Cooling device and heat transport device

Abstract

A cooling device (100) comprises: an evaporator (1) that evaporates a liquid refrigerant (101) and cools a target (200); a condenser (2) that condenses gas refrigerant obtained by the evaporation performed by the evaporator; a valve (5) that is provided between the evaporator and the condenser, and the opening degree of which can be adjusted for regulating the evaporation temperature of the refrigerant; and a pump (4) that includes a backflow prevention mechanism (41) and that discharges liquid refrigerant, obtained by the condensation performed by the condenser, toward the evaporator while the backflow prevention mechanism prevents a backflow of the refrigerant.

Description

Cooling and heat transport devices

[0001] The present invention relates to a cooling device and a heat transport device.

[0002] Conventionally, cooling devices have been known. Such cooling devices are disclosed, for example, in "Research on Temperature Control by Steam Valve Operation of a Latent Heat Utilizing Fluid Loop Heat Exhaust System" by Terushige Fujii and three others, Japan Aerospace Exploration Agency Contract Report, Japan Aerospace Exploration Agency, October 29, 2004, JAXA-CR-04-002 (hereinafter simply referred to as "Non-Patent Document 1").

[0003] Non-Patent Document 1 discloses a cooling device including a pump, an evaporator, a condenser, and a valve. In this cooling device, refrigerant discharged from the pump evaporates by absorbing a heat load in the evaporator and condenses in the condenser. The condensed refrigerant returns to the pump and is discharged again, repeating the cycle. In addition, a valve is provided between the evaporator and the condenser, and by adjusting its opening, the pressure of the refrigerant inside the evaporator and the evaporation temperature of the refrigerant are changed. By adjusting the opening of the valve between the evaporator and the condenser, the evaporation temperature of the refrigerant is adjusted, thereby adjusting the temperature of the evaporator surface. The pump is a gear pump.

[0004] Terushige Fujii and three others, "Study on temperature control by steam valve operation of latent heat utilization fluid loop type heat exhaust system," Japan Aerospace Exploration Agency contract report, Japan Aerospace Exploration Agency, October 29, 2004, JAXA-CR-04-002

[0005] The inventors of the present application discovered that the cooling device described in Non-Patent Document 1, which uses a gear pump, has the following new problem. Specifically, due to the structure of the gear pump, it is not possible to provide a seal that completely separates the high-pressure side and the low-pressure side inside the gear pump. Therefore, a backflow of refrigerant occurs due to the pressure difference between the high-pressure side and the low-pressure side inside the gear pump, causing a change in the discharge flow rate of the refrigerant. Specifically, if the discharge pressure of the refrigerant is increased to increase the pressure difference between the high-pressure side and the low-pressure side, the backflow of refrigerant inside the gear pump increases, resulting in a decrease in the discharge flow rate of the refrigerant. The backflow of refrigerant inside the gear pump is unavoidable due to the structure of the gear pump.

[0006] Furthermore, in the cooling device described in Non-Patent Document 1, when adjusting the evaporation temperature of the refrigerant by adjusting the valve opening, the refrigerant pressure changes, and the change in refrigerant pressure caused by adjusting the valve opening causes a change in the refrigerant discharge pressure of the gear pump. In this case, the backflow rate of refrigerant inside the gear pump changes as described above, and therefore the refrigerant discharge rate of the gear pump changes. Therefore, in order to perform cooling accurately, the cooling device described in Non-Patent Document 1 needs to control not only the valve opening but also the refrigerant discharge rate of the gear pump. In this case, the number of controlled objects increases, which is considered to be a problem in that the control becomes complicated.

[0007] The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to provide a cooling device and a heat transport device that can suppress the complexity of control when adjusting the evaporation temperature of a refrigerant by adjusting the valve opening in a two-phase heat exchanger that utilizes the phase change when a refrigerant changes between a liquid and a gas.

[0008] A cooling device in a first aspect of the present invention includes an evaporator that evaporates liquid refrigerant to cool an object, a condenser that condenses the gaseous refrigerant evaporated in the evaporator, a valve that is provided between the evaporator and the condenser and has an adjustable opening to adjust the evaporation temperature of the refrigerant, and a pump that includes a backflow prevention mechanism and discharges the liquid refrigerant condensed in the condenser toward the evaporator while preventing backflow of the refrigerant using the backflow prevention mechanism.

[0009] A heat transport device according to a second aspect of the present invention includes a preheater that evaporates a portion of a liquid refrigerant, a heat exchanger that condenses the gaseous refrigerant evaporated in the preheater or evaporates the liquid refrigerant to heat or cool an object, a condenser that condenses the gaseous refrigerant evaporated in the preheater and / or the heat exchanger, a valve that is disposed between the evaporator and the condenser and has an adjustable opening to adjust the evaporation temperature of the refrigerant, and a pump that includes a backflow prevention mechanism and discharges the liquid refrigerant condensed in the condenser toward the heat exchanger while preventing backflow of the refrigerant with the backflow prevention mechanism.

[0010] The cooling device according to a first aspect of the present invention and the heat transport device according to a second aspect of the present invention each include a pump that includes a backflow prevention mechanism and discharges the liquid refrigerant condensed in the condenser toward the evaporator while preventing backflow of the refrigerant using the backflow prevention mechanism. This prevents backflow of the refrigerant inside the pump, so that the refrigerant discharge flow rate from the pump does not change even if the refrigerant pressure changes due to changes in the refrigerant pressure caused by adjusting the valve opening. As a result, when adjusting the refrigerant evaporation temperature by adjusting the valve opening, it is not necessary to control the refrigerant discharge flow rate from the pump. This reduces the number of control targets, thereby preventing the complexity of control when adjusting the refrigerant evaporation temperature by adjusting the valve opening in a two-phase heat exchanger that utilizes the phase change when the refrigerant changes between liquid and gas.

[0011] Fig. 1 is a schematic diagram showing a cooling device according to a first embodiment. Fig. 2 is a schematic diagram showing a pump according to the first embodiment. Fig. 3 is a schematic diagram for explaining a refrigerant suction operation of the pump according to the first embodiment. Fig. 4 is a schematic diagram for explaining a refrigerant discharge operation of the pump according to the first embodiment. Fig. 5 is a schematic diagram for explaining control when lowering the evaporation temperature of the refrigerant according to the first embodiment. Fig. 6 is a schematic diagram for explaining control when raising the evaporation temperature of the refrigerant according to the first embodiment. Fig. 7 is a schematic diagram showing a heat transport device according to a second embodiment.

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.

[0013] First Embodiment The configuration of a cooling device 100 according to a first embodiment will be described with reference to FIGS.

[0014] (Configuration of Cooling Device) As shown in Fig. 1, cooling device 100 is a cooling device that performs two-phase heat exchange (cooling) utilizing the phase change that occurs when refrigerant 101 changes between a liquid and a gas. Specifically, cooling device 100 includes an evaporator 1, a condenser 2, a tank 3, a pump 4, a valve 5, a sensor 6, and a control unit 7. Refrigerant 101 is carbon dioxide, which is a natural refrigerant. Compared to fluorocarbon-based refrigerants, carbon dioxide has a greater rate of increase in saturation pressure relative to a temperature increase. For example, when the evaporation temperature of carbon dioxide is changed from -20°C to 0°C, the saturation pressure increases by approximately 1.5 MPa.

[0015] The evaporator 1 evaporates a liquid refrigerant 101 to cool an object 200. The object 200 is a heat generating body such as an electronic device. The evaporator 1 functions as a heat exchanger that exchanges heat between the object 200 and the refrigerant 101. The evaporator 1 receives heat from the object 200 and evaporates the refrigerant 101. The evaporator 1 is also connected to the condenser 2 via a refrigerant pipe 8a. In the refrigerant pipe 8a, the refrigerant 101 is in a gas-liquid two-phase flow state in which the liquid refrigerant 101 and the gas refrigerant 101 are mixed.

[0016] The condenser 2 condenses the gaseous refrigerant 101 evaporated in the evaporator 1. The condenser 2 functions as a heat exchanger that exchanges heat between the cooling liquid 9a of the chiller 9 and the refrigerant 101. The condenser 2 transfers heat to the cooling liquid 9a, condensing the refrigerant 101. The condenser 2 is also connected to the tank 3 via a refrigerant pipe 8b.

[0017] The tank 3 is provided between the condenser 2 and the pump 4, and is a container for storing the liquid refrigerant 101 condensed in the condenser 2. The tank 3 is connected to the pump 4 via a refrigerant pipe 8c.

[0018] The pump 4 discharges the liquid refrigerant 101, which has been condensed in the condenser 2 and stored in the tank 3, toward the evaporator 1. The pump 4 sucks the liquid refrigerant 101 stored in the tank 3 and discharges the sucked liquid refrigerant 101 toward the evaporator 1. The pump 4 is also connected to the evaporator 1 via a refrigerant pipe 8d. The detailed configuration of the pump 4 will be described later.

[0019] The valve 5 is provided between the evaporator 1 and the condenser 2 to adjust the evaporation temperature of the refrigerant 101. The valve 5 is provided midway through the refrigerant pipe 8a connecting the evaporator 1 and the condenser 2. The valve 5 has an adjustable opening. The opening of the valve 5 can be adjusted in stages from fully closed to fully open. The valve 5 is driven by an actuator such as a solenoid valve or an electric valve, and the opening is adjusted by driving the actuator based on a control signal from the control unit 7. When the opening of the valve 5 is adjusted, the pressure loss in the valve 5 changes, and therefore the pressure of the refrigerant 101 in the evaporator 1 upstream of the valve 5 changes. Then, by changing the pressure of the refrigerant 101 in the evaporator 1, the evaporation temperature of the refrigerant 101 in the evaporator 1 is adjusted.

[0020] The sensor 6 detects a value related to the evaporation temperature of the refrigerant 101 in the evaporator 1. The sensor 6 is, for example, a temperature sensor that detects the temperature of the evaporator 1 or the temperature of the refrigerant 101 in the evaporator 1, or a pressure sensor that detects the pressure of the evaporator 1. The sensor 6 outputs the detected value to the control unit 7. The control unit 7 performs control to adjust the opening of the valve 5 based on the value acquired from the sensor 6.

[0021] The control unit 7 controls the entire cooling device 100. The control unit 7 includes a processor such as a CPU (Central Processing Unit) and a memory. The control unit 7 controls the entire cooling device 100 based on a program stored in an internal or external memory.

[0022] In the cooling device 100, the refrigerant 101 flows through the tank 3, the pump 4, the evaporator 1, and the condenser 2 in this order, and is then returned to the tank 3, repeating this circulation cycle to cool the target 200. Furthermore, when cooling the target 200, the evaporation temperature of the refrigerant 101 in the evaporator 1 is adjusted by adjusting the opening of the valve 5, thereby adjusting the amount of heat exchange (amount of cooling) for the target 200.

[0023] (Detailed Configuration of Pump) In the first embodiment, as shown in FIGS. 2 to 4 , the pump 4 includes a backflow prevention mechanism 41, and discharges the liquid refrigerant 101 condensed in the condenser 2 toward the evaporator 1 while preventing backflow of the refrigerant 101 with the backflow prevention mechanism 41. The pump 4 is a reciprocating pump. Specifically, the pump 4 is a plunger pump. The pump 4 includes an inlet 4a connected to the refrigerant pipe 8c, an outlet 4b connected to the refrigerant pipe 8d, and a pump chamber 4c provided between the inlet 4a and the outlet 4b. The pump 4 also includes the backflow prevention mechanism 41, a plunger 42, a power transmission unit 43, a motor 44, and an inverter 45.

[0024] The backflow prevention mechanism 41 has check valves 41 a and 41 b arranged inside the pump 4 .

[0025] The check valve 41a is disposed on the inlet 4a side of the pump 4. Specifically, the check valve 41a is disposed between the inlet 4a and the pump chamber 4c, and prevents the refrigerant 101 from flowing back from the pump chamber 4c to the inlet 4a. The check valve 41a is opened when the pump 4 draws the refrigerant 101. Furthermore, the check valve 41a is closed when the pump 4 has completed drawing the refrigerant 101. This prevents the drawn refrigerant 101 from flowing back from the pump chamber 4c to the inlet 4a.

[0026] The check valve 41b is disposed on the outlet 4b side of the pump 4. Specifically, the check valve 41b is disposed between the outlet 4b and the pump chamber 4c, and prevents the refrigerant 101 from flowing back from the outlet 4b to the pump chamber 4c. The check valve 41b is opened when the pump 4 discharges the refrigerant 101. Furthermore, the check valve 41b is closed when the pump 4 has completed discharging the refrigerant 101. This prevents the discharged refrigerant 101 from flowing back from the outlet 4b to the pump chamber 4c.

[0027] The plunger 42 is disposed in the pump chamber 4c. The plunger 42 changes the volume of the pump chamber 4c by linearly reciprocating, thereby drawing in or discharging the refrigerant 101 in the pump 4. The power transmission unit 43 is disposed between the plunger 42 and the motor 44 and transmits driving force from the motor 44 to the plunger 42. The power transmission unit 43 may include a cam mechanism or a crank mechanism that converts the circular motion of the motor 44 into the linear motion of the plunger 42. The motor 44 is the drive source for the plunger 42 and drives the plunger 42 via the power transmission unit 43. The inverter 45 is connected to the motor 44 and controls the frequency of power supplied to the motor 44 based on a control signal from the control unit 7. The motor 44 operates at a rotational speed corresponding to the operating frequency, which is the frequency of the power supplied from the inverter 45. The pump 4 discharges the refrigerant 101 at a constant discharge flow rate corresponding to the operating frequency (rotational speed) of the motor 44.

[0028] As shown in FIG. 3 , the pump 4 draws the refrigerant 101 from the inlet 4a into the pump chamber 4c by the motor 44 driving the plunger 42 backward. That is, when the motor 44 drives the plunger 42 backward, the volume of the pump chamber 4c increases and the pressure in the pump chamber 4c decreases. As a result, the refrigerant 101 is drawn into the pump chamber 4c from the inlet 4a. At this time, the force of the refrigerant 101 being drawn into the pump chamber 4c from the inlet 4a causes the check valve 41a to change from a closed state to an open state. Then, once the suction of the refrigerant 101 is complete, the check valve 41a changes from an open state to a closed state. This prevents the drawn refrigerant 101 from flowing back from the pump chamber 4c to the inlet 4a. During the suction of the refrigerant 101, the check valve 41b remains closed.

[0029] As shown in FIG. 4 , the pump 4 discharges the refrigerant 101 from the pump chamber 4c to the outlet 4b as the motor 44 moves the plunger 42 forward. That is, when the motor 44 moves the plunger 42 forward, the volume of the pump chamber 4c decreases and the pressure in the pump chamber 4c increases. As a result, the refrigerant 101 is discharged from the pump chamber 4c to the outlet 4b. At this time, the force of the refrigerant 101 being discharged from the pump chamber 4c to the outlet 4b changes the check valve 41b from a closed state to an open state. Then, when the discharge of the refrigerant 101 is completed, the check valve 41b changes from an open state to a closed state. This prevents the discharged refrigerant 101 from flowing back from the outlet 4b to the pump chamber 4c. Note that the check valve 41a remains closed while the refrigerant 101 is being discharged.

[0030] The pump 4 delivers the refrigerant 101 by linearly reciprocating the plunger 42 so as to alternately suck in and discharge the refrigerant 101. As described above, the check valve 41a prevents backflow of the refrigerant 101 when sucking in the refrigerant 101, and the check valve 41b prevents backflow of the refrigerant 101 when discharging the refrigerant 101. This allows the pump 4 to deliver the refrigerant 101 at a constant discharge rate while preventing backflow. Note that while FIGS. 2 to 4 show an example in which the pump 4 is provided with one plunger 42, the pump 4 may be provided with multiple plungers 42. When the pump 4 is provided with multiple plungers 42, operating the multiple plungers 42 at different timings allows the refrigerant 101 to be delivered while suppressing pulsation.

[0031] 5 and 6 , the control unit 7 adjusts the opening of the valve 5 while keeping the operation frequency of the pump 4 constant, thereby adjusting the evaporation temperature of the refrigerant 101. Specifically, the control unit 7 adjusts the opening of the valve 5 while keeping the operation frequency of the pump 4 constant at an operation frequency based on the amount of heat input from the target 200 to the evaporator 1, thereby adjusting the evaporation temperature of the refrigerant 101.

[0032] For example, the operating frequency of the pump 4 is determined in advance by calculating an operating frequency (discharge flow rate) from a previously obtained heat input from the target 200 to the evaporator 1 such that the refrigerant 101 is saturated (a state in which both liquid and gas exist) at the outlet of the evaporator 1. When the heat input is large, the discharge flow rate of the refrigerant 101 from the pump 4 must be increased to saturate the refrigerant 101 at the outlet of the evaporator 1, and therefore the operating frequency becomes high. On the other hand, when the heat input is small, the discharge flow rate of the refrigerant 101 from the pump 4 must be reduced to saturate the refrigerant 101 at the outlet of the evaporator 1, and therefore the operating frequency becomes low.

[0033] The control unit 7 controls the inverter 45 to control the pump 4 so that it operates at a predetermined constant operating frequency. The pump 4 discharges the refrigerant 101 at a constant discharge flow rate according to the constant operating frequency from the inverter 45. The pump 4 continues to operate at the constant operating frequency during the cooling control of the target 200.

[0034] Furthermore, the control unit 7 determines whether to increase or decrease the evaporation temperature of the refrigerant 101 based on the value detected by the sensor 6. When the control unit 7 determines, based on the value detected by the sensor 6, that it is necessary to decrease the evaporation temperature of the refrigerant 101, it controls the valve 5 to increase its opening. This reduces the pressure loss in the valve 5, thereby decreasing the pressure of the refrigerant 101 in the evaporator 1. As a result, the evaporation temperature of the refrigerant 101 in the evaporator 1 decreases. At this time, the discharge pressure of the refrigerant 101 from the pump 4 decreases due to the reduction in the pressure of the refrigerant 101 caused by the adjustment of the opening of the valve 5. However, because the backflow prevention mechanism 41 prevents the refrigerant 101 from flowing back inside the pump 4, the pump 4 discharges the refrigerant 101 at a constant discharge flow rate corresponding to a constant operating frequency, without being affected by changes in the discharge pressure of the refrigerant 101 from the pump 4.

[0035] Furthermore, when the control unit 7 determines, based on the value detected by the sensor 6, that it is necessary to increase the evaporation temperature of the refrigerant 101, it controls the valve 5 to decrease its opening. This increases the pressure loss in the valve 5, and therefore the pressure of the refrigerant 101 in the evaporator 1. As a result, the evaporation temperature of the refrigerant 101 in the evaporator 1 increases. At this time, the discharge pressure of the refrigerant 101 from the pump 4 increases due to the increase in the pressure of the refrigerant 101 caused by adjusting the opening of the valve 5. However, because the backflow prevention mechanism 41 prevents the refrigerant 101 from flowing back inside the pump 4, the pump 4 discharges the refrigerant 101 at a constant discharge flow rate corresponding to a constant operating frequency, without being affected by changes in the discharge pressure of the refrigerant 101 from the pump 4.

[0036] (Effects of First Embodiment) In the first embodiment, the following effects can be obtained.

[0037] In the first embodiment, a pump 4 is provided that includes a backflow prevention mechanism 41 and discharges the liquid refrigerant 101 condensed in the condenser 2 toward the evaporator 1 while preventing backflow of the refrigerant 101 with the backflow prevention mechanism 41. This prevents backflow of the refrigerant 101 inside the pump 4, so that even if the discharge pressure of the refrigerant 101 from the pump 4 changes due to a change in the pressure of the refrigerant 101 caused by adjustment of the opening of the valve 5, the discharge flow rate of the refrigerant 101 from the pump 4 does not change. As a result, when adjusting the evaporation temperature of the refrigerant 101 by adjusting the opening of the valve 5, it is not necessary to control the discharge flow rate of the refrigerant 101 from the pump 4. This reduces the number of objects to be controlled, and therefore prevents the control from becoming complicated when adjusting the evaporation temperature of the refrigerant 101 by adjusting the opening of the valve 5 in two-phase heat exchange (cooling) that utilizes the phase change when the refrigerant 101 changes between a liquid and a gas.

[0038] Furthermore, unlike the first embodiment, if the pump 4 is a pump whose discharge flow rate changes depending on the discharge pressure, such as a gear pump, the discharge flow rate of the refrigerant 101 from the pump 4 changes by adjusting the opening of the valve 5. Therefore, in order to appropriately adjust the discharge flow rate of the refrigerant 101 from the pump 4, it is necessary to increase or decrease the pressure using an accumulator, add a valve for adjusting the flow rate between the evaporator 1 and the pump 4, or feedback control the rotational speed of the pump 4. In contrast, in the present embodiment, the discharge flow rate of the refrigerant 101 from the pump 4 does not change, and there is no need to adjust the discharge flow rate of the refrigerant 101 from the pump 4. Therefore, there is no need to increase or decrease the pressure using an accumulator, add a valve for adjusting the flow rate between the evaporator 1 and the pump 4, or feedback control the rotational speed of the pump 4. Therefore, the number of components required for control is reduced (an accumulator or additional valves are not required), thereby suppressing structural complexity, and the number of controlled objects is reduced (feedback control of the rotational speed of the pump 4 is not required), thereby suppressing control complexity.

[0039] Furthermore, the cooling device 100 according to the first embodiment is configured as follows, thereby providing the following additional effects.

[0040] In the first embodiment, the backflow prevention mechanism 41 has check valves 41a and 41b arranged inside the pump 4. This makes it possible to prevent backflow of the refrigerant 101 inside the pump 4 with a simple structure.

[0041] In the first embodiment, the pump 4 is a reciprocating pump, which has a stable discharge flow rate regardless of the discharge pressure, and therefore, the refrigerant 101 can be stably discharged at a constant discharge flow rate.

[0042] In the first embodiment, the pump 4 is a plunger pump. This allows for greater freedom in selecting the pump 4, since a plunger pump, unlike a gear pump, can handle high discharge pressures (for example, several MPa). Even refrigerants 101 such as carbon dioxide, which tend to require high pressure because their saturation pressure increases at a high rate relative to a rise in temperature, can be easily pressurized.

[0043] Furthermore, in the first embodiment, the cooling device 100 includes a control unit 7 that adjusts the evaporation temperature of the refrigerant 101 by adjusting the opening of the valve 5 while keeping the operation frequency of the pump 4 constant. As a result, when adjusting the evaporation temperature of the refrigerant 101 by adjusting the opening of the valve 5, it is not necessary to control the discharge flow rate of the refrigerant 101 from the pump 4, and this makes it possible to keep the operation frequency of the pump 4 constant, thereby facilitating control.

[0044] Furthermore, in the first embodiment, the control unit 7 adjusts the opening of the valve 5 while keeping the operation frequency of the pump 4 constant at an operation frequency based on the amount of heat input from the target 200 to the evaporator 1, thereby adjusting the evaporation temperature of the refrigerant 101. This makes it possible to adjust the evaporation temperature of the refrigerant 101 by adjusting the opening of the valve 5 while discharging the refrigerant 101 at an appropriate discharge flow rate based on the amount of heat input from the target 200 to the evaporator 1, making control easier.

[0045] Furthermore, in the first embodiment, the cooling device 100 includes a tank 3 that is provided between the condenser 2 and the pump 4 and that stores the liquid refrigerant 101 condensed by the condenser 2, and the pump 4 discharges the liquid refrigerant 101 stored in the tank 3 toward the evaporator 1. This allows the liquid refrigerant 101 to be stably supplied from the tank 3 to the pump 4, and therefore the liquid refrigerant 101 to be stably supplied from the pump 4 to the evaporator 1.

[0046] Furthermore, in the first embodiment, the refrigerant 101 is carbon dioxide. Here, when carbon dioxide, which has a large rate of increase in saturation pressure relative to an increase in temperature, is used as the refrigerant 101, a high discharge pressure is required of the pump 4, which tends to increase the pressure difference between the high-pressure side and the low-pressure side inside the pump 4. Therefore, when the pump 4 is a pump whose discharge flow rate changes depending on the discharge pressure, using carbon dioxide as the refrigerant tends to increase the amount of backflow of the refrigerant 101 inside the pump 4. In contrast, in the first embodiment, the pump 4 is provided with a backflow prevention mechanism 41, which makes it possible to effectively prevent backflow of carbon dioxide as the refrigerant 101.

[0047] Second Embodiment Next, a second embodiment of the present invention will be described with reference to Fig. 7. In the second embodiment, an example of a heat transport device will be described. Note that the same components as those in the first embodiment are designated by the same reference numerals, and their description will be omitted.

[0048] 7, the heat transport device 300 is a heat transport device that performs two-phase heat exchange (heating or cooling) utilizing the phase change that occurs when the refrigerant 101 changes between a liquid and a gas. Specifically, the heat transport device 300 includes a preheater 310, a heat exchanger 301, a condenser 2, a tank 3, a pump 4, a valve 5, a sensor 6, and a control unit 7.

[0049] The preheater 310 is provided between the pump 4 and the heat exchanger 301. The preheater 310 preheats the liquid refrigerant 101 flowing into the heat exchanger 301, thereby evaporating a portion of the liquid refrigerant 101. The preheater 310 has a function of supplying the refrigerant 101 in a gas-liquid two-phase state to the heat exchanger 301.

[0050] The heat exchanger 301 is provided in place of the evaporator 1 of the first embodiment. The heat exchanger 301 condenses the gaseous refrigerant 101 evaporated in the preheater 310 or evaporates the liquid refrigerant 101 to heat or cool the target 200. The heat exchanger 301 functions as a heat exchanger that exchanges heat between the target 200 and the refrigerant 101. The heat exchanger 301 receives heat from the target 200 and evaporates the refrigerant 101. In this case, the target 200 is cooled. The heat exchanger 301 also provides heat to the target 200 and condenses the refrigerant 101. In this case, the target 200 is heated. In the second embodiment, by providing the preheater 310, it is possible to not only cool but also heat the target 200.

[0051] The other configurations of the second embodiment are similar to those of the first embodiment.

[0052] (Effects of Second Embodiment) In the second embodiment, the following effects can be obtained.

[0053] In the second embodiment, a pump 4 is provided that includes a backflow prevention mechanism 41 and discharges the liquid refrigerant 101 condensed in the condenser 2 toward the heat exchanger 301 while preventing backflow of the refrigerant 101 with the backflow prevention mechanism 41. As a result, similar to the first embodiment, in two-phase heat exchange (heating or cooling) that utilizes the phase change when the refrigerant 101 changes between a liquid and a gas, when the evaporation temperature of the refrigerant 101 is adjusted by adjusting the opening of the valve 5, it is possible to prevent the control from becoming complicated.

[0054] The other effects of the second embodiment are the same as those of the first embodiment.

[0055] [Modifications] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the description of the above-mentioned embodiments, and further includes all modifications (modifications) within the meaning and scope of the claims.

[0056] For example, in the first and second embodiments, the pump is a reciprocating pump, but the present invention is not limited to this. In the present invention, the pump may be a pump other than a reciprocating pump as long as it includes a backflow prevention mechanism.

[0057] Furthermore, in the first and second embodiments, examples have been shown in which the pump is a plunger pump, but the present invention is not limited to this, and the pump in the present invention may be a diaphragm pump.

[0058] In the first and second embodiments, the cooling device includes a tank, but the present invention is not limited to this. For example, in the present invention, the cooling device does not need to include a tank if the refrigerant can be stably supplied to the pump from the refrigerant pipe without the tank.

[0059] Although the first and second embodiments have been described above with reference to examples in which the refrigerant is carbon dioxide, the present invention is not limited to this. In the present invention, the refrigerant may be a natural refrigerant other than carbon dioxide, such as ammonia. The refrigerant may also be a fluorocarbon-based refrigerant.

[0060] Aspects It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0061] (Item 1) A cooling device comprising: an evaporator that evaporates a liquid refrigerant to cool an object; a condenser that condenses the gaseous refrigerant evaporated in the evaporator; a valve that is provided between the evaporator and the condenser and has an adjustable opening to adjust the evaporation temperature of the refrigerant; and a pump that includes a backflow prevention mechanism and discharges the liquid refrigerant condensed in the condenser toward the evaporator while preventing backflow of the refrigerant using the backflow prevention mechanism.

[0062] (Item 2) The cooling device according to item 1, wherein the backflow prevention mechanism includes a check valve disposed inside the pump.

[0063] (Item 3) The cooling device according to item 1 or 2, wherein the pump is a reciprocating pump.

[0064] (Item 4) The cooling device according to item 3, wherein the pump is a plunger pump or a diaphragm pump.

[0065] (Item 5) The cooling device according to any one of items 1 to 4, further comprising a control unit that adjusts an opening degree of the valve while keeping the operating frequency of the pump constant, thereby adjusting an evaporation temperature of the refrigerant.

[0066] (Item 6) The cooling device according to Item 5, wherein the control unit adjusts an opening of the valve while keeping an operating frequency of the pump constant at an operating frequency based on an amount of heat input from the target to the evaporator, thereby adjusting an evaporation temperature of the refrigerant.

[0067] (Item 7) The cooling device according to any one of Items 1 to 6, further comprising a tank provided between the condenser and the pump for storing the refrigerant in liquid form condensed by the condenser, wherein the pump discharges the refrigerant in liquid form stored in the tank toward the evaporator.

[0068] (Item 8) The cooling device according to any one of Items 1 to 7, wherein the refrigerant is carbon dioxide.

[0069] (Item 9) A heat transport device comprising: a preheater that evaporates a portion of a liquid refrigerant; a heat exchanger that condenses the gaseous refrigerant evaporated in the preheater or evaporates the liquid refrigerant to heat or cool an object; a condenser that condenses the gaseous refrigerant evaporated in the preheater and / or the heat exchanger; a valve that is provided between the heat exchanger and the condenser and has an adjustable opening for adjusting the evaporation temperature of the refrigerant; and a pump that includes a backflow prevention mechanism and discharges the liquid refrigerant condensed in the condenser toward the heat exchanger while preventing backflow of the refrigerant with the backflow prevention mechanism.

[0070] REFERENCE SIGNS LIST 1 evaporator 2 condenser 3 tank 4 pump 5 valve 7 control unit 41 backflow prevention mechanism 41a, 41b check valve 100 cooling device 101 refrigerant 200 object 300 heat transport device 301 heat exchanger 310 preheater

Claims

1. A cooling device comprising: an evaporator that evaporates a liquid refrigerant to cool an object; a condenser that condenses the gaseous refrigerant evaporated in the evaporator; a valve that is provided between the evaporator and the condenser and has an adjustable opening for adjusting the evaporation temperature of the refrigerant; and a pump that includes a backflow prevention mechanism and discharges the liquid refrigerant condensed in the condenser toward the evaporator while preventing backflow of the refrigerant using the backflow prevention mechanism.

2. The cooling device according to claim 1, wherein the backflow prevention mechanism comprises a check valve disposed inside the pump.

3. The cooling device of claim 1, wherein the pump is a reciprocating pump.

4. The cooling device according to claim 3, wherein the pump is a plunger pump or a diaphragm pump.

5. The cooling device according to claim 1, further comprising a control unit that performs control to adjust the evaporation temperature of the refrigerant by adjusting the opening degree of the valve while keeping the operating frequency of the pump constant.

6. A cooling device as described in claim 5, wherein the control unit performs control to adjust the evaporation temperature of the refrigerant by adjusting the opening of the valve while keeping the operating frequency of the pump constant at an operating frequency based on the amount of heat input from the target to the evaporator.

7. The cooling device according to claim 1, further comprising a tank provided between the condenser and the pump for storing the liquid refrigerant condensed in the condenser, and the pump discharges the liquid refrigerant stored in the tank toward the evaporator.

8. The cooling device of claim 1, wherein the refrigerant is carbon dioxide.

9. A heat transport device comprising: a preheater which evaporates a portion of a liquid refrigerant; a heat exchanger which condenses the gaseous refrigerant evaporated in the preheater or evaporates the liquid refrigerant to heat or cool an object; a condenser which condenses the gaseous refrigerant evaporated in the preheater and / or the heat exchanger; a valve provided between the heat exchanger and the condenser, the valve having an adjustable opening for adjusting the evaporation temperature of the refrigerant; and a pump which includes a backflow prevention mechanism and discharges the liquid refrigerant condensed in the condenser toward the heat exchanger while preventing backflow of the refrigerant by the backflow prevention mechanism.

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