WO2005116537A1

WO2005116537A1 - A method for realizing magnetization and demagnetization of the magnetic refrigerating working substance, utilizing dynamic magnetic circuit

Info

Publication number: WO2005116537A1
Application number: PCT/CN2004/000554
Authority: WO
Inventors: Dingwei Lu
Original assignee: Nanjing University
Priority date: 2004-05-28
Filing date: 2004-05-28
Publication date: 2005-12-08

Abstract

A method is used for realizing magnetization and demagnetization of the magnetic refrigerating working substance in room-temperature magnetic refrigeration system, which utilizes dynamic magnetic circuit. The magnitude of the magnetic field in the working space of the magnetic refrigerating working substance is controlled by said dynamic magnetic circuit through varying the magnetic field direction of permanent magnet block. The magnetic refrigerating working substance is quiescent relative to the magnet. A closed magnetic circuit is constituted by multiple small magnet units which make up a closed loop. Each small magnet unit is successively mounted in terms of a definite angle after charging magnetism. A central cavity is the convergence space of the magnetic field. At least four small magnets are rotated under activation of the external force in the closed magnetic circuit. The magnetic field in the working space of the magnetic refrigerating working substance is changed periodically from intense magnetic field to weak magnetic field or no magnetic field during the variation of the magnetic field direction. The present invention can decrease the motion amplitude of the motion components, and then decrease the volume of the system. The heat exchange efficiency of the secondary refrigerant .and the cold accumulator is improved since the magnetic refrigranting working substance is provided in the central cavity.

Description

Method for realizing magnetization and demagnetization of magnetic refrigerant using dynamic magnetic circuit

Technical field

The present invention relates to a type of refrigeration method, and particularly to a method for implementing magnetization and demagnetization of a magnetic refrigerant using a dynamic magnetic circuit in room temperature magnetic refrigeration. It can also be used in other applications where a changing magnetic field is used.

Background technique

The development of modern society and the improvement of the quality of life require a comfortable environment. The refrigeration technology, which is the blood of modern science, has gradually developed and matured in the past 200 years. It has brought comfort and enjoyment to human life, and also provided science and technology. Research and use platforms. Because one third of human energy is consumed in refrigeration, the state of refrigeration technology is extremely important to human survival. Refrigeration technology mainly includes liquid vaporization refrigeration, gas expansion refrigeration, adsorption refrigeration, thermoelectric refrigeration, vortex tube refrigeration, thermoacoustic refrigeration, pulse tube refrigeration, and magnetic refrigeration, etc., but the most popular is liquid vapor refrigeration. Liquid vapor refrigeration requires the use of Freon. It not only destroys the ozone environment over the atmosphere, but also has a greenhouse effect. Therefore, refrigeration directly affects the use of energy and the quality of the environment. It is very urgent and significant to research and develop new energy-saving and environmental-friendly refrigeration methods. major.

As a refrigeration method, magnetic refrigeration was scientifically confirmed in 1926. It theoretically has the highest cycle efficiency and has no compressor, so it has become the dream refrigeration method of physicists. However, subsequent research was only successful in the extremely low temperature field (near absolute zero), and helium magnetic refrigeration liquefaction equipment has been produced. At room temperature, the magnetic refrigeration part experienced long-term stagnation after experiencing too many failures, and there was no progress. Different from magnetic refrigeration at low temperature, room temperature magnetic refrigeration has special requirements on the circulation mode, magnetic refrigeration working medium and magnetic field, so it is very difficult to achieve.

In 1976, NASA's Brown first used a sampan plate mixed with water-containing alcohol as a coolant to first achieve a temperature difference of 38 degrees in a superconducting magnetic field environment, showing the possibility of room-temperature magnetic refrigeration to humans.

^1982, and U.S. Barc lay Clayar t the proposed active magnetic regenerator (AMR) is a new concept, is made practical theoretical preparation room temperature magnetic refrigeration.

In 1990, the U.S. Department of Energy funded NASA and the University of Iowa's Ames Lab to carry out AMR-based room temperature magnetic refrigeration prototype research. In the research of room temperature magnetic refrigeration materials, in 1997 they found that the gadolinium-silicon-germanium alloy has a so-called giant magnetocaloric effect, which found a place for active magnetic regenerators. In the research of room temperature magnetic refrigerator, after nearly 8 years of hard exploration, in 1997, the first reciprocating room temperature magnetic refrigerator capable of long-term efficient operation was announced. The refrigerating medium used is a metal ball with a diameter of 0. ΙιηηΓθ. 3 awakening, a weight of 3 kg, a superconducting magnetic field of 1.5-5 Tesla, a cycle period of 6 seconds, and it ran. 1500 hours. When working under a 5 Tesla magnetic field, the thermodynamic perfection reaches 60%, and when working under a 1.5 Tesla magnetic field, it is about 20%. This work heralded the advent of the practical era of room temperature magnetic refrigeration technology.

Replacement page (Article 26) Room temperature magnetic refrigeration is an inevitable development of refrigeration, and it will certainly replace the current refrigeration method in the near future. All the air conditioners, refrigerators and other refrigerators associated with traditional cooling methods will complete a revolutionary change. However, to reach the market, room temperature magnetic refrigeration first needs to solve the problem of efficiency, reliability and economy. With the gradual maturity of room temperature magnetic refrigeration technology, the refrigeration industry around the world will completely change the existing product structure, and its market is immeasurable. Since 1997, practical research on room temperature magnetic refrigeration has begun. The initial success was achieved using a reciprocating approach. The method is to let the magnetic working medium enter the working space with a magnetic field by mechanical movement. At this time, the working medium is magnetized and has a heating effect. After the heat generated by the magnetocaloric effect is taken away by the cooling fluid, the magnetic working fluid is mechanically removed from the magnetic field region, so that the magnetic working fluid is cooled by the magnetocaloric effect. Because this working process is discontinuous, if the circulation speed of room temperature magnetic refrigerators is to be increased to increase the cooling capacity-while the cooling capacity of magnetic cooling is usually too small to have great application value, the reciprocating type is limited. Later, the research of room temperature magnetic refrigeration in the United States began to study the rotation mode. The magnetic structure of the magnet was changed from a hollow cylindrical shape to a shape where the letter C rotates around an axis outside the letter. It is because the magnetic working medium needs to use a driving robot arm to enter and leave the magnetic field space. This method reduces the magnetic field of the original 0-type magnet. In addition, the heat exchange is insufficient when the magnetic working medium is inside and outside the magnetic field.

Summary of the invention

The present invention is to provide a method for realizing the magnetization and demagnetization of a magnetic refrigerant using a dynamic magnetic circuit in room temperature magnetic refrigeration, which is capable of removing the band caused by the relative movement of the magnetic refrigerant and the magnet. This is an effective method for difficult heat exchange fluid switching, while retaining the high refrigeration efficiency of magnetic refrigeration. With this method of magnetizing and demagnetizing the magnetic working medium, the magnetic field strength of room temperature magnetic refrigeration can be increased, the heat exchange effect can be improved, it is more suitable for practical use, and the cooling capacity of room temperature magnetic refrigeration can be increased. Wide operating temperature range: 20Γ330K.

The purpose of the present invention is achieved as follows: A method for realizing magnetization and demagnetization of a magnetic refrigeration working medium by using a dynamic magnetic circuit in room temperature magnetic refrigeration, which is characterized by using a dynamic magnetic circuit method to perform magnetic refrigeration working medium. The method of magnetizing and demagnetizing the dynamic magnetic circuit is to control the size of the magnetic field of the magnetic refrigerant in the working space in the middle of the magnetic block by controlling the direction of the magnetic field of the permanent magnet block in the magnetic circuit. The magnetic refrigerant is relative to the magnet. It is stationary without relative motion.

The method of the present invention performs dynamic magnetic circuit control on a closed magnetic circuit composed of a permanent magnet. The magnetic circuit forms a closed loop with a plurality of small magnet units. Each small magnet unit is magnetized and installed at a certain angle in turn. The central cavity of the block is the converging space of the magnetic field. At least four small magnets on the closed magnetic circuit rotate under the drive of external force. During the process of changing the magnetic field orientation, the magnetic field in the working space where the magnetic refrigerant is located will change from a strong magnetic field to Weak or no magnetic field changes periodically.

The method of the present invention further includes: closing the magnetic path to form a closed loop with a plurality of small magnet units, each of the small magnet units being magnetized and installed at a certain angle in turn, and at least four rotating small magnets on the closed magnetic circuit. Is a cylindrical unit, and the shape of one end of the magnet adjacent to the cylinder on the closed magnetic circuit is a concave shape embedded in the cylinder. The center of the entire magnet is equipped with a magnetic refrigeration working material.

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Replacement page (Article 26) The structure of the entire magnetic circuit can be square, rectangular or circular. In short, a pair of rotatable magnets can be provided on the magnetic circuit in the square, rectangle or circle to control the change of the magnetic field in the working space in the cavity.

After the entire closed magnetic circuit magnetic block is installed, an armature should be added for magnetic shielding. If a better shielding effect is required, the armature can be made in multiple layers, and a non-magnetic medium, such as plastic or graphite, is inserted between each layer of the armature.

In order to reduce the external driving torque or input power, in practice, the above-mentioned closed magnetic circuit magnets are connected in series with each other in the axial direction, and the adjacent magnetic blocks thereof have opposite orientations; they are combined with each other to form an even number.

The simplest and typical dynamic magnetic circuit is a square closed magnetic circuit. There are four cylindrical side magnet units on the four sides of the magnet, and cylindrical corner rotating magnet units can also be on the four corners.

All magnet units preferably require a high coercive force, which allows the permanent magnets to maintain the original magnetic field strength during repeated magnetization processes.

The features of the invention are:

1. It can reduce the movement amplitude of the moving parts, thereby reducing the volume;

2. The magnetic refrigerant working medium is placed in the central cavity and is in a static state. The inlet and outlet of the refrigerant can be made together to reduce the dead volume of the refrigerant flow and improve the heat exchange efficiency between the refrigerant and the cold accumulator.

3. Reduced the use of a large number of pipes in the rotary magnetic refrigerator;

4. The number of switching valves for the flow of the refrigerant has also been reduced. Such valves not only occupy a large volume, but also are difficult to manufacture and costly.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic diagram of the structure of a square closed magnetic circuit magnet of the present invention, and the center is a room temperature magnetic refrigerant. Fig. 2 is a schematic diagram of the structure of a round closed magnetic circuit magnet of the present invention.

Fig. 3 is a schematic diagram of the magnetic field line distribution of the closed magnetic circuit of the present invention. Fig. 3 also shows that each small magnet constituting the ring has a different magnetization direction. Figure 3 shows a quadrant (1/4) small magnet distribution and magnetizing direction distribution. The remaining 3/4 are symmetrically distributed and form a closed magnetic circuit.

In the picture, the small permanent magnet 1, the rotatable permanent magnet 2, and the central cavity 3. The arrows in the figure indicate the gram orientation of the magnet. detailed description

Figure 1 The structure of a square closed magnetic circuit magnet is a schematic diagram, which is not an ideal working magnetic circuit. The ideal working magnetic circuit should have the closed magnetic circuit magnetic field lines as shown in FIG. 3, so that the central cavity has the strongest magnetic field, as shown in FIG. As shown in Fig. 2, each of the small magnets forming the ring has a different magnetization direction, so as to form the magnetic field distribution diagram of Fig. 3.

Selected materials: NdFeB material, samarium cobalt alloy or other high performance permanent magnet materials.

Working process and structure: Use the above permanent magnet material to form a magnetic circuit according to the following methods and steps:

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Replacement page (Article 26) 1. As shown in Figure 1, eight small magnet units (arrows are drawn and magnetized in the direction of magnetization) are respectively magnetized and installed in accordance with a certain illustrated angle in order. _{5 The} magnetic lines of force form a closed loop. There are eight small magnets in total. The central cavity is the converging space of the magnetic field. The magnetization directions of the four cylindrical magnetic blocks on the square edge next to the cavity are the same in a symmetrical position. The square in the figure is only a schematic. It should be a cylinder placed in the cavity as shown in Figure 2 and can be rotated. The diameter of each cylinder is similar to the size of the outer edge of the cavity. The specific size is required to make the magnetic field in the cavity change the maximum when the four cylinders rotate and change direction. Such a magnet may be changed to a hollow cylinder or a hollow cube according to the application.

2. The magnetization size of the four cylinders is the same, but can be different from other parts, but the cavity is required to have the largest magnetic field change when the cylindrical magnet unit rotates.

3. If cylindrical rotating magnet units are also used at the four corners, the combined action of the four corner magnet units and the side magnet rotating units will not only change the magnitude of the magnetic field, but also achieve the reversal of the magnetic field.

4. The two sets of magnets with the same field strength are stacked up and down in a manner that the magnetic field is reversed. The magnetization directions of the two adjacent magnets are opposite. If the rotating shafts at the same position are connected, the attraction when rotating the magnets? ] Forces and repulsive forces can cancel each other out.

As shown in Figure 3, each small magnet unit is installed at a certain angle after being magnetized, so that the magnetic lines of force form a closed loop. Such magnets must appear in pairs on symmetrical lines, so that the power required when rotating Smaller. Figure 3 shows three pairs of rotatable magnets, and four pairs of rotatable magnets can also be provided.

Selection of permanent magnet materials: high coercive force NdFeB (for example, He 2Tes la), armature, etc. Mode: square hollow, surrounded by eight cubes of equal volume, the typical size of each magnetic block is 3 cm * 3cm * 5 cm, more specific design is as follows:

1. Figure 1 is a sectional view after molding. The figure shows the shape of the magnetic block and the magnetic field direction of each magnetic block.

The eight magnetic blocks need to be processed before being magnetized and assembled. The four blocks on the side are cylindrical, and there is a concave half garden that fits with this.

2. Cut the four cubic magnets adjacent to the middle phase into a cylindrical shape and take it out for processing, while retaining the rest of the surrounding area.

3. Connect the remaining part to the surrounding four cubes (located on the corners) with glue.

4. Coat the inner wall of the rotatable magnet, that is, the cylindrical cavity, with molybdenum disulfide (made with butter). 5. Make holes in the two ends of the four cylinders and install them in the drive shaft.

6. The shaft for rotary drive needs to use high-strength non-magnetic material metal or alloy material.

7. On the outside of the magnet, the shaft should be installed in a bearing to avoid or reduce the friction between the cylindrical magnetic block and the wall of the cylindrical cavity.

8. An armature should be added to the entire installed magnetic block for shielding. If a good shielding effect is required, the armature can be made in multiple layers, and a non-magnetic shield, such as plastic, is inserted between each layer of armature.

9. The magnets can be connected in series with each other in the axial direction, but it should be noted that the directions of the magnetic blocks are opposite;

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Replacement page (Article 26) When forming four groups, the two groups at the two ends should be in the same direction, while the two groups at the middle are opposite to the two groups at the ends, which can reduce the instability during rotation.

The assembly structure of Figure 2-3 is shown in Figure 1: the structure of the cylindrically-connected magnet in Figure 2. The figure is symmetrical left and right. The internal magnetization direction of each sector is the same, and the magnetization directions of adjacent magnetic blocks differ by 60 ". Therefore, the magnetization direction of the first block on the top right is vertically 30 ° to the right, and Yu sequentially Add 60 °. The left side is magnetized symmetrically to the right side.

Figure 3: This figure shows the distribution of magnetic field lines in a 1/4 cross section in a cylinder. The other parts are symmetrical. It is uniform in the center circular hole, and there are some magnetic leaks on the outside of the magnet because 16 finite blocks are used to form the loop. The size of the outer cylinder is 13 cm in diameter, while the diameter of the inner cylinder hole is 3.2 cm.

Each small magnet unit in Figure 1-2 is installed at a certain angle after being magnetized. The central cavity is the converging space of the magnetic field. When the rotating magnetic block is rotated, you can see that the process of changing the orientation of the magnetic field makes the central space empty. In the working space of the magnetic refrigeration working medium of the cavity, a region in which a strong magnetic field is formed from a closed magnetic circuit to a weak magnetic field or no magnetic field periodic change can be formed.

The size described in the present invention is only an example, and the size is not limited.

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Replacement page (Article 26)

Claims

Rights request

1. A method for realizing magnetization and demagnetization of a magnetic refrigeration working medium by using a dynamic magnetic circuit in room temperature magnetic refrigeration, characterized in that a dynamic magnetic circuit method is used to magnetize and demagnetize a magnetic refrigeration working medium, said dynamic The method of the magnetic circuit is to control the magnitude of the magnetic field in the working space of the magnetic refrigerant working medium by controlling the direction of the magnetic field of the permanent magnet block in the magnetic circuit, and the magnetic refrigerant working medium is stationary relative to the magnet.

2. The method for magnetizing and demagnetizing a magnetic refrigerant using a dynamic magnetic circuit in room temperature magnetic refrigeration according to claim 1, characterized in that dynamic magnetic circuit control is performed on a closed magnetic circuit composed of a permanent magnet, The closed magnetic circuit forms a closed loop with multiple small magnet units, and each small magnet unit is installed at a certain angle after being magnetized. The central cavity is the converging space of the magnetic field. At least four small magnets are driven by the external force on the closed magnetic circuit. Rotation, in the process of changing the orientation of the magnetic field, the magnetic field in the working space where the magnetic refrigeration working medium is located will change periodically from a strong magnetic field to a weak or no magnetic field.

3. The method for magnetizing and demagnetizing a magnetic refrigerant using a dynamic magnetic circuit in room temperature magnetic refrigeration according to claim 1, characterized in that the closed magnetic path forms a closed loop with a plurality of small magnet units, and each small magnet The units are respectively installed at a certain angle after being magnetized. There are at least four small rotating magnets on the closed magnetic circuit. This small magnet is a cylindrical unit, and the shape of one end of the adjacent magnet on the closed magnetic circuit is a concave recess embedded in a cylinder. shape. The center of the closed magnetic circuit is provided with a magnetic refrigeration working material.

4. The method for magnetizing and demagnetizing a magnetic refrigerant using a dynamic magnetic circuit in room temperature magnetic refrigeration according to claim 1, characterized in that the entire magnetic circuit structure comprises a square, a rectangle or a circle, and On the geometric symmetry line, there are pairs of rotatable magnets.

5. The method for magnetizing and demagnetizing a magnetic refrigerant using a dynamic magnetic circuit in room temperature magnetic refrigeration according to claim 4, wherein each of said cylindrically-connected magnet structures is The internal magnetization directions of the sectors are the same. The magnetization directions of adjacent magnetic blocks differ by 60 °. The magnetization direction of the first block on the top right is vertically 30 ° to the right, and Yu sequentially adds 60 °. The left side is magnetized symmetrically to the right side.

6. The method for magnetizing and demagnetizing a magnetic refrigerant using a dynamic magnetic circuit in room temperature magnetic refrigeration according to claim 4, characterized in that the magnetic circuit structure is a square magnetic circuit, and there are four on four sides of the magnet. For a cylindrical magnet unit, a cylindrical angular rotation magnet unit may also be provided at four corners.

7. The method for magnetizing and demagnetizing a magnetic refrigerant using a dynamic magnetic circuit in room temperature magnetic refrigeration according to claim 4, characterized in that an armature should be added to the closed magnetic circuit after the magnetic block is installed. Magnetically shielded.

8. The method for magnetizing and demagnetizing a magnetic refrigerant using a dynamic magnetic circuit in room temperature magnetic refrigeration according to claim 7, wherein the closed magnetic circuit magnets are connected in series with each other in the axial direction, and adjacent magnets The orientation of the blocks is opposite; they are grouped with each other in even numbers.

9. The method for magnetizing and demagnetizing a magnetic refrigerant using a dynamic magnetic circuit in room temperature magnetic refrigeration according to claim 7 or 8, characterized in that the inner wall of the cylindrical cavity, which is a rotatable magnet, is coated Lubricating material Molybdenum disulfide.

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Replacement page (Article 26) 7. The dynamic magnetic circuit used in room temperature magnetic refrigeration according to claim 7 or 8 to realize the magnetization and removal of the magnetic refrigeration working medium, characterized in that the magnets can be connected in series with each other in the axial direction, and the directions of adjacent magnetic blocks are opposite to each other. ; When cascaded into four groups, the two groups at the two ends should be in the same direction, while the two groups at the middle are opposite to the two groups at the ends, which can reduce the instability during rotation.

Replacement page (Article 26;)