condenser 20 is configured to condense the gas-phase refrigerant in the gas-liquid mixed refrigerant 2 flowing out from the evaporator 80 to generate liquid-phase refrigerant 1. In the first embodiment, the condenser 20 is configured to cool and condense the refrigerant by exchanging heat with a cooling liquid 23 flowing in from the outside. The condenser 20 condenses the refrigerant by, for example, causing the cooling liquid 23 flowing inside the condenser 20 from an external chiller (not shown) to absorb heat from the refrigerant. The condenser 20 includes a flow path 21 through which the refrigerant flows and a cooling liquid flow path 22 through which the cooling liquid 23 flows. The condenser 20 receives the gas-liquid mixed refrigerant 2 from an inlet of the condenser 20 and discharges the liquid-phase refrigerant 1 from an outlet of the condenser 20.

[0022] The condenser 20 is provided downstream of the outlet-side connecting portion 42 in the second refrigerant flow path 72. The refrigerant flows into the condenser 20 via the second refrigerant flow path 72. The refrigerant condensed by the condenser 20 flows into the storage portion 30 via the third refrigerant flow path 73. A coolant having a lower temperature than the liquid-phase refrigerant 1 is used as the coolant 23. In the first embodiment, carbon dioxide is used as the refrigerant, and a liquid containing hydrofluoroether as a main component is used as the coolant 23. The type of coolant 23 is selected depending on the type of refrigerant. There are no particular limitations on the coolant 23, as long as it is a known coolant.

[0023] The storage unit 30 is configured to store the liquid-phase refrigerant 1. Furthermore, when there is gas-liquid mixed refrigerant 2 that has not been completely condensed in the condenser 20, the storage unit 30 is configured to separate and store the gas bubbles (gas-phase refrigerant) contained in the gas-liquid mixed refrigerant 2 at an upper portion. The storage unit 30 is provided downstream of the condenser 20 in the third refrigerant flow path 73. The storage unit 30 allows the liquid-phase refrigerant 1 to flow in from an inlet of the storage unit 30 and allows the liquid-phase refrigerant 1 to flow out from an outlet of the storage unit 30. Furthermore, the storage unit 30 is configured to send the liquid-phase refrigerant 1 to the pump 10 via the fourth refrigerant flow path 74.

[0024] The inlet-side connector 41 is configured to connect the first refrigerant flow path 71 and a refrigerant inlet of the evaporator 80. The inlet-side connector 41 connects the other end of the first refrigerant flow path 71 and a refrigerant inlet provided in the evaporator 80. The inlet-side connector 41 is, for example, a coupling member that is detachable from an inlet-side coupling member 84 formed at the refrigerant inlet of the evaporator 80. The inlet-side connector 41 may be, for example, a known coupling such as a threaded coupling, a flange coupling, a quick coupling, or a bite coupling. The inlet-side connector 41 is provided downstream of the pump 10.

[0025] The outlet-side connector 42 is configured to connect a refrigerant outlet of the evaporator 80 to the second refrigerant flow path 72. The outlet-side connector 42 connects a refrigerant outlet provided in the evaporator 80 to one end of the second refrigerant flow path 72. The outlet-side connector 42 is, for example, a coupling member that is detachable from an outlet-side coupling member 85 formed at the refrigerant outlet of the evaporator 80. The outlet-side connector 42 may be, for example, a known coupling such as a threaded coupling, a flange coupling, a quick coupling, or a bite coupling. The outlet-side connector 42 is provided downstream of the pump 10 and the evaporator 80 and upstream of the condenser 20.

[0026] The inlet-side on-off valve 51 is provided between the branching portion 76 provided in the first refrigerant flow path 71 and the inlet-side connecting portion 41. That is, the inlet-side on-off valve 51 is provided in the first refrigerant flow path between the branching portion where the bypass flow path 75 branches off from the first refrigerant flow path 71 downstream of the pump 10 and the inlet-side connecting portion 41. The inlet-side on-off valve 51 is configured to be able to open and close the flow path. The inlet-side on-off valve 51 is, for example, an on-off valve that can switch the flow path between a fully open state and a fully closed state. The inlet-side on-off valve 51 may be provided integrally with the inlet-side connecting portion 41. Alternatively, the inlet-side on-off valve 51 may be provided in the branching portion 76.

[0027] The outlet-side on-off valve 52 is provided between the outlet-side connecting portion 42 and a junction 77 provided in the second refrigerant flow path 72. That is, the outlet-side on-off valve 52 is provided in the second refrigerant flow path between the outlet-side connecting portion 42 and a connection portion downstream of the outlet-side connecting portion 42 to which the bypass flow path 75 is connected. The outlet-side on-off valve 52 is configured to be able to open and close the flow path. The outlet-side on-off valve 52 is, for example, an on-off valve that can switch the flow path between a fully open state and a fully closed state. The outlet-side on-off valve 52 may be provided integrally with the outlet-side connecting portion 42. Alternatively, the outlet-side on-off valve 52 may be provided at the junction 77.

[0028] The flow rate adjusting unit 60 is provided in the bypass flow path 75. The flow rate adjusting unit 60 is configured to increase the pressure loss of the bypass flow path 75 by reducing the flow path cross-sectional area of ​​a portion of the bypass flow path 75. In the first embodiment, the flow rate adjusting unit 60 is an orifice 61. The hole diameter of the orifice 61 is set in advance to adjust the distribution of the refrigerant flow rate flowing into the evaporator 80 and the refrigerant flow rate flowing into the bypass flow path 75 when the evaporator 80 is connected. In the first embodiment, the hole diameter of the orifice 61 is set so that the refrigerant flow rate flowing into the evaporator 80 is greater than the refrigerant flow rate flowing into the bypass flow path 75.

[0029] As shown in FIG. 1 , in the circulation device 100 for a two-phase cooling system, an evaporator 80 is connected to an inlet-side connection 41 and an outlet-side connection 42. The evaporator 80 cools a heat source 81 by utilizing the heat of vaporization generated when a portion of the liquid-phase refrigerant 1 delivered through the inlet-side connection 41 evaporates and transforms into a gas-liquid mixture of refrigerant 2. The evaporator 80 includes a cold plate 82 and a refrigerant flow path 83 disposed within the cold plate 82. The inlet-side connection 41 is connected to a refrigerant inlet of the refrigerant flow path 83, and the outlet-side connection 42 is connected to a refrigerant outlet of the refrigerant flow path 83. A heat source 81 is disposed on one surface of the cold plate 82. The evaporator 80 and the heat source 81 are integrally formed. Note that the refrigerant flow path 83 shown in FIG. 1 is a schematic diagram. The refrigerant flow path 83 may have a structure that bends multiple times within the evaporator 80 to efficiently exchange heat. The refrigerant flow path 83 may be formed so that it splits into multiple paths at the inlet, passes through the inside of the evaporator 80, and merges into one path at the outlet. The structure of the evaporator 80 is not particularly limited.

[0030] In the first embodiment, the refrigerant is carbon dioxide. However, the type of refrigerant is not limited to this. The refrigerant may be, for example, chlorofluorocarbon or ammonia.

[0031] 2 shows the circulation device 100 for a two-phase cooling system in a state where the removable evaporator 80 is not connected. The state where the removable evaporator 80 is not connected refers to a state where the evaporator 80 is removed from the circulation device 100 for a two-phase cooling system, for example, due to maintenance of the heat source 81 or the evaporator 80. In the circulation device 100 for a two-phase cooling system in a state where the evaporator 80 is not connected, the inlet side opening / closing valve 51 and the outlet side opening / closing valve 52 are in a closed state.

[0032] The condenser 20 is configured to cool the liquid-phase refrigerant 1 sent from the pump 10 via the bypass flow path 75 when the evaporator 80 is not connected. When the evaporator 80 is not connected, the condenser 20 allows the liquid-phase refrigerant 1 to flow in from the inlet of the condenser 20 and allows the cooled liquid-phase refrigerant 1 to flow out from the outlet of the condenser 20. Note that other configurations of the circulation device 100 for a two-phase refrigeration system when the evaporator 80 is not connected are the same as the configuration of the circulation device 100 for a two-phase refrigeration system when the evaporator 80 is connected, as described with reference to FIG. 1, and therefore description thereof will be omitted.

[0033] (Refrigerant Circulation) Referring to FIG. 1, the circulation of the refrigerant within the circulation device 100 for a two-phase cooling system in a state where the evaporator 80 is connected to the inlet side connection part 41 and the outlet side connection part 42 will be described.

[0034] Liquid-phase refrigerant 1 is pumped from pump 10. The refrigerant flows through first refrigerant flow path 71. At branch point 76 of first refrigerant flow path 71, a portion of the refrigerant flows through fully open inlet-side opening / closing valve 51 and inlet-side connecting portion 41 and enters evaporator 80. The remainder of the refrigerant flows into bypass flow path 75, as described below. The liquid-phase refrigerant 1 that flows into evaporator 80 is partially evaporated and converted into gas-liquid mixed refrigerant 2. The gas-liquid mixed refrigerant 2 flows from evaporator 80 through outlet-side connecting portion 42 into second refrigerant flow path 72. The gas-liquid mixed refrigerant 2 that flows into second refrigerant flow path 72 flows through fully open outlet-side opening / closing valve 52 and junction 77. At junction 77, the gas-liquid mixed refrigerant 2 merges with the liquid-phase refrigerant 1 that flows from bypass flow path 75. The joined gas-liquid mixed refrigerant 2 and the liquid-phase refrigerant 1 flowing in from the bypass flow path 75 flow into the condenser 20 in a gas-liquid mixed state. The gas-phase refrigerant of the gas-liquid mixed refrigerant 2 that flows into the condenser 20 is condensed and changes into liquid-phase refrigerant 1. The condensed liquid-phase refrigerant 1 flows from the condenser 20 through the third refrigerant flow path 73 and into the storage unit 30. The refrigerant that flows into the storage unit 30 flows through the fourth refrigerant flow path 74 and into the pump 10.

[0035] Furthermore, at the branching portion 76 of the first refrigerant flow path 71, the remainder of the liquid-phase refrigerant 1 flows into the bypass flow path 75. The refrigerant that has flowed into the bypass flow path 75 flows through the orifice 61 provided in the bypass flow path 75 and flows into the junction portion 77 of the second refrigerant flow path 72. At the junction portion 77, the liquid-phase refrigerant 1 that has flowed from the bypass flow path 75 merges with the gas-liquid mixture refrigerant 2.

[0036] Next, referring to FIG. 2, the circulation of the refrigerant in the circulation device 100 for a two-phase cooling system when the evaporator 80 is not connected to the inlet side connection part 41 and the outlet side connection part 42 will be described.

[0037] When the evaporator 80 is not connected, the inlet-side opening / closing valve 51 and the outlet-side opening / closing valve 52 are fully closed to prevent the liquid-phase refrigerant 1 from flowing out from the inlet-side connecting portion 41 and the gas-liquid mixed refrigerant 2 from flowing out from the outlet-side connecting portion 42. As a result, unlike when the evaporator 80 is connected to the inlet-side connecting portion 41 and the outlet-side connecting portion 42, at the branching portion 76 of the first refrigerant flow path 71, the liquid-phase refrigerant 1 flows into the bypass flow path 75 except for the refrigerant that flows between the branching portion 76 and the inlet-side opening / closing valve 51. Furthermore, at the junction 77 of the second refrigerant flow path 72, the liquid-phase refrigerant 1 that flows from the bypass flow path 75 flows through the second refrigerant flow path 72 and into the condenser 20.

[0038] Liquid-phase refrigerant 1 is pumped from pump 10. The liquid-phase refrigerant 1 flows through first refrigerant flow path 71. At branching point 76 of first refrigerant flow path 71, the liquid-phase refrigerant 1 flows into bypass flow path 75. The liquid-phase refrigerant 1 that has flowed into bypass flow path 75 flows through orifice 61 provided in bypass flow path 75 and flows into junction point 77 of second refrigerant flow path 72. The liquid-phase refrigerant 1 that has flowed into junction point 77 flows through second refrigerant flow path 72 and into condenser 20, except for the refrigerant that has flowed between junction point 77 and outlet-side opening / closing valve 52. The liquid-phase refrigerant 1 that has flowed into condenser 20 is cooled or maintained in a cooled state. The liquid-phase refrigerant 1 flows from condenser 20 through third refrigerant flow path 73 and flows into storage section 30. The refrigerant that has flowed into the reservoir 30 flows through the fourth refrigerant flow path 74 and into the pump 10 .

[0039] (Effects of First Embodiment) In the first embodiment, the following effects can be obtained.

[0040] As described above, the first embodiment includes the bypass flow path 75, which branches downstream of the pump 10 and upstream of the inlet-side connection 41 and allows the refrigerant to flow to the condenser 20 without passing through the inlet-side connection 41 and the outlet-side connection 42. When at least the evaporator 80 is not connected to the inlet-side connection 41 and the outlet-side connection 42, the refrigerant is circulated through the bypass flow path 75 without passing through the inlet-side connection 41 and the outlet-side connection 42. As a result, even when the removable evaporator 80 is not connected to the inlet-side connection 41 and the outlet-side connection 42, the liquid-phase refrigerant 1 can be circulated through the bypass flow path 75, allowing the condenser 20 to continuously cool the liquid-phase refrigerant 1. Therefore, even immediately after the removable evaporator 80 is detached from the inlet-side connection 41 and the outlet-side connection 42 and then reconnected, the cooled liquid-phase refrigerant 1 can flow into the evaporator 80, and the evaporator 80 can immediately cool the heat source 81.

[0041] Furthermore, in the first embodiment, as described above, the refrigerant circulation method includes the steps of circulating the refrigerant through the bypass flow path 75, which circulates the refrigerant without passing through the inlet-side connection 41 and the outlet-side connection 42, when at least the evaporator 80 is not connected to the inlet-side connection 41 and the outlet-side connection 42, and cooling the refrigerant that has flowed through the bypass flow path 75 and flowed into the condenser 20. As a result, even when the removable evaporator 80 is not connected to the inlet-side connection 41 and the outlet-side connection 42, the liquid-phase refrigerant 1 can be circulated through the bypass flow path 75, so that the liquid-phase refrigerant 1 can be continuously cooled by the condenser 20. Therefore, even immediately after the removable evaporator 80 is reconnected after being detached from the inlet-side connection 41 and the outlet-side connection 42, the cooled liquid-phase refrigerant 1 can be flowed into the evaporator 80, and the heat source 81 can be immediately cooled by the evaporator 80.

[0042] Furthermore, in the first embodiment, the following additional effects can be obtained by configuring as follows.

[0043] That is, in the first embodiment, as described above, in a normal operating state in which the evaporator 80 is connected to the inlet-side connection 41 and the outlet-side connection 42, a portion of the refrigerant is circulated through the evaporator 80, and the remainder of the refrigerant is circulated through the bypass flow path 75. As a result, even if the refrigerant cannot be circulated through the evaporator 80 due to blockage of the evaporator 80 in a normal operating state in which the evaporator 80 is connected to the inlet-side connection 41 and the outlet-side connection 42, the liquid-phase refrigerant 1 can be circulated through the bypass flow path 75. Therefore, it is possible to suppress malfunctions of the circulation device 100 for a two-phase cooling system caused by an increase in pressure at the outlet of the pump 10 due to an inability to circulate the refrigerant.

[0044] Furthermore, in the first embodiment, as described above, the flow rate adjusting unit 60 is further provided in the bypass flow path 75. The flow rate adjusting unit 60 can reduce the flow path cross-sectional area of ​​a portion of the bypass flow path 75, thereby increasing the pressure loss of the bypass flow path 75. This can reduce the refrigerant flow rate flowing into the bypass flow path 75 when the evaporator 80 is connected. Therefore, when the evaporator 80 is connected, the refrigerant flow rate flowing into the evaporator 80 and the refrigerant flow rate flowing into the bypass flow path 75 can be adjusted so that the refrigerant flow rate flowing into the evaporator 80 is greater than the refrigerant flow rate flowing into the bypass flow path 75.

[0045] In the first embodiment, as described above, the flow rate adjusting unit 60 is the orifice 61 that adjusts the flow rate of the refrigerant flowing through the bypass flow path 75. The orifice 61 can increase the pressure loss of the bypass flow path 75, thereby reducing the flow rate of the refrigerant flowing into the bypass flow path 75. Therefore, the flow rate of the liquid-phase refrigerant 1 flowing into the evaporator 80 and the flow rate of the liquid-phase refrigerant 1 flowing into the bypass flow path 75 can be adjusted at the branching unit 76 with a simple configuration so that the flow rate of the refrigerant flowing into the evaporator 80 is greater than the flow rate of the refrigerant flowing into the bypass flow path 75.

[0046] Furthermore, in the first embodiment, as described above, the condenser 20 is configured to condense and cool the gas phase refrigerant contained in the gas-liquid mixture refrigerant 2 of the refrigerants by the cooling liquid 23 flowing in from the outside, or to cool the liquid phase refrigerant 1 of the refrigerants. Because the gas phase refrigerant contained in the gas-liquid mixture refrigerant 2 and the liquid phase refrigerant 1 are cooled by the cooling liquid 23 flowing in from the outside, it is possible to achieve both a simplified configuration of the condenser 20 and reliable cooling of the refrigerant.

[0047] Furthermore, in the first embodiment, as described above, the bypass flow path 75 branches downstream of the pump 10 and upstream of the inlet connector 41, and is connected downstream of the outlet connector 42 and upstream of the condenser 20. As a result, the bypass flow path 75 is not directly connected to the condenser 20, but is connected to the flow path between the outlet connector 42 and the condenser 20. Therefore, multiple refrigerant flow paths are not connected to the condenser 20, which further simplifies the configuration of the condenser 20. As a result, it is possible to further prevent the size of the circulation device 100 for a two-phase cooling system from increasing.

[0048] As described above, the first embodiment further includes the inlet-side on-off valve 51, which is provided downstream of the pump 10 between the branching portion where the bypass flow path 75 branches and the inlet-side connecting portion 41 and opens and closes the refrigerant flow path, and the outlet-side on-off valve 52, which is provided between the outlet-side connecting portion 42 and the connecting portion where the bypass flow path 75 is connected downstream of the outlet-side connecting portion 42 and opens and closes the refrigerant flow path. Thus, when the evaporator 80 is not connected, the inlet-side on-off valve 51 and the outlet-side on-off valve 52 are fully closed, thereby preventing the liquid-phase refrigerant 1 from flowing out from the inlet-side connecting portion 41 and the gas-liquid mixed refrigerant 2 from flowing out from the outlet-side connecting portion 42. When the evaporator 80 is removed from the inlet-side connecting portion 41 and the outlet-side connecting portion 42, the inlet-side on-off valve 51 and the outlet-side on-off valve 52 are fully closed before removing the evaporator 80. This allows the condenser 20 to cool the liquid-phase refrigerant 1 circulating through the bypass flow path 75 without stopping the condenser 20. Therefore, even immediately after the detachable evaporator 80 is connected to the inlet side connection portion 41 and the outlet side connection portion 42, appropriately cooled refrigerant can be flowed into the evaporator 80, and the heat source 81 can be cooled more immediately by the evaporator 80.

[0049] Furthermore, in the first embodiment, as described above, the storage unit 30 is further provided downstream of the condenser 20 and upstream of the pump 10. As a result, when there is gas-liquid mixed refrigerant 2 that has not been completely condensed in the condenser 20, the storage unit 30 can separate the bubbles (gas-phase refrigerant) contained in the gas-liquid mixed refrigerant 2, thereby sending only the liquid-phase refrigerant 1 to the pump 10. As a result, it is possible to suppress malfunctions of the pump 10 caused by the bubbles (gas-phase refrigerant) contained in the refrigerant.

[0050] Furthermore, in the first embodiment, as described above, in a state in which the evaporator 80 is connected to the inlet-side connection portion 41 and the outlet-side connection portion 42, the gas-liquid mixed refrigerant 2 flowing out of the evaporator 80 flows into the condenser 20. As a result, the gas-liquid mixed refrigerant 2 flows out of the evaporator 80 without completely evaporating the liquid-phase refrigerant 1 in the evaporator 80, and therefore, it is possible to prevent the heat source from being insufficiently cooled using the latent heat of evaporation in the evaporator 80.

[0051] Second Embodiment The overall configuration of a circulation device 300 for a two-phase cooling system and a refrigerant recovery method for recovering refrigerant from an evaporator 80 according to a second embodiment will be described with reference to FIGS.

[0052] For example, when performing maintenance on an evaporator installed in a two-phase cooling system circulation device, the evaporator is removed from the two-phase cooling system circulation device. When removing the evaporator from the two-phase cooling system circulation device, if liquid refrigerant remains in the refrigerant flow path inside the evaporator, the remaining liquid refrigerant may evaporate and flow out, resulting in refrigerant loss or freezing due to the heat of vaporization. Therefore, in order to reduce the amount of refrigerant remaining inside the evaporator when removing it from the two-phase cooling system circulation device, it is necessary to recover the refrigerant remaining in the refrigerant flow path inside the evaporator into a reservoir before removing the evaporator from the two-phase cooling system circulation device.

[0053] (Overall Configuration of Circulation Device for Two-Phase Cooling System) The overall configuration of a circulation device 300 for a two-phase cooling system according to a second embodiment will be described with reference to Figures 5 and 6. Figure 5 shows the circulation device 300 for a two-phase cooling system in a refrigerant recovery state when recovering refrigerant from the evaporator 80. In the refrigerant recovery state of the circulation device 300 for a two-phase cooling system, the evaporator 80 is connected to the inlet-side connector 41 and the outlet-side connector 42, the inlet-side opening / closing valve 51 is closed, and the outlet-side opening / closing valve 52 is open. Note that components similar to those in the first embodiment are designated by the same reference numerals, and descriptions thereof will be omitted.

[0054] Compared to the circulation device 100 for a two-phase cooling system according to the first embodiment, the circulation device 300 for a two-phase cooling system according to the second embodiment further includes an inlet side opening / closing valve opening / closing mechanism 53, an outlet side opening / closing valve opening / closing mechanism 54, a detection unit 31, and a control device 90 (see Figure 6).

[0055] The inlet-side on-off valve opening / closing mechanism 53 is configured to be able to switch the inlet-side on-off valve 51 between an open state and a closed state. The inlet-side on-off valve opening / closing mechanism 53 includes, for example, a motor. The inlet-side on-off valve opening / closing mechanism 53 is connected to a control unit 91 (see FIG. 6 ). The inlet-side on-off valve 51 is opened and closed by the inlet-side on-off valve opening / closing mechanism 53 under the control of the control unit 91.

[0056] The outlet-side on-off valve opening / closing mechanism 54 is configured to be able to switch the outlet-side on-off valve 52 between an open state and a closed state. The outlet-side on-off valve opening / closing mechanism 54 includes, for example, a motor. The outlet-side on-off valve opening / closing mechanism 54 is connected to a control unit 91 (see FIG. 6 ). The outlet-side on-off valve 52 is opened and closed by the outlet-side on-off valve opening / closing mechanism 54 under the control of the control unit 91. Note that the configurations of the inlet-side on-off valve opening / closing mechanism 53 and the outlet-side on-off valve opening / closing mechanism 54 are not particularly limited as long as they are known valve opening / closing mechanisms.

[0057] The detection unit 31 is configured to detect the amount of recovered refrigerant. Specifically, the detection unit 31 is configured to detect the amount of refrigerant stored in the storage unit 30 as the amount of recovered refrigerant. The detection unit 31 is, for example, a liquid level sensor, and measures the liquid level 3 (see FIG. 7 ) of the liquid-phase refrigerant stored in the storage unit 30.

[0058] As shown in FIG. 6 , the control device 90 includes a control unit 91 and a storage unit 92. The control unit 91 is configured to stop operation of the pump 10 and terminate the refrigerant recovery process based on the detection result by the detection unit 31. The control unit 91 is also configured to close the outlet-side opening / closing valve 52 using the outlet-side opening / closing valve opening / closing mechanism 54 based on the detection result by the detection unit 31, thereby preventing refrigerant from flowing out from the outlet-side opening / closing valve 52 to the outlet-side connection unit 42. The control unit 91 is configured, for example, by a processor such as a CPU (Central Processing Unit). The storage unit 92 includes a volatile storage device and a non-volatile storage device. The storage unit 92 stores a set amount of refrigerant to be stored in the storage unit 30 (described later) and a program for setting the set amount. The set amount includes a set liquid level 5 (see FIG. 7 ), described later. The program for setting the set amount includes a program for setting the set liquid level 5. The volatile storage device is also used for temporary storage when the control unit 91 performs calculations.

[0059] (Circulation of Refrigerant When Recovering Refrigerant from Evaporator) Referring to FIG. 5, the circulation of refrigerant when recovering refrigerant from the evaporator 80 connected to the circulation device 300 for a two-phase cooling system will be described.

[0060] In the refrigerant recovery state of the two-phase cooling system circulation device 300, the evaporator 80 is connected to the inlet side connection part 41 and the outlet side connection part 42. The inlet side opening / closing valve 51 is closed, and the outlet side opening / closing valve 52 is open. The heat source 81 is not generating heat.

[0061] Liquid-phase refrigerant 1 is pumped from pump 10. The liquid-phase refrigerant 1 flows through first refrigerant flow path 71. Because inlet-side on-off valve 51 is fully closed, at branching portion 76 of first refrigerant flow path 71, the liquid-phase refrigerant 1 flows into bypass flow path 75, except for the refrigerant 1 flowing between branching portion 76 and inlet-side on-off valve 51. The liquid-phase refrigerant 1 that flows into bypass flow path 75 flows into junction portion 77 of second refrigerant flow path 72. The liquid-phase refrigerant 1 that flows into junction portion 77 flows through second refrigerant flow path 72 and into condenser 20. The refrigerant that flows into condenser 20 flows through third refrigerant flow path 73 and into storage portion 30. The refrigerant that flows into storage portion 30 flows through fourth refrigerant flow path 74 and into pump 10.

[0062] Liquid-phase refrigerant 1 is not sent from pump 10 to evaporator 80. Therefore, liquid-phase refrigerant 1 circulating through two-phase cooling system circulation device 300 does not flow into evaporator 80 in the refrigerant recovery state. Then, immediately after inlet-side open / close valve 51 is fully closed, liquid-phase refrigerant 1 remains in refrigerant flow path 83 inside evaporator 80. Although heat generation from heat source 81 has stopped, the temperature inside evaporator 80 rises due to heat from the outside air. Due to the rise in temperature inside evaporator 80, the temperature and pressure of liquid-phase refrigerant 1 remaining in evaporator 80 rise, and a portion of the liquid-phase refrigerant 1 evaporates and changes into gas-liquid mixed refrigerant 2.

[0063] Here, liquid-phase refrigerant 1 sent from pump 10 flows from bypass flow path 75 into junction 77 of second refrigerant flow path 72 and circulates through second refrigerant flow path 72, condenser 20, third refrigerant flow path 73, storage section 30, and fourth refrigerant flow path 74. This circulating liquid-phase refrigerant 1 is cooled or maintained in a cooled state by condenser 20. Therefore, the pressure of the gas-phase refrigerant in the gas-liquid mixed refrigerant 2 residing in evaporator 80 is higher than the pressure of the liquid-phase refrigerant 1 circulating through two-phase cooling system circulation device 300. In other words, the pressure difference between the pressure of the gas-phase refrigerant contained in the gas-liquid mixed refrigerant 2 in evaporator 80 and the pressure of the liquid-phase refrigerant 1 circulating in the path from junction 77 of second refrigerant flow path 72 through condenser 20, storage section 30, pump 10, and bypass flow path 75 becomes large. Due to this pressure difference, the gas-liquid mixed refrigerant 2 in the evaporator 80 flows out from the evaporator 80 toward the confluence portion 77 of the second refrigerant flow path 72. Specifically, the gas phase refrigerant of the gas-liquid mixed refrigerant 2 in the evaporator 80 flows out from the evaporator 80 toward the confluence portion 77 of the second refrigerant flow path 72, and also flows out so as to push out the liquid phase refrigerant of the gas-liquid mixed refrigerant 2 in the evaporator 80. Then, at the confluence portion 77, the gas-liquid mixed refrigerant 2 flowing out from the evaporator 80 merges with the liquid phase refrigerant 1 flowing in from the bypass flow path 75, and the gas phase refrigerant contained in the merged gas-liquid mixed refrigerant 2 is condensed. The liquid phase refrigerant 1 after the merger flows through the second refrigerant flow path 72 and flows into the condenser 20. That is, the gas-liquid mixed refrigerant 2 in the evaporator 80 flows through the second refrigerant flow path 72 and is guided to the condenser 20.

[0064] As a result, the refrigerant remaining in the refrigerant flow path inside the evaporator 80 is recovered into the reservoir 30. Note that, because the flow path 83 inside the evaporator 80 cannot be evacuated, it is not possible to recover all of the refrigerant inside the evaporator 80. However, it is possible to reduce the amount of refrigerant remaining inside the evaporator 80 when the evaporator 80 is removed from the circulation device 300 for a two-phase cooling system.

[0065] (Control of Termination of Refrigerant Recovery Process by Control Unit Based on Detection Result of Detector) With reference to FIG. 7, control of termination of refrigerant recovery process by control unit 91 based on the detection result of detector 31 will be described.

[0066] In the refrigerant recovery state, when the amount of stored refrigerant detected by the detection unit 31 while circulating the refrigerant through the bypass flow path 75 without passing through the evaporator 80 becomes equal to or exceeds a preset amount, the control unit 91 closes the outlet-side opening / closing valve 52 to prevent the refrigerant from flowing out from the outlet-side opening / closing valve 52 to the outlet-side connecting unit 42, and stops the operation of the pump 10 to terminate the refrigerant recovery process. The preset amount of stored refrigerant includes a preset liquid level of 5. The preset amount of stored refrigerant also includes a liquid level of 3.

[0067] 2, before the evaporator 80 is connected to the circulation device 300 for a two-phase cooling system, the refrigerant is circulated through the bypass flow path 75 without passing through the inlet side connection part 41 and the outlet side connection part 42. That is, the refrigerant circulates within the circulation device 300 for a two-phase cooling system in a state where the evaporator 80 is not connected to the inlet side connection part 41 and the outlet side connection part 42. At this time, the detection part 31 (see FIG. 5) measures the liquid level of the liquid-phase refrigerant 1 stored in the storage part 30.

[0068] Here, if the liquid level 3 (see FIG. 7 ) of the liquid-phase refrigerant 1 stored in the storage unit 30 in the refrigerant recovery state becomes equal to the liquid level of the liquid-phase refrigerant 1 stored in the storage unit 30 when the evaporator 80 is not connected, it can be said that the refrigerant remaining in the evaporator 80 has been recovered to the storage unit 30. However, as described above, it is not possible to recover all of the refrigerant in the evaporator 80. Therefore, as shown in FIG. 7 , a set liquid level 5 is set based on the liquid level 4 of the liquid-phase refrigerant 1 stored in the storage unit 30 when the evaporator 80 is not connected. The set liquid level 5 is the liquid level of the liquid-phase refrigerant 1 stored in the storage unit 30 in the refrigerant recovery state, which is set by subtracting a margin, such as the amount of refrigerant that cannot be recovered in the evaporator 80, from the liquid level 4 of the liquid-phase refrigerant 1 stored in the storage unit 30 when the evaporator 80 is not connected. Therefore, when the liquid level of the liquid phase refrigerant stored in the storage section 30 during refrigerant recovery becomes equal to or higher than the set liquid level 5, it can be considered that the refrigerant remaining in the evaporator 80 has been recovered into the storage section 30.

[0069] The set liquid level 5 is set by the control unit 91. That is, the control unit 91 acquires the liquid level 4 of the liquid phase refrigerant 1 stored in the storage unit 30 when the evaporator 80 is not connected, which is detected by the detection unit 31, and sets the set liquid level 5 by executing a program for setting the set liquid level 5 stored in the memory unit 92. The set set liquid level 5 is stored in the memory unit 92.

[0070] For example, when the evaporator 80 is removed from the circulation device 300 for a two-phase cooling system for maintenance, the refrigerant is recovered from the evaporator 80 before removal. Specifically, the evaporator 80 is connected to the inlet-side connection 41 and the outlet-side connection 42, the inlet-side opening / closing valve 51 and the outlet-side opening / closing valve 52 are open, and the heat source 81 is cooled by the evaporator 80, as shown in FIG. 1 . The evaporator 80 is then connected to the inlet-side connection 41 and the outlet-side connection 42, the inlet-side opening / closing valve 51 is closed, and the outlet-side opening / closing valve 52 is open. As shown in FIG. 5 , the evaporator 80 is connected to the inlet-side connection 41 and the outlet-side connection 42, the inlet-side opening / closing valve 51 is closed, and the outlet-side opening / closing valve 52 is open. The refrigerant is circulated through the bypass flow path 75 without passing through the evaporator 80. In the refrigerant recovery state, the heat source 81 is stopped from generating heat. At this time, the detector 31 measures the liquid level 3 (see FIG. 7 ) of the liquid-phase refrigerant 1 stored in the storage unit 30 in the refrigerant recovery state.

[0071] The control unit 91 acquires the liquid level 3 of the liquid phase refrigerant 1 stored in the storage unit 30, detected by the detection unit 31. As shown in Fig. 7 , the liquid level h (liquid level 3) of the liquid phase refrigerant 1 stored in the storage unit 30 rises as time t passes. When the liquid level 3 of the liquid phase refrigerant 1 detected by the detection unit 31 becomes equal to or higher than a preset liquid level 5 (time t1), the control unit 91 performs control to close the outlet side opening / closing valve 52 to prevent the refrigerant from flowing out from the outlet side opening / closing valve 52 to the outlet side connection unit 42, and also performs control to stop the operation of the pump 10 to end the refrigerant recovery process.

[0072] (Refrigerant recovery process by the control unit) The refrigerant recovery process by the control unit 91 according to the second embodiment will be described with reference to Fig. 8. The order of the processing steps can be reversed or can be performed simultaneously as long as there are no contradictions.

[0073] In step S1, with the evaporator 80 connected, the inlet-side on-off valve 51 and the outlet-side on-off valve 52 open, and the heat source 81 cooled by the evaporator 80, after the heat source 81 stops generating heat, the control unit 91 closes the inlet-side on-off valve 51 using the inlet-side on-off valve on-off mechanism 53 to enter a refrigerant recovery state. In the refrigerant recovery state, the refrigerant is circulated via the bypass flow path 75 without passing through the evaporator 80. Then, the process proceeds to step S2.

[0074] In step S2, the control unit 91 acquires the liquid level 3 of the liquid-phase refrigerant 1 stored in the storage unit 30, which is detected by the detection unit 31. Thereafter, the process proceeds to step S3.

[0075] In step S3, if the liquid level 3 of the acquired liquid phase refrigerant 1 is equal to or greater than the set liquid level 5 (Yes in step S3), the control unit 91 proceeds to step S4, and if the liquid level 3 is less than the set liquid level 5 (No in step S3), the control unit 91 proceeds to step S2.

[0076] In step S4, the control unit 91 closes the outlet-side opening / closing valve 52 using the outlet-side opening / closing valve opening / closing mechanism 54. Thereafter, the process proceeds to step S5.

[0077] In step S5, the control unit 91 stops the operation of the pump 10. Thereafter, the refrigerant recovery process ends.

[0078] (Effects of Second Embodiment) In the second embodiment, the following effects can be obtained.

[0079] As described above, the second embodiment further includes an inlet-side opening / closing valve 51, which is provided downstream of the pump 10 between the branch point 76 where the bypass flow path 75 branches and the inlet-side connecting portion 41 and opens and closes the refrigerant flow path. When recovering refrigerant from the evaporator 80, the evaporator 80 is connected to the inlet-side connecting portion 41 and the outlet-side connecting portion 42. In a refrigerant recovery state in which the inlet-side opening / closing valve 51 is closed, the refrigerant is circulated through the bypass flow path 75 without passing through the evaporator 80, and the refrigerant in the evaporator 80 is directed to the condenser 20. Because the inlet-side opening / closing valve 51 is closed, the circulating liquid-phase refrigerant 1 does not flow into the evaporator 80. Furthermore, the evaporator 80 receives heat from the outside air, causing the temperature inside the evaporator 80 to rise. Therefore, the temperature and pressure of the liquid-phase refrigerant 1 remaining in the evaporator 80 rise, and a portion of the liquid-phase refrigerant 1 in the evaporator 80 evaporates and changes into a gas-liquid mixture of refrigerant 2. This creates a pressure difference between the pressure of the gas-phase refrigerant contained in the gas-liquid mixed refrigerant 2 in the evaporator 80 and the pressure of the liquid-phase refrigerant 1 circulating in the path from the confluence 77 of the second refrigerant flow path 72 through the condenser 20, the storage section 30, the pump 10, and the bypass flow path 75, so that the gas-liquid mixed refrigerant 2 in the evaporator 80 can flow out from the evaporator 80 toward the confluence 77 of the second refrigerant flow path 72. Furthermore, because the liquid-phase refrigerant 1 in the evaporator 80 can be converted into the gas-liquid mixed refrigerant 2 by the increase in the temperature inside the evaporator 80, there is no need to provide additional equipment such as a heater for converting the liquid-phase refrigerant 1 into the gas-liquid mixed refrigerant 2. For these reasons, it is possible to suppress an increase in the number of parts and a complex structure, and it is also possible to easily recover the refrigerant remaining in the refrigerant flow path 83 inside the evaporator 80.

[0080] As described above, the second embodiment further includes a detection unit 31 that detects the amount of recovered refrigerant, and a control unit 91 that stops the operation of the pump 10 and terminates the refrigerant recovery process based on the detection result by the detection unit 31. This allows the refrigerant recovery process to be terminated based on the detection result by the detection unit 31 that detects the amount of recovered refrigerant. Therefore, the refrigerant recovery process can be reliably performed based on the detection result by the detection unit 31 that detects the amount of recovered refrigerant.

[0081] Furthermore, as described above, the second embodiment further includes a storage unit 30 provided downstream of the condenser 20 and upstream of the pump 10, and the detection unit 31 detects the amount of refrigerant stored in the storage unit 30 as the amount of recovered refrigerant. As a result, the operation of the pump 10 can be stopped and the refrigerant recovery process can be terminated based on the detection result of the amount of refrigerant stored in the storage unit 30 as the amount of recovered refrigerant. Therefore, the detection result of the amount of recovered refrigerant can be obtained using the simple configuration of the detection unit 31, which prevents the structure of the circulation device 300 for a two-phase cooling system from becoming complicated.

[0082] Furthermore, in the second embodiment, as described above, when the amount of stored refrigerant detected by the detection unit 31 while circulating the refrigerant through the bypass flow path 75 without passing through the evaporator 80 in the refrigerant recovery state becomes equal to or greater than a preset storage amount, the control unit 91 controls the pump 10 to stop operation and terminate the refrigerant recovery process. This makes it easier to detect, based on the set storage amount, that the refrigerant remaining in the evaporator 80 has been recovered into the storage unit 30. Therefore, the refrigerant recovery process can be performed more easily and reliably based on the set storage amount.

[0083] Furthermore, in the second embodiment, as described above, the outlet-side opening / closing valve 52 is provided between the outlet-side connecting part 42 and the connecting part downstream of the outlet-side connecting part 42 to which the bypass flow path 75 is connected, and opens and closes the refrigerant flow path, and the control part 91 performs control to close the outlet-side opening / closing valve 52 to prevent the refrigerant from flowing out from the outlet-side opening / closing valve 52 to the outlet-side connecting part 42 based on the detection result by the detection part 31. This makes it possible to prevent the refrigerant from flowing out from the outlet-side opening / closing valve 52 to the outside when, for example, removing the evaporator 80 from the two-phase cooling system circulation device 300, thereby suppressing additional charging of the refrigerant.

[0084] In the second embodiment, as described above, the refrigerant circulation method further includes the steps of: circulating the refrigerant through the bypass flow path 75 without passing through the evaporator 80 and directing the refrigerant from the evaporator 80 to the condenser 20 in a refrigerant recovery state in which the evaporator 80 is connected to the inlet connection 41 and the outlet connection 42 and the inlet valve 51, which is provided between the branching portion 76 where the bypass flow path 75 branches and the inlet connection 41, is closed; and stopping the circulation of the refrigerant and terminating the refrigerant recovery process based on the detection result of the amount of recovered refrigerant. Because the inlet valve 51 is closed, the circulating liquid-phase refrigerant 1 does not flow into the evaporator 80, and the evaporator 80 receives heat from the outside air, so the temperature inside the evaporator 80 rises. Therefore, the temperature and pressure of the liquid-phase refrigerant 1 remaining in the evaporator 80 rise, and a portion of the liquid-phase refrigerant 1 evaporates and changes into a gas-liquid mixture of refrigerant 2. This creates a pressure difference between the pressure of the gas-phase refrigerant contained in the gas-liquid mixed refrigerant 2 in the evaporator 80 and the pressure of the liquid-phase refrigerant 1 circulating in the path from the confluence 77 of the second refrigerant flow path 72 through the condenser 20, the storage section 30, the pump 10, and the bypass flow path 75, so that the gas-liquid mixed refrigerant 2 in the evaporator 80 can flow out from the evaporator 80 toward the confluence 77 of the second refrigerant flow path 72. Furthermore, because the liquid-phase refrigerant 1 in the evaporator 80 can be converted into the gas-liquid mixed refrigerant 2 by the increase in the temperature inside the evaporator 80, there is no need to provide additional equipment such as a heater for converting the liquid-phase refrigerant 1 into the gas-liquid mixed refrigerant 2. For these reasons, it is possible to suppress an increase in the number of parts and a complex structure, and it is also possible to easily recover the refrigerant remaining in the refrigerant flow path 83 inside the evaporator 80.

[0085] [Modifications] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the description of the above-mentioned embodiments, and further includes all modifications (modifications) within the meaning and scope of the claims.

[0086] For example, in the first embodiment described above, an example was shown in which the flow rate adjustment unit 60 was provided in the bypass flow path 75, but the present invention is not limited to this. For example, as in a first modified example shown in Fig. 3 , the flow rate adjustment unit 60 does not have to be provided in the bypass flow path 75. When the flow rate adjustment unit 60 is not provided in the bypass flow path 75, the distribution of the refrigerant flow rate between the evaporator 80 and the bypass flow path 75 when the evaporator 80 is connected can be adjusted by, for example, the pipe diameter or the flow path length of the bypass flow path 75.

[0087] In the first embodiment, the refrigerant flow rate flowing into the evaporator 80 is greater than the refrigerant flow rate flowing into the bypass passage 75. However, the present invention is not limited to this. For example, the refrigerant flow rate flowing into the evaporator 80 and the refrigerant flow rate flowing into the bypass passage 75 may be configured to be equal, or the refrigerant flow rate flowing into the evaporator 80 may be configured to be less than the refrigerant flow rate flowing into the bypass passage 75.

[0088] Furthermore, in the first embodiment described above, an example was shown in which the flow rate adjustment unit 60 was an orifice 61, but the present invention is not limited to this. For example, as in a second modified example shown in Fig. 4, the flow rate adjustment unit 60 may be a flow rate adjustment valve 62. The flow rate adjustment valve 62 is not particularly limited as long as it is a known valve, such as a needle valve, that can be shut off and adjust the flow rate. Furthermore, the opening degree of the flow rate adjustment valve 62 may be adjusted manually or by computer control.

[0089] When the flow rate adjustment unit 60 is a flow rate adjustment valve 62, the flow rate adjustment unit 60 may be configured to adjust the opening degree of the flow rate adjustment valve 62 according to the cooling level of the cooling target, which is the heat source 81. For example, the opening degree of the flow rate adjustment valve 62 can be set larger in a state where the cooling target requires less cooling than in a normal operating state than in a normal operating state. This allows the refrigerant flow rate flowing into the evaporator 80 to be smaller than the refrigerant flow rate flowing into the bypass flow path 75, for example. Furthermore, since the pump 10 does not need to adjust the amount of refrigerant flowing into the evaporator 80, the burden on the pump 10 can be reduced. Furthermore, when it is desired to keep the refrigerant flow rate flowing into the evaporator 80 equal to or lower than the minimum flow rate of the pump 10, the opening degree of the flow rate adjustment valve 62 can be increased to adjust the refrigerant flow rate flowing into the evaporator 80 to be smaller.

[0090] In the first embodiment, an example was shown in which the inlet-side opening / closing valve 51 and the outlet-side opening / closing valve 52 were provided, but the present invention is not limited to this. For example, both the inlet-side opening / closing valve 51 and the outlet-side opening / closing valve 52 do not have to be provided, or either the inlet-side opening / closing valve 51 or the outlet-side opening / closing valve 52 may not be provided.

[0091] In the first embodiment, the bypass flow path 75 is connected downstream of the outlet connector 42 and upstream of the condenser 20, but the present invention is not limited to this. For example, the bypass flow path 75 may be directly connected to the condenser 20, and may not be connected to the flow path between the outlet connector 42 and the condenser 20.

[0092] Furthermore, in the first embodiment, an example was shown in which the reservoir 30 was provided, but the present invention is not limited to this. For example, the reservoir 30 does not have to be provided.

[0093] In the first embodiment, the circulation device 100 for a two-phase cooling system is a portable type, but the present invention is not limited to this. For example, the circulation device 100 for a two-phase cooling system may be a fixed installation type.

[0094] In the first embodiment, the refrigerant 2 in the gas-liquid mixed state flows out of the evaporator 80 into the condenser 20 while the evaporator 80 is connected. However, the present invention is not limited to this. For example, the refrigerant may be configured so that it flows out of the evaporator 80 in a single gas phase.

[0095] In the second embodiment, the detection unit 31 is a liquid level sensor, and the amount of refrigerant stored in the storage unit 30 (the amount of recovered refrigerant) is detected by measuring the liquid level 3 of the liquid-phase refrigerant 1 stored in the storage unit 30. However, the present invention is not limited to this. For example, the detection unit may be a differential pressure level sensor, and the amount of refrigerant stored in the storage unit (the amount of recovered refrigerant) may be detected by measuring the liquid level from the difference between the pressure at the bottom of the storage unit and the pressure at the liquid level. The detection unit may also be another known sensor.

[0096] In the second embodiment, the set liquid level 5 is set by the control unit 91, but the present invention is not limited to this. For example, the set liquid level 5 may be set by the user.

[0097] In the second embodiment, the detector 31 detects the amount of refrigerant stored in the storage unit 30 as the amount of recovered refrigerant. However, the present invention is not limited to this. For example, the circulation device for a two-phase cooling system may be configured to include detectors near the inlet and outlet of the storage unit, respectively, and to detect the amount of recovered refrigerant based on the refrigerant flow rate detected by the detector near the inlet and the detector near the outlet. In this case, when the difference between the refrigerant flow rate detected by the detector near the inlet and the refrigerant flow rate detected by the detector near the outlet becomes equal to or less than a threshold, the control unit may stop operation of the pump and terminate the refrigerant recovery process. Furthermore, for example, the circulation device for a two-phase cooling system may be configured to include a detector between the outlet-side opening / closing valve and the confluence unit, and to detect the amount of recovered refrigerant based on the refrigerant flow rate detected by the detector.

[0098] In the second embodiment, the control unit 91 stops the operation of the pump 10 and terminates the refrigerant recovery process when the amount of stored refrigerant detected by the detection unit 31 becomes equal to or greater than a preset amount. However, the present invention is not limited to this. For example, as in a third modified example, the control unit 91 may stop the operation of the pump 10 and terminate the refrigerant recovery process when the amount of change in the amount of stored refrigerant detected by the detection unit 31 becomes equal to or less than a preset amount of change. The amount of change in the amount of stored refrigerant includes the amount of change 6 of the refrigerant liquid level (see FIG. 9 ).

[0099] As shown in Figure 9, immediately after the inlet side opening / closing valve 51 is closed to enter the refrigerant recovery state, the change amount 6 per unit time of the liquid level of the liquid phase refrigerant 1 stored in the storage unit 30 is greatest, and as time t passes, the change amount 6 per unit time of the liquid phase refrigerant 1 decreases. Therefore, the change amount per unit time of the liquid phase refrigerant 1 is set in advance as a set change amount 7. The set change amount 7 is a reference value at which it can be assumed that the refrigerant remaining in the evaporator 80 has been recovered to the storage unit 30. The set change amount 7 is set in advance by the user. The set change amount 7 is stored in the memory unit 92.

[0100] In the refrigerant recovery state, the control unit 91 acquires the liquid level of the liquid-phase refrigerant 1 stored in the storage unit 30, detected by the detection unit 31. The control unit 91 acquires a change amount 6 per unit time of the liquid level of the liquid-phase refrigerant 1, based on the liquid level of the liquid-phase refrigerant 1 detected by the detection unit 31. Then, when the change amount 6 of the liquid level of the liquid-phase refrigerant 1 becomes equal to or less than a preset change amount 7 (at time t2), the control unit 91 performs control to close the outlet-side opening / closing valve 52 to prevent the refrigerant from flowing out from the outlet-side opening / closing valve 52 to the outlet-side connection unit 42, and also performs control to stop the operation of the pump 10 to end the refrigerant recovery process.

[0101] According to the third modification, as described above, in the refrigerant recovery state, when the amount of change in the amount of stored refrigerant detected by the detection unit 31 while the refrigerant is circulating through the bypass flow path 75 without passing through the evaporator 80 becomes equal to or less than the preset set change amount 7, the control unit 91 controls the pump 10 to stop operation and terminate the refrigerant recovery process. As a result, even if the total amount of refrigerant changes due to a decrease in the amount of refrigerant during normal operation to cool the heat source 81, the control unit 91 can reliably detect, based on the set change amount 7, that the refrigerant remaining in the evaporator 80 has been recovered into the storage unit 30.

[0102] Furthermore, the control unit 91 may be configured to control the pump 10 to stop operation and terminate the refrigerant recovery process when the liquid level 3 of the liquid phase refrigerant 1 detected by the detection unit 31 becomes equal to or higher than a preset set liquid level 5 (see Figure 7) and the change in liquid level 6 of the liquid phase refrigerant 1 detected by the detection unit 31 becomes equal to or lower than a preset set change amount 7.

[0103] In the second embodiment, the control unit 91 is configured to control the inlet valve 51 to be closed by the inlet valve mechanism 53, the outlet valve 52 to be closed by the outlet valve mechanism 54 based on the set storage volume, and the pump 10 to stop operating based on the set storage volume. However, the present invention is not limited to this. For example, the user may perform any or all of the following operations: closing the inlet valve 51, closing the outlet valve 52 based on the set storage volume, and stopping the pump 10 based on the set storage volume. If the user performs all of the following operations: closing the inlet valve 51, closing the outlet valve 52 based on the set storage volume, and stopping the pump 10 based on the set storage volume, a control unit may not be provided.

[0104] For example, the user may manually close the inlet-side opening / closing valve 51 before recovering refrigerant from the evaporator 80. The user may also manually close the outlet-side opening / closing valve 52 based on visual confirmation of the liquid level gauge. The user may also perform an operation to stop the operation of the pump 10 based on visual confirmation of the liquid level gauge.

[0105] In the second embodiment and the third modification, the control unit 91 controls the outlet valve 52 to close and the pump 10 to stop the refrigerant recovery process when the amount of stored refrigerant detected by the detection unit 31 becomes equal to or greater than a preset amount, or when the change in the amount of stored refrigerant detected by the detection unit 31 becomes equal to or less than a preset amount. However, the present invention is not limited to this. For example, as in a fourth modification, the circulation device 300 for a two-phase cooling system may further include an alarm 93, and the control unit 91 may be configured to alarm the amount of stored refrigerant detected by the detection unit 31 to become equal to or greater than the preset amount, or to alarm the amount of change in the amount of stored refrigerant detected by the detection unit 31 to become equal to or less than the preset amount. This allows the user to recognize that the amount of refrigerant stored detected by the detection unit 31 has become equal to or greater than the set amount, or that the change in the amount of refrigerant stored detected by the detection unit 31 has become equal to or less than the set change amount, thereby allowing the user to quickly perform the operation of closing the outlet side opening / closing valve 52 and the operation of stopping the operation of the pump 10.

[0106] When the user is notified of the above by the notification unit 93, the user performs an operation to close the outlet side opening / closing valve 52 and also performs an operation to stop the operation of the pump 10.

[0107] In this case, the notification unit 93 may include a display unit 94, and when the amount of stored refrigerant detected by the detection unit 31 becomes equal to or greater than a preset set amount, or when the amount of change in the amount of stored refrigerant detected by the detection unit 31 becomes equal to or less than a preset change amount, the control unit 91 may control the display unit 94 to display a notification that "Refrigerant has been recovered." Alternatively, the notification unit 93 may include an audio output unit 95 instead of or in addition to the display unit 94, and when the amount of stored refrigerant detected by the detection unit 31 becomes equal to or greater than a preset set amount, or when the amount of change in the amount of stored refrigerant detected by the detection unit 31 becomes equal to or less than the preset change amount, the control unit 91 may control the audio output unit 95 to announce that "Refrigerant has been recovered."

[0108] Furthermore, in the first and second embodiments, examples have been described in which the inlet-side opening / closing valve 51, the outlet-side opening / closing valve 52, and the flow rate adjustment unit 60 are provided, but the present invention is not limited to this. For example, as in a fifth modified example shown in Fig. 12, instead of the inlet-side opening / closing valve 51, the outlet-side opening / closing valve 52, and the flow rate adjustment unit 60, a first three-way valve 98 may be provided in the branching unit 76 and a second three-way valve 99 may be provided in the merging unit 77. In this case, the control unit 91 may be configured to control switching between the first three-way valve 98 and the second three-way valve 99, or a user may switch between the first three-way valve 98 and the second three-way valve 99.

[0109] Aspects It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0110] (Item 1) A circulation device for a two-phase cooling system that constitutes a two-phase cooling system that circulates a refrigerant by connecting a removable evaporator, comprising: a pump that pumps the refrigerant; an inlet-side connector that is provided downstream of the pump and is connected to an inlet of the refrigerant of the evaporator, and an outlet-side connector that is connected to an outlet of the refrigerant; a condenser that is provided downstream of the outlet-side connector and cools the refrigerant; and a bypass flow path that branches downstream of the pump and upstream of the inlet-side connector and that circulates the refrigerant to the condenser without passing through the inlet-side connector and the outlet-side connector, wherein the circulation device for a two-phase cooling system circulates the refrigerant via the bypass flow path without passing through the inlet-side connector and the outlet-side connector at least when the evaporator is not connected to the inlet-side connector and the outlet-side connector.

[0111] (Item 2) In a normal operating state in which the evaporator is connected to the inlet side connection portion and the outlet side connection portion, a portion of the refrigerant is circulated through the evaporator, and the remainder of the refrigerant is circulated through the bypass flow path.

[0112] (Item 3) The circulation device for a two-phase cooling system according to item 1 or 2, further comprising a flow rate adjusting unit provided in the bypass flow path.

[0113] (Item 4) The circulation device for a two-phase cooling system according to Item 3, wherein the flow rate adjusting unit is an orifice that adjusts the flow rate of the refrigerant flowing through the bypass flow path.

[0114] (Item 5) The circulation device for a two-phase cooling system according to Item 3, wherein the flow rate adjustment unit is a flow rate adjustment valve that adjusts the flow rate of the refrigerant flowing through the bypass flow path.

[0115] (Item 6) The circulation device for a two-phase cooling system according to any one of Items 1 to 5, wherein the condenser is configured to condense and cool a gas phase refrigerant contained in a gas-liquid mixture of the refrigerant by a cooling liquid flowing in from an outside, or to cool a liquid phase refrigerant of the refrigerant.

[0116] (Item 7) The circulation device for a two-phase cooling system according to any one of Items 1 to 6, wherein the bypass flow path branches off downstream of the pump and upstream of the inlet connection part, and is connected downstream of the outlet connection part and upstream of the condenser.

[0117] (Item 8) The circulation device for a two-phase cooling system according to Item 7, further comprising: an inlet-side opening / closing valve provided between the inlet-side connecting part and a branching part where the bypass flow path branches downstream of the pump, the inlet-side opening / closing valve opening and closing the flow path of the refrigerant; and an outlet-side opening / closing valve provided between the outlet-side connecting part and a connecting part where the bypass flow path is connected downstream of the outlet-side connecting part, the outlet-side opening / closing valve opening and closing the flow path of the refrigerant.

[0118] (Item 9) The circulation device for a two-phase cooling system according to any one of items 1 to 8, further comprising a reservoir downstream of the condenser and upstream of the pump.

[0119] (Item 10) The circulation device for a two-phase cooling system according to any one of Items 1 to 9, wherein, in a state in which the evaporator is connected to the inlet-side connection portion and the outlet-side connection portion, the gas-liquid mixture of refrigerant flowing out of the evaporator flows into the condenser.

[0120] (Item 11) The circulation device for a two-phase cooling system according to item 1, further comprising an inlet-side opening / closing valve provided downstream of the pump between a branch point where the bypass flow path branches and the inlet-side connecting part, and opening and closing the refrigerant flow path, wherein when the refrigerant is recovered from the evaporator, the evaporator is connected to the inlet-side connecting part and the outlet-side connecting part, and in a refrigerant recovery state where the inlet-side opening / closing valve is closed, the refrigerant is circulated via the bypass flow path without passing through the evaporator, and the refrigerant in the evaporator is led to the condenser.

[0121] (Item 12) The circulation device for a two-phase cooling system according to Item 11, further comprising: a detection unit that detects an amount of the recovered refrigerant; and a control unit that stops operation of the pump and terminates the refrigerant recovery process based on a detection result by the detection unit.

[0122] (Item 13) The circulation device for a two-phase cooling system according to Item 12, further comprising a storage unit provided downstream of the condenser and upstream of the pump, wherein the detection unit detects the amount of the refrigerant stored in the storage unit as the amount of the recovered refrigerant.

[0123] (Item 14) In the refrigerant recovery state, when the amount of the refrigerant detected by the detection unit while the refrigerant is circulating through the bypass flow path without passing through the evaporator becomes equal to or greater than a preset amount, the control unit controls to stop operation of the pump and terminate the refrigerant recovery process.

[0124] (Item 15) In the refrigerant recovery state, when a change in the amount of stored refrigerant detected by the detection unit while the refrigerant is circulating through the bypass flow path without passing through the evaporator becomes equal to or less than a preset change amount, the control unit controls to stop operation of the pump and terminate the refrigerant recovery process.

[0125] (Item 16) The circulation device for a two-phase cooling system according to Item 14 or 15, further comprising a notification unit that notifies the user that the amount of stored refrigerant detected by the detection unit has reached or exceeded the set amount of stored refrigerant, or that the amount of change in the amount of stored refrigerant detected by the detection unit has reached or exceeded the set amount of change.

[0126] (Item 17) The circulation device for a two-phase cooling system according to Item 13, further comprising an outlet-side opening / closing valve provided between the outlet-side connecting portion and a connecting portion to which the bypass flow path is connected downstream of the outlet-side connecting portion, and opening and closing the flow path of the refrigerant, wherein the control portion performs control to close the outlet-side opening / closing valve to prevent the refrigerant from flowing out from the outlet-side opening / closing valve to the outlet-side connecting portion based on a detection result by the detection portion.

[0127] (Item 18) A refrigerant circulating method in a circulation device for a two-phase cooling system that constitutes a two-phase cooling system that circulates a refrigerant by connecting a removable evaporator, the refrigerant circulating method comprising the steps of: circulating the refrigerant through a bypass flow path that circulates the refrigerant without passing through the inlet side connection part and the outlet side connection part, when at least the evaporator is not connected to an inlet side connection part that is connected to an inlet of the refrigerant in the evaporator and an outlet side connection part that is connected to an outlet of the refrigerant; and cooling the refrigerant that has flowed through the bypass flow path and flowed into a condenser.

[0128] (Item 19) The refrigerant circulation method according to Item 18, further comprising: when recovering the refrigerant from the evaporator, the evaporator is connected to the inlet-side connection and the outlet-side connection, and in a refrigerant recovery state in which an inlet-side opening / closing valve provided between a branch point where the bypass flow path branches and the inlet-side connection is closed, circulating the refrigerant via the bypass flow path without passing through the evaporator and directing the refrigerant from the evaporator to the condenser; and stopping the circulation of the refrigerant and terminating the refrigerant recovery process based on a detection result of the amount of recovered refrigerant.

[0129] 2 Gas-liquid mixture refrigerant 5 Set liquid level (set storage amount) 7 Set change amount 10 Pump 20 Condenser 23 Cooling liquid 30 Storage section 31 Detection section 41 Inlet side connection section 42 Outlet side connection section 51 Inlet side opening / closing valve 52 Outlet side opening / closing valve 60 Flow rate adjustment section 61 Orifice 62 Flow rate adjustment valve 75 Bypass flow path 80 Evaporator 91 Control section 93 Notification section 100, 300 Circulation device for two-phase cooling system 200, 400 Two-phase cooling system

Claims

1. A two-phase cooling system circulation device that circulates a refrigerant by connecting a removable evaporator, A pump that pumps the refrigerant; an inlet side connection portion provided downstream of the pump and connected to an inlet of the refrigerant in the evaporator and an outlet side connection portion connected to an outlet of the refrigerant; a condenser provided downstream of the outlet connection portion and configured to cool the refrigerant; a bypass flow path that branches off downstream of the pump and upstream of the inlet connection portion and allows the refrigerant to flow to the condenser without passing through the inlet connection portion and the outlet connection portion, A circulation device for a two-phase cooling system, which circulates the refrigerant not through the inlet side connection part and the outlet side connection part and through the bypass flow path, at least when the evaporator is not connected to the inlet side connection part and the outlet side connection part.

2. 2. The circulation device for a two-phase cooling system according to claim 1, wherein in a normal operating state in which the evaporator is connected to the inlet side connection portion and the outlet side connection portion, a portion of the refrigerant is circulated through the evaporator, and the remaining portion of the refrigerant is circulated through the bypass flow path.

3. The circulation device for a two-phase cooling system according to claim 1 or 2, further comprising a flow rate regulator provided in the bypass flow path.

4. 2. The circulation device for a two-phase cooling system according to claim 1, wherein the condenser is configured to condense and cool a gas phase refrigerant contained in a gas-liquid mixed refrigerant among the refrigerants by a cooling liquid flowing in from an outside, or to cool a liquid phase refrigerant among the refrigerants.

5. 2. The circulation device for a two-phase cooling system according to claim 1, wherein the bypass flow path branches off downstream of the pump and upstream of the inlet side connection part, and is connected downstream of the outlet side connection part and upstream of the condenser.

6. 6. The circulation device for a two-phase cooling system according to claim 5, further comprising: an inlet side opening / closing valve provided between a branching portion where the bypass flow path branches off downstream of the pump and the inlet side connecting portion, opening and closing the flow path of the refrigerant; and an outlet side opening / closing valve provided between the outlet side connecting portion and a connecting portion where the bypass flow path is connected downstream of the outlet side connecting portion, opening and closing the flow path of the refrigerant.

7. 2. The circulation device for a two-phase cooling system according to claim 1, wherein, when the evaporator is connected to the inlet side connection portion and the outlet side connection portion, the gas-liquid mixture of refrigerant flowing out of the evaporator flows into the condenser.

8. an inlet side opening / closing valve that is provided between a branching portion where the bypass flow path branches off and the inlet side connecting portion on the downstream side of the pump and opens and closes the flow path of the refrigerant; 2. The circulation device for a two-phase cooling system according to claim 1, wherein, when recovering the refrigerant from the evaporator, the evaporator is connected to the inlet side connection part and the outlet side connection part, and in a refrigerant recovery state in which the inlet side opening / closing valve is closed, the refrigerant is circulated through the bypass flow path without passing through the evaporator, and the refrigerant in the evaporator is guided to the condenser.

9. A detection unit that detects the amount of recovered refrigerant; 9. The circulation device for a two-phase cooling system according to claim 8, further comprising: a control unit that stops operation of the pump and terminates the refrigerant recovery process based on a detection result by the detection unit.

10. The refrigerant supply system further comprises a reservoir disposed downstream of the condenser and upstream of the pump, The detection unit detects an amount of the refrigerant stored in the storage unit as an amount of the recovered refrigerant, 10. The circulation device for a two-phase cooling system according to claim 9, wherein, in the refrigerant recovery state, when the amount of the refrigerant detected by the detection unit while the refrigerant is circulated through the bypass flow path without passing through the evaporator becomes equal to or greater than a preset storage amount, the control unit controls to stop operation of the pump and terminate the refrigerant recovery process.

11. The refrigerant supply system further comprises a reservoir disposed downstream of the condenser and upstream of the pump, The detection unit detects an amount of the refrigerant stored in the storage unit as an amount of the recovered refrigerant, 10. The circulation device for a two-phase cooling system according to claim 9, wherein, in the refrigerant recovery state, when a change in the amount of stored refrigerant detected by the detection unit while the refrigerant is circulated through the bypass flow path without passing through the evaporator becomes equal to or less than a preset change amount, the control unit controls to stop operation of the pump and terminate the refrigerant recovery process.

12. The circulation device for a two-phase cooling system according to claim 10 , further comprising an alarm unit that notifies the user that the amount of the refrigerant detected by the detector has reached or exceeded the set amount.

13. The condenser further comprises a reservoir disposed downstream of the condenser and upstream of the pump, The detection unit detects an amount of the refrigerant stored in the storage unit as an amount of the recovered refrigerant, an outlet side opening / closing valve that is provided between the outlet side connecting portion and a connecting portion to which the bypass flow path is connected downstream of the outlet side connecting portion and opens and closes the flow path of the refrigerant, The circulation device for a two-phase cooling system according to claim 9, wherein the control unit performs control to close the outlet side opening / closing valve to prevent the refrigerant from flowing out from the outlet side opening / closing valve to the outlet side connection portion based on the detection result by the detection unit.

14. A refrigerant circulating method in a circulation device for a two-phase cooling system that constitutes a two-phase cooling system in which a refrigerant is circulated by connecting a removable evaporator, comprising: a step of circulating the refrigerant through a bypass flow path that circulates the refrigerant without passing through the inlet side connection part and the outlet side connection part, in a state where at least the evaporator is not connected to an inlet side connection part that is connected to an inlet of the refrigerant in the evaporator and an outlet side connection part that is connected to an outlet of the refrigerant; cooling the refrigerant that has flowed through the bypass passage and into the condenser.

15. when recovering the refrigerant from the evaporator, the evaporator is connected to the inlet side connection part and the outlet side connection part, and in a refrigerant recovery state in which an inlet side opening / closing valve provided between a branching portion of the bypass flow path and the inlet side connection part is closed, the refrigerant is circulated through the bypass flow path without passing through the evaporator, and the refrigerant in the evaporator is guided to the condenser; The refrigerant circulating method according to claim 14, further comprising the step of stopping the circulation of the refrigerant and terminating the refrigerant recovery process based on a result of detection of the amount of recovered refrigerant.