Magnetocaloric / inverse magnetocaloric effect testing device suitable for teaching and scientific research

Abstract

The utility model discloses a magnetocaloric / diamagnetocaloric effect testing device suitable for teaching and scientific research, relates to the technical field of solid refrigeration, and solves the problems that the conventional magnetocaloric / diamagnetocaloric effect testing device is single in function, cannot realize the simultaneous adjustment of testing temperature and measuring magnetic field, and cannot meet the testing requirements of different materials. The device comprises an electromagnet, a quartz tube, a programmable constant-temperature and constant-humidity chamber, a temperature sensor, an adjustable direct-current voltage-stabilizing source and a gauss meter, wherein the electromagnet is arranged in the programmable constant-temperature and constant-humidity chamber; a quartz tube is arranged between two pole heads of the electromagnet, and a sample and a gauss meter probe are arranged in the quartz tube; a temperature sensor is arranged on the sample; and the electromagnet is connected with the adjustable direct-current voltage-stabilizing source. According to the utility model, the test temperature and the magnetic field can be adjusted, continuous and discontinuous measurement schemes can be realized, and the device can be simultaneously suitable for measurement of magnetocaloric / inverse magnetocaloric effects of a first-stage phase change material and a second-stage phase change material.

Description

TECHNICAL FIELD

[0001] The utility model relates to solid refrigeration technical field, concretely is a kind of magnetocaloric effect / anti-magnetocaloric effect testing device suitable for teaching scientific research. BACKGROUND

[0002] Magnetocaloric effect is a phenomenon that material shows reversible thermal change in response to the change (Δμ0H) of external magnetic field. Generally, entropy in magnetic material system is composed of three parts, i.e. magnetic entropy (ΔS mag ), lattice vibration entropy (ΔS at ) and electronic entropy (ΔS e ). Magnetic entropy, lattice vibration entropy and electronic entropy respectively describe the disorder degree of magnetic system, atomic vibration system and electronic system. In adiabatic magnetization process, total entropy is constant. However, due to the application of external magnetic field, the disorder degree of magnetic spin is reduced, so that magnetic entropy is reduced. In order to keep total entropy unchanged, lattice vibration entropy and electronic entropy are increased, which makes the material temperature rise, and the superposition of the two makes the system temperature rise. When the heat of the system is dissipated, adiabatic demagnetization makes the magnetic entropy recover, which reduces the temperature of the material. Magnetocaloric effect usually occurs in gadolinium, lanthanum iron silicon, nickel manganese base, iron rhodium base alloy and other materials.

[0003] There is also anti-magnetocaloric effect corresponding to the above phenomenon, i.e. the material cools down when magnetized and heats up when demagnetized. For example, nickel manganese tin base, nickel manganese indium base, nickel manganese antimony base alloy and gallium garnet, when they are converted from paramagnetic / antiferromagnetic martensite phase to ferromagnetic austenite phase under the action of magnetic field, the absolute value of heat absorbed by structural phase change is greater than the absolute value of heat released by ferromagnetic phase change, so the net temperature of the system decreases with the magnetization of the sample.

[0004] By using magnetocaloric effect (or anti-magnetocaloric effect), solid refrigeration technology can be realized. This technology is clean and environmentally friendly, high in efficiency, and helps to cope with global climate warming and energy crisis. Magnetocaloric effect / anti-magnetocaloric effect can be obtained by direct method and indirect method, the direct method is to directly measure adiabatic temperature change (ΔT ad ), and the indirect method is to obtain magnetic entropy change value (ΔS m ) by calculation.

[0005] However, the current magnetocaloric effect / anti-magnetocaloric effect testing device has single function, cannot realize simultaneous adjustment of test temperature and measured magnetic field, and cannot match the test requirements of different materials. INVENTION CONTENTS

[0006] The utility model discloses a kind of magnetic heat / anti-magnetic heat effect test devices of adjustable temperature and magnetic field, and the device can be applied to teaching research and other application scenarios.The utility model can realize two kinds of measurement scheme of continuous and discontinuous, and can be suitable for the measurement of first-order phase change material and second-order phase change material magnetic heat / anti-magnetic heat effect simultaneously.

[0007] The utility model discloses a kind of magnetic heat / anti-magnetic heat effect test devices suitable for teaching research, specifically includes electromagnet, quartz tube, programmable constant temperature and humidity chamber, temperature sensor, adjustable DC regulated power supply and gauss meter, electromagnet is set in programmable constant temperature and humidity chamber;Quartz tube is placed between the two pole heads of electromagnet, sample and the probe of gauss meter are placed in quartz tube inside;Temperature sensor is arranged on sample;Electromagnet and adjustable DC regulated power supply are connected.

[0008] Further, temperature recorder is further included, and temperature recorder is connected with temperature sensor.

[0009] Further, the temperature sensor is thermocouple or platinum resistance.

[0010] Further, 220V AC power supply is further included, and 220V AC power supply is connected with adjustable DC regulated power supply and gauss meter respectively.

[0011] Further, the electromagnet includes core and helmholtz coil, and helmholtz coil is wound on core.

[0012] The utility model discloses a kind of magnetic heat / anti-magnetic heat effect test devices suitable for teaching research, and beneficial effects are as follows:

[0013] (1) the utility model discloses a kind of magnetic heat / anti-magnetic heat effect test devices suitable for teaching research, solve the current magnetic heat / anti-magnetic heat effect test device function single, cannot realize test temperature and measurement magnetic field simultaneous regulation, cannot match different material test demand problem, adjustable DC regulated power supply and electromagnet are connected, high gauss meter is simultaneously arranged in the center area of electromagnet pole head, can be adjusted and measured respectively to magnetic field intensity;Sample surface temperature is measured by temperature sensor.

[0014] (2) the utility model discloses a kind of magnetic heat / anti-magnetic heat effect test devices suitable for teaching research, sample is placed in quartz tube inside, to avoid the direct contact of sample and pole head in magnetization process. DRAWINGS

[0015] The accompanying drawings, which form part of this application, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0016] In the attached diagram:

[0017] Figure 1 This is a schematic diagram of the structure of a magnetocaloric / reverse magnetocaloric effect testing device suitable for teaching and scientific research, as described in this utility model.

[0018] Figure 2 This utility model describes a magnetocaloric / reverse magnetocaloric effect testing device suitable for teaching and research. Figure 1 A magnified view of a section at point A in the middle;

[0019] Figure 3 This utility model describes a magnetocaloric / reverse magnetocaloric effect testing device suitable for teaching and scientific research, which uses a continuous and discontinuous measurement scheme to measure the adiabatic temperature change value of a nickel-manganese-tin-cobalt alloy.

[0020] Among them: 1-Helmholtz coil, 2-quartz tube, 3-sample, 4-programmable constant temperature and humidity chamber, 5-temperature sensor, 6-temperature recorder, 7-adjustable DC regulated power supply, 8-gaussmeter. Detailed Implementation

[0021] The technical solution of this invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of, and not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0022] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0023] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integral connection, it can be mechanical connection, or electrical connection, it can be direct connection, or indirect connection through intermediate medium, or internal connection of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0024] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as there is no conflict between them.

[0025] Specific implementation method one: see Figures 1-3 Specifically, the magnetic heating / reverse magnetic heating effect testing device suitable for teaching and scientific research comprises an electromagnet, a quartz tube 2, a programmable constant temperature and humidity box 4, a temperature sensor 5, an adjustable DC voltage source 7 and a gauss meter 8. The electromagnet, the quartz tube 2, the sample 3 and the probe of the gauss meter 8 are arranged in the programmable constant temperature and humidity box 4, and the temperature of the test environment is adjusted by the programmable constant temperature and humidity box 4. The air gap between the pole heads of the two electromagnets is provided with the quartz tube 2, and the quartz tube 2 is installed in the central region of the pole head. The outer diameter of the quartz tube 2 is 5 mm. The sample 3 is arranged in the quartz tube 2 to avoid direct contact between the sample 3 and the pole head during magnetization. The temperature sensor 5 is arranged on the sample 3 and is attached to the surface of the sample 3 by silver glue. The temperature sensor 5 is a thermocouple or a platinum resistance. The electromagnet is connected with the adjustable DC voltage source 7, the magnetic field strength generated by the electromagnet is adjusted by the adjustable DC voltage source 7, and the magnetic field strength is measured by the gauss meter 8.

[0026] The temperature recorder 6 is further included, and the temperature recorder 6 is connected with the temperature sensor 5 to record the temperature of the sample 3.

[0027] The 220V AC power supply is further included, and the 220V AC power supply is connected with the adjustable DC voltage source 7 and the gauss meter 8 respectively.

[0028] The electromagnet comprises a core and a Helmholtz coil 1, and the Helmholtz coil 1 is wound on the core.

[0029] A testing method using the above magnetic heating / reverse magnetic heating effect testing device comprises the following steps:

[0030] Step one, fixing the temperature sensor 5. In order to improve the sensitivity of the test, the platinum resistance or thermocouple is usually attached to the surface of the sample 3 by silver glue, or the temperature sensor 5 is directly welded on the surface of the sample 3 by soldering. Then, the platinum resistance or thermocouple is connected with the temperature recorder 6;

[0031] Step two, install sample 3. According to the size of sample 3 and temperature sensor 5, select the appropriate size of quartz tube 2. The sample 3 can be just put into the inner diameter of the quartz tube 2. Then, adjust the air gap of the electromagnet pole head, and clamp or paste the quartz tube 2 between the two pole heads. The reason for choosing to install the sample 3 inside the quartz tube 2 is that the sample 3 is easy to contact the pole head during magnetization, thereby affecting the measurement results.

[0032] Step three, determine the applied magnetic field. Insert gauss meter 8 into quartz tube 2, and control the magnetic field strength by adjusting the output current of adjustable DC voltage source 7.

[0033] Step four, select the measurement scheme. The device can realize two measurement schemes: one is continuous measurement scheme. That is, under the temperature rising and falling rate of 0.1-0.2K / min, the real-time temperature change of the surface of sample 3 is monitored by temperature recorder 6. When the surface temperature of sample 3 reaches the set temperature, the adjustable DC voltage source 7 is turned on to apply a magnetic field, and the data of the surface temperature change of sample 3 is obtained. In order to ensure the test accuracy, the adiabatic temperature change measurement is usually selected at intervals of 1K or 2K. The second is the non-continuous measurement scheme. That is, before testing, the sample 3 is cooled or heated to a certain temperature and kept for 5-10min. Then, the sample 3 is heated or cooled to the set temperature at a rate of 0.1-0.2K / min. At this time, the magnetic field is applied again to monitor the change of the surface temperature of sample 3. In order to ensure the test accuracy, the adiabatic temperature change measurement is usually selected at intervals of 1K or 2K.

[0034] For first-order phase change materials, such as nickel-manganese-based alloys (including nickel-manganese-tin, nickel-manganese-antimony, nickel-manganese-gallium, nickel-manganese-indium), etc., due to the inherent thermal hysteresis of the material during phase change, in order to monitor the more optimal temperature change, the non-continuous measurement scheme is usually selected. For second-order phase change materials, such as gadolinium, lanthanum iron silicon, etc., due to the strong reversibility of phase change, the continuous measurement scheme can be directly selected.

[0035] The specific test process of the magnetic heat / reverse magnetic heat effect test device suitable for teaching and scientific research is explained as follows:

[0036] Taking a nickel-manganese-tin-cobalt alloy with a martensitic phase change end temperature of 260K as an example, the alloy can undergo martensite to austenite transformation under the action of a magnetic field, thereby exhibiting reverse magnetic heat effect. Two measurement schemes, continuous measurement and non-continuous measurement, are used respectively:

[0037] (1) Continuous measurement. First, adjust the programmable constant temperature and humidity chamber 4, and first reduce the temperature of the sample 3 surface to 238K, and keep it for 5 min, so that the alloy is completely transformed into martensite. Then, slowly increase the temperature at a rate of 0.12K / min to simulate isothermal conditions. When the test temperature is 268K, apply a magnetic field and record the temperature change of the sample surface. By reading the temperature difference of the sample surface before and after the magnetic field is applied, the ΔT ad value of the sample at that temperature can be obtained. In order to ensure the accuracy of the test, a group of data is selected for every 2K interval. Figure 3 The hollow heart dot is the adiabatic temperature change value of the selected nickel-manganese-tin-cobalt alloy measured at a magnetic field of 1.38T and a temperature range of 270-310K.

[0038] (2) Non-continuous measurement. First, adjust the programmable constant temperature and humidity chamber 4, and first reduce the temperature of the sample 3 surface to 238K, and keep it for 5 min, so that the alloy is completely transformed into martensite. Then, slowly increase the temperature at a rate of 0.12K / min to simulate isothermal conditions. When the test temperature is 290K, apply a magnetic field and record the temperature change of the sample surface. By reading the temperature difference of the sample 3 surface before and after the magnetic field is applied, the ΔT ad value of the sample at that temperature can be obtained. Next, continue to adjust the constant temperature and humidity chamber, and reduce the temperature of the sample surface to 238K, and keep it for 5 min, so that the alloy is completely restored to martensite. Then, slowly increase the temperature at a rate of 0.12K / min to 292K, apply a magnetic field, and record the temperature change of the sample surface. In this way, a group of data is tested every 2K interval (when the temperature is 298-300K, the measurement interval is 1K). Figure 3 The solid center dot is the adiabatic temperature change value of the selected nickel-manganese-tin-cobalt alloy measured at a magnetic field of 1.38T and a temperature range of 290-302K.

[0039] In summary of the above implementation cases, the magnetic heating / reverse magnetic heating effect testing device suitable for teaching and scientific research solves the problems of single function of the current magnetic heating / reverse magnetic heating effect testing device, inability to simultaneously adjust the test temperature and the measurement magnetic field, and inability to match different material testing requirements. The adjustable DC voltage source 7 is connected with the electromagnet, and the gauss meter 8 is arranged in the center area of the pole head, so as to respectively realize adjustment and measurement of the magnetic field strength; and the temperature of the sample surface is measured by the temperature sensor 5. The magnetic heating / reverse magnetic heating effect testing device suitable for teaching and scientific research places the sample 3 in the quartz tube 2 to avoid direct contact between the sample and the pole head during magnetization.

[0040] The above-described specific embodiments further specifically describe the purposes, technical solutions and beneficial effects of the present application. It should be understood that the above-described specific embodiments are merely examples of the present application and are not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A magnetocaloric / reverse magnetocaloric effect testing device suitable for teaching and research, characterized in that: The device includes an electromagnet, a quartz tube (2), a programmable constant temperature and humidity chamber (4), a temperature sensor (5), an adjustable DC power supply (7), and a gaussmeter (8). The electromagnet is placed inside the programmable constant temperature and humidity chamber (4). A quartz tube (2) is placed between the two poles of the electromagnet. The sample (3) and the probe of the gaussmeter (8) are placed inside the quartz tube (2). A temperature sensor (5) is placed on the sample (3). The electromagnet is connected to the adjustable DC power supply (7). The electromagnet includes two Helmholtz coils (1).

2. The magnetocaloric / reverse magnetocaloric effect testing device according to claim 1, characterized in that: It also includes a temperature recorder (6), and the temperature recorder (6) and temperature sensor (5) are connected.

3. The magnetocaloric / reverse magnetocaloric effect testing device according to claim 2, characterized in that: The temperature sensor (5) is a thermocouple or a platinum resistance thermometer.

4. The magnetocaloric / reverse magnetocaloric effect testing device according to claim 1, characterized in that: It also includes a 220V AC power supply, which is connected to an adjustable DC voltage regulator (7) and a gaussmeter (8).

5. The magnetocaloric / reverse magnetocaloric effect testing device according to claim 1, characterized in that: The electromagnet also includes an iron core on which a Helmholtz coil (1) is wound (on the iron core).

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