A multi-stage cascaded large-temperature transmagnetic heat pump system

Abstract

This invention provides a multi-stage cascaded magnetic heat pump system with a large temperature span, composed of multiple stages of magnetic heat pump systems directly cascaded for heat exchange. The multi-stage magnetic heat pump system includes a low-temperature stage regenerator system, a first high-temperature stage magnetic heat pump system, and a second high-temperature stage magnetic heat pump system. The interstage flow paths directly mix and exchange heat through an intermediate water tank, reducing the interstage heat exchange temperature difference, improving the thermal efficiency of the magnetic heat pump system, and widening the operating temperature span. This invention increases the system's temperature span through multi-stage active regenerator cascading, solving the problem of limited temperature span in existing single-stage independent or parallel regenerators. By expanding the system's operating temperature span through multi-stage magnetic heat pump cascading, it can be applied to more scenarios, such as water heaters and air conditioners. Simultaneously, it improves existing magnetic regenerator cascading technology by employing a direct mixing method to complete heat transfer between magnetic heat pump stages, reducing the interstage heat exchange temperature difference.

Description

Technical Field

[0001] This invention relates to the field of magnetic heat pump technology, and more specifically, to a multi-stage cascaded large-temperature transverse magnetic heat pump system. Background Technology

[0002] Room temperature magnetic heat pumps utilize the magnetocaloric effect (MCE) of magnetocaloric materials (MCMs) at room temperature to achieve cooling or heating. Compared to vapor compression technology, it eliminates the need for hydrofluorocarbons (HFCs) refrigerants that exacerbate the greenhouse effect, and its theoretical cycle efficiency can reach 60% of the Carnot cycle. It also boasts advantages such as being environmentally friendly, low-noise, and safe and reliable. Therefore, room temperature magnetic heat pump technology is widely recognized as one of the most promising new refrigeration technologies to replace vapor compression refrigeration.

[0003] In recent years, room temperature magnetic refrigeration / room temperature magnetic heat pump technology has developed rapidly. A large number of room temperature magnetic refrigeration prototypes based on the active magnetic regenerator (AMR) principle have emerged, and there have been cases of magnetic refrigeration machines being applied to room air conditioners.

[0004] Currently, most prototypes operate with a single AMR or multiple AMRs in parallel, i.e., single-stage operation. However, the operating temperature range of a single-stage AMR is limited, with most prototypes achieving a maximum temperature range of approximately 20K, which limits their application scenarios. To expand the application range of room temperature magnetic chiller / heat pump systems, multiple AMRs need to be connected in series or stacked.

[0005] Therefore, multi-stage cascaded or series-connected magnetic refrigeration / heat pump systems are of great significance for expanding the temperature span of traditional room-temperature magnetic heat pumps. One series-connected magnetic refrigeration system (CN202010973254.7) directly connects multiple AMRs in series, using a single hydraulic piston pump to drive the reciprocating flow of the fluid. While this increases the system's temperature span, the series operation of multiple regenerators leads to excessive fluid pressure drop, significantly limiting the hydraulic piston pump frequency. Compared to series-connected AMRs, cascaded AMRs offer more advantages for large-temperature-span magnetic refrigeration / heat pump systems: performance is similar to series-connected systems, but lower-pressure pumps can be used, and the AMRs operate independently, making operation more convenient. A cascaded room temperature magnetic refrigeration system (201810315735.1) is described. This invention cascades multiple AMRs (Automatic Magnetically Modulated Magnetic Heat Pumps) and exchanges heat through heat exchangers in between. However, because the intermediate heat exchange in such cascaded magnetic heat pumps typically uses plate heat exchangers, the heat exchange temperature difference between AMR stages increases, further reducing the hard-won operating temperature range. Therefore, the key to this invention is to design a multi-stage AMR cascaded magnetic heat pump system with high interstage heat exchange efficiency and a simple structure. Summary of the Invention

[0006] To address the issues of small temperature span in existing room temperature magnetic heat pumps and to reduce the heat exchange temperature difference between AMR stages, this invention provides a multi-stage cascaded magnetic heat pump system with a large temperature span.

[0007] The present invention is achieved by at least one of the following technical solutions.

[0008] A multi-stage cascaded high-temperature magnetic heat pump system includes a multi-stage magnetic heat pump system, wherein the multi-stage magnetic heat pump system includes a low-temperature stage regenerator system, a first high-temperature stage magnetic heat pump system, and a second high-temperature stage magnetic heat pump system.

[0009] The low-temperature stage regenerator system includes a first heat exchanger, a first water tank, a first water pump, a first check valve, a first magnetic regenerator, a first solenoid valve, a first filter, a second water tank, a second water pump, and a second check valve connected in sequence. The output end of the second check valve is connected to the input end of the first filter, and the first solenoid valve is located between the second check valve and the first filter. The end of the first magnetic regenerator connected to the first check valve is also connected to the second filter, and the output end of the second filter is connected to the input end of the first heat exchanger. A second solenoid valve is provided between the first magnetic regenerator and the second filter.

[0010] The first high-temperature magnetic heat pump system includes a third water pump, a third one-way valve, a second magnetic regenerator, a third solenoid valve, a third filter, a third water tank, and a fourth water pump connected in sequence; the third water pump is connected to the second water tank; the fourth water pump is connected to one end of the second magnetic regenerator through the fourth one-way valve, and the other end of the second magnetic regenerator is connected to the third water pump, the fourth solenoid valve, the fourth filter, and the second water tank in sequence;

[0011] The second high-temperature magnetic heat pump system includes a fifth water pump, a fifth one-way valve, a third magnetic regenerator, a fifth solenoid valve, a fifth filter, and a second heat exchanger that outputs heat externally, connected in sequence. The fifth water pump is connected to a third water tank. The output end of the second heat exchanger is connected in sequence to a fourth water tank, a sixth water pump, and a sixth one-way valve. The output end of the sixth one-way valve is connected between one end of the third magnetic regenerator and the fifth solenoid valve. The other end of the third magnetic regenerator is connected in sequence to a sixth solenoid valve and a sixth filter. The other end of the sixth filter is connected to the third water tank.

[0012] The first magnetic regenerator, the second magnetic regenerator, and the third magnetic regenerator are respectively equipped with a first permanent magnet, a second permanent magnet, and a third permanent magnet.

[0013] Furthermore, the first magnetic regenerator, the second magnetic regenerator, and the third magnetic regenerator include a magnetic regenerator shell and an internal magnetic thermal material.

[0014] Furthermore, the material of the magnetic regenerator housing is not limited to PVC or PMMA.

[0015] Furthermore, the cross-sectional shape of the magnetic regenerator is not limited to rectangle or circle.

[0016] Furthermore, the magnetocaloric material is not limited to granular Gd, Gd-based alloys, La-Fe-Si alloys, or MnFePSi alloys.

[0017] Furthermore, the first permanent magnet, the second permanent magnet, and the third permanent magnet are not limited to nested Halbach magnets.

[0018] Furthermore, the first heat exchanger and the second heat exchanger are not limited to tube-fin heat exchangers, plate heat exchangers, and microchannel heat exchangers.

[0019] Furthermore, the heat exchange fluid used for heat exchange with the solid magnetocalor material inside the magnetic regenerator is not limited to water, deionized water, salt solution, or ethylene glycol-water solution.

[0020] Furthermore, the operating mode of the high-temperature transmagnetic heat pump system is as follows:

[0021] The multi-stage magnetic heat pump system operates at the same frequency and synchronously. The first permanent magnet, the second permanent magnet, and the third permanent magnet rotate to the high magnetic field position at the same time. The magnetic thermal materials in the first, second, and third magnetic regenerators are magnetized and heated. The heat exchange fluid is pumped into the magnetic regenerator by the first, third, and fifth water pumps to complete the cold blowing process.

[0022] Subsequently, the first, second, and third permanent magnets simultaneously rotate to a low magnetic field position, and the magnetothermal materials in the first, second, and third magnetic regenerators demagnetize and cool down. The heat exchange fluid is pumped into the magnetic regenerator by the second, fourth, and sixth water pumps to complete the heat blowing process. This cycle repeats, and the magnetothermal materials in the first, second, and third magnetic regenerators will form a temperature span along the axis. The heat from the hot end of the first magnetic regenerator is transferred to the cold end of the second magnetic regenerator, and the heat from the hot end of the second magnetic regenerator is transferred to the cold end of the third magnetic regenerator, forming a superposition between the regenerators and expanding the operating temperature span of the system.

[0023] Furthermore, the operating mode of the high-temperature transmagnetic heat pump system is as follows:

[0024] The multi-stage magnetic heat pump system operates at the same frequency but not synchronously. The first and third permanent magnets rotate to the high magnetic field position, and the second permanent magnet rotates to the low magnetic field position. The magnetic thermal materials in the first and third magnetic regenerators are magnetized and heated, while the magnetic thermal materials in the second magnetic regenerator are demagnetized and cooled. The heat exchange fluid is pumped into the magnetic regenerator by the first, fourth, and fifth water pumps. The first and third magnetic regenerators complete the cold blowing process, and the second magnetic regenerator completes the hot blowing process.

[0025] Subsequently, the first and third permanent magnets rotate to a low magnetic field position, and the second permanent magnet rotates to a high magnetic field position. The magnetothermal materials in the first and third magnetic regenerators demagnetize and cool down, while the magnetothermal materials in the second magnetic regenerator are magnetized and heated up. The heat exchange fluid is pumped into the magnetic regenerator by the second, third, and sixth water pumps. The first and third magnetic regenerators complete the hot blowing process, and the second magnetic regenerator completes the cold blowing process. This cycle repeats, and the magnetothermal materials of the first, second, and third magnetic regenerators will form a temperature span along the axis. The heat from the hot end of the first magnetic regenerator is transferred to the cold end of the second magnetic regenerator, and the heat from the hot end of the second magnetic regenerator is transferred to the cold end of the third magnetic regenerator, forming a superposition between the regenerators and expanding the operating temperature span of the system.

[0026] Compared with existing technologies, the beneficial effects of the present invention are as follows:

[0027] This invention expands the operating temperature range of a system by using multi-stage magnetic heat pumps in combination, based on the single-stage magnetic heat pump operating alone or in parallel, enabling its application in more scenarios, such as water heaters and air conditioners. At the same time, it improves the existing magnetic regenerator cascade technology by using a direct mixing method to complete the heat transfer between magnetic heat pump stages and reduce the temperature difference between stages. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the flow path of the three-stage cascaded magnetic heat pump system in Example 1.

[0029] Figure 2 This is a schematic diagram of a nested Harbach magnet with a high magnetic field, as shown in the example.

[0030] Figure 3 This is a schematic diagram of a nested Halbach magnet with a low magnetic field, as shown in the example. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to specific embodiments:

[0032] like Figure 1 As shown, this embodiment of a multi-stage cascaded large-temperature-crossing magnetic heat pump system is a large-temperature-crossing magnetic heat pump system composed of a low-temperature stage regenerator system, at least one high-temperature stage magnetic heat pump system, and an interstage water tank for direct heat exchange. Taking a three-stage magnetic heat pump system as an example, the three-stage cascaded magnetic heat pump system includes a low-temperature stage regenerator system, a first high-temperature stage magnetic heat pump system, and a second high-temperature stage magnetic heat pump system.

[0033] Specifically, the low-temperature stage regenerator system includes a first heat exchanger 1 that exchanges heat with the environment, a first water tank 2, a first water pump 3, a first check valve 4, a first magnetic regenerator 5, a first permanent magnet 6, a first solenoid valve 7, a first filter 8, a second water tank 9, a second water pump 10, a second check valve 11, a second solenoid valve 12, a second filter 13, a closed-loop flow path system, and a heat exchange fluid;

[0034] The first heat exchanger 1, the first water tank 2, the first water pump 3, the first check valve 4, the first magnetic regenerator 5, the first solenoid valve 7, the first filter 8, the second water tank 9, the second water pump 10, and the second check valve 11 are connected in sequence; the output end of the second check valve 11 is connected to the input end of the first filter 8, and the first solenoid valve 7 is located between the second check valve 11 and the first filter 8; the end of the first magnetic regenerator 5 connected to the first check valve 4 is also connected to the second filter 13, the output end of the second filter 13 is connected to the input end of the first heat exchanger 1, and a second solenoid valve 12 is provided between the first magnetic regenerator 5 and the second filter 13;

[0035] The first high-temperature magnetic heat pump system includes a third water pump 14, a third check valve 15, a second magnetic regenerator 16, a second permanent magnet 17, a third solenoid valve 18, a third filter 19, a third water tank 20, a fourth water pump 21, a fourth check valve 22, a fourth solenoid valve 23, a fourth filter 24, a closed-loop flow path system, and a heat exchange fluid.

[0036] The third water pump 14, the third one-way valve 15, the second magnetic regenerator 16, the third solenoid valve 18, the third filter 19, the third water tank 20, and the fourth water pump 21 are connected in sequence; the third water pump 14 is connected to the second water tank 9; the fourth water pump 21 is connected to one end of the second magnetic regenerator 16 through the fourth one-way valve 22, and the other end of the second magnetic regenerator 16 is connected to the third water pump 14, the fourth solenoid valve 23, the fourth filter 24, and the second water tank 9, and directly mixes and exchanges heat with the low-temperature stage regenerator system;

[0037] The second high-temperature stage magnetic heat pump system includes a third water tank 20, a fifth water pump 25, a fifth check valve 26, a third magnetic regenerator 27, a third permanent magnet 28, a fifth solenoid valve 29, a fifth filter 30, a second heat exchanger 31 that directly mixes and exchanges heat with the first high-temperature stage regenerator system, a fourth water tank 32, a sixth water pump 33, a sixth check valve 34, a sixth solenoid valve 35, a sixth filter 36, a closed-loop flow path system, and a heat exchange fluid;

[0038] The third water tank 20, the fifth water pump 25, the fifth one-way valve 26, the third magnetic regenerator 27, the fifth solenoid valve 29, the fifth filter 30, and the second heat exchanger 31 that outputs heat are connected in sequence. The output end of the second heat exchanger 31 is connected in sequence to the fourth water tank 32, the sixth water pump 33, and the sixth one-way valve 34. The output end of the sixth one-way valve 34 is connected between one end of the third magnetic regenerator 27 and the fifth solenoid valve 29. The other end of the third magnetic regenerator 27 is connected in sequence to the sixth solenoid valve 35 and the sixth filter 36. The other end of the sixth filter 36 is connected to the third water tank 20, and it directly mixes and exchanges heat with the first high-temperature stage regenerator system.

[0039] Specifically, the outer shell of the magnetic regenerator is made of engineering plastics such as PVC, and its cross-sectional shape is round.

[0040] In a preferred embodiment, the first magnetic regenerator 5 is filled with spherical Gd-Er series and Gd magnetocaloric materials with Curie temperatures ranging from 0 to 20°C, arranged in order of increasing Curie temperature; the second magnetic regenerator 16 is filled with spherical Gd and granular LaFeSi series magnetocaloric materials with Curie temperatures ranging from 20 to 40°C, arranged in order of increasing Curie temperature; and the third magnetic regenerator 27 is filled with granular LaFeSi series magnetocaloric materials with Curie temperatures ranging from 40 to 60°C, arranged in order of increasing Curie temperature.

[0041] Specifically, the first heat exchanger 1 and the second heat exchanger 31 are plate heat exchangers. Preferably, the heat exchange between the stages of the magnetic heat pump is carried out by a direct fluid mixing heat exchanger, such as the second water tank 9 and the third water tank 20.

[0042] In a preferred embodiment, the first permanent magnet 6, the second permanent magnet 17, and the third permanent magnet 28 are nested Halbach magnets, such as... Figure 2 , Figure 3 As shown;

[0043] Specifically, the regenerator, pipelines, heat exchanger and water tank are filled with heat exchange fluid, and the water tank is placed high and has a filling port. Preferably, the heat exchange fluid is an ethylene glycol-water solution.

[0044] The operation of the multi-stage cascaded large-temperature-span magnetic heat pump system of this invention mainly has the following two modes:

[0045] Operating Mode 1:

[0046] In a three-stage magnetic heat pump system, the three magnets operate at the same frequency and synchronously. Figure 1As shown, the first permanent magnet 6 rotates to the high magnetic field position, and the magnetocaloric material in the first regenerator 5 is magnetized and heated (referring to the temperature compared to the moment before magnetization, the magnitude of which depends on the magnetic induction intensity; for example, when the magnetic induction intensity is 1.5T and the temperature is 20℃, the temperature of the Gd material increases by about 3 to 4℃). The first solenoid valve 7 and the first water pump 3 are opened, and the second solenoid valve 12 and the second pump 10 are closed. The relatively cold fluid in the first water tank 2 flows through the first magnetic regenerator 5 through the first one-way valve 4 under the action of the first water pump 3, and exchanges heat with the heated magnetocaloric material. The fluid temperature rises and the magnetocaloric material temperature drops, forming a temperature gradient along the length direction. Under the back pressure of the second one-way valve 11, the heated fluid flowing out of the first magnetic regenerator 5 can only flow into the second water tank 9 through the first solenoid valve 7 and the first filter 8, causing the fluid temperature in the second water tank 9 to rise.

[0047] Meanwhile, the second permanent magnet 17 of the first high-temperature magnetic heat pump system rotates to the high magnetic field position, the magnetic thermal material in the second magnetic regenerator 16 is magnetized and heated, the third solenoid valve 18 and the third water pump 14 are opened, and the fourth solenoid valve 23 and the fourth water pump 21 are closed. The fluid in the second water tank 9 flows through the second regenerator 16 through the third one-way valve 15 under the action of the third water pump 14, and exchanges heat with the heated magnetic thermal material. The fluid temperature rises and the magnetic thermal material temperature drops, and a temperature gradient is formed along the length direction. Under the back pressure of the fourth one-way valve 22, the heated fluid flowing out of the second magnetic regenerator 16 can only flow into the third water tank 20 through the third solenoid valve 18 and the third filter 19, so that the fluid temperature in the third water tank 20 rises.

[0048] Simultaneously, the third permanent magnet 28 of the second high-temperature magnetic heat pump system rotates to the high magnetic field position, the magnetic thermal material in the third magnetic regenerator 27 is magnetized and heated, the fifth solenoid valve 29 and the fifth water pump 25 are opened, and the sixth solenoid valve 35 and the sixth pump 33 are closed. The fluid in the third water tank 20 flows through the third regenerator 27 through the fifth one-way valve 26 under the action of the fifth water pump 25, and exchanges heat with the heated magnetic thermal material. The fluid temperature rises and the magnetic thermal material temperature drops, and a temperature gradient is formed along the length direction. Under the back pressure of the sixth one-way valve 34, the heated fluid flowing out of the third magnetic regenerator 27 can only flow into the second heat exchanger 32 through the sixth solenoid valve 29 and the sixth filter 30, and outputs heat to the outside. After outputting heat, the fluid temperature drops and flows to the fourth water tank 32.

[0049] Next, the first permanent magnet 6 of the low-temperature stage system rotates to the low magnetic field position (approximately 0T), and the magnetocaloric material in the first magnetic regenerator 5 demagnetizes and cools down (meaning the temperature drops compared to the moment before demagnetization, the magnitude of which depends on the magnetic induction intensity; for example, when the magnetic induction intensity is 1.5T and the temperature is 20℃, the temperature of the Gd material drops by about 3-4℃). The first solenoid valve 7 and the first water pump 3 are closed, and the second solenoid valve 12 and the second water pump 10 are opened. The hotter fluid in the second water tank 9 flows through the first regenerator 5 through the second one-way valve 11 under the action of the second water pump 10, and exchanges heat with the cooled magnetocaloric material. The fluid temperature drops (below the ambient temperature), the temperature of the magnetocaloric material rises, and the previously formed temperature gradient is increased. Under the back pressure of the second one-way valve 4, the cooled fluid flowing out of the first magnetic regenerator 5 can only flow into the first heat exchanger 1 through the second solenoid valve 12 and the second filter 13. The fluid below the ambient temperature absorbs heat from the environment and then flows to the first water tank 2.

[0050] Meanwhile, the second permanent magnet 17 of the first high-temperature stage magnetic heat pump system rotates to the low magnetic field position, the magnetic thermal material in the second regenerator 16 demagnetizes and cools down, the third solenoid valve 18 and the third water pump 14 close, and the fourth solenoid valve 23 and the fourth water pump 21 open. The fluid in the third water tank 20 flows through the second magnetic regenerator 16 through the fourth one-way valve 22 under the action of the fourth water pump 21, and exchanges heat with the cooled magnetic thermal material. The fluid temperature decreases and the temperature of the magnetic thermal material increases, and the original temperature gradient is increased. Under the back pressure of the third one-way valve 15, the cooled fluid flowing out of the second magnetic regenerator 16 can only flow into the second water tank 9 through the fourth solenoid valve 23 and the fourth filter 24, and complete the heat exchange with the low-temperature stage hot end in the second water tank 9.

[0051] Simultaneously, the third permanent magnet 28 of the second high-temperature stage magnetic heat pump system rotates to the low magnetic field position, the magnetic thermal material in the third magnetic regenerator 27 demagnetizes and cools down, the fifth solenoid valve 29 and the fifth water pump 25 close, and the sixth solenoid valve 35 and the sixth water pump 33 open. The fluid in the fourth water tank 32 flows through the third magnetic regenerator 27 through the sixth one-way valve 34 under the action of the sixth pump 33, and exchanges heat with the cooled magnetic thermal material. The fluid temperature decreases, the magnetic thermal material temperature increases, and the original temperature gradient increases. Under the back pressure of the fifth one-way valve 26, the cooled fluid flowing out of the third magnetic regenerator 27 can only flow into the third water tank 20 through the sixth solenoid valve 35 and the sixth filter 36, and complete the heat exchange with the medium-temperature stage hot end in the third water tank 20.

[0052] By continuously repeating the above 6 processes, the system temperature can be brought up to the working range, and heat can be continuously absorbed from the cold end and released from the hot end to achieve the purpose of heating.

[0053] Operating Mode 2:

[0054] The three magnets of the three-stage magnetic heat pump system operate at the same frequency but not synchronously. For example, the low-temperature magnetic heat pump system and the second high-temperature magnetic heat pump system operate synchronously at the same frequency, while the first high-temperature magnetic heat pump system operates synchronously at the same frequency with a phase difference of 180°.

[0055] Specifically, such as Figure 1 As shown, the first permanent magnet 6 of the low-temperature stage system rotates to the high magnetic field position, the magnetothermal material in the first regenerator 5 is magnetized and heated, the first solenoid valve 7 and the first water pump 3 are opened, and the second solenoid valve 12 and the second pump 10 are closed. The relatively cold fluid in the first water tank 2 flows through the first magnetic regenerator 5 through the first one-way valve 4 under the action of the first water pump 3, and exchanges heat with the heated magnetothermal material. The fluid temperature rises and the magnetothermal material temperature drops, and a temperature gradient is formed along the length direction. Under the back pressure of the second one-way valve 11, the heated fluid flowing out of the first magnetic regenerator 5 can only flow into the second water tank 9 through the first solenoid valve 7 and the first filter 8, so that the fluid temperature in the second water tank 9 rises.

[0056] Meanwhile, the second permanent magnet 17 of the first high-temperature stage magnetic heat pump system rotates to the low magnetic field position, the magnetic thermal material in the second regenerator 16 demagnetizes and cools down, the third solenoid valve 18 and the third water pump 14 close, and the fourth solenoid valve 23 and the fourth water pump 21 open. The fluid in the third water tank 20 flows through the second magnetic regenerator 16 through the fourth one-way valve 22 under the action of the fourth water pump 21, and exchanges heat with the cooled magnetic thermal material. The fluid temperature decreases and the temperature of the magnetic thermal material increases, and the original temperature gradient is increased. Under the back pressure of the third one-way valve 15, the cooled fluid flowing out of the second magnetic regenerator 16 can only flow into the second water tank 9 through the fourth solenoid valve 23 and the fourth filter 24, and complete the heat exchange with the low-temperature stage hot end in the second water tank 9.

[0057] Simultaneously, the third permanent magnet 28 of the second high-temperature magnetic heat pump system rotates to the high magnetic field position, the magnetic thermal material in the third magnetic regenerator 27 is magnetized and heated, the fifth solenoid valve 29 and the fifth water pump 25 are opened, and the sixth solenoid valve 35 and the sixth pump 33 are closed. The fluid in the third water tank 20 flows through the third regenerator 27 through the fifth one-way valve 26 under the action of the fifth water pump 25, and exchanges heat with the heated magnetic thermal material. The fluid temperature rises and the magnetic thermal material temperature drops, and a temperature gradient is formed along the length direction. Under the back pressure of the sixth one-way valve 34, the heated fluid flowing out of the third magnetic regenerator 27 can only flow into the second heat exchanger 32 through the sixth solenoid valve 29 and the sixth filter 30, and outputs heat to the outside. After outputting heat, the fluid temperature drops and flows to the fourth water tank 32.

[0058] Next, the first permanent magnet 6 of the low-temperature stage system rotates to the low magnetic field position, the magnetocaloric material in the first magnetic regenerator 5 demagnetizes and cools down, the first solenoid valve 7 and the first water pump 3 are closed, and the second solenoid valve 12 and the second water pump 10 are opened. The hotter fluid in the second water tank 9 flows through the first regenerator 5 through the second one-way valve 11 under the action of the second water pump 10, and exchanges heat with the cooled magnetocaloric material. The fluid temperature drops (below the ambient temperature), the temperature of the magnetocaloric material rises, and the previously formed temperature gradient is increased. Under the back pressure of the second one-way valve 4, the cooled fluid flowing out of the first magnetic regenerator 5 can only flow into the first heat exchanger 1 through the second solenoid valve 12 and the second filter 13. The fluid below the ambient temperature absorbs heat from the environment and then flows to the first water tank 2.

[0059] Meanwhile, the second permanent magnet 17 of the first high-temperature magnetic heat pump system rotates to the high magnetic field position, the magnetic thermal material in the second magnetic regenerator 16 is magnetized and heated, the third solenoid valve 18 and the third water pump 14 are opened, and the fourth solenoid valve 23 and the fourth water pump 21 are closed. The fluid in the second water tank 9 flows through the second regenerator 16 through the third one-way valve 15 under the action of the third water pump 14, and exchanges heat with the heated magnetic thermal material. The fluid temperature rises and the magnetic thermal material temperature drops, and a temperature gradient is formed along the length direction. Under the back pressure of the fourth one-way valve 22, the heated fluid flowing out of the second magnetic regenerator 16 can only flow into the third water tank 20 through the third solenoid valve 18 and the third filter 19, so that the fluid temperature in the third water tank 20 rises.

[0060] Simultaneously, the third permanent magnet 28 of the second high-temperature stage magnetic heat pump system rotates to the low magnetic field position, the magnetic thermal material in the third magnetic regenerator 27 demagnetizes and cools down, the fifth solenoid valve 29 and the fifth water pump 25 close, and the sixth solenoid valve 35 and the sixth water pump 33 open. The fluid in the fourth water tank 32 flows through the third magnetic regenerator 27 through the sixth one-way valve 34 under the action of the sixth pump 33, and exchanges heat with the cooled magnetic thermal material. The fluid temperature decreases, the magnetic thermal material temperature increases, and the original temperature gradient increases. Under the back pressure of the fifth one-way valve 26, the cooled fluid flowing out of the third magnetic regenerator 27 can only flow into the third water tank 20 through the sixth solenoid valve 35 and the sixth filter 36, and complete the heat exchange with the medium-temperature stage hot end in the third water tank 20.

[0061] By repeating the above process, the system temperature can be brought up to the operating range to meet the heating requirements.

[0062] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A multi-stage cascaded large-temperature transmagnetic heat pump system, characterized in that: It includes a multi-stage magnetic heat pump system, which comprises a low-temperature stage regenerator system, a first high-temperature stage magnetic heat pump system, and a second high-temperature stage magnetic heat pump system. The low-temperature stage regenerator system includes a first heat exchanger (1), a first water tank (2), a first water pump (3), a first check valve (4), a first magnetic regenerator (5), a first solenoid valve (7), a first filter (8), a second water tank (9), a second water pump (10), and a second check valve (11) connected in sequence. The output end of the second check valve (11) is connected to the input end of the first filter (8), and the first solenoid valve (7) is located between the second check valve (11) and the first filter (8). The first magnetic regenerator (5) is connected to the first check valve (4) and the second filter (13) is also connected to the first filter (13). The output end of the second filter (13) is connected to the input end of the first heat exchanger (1), and a second solenoid valve (12) is provided between the first magnetic regenerator (5) and the second filter (13). The first high-temperature magnetic heat pump system includes a third water pump (14), a third check valve (15), a second magnetic regenerator (16), a third solenoid valve (18), a third filter (19), a third water tank (20), and a fourth water pump (21) connected in sequence; the third water pump (14) is connected to the second water tank (9); the fourth water pump (21) is connected to one end of the second magnetic regenerator (16) through the fourth check valve (22), and the other end of the second magnetic regenerator (16) is connected to the third water pump (14), the fourth solenoid valve (23), the fourth filter (24), and the second water tank (9); The second high-temperature magnetic heat pump system includes a fifth water pump (25), a fifth check valve (26), a third magnetic regenerator (27), a fifth solenoid valve (29), a fifth filter (30), and a second heat exchanger (31) that outputs heat externally, connected in sequence. The fifth water pump (25) is connected to the third water tank (20). The output end of the second heat exchanger (31) is connected in sequence to the fourth water tank (32), the sixth water pump (33), and the sixth check valve (34). The output end of the sixth check valve (34) is connected between one end of the third magnetic regenerator (27) and the fifth solenoid valve (29). The other end of the third magnetic regenerator (27) is connected in sequence to the sixth solenoid valve (35) and the sixth filter (36). The other end of the sixth filter (36) is connected to the third water tank (20). The first magnetic regenerator (5), the second magnetic regenerator (16), and the third magnetic regenerator (27) are respectively equipped with a first permanent magnet (6), a second permanent magnet (17), and a third permanent magnet (28).

2. The multi-stage cascaded large-temperature transmagnetic heat pump system according to claim 1, characterized in that: The first magnetic regenerator (5), the second magnetic regenerator (16), and the third magnetic regenerator (27) include a magnetic regenerator shell and an internal magnetic thermal material.

3. The multi-stage cascaded large-temperature transmagnetic heat pump system according to claim 2, characterized in that: The material of the magnetic regenerator housing is not limited to PVC or PMMA.

4. The multi-stage cascaded large-temperature transmagnetic heat pump system according to claim 1, characterized in that: The cross-sectional shape of the magnetic regenerator is not limited to rectangle or circle.

5. The multi-stage cascaded large-temperature transmagnetic heat pump system according to claim 2, characterized in that: The magnetocaloric material is not limited to granular Gd, Gd-based alloys, La-Fe-Si alloys, or MnFePSi alloys.

6. The multi-stage cascaded large-temperature transmagnetic heat pump system according to claim 1, characterized in that: The first permanent magnet (6), the second permanent magnet (17), and the third permanent magnet (28) are not limited to nested Halbach magnets.

7. The multi-stage cascaded large-temperature transmagnetic heat pump system according to claim 1, characterized in that: The first heat exchanger (1) and the second heat exchanger (31) are not limited to tube-fin heat exchangers, plate heat exchangers, and microchannel heat exchangers.

8. The multi-stage cascaded large-temperature transmagnetic heat pump system according to claim 1, characterized in that: The heat exchange fluid used for heat exchange with the solid magnetocalor material inside the magnetic regenerator is not limited to water, deionized water, salt solution, or ethylene glycol-water solution.

9. The multi-stage cascaded large-temperature transmagnetic heat pump system according to claim 1, characterized in that: The operating mode of the high-temperature transmagnetic heat pump system is as follows: The multi-stage magnetic heat pump system operates at the same frequency and synchronously. The first permanent magnet (6), the second permanent magnet (17), and the third permanent magnet (28) rotate to the high magnetic field position at the same time. The magnetic thermal materials in the first magnetic regenerator (5), the second magnetic regenerator (16), and the third magnetic regenerator (27) are magnetized and heated. The heat exchange fluid is pumped into the magnetic regenerator by the first water pump (3), the third water pump (14), and the fifth water pump (25) to complete the cold blowing process. Subsequently, the first permanent magnet (6), the second permanent magnet (17), and the third permanent magnet (28) rotate simultaneously to the low magnetic field position. The magnetothermal materials in the first magnetic regenerator (5), the second magnetic regenerator (16), and the third magnetic regenerator (27) demagnetize and cool down. The heat exchange fluid is pumped into the magnetic regenerator by the second water pump (10), the fourth water pump (21), and the sixth water pump (33) to complete the heat blowing process. This cycle repeats, and the magnetothermal materials of the first magnetic regenerator (5), the second magnetic regenerator (16), and the third magnetic regenerator (27) will form a temperature span along the axis. The heat from the hot end of the first magnetic regenerator (5) is transferred to the cold end of the second magnetic regenerator (16), and the heat from the hot end of the second magnetic regenerator (16) is transferred to the cold end of the third magnetic regenerator (27), forming a superposition between the regenerators and expanding the working temperature span of the system.

10. The multi-stage cascaded large-temperature transmagnetic heat pump system according to claim 1, characterized in that: The operating mode of the high-temperature transmagnetic heat pump system is as follows: The multi-stage magnetic heat pump system operates at the same frequency but not synchronously. The first permanent magnet (6) and the third permanent magnet (28) rotate to the high magnetic field position, and the second permanent magnet (17) rotates to the low magnetic field position. The magnetic thermal materials in the first magnetic regenerator (5) and the third magnetic regenerator (27) are magnetized and heated, while the magnetic thermal materials in the second magnetic regenerator (16) are demagnetized and cooled. The heat exchange fluid is pumped into the magnetic regenerator by the first water pump (3), the fourth water pump (21), and the fifth water pump (25). The first magnetic regenerator (5) and the third magnetic regenerator (27) complete the cold blowing process, and the second magnetic regenerator (16) completes the hot blowing process. Subsequently, the first permanent magnet (6) and the third permanent magnet (28) rotate to the low magnetic field position, and the second permanent magnet (17) rotates to the high magnetic field position. The magnetothermal materials of the first magnetic regenerator (5) and the third magnetic regenerator (27) are demagnetized and cooled down, while the magnetothermal materials in the second magnetic regenerator (16) are magnetized and heated up. The heat exchange fluid is pumped into the magnetic regenerator by the second water pump (10), the third water pump (14), and the sixth water pump (33). After the hot blowing process is completed, the second magnetic regenerator (16) completes the cold blowing process; this cycle repeats, and the magnetic thermal materials of the first, second, and third magnetic regenerators (5), (16), and (27) will form a temperature span along the axis. The heat from the hot end of the first magnetic regenerator (5) is transferred to the cold end of the second magnetic regenerator (16), and the heat from the hot end of the second magnetic regenerator (16) is transferred to the cold end of the third magnetic regenerator (27), forming a superposition between the regenerators and expanding the operating temperature span of the system.

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