JP2016218716A - Two-phase cooling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a two-phase cooling device in which a flow passage is not clogged by a valve element that uses a check valve controlled by a flow of coolant.SOLUTION: A check valve 103 has a pipe structure having the same diameter as that of a liquid pipe 111, and includes: a tapered part 201 tapered toward a side of a liquid separation tank 107; a net 202 arranged on a side of a pump 101; and a valve element 105 arranged inside the pipe. An inner diameter of the tapered part 201 is reduced to a diameter smaller than a diameter of the valve element 105. The tapered part 201 stops a reverse flow by being blocked by the valve element 105. The net 202 is provided to prevent the valve element 105 from being moved into the pump 101 under forward flow. In addition, when a forward flow rate is so high that working fluid of gas reaches the pump 101 beyond the liquid separation tank 107, the net 202 fragments a lump of the working fluid of gas to prevent idle rotation of the pump 101.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a technique for cooling an electronic device with a working fluid.

  There is known a heat pipe in which a working fluid is sealed inside a container such as a vacuum degassed sealed tube. The heat pipe transports heat using the cycle of absorption and release of latent heat due to the phase change of the working fluid when the working fluid evaporated in the evaporation section heated from the outside flows into the condensing part and radiates and condenses. It is. Among these, a loop heat pipe (LHP: Loop Heat Pipe) is composed of an evaporating part that is heated from the outside to evaporate the working fluid, and a condensing part that radiates heat to the outside to condense the vapor, and a steam pipe and a liquid pipe. Are connected so as to form an annular flow path.

  In recent years, the heat generation amount of CPU (Central Processing Unit) used in electronic devices has increased due to the high performance of electronic devices such as servers. Recently, CPUs having a heat generation amount exceeding several hundred W have begun to be used. . The CPU needs to be cooled to a temperature at which it can be stably operated. However, the conventional air cooling system cannot cool the CPU. Water cooling, which uses water with a larger heat capacity than air for cooling, is also used, but cooling performance will be insufficient in the near future when further heat generation of the CPU is considered. Therefore, it is considered to use a loop heat pipe for cooling the CPU.

  CPUs with high heat generation are often used in server machines. Server machines often operate for a long time, and it must be avoided that the CPU becomes hot due to a failure of the cooling device, resulting in malfunction or server failure. In the liquid cooling system, redundancy is provided by duplicating a pump, which is a highly likely drive part as a cause of failure, and stable operation of the cooling system is achieved (Patent Document 3).

Japanese Patent Laid-Open No. 4-245697 Japanese Patent Laid-Open No. 7-324761 JP 2005-228237 A

  In LHP, studies have been made to make the pump redundant by duplicating the pump. For example, an operational flow path for operating the pump and a standby flow path for alternative operation in the event of a failure are provided in parallel. The standby pump is normally stopped. When the pump provided in the operation system flow path is operated, a back flow from the operation system flow path to the standby system flow path occurs, and cooling efficiency decreases. Therefore, for example, a check valve is provided near the pump in the standby system flow path to prevent the backflow of the refrigerant from the operation system to the standby system. If a control mechanism is provided for controlling the check valve, a risk of failure of the mechanism is also assumed. Therefore, a check valve that is automatically controlled by the flow of the refrigerant is preferable.

  However, the check valve controlled by the flow of the refrigerant has a problem that the flow path of the operation system is hindered by the valve body contained in the check valve due to its structure.

  The present invention provides a two-phase cooling device using a check valve that is controlled by the flow of refrigerant without interfering with the flow path of the operation system.

  According to one aspect of the two-phase cooling device disclosed in the present specification, an evaporator that receives heat from the outside, a condenser that releases heat to the outside, and a first pipe that communicates the evaporator and the condenser A first tank having a first connection portion, a second connection portion, and a third connection portion, a second pipe communicating the condenser and the first connection portion of the first tank, and a first pump, A first case having a flow path communicating the first tank and the first pump, a first valve body movable in the flow path of the first case, and the first case in the flow path of the first case. A first narrow portion provided at a position closer to the first tank than the first valve body and having an opening having a diameter smaller than that of the first valve body, the second connection portion of the first tank and the first pump A first check valve that communicates with the second connection portion of the first tank, and a front of the first case. A two-phase circuit comprising: a third pipe communicating with the first check valve at a position farther from the first tank than the first narrow part; and a fourth pipe communicating the first pump and the evaporator. It is a cooling device.

  According to one form of the two-phase cooling device disclosed in the present specification described above, a two-phase cooling device using a check valve that is controlled by the flow of refrigerant without interfering with the flow path of the operation system is provided.

It is a figure explaining one Example of structures, such as a non-return valve with which the two-phase cooling device disclosed in this specification is provided. It is a figure explaining adsorption | suction of the valve body by the adsorption pipe with which the two-phase cooling device disclosed in this specification is provided. It is a figure explaining nonreturn operation by a nonreturn valve with which the two phase cooling device disclosed in this specification is provided. It is a figure explaining the operation principle of adsorption of a valve element by an adsorption pipe with which a two phase cooling device indicated in this specification is provided. It is a figure explaining the operation | movement until the valve body which is preventing the reverse flow with the non-return valve with which the two-phase cooling device disclosed by this specification adsorb | sucks to an adsorption pipe. It is a figure explaining operation | movement until the valve body which adsorb | sucks to the adsorption pipe with which the two-phase cooling device disclosed in this specification is equipped stops reverse flow of a working fluid. It is a figure which shows the Example concerning the removal | desorption of the valve body at the time of a backflow. It is a figure explaining the modification of composition, such as a non-return valve with which the two phase cooling device disclosed in this specification is provided. It is a figure explaining the conventional two-phase cooling device. It is the figure 1 explaining operation | movement of the valve | bulb of the conventional two-phase cooling device. It is the figure 2 explaining operation | movement of the valve | bulb of the conventional two-phase cooling device.

  Before describing the two-phase cooling device of this embodiment, the two-layer cooling device made redundant by providing pumps in parallel flow paths in the comparative embodiment will be described with reference to FIGS.

  FIG. 9 is an overhead view of a two-layer cooling device made redundant by providing pumps in parallel flow paths. The two-phase cooling device installed on the system board 900 forms a closed loop system. The two-phase cooling device includes an evaporator 913, a condenser 909, and a liquid branch tank 907.

  The condenser 909 is connected to the evaporator 913 via the vapor pipe 918. The liquid branch tank 907 is connected to the condenser 909 via the liquid pipe 908.

  The two-phase cooling device of the comparative embodiment further includes check valves 903 and 904 and pumps 901 and 902.

  The pump 901 is connected to the liquid branch tank 907 via a check valve 903, and the pump 902 is connected to the liquid branch tank 907 via a check valve 904.

  The evaporator 913 is connected to pumps 901 and 902 through a liquid return pipe 911.

  A first annular flow path is formed in the order of the evaporator 913, the vapor pipe 918, the condenser 909, the liquid pipe 908, the liquid branch tank 907, the check valve 903, the pump 901, the liquid return pipe 911, and the evaporator 913. A second annular flow path is formed in the order of the evaporator 913, the steam pipe 918, the condenser 909, the liquid pipe 908, the liquid branch tank 907, the check valve 904, the pump 902, the liquid return pipe 911, and the evaporator 913. Pumps 901 and 902 are made redundant by the first annular channel and the second annular channel.

  The working fluid is enclosed in the two-phase cooling device. As the working fluid, for example, a fluorine-based inert liquid such as FLUORINERT (registered trademark) or NOVEC (registered trademark) manufactured by 3M can be used in addition to water and alcohol. The selection of the working fluid is selected according to the boiling point of the working fluid and the amount of heat of the heating element according to the application of the two-phase cooling device.

  The evaporator 913 is disposed in thermal connection with the heat generating component 912. The heat generating component 912 is, for example, a CPU built in the server. Inside the evaporator 913 is provided a wick (not shown) that allows the gaseous working fluid to pass therethrough and sucks the liquid working fluid by capillary action. The liquid working fluid sucked up by the wick is evaporated (vaporized) by the heat obtained from the heat generating component 912 on the surface of the wick. The heat generating component 912 is cooled by applying latent heat to the liquid working fluid.

  The condenser 909 has fins (not shown) thermally connected to the periphery of the flow path through which the working fluid flows. For example, the plate-like plate fins may be provided in a radial pattern around the flow path in parallel with the flow path, or a plurality of plate-shaped plate fins may be arranged along the flow path perpendicular to the flow path. Conceivable. The fins are blown from the cooling fan 910 to cool the working fluid. By cooling the gaseous working fluid, latent heat is released and the working fluid is condensed (liquefied).

  The steam pipe 918 connects the working fluid outlet of the evaporator 913 and the working fluid inlet of the condenser 909, and guides the working fluid heated by the evaporator 913 to the condenser 909. The steam pipe 918 can be formed using a metal such as copper.

  The cooling fan 910 is disposed along the condenser 909. The cooling fan 910 can maintain the temperature of the heat generating component 912 at a constant value by increasing or decreasing the number of the cooling fans 910 according to the amount of heat generated by the heat generating component 912 or by increasing or decreasing the amount of air to be blown. It is.

  The liquid branch tank 907 separates the gaseous working fluid that could not be condensed in the working fluid and leaves the liquid working fluid in the flow path. If the gaseous working fluid is sent to the condenser 909 beyond the cooling capacity of the condenser 909, the gaseous working fluid will not be completely condensed in the condenser 909 and will leave the condenser 909 as a gas. Become. When the gaseous working fluid reaches the pumps 901 and 902, the pumps 901 and 902 run idle, and the working fluid cannot be sent out. Therefore, a liquid branch tank 907 is provided between the pumps 901 and 902 and the condenser 909 so as to prevent the gaseous working fluid from being fed into the pumps 901 and 902, thereby separating the gaseous working fluid. The liquid branch tank 907 can be formed using a metal such as copper.

  The liquid pipe 908 connects the working fluid outlet of the condenser 909 and the working fluid inlet of the liquid branch tank 907, and guides the working fluid cooled by the condenser 909 to the liquid branch tank 907. The liquid tube 908 can be formed using a metal such as copper.

  The pumps 901 and 902 are flat centrifugal pumps. The liquid working fluid condensed in the liquid branch tank 907 is sent to the evaporator 913 by the rotation of the impellers 919 and 920 in the pumps 901 and 902. The flow of the working fluid at this time is called forward flow. On the other hand, the operation of the pumps 901 and 902 is stopped, and the flow of the working fluid from the evaporator 913 side toward the liquid branch tank 907 is referred to as reverse flow. The first annular channel and the second annular channel are provided so that the pump 901 and the pump 902 are in parallel. When the pump 901 operates during the operation of the two-phase cooling device, the operating pump 901 is called an operational system. At this time, the stopped pump 902 is called a standby system.

  The check valves 903 and 904 connect the outlet of the working fluid of the liquid branch tank 907 and the suction ports of the pumps 901 and 902. The check valves 903 and 904 have valve bodies 905 and 906 inside the tubular case, and a net for keeping the valve bodies 905 and 906 in the check valves 903 and 904 on the suction port side of the pumps 901 and 902. 916 and 917 and tapered portions 914 and 915 narrowed to have an opening diameter smaller than the diameter of the valve bodies 905 and 906 on the liquid branch tank 907 side. When the operational pump 901 is operating, the valve body 905 is in contact with the network 916 on the pump 901 side, as shown in FIG. The standby pump 902 does not operate, and the liquid working fluid discharged from the pump 901 flows into the standby pump 902 via the liquid return pipe 911 and flows backward. When the back-flowing liquid working fluid flows directly into the liquid branch tank 907, the liquid working fluid circulates between the liquid branch tank 907 and the pumps 901 and 902, and the working fluid does not reach the entire two-layer cooling device and is cooled. Efficiency is reduced. In the check valve 904, the valve body 906 is brought into close contact with the tapered portion 915, whereby the flow path of the liquid working fluid is blocked and the backflow is stopped.

  The liquid return pipe 911 connects the discharge ports of the pumps 901 and 902 and the inlet of the working fluid of the evaporator 913, and sends the liquid working fluid discharged by the operational pump 901 to the evaporator 913. The liquid return pipe 911 can be formed using a metal such as copper.

  FIG. 10 is an overhead view in which a portion surrounded by a one-dot chain line in FIG. 9 is enlarged, and is a diagram illustrating an operation at the time of forward flow of the two-phase cooling device. The working fluid in which the gas and the liquid are mixed is sent from the liquid pipe 908 to the liquid branch tank 907. The gaseous working fluid is separated in the liquid branch tank 907. The liquid working fluid is sucked up by the operational pump 901. The standby pump 902 stops operating and does not suck up the working fluid from the liquid branch tank 907. The working fluid sucked up by the operational pump 901 tries to flow backward toward the liquid branch tank 907 via the standby pump 902. However, in the check valve 904 of the standby system, the valve body 906 blocks the tapered portion 915 so that such a backflow is prevented.

  FIG. 11 is a sectional view in the height direction along the two-dot chain line A-A ′ in FIG. 10, and is a part of the sectional view of the two-phase cooling device. The liquid branch tank 907 receives a working fluid in which a gas and a liquid are mixed from a liquid pipe 908, separates the gaseous working fluid, and sends the liquid working fluid to the pump 901 side. At this time, since the valve body 905 is separated from the tapered portion 914, the valve does not block the working fluid flow path as a valve. However, the flow path is narrowed by the presence of the valve body 905 on the flow path. Furthermore, since the vibration is generated in the working fluid, the flow path of the working fluid is disturbed, resulting in a decrease in the flow velocity.

  Hereinafter, the two-phase cooling device of the first embodiment will be described with reference to FIGS.

  FIG. 1 is an overhead view of the two-phase cooling device disclosed in the present specification. The two-phase cooling device installed on the system board 100 forms a closed loop system. The two-phase cooling device includes an evaporator 116, a condenser 112, and liquid branch tanks 107 and 108. The condenser 112 is connected to the evaporator 116 via the vapor pipe 117. The liquid branch tanks 107 and 108 are connected to the condenser 112 via the liquid pipe 111.

  The two-phase cooling device of the first embodiment further includes check valves 103 and 104, adsorption tubes 109 and 110, and pumps 101 and 102.

  The pump 101 is connected to the liquid branch tank 107 via the check valve 103, and the pump 102 is connected to the liquid branch tank 108 via the check valve 104.

  The evaporator 116 is connected to the pumps 101 and 102 via the liquid return pipe 114.

  A first annular flow path is formed in the order of the evaporator 116, the vapor pipe 117, the condenser 112, the liquid pipe 111, the liquid branch tank 107, the check valve 103, the pump 101, the liquid return pipe 114, and the evaporator 116. A second annular flow path is formed in the order of the evaporator 116, the vapor pipe 117, the condenser 112, the liquid pipe 111, the liquid branch tank 108, the check valve 104, the pump 102, the liquid return pipe 114, and the evaporator 116. The pumps 101 and 102 are made redundant by the first annular channel and the second annular channel.

  A working fluid is sealed inside the first annular channel and the second annular channel of the two-phase cooling device. As the working fluid, for example, a fluorine-based inert liquid such as FLUORINERT (registered trademark) or NOVEC (registered trademark) manufactured by 3M can be used in addition to water and alcohol. The working fluid is selected according to the use of the two-phase cooling device, the boiling point of the working fluid, the heat quantity of the heating element, and the like.

  The evaporator 116 is disposed in thermal connection with the heat generating component 115. The heat generating component 115 is, for example, a CPU built in the server. Inside the evaporator 116, there is provided a wick (not shown) through which a gaseous working fluid can pass and sucks up the liquid working fluid by capillary action. The liquid working fluid sucked up by the wick is evaporated (vaporized) by heat obtained from the heat generating component 115 on the surface of the wick. The heat generating component 115 is cooled by applying latent heat to the liquid working fluid.

  The condenser 112 has fins (not shown) thermally connected around the flow path through which the working fluid flows. For example, a plurality of plate-like plate fins may be arranged along the flow path. The fins are blown from the cooling fan 113 to cool the working fluid. By cooling the gaseous working fluid, latent heat is released and the working fluid is condensed (liquefied).

  The vapor pipe 117 connects the working fluid outlet of the evaporator 116 and the working fluid inlet of the condenser 112, and guides the working fluid heated by the evaporator 116 to the condenser 112. The steam pipe 117 can be formed using a metal such as copper.

  The cooling fan 113 is disposed along the condenser 112. The cooling fan 113 can maintain the temperature of the heat generating component 115 at a constant value by increasing or decreasing the number of the cooling fans 113 according to the heat generation amount of the heat generating component 115 or by increasing or decreasing the amount of air to be blown. It is.

  The liquid branch tanks 107 and 108 separate the gaseous working fluid that could not be condensed in the condenser 112 from the working fluid, and leave the liquid working fluid in the flow path. When the gaseous working fluid is sent to the condenser 112 beyond the cooling capacity of the condenser 112, the gaseous working fluid is not fully condensed in the condenser 112, leaving the condenser 112 as a gas. Become. When the gaseous working fluid reaches the pumps 101 and 102, the pumps 101 and 102 run idle, and the working fluid cannot be sent out. Accordingly, liquid branch tanks 107 and 108 are provided between the pumps 101 and 102 and the condenser 112 so as to prevent the gaseous working fluid from being fed into the pumps 101 and 102 to separate the gaseous working fluid. The liquid branch tanks 107 and 108 can be formed using a metal such as copper.

  The liquid pipe 111 connects the working fluid outlet of the condenser 112 and the working fluid inlet of the liquid branch tanks 107 and 108, and guides the working fluid cooled by the condenser 112 to the liquid branch tanks 107 and 108. The liquid tube 111 can be formed using a metal such as copper.

  The pumps 101 and 102 are flat centrifugal pumps. The liquid working fluid condensed in the liquid branch tanks 107 and 108 is sent to the evaporator 116 by the rotation of the impellers 118 and 119 in the pumps 101 and 102. The flow of the working fluid at this time is called forward flow. On the other hand, the operation of the pumps 101 and 102 is stopped, and the flow of the working fluid from the evaporator 116 side toward the liquid branch tanks 107 and 108 is referred to as reverse flow. The first annular channel and the second annular channel are provided so that the pump 101 and the pump 102 are in parallel. When the pump 101 operates during the operation of the two-phase cooling device, the operating pump 101 is referred to as an operational system. At this time, the stopped pump 102 is called a standby system.

  The check valve 103 in the first annular path connects the working fluid outlet of the liquid branch tank 107 and the suction port of the pump 101. The check valve 103 has a valve body 105 inside the tubular case, and a net 202 for keeping the valve body 105 in the check valve 103 on the suction port side of the pump 101 and a valve on the liquid branch tank 107 side. A tapered portion 201 narrowed to have an opening diameter smaller than the diameter of the body 105 is provided. The adsorption pipe 109 connects the upper part of the check valve 103 and the upper part of the liquid branch tank 107.

  The check valve 104 in the second annular path connects the outlet of the working fluid in the liquid branch tank 108 and the suction port of the pump 102. The check valve 104 has a valve body 106 inside the tubular case, and a net 302 for keeping the valve body 106 in the check valve 104 on the suction port side of the pump 102 and a valve on the liquid branch tank 108 side. The tapered portion 301 is narrowed so as to have an opening diameter smaller than the diameter of the body 106. The adsorption pipe 110 connects the upper part of the check valve 104 and the upper part of the liquid branch tank 108.

  When the active pump 101 is operating, the standby pump 102 does not operate, and the liquid working fluid discharged by the pump 101 flows into the standby pump 102 via the liquid return pipe 114 and backflows. To do. When the liquid working fluid that has flowed back flows into the liquid branch tank 108 as it is, the liquid working fluid circulates between the liquid branch tanks 107 and 108 and the pumps 101 and 102, and the working fluid is spread over the entire two-layer cooling device. Cooling efficiency decreases. In the check valve 104, the valve body 106 is brought into close contact with the tapered portion 301, whereby the flow path of the liquid working fluid is blocked and the backflow is stopped.

  The liquid return pipe 114 connects the discharge ports of the pumps 101 and 102 and the working fluid inlet of the evaporator 116, and sends the liquid working fluid discharged by the operational pump 101 to the evaporator 116. The liquid return pipe 114 can be formed using a metal such as copper.

  FIG. 2 is a cross-sectional view in the height direction along the alternate long and short dash line A-A ′ in FIG. 1. A working fluid in which a gas and a liquid are mixed is sent from the liquid pipe 111, the gas working liquid is separated by collecting the gaseous working fluid in the liquid branch tank 107, and the liquid working fluid is sent out by the pump 101. The gaseous working fluid accumulated in the upper part of the liquid branch tank 107 is cooled and liquefied by natural heat dissipation in the liquid branch tank 107. Therefore, the gaseous working fluid in the liquid branch tank 107 is in a reduced pressure state. The upper part of the check valve 103 is connected to the upper part of the liquid branch tank 107 by an adsorption pipe 109. The adsorption force due to the reduced pressure state of the gaseous working fluid in the liquid branch tank 107 becomes the force for adsorbing the valve body 105 by the check valve 103 via the adsorption pipe 109.

  The check valve 103 has a pipe structure having the same diameter as the liquid pipe 111, and has a tapered portion 201 having a throttle toward the liquid branch tank 107 side, a net 202 on the pump 101 side, and a valve body 105 inside the pipe. The tapered portion 201 is narrowed to an inner diameter smaller than the diameter of the valve body 105. The tapered portion 201 is stopped by the valve body 105 to stop the backflow. The net 202 is provided to prevent the valve body 105 from being sent to the pump 101 during forward flow. Further, the net 202 has a high forward flow velocity, and when the gaseous working fluid exceeds the liquid branch tank 107 and reaches the pump 101, the mass of the gaseous working fluid is subdivided and To prevent.

  The check valve 103 may have a curved portion 203 that extends downward in a vertical direction at a portion connected to the adsorption pipe 109. Since the curved pipe 203 is connected to the adsorption pipe 109, the gaseous working fluid in the liquid branch tank 107 is cooled, so that the check pipe 103 moves from the check valve 103 toward the liquid branch tank 107. An adsorption force is generated, and the valve body 105 is adsorbed by the bending portion 203. The valve body 105 also reduces the volume on the forward flow path and reduces the degree of inhibition of the forward flow depending on the ratio of the bending portion 203 to the flow path. In addition, as described later, the bending portion 203 exerts a function of drawing the valve body 105 toward the bending portion 203 by affecting the flow of the working fluid around the valve body 105. In order to exhibit such a function, the shape of the bending portion 203 may be hemispherical or mortar-shaped.

  Returning to the description of FIG.

  Using the second annular flow path, that is, the flow path constituted by the condenser 112, the liquid pipe 111, the liquid branch tank 108, the check valve 104, the pump 102, the liquid return pipe 114, the evaporator 116, and the steam pipe 117, The operation of the check valve 104 during backflow will be described. The pump 102 has stopped operating and is not functioning to send liquid working fluid to the evaporator 116. That is, the pump 102 is a standby system and has a redundant configuration for switching to the active system when there is a failure in the operation of the pump 101 that is the active system. When the liquid working fluid sent from the operation system pump 101 flows backward from the confluence of the liquid return pipe 114 toward the standby system pump 102, the flow rate of the working fluid in the entire cooling device is reduced, and the cooling efficiency is increased. Getting worse. In the two-phase cooling device of this embodiment, the check valve 104 prevents the back flow.

  FIG. 3 is a cross-sectional view in the height direction along the alternate long and short dash line B-B ′ in FIG. 1. Since the pump 102 is stopped, there is no flow of liquid working fluid from the condenser 112 to the evaporator 116. Therefore, there is no gas working fluid newly added to the liquid branch tank 108, and the gas-liquid equilibrium state is established in the liquid branch tank 108. In the check valve 104, the working fluid sent from the operation system pump 101 is controlled by the pressure of the liquid working fluid that tends to flow from the confluence of the liquid return pipe 114 toward the standby system pump 102. The body 106 is pressed against the taper portion 301 to check backflow.

  FIG. 4 is a view for explaining the principle of adsorption of the valve body 105 by the adsorption tube 109. When the sectional area of the adsorption pipe 109 is S and the internal pressure of the liquid branch tank 107 is P1, the force F1 applied to the adsorption of the valve body 105 is expressed as F1 = P1 × S. Further, the internal pressure P1 is obtained by using the refrigerant density ρ of the liquid-phase working fluid and the height difference h between the position where the valve body 105 is adsorbed and the gas-liquid interface of the working fluid in the liquid branch tank 107. = Ρgh (g is gravitational acceleration). Therefore, the force F1 applied to the adsorption of the valve body 105 is expressed as shown in Expression (1).

On the other hand, a force that inhibits the adsorption of the valve body 105 is generated by the flow of the working fluid. When this force is defined as lift F2, F2 is expressed by equation (2).

Here, μ is a viscosity coefficient of the working fluid, ν is a kinematic viscosity coefficient of the working fluid, a is a radius of the valve body 105, V is an average velocity of the flow of the working fluid, and k is a velocity gradient.

The valve body 105 is adsorbed to the adsorption pipe 109 when the relationship between the force F1 applied to the adsorption and the lift F2 is F1> F2. Specifically, the refrigerant density ρ = 0.9995646 g / cm ³ of the liquid phase working fluid, the gravitational acceleration 9.8 m / s ² , the height difference h = 15 mm, the cross-sectional area S of the adsorption tube S = 1.0πmm ^2, so it is F1 = 0.460mN. Viscosity coefficient of working fluid μ = 0.00656 μg / cm · s, kinematic viscosity coefficient of working fluid ν = 0.661 cm ² / s, radius of valve body a = 1.5 mm, average velocity of working fluid flow V = 0 .2 m / s, velocity gradient k = 181.8, so F2 = 0.398 mN. Therefore, F1> F2.

  In order for the valve body 105 to be easily adsorbed to the adsorption pipe 109 without being affected by the flow of the liquid working fluid, it is desirable that the valve body 105 is formed in a spherical shape or a substantially spherical shape with resin. It is desirable that the density of the valve body 105 is substantially equal to the refrigerant density ρ of the liquid working fluid so that the valve body 105 does not float or sink with respect to the liquid phase working fluid. The adsorption pipe 109 and other pipes such as the steam pipe 117 and the liquid pipe 111 are preferably formed of a metal such as copper from the viewpoint of shape processing. The liquid branch tank 107 is preferably formed of copper that is easy to process and has high thermal conductivity from the viewpoint of processing the shape and condensing the gaseous working fluid. As shown in Equation (1), the cross-sectional area S of the adsorption pipe 109 affects the adsorption of the valve body 105. Since the shape other than the cross-sectional area of the adsorption tube 109 does not affect the adsorption, the shape of the adsorption tube 109 can be appropriately changed according to the mounting form of the two-phase cooling device. The adsorption pipe 109 according to the embodiment shows a shape bent vertically near the middle of the connection portion between the check valve 103 and the liquid branch tank 107, but the shape is not particularly limited.

  The principle of transition from the state in which the valve body 106 functions as the check valve 104 to the state in which it is adsorbed and fixed to the adsorption pipe 110 will be described with reference to FIGS. 5A to 5D. 5A to 5D are cross-sectional views in the height direction along the alternate long and short dash line B-B ′ in FIG. 1.

  FIG. 5A shows a state where the check valve 104 is blocked by the valve body 106. In this state, the valve body 106 is in close contact with the tapered portion 301 of the check valve 104 to check the working fluid sent from the pump 102 side. At this time, the pump 102 is a standby system.

  FIG. 5B shows a state when the pump 102 is operated and the check valve 104 system is switched from the standby system to the active system. The flow of the working fluid changes due to the operation of the pump 102, and the force that holds the valve body 106 to the tapered portion 301 disappears, and the valve body 106 flows to the pump 102 side. The check valve 104 has a curved portion 303 on the pump 102 side. Due to the influence of the curved portion 303, the valve body 106 does not move straight toward the downstream of the flow, but is guided to the curved portion 303 having a fast flow and a low static pressure according to Bernoulli's law. The movement of the valve body 106 toward the pump 102 is restricted by a net 302 provided in front of the pump 102.

  FIG. 5C is a diagram illustrating a state in which the valve body 106 is close to the bending portion 303. As the valve body 106 approaches the bending portion 303, the gap between the valve body 106 and the upper portion of the bending portion 303 becomes narrower. Since the working fluid of the same density tries to pass through a narrower portion, the flow velocity increases and the working fluid moves further in contact with the curved portion 303. When the valve body 106 comes into contact with the bending portion 303, there is no flow of the gap between the valve body 106 and the bending portion 303, and the function of bringing the valve body 106 close to the bending portion 303 is lost. That is, a force toward the direction away from the bending portion 303 works. When the valve body 106 moves away from the bending portion 303, a force that brings the valve body 106 closer to the bending portion 303 works again, so that the valve body 106 moves so as to contact the bending portion 303. In this way, the valve body 106 performs a minute vertical movement in the vicinity of the bending portion 303. This minute vertical movement disturbs the flow of the liquid working fluid.

  FIG. 5D is a diagram illustrating a state in which the valve body 106 performing a minute vertical movement is adsorbed and fixed to the adsorption tube 110. According to the flow of the working fluid, a gaseous working fluid (steam) is conveyed. In the liquid branch tank 108, the vapor is separated and accumulated above the liquid branch tank 108 by buoyancy. The vapor accumulated in the liquid branch tank 108 is cooled and liquefied by naturally radiating heat in the liquid branch tank 108 and decompressed. By this pressure reduction, an adsorption force F1 is generated in the adsorption tube 110. The valve element 106 is adsorbed and fixed to the adsorption tube 110 by the adsorption force F1. As a result, the vertical motion of the valve body 106 is stopped and the flow of the liquid working fluid is not found, so that the liquid working fluid flows smoothly.

  Next, the operation when the valve body 105 is adsorbed to the adsorption pipe 109 and switched to the standby system when the valve body 105 is adsorbed to the adsorption pipe 109, that is, when the working fluid becomes a reverse flow will be described with reference to FIGS. 6A to 6D are cross-sectional views in the height direction along an alternate long and short dash line A-A ′ in FIG. 1.

  FIG. 6A is a view showing a state where the valve body 105 is adsorbed on the adsorption pipe 109. In this state, there is a new inflow of steam in the liquid branch tank 107, and the decrease in internal pressure due to the liquefaction of the steam continues. The internal pressure of the liquid branch tank 107 at this time is represented as P1.

  FIG. 6B is a diagram illustrating a point in time when the flow of the working fluid is reversed. Since the flow of the working fluid is reversed, new steam does not flow into the liquid branch tank 107, and the decrease in internal pressure stops. On the other hand, evaporation from the liquid phase of the working fluid has occurred, and is expressed by Equation (3).

Here, N is the amount of evaporation per unit, D is the diffusion coefficient of the vapor, the C _s saturated vapor pressure, C _t is the vapor pressure in the liquid branch tank 107, [delta] is a change in the concentration of the vapor layer (boundary film) Is the thickness.

  When the working fluid continues to evaporate from the liquid phase, the internal pressure of the liquid branch tank 107 begins to rise overcoming the reduction in the liquid branch tank 107. The valve body 105 is adsorbed and fixed to the adsorption pipe 109 while the adsorption force F1 applied to the valve body 105 is larger than the lifting force F2 for floating the valve body 105 from the adsorption pipe 109. The internal pressure of the liquid branch tank 107 at this time is represented as P2.

  FIG. 6C is a diagram illustrating a point in time when the internal pressure of the liquid branch tank 107 increases and the adsorption force F1 becomes smaller than the lift force F2. The valve body 105 cannot be adsorbed and fixed to the adsorption pipe 109 and flows along the reverse flow of the working fluid. The internal pressure of the liquid branch tank 107 at this time is represented as P3.

  FIG. 6D is a diagram illustrating a state where the valve body 105 is finally pressed against the tapered portion 201 of the check valve 103 and the backflow of the working fluid is stopped. The internal pressure of the liquid branch tank 107 at this time is represented as P4. P4 is the equilibrium vapor pressure at the liquid temperature of the working fluid. The relationship between the internal pressures P1 to P4 of the liquid branch tank 107 in FIGS. 6A to 6D is as shown in Expression (4).

FIG. 7 is a view showing an embodiment relating to the attachment / detachment of the valve body 105 at the time of backflow. The liquid temperature of the working fluid is 30 ° C., the vapor in the liquid branch tank 107 is also 30 ° C. in equilibrium with the liquid temperature, and the height between the position where the valve body 105 is adsorbed and the gas-liquid interface of the working fluid in the liquid branch tank 107 It is assumed that the valve element 105 is adsorbed under the condition that the direction difference h is 12.7 mm. At this time, the water vapor diffusion coefficient D = 2.88 × 10 ⁻⁵ (m ² / s), the saturated vapor pressure Cs = 4.0 kPa = 7.2 mol / m ³ , the vapor pressure in the liquid branch tank 107 Ct = P1 = Substituting ρgh = 1500 Pa = 0.56 mol / m ³ and the thickness of the boundary film δ = 0.1 mm into the equation (3), N = 1.9 mol / m ² · s is obtained. Assuming that the difference h in the height direction between the position where the valve body 105 is adsorbed and the gas-liquid interface of the working fluid in the liquid branch tank 107 is 11.7 mm, it is assumed that F1 = F2 and the balance is satisfied. Since it changes to 11.7 mm, it is considered that the time required for the 1 mm gas-liquid interface to drop is the time required to escape from the adsorption state. Here, the time required for the 1 mm gas-liquid interface to fall is calculated. The mass of 1 mol of water is 18 g. Mass of water evaporated per unit time area, multiplied by 18 g / mol to N obtained above, a ^{1.9mol / m 2 · s × 18g} / mol = 34.2g / m 2 · s. By approximating the volume from the mass of water, the volume evaporated per unit time area is about 34.2 cm ³ / m ² · s. When the unit is arranged and the height of the gas-liquid interface decreasing per unit time is calculated, it is about 34.2 × 10 ⁻³ mm / s. Therefore, the time for the gas-liquid interface to decrease by 1 mm is 1 mm ÷ 34.2 × 10 ⁻³ mm / s = 29.2 s. That is, about 29 seconds after the moment of switching to the reverse flow, the valve body 105 is released from the adsorption state and flows toward the tapered portion 201 of the check valve 103. It takes several seconds for the working fluid to stop flowing after the pump 101 is stopped. This is because it is not possible to stop the working fluid from continuing to flow by inertia only by stopping the pump 101. The moment when the working fluid delivered from the operational pump 102 goes around the confluence and overcomes the working fluid flowing from the pump 101 by inertia is the moment when the reverse flow is switched. It takes about 1 to 3 seconds from the time when the pump 101 is stopped to this point. It takes about 29 seconds from this point to the detachment of the valve body 105, and the desorbed valve body 105 is flowed by the backflowing working fluid and reaches the tapered portion 201 of the check valve 103. When the valve body 105 arrives at the taper part 201, the backflow working fluid can be checked back. It takes about 1 to 2 seconds until the valve body 105 arrives at the taper portion 201 from the attachment / detachment. Therefore, it takes about 31 to 34 seconds from when the pump 101 stops until it stops.

  Hereinafter, the two-phase cooling device of the second embodiment will be described with reference to FIG.

  FIG. 8 is a diagram showing a second embodiment of the present invention. Note that the two-phase cooling device of the second embodiment is a partial modification of the first embodiment, and the same components as those of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. Is omitted.

  The two-phase cooling device of the second embodiment includes an evaporator 116, a condenser 112, and a liquid branch tank 802. The condenser 112 is connected to the evaporator 116 via the vapor pipe 117. The liquid branch tank 802 is connected to the condenser 112 via the liquid pipe 111. The liquid branch tank 802 is connected to a pump 801, and the pump 801 is connected to the evaporator 116 via a liquid return pipe 114.

  A first annular flow path is formed in the order of the evaporator 116, the vapor pipe 117, the condenser 112, the liquid pipe 111, the liquid branch tank 802, the pump 801, the liquid return pipe 114, and the evaporator 116. Similar to the first embodiment, a second annular flow path that is replaced by a pump (not shown) similar to the pump 801 and a liquid branch tank (not shown) similar to the liquid branch tank 802 is formed. However, it is omitted in the description of the second embodiment. Hereinafter, although the structure of the pump 801 and the liquid branch tank 802 will be described, the pump (not shown) and the liquid branch tank (not shown) in the second annular flow path have the same structure.

  The pump 801 is a flat centrifugal pump. The liquid working fluid condensed in the liquid branch tank 802 is sent to the evaporator 116 by the rotation of the impeller 809 in the pump 801.

  The liquid branch tank 802 has a structure including a check valve 803 therein. The junction between the liquid branch tank 802 and the pump 801 is connected by a check valve 803.

  The check valve 803 has a pipe structure, and has a tapered portion 806 having a throttle toward the connection portion between the liquid branch tank 802 and the liquid pipe 111, a net 807 on the pump 801 side, and a valve body 805 inside the pipe. . The tapered portion 806 is narrowed to an inner diameter smaller than the diameter of the valve body 805. The tapered portion 806 stops backflow by being blocked by the valve body 805. The net 807 is provided to prevent the valve body 805 from being sent to the pump 801 during forward flow. Further, the net 807 prevents the idling of the pump 801 by subdividing the mass of the gas working fluid when the flow speed of the forward flow is high and the gas working fluid reaches the pump 801. Further, the check valve 803 may have a curved portion 808 that extends downward in the vertical direction at a portion connected to the adsorption pipe 804.

  A working fluid in which a gas and a liquid are mixed is sent from the liquid pipe 111, the gas and liquid are separated by collecting the gas working fluid in the upper part in the liquid branch tank 802, and the liquid working fluid is sent out by the pump 801. The gaseous working fluid accumulated in the upper part of the liquid branch tank 802 is cooled and liquefied by natural heat dissipation in the liquid branch tank 802. Therefore, the gaseous working fluid in the liquid branch tank 802 is in a reduced pressure state. An upper part of the check valve 803 is connected to the upper part of the liquid branch tank 802 by an adsorption pipe 804. The adsorption force due to the reduced pressure state of the gas working fluid in the liquid branch tank 802 becomes the force for adsorbing the valve body 805 by the check valve 803 via the adsorption pipe 804.

  By adopting such a configuration, the capacity of the liquid branch tank 802 can be secured even when the space for mounting the two-phase cooling device is limited. By securing a sufficient capacity, the effect of decompression due to the condensation of the gaseous working fluid is increased, and the valve body 805 can be adsorbed to the adsorption pipe 804 with a sufficient adsorption force.

  In addition, this invention is not limited to the structure described in each embodiment mentioned above, A various deformation | transformation is possible in the range which does not deviate from the meaning of this invention.

DESCRIPTION OF SYMBOLS 100 ... System board 101, 102 ... Pump 103, 104 ... Check valve 105, 106 ... Valve body 107, 108 ... Liquid branch tank 109, 110 ... Adsorption pipe 111 ... Liquid pipe 112 ... Condenser 113 ... Cooling fan 114 ... Liquid return pipe 115 ... Heat generating component 116 ... Evaporator 117 ... Steam pipe 118, 119 ... Impeller 201 .... Tapered part 202 ... Net 203 ... Curved part 301 ... Tapered part 302 ... Net 303 ... Curved part 801 ... Pump 802 ... Liquid branch tank 803 ... Non-return Valve 804 ... Adsorption pipe 805 ... Valve body 806 ... Tapered portion 807 ... Net 808 ... Curved portion 809 ... Impeller 900 ... System boards 901, 902 ... Pump 903 904 ... Check valve 90 , 906 ... Valve body 907 ... Liquid branch tank 908 ... Liquid pipe 909 ... Condenser 910 ... Cooling fan 911 ... Liquid return pipe 912 ... Heating component 913 ... Evaporation 914, 915 ... taper 916, 917 ... net 918 ... steam pipe 919, 920 ... impeller

Claims (7)

An evaporator that receives heat from outside and evaporates the working fluid;
A condenser that radiates heat to the outside and condenses the working fluid;
A first pipe connecting the evaporator and the condenser;
A first tank having a first connection, a second connection, and a third connection;
A second pipe connecting the condenser and the first connecting portion of the first tank;
A first pump;
A first case having a flow path connecting the first tank and the first pump; a first valve body movable in the flow path of the first case; and the first case in the flow path of the first case. A first narrow portion provided at a position closer to the first tank than the valve body and having a diameter smaller than that of the first valve body, the second connection portion of the first tank, the first pump, A first check valve for connecting
A third pipe connected to the third connection part of the first tank and connected to the first check valve at a position farther from the first tank than the first narrow part of the first case;
A fourth pipe connecting the first pump and the evaporator;
A two-phase cooling device.   2. The two-phase cooling device according to claim 1, wherein the first check valve has a recess that becomes wider as the distance from the third pipe increases.   The two-phase cooling device according to claim 1 or 2, wherein the recess is mortar-shaped or hemispherical.   The two-phase cooling device according to any one of claims 1 to 3, wherein the first tank has an outer wall having a heat transfer coefficient equal to or lower than a heat transfer coefficient of the second pipe.   The two-phase cooling device according to any one of claims 1 to 4, wherein the first valve body has the same density as the working fluid.   The two-phase cooling device according to any one of claims 1 to 5, wherein the first valve body is spherical or substantially spherical. The two-phase cooling device according to any one of claims 1 to 6, further comprising:
A second tank having a fourth connection portion, a fifth connection portion, and a sixth connection portion;
A fifth pipe connecting the condenser and the fourth connecting portion of the second tank;
A second pump;
A second case having a flow path connecting the second tank and the second pump; a second valve body movable in the flow path of the second case; and the second case in the flow path of the second case. A second narrow portion provided at a position closer to the second tank than the valve body and having an opening smaller in diameter than the second valve body, the fifth connection portion of the second tank, the second pump, A second check valve connecting the
A sixth pipe connected to the sixth connection part of the second tank and connected to the second check valve at a position farther from the second tank than the second narrow part of the second case;
A seventh pipe connecting the second pump and the evaporator;
A two-phase cooling device.