REFRIGERANT CIRCULATION DEVICE

Abstract

A refrigerant circulation device includes a primary flow path, a secondary flow path, a valve, and a controller. The primary flow path allows circulation of a primary refrigerant. The secondary flow path allows circulation of a secondary refrigerant. The valve is provided in the primary flow path or the secondary flow path, and includes an opening degree that is adjustable. The controller is configured or programmed to control operation of the valve and cause the valve to perform a predetermined operation when a period during which the valve is not operated exceeds a threshold value.

Description

1. FIELD OF THE INVENTION

The present disclosure relates to refrigerant circulation devices.

2. BACKGROUND

Cooling control devices have been conventionally known, the cooling control devices being configured to cool a heat source such as a central processing unit (CPU) by transmitting heat received from the heat source to a refrigerant internally circulating.

Conventional cooling control devices each include a flow path of primary cooling water, a flow path of secondary cooling water as a refrigerant for cooling a heat source, and a heat exchanger for performing heat exchange between the primary cooling water and the secondary cooling water.

Techniques have been conventionally known and used for controlling secondary cooling water to cause the secondary cooling water to have a predetermined temperature by adjusting an opening degree of a valve that changes a flow rate of primary cooling water to a heat exchanger.

Unfortunately, the conventional cooling control device may cause the valve not to operate normally when the valve provided in the flow path is not operated for a predetermined period of time, due to a deposit in which ionized metal, impurities, or the like are deposited, the deposit adhering to the valve.

Thus, a refrigerant circulation device is expected to overcome the above-described problems and cause a deposit to be less likely to adhere to a valve provided in a flow path.

SUMMARY

A refrigerant circulation device according to an example embodiment of the present disclosure includes a primary flow path, a secondary flow path, a valve, and a controller. The primary flow path allows circulation of a primary refrigerant. The secondary flow path allows circulation of a secondary refrigerant. The valve is provided in the primary flow path or the secondary flow path, and includes an opening degree that is adjustable. The controller is configured or programmed to control operation of the valve and cause the valve to perform a predetermined operation when a period during which the valve is not operated exceeds a threshold value.

The above and other elements, features, steps, characteristics and advantages of the present disclosure will become more apparent from the following detailed description of the example embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a schematic configuration of a CDU according to a first example embodiment of the present disclosure.

FIG. 2 is a flowchart illustrating a procedure of operation processing of a first valve, the operation processing being performed by the CDU according to the first example embodiment.

FIG. 3 is a flowchart illustrating a procedure of operation processing of a second valve, the operation processing being performed by the CDU according to the first example embodiment.

FIG. 4 is a diagram illustrating a schematic configuration of a CDU according to a second example embodiment of the present disclosure.

DETAILED DESCRIPTION

Hereinafter, refrigerant circulation devices according to example embodiments of the present disclosure will be described in detail with reference to the drawings. The example embodiments does not limit the present disclosure. Each example embodiment can be appropriately combined within a range in which processing contents do not contradict each other. Each example embodiment below includes an identical part that is denoted by an identical reference numeral, and duplicated description will not be described.

Each of the drawings to be referred to below defines an X axis direction, a Y axis direction, and a Z axis direction orthogonal to one another, and may show an orthogonal coordinate system, in which the Z axis direction is a vertically upward direction, for easy understanding of the description.

First, a schematic configuration of a CDU 100 according to a first example embodiment will be described with reference to FIG. 1. FIG. 1 is a diagram illustrating a schematic configuration of the CDU 100 according to the first example embodiment. The term, “CDU”, is an abbreviation for “coolant distribution unit”. The CDU 100 is an example of a refrigerant circulation device.

The CDU 100 controls a flow rate, temperature, water quality, or a distribution destination of a refrigerant supplied from an equipment side. The CDU 100 sucks a primary refrigerant to the inside of the CDU 100 and pumps the primary refrigerant to the outside of the CDU 100. The CDU 100 sucks a secondary refrigerant to the inside of the CDU 100 and pumps the secondary refrigerant to the outside of the CDU 100. The CDU 100 is not provided inside with a pump on a primary refrigerant side, so that the primary refrigerant is sucked and pumped in the CDU 100 using an external pump.

The CDU 100 performs heat exchange between the primary refrigerant and the secondary refrigerant. For example, refrigerant liquids such as antifreeze and pure water can be used as the primary refrigerant and the secondary refrigerant. Examples of the antifreeze usable as a refrigerant include an ethylene glycol aqueous solution and a propylene glycol aqueous solution. The primary refrigerant and the secondary refrigerant may be identical in type to each other or different in type from each other. At least one of the primary refrigerant and the secondary refrigerant may be a gas refrigerant.

As illustrated in FIG. 1, the CDU 100 includes a primary flow path 10, a secondary flow path 20, a tank 30, and a heat exchanger 40, which are housed in a housing 100a.

The primary flow path 10 allows circulation of the primary refrigerant. The primary flow path 10 connects a primary inflow port 10a and a primary outflow port 10b provided in the housing 100a. The primary inflow port 10a and the primary outflow port 10b are open to a side surface of the housing 100a, the side surface facing a positive X-axis direction. The housing 100a includes the side surface facing the positive X-axis direction, the side surface being a back surface of the housing 100a, for example.

The primary flow path 10 includes a main flow path 11 and a bypass flow path 12. That is, a primary medium having flowed in from the primary inflow port 10a passes through the main flow path 11 and partially passes through the bypass flow path 12 to flow out from the primary outflow port 10b.

The main flow path 11 connects the primary inflow port 10a and the primary outflow port 10b via the heat exchanger 40. The main flow path 11 includes a temperature sensor 111, a pressure sensor 112, a first valve 113 (referred to also simply as a “valve 113”), the heat exchanger 40, a temperature sensor 114, and a flow rate sensor 115, in order from upstream.

The temperature sensor 111 measures liquid temperature of the primary refrigerant upstream of the primary flow path 10, specifically, upstream from the heat exchanger 40 in the primary flow path 10. The pressure sensor 112 is provided downstream from the temperature sensor 111 in the main flow path 11 to measure pressure of the primary refrigerant in the primary flow path 10.

The first valve 113 is provided on the upstream side of the heat exchanger 40 in the main flow path 11. Specifically, the first valve 113 is connected to the main flow path 11 at a position not only downstream from a branch position of the bypass flow path 12 in the main flow path 11 but also upstream of the heat exchanger 40. The first valve 113 controls a flow rate of the primary refrigerant in the main flow path 11. The first valve 113 is an electromagnetic two-way valve, for example. The first valve 113 has an opening degree that is adjustable using a controller 50 described later.

The heat exchanger 40 is provided downstream from the first valve 113 in the main flow path 11. The heat exchanger 40 will be described later.

The bypass flow path 12 branches from the main flow path 11 at a position not only upstream from the heat exchanger 40 but also downstream from the pressure sensor 112.

The bypass flow path 12 is provided with a second valve 121 (referred to also simply as a “valve 121”). The second valve 121 is connected to the bypass flow path 12 and controls a flow rate of the primary refrigerant in the bypass flow path 12. The second valve 121 is an electromagnetic two-way valve, for example. The second valve 121 has an opening degree that is adjustable using a controller 50 described later.

Controlling an opening degree of each of the first valve 113 of the main flow path 11 and the second valve 121 of the bypass flow path 12 enables adjustment of an inflow of the primary refrigerant into the heat exchanger 40. That is, heat exchange performance between the primary refrigerant and the secondary refrigerant in the heat exchanger 40 can be adjusted. Closing the first valve 113 and the second valve 121 enables stopping the circulation of the primary refrigerant. Thus, when the primary refrigerant leaks, the valve disposed in the flow path leading to a place of the leak is closed to stop a flow of the primary refrigerant and prevent the leak of the primary refrigerant from spreading.

The bypass flow path 12 merges with the main flow path 11 at a position downstream from the heat exchanger 40.

The temperature sensor 114 is provided at a junction of the main flow path 11 and the bypass flow path 12. The temperature sensor 114 measures liquid temperature of the primary refrigerant downstream of the primary flow path 10, specifically, downstream from the heat exchanger 40 in the primary flow path 10.

The flow rate sensor 115 is provided downstream from the temperature sensor 114 in the main flow path 11 to measure a flow rate of the primary refrigerant flowing through the primary flow path 10. The flow rate sensor 115 is provided downstream from the junction of the main flow path 11 and the bypass flow path 12, and thus can measure a flow rate of the entire primary flow path 10.

The secondary flow path 20 allows circulation of the secondary refrigerant. The secondary flow path 20 connects a secondary inflow port 20a and a secondary outflow port 20b provided in the housing 100a. The secondary inflow port 20a and the secondary outflow port 20b are open to a side surface of the housing 100a, the side surface facing the positive X-axis direction.

The secondary flow path 20 includes a main flow path 21, a supply flow path 22, a first flow path 23, and a second flow path 24. That is, a secondary medium having flowed in from the secondary inflow port 20a passes through the main flow path 21 and passes through the first flow path 23 or the second flow path 24 to flow out from the secondary outflow port 20b.

The main flow path 21 includes a temperature sensor 211, the heat exchanger 40, a pressure sensor 214, a temperature sensor 215, and a flow rate sensor 216, in order from upstream.

The temperature sensor 211 measures liquid temperature of the secondary refrigerant upstream of the secondary flow path 20, specifically, upstream from the heat exchanger 40 in the secondary flow path 20. The heat exchanger 40 is provided downstream from the temperature sensor 211 in the main flow path 11. The heat exchanger 40 will be described later.

The supply flow path 22 merges with the main flow path 21 at a position not only downstream from the heat exchanger 40 in main flow path 21 but also upstream from a branch position of the first flow path 23 and the second flow path 24. The supply flow path 22 is connected to the tank 30. The tank 30 will be described later.

The main flow path 21 branches into the first flow path 23 and the second flow path 24 at a position downstream from a branch position from the supply flow path 22.

The first flow path 23 includes a pump 231 and a check valve 232 in order from upstream.

The pump 231 pumps the secondary refrigerant to downstream of the first flow path 23. The check valve 232 is provided downstream from the pump 231 in the first flow path 23 to prevent backflow of the secondary refrigerant flowing through the secondary flow path 20.

The second flow path 24 includes a pump 241 and a check valve 242 in order from upstream.

The pump 241 pumps the secondary refrigerant to downstream of the second flow path 24. The check valve 242 is provided downstream from the pump 241 in the branch second flow path 24 to prevent backflow of the secondary refrigerant flowing through the secondary flow path 20.

The first flow path 23 and the second flow path 24 merge at their downstream ends, i.e., at a position not only downstream from the check valve 232 but also downstream from the check valve 242, and are connected to the main flow path 21.

The pressure sensor 214 is provided at a junction of the first flow path 23 and the second flow path 24 to measure pressure of the secondary refrigerant in the secondary flow path 20. The pressure sensor 214 measures pressure in a state where the secondary refrigerant pumped from the pump 231 and that pumped from the pump 241 merge with each other.

The temperature sensor 215 measures liquid temperature of the secondary refrigerant downstream of the secondary flow path 20, specifically, downstream from the heat exchanger 40 in the secondary flow path 20. The flow rate sensor 216 is provided downstream from the temperature sensor 215 in the main flow path 21 to measure a flow rate of the secondary refrigerant flowing through the main flow path 21.

The tank 30 stores a refrigerant used as the secondary refrigerant. The tank 30 is connected to the supply flow path 22 of the secondary flow path 20. The tank 30 can supply the refrigerant to the secondary flow path 20. When the secondary refrigerant circulating in the secondary flow path 20 decreases, the refrigerant in the tank 30 is supplied to the secondary flow path 20. Consequently, a flow rate of the secondary refrigerant circulating in the secondary flow path 20 can be kept constant. The tank 30 includes a liquid level sensor (not illustrated), an inspection window through which a liquid level of the tank 30 can be visually checked, an air vent valve that releases accumulated gas, and a water injection hole through which water can be injected when the secondary refrigerant decreases.

The heat exchanger 40 is connected to the primary flow path 10 and the secondary flow path 20. The primary refrigerant and the secondary refrigerant flow into the heat exchanger 40 and flow out of the heat exchanger 40. The heat exchanger 40 exchanges heat between the primary refrigerant and the secondary refrigerant inside the heat exchanger 40. The heat exchange system of the heat exchanger 40 is a plate system, for example.

The CDU 100 further includes the controller 50. The controller 50 is configured or programmed to process computer-executable commands that cause the CDU 100 to perform various steps described in example embodiments of the present disclosure. The controller 50 can be configured or programmed to control each element of the CDU 100 to perform the various steps described herein. For example, the controller 50 is configured or programmed to control operation of the valve 113 or the valve 121. In the first example embodiment, a portion or an entirety of the controller 50 may be included in the CDU 100.

The controller 50 may be configured or programmed to include a processor, a storage, and a communication interface. The controller 50 may include a computer, for example. The processor can be configured or programmed to perform various control operations by reading out a program from the storage and executing the program read out. This program may be stored in the storage in advance, or may be acquired using a medium when necessary. The program acquired is stored in the storage, and is read out from the storage and executed by the processor. The medium may be various kinds of computer-readable storage medium, or may be a communications line connected to a communications interface. The processor may be a central processing unit (CPU). The storage may include a random access memory (RAM), a read only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof. The communication interface may communicate with the CDU 100 through a communication line such as a local area network (LAN).

FIG. 1 illustrates an example of the configuration of the CDU 100, and members other than the members illustrated in FIG. 1 may be further provided. For example, the CDU 100 may include a touch screen. The touch screen is provided on a side surface of the housing 100a, the side surface facing an X-axis negative direction, to display an operating state of the system and a measurement value of each sensor. The CDU 100 may also include a power supply unit. The power supply unit supplies power to the pump 231, the pump 241, the valve 113, the valve 121, and the like described later. When power is supplied from the outside, the CDU 100 may not include the power supply unit.

The CDU 100 may further include another sensor in addition to the sensors illustrated in FIG. 1. Examples of the other sensor include a flow rate sensor that measures a flow rate of the primary refrigerant or the secondary refrigerant in the primary flow path 10 or the secondary flow path 20, a water quality sensor that measures conductivity, turbidity, ion index, pH, or the like of the primary refrigerant or the secondary refrigerant, a humidity sensor that measures humidity inside the CDU 100, and a leak sensor that detects liquid leakage inside the CDU 100.

Examples of sensors may be disposed in the primary flow path 10 or the secondary flow path 20, or may be disposed outside the primary flow path 10 or the secondary flow path 20. Examples of sensors disposed in the primary flow path 10 or the secondary flow path 20 include the pressure sensors 112 and 214, and the flow rate sensors 115 and 216. Examples of sensors disposed outside the primary flow path 10 or the secondary flow path 20 include a humidity sensor and a leak sensor. The term, “inside of the primary flow path 10”, described in the present disclosure includes not only a place where the primary refrigerant circulates but also a space fluidly connected to the primary flow path 10.

The sensor can transmit a measurement result to the controller 50 by being connected to the controller 50. The sensor is also connected to the controller 50 in a hot swappable manner, and thus can be inserted and removed even when the CDU 100 is in operation. For this reason, when an abnormality occurs in the sensor, maintenance of the sensor can be performed without stopping the CDU 100, and thus influence on a server can be suppressed. Disposing a plurality of sensors identical in type close to each other enables continuous measurement in a close range even when one sensor is removed.

The CDU 100 configured as described above may cause the valve 113 or the valve 121 not to operate normally when the valve 113 or the valve 121 is not operated for a predetermined period of time, due to a deposit in which ionized metal, impurities, or the like are deposited, the deposit adhering to the valve 113 or the valve 121. Even when an abnormality occurs in the valve 113 and the valve 121, the abnormality may not be detected. When the valve 113 or the valve 121 is not operated for a long time, the valve may be stuck and fail.

Thus, the CDU 100 according to the first example embodiment causes the valve 113 or the valve 121 to perform a predetermined operation when the valve 113 or the valve 121 has not operated for a predetermined period of time. Consequently, a deposit are less likely to accumulate in the valve 113 or the valve 121. Even when the valve 113 or the valve 121 fails, the failure can be found early. Specifically, when the valve 113 or the valve 121 does not work due to a failure and the failure is found after the secondary refrigerant has a temperature out of a threshold value range, temperature adjustment of the secondary refrigerant is required. In contrast, the CDU 100 according to the first example embodiment enables a failure to be found before such temperature adjustment becomes necessary. Hereinafter, specific operation processing of the CDU 100 will be described with reference to FIG. 2.

FIG. 2 is a flowchart illustrating a procedure of operation processing of the first valve 113, the operation processing being performed by the CDU 100 according to the first example embodiment.

First, the controller 50 determines whether a period during which the first valve 113 is not operated exceeds a threshold value (step S101). The threshold value is three days, for example.

When determining that the period during which the first valve 113 is not operated exceeds the threshold value (Yes in step S101), the controller 50 acquires liquid temperature of the secondary refrigerant from the temperature sensors 211 and 215 in the secondary flow path 20 (step S102). For example, the controller 50 may determine an average value of measurement values acquired from the temperature sensors 211 and 215 as the liquid temperature of the secondary refrigerant.

Subsequently, the controller 50 determines whether the liquid temperature of the secondary refrigerant is within a predetermined temperature range (step S103). When the liquid temperature of the secondary refrigerant is within the predetermined temperature range (Yes in step S103), the controller 50 advances the processing to step S104. In contrast, when the liquid temperature of the secondary refrigerant is not within the predetermined temperature range (No in step S103), the controller 50 ends the processing of this flow.

Subsequently, the controller 50 acquires information on an opening degree of the first valve 113 from the first valve 113. The controller 50 also acquires a measurement value from the pressure sensor 214 (step S104).

Subsequently, the controller 50 determines whether the measurement value of the pressure sensor 214 has greatly changed (step S105). For example, when the change in the measurement value of the pressure sensor 214 is larger than a fluctuation range of the pressure sensor 214 corresponding to an opening degree of the first valve 113, the fluctuation range being measured in advance, the controller 50 determines that the measurement value of the pressure sensor 214 has greatly changed.

When the measurement value of the pressure sensor 214 has greatly changed (Yes in step S105), the controller 50 advances the processing to step S106. In contrast, when the measurement value of the pressure sensor 214 has not changed greatly (No in step S105), the controller 50 ends the processing of this flow.

Subsequently, the controller 50 causes the second valve 121 to open (step S106). The term, “open”, here includes not only a fully open state but also an open state in which an opening degree is equal to or greater than a predetermined degree. That is, the controller 50 increases the opening degree of the second valve 121 to a predetermined degree or more. When the second valve 121 has already opened, the controller 50 may skip this processing.

Subsequently, the controller 50 causes the first valve 113 to perform the predetermined operation (step S107). For example, the controller 50 may increase the opening degree of the first valve 113. The controller 50 may lower the opening degree of the first valve 113. The controller 50 may cause the first valve 113 to perform an operation of increasing and lowering the opening degree. The controller 50 may also cause the first valve 113 to perform the operation of increasing and lowering the opening degree multiple times. Here, the opening degree of the first valve 113 is desirably equal before and after the predetermined operation. Consequently, change in circulation of the secondary refrigerant before and after the predetermined operation of the first valve 113 can be suppressed.

Here, when the first valve 113 has not performed the predetermined operation, for example, when the opening degree of the first valve 113 has not changed or when an error is output from the first valve 113, the controller 50 may notify the error using a display unit (not illustrated) such as a touch screen.

Subsequently, the controller 50 checks operation of the sensor (step S108). Specifically, the controller 50 checks operation of the flow rate sensors 115 and 216, or of the pressure sensors 112 and 214. For example, the controller 50 checks whether a measurement value of the flow rate sensor 115 has changed while causing the first valve 113 to perform the predetermined operation. When the measurement value of the flow rate sensor 115 has changed, the controller 50 determines that the flow rate sensor 115 normally operates. In contrast, when the measurement value of the flow rate sensor 115 has not changed, the controller 50 may determine that the flow rate sensor does not operate normally, and may notify an error using the display unit (not illustrated) such as a touch screen.

The controller 50 may similarly check the operation of the flow rate sensor 216, or of the pressure sensor 112 or 214. The controller 50 may also similarly check operation of other sensors such as the temperature sensors 111, 114, 211, and 215.

As described above, the controller 50 of the CDU 100 according to the first example embodiment causes the valve 113 to perform the predetermined operation when the period during which the valve 113 is not operated exceeds the threshold value.

Causing the valve 113 to operate as described above at regular intervals causes a deposit to be less likely to adhere to the valve 113.

While one of the first valve 113 and the second valve 121 performs the predetermined operation, the controller 50 may cause the other of the first valve 113 and the second valve 121 to open.

Consequently, an increase in internal pressure in the primary flow path 10 due to the operation of the first valve 113 or the second valve 121 can be suppressed.

Here, the opening degree of the other of the first valve 113 and the second valve 121 is desirably equal before and after the predetermined operation of the one of the first valve 113 and the second valve 121. Consequently, change in circulation of the secondary refrigerant before and after the predetermined operation of the first valve 113 or the second valve 121 can be suppressed.

When not only the period during which the valve 113 is not operated exceeds the threshold value, but also the liquid temperature of the secondary refrigerant acquired from each of the temperature sensor 211 and the temperature sensor 215 is within the predetermined temperature range, the controller 50 may cause the valve 113 to perform the predetermined operation. In other words, even when the period during which the valve 113 is not operated exceeds the threshold value, the controller 50 may not cause the valve 113 to perform the predetermined operation when the liquid temperature of the secondary refrigerant is out of the predetermined temperature range.

When the liquid temperature of the secondary refrigerant is out of the predetermined temperature range, the liquid temperature of the secondary refrigerant needs to be adjusted. Thus, the predetermined operation is not performed in this case. Consequently, cooling performance of the CDU 100 can be maintained. Additionally, dew condensation in the primary flow path 10 and the secondary flow path 20 can be suppressed.

The controller 50 may determine whether to cause the predetermined operation to be performed in accordance with a measurement value of the pressure sensor 112 and an opening degree of the valve 113.

When a deposit adheres to the valve 113, pressure in the primary flow path 10 tends to increase. Thus, determining whether to cause the valve 113 to operate based on the measurement value of the pressure sensor 112 in the primary flow path 10 enables suppressing progress of adhesion of the deposit to the valve 113.

The controller 50 also includes the storage that may include a plurality of threshold values for determining a period in which the valve 113 is not operated. The controller 50 may select one threshold value from among the plurality of threshold values based on a measurement value of the pressure sensor 112 to determine whether the period during which the valve 113 is not operated exceeds the one threshold value. For example, when the measurement value of the pressure sensor 112 is large, a small threshold value may be selected from among the plurality of threshold values.

Consequently, when the internal pressure of the primary flow path 10 tends to increase, the operation processing can be performed in a shorter period than a usual period, and thus the progress of the adhesion of the deposit to the valve 113 can be suppressed.

The controller 50 may check whether the sensor normally operates based on change in a measurement value of the sensor (e.g., the flow rate sensor 115 or 216, or the pressure sensor 112 or 214) during the predetermined operation.

Consequently, the controller 50 can check whether the sensor normally operates while suppressing adhesion of a deposit to the valve 113.

Operation processing as in the flowchart of FIG. 2 may be performed on the second valve 121. FIG. 3 is a flowchart illustrating a procedure of operation processing of the second valve 121, the operation processing being performed by the CDU 100 according to the first example embodiment. The flowchart is similar to the flowchart of FIG. 2 except for difference in a target that is caused to operate by the controller 50, so that detailed description of each step will not be described.

First, the controller 50 determines whether a period during which the second valve 121 is not operated exceeds a threshold value (step S201). When determining that the period during which the second valve 121 is not operated exceeds the threshold value (Yes in step S201), the controller 50 advances the processing to step S202.

Subsequently, the controller 50 performs processing in steps S202 and S203, the processing being similar to that in steps S102 and S103 in FIG. 2.

Subsequently, the controller 50 acquires information on the opening degree of the second valve 121 from the second valve 121. The controller 50 also acquires a measurement value from the pressure sensor 214 (step S204).

Subsequently, the controller 50 determines whether the opening degree of the second valve 121 and the measurement value of the pressure sensor 214 are each within a threshold value range (step S205). When each of the opening degree of the second valve 121 and the measurement value of the pressure sensor 214 is within the threshold value range (Yes in step S205), the controller 50 advances the processing to step S206. In contrast, when each of the opening degree of the second valve 121 and the measurement value of the pressure sensor 214 is not within the threshold value range (No in step S205), the controller 50 ends the processing of this flow.

Subsequently, the controller 50 causes the first valve 113 to open (step S206) and causes the second valve 121 to perform a predetermined operation (step S207).

Subsequently, the controller 50 checks operation of the sensor (step S208).

The processing of this flow may be performed at timing shifted from that in the operation processing of the first valve 113 illustrated in FIG. 2. Consequently, a flow of the primary refrigerant is less likely to be affected, and increase in the internal pressure in the primary flow path 10 can be suppressed, in comparison with when the operation processing of the first valve 113 and the operation processing of the second valve 121 are simultaneously performed.

Although an example has been here described in which the operation processing is performed on the first valve 113 and the second valve 121 provided in the primary flow path 10, a valve to be subjected to the operation processing is not limited the valves. For example, the operation processing may be performed on a valve (not illustrated) provided in the secondary flow path 20. Additionally, valves are not limited in position and number to those in an example of FIG. 1.

The controller 50 may adjust the opening degree of the valve 113 or the valve 121 in accordance with a measurement value of the pressure sensor 214. This configuration enables suppressing the increase in the internal pressure in the primary flow path 10.

The controller 50 may also be configured or programmed to perform the processing illustrated in the flowchart of FIG. 2 after causing the valve 113 or the valve 121 to close. The internal pressure of the primary flow path 10 increases by causing the valve 113 and the valve 121 to close, so that a deposit on the valve 113 or the valve 121 is more easily removed when the operation processing is performed.

The primary flow path 10 may be provided with a plurality of pressure sensors. Similarly, the secondary flow path 20 may be provided with a plurality of pressure sensors.

In step S105 of FIG. 2, the controller 50 may further use a measurement value of the flow rate sensor 115 to determine whether change in the measurement value of the pressure sensor 214 is large.

As described above, the controller 50 of the CDU 100 according to the first example embodiment causes the valve 113 to perform the predetermined operation when the period during which the valve 113 is not operated exceeds the threshold value. Causing the valve 113 to operate as described above at regular intervals causes a deposit to be less likely to adhere to the valve 113.

Although an example in which two two-way valves of the valve 113 and the valve 121 are provided in the primary flow path 10 has been described in the first example embodiment, a type of valve is not limited thereto. Instead of the two two-way valves, one three-way valve may be provided in the primary flow path 10. FIG. 4 is a diagram illustrating a schematic configuration of a CDU 100 according to a second example embodiment.

A valve 19 is provided at a branch point between a main flow path 11 and a bypass flow path 12 to control a flow rate of a primary refrigerant in the main flow path 11 and the bypass flow path 12. The valve 19 is an electromagnetic three-way valve, for example. The valve 19 has an opening degree that is adjustable using a controller 50.

The valve 19 may include a first valve that controls a flow rate of the primary refrigerant in the main flow path 11 and a second valve that controls a flow rate of the primary refrigerant in the bypass flow path 12. The controller 50 can adjust an inflow of the primary refrigerant into the heat exchanger 40 by controlling an opening degree of each of the first valve and the second valve. That is, heat exchange performance between the primary refrigerant and the secondary refrigerant in the heat exchanger 40 can be adjusted.

A configuration in which one three-way valve is provided in the primary flow path 10 as described above enables reduction not only in number of valves to be used, but also in cost.

The CDU 100 of the present disclosure includes the plurality of pumps 231 and 241 (see FIG. 1), so that only one of the plurality of pumps 231 and 241 can be operated while the other thereof is caused to stand by. When the pump standing by is not operated for a predetermined period of time, operation processing can be performed as in the first valve 113 and the second valve 121.

Deposits may accumulate on a member and in a flow path tube, the member and the passage tube being disposed in the primary flow path 10 or the secondary flow path 20, and may cause malfunction or a decrease in area of allowing the primary refrigerant or the secondary refrigerant to circulate.

Specifically, when a sensor is disposed in the flow path tube, function of the sensor may be limited due to accumulation of the deposits around the sensor. When the deposits accumulate in a place (a bent part or a part having a narrow flow path) having high flow path resistance in the primary flow path 10 or the secondary flow path 20, the flow path resistance may further increase to affect circulation of the primary refrigerant or the secondary refrigerant.

For this concern, opening and closing of the valve 113 or the valve 121 is repeated to enable generating a turbulent flow near the valve 113 or the valve 121 when the valve 113 or the valve 121 is disposed in the primary flow path 10 as illustrated in FIG. 1, so that the deposits having adhered can be peeled off from an adhered position by the turbulent flow to circulate the deposits in the flow path. When a mesh-like filter is further provided in the primary flow path 10, the deposits can be stopped by the filter, and thus can be prevented from adhering to another member again. The filter can be removed from the inside of the primary flow path 10, so that the filter can be removed for maintenance when the filter has clogged. Opening and closing speed of the valve 113 or the valve 121 for generating the turbulent flow is higher than opening and closing speed of the valve 113 or the valve 121 for adjusting the amount of the refrigerant flowing through the primary flow path 10.

The turbulent flow is generated to cause the deposits to flow at timing at which the operation processing of the valve 113 or the valve 121 described above in the first example embodiment can be performed together. The turbulent flow also can be generated at timing when influence of the deposits is detected from a measurement value (e.g., a flow rate measured by the flow rate sensor 115 or 216, and the like) of the sensor, rotation speed of the pump 231 or 241, or the like.

Increasing the turbulent flow or making the turbulent flow into an impact flow enables deposits having a large volume or deposits strongly adhered to flow out. Examples of a method for increasing the turbulent flow or making the turbulent flow into an impact flow include increasing the opening and closing speed of the valve 113 or the valve 121, increasing the number of times of opening and closing, and increasing a flow rate of the primary refrigerant circulating. This process may be performed on a valve provided in the secondary flow path 20.

As illustrated in FIG. 1, when the pump 231 or the pump 241 is disposed in the primary flow path 10, the turbulent flow can be generated by adjusting rotation of the pump 231 or the pump 241. The turbulent flow can be generated by repeating rotation, stopping, or reverse rotation of the pump 231 or the pump 241.

Change in the rotational speed of the pump 231 or the pump 241 for generating the turbulent flow is larger than change in the rotational speed of the pump 231 or the pump 241 for adjusting the amount of the refrigerant flowing through the primary flow path 10 and the secondary flow path 20. Examples of increasing the turbulent flow or making the turbulent flow into an impact flow include an increase in the rotation speed and a sudden stop of the pump 231 or the pump 241, and an increase in the amount of the refrigerant circulating.

A member disposed in the CDU 100 and connected to the controller 50 can notify the controller 50 when an abnormality occurs. When each member records its operating state, maintenance frequency, or the like, a period until maintenance is required can be self-diagnosed. Although examples of the member capable of self-diagnosis include the valves 113 and 121, and the pumps 231 and 241, even a member not described can have a self-diagnosis function.

The valve 113 or the valve 121 has a function of self-diagnosing time when the maintenance is required from operation detection during the operation processing of the valve 113 or the valve 121 described in the first example embodiment, the number of times of opening and closing from the previous maintenance, the cumulative amount of change, the continuous operating time, or the like.

The pump 231 or the pump 241 has a function of self-diagnosing time when the maintenance is required from operation detection during operation processing of the pump 231 or the pump 241 described above, the cumulative number of rotations from the previous maintenance, frequency of change in rotation speed, the number of times of starting and stopping, or the like. As an index of a period until the maintenance, a rate of change can be used, the change being acquired by comparing rotation speeds at an identical duty ratio stored in the storage. Additionally, comparing operation sound during normal operation with operation sound during abnormal operation enables determining whether the pump 231 or the pump 241 is normal.

When a detachable coupler (rapid fluid coupling) is provided in the primary flow path 10 and the secondary flow path 20 in the CDU 100, a specific part can be disconnected from the primary flow path 10 and the secondary flow path 20 by disconnecting the coupler. For example, when the coupler is provided not only upstream of the inflow port of the heat exchanger 40 but also downstream of the outflow port thereof, the heat exchanger 40 can be separated from the primary flow path 10 or the secondary flow path 20. When scales (water scales) attach or adhere, the scales being formed by deposition of inorganic salts, such as silica, calcium, and magnesium, dissolved in the refrigerant flowing in the primary flow path 10 or the secondary flow path 20, the heat exchanger 40 is disconnected by disconnecting the coupler. Then, a coupler for external connection connected to a cleaning flow path is attached, so that the scales can be cleaned by feeding a strong acid or the like from the cleaning flow path.

Besides the strong acid, an alkaline liquid or a liquid having other properties can be used for the cleaning. Besides using a liquid, cleaning by collision of gas and cleaning using powder or pellet are available.

As a form other than separation from the flow path using the coupler, the cleaning flow path can be provided by providing a valve (such as a three-way valve or a combination of two two-way valves) capable of switching a flow path.

The three-way valve can be provided not only upstream of the inflow port of the heat exchanger 40 but also downstream of the outflow port thereof, and the controller 50 can separate a flow path for circulation from the cleaning flow path by operating the three-way valve.

For example, when the refrigerant is circulated, the controller 50 causes the three-way valve to open its valve for communicating with the flow path for circulation, and to close its valve for communicating with the cleaning flow path. In contrast, when cleaning is performed, the controller 50 causes the valve for communicating with the cleaning flow path to open and the valve for communicating with the flow path for circulation to close. When an acidic or alkaline liquid is fed, influence on circulation of the refrigerant can be suppressed by neutralizing the inside of the heat exchanger 40 after the cleaning.

Although the heat exchanger 40 of the CDU 100 has been described in the above description, a member other than the heat exchanger 40 may be applied. Even the member other than the CDU 100 (such as closed water-cooling including a radiator, a water-cooling head, and the like) can have a similar configuration.

The present techniques can be configured as follows.

(1) A refrigerant circulation device including a primary flow path that allows circulation of a primary refrigerant, a secondary flow path that allows circulation of a secondary refrigerant, a valve that is provided in the primary flow path or the secondary flow path, and includes an opening degree that is adjustable, and a controller configured or programmed to control operation of the valve and cause the valve to perform a predetermined operation when a period during which the valve is not operated exceeds a threshold value.

(2) The refrigerant circulation device described in Item (1), further including a heat exchanger connected to the primary flow path and the secondary flow path, the primary flow path including a main flow path that connects an inflow port and an outflow port that are for the primary refrigerant via the heat exchanger, and a bypass flow path that branches from the main flow path at a position upstream of the heat exchanger and merges with the main flow path at a position downstream of the heat exchanger, and the valve including a first valve connected to the main flow path at a position not only downstream of a branch position of the bypass flow path in the main flow path but also upstream of the heat exchanger, and a second valve connected to the bypass flow path, in which while one of the first valve and the second valve performs the predetermined operation, the controller is configured or programmed to cause the other of the first valve or the second valve to open.

(3) The refrigerant circulation device according to Item (1) or (2), further including a temperature sensor provided in the secondary flow path, in which the controller is configured or programmed to cause the valve to perform the predetermined operation when not only the period during which the valve is not operated exceeds the threshold value but also when a liquid temperature of the secondary refrigerant acquired from the temperature sensor is within a predetermined temperature range.

(4) The refrigerant circulation device according to any one of Items (1) to (3), further including a pressure sensor provided in the primary flow path, in which the controller is configured or programmed to determine whether to cause the predetermined operation to be performed in accordance with a measurement value of the pressure sensor and an opening degree of the valve.

(5) The refrigerant circulation device according to any one of Items (1) to (4), further including a sensor provided in the primary flow path or the secondary flow path, in which the controller is configured or programmed to check whether the sensor normally operates based on change in measurement values of the sensor during the predetermined operation.

It should be understood that the example embodiments disclosed herein are illustrative in all respects and not restrictive. In fact, the above example embodiments can be implemented in a variety of forms. Various forms of elimination, replacement, and modification may be applied to the above example embodiments without departing from the spirit of the scope of claims appended.

Features of the above-described example embodiments and the modifications thereof may be combined appropriately as long as no conflict arises.

While example embodiments of the present disclosure have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present disclosure. The scope of the present disclosure, therefore, is to be determined solely by the following claims.

Claims

1. A refrigerant circulation device comprising: a primary flow path that allows circulation of a primary refrigerant;a secondary flow path that allows circulation of a secondary refrigerant;a valve that is provided in the primary flow path or the secondary flow path, and includes an opening degree that is adjustable; anda controller configured or programmed to control operation of the valve and cause the valve to perform a predetermined operation when a period during which the valve is not operated exceeds a threshold value.

2. The refrigerant circulation device according to claim 1, further comprising: a heat exchanger connected to the primary flow path and the secondary flow path;the primary flow path including: a main flow path that connects an inflow port and an outflow port that are for the primary refrigerant via the heat exchanger; anda bypass flow path that branches from the main flow path at a position upstream of the heat exchanger and merges with the main flow path at a position downstream of the heat exchanger; andthe valve including: a first valve connected to the main flow path at a position not only downstream of a branch position of the bypass flow path in the main flow path but also upstream of the heat exchanger; anda second valve connected to the bypass flow path; whereinwhile one of the first valve and the second valve performs the predetermined operation, the controller is configured or programmed to cause the other of the first valve or the second valve to open.

3. The refrigerant circulation device according to claim 1, further comprising: a temperature sensor provided in the secondary flow path; whereinthe controller is configured or programmed to cause the valve to perform the predetermined operation when not only the period during which the valve is not operated exceeds the threshold value but also when a liquid temperature of the secondary refrigerant acquired from the temperature sensor is within a predetermined temperature range.

4. The refrigerant circulation device according to claim 1, further comprising: a pressure sensor provided in the primary flow path; whereinthe controller is configured or programmed to determine whether to cause the predetermined operation to be performed in accordance with a measurement value of the pressure sensor and an opening degree of the valve.

5. The refrigerant circulation device according to claim 1, further comprising: a sensor provided in the primary flow path or the secondary flow path; whereinthe controller is configured or programmed to check whether the sensor normally operates based on change in measurement values of the sensor during the predetermined operation.