Refrigeration system and refrigeration method

Abstract

Provided are a refrigeration system and a refrigeration method, which are robust with respect to variations in outside temperature. The refrigeration system comprises: a first refrigeration cycle for cooling an object to be cooled by discharging heat to an intermediate refrigerant, the temperature of the object to be cooled being 0°C or below; a second refrigeration cycle for cooling the intermediate refrigerant by discharging heat directly or indirectly to the atmosphere, the temperature of the object to be cooled being 0°C or above; and an intermediate refrigerant line that circulates the intermediate refrigerant between the first refrigeration cycle and the second refrigeration cycle.

Description

Refrigeration System and Refrigeration Method

[0004]

[0001] The present disclosure relates to a refrigeration system and a refrigeration method.

[0002] Techniques for cooling a cooling target are known. For example, Patent Document 1 discloses an air refrigerant type refrigeration apparatus that uses air as the cooling target and supplies the cooled air into a refrigerator. The air refrigerant type refrigeration apparatus arranges a compression turbine, an air cooler, an air-to-air heat exchanger, and an expansion turbine in the order of the air flow, and exchanges heat between the air taken in from the refrigerator and the high-temperature air at the outlet of the compression turbine in the air-to-air heat exchanger. The air cooler is composed of a water-to-air heat exchanger that exchanges heat between cooling water and air. <C000005>

[0003] Japanese Patent Laid-Open No. 11-132582

[0004] In Patent Document 1, the high-temperature air at the outlet of the compressor (compression turbine) is cooled by cooling water. Since the temperature of the cooling water changes with the outside air temperature in summer and winter, the refrigeration performance (coefficient of performance: COP) of the refrigeration system fluctuates depending on the outside air temperature. That is, compared with winter, in summer when the outside air temperature and the cooling water temperature are high, the cooling capacity by the cooling water decreases, and the temperature of the cooled air rises, so that the refrigeration performance of the refrigeration system decreases accordingly. A refrigeration system that is robust against fluctuations in the outside air temperature is required.

[0005] An object of the present disclosure is to provide a refrigeration system and a refrigeration method that are robust against fluctuations in the outside air temperature.

[0006] The refrigeration system of the present disclosure for achieving the above object includes a first refrigeration cycle in which a cooling target is cooled by discharging waste heat to an intermediate refrigerant, the temperature of the cooling target being 0°C or lower, a second refrigeration cycle in which the intermediate refrigerant is cooled by directly or indirectly discharging waste heat to the atmosphere, the temperature of the cooling target being 0°C or higher, and an intermediate refrigerant line for circulating the intermediate refrigerant between the first refrigeration cycle and the second refrigeration cycle.

[0007] Furthermore, the refrigeration method of the present disclosure is a refrigeration method in a refrigeration system comprising a first refrigeration cycle and a second refrigeration cycle, comprising the steps of: cooling an intermediate refrigerant by directly or indirectly discharging heat to the atmosphere from the second refrigeration cycle, where the temperature of the object to be cooled is 0°C or higher; circulating the intermediate refrigerant between the first refrigeration cycle and the second refrigeration cycle; and cooling the object to be cooled by discharging heat to the intermediate refrigerant from the first refrigeration cycle, where the temperature of the object to be cooled is 0°C or lower.

[0008] This disclosure provides a refrigeration system and refrigeration method that are robust against fluctuations in ambient temperature.

[0009] Figure 1 is a schematic diagram representing a refrigeration system according to the first embodiment. Figure 2 is a schematic diagram representing a refrigeration system according to the second embodiment. Figure 3 is a schematic diagram representing a refrigeration system according to the third embodiment. Figure 4 is a schematic diagram representing a first inverse Brayton refrigeration cycle. Figure 5 is a schematic diagram representing a refrigeration system according to the fourth embodiment. Figure 6 is a diagram showing a specific configuration example of a refrigeration system according to the fourth embodiment. Figure 7 is a schematic diagram representing a refrigeration system according to the fifth embodiment. Figure 8 is a schematic diagram representing a first operating mode of a refrigeration system according to the sixth embodiment. Figure 9 is a schematic diagram representing a second operating mode of a refrigeration system according to the sixth embodiment. Figure 10 is a schematic diagram representing a refrigeration system according to the seventh embodiment. Figure 11 is a schematic diagram representing a refrigeration system according to the eighth embodiment. Figure 12 is a schematic diagram representing a refrigeration system according to the ninth embodiment.

[0010] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. However, these embodiments do not limit the present disclosure, and where there are multiple embodiments, they may be combinations of these embodiments. Furthermore, the components in the embodiments include those readily conceivable by those skilled in the art, those that are substantially identical, and those that are equivalent.

[0011] [First Embodiment] Figure 1 is a schematic diagram showing a refrigeration system 1 according to the first embodiment. The refrigeration system 1 is a system that supplies cooling heat to a cooling object 2. The refrigeration system 1 is installed in facilities such as factories, plants, logistics centers, and data centers. The cooling object 2 is not particularly limited. The cooling object 2 may be, for example, air or gas used in air conditioning equipment, freezers or processing equipment, or a sample. The cooling object 2 may also be, for example, a heat source provided in the device. The refrigeration system 1 comprises a plurality of refrigeration cycles. A refrigeration cycle means a thermodynamic cycle in which heat is absorbed from the cooling object by power and discharged to a high-temperature heat source.

[0012] The refrigeration system 1 comprises a first refrigeration cycle 10, a second refrigeration cycle 20, and an intermediate refrigerant line 30. The first refrigeration cycle 10 and the second refrigeration cycle 20 are connected via the intermediate refrigerant line 30.

[0013] The first refrigeration cycle 10 is a refrigeration cycle in which the temperature of the object to be cooled is 0°C or lower. The first refrigeration cycle 10 cools the object to be cooled 2 by directly or indirectly absorbing heat from the object to be cooled 2. The temperature of the object to be cooled in the first refrigeration cycle 10 is the temperature of the object to be cooled 2 of the refrigeration system 1 (target temperature). Direct or indirect heat absorption means that the object to be cooled 2 may be cooled directly, or the object to be cooled 2 may be cooled indirectly by cooling a heat transfer medium (refrigerant) that can exchange heat with the object to be cooled 2. The temperature of the object to be cooled in the first refrigeration cycle 10 is not particularly limited as long as it is 0°C or lower, and may be 0°C or a temperature lower than 0°C.

[0014] The first refrigeration cycle 10 cools the object to be cooled 2 by discharging heat to the intermediate refrigerant MR. In addition to the intermediate refrigerant MR, the first refrigeration cycle 10 may also use other heat transfer fluids. The first refrigeration cycle 10 absorbs heat from the object to be cooled 2 and discharges at least a portion of the absorbed heat to the intermediate refrigerant MR.

[0015] The configuration of the first refrigeration cycle 10 is not particularly limited. The first refrigeration cycle 10 may be, for example, a vapor compression refrigeration cycle, a gas refrigeration cycle, an absorption refrigeration cycle, an adsorption refrigeration cycle, a magnetic refrigeration cycle, etc. The first refrigeration cycle 10 may be single-stage or multi-stage.

[0016] The second refrigeration cycle 20 is a refrigeration cycle with a target temperature of 0°C or higher. The second refrigeration cycle 20 is a heat pump that cools the intermediate refrigerant MR by directly or indirectly discharging heat into the atmosphere. Discharging heat directly or indirectly into the atmosphere means that heat may be discharged by heat exchange with the atmosphere (external air), or heat may be discharged indirectly into the atmosphere by discharging heat into a heat transfer medium (such as water) that can exchange heat with the atmosphere. The target of cooling in the second refrigeration cycle 20 is the intermediate refrigerant MR, and the target temperature of the second refrigeration cycle 20 is the temperature of the intermediate refrigerant MR. The target temperature of the second refrigeration cycle 20 is not particularly limited as long as it is 0°C or higher, and may be 0°C or a temperature higher than 0°C. In the first embodiment, the target temperature of the second refrigeration cycle 20 is higher than the target temperature of the first refrigeration cycle 10. The second refrigeration cycle 20 can supply the intermediate refrigerant MR, which has been cooled to the target temperature, to the first refrigeration cycle 10 via the intermediate refrigerant line 30.

[0017] The configuration of the second refrigeration cycle 20 is not particularly limited. The second refrigeration cycle 20 may be, for example, a vapor compression refrigeration cycle, an air refrigeration cycle, an absorption refrigeration cycle, an adsorption refrigeration cycle, a magnetic refrigeration cycle, or the like. The second refrigeration cycle 20 may be single-stage or multi-stage.

[0018] The intermediate refrigerant line 30 is a circulation line for circulating fluid. The intermediate refrigerant line 30 is composed of a circularly connected pipeline. The intermediate refrigerant line 30 circulates the intermediate refrigerant MR between the first refrigeration cycle 10 and the second refrigeration cycle 20. Part of the intermediate refrigerant line 30 passes through the first refrigeration cycle 10, and another part of the intermediate refrigerant line 30 passes through the second refrigeration cycle 20. The intermediate refrigerant MR flowing through the intermediate refrigerant line 30 is heat exchangerable with the first refrigeration cycle 10 and the second refrigeration cycle 20, respectively. The first refrigeration cycle 10 and the second refrigeration cycle 20 may each be equipped with a heat exchanger for heat exchange with the intermediate refrigerant MR. The intermediate refrigerant line 30 may be equipped with a pump for circulating the intermediate refrigerant MR.

[0019] As the intermediate refrigerant MR circulates through the intermediate refrigerant line 30, it absorbs heat from the first refrigeration cycle 10 and its temperature rises. The heated intermediate refrigerant MR is then cooled to the target temperature by the second refrigeration cycle 20.

[0020] (Freezing Method) Next, a freezing method according to the first embodiment will be described. The freezing method according to the first embodiment is a freezing method in a freezing system 1 comprising a first freezing cycle 10 and a second freezing cycle 20. Figure 1 shows an example of the target temperature for cooling in each freezing cycle in the freezing system 1 according to the first embodiment. In the first embodiment, the target temperature for cooling in the first freezing cycle 10 is -30°C, and the target temperature for cooling in the second freezing cycle 20 is 10°C.

[0021] The refrigeration method according to the first embodiment includes a step in which a second refrigeration cycle 20, whose target temperature is 0°C or higher, cools the intermediate refrigerant MR by directly or indirectly discharging heat into the atmosphere. In the example shown in Figure 1, the second refrigeration cycle 20 cools the intermediate refrigerant MR from 15°C to 10°C by discharging heat into the 32°C atmosphere. Due to the heat discharge, air heated to 37°C is discharged from the second refrigeration cycle 20.

[0022] The refrigeration method according to the first embodiment includes the step of circulating intermediate refrigerant MR between a first refrigeration cycle 10 and a second refrigeration cycle 20. In the example shown in Figure 1, the intermediate refrigerant line 30 circulates the intermediate refrigerant MR, sending the 10°C intermediate refrigerant MR cooled in the second refrigeration cycle 20 to the first refrigeration cycle 10.

[0023] The refrigeration method according to the first embodiment includes a step in which a first refrigeration cycle 10, whose target temperature is 0°C or lower, cools the target to be cooled 2 by discharging heat to an intermediate refrigerant MR. In the example shown in Figure 1, the first refrigeration cycle 10 cools the target to be cooled 2 from -25°C to -30°C using an intermediate refrigerant MR at 10°C. The intermediate refrigerant MR rises in temperature to 15°C by absorbing the heat discharged from the first refrigeration cycle 10.

[0024] The intermediate refrigerant MR, whose temperature has risen to 15°C due to the waste heat from the first refrigeration cycle 10, is returned to the second refrigeration cycle 20 via the intermediate refrigerant line 30.

[0025] Refrigeration cycles that dissipate heat directly or indirectly into the atmosphere are affected by fluctuations in ambient temperature. That is, refrigeration performance is high in winter when ambient temperatures are low, but decreases in summer when ambient temperatures are high, making it easy for the supply of cold energy to be insufficient to meet demand. Therefore, in the first embodiment, a second refrigeration cycle 20 that cools the intermediate refrigerant MR is combined with a first refrigeration cycle 10 that cools the object to be cooled 2. Even when ambient temperatures are high, the first refrigeration cycle 10 is supplied with intermediate refrigerant MR whose temperature has been adjusted by the second refrigeration cycle 20. As a result, the influence of fluctuations in ambient temperature on the first refrigeration cycle 10 that cools the object to be cooled 2 is reduced.

[0026] [Second Embodiment] Figure 2 is a schematic diagram showing the refrigeration system 1A according to the second embodiment. In the second embodiment, the target temperature for cooling of the refrigeration system is different from that of the first embodiment.

[0027] In the refrigeration system 1A according to the second embodiment, the first refrigeration cycle 10 has a target temperature of -40°C or lower. The target temperature of the first refrigeration cycle 10 may be -40°C or a temperature lower than -40°C. In the second embodiment, the temperature difference between the target temperature of the first refrigeration cycle 10 and the target temperature of the second refrigeration cycle 20 is 40°C or more.

[0028] In Figure 2, as an example, the target temperature for cooling in the first refrigeration cycle 10 is -245°C. The first refrigeration cycle 10 supplies cold energy to cryogenic demand equipment, such as equipment that handles liquefied gases. Such a cryogenic first refrigeration cycle 10 is effective when it is a multi-stage (or multi-component) cycle.

[0029] In the second embodiment, the target temperature for cooling in the second refrigeration cycle 20 is the same as in the first embodiment. In the example shown in Figure 2, the second refrigeration cycle 20 cools the intermediate refrigerant MR, which is at 15°C, to 10°C by releasing heat into the 32°C atmosphere. Due to the heat release, air heated to 37°C is discharged from the second refrigeration cycle 20. The first refrigeration cycle 10 cools the target 2, which is at -240°C, to -245°C using the intermediate refrigerant MR at 10°C. The intermediate refrigerant MR is heated to 15°C by absorbing heat released from the first refrigeration cycle 10.

[0030] [Third Embodiment] Figure 3 is a schematic diagram showing a refrigeration system 1B according to the third embodiment. In the third embodiment, a specific example of the configuration of the first refrigeration cycle 10 is shown.

[0031] In the refrigeration system 1B according to the third embodiment, the first refrigeration cycle 10 includes an inverted Brayton refrigeration cycle. The inverted Brayton refrigeration cycle is a type of refrigeration cycle that generates low temperatures by compressing a gas with a compressor, cooling it in a heat exchanger, and then lowering the pressure and temperature of the gas with an expander. The inverted Brayton refrigeration cycle is a single-phase (gas phase) cycle that does not utilize the latent heat of vaporization associated with the evaporation and condensation of gas. The gaseous refrigerant used in the inverted Brayton refrigeration cycle is not particularly limited. The gaseous refrigerant may be air or other natural refrigerants (e.g., nitrogen gas). The target temperature to be cooled in the first refrigeration cycle 10 may be -40°C or a temperature lower than -40°C. In Figure 3, as an example, the target temperature to be cooled in the first refrigeration cycle 10 is -45°C. The first refrigeration cycle 10 cools the target to be cooled 2 from -40°C to -45°C with an intermediate refrigerant MR at 10°C.

[0032] Figure 4 is a schematic diagram showing the first refrigeration cycle of an inverted Brayton type.

[0033] The first refrigeration cycle 10 according to the third embodiment includes a compressor 11 for compressing the refrigerant, a prime mover 12 for driving the compressor 11, an intermediate refrigerant heat exchanger 13 for cooling the refrigerant with an intermediate refrigerant MR, and an expander 14 for expanding the refrigerant. In Figure 4, the first refrigeration cycle 10 also includes a regenerative heat exchanger 15. The compressor 11, the intermediate refrigerant heat exchanger 13, the expander 14, the cooling target 2, and the regenerative heat exchanger 15 are connected by a refrigerant line 16.

[0034] The refrigerant line 16 includes a first portion 16A that connects from the outlet of the compressor 11 through the high-temperature side flow path of the intermediate refrigerant heat exchanger 13, the high-temperature side flow path of the regenerative heat exchanger 15, and the expander 14 to the object to be cooled 2, and a second portion 16B that connects from the object to be cooled 2 through the low-temperature side flow path of the regenerative heat exchanger 15 to the inlet of the compressor 11.

[0035] The compressor 11 is a turbo compressor that includes a compression turbine that compresses the refrigerant using the rotational power of the prime mover 12. The prime mover 12 is, for example, an electric motor. The expander 14 is an expansion turbine that rotates while expanding the high-pressure refrigerant. The compressor 11, prime mover 12, and expander 14 are connected by a rotating shaft 14A. The rotational power of the expansion turbine generated by the expansion of the high-pressure refrigerant is used to rotate the compression turbine (compression work).

[0036] The intermediate refrigerant heat exchanger 13 performs heat exchange between the intermediate refrigerant MR and the refrigerant. The intermediate refrigerant heat exchanger 13 includes a low-temperature side passage through which the intermediate refrigerant MR flows and a high-temperature side passage through which the refrigerant flows, and the low-temperature side passage and the high-temperature side passage are separated by a heat transfer surface so that heat exchange can occur. The low-temperature side passage is connected to the intermediate refrigerant line 30 and constitutes a part of the intermediate refrigerant line 30. The high-temperature side passage is connected to the first part 16A of the refrigerant line 16 and constitutes a part of the first part 16A. The intermediate refrigerant heat exchanger 13 cools the high-temperature, high-pressure refrigerant sent from the outlet of the compressor 11 with the intermediate refrigerant MR cooled in the second refrigeration cycle 20.

[0037] The regenerative heat exchanger 15 performs heat exchange between the refrigerant passing through the first section 16A and the refrigerant passing through the second section 16B of the refrigerant line 16. The regenerative heat exchanger 15 includes a high-temperature side flow path and a low-temperature side flow path, and the high-temperature side flow path and the low-temperature side flow path are separated by a heat transfer surface so that heat exchange can occur. The high-temperature side flow path is connected to the first section 16A and constitutes a part of the first section 16A. The low-temperature side flow path is connected to the second section 16B and constitutes a part of the second section 16B. The regenerative heat exchanger 15 cools the high-pressure refrigerant after it has passed through the intermediate refrigerant heat exchanger 13 with the low-temperature refrigerant that has come out of the cooling target 2.

[0038] In the first refrigeration cycle 10, the high-pressure, high-temperature refrigerant compressed by the compressor 11 is cooled by the intermediate refrigerant MR in the intermediate refrigerant heat exchanger 13. The high-pressure refrigerant cooled in the intermediate refrigerant heat exchanger 13 is further cooled by the low-temperature refrigerant from the cooling target 2 in the regenerative heat exchanger 15. The high-pressure refrigerant cooled in the regenerative heat exchanger 15 is adiabatically expanded in the expander 14 to atmospheric pressure or near atmospheric pressure, thereby lowering its temperature to the cooling target temperature. The low-temperature refrigerant exiting the expander 14 is supplied to the cooling target 2. The refrigerant that exits the cooling target 2 and absorbs heat in the regenerative heat exchanger 15 flows into the compressor 11. The first refrigeration cycle 10 circulates and supplies the refrigerant cooled to the cooling target temperature to the cooling target 2.

[0039] While the reverse Brayton refrigeration cycle generally performs worse than the vapor compression refrigeration cycle in terms of refrigeration performance (COP) above -40°C, the difference in refrigeration performance between the reverse Brayton and vapor compression refrigeration cycles disappears in the low-temperature range below -40°C. Furthermore, the lower the target temperature to be cooled, the better the reverse Brayton refrigeration cycle performs than the vapor compression refrigeration cycle. Therefore, by adopting the reverse Brayton refrigeration cycle as the first refrigeration cycle 10, where the target temperature to be cooled is below -40°C, the refrigeration performance (COP) is improved.

[0040] [Fourth Embodiment] Figure 5 is a schematic diagram showing a refrigeration system 1C according to the fourth embodiment. In the fourth embodiment, an example is shown in which the first refrigeration cycle 10 is configured as an inverted Brayton refrigeration cycle and the second refrigeration cycle 20 is configured as a vapor compression refrigeration cycle.

[0041] In the refrigeration system 1C according to the fourth embodiment, the first refrigeration cycle 10 includes a reverse Brayton refrigeration cycle. The second refrigeration cycle 20 includes a vapor compression refrigeration cycle. The vapor compression refrigeration cycle is a refrigeration cycle that compresses, condenses, expands, and evaporates a refrigerant and performs cooling by utilizing the latent heat of vaporization. In the vapor compression refrigeration cycle, the refrigerant repeatedly undergoes a phase change between the gas phase and the liquid phase. In the example of FIG. 5, the first refrigeration cycle 10 cools the cooling target 2 at -80°C to -85°C with the intermediate refrigerant MR at 7°C. The second refrigeration cycle 20 cools the intermediate refrigerant MR at 12°C to 7°C by discharging heat to the atmosphere at 32°C. The atmosphere that has absorbed heat from the second refrigeration cycle 20 is discharged at 37°C.

[0042] FIG. 6 is a diagram showing a specific configuration example of the refrigeration system according to the fourth embodiment.

[0043] In the example of FIG. 6, the configuration of the first refrigeration cycle 10 is the same as that of the above-described third embodiment.

[0044] The second refrigeration cycle 20 includes a compression part 21 that compresses the gaseous refrigerant 25A, a condenser 22 that condenses the compressed refrigerant 25A, an expansion valve 23 that expands the liquid-phase refrigerant 25A, and an evaporator 24 that evaporates the expanded refrigerant 25A with the intermediate refrigerant MR. The second refrigeration cycle 20 includes a refrigerant line 25 that connects the compression part 21, the condenser 22, the expansion valve 23, and the evaporator 24.

[0045] The refrigerant line 25 is a circulation flow path that connects each part so that the refrigerant 25A returns from the outlet of the compression part 21 to the compression part 21 through the condenser 22, the expansion valve 23, and the evaporator 24.

[0046] The compression part 21 includes a compression turbine 26 that compresses the refrigerant 25A by rotational power and a prime mover 27. The compression part 21 may be single-stage compression or multi-stage compression. The compression turbine 26 compresses the low-pressure refrigerant 25A from the evaporator 24. The outlet of the compression turbine 26 is connected to the condenser 22. The compression turbine 26 is connected to the prime mover 27 by a rotating shaft and rotates by the driving force of the prime mover 27. The prime mover 27 is, for example, an electric motor.

[0047] The condenser 22 cools and condenses the high-temperature and high-pressure refrigerant 25A compressed in the compression unit 21 by discharging waste heat directly or indirectly to the atmosphere. The condenser 22 may be an air-cooled type that discharges waste heat directly to the air (atmosphere), or a water-cooled type that finally discharges waste heat to the atmosphere through cooling water.

[0048] The expansion valve 23 expands the liquid-phase refrigerant 25A that has passed through the condenser 22 to reduce the pressure of the refrigerant 25A. The evaporator 24 exchanges heat between the refrigerant 25A that has passed through the expansion valve 23 in the refrigerant line 25 and the intermediate refrigerant MR flowing through the intermediate refrigerant line 30. The evaporator 24 evaporates the refrigerant 25A by absorbing heat from the intermediate refrigerant MR. The evaporator 24 cools the intermediate refrigerant MR by the latent heat of vaporization of the refrigerant 25A.

[0049] Thus, in the second refrigeration cycle 20, the high-pressure and high-temperature refrigerant 25A compressed in the compression unit 21 is condensed by discharging waste heat to the atmosphere in the condenser 22. After the high-pressure refrigerant 25A that has passed through the condenser 22 is depressurized by the expansion valve 23 and its temperature drops, it evaporates by absorbing heat from the intermediate refrigerant MR in the evaporator 24. As a result of the heat absorption, the intermediate refrigerant MR is cooled to the target cooling temperature. The refrigerant 25A that has passed through the evaporator 24 is sent to the compression unit 21 and compressed again. The second refrigeration cycle 20 cools the intermediate refrigerant MR in the intermediate refrigerant line 30 to the target cooling temperature by the circulation of this refrigerant 25A.

[0050] The intermediate refrigerant line 30 is a circulation flow path that passes through the intermediate refrigerant heat exchanger 13 of the first refrigeration cycle 10 and the evaporator 24 of the second refrigeration cycle 20. In the fourth embodiment, the intermediate refrigerant MR is a liquid refrigerant containing water. The intermediate refrigerant MR is water, or a brine solution (antifreeze) in which glycol or the like is mixed with water. In this specification, the brine solution means water to which a component for lowering the freezing temperature is added, and is not limited to salt water. Such an intermediate refrigerant MR is easy to handle, has a large density because it is a liquid, and can reduce the size of pipes and heat exchangers. Therefore, not only the cooling performance (COP) is improved, but also the economic rationality is improved.

[0051] [Fifth Embodiment] Figure 7 is a schematic diagram showing a refrigeration system 1D according to the fifth embodiment. In the fifth embodiment, an example is shown in which the second refrigeration cycle 20 is configured by the refrigeration cycle of the air conditioner 4.

[0052] For example, in facilities such as factories, a large air conditioner (air conditioner 4) is installed to supply cooling to the demand equipment 5 within the facility. The large air conditioner 4 is installed, for example, in the facility's machine room and supplies cooling water to the demand equipment 5 within the facility via piping. In the refrigeration system 1D according to the fifth embodiment, the intermediate refrigerant MR is cooled by this air conditioner 4. That is, the refrigeration system 1D includes a second refrigeration cycle 20 and is equipped with an air conditioner 4 that supplies the intermediate refrigerant MR to the demand equipment 5.

[0053] The air conditioner 4 includes a second refrigeration cycle 20 consisting of a vapor compression refrigeration cycle, similar to that of the fourth embodiment described above. The air conditioner 4 cools the intermediate refrigerant MR by directly or indirectly discharging heat into the atmosphere. The intermediate refrigerant MR is distributed to the first refrigeration cycle 10 and the demand equipment 5 by the intermediate refrigerant line 30. Thus, in the fifth embodiment, a portion of the intermediate refrigerant MR from the air conditioner 4 is supplied to the first refrigeration cycle 10 via the intermediate refrigerant line 30. The first refrigeration cycle 10 can also be considered a type of demand equipment 5.

[0054] The intermediate refrigerant line 30 is a circulating passage that connects to the air conditioner 4 and branches off at a branching point 31 to connect to the demand equipment 5 and the first refrigeration cycle 10, respectively. In other words, in the fifth embodiment, by providing a branching point 31 in the circulating passage connecting the air conditioner 4 and the demand equipment 5 and connecting the intermediate refrigerant line 30, cooling water from the air conditioner 4 can be supplied to the first refrigeration cycle 10 as intermediate refrigerant MR. The intermediate refrigerant line 30 includes a pump 32. The pump 32 circulates the intermediate refrigerant MR within the intermediate refrigerant line 30.

[0055] In Figure 7, the first refrigeration cycle 10 is a closed cycle comprising an annular refrigerant line 16 through which the refrigerant 16C circulates. The refrigerant line 16 is an independent circulation path that does not communicate with the supply line 8 through which the material to be cooled 2 flows. The first refrigeration cycle 10 includes a first heat exchanger 51 that cools the material to be cooled 2. In Figure 7, the material to be cooled 2 is, for example, brine.

[0056] The first heat exchanger 51 includes a low-temperature side passage through which the refrigerant 16C flows and a high-temperature side passage through which the material to be cooled 2 flows, and the low-temperature side passage and the high-temperature side passage are separated by a heat transfer surface so that heat exchange can occur. The low-temperature side passage is connected to the refrigerant line 16 and constitutes a part of the refrigerant line 16. The high-temperature side passage is connected to the supply line 8 and constitutes a part of the supply line 8. The first heat exchanger 51 cools the material to be cooled 2 with the refrigerant 16C cooled in the first refrigeration cycle 10. The first heat exchanger 51 exchanges heat between the gas phase refrigerant 16C and the liquid phase material to be cooled 2.

[0057] In the example shown in Figure 7, the first refrigeration cycle 10 cools the object to be cooled 2 from -80°C to -85°C using an intermediate refrigerant MR at 7°C. The air conditioner 4 (second refrigeration cycle 20) cools the intermediate refrigerant MR at 12°C to 7°C by releasing heat into the 32°C atmosphere. The atmosphere that has absorbed heat from the air conditioner 4 (second refrigeration cycle 20) is discharged at 37°C.

[0058] Thus, in the refrigeration system 1D according to the fifth embodiment, a portion of the cooling water supplied from the air conditioner 4 is used as an intermediate refrigerant MR in the first refrigeration cycle 10. Since the air conditioner 4 is already installed in facilities such as factories, the refrigeration system 1D can be constructed by retrofitting the piping that will become the first refrigeration cycle 10 and the intermediate refrigerant line 30 to the air conditioner 4 and cooling water piping within the facility. In this case, there is no need to install a second refrigeration cycle 20 separately from the air conditioner 4, so the system configuration related to cooling and refrigeration throughout the facility is simplified, the installation space for the equipment can be reduced, and the construction of the refrigeration system 1D becomes easier.

[0059] [Sixth Embodiment] Figure 8 is a schematic diagram showing a first operating mode of the refrigeration system according to the sixth embodiment. Figure 9 is a schematic diagram showing a second operating mode of the refrigeration system according to the sixth embodiment. In the sixth embodiment, in addition to the fifth embodiment described above, an example is shown in which the intermediate refrigerant line 30 is also connected to the cooling tower 6.

[0060] In the refrigeration system 1E according to the sixth embodiment, the intermediate refrigerant line 30 is connected to a cooling tower 6 in addition to the second refrigeration cycle 20. The cooling tower 6 is a heat exchanger that cools water by bringing it into direct or indirect contact with the atmosphere. The configuration of the cooling tower 6 is not particularly limited. The cooling tower 6 is, for example, a closed type, and cools the cooling water circulating in the piping by the latent heat of vaporization of water, which is achieved by spraying water inside the cooling tower 6 while passing outside air through it with a blower. The intermediate refrigerant line 30 is connected to the piping of this cooling tower 6.

[0061] The cooling tower 6 is connected to the air conditioner 4 (second refrigeration cycle 20) via piping 6A, separate from the intermediate refrigerant line 30. The cooling tower 6 supplies cooling water to the air conditioner 4 (second refrigeration cycle 20). The air conditioner 4 (second refrigeration cycle 20) indirectly dissipates heat into the atmosphere through heat exchange with the cooling water from the cooling tower 6 in its condenser 22.

[0062] The intermediate refrigerant line 30 is capable of circulating the intermediate refrigerant MR between the first refrigeration cycle 10, the air conditioner 4 (second refrigeration cycle 20), the demand equipment 5, and the cooling tower 6. Specifically, the intermediate refrigerant line 30 includes pipelines 33A, 33B, 33C, 33D, 33E, and 33F. Pipelines 33A and 33B connect the air conditioner 4 and the demand equipment 5. Pipeline 33A is the forward path that sends low-temperature intermediate refrigerant MR to the demand equipment 5, and pipeline 33B is the return path that returns high-temperature intermediate refrigerant MR to the air conditioner 4. Pipelines 33C and 33D connect the cooling tower 6 and the first refrigeration cycle 10. Pipeline 33C is the forward path that sends low-temperature intermediate refrigerant MR to the first refrigeration cycle 10, and pipeline 33D is the return path that returns high-temperature intermediate refrigerant MR to the cooling tower 6. Pipeline 33E connects pipeline 33A and pipeline 33C, which are forward lines for supplying the low-temperature intermediate refrigerant MR. Pipeline 33F connects pipeline 33B and pipeline 33D, which are return lines for supplying the high-temperature intermediate refrigerant MR.

[0063] In the sixth embodiment, the intermediate refrigerant line 30 includes a flow path switching unit 34 that switches between a first path RP1 (see Figure 8) that circulates the intermediate refrigerant MR between the second refrigeration cycle 20 and the first refrigeration cycle 10, and a second path RP2 (see Figure 9) that circulates the intermediate refrigerant MR between the cooling tower 6 and the first refrigeration cycle 10. The intermediate refrigerant line 30 also includes a first pump 32A that circulates the intermediate refrigerant MR in the first path RP1, and a second pump 32B that circulates the intermediate refrigerant MR in the second path RP2.

[0064] The flow path switching section 34 has a pair of first valves 34A and 34B and a pair of second valves 34C and 34D. The first valves 34A and 34B are provided in pipelines 33E and 33F, respectively, and open and close the pipelines. The second valves 34C and 34D are provided in pipelines 33C and 33D, respectively, and open and close the pipelines. The first pump 32A is provided in pipeline 33A, but may also be provided in pipeline 33B. The second pump 32B is provided in pipeline 33C, but may also be provided in pipeline 33D. In Figures 8 and 9, valves shown in white indicate an open state that allows the passage of intermediate refrigerant MR, and valves shown in black indicate a closed state that blocks the passage of intermediate refrigerant MR.

[0065] As shown in Figure 8, the flow path switching unit 34 switches the intermediate refrigerant line 30 to the first path RP1 by opening a pair of first valves 34A and 34B and closing a pair of second valves 34C and 34D. The first path RP1 is a path that circulates the intermediate refrigerant MR between the air conditioner 4, the first refrigeration cycle 10, and the demand equipment 5 using the first pump 32A, while also blocking the flow of the intermediate refrigerant MR to the cooling tower 6. Therefore, when the intermediate refrigerant line 30 is switched to the first path RP1, the intermediate refrigerant MR is cooled by the air conditioner 4 (second refrigeration cycle 20).

[0066] As shown in Figure 9, the flow path switching unit 34 switches the intermediate refrigerant line 30 to the second path RP2 by closing a pair of first valves 34A and 34B and opening a pair of second valves 34C and 34D. The second path RP2 is a path that circulates the intermediate refrigerant MR between the cooling tower 6, the first refrigeration cycle 10, and the demand equipment 5 using the second pump 32B, while also blocking the flow of the intermediate refrigerant MR to the air conditioner 4. Therefore, when the intermediate refrigerant line 30 is switched to the second path RP2, the intermediate refrigerant MR is cooled by the cooling tower 6.

[0067] The refrigeration system 1E includes a control unit 40 that controls the switching operation of the flow path switching unit 34. The control unit 40 includes a computer system. The control unit 40 has a processor such as a CPU, a main memory including non-volatile memory such as ROM and volatile memory such as RAM, storage, and an interface including input / output circuits. The functions of the control unit 40 are stored in the storage as a computer program. The processor reads the computer program from the storage, expands it into the main memory, and executes predetermined processing according to the computer program. The control unit 40 controls the opening and closing of a pair of first valves 34A, 34B and a pair of second valves 34C, 34D by transmitting control signals to each valve of the flow path switching unit 34.

[0068] This configuration allows the refrigeration system 1E to select between the air conditioner 4 (second refrigeration cycle 20) and the cooling tower 6 as the cooling devices for the intermediate refrigerant MR supplied to the first refrigeration cycle 10. For example, the cooling devices can be switched between summer, when the outside temperature is high, and winter, when the outside temperature is low.

[0069] Specifically, in summer, the cooling capacity of the cooling tower 6 is insufficient due to the high ambient temperature. Therefore, in summer, as shown in Figure 8, the control unit 40 controls the flow path switching unit 34 to switch the intermediate refrigerant line 30 to the first path RP1. This allows the air conditioner 4 (second refrigeration cycle 20) to cool the intermediate refrigerant MR. For example, the air conditioner 4 receives the intermediate refrigerant MR at 12°C in the evaporator 24 (see Figure 6) and cools it to the target temperature of 7°C. The air conditioner 4 releases heat to the cooling water from the cooling tower 6 in the condenser 22 (see Figure 6). The cooling tower 6 receives cooling water heated to 37°C via piping 6A and supplies the cooling water cooled to 32°C to the condenser 22. The intermediate refrigerant MR cooled to 7°C is supplied to the first refrigeration cycle 10 via the intermediate refrigerant line 30. The first refrigeration cycle 10 cools the object to be cooled 2 from -80°C to -85°C using an intermediate refrigerant MR at 7°C.

[0070] On the other hand, in winter, the demand for cooling by the air conditioner 4 is low, and refrigeration by the air conditioner 4 may not be necessary. Because the outside temperature is low, the cooling tower 6 can sufficiently cool the intermediate refrigerant MR. For this reason, in winter, as shown in Figure 9, the control unit 40 controls the flow path switching unit 34 to switch the intermediate refrigerant line 30 to the second path RP2. This cools the intermediate refrigerant MR with the cooling tower 6. For example, the cooling tower 6 receives the intermediate refrigerant MR at 12°C and cools it to 7°C by using the latent heat of vaporization to dissipate heat to the outside air. The intermediate refrigerant MR cooled to 7°C is supplied to the first refrigeration cycle 10 via the intermediate refrigerant line 30. The first refrigeration cycle 10 cools the object to be cooled 2 from -80°C to -85°C with the intermediate refrigerant MR at 7°C.

[0071] As a result, even when the second refrigeration cycle 20 is configured by the air conditioner 4, the first refrigeration cycle 10 is less affected by changes in the operating state of the air conditioner 4.

[0072] [Seventh Embodiment] Figure 10 is a schematic diagram showing a refrigeration system according to the seventh embodiment. In the seventh embodiment, in addition to the sixth embodiment described above, an example of a configuration that further suppresses temperature fluctuations in the first refrigeration cycle 10 is shown.

[0073] The first refrigeration cycle 10 according to the seventh embodiment is, for example, a Brayton cycle type refrigeration cycle as shown in Figure 4. As described above, the first refrigeration cycle 10 includes a compressor 11 for compressing the refrigerant, a prime mover 12 for driving the compressor 11, an intermediate refrigerant heat exchanger 13 for cooling the refrigerant with an intermediate refrigerant MR, and an expander 14 for expanding the refrigerant.

[0074] The refrigeration system 1F according to the seventh embodiment includes a detection unit 50 that detects the temperature T of the cooling target 2 in the first refrigeration cycle 10. The detection unit 50 includes a temperature sensor and outputs the temperature detection data to the control unit 40.

[0075] The control unit 40 controls the operation of the flow path switching unit 34. In the seventh embodiment, the control unit 40 controls the prime mover 12 to maintain the temperature T of the cooling target 2 based on the output signal of the detection unit 50 in response to the operation of the flow path switching unit 34. Although Figure 10 shows an example in which a single control unit 40 controls both the operation of the flow path switching unit 34 and the prime mover 12 of the first refrigeration cycle 10, the system is not limited to this. The control unit that controls the operation of the flow path switching unit 34 and the control unit that controls the prime mover 12 of the first refrigeration cycle 10 may be composed of separate, independent devices and may operate in conjunction with each other through mutual communication.

[0076] The control unit 40 controls the flow path switching unit 34 to selectively switch the intermediate refrigerant line 30 between the first path RP1 and the second path RP2. The temperature and flow rate of the intermediate refrigerant MR may change depending on whether the intermediate refrigerant MR cooled by the air conditioner 4 (second refrigeration cycle 20) is sent to the first refrigeration cycle 10 via the first path RP1 or via the second path RP2. When the temperature and flow rate of the intermediate refrigerant MR change, the amount of heat used for cooling by the intermediate refrigerant MR in the first refrigeration cycle 10 changes. This change in the amount of heat used for cooling may cause a temporary change in the temperature of the object to be cooled 2.

[0077] Therefore, in the seventh embodiment, when the flow path switching unit 34 switches between the first path RP1 and the second path RP2, the control unit 40 controls the prime mover 12 of the first refrigeration cycle 10 in accordance with the switching operation of the flow path switching unit 34. In other words, the control unit 40 initiates a process to control the prime mover 12 in advance to maintain the temperature T of the object to be cooled 2, before the temperature T of the object to be cooled changes due to fluctuations in the amount of cooling heat caused by the switching operation of the flow path switching unit 34.

[0078] The prime mover 12 is, for example, an electric motor, and the control unit 40 controls the rotational speed of the electric motor by inverter control. The compression ratio of the refrigerant in the refrigerant line 16 is adjusted by controlling the rotational speed of the electric motor. The prime mover 12 monitors the output signal (temperature T) of the detection unit 50 and increases or decreases its rotational speed so that the temperature T of the object to be cooled 2 is maintained at the target temperature. This suppresses the effect of transient fluctuations in the amount of cooling heat of the intermediate refrigerant MR during the switching operation between the first path RP1 and the second path RP2 on the temperature T of the object to be cooled 2.

[0079] In the seventh embodiment, in addition to the detection unit 50 that detects the temperature T of the cooling target 2, an inlet temperature sensor that detects the inlet temperature of the intermediate refrigerant MR in the intermediate refrigerant heat exchanger 13 of the first refrigeration cycle 10, and a flow rate sensor that detects the flow rate of the intermediate refrigerant MR supplied to the first refrigeration cycle 10 may be further provided. The control unit 40 can accurately adjust the temperature T of the cooling target 2 by controlling the prime mover 12 based on the output signals of the inlet temperature sensor and the flow rate sensor.

[0080] [Eighth Embodiment] Figure 11 is a schematic diagram showing a refrigeration system according to the eighth embodiment. In the eighth embodiment, a specific example of the cooling target 2 of the first refrigeration cycle 10 is shown.

[0081] The refrigeration system 1G according to the eighth embodiment is configured as a chiller for semiconductor manufacturing and inspection equipment. Specifically, in the refrigeration system 1G, the cooling target 2 of the first refrigeration cycle 10 is the process gas PG of the semiconductor manufacturing and inspection equipment 7. The process gas PG is supplied to the semiconductor manufacturing and inspection equipment 7 from a gas source via a gas supply line 7A. The first refrigeration cycle 10 cools the process gas PG, which is the cooling target 2, to a preset cooling target temperature. The semiconductor manufacturing and inspection equipment 7 is, for example, an etching apparatus that performs etching on a processing target such as a semiconductor wafer using the process gas PG, or a low-temperature inspection apparatus that performs low-temperature testing on a manufactured semiconductor device (or electronic equipment incorporating the semiconductor device).

[0082] In Figure 11, the first refrigeration cycle 10 is a closed cycle comprising an annular refrigerant line 16 through which the refrigerant 16C circulates. The refrigerant line 16 is an independent flow path that does not communicate with the gas supply line 7A. The first refrigeration cycle 10 includes a first heat exchanger 51 for cooling the process gas PG.

[0083] The first heat exchanger 51 includes a low-temperature side passage through which refrigerant 16C flows and a high-temperature side passage through which process gas PG flows, and the low-temperature side passage and the high-temperature side passage are separated by a heat transfer surface so that heat exchange can occur. The low-temperature side passage is connected to the refrigerant line 16 and constitutes a part of the refrigerant line 16. The high-temperature side passage is connected to the gas supply line 7A and constitutes a part of the gas supply line 7A. The first heat exchanger 51 cools the process gas PG with the refrigerant 16C cooled in the first refrigeration cycle 10. The first heat exchanger 51 is a gas-to-gas heat exchanger that exchanges heat between the gas-phase refrigerant 16C and the process gas PG.

[0084] The cooled process gas PG is introduced into the semiconductor manufacturing and inspection equipment 7 by a vacuum pump or the like, used for etching, and then exhausted.

[0085] In etching processes, the temperature of the process gas PG significantly affects etching quality and efficiency, requiring precise temperature control regardless of the season. The refrigeration system 1G according to the eighth embodiment can reduce the influence of ambient temperature fluctuations on the first refrigeration cycle 10 and is robust against ambient temperature fluctuations, thus enabling precise temperature control of the process gas PG.

[0086] [Ninth Embodiment] Figure 12 is a schematic diagram showing a refrigeration system according to the ninth embodiment. The ninth embodiment shows an example in which process gas PG is cooled via a secondary refrigerant BR.

[0087] As shown in Figure 12, in the refrigeration system 1H according to the ninth embodiment, similar to the eighth embodiment, the object to be cooled 2 in the first refrigeration cycle 10 is the process gas PG of the semiconductor manufacturing and inspection equipment 7. In the ninth embodiment, the first refrigeration cycle 10 cools the secondary refrigerant BR with a refrigerant, and then cools the process gas PG with the cooled secondary refrigerant BR.

[0088] Specifically, the first refrigeration cycle 10 includes a second heat exchanger 52 that cools the secondary refrigerant BR with refrigerant 16C, and a secondary refrigerant line 53 that circulates the secondary refrigerant BR between the first heat exchanger 51 and the second heat exchanger 52.

[0089] The second heat exchanger 52 includes a low-temperature side passage through which refrigerant 16C flows and a high-temperature side passage through which secondary refrigerant BR flows, and the low-temperature side passage and the high-temperature side passage are separated by a heat transfer surface so as to be able to exchange heat. The low-temperature side passage is connected to refrigerant line 16 and constitutes a part of refrigerant line 16. The high-temperature side passage is connected to secondary refrigerant line 53 and constitutes a part of secondary refrigerant line 53. The second heat exchanger 52 cools the secondary refrigerant BR with refrigerant 16C cooled in the first refrigeration cycle 10. The secondary refrigerant BR is not particularly limited, but is a liquid refrigerant, for example, brine. Therefore, the second heat exchanger 52 is a gas-to-liquid heat exchanger.

[0090] The secondary refrigerant line 53 is an annular flow path for circulating the secondary refrigerant BR, and passes through the first heat exchanger 51 and the second heat exchanger 52. The secondary refrigerant line 53 is equipped with a pump or the like for circulating the secondary refrigerant BR. The secondary refrigerant line 53 may also be connected to other parts of the semiconductor manufacturing and inspection equipment 7, or to other cooling and heating equipment related to the semiconductor manufacturing and inspection equipment 7. This allows multiple cooling targets 2, including process gas PG, to be cooled by the secondary refrigerant BR.

[0091] The first heat exchanger 51 includes a low-temperature side passage through which secondary refrigerant BR flows and a high-temperature side passage through which process gas PG flows. The low-temperature side passage is connected to the secondary refrigerant line 53 and constitutes part of the secondary refrigerant line 53. The high-temperature side passage is connected to the gas supply line 7A and constitutes part of the gas supply line 7A. The first heat exchanger 51 cools the process gas PG with the secondary refrigerant BR cooled in the first refrigeration cycle 10. The first heat exchanger 51 is a gas-to-liquid heat exchanger.

[0092] In the refrigeration system 1H according to the ninth embodiment, a secondary refrigerant BR, which is a brine solution, is interposed between the refrigerant 16C of the first refrigeration cycle 10 and the process gas PG, which is the object to be cooled 2. As a result, even if the refrigerant temperature of the first refrigeration cycle 10 fluctuates due to fluctuations in ambient temperature, the effect of the fluctuations in refrigerant temperature can be mitigated by the heat capacity of the brine solution, thereby suppressing temperature changes in the object to be cooled 2 (process gas PG).

[0093] [Effects of the Embodiment] The refrigeration system 1 according to the first embodiment comprises: a first refrigeration cycle 10 that cools the object to be cooled 2 by discharging heat to an intermediate refrigerant MR, with a temperature of the object to be cooled of 0°C or lower; a second refrigeration cycle 20 that cools the intermediate refrigerant MR by discharging heat directly or indirectly to the atmosphere, with a temperature of the object to be cooled of 0°C or higher; and an intermediate refrigerant line 30 that circulates the intermediate refrigerant MR between the first refrigeration cycle 10 and the second refrigeration cycle 20.

[0094] According to the first embodiment of the refrigeration system 1, the intermediate refrigerant MR cooled by the second refrigeration cycle 20 is supplied to the first refrigeration cycle 10 via the intermediate refrigerant line 30, and the object to be cooled 2 can be cooled in the first refrigeration cycle 10 by the heat discharged to the intermediate refrigerant MR. The second refrigeration cycle 20 is affected by fluctuations in ambient temperature because it discharges heat into the atmosphere, but since the intermediate refrigerant MR cooled by the second refrigeration cycle 20 is supplied to the first refrigeration cycle 10, the influence of fluctuations in ambient temperature on the first refrigeration cycle 10 can be reduced. As a result, a refrigeration system 1 that is robust to fluctuations in ambient temperature can be realized.

[0095] The refrigeration system 1 according to the second embodiment is the refrigeration system 1 according to the first embodiment, wherein the first refrigeration cycle 10 has a cooling target temperature of -40°C or lower. In a refrigeration cycle, the lower the temperature of the cooling target 2, the greater the power consumption required to achieve the same refrigeration capacity, and the lower the refrigeration performance (COP). Therefore, refrigeration cycles with a cooling target temperature of -40°C or lower tend to have low refrigeration performance to begin with. In contrast, the second refrigeration cycle 20 with a cooling target temperature of 0°C or higher has relatively high refrigeration performance, and by cooling the intermediate refrigerant MR with this second refrigeration cycle 20, refrigeration performance can be improved even when generating ultra-low temperatures of -40°C or lower.

[0096] The third embodiment of the refrigeration system 1 is the same as the second embodiment of the refrigeration system 1, wherein the first refrigeration cycle 10 includes an inverse Brayton refrigeration cycle. The inverse Brayton refrigeration cycle has the characteristic of having higher refrigeration performance (COP) in the ultra-low temperature range of -40°C or below compared to other refrigeration cycles. Therefore, refrigeration performance can be effectively improved when generating ultra-low temperatures of -40°C or below.

[0097] The refrigeration system 1 according to the fourth embodiment is the refrigeration system 1 according to the second or third embodiment, wherein the second refrigeration cycle 20 includes a vapor compression refrigeration cycle. This makes it possible to obtain high refrigeration performance in the second refrigeration cycle 20 where the temperature to be cooled is 0°C or higher.

[0098] The fifth embodiment of the refrigeration system 1 is a refrigeration system 1 according to any one of the first to fourth embodiments, wherein the intermediate refrigerant MR is a liquid refrigerant containing water. This makes it easier to handle the intermediate refrigerant MR. Because water is a liquid, it has a high density, which allows for smaller piping and heat exchangers, thus contributing to improved refrigeration performance as well as miniaturization of the refrigeration system 1.

[0099] The sixth embodiment of the refrigeration system 1 is a refrigeration system 1 according to any one of the first to fifth embodiments, and includes a second refrigeration cycle 20, and is equipped with an air conditioner 4 that supplies intermediate refrigerant MR to the demand equipment 5, with a portion of the intermediate refrigerant MR from the air conditioner 4 being supplied to the first refrigeration cycle 10 via an intermediate refrigerant line 30. For example, industrial facilities such as factories and plants generally have air conditioners 4 equipped with refrigeration cycles. In this case, a portion of the refrigerant supplied from the air conditioner 4 can be used as intermediate refrigerant MR for the first refrigeration cycle 10. Compared to the case where a dedicated second refrigeration cycle 20 is installed separately from the air conditioner 4 in an industrial facility, the installation of additional equipment can be avoided, and the refrigeration system 1 can be made more space-efficient.

[0100] The seventh embodiment of the refrigeration system 1 is the same as the sixth embodiment of the refrigeration system 1, wherein the intermediate refrigerant line 30 is connected to the cooling tower 6 in addition to the second refrigeration cycle 20, and the intermediate refrigerant line 30 includes a flow path switching unit 34 that switches between a first path RP1 that circulates the intermediate refrigerant MR between the second refrigeration cycle 20 and the first refrigeration cycle 10, and a second path RP2 that circulates the intermediate refrigerant MR between the cooling tower 6 and the first refrigeration cycle 10. As a result, in winter when the ambient temperature is low, or when the air conditioner 4 is stopped, the cooling tower 6 can be used to remove heat from the intermediate refrigerant MR by switching to the second path RP2. The air conditioner 4, including the second refrigeration cycle 20, operates in response to the air conditioning needs of the demand equipment 5, so the refrigeration system 1 (first refrigeration cycle 10) can be operated regardless of the operating status of the air conditioner 4.

[0101] The eighth embodiment of the refrigeration system 1 is the seventh embodiment of the refrigeration system 1, wherein the first refrigeration cycle 10 includes a compressor 11 for compressing a refrigerant, a prime mover 12 for driving the compressor 11, a heat exchanger (intermediate refrigerant heat exchanger 13) for cooling the refrigerant with an intermediate refrigerant MR, and an expander 14 for expanding the refrigerant, and further comprises a detection unit 50 for detecting the temperature T of the object to be cooled in the first refrigeration cycle 10, and a control unit 40 that controls the prime mover 12 to maintain the temperature T of the object to be cooled 2 based on the output signal of the detection unit 50 in accordance with the operation of the flow path switching unit 34. When the flow path switching unit 34 performs a path switch, the amount of cooling heat of the intermediate refrigerant MR fluctuates, and the fluctuation in the amount of cooling heat may affect the temperature T of the object to be cooled 2 in the first refrigeration cycle 10. Therefore, when the flow path switching unit 34 operates, the control unit 40 controls the operation of the prime mover 12 to maintain the temperature T of the object to be cooled 2, thereby stabilizing the temperature of the object to be cooled in the first refrigeration cycle 10.

[0102] The refrigeration system 1 according to the ninth embodiment is a refrigeration system 1 according to any one of the first to eighth embodiments, wherein the object to be cooled 2 of the first refrigeration cycle 10 is the process gas PG of semiconductor manufacturing and inspection equipment 7, and the first refrigeration cycle 10 includes a first heat exchanger 51 for cooling the process gas PG. Since the process gas PG of semiconductor manufacturing and inspection equipment 7 requires precise temperature control regardless of the season, cooling by the first refrigeration cycle 10, which is robust to fluctuations in ambient temperature and provides stable cooling, is effective.

[0103] The refrigeration system 1 according to the tenth embodiment is the refrigeration system 1 according to the ninth embodiment, wherein the first refrigeration cycle 10 includes a second heat exchanger 52 that cools the secondary refrigerant BR with refrigerant 16C, and a secondary refrigerant line 53 that circulates the secondary refrigerant BR between the first heat exchanger 51 and the second heat exchanger 52. As a result, even if a temperature fluctuation occurs on the first refrigeration cycle 10 side, the heat capacity of the secondary refrigerant BR mitigates the effect of the temperature fluctuation on the process gas PG side, and the temperature change of the object to be cooled 2 (process gas PG) can be suppressed.

[0104] A refrigeration method according to the eleventh embodiment is a refrigeration method in a refrigeration system 1 comprising a first refrigeration cycle 10 and a second refrigeration cycle 20, comprising the steps of: cooling an intermediate refrigerant MR by directly or indirectly discharging heat to the atmosphere from the second refrigeration cycle 20, which has a cooling target temperature of 0°C or higher; circulating the intermediate refrigerant MR between the first refrigeration cycle 10 and the second refrigeration cycle 20; and cooling a cooling target 2 by discharging heat to the intermediate refrigerant MR from the first refrigeration cycle 10, which has a cooling target temperature of 0°C or lower.

[0105] According to the 11th embodiment of the refrigeration method, the intermediate refrigerant MR cooled by the second refrigeration cycle 20 is supplied to the first refrigeration cycle 10 via the intermediate refrigerant line 30, and the object to be cooled 2 can be cooled in the first refrigeration cycle 10 by the heat discharged to the intermediate refrigerant MR. The second refrigeration cycle 20 is affected by fluctuations in ambient temperature because it discharges heat into the atmosphere, but since the intermediate refrigerant MR cooled by the second refrigeration cycle 20 is supplied to the first refrigeration cycle 10, the influence of fluctuations in ambient temperature on the first refrigeration cycle 10 can be reduced. As a result, a refrigeration system 1 that is robust to fluctuations in ambient temperature can be realized.

[0106] Although embodiments of the present disclosure have been described above, the embodiments are not limited to those described herein. Furthermore, the aforementioned components include those that can be easily conceived by those skilled in the art, those that are substantially the same, and those that fall within the so-called equivalent range. Moreover, the aforementioned components can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the gist of the embodiments described above.

[0107] For example, the descriptions of the temperatures of the outside air, refrigerant, and object to be cooled shown in each of the embodiments described above are examples only and are not limited to those described above.

[0108] 1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H Refrigeration system 2 Cooling target 4 Air conditioner 5 Demand equipment 6 Cooling tower 7 Semiconductor manufacturing and inspection equipment 10 First refrigeration cycle 11 Compressor 12 Prime mover 13 Intermediate refrigerant heat exchanger (heat exchanger) 14 Expander 16C Refrigerant 20 Second refrigeration cycle 30 Intermediate refrigerant line 34 Flow path switching unit 40 Control unit 50 Detection unit 51 First heat exchanger 52 Second heat exchanger 53 Secondary refrigerant line BR Secondary refrigerant MR Intermediate refrigerant PG Process gas RP1 First path RP2 Second path T Temperature

Claims

1. A refrigeration system comprising: a first refrigeration cycle that cools an object to be cooled by discharging heat to an intermediate refrigerant, with the temperature of the object to be cooled being 0°C or lower; a second refrigeration cycle that cools the intermediate refrigerant by discharging heat directly or indirectly to the atmosphere, with the temperature of the object to be cooled being 0°C or higher; and an intermediate refrigerant line that circulates the intermediate refrigerant between the first refrigeration cycle and the second refrigeration cycle.

2. The refrigeration system according to claim 1, wherein the first refrigeration cycle has a target temperature of -40°C or lower.

3. The refrigeration system according to claim 2, wherein the first refrigeration cycle includes an inverse Brayton refrigeration cycle.

4. The refrigeration system according to claim 2, wherein the second refrigeration cycle includes a vapor compression refrigeration cycle.

5. The refrigeration system according to claim 3, wherein the intermediate refrigerant is a liquid refrigerant containing water.

6. The refrigeration system according to claim 5, comprising the second refrigeration cycle and an air conditioner that supplies the intermediate refrigerant to a demand facility, wherein a portion of the intermediate refrigerant from the air conditioner is supplied to the first refrigeration cycle via the intermediate refrigerant line.

7. The refrigeration system according to claim 6, wherein the intermediate refrigerant line is connected to a cooling tower in addition to the second refrigeration cycle, and the intermediate refrigerant line includes a flow path switching unit that switches between a first path for circulating the intermediate refrigerant between the second refrigeration cycle and the first refrigeration cycle, and a second path for circulating the intermediate refrigerant between the cooling tower and the first refrigeration cycle.

8. The refrigeration system according to claim 7, wherein the first refrigeration cycle includes a compressor for compressing a refrigerant, a prime mover for driving the compressor, a heat exchanger for cooling the refrigerant with the intermediate refrigerant, and an expander for expanding the refrigerant, and further comprises a detection unit for detecting the temperature of the object to be cooled in the first refrigeration cycle, and a control unit that controls the prime mover to maintain the temperature of the object to be cooled based on the output signal of the detection unit in accordance with the operation of the flow path switching unit.

9. The refrigeration system according to any one of claims 1 to 8, wherein the object to be cooled by the first refrigeration cycle is a process gas for semiconductor manufacturing and inspection equipment, and the first refrigeration cycle includes a first heat exchanger for cooling the process gas.

10. The refrigeration system according to claim 9, wherein the first refrigeration cycle includes a second heat exchanger for cooling a secondary refrigerant with a refrigerant, and a secondary refrigerant line for circulating the secondary refrigerant between the first heat exchanger and the second heat exchanger.

11. A refrigeration method in a refrigeration system comprising a first refrigeration cycle and a second refrigeration cycle, comprising the steps of: cooling an intermediate refrigerant by directly or indirectly discharging heat to the atmosphere from the second refrigeration cycle, where the temperature of the object to be cooled is 0°C or higher; circulating the intermediate refrigerant between the first refrigeration cycle and the second refrigeration cycle; and cooling the object to be cooled by discharging heat to the intermediate refrigerant from the first refrigeration cycle, where the temperature of the object to be cooled is 0°C or lower.

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