Step self-regenerative circulating system for room-temperature magnetic refrigeration

Abstract

The invention discloses a stepped self-regenerative circulating system for room-temperature magnetic refrigeration, which comprises a magnet group, magnet group driving devices, a double-layer regenerator and regenerator driving devices, and the magnet group driving devices capable of driving the magnet group to reciprocate up and down are symmetrically connected to two sides of the magnet group. A high-magnetic-field-intensity air gap is formed in the magnet set, the double-layer heat regenerator is matched with the high-magnetic-field-intensity air gap, and the heat regenerator driving device is arranged on the left side of the double-layer heat regenerator and drives the heat regenerator to move left and right in a reciprocating mode. According to the cascade self-regenerative circulating system for room-temperature magnetic refrigeration, heat exchange fluid is thoroughly removed from the interior of the double-layer heat regenerator, one-way self-regenerative independent of additional elements in the double-layer heat regenerator under a reciprocating structure is achieved, meanwhile, cascade distribution of MCM infinitesimal cell temperature between the cold end and the hot end is achieved through the space-time matching design in the double-layer heat regenerator, and the heat exchange efficiency is improved. And the refrigerating capacity is effectively improved on the premise of ensuring the temperature span.

Description

Technical Field

[0001] The present invention relates to the field of refrigeration technology, and in particular to a stepped self-regenerative circulation system for room-temperature magnetic refrigeration. Background Art

[0002] Environmental protection, energy conservation, and water conservation have become rigid requirements for the development of my country's air-conditioning industry. Currently, the annual output value of my country's refrigeration and air-conditioning industry exceeds 600 billion yuan, but mainstream vapor compression refrigeration technology still relies on hydrofluorocarbons (HFCs) as refrigerants. HFCs pose leakage risks during production and use, and their global warming potential (GWP) is generally above 1000, significantly contributing to the greenhouse effect. To address this challenge, the Kigali Amendment to the Montreal Protocol, which came into effect in 2019, explicitly calls for a reduction in HFC consumption. However, the development of alternative refrigerants faces multiple constraints: hydrofluoroalkanes and olefins require a balance between flammability, high GWP, and toxicity; and natural refrigerants (such as ammonia and carbon dioxide) pose safety risks. Against this backdrop, the development of new, climate-friendly, zero-GWP refrigeration technologies is urgently needed.

[0003] Magnetic refrigeration technology, based on the magnetocaloric effect of magnetocaloric materials (MCMs), is considered an important alternative to HFCs due to its zero global warming potential, high thermodynamic efficiency, and rapid response. Common magnetocaloric materials include gallium-based alloys and manganese-based compounds. Currently, room-temperature magnetic refrigerators based on active regenerative (AMR) cycles have entered the engineering stage, but their core drawback stems from their reliance on heat transfer mechanisms involving heat exchange fluids.

[0004] (1) Material corrosion and frequency limitation: The fluid medium makes MCM susceptible to corrosion, and the system operating frequency is restricted by the fluid flow rate;

[0005] (2) Insufficient heat transfer efficiency: The complex flow path and non-ideal contact between the fluid and the MCM lead to large heat exchange temperature differences and high irreversible losses;

[0006] (3) Secondary heat exchange bottleneck: The establishment of temperature span requires a secondary heat exchange process of “MCM→fluid→MCM”, which further aggravates energy dissipation.

[0007] The above issues indicate that the energy efficiency improvement of the AMR cycle is limited by the convective heat transfer mechanism between the fluid and the MCM. Therefore, all-solid-state magnetic refrigeration technology (replacing the fluid medium with solid-state heat transfer) has become a breakthrough direction. Existing research focuses on solid-state enhanced heat transfer structures (such as thermal switches and phase change materials) and new cycle designs, but still faces two major bottlenecks:

[0008] (1) Dependence on external thermal control components: The heat recovery process needs to be realized with the help of thermoelectric semiconductors or kH heat pipes, which increases the system complexity and cost;

[0009] (2) Limited temperature span: The thermal resistance of the solid-state heat transfer interface makes it difficult for the actual temperature span to meet the requirements of air-conditioning conditions (usually >15K). Summary of the Invention

[0010] The purpose of the present invention is to provide a regenerator that can completely eliminate the heat exchange fluid inside and realize one-way self-regeneration in the regenerator under a reciprocating structure without relying on external components. At the same time, through the "time-space matching" design in the regenerator, a stepped distribution of the temperature of the MCM micro-element between the cold and hot ends is achieved, effectively increasing the cooling capacity while ensuring the temperature span. This is a stepped self-regeneration circulation system for room-temperature magnetic refrigeration.

[0011] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0012] A stepped self-regenerating circulation system for room-temperature magnetic refrigeration includes a magnet group, a magnet group drive device, a double-layer regenerator and a regenerator drive device. The two sides of the magnet group are symmetrically connected to the magnet group drive device that can drive the magnet group to move back and forth up and down. A high magnetic field strength air gap is provided inside the magnet group. The double-layer regenerator matches the high magnetic field strength air gap. The regenerator drive device is arranged on the left side of the double-layer regenerator to drive the regenerator to move back and forth left and right.

[0013] Preferably, the magnet group is a linear magnet group, which includes symmetrically arranged upper magnets and lower magnets. The upper magnets and lower magnets are each composed of a combination of five magnetic blocks with different magnetization directions, and the magnetic blocks are spliced to form an air gap with high magnetic field strength.

[0014] Preferably, the double-layer heat regenerator includes an upper layer heat regenerator and a lower layer heat regenerator each having cells therein, the cells of the upper layer heat regenerator being fully filled with magnetocaloric material; a cold end heat exchanger is placed in the leftmost cell of the lower layer heat regenerator, a hot end heat exchanger is placed in the rightmost cell of the lower layer heat regenerator, and the remaining cells of the lower layer heat regenerator are filled with magnetocaloric material; the left side of the upper layer heat regenerator is connected to the heat regenerator drive device.

[0015] Preferably, the magnetocaloric material is in the shape of a rectangular block.

[0016] Preferably, an upper heat insulation sleeve is provided on the outer side of the upper heat regenerator, and a lower heat insulation sleeve is provided on the outer side of the lower heat regenerator, and both the upper heat insulation sleeve and the lower heat insulation sleeve are made of PVC material.

[0017] Preferably, it further includes a support frame, an intermediate heat transfer plate and a heat transfer block, wherein the intermediate heat transfer plate is arranged above the support frame and between the upper heat regenerator and the lower heat regenerator, the heat transfer block is embedded in the intermediate heat transfer plate, and the heat regenerator drive device is arranged above the left side of the intermediate heat transfer plate.

[0018] Preferably, the heat transfer blocks are made of copper, and the arrangement of the heat transfer blocks corresponds to the unit cell layout of the lower heat regenerator.

[0019] Preferably, a bottom plate is further included, and the magnet group driving device and the support frame are arranged above the bottom plate.

[0020] The present invention has the following beneficial effects due to the adoption of the above technical solution:

[0021] 1. This invention completely eliminates heat exchange fluids through the all-solid-state magnetic refrigeration cycle architecture and the dynamic gradient arrangement design of magnetocaloric materials (MCMs), achieving a heat exchange medium innovation. MCMs are used solely as cooling and cold storage materials, fundamentally addressing the three major drawbacks of the traditional AMR cycle:

[0022] 1) Eliminate corrosion and frequency bottlenecks: No fluid medium is involved, avoiding the performance degradation of the MCM due to fluid corrosion, while also removing the problem of flow rate limiting the system operating frequency;

[0023] 2) Optimize heat transfer paths: Directly conduct heat through solid-state contact, eliminating heat transfer efficiency losses caused by disordered motion of fluid molecules (experiments show that interfacial thermal resistance is reduced by approximately 40%).

[0024] 3) Avoiding secondary heat exchange losses: The establishment of the temperature span relies only on a single heat transfer between MCMs, which reduces thermodynamic irreversible losses by more than 50% compared to the traditional secondary heat exchange mode of "MCM→heat exchange fluid→MCM".

[0025] 2. The present invention achieves the synergistic benefits of heat recovery mechanism reconstruction by arranging magnetocaloric materials in layers:

[0026] 1) Spatiotemporal matching of cooling capacity: The cooling phase of the upper MCM is synchronized with the cooling demand of the lower layer in real time, and a spontaneous heat recovery mechanism is established. The large temperature difference between the fluid and the MCM in the traditional AMR cycle (ΔT>8K) is decomposed into a small temperature difference step heat transfer between adjacent MCM units (ΔT<2K);

[0027] 2) Minimizing entropy generation: Precisely controlling the temperature gradient distribution of the micro-element lattice makes the reheating process approach a quasi-equilibrium state, reducing the total entropy generation of the system by more than 30%;

[0028] 3) Improved refrigeration performance: While maintaining the target temperature span (>15K), the unit cycle cooling capacity is increased by 15%. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of the present invention;

[0030] Figure 2 Schematic diagram of a magnet group and a magnet group driving device;

[0031] Figure 3 Schematic diagram of the high magnetic field strength air gap inside the magnet group;

[0032] Figure 4 Schematic diagram of magnetizing direction of magnet;

[0033] Figure 5 Schematic diagram of the double-layer regenerator structure;

[0034] Figure 6 This is a schematic diagram of the upper regenerator and drive device;

[0035] Figure 7 This is a schematic diagram of the filling form of the upper regenerator;

[0036] Figure 8 This is a schematic diagram of the lower regenerator;

[0037] Figure 9 This is a schematic diagram of the filling form of the lower regenerator;

[0038] Figure 10 Schematic diagram of the middle heat transfer plate;

[0039] Figure 11 This is another structural diagram of the present invention.

[0040] In the figure: 1. Magnet group drive device; 2. Upper magnet; 3. Lower magnet; 4. Lower regenerator; 5. Regenerator drive device; 6. Upper regenerator; 7. Support frame; 8. Bottom plate; 9. High magnetic field strength air gap; 10. Magnetocaloric material; 11. Upper insulation sleeve; 12. Cold end heat exchanger; 13. Hot end heat exchanger; 14. Lower insulation sleeve; 15. Middle heat transfer plate; 16. Heat transfer block. DETAILED DESCRIPTION

[0041] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and by way of preferred embodiments. However, it should be noted that many of the details listed in this specification are merely provided to help the reader gain a thorough understanding of one or more aspects of the present invention, and these aspects of the present invention can be practiced even without these specific details.

[0042] Example 1

[0043] like Figure 1 As shown, a cascade self-regenerative circulation system for room temperature magnetic refrigeration includes a magnet group, a magnet group driving device 1, a double-layer regenerator and a regenerator driving device 5, as shown in FIG. Figure 2 As shown, the two sides of the magnet group are symmetrically connected to the magnet group driving device 1 that can drive the magnet group to move up and down. In specific implementation, the magnet group driving device is an electric push rod, linear motor, servo motor or cylinder that can drive the magnet group to move up and down. Figure 1The magnet group driving device is an electric push rod. Figure 11 The magnet drive device includes a motor, an output shaft, and a push rod. The push rod is driven by the output shaft of the motor to reciprocate up and down. The push rod is connected to both ends of the magnet group, and the magnet group is driven by the push rod to reciprocate up and down. A high magnetic field strength air gap 9 is provided inside the magnet group. The double-layer heat exchanger matches the high magnetic field strength air gap 9. The heat exchanger drive device 5 is provided on the left side of the double-layer heat exchanger to drive the heat exchanger to reciprocate left and right. In a specific implementation, the heat exchanger drive device is a linear motor or a servo motor that can drive the heat exchanger to reciprocate left and right.

[0044] like Figure 3-4 As shown, the magnet group is a linear magnet group, which includes an upper magnet 2 and a lower magnet 3 symmetrically arranged. The upper magnet 2 and the lower magnet 3 are each composed of a combination of five magnetic blocks with different magnetization directions. The magnetic blocks are spliced to form a high magnetic field strength air gap 9;

[0045] like Figure 5-9 As shown, the double-layer regenerator includes an upper regenerator 6 and a lower regenerator 4 with cells therein. The cells of the upper regenerator 6 are fully filled with magnetocaloric material 10. In the double-layer regenerator structure, the upper regenerator 6 and the lower regenerator 4 are filled with magnetocaloric material and do not contain any fluid, thereby avoiding the problem of corrosion of the magnetocaloric material. At the same time, it overcomes the limitation of the system's operating frequency, eliminates the problem of large temperature difference heat recovery between the fluid and the material, reduces irreversible losses in the cycle, and improves the system efficiency.

[0046] A cold-end heat exchanger 12 is placed in the leftmost cell of the lower regenerator 4, a hot-end heat exchanger 13 is placed in the rightmost cell of the lower regenerator 4, and the remaining cells of the lower regenerator 4 are filled with magnetocaloric material 10; the left side of the upper regenerator 6 is connected to the regenerator drive device 5; the magnetocaloric material 10 is in the shape of a rectangular block; an upper insulation sleeve 11 is provided on the outside of the upper regenerator 6, and a lower insulation sleeve 14 is provided on the outside of the lower regenerator 4. Both the upper insulation sleeve 11 and the lower insulation sleeve 14 are made of PVC material. The thermal conductivity of PVC material is low and can block heat transfer between the magnetocaloric materials 10 in the same layer.

[0047] The present invention achieves a four-step cycle, including magnetization, demagnetization, heat transfer, and heat exchange, through the vertical movement of the magnet assembly and the left-right movement of the upper regenerator 6. This achieves one-way self-heating within the regenerator, independent of external components. It also decomposes large temperature differential heat recovery into smaller temperature differentials between material blocks, enabling precise heat recovery. It also creates a stepped temperature distribution within the MCM microcells between the hot and cold ends, increasing cooling capacity. It also effectively reduces cycle entropy generation, improving system efficiency.

[0048] When the upper regenerator 6 is magnetized and the lower regenerator 4 is demagnetized, the electric push rod extends rightward, allowing the magnetocaloric material 10 on the rightmost side of the upper regenerator 6 to contact the hot-end heat exchanger 13 on the rightmost side of the lower regenerator 4, dissipating heat. The remaining magnetocaloric material 10 in the upper regenerator 6 then transfers heat to the magnetocaloric material 10 in the lower regenerator 4. When the lower regenerator 4 is magnetized and the upper regenerator 6 is demagnetized, the regenerator drive 5 is activated, driving the electric push rod to retract leftward, allowing the magnetocaloric material 10 on the leftmost side of the upper regenerator 6 to contact the cold-end heat exchanger 12 on the leftmost side of the lower regenerator 4, achieving cooling. The remaining magnetocaloric material 10 absorbs the heat gained by the magnetocaloric material 10 in the lower regenerator 4 due to magnetization. The coordinated movement of the magnet assembly and the regenerator achieves precise control of magnetization, demagnetization, and heat transfer. The temporal and spatial matching of cold production and use improves the thermodynamic efficiency of the system; avoids the secondary heat exchange process of "magnetocaloric material-heat exchange fluid-magnetocaloric material" in the traditional AMR cycle; and also reduces the irreversible loss in the heat exchange process, thereby improving the overall performance of the system.

[0049] Example 2

[0050] As shown in the figure, this embodiment is consistent with the other structures and performance parameters of embodiment 1, except that it also includes a support frame 7, an intermediate heat transfer plate 15 and a heat transfer block 16. Figure 10 As shown, the intermediate heat transfer plate 15 is disposed above the support frame 7 and between the upper regenerator 6 and the lower regenerator 4. The heat transfer blocks 16 are embedded within the intermediate heat transfer plate 15, and the regenerator drive device 5 is disposed above and to the left of the intermediate heat transfer plate 15. The heat transfer blocks 16 are made of copper and arranged in an array pattern that corresponds to the cell layout of the lower regenerator 4 to reduce the thermal resistance between the upper and lower regenerators 4. The number of heat transfer blocks 16 is consistent with the number of cells in the lower regenerator 4. The system also includes a base plate 8, above which the magnet assembly drive device 1 and support frame 7 are disposed.

[0051] The working principle of the cascade self-regenerative circulation system for room temperature magnetic refrigeration of the present invention is as follows:

[0052] Start the magnet group driving device 1 to move the magnet group downward as a whole, so that the upper regenerator 6 moves into the interior of the upper magnet 2 and is magnetized; at the same time, the lower regenerator 4 moves out of the interior of the lower magnet 3 and is demagnetized;

[0053] The magnet assembly remains in place. The magnetocaloric material 10 in the upper regenerator 6 heats up due to magnetization, transferring heat to the magnetocaloric material 10 in the lower regenerator 4, which cools down due to demagnetization. Simultaneously, the magnetocaloric material 10 on the far right of the upper regenerator 6 transfers heat to the hot-end heat exchanger 13 for dissipation.

[0054] The magnet assembly drive device 1 is activated to move the entire magnet assembly upward, moving the upper regenerator 6 out of the upper magnet 2 and demagnetizing the upper regenerator 6. Simultaneously, the lower regenerator 4 is moved into the lower magnet 3 and magnetized. Simultaneously, the regenerator drive device 5 is activated to move the entire upper regenerator 6 to the left, bringing the leftmost magnetocaloric material 10 into contact with the cold-end heat exchanger 12.

[0055] The position of the magnet group remains unchanged, but the direction of heat transfer is opposite to that in step (2). The magnetocaloric material 10 in the lower regenerator 4 is heated due to magnetization, and transfers heat to the magnetocaloric material 10 in the upper regenerator 6, which is cooled due to demagnetization. At the same time, the magnetocaloric material 10 on the far left of the upper regenerator 6 contacts the hot end heat exchanger 13, absorbing heat and cooling.

[0056] The present invention's stepped self-regenerative circulation system for room-temperature magnetic refrigeration utilizes the vertical reciprocating motion of the magnet assembly and the horizontal reciprocating motion of the upper regenerator (6) to achieve a four-step cycle, including magnetization, demagnetization, heat transfer, and heat exchange. This system completely eliminates heat exchange fluids and utilizes an all-solid-state design, achieving unidirectional self-regenerative heat within the double-layer regenerator in a reciprocating structure, independent of external components. Furthermore, the "time-space matching" design within the double-layer regenerator achieves a stepped distribution of MCM micro-element temperatures between the hot and cold ends, effectively increasing cooling capacity while ensuring a stable temperature span.

[0057] Through innovative structural design and working principle, the present invention effectively overcomes the problems of magnetocaloric material corrosion caused by heat exchange fluid in traditional AMR cycle, limited system operating frequency, low heat exchange efficiency, etc.; by arranging magnetocaloric materials in layers, a precise heat recovery cycle design is realized, effectively reducing the cycle entropy generation; a stepped distribution of MCM micro-element temperature between the cold and hot ends is achieved, which improves the cooling capacity while ensuring the temperature span; and provides new ideas and possibilities for the practical application of room temperature magnetic refrigeration technology.

[0058] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A cascade self-regenerative circulation system for room temperature magnetic refrigeration, characterized by: It includes a magnet group, a magnet group driving device, a double-layer heat exchanger and a heat exchanger driving device. The two sides of the magnet group are symmetrically connected to the magnet group driving device that can drive the magnet group to move back and forth. A high magnetic field strength air gap is provided inside the magnet group. The double-layer heat exchanger matches the high magnetic field strength air gap. The heat exchanger driving device is provided on the left side of the double-layer heat exchanger to drive the heat exchanger to move back and forth.

2. The cascade self-regenerative circulation system for room temperature magnetic refrigeration according to claim 1, characterized in that: The magnet group is a linear magnet group, which includes symmetrically arranged upper magnets and lower magnets. The upper magnet and lower magnet are each composed of a combination of five magnetic blocks with different magnetization directions. The magnetic blocks are spliced to form an air gap with high magnetic field strength.

3. The cascade self-regenerative circulation system for room temperature magnetic refrigeration according to claim 1 or 2, characterized in that: The double-layer heat regenerator includes an upper layer heat regenerator and a lower layer heat regenerator each having cells therein. The cells of the upper layer heat regenerator are fully filled with magnetocaloric material. A cold end heat exchanger is placed in the leftmost cell of the lower layer heat regenerator, and a hot end heat exchanger is placed in the rightmost cell of the lower layer heat regenerator. The remaining cells of the lower layer heat regenerator are filled with magnetocaloric material. The left side of the upper layer heat regenerator is connected to the heat regenerator drive device.

4. The cascade self-regenerative circulation system for room temperature magnetic refrigeration according to claim 3, characterized in that: The magnetocaloric material is in the shape of a rectangular block.

5. The cascade self-regenerative circulation system for room temperature magnetic refrigeration according to claim 3, characterized in that: An upper heat insulation sleeve is provided on the outer side of the upper heat regenerator, and a lower heat insulation sleeve is provided on the outer side of the lower heat regenerator. Both the upper heat insulation sleeve and the lower heat insulation sleeve are made of PVC material.

6. The cascade self-regenerative circulation system for room temperature magnetic refrigeration according to claim 3, characterized in that: The heat exchanger further comprises a support frame, an intermediate heat transfer plate and a heat transfer block. The intermediate heat transfer plate is arranged above the support frame and between the upper heat exchanger and the lower heat exchanger. The heat transfer block is embedded in the intermediate heat transfer plate. The heat exchanger drive device is arranged above the left side of the intermediate heat transfer plate.

7. The cascade self-regenerative circulation system for room temperature magnetic refrigeration according to claim 6, characterized in that: The heat transfer blocks are made of copper material, and the array arrangement of the heat transfer blocks corresponds to the unit cell layout of the lower heat regenerator.

8. The cascade self-regenerative circulation system for room temperature magnetic refrigeration according to claim 6, characterized in that: It also includes a bottom plate, and the magnet group driving device and the support frame are arranged above the bottom plate.

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