JPH0481100B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a magnetic refrigerator with high efficiency and large refrigerating capacity.

[Technical background of the invention and its problems]

It is known that when a magnetic field is applied to a rare earth element such as Gd gadolinium or its compound, its temperature increases, and when the magnetic field is removed, the temperature returns to the original temperature. Conventionally, magnetic refrigerators have been developed by utilizing the temperature characteristics of such materials due to the magnetic field. For example, as shown in FIG. 1, this magnetic refrigerator includes the above-mentioned working material 2 placed in a magnetic field space intermittently formed by a pulse-driven superconducting magnet 1, and causing a refrigeration cycle in the working material 2. , this working substance 2
Helium in a liquid helium tank 4 communicated with a space provided through a heat pipe section 3 is frozen. The precooling refrigerator 5 is connected to a high-temperature waste heat section 9 of the space in which the working material 2 is provided via a valve mechanism consisting of a gas injection valve 6, a gas return valve 7, and a bypass valve 8. 2 is designed to recover the excess heat obtained.

In the magnetic refrigerator thus configured, when the superconducting magnet 1 is excited and a magnetic field is applied to the working material 2, the temperature of the working material 2 increases. At this time, the bypass valve 8 is closed, the gas injection valve 6 and the gas return valve 7 are opened to flow cooling gas from the pre-cooling refrigerator 5 to the high-temperature waste heat section 9 to recover excess heat from the working material 2. . Thereafter, the gas injection valve 6 and the gas return valve 7 are closed, the bypass valve 8 is opened, and then the excitation of the superconducting magnet 1 is stopped to eliminate the magnetic field. As a result, the temperature of the working material 2 decreases, and when the temperature becomes below the liquefaction point of helium, helium condenses on the surface of the working material 2. The helium liquefied by this condensation falls into the liquid helium tank 4 through the heat pipe section 3, and the helium gas in the liquid helium tank 4 is sent to the storage space for the working material 2. The above process is repeated to liquefy helium.

Magnetic refrigerators exhibit such a freezing effect and are highly effective in liquefying helium and the like.

However, as described above, the superconducting magnet 1, which is the power source of the refrigerator, is driven in pulses to intermittently apply a magnetic field to the work material 2, so there is a problem in that the loss is large. As a result, there was a problem in that not only the driving efficiency of the refrigerator was poor, but also the refrigerating capacity thereof was very poor.

[Purpose of the invention]

The present invention has been made in consideration of these circumstances, and its purpose is to provide a highly practical magnetic refrigerator with high drive efficiency and high refrigerating capacity.

[Summary of the invention]

In order to achieve the above object, the magnetic refrigerator according to the present invention has two magnetic field generators that constantly generate magnetic fields in a gas tank containing gas to be cooled and two spaces communicating with the upper part of the gas tank. The apparatus is movably provided along a path from each space to the upper part of the gas tank, and generates heat when it is located within a magnetic field, and absorbs heat when it is located at the upper part of the gas tank outside the magnetic field. Two working substances that liquefy the gas to be cooled in a gas tank, and one driving source provided outside the gas tank to apply power to move the two working substances into the space and the upper part of the gas tank. a drive means for exclusively reciprocating the gas, and a suction port and a discharge port are respectively located in each of the spaces, and after cooling a part of the cooled gas sucked through the suction port, the discharge port is cooled. and an exhaust heat recovery means for recovering exhaust heat of each work substance by spraying it onto the work substance located in the space.

〔Effect of the invention〕

Thus, according to the present invention, the working material moves back and forth between a space where a magnetic field is formed and a space where there is no magnetic field, creating a refrigeration cycle, so there is no need to drive the superconducting magnets etc. that form the magnetic field in pulses as in the conventional method. do not have. In other words, most of the power required to operate this refrigerator is for moving the two working materials back and forth, but it is possible to move the two working materials exclusively back and forth using one drive source. Therefore, when one working substance tries to move away from the magnetic field, the other working substance approaches the magnetic field,
The magnetic attraction generated between one working substance and the magnetic field can consequently be reduced by the magnetic attraction generated between the other working substance and the magnetic field. Therefore, the power required to reciprocate the two work materials can be sufficiently reduced, and as a result, the refrigeration efficiency can be improved. In particular, a suction port and a discharge port are located in each space to which a magnetic field is applied, and after cooling a part of the gas to be cooled sucked in through the suction port, the gas is cooled into the space through the discharge port. Since we are equipped with an exhaust heat recovery means that recovers the waste heat of each work material by spraying it on the work material located,
Each work substance can be directly precooled without contaminating the gas to be cooled in the gas tank, and the work substance can be efficiently precooled, which is a problem when a method of moving the work substance is adopted. Therefore, it is possible to improve not only the refrigeration efficiency but also the refrigeration capacity. Therefore, it is possible to provide a highly practical magnetic refrigerator that eliminates the drawbacks of the conventional technology and has high efficiency and large refrigerating capacity.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is a schematic diagram of the magnetic refrigerator according to the embodiment.

A liquid helium tank 12 containing helium, which is a medium to be cooled, is provided inside the vacuum insulation container 11 . However, in the vacuum insulation container 11,
Two cylinders 14 are provided through this and in communication with the liquid helium tank 12, and a piston 15 is provided within the cylinders 14 so as to be able to move up and down. The piston 15 is reciprocated within the cylinder 14 via a crank mechanism 17 by rotation of a motor 16. In addition, the two pistons 15 are interlocked with each other and are oriented in opposite directions,
In other words, it is configured to move exclusively back and forth. Thereby, the driving force of the piston 15 by the motor 16 can be suppressed to a minimum.

The tip of the piston 15 has a working material 1 which exhibits a magnetic refrigerating effect by receiving a magnetic field such as Gd.
8 is attached, and as the piston 15 reciprocates, the work material 18 is moved back and forth between a first space in which a constant magnetic field is formed and a second space in which there is no magnetic field. There is. The first space is a space in which a constant magnetic field is formed by a superconducting magnet 19 provided at the bottom dead center position of the piston 15,
The magnetic field space is magnetically separated from a second space, which is defined at the top dead center of the piston 15 and has no magnetic field, by a canceling magnetic field generated by the superconducting magnet 20. In other words, the superconducting magnet 20 generates a magnetic field for canceling the magnetic field in the second space, which is located at a short distance from the first space, to zero (0).
The influence of the magnetic field generated by the superconducting magnet 19 on the second space is removed. Such superconducting magnets 19 and 20 form a first space in which a constant magnetic field is formed in the reciprocating range of the piston 15 (working substance 18) and a second space in which there is no magnetic field, and there is a gap between these spaces. As the working material 18 reciprocates, the working material 18 produces a magnetic refrigeration cycle action.

The second space without a magnetic field is connected to the liquid helium tank 12 or is formed as an upper space of the liquid helium tank 12, and the second space is filled with helium gas, which is an object to be cooled. is being guided. Furthermore, a high-temperature heat exhaust section 21 is provided in the upper space of the liquid helium tank 12 at a position surrounding the first space. The high-temperature heat exhaust section 21 is provided with an inlet for sucking helium gas present in the first space and an outlet for blowing out helium gas toward the first space. The suction port is connected to the circulation pump 22 and the precooling refrigerator 23.
It communicates with the air outlet through the. That is, the helium gas existing in the first space is sucked in from the suction port using the power of the circulation pump 22, cooled by the pre-cooling refrigerator 23, and the cooled helium gas is delivered to the work material from the blowout port. I try to spray towards 18. The working material 18 is forcibly and effectively cooled by this cooling gas,
The exhaust heat is released from the circulation pump 22 to the outside via the precooling refrigerator 23. The packing 13 provided at the opening of the cylinder 14 seals the inside of the cylinder 14 with the outside which is at room temperature. Further, the superconducting magnets 19 and 20 are immersed in liquid helium and maintained in a superconducting state,
Generates a constant magnetic field in persistent current mode.

According to the magnetic refrigerator constructed in this manner, the working material 18 is placed in the first
It exhibits a magnetic refrigeration effect by reciprocating between the space of This heat is then exhausted in the first space by its magnetic refrigeration effect. Then, this heat is forcibly exchanged with the cooling gas blown onto the working material 18, and is transferred to the circulation pump 22 and the pre-cooling refrigerator 23.
It will be released to the outside through. As a result, the helium gas, which is the object to be cooled, in the liquid helium tank 12 is cooled below its liquefaction point, condenses, becomes liquid helium, and accumulates in the tank 12.

That is, the helium gas in the liquid helium tank 12 is guided to the second space, and heat is exchanged by the magnetic refrigerating action of the working material 18, which is powered by the movement of the piston 15. After the heat is transferred from the second space to the first space by the working material 18, the heat is forcibly and effectively exchanged by the blowing of the cooling gas, and the heat is exhausted to the outside. Therefore, helium, which is the object to be cooled, can be efficiently cooled with a small power source such as the reciprocating movement of the piston 15 by the motor 16. In other words, it can be said that the magnetic refrigerator with this configuration has high refrigerating efficiency and high refrigerating capacity.
Furthermore, as mentioned above, the superconducting magnets 19 and 20 only need to generate a fixed magnetic field, and unlike conventional magnets, there is no need for pulse driving, so the configuration of the drive source can be greatly simplified. can. Furthermore, by configuring the superconducting magnets 19 and 20 to operate in persistent current mode, it is possible to save driving energy. Further, according to the above-mentioned configuration, the moving force of the piston 15 by the motor 16 is required as a drive source, but as described above, the force for moving the piston 15 is
Using real pistons 15, these pistons 15
By configuring the pistons 15 to reciprocate in opposite directions, the forces of movement of the two pistons 15 in different directions can be canceled out to minimize the driving force required for the motor 16, thereby increasing its driving efficiency. be able to.

Note that the present invention is not limited to the embodiments described above. For example, the means for driving the movement of the two pistons 15 by the rotation of the motor 16 may be transmitted to the two pistons 15 in relation to each other via an appropriate ring mechanism, gear mechanism, etc. The mechanism can be modified in various ways. It goes without saying that the driving source is not limited to the motor 16. In short, the present invention can be implemented with various modifications without departing from the gist thereof.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of a conventional magnetic refrigerator;
The figure is a schematic configuration diagram of a magnetic refrigerator according to an embodiment of the present invention. 11... Vacuum insulation container, 12... Liquid helium tank, 13... Packing, 14... Cylinder, 1
5... Piston, 16... Motor, 17... Crank mechanism, 18... Working material, 19... Superconducting magnet, 21... High temperature exhaust heat section, 22... Circulation pump,
23... Refrigeration machine for pre-cooling.

Claims (1)

[Claims] 1. A gas tank containing a gas to be cooled, two magnetic field generators that constantly generate magnetic fields in two spaces connected to the upper part of the gas tank, and a path from each of the spaces to the upper part of the gas tank. two working substances that are movably disposed in the gas tank and generate heat when positioned within the magnetic field, and absorb heat when positioned above the gas tank outside the magnetic field to liquefy the gas to be cooled in the gas tank; a drive means that applies power from one drive source provided outside the gas tank to exclusively reciprocate the two working materials into the space and to the upper part of the gas tank, and within each of the spaces; a suction port and a discharge port are respectively located in the space, and after cooling a part of the gas to be cooled sucked in through the suction port, the gas is sprayed onto the work material located in the space through the discharge port. A magnetic refrigerator characterized in that it is equipped with an exhaust heat recovery means for recovering exhaust heat of each working material.