High-field permanent magnet magnetic circuit for room temperature magnetic refrigeration and method of using same

Abstract

The application discloses a high-field-strength permanent magnet magnetic circuit for room-temperature magnetic refrigeration, which comprises a low-carbon steel rod, a magnetic ring and a magnetic yoke, the center of the magnetic ring is provided with an intermediate gap, the low-carbon steel rod is located at the intermediate gap, the low-carbon steel rod and the intermediate gap are located on the same axis, and the magnetic yoke is arranged outside the magnetic ring; the magnetic field at the intermediate gap is a non-uniform magnetic field, and the magnetic induction intensity value continuously changes between 0 and a set value. The application further discloses a use method of the high-field-strength permanent magnet magnetic circuit for room-temperature magnetic refrigeration. The application provides a non-uniform magnetic field at the intermediate gap, which is beneficial to the full application of the magnetic heat effect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of room-temperature magnetic refrigeration, and particularly relates to a high-field permanent magnetic magnetic circuit for room-temperature magnetic refrigeration and a use method thereof. BACKGROUND

[0002] At present, the common refrigeration mode in the field of room-temperature refrigeration is gas compression refrigeration, such as air conditioners, refrigerators and refrigerated cabinets. However, the gas compression refrigeration often uses hydrofluorocarbons (HFCs) as refrigerants, and the global warming potential of the refrigerants is thousands of times that of carbon dioxide, causing serious greenhouse effect. Moreover, the energy efficiency of gas compression refrigeration is 5%-10% of the Carnot cycle. In the past five years, many organizations and countries in the world have proposed plans and relevant regulations to gradually eliminate greenhouse gas emissions. China has introduced relevant policies to strengthen the control of greenhouse gas emissions such as hydrofluorocarbons and establish a license system for its import and export. Therefore, it is urgent to develop new room-temperature magnetic refrigeration technology.

[0003] Compared with gas compression refrigeration, room-temperature magnetic refrigeration technology has the advantages of environmental friendliness, stable operation and high energy efficiency, and has attracted much attention in the research field. Room-temperature magnetic refrigeration technology is based on the magneto-caloric effect of magnetic working substance. When the magnetic working substance is in an adiabatic process and a changing magnetic field, the total entropy remains unchanged while the magnetic entropy changes, causing the change of lattice entropy, and the endothermic and exothermic phenomena occur. According to the difference in operation mode, the room-temperature magnetic refrigeration prototypes developed at present can be mainly divided into reciprocating magnetic refrigeration prototypes (magnet reciprocating type, magnetic working substance reciprocating type), rotary magnetic refrigeration machines (magnet rotary type, magnetic working substance rotary type), and the commonly used solid magnetic working substance is metal Gd and its alloy (GdEr, GdTb, GdDy, GdY, etc.).

[0004] The magnetic working substance exhibits the magneto-caloric effect in a changing magnetic field, so the design of the magnetic circuit is a key technology. Compared with superconducting magnetic systems, electromagnets and permanent magnetic systems, the permanent magnetic system has the advantages of simple structure and easy assembly, and is widely used in room-temperature magnetic refrigeration machines. The magnetic field of the permanent magnetic system is mainly provided by NdFeB permanent magnets. The developed permanent magnetic systems include U-shaped, C-shaped and Halbach cylindrical permanent magnetic circuits, and the generated magnetic field range mainly concentrates on 0-1.5T. Among them, the Halbach cylindrical permanent magnetic circuit has a significant magnetic concentration effect and less magnetic leakage, and is the main permanent magnetic system. However, the Halbach cylindrical permanent magnetic circuit is spliced by multiple NdFeB permanent magnets, and the amount of NdFeB permanent magnets is large, which limits the marketization of room-temperature magnetic refrigeration machines.

[0005] Therefore, a method for reducing the demand for NdFeB permanent magnets and controlling the manufacturing cost is needed in the field of room-temperature magnetic refrigeration to further promote the application and marketization of room-temperature magnetic refrigeration technology. SUMMARY

[0006] The application aims to provide a high-field permanent magnet magnetic circuit for room-temperature magnetic refrigeration and a use method thereof.

[0007] The technical scheme is as follows:

[0008] The high-field permanent magnet magnetic circuit for room-temperature magnetic refrigeration comprises a low-carbon steel rod, a magnetic ring and a magnetic yoke, the center of the magnetic ring is provided with an intermediate gap, the low-carbon steel rod is located at the intermediate gap, the low-carbon steel rod and the intermediate gap are located on the same axis, and the magnetic yoke is arranged outside the magnetic ring; the magnetic field at the intermediate gap is a non-uniform magnetic field, and the magnetic induction intensity value continuously changes between 0 and a set value.

[0009] Further, the low-carbon steel rod is in a cylindrical shape, and the material is high-permeability low-carbon steel.

[0010] Further, the magnetic ring comprises a plurality of sector-shaped magnetic blocks and a plurality of sector-shaped low-carbon steel blocks, and the sector-shaped magnetic blocks and the sector-shaped low-carbon steel blocks are arranged at intervals; the magnetic field directions of the sector-shaped magnetic blocks on both sides of the center plane of the axis are symmetrical, and the magnetic field directions of the sector-shaped magnetic blocks on the same side are tangent to the same circle.

[0011] Further, the magnetic ring comprises four sector-shaped magnetic blocks and four sector-shaped low-carbon steel blocks, and the sector-shaped magnetic blocks and the sector-shaped low-carbon steel blocks are alternately arranged and fixed; the central angle of the sector-shaped low-carbon steel block is 45°, and the material is high-permeability low-carbon steel; the sector-shaped magnetic block comprises three sector-shaped permanent magnets, and the central angle of the sector-shaped permanent magnet is 15°.

[0012] Further, the sector-shaped permanent magnet is an NdFeB permanent magnet material.

[0013] Further, the magnetic field directions of the three sector-shaped permanent magnets in the sector-shaped magnetic block are tangent to the same circle.

[0014] Further, the magnetic ring and the magnetic yoke are fixed by screws.

[0015] The use method of the high-field permanent magnet magnetic circuit for room-temperature magnetic refrigeration comprises the following steps:

[0016] The low-carbon steel rod is fixed in position, a magnetic refrigeration bed is placed at the intermediate gap, and the magnetic field at the intermediate gap is a non-uniform magnetic field.

[0017] The magnetic refrigeration bed rotates relative to the magnetic ring, the room-temperature magnetic working substance particles in the magnetic refrigeration bed are excited or demagnetized, and the generated heat or cold is taken away by a heat exchange fluid.

[0018] Preferably, the magnetic ring is fixed in position, the magnetic refrigeration bed is driven to rotate by a motor, and the room-temperature magnetic working substance is excited or demagnetized in the non-uniform magnetic field; the heat generated by the room-temperature magnetic working substance in the excitation process is sent to a heat sink by the heat exchange fluid, and the cold generated in the demagnetization process is sent to a cold accumulator.

[0019] Preferably, the magnetic refrigeration bed position is fixed, a motor is arranged outside the magnetic yoke, and the motor rotating shaft drives the magnetic ring to rotate; the room temperature magnetic working substance is excited or demagnetized in the non-uniform magnetic field; and the heat generated by the room temperature magnetic working substance during the excitation process is sent to the heat sink by the heat exchange fluid, and the cold generated during the demagnetization process is sent to the cold accumulator.

[0020] Compared with the prior art, the application has the following advantages:

[0021] The application provides a non-uniform magnetic field at the intermediate gap, which is beneficial to the full application of the magnetic heat effect.

[0022] The application can effectively solve the problem of large amount of permanent magnet blocks required by the Halbach cylindrical permanent magnetic circuit. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a structural schematic view of the high-field-strength permanent magnetic circuit for room temperature magnetic refrigeration in the application;

[0024] Figure 2 is a schematic view of the magnetization direction of the magnetic ring in the application;

[0025] Figure 3 is a cross-sectional magnetic field distribution diagram of the high-field-strength permanent magnetic circuit for room temperature magnetic refrigeration in the application;

[0026] Figure 4 is a longitudinal cross-sectional magnetic field distribution diagram of the high-field-strength permanent magnetic circuit for room temperature magnetic refrigeration in the application. DETAILED DESCRIPTION

[0027] The following description fully illustrates the specific embodiments of the application to enable a person skilled in the art to practice and reproduce the same.

[0028] As Figure 1 shown, it is a structural schematic view of the high-field-strength permanent magnetic circuit for room temperature magnetic refrigeration in the application.

[0029] The high-field-strength permanent magnetic circuit for room temperature magnetic refrigeration comprises a low-carbon steel rod 1, a magnetic ring 2 and a magnetic yoke 3. The center of the magnetic ring 2 is provided with an intermediate gap 4, and the low-carbon steel rod 1 is located at the intermediate gap 4. The low-carbon steel rod 1 and the intermediate gap 4 are located on the same axis, which is the central axis of the entire high-field-strength permanent magnetic circuit for room temperature magnetic refrigeration. The magnetic yoke 3 is arranged outside the magnetic ring 2.

[0030] The low-carbon steel rod 1 is in a cylindrical shape and is made of low-carbon steel with high magnetic permeability. The low-carbon steel rod 1 is magnetized under the action of the magnetic ring 2 to strengthen the magnetic induction intensity at the intermediate gap 4. The low-carbon steel rod 1 remains stationary during the operation of the room temperature rotary magnetic refrigerator. The magnetic yoke 3 is made of cast iron and serves to fix the magnetic ring 2 and guide the magnetism.

[0031] The intermediate gap 4 is used to place a magnetic refrigeration bed, and the magnetic refrigeration bed is filled with spherical room-temperature magnetic working substance particles; the magnetic refrigeration bed is driven by a motor to rotate around a fixed axis, so as to realize excitation and demagnetization of the room-temperature magnetic working substance; heat generated by the magnetic working substance during excitation and demagnetization is taken away by heat exchange fluid, the low-temperature heat exchange fluid flows through the chamber to realize refrigeration, and the high-temperature heat exchange fluid flows through a heat sink and discharges heat to the surrounding environment. The magnetic field at the intermediate gap 4 is a non-uniform magnetic field, and the magnetic induction intensity continuously changes between 0T and a set value, which is beneficial to the application of the magnetic heat effect.

[0032] As shown in Figure 2 , it is a schematic diagram of the magnetization direction of the magnetic ring 2 in the application.

[0033] The magnetic ring 2 comprises a plurality of sector-shaped magnetic blocks 21 and a plurality of sector-shaped low-carbon steel blocks 22, and the sector-shaped magnetic blocks 21 and the sector-shaped low-carbon steel blocks 22 are arranged at intervals. The magnetic field directions of the sector-shaped magnetic blocks 21 on both sides of the center plane passing through the axis are symmetrical, and the magnetic field directions of the sector-shaped magnetic blocks 21 on the same side are tangent to the same circle.

[0034] After the sector-shaped low-carbon steel blocks 22 are magnetized, they can not only conduct a magnetic field, but also effectively reduce the use amount of the sector-shaped magnetic blocks 21; the low-carbon steel rods 1, the sector-shaped magnetic blocks 21 and the sector-shaped low-carbon steel blocks 22 on both sides of the center plane form a complete magnetic circuit. The magnetic yoke 3 not only fixes the sector-shaped magnetic blocks 21 and the sector-shaped low-carbon steel blocks 22, but also prevents magnetic leakage and improves the magnetic field strength at the intermediate gap 4.

[0035] In the preferred embodiment, the magnetic ring 2 comprises four sector-shaped magnetic blocks 21 and four sector-shaped low-carbon steel blocks 22, and the sector-shaped magnetic blocks 21 and the sector-shaped low-carbon steel blocks 22 are arranged alternately and fixed to form the magnetic ring 2. The magnetic ring 2 and the magnetic yoke 3 are punched by a puncher and fixed by screws. The central angle of the sector-shaped low-carbon steel block 22 is 45°, and the material is high-magnetic-permeability low-carbon steel. The sector-shaped magnetic block 21 comprises three sector-shaped permanent magnets 211, the central angle of the sector-shaped permanent magnet 211 is 15°, the residual magnetic induction intensity is higher than 1.4T, the coercive force is higher than 700kA / m, and the material is NdFeB permanent magnet material, which is beneficial to improving the magnetic induction intensity at the intermediate gap and improving the performance of the rotary room-temperature magnetic refrigerator. The magnetic field directions of the three sector-shaped permanent magnets 211 in the sector-shaped magnetic block 21 are tangent to the same circle and fixed together.

[0036] As shown in Figure 3 , it is a cross-sectional magnetic field distribution diagram of the high-field-strength permanent magnetic circuit for room-temperature magnetic refrigeration in the application. Figure 4 As shown in

[0037] Based on three-dimensional finite element method numerical calculation of spatial magnetic field distribution;

[0038] The three-dimensional finite element method is based on the magnetic field part of Maxwell's equations, which are as follows:

[0039]

[0040]

[0041] In the formula, Magnetic flux density The magnetic field strength;

[0042] Introducing scalar magnetomotive force V m Satisfying the equation

[0043]

[0044] Set the magnetic induction intensity at infinity magnetic field strength and magnetic potential V m It is zero;

[0045] In the numerical modeling process, it is assumed that the NdFeB permanent magnet is uniformly magnetized;

[0046] Magnetic potential V during finite element numerical calculation m The function is continuous at every point within the design structure;

[0047] The designed structure is meshed, and the solution is obtained by using a solver.

[0048] Modeling was performed using COMSOL Multiphysics software equipped with the 3D finite element method. The "Magnetic Field, No Current" interface was selected, and the "Steady State" study was chosen. The 3D geometric model built in Solidworks was imported into COMSOL Multiphysics, and the materials and parameters for each part of the designed structure were selected and input. In the "Magnetic Field, No Current" interface under the model tree, the magnetization direction of each NdFeB permanent magnet and the remanent magnetic induction intensity were defined. Under the "Mesh" interface, the "Extremely Fine" cell size of "Physical Field Controlled Mesh" was selected for mesh generation, and numerical calculations were performed using the "Direct Solver". The calculation results were post-processed to show the spatial magnetic field distribution of the high-field-strength permanent magnet circuit for room temperature magnetic refrigeration.

[0049] The magnetic field at the intermediate gap 4 is a non-uniform magnetic field, with a maximum magnetic induction intensity exceeding 1.5T and a minimum magnetic induction intensity close to 0T. When the room temperature magnetic working fluid is placed at the intermediate gap 4 and rotated on a fixed axis by a rotating motor, the room temperature magnetic working fluid is continuously energized and demagnetized, resulting in a magnetocaloric effect. The heat generated is carried away by the heat exchange fluid, and the low-temperature liquid flows through the chamber to achieve the purpose of cooling.

[0050] The method for using the high-field permanent magnet magnetic circuit for room temperature magnetic refrigeration comprises the following specific steps:

[0051] Step 1: The low-carbon steel rod 1 is fixed in position, and the magnetic refrigeration bed is placed at the middle gap 4, and the magnetic field at the middle gap 4 is a non-uniform magnetic field;

[0052] The low-carbon steel rod 1 is fixed in position and remains stationary during the operation of the room temperature rotary magnetic refrigerator, and the magnetic refrigeration bed is filled with spherical room temperature magnetic working substance particles. The magnetic refrigeration bed is connected to the cold reservoir and the heat sink through a pipeline.

[0053] Step 2: The magnetic refrigeration bed is rotated relative to the magnetic ring 2, and the room temperature magnetic working substance particles in the magnetic refrigeration bed are excited or demagnetized, and the generated heat or cold is taken away by the heat exchange fluid.

[0054] The magnetic ring 2 is fixed in position, and the magnetic refrigeration bed is driven to rotate by the motor, and the room temperature magnetic working substance is excited or demagnetized in the non-uniform magnetic field; the heat generated by the room temperature magnetic working substance during excitation is sent to the heat sink by the heat exchange fluid, and the cold generated during demagnetization is sent to the cold reservoir, and the low temperature is taken away by the heat exchange fluid for refrigeration.

[0055] The magnetic refrigeration bed is fixed in position, and the motor is arranged outside the magnetic yoke 3, and the rotating shaft of the motor drives the magnetic ring 2 to rotate; the room temperature magnetic working substance is excited or demagnetized in the non-uniform magnetic field; the heat generated by the room temperature magnetic working substance during excitation is sent to the heat sink by the heat exchange fluid, and the cold generated during demagnetization is sent to the cold reservoir, and the low temperature is taken away by the heat exchange fluid for refrigeration.

[0056] The terms used in the present application are illustrative and exemplary, but not limiting. Since the present application can be embodied in various forms without departing from the spirit or essential characteristics thereof, it should be understood that the above-described embodiments are not limited to any of the foregoing details, but are to be broadly interpreted within the spirit and scope of the appended claims, and all changes and modifications that fall within the meaning and range of equivalents are intended to be embraced by the claims.

Claims

1. A high-field-strength permanent magnet circuit for room-temperature magnetic refrigeration, characterized in that, include: The magnetic ring comprises a low-carbon steel rod, a magnetic ring, and a magnetic yoke. A central gap is located at the center of the magnetic ring. The magnetic ring includes multiple sector-shaped magnetic blocks and multiple sector-shaped low-carbon steel blocks, arranged alternately. The magnetic field directions of the sector-shaped magnetic blocks on both sides of the central plane passing through the axis are symmetrical, and the magnetic field directions of the sector-shaped magnetic blocks on the same side are tangent to the same circle. The low-carbon steel rod, cylindrical in shape and made of high-permeability low-carbon steel, is located in the central gap. The low-carbon steel rod and the central gap are on the same axis. The magnetic yoke is located outside the magnetic ring. The magnetic field in the central gap is a non-uniform magnetic field, with the magnetic induction intensity continuously varying between 0 and a set value.

2. The high-field-strength permanent magnet circuit for room-temperature magnetic refrigeration as described in claim 1, characterized in that, The magnetic ring consists of four sector-shaped magnetic blocks and four sector-shaped low-carbon steel blocks, which are arranged alternately and fixedly. The central angle of the sector-shaped low-carbon steel blocks is 45°, and the material is low-carbon steel with high magnetic permeability. The sector-shaped magnetic blocks include three sector-shaped permanent magnets, and the central angle of the sector-shaped permanent magnets is 15°.

3. The high-field-strength permanent magnet circuit for room-temperature magnetic refrigeration as described in claim 2, characterized in that, The sector-shaped permanent magnet is made of NdFeB permanent magnet material.

4. The high-field-strength permanent magnet circuit for room-temperature magnetic refrigeration as described in claim 2, characterized in that, The magnetic fields of the three sector permanent magnets in the sector-shaped magnetic block are tangent to the same circle.

5. The high-field-strength permanent magnet circuit for room-temperature magnetic refrigeration as described in claim 1, characterized in that, The magnetic ring and yoke are secured with screws.

6. The method of using the high field strength permanent magnet circuit for room temperature magnetic refrigeration as described in any one of claims 1-5, characterized in that, include: The low-carbon steel bar is fixed in position, and a magnetic refrigeration bed is placed in the middle gap. The magnetic field in the middle gap is a non-uniform magnetic field. The magnetic refrigeration bed rotates relative to the magnetic ring, which is in a fixed position. The magnetic refrigeration bed is driven to rotate by a motor. The room temperature magnetic working fluid is energized or demagnetized in a non-uniform magnetic field. Alternatively, the magnetic refrigeration bed is in a fixed position, and a motor is installed on the outside of the magnetic yoke. The motor shaft drives the magnetic ring to rotate. The room temperature magnetic working fluid particles in the magnetic refrigeration bed are energized or demagnetized in a non-uniform magnetic field. The heat or cold generated is carried away by the heat exchange fluid. The heat generated by the room temperature magnetic working fluid during the energization process is sent to the radiator by the heat exchange fluid, and the cold generated during the demagnetization process is sent to the cold storage.

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