Cryogenic cooling device and cryogenic cooling method

Abstract

To provide a cryogenic cooling technique that improves cooling capacity by enhancing suppression of heat exchange loss.SOLUTION: A cryogenic cooling device 10A (10) comprises: an ejector 20 into which a first refrigerant m1 under flow pressure is injected from an injection part 21, and for sucking a second refrigerant m2 from a suction part 22 provided separately from the injection part 21, and outputting a third refrigerant m3 made by mixing the first refrigerant m1 and the second refrigerant m2, from a discharge part 25 provided in the same direction as that of the injection part 21; a second circuit 12 for making the third refrigerant m3 flow from the discharge part 25, in which a cooling source 15a (15) and a cooled body 16 are arranged in series, and connected to the suction part 22; and a first circuit 11 branching from the second circuit 12 downstream of the cooled body 16, and connected to the injection part 21.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to cryogenic cooling technology using a gas circulation cooling method.

Background Art

[0002] For cryogenic cooling methods of superconducting magnets, there are a conduction cooling method using a heat transfer plate for heat transfer between a cooling source and an object to be cooled, and a gas circulation cooling method in which a gas cooled by a cooling source is circulated. Among these, in the gas circulation cooling method, the temperature difference between the cooling source and the object to be cooled can be reduced. Therefore, when separating a refrigerator to avoid the magnetic field generated by a superconducting coil as the object to be cooled, or when cooling a plurality of objects to be cooled with a single cooling source, etc., under conditions where the heat transfer distance between the refrigerator and the object to be cooled is long, the gas circulation cooling method is advantageous.

[0003] In the gas circulation cooling method, it has components including a pump provided outside a heat insulation container (room temperature environment) that applies a flow pressure to a refrigerant gas, a piping circuit that circulates the refrigerant gas inside the heat insulation container, a cooling source (such as a GM refrigerator) and an object to be cooled (such as a superconducting magnet) arranged in series in this piping circuit. Furthermore, in the gas circulation cooling method, there is a prior art that discloses reducing heat exchange loss by providing an ejector in the piping circuit, reducing the flow rate of the refrigerant gas delivered to the pump in the room temperature environment, and increasing the ratio of the refrigerant gas that circulates only inside the heat insulation container.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The ejector has an injection part, a suction part provided separately from this injection part, and a discharge part provided in the same direction as the injection part. Then, high-pressure gas is injected into the injection part, the gas is sucked from the suction part using its kinetic energy, and a mixed gas of the injected gas and the sucked gas is discharged from the discharge part.

[0006] In the prior art, the mixed gas discharged from the discharge part is branched after passing through a cooling source and a cooled object. One is directly injected into the injection part, and the other is given a flow pressure by a pump and then sucked from the suction part. In this prior art, as conditions become severe, such as when cooling a plurality of cooled objects with a single cooling source or when the heat transfer distance between the refrigerator and the cooled object is long, there is a problem that the heat exchange loss increases and the cooling capacity becomes insufficient.

[0007] The embodiment of the present invention has been made in consideration of such circumstances, and an object thereof is to provide an ultra-low temperature cooling technology that enhances the suppression of heat exchange loss and improves the cooling capacity.

Means for Solving the Problems

[0008] In the ultra-low temperature cooling device according to the embodiment, an ejector that injects a first refrigerant with a flow pressure from an injection part, sucks a second refrigerant from a suction part provided separately from the injection part, and outputs a third refrigerant in which the first refrigerant and the second refrigerant are mixed from a discharge part provided in the same direction as the injection part; a second circuit that flows the third refrigerant from the discharge part and in which a cooling source and a cooled object are arranged in series and connected to the suction part; and a first circuit that branches from the second circuit downstream of the cooled object and is connected to the injection part.

Effects of the Invention

[0009] According to the embodiment of the present invention, an ultra-low temperature cooling technology that enhances the suppression of heat exchange loss and improves the cooling capacity is provided.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

[0011] (First embodiment) Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 shows a circulating refrigerant m (m 1 ,m 2 ,m 3 (=m 1 +m 2 6 is a vertical cross-sectional view of the ejector 20 applied to each embodiment.

[0012] In this way, the cryogenic cooling device 10A (10) is supplied with the first refrigerant m under flow pressure from the inlet 21. 1 By injecting the second refrigerant m from the suction part 22 provided separately from the injection part 21 (in the drawing, the direction is perpendicular to the injection part 21), 2 The first refrigerant m 1 and the second refrigerant m 2 The third refrigerant m 3 The ejector 20 outputs the third refrigerant m from the discharge portion 25 provided in the same direction as the injection portion 21. 3 The cooling system includes a second circuit 12 that allows the cooling water to flow and has a cooling source 15a (15) and a body to be cooled 16 arranged in series and connected to an intake section 22, and a first circuit 11 that branches off from the second circuit 12 downstream of the body to be cooled 16 and connects to an injection section 21.

[0013] Furthermore, the cryogenic cooling device 10A includes a heat insulation container 17 that houses an ejector 20, a cooling source 15a, a body to be cooled 16, and a second circuit 12 therein, and a first refrigerant m 1 that is disposed in the first circuit 11 outside the heat insulation container 17 and gives a flow pressure to the first refrigerant m 1 and a heat exchanger 19 that exchanges heat with the first refrigerant m

[0014] The circulating refrigerant m (the first refrigerant m 1 , the second refrigerant m 2 , the third refrigerant m 3 ) is a low-boiling-point substance such as helium gas that maintains a gaseous state even at extremely low temperatures. The ejector 20 injects the first refrigerant m 1 given a flow pressure by the pump 18 from the injection part 21. By passing through the nozzle of the injection part 21, the first refrigerant m 1 is decompressed and accelerated, and uses the increased kinetic energy to suck in the second refrigerant m 2 from the suction part 22. In this way, the third refrigerant m 1 in which the first refrigerant m 2 and the second refrigerant m 3 are mixed is pressurized and decelerated by a diffuser that is the discharge part 25 and discharged.

[0015] In this way, the ejector 20 sucks in the second refrigerant m 1 from the suction part 22 on the low-pressure side due to the action of the first refrigerant m 2 injected from the injection part 21 on the high-pressure side. Furthermore, the ejector 20 has a pump function of pressurizing the second refrigerant m 2 and discharging it from the discharge part 25 facing the same direction as the injection part 21.

[0016] Here, the pressure of the second refrigerant m 2 sucked into the suction part 22 of the ejector 20 after the body to be cooled 16 is cooled can be set to be equal to or higher than the critical pressure of the circulating refrigerant m. This setting is determined by the design specifications of the first circuit 11, the second circuit 12, the pump 18, the heat exchanger 19, and the ejector 20 in addition to the flow pressure by the pump 18.

[0017] By being set in this way, the circulating refrigerant m passing through the first circuit 11, the second circuit 12, the pump 18, the heat exchanger 19, and the ejector 20 will not become a liquid / gas two-layer flow. As a result, the circulating refrigerant m will not condense from a gas and liquefy, the suppression of heat exchange loss is strengthened, and the cooling capacity of the object to be cooled 16 can be improved.

[0018] The cooling source 15a (15) includes a GM refrigerator (Gifford-McMahon refrigerator) that expands the working gas inside the cooling cylinder and generates cold at the cold head at its tip. In addition, a Solvay refrigerator, a pulse tube refrigerator, etc. can be mentioned, but it is not limited to these. The third refrigerant m output from the discharge part 25 of the ejector 20 3 is imparted cold from the cooling source 15 when passing through the second circuit 12.

[0019] The object to be cooled 16 is exemplified as a superconducting coil, but is not particularly limited. This object to be cooled 16 receives the supply of cold from the third refrigerant m that has passed through the cooling source 15a via the second circuit 12. And the third refrigerant m that has supplied cold to the object to be cooled 16 3 partially enters the suction part 22 of the ejector 20 as the second refrigerant m 3 from the second circuit 12. Further, another part of the third refrigerant m 2 flows through the first refrigerant m flowing through the first circuit 11 branched from the second circuit 12 3 and is input to the injection part 21 of the ejector 20 after a flow pressure is applied. 1

[0020] The heat insulation container 17 partitions the inner low-temperature region from the outer normal-temperature environment, and maintains the low-temperature region at an extremely low temperature of about 4K to 10K, for example, by a vacuum heat insulation function. The first circuit 11, the second circuit 12, the cooling source 15, the object to be cooled 16, and the ejector 20 are accommodated in the low-temperature region inside the heat insulation container 17.

[0021] One end of the first circuit 11 is branched and connected to the second circuit 12 downstream of the object to be cooled 16, and the other end is connected to the injection part 21 of the ejector 20. And in the first circuit 11, outside the heat insulation container 17, the first refrigerant m 1 is provided with a pump 18 that applies a flow pressure. Therefore, by passing through the pump 18 in the normal temperature environment, the first refrigerant m 1 will be heated.

[0022] Therefore, inside the heat insulation container 17, a heat exchanger 19 is arranged in the first circuit 11 located at both ends of the pump 18. Due to the action of this heat exchanger 19, the first refrigerant m 1 output from the pump 18 exchanges heat with the first refrigerant m 1 before entering the pump 18, is cooled and input into the suction part 22 of the ejector 20.

[0023] Also, the first refrigerant m 1 injected from the injection part 21 of the ejector 20 can have its flow rate throttled to increase the flow pressure. Therefore, for the first refrigerant m 1 circulating in the first circuit 11, the circulation amount of the second refrigerant m 2 in the second circuit 12 can be improved. As a result, the flow rate of the first refrigerant m 1 passing through the normal temperature environment is reduced, the suppression of heat exchange loss associated with heat intrusion from the outside to the inside of the heat insulation container 17 is strengthened, and the cooling capacity for the object to be cooled 16 increases.

[0024] Furthermore, the setting of the pump 18 that applies a flow pressure to the first refrigerant m 2 can be adjusted so that the pressure of the second refrigerant m 1 sucked into the suction part 22 is equal to or higher than the critical pressure of the circulating refrigerant m. Therefore, it can operate stably at a pressure equal to or higher than the critical pressure, prevent liquefaction without condensing the third refrigerant m 3 and realize an efficient circulation, thereby improving the cooling capacity.

[0025] (Second Embodiment) FIG. 2 is a circuit diagram of a cryogenic cooling device 10B(10) showing the second embodiment. The cryogenic cooling device 10B of the second embodiment is composed of a cooling source 15b(15) containing a liquid medium instead of the refrigeration source 15a that utilizes the cold generated by expansion in the cryogenic cooling device 10A of the first embodiment described above. In FIG. 2, parts having the same configuration or function as those in FIG. 1 are denoted by the same reference numerals, and redundant explanations are omitted.

[0026] According to the cryogenic cooling device 10B of the second embodiment, heat intrusion from the outside to the inside of the heat insulation container 17 is suppressed, and as a result of the increase in the circulation amount of the second refrigerant m in the second circuit 12, the cooling source 15b of the liquid medium with a reduced evaporation amount can increase the cooling capacity of the object to be cooled 16. 2

[0027] (Third Embodiment) FIG. 3 is a circuit diagram of a cryogenic cooling device 10C(10) showing the third embodiment. The cryogenic cooling device 10C of the third embodiment has a configuration in which the pump 18 provided outside the heat insulation container 17 in the cryogenic cooling device 10A of the first embodiment described above is arranged in the first circuit 11 inside the heat insulation container 17 to apply a flow pressure to the first refrigerant m. In FIG. 3, parts having the same configuration or function as those in FIG. 1 are denoted by the same reference numerals, and redundant explanations are omitted. 1

[0028] According to the cryogenic cooling device 10C of the third embodiment, heat intrusion from the outside to the inside of the heat insulation container 17 is further suppressed, and as a result of the increase in the circulation amount of the second refrigerant m in the second circuit 12, the suppression of heat exchange loss is strengthened and the cooling capacity of the object to be cooled 16 increases. 2

[0029] (Fourth Embodiment) FIG. 4 is a circuit diagram of a cryogenic cooling device 10D(10) showing the fourth embodiment. In the cryogenic cooling device 10D of the fourth embodiment, a plurality of objects to be cooled 16(16a, 16b) are connected in parallel. In FIG. 4, parts having the same configuration or function as those in FIG. 1 are denoted by the same reference numerals, and redundant explanations are omitted.

[0030] In this cryogenic cooling device 10D, the heat-insulating container 17 is composed of a main chamber that houses the ejector 20 and the cooling source 15, and sub-chambers 17a and 17b that are separated from the main chamber and individually house the objects to be cooled 16 (16a, 16b). The main chamber of the heat-insulating container 17 and the sub-chambers 17a and 17b are connected by a heat-insulating connecting pipe 27. A second circuit 12 connected in parallel penetrates each of the connecting pipes 27.

[0031] According to this cryogenic cooling device 10D, heat intrusion from the outside to the inside of the heat-insulating container 17 is further suppressed, and as a result of an increase in the circulation amount of the second refrigerant m in the second circuit 12, the objects to be cooled 16 (16a, 16b) can be installed away from the cooling source 15 without increasing the volume of the heat-insulating container 17. Furthermore, since one pump 18 and the cooling source 15 are connected to a plurality of objects to be cooled 16 (16a, 16b), suppression of heat exchange loss is strengthened and improvement of the cooling capacity is realized. 2 As a result of an increase in the circulation amount of the second refrigerant m in the second circuit 12, the objects to be cooled 16 (16a, 16b) can be installed away from the cooling source 15 without increasing the volume of the heat-insulating container 17. Furthermore, since one pump 18 and the cooling source 15 are connected to a plurality of objects to be cooled 16 (16a, 16b), suppression of heat exchange loss is strengthened and improvement of the cooling capacity is realized.

[0032] (Fifth Embodiment) FIG. 5 is a circuit diagram of the circulating refrigerant in the cryogenic cooling device 10E (10) showing the fifth embodiment. The cryogenic cooling device 10E of the fifth embodiment includes a detector 29 (29a, 29b) that detects the temperature of the object to be cooled 16, and an adjustment valve 28 (28a, 28b) that adjusts the amount of refrigerant passing through each of the plurality of objects to be cooled 16 (16a, 16b) based on the detected temperature, with respect to the configuration of the cryogenic cooling device 10D of the fourth embodiment. In FIG. 5, parts having the same configuration or function as those in FIG. 4 are denoted by the same reference numerals, and redundant explanations are omitted.

[0033] Thus, according to the cryogenic cooling device 10E, the opening degree of the adjustment valve 28 (28a, 28b) is adjusted according to fluctuations in the heat loads of the plurality of objects to be cooled 16 (16a, 16b), and the refrigerant n (n 1 , n 2) The flow rate can be changed. As a result, the temperature difference between these multiple objects to be cooled 16 (16a, 16b) can be reduced. Then, it is possible to prevent the temperature of a specific object to be cooled 16 from selectively increasing, uniformly lower the temperatures of all the objects to be cooled 16, and ensure the soundness of the objects to be cooled 16.

[0034] According to the cryogenic cooling device of at least one of the embodiments described above, the refrigerant that has passed through the cooling source and the object to be cooled is branched, a flow pressure is applied to one refrigerant and it is injected from the injection part of the ejector, and the other refrigerant is sucked from the suction part of the ejector, so that the suppression of heat exchange loss is strengthened and the cooling capacity can be improved.

[0035] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, changes, and combinations can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalent scope thereof.

Description of Reference Numerals

[0036] 10 (10A, 10B, 10C, 10D, 10E) … Cryogenic cooling device, 11 … First circuit, 12 … Second circuit, 15 (15a, 15b) … Cooling source, 16 … Object to be cooled, 17 … Heat insulation container, 17a … Sub chamber, 18 … Pump, 19 … Heat exchanger, 20 … Ejector, 21 … Injection part, 22 … Suction part, 25 … Discharge part, 27 … Connecting pipe, 28 … Control valve, 29 … Detector.

Claims

1. An ejector that injects a first refrigerant under a flow pressure from an injection section, sucks a second refrigerant from a suction section provided separately from the injection section, and outputs a third refrigerant in which the first refrigerant and the second refrigerant are mixed from a discharge section provided in the same direction as the injection section, a second circuit that allows the third refrigerant to flow from the discharge section and in which a cooling source and a body to be cooled are arranged in series and connected to the suction section, a cryogenic cooling device comprising a first circuit that branches from the second circuit downstream of the body to be cooled and is connected to the injection section.

2. In the cryogenic cooling device according to Claim 1, a heat-insulating container that houses the ejector, the cooling source, the body to be cooled, and the second circuit therein, a pump that is arranged in the first circuit outside the heat-insulating container and applies the flow pressure to the first refrigerant, a cryogenic cooling device comprising a heat exchanger that exchanges heat with the first refrigerant in the first circuit located at both ends of the pump inside the heat-insulating container.

3. In the cryogenic cooling device according to Claim 1, a heat-insulating container that houses the ejector, the cooling source, the body to be cooled, and the second circuit therein, a cryogenic cooling device comprising a pump that is arranged in the first circuit inside the heat-insulating container and applies a flow pressure to the first refrigerant.

4. In the cryogenic cooling device according to Claim 2 or Claim 3, a cryogenic cooling device in which the flow pressure is set so that the pressure of the second refrigerant sucked into the suction section is equal to or higher than its critical pressure.

5. In the cryogenic cooling device according to Claim 2 or Claim 3, a cryogenic cooling device in which the cooling source is a mechanism or a liquid medium that expands a working gas to generate cold.

6. In the cryogenic cooling device according to Claim 2 or Claim 3, a cryogenic cooling device in which a plurality of the bodies to be cooled are connected in parallel.

7. In the cryogenic cooling device according to Claim 6, a detector that detects the temperature of the body to be cooled, a cryogenic cooling device comprising an adjustment valve that adjusts the amount of refrigerant passing through each of the plurality of bodies to be cooled based on the detected temperature.

8. A step in which an ejector injects a first refrigerant under a flow pressure from an injection section, sucks a second refrigerant from a suction section provided separately from the injection section, and outputs a third refrigerant in which the first refrigerant and the second refrigerant are mixed from a discharge section provided in the same direction as the injection section, In a second circuit in which a cooling source and a body to be cooled are arranged in series, a step of flowing the third refrigerant from the discharge portion and sucking the second refrigerant into the suction portion; A cryogenic cooling method including a step of injecting the first refrigerant into the injection portion in a first circuit branched from the second circuit downstream of the body to be cooled.

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