Liquid immersion cooling system and control method thereof

Abstract

To provide a liquid immersion cooling system that can handle a large amount of heat generation without increasing the number of liquid immersion heat exchangers.SOLUTION: A liquid immersion cooling system 1 includes: a radiator 11 that cools cooling water by exchanging heat with outside air; a CDU 7 where the cooling water cooled by the radiator 11 is guided and exchanged with coolant; a cooling water circulation system 17 where the cooling water is circulated between the radiator 11 and the CDU 7; a liquid immersion vessel 5 where the coolant cooled by the CDU 7 is guided and the coolant for immersing and cooling an electronic apparatus is stored; and a coolant circulation system 9 for circulating the coolant between the CDU 7 and the liquid immersion vessel 5. A plurality of liquid immersion vessels 5 are connected to one CDU 7, and one coolant transport pump 39 is provided in the coolant circulation system 9 that circulates the coolant between the one CDU 7 and the plurality of liquid immersion vessels 5.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a liquid immersion cooling system and a control method therefor, which are suitable for use in cooling servers in a data center, for example.

Background Art

[0002] Patent Document 1 discloses that in a data center, electronic devices such as servers and storage are immersed in a coolant for cooling. In the liquid immersion cooling system described in this document, one CDU (Coolant Distribution Unit) is connected to one liquid immersion cooling device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When attempting to adopt a liquid immersion cooling system for a data center with a large heat generation amount, since currently available liquid immersion cooling devices are in the 50 kW class, a plurality of liquid immersion cooling devices are required for the liquid immersion cooling system. However, on the premise of the configuration where one CDU is provided for one liquid immersion cooling device as in Patent Document 1, in order to cope with a data center with a large heat generation amount, a CDU is required for each liquid immersion cooling device, resulting in a complicated configuration. In addition, there is a problem that the control for each liquid immersion cooling device becomes complicated.

[0005] [[ID=�9]]In view of such circumstances, the present disclosure has been made, and an object thereof is to provide a liquid immersion cooling system and a control method therefor that can cope with a large heat generation amount without increasing the number of liquid immersion heat exchangers (CDUs).

Means for Solving the Problems

[0006] An immersion cooling system according to one embodiment of the present disclosure comprises a radiator that cools cooling water, an immersion heat exchanger to which the cooling water cooled by the radiator is guided and which exchanges heat with a cooling liquid, a cooling water circulation system in which the cooling water is circulated between the radiator and the immersion heat exchanger, an immersion vessel to which the cooling liquid cooled by the immersion heat exchanger is guided and which stores the cooling liquid for immersing and cooling an electronic device, and a cooling liquid circulation system in which the cooling liquid is circulated between the immersion heat exchanger and the immersion vessel, wherein a plurality of the immersion vessels are connected to one immersion heat exchanger, and a cooling liquid transport pump is provided in the cooling liquid circulation system that circulates the cooling liquid between one immersion heat exchanger and the plurality of immersion vessels.

[0007] A control method for an immersion cooling system according to one embodiment of the present disclosure is a control method for an immersion cooling system comprising: a radiator that cools cooling water; an immersion heat exchanger to which the cooling water cooled by the radiator is guided and which exchanges heat with a cooling liquid; a cooling water circulation system in which the cooling water is circulated between the radiator and the immersion heat exchanger; an immersion vessel to which the cooling liquid cooled by the immersion heat exchanger is guided and which stores the cooling liquid for immersing and cooling an electronic device; and a cooling liquid circulation system in which the cooling liquid is circulated between the immersion heat exchanger and the immersion vessel, wherein a plurality of the immersion vessels are connected to one immersion heat exchanger, and a cooling liquid transport pump is provided in the cooling liquid circulation system that circulates the cooling liquid between one immersion heat exchanger and the plurality of immersion vessels, and the flow rate of the cooling liquid flowing into each of the immersion vessels is adjusted. [Effects of the Invention]

[0008] It is possible to handle large amounts of heat without increasing the number of immersion heat exchangers (CDUs). [Brief explanation of the drawings]

[0009]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments according to the present disclosure will be described with reference to the drawings. FIG. 1 shows a schematic configuration of a liquid immersion cooling system 1 used in a data center. The liquid immersion cooling system 1 includes a liquid immersion container 5, a free cooling device 3, and a CDU (heat exchanger for liquid immersion) 7.

[0011] The liquid immersion container 5 is a bottomed container in which a coolant is stored. As the coolant, a liquid having electrical insulation is used, for example, silicone oil or the like. The coolant is filled to a height such that the entire plurality of substrates (electronic devices) arranged inside the liquid immersion container 5 are immersed. Each substrate is, for example, a substrate constituting a server, and is arranged at a predetermined interval. A plurality of electronic components such as a CPU, a power supply unit, a memory, a storage such as a hard disk or an SSD (Solid State Drive), and a communication unit for constituting the server are mounted on the substrate. These electronic components generate heat during the operation of the server and are cooled by the coolant.

[0012] In the present embodiment, two or more liquid immersion containers 5 are provided in parallel. The number of liquid immersion containers 5 is not limited as long as it is two or more. The amount of heat that can be cooled in each liquid immersion container 5 is, for example, 50 kW. However, the amount of heat that can be cooled is not limited to 50 kW, and typically, it is a capacity that is widely distributed in the market.

[0013] The CDU 7 is an abbreviation for Coolant Distribution Unit (cooling water circulation device), and is a heat exchanger that exchanges heat between the cooling water supplied from the free cooling device 3 and the coolant supplied to each liquid immersion container 5.

[0014] The CDU7 is regarded as one unit and is common to each immersion vessel 5. In this embodiment, there is one CDU7 for all the immersion vessels 5, but it is also possible to use a plurality of sets each combining one CDU7 common to two or more immersion vessels 5.

[0015] The free cooling device 3 includes a radiator 11, a fan 13 provided on the radiator, and a cooling water tank 15 for storing the cooling water flowing out from the radiator 11. The radiator 11, the cooling water tank 15, and the CDU7 are connected by a cooling water circulation system 17. Note that the radiator 11 is not limited to one, and a plurality of radiators may be provided in parallel.

[0016] The radiator 11 is, for example, a fin-tube type heat exchanger, and cools the cooling water by exchanging heat with the outside air. The outside air is supplied to the radiator 11 by the fan 13. The fan 13 has a variable rotation speed and is controlled by a control unit.

[0017] The cooling water flowing out from the radiator 11 is sent to the cooling water tank 15 through the radiator outlet pipe 17a. The cooling water tank 15 is provided with a cooling water supply pipe 17b for supplying cooling water to the CDU7. A cooling water pump 19 is provided in the cooling water supply pipe 17b. The rotation speed of the cooling water pump 19 is controlled by a control unit (not shown) and is variable in flow rate. A cooling water return pipe 17c is connected between the CDU7 and the radiator 11. The cooling water heated by cooling the coolant in the CDU7 is led to the radiator 11 through the cooling water return pipe 17c.

[0018] A coolant circulation system 9 in which the coolant is circulated is provided between the CDU7 and the immersion vessel 5. The coolant circulation system 9 includes an inlet branch header (branch header) 21 provided on the coolant inlet side of each immersion vessel 5 and an outlet branch header 23 provided on the coolant outlet side of each immersion vessel 5.

[0019] A single coolant supply pipe 25 is provided between the inlet branch header 21 and the CDU 7. The coolant cooled by the CDU 7 is guided to the inlet branch header 21 through the coolant supply pipe 25.

[0020] The inlet branch header 21 includes a single inlet header pipe 21a and a plurality of inlet branch pipes 21b branching in parallel from the inlet header pipe 21a. The inlet header pipe 21a is connected to the coolant supply pipe 25.

[0021] Each inlet branch pipe 21b is connected to each immersion vessel 5. A flow rate control valve (flow rate control means) 27 and a flow meter (flow rate control means) 29 are provided in each inlet branch pipe 21b in order from the upstream side of the coolant. Based on the measured value of the flow meter 29, the opening degree of the flow rate control valve 27 is controlled by a control unit (not shown).

[0022] An inlet flow rate control valve 31 is provided in the inlet header pipe 21a upstream of the most upstream inlet branch pipe 21b. The opening degree of the inlet flow rate control valve 31 is controlled by a control unit (not shown) to control the total flow rate of the coolant supplied to each immersion vessel 5. Note that the inlet flow rate control valve 31 can also be omitted.

[0023] The outlet branch header 23 includes a single outlet header pipe 23a and a plurality of outlet branch pipes 23b connected to the outlet header pipe 23a. The outlet header pipe 23a is connected to a single coolant return pipe 33 that returns the coolant to the CDU 7.

[0024] Each outlet branch pipe 23b is connected to each immersion vessel 5. A liquid level control valve (liquid level control means) 35 is provided in each outlet branch pipe 23b. The opening degree of the liquid level control valve 35 is controlled by a control unit (not shown) based on the measured value of the liquid level gauge 37 provided in each immersion vessel 5.

[0025] The coolant return pipe 33 is provided with a coolant transport pump 39 that transports the coolant. The rotation speed of the coolant transport pump 39 is controlled by a control unit (not shown), making the flow rate variable. One coolant transport pump 39 is provided for the coolant circulation system 9. The capacity of the coolant transport pump 39 is set to be equal to or greater than the flow rate required by all of the immersion vessels 5. Therefore, when five immersion vessels 5 are connected, the capacity of the coolant transport pump 39 is set to be equal to or greater than five times the flow rate required by one immersion vessel 5.

[0026] An outlet flow rate control valve 41 is provided in the outlet header pipe 23a downstream of the most downstream outlet branch pipe 23b. The opening of the outlet flow rate control valve 41 is controlled by a control unit (not shown) to control the total flow rate of the coolant returning to the CDU 7. The outlet flow rate control valve 41 may be omitted.

[0027] Overflow pipes 43 are provided between the immersion vessels 5. The overflow pipes 43 are provided above each immersion vessel 5, and their height positions are set based on the maximum allowable liquid level in each immersion vessel 5. The overflow pipes 43 allow the cooling liquid to flow, and when the liquid level of the cooling liquid becomes higher than the connection position of the overflow pipes 43, the cooling liquid flows out toward the other immersion vessels 5.

[0028] 2 shows an example of connection of the overflow pipe 43. The overflow pipe 43 as a flanged connecting pipe is connected to a flange pipe base 5a provided in each immersion vessel 5.

[0029] The control unit is configured to obtain the amount of heat generated by electronic devices such as servers housed in the immersion vessel 5. The amount of heat generated by the electronic devices can be obtained from, for example, a higher-level control system.

[0030] The control unit is composed of, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and a computer-readable storage medium, etc. And a series of processes for realizing various functions are stored in a storage medium or the like in the form of a program as an example. The CPU reads this program into the RAM or the like and executes information processing and arithmetic operations, thereby realizing various functions. Note that the program may be in a form pre-installed in a ROM or other storage medium, in a form provided in a state stored in a computer-readable storage medium, in a form distributed via wired or wireless communication means, etc. A computer-readable storage medium is a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, etc.

[0031] Next, the operation of the liquid immersion cooling system 1 described above will be explained. The cooling water is cooled by the outside air supplied from the fan 13 in the radiator 11 and led to the cooling water tank 15. The cooling water stored in the cooling water tank 15 is led to the CDU 7 by the cooling water pump 19. In the CDU 7, the cooling liquid is cooled by exchanging heat with the cooling liquid. The cooling water heated by cooling the cooling liquid is returned to the radiator 11 and cooled.

[0032] The cooling liquid is circulated through the cooling liquid circulation system 9 by the cooling liquid transport pump 39. The cooling liquid cooled in the CDU 7 is led to the inlet header pipe 21a of the inlet branch header 21 and supplied to each liquid immersion container 5 through each inlet branch pipe 21b.

[0033] The supply flow rate of the cooling liquid is controlled for each liquid immersion container 5 by the control unit using the flow rate adjustment valve 27 and the flow meter 29 so that the required cooling heat quantity can be obtained. That is, the flow rate control for each liquid immersion container 5 is not performed by controlling the rotation speed of the cooling liquid transport pump 39, but is performed by the flow rate adjustment valve 27 provided for each liquid immersion container 5.

[0034] The level of the coolant in each immersion vessel 5 is controlled by the control unit using a level control valve 35 and a level gauge 37. If a malfunction or other problem occurs in the level control and the liquid level exceeds a predetermined value, the coolant is guided to another immersion vessel 5 via an overflow pipe 43.

[0035] When emergency cooling of a specific liquid immersion vessel 5 is required due to an accident or the like, the control is performed as follows. When the control unit receives a signal indicating that emergency cooling is required, it increases the rotation speed of the coolant transport pump 39 to increase the flow rate of the coolant. The coolant transport pump 39 has a capacity greater than the flow rate required by the immersion vessel 5, and therefore can supply a greater flow rate to the specified immersion vessel 5 than at the normal setting. This enables emergency cooling of the specified immersion vessel 5.

[0036] In contrast to this, when dealing with one immersion vessel 5 as in the past, a coolant transport pump with a capacity equivalent to the flow rate required by one immersion vessel 5 is provided. This is because the pump capacity cannot be designed to be excessively large in order to ensure PUE (= (power consumption of IT equipment + power consumption of ancillary facilities) / power consumption of IT equipment). Therefore, with the conventional coolant transport pump, as shown in Figure 3, the flow rate of the coolant is limited as shown in area A, making it impossible to reduce the cooling time.

[0037] In contrast to this, the capacity of the coolant transport pump 39 in this embodiment is larger than the flow rate required by one immersion vessel 5, and has a capacity equal to or greater than the flow rate corresponding to the total number of immersion vessels 5. Therefore, if the coolant is preferentially flowed to the immersion vessels 5 that require emergency cooling, the coolant flow rate can be increased beyond region A in Figure 3, and the cooling time can be reduced as shown in region B in Figure 3.

[0038] The above-described embodiment has the following advantages. Since a plurality of immersion vessels 5 are provided for one CDU 7, the number of CDUs 7 can be reduced. Since one CDU 7 is made to correspond to a plurality of immersion containers 5, it is possible to cope with a large calorific value without increasing the number of CDUs 7. Also, since one coolant transport pump 39 is provided in the coolant circulation system 9 that circulates one CDU 7 and a plurality of immersion containers 5, the number of pumps can be reduced and the control of the coolant flow rate becomes easy.

[0039] The coolant transport pump 39 is set to have a capacity equal to or greater than the flow rate required by all the immersion containers 5 connected to the coolant transport pump 39. Thereby, a coolant flow rate several times that of the conventional one can be ensured, and the cooling rate can be improved.

[0040] Since the coolant transport pump 39 is sized to correspond to the total capacity of the connected immersion containers 5, the coolant transport pump 39 becomes large, and it becomes difficult to adjust the flow rate according to its rotation speed. Therefore, instead of adjusting the flow rate to the immersion containers 5 by the coolant transport pump 39, a flow rate adjustment valve 27 is provided for each immersion container 5 to perform individual flow rate control. Thereby, the cooling amount can be accurately adjusted for each immersion container 5.

[0041] Since a plurality of immersion containers 5 are connected to one CDU 7, if the coolant flow rate supplied to one immersion container 5 becomes excessive due to equipment trouble or control trouble, there is a risk of coolant leakage from the one immersion container 5. Therefore, an overflow pipe 43 is installed between the immersion containers 5. Thereby, even when equipment trouble or control trouble occurs, coolant leakage can be prevented.

[0042] The immersion cooling system 1 and its control method described in each of the above embodiments can be understood as follows, for example.

[0043] The immersion cooling system (1) according to the first aspect of the present disclosure includes a radiator (11) that cools by exchanging heat between cooling water and the outside air, an immersion heat exchanger (7) into which the cooling water cooled by the radiator is introduced to exchange heat with a coolant, a cooling water circulation system (17) in which the cooling water circulates between the radiator and the immersion heat exchanger, an immersion container (5) into which the coolant cooled by the immersion heat exchanger is introduced and in which the coolant for cooling the electronic device by immersion is stored inside, and a coolant circulation system (9) in which the coolant circulates between the immersion heat exchanger and the immersion container. A plurality of the immersion containers are connected to one of the immersion heat exchangers, and one coolant transport pump (39) is provided in the coolant circulation system that circulates one of the immersion heat exchangers and the plurality of immersion containers.

[0044] Since a plurality of immersion containers are provided for one immersion heat exchanger (CDU), the number of CDUs can be reduced. Since one CDU is configured to correspond to a plurality of immersion containers, it is possible to cope with a large heat generation amount without increasing the number of CDUs. In addition, since one coolant transport pump is provided in the coolant circulation system that circulates one CDU and a plurality of immersion containers, the number of pumps can be reduced and the control of the coolant flow rate becomes easy.

[0045] The immersion cooling system according to the second aspect of the present disclosure is the same as the first aspect, wherein the coolant transport pump has a capacity equal to or greater than the flow rate required by all the immersion containers connected to the coolant transport pump.

[0046] In the case of an emergency such as an accident where emergency cooling is required, the cooling rate is slow with a coolant transport pump corresponding to one immersion container, and it is difficult to ensure the required flow rate. This is because the cooling rate of the coolant in the immersion container depends on the circulation flow rate of the coolant. Generally, in a configuration in which one CDU is provided for one conventional immersion cooling device, the pump capacity cannot be designed to be excessive in order to ensure PUE (= (power consumption of IT equipment + power consumption of auxiliary equipment) / power consumption of IT equipment), and there is a limit to the cooling rate. Therefore, the coolant transport pump is sized to have a capacity equal to or greater than the flow rate required by all the liquid immersion containers connected to the coolant transport pump. As a result, a coolant flow rate several times that of the prior art can be ensured, and the cooling rate can be improved.

[0047] In the liquid immersion cooling system according to the third aspect of the present disclosure, in the first aspect or the second aspect, each of the liquid immersion containers is provided with flow rate adjusting means (27, 29) for adjusting the flow rate of the coolant flowing into the liquid immersion container.

[0048] Since the coolant transport pump is sized to correspond to the total capacity of the connected liquid immersion containers, the coolant transport pump becomes larger, and it becomes difficult to adjust the flow rate by its rotational speed. Therefore, flow rate adjusting means is provided for each liquid immersion container, so that the cooling amount can be accurately adjusted by changing the flow rate for each liquid immersion container.

[0049] In the liquid immersion cooling system according to the fourth aspect of the present disclosure, in any one of the first aspect to the third aspect, each of the liquid immersion containers is provided with liquid level control means (35, 37) for controlling the liquid level of the coolant in the liquid immersion container.

[0050] By providing liquid level control means for each liquid immersion container, the liquid level of each liquid immersion container can be appropriately controlled.

[0051] In the liquid immersion cooling system according to the fifth aspect of the present disclosure, in any one of the first aspect to the fourth aspect, an overflow pipe (43) is provided which is connected between the liquid immersion containers and through which the coolant can flow.

[0052] Since a plurality of liquid immersion containers are connected to one CDU, if the coolant flow rate supplied to one liquid immersion container becomes excessive due to equipment trouble or control trouble, there is a risk of coolant leakage from the one liquid immersion container. Therefore, an overflow pipe is installed between the liquid immersion containers. As a result, coolant leakage can be prevented even when equipment trouble or control trouble occurs.

[0053] The immersion cooling system according to a sixth aspect of the present disclosure is the immersion cooling system of any one of the first to fifth aspects, further comprising a branch header (21) that distributes the cooling liquid to the plurality of immersion vessels arranged in parallel.

[0054] The cooling liquid is distributed to each immersion vessel arranged in parallel by a branch header. By using a branch header, the piping can be configured as a single unit, making the device more compact.

[0055] A control method for an immersion cooling system according to a first aspect of the present disclosure is a control method for an immersion cooling system comprising: a radiator that cools cooling water; an immersion heat exchanger to which the cooling water cooled by the radiator is guided and which exchanges heat with a cooling liquid; a cooling water circulation system in which the cooling water is circulated between the radiator and the immersion heat exchanger; an immersion vessel to which the cooling liquid cooled by the immersion heat exchanger is guided and which stores the cooling liquid for immersing and cooling an electronic device; and a cooling liquid circulation system in which the cooling liquid is circulated between the immersion heat exchanger and the immersion vessel, wherein a plurality of the immersion vessels are connected to one immersion heat exchanger, and a cooling liquid transport pump is provided in the cooling liquid circulation system that circulates the cooling liquid between one immersion heat exchanger and the plurality of immersion vessels, and the flow rate of the cooling liquid flowing into each of the immersion vessels is adjusted. [Explanation of symbols]

[0056] 1. Immersion cooling system 3 Free cooling equipment 5. Immersion container 5a flange pipe base 7 CDU (immersion heat exchanger) 9 Coolant circulation system 11 Radiator 13 Fan 15 Cooling water tank 17 Cooling water circulation system 17a Radiator outlet pipe 17b Cooling water supply piping 17c Cooling water return pipe 19 Cooling water pump 21 Inlet branch header (branch header) 21a Inlet header pipe 21b Inlet branch pipe 23 Exit branch header 23a Outlet header pipe 23b Outlet branch pipe 25 Coolant supply pipe 27 Flow control valve (flow control means) 29 Flow meter (flow rate adjustment means) 31 Inlet flow control valve 33 Coolant return pipe 35 Level control valve 37 Liquid level gauge 39 Coolant transport pump 41 Outlet flow control valve 43 Overflow pipe

Claims

1. A radiator for cooling cooling water, A heat exchanger for immersion that is guided by the cooling water cooled by the radiator and exchanges heat with a coolant, A cooling water circulation system in which cooling water is circulated between the radiator and the heat exchanger for immersion, A liquid immersion container into which the coolant cooled by the heat exchanger for immersion is guided and in which the coolant for cooling by immersing electronic devices is stored inside, A coolant circulation system in which coolant is circulated between the heat exchanger for immersion and the liquid immersion container, Comprising, A plurality of the liquid immersion containers are connected to one of the heat exchangers for immersion, A liquid immersion cooling system in which one coolant transport pump is provided in the coolant circulation system that circulates one heat exchanger for immersion and a plurality of the liquid immersion containers.

2. The liquid immersion cooling system according to claim 1, wherein the coolant transport pump has a capacity equal to or greater than the flow rate required by all the liquid immersion containers connected to the coolant transport pump.

3. The liquid immersion cooling system according to claim 2, wherein each of the liquid immersion containers is provided with a flow rate adjusting means for adjusting the flow rate of the coolant flowing into the liquid immersion container.

4. The liquid immersion cooling system according to claim 2, wherein a liquid level control means for controlling the liquid level of the coolant in each of the liquid immersion containers is provided.

5. The liquid immersion cooling system according to claim 1, wherein an overflow pipe is provided that is connected between the liquid immersion containers and allows the coolant to flow therethrough.

6. The liquid immersion cooling system according to claim 1, comprising a branch header for distributing coolant to a plurality of the liquid immersion containers provided in parallel.

7. A radiator for cooling cooling water, A heat exchanger for immersion that is guided by the cooling water cooled by the radiator and exchanges heat with a coolant, A cooling water circulation system in which cooling water is circulated between the radiator and the heat exchanger for immersion, A liquid immersion container into which the coolant cooled by the heat exchanger for immersion is guided and in which the coolant for cooling by immersing electronic devices is stored inside, A coolant circulation system in which coolant is circulated between the heat exchanger for immersion and the liquid immersion container, Comprising, A plurality of the liquid immersion containers are connected to one of the heat exchangers for immersion, A control method for a liquid immersion cooling system in which one coolant transport pump is provided in the coolant circulation system that circulates one heat exchanger for immersion and a plurality of the liquid immersion containers, A control method for a liquid immersion cooling system that adjusts the flow rate of the coolant flowing into each of the liquid immersion containers.

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