JP2007143865A - Cooling system, magnetic resonance diagnostic equipment, and cooling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling system which does not cool a secondary-side coolant more than necessary, magnetic resonance diagnostic equipment, and a cooling method. <P>SOLUTION: When the liquid temperature of a liquid coolant B is lower than a predetermined temperature, in a primary-side cooling system, a liquid coolant A cooled by a cooler 41 is heated only by a gradient coil part 13 without being heated by a heat exchanger 46; and in a secondary-side cooling system, a second channel including the heat exchanger 46, through which the liquid coolant B passes, is closed by a channel switching part 48. When the liquid temperature of the liquid coolant B is as high as/higher than the predetermined temperature, in the primary-side cooling system, the liquid coolant A cooled by the cooler 41 is heated by the gradient coil part 13 and the heat exchanger 46; in the secondary-side cooling system, the second channel including the heat exchanger 46 is opened by the channel switching part 48; and in the heat exchanger 46, the liquid coolant B, which is cooled by the liquid coolant A, cools an RF driving part 22 and/or a gradient drive part 23. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cooling system having two or more heat sources, a magnetic resonance diagnostic apparatus, and a cooling method.

In recent years, magnetic resonance imaging has been used to measure the density distribution and relaxation time distribution of nuclear spins at a desired examination site in a subject using nuclear magnetic resonance, and display a cross section of the subject from the measured data ( Magnetic resonance diagnostic apparatuses (MR apparatuses) that perform MRI) and the like are widely used.
In the MR apparatus, various coils for irradiating a subject with a strong magnetic field are used. Of these, the gradient coil is generally cooled by water cooling.
On the other hand, air cooling of a fan or the like is generally used for computer cooling such as signal processing and image processing of the MR apparatus.

However, air cooling has problems such as loud noise and low cooling capacity. As a method for solving this problem, there is a method of cooling both the cooling of the gradient coil and the cooling of the electronic equipment.
That is, the cooling of the gradient coil is the primary cooling, the cooling of the electronic equipment is the secondary cooling, the refrigerant cooled by the cooler flows on the primary side, and the refrigerant on the secondary side is the heat exchanger and the primary side It is cooled by the refrigerant.

  Here, generally, the primary side (gradient coil side) is stronger than the secondary side (electronic equipment side), and is cooled to, for example, 20 ° C. That is, in the above-described method, since the temperature of the primary side refrigerant is lower than that of the secondary side, the secondary side cooling is always performed by the primary side refrigerant in the heat exchanger. Since it is not necessary to cool the secondary side refrigerant to the same temperature as that of the primary side, in this case, cooling is performed wastefully.

  An object of the present invention is to provide a cooling system, a magnetic resonance diagnostic apparatus, and a cooling method that do not cool the refrigerant on the secondary side more than necessary.

  In order to solve the above-described problem, a cooling system according to a first aspect of the present invention is a cooling system that cools a first heat source and a second heat source, a cooler that cools a first refrigerant, A pump, a second pump, a flow path switching unit that switches a flow path of the second refrigerant, and a heat exchanger that exchanges heat of the first refrigerant and heat of the second refrigerant. And the first pump, the first heat source, the heat exchanger, and the cooler are connected, and the first pump includes the first heat source, the heat exchanger, The first refrigerant is circulated through the cooler, the second pump, the second heat source, and the flow path switching unit are connected to form a first flow path, A flow path switching unit and the heat exchanger are connected to form a second flow path, and the flow path switching unit includes the second refrigerant. When the temperature is lower than a predetermined temperature, the second flow path is closed, and when the second refrigerant is equal to or higher than a predetermined temperature, the second flow path is opened. The second refrigerant is circulated through the second flow path and the second flow path, and in the heat exchanger, the temperature of the first refrigerant is lower than the temperature of the second refrigerant.

  Preferably, the flow path switching unit is installed at a branch point between the first flow path and the second flow path.

  Preferably, the first heat source is a gradient coil of a magnetic resonance diagnostic apparatus.

  Preferably, the second heat source is an RF coil driving unit and / or a gradient coil driving unit of a magnetic resonance diagnostic apparatus.

  Preferably, the predetermined temperature, which is a reference for switching the flow channel, can be arbitrarily set.

  Preferably, the first refrigerant and the second refrigerant are liquids.

  According to a second aspect of the present invention, there is provided a magnetic resonance diagnostic apparatus comprising: a scan unit that performs a scan for measuring a magnetic resonance signal from the subject after applying a high-frequency magnetic field to the subject in a static magnetic field; An operation console unit that generates an image of the subject based on the obtained magnetic resonance signal, and a cooling unit that cools the RF coil driving unit and / or the gradient coil driving unit that drives the RF coil and the gradient coil unit The cooling section includes a cooler that cools the first refrigerant, a first pump, a second pump, and a flow path that switches a flow path of the second refrigerant. A switching unit; and a heat exchanger that exchanges heat of the first refrigerant and heat of the second refrigerant, the first pump, the first heat source, and the heat exchanger; , The cooler is connected, and the first pump Circulates the first refrigerant through the first heat source, the heat exchanger, and the cooler, and the second pump, the second heat source, and the flow path switching unit are Connected to form a first flow path, and the flow path switching unit and the heat exchanger are connected to form a second flow path, and the flow path switching unit includes the second refrigerant Is less than a predetermined temperature, the second flow path is closed, and when the second refrigerant is equal to or higher than a predetermined temperature, the second flow path is opened, and the second pump The second refrigerant is circulated through the first flow path and the second flow path, and in the heat exchanger, the temperature of the first refrigerant is lower than the temperature of the second refrigerant.

  The cooling method of the invention of the third aspect includes a cooler that cools the first refrigerant, a first pump, a second pump, a flow path switching unit that switches a flow path of the second refrigerant, A cooling method for a cooling system that includes a heat exchanger that exchanges heat of the first refrigerant and heat of the second refrigerant, and cools the first heat source and the second heat source, wherein the first heat source and the second heat source are cooled. The pump, the first heat source, the heat exchanger, and the cooler are connected, and the first pump is connected to the first heat source, the heat exchanger, and the cooler. Circulating the first refrigerant, the second pump, the second heat source, and the flow path switching unit are connected to form a first flow path, the flow path switching unit, The heat exchanger is connected to form a second flow path, and the flow path switching unit is configured such that the second refrigerant is below a predetermined temperature. The second flow path is closed, and the second flow path is opened when the second refrigerant has a temperature equal to or higher than a predetermined temperature. The second pump includes the first flow path and the second flow path. The second refrigerant is circulated through the flow path.

  According to the present invention, it is possible to provide a cooling system, a magnetic resonance diagnostic apparatus, and a cooling method that do not cool the refrigerant on the secondary side more than necessary.

Hereinafter, embodiments of the present invention will be described.
FIG. 1 is a configuration diagram showing a configuration of a magnetic resonance diagnostic apparatus 1 in an embodiment according to the present invention.

  As shown in FIG. 1, the magnetic resonance diagnostic apparatus 1 includes a scanning unit 2, an operation console unit 3, and a cooling system 4.

  The scanning unit 2 will be described.

  As shown in FIG. 1, the scanning unit 2 includes a static magnetic field magnet unit 12, a gradient coil unit 13, an RF coil unit 14, and a table 15. In the imaging space where the static magnetic field is formed, Then, the subject SU is irradiated with electromagnetic waves so as to excite the imaging region of the subject SU, and a scan for obtaining a magnetic resonance signal generated in the imaging region of the subject SU is performed.

  Each component of the scanning unit 2 will be described sequentially.

  The static magnetic field magnet unit 12 is composed of, for example, a superconducting magnet, and forms a static magnetic field in an imaging space in which the subject SU is accommodated. Here, the static magnetic field magnet unit 12 forms a static magnetic field such that the direction of the static magnetic field is along the direction Y along the body axis direction of the subject SU. In addition, the static magnetic field magnet part 12 may be comprised with the permanent magnet.

The gradient coil unit 13 forms a gradient magnetic field in the imaging space where the static magnetic field is formed, and adds spatial position information to the magnetic resonance signal received by the RF coil unit 14. Here, the gradient coil unit 13 includes three systems of an x direction, a y direction, and a z direction, and forms a gradient magnetic field in each of the frequency encode direction, the phase encode direction, and the slice selection direction according to the imaging conditions. . Specifically, the gradient coil unit 13 applies a gradient magnetic field in the slice selection direction of the subject SU, and selects a slice of the subject SU to be excited by the RF coil unit 14 transmitting an RF pulse. The gradient coil unit 13 applies a gradient magnetic field in the phase encoding direction of the subject SU, and phase encodes the magnetic resonance signal from the slice excited by the RF pulse. The gradient coil unit 13 applies a gradient magnetic field in the frequency encoding direction of the subject SU, and frequency encodes the magnetic resonance signal from the slice excited by the RF pulse.
Moreover, in this embodiment, it cools with the cooling system 4. FIG.

  As shown in FIG. 1, the RF coil unit 14 is disposed so as to surround the imaging region of the subject SU. The RF coil unit 14 transmits an RF pulse, which is an electromagnetic wave, to the subject SU in the imaging space where the static magnetic field magnet unit 12 forms a static magnetic field to form a high-frequency magnetic field, and protons in the imaging region of the subject SU. Excites the spin. The RF coil unit 14 receives an electromagnetic wave generated from the excited proton in the subject SU as a magnetic resonance signal.

  The table 15 has a table on which the subject SU is placed.

  Next, the operation console unit 3 will be described.

  As shown in FIG. 1, the operation console unit 3 includes an RF drive unit 22, a gradient drive unit 23, a data collection unit 24, a control unit 30, an image generation unit 31, an operation unit 32, and a display unit 33. And a storage unit 34.

  Each component of the operation console unit 3 will be described sequentially.

  The RF drive unit 22 drives the RF coil unit 14 to transmit RF pulses in the imaging space to form a high frequency magnetic field. Based on the control signal from the control unit 30, the RF drive unit 22 modulates the signal from the RF oscillator to a signal having a predetermined timing and a predetermined envelope using a gate modulator, and then modulates the signal by the gate modulator. The signal thus amplified is amplified by an RF power amplifier and output to the RF coil unit 14 to transmit an RF pulse.

The gradient driving unit 23 applies a gradient pulse to the gradient coil unit 13 based on a control signal from the control unit 30 to drive the gradient coil unit 13 to generate a gradient magnetic field in an imaging space where a static magnetic field is formed. The gradient drive unit 23 includes three systems of drive circuits (not shown) corresponding to the three systems of gradient coil units 13.
In the present embodiment, the RF drive unit 22 and the gradient drive unit 23 are cooled by the cooling system 4.

  The data collection unit 24 collects magnetic resonance signals received by the RF coil unit 14 based on the control signal from the control unit 30. Here, in the data collecting unit 24, the phase detector detects the magnetic resonance signal received by the RF coil unit 14 using the output of the RF oscillator of the RF driving unit 22 as a reference signal. Thereafter, the magnetic resonance signal, which is an analog signal, is converted into a digital signal using an A / D converter and output.

  The control unit 30 includes a computer and a program that causes each unit to execute an operation corresponding to a predetermined scan using the computer, and controls each unit. Here, the control unit 30 receives operation data from the operation unit 32, and each of the RF drive unit 22, the gradient drive unit 23, and the data collection unit 24 based on the operation data input from the operation unit 32. In addition, control is performed by outputting a control signal for executing a predetermined scan, and control is performed by outputting control signals to the image generation unit 31, the display unit 33, and the storage unit.

  The image generation unit 31 includes a computer and a program that executes predetermined data processing using the computer, and is based on a magnetic resonance signal from the subject SU based on a control signal from the control unit 30. Thus, a slice image for the slice of the subject SU is reconstructed. Then, the image generation unit 31 outputs the generated image to the display unit 33.

  The operation unit 32 is configured by operation devices such as a keyboard and a pointing device. The operation unit 32 is input with operation data by an operator and outputs the operation data to the control unit 30.

  The display unit 33 is configured by a display device such as a CRT, and displays an image on the display screen based on a control signal from the control unit 30. For example, the display unit 33 displays a plurality of images of input items for which operation data is input to the operation unit 32 by the operator on the display screen. Further, the display unit 33 receives data about the slice image of the subject SU generated based on the magnetic resonance signal from the subject SU from the image generation unit 31 and displays the slice image on the display screen.

  The storage unit 34 includes a memory and stores various data. The storage unit 34 is accessed by the control unit 30 as necessary for the stored data.

Next, the cooling system 4 of this embodiment is demonstrated.
FIG. 2 is a diagram illustrating an example of the configuration of the cooling system 4 of the present embodiment.
As shown in FIG. 2, the cooling system 4 includes a cooler 41, a tank 42, a pump 43, a tank 44, a pump 45, a heat exchanger 46, a temperature detection unit 47, and a flow path switching unit 48, and the gradient described above. The coil unit 13, the RF drive unit 22, and the gradient drive unit 23 are used as heat sources.
The cooling system constituted by the cooler 41, the tank 42, the pump 43, the gradient coil unit 13 and the heat exchanger 46 is the primary side cooling system, the tank 44, the pump 45, the RF drive unit 22, the gradient drive unit 23, and the heat exchange. The cooling system constituted by the vessel 46, the temperature detection unit 47, and the flow path switching unit 48 is a secondary side cooling system.

The cooler 41 cools the liquid refrigerant A warmed by the gradient coil unit 13 or both of the gradient coil unit 13 and the heat exchanger 46. For the liquid refrigerant A, for example, water is used. In the present embodiment, the cooler 41 cools the liquid refrigerant A to 20 ° C., for example.
The tank 42 temporarily stores the liquid refrigerant A cooled by the cooler 41.

The pump 43 circulates the liquid refrigerant A through the cooler 41, the tank 42, the pump 43, the heat exchanger 46, and the gradient coil unit 13.
The gradient coil unit 13 is a heat source and transfers heat to the liquid refrigerant A.

  In addition, although FIG. 2 demonstrated the example in which the cooler 41, the tank 42, the pump 43, the heat exchanger 46, and the gradient coil part 13 were connected in series, this invention is not limited to this. That is, as shown in FIG. 3, the gradient coil unit 13 and the heat exchanger 46 may be connected in parallel.

  The tank 44 temporarily stores the secondary side cooling system liquid refrigerant B cooled by a heat exchanger 46 described later. For example, water is used as the liquid refrigerant B.

The pump 45 sends out the liquid refrigerant B temporarily stored in the tank 44, and as shown in FIG. 2, the tank 44, the pump 45, the RF drive unit 22 and / or the gradient drive unit 23, and the flow path switching. The first flow path formed by connecting the part 48 and the temperature detection part 47 is circulated.
Further, as shown in FIG. 2, the pump 45 circulates through the second flow path formed by connecting the heat exchanger 46 and the flow path switching unit 48.

The RF drive unit 22 and the gradient drive unit 23 are units that give a predetermined current to control the RF coil unit 14 and the gradient coil unit 13. That is, it can be said to be a power source for the RF coil unit 14 and the gradient coil unit 13, and is therefore a heat source that generates heat, and transfers heat to the liquid refrigerant B.
The heat exchanger 46 transfers the heat of the liquid refrigerant B to the liquid refrigerant A through the partition wall. Examples of the heat exchanger include a multi-tube cylindrical heat exchanger, a double-tube heat exchanger, and a plate heat exchanger, and any of them may be used in the present invention.

The temperature detection unit 47 detects the temperature when the liquid refrigerant B is allowed to pass and outputs the detected temperature to the flow path switching unit 48.
The channel switching unit 48 controls the channel according to the temperature of the liquid refrigerant B detected by the temperature detection unit 47. The flow path switching unit 48 that changes the flow path according to the temperature includes a material that uses a material that expands and contracts due to a temperature change, such as a thermo wax. In the present invention, the structure of the flow path switching unit 48 is not limited.

  As shown in FIG. 4A, for example, the flow path switching unit 48 includes a second heat exchanger 46 when the liquid temperature of the liquid refrigerant B when passing through the flow path switching unit 48 is lower than a predetermined temperature. When the liquid temperature of the liquid refrigerant B is equal to or higher than a predetermined temperature, the second flow path including the heat exchanger 46 is opened and the liquid refrigerant B is opened as shown in FIG. Pass through. The predetermined temperature is set to a temperature that does not affect the RF driving unit 22 and the gradient driving unit 23, for example, 30 ° C. This predetermined temperature may be arbitrarily controlled by a method such as making the flow path switching unit 48 electronically controlled, for example.

As described above, in the cooling system 4 of the present embodiment, the secondary side cooling system is divided into a case where the liquid temperature of the liquid refrigerant B of the secondary side cooling system is lower than the predetermined temperature and a case where the liquid temperature is higher than the predetermined temperature. The flow paths are different.
Hereinafter, as an example, when the predetermined temperature is 30 ° C., the case where the liquid temperature of the liquid refrigerant B is lower than 30 ° C. and the case where the liquid temperature is 30 ° C. or higher will be described.

<When liquid refrigerant B is less than 30 ° C.>
When the liquid temperature of the liquid refrigerant B is lower than 30 ° C., as described above and as shown in FIG. 4A, the flow path switching unit 48 closes the second flow path including the heat exchanger 46, and The liquid refrigerant B is passed through only one flow path.
That is, in the primary side cooling system, the liquid refrigerant A cooled by the cooler 41 is heated only by the gradient coil unit 13 and not heated by the heat exchanger 46. That is, the liquid temperature does not rise so much and the burden on the cooler 41 is small.
In the secondary side cooling system, the liquid refrigerant B heated by the RF drive unit 22 and / or the gradient drive unit 23 passes only through the first flow path that does not pass through the heat exchanger 46 by the flow path switching unit 48. Is done. However, since the liquid temperature is not as high as less than 30 ° C., the RF driving unit 22 and the gradient driving unit 23 are not adversely affected.

<When liquid refrigerant B is 30 ° C. or higher>
When the liquid temperature of the liquid refrigerant B is 30 ° C. or higher, the flow path switching unit 48 opens the second flow path including the heat exchanger 46 and passes the liquid refrigerant B as described above.
That is, in the primary side cooling system, the liquid refrigerant A cooled by the cooler 41 is heated by the gradient coil unit 13 and the heat exchanger 46.
In the secondary side cooling system, the liquid refrigerant B heated by the RF driving unit 22 and / or the gradient driving unit 23 is passed through the second flow path including the heat exchanger 46 by the flow path switching unit 48. . In the heat exchanger 46, the liquid refrigerant B is cooled by the liquid refrigerant A, and the cooled liquid refrigerant B cools the RF driving unit 22 and / or the gradient driving unit 23.

As described above, according to the cooling system 4 of the present embodiment, when the refrigerant of the secondary side cooling system is lower than the predetermined temperature, the second flow path including the heat exchanger 46 is provided by the flow path switching unit 48. Since it is closed, when the liquid temperature of the secondary side liquid refrigerant B is lower than a predetermined temperature, the secondary side refrigerant is not cooled, and condensation occurs due to cooling the secondary side liquid refrigerant B too much. Can be prevented, and damage such as a short circuit due to condensation of the RF driving unit 22 and the gradient driving unit 23 can be prevented.
Further, when the secondary side liquid refrigerant B is lower than a predetermined temperature, the burden on the primary side cooler 41 is reduced, and the running cost of the cooler can be saved. As a result, for example, a third or higher order cooling system can be added to the cooling system 4 and the cooling system newly added to the cooler 41 can be cooled.
Furthermore, since the temperature change of the liquid refrigerant B can be suppressed in the secondary side cooling system, the life of the cooling system 4 can be expected to be extended.

The present invention is not limited to the embodiment described above.
That is, those skilled in the art may make various modifications, combinations, subcombinations, and alternatives regarding the components of the above-described embodiments within the technical scope of the present invention or an equivalent scope thereof.

In the embodiment described above, the cooling system 4 is incorporated in the magnetic resonance diagnostic apparatus 1, the gradient coil unit 13 is the heat source of the primary cooling system, and the RF drive unit 22 and / or the gradient drive unit 23 is the secondary cooling system. However, the present invention is not limited to this, and a cooling system for cooling other heat sources may be used.
Further, the order in which the constituent elements of the first cooling system and the second cooling system shown in this embodiment are connected is an example, and the present invention is not limited to this.
Further, in this embodiment, water is used for the liquid refrigerants A and B, but other liquid refrigerants may be used and are not limited in the present invention.
Further, the cooling system 4 is not limited to the cooling system having only the primary and secondary cooling systems, and may be a cooling system including more cooling systems or a part thereof.

FIG. 1 is a configuration diagram showing the configuration of the magnetic resonance diagnostic apparatus 1. FIG. 2 is a diagram illustrating an example of the configuration of the cooling system 4 of the present embodiment. FIG. 3 is a diagram illustrating another example of the configuration of the cooling system 4 of the present embodiment. FIG. 4 is a diagram for explaining a change in the flow path of the secondary cooling system by the flow path switching unit 48.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Magnetic resonance diagnostic apparatus, 2 ... Scan part, 3 ... Operation console part, 4 ... Cooling system, 12 ... Static magnetic field magnet part, 13 ... Gradient coil part, 14 ... Coil part, 15 ... Table, 22 ... Drive part, DESCRIPTION OF SYMBOLS 23 ... Gradient drive part, 24 ... Data collection part, 30 ... Control part, 31 ... Image generation part, 32 ... Operation part, 33 ... Display part, 34 ... Memory | storage part, 41 ... Cooler, 42 ... Tank, 43 ... Pump , 44 ... Tank, 45 ... Pump, 46 ... Heat exchanger, 47 ... Temperature detector, 48 ... Flow path switching unit

Claims (8)

A cooling system for cooling the first heat source and the second heat source,
A cooler for cooling the first refrigerant;
A first pump;
A second pump;
A flow path switching unit for switching the flow path of the second refrigerant;
A heat exchanger for exchanging heat of the first refrigerant and heat of the second refrigerant;
Have
The first pump, the first heat source, the heat exchanger, and the cooler are coupled;
The first pump circulates the first refrigerant through the first heat source, the heat exchanger, and the cooler,
The second pump, the second heat source, and the flow path switching unit are connected to form a first flow path,
The flow path switching unit and the heat exchanger are connected to form a second flow path,
The flow path switching unit closes the second flow path when the second refrigerant is lower than a predetermined temperature, and the second flow path when the second refrigerant is equal to or higher than a predetermined temperature. Open
The second pump circulates the second refrigerant in the first flow path and the second flow path,
In the heat exchanger, the temperature of the first refrigerant is lower than the temperature of the second refrigerant. The cooling system according to claim 1, wherein the flow path switching unit is installed at a branch point between the first flow path and the second flow path. The cooling system according to claim 1 or 2, wherein the first heat source is a gradient coil of a magnetic resonance diagnostic apparatus. The cooling system according to any one of claims 1 to 3, wherein the second heat source is an RF coil driving unit or / and a gradient coil driving unit of a magnetic resonance diagnostic apparatus. The cooling system according to any one of claims 1 to 4, wherein the predetermined temperature, which is a reference for switching the flow path, can be arbitrarily set. The cooling system according to any one of claims 1 to 5, wherein the first refrigerant and the second refrigerant are liquids. After applying a high-frequency magnetic field to a subject in a static magnetic field, a scan unit that performs a scan for measuring a magnetic resonance signal from the subject, and the subject based on the magnetic resonance signal obtained by the scan unit A magnetic resonance diagnostic apparatus having an operation console unit that generates an image of the above and a cooling unit that cools an RF coil driving unit and / or a gradient coil driving unit that drives an RF coil and a gradient coil unit,
The cooling part is
A cooler for cooling the first refrigerant;
A first pump;
A second pump;
A flow path switching unit for switching the flow path of the second refrigerant;
A heat exchanger for exchanging heat of the first refrigerant and heat of the second refrigerant;
Have
The first pump, the first heat source, the heat exchanger, and the cooler are coupled;
The first pump circulates the first refrigerant through the first heat source, the heat exchanger, and the cooler,
The second pump, the second heat source, and the flow path switching unit are connected to form a first flow path,
The flow path switching unit and the heat exchanger are connected to form a second flow path,
The flow path switching unit closes the second flow path when the second refrigerant is lower than a predetermined temperature, and the second flow path when the second refrigerant is equal to or higher than a predetermined temperature. Open
The second pump circulates the second refrigerant in the first flow path and the second flow path,
In the heat exchanger, the temperature of the first refrigerant is lower than the temperature of the second refrigerant. Magnetic resonance diagnostic apparatus. A cooler that cools the first refrigerant, a first pump, a second pump, a flow path switching unit that switches a flow path of the second refrigerant, heat of the first refrigerant, and the second A cooling method for cooling a cooling system having a heat exchanger for exchanging heat of the refrigerant and cooling the first heat source and the second heat source,
The first pump, the first heat source, the heat exchanger, and the cooler are coupled;
The first pump circulates the first refrigerant through the first heat source, the heat exchanger, and the cooler,
The second pump, the second heat source, and the flow path switching unit are connected to form a first flow path,
The flow path switching unit and the heat exchanger are connected to form a second flow path,
The flow path switching unit closes the second flow path when the second refrigerant is lower than a predetermined temperature, and the second flow path when the second refrigerant is equal to or higher than a predetermined temperature. Open
The cooling method, wherein the second pump circulates the second refrigerant in the first flow path and the second flow path.

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