Cooling system, cooling method, and control device

Abstract

To reduce power consumption associated with cooling the server device SV. [Solution] The cooling system S according to this embodiment includes a first channel through which cooling water circulates to cool a cooling liquid for cooling a server device SV by exchanging heat with it; a second channel branching off from the first channel and provided with a cooling device 23 for cooling a portion of the cooling water; and a control device 3 that controls the flow rate of cooling water circulating within the first channel without flowing from the first channel to the second channel, and the flow rate of cooling water that flows from the first channel to the second channel, is cooled by the cooling device 23, and then returns to the first channel, according to the temperature of the cooling water flowing within the first channel.

Description

Technical Field

[0001] The present invention relates to a cooling system, a cooling method, and a control device for cooling a server apparatus.

Background Art

[0002] A cooling system is known that cools, by a cooling tower, cooling water whose temperature has risen through heat exchange with a refrigerant (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The temperature of the cooling water that exchanges heat with the cooling liquid for cooling the server apparatus gradually rises due to the heat exchange, so the cooling water needs to be cooled by a cooling device. However, in conventional cooling systems, the cooling water was sent to the cooling device even when the cooling liquid was within the temperature range that allows the server apparatus to perform its functions, which resulted in a problem of high power consumption for transporting the cooling water.

[0005] The present invention has been made in view of these points, and an object thereof is to reduce power consumption associated with cooling a server apparatus.

Means for Solving the Problems

[0006] A cooling system according to a first aspect of the present invention includes: a first channel through which cooling water circulates to cool a cooling liquid for cooling a server device by exchanging heat with the cooling liquid; a second channel branching off from the first channel and provided with a cooling device for cooling a portion of the cooling water; and a control device that controls, according to the temperature of the cooling water flowing in the first channel, the flow rate of the cooling water that circulates within the first channel without flowing from the first channel to the second channel, and the flow rate of the cooling water that flows from the first channel to the second channel, is cooled by the cooling device, and then returns to the first channel.

[0007] The control device may control the flow rate of the cooling water by controlling the flow of the cooling water so that it circulates within the first channel without flowing from the first channel to the second channel when the temperature of the cooling water flowing within the first channel is below a first threshold, and by controlling the flow of the cooling water so that it flows from the first channel to the second channel, and after the cooling water that has flowed into the second channel is cooled by the cooling device, it returns to the first channel when the temperature of the cooling water flowing within the first channel is above a first threshold.

[0008] The second flow path may be provided with a second pump for circulating the cooling water within the second flow path, and the control device may relatively reduce the operating amount of the second pump when the temperature of the cooling water flowing in the first flow path is below a first threshold, and relatively increase the operating amount of the second pump when the temperature of the cooling water flowing in the first flow path is at or above the first threshold.

[0009] The first flow path may be provided with a first valve for controlling the flow rate of the cooling water circulating within the first flow path, and the second flow path may be provided with a second valve for controlling the flow rate of the cooling water flowing from the first flow path to the second flow path, and a third valve for controlling the flow rate of the cooling water flowing from the second flow path to the first flow path, and the control device may control the flow rate of the cooling water by controlling the state of the first valve, the second valve and the third valve.

[0010] The control device may control the opening and closing states of the first valve, the second valve, and the third valve so that when the temperature of the cooling water flowing in the first flow path is below a first threshold, the first valve is open and the second valve and the third valve are closed. The control device may also control the opening and closing states of the first valve, the second valve, and the third valve so that when the temperature of the cooling water flowing in the first flow path is equal to or greater than the first threshold, the first valve is closed and the second valve and the third valve are open.

[0011] The first flow path may be provided with a first pump for circulating the cooling water within the first flow path and a heat exchanger for exchanging heat between the coolant and the cooling water. The control device may control the flow velocity of the cooling water flowing through the first flow path by controlling the operation of the first pump based on the temperature difference, which is the difference between the temperature of the cooling water flowing into the heat exchanger and the temperature of the cooling water flowing out of the heat exchanger.

[0012] The control device may, when the temperature difference is less than a second threshold, control the operation of the first pump so that the flow velocity of the cooling water flowing through the first channel decreases.

[0013] The control device may control the operation of the first pump so that the flow velocity of the cooling water flowing through the first channel increases when the temperature difference is greater than or equal to a third threshold, which is greater than the second threshold.

[0014] The control device may control the flow velocity of the cooling water flowing through the channel based on the temperature of the cooling water flowing through the channel.

[0015] A pump for controlling the flow rate of the cooling water flowing through the first and second flow paths may be provided in at least one of them, and the control device may control the operation of the pump with the minimum power value required to set the flow rate of the cooling water so that the temperature of the cooling water after heat exchange with the coolant is kept within a predetermined range.

[0016] The control device may determine the minimum power value based on the estimated power required by the pump output by a machine learning model, which has been trained using the temperature of the cooling water after it has exchanged heat with the coolant and the power consumption of the pump required to bring the cooling water to that temperature as training data, by inputting the predetermined range of the cooling water temperature into the machine learning model.

[0017] The control device may calculate the power reduction due to circulation by subtracting the power consumption when the cooling water flow is controlled so that the cooling water does not flow from the first channel to the second channel but circulates within the first channel, from the power consumption when the time is predetermined to be controlled so that the cooling water flows into the second channel, is cooled by the cooling device, and then returns to the first channel, and output the calculated power reduction.

[0018] The first channel may be provided with a water storage tank for storing a quantity of cooling water greater than the capacity of the first channel.

[0019] A cooling method according to a second aspect of the present invention is executed by a computer, and includes a step of controlling, according to the temperature of cooling water flowing in a first flow path in which the cooling water that cools a cooling liquid by exchanging heat with the cooling liquid for cooling a server device circulates, the flow rate of the cooling water that circulates in the first flow path without flowing from the first flow path into a second flow path that branches off from the first flow path and is provided with a cooling device for cooling a part of the cooling water, and the flow rate of the cooling water that flows from the first flow path into the second flow path, is cooled by the cooling device, and then returns to the first flow path.

[0020] A control device according to a third aspect of the present invention controls, according to the temperature of cooling water flowing in a first flow path in which the cooling water that cools a cooling liquid by exchanging heat with the cooling liquid for cooling a server device circulates, the flow rate of the cooling water that circulates in the first flow path without flowing from the first flow path into a second flow path that branches off from the first flow path and is provided with a cooling device for cooling a part of the cooling water, and the flow rate of the cooling water that flows from the first flow path into the second flow path, is cooled by the cooling device, and then returns to the first flow path. Effects of the Invention

[0021] According to the present invention, an effect of reducing power consumption associated with cooling the server device is achieved. Brief Description of the Drawings

[0022] [Figure 1] It is a diagram showing an outline of the operation of the cooling system S. [Figure 2] It is a diagram showing an example of the configuration of the control device 3. [Figure 3] It is a diagram showing an example of a state management table. [Figure 4] It is a diagram showing an example of a power recording table. [Figure 5] It is a flowchart showing the flow of processing executed by the control device 3. [Figure 6] It is a flowchart showing the flow of processing for opening the second flow path by a continuous control method. [Figure 7] This figure shows an overview of the operation of the cooling system S in a modified example. [Modes for carrying out the invention]

[0023] [Overview of Information Processing System S] Figure 1 shows an overview of the operation of the cooling system S. The cooling system S is a system that controls the flow rate of the cooling water so that the cooling device 23 can cool a portion of the cooling water when the temperature of the cooling water, which exchanges heat with the cooling liquid used to cool the server device SV, rises.

[0024] The cooling system S includes a first channel through which cooling water circulates, a second channel equipped with a cooling device 23, and a control device 3 that controls the flow rate of the cooling water. The control device 3 controls the flow rate of the cooling water that circulates within the first channel without flowing into the second channel, and the flow rate of the cooling water that flows into the second channel from the first channel, is cooled by the cooling device 23, and then returns to the first channel, according to the temperature of the cooling water flowing in the first channel.

[0025] For example, the control device 3 controls the flow of cooling water so that if the temperature of the cooling water flowing in the first channel is below a threshold, the cooling water does not flow into the second channel but circulates within the first channel. On the other hand, if the temperature of the cooling water flowing in the first channel is above a threshold, the control device 3 controls the flow of cooling water so that the cooling water flows from the first channel to the second channel, and after the cooling water that flows into the second channel is cooled by the cooling device 23, it returns to the first channel. The following describes in detail the processing flow performed by the cooling system S.

[0026] The coolant, whose temperature has risen due to absorbing the heat dissipated by the server devices SV (the number of which is not limited), flows into the secondary side of the cooling distribution unit (CDU13), which functions as a heat exchanger. Meanwhile, the cooling water in the reservoir 14 located in the first flow path is discharged from the reservoir 14 by the power of the first pump 12. The cooling water discharged from the reservoir 14 circulates within the first flow path as the first valve 11 located in the first flow path opens and the second valve 211 and third valve 212 located in the second flow path close. The cooling water circulating within the first flow path flows into the primary side of the CDU13.

[0027] The heat from the heated coolant that flows into the secondary side of the CDU13 is transferred to the coolant that flows into the primary side of the CDU13. In this way, heat exchange occurs between the coolant and the coolant, and the temperature of the coolant circulating in the first flow path gradually rises.

[0028] The control device 3 periodically acquires the temperature of the cooling water circulating in the first flow path. When the acquired temperature of the cooling water is above a threshold (e.g., 45°C), the control device 3 controls the open / closed states of the first valve 11, the second valve 211, and the third valve 212 so that the first valve 11 is closed and the second valve 211 and the third valve 212 are open. The control device 3 also operates the second pump 22 provided in the second flow path.

[0029] As a result, cooling water whose temperature exceeds a threshold flows into the second flow path via the second valve 211. The cooling water that flows into the second flow path is cooled to a first predetermined temperature (for example, 18°C ​​to 35°C) by the influence of the outside air, etc., before flowing into the cooling device 23. The cooling water that has been cooled by the cooling device 23 to a second predetermined temperature (for example, 15°C to 29°C) lower than the first predetermined temperature is then discharged from the cooling device 23 by the power of the second pump 22 and returns to the first flow path via the third valve 212. In this way, the cooling water circulating in the first flow path is cooled.

[0030] When the temperature of the cooling water circulating in the first flow path falls below a threshold, the control device 3 controls the open / closed states of the first valve 11, the second valve 211, and the third valve 212 so that the first valve 11 opens again and the second valve 211 and the third valve 212 close again. As a result, the cooling water circulates in the first flow path again without flowing into the second flow path. In addition, when the temperature of the cooling water circulating in the first flow path falls below a threshold, the control device 3 controls the second pump 22, which is provided in the second flow path, so that it does not operate.

[0031] As explained above, when the temperature of the cooling water flowing in the first channel is below a threshold, the control device 3 controls the flow of the cooling water so that the cooling water does not flow into the second channel but circulates within the first channel, and therefore does not operate the second pump 22 provided in the second channel. As a result, compared to conventional cooling systems that sent cooling water to the cooling device even when the cooling liquid was within a temperature range in which the server device could perform its functions, the cooling system S can reduce the power consumption associated with cooling the server device SV. The configuration of the first channel, the second channel, and the control device 3 of the cooling system S will be described below.

[0032] [Configuration of the first channel] The first channel is a channel through which cooling water circulates to cool the cooling liquid used to cool the server device SV by exchanging heat with it. The shape of the first channel can be any shape as long as the cooling water can circulate through it. The first channel is equipped with a first valve 11, a first pump 12, a CDU 13, and a water storage tank 14. The first valve 11, the first pump 12, the CDU 13, and the water storage tank 14 are capable of sending and receiving data with the control device 3.

[0033] The first valve 11 is a valve for controlling the flow rate of cooling water circulating in the first flow path. The method by which the first valve 11 controls the flow rate of cooling water may be an ON-OFF control method, which controls the flow rate of cooling water by setting the valve opening to "fully open" or "fully closed," or a continuous control method, which controls the flow rate of cooling water by continuously changing the valve opening. When the control method is an ON-OFF control method, the first valve 11 is a valve for switching between a state in which cooling water circulates in the first flow path and a state in which it does not circulate.

[0034] The first pump 12 is a pump for circulating cooling water in the first flow path. The first pump 12 circulates cooling water in the first flow path by, for example, using its power to discharge the cooling water stored in the water storage tank 14 (described later) from the water storage tank 14.

[0035] The CDU13 functions as a heat exchanger to exchange heat between the coolant used to cool the server device SV and the cooling water that cools the coolant. As described above, heat exchange occurs between the coolant and the cooling water when the heat from the coolant flowing into the secondary side of the CDU13 is transferred to the cooling water flowing into the primary side of the CDU13.

[0036] The water storage tank 14 is a tank or the like for storing a larger amount of cooling water than the capacity of the first flow path. The cooling water stored in the water storage tank 14 is discharged from the water storage tank 14 by the power of the first pump 12, then circulates through the first flow path and flows back into the water storage tank 14. The water storage tank 14 is, for example, a sealed water storage tank in which the tank is sealed and the inside of the tank is filled with cooling water. By making the water storage tank 14 a sealed water storage tank, the cooling water does not come into contact with the atmosphere, so oxidation corrosion of piping and equipment can be prevented.

[0037] The higher the outside air temperature, the easier it is for the cooling water to be heated by the outside air. Therefore, the higher the outside air temperature, the lower the temperature inside the water storage tank 14 may be set to make it easier to cool the heated cooling water.

[0038] [Configuration of the second channel] The second flow path is a flow path for cooling the cooling water whose temperature has risen due to absorbing heat from the coolant. The second flow path branches off from the first flow path. As shown in Figure 1, the second flow path branches off, for example, from a position between the CDU 13 and the first valve 11 in the first flow path, and from a position between the first valve 11 and the water tank 14 in the first flow path. The second flow path is equipped with a second valve 211, a third valve 212, a second pump 22, and a cooling device 23. The second valve 211, the third valve 212, the second pump 22, and the cooling device 23 can send and receive data with the control device 3.

[0039] The second valve 211 is a valve for controlling the flow rate of cooling water flowing from the first flow path to the second flow path. The second valve 211 may be controlled using either the ON-OFF control method or the continuous control method described above. When the control method is the ON-OFF control method, the second valve 211 is a valve for switching between a state in which cooling water flows from the first flow path to the second flow path and a state in which it does not flow.

[0040] The third valve 212 is a valve for controlling the flow rate of cooling water flowing from the second flow path to the first flow path. The third valve 212 may use either the ON-OFF control method or the continuous control method described above. When the control method is the ON-OFF control method, the third valve 212 is a valve for switching between a state in which cooling water flows from the second flow path to the first flow path and a state in which it does not flow.

[0041] The second pump 22 is a pump for circulating cooling water into the second flow path. The second pump 22 uses its power to discharge the cooling water cooled by the cooling device 23 (described later) from the cooling device 23, thereby circulating the cooling water into the second flow path.

[0042] The cooling device 23 is a device for cooling a portion of the cooling water. The cooling water that flows into the cooling device 23 is cooled by the cooling device 23 and discharged from the cooling device 23 by the power of the second pump 22. The cooling device 23 is, for example, a cooling tower and is installed in a well-ventilated location (for example, on a rooftop).

[0043] [Configuration of Control Device 3] Figure 2 shows an example of the configuration of the control device 3. The control device 3 comprises a communication unit 31, a storage unit 32, and a control unit 33.

[0044] The communication unit 31 is a communication interface for sending and receiving data with various equipment. The communication unit 31 transmits an operation control signal to the first pump 12 or the second pump 22 to control the amount of pump operation input from the control unit 33. The communication unit 31 also transmits a status control signal to the first valve 11, the second valve 211, or the third valve 212 to control the state of the valves input from the control unit 33.

[0045] The communication unit 31 receives power consumption data indicating the power consumption of the pump from the first pump 12 or the second pump 22. The communication unit 31 receives status data indicating the status of the valves from the first valve 11, the second valve 211, or the third valve 212. The communication unit 31 receives temperature data indicating the temperature of the cooling water flowing through the first flow path from a thermometer installed in the first flow path. The communication unit 31 receives temperature data from a thermometer installed in at least one of the following locations in the first flow path: downstream of the CDU 13 (after heat exchange), inside the tank in the water storage tank 14 (inside the water storage tank), and at the point where the cooling water flows into the water storage tank 14 (water storage tank inlet). The communication unit 31 notifies the control unit 33 of the received power consumption data, status data, and temperature data.

[0046] The memory unit 32 is a storage medium including ROM (Read Only Memory) and RAM (Random Access Memory). The memory unit 32 stores the program executed by the control unit 33. The memory unit 32 also stores a state management table and a power recording table.

[0047] Figure 3 shows an example of a state management table. The state management table is used by the control unit 33 to control the state of the pump and valve according to the temperature of the cooling water flowing through the first channel. In the state management table, the temperature of the cooling water flowing through the first channel, the operating state of the pump, and the state of the valve are associated.

[0048] In the example state management table shown in Figure 3, the pump's operating state is either "operate" or "do not operate." However, the higher the temperature of the cooling water flowing through the first channel, the greater the operating amount of the second pump 22 may be set to improve cooling efficiency. Similarly, in the example state management table shown in Figure 3, the valve's state is either "open" or "closed." However, the higher the temperature of the cooling water flowing through the first channel, the greater the valve opening of the second valve 211 or the third valve 212 may be set to improve cooling efficiency.

[0049] Figure 4 shows an example of a power recording table. The power recording table is the table used to train a machine learning model that the control device 3 uses to predict the minimum power value of the pump. In the power recording table, the date and time of data acquisition, the temperature of the cooling water, the open / closed state of the valve, and the power consumption of the pump are associated. The power consumption of the pump is, for example, the power consumption of the pump from one hour before the date and time of data acquisition to the date and time of data acquisition. In the power recording table shown in Figure 3, the temperature of the cooling water is recorded as the temperature after heat exchange, the temperature inside the water tank, and the temperature at the water tank inlet, but at least one of these temperatures may be recorded, or the average value of these may be recorded.

[0050] The control unit 33 is, for example, a CPU (Central Processing Unit). The control unit 33 executes the information processing program stored in the memory unit 32.

[0051] The control unit 33 acquires the temperature of the cooling water flowing in the first channel. For example, the control unit 33 acquires one of the three cooling water temperatures received by the communication unit 31—the cooling water temperature after heat exchange, the cooling water temperature in the reservoir, and the cooling water temperature at the reservoir inlet—as the temperature of the cooling water flowing in the first channel. The control unit 33 may also acquire the average of the three cooling water temperatures as the temperature of the cooling water flowing in the first channel.

[0052] The control unit 33 controls the flow rate of cooling water that circulates within the first channel without flowing into the second channel (first flow rate), and the flow rate of cooling water that flows from the first channel into the second channel, is cooled by the cooling device 23, and then returns to the first channel (second flow rate), according to the temperature of the cooling water flowing through the first channel. For example, if the temperature of the cooling water flowing through the first channel is below a first threshold, the control unit 33 controls the flow rate of the cooling water so that the second flow rate is less than the first flow rate. On the other hand, for example, if the temperature of the cooling water flowing through the first channel is above a first threshold, the control unit 33 controls the flow rate of the cooling water so that the second flow rate is greater than the second flow rate when the temperature of the cooling water flowing through the first channel is below the first threshold.

[0053] The control unit 33 may relatively reduce the operating amount of the second pump 22 if the temperature of the cooling water flowing in the first channel is below a first threshold. For example, if the temperature of the cooling water flowing in the first channel is below a first threshold, the control unit 33 transmits an operation control signal indicating a first operating amount to the first pump 12 via the communication unit 31, and transmits an operation control signal indicating a second operating amount smaller than the first operating amount to the second pump 22.

[0054] On the other hand, the control unit 33 may relatively increase the operating amount of the second pump 22 when the temperature of the cooling water flowing in the first channel is above a first threshold. For example, when the temperature of the cooling water flowing in the first channel is above a first threshold, the control unit 33 transmits an operation control signal to the second pump 22 indicating a cooling operation amount greater than the second operating amount. The higher the temperature of the cooling water flowing in the first channel, the more the control unit 33 may transmit an operation control signal to the second pump 22 indicating a larger cooling operation amount in order to cool more efficiently. Also, since the cooling water is more easily heated by the outside air when the outside air temperature is high, the control unit 33 may transmit an operation control signal to the second pump 22 indicating a larger cooling operation amount in order to cool more efficiently when the outside air temperature is high.

[0055] The control unit 33 may control the flow rate of the cooling water by controlling the states of the first valve 11, the second valve 211, and the third valve 212. When the temperature of the cooling water flowing through the first flow path is below a first threshold, for example, the valve opening indicated by the state control signal transmitted by the control unit 33 to the first valve 11 is greater than the valve opening indicated by the state control signals transmitted by the control unit 33 to the second valve 211 and the third valve 212. On the other hand, when the temperature of the cooling water flowing through the first flow path is above the first threshold, for example, the valve opening indicated by the state control signals transmitted by the control unit 33 to the second valve 211 and the third valve 212 is greater than the valve opening indicated by the state control signal transmitted by the control unit 33 to the first valve 11. The higher the temperature of the cooling water flowing through the first flow path, the more efficiently the cooling may be performed, and the control unit 33 may transmit state control signals indicating a larger valve opening to the second valve 211 and the third valve 212.

[0056] In this way, when the temperature of the cooling water flowing in the first channel is below a first threshold and cooling is not required, the control unit 33 controls the flow rate of the cooling water so that the second flow rate flowing in the second cooling channel is less than the first flow rate, thereby reducing the power required to flow the cooling water through the second channel. As a result, the power consumption associated with cooling the server device SV can be reduced.

[0057] Up to this point, we have described an example in which the control unit 33 controls the flow rate of cooling water flowing from the first channel to the second channel based on whether or not the temperature of the cooling water flowing in the first channel is below a first threshold. In contrast, as will be explained below, the control unit 33 may control the flow rate of the cooling water by controlling the flow of the cooling water so that, when the temperature of the cooling water flowing in the first channel is below a first threshold, the cooling water does not flow from the first channel to the second channel but circulates within the first channel. On the other hand, the control unit 33 may control the flow rate of the cooling water by controlling the flow of the cooling water so that, when the temperature of the cooling water flowing in the first channel is above a first threshold, the cooling water flows from the first channel to the second channel, and after the cooling water that has flowed into the second channel is cooled by the cooling device 23, it returns to the first channel.

[0058] The control unit 33 may choose not to operate the second pump 22, or may reduce the operating amount of the second pump 22, if the temperature of the cooling water flowing in the first channel is below a first threshold. For example, if the temperature of the cooling water flowing in the first channel is below a first threshold, the control unit 33 refers to the state management table (Figure 3) and obtains an operation control signal indicating "operate" for the first pump 12, and an operation control signal indicating "do not operate" for the second pump 22. For example, the control unit 33 transmits the obtained operation control signals to the first pump 12 and the second pump 22 via the communication unit 31.

[0059] On the other hand, the control unit 33 may operate the second pump 22 or increase the operating amount of the second pump 22 if the temperature of the cooling water flowing in the first channel is above a first threshold. For example, if the temperature of the cooling water flowing in the first channel is above a first threshold, the control unit 33 refers to the state management table (Figure 3) and obtains an operation control signal indicating to "operate" the first pump 12 and the second pump 22. For example, the control unit 33 transmits the obtained operation control signal to the first pump 12 and the second pump 22 via the communication unit 31.

[0060] The control unit 33 may control the open / closed states of the first valve 11, the second valve 211, and the third valve 212 so that when the temperature of the cooling water flowing in the first channel is below a first threshold, the first valve 11 is open and the second valve 211 and the third valve 212 are closed. For example, when the temperature of the cooling water flowing in the first channel is below a first threshold, the control unit 33 refers to the state management table (Figure 3) and obtains a state control signal indicating "open" for the first valve 11 and a state control signal indicating "close" for the second valve 211 and the third valve 212. For example, the control unit 33 transmits the obtained state control signals to the first valve 11, the second valve 211, and the third valve 212 via the communication unit 31.

[0061] On the other hand, the control unit 33 may control the open / closed states of the first valve 11, the second valve 211, and the third valve 212 so that when the temperature of the cooling water flowing in the first channel is above a first threshold, the first valve 11 is closed and the second valve 211 and the third valve 212 are open. For example, when the temperature of the cooling water flowing in the first channel is above a first threshold, the control unit 33 refers to the state management table (Figure 3) and obtains a state control signal indicating "close" for the first valve 11 and a state control signal indicating "open" for the second valve 211 and the third valve 212. For example, the control unit 33 transmits the obtained state control signals to the first valve 11, the second valve 211, and the third valve 212 via the communication unit 31.

[0062] By the way, in order to efficiently cool the server device SV, it is desirable to perform efficient heat exchange in the CDU13, which acts as a heat exchanger. If the difference between the temperature of the cooling water flowing into the CDU13 and the temperature of the cooling water flowing out of the CDU13 is small, the heat exchange in the CDU13 may be insufficient. Therefore, in order to improve the efficiency of heat exchange in the CDU13, the control unit 33 may control the flow velocity of the cooling water flowing through the first channel by controlling the operation of the first pump 12 based on the temperature difference, which is the difference between the temperature of the cooling water flowing into the CDU13 and the temperature of the cooling water flowing out of the CDU13.

[0063] The control unit 33 controls the operation of the first pump 12 so that the flow velocity of the cooling water flowing through the first channel decreases when the temperature difference between the temperature of the cooling water flowing into the CDU 13 and the temperature of the cooling water flowing out of the CDU 13 is less than a second threshold (e.g., 5°C). The control unit 33 may also control the operation of the first pump 12 so that the flow velocity of the cooling water decreases as the temperature difference decreases.

[0064] In this way, the control unit 33 reduces the flow rate of the cooling water when the temperature difference of the cooling water before and after its inflow into the CDU 13 is small, thereby increasing the time the cooling water passes through the CDU 13. As a result, heat exchange between the coolant and the cooling liquid is facilitated in the CDU 13, improving the efficiency of heat exchange, and thus enabling efficient cooling of the server device SV.

[0065] On the other hand, if the temperature difference of the cooling water before and after it flows into the CDU 13 is large, heat exchange is considered to be sufficient, but the flow velocity of the cooling water flowing through the first channel may be too low. If the flow velocity is too low, dirt and other debris may adhere to the inner surface of the pipe through which the cooling water flows, potentially causing pipe corrosion or blockage. Therefore, the control unit 33 may control the operation of the first pump 12 so that the flow velocity of the cooling water flowing through the first channel increases when the temperature difference between the temperature of the cooling water flowing into the CDU 13 and the temperature of the cooling water flowing out of the CDU 13 is greater than or equal to a third threshold (for example, 10°C) which is greater than the second threshold. For example, the control unit 33 controls the operation of the first pump 12 so that the flow velocity of the cooling water increases as the temperature difference increases.

[0066] In this way, the control unit 33 increases the flow velocity of the cooling water when there is a large temperature difference between the cooling water before and after it flows into the CDU 13, making it less likely for dirt and other debris to adhere to the inner surface of the pipe through which the cooling water flows. As a result, the condition of the pipe can be kept in good condition and the flow of the cooling water can be kept normal.

[0067] As described above, the heat exchange function of the CDU13 can be maintained at an appropriate level. However, in order to reduce the power consumption associated with cooling the server device SV, it is important to minimize the amount of operation of the pump that controls the flow rate of the cooling water flowing through the channel. Therefore, the control unit 33 may control the flow rate of the cooling water flowing through the channel based on the temperature of the cooling water flowing through the channel. For example, the control unit 33 controls the operation of the pump with the minimum power value required to set the flow rate of the cooling water so that the temperature of the cooling water after heat exchange with the coolant is kept within a predetermined range.

[0068] The control unit 33, for example, refers to a power recording table (Figure 4) and obtains a first power consumption, which is the power consumption of the pump associated with the temperature of the cooling water after heat exchange that is closest to the lower limit of a specified predetermined range. The control unit 33 also refers to a power recording table (Figure 4) and obtains a second power consumption, which is the power consumption of the pump associated with the temperature of the cooling water after heat exchange that is closest to the upper limit of a specified predetermined range. Then, the control unit 33 determines the minimum power value as the midpoint between the obtained first and second power consumptions, and controls the operation of the pump with the determined minimum power value.

[0069] The control unit 33 may use a machine learning model to determine the minimum power value with greater accuracy. The machine learning model is, for example, a machine learning model that has been trained using the temperature of the cooling water after heat exchange with the coolant and the power consumption of the pump required to bring the cooling water to that temperature as training data. Specifically, the machine learning model is a machine learning model that has been trained using the power record table (Figure 4) as training data.

[0070] The control unit 33 may determine the minimum power value based on the estimated power required by the pump output by the machine learning model after inputting a predetermined range of cooling water temperatures to the machine learning model. The control unit 33 may determine the estimated power required by the machine learning model itself as the minimum power value, or it may determine the minimum power value as a value obtained by multiplying the estimated power required by the machine learning model by a coefficient indicating environmental factors such as ambient temperature or the degree of deterioration of the piping.

[0071] As described above, the control unit 33 performs optimal control to control the operation of the pump with the minimum power value that keeps the temperature of the cooling water after heat exchange within an acceptable range. As a result, the power consumption associated with cooling the server device SV can be minimized.

[0072] There are times when it is desirable to objectively evaluate the power consumption reduction effect of the cooling system S described above. In such cases, the control unit 33 may identify the normal power consumption, which is the power consumption when the time for which the flow of cooling water is controlled so that the cooling water that flows into the second channel returns to the first channel after being cooled by the cooling device 23 is a predetermined time. Normal power can also be said to be the power required by a conventional cooling system that controls the flow of cooling water so that the cooling water flows into the cooling device regardless of the temperature of the cooling water.

[0073] On the other hand, the control unit 33 may identify the circulation power, which is the power consumed when the cooling water flow is controlled for a predetermined period of time so that the cooling water does not flow from the first channel to the second channel but circulates within the first channel. The control unit 33 may also identify, for example, the normal power and circulation power when the cooling water flow is controlled for a predetermined period of time while the temperature of the cooling water after heat exchange by the CDU 13 is within a predetermined range.

[0074] The control unit 33 calculates the power reduction achieved by circulating cooling water in the first channel by subtracting the power used for circulation from the normal power, and outputs the calculated power reduction. This allows administrators and others managing the cooling system S to understand the extent of power reduction achieved by controlling the flow of cooling water so that the cooling water circulates in the first channel when the cooling water temperature is below a first threshold.

[0075] [Processing flow executed by control device 3] Figure 5 is a flowchart showing the processing flow executed by the control device 3. The control unit 33 periodically (for example, once every hour) acquires the temperature of the cooling water circulating in the first channel without flowing into the second channel (S1).

[0076] The control unit 33 determines whether the acquired cooling water temperature is above a first threshold (S2). If the control unit 33 determines that the acquired cooling water temperature is not above the first threshold (S2:NO), it continues to control the flow of the cooling water so that the second flow rate is less than the first flow rate. Then, returning to S1, the control unit 33 acquires the temperature of the cooling water circulating in the first flow path again.

[0077] On the other hand, if the control unit 33 determines that the acquired cooling water temperature is above a first threshold (S2: YES), it opens the second flow path more than it is currently open, thereby controlling the flow of the cooling water so that the second flow rate is greater than the second flow rate when the temperature of the cooling water flowing in the first flow path is below the first threshold (S3). After a first predetermined time has elapsed since opening the second flow path, the control unit 33 acquires the temperature of the cooling water circulating in the first flow path (S4). The first predetermined time is, for example, the time considered necessary to return the cooling water, which has reached a temperature above the first threshold, to a temperature below the first threshold.

[0078] The control unit 33 determines whether the acquired cooling water temperature has fallen below the first threshold (S5). If the control unit 33 determines that the acquired cooling water temperature has not fallen below the first threshold (S5: NO), it acquires the temperature of the cooling water circulating in the first flow path again after a second predetermined time has elapsed. The second predetermined time is a time for additional cooling if cooling is insufficient, and is therefore, for example, shorter than the first predetermined time.

[0079] On the other hand, if the control unit 33 determines that the acquired cooling water temperature has fallen below the first threshold (S5: YES), it controls the flow of the cooling water by closing the second flow path more than it currently is, so that the second flow rate becomes less than the first flow rate (S6).

[0080] The control unit 33 determines whether or not an termination signal has been input to terminate the process (S7). The termination signal is a signal that is input, for example, when the cooling system S is to be temporarily stopped for maintenance of the pump, valves, or piping in the cooling system S.

[0081] If the control unit 33 determines that no termination signal has been received (S7: NO), it returns to S1 and obtains the temperature of the cooling water circulating in the first flow path again. On the other hand, if the control unit 33 determines that a termination signal has been received (S7: YES), it terminates the process.

[0082] Figure 6 is a flowchart showing the process of opening the second channel using a continuous control method. The control unit 33 acquires the temperature of the cooling water circulating in the first channel (S31).

[0083] The control unit 33 identifies the temperature difference between the target temperature of the cooling water circulating in the first flow path, which is stored in the memory unit 32, and the actual temperature of the cooling water acquired in S31, and inputs the identified temperature difference to the PID (Proportional-Integral-Derivative) controller (S32). The PID controller may be provided by the control device 3, or it may be a controller located outside the control device 3.

[0084] The control unit 33 determines the opening degree of each valve based on the calculation results from the PID controller (S33). The control unit 33 transmits a status control signal to each valve indicating the opening degree of each valve determined in S33 (S34). As a result, each valve opens to the opening degree indicated by the status control signal.

[0085] [Effects of Cooling System S] As explained above, the cooling system S controls the flow rate of cooling water that circulates within the first channel without flowing into the second channel, and the flow rate of cooling water that flows from the first channel into the second channel, is cooled by the cooling device 23, and then returns to the first channel, according to the temperature of the cooling water flowing in the first channel. As a result, the power required to flow the cooling water into the second channel can be reduced, thereby reducing the power consumption associated with cooling the server device SV.

[0086] <Variation> In the embodiments described above, an example was given in which the cooling water is cooled by the cooling device 23. In a modified example, the cooling water may be pre-cooled using external water before being cooled by the cooling device 23.

[0087] Figure 7 shows an overview of the operation of the cooling system S in a modified example. In this modified example, external water (e.g., river water, irrigation water, reservoir water, well water, etc.) present outside the first and second flow channels is drawn up by the power of an external pump 41 and flows into the primary side of the heat exchanger (HEX) 24. The external water that flows out from the primary side of the HEX 24 is returned to where the external water was located. Meanwhile, the cooling water that has flowed from the first flow channel to the second flow channel due to the rise in temperature flows into the secondary side of the HEX 24.

[0088] The heat from the heated cooling water that flows into the secondary side of HEX24 is transferred to the external water that flows into the primary side of HEX24. In this way, heat exchange occurs between the cooling water and the external water, and the cooling water flows into the cooling device 23 at a temperature that has dropped to a certain extent. Therefore, in this modified example, compared to the above embodiment which does not use external water, the time it takes for the cooling water temperature to return to below the first threshold is shortened, and the time required to operate the second pump 22 to cool the cooling water that has reached a temperature above the first threshold is also shortened. As a result, the power required to operate the second pump 22 is reduced, and the power consumption associated with cooling the server device SV can be further reduced.

[0089] Furthermore, the heat transferred from the cooling water to the external water can be effectively utilized by transferring that heat to water that requires heating (such as low-temperature hot spring water).

[0090] Furthermore, if the water quality of the second channel cannot be guaranteed, or if the temperature of the cooling water in the second channel is extremely low and condensation in the first channel is anticipated, a heat exchanger may be provided to separate the first and second channels.

[0091] Furthermore, this invention will make it possible to contribute to Goal 9 of the United Nations-led Sustainable Development Goals (SDGs), "Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation."

[0092] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of its gist. For example, all or part of the apparatus can be configured by functionally or physically distributing and integrating in any unit. Furthermore, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effects of the new embodiments resulting from the combinations are combined with the effects of the original embodiments. [Explanation of Symbols]

[0093] 11. Valve No. 1 12. Pump No. 1 13 CDU 14 Water storage tank 211 Second valve 212 Third valve 22 Pump No. 2 23 Cooling device 24 HEX 3. Control device 31 Communications Department 32 Storage section 33 Control Unit 41 External pump S Cooling System SV Server Equipment

Claims

1. A first channel through which cooling water circulates to cool the cooling liquid for cooling the server device by exchanging heat with the cooling liquid, A second flow path is provided, which branches off from the first flow path and is equipped with a cooling device for cooling a portion of the cooling water, A control device that controls, according to the temperature of the cooling water flowing in the first channel, the flow rate of the cooling water that circulates within the first channel without flowing into the second channel from the first channel, and the flow rate of the cooling water that flows from the first channel into the second channel, is cooled by the cooling device, and then returns to the first channel; A cooling system having

2. The control device is If the temperature of the cooling water flowing in the first channel is below a first threshold, the flow rate of the cooling water is controlled by controlling the flow of the cooling water so that it circulates within the first channel without flowing from the first channel to the second channel; if the temperature of the cooling water flowing in the first channel is equal to or greater than the first threshold, the flow rate of the cooling water is controlled by controlling the flow of the cooling water so that it flows from the first channel to the second channel, and after the cooling water that has flowed into the second channel is cooled by the cooling device, it returns to the first channel. The cooling system according to claim 1.

3. The second flow path is provided with a second pump for circulating the cooling water within the second flow path. The control device reduces the operating amount of the second pump relatively when the temperature of the cooling water flowing in the first channel is below a first threshold, and increases the operating amount of the second pump relatively when the temperature of the cooling water flowing in the first channel is equal to or greater than the first threshold. The cooling system according to claim 1.

4. The first flow path is provided with a first valve for controlling the flow rate of the cooling water circulating within the first flow path. The second flow path is provided with a second valve for controlling the flow rate of the cooling water flowing from the first flow path to the second flow path, and a third valve for controlling the flow rate of the cooling water flowing from the second flow path to the first flow path. The control device controls the flow rate of the cooling water by controlling the state of the first valve, the second valve, and the third valve. The cooling system according to claim 1.

5. The control device controls the opening and closing states of the first valve, the second valve, and the third valve so that when the temperature of the cooling water flowing in the first flow path is below a first threshold, the first valve is open and the second valve and the third valve are closed. When the temperature of the cooling water flowing in the first flow path is equal to or greater than the first threshold, the control device controls the opening and closing states of the first valve, the second valve, and the third valve so that the first valve is closed and the second valve and the third valve are open. The cooling system according to claim 4.

6. The first flow path is provided with a first pump for circulating the cooling water within the first flow path, and a heat exchanger for exchanging heat between the cooling liquid and the cooling water. The control device controls the flow velocity of the cooling water flowing through the first channel by controlling the operation of the first pump based on the temperature difference, which is the difference between the temperature of the cooling water flowing into the heat exchanger and the temperature of the cooling water flowing out of the heat exchanger. The cooling system according to claim 1.

7. The control device controls the operation of the first pump so that the flow velocity of the cooling water flowing through the first channel decreases when the temperature difference is less than a second threshold. The cooling system according to claim 6.

8. The control device controls the operation of the first pump so that the flow velocity of the cooling water flowing through the first channel increases when the temperature difference is greater than or equal to a third threshold greater than the second threshold. The cooling system according to claim 6 or 7.

9. The control device controls the flow velocity of the cooling water flowing through the channel based on the temperature of the cooling water flowing through the channel. The cooling system according to claim 1.

10. At least one of the first and second flow paths is provided with a pump that controls the flow velocity of the cooling water flowing through the flow path. The control device controls the operation of the pump with the minimum power value required to maintain the flow rate of the cooling water so that the temperature of the cooling water after heat exchange with the coolant is within a predetermined range. The cooling system according to claim 9.

11. The control device determines the minimum power value based on the predicted power required by the pump output by a machine learning model, which has been trained using the temperature of the cooling water after heat exchange with the coolant and the power consumption of the pump required to bring the cooling water to that temperature as training data, by inputting the predetermined range of the cooling water temperature into the machine learning model. The cooling system according to claim 10.

12. The control device calculates the power reduction due to circulation by subtracting the power consumption when the cooling water flow is controlled so that the cooling water circulates within the first channel without flowing from the first channel to the second channel, from the power consumption when the cooling water flow is controlled so that the cooling water that has flowed into the second channel returns to the first channel after being cooled by the cooling device, for a predetermined period of time, and outputs the calculated power reduction. The cooling system according to claim 1.

13. The first channel is provided with a water storage tank for storing a quantity of cooling water greater than the capacity of the first channel. The cooling system according to claim 1.

14. A computer executes The system includes a step of controlling the flow rate of the cooling water that circulates within the first channel without flowing from the first channel into a second channel, which branches off from the first channel and is equipped with a cooling device for cooling a portion of the cooling water, according to the temperature of the cooling water flowing within the first channel, which cools the cooling liquid by exchanging heat with the cooling liquid for cooling the server device, and the flow rate of the cooling water that flows from the first channel into the second channel, is cooled by the cooling device, and then returns to the first channel. Cooling method.

15. The system controls the flow rate of the cooling water that circulates within a first channel, which is a branch channel of the first channel and is equipped with a cooling device for cooling a portion of the cooling water, without flowing from the first channel into the second channel, and the flow rate of the cooling water that flows from the first channel into the second channel, is cooled by the cooling device, and then returns to the first channel, according to the temperature of the cooling water that circulates within the first channel, and the flow rate of the cooling water that flows from the first channel into the second channel, is cooled by the cooling device, and then returns to the first channel. Control device.

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