Cold storage type refrigeration system

Abstract

To improve efficiency in cooling at a cryogenic temperature that can attain superconductivity.SOLUTION: In a cold storage type refrigerator 10 having a pulse tube 14, a heat exchanger 200 is provided between a cold storage unit (low temperature side) 16 and a cold storage unit (high temperature side) 17. In the heat exchanger 200, by supplying a refrigerant of a steam compression type refrigerator 30, cooling is performed to attain an intermediate temperature between a high temperature end 18 (room temperature) and a low temperature end 15 of the cold storage type refrigerator. That is, heat from the cold storage type refrigerator 10 is extracted by a portion of the heat exchanger 200. Thus even when power consumption in the steam compression type refrigerator 30 is considered, cooling efficiency as the entire system can be improved.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a regenerative refrigeration system that realizes extremely low temperature cooling, and more particularly to a technique for improving the cooling efficiency thereof. [Background technology]

[0002] Generally, to realize superconductivity, an environment of about 20 to 40K is required. Regenerative refrigerators are often used as devices to realize such cooling. Known regenerative refrigerators include Stirling refrigerators, GM (Gifford-McMahon) refrigerators, and pulse tube refrigerators. However, although regenerative refrigerators can realize extremely low temperature freezing, their cooling efficiency cannot be said to be sufficiently high.

[0003] Patent Document 1 discloses a cascade type cryogenic refrigerator as a technology for improving the cooling efficiency of a regenerative refrigerator, in which a vapor compression refrigerator cools from room temperature to a predetermined intermediate temperature, and a regenerative refrigerator cools from the intermediate temperature to a cryogenic temperature. As shown in Fig. 1, in a cascade type cryogenic refrigerator, a heat exchanger is provided at the high temperature end of the regenerative refrigerator and the pulse tube in a regenerative refrigerator equipped with a compressor, a regenerator, a pulse tube, and a buffer tank, and heat is exchanged with a refrigerant cooled to an intermediate temperature by a separately prepared vapor compression refrigerator. In this way, the high temperature end becomes the intermediate temperature, and the regenerative refrigerator is responsible for cooling from the intermediate temperature to the cryogenic temperature. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2022-175537 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the cooling efficiency of the conventional technology is not sufficient, and there is a demand for and room for further improvement. An object of the present invention is to improve the cooling efficiency of a regenerative refrigerator to a very low temperature. [Means for solving the problem]

[0006] The present invention provides a regenerative refrigeration system, a regenerative refrigerator having a pressure drive source, a regenerator having a high-temperature end and a low-temperature end at both ends, and a phase adjuster; a heat exchanger provided between the high temperature end and the low temperature end and performing heat exchange at an intermediate temperature set between the temperatures at the high temperature end and the low temperature end; The heat exchanger may further include a cooling mechanism for cooling the heat exchanger.

[0007] According to the present invention, the heat exchanger can extract heat from the regenerator (hereinafter, this may be referred to as "heat extraction"). In other words, the regenerator is cooled to an intermediate temperature between the high temperature end and the low temperature end. By extracting heat, the cooling efficiency of the regenerative refrigerator can be improved, and the overall cooling efficiency can be improved even when the power consumed by the cooling mechanism is taken into account. In conventional cascade-type cryogenic refrigerators, the power consumption required to cool the high-temperature end of the regenerative refrigerator to an intermediate temperature can be high. However, in the present invention, the cooling of the high-temperature end is avoided, thereby making it possible to further improve the cooling efficiency.

[0008] In the present invention, the cooling mechanism may be a mechanism for supplying a coolant, such as liquid nitrogen, whose temperature is equal to or lower than an intermediate temperature, to the heat exchanger. This has the advantage that the power consumed by the cooling mechanism can be made extremely small.

[0009] In the present invention, the heat exchanger can be provided in various ways. For example, the heat exchanger may be attached to any part of an integrated regenerator. Alternatively, the regenerator may be divided into a high-temperature side and a low-temperature side, and the heat exchanger may be attached to the connecting part connecting the two. In either case, the heat exchanger may be attached to the outside of the regenerator, or may be incorporated into a part of the regenerator.

[0010] In the present invention, two or more heat exchangers and cooling mechanisms may be provided. For example, the regenerator may be provided with a heat exchanger and cooling mechanism that extracts heat at a first intermediate temperature, and a heat exchanger and cooling mechanism that extracts heat at a second intermediate temperature. It is also possible to provide three or more.

[0011] On the other hand, in the present invention, The cooling mechanism may be a refrigerator of a type different from the regenerative refrigerator.

[0012] If the above-mentioned refrigerator is selected to have a higher cooling efficiency from room temperature to an intermediate temperature than the regenerative refrigerator, it is possible to improve the cooling efficiency of the entire regenerative refrigerator system, even when taking into account the power consumption of the refrigerator. As the refrigerator, for example, a vapor compression refrigerator, a Brayton refrigerator, a Stirling refrigerator, etc. can be used. From the viewpoint of cooling efficiency, a vapor compression refrigerator is particularly preferable. The cooling mechanism may be realized by combining a plurality of types of mechanisms. For example, a mechanism for supplying a refrigerant having an intermediate temperature or lower, such as liquid nitrogen, to the heat exchanger may be combined with any of the above-mentioned refrigerators, or a plurality of types of the above-mentioned refrigerators may be combined. The refrigerator is not limited to being operated constantly, but can be operated in various modes, such as being operated intermittently or being switched on and off depending on whether a predetermined condition is met.

[0013] In the present invention, the intermediate temperature can be set arbitrarily. When a refrigerant such as liquid nitrogen is used, the intermediate temperature may be determined by the temperature of the refrigerant.

[0014] When using a refrigerator, When the cooling efficiency is defined as cooling capacity / power consumption, the intermediate temperature may be set so that the cooling efficiency taking into account the total value of the power consumption of the regenerative refrigerator and the refrigerator is higher than the cooling efficiency of the regenerative refrigerator alone.

[0015] The total power consumption (i.e., "power consumption of the regenerative refrigerator + power consumption of the refrigerator") and the refrigeration capacity of the regenerative refrigerator vary depending on the setting value of the intermediate temperature. In the above embodiment, the cooling efficiency (=refrigeration capacity / power consumption) can be used as an index for setting the intermediate temperature. The refrigeration capacity can be defined in various ways, but for example, it can be defined as the amount of heat (W) that can be absorbed per unit time at the low temperature end of a regenerative refrigerator.

[0016] The intermediate temperature may be set based on a lowest temperature to which the refrigerator can cool.

[0017] The above embodiment is considered to be equivalent to an embodiment in which heat is extracted close to the limit of the refrigerator's capacity. Since a regenerative refrigerator generally has poor cooling efficiency in a range higher than the intermediate temperature, it is considered possible to improve the overall cooling efficiency by entrusting the freezing in this range largely to the refrigerator. This embodiment also has the advantage that the intermediate temperature can be set relatively easily. The "lowest temperature at which cooling can be achieved" refers to the lower limit of a practical range. The cooling efficiency of a refrigerator varies depending on the cooling temperature. When the cooling temperature is lowered, the cooling efficiency gradually deteriorates, reaches a minimum value, improves to a maximum value, and then deteriorates again, in some cases varying like a cubic function. The lower limit of the practical range may be defined as the temperature corresponding to the maximum value mentioned above. It may also be defined as the temperature at which the cooling efficiency falls below the minimum value.

[0018] As the regenerative refrigerator of the present invention, various types of refrigerators can be used, such as a Stirling refrigerator, a GM (Gifford-McMahon) refrigerator, and a pulse tube refrigerator. Among these, the regenerative refrigerator is preferably a pulse tube refrigerator having a pulse tube connected to the low temperature end of the regenerator.

[0019] In the present invention, heat is extracted from the regenerator, so there is no need to extract heat from the pulse tube. The end of the pulse tube opposite the low-temperature end connected to the regenerator is the high-temperature end, but there is no need to cool this high-temperature end to an intermediate temperature. In the cascade type cryogenic refrigerator exemplified in the prior art, the vapor compression refrigerator is responsible for temperatures from room temperature to the intermediate temperature, and the regenerative refrigerator is responsible for temperatures below the intermediate temperature. This means that the high temperature end of the regenerative refrigerator needs to be cooled to the intermediate temperature, which reduces the overall cooling efficiency. In contrast, in the present invention, as described above, the high temperature end of the pulse tube does not need to be cooled to an intermediate temperature, and therefore the present invention is particularly useful for pulse tube refrigerators.

[0020] When using a pulse tube refrigerator, The regenerative refrigerator may have an end opposite to the low temperature end of the pulse tube that is open to room temperature.

[0021] In this embodiment, the high temperature end is exposed to room temperature. In this case, since there is no need to cool the high temperature end, the overall cooling efficiency can be further improved. However, the temperature of the high temperature end can be determined arbitrarily, and it is not necessarily required that the high temperature end be exposed to room temperature.

[0022] The present invention does not necessarily have to have all of the above-mentioned features, and may be configured by omitting or combining some of them as appropriate. The present invention can also be configured in various aspects such as an operation control method and a design method for a regenerative refrigeration system. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is an explanatory diagram showing the overall configuration of a cascade refrigerator according to a conventional technology. [Diagram 2] 1 is an explanatory diagram showing the overall configuration of a regenerative refrigeration system according to an embodiment; [Diagram 3] FIG. 2 is an explanatory diagram showing a configuration of a heat exchanger. [Figure 4] FIG. 1 is an explanatory diagram showing an analysis example of cooling efficiency in a regenerative refrigeration system. [Diagram 5] FIG. 11 is an explanatory diagram showing an analysis example of a change in cooling efficiency due to an intermediate temperature. [Figure 6] FIG. 13 is an explanatory diagram showing the overall configuration of a regenerative refrigeration system as a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] The regenerative refrigeration system will be described below as an embodiment. In the embodiment, an example of a device with a target cooling temperature of about 20K is shown, but the regenerative refrigeration system can be configured as a device that performs cooling to various cryogenic temperatures below liquid nitrogen regardless of the target cooling temperature.

[0025] FIG. 2 is an explanatory diagram showing the overall configuration of a regenerative refrigeration system according to an embodiment of the present invention. The regenerative refrigeration system includes a regenerative refrigerator 10 , a vapor compression refrigerator 30 , and a heat exchanger 200 .

[0026] The vapor compression refrigerator 30 is a device that performs cooling by compressing and expanding a gaseous refrigerant. In this embodiment, the refrigerator 30 performs cooling from the temperature of the place where the regenerative refrigeration system is installed (hereinafter simply referred to as "room temperature") to a predetermined intermediate temperature. The intermediate temperature can be set arbitrarily, and the method for setting it will be described later, but it is expected to be set at a temperature of around 100K.

[0027] Various types of refrigerators, such as a Stirling refrigerator, a GM (Gifford-McMahon) refrigerator, and a pulse tube refrigerator, can be used as the regenerative refrigerator 10. In this embodiment, a pulse tube refrigerator is used. As shown in the figure, the main body of the regenerative refrigerator 10 has a structure in which a pulse tube 14 and a regenerator (a regenerator (low temperature side) 16 and a regenerator (high temperature side) 17) are connected together. The high temperature end 13 of the pulse tube 14 and the high temperature end 18 of the regenerator (high temperature side) 17 are both at room temperature. The low-temperature end 15 between the pulse tube 14 and the regenerator (low-temperature side) 16 is the portion that cools the object to be cooled in the regenerative refrigeration system. In this embodiment, the temperature of the low-temperature end 15 is about 20K.

[0028] Since the heat exchanger 200 is provided between the cold storage unit (low temperature side) 16 and the cold storage unit (high temperature side) 17, for convenience, the lower temperature side than the heat exchanger 200 is called the cold storage unit (low temperature side) 16 and the higher temperature side is called the cold storage unit (high temperature side) 17, but as a device, both are configured as an integrated unit. However, this does not exclude a configuration in which the cold storage unit (low temperature side) 16 and the cold storage unit (high temperature side) 17 are separate units.

[0029] The pulse tube 14, regenerator (low temperature side) 16, and regenerator (high temperature side) 17 are filled with a gas such as helium, and a pressure wave with a sine wave or other shape is applied to the gas from a compressor 19 connected to the high temperature end 18 of the regenerator (high temperature side) 17. The gas moves back and forth in response to this pressure, thereby cooling it. A buffer tank 11 is connected to the high temperature end 13 of the pulse tube via an orifice valve 12 in order to adjust the phase difference of the pressure wave applied to the gas. The regenerative refrigerator 10 is not limited to the configuration shown in the figure, and may have various other configurations.

[0030] The heat exchanger 200 and the vapor compression refrigerator 30 are connected by a refrigerant pipe. In this way, the vapor compression refrigerator 30 can extract heat from the cold storage unit (low temperature side) 16 and the cold storage unit (high temperature side) 17 in the heat exchanger 200.

[0031] FIG. 3 is an explanatory diagram showing the configuration of the heat exchanger. FIG. 3(a) shows a perspective view of the heat exchanger 200. The heat exchanger 200 has a structure in which a plurality of flow passage layers 211a to 211d are laminated, each of which is formed by sandwiching a triangular corrugated metal plate between flat metal plates from above and below. In this embodiment, an example is shown in which the flow passages of the flow passage layers 211a and 211c and the flow passages of the flow passage layers 211b and 211d are laminated so as to be perpendicular to each other. Gas from the regenerative refrigerator 10 is passed through the flow passage layers 211a and 211c, and refrigerant cooled by the vapor compression refrigerator 30 is passed through the flow passage layers 211b and 211d. Since the flow passages of both are in contact with each other, heat exchange is performed and the temperature is cooled to an intermediate temperature. In the embodiment, the flow paths of the flow path layers 211a and 211c and the flow paths of the flow path layers 211b and 211d may be arranged in the same direction. In this case, the gas of the regenerative refrigerator 10 and the refrigerant cooled by the vapor compression refrigerator 30 may flow in the same direction or in opposite directions.

[0032] The heat exchanger is not limited to the structure shown in Fig. 3(a). For example, the gas and refrigerant flow paths may be formed by through holes formed in a single metal plate. Alternatively, cylindrical pipes forming each flow path may be arranged. In this case, since a circular cross section of the pipe reduces the contact area with adjacent pipes, it is preferable to make the cross section rectangular or hexagonal so that the pipes can be arranged without gaps, or to fill the gaps between the pipes with metal or other material with high thermal conductivity.

[0033] 3(b) shows a schematic diagram of the internal structure of the regenerator with the heat exchanger 200 installed. As shown in the figure, the heat exchanger 200 is installed between the regenerator (low temperature side) 16 and the regenerator (high temperature side) 17. Since the gas in the regenerator type refrigerator 10 flows in the vertical direction as indicated by the arrow A, the flow path layers 211a and 211c are installed along this direction. The flow path layers 211a and 211c through which the refrigerant flows are installed facing the direction of the arrow B. This allows heat exchange in the heat exchanger 200 to be performed without impeding the flow of gas in the regenerative refrigerator 10. However, the installation method of the heat exchanger 200 is not limited to this embodiment, and the heat exchanger 200 can be installed in various embodiments.

[0034] As shown in the lower part of Fig. 3(b), a heat exchanger 220 may be provided on the outer surfaces of the regenerator (low temperature side) 16 and the regenerator (high temperature side) 17. The heat exchanger 220 is configured by filling with a metal foam, a laminate of metal thin films, metal microspheres, or the like, and is wrapped around the outer circumference of the regenerator (high temperature side) 17. The heat exchanger 220 is connected to the vapor compression refrigerator 30 via a refrigerant inlet 221 and an outlet 222. The refrigerant flows into the heat exchanger 220 as indicated by an arrow C, exchanges heat, and is then discharged as indicated by an arrow D. The heat exchanger 220 may be provided in conjunction with the heat exchanger 200 or may be provided in place of the heat exchanger 200 .

[0035] Fig. 4 is an explanatory diagram showing an example of analysis of cooling efficiency in a regenerative refrigeration system. Fig. 4(a) shows an analysis model for a single regenerative refrigerator, and Fig. 4(c) shows an analysis model for the regenerative refrigeration system of the embodiment. Fig. 4(b) shows the analysis results for a single regenerative refrigerator on the left side, and the analysis results for the regenerative refrigeration system of the embodiment on the right side. T1 to T10 respectively represent temperatures (K) at the locations shown in Fig. 4(a) and Fig. 4(c).

[0036] First, the following values ​​were set as calculation conditions common to both. Temperature T2 (temperature at compressor outlet): Room temperature 300K Temperature T7 (temperature of low temperature part): 20K Pulse tube adiabatic expansion efficiency: 75% Compressor adiabatic efficiency: 75% Compressor mechanical efficiency: 90% High pressure side pressure: 2.4MPa Low pressure side pressure: 1.2MPa Refrigerant gas (helium gas) flow rate: 0.0025 kg / sec

[0037] In addition, the conditions for a single regenerative refrigerator (Figure 4(a)) are as follows: Cool storage (heat exchanger) efficiency: 99% It was decided. In contrast, the conditions for a regenerative refrigeration system (Figure 4(c)) are as follows: High temperature side cool storage (heat exchanger) efficiency: 98% Low temperature side regenerator (heat exchanger) efficiency: 99% Extraction section (heat exchanger 200) efficiency: 90% Temperature T4 (intermediate temperature in heat exchanger 200): 100K It was decided.

[0038] Based on the above conditions, the temperature, enthalpy, and entropy at each part were calculated, and the results are shown in Figure 4(b).

[0039] The cooling capacities Q1 and Q2 at the low temperature end are expressed by the following equations, where the refrigerant gas flow rate is m, the temperature difference is (T7-T6), and the specific heat of the refrigerant gas is Cp (=5223 J / kg K). Q1 or Q2=m Cp (T7-T6) Therefore, the ratio Q2 / Q1 of the cooling capacity Q2 in the regenerative refrigeration system to the cooling capacity Q1 of the regenerative refrigerator alone is approximately three times as follows: Q2 / Q1=(20-17.76) / (20-19.26) =2.24 / 0.74 =3.03

[0040] The amount of heat Q3 extracted in the heat exchanger 200 is given by the following equation, assuming that the refrigerant gas flow rate is m (0.0025 kg / sec), the temperature difference is (T3-T4), and the specific heat of the refrigerant gas is Cp (=5223 J / kg K): Q3=m Cp (T3-T4) =0.0025×5223×3.27 =about 43W It is required.

[0041] Fig. 5 is an explanatory diagram showing an analysis example of the change in cooling efficiency due to the intermediate temperature. The cooling efficiency COP is defined as cooling capacity / power consumption. FIG. 5(a) shows a schematic diagram of heat exchange in a regenerative refrigerator system. The cooling efficiency COP10 represents the cooling efficiency of the regenerative refrigerator 10. The high temperature end temperature TH is 300K, and the low temperature end temperature TL is 20K. At the low temperature end, the heat extracted from the object to be cooled is represented by Q1 (in the case of a single regenerative refrigerator) or Q2 (in the case of a regenerative refrigerator system). The power consumption to drive the regenerative refrigerator 10 is represented by Q0. In the regenerative refrigeration system, the vapor compression refrigerator 30 extracts heat from the regenerative refrigerator 10 in the heat exchanger 200. This heat is represented by Q3. The intermediate temperature during extraction is represented by TM. The vapor compression refrigerator 30 performs cooling from the outlet temperature (T3) of the regenerator (high temperature side) 17 to an intermediate temperature TM. The power consumption required for this cooling is represented by Q4.

[0042] Figure 5(b) shows the analysis results of the cooling efficiency for each intermediate temperature. The leftmost column (case where intermediate temperature is not set) shows the case where the vapor compression refrigerator 30 is not used, i.e., the case where only the regenerative refrigerator is used. If the cooling efficiency COP10 of the regenerative refrigerator 10 in this state is 0.005 and the power consumption Q0 is 2000 W, then the cooling capacity Q1 is calculated as 10 W (= 2000 x 0.005). The cooling efficiency (total COP) of the entire regenerative refrigerator system is 0.005, the same as COP10.

[0043] This shows the case of intermediate temperature 100K. Power consumption is 2000W. As explained above in Fig. 4, the analysis results show that when the intermediate temperature is 100K, the cooling efficiency at the low temperature end is about three times that of a single regenerative refrigerator. Therefore, the cooling capacity Q2 is 30W. 4, the heat Q3 extracted by the heat exchanger 200 is 43 W. If the cooling efficiency COP30 of the vapor compression refrigerator 30 when cooling from room temperature 300 K to the intermediate temperature 100 K is 0.1, the power consumption Q4 in the vapor compression refrigerator 30 is calculated as 430 W (=43 / 0.1). As a result, the overall COP is calculated as follows: Total COP=30 / (2000+430)=0.0123

[0044] This shows the case of intermediate temperature 150K. Power consumption is 2000W. Furthermore, as a result of the same analysis as explained in Fig. 4, when the intermediate temperature is 150K, the cooling efficiency at the low temperature end is found to be about 2.5 times that of a single regenerative refrigerator. Therefore, the cooling capacity Q2 is 25W. 4, when the refrigerant gas flow rate m is assumed, in the case of an intermediate temperature of 150 K, the heat Q3 extracted by the heat exchanger 200 is 22 W. If the cooling efficiency COP30 of the vapor compression chiller 30 during cooling from room temperature 300 K to the intermediate temperature 150 K is 0.25, the power consumption Q4 in the vapor compression chiller 30 is calculated to be 88 W. As a result, the overall COP is calculated as follows: Total COP=25 / (2000+88)=0.0120

[0045] This shows the case of intermediate temperature 200K. Power consumption is 2000W. Furthermore, as a result of the same analysis as explained in Fig. 4, when the intermediate temperature is 200K, the cooling efficiency at the low temperature end is found to be about 2.0 times that of a single regenerative refrigerator. Therefore, the cooling capacity Q2 is 20W. 4, when the refrigerant gas flow rate m is assumed, in the case of an intermediate temperature of 200 K, the heat Q3 extracted by the heat exchanger 200 is 28 W. If the cooling efficiency COP30 of the vapor compression chiller 30 during cooling from room temperature 300 K to the intermediate temperature 200 K is 0.65, the power consumption Q4 in the vapor compression chiller 30 is calculated to be 43 W. As a result, the overall COP is calculated as follows: Total COP=20 / (2000+43)=0.00979

[0046] In this way, it was confirmed that the total COP also changes when the intermediate temperature is changed. Within the scope of the analysis in the embodiment, it was confirmed that the total COP is highest when the intermediate temperature is set to 100K. It is known that the cooling efficiency (COP30) of a vapor compression refrigerator is extremely deteriorated when cooling to a temperature below 100K, so the intermediate temperature of 100K can be said to be the lower limit of the practical cooling temperature of a vapor compression refrigerator. However, this analysis was performed under several assumptions, and the intermediate temperature at which the overall COP is optimized may differ if the position of the heat exchanger 200, the heat exchange efficiency, etc. are different. However, if the analysis described in Figures 4 and 5 is performed according to the configuration of the regenerative refrigeration system, the intermediate temperature at which the overall COP is optimized can be set.

[0047] According to the embodiment of the regenerative refrigeration system described above, heat can be extracted from the regenerative refrigeration unit by a heat exchanger. As a result, it is possible to improve the overall cooling efficiency even when taking into account the power consumption of the vapor compression refrigeration unit used in combination.

[0048] It is not necessary to have all of the various features described in the above embodiments, and some of them may be omitted or combined as appropriate. Furthermore, the present invention is not limited to the embodiments, and various modifications can be made.

[0049] FIG. 6 is an explanatory diagram showing the overall configuration of a regenerative refrigeration system 10A as a modified example. Unlike the embodiment, in the modified example, the cold storage unit (low temperature side) 16A and the cold storage unit (high temperature side) 17A are separate units, and a connection part 20 is provided to connect the two. The connection part 20 simply serves as a flow path for the refrigerant gas and does not perform cold storage. A heat exchanger 200A is provided at this connection part. Other components are as described in the embodiment (FIG. 2). Also, the method of mounting the heat exchanger 200A to the connection part 20 can take various forms, such as the structure described in FIG. 3. According to this modification, the connection portion 200 can be easily formed in a shape and structure suitable for heat exchange, and the efficiency of heat exchange can be improved.

[0050] In addition, in any of the embodiments and modifications, the heat exchanger 200 may be cooled by a refrigerant such as liquid nitrogen instead of the vapor compression refrigerator. In this case, the power consumption of the vapor compression refrigerator is not required, and therefore the cooling efficiency can be further improved. The present invention can be modified in various other ways. [Industrial Applicability]

[0051] The present invention can be used to realize cryogenic cooling at temperatures lower than liquid nitrogen, and in particular, can be used to realize cryogenic cooling when the object to be cooled is a superconducting coil. [Explanation of symbols]

[0052] 10,10A Regenerative refrigerator 11 Buffer Tank 12 Orifice valve 13 Hot End 14 Pulse tube 15 Low temperature end 16, 16A regenerator (low temperature side) 17, 17A regenerator (high temperature side) 18 Hot End 19 Compressor 20 Connection 30 Vapor compression refrigerator 200, 200A heat exchanger 211a~211d Flow path layer 220 Heat exchanger 221 Inlet 222 Outlet

Claims

1. A regenerative refrigeration system, comprising: a regenerative refrigerator having a pressure drive source, a regenerator having a high-temperature end and a low-temperature end at both ends, and a phase adjuster; a heat exchanger provided between the high temperature end and the low temperature end and performing heat exchange at an intermediate temperature set between the temperatures at the high temperature end and the low temperature end; and a cooling mechanism for cooling the heat exchanger.

2. The regenerative refrigeration system according to claim 1, The cooling mechanism is a regenerative type refrigeration system that is a refrigerator of a different type from the regenerative type refrigerator.

3. The regenerative refrigeration system according to claim 2, When cooling efficiency is defined as cooling capacity / power consumption, the intermediate temperature is set so that the cooling efficiency based on the total value of the power consumption of the regenerative refrigerator and the refrigerator is higher than the cooling efficiency of the regenerative refrigerator alone.

4. The regenerative refrigeration system according to claim 2, A regenerative refrigeration system in which the intermediate temperature is set based on the lowest temperature that can be cooled by the refrigerator.

5. The regenerative refrigeration system according to claim 1, The regenerative refrigerator is a pulse tube refrigerator having a pulse tube connected to the low temperature end of the regenerator.

6. The regenerative refrigeration system according to claim 5, The regenerative refrigerator is a regenerative refrigeration system in which an end of the pulse tube opposite to the low temperature end is open to room temperature.

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