Refrigeration cycle device

Abstract

Provided is a refrigeration cycle device capable of ultra-low temperature cooling using a refrigerant that has, as a main component, carbon dioxide with a low ozone depletion potential and a global warming potential.　This vapor compression-type refrigeration cycle device comprises a refrigerant circuit (10) in which a compression means (11), a radiator (12), a throttling means (14), and an evaporator (15) are sequentially connected and in which a refrigerant circulates, wherein a mixed refrigerant having carbon dioxide as a main component and containing at least one among dimethyl ether and difluoromethane is used as the refrigerant, and a refrigeration cycle operation is performed with the pressure of the refrigerant at an inlet of the evaporator (15) being the triple point pressure of the carbon dioxide or lower. According to this device, by using a refrigerant containing carbon dioxide which has excellent environmental performance, ultra-low temperature cooling in which the set temperature of a control target is negative 40°C or lower can be safely performed without circulation defects caused by solidification of the refrigerant.

Description

Technical Field

[0001] The present invention relates to a refrigeration cycle device that performs cooling or heating using a vapor compression refrigeration cycle, and particularly to a refrigeration cycle device that uses a refrigerant mainly composed of carbon dioxide.

Background Art

[0002] Conventionally, a vapor compression refrigeration cycle device that uses carbon dioxide (R744, CO2) as a refrigerant has been known. For example, Patent Document 1 discloses a refrigeration cycle device employed in a low-temperature showcase or the like, which uses carbon dioxide as a refrigerant. The refrigeration cycle device disclosed in this document includes a main circuit including a two-stage compression compressor, a radiator, an expansion valve, and an evaporator, and further includes a sub-circuit including a diverter, a sub-pressure reducing device, and an intermediate heat exchanger, which is a so-called split cycle (two-stage compression one-stage expansion intermediate cooling cycle) device.

[0003] In a split cycle refrigeration device, the refrigerant cooled by the radiator is divided into two refrigerant flows by the diverter. One of the diverted refrigerants flows through the main circuit, and the other refrigerant flows through the sub-circuit. The refrigerant flowing through the sub-circuit is decompressed by the sub-pressure reducing device and then exchanges heat with the refrigerant flowing through the main circuit in the intermediate heat exchanger and is sucked into the high-stage compressor. On the other hand, the refrigerant flowing through the main circuit is cooled by the refrigerant flowing through the sub-circuit in the intermediate heat exchanger, then decompressed by the expansion valve, evaporated in the evaporator, and sucked into the low-stage compressor. Thereby, in the carbon dioxide refrigerant with a low critical pressure, while reducing the pressure on the high-pressure side to suppress the high and low pressure difference, the specific enthalpy of the refrigerant flowing into the evaporator can be reduced to ensure the refrigeration capacity, and the decrease in the coefficient of performance can be prevented.

[0004] In general, in the manufacturing of semiconductor devices and the like, it is necessary to control the temperature of manufacturing equipment and the like so that the temperature of the processing location, measurement location, etc. of the workpiece by the manufacturing equipment reaches a predetermined temperature according to each manufacturing process. Conventionally, as a device for performing such temperature control, a temperature adjustment device is known that has a circulation path through which a heat medium circulates, and cools or heats a control target that requires temperature adjustment by the heat medium circulating through the circulation path. This type of temperature adjustment device includes a chiller of a vapor compression refrigeration cycle that cools the circulating heat medium, a heater that heats the cooled heat medium, and the like.

[0005] For example, Patent Document 2 discloses an area-specific parameter control method hybrid chiller used for controlling the temperature of various devices such as semiconductor manufacturing equipment and processes. The area-specific parameter control method hybrid chiller disclosed in the same document has a refrigeration cycle device including a compressor, a condenser, an expansion valve, and a heat exchanger, and a circulating liquid circulation circuit that circulates the circulating liquid supplied to the control target. The circulating liquid cooled by the refrigerant in the heat exchanger of the refrigeration cycle device is heated by a heater so as to reach a preset liquid temperature and then supplied to the control target.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, in the refrigeration cycle device of the above-described conventional technology, for example, in applications where cooling to an ultra-low temperature of minus 40°C or lower is required for the control target, there are points that need to be improved in order to achieve highly efficient cooling with a small environmental load such as ozone layer depletion and global warming.

[0008] For example, in a refrigeration cycle device that uses carbon dioxide as a refrigerant, like the prior art disclosed in Patent Document 1, by adopting, for example, a split cycle or the like, cooling operation in the refrigeration field such as a super showcase has been realized. However, the prior art refrigeration cycle device has a problem that it is difficult to use it for ultra-low temperature cooling with an even lower temperature.

[0009] Specifically, the triple point temperature of carbon dioxide is -56.6 °C, and the triple point pressure is 0.52 MPa. When the evaporation pressure of the refrigeration cycle device is set below the triple point pressure, the solidified carbon dioxide (dry ice) cannot be liquefied and adheres inside the refrigerant pipes of the evaporator etc., and it stops flowing. That is, under ultra-low temperature cooling conditions, clogging due to the adhesion of dry ice occurs in the expansion valve, evaporator, accumulator, refrigerant pipes, etc., and the compressor cannot suck up the refrigerant, and the circulation of the refrigerant cannot be maintained.

[0010] Also, in the processing process, measurement process, etc. of semiconductor device manufacturing, in order to improve accuracy and production efficiency, it is required to lower the temperature of the control target to -40 to -80 °C or lower, or even lower. However, the prior art refrigeration cycle device could not perform the required ultra-low temperature cooling using an environmentally friendly natural refrigerant.

[0011] In addition, the prior art refrigeration cycle device has points that should be improved in order to shorten the time required for temperature adjustment to improve the efficiency of the production process in semiconductor device manufacturing etc., and to reduce the energy consumption for temperature adjustment to achieve energy saving.

[0012] Specifically, in semiconductor device manufacturing and the like, there are cases where the temperature of a controlled object such as a manufacturing apparatus is changed corresponding to each process. For example, there may be a case where the set temperature of the controlled object has to be changed from -40°C to 130°C in a process where temperature control is being performed with the set temperature of the controlled object being -40°C. In such a case, with a conventional refrigeration cycle apparatus, it takes a long time to change the temperature of the controlled object to a predetermined set temperature. The time required to change the temperature of the controlled object in this way becomes a time loss in the manufacturing process.

[0013] That is, in a temperature adjustment apparatus using a conventional refrigeration cycle apparatus, in order to change the set temperature of the controlled object and raise the temperature, it was necessary to heat the circulating fluid with a heater such as an electric heater for a long time. The process of heating the circulating fluid with a heater or the like to raise the temperature of the controlled object is performed until the temperature of the controlled object reaches a stable set temperature. The time for heating the circulating fluid with a heater or the like to raise the temperature of the controlled object has been a waiting time during which processing processes, measurement processes, etc. cannot be performed in semiconductor device manufacturing and the like.

[0014] Further, a conventional temperature adjustment apparatus has a configuration in which the circulating fluid is cooled by an evaporator of a refrigeration cycle apparatus and then the cooled circulating fluid is heated to a predetermined temperature by a heater such as a heater. Therefore, there has been a problem that the energy consumed for heating the circulating fluid, that is, the amount of electric power consumed by a heater or the like, becomes large.

[0015] The present invention has been made to solve the above problems. An object of the present invention is to provide a refrigeration cycle apparatus that realizes ultra-low temperature cooling using a refrigerant mainly composed of carbon dioxide with a small ozone depletion potential (ODP) and global warming potential (GWP) and is excellent in environmental performance and safety.

[0016] Another object of the present invention is to provide a refrigeration cycle apparatus that can shorten the time required for temperature adjustment when changing the set temperature of a temperature adjustment apparatus or the like and improve productivity in semiconductor device manufacturing and the like.

[0017] Another object of the present invention is to provide a refrigeration cycle apparatus capable of reducing energy consumption in semiconductor device manufacturing and the like and achieving energy savings.

Means for Solving the Problems

[0018] The refrigeration cycle apparatus of the present invention is a vapor compression type refrigeration cycle apparatus, comprising a refrigerant circuit in which a compression means, a radiator, a throttling means, and an evaporator are sequentially connected and a refrigerant circulates. As the refrigerant, a mixed refrigerant containing at least one of dimethyl ether (DME, C2H6O) and difluoromethane (R32, CH2F2) with carbon dioxide as a main component is used, and the operation of the refrigeration cycle is performed with the pressure of the refrigerant at the inlet of the evaporator being equal to or lower than the triple point pressure of carbon dioxide. It is configured to be connected to a circulating liquid circuit in which a circulating liquid for adjusting the temperature of a control target circulates. The circulating liquid circuit has an openable and closable low-temperature path through which the circulating liquid flows through the evaporator in a heat-exchangeable manner with the refrigerant, and an openable and closable high-temperature path through which the circulating liquid flows through the radiator in a heat-exchangeable manner with the refrigerant. A high-temperature tank for storing the circulating liquid heated by the refrigerant in the radiator is provided in the high-temperature path. It is characterized by this.

Effects of the Invention

[0019] According to the refrigeration cycle device of the present invention, it is a vapor compression type refrigeration cycle device, which comprises a refrigerant circuit in which a compression means, a radiator, a throttling means and an evaporator are sequentially connected and the refrigerant circulates. As the refrigerant, a mixed refrigerant containing at least one of dimethyl ether and difluoromethane with carbon dioxide as the main component is used. The operation of the refrigeration cycle is performed with the pressure of the refrigerant at the inlet of the evaporator being equal to or lower than the triple point pressure of carbon dioxide. Thereby, even when cooling is required with the set temperature of the control target being an ultra-low temperature of minus 40°C or lower, high-performance cooling can be achieved without causing poor circulation due to solidification of the refrigerant. Therefore, ultra-low temperature cooling can be performed using a refrigerant containing carbon dioxide with excellent environmental performance. Specifically, the refrigerant is a mixed refrigerant containing at least one of dimethyl ether and difluoromethane with carbon dioxide as the main component. Therefore, the ozone depletion potential and the global warming potential of the refrigerant are extremely small, and the toxicity and flammability can also be at a level without problems. And since the triple point pressure of the mixed refrigerant is lower than the triple point pressure of carbon dioxide, even if the pressure of the refrigerant at the inlet of the evaporator is set to be equal to or lower than the triple point pressure of carbon dioxide, poor circulation due to solidification of the refrigerant will not occur. Therefore, the evaporation temperature of the refrigerant can be made lower than the triple point temperature of carbon dioxide, that is, minus 56.6°C, and high-performance ultra-low temperature cooling can be achieved.

[0020] Further, the refrigeration cycle device of the present invention comprises a high-temperature side refrigerant circuit in which a high-temperature side compression means, a high-temperature side radiator, a high-temperature side throttling means and a cascade heat exchanger are sequentially connected and the high-temperature side refrigerant circulates. The cascade heat exchanger may be provided in the radiator or the refrigerant circuit downstream of the radiator so as to perform heat exchange between the refrigerant and the high-temperature side refrigerant. With such a configuration, an environmentally friendly refrigerant can be used to operate a highly efficient binary refrigeration cycle to perform ultra-low temperature cooling.

[0021] Further, in the refrigeration cycle device of the present invention, the compression means includes a low-stage compressor and a high-stage compressor that further compresses the refrigerant compressed by the low-stage compressor. The throttling means includes a high-stage expansion valve and a low-stage expansion valve that further reduces the pressure of the refrigerant decompressed by the high-stage expansion valve. A receiver tank for separating the refrigerant into a gaseous-phase refrigerant and a liquid-phase refrigerant is provided in the refrigerant circuit between the high-stage expansion valve and the low-stage expansion valve. The gaseous-phase refrigerant separated by the receiver tank may be sucked into the high-stage compressor via a bypass path that bypasses the low-stage expansion valve, the evaporator, and the low-stage compressor and connects to the downstream of the low-stage compressor. By such a two-stage compression two-stage expansion intermediate gas-liquid separation type refrigeration cycle, even in the case of ultra-low temperature cooling, a high-performance cooling operation can be performed without clogging of the evaporator or the like due to freezing of the refrigerant. Specifically, the gaseous-phase refrigerant separated by the receiver tank at the intermediate pressure contains a large amount of carbon dioxide having a boiling temperature higher than that of a mixed component such as dimethyl ether. The gaseous-phase refrigerant having a large mass fraction of carbon dioxide is sucked into the high-stage compressor without being decompressed by the low-stage expansion valve and sent to the evaporator. Therefore, the low-pressure mixed refrigerant flowing through the evaporator has a smaller mass fraction of carbon dioxide and a lower triple point temperature. Thus, the adhesion of the solidified refrigerant is suppressed, and a high-performance ultra-low temperature cooling operation without clogging of the piping or the like is realized.

[0022] Further, the refrigeration cycle device of the present invention includes a control device that controls the rotational speed of at least one of the low-stage compressor and the high-stage compressor, and a liquid level sensor that detects the liquid level of the liquid-phase refrigerant in the receiver tank. The control device may control the rotational speed of at least one of the low-stage compressor and the high-stage compressor based on the liquid level of the liquid-phase refrigerant in the receiver tank detected by the liquid level sensor. With such a configuration, the amount of the gaseous-phase refrigerant sent from the receiver tank to the high-stage compressor via the bypass path can be suitably controlled. That is, it is possible to prevent the gaseous-phase refrigerant generated in the receiver tank from being decompressed by the low-stage expansion valve and flowing into the evaporator, and to prevent the liquid-phase refrigerant generated in the receiver tank from flowing through the bypass path and being sucked into the high-stage compressor. Therefore, a safe and high-performance ultra-low temperature cooling operation can be performed.

[0023] Further, the refrigeration cycle device of the present invention may include a liquid-gas heat exchanger that performs heat exchange between the refrigerant after heat dissipation by the radiator and the refrigerant after heat absorption by the evaporator. With such a configuration, by utilizing the latent heat of vaporization of the liquid-phase refrigerant that did not evaporate in the evaporator, the high-pressure refrigerant that has dissipated heat in the radiator can be further cooled, and the cold heat can be reused for cooling in the evaporator. Thereby, even when using a mixed refrigerant with a large temperature glide in the evaporator, the unevaporated liquid-phase refrigerant can be completely gasified, preventing the liquid-phase refrigerant from being sucked into the compressor. Also, the average evaporation temperature of the refrigerant in the evaporator can be lowered, enabling safe and high-performance ultra-low temperature cooling to be performed.

[0024] Moreover, in the refrigeration cycle device of the present invention, the refrigerant may have a carbon dioxide filling amount of 75 to 97% by mass with respect to the total filling amount. By including carbon dioxide in the mixed refrigerant at such a mass fraction, the ozone depletion potential and global warming potential of the refrigerant can be reduced, and the toxicity and flammability can be lowered. Therefore, ultra-low temperature cooling with excellent environmental performance and safety can be performed.

[0025] Furthermore, the refrigeration cycle device of the present invention is connected to a circulating liquid circuit through which a circulating liquid for adjusting the temperature of a control object circulates. The circulating liquid circuit has an openable and closable low-temperature path through which the circulating liquid flows through the evaporator in a heat-exchangeable manner with the refrigerant, and an openable and closable high-temperature path through which the circulating liquid flows through the radiator in a heat-exchangeable manner with the refrigerant. A high-temperature tank for storing the circulating liquid heated by the refrigerant in the radiator may be provided in the high-temperature path. With such a configuration, the refrigeration cycle device can supply a circulating liquid cooled or heated by the refrigerant to a control object such as a semiconductor manufacturing device and perform highly efficient temperature adjustment.

[0026] Specifically, when cooling of the control target is required, the low-temperature path of the circulating fluid circuit is opened so that the circulating fluid flows through the low-temperature path. Then, the circulating fluid flows through the low-temperature path and is cooled by utilizing the latent heat of the refrigerant that evaporates in the evaporator of the refrigeration cycle device. And the circulating fluid cooled by the refrigeration cycle device is heated to a predetermined temperature by the heater of the circulating fluid circuit and supplied to the control target at a suitable temperature so that the control target reaches the set temperature.

[0027] Also, when the temperature of the circulating fluid returning from the control target is low and it is necessary to significantly increase the temperature of the circulating fluid, the high-temperature path of the circulating fluid circuit is opened so that the circulating fluid flows through the high-temperature path. Thereby, the refrigeration cycle device can heat the circulating fluid by utilizing the heat dissipation of the refrigerant flowing through the radiator. And the circulating fluid heated by the radiator of the refrigeration cycle device is heated to a predetermined temperature by the heater of the circulating fluid circuit and supplied to the control target at a suitable temperature so that the control target reaches the accurate set temperature. In this way, since the circulating fluid can be heated by utilizing the heat dissipation of the radiator of the refrigeration cycle device, the energy consumed by the heater of the circulating fluid circuit can be reduced and highly efficient temperature adjustment can be performed.

[0028] In this way, the refrigeration cycle device of the present invention can perform highly efficient temperature adjustment with less waste heat loss by utilizing both the cold heat and the warm heat generated in the vapor compression refrigeration cycle.

[0029] Further, a high-temperature tank for storing the circulating fluid heated by the radiator in the refrigerant is provided in the high-temperature path. Thereby, for example, when the set temperature of the control target is changed due to a change in a processing step or the like and the temperature of the circulating fluid is significantly increased, the high-temperature circulating fluid stored in the high-temperature tank is supplied to the circulating fluid circuit, and the temperature of the circulating fluid circulating in the circulating fluid circuit can be rapidly increased to a predetermined temperature in a short time. Therefore, the time required for changing the set temperature can be significantly shortened, the time loss associated with the temperature change until starting a processing step, a measurement step, etc. can be reduced, and the productivity of a semiconductor device or the like can be improved.

Brief Description of the Drawings

[0030]

Figure 1

Figure 2

Figure 3

Figure 4

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Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0031] Hereinafter, a refrigeration cycle apparatus according to an embodiment of the present invention will be described in detail with appropriate reference to the drawings. Note that the illustrated embodiments do not limit the present invention, but merely show an example of the embodiments of the present invention.

[0032] FIG. 1 is a diagram showing a schematic configuration of a refrigeration cycle apparatus 1 according to an embodiment of the present invention. Referring to FIG. 1, the refrigeration cycle apparatus 1 is an apparatus that performs cooling or heating using a vapor compression refrigeration cycle. Specifically, the refrigeration cycle apparatus 1 is an example of an apparatus that operates a refrigeration cycle of single-stage compression and single-stage expansion.

[0033] Specifically, the refrigeration cycle apparatus 1 includes a refrigerant circuit 10 in which a compressor 11, a radiator 12, an expansion valve 14, and an evaporator 15 are sequentially connected via refrigerant pipes. The refrigerant circuit 10 is a closed circuit in which the refrigerant circulates and the operation of the vapor compression refrigeration cycle is performed.

[0034] The compressor 11 is a compressing means that compresses the refrigerant and sends it to the radiator 12. As the compressor 11, various types of compression devices such as a rotary type, a scroll type, a reciprocating type, and a screw type can be adopted.

[0035] In particular, the rotary compressor 11 is suitable when configuring a compact refrigeration cycle apparatus 1 with a small cooling capacity. Further, the compressor 11 may be a two-stage compression type. Adopting a two-stage compression type as the compressor 11 is suitable for compressing a mixed refrigerant mainly composed of carbon dioxide, whose pressure after compression is higher than that of other refrigerants.

[0036] The radiator 12 is a heat exchanger that cools the refrigerant compressed by the compressor 11 and heated to a high pressure and high temperature. The heat transferred from the refrigerant by heat exchange in the radiator 12 may be released to the outside, or may be transferred to and utilized by another heat medium that requires heating.

[0037] For example, the radiator 12 may be an air-cooled condenser or a gas cooler that releases the heat of the refrigerant to the outside. The radiator 12 may be provided with a blower fan 16 that sends air for heat exchange with the refrigerant.

[0038] The radiator 12 may be a fin-and-tube type heat exchanger, although not shown in the figure. That is, the radiator 12 has a plurality of tubes such as copper tubes through which the refrigerant flows, and a plurality of aluminum fins provided in parallel therewith, and the tubes are inserted into holes formed in the fins.

[0039] Note that the radiator 12 may be a water-cooled heat exchanger. Also, as the radiator 12, various types of heat exchangers such as plate type, shell-and-tube type, double-tube type can be adopted. In particular, the plate type heat exchanger is preferable because it has high heat exchange efficiency and can make the radiator 12 compact.

[0040] Also, although details will be described later, the radiator 12 may be a heat exchanger that exchanges heat with the circulating liquid in the circulating liquid circuit 20 (see FIG. 9). Thereby, the waste heat from the refrigerant in the radiator 12 can be effectively utilized for heating the control target 46 (see FIG. 9) such as a semiconductor manufacturing apparatus.

[0041] The expansion valve 14 is a throttling means for reducing the pressure of the high-pressure refrigerant that has passed through the radiator 12 and become low-temperature. Also, the expansion valve 14 has a function of adjusting the flow of the refrigerant. As the expansion valve 14, various types of throttling means such as an electronic expansion valve, a temperature automatic expansion valve, and a capillary tube can be adopted. By adopting an electronic expansion valve as the expansion valve 14, the cooling and heating by the refrigeration cycle device 1 can be controlled with high performance.

[0042] The evaporator 15 is a heat exchanger in which the low-pressure liquid refrigerant evaporates, and the cooling target such as the circulating liquid is cooled by the latent heat of evaporation. As the evaporator 15, various types of heat exchangers such as plate type, double-tube type, tube contact type, and shell-and-tube type can be adopted.

[0043] In particular, the plate type heat exchanger is preferable because it has high heat exchange efficiency and can make the evaporator 15 compact. Also, the double-tube type and the tube contact type are excellent in that they are easy to manufacture and process, and suitable pressure resistance strength can be easily obtained.

[0044] The refrigerant pipe downstream of the evaporator 15 is connected to the compressor 11 via an accumulator 57 or the like (see FIG. 4). With the above configuration, a refrigerant circuit 10 of the refrigeration cycle apparatus 1 in which the compressor 11, the radiator 12, the expansion valve 14, and the evaporator 15 are sequentially connected is formed.

[0045] Also, for example, downstream of the compressor 11 in the refrigerant circuit 10, a refrigerant temperature sensor 18 for measuring the temperature of the refrigerant protruding from the compressor 11 is provided. A plurality of refrigerant temperature sensors 18 may be provided to measure the refrigerant temperature at other locations such as the inlet and outlet of the evaporator 15.

[0046] For example, at the inlet of the evaporator 15 in the refrigerant circuit 10, a pressure sensor 19 for measuring the pressure of the refrigerant is provided. The pressure sensor 19 may be provided at a plurality of locations downstream of the evaporator 15, downstream of the compressor 11, and other refrigerant circuits 10.

[0047] The refrigeration cycle apparatus 1 includes a control device 43 for controlling each component device. The control device 43 is a control means including a microprocessor, and executes a predetermined calculation to control the operation of the refrigeration cycle of the refrigeration cycle apparatus 1.

[0048] Specifically, sensors such as a refrigerant temperature sensor 18 for measuring the temperature of the refrigerant and a pressure sensor 19 for measuring the pressure of the refrigerant are connected to the input of the control device 43. To the output of the control device 43, the compressor 11, the expansion valve 14, the blower fan 16, etc. are connected.

[0049] Also, the control device 43 is provided with an input device 44 for inputting set temperatures of cooling and heating targets and other operation information, and a display device 45 for displaying temperature information and other control information of each part. Note that other sensors, information input devices, display devices, control target devices, recording devices, etc. (not shown) may be connected to the control device 43.

[0050] The control device 43 executes a predetermined calculation based on the temperature of the refrigerant measured by the refrigerant temperature sensor 18, the pressure of the refrigerant measured by the pressure sensor 19, and other input information, and controls the compressor 11, the expansion valve 14, etc. Thereby, the refrigeration cycle device 1 can perform high-performance ultra-low temperature cooling.

[0051] The refrigerant used in the refrigeration cycle device 1 is a mixed refrigerant containing at least one of dimethyl ether and difluoromethane with carbon dioxide as the main component. And in the refrigeration cycle device 1, the operation of the vapor compression refrigeration cycle is performed with the pressure of the refrigerant at the inlet of the evaporator 15 being equal to or lower than the triple point pressure P1 of carbon dioxide (see Fig. 2).

[0052] Fig. 2 is a graph showing the relationship between the mass fraction of carbon dioxide, the triple point pressure P2 and the triple point temperature T2 in a mixed refrigerant of carbon dioxide and dimethyl ether as an example of the refrigerant according to the embodiment of the present invention. In Fig. 2, for comparison, the triple point pressure P1 and the triple point temperature T1 of carbon dioxide, that is, the triple point pressure P1 and the triple point temperature T1 when carbon dioxide is 100% by mass, are shown by a one-dot chain horizontal line.

[0053] Fig. 3 is a graph showing the relationship between the mass fraction of carbon dioxide, the triple point pressure P2, the triple point temperature T2, the evaporation pressure P3 and the evaporator outlet temperature T3 in a mixed refrigerant of carbon dioxide and dimethyl ether.

[0054] Referring to Fig. 2 and Fig. 3, for example, the triple point temperature T2 of a mixed refrigerant with a mass fraction of carbon dioxide of 91% by mass, that is, a mixed refrigerant in which 9% by mass of dimethyl ether is added to carbon dioxide, is -75°C.

[0055] That is, the triple point temperature T2 of a mixed refrigerant obtained by mixing carbon dioxide and dimethyl ether at a mixing ratio of 91:9 is -75°C, which is lower than the triple point temperature T1 of carbon dioxide, which is -56.6°C.

[0056] If the evaporation pressure P3 of the refrigerant in the refrigeration cycle is controlled to be, for example, from 0.1901 to 0.518 MPa using such a mixed refrigerant, the cooling effect up to a refrigerant temperature of minus 75 °C can be utilized without causing poor circulation due to the adhesion of solidified carbon dioxide.

[0057] In addition, it is desirable that the amount of carbon dioxide enclosed in the refrigerant is 75 to 97% by mass with respect to the total enclosed amount. That is, the mixing ratio of carbon dioxide and dimethyl ether is preferably from 75:25 to 97:3. With such a mixing ratio, the ozone depletion potential and the global warming potential of the refrigerant can be reduced, and the toxicity and flammability can be lowered. Thereby, the refrigeration cycle device 1 can perform a high-performance ultra-low temperature cooling operation with excellent environmental performance and safety.

[0058] That is, carbon dioxide, which is the main component of the refrigerant, has an ozone depletion potential of 0, a global warming potential of 1, no toxicity, and is non-flammable. Dimethyl ether has a small ozone depletion potential and a small global warming potential, and has toxicity and flammability. However, the refrigerant mixed with carbon dioxide has an extremely low ozone depletion potential and a global warming potential, and also has only a slight toxicity and flammability, and there is no problem with safety.

[0059] In addition, difluoromethane is a hydrofluorocarbon refrigerant, has an ozone depletion potential of 0, a low global warming potential (675), no toxicity, and is slightly flammable. The mixed refrigerant of carbon dioxide and difluoromethane is also a refrigerant with excellent environmental performance and safety and a low triple point temperature.

[0060] In this way, the refrigeration cycle device 1 can perform ultra-low temperature cooling safely and with high performance by using a mixed refrigerant having 75 to 97% by mass of carbon dioxide as the main component and containing at least one of dimethyl ether and difluoromethane as the mixed component.

[0061] Next, with reference to FIGS. 4 to 8, an example of an embodiment in which components and refrigerant paths are added or changed based on the configuration of the refrigeration cycle apparatus 1 will be described in detail. Note that components having the same or similar operations and effects as those of the embodiments already described are denoted by the same reference numerals, and the description thereof will be omitted.

[0062] FIG. 4 is a diagram showing a refrigeration cycle apparatus 101 according to another embodiment of the present invention. The refrigeration cycle apparatus 101 is, for example, an apparatus that operates a refrigeration cycle of single-stage two-stage compression and single-stage expansion. The various configurations described below can also be adopted in the refrigeration cycle apparatus 1 that operates a refrigeration cycle of single-stage single-stage compression and single-stage expansion already described.

[0063] With reference to FIG. 4, a drier 56 that adsorbs moisture in the refrigerant may be provided upstream of the suction port of the compressor 11. Thereby, it is possible to prevent clogging of the refrigerant piping or the like and damage to the compressor 11 or the like due to freezing of the moisture in the refrigerant.

[0064] Further, an accumulator 57 capable of storing unevaporated liquid-phase refrigerant may be provided upstream of the suction port of the compressor 11. Thereby, it is possible to prevent the liquid-phase refrigerant that could not be evaporated in the evaporator 15 from being sucked into the compressor 11 and damaging the compressor 11.

[0065] Further, the compressor 11 may be a two-stage compression type compressor including a first-stage compression mechanism 50 and a second-stage compression mechanism 51 that further compresses the refrigerant compressed by the first-stage compression mechanism 50. Thereby, in the refrigeration cycle apparatus 101 using a refrigerant mainly composed of carbon dioxide, high-performance refrigerant compression can be performed from a low-pressure evaporation pressure to a high pressure capable of ultra-low temperature cooling.

[0066] In addition, the refrigeration cycle device 101 may be provided with an economizer 55 (split heat exchanger) that reduces the high-pressure refrigerant that has been split to an intermediate pressure and exchanges heat with the high-pressure main refrigerant. Specifically, a splitting point 52 that splits the high-pressure refrigerant into a main refrigerant and a sub-refrigerant is provided in the refrigerant circuit 10 downstream of the radiator 12. The splitting point 52 and the intermediate pressure section of the two-stage compression type compressor are connected by a sub-pipe 53 through which the sub-refrigerant flows. The sub-pipe 53 is provided with a sub-expansion valve 54 that reduces the pressure of the sub-refrigerant to the intermediate pressure, and an economizer 55 that exchanges heat between the sub-refrigerant decompressed by the sub-expansion valve 54 and the main refrigerant.

[0067] The intermediate-pressure sub-refrigerant that has exchanged heat in the economizer 55 flows, for example, into the intermediate pressure of the two-stage compression type compressor section , that is, between the first-stage compression mechanism 50 and the second-stage compression mechanism 51. Thereby, in the refrigeration cycle device 101 using a refrigerant mainly composed of carbon dioxide, the specific enthalpy of the refrigerant flowing into the evaporator 15 can be reduced, and high-performance cooling operation can be performed in an ultra-low temperature range.

[0068] In addition, an oil separator (not shown) may be provided in the high-pressure refrigerant pipe downstream of the compressor 11. The oil separated by the oil separator is returned, via an oil return pipe (not shown) having throttling means such as a capillary tube (not shown), upstream of the compressor 11, for example, upstream of the accumulator 57. With such a configuration, the compressor 11 can be protected with an appropriate amount of oil, and the reliability of refrigerant compression can be enhanced.

[0069] In addition, the refrigerant circuit 10 may be provided with a gas injection pipe (not shown) that connects the high-pressure refrigerant pipe downstream of the compressor 11 and the low-pressure refrigerant pipe upstream of the compressor 11. The gas injection pipe may be provided with throttling means such as an injection expansion valve (not shown) that opens and closes the pipe to control the flow of the refrigerant.

[0070] The gas injection pipe decompresses the high-temperature refrigerant compressed by the compressor 11 and flows it to the suction port of the compressor 11. Thereby, the capacity of the refrigeration cycle can be controlled according to the cooling load, the liquid-phase refrigerant that has not evaporated in the evaporator 15 can be evaporated, and the compressor 11 can be prevented from sucking the liquid-phase refrigerant.

[0071] FIG. 5 is a diagram showing a refrigeration cycle device 201 according to another embodiment of the present invention. As shown in FIG. 5, the refrigeration cycle device 201 is a device that operates a binary refrigeration cycle. Specifically, the refrigeration cycle device 201 includes a refrigerant circuit 10 as a low-temperature side refrigerant circuit and a high-temperature side refrigerant circuit 60.

[0072] The refrigerant circuit 10 constituting the low-temperature side refrigerant circuit may have substantially the same configuration as the refrigeration cycle devices 1, 101, etc. already described. That is, as basic components, a compressor 11, a radiator 12, an expansion valve 14, and an evaporator 15 are connected to the refrigerant circuit 10. Further, a cascade heat exchanger 65 for heat exchange between the refrigerant flowing through the refrigerant circuit 10 and the high-temperature side refrigerant flowing through the high-temperature side refrigerant circuit 60, that is, the binary side refrigerant, is provided downstream of the radiator 12 in the refrigerant circuit 10.

[0073] Note that the radiator 12 may be provided so as to exchange heat with a circulating liquid that adjusts the temperature of the control target 46 (see FIG. 9). That is, the refrigerant flowing through the radiator 12 heats the circulating liquid. Further, the radiator 12 may be provided inside a high-temperature tank 39 (see FIG. 9) that stores the heated circulating liquid. Details will be described later.

[0074] Further, when the refrigeration cycle device 201 is used only for cooling applications and the radiator 12 for heating a circulating liquid or the like is not required, the radiator 12 may be used as a cascade heat exchanger 65 that radiates heat to the high-temperature side refrigerant of the high-temperature side refrigerant circuit 60.

[0075] The high-temperature-side refrigerant circuit 60 is a circuit in which a high-temperature-side compressor 61 as high-temperature-side compression means, a high-temperature-side radiator 62, a high-temperature-side expansion valve 64 as high-temperature-side throttling means, and a cascade heat exchanger 65 are sequentially connected, and the high-temperature-side refrigerant circulates.

[0076] The high-temperature-side compressor 61 is compression means for compressing the high-temperature-side refrigerant and sending it to the high-temperature-side radiator 62. As the high-temperature-side compressor 61, various types of compression devices such as rotary, scroll, reciprocating, and screw types can be adopted. Further, the high-temperature-side compressor 61 may be of a two-stage compression type.

[0077] The high-temperature-side radiator 62 is a heat exchanger for cooling the high-temperature-side refrigerant compressed by the high-temperature-side compressor 61 to become high-pressure and high-temperature. The heat transferred from the high-temperature-side refrigerant by heat exchange in the high-temperature-side radiator 62 may be released to the outside, or may be transferred to and utilized by another heat medium that requires heating.

[0078] For example, the high-temperature-side radiator 6 2 may be an air-cooled condenser or gas cooler that releases the heat of the high-temperature-side refrigerant to the outside. The high-temperature-side radiator 6 2 may be provided with a high-temperature-side blower fan 66 for sending air that exchanges heat with the high-temperature-side refrigerant.

[0079] Further, although not shown in the figure, the high-temperature-side radiator 62 may also be a fin-and-tube type heat exchanger. That is, the radiator 12 has a plurality of tubes such as copper tubes through which the high-temperature-side refrigerant flows, and a plurality of aluminum fins provided in parallel therewith, and the tubes are inserted into holes formed in the fins.

[0080] Note that the high-temperature-side radiator 62 may be a water-cooled heat exchanger. Further, as the high-temperature-side radiator 62, various types of heat exchangers such as plate type, shell-and-tube type, and double-tube type can be adopted.

[0081] Further, although details will be described later, the high-temperature-side radiator 62 may be provided with a heat exchanger that exchanges heat with the circulating liquid of the circulating liquid circuit 20 (see FIG. 9). Thereby, the high-temperature-side radiator 62 The waste heat from the high-temperature side refrigerant in it can be effectively utilized for heating the control target 46 such as a semiconductor manufacturing apparatus.

[0082] The high-temperature side expansion valve 64 is a throttling means for reducing the pressure of the high-pressure high-temperature side refrigerant that has passed through the high-temperature side radiator 62 and become low-temperature. Further, the high-temperature side expansion valve 64 has a function of adjusting the flow of the refrigerant. As the high-temperature side expansion valve 64, various types of throttling means such as an electronic expansion valve, a temperature automatic expansion valve, and a capillary tube can be adopted. By adopting an electronic expansion valve as the high-temperature side expansion valve 64, the cooling and heating by the refrigeration cycle device 201 can be controlled with high performance.

[0083] The cascade heat exchanger 65 is a heat exchanger in which the liquid phase of the high-temperature side refrigerant becomes low-pressure and evaporates, and the refrigerant in the low-temperature side refrigerant circuit, that is, the refrigerant circuit 10, is cooled by the latent heat of evaporation. As the cascade heat exchanger 65, various types of heat exchangers such as a plate type, a double pipe type, and a tube contact type can be adopted.

[0084] In particular, the plate type heat exchanger is preferable because it has high heat exchange efficiency and can make the cascade heat exchanger 65 compact. Also, the double pipe type and the tube contact type are excellent in that they are easy to manufacture and process and can easily obtain suitable pressure resistance strength.

[0085] The refrigerant enclosed in the refrigerant circuit 10 which is the low-temperature side refrigerant circuit is a mixed refrigerant equivalent to the above-described refrigeration cycle device 1. That is, the refrigerant in the refrigerant circuit 10 is a refrigerant in which at least one of dimethyl ether and difluoromethane is mixed with carbon dioxide as the main component.

[0086] The high-temperature side refrigerant enclosed in the high-temperature side refrigerant circuit 60 may be carbon dioxide, a hydrofluorocarbon-based refrigerant such as R404A, or a hydrofluoroolefin-based refrigerant such as R448A. From the viewpoint of green transformation (GX), carbon dioxide is most preferable as the high-temperature side refrigerant.

[0087] In the refrigeration cycle device 201, an operation of a binary refrigeration cycle is performed, in which a low-temperature side refrigeration cycle using a refrigerant obtained by mixing at least one of dimethyl ether and difluoromethane with carbon dioxide is taken as the single-element side, and a high-temperature side refrigeration cycle using a high-temperature side refrigerant is taken as the binary side.

[0088] The low-temperature side refrigeration cycle operating in the refrigerant circuit 10, that is, the single-element side refrigeration cycle, operates with the refrigerant pressure at the inlet of the evaporator 15 being equal to or lower than the triple point pressure P1 of carbon dioxide (see FIG. 2). Thereby, the refrigeration cycle device 201 can efficiently perform ultra-low temperature cooling.

[0089] Although not shown, the refrigeration cycle device 201, the refrigeration cycle device 301 (see FIG. 6) described later, and the refrigeration cycle device 401 (see FIG. 7) may be provided with a heat exchanger corresponding to the economizer 55 of the refrigeration cycle device 101 in the high-temperature side refrigerant circuit 60 that constitutes the binary side refrigeration cycle. That is, the high-temperature side refrigerant circuit 60 may be configured to operate a split cycle, that is, a two-stage compression one-stage expansion intermediate cooling cycle.

[0090] FIG. 6 is a diagram showing a refrigeration cycle device 301 according to another embodiment of the present invention. Referring to FIG. 6, the refrigeration cycle device 301 is a device of a binary refrigeration cycle that employs two-stage compression and two-stage expansion on the single-element side.

[0091] Specifically, the refrigeration cycle device 301 includes, as compression means, a low-stage compressor 70 that compresses the low-pressure refrigerant evaporated in the evaporator 15 to an intermediate pressure, and a high-stage compressor 71 that further compresses the intermediate-pressure refrigerant compressed by the low-stage compressor 70.

[0092] The refrigeration cycle device 301 also includes, as throttling means, a high-stage expansion valve 72 that reduces the pressure of the high-pressure refrigerant radiated by the cascade heat exchanger 65 to an intermediate pressure, and a low-stage expansion valve 73 that further reduces the pressure of the intermediate-pressure refrigerant decompressed by the high-stage expansion valve 72.

[0093] In the refrigerant circuit 10 between the high-stage expansion valve 72 and the low-stage expansion valve 73, a receiver tank 74 for separating the refrigerant at the intermediate pressure into a gaseous-phase refrigerant and a liquid-phase refrigerant is provided. A bypass path 75 is connected to the receiver tank 74. The bypass path 75 bypasses the low-stage expansion valve 73, the evaporator 15, and the low-stage compressor 70, and connects the receiver tank 74 to a confluence point 77 of the refrigerant circuit 10 at the intermediate pressure between the low-stage compressor 70 and the high-stage compressor 71.

[0094] With such a configuration, the gaseous-phase refrigerant separated by the receiver tank 74 bypasses the low-stage expansion valve 73, the evaporator 15, and the low-stage compressor 70 via the bypass path 75 from the receiver tank 74, flows to the confluence point 77 downstream of the low-stage compressor 70, and is sucked by the high-stage compressor 71.

[0095] And the liquid-phase refrigerant separated by the receiver tank 74 is depressurized by the low-stage expansion valve 73 and sent to the evaporator 15, evaporates in the evaporator 15, is sucked by the low-stage compressor 70 and compressed to the intermediate pressure, and then merges with the gaseous-phase refrigerant flowing through the bypass path 75 at the confluence point 77 and is sucked by the high-stage compressor 71.

[0096] With such a two-stage compression and two-stage expansion intermediate gas-liquid separation type refrigeration cycle, even for ultra-low temperature cooling, a high-performance cooling operation can be performed without clogging of the evaporator 15 or the like due to freezing of the refrigerant.

[0097] Specifically, the gaseous-phase refrigerant separated by the receiver tank 74 at the intermediate pressure contains a large amount of carbon dioxide with a boiling temperature higher than that of mixed components such as dimethyl ether. And the gaseous-phase refrigerant with a large mass fraction of carbon dioxide is sucked into the high-stage compressor 71 without being depressurized by the low-stage expansion valve 73 and sent to the evaporator 15. Therefore, the low-pressure mixed refrigerant flowing through the evaporator 15 has a smaller mass fraction of carbon dioxide and a lower triple point temperature T2 (see Figure 2). Thus, the adhesion of the solidified refrigerant is suppressed, and a high-performance ultra-low temperature cooling operation without clogging of the piping or the like is realized.

[0098] Note that the bypass path 75 is provided with a check valve 76 that allows the refrigerant to flow only in the direction from the receiver tank 74 to the confluence point 77. This prevents the refrigerant at an intermediate pressure compressed by the low-stage compressor 70 from returning to the receiver tank 74 via the bypass path 75.

[0099] The receiver tank 74 is also provided with a liquid level sensor 78 that detects the liquid level or liquid volume of the liquid-phase refrigerant in the receiver tank 74. The liquid level sensor 78 is connected to the control device 43 (see FIG. 1). As the liquid level sensor 78, various level sensors or level switches such as an electric resistance type, a magnetic type, a temperature type, a float type, an optical type, a capacitance type, an ultrasonic type, etc. can be adopted. For example, the receiver tank 74 may be provided with liquid level sensors 78 for detecting the liquid-phase refrigerant at a plurality of upper and lower positions.

[0100] The control device 43 controls the rotational speed of at least one of the low-stage compressor 70 and the high-stage compressor 71 based on the liquid level of the liquid-phase refrigerant in the receiver tank 74 detected by the liquid level sensor 78. Specifically, when the amount of the liquid-phase refrigerant in the receiver tank 74 is more than a predetermined value, for example, when the liquid-phase refrigerant is detected by the uppermost liquid level sensor 78, the control device 43 performs control to lower the rotational speed of the high-stage compressor 71 or control to increase the rotational speed of the low-stage compressor 70 or both controls.

[0101] On the other hand, when the amount of the liquid-phase refrigerant in the receiver tank 74 is less than a predetermined value, for example, when the liquid-phase refrigerant is not detected by the lowermost liquid level sensor 78, the control device 43 performs control to increase the rotational speed of the high-stage compressor 71 or control to lower the rotational speed of the low-stage compressor 70 or both controls.

[0102] As a result, the amount of the gaseous refrigerant sent from the receiver tank 74 to the high-stage compressor 71 via the bypass path 75 can be suitably controlled. That is, it is possible to prevent the gaseous refrigerant generated in the receiver tank 74 from being depressurized by the low-stage expansion valve 73 and flowing into the evaporator 15, and to prevent the liquid-phase refrigerant generated in the receiver tank 74 from flowing through the bypass path 75 and being sucked into the high-stage compressor 71. Therefore, a safe and high-performance ultra-low temperature cooling operation can be performed.

[0103] Further, an intermediate radiator 79 may be provided downstream of the low-stage compressor 70. The intermediate radiator 79 may be provided with an intermediate blower fan 80 for sending air that exchanges heat with the refrigerant. The intermediate radiator 79 is a heat exchanger that exchanges heat between the refrigerant compressed to an intermediate pressure and heated by the low-stage compressor 70 and, for example, outside air or a circulating liquid, etc., to lower the temperature of the refrigerant. By providing the intermediate radiator 79, the temperature of the refrigerant compressed to a high pressure by the high-stage compressor 71 can be lowered at the intermediate pressure stage, preventing damage to the compressor 11 due to overheating, and enabling safe high-pressure compression to be performed.

[0104] In the refrigeration cycle device 301, in addition to the bypass path 75, an injection pipe (not shown) connecting the receiver tank 74 and the low-stage compressor 70 may be provided. The injection pipe may have, for example, a gas injection path (not shown) connected to the upper part of the receiver tank 74 and a liquid injection path (not shown) connected to the lower part of the receiver tank 74. Further, throttle means such as solenoid valves (not shown) for opening and closing the pipes to control the flow of the refrigerant are provided in the gas injection path and the liquid injection path of the injection pipe, respectively.

[0105] By providing such an injection pipe, the gaseous refrigerant or liquid-phase refrigerant separated in the receiver tank 74 can be sent to the low-stage compressor 70. Thereby, the low-stage compressor 70 can be cooled according to the operating conditions, and damage to the low-stage compressor 70 due to overheating can be prevented.

[0106] FIG. 7 is a diagram showing a refrigeration cycle device 401 according to another embodiment of the present invention. Referring to FIG. 7, the refrigeration cycle device 401 is a binary refrigeration cycle device that employs a liquid-gas heat exchanger 81 as the primary unit.

[0107] The liquid-gas heat exchanger 81 is a heat exchanger that performs heat exchange between the refrigerant after heat dissipation by the radiator 12 or the cascade heat exchanger 65 and the refrigerant after heat absorption by the evaporator 15. As the liquid-gas heat exchanger 81, various types of heat exchangers such as plate type, shell and tube type, and double tube type can be employed.

[0108] FIG. 8 is a graph showing the temperature glide of the refrigerant in the evaporator 15 of the refrigeration cycle device 401 and the subcooling of the high-pressure refrigerant in the liquid-gas heat exchanger 81. In FIG. 8, the horizontal axis represents the quality (dryness) of the refrigerant, the vertical axis represents the temperature, and shows the evaporation temperature T4 of the refrigerant in the evaporator 15, the temperature T5 of the circulating liquid, as well as the evaporation temperature T6 of the low-pressure refrigerant and the temperature T7 of the high-pressure refrigerant in the liquid-gas heat exchanger 81. Note that in FIG. 8, the arrows indicate the flow direction of the refrigerant or the circulating liquid.

[0109] Referring to FIGS. 7 and 8, in the vicinity of the evaporation completion region where the quality of the refrigerant increases, specifically, in the region where the quality is about 0.9 to 1.0, the evaporation temperature T6 of the refrigerant increases significantly. Therefore, in a configuration where the refrigerant flowing out from the evaporator 15 is sucked and compressed by the compressor 11 without cooling by the liquid-gas heat exchanger 81, it is difficult to cool the circulating liquid to be cooled to a low temperature. That is, in the vicinity of the evaporation completion region where the evaporation temperature T6 (T4) of the refrigerant rapidly increases, the circulating liquid cannot be cooled by the high-temperature refrigerant to lower its temperature T5.

[0110] Also, when the refrigeration cycle is operated to cool the circulating liquid to be cooled and lower its temperature T5, the liquid-phase refrigerant that could not be evaporated flows out from the evaporator 15, and this liquid-phase refrigerant is sucked into the compressor 11. Therefore, there is a risk of damage to the compressor 11 due to the suction of the unevaporated liquid-phase refrigerant.

[0111] In the refrigeration cycle device 401, since the liquid-gas heat exchanger 81 is provided, the latent heat of vaporization of the liquid-phase refrigerant that has not vaporized in the evaporator 15 can be utilized to further cool the high-pressure refrigerant after heat dissipation in the radiator 12 or the cascade heat exchanger 65. That is, subcooling is performed to lower the temperature T7 of the high-pressure refrigerant by utilizing the latent heat of vaporization that was not utilized in the evaporator 15, and the cold heat can be reused for cooling in the evaporator 15.

[0112] Thereby, even when using a mixed refrigerant with a large temperature glide in the evaporator 15, the unvaporized liquid-phase refrigerant can be completely gasified, preventing the liquid-phase refrigerant from being sucked into the compressor 11. Also, the average evaporation temperature of the refrigerant in the evaporator 15, that is, the average value of the evaporation temperature T4, can be lowered, enabling safe and high-performance ultra-low temperature cooling.

[0113] Next, with reference to FIGS. 9 and 10, the temperature adjustment device 2 using the refrigeration cycle devices 1, 101, 201, 301, 401, etc. according to the embodiments of the present invention will be described in detail. Components having the same or similar operations and effects as those already described in the embodiments are denoted by the same reference numerals, and their descriptions are omitted.

[0114] FIG. 9 is a diagram showing the temperature adjustment device 2 using the refrigeration cycle devices 1, 101, 201, 301, 401, etc. FIG. 10 is a diagram showing the control system of the temperature adjustment device 2. The temperature adjustment device 2 is a device used to adjust the temperature of a control object 46, such as various manufacturing devices like semiconductor manufacturing devices, or various measuring devices used in the manufacturing process of semiconductor devices, etc., to a predetermined temperature according to the process.

[0115] The temperature adjustment device 2 includes a circulating liquid circuit 20 that circulates the circulating liquid cooled or heated by the refrigerant in the refrigerant circuit 10 of the refrigeration cycle device 1 to the control object 46 to adjust the temperature of the control object 46.

[0116] The circulating fluid that circulates through the circulation fluid circuit 20 includes, for example, water. The circulating fluid is cooled or heated by the refrigerant flowing through the refrigerant circuit 10, and is heated to a suitable temperature by the heater 26 of the circulation fluid circuit 20 and supplied to the control target 46 such as a semiconductor manufacturing apparatus. Thereby, the control target 46 is cooled or heated by the circulating fluid adjusted to a suitable temperature, and is controlled to reach a suitable temperature suitable for each manufacturing process, measurement process, etc.

[0117] The radiator 12 of the refrigeration cycle apparatus 1 is provided, for example, inside the high-temperature tank 39 in which the circulating fluid is stored, and has a plurality of tubes through which the refrigerant flows, although not shown. The tubes are, for example, steel pipes or the like.

[0118] Specifically, the tubes of the radiator 12 have an inlet at the upper side and an outlet at the lower side so that the refrigerant flows from top to bottom, and are wound in a substantially spiral shape, for example, and are provided inside the high-temperature tank 39. With such a configuration, the refrigerant flowing through the radiator 12 can efficiently heat the circulating fluid in the high-temperature tank 39.

[0119] For example, even when the circulating fluid in the high-temperature tank 39 is not supplied to the control target 46, that is, when the circulating fluid does not flow through the high-temperature path 38 of the circulation fluid circuit 20 provided with the high-temperature tank 39, the refrigerant flowing through the radiator 12 can heat the circulating fluid in the high-temperature tank 39.

[0120] That is, according to such a configuration, in order to heat the circulating fluid with the radiator 12, it is possible to heat the circulating fluid stored in the high-temperature tank 39 to a high temperature with the radiator 12 without providing a circulation pump or the like that causes the circulating fluid to flow through the high-temperature path 38 of the circulation fluid circuit 20.

[0121] Therefore, when the refrigeration cycle apparatus 1 is performing an operation of cooling the circulating fluid by utilizing the latent heat of vaporization of the evaporator 15, it is possible to effectively utilize the waste heat from the radiator 12 to heat the circulating fluid in the high-temperature tank 39 to a high temperature without circulating the circulating fluid through the high-temperature path 38.

[0122] Note that the radiator 12 may be provided outside the high-temperature tank 39 as long as the refrigerant can exchange heat with the circulating liquid.

[0123] As described above, a cascade heat exchanger 65 (see FIG. 5) that cools the refrigerant after heating the circulating liquid in the radiator 12 in a binary-side refrigeration cycle may be provided downstream of the radiator 12. Further, a second radiator 13 and a second blower fan 17 that release the heat of the refrigerant after heating the circulating liquid in the radiator 12 to the outside may be provided downstream of the radiator 12.

[0124] Since the cascade heat exchanger 65 or the second radiator 13 is provided downstream of the radiator 12, the refrigerant whose temperature has decreased after heating the circulating liquid in the radiator 12 can be cooled to a lower temperature.

[0125] Also, even when the circulating liquid in the high-temperature tank 39 becomes high temperature and it is not necessary to heat the circulating liquid with the refrigerant flowing through the radiator 12, the high-temperature refrigerant that has passed through the radiator 12 can be cooled to a low temperature by heat dissipation in the cascade heat exchanger 65 or the second radiator 13. Thereby, even when the inside of the high-temperature tank 39 is filled with the high-temperature circulating liquid, the cooling capacity of the refrigeration cycle device, that is, the ability to cool the circulating liquid by utilizing the latent heat of vaporization of the refrigerant in the evaporator 15, is exhibited.

[0126] As described above, the refrigerant used in the refrigeration cycle device 1 is a mixed refrigerant mainly composed of carbon dioxide. And the refrigerant can efficiently heat the circulating liquid to a high temperature at the supercritical pressure of carbon dioxide in the radiator 12.

[0127] Specifically, the circulating liquid can be heated by the radiator 12 of the refrigeration cycle device 1 up to a high temperature range that was impossible with condensers of conventional chillers or the like using hydrofluorocarbon-based refrigerants, hydrofluoroolefin-based refrigerants, or mixed refrigerants thereof.

[0128] For example, even when the set temperature is changed to a high temperature of 130°C for changes in processing steps or the like, the refrigeration cycle apparatus 1 can raise the temperature of the circulating liquid to a high temperature in a short time. Therefore, the refrigeration cycle apparatus 1 can reduce the time loss caused by temperature adjustment and improve the productivity of semiconductor devices and the like. Further, since the heating amount by the heater 26 in the circulating liquid circuit 20 can be reduced, the energy consumption by the heater 26 can be reduced, and energy saving in the manufacturing process of semiconductor devices and the like can be achieved.

[0129] Next, the circulating liquid circuit 20 will be described in detail. The circulating liquid circuit 20 constitutes a closed circuit through which the circulating liquid that cools and heats the control object 46 circulates. Specifically, the circulating liquid circuit 20 includes a plurality of circuit modules 21 connected to the control object 46 and circulating the circulating liquid, a low-temperature path 31 to which the circuit modules 21 are connected and through which the circulating liquid flows through the evaporator 15 so as to be heat-exchangeable with the refrigerant, and a high-temperature path 38 to which the circuit modules 21 are connected and through which the circulating liquid flows through the radiator 12 so as to be heat-exchangeable with the refrigerant.

[0130] The circuit module 21 is a device that supplies the circulating liquid to the control object 46 and adjusts the temperature of the control object 46. A basic circulation path 22 that forms a basic closed circuit for circulating the circulating liquid is formed in each circuit module 21. Specifically, in the circuit module 21, a basic circulation path 22 is formed, which is a closed circuit to which a feed path 23 for supplying the circulating liquid to the control object 46 such as a semiconductor manufacturing apparatus and a return path 24 for returning the circulating liquid that has cooled and heated the control object 46 are connected.

[0131] In the feed path 23 of each circuit module 21, a circulation pump 25 for sending the circulating liquid to the control object 46, a heater 26 for heating and adjusting the temperature of the circulating liquid supplied to the control object 46, and a temperature sensor 27 for measuring the temperature of the circulating liquid heated by the heater 26 are provided.

[0132] The heater 26 is a resistance heating type electric heater or the like, for example, a sheathed heater in which a nichrome wire as a heating element is covered with a metal pipe. Further, the heater 26 may be an induction heating type heating means, for example, an induction coil or the like connected to an induction heating power source (not shown).

[0133] The temperature sensor 27 is provided in the feed path 23 downstream of the heater 26 and measures the temperature of the circulating liquid heated by the heater 26. The circulation pump 25, the heater 26, and the temperature sensor 27 are connected to the control device 43. The control device 43 controls the circulation pump 25 and the heater 26 so that the temperature of the circulating liquid measured by the temperature sensor 27 becomes a predetermined temperature. Thereby, the temperature of the control target 46 is controlled to become the set temperature.

[0134] Also, an electromagnetic valve 28 for opening and closing the feed path 23 is provided in the basic circulation path 22 of each circuit module 21. Thereby, when temperature control is not required for the control target 46 connected to the circuit module 21, the electromagnetic valve 28 can be closed to stop the flow of the circulating liquid.

[0135] The low-temperature path 31 is a path for cooling the circulating liquid by the refrigeration cycle device 1. The low-temperature path 31 is connected to the return path 24 side of the circuit module 21 at the inlet side and to the feed path 23 side of the circuit module 21 at the outlet side so as to form a bypass flow path for the circulating liquid in the basic circulation path 22.

[0136] That is, the circulating liquid circulating in the basic circulation path 22 of the circuit module 21 can flow into the low-temperature path 31 at the branch point serving as the inlet of the low-temperature path 31 and can also flow to the feed path 23 side without flowing into the low-temperature path 31.

[0137] A mixing valve 30 is provided at the confluence point of the outlet of the low-temperature path 31 and the basic circulation path 22. The mixing valve 30 is a valve that mixes the circulating liquid that has passed through the low-temperature path 31 with the circulating liquid supplied to the control target 46 via the feed path 23 of the circuit module 21. That is, the low-temperature path 31 can be opened and closed and its flow rate can be adjusted by the mixing valve 30.

[0138] By adjusting the mixing valve 30, it is possible to perform an operation of mixing the circulating liquid returned from the controlled object 46 with the circulating liquid cooled by the evaporation of the refrigerant in the evaporator 15 of the refrigeration cycle device 1 to obtain a suitable temperature.

[0139] Also, by adjusting the mixing valve 30, it is also possible to perform an operation of not supplying the circulating liquid cooled by the evaporator 15 to the controlled object 46. That is, it is also possible to perform a temperature adjustment operation in which only the circulating liquid returned from the controlled object 46 or only the circulating liquid heated by the radiator 12 is sent to the feed path 23, heated by the heater 26, and supplied to the controlled object 46 for circulation.

[0140] In addition, the low-temperature path 31 is provided with a low-temperature tank 32 for storing the circulating liquid, a low-temperature pump 33 for sending the circulating liquid, and a low-temperature circulation path 34 for returning the circulating liquid to the inlet side of the low-temperature path 31 without sending it to the controlled object 46.

[0141] Specifically, for example, a low-temperature tank 32 is provided on the inlet side of the low-temperature path 31, a low-temperature pump 33 is provided downstream of the low-temperature tank 32, and an evaporator 15 is provided downstream of the low-temperature pump 33. And the low-temperature circulation path 34 may be provided so as to connect the system branch pipe 36 provided downstream of the evaporator 15 of the low-temperature path 31 and the low-temperature tank 32 provided on the inlet side of the low-temperature path 31.

[0142] The low-temperature tank 32 is provided with a low-temperature sensor 37 for measuring the temperature of the circulating liquid in the low-temperature tank 32. The low-temperature pump 33 and the low-temperature sensor 37 are connected to the control device 43. The control device 43 may control the operation of the circulation pump 25 and the low-temperature pump 33 and the opening adjustment of the mixing valve 30 by using the temperature information of the circulating liquid measured by the low-temperature sensor 37 in the calculation.

[0143] As described above, the low-temperature path 31 is provided with a low-temperature tank 32, a low-temperature pump 33 for sending the circulating liquid, and a low-temperature circulation path 34 for returning the circulating liquid from the outlet side to the inlet side of the low-temperature path 31. Therefore, even when the circulating liquid in the low-temperature path 31 is not used as the circulating liquid supplied to the control target 46, the circulating liquid in the low-temperature path 31 can be circulated and cooled by the refrigerant flowing through the evaporator 15.

[0144] Then, the circulating liquid cooled by the refrigerant is stored in the low-temperature tank 32, and the stored low-temperature circulating liquid can be supplied to the circulating liquid circuit 20 as needed. For example, when the set temperature of the control target 46 is changed due to a change in the processing process or the like and the temperature of the circulating liquid is significantly reduced, the low-temperature circulating liquid stored in the cold and warm tank can be supplied to the circulating liquid circuit 20.

[0145] Thereby, the temperature of the circulating liquid circulating in the circulating liquid circuit 20 can be rapidly reduced to a predetermined temperature in a short time. Therefore, the time required for changing the set temperature can be significantly shortened, and the time loss associated with the temperature change until the start of the processing process, the measurement process, etc. can be reduced.

[0146] Also, as described above, the low-temperature path 31 is provided with a low-temperature tank 32, a low-temperature pump 33, and a low-temperature circulation path 34. Therefore, even when the circulating liquid in the low-temperature path 31 is not supplied to the control target 46, the refrigeration cycle device 1 can be operated to heat the circulating liquid in the high-temperature path 38 with the refrigerant in the radiator 12.

[0147] The high-temperature path 38 is a path for heating the circulating liquid by the refrigeration cycle device 1. The high-temperature path 38 is connected to the return path 24 side of the circuit module 21 at the inlet side and to the feed path 23 side of the circuit module 21 at the outlet side so as to form a bypass flow path for the circulating liquid in the basic circulation path 22.

[0148] Specifically, a three-way valve 29 is provided in the basic circulation path 22 of the circulating fluid circuit 20 upstream of the branch point to the low-temperature path 31. The three-way valve 29 is a valve that switches whether to send the circulating fluid returning from the control object 46 to the high-temperature path 38. That is, the high-temperature path 38 can be opened and closed by the three-way valve 29.

[0149] Specifically, the inlet of the high-temperature path 38 is connected to the three-way valve 29. The outlet of the high-temperature path 38 is connected downstream of the three-way valve 29 in the basic circulation path 22 and upstream of the branch point to the low-temperature path 31.

[0150] With such a configuration, by switching the three-way valve 29, it is possible to switch and execute an operation of supplying the circulating fluid heated by the radiator 12 of the refrigeration cycle device 1 to the control object 46 and an operation of not supplying it.

[0151] In the high-temperature path 38, a high-temperature tank 39 for storing the circulating fluid heated to a high temperature and a high-temperature sensor 42 for measuring the temperature of the circulating fluid in the high-temperature tank 39 are provided. And inside the high-temperature tank 39, the radiator 12 of the refrigeration cycle device 1 is provided so that the circulating fluid can be heated by the refrigerant.

[0152] The high-temperature tank 39 has an inlet for the circulating fluid formed at the lower part and an outlet for the circulating fluid formed at the upper part. Thereby, the high-temperature circulating fluid stored in the high-temperature tank 39 can be efficiently supplied to the control object 46.

[0153] That is, the low-temperature circulating fluid returning from the control object 46 flows into the high-temperature path 38 through the three-way valve 29 and flows into the inside of the high-temperature tank 39 from the inlet formed at the lower part of the high-temperature tank 39. And the high-temperature circulating fluid stored in the high-temperature tank 39 is sent from the outlet formed at the upper part of the high-temperature tank 39 to the basic circulation path 22 and supplied to the control object 46.

[0154] In this way, the temperature adjustment device 2 includes the high-temperature tank 39, and can send the high-temperature circulating liquid stored in the high-temperature tank 39 to the basic circulation path 22. Therefore, for example, when the set temperature of the control target 46 is changed due to a change in a processing step or the like and the temperature of the circulating liquid is significantly increased, a highly efficient temperature change becomes possible.

[0155] That is, the high-temperature circulating liquid stored in the high-temperature tank 39 can be supplied to the circulating liquid circuit 20, and the temperature of the circulating liquid circulating in the circulating liquid circuit 20 can be rapidly increased to a predetermined temperature in a short time. Therefore, the refrigeration cycle device 1 can significantly shorten the time required for changing the set temperature and reduce the time loss associated with the temperature change until the start of a processing step, a measurement step, or the like.

[0156] Note that the control device 43 may use the temperature information of the circulating liquid in the high-temperature tank 39 measured by the high-temperature sensor 42 in the operation for controlling the opening and closing of the three-way valve 29. Thereby, the flow of the high-temperature path 38 can be controlled according to the amount of the high-temperature circulating liquid stored in the high-temperature tank 39. Therefore, when the high-temperature circulating liquid stored in the high-temperature tank 39 is insufficient, it is possible to suppress the low-temperature circulating liquid from being sent to the basic circulation path 22 and causing a time loss in the temperature change.

[0157] In addition, the low-temperature path 31 and the high-temperature path 38 are provided with system confluence pipes 35, 40 and system branch pipes 36, 41 for connecting a plurality of circuit modules 21. Specifically, the low-temperature path 31 is provided with a system confluence pipe 35 on the inlet side and a system branch pipe 36 on the outlet side. The high-temperature path 38 is provided with a system confluence pipe 40 on the inlet side and a system branch pipe 41 on the outlet side.

[0158] Thereby, a plurality of circuit modules 21, for example, 2 to 8 or more circuit modules 21, can be connected to the low-temperature path 31 and the high-temperature path 38 via the system confluence pipes 35, 40 and the system branch pipes 36, 41.

[0159] The plurality of circuit modules 21 each have a circulation pump 25 and a heater 26, and can circulate the circulating liquid through different controlled objects 46 respectively. As a result, by using one refrigeration cycle device 1, the controlled objects 46 such as a plurality of processing locations and measurement locations can be cooled and heated with high efficiency, and each controlled object 46 can be adjusted to a suitable temperature.

[0160] Note that the present invention is not limited to the above-described embodiments. The present invention can be implemented with various modifications without departing from the gist thereof.

Explanation of Reference Numerals

[0161] 1, 101, 201, 301, 401 Refrigeration cycle device 2 Temperature adjustment device 10 Refrigerant circuit 11 Compressor 12 Radiator 13 Second radiator 14 Expansion valve 15 Evaporator 16 Blower fan 17 Second blower fan 18 Refrigerant temperature sensor 19 Pressure sensor 20 Circulating liquid circuit 21 Circuit module 22 Basic circulation path 23 Feed path 24 Return path 25 Circulation pump 26 Heater 27 Temperature sensor 28 Solenoid valve 29 Three-way valve 30 Mixing valve 31 Low-temperature path 32 Low-temperature tank 33 Low-temperature pump 34 Low-temperature circulation path 35 System confluence pipe 36 System branch pipe 37 Low-temperature sensor 38 High-temperature path 39 High-temperature tank 40 System Confluence Pipe 41 System Branch Pipe 42 High-Temperature Sensor 43 Control Device 44 Input Device 45 Display Device 46 Controlled Object 50 First-Stage Compression Mechanism 51 Second-Stage Compression Mechanism 52 Diverging Point 53 Auxiliary Flow Pipe 54 Auxiliary Flow expansion Valve 55 Economizer 56 Dryer 57 Accumulator 60 High-Temperature Side Refrigerant Circuit 61 High-Temperature Side Compressor 62 High-Temperature Side Radiator 64 High-Temperature Side Expansion Valve 65 Cascade Heat Exchanger 66 High-Temperature Side Blower Fan 70 Low-Stage Compressor 71 High-Stage Compressor 72 High-Stage Expansion Valve 73 Low-Stage Expansion Valve 74 Receiver Tank 75 Bypass Route 76 Check Valve 77 Confluence Point 78 Liquid-Level Sensor 79 Intermediate Radiator 80 Intermediate Blower Fan 81 Liquid-Gas Heat Exchanger T1~T7 Temperatures P1~P3 Pressures

Claims

1. A vapor compression refrigeration cycle device, comprising: a refrigerant circuit in which a compression means, a radiator, a throttling means, and an evaporator are sequentially connected and a refrigerant circulates; as the refrigerant, a mixed refrigerant containing at least one of dimethyl ether and difluoromethane with carbon dioxide as a main component is used; configured such that the operation of the refrigeration cycle is performed with the pressure of the refrigerant at the inlet of the evaporator being equal to or lower than the triple point pressure of carbon dioxide; connected to a circulating liquid circuit in which a circulating liquid for adjusting the temperature of a control target circulates; the circulating liquid circuit has an openable and closable low-temperature path through which the circulating liquid flows through the evaporator so as to be heat-exchangeable with the refrigerant, and an openable and closable high-temperature path through which the circulating liquid flows through the radiator so as to be heat-exchangeable with the refrigerant; A refrigeration cycle device, characterized in that a high-temperature tank for storing the circulating liquid heated by the refrigerant in the radiator is provided in the high-temperature path.

2. Comprising a high-temperature side refrigerant circuit in which a high-temperature side compression means, a high-temperature side radiator, a high-temperature side throttling means, and a cascade heat exchanger are sequentially connected and a high-temperature side refrigerant circulates; The cascade heat exchanger is provided in the radiator or the refrigerant circuit downstream of the radiator so as to perform heat exchange between the refrigerant and the high-temperature side refrigerant. The refrigeration cycle device according to claim 1.

3. The compression means has a low-stage compressor and a high-stage compressor for further compressing the refrigerant compressed by the low-stage compressor; The throttling means has a high-stage expansion valve and a low-stage expansion valve for further decompressing the refrigerant decompressed by the high-stage expansion valve; A receiver tank for separating the refrigerant into a gaseous refrigerant and a liquid refrigerant is provided in the refrigerant circuit between the high-stage expansion valve and the low-stage expansion valve; The gaseous refrigerant separated by the receiver tank is sucked into the high-stage compressor via a bypass path that bypasses the low-stage expansion valve, the evaporator, and the low-stage compressor from the receiver tank and is connected to the downstream of the low-stage compressor. The refrigeration cycle device according to claim 1 or claim 2.

4. A control device for controlling the rotational speed of at least one of the low-stage compressor and the high-stage compressor; A liquid level sensor for detecting the liquid level of the liquid-phase refrigerant in the receiver tank. The refrigeration cycle device according to claim 3, wherein the control device controls the rotational speed of at least one of the low-stage compressor and the high-stage compressor based on the liquid level of the liquid-phase refrigerant in the receiver tank detected by the liquid level sensor.

5. The refrigeration cycle device according to claim 1 or claim 2, further comprising a liquid-gas heat exchanger configured to perform heat exchange between the refrigerant after heat dissipation by the radiator and the refrigerant after heat absorption by the evaporator.

6. The refrigeration cycle device according to claim 1 or claim 2, wherein the amount of carbon dioxide enclosed in the refrigerant is 75 to 97% by mass based on the total enclosed amount.

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