JPH0569563U - Cryogenic cooling device - Google Patents

Abstract

(57) [Abstract] [Purpose] Regarding a novel structure of a cooling device capable of cooling a device such as a superconducting magnet device which requires a temperature of several K to several tens of K to such an extremely low temperature, a load of a cooling load. An object of the present invention is to provide a highly reliable cryogenic cooling device capable of performing stable cooling by suppressing fluctuation of the cooling temperature to a minimum with a simple configuration despite the fluctuation. A cryogenic cooling device for cooling a cooling load with a cooling medium cooled by a cryogenic refrigerator, comprising a cooling circuit for circulating the cooling medium, the cooling circuit comprising:
A first for cooling the cooling medium by the cryogenic refrigerator
Heat exchanger, a second heat exchanger through which the cooling medium cooled by the first heat exchanger passes to cool the cooling load, and a cold storage provided after the second heat exchanger. And a vessel.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a cryogenic cooling device, and more particularly, to a novel structure of a cooling device capable of cooling an extremely low temperature device such as a superconducting magnet device requiring an extremely low temperature of several K to several tens K to such a cryogenic temperature. ..

[0002]

[Prior Art]

 FIG. 3 shows a conceptual diagram of a conventional cryogenic cooling device. This cryogenic cooling device cools a helium (He) gas as a cooling medium by a cryogenic refrigerator 10, and cools a cooling load such as a superconducting magnet device through a heat exchanger by the cooled He gas. It is a thing. The cryogenic cooling device in FIG. 3 does not directly cool the cooling load by the refrigerator 10, but indirectly cools the cooling load through the cooling circuit 20. This is an effective configuration for increasing the distance between the refrigerator 10 and the cooling load when the load receiving the cooling resists the vibration of the refrigerator 10.

The cryogenic refrigerator 10 shown in FIG. 3 includes a Gifford-McMahon (GM) cycle refrigerator, a solver refrigerator or a Stirling refrigerator, and the refrigerator cycle is sent from the refrigerant gas compressor 11. The high-pressure refrigerant gas is adiabatically expanded to absorb heat at the tip of the cold head 12, and the tip is cooled to an extremely low temperature. The cold head 12 and the cooling circuit 20 are housed inside the vacuum container 13.

Next, the operation and structure of the cooling circuit 20 will be further described. The refrigerant circulation pump 21 sends out He gas as a cooling medium into the cooling circuit. The He gas is cooled by the regenerative heat exchanger 22 (point b) and then enters the precooling heat exchanger 23.

The pre-cooling heat exchanger 23 is in contact with the cold head 12 of the cryogenic refrigerator 10, and the He gas of the cooling medium passing through the pre-cooling heat exchanger 23 is cooled to the cryogenic temperature (point c). The cooled He gas passes through the load heat exchanger 24 and cools the object to be cooled 24 which is a cooling load (point a).

The He gas that has passed through the load heat exchanger 24 enters the regenerative heat exchanger 22, receives heat, reaches room temperature, and then returns to the inlet of the circulation pump 21. The above cycle is repeated to keep cooling the cooling load 25.

FIG. 4 illustrates the detailed structures of the load heat exchanger 24 and the cooling load 25 when cooling the superconducting magnet device.

[0008]

[Problems to be solved by the device]

 When the cooling load 25, for example, the amount of heat generated by the superconducting magnet is constant, a constant cooling temperature can be maintained even if the amount of heat absorbed by the cooling in the load heat exchanger 24 is constant.

However, the load of the cooling load 25, that is, the amount of heat to be absorbed may fluctuate periodically as shown in FIG. 5, or may fluctuate in a pulsed manner as shown in FIG. For example, the current flowing through the superconducting magnet may be changed, or the current may be applied to the measurement target to generate heat.

When the temperature of the superconducting magnet rises due to heat generation, the He gas temperature of the cooling medium at point a rises, and the risen temperature is transmitted through the regenerative heat exchanger 22 and the temperature at point b rises. Then, the temperature of He gas at point c also rises. Therefore, the temperature of the cooling load 25 further rises.

However, while the cooling cycle in the cooling circuit 20 is repeated, the increased heat amount of the cooling load 25 is absorbed by the refrigerator 10 to reach an equilibrium state, and settles to a predetermined reference cooling temperature after a certain delay time. become. When the calorific value decreases, the temperature drops, but the same phenomenon occurs.

As described above, since the response time of the cooling cycle is slow, when the heat generation amount of the cooling load 25 increases or decreases, the cooling temperature of the cooling circuit 20 thereafter returns to the equilibrium state. It takes time, and the cooling temperature also fluctuates due to the fluctuation of the cooling load 25.

Therefore, in the conventional cryogenic cooling device, the cooling temperature greatly fluctuates according to the load fluctuation of the cooling load 25. When cooling superconducting magnets, it is necessary to prevent temperature rise as much as possible. In order to suppress this fluctuation range, the refrigerating capacity of the refrigerator 10 must be increased. Such an increase in the size of the cooling device has been a cause of increased costs.

An object of the present invention is to provide a highly reliable cryogenic cooling device capable of performing stable cooling while suppressing fluctuations in cooling temperature to a minimum with a simple configuration despite fluctuations in cooling load. Is.

[0015]

[Means for Solving the Problems]

 The cryogenic cooling device of the present invention is configured to cool the cooling load by the cooling medium cooled by the cryogenic refrigerator, and cools the cooling medium by the cryogenic refrigerator in the cooling circuit for circulating the cooling medium. A first heat exchanger, a second heat exchanger through which a cooling medium cooled by the first heat exchanger passes to cool a cooling load, and a regenerator provided after the second heat exchanger. Place and.

Furthermore, another cryogenic cooling device of the present invention is a cryogenic cooling device for directly cooling a cooling load by a cryogenic refrigerator, wherein the cold storage is provided around a portion of the refrigerator in contact with the cooling load. Arranged the vessels.

[0017]

[Action]

 A regenerator is provided during the cooling cycle, and the regenerator absorbs the increase in the amount of heat of the cooling medium and absorbs fluctuations in the cooling temperature.

In addition, a regenerator is provided around the portion of the refrigerator that is in contact with the cooling load to absorb an increase in the amount of heat of the cooling load and absorb fluctuations in the cooling temperature.

[0019]

【Example】

 FIG. 1 shows a conceptual diagram of a first embodiment of a cryogenic cooling device according to the present invention. In FIG. 1, the same reference numerals as those in FIG. 3 indicate the same or similar members.

The operation and structure of the cooling circuit 20 of FIG. 1 will be further described below. The refrigerant circulation pump 21 sends out He gas as a cooling medium into the cooling circuit. The He gas is cooled by the regenerative heat exchanger 22 (point b) and then enters the precooling heat exchanger 23. The pre-cooling heat exchanger 23 is in contact with the cold head 12 of the cryogenic refrigerator 10, and the He gas of the cooling medium passing through the pre-cooling heat exchanger 23 is cooled to the cryogenic temperature (point c).

The cooled He gas passes through the load heat exchanger 24 to cool the cooling load 25 (point a). The He gas that has passed through the load heat exchanger 24 passes through the regenerator 26. The regenerator 26 has a structure in which a cylindrical container is filled with a stack of a wire mesh made of a material having a large specific heat, such as copper, and He gas is configured to pass through the gap of the wire mesh. ing.

The He gas that has passed through the regenerator 26 enters the regenerative heat exchanger 22, receives heat, reaches room temperature, and returns to the inlet of the circulation pump 21. The above cycle is repeated to continue cooling the cooling load 25.

Although the temperature at point a immediately after the load heat exchanger 24 rises due to the increase in the amount of heat of the cooling load 25, the regenerator 26 having a large heat capacity absorbs the amount of heat and the inlet a of the regenerative heat exchanger 22. Suppress the temperature increase of He gas at the'point.

Therefore, since the temperature rise of the He gas passing through the regenerative heat exchanger 22 at the point b or the point c is suppressed, the reference cooling temperature of the cooling device is less likely to change. With such a structure, the cooling cycle is stable even with respect to load fluctuations (fluctuations in heat generation amount) as shown in FIG. 5 or FIG.

FIG. 2 shows a cryogenic cooling device according to another embodiment of the present invention. The method of using the regenerator is the same as that of the embodiment of FIG. 1, but in the embodiment of FIG. 2, the cooling load is directly cooled by the cold head of the refrigerator without passing through the cooling circuit.

The cryogenic refrigerator 10 shown in FIG. 2 is basically the same as that shown in FIG. 1 or 3. The different structure is that the regenerator 27 is thermally coupled and fixed around the portion of the tip of the cold head 12 where the cooling load 25 contacts.

Since the regenerator 27 does not need to pass He gas as a cooling medium unlike the embodiment of FIG. 1, it is not necessary to form a gas passage, and a block having a larger heat capacity, such as a copper block, is used. ..

By installing the regenerator 27, the heat capacity of the cold head 13 of the refrigerator 10 increases, and the load temperature is changed due to the load fluctuation (fluctuation of the heat generation amount) as shown in FIG. 5 or 6. Even if the temperature rises, the cooling temperature immediately returns to the original value, and the cooling temperature can be kept almost constant regardless of load fluctuation.

Although the case where the refrigerator having the one-stage configuration is used has been described above, the configuration of the refrigerator is not limited to the one-stage configuration. FIG. 7 shows a structural example of a cryogenic cooling device using a two-stage refrigerator.

In FIG. 7A, the cold heads 31 and 32 form a two-stage Gifford-McMahon refrigerator. The cooling circuit 20 is cooled by exchanging heat with the cold heads 31 and 32 by precooling heat exchangers 23a and 23b, respectively. The cooling medium cooled to the cryogenic temperature in the second-stage precooling heat exchanger 23b cools the cooling load 25 in the load heat exchanger 24 and passes through the regenerator 26. While the cooling capacity has a margin, the regenerator 26 accumulates cold. The cooling medium is then heat-exchanged with the cooling medium having a relatively high temperature in the regenerative heat exchangers 22b and 22a and sent to the cooling medium circulation pump (not shown).

FIG. 7B shows the configuration of another two-stage Gifford-McMahon refrigerator. In this configuration, the third regenerative heat exchanger 22c is arranged between the precooling heat exchanger 23b and the load heat exchanger 24.

As described above, when a multi-stage refrigerator is used, it is preferable to provide a regenerator after the load heat exchanger or in the final stage refrigerator itself in order to assist the capacity of the final stage refrigerator. ..

Although the present invention has been described with reference to the embodiments, the present invention is not limited to these. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

The material and shape of the configuration of the cooling circuit or the model of the refrigerator described in the embodiments described above are within the scope of the claims of this utility model, and various improvements and modifications are made so that the effects of the invention can be obtained. Changes may be made and all such improvements and changes are within the scope of the invention.

[0035]

[Effect of the device]

 In a cryogenic cooling device in which a refrigerator cools a cooling load via a cooling circuit, a regenerator is provided during the cooling cycle, and the regenerator absorbs an increase in the amount of heat of the cooling medium to suppress fluctuations in the cooling temperature. A stable and reliable cooling device is provided.

Further, in a cryogenic cooling device that directly cools a refrigeration load with a refrigerator, a regenerator is provided around a portion of the refrigerator that is in contact with the refrigeration load to absorb an increase in the amount of heat of the cooling load and cool the refrigeration temperature. The fluctuation of can be absorbed.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a cryogenic cooling device according to a first embodiment of the present invention.

FIG. 2 is a conceptual diagram of a cryogenic cooling device according to a second embodiment of the present invention.

FIG. 3 is a conceptual diagram of a cryogenic cooling device according to a conventional technique.

FIG. 4 is a diagram showing a structure of a specific example of a cooling load.

FIG. 5 is a diagram showing a periodic time variation of a cooling load amount.

FIG. 6 is a diagram showing a pulse-like temporal variation of a load amount of a cooling load.

FIG. 7 is a conceptual diagram of a cryogenic cooling device using a two-stage refrigerator.

[Explanation of symbols]

 10-Refrigerator 11-Compressor 12-Cold head 13-Vacuum container 20-Cooling circuit 21- ..Cooling medium circulation pump 22 ........ Regeneration heat exchanger 23 ........ Pre-cooling heat exchanger 24 ..... Load heat exchanger 25 ........ Cooling load 26, 27: Regenerator 30: Jules Thomson valve 31, 32: Cold head

Claims (5)

[Scope of utility model registration request] 1. A cryogenic cooling device for cooling a cooling load with a cooling medium cooled by a cryogenic refrigerator, comprising a cooling circuit for circulating the cooling medium, wherein the cooling circuit comprises the cryogenic refrigeration. Heat exchanger for cooling the cooling medium by a machine, a second heat exchanger for cooling the cooling load through which the cooling medium cooled by the first heat exchanger passes, and A cryogenic cooling device having a regenerator provided after the heat exchanger of No. 2. 2. The cryogenic cooling device according to claim 1, wherein the regenerator includes a container and a high specific heat material filled in the container. 3. A cryogenic cooling device for directly cooling a cooling load by means of a cryogenic refrigerator, the cryogenic cooling device having a regenerator arranged around a portion of the refrigerator in contact with the cooling load. 4. The cryogenic cooling device according to claim 3, wherein the regenerator comprises a block of a high specific heat material. 5. The cryogenic cooling device according to claim 1, wherein the cryogenic refrigerator is a final stage refrigerator of a cryogenic refrigerator having a plurality of stages.