Room temperature magnetic refrigeration demonstration instrument based on magnetothermal effect and use method thereof

Abstract

The invention discloses a room temperature magnetic refrigeration demonstration instrument based on a magnetothermal effect and a use method thereof. A magnetizer and a magnetic field controller are electrically connected, the magnetizer is provided with a magnetic field test module, the top of the magnetizer is provided with a manual rocking handle, the middle part of the magnetizer is provided with an electromagnet magnetic field space, and the upper and lower parts of the electromagnet magnetic field space are provided with pole heads; the magnetizing time control module controls the action time of the magnetic field action module; the electromagnet magnetic field space is used for placing a magnetic refrigeration working medium; the manual rocking handle is used for fixing the magnetic refrigeration working medium; the magnetic field test module is a millteslameter, and the temperature control module is composed of a heating table and a non-metal thermal insulation layer; the temperature testing module is a temperature sensor; the adiabatic temperature change of the tested magnetic refrigeration working medium along with the application and revocation of the external magnetic field is visually displayed through a temperature sensor and a millteslameter. The demonstration instrument is low in cost, simple and convenient to operate and visual in demonstration mode, and the design pays attention to safety and environmental friendliness.

Description

Technical Field

[0001] The present invention relates to the technical field of a room-temperature magnetic refrigeration demonstrator based on the magnetocaloric effect and its usage method, and specifically refers to a room-temperature magnetic refrigeration demonstrator based on the magnetocaloric effect and its usage method. Background Art

[0002] The magnetocaloric effect refers to the phenomenon that the temperature of a magnetic material changes under adiabatic conditions by applying or removing an external magnetic field, which is the basis of magnetic refrigeration technology. The magnetic refrigeration technology based on the magnetocaloric effect, compared with the traditional gas compression refrigeration technology, has the advantages of high efficiency, energy conservation, environmental friendliness, and small volume because it applies and removes a magnetic field to a solid-state refrigerant and its efficiency can reach 30 - 60% of the Carnot cycle, and thus is very promising to become a new generation of refrigeration technology.

[0003] Currently, the mainstream characterization means of the magnetocaloric effect on the market mainly use imported foreign instruments such as a comprehensive physical property measurement system (PPMS) and a magnetic measurement system (MPMS). The purchase cost is extremely high (> 4 million yuan), so it is not suitable as a tool for physical experiment teaching and popular science demonstration work. The development of components such as superconducting magnets and fine measurements used in them as high-precision technologies has not yet been tackled and mass-produced in China.

[0004] Taking the measurement of the magnetocaloric effect of magnetic materials by a physical property measurement system (PPMS) as an example, its characterization method mainly indirectly measures data such as its isothermal magnetization curve and specific heat capacity, and obtains parameters such as the magnetic entropy change |ΔS M |, adiabatic temperature change ΔT ad , refrigeration capacity RC, etc. through further data processing and calculation, so as to further measure the magnitude of the magnetocaloric effect, but the measurement results are not so intuitive. Summary of the Invention

[0005] The purpose of the present invention is to provide a room-temperature magnetic refrigeration demonstrator based on the magnetocaloric effect and its usage method to solve the problems raised in the above background art.

[0006] To solve the above technical problems, the present invention provides the following technical solutions:

[0007] A room-temperature magnetic refrigeration demonstrator based on the magnetocaloric effect of the present invention includes a magnetizer and a magnetic field controller which are electrically connected. The magnetizer is provided with a magnetic field test module. A manual crank is provided at the top of the magnetizer, and an electromagnet magnetic field space is provided in the middle of the magnetizer. Pole heads are provided above and below the electromagnet magnetic field space. The magnetic field controller is provided with a magnetizing pedal, a magnetizing time control module, and a magnetic field control module which are electrically connected;

[0008] The magnetic field control module utilizes the principle of electromagnetic induction to achieve rapid magnetization and demagnetization, thereby controlling the magnitude of the magnetic field; the magnetization time control module controls the magnetic field action time of the magnetic field control module. The electromagnetic iron magnetic field space is used to place the magnetic refrigeration working medium, and the magnetic refrigeration working medium is placed between two pole heads. The manual crank is used to control the lifting of the upper pole head to clamp the magnetic refrigeration working medium, and the lower pole head is fixed. The magnetic field test module is a millitesla meter, and the millitesla meter is arranged in the electromagnetic iron magnetic field space;

[0009] It further includes a temperature test module and a temperature control module. The temperature control module is composed of a heating table and a non-metallic heat insulation layer; the temperature test module is a temperature sensor, which is used to directly measure the temperature of the magnetic refrigeration working medium; through the temperature sensor and the millitesla meter, the adiabatic temperature change of the measured magnetic refrigeration working medium with the application and cancellation of the external magnetic field is intuitively displayed.

[0010] As an improvement, the magnetizer further includes a sample heat insulation component, and the manual crank is arranged at the top of the column sleeve.

[0011] A usage method of a room temperature magnetic refrigeration demonstrator based on the magnetocaloric effect includes the following operation steps:

[0012] S1. Place the magnetic refrigeration working medium into the electromagnetic iron magnetic field space of the demonstrator, and connect it to the magnetic field test module and the temperature test module;

[0013] S2. Rotate the manual crank to fix the magnetic refrigeration working medium in the electromagnetic iron magnetic field space, and test the initial temperature and magnetic field of the magnetic refrigeration working medium;

[0014] S3. Apply an external magnetic field to the magnetic refrigeration working medium, and cancel the magnetic field after a certain time. Observe and record the changes in the magnetic field and temperature of the magnetic refrigeration working medium in the temperature test module and the magnetic field test module; repeat this process by changing the initial temperature.

[0015] As an improvement, in step S1, the magnetic refrigeration working medium is Gd metal.

[0016] As an improvement, the Gd metal is 700 g.

[0017] As an improvement, in step S2, the initial temperature is 299 K.

[0018] As an improvement, in step S3, the external magnetic field is 2 tesla.

[0019] As an improvement, in step S3, the application time of the external magnetic field is 100 s.

[0020] As an improvement, in step S3, the observation and recording time is 3 min.

[0021] The advantages of the present invention compared with the prior art are:

[0022] This demonstrator has a low cost and is easy to operate. It helps to improve the public's understanding and interest in the magnetocaloric effect. It can be used in higher education institutions and science and technology exhibition halls to support the physical experiment teaching and popular science demonstration work of the magnetocaloric effect and magnetic refrigeration, etc. It is an efficient and practical tool.

[0023] This demonstrator has an intuitive demonstration method. By measuring the adiabatic temperature change of the magnetic refrigeration working medium under a variable magnetic field, users can very intuitively see the temperature change of the object under test when the magnetic field is applied and withdrawn, and can intuitively experience and learn the magnetocaloric effect, thereby deepening the understanding of this physical phenomenon and effectively making up for the demonstration shortcoming of the magnetocaloric effect in the teaching field.

[0024] The design of this demonstrator pays attention to safety and environmental friendliness. It does not use high-GWP (Global Warming Potential) refrigerants, has low energy consumption, and conforms to the concept of sustainable development and relevant national policies such as energy conservation and carbon reduction. Brief Description of the Drawings

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the description of the embodiments or the prior art. Obviously, the following listed drawings are only some structural schematic diagrams of the present invention, rather than all of them.

[0026] Figure 1 It is a structural schematic diagram of the magnetizer of a room-temperature magnetic refrigeration demonstrator based on the magnetocaloric effect of the present invention Figure 1 .

[0027] Figure 2 It is a graph of the variation of temperature and external magnetic field with time under different initial states in Embodiment 1 of the present invention and a graph of the variation of the maximum adiabatic temperature change |ΔT max | with the initial temperature.

[0028] Figure 3 It is a data comparison graph of the magnetic entropy change -ΔS of Gd under a magnetic field of 20 kOe (2 T) in Embodiment 1 of the present invention m and the maximum temperature difference |ΔT max |.

[0029] Figure 4 It is a graph of the adiabatic temperature change ΔT of Gd metal and the control group of Cu, Fe, and Al metals under the change of rising and falling magnetic fields near room temperature in Embodiment 2 of the present invention.

[0030] Figure 5It is the graph of the temperature change over time generated by three magnetic refrigerants in Embodiment 3 of the present invention (Gd metal and two other typical room-temperature magnetic refrigeration materials (LaFe11.4Si1.6, Ni54Mn23Ga23)) and the control group of Cu, Fe, and Al metals under the same variable magnetic field condition, as well as the maximum temperature difference |ΔT generated by the six test materials max |Comparison graph.

[0031] Figure 6 It is the structural schematic of the magnetizer of a room-temperature magnetic refrigeration demonstrator based on the magnetocaloric effect of the present invention Figure 2 。

[0032] Figure 7 It is the structural schematic of the magnetic field controller of a room-temperature magnetic refrigeration demonstrator based on the magnetocaloric effect of the present invention Figure 1 。

[0033] Figure 8 It is the structural schematic of the magnetic field controller of a room-temperature magnetic refrigeration demonstrator based on the magnetocaloric effect of the present invention Figure 2 。

[0034] Reference numerals:

[0035] Magnetizer 1; Magnetic field controller 2; Magnetic field test module 3; Temperature test module 4; Manual crank 5; Electromagnet magnetic field space 6; Pole head 7; Magnetization pedal 8; Magnetization time control module 9; Magnetic field control module 10; Bush 11. Detailed implementation manners

[0036] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0037] In the description of the embodiments of the present invention, it should be noted that if terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. appear, the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the invention product is usually placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0038] In addition, if terms such as "first", "second", "third", etc. appear, they are only used for distinguishing descriptions and cannot be construed as indicating or implying relative importance. If terms such as "horizontal", "vertical", "hanging", etc. appear, it does not mean that the components are required to be absolutely horizontal or hanging, but they can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and it does not mean that the structure must be completely horizontal, but it can be slightly inclined.

[0039] In the description of the embodiments of the present invention, if the terms "a plurality of" or "several" appear, they represent at least two.

[0040] In the description of the embodiments of the present invention, it should also be noted that unless otherwise clearly specified and limited, if terms such as "arranged", "installed", "connected", "coupled" are used, they should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] This embodiment combines the attached Figures 1 to 8 to elaborate in detail on a room-temperature magnetic refrigeration demonstrator based on the magnetocaloric effect and its usage method.

[0042] A room-temperature magnetic refrigeration demonstrator based on the magnetocaloric effect in this embodiment includes a magnetizer 1 and a magnetic field controller 2 that are electrically connected. The magnetizer 1 is provided with a magnetic field test module 3. A manual crank 5 is provided at the top of the magnetizer 1. An electromagnetic field space 6 is provided in the middle of the magnetizer 1. Pole heads 7 are provided above and below the electromagnetic field space 6. The magnetic field controller 2 is provided with a magnetizing pedal 8, a magnetization time control module 9, and a magnetic field control module 10 that are electrically connected;

[0043] The magnetic field control module 10 utilizes the principle of electromagnetic induction to achieve rapid magnetization and demagnetization, thereby controlling the magnitude of the magnetic field. The magnetization time control module 9 controls the magnetic field action time of the magnetic field control module 10. The electromagnetic field space 6 is used to place the magnetic refrigeration working medium. The magnetic refrigeration working medium is placed between the two pole heads 7. The manual crank is used to control the lifting of the upper pole head 7 to clamp the magnetic refrigeration working medium, and the lower pole head 7 is fixed. The magnetic field test module 3 is a millitesla meter, and the millitesla meter is provided in the electromagnetic field space;

[0044] It also includes a temperature test module 4 and a temperature control module. The temperature control module consists of a heating table and a non-metallic heat insulation layer. The temperature test module 4 is a temperature sensor for directly measuring the temperature of the magnetic refrigeration working medium. The adiabatic temperature change of the measured magnetic refrigeration working medium with the application and cancellation of the external magnetic field is visually demonstrated through the temperature sensor and the millitesla meter.

[0045] The magnetizer 1 also includes a sample heat insulation component, and the manual crank 5 is arranged at the top of the column sleeve 11.

[0046] A usage method of a room-temperature magnetic refrigeration demonstrator based on the magnetocaloric effect includes the following operation steps:

[0047] S1. Place the magnetic refrigeration working medium into the electromagnetic field space 6 of the demonstrator, and connect it to the magnetic field test module 3 and the temperature test module 4.

[0048] S2. Rotate the manual crank 5 to fix the magnetic refrigeration working medium in the electromagnetic field space 6, and test the initial temperature and magnetic field of the magnetic refrigeration working medium.

[0049] S3. Apply an external magnetic field to the magnetic refrigeration working medium, cancel the magnetic field after a certain time, and observe and record the changes in the magnetic field and temperature of the magnetic refrigeration working medium in the temperature test module 4 and the magnetic field test module 3. Repeat this process by changing the initial temperature.

[0050] In step S1, the magnetic refrigeration working medium is Gd metal.

[0051] The Gd metal is 700 g.

[0052] In step S2, the initial temperature is 299 K.

[0053] In step S3, the external magnetic field is 2 tesla.

[0054] In step S3, the application time of the external magnetic field is 100 s.

[0055] In step S3, the observation and recording time is 3 min.

[0056] Example 1

[0057] In specific implementation, as Figure 2 shown, this example adopts comparing the adiabatic temperature change of Gd metal at different temperatures, and its measurement operation method is carried out according to the following specific steps:

[0058] (1) Control the temperature of Gd metal with tools such as a magnetic heating stirrer, wrap Gd metal with different initial temperatures with a non-metallic sample heat insulation bag and put it into the electromagnetic field region, and connect the temperature sensor and the portable millitesla meter to the Gd block.

[0059] (2) Rotate the control crank of the demonstration instrument to fix the Gd block within the electromagnet region, and measure and record the initial external magnetic field strength of the Gd metal.

[0060] (3) Apply a magnetic field to the electromagnet region using the principle of electromagnetic induction, and observe and record the changes in the external magnetic field and temperature of the Gd metal.

[0061] (4) Plot and analyze the recorded data.

[0062] The graphs of the temperature and external magnetic field of Gd versus time at the initial states of 288.8 K (a), 300.5 K (b), and 305.5 K (c), and the graph of the maximum adiabatic temperature change |Δmax| of Gd versus the initial temperature (d) are shown in Figure 2 , and the data of the maximum temperature difference |Δmax| of Gd varying with the initial temperature T0 under a 2T magnetic field change are compared with the magnetic entropy change -ΔSm measured and calculated using a comprehensive physical property measurement system, as shown in Figure 3 , and it is found that both show a downward trend with temperature, further verifying that the data of the maximum temperature difference |Δmax| obtained in this experimental project can well describe and demonstrate the magnetocaloric effect and magnetic refrigeration effect of the material.

[0063] Example 2

[0064] In specific implementation, as Figure 3 shown, this example uses the adiabatic temperature changes of Gd metal, Cu, Fe, and Al metals under the change of rising and falling magnetic fields near room temperature, and the measurement operation method is carried out according to the following specific steps:

[0065] (1) Wrap the Gd, Cu, Fe, and Al metals near room temperature with non-metallic sample insulation bags and place them in the electromagnet region, and connect the temperature sensor and the portable millitesla meter to the metal blocks.

[0066] (2) Rotate the control crank of the demonstration instrument to fix the metal blocks within the electromagnet region, and measure and record the initial external magnetic field strength of the metal blocks.

[0067] (3) Apply a magnetic field to the electromagnet region using the principle of electromagnetic induction, and observe and record the changes in the external magnetic field and temperature of different metal blocks.

[0068] (4) Plot and analyze the recorded data.

[0069] The graph of the adiabatic temperature change ΔT of Gd, Cu, Fe, and Al metals under the change of rising and falling magnetic fields near room temperature is shown in Figure 4 , during the rapid rise and rapid fall of the magnetic field, the temperature of Gd also suddenly rises and suddenly falls, and the maximum temperature difference reaches |Δmax| = 4.4 K. Figure 4(b)-(c) show the adiabatic temperature change data of metal materials Cu, Fe, and Al as control groups under the same experimental conditions. The temperature changes generated by the latter three in the changing magnetic field are not obvious, being 0.3K, 1.1K, and 0.6K respectively, which are much smaller than those of the traditional room-temperature magnetic refrigeration material Gd metal.

[0070] Example 3

[0071] In specific implementation, as Figure 4 shown, this example adopts the adiabatic temperature change of Gd metal, two other typical room-temperature magnetic refrigeration materials (LaFe11.4Si1.6, Ni54Mn23Ga23), and control group Cu, Fe, and Al metals under the rising and falling magnetic field changes near room temperature. The measurement operation method is carried out according to the following specific steps:

[0072] (1) Wrap six kinds of metals near room temperature with non-metallic sample insulation bags and place them in the electromagnet area. Connect the temperature sensor and the portable millitesla meter to the metal blocks.

[0073] (2) Rotate the control crank of the demonstrator to fix the metal blocks in the electromagnet area, and measure and record the initial external magnetic field strength of the metal blocks.

[0074] (3) Apply a magnetic field to the electromagnet area using the principle of electromagnetic induction, and observe and record the changes in the external magnetic field and temperature of the metal blocks.

[0075] (4) Plot and analyze the recorded data.

[0076] Figure 5 shows the change of temperature with time (a) generated by six test materials under the same variable magnetic field condition and the comparison of the maximum temperature difference |Δmax| generated by six test materials (b). By statistically analyzing the maximum temperature difference values |Δmax| of the six materials, it is obvious that the maximum temperature difference |Δmax| of Gd is the largest among the six materials, being 4.4K, indicating that the magnetocaloric effect and magnetic refrigeration performance of Gd are the most excellent under room-temperature conditions.

[0077] From the above results, it can be seen that the operation method in the present invention does not use any special equipment. Therefore, this method is simple and efficient, suitable for large-scale production, and has high economic value.

[0078] The present invention and its implementation manners have been described above. Such description is not restrictive, and the actual protection scope is not limited thereto. Any changes or substitutions that can be easily thought of by any person skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claimed rights.

Claims

1. A room-temperature magnetic refrigeration demonstrator based on the magnetocaloric effect, characterized in that It includes a magnetizer (1) and a magnetic field controller (2) which are electrically connected. The magnetizer (1) is provided with a magnetic field test module (3). A manual crank (5) is provided at the top of the magnetizer (1). An electromagnet magnetic field space (6) is provided in the middle of the magnetizer (1). Pole heads (7) are provided above and below the electromagnet magnetic field space (6). The magnetic field controller (2) is provided with a magnetizing pedal (8), a magnetizing time control module (9), and a magnetic field control module (10) which are electrically connected. The magnetic field control module (10) uses the principle of electromagnetic induction to achieve rapid magnetization and demagnetization, thereby controlling the magnitude of the magnetic field. The magnetizing time control module (9) controls the magnetic field action time of the magnetic field control module (10). The electromagnet magnetic field space (6) is used to place the magnetic refrigeration working medium. The magnetic refrigeration working medium is placed between the two pole heads (7). The manual crank is used to control the lifting of the upper pole head (7) to clamp the magnetic refrigeration working medium, and the lower pole head (7) is fixed. The magnetic field test module (3) is a millitesla meter, and the millitesla meter is provided in the electromagnet magnetic field space. It further includes a temperature test module (4) and a temperature control module. The temperature control module is composed of a heating table and a non-metallic heat insulation layer. The temperature test module (4) is a temperature sensor, which is used to directly measure the temperature of the magnetic refrigeration working medium. The adiabatic temperature change of the measured magnetic refrigeration working medium with the application and cancellation of the external magnetic field is visually displayed through the temperature sensor and the millitesla meter.

2. The room-temperature magnetic refrigeration demonstrator based on the magnetocaloric effect according to claim 1, characterized in that, The magnetizer (1) further includes a sample heat insulation component. The manual crank (5) is provided at the top of the column sleeve (11).

3. The method of using a room-temperature magnetic refrigeration demonstrator based on the magnetocaloric effect according to claim 1, characterized in that, It includes the following operation steps: S1. Place the magnetic refrigeration working medium into the electromagnet magnetic field space (6) of the demonstrator, and connect it to the magnetic field test module (3) and the temperature test module (4). S2. Rotate the manual crank (5) to fix the magnetic refrigeration working medium in the electromagnet magnetic field space (6), and test the initial temperature and magnetic field of the magnetic refrigeration working medium. S3. Apply an external magnetic field to the magnetic refrigeration working medium, and cancel the magnetic field after a certain time. Observe and record the changes in the magnetic field and temperature of the magnetic refrigeration working medium in the temperature test module (4) and the magnetic field test module (3). Repeat this process by changing the initial temperature.

4. The usage method of a room-temperature magnetic refrigeration demonstrator based on the magnetocaloric effect according to claim 2, characterized in that, In the step S1, the magnetic refrigeration working medium is Gd metal.

5. The usage method of a room-temperature magnetic refrigeration demonstrator based on the magnetocaloric effect according to claim 3, characterized in that, The Gd metal is 700 g.

6. The usage method of a room-temperature magnetic refrigeration demonstrator based on the magnetocaloric effect according to claim 2, characterized in that In the step S2, the initial temperature is 299 K.

7. The method for using a room-temperature magnetic refrigeration demonstrator based on the magnetocaloric effect according to claim 2, characterized in that, In the step S3, the external magnetic field is 2 tesla.

8. The method for using a room-temperature magnetic refrigeration demonstrator based on the magnetocaloric effect according to claim 2, characterized in that, In the step S3, the application time of the external magnetic field is 100 s.

9. The method for using a room-temperature magnetic refrigeration demonstrator based on the magnetocaloric effect according to claim 2, characterized in that, In the step S3, the observation and recording time is 3 min.

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