Magnetic fluid thermal switch and heat conduction control method

Abstract

The application relates to a magnetic fluid heat switch and a heat conduction control method, and solves the technical problems that existing space observation equipment has large refrigeration difficulty, poor heat dissipation and large heat dissipation design difficulty. The application comprises a heat conduction mounting plate, a separation heat insulation pad, an annular heat insulation pad, a working area sealed cavity and a storage area sealed cavity; the heat conduction mounting plate and the separation heat insulation pad are connected to enclose the working area; the two ends of the working area are connected with the working area sealed cavity and the storage area sealed cavity through the annular heat insulation pad; the working area sealed cavity is provided with a working area sealed cavity which is communicated with the working area; the inner wall of the working area sealed cavity is provided with a working area coil protection layer and a working area magnetic coil; the storage area sealed cavity is provided with a storage area sealed cavity which is communicated with the working area; the inner wall of the storage area sealed cavity is provided with a storage area coil protection layer and a storage area magnetic coil; the remaining cavity part of the storage area sealed cavity constitutes a storage area, and the vacuum cavities in the storage area and the working area are filled with magnetic fluids.

Description

Technical Field

[0001] The invention relates to a thermal switch, in particular to a magnetic fluid thermal switch and a heat conduction control method. Background Art

[0002] With the increasing demand for in-depth research and development in space astronomical observation, observation missions require high sensitivity and wide fields of view. Because target signals are weak, observation instruments must possess high sensitivity and low noise. To reduce thermal noise interference, space optical camera detectors must be cooled to a low temperature. Heat from the detectors is then dissipated through heat sinks.

[0003] To capture target signals across a wide field of view, the space optical camera detector operates at a certain azimuth and elevation angle. This results in a high external solar heat flux reaching the heat sink under certain operating conditions, affecting the detector's cooling and heat dissipation, and thus the optical camera's detection performance. Simply increasing the heat sink area to meet the cooling temperature requirement is of limited effectiveness and can negatively impact satellite weight reduction and the fundamental frequency of the satellite's mechanical system.

[0004] As satellite payload functionality and performance requirements increase, the heat generated by electronic equipment onboard satellites is also increasing. The heat dissipation surfaces of the cabin panels in different directions are alternately exposed to the sun. While dissipating heat, the heat sink also absorbs solar radiation, which reduces its cooling effectiveness. Furthermore, satellite electronic equipment operates intermittently. When generating heat, thermal conductivity is required to dissipate heat, while heaters are required to prevent the electronics from cooling too low. This also places certain demands on heat dissipation design. Summary of the Invention

[0005] The purpose of the present invention is to solve the technical problems of existing space observation equipment such as difficulty in cooling, poor heat dissipation and difficulty in heat dissipation design, and to provide a magnetic fluid thermal switch and heat conduction control method.

[0006] The concept behind this invention is to use a thermal switch to control the on / off switching of the heat transfer path. Specifically, when the electronic device is turned off and not generating heat, the heat transfer path is closed, insulating the device. Specifically, a magnetic fluid thermal switch is designed. When the heat sink on one side is exposed to sunlight and the temperature rises, the switch inhibits heat transfer between that side and the heat-generating component. When the heat sink temperature drops to a certain level, the switch increases heat transfer between that side and the heat-generating component. This not only meets the cooling needs of the detector and electronic equipment, but also reduces the heat sink area, simplifying thermal and structural design.

[0007] In order to achieve the above objectives and realize the above concepts, the technical solutions provided by the present invention are as follows:

[0008] A magnetic fluid thermal switch, which is special in that:

[0009] It includes two heat-conducting mounting plates, two separate thermal insulation pads, two annular thermal insulation pads, a sealed cavity in the working area, and a sealed cavity in the storage area;

[0010] Two heat-conducting mounting plates are spaced apart, and two separation heat-insulating pads are relatively arranged in the space between the two heat-conducting mounting plates to enclose a working area;

[0011] The two ends of the working area are connected to the working area sealed cavity and the storage area sealed cavity respectively through annular thermal insulation pads;

[0012] The working area sealed cavity body is provided with a working area sealed cavity located inside thereof and a working area connecting port located on its surface, and the working area sealed cavity is connected with the working area through the working area connecting port; a working area coil protective layer and a working area magnetic coil are provided on the inner wall of the working area sealed cavity away from the working area connecting port;

[0013] The storage area sealed cavity body is provided with a storage area sealed cavity located therein and a storage area connection port located on the surface, and the storage area sealed cavity is connected to the working area through the storage area connection port; a storage area coil protective layer and a storage area magnetic coil are provided on the inner wall of the storage area sealed cavity away from the storage area connection port; the storage area magnetic coil includes a storage area center magnetic coil and at least one storage area edge magnetic coil; the storage area center magnetic coil is close to the storage area connection port, and the storage area edge magnetic coil is away from the storage area connection port;

[0014] The remaining cavity of the storage area sealed cavity constitutes the storage area, and the vacuum cavity in the storage area and the working area is filled with magnetic fluid; the working area magnetic coil is insulated from the magnetic fluid by the working area coil protective layer; the storage area magnetic coil is insulated from the magnetic fluid by the storage area coil protective layer;

[0015] The volume V1 of the magnetic fluid, the volume V2 of the storage area, and the volume V3 of the working area satisfy the following relationship:

[0016] V1 <V2+V3。

[0017] Furthermore, the working area magnetic coil is embedded in the working area coil protection layer; the surface of the working area coil protection layer facing the working area is smooth; the working area coil protection layer fills the working area sealed cavity, and the smooth surface of the working area coil protection layer is flush with the outer edge of the working area connection port;

[0018] The storage area magnetic coil is embedded in the storage area coil protection layer; the surface of the storage area coil protection layer facing the storage area is smooth.

[0019] Furthermore, the cross-sectional area of ​​the storage area sealed cavity parallel to the plane where the storage area connection port is located gradually increases from the storage area connection port toward the inside.

[0020] Furthermore, V1, V2 and V3 satisfy the relationship: V3 <V1<V2。

[0021] Furthermore, the storage area sealed cavity is a rectangular block structure, the storage area connection port is located at the center of one of its largest surfaces, and the plane where the storage area coil protection layer is located is arranged parallel to the largest surface; there are two storage area edge magnetic coils, which are located at both ends of the storage area coil protection layer, and the storage area center magnetic coil is located at the storage area coil protection layer corresponding to the storage area connection port position.

[0022] Furthermore, the separation thermal insulation pad is a T-shaped structure, with the bottom end of the T facing the working area and sandwiched between two heat-conducting mounting plates.

[0023] Furthermore, the inner surfaces of the heat-conducting mounting plate and the separation heat-insulating pad facing the working area are provided with a gold-plated film or a silver-plated film, and the film meets the condition: infrared emissivity is less than 0.1.

[0024] Furthermore, the thickness of the thermally conductive mounting plate is 1 mm;

[0025] The heat-conducting mounting plate, the separated heat-insulating pad and the annular heat-insulating pad are all connected by vacuum sealant;

[0026] Magnetic fluid is composed of magnetic metal particles mixed with filling liquid.

[0027] The present invention also provides a magnetic fluid heat conduction control method, which is special in that it includes the following steps:

[0028] S0, installing the above-mentioned magnetic fluid thermal switch at the target location, with two heat-conducting mounting plates corresponding to the two ports of the heat transfer path respectively;

[0029] S1, turn on thermal conduction mode

[0030] When heat conduction is required, currents I1, I2, and I3 are respectively passed through the central magnetic coil in the storage area, the edge magnetic coil in the storage area, and the magnetic coil in the working area, where I3>I1 and I2=0.

[0031] S2, conduct heat

[0032] Under the action of the magnetic field, the magnetic fluid flows into the working area;

[0033] When the magnetic fluid is waiting to flow into the working area or fill the working area, the magnetic fluid thermal switch is in the heat conduction mode; at this time, the thermal resistance between the heat conduction mounting plates on both sides of the working area is reduced due to the presence of magnetic fluid, and the temperature difference between the two sides is reduced;

[0034] S3, turn on heat insulation mode

[0035] When thermal insulation is required, currents I1, I2, and I3 are applied to the central magnetic coil in the storage area, the edge magnetic coil in the storage area, and the magnetic coil in the working area, respectively, where I2>I1 and I3=0.

[0036] S4, perform thermal insulation

[0037] Under the action of the magnetic field, the magnetic fluid flows into the storage area;

[0038] While waiting for the magnetic fluid to flow into the storage area or fill the storage area, the magnetic fluid thermal switch is in the insulation mode; at this time, the thermal resistance between the heat-conducting mounting plates on both sides of the working area increases due to the vacuum, and the temperature difference on both sides increases, thereby realizing the thermal control of the magnetic fluid.

[0039] Furthermore, after step S2 is completed and heat conduction is performed, the method further includes:

[0040] A. Thermal conductivity and energy saving

[0041] The power supply mode of the magnetic coil in the center of the storage area, the magnetic coil at the edge of the storage area and the magnetic coil in the working area is changed to intermittent power supply so that the following conditions are met: the magnetic fluid does not flow back;

[0042] After step S4 is completed and the heat insulation is performed, the method further includes:

[0043] B. Heat insulation and energy saving

[0044] The power supply mode of the central magnetic coil in the storage area, the edge magnetic coil in the storage area and the magnetic coil in the working area is changed to intermittent power supply so that the condition is met: the magnetic fluid does not flow back.

[0045] The present invention has the following beneficial effects compared with the prior art:

[0046] 1. The present invention provides a magnetic fluid thermal switch, which uses magnetic fluid in conjunction with an electromagnetic field to control the on / off of the heat transfer path. Compared with a mechanical contact thermal switch, it is small in size and light in weight, and can effectively avoid the problem of thermal switch failure caused by vacuum cold welding.

[0047] 2. The present invention provides a magnetic fluid thermal switch, which adopts a structural design of two heat-conducting mounting plates plus two sealed cavities. It is not limited by the size of the mounting interface and can be as small as 5 mm in thickness (where the working area of ​​the magnetic fluid is within 3 mm). It is suitable for use in occasions where the space area of ​​the heat transfer path from the heating equipment to the heat sink is narrow. The spatial size and shape of the sealed cavity can be flexibly designed according to actual equipment requirements.

[0048] 3. The present invention provides a method for controlling the thermal conductivity of magnetic fluid, which uses multiple adjustable magnetic fields to cooperate with each other to control the flow of magnetic fluid and realize thermal switching between interfaces, thereby meeting the heat dissipation and insulation requirements of detectors and electronic equipment, and providing the possibility for weight reduction design of heat sinks and the entire satellite.

[0049] 4. This invention provides a magnetic fluid thermal conductivity control method that utilizes an intermittent magnetic field to prevent magnetic fluid backflow while reducing magnetic coil power and heat dissipation. When the electronic device is powered off and not generating heat, the heat transfer path is closed and insulated, effectively reducing the thermal compensation power required during shutdown and minimizing satellite resource consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is a schematic structural diagram of an embodiment of a magnetic fluid thermal switch of the present invention;

[0051] Figure 2 yes Figure 1 Exploded view of

[0052] Figure 3 This is a half-section diagram of an embodiment of the present invention. Figure 1 ;

[0053] Figure 4 This is a half-section diagram of an embodiment of the present invention. Figure 2 ;

[0054] Figure 5 This is a half-section diagram of an embodiment of the present invention. Figure 3 ;

[0055] Figure 6 yes Figure 5 Exploded view of

[0056] Figure 7 yes Figure 5 Cross-sectional view of .

[0057] The following are the descriptions of the accompanying figures:

[0058] 1-heat conduction mounting plate; 2-separated thermal insulation pad; 3-ring thermal insulation pad; 4-working area;

[0059] 5-working area sealed cavity, 51-working area sealed cavity, 52-working area connection port; 6-working area magnetic coil; 7-working area coil protective layer;

[0060] 8-storage area sealed cavity, 81-storage area sealed cavity, 82-storage area connection port; 9-storage area magnetic coil, 91-storage area center magnetic coil, 92-storage area edge magnetic coil; 10-storage area coil protection layer; 11-storage area. DETAILED DESCRIPTION

[0061] The specific technical solutions in the embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0062] The present invention addresses the problems of large fluctuations in external heat flux of heat sinks used for heat dissipation of space observation optical cameras and space electronic equipment, large design area of ​​heat sinks caused by solar radiation heating, and large compensatory heating power of electronic equipment, which cannot simultaneously meet the requirements of satellite weight reduction, structural design, thermal design and other indicators. The present invention innovatively adopts magnetic fluid in combination with electromagnetic field control, utilizes magnetic fluid as the interface filling material between the hot and cold ends of the thermal conductive mounting plate, controls the flow of magnetic fluid by changing the magnetic field, thereby regulating the presence or absence of interface filling material between the hot and cold ends of the thermal conductive mounting plate, and further controls the switching of the heat transfer path, thereby realizing flexible control of thermal conduction / insulation.

[0063] Figure 1-Figure 7 A magnetic fluid thermal switch provided in an embodiment of the present invention is mainly composed of a sealed cavity in the storage area, a central magnetic coil in the storage area, an edge magnetic coil in the storage area, a magnetic coil in the working area, thermal insulation materials, a coil protective layer and the like. The volume of the storage area is equal to the volume of the working area, and the thickness of the sealed cavity in the working area is relatively thin (the thinnest is 1mm, which is determined by the area of ​​the heat-conducting mounting plate in the working area. The smaller the area, the thinner the thickness, and the larger the area, the thicker the thickness). The size and shape of the storage area can be flexibly designed according to the available space near the heat-conducting mounting plate. The magnetic coil is insulated from the sealed cavity and the magnetic fluid by the insulating glue of the coil protective layer. The insulating glue of the coil protective layer also plays a role in reducing the resistance to the flow of the magnetic fluid. Compared with the insulation skin of the coil itself, it mainly reduces the surface roughness of the coil and reduces the relative resistance to the flow of the magnetic fluid. All mounting surfaces have vacuum sealing measures, and the areas inside the cavity where there is no magnetic fluid are in a vacuum state. The specific method is as follows:

[0064] It includes two heat-conducting mounting plates 1, two separated heat-insulating pads 2, two annular heat-insulating pads 3, a working area sealed cavity 5 and a storage area sealed cavity 8, and the cavity is filled with magnetic fluid;

[0065] Workspace

[0066] The working area 4 includes two upper and lower heat-conducting mounting plates 1. The inner surfaces of the heat-conducting mounting plates 1 and the heat-insulating material are coated with a metal film with low infrared emissivity, making "heat-conducting mounting plate - magnetic fluid - heat-conducting mounting plate" the main heat transfer path. Specifically:

[0067] The two thermally conductive mounting plates 1 are spaced apart, and the two separate thermal insulation pads 2 are relatively arranged in the space between the two thermally conductive mounting plates 1 to form a working area 4; the two ends of the working area 4 are respectively connected to the working area sealed cavity 5 and the storage area sealed cavity 8 through annular thermal insulation pads 3.

[0068] The separation thermal insulation pad 2 is a T-shaped structure, with the bottom end of the T facing the working area 4 and sandwiched between the two thermally conductive mounting plates 1. The inner surfaces of the thermally conductive mounting plate 1 and the separation thermal insulation pad 2 facing the working area 4 are provided with a gold-plated film or a silver-plated film, and the film meets the condition: infrared emissivity is less than 0.1. The thermally conductive mounting plate also needs to be coated because it is necessary to reduce the radiation heat exchange between the two thermally conductive mounting plates 1 during thermal insulation. The effect of reducing the radiation heat exchange between the two thermally conductive mounting plates 1 is achieved by reducing the radiation emissivity. The thickness of the thermally conductive mounting plate 1 is 1 mm. The thermally conductive mounting plate 1, the separation thermal insulation pad 2 and the annular thermal insulation pad 3 are connected by vacuum sealant.

[0069] The working area sealed cavity 5 is provided with a working area sealed cavity 51 located inside it and a working area connecting port 52 located on its surface. The working area sealed cavity 51 is connected with the working area 4 through the working area connecting port 52; a working area coil protective layer 7 and a working area magnetic coil 6 are provided on the inner wall of the working area sealed cavity 51 away from the working area connecting port 52. The working area magnetic coil 6 is embedded in the working area coil protective layer 7 and is insulated from the magnetic fluid by the working area coil protective layer 7; the surface of the working area coil protective layer 7 facing the working area 4 is smooth; the working area coil protective layer 7 fills the working area sealed cavity 51, and the smooth surface of the working area coil protective layer 7 is flush with the outer edge of the working area connecting port 52.

[0070] Storage Area

[0071] The storage area has three sets of magnetic coils, with the positive and negative poles of the magnetic coils passing through the sealed cavity and connected to the magnetic coil control assembly. The surface of the coil protection layer in the storage area is smooth, and the edges of the storage area are sloped to reduce the flow resistance of the magnetic fluid during flow and reduce the required magnetic field. Specifically:

[0072] The storage area sealed cavity 8 is provided with a storage area sealed cavity 81 located inside it and a storage area connecting port 82 located on the surface. The storage area sealed cavity 81 is connected with the working area 4 through the storage area connecting port 82; a storage area coil protective layer 10 and a storage area magnetic coil 9 are provided on the inner wall of the storage area sealed cavity 81 away from the storage area connecting port 82. The storage area magnetic coil 9 is embedded in the storage area coil protective layer 10 and is insulated from the magnetic fluid by the storage area coil protective layer 10; the storage area magnetic coil 9 includes a storage area center magnetic coil 91 and at least one storage area edge magnetic coil 92; the storage area center magnetic coil 91 is close to the storage area connecting port 82, and the storage area edge magnetic coil 92 is away from the storage area connecting port 82; the surface of the storage area coil protective layer 10 facing the storage area 11 is smooth.

[0073] The storage area sealed cavity 8 is a rectangular block structure. The storage area connection port 82 is located at the center of its largest surface. The plane where the storage area coil protection layer 10 is located is parallel to this largest surface. There are two magnetic coils 92 at the edges of the storage area, which are respectively located at both ends of the storage area coil protection layer 10. The central magnetic coil 91 of the storage area is located at the position corresponding to the storage area connection port 82 on the storage area coil protection layer 10.

[0074] The cross-sectional area of the storage area sealed cavity 81 parallel to the plane of the storage area connection port 8 gradually increases from the storage area connection port 82 inward, that is, it can reduce the flow resistance during the flow of the ferrofluid, improve the fluidity of the ferrofluid, and at the same time can reduce the magnetic field required for the magnetic coil to attract the ferrofluid. The remaining cavity part of the storage area sealed cavity 81 constitutes the storage area 11. The storage area 11 and the vacuum cavity in the working area 4 are filled with ferrofluid, and the fluid is composed of a liquid doped with magnetic metal particles. Most of the ferrofluid is magnetic metal particles, and the filling liquid of the polymer material only plays the role of filling the gaps between the particles and accounts for a relatively small volume ratio.

[0075] The relationship between the volume V1 of the ferrofluid, the volume V2 of the storage area 11, and the volume V3 of the working area 4 is satisfied: V3 < V1 < V2. The more the working area 4 filled with ferrofluid, the better the heat conduction performance. If V1 > V2, there will always be ferrofluid in the working area 4, which will affect the heat insulation performance.

[0076] The working principle of the embodiment of the present invention is as follows:

[0077] When the thermal switch plays a heat conduction role, a larger current is applied to the magnetic coil in the working area, a smaller current is applied to the central magnetic coil in the storage area, and the magnetic coils at the edges of the storage area are not energized. The ferrofluid will flow from the storage area to the working area under the action of the magnetic field. After all the ferrofluid flows into the working area, the ferrofluid fills the space between the two heat conduction mounting plates on both sides of the working area, the thermal resistance decreases, and the temperature difference between the two sides of the heat conduction mounting plate in the working area is significantly reduced. At this time, the power-on mode is changed to intermittent power-on, which can reduce the magnetic coil power and heat consumption while avoiding the backflow of the ferrofluid;

[0078] When the thermal switch plays a heat insulation role, a larger current is applied to the magnetic coils at the edges of the storage area, a smaller current is applied to the central magnetic coil in the storage area, and the magnetic coil in the working area is not energized. The ferrofluid will flow from the working area to the storage area under the action of the magnetic field. After all the ferrofluid flows into the storage area, there is no ferrofluid conduction between the two heat conduction mounting plates on both sides of the working area, the thermal resistance increases, and the temperature difference between the two sides of the heat conduction mounting plate significantly increases. At this time, the power-on mode is changed to intermittent power-on, and the function is the same as above.

[0079] The steps of a ferrofluid heat conduction control method provided in this embodiment are as follows:

[0080] S0, install a ferrofluid thermal switch at the target position, and the two heat conduction mounting plates 1 respectively correspond to the two ports of the heat transfer path;

[0081] S1, turn on thermal conduction mode

[0082] When heat conduction is required, currents I1, I2, and I3 are respectively applied to the storage area center magnetic coil 91, the storage area edge magnetic coil 92, and the working area magnetic coil 6, where I3>I1 and I2=0.

[0083] S2, conduct heat

[0084] Under the action of the magnetic field, the magnetic fluid flows into the working area 4;

[0085] When the magnetic fluid is completely flowing into the working area 4 or the working area 4 is filled, the magnetic fluid thermal switch is in the heat conduction mode; at this time, the thermal resistance between the heat conduction mounting plates 1 on both sides of the working area 4 is reduced due to the presence of the magnetic fluid, and the temperature difference between the two sides is reduced;

[0086] A. Thermal conductivity and energy saving

[0087] The power supply mode of the storage area center magnetic coil 91, the storage area edge magnetic coil 92 and the working area magnetic coil 6 is changed to intermittent power supply so that the conditions are met: the magnetic fluid does not flow back;

[0088] S3, turn on heat insulation mode

[0089] When thermal insulation is required, currents I1, I2, and I3 are respectively applied to the storage area center magnetic coil 91, the storage area edge magnetic coil 92, and the working area magnetic coil 6, where I2>I1 and I3=0.

[0090] S4, perform thermal insulation

[0091] Under the action of the magnetic field, the magnetic fluid flows into the storage area 11;

[0092] When the magnetic fluid is completely flowing into the storage area 11 or the storage area 11 is filled, the magnetic fluid thermal switch is in the heat insulation mode; at this time, the thermal resistance between the heat-conducting mounting plates 1 on both sides of the working area 4 increases due to the vacuum, and the temperature difference between the two sides increases;

[0093] B. Heat insulation and energy saving

[0094] The power supply mode of the storage area center magnetic coil 91, the storage area edge magnetic coil 92 and the working area magnetic coil 6 is changed to intermittent power supply so that the condition is met: the magnetic fluid does not flow back.

[0095] The above content is only one embodiment of the present invention and does not limit the scope of protection of the present invention. Any equivalent structural transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A magnetic fluid thermal switch, characterized in that: It comprises two heat-conducting mounting plates (1), two separate heat-insulating pads (2), two annular heat-insulating pads (3), a working area sealed cavity (5), and a storage area sealed cavity (8); The two heat-conducting mounting plates (1) are spaced apart, and the two separation heat-insulating pads (2) are relatively arranged in the space between the two heat-conducting mounting plates (1), thereby enclosing a working area (4); The two ends of the working area (4) are respectively connected to the working area sealed cavity (5) and the storage area sealed cavity (8) through the annular thermal insulation pad (3); The working area sealed cavity body (5) is provided with a working area sealed cavity (51) located inside the working area sealed cavity and a working area connecting port (52) located on the surface thereof, and the working area sealed cavity (51) is connected to the working area (4) through the working area connecting port (52); a working area coil protective layer (7) and a working area magnetic coil (6) are provided on the inner wall of the working area sealed cavity (51) away from the working area connecting port (52); The storage area sealed cavity (8) is provided with a storage area sealed cavity (81) located inside the storage area sealed cavity and a storage area connecting port (82) located on the surface. The storage area sealed cavity (81) is connected to the working area (4) through the storage area connecting port (82). A storage area coil protective layer (10) and a storage area magnetic coil (9) are provided on the inner wall of the storage area sealed cavity (81) away from the storage area connecting port (82). The storage area magnetic coil (9) includes a storage area center magnetic coil (91) and at least one storage area edge magnetic coil (92). The storage area center magnetic coil (91) is close to the storage area connecting port (82), and the storage area edge magnetic coil (92) is away from the storage area connecting port (82). The remaining cavity portion of the storage area sealed cavity (81) constitutes a storage area (11), and the vacuum cavity in the storage area (11) and the working area (4) is filled with magnetic fluid; the working area magnetic coil (6) is insulated from the magnetic fluid by the working area coil protective layer (7); and the storage area magnetic coil (9) is insulated from the magnetic fluid by the storage area coil protective layer (10); The volume V1 of the magnetic fluid, the volume V2 of the storage area (11) and the volume V3 of the working area (4) satisfy the relationship: V1 <V2+V3。 2. A magnetic fluid thermal switch according to claim 1, characterized in that: The working area magnetic coil (6) is embedded in the working area coil protection layer (7); the surface of the working area coil protection layer (7) facing the working area (4) is smooth; the working area coil protection layer (7) fills the working area sealed cavity (51), and the smooth surface of the working area coil protection layer (7) is flush with the outer edge of the working area connection port (52); The storage area magnetic coil (9) is embedded in the storage area coil protection layer (10); the surface of the storage area coil protection layer (10) facing the storage area (11) is smooth.

3. A magnetic fluid thermal switch according to claim 2, characterized in that: The cross-sectional area of ​​the storage area sealed cavity (81) parallel to the plane where the storage area connecting port (82) is located gradually increases from the storage area connecting port (82) inwards.

4. A magnetic fluid thermal switch according to any one of claims 1 to 3, characterized in that: The V1, V2 and V3 satisfy the relationship: V3 <V1<V2。 5. The magnetic fluid thermal switch according to claim 4, characterized in that: The storage area sealed cavity (8) is a rectangular block structure, the storage area connection port (82) is located at the center of one of its largest surfaces, and the plane where the storage area coil protection layer (10) is located is arranged parallel to the largest surface; there are two storage area edge magnetic coils (92), which are respectively located at the two ends of the storage area coil protection layer (10), and the storage area center magnetic coil (91) is located at the storage area coil protection layer (10) corresponding to the storage area connection port (82).

6. The magnetic fluid thermal switch according to claim 5, characterized in that: The separation heat insulation pad (2) is a T-shaped structure, with the bottom end of the T facing the working area (4) and sandwiched between the two heat-conducting mounting plates (1).

7. The magnetic fluid thermal switch according to claim 6, characterized in that: The inner surfaces of the heat-conducting mounting plate (1) and the separation heat-insulating pad (2) facing the working area (4) are provided with a gold-plated film or a silver-plated film, and the film meets the condition that the infrared emissivity is less than 0.

1.

8. The magnetic fluid thermal switch according to claim 7, characterized in that: The thickness of the heat-conducting mounting plate (1) is 1 mm; The heat-conducting mounting plate (1), the separation heat-insulating pad (2) and the annular heat-insulating pad (3) are all connected by vacuum sealant; The magnetic fluid is composed of magnetic metal particles doped with filling liquid.

9. A magnetic fluid thermal conductivity control method, characterized in that: The following steps are involved: S0, installing a magnetic fluid thermal switch according to any one of claims 1 to 8 at a target location, wherein the two heat-conducting mounting plates (1) correspond to two ports of a heat transfer path respectively; S1, turn on thermal conduction mode When heat conduction is required, currents I1, I2, and I3 are respectively passed through the storage area center magnetic coil (91), the storage area edge magnetic coil (92), and the working area magnetic coil (6), wherein I3>I1, and I2=0; S2, conduct heat Under the action of the magnetic field, the magnetic fluid flows into the working area (4); When the magnetic fluid is completely flowed into the working area (4) or the working area (4) is filled, the magnetic fluid thermal switch is in a heat conduction mode; at this time, due to the presence of the magnetic fluid, the thermal resistance between the heat conduction mounting plates (1) on both sides of the working area (4) is reduced, and the temperature difference between the two sides is reduced; S3, turn on heat insulation mode When heat insulation is required, currents I1, I2, and I3 are respectively passed through the storage area center magnetic coil (91), the storage area edge magnetic coil (92), and the working area magnetic coil (6), wherein I2>I1, and I3=0; S4, perform thermal insulation Under the action of the magnetic field, the magnetic fluid flows into the storage area (11); When the magnetic fluid is waiting to flow into the storage area (11) or the storage area (11) is filled, the magnetic fluid thermal switch is in the heat insulation mode; at this time, due to the existence of vacuum between the heat conduction mounting plates (1) on both sides of the working area (4), the thermal resistance increases and the temperature difference between the two sides increases; thus, the heat conduction control of the magnetic fluid is achieved.

10. A magnetic fluid thermal conductivity control method according to claim 9, characterized in that: After step S2 is completed and heat conduction is performed, the method further includes: A. Thermal conductivity and energy saving The power supply mode of the storage area center magnetic coil (91), the storage area edge magnetic coil (92) and the working area magnetic coil (6) is changed to intermittent power supply so as to meet the following conditions: the magnetic fluid does not flow back; After step S4 is completed and the heat insulation is performed, the method further includes: B. Heat insulation and energy saving The energizing mode of the storage area center magnetic coil (91), the storage area edge magnetic coil (92) and the working area magnetic coil (6) is changed to intermittent energizing so as to meet the condition that the magnetic fluid does not flow back.

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