High-power-density solid-liquid phase change cooling system and method based on force-heat coupling effect

Abstract

The invention discloses a high-power-density solid-liquid phase change cooling system and method based on a force-heat coupling effect. In the thermal pulse stage, a contact melting mode is adopted, that is, a servo motor actively drives a solid phase change material to make close contact with a heat source to be melted, the melted liquid phase change material is discharged into a liquid storage cavity in time, and the thickness of the liquid phase change material, making close contact with the heat source, in the solid-liquid phase change cavity is maintained to be below hundred micrometers; in a thermal pulse intermittent stage, a dynamic solidification mode is adopted, namely, a servo motor actively pushes a liquid phase change material into a solid-liquid phase change cavity to enable the liquid phase change material to be solidified under the action of a refrigeration module, the solidified phase change material is lifted by a pin fin at the bottom of a piston of the solid-liquid phase change cavity to move upwards, and layer-by-layer stepping solidification of the liquid phase change material is achieved; meanwhile, layer-by-layer solidification can inhibit hole development, the recycling performance of the phase change material is improved, and more efficient and stable reciprocating work is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of cooling of high-power heat flux in space, and particularly relates to a high-power density solid-liquid phase change cooling system and method based on force-thermal coupling effect. Background Art

[0002] High-power space equipment generates periodic heat pulses, and the waste heat per unit area on its optical and electronic components is huge. The thermal management of these components faces new thermal safety challenges such as microgravity, vacuum environment, limited weight and volume. Traditional air-cooling and water-cooling technologies rely on the flow of air or water, and have limitations such as complex structure, large volume, and high energy consumption, and are difficult to meet the cooling requirements of high power, high temperature uniformity, and lightweight integration in space. The solid-liquid phase change technology has the characteristics of high latent heat and constant-temperature heat storage and release, and can solve the problem of incoordination of heat load in time and space under extreme space environments through the method of peak shifting and valley filling.

[0003] However, the existing solid-liquid phase change cooling technologies usually adopt passive cooling methods, and their performance drops significantly under microgravity. During the melting process, the low-thermal-conductivity liquid of the phase change material cannot be removed in time, and the thermal resistance continuously increases, resulting in a low cooling power density. During the solidification process, traditional solid-liquid phase change cooling technologies mostly adopt overall simultaneous solidification, with a slow speed and it is difficult to achieve rapid melting / solidification cycles. The existing composite phase change cooling systems with added metal fins and metal foams still cannot achieve cooling under high heat flux density, and at the same time reduce the comprehensive energy storage density. Summary of the Invention

[0004] In view of this, the present invention provides a high-power density solid-liquid phase change cooling system and method based on force-thermal coupling effect, which can be used for the thermal management of periodic high-power heat pulses in space environment, and realize solid-liquid phase change cooling with high power density and high temperature uniformity.

[0005] The high-power density solid-liquid phase change cooling system based on force-thermal coupling effect of the present invention includes: a solid-liquid phase change module, a motor module, and a refrigeration module; wherein, the solid-liquid phase change module includes a solid-liquid phase change cavity, a liquid storage cavity, a liquid delivery pipe, and a support frame; the motor module includes a servo motor I, a servo motor II, a solid-liquid phase change cavity piston, and a liquid storage cavity piston;

[0006] Wherein, the solid-liquid phase change cavity and the liquid storage cavity are fixed on the support frame, and the solid-liquid phase change cavity and the liquid storage cavity are connected through the liquid delivery pipe; the solid-liquid phase change cavity is closely attached to the heat source and is filled with a solid-liquid phase change material inside;

[0007] The refrigeration module is arranged at the bottom of the solid-liquid phase change cavity and is used for the solidification of the liquid phase change material;

[0008] The servo motor I and the servo motor II are respectively installed at the tops of the solid-liquid phase change cavity and the liquid storage cavity; one end of the solid-liquid phase change cavity piston / liquid storage cavity piston is connected to the servo motor I / servo motor II, and the other end is hermetically extended into the solid-liquid phase change cavity / liquid storage cavity; the bottom of the solid-liquid phase change cavity piston is provided with pin fins.

[0009] Preferably, the inner surface of the bottom of the solid-liquid phase change cavity and / or the inner surface of the bottom of the liquid storage cavity is provided with a micro-nano drag reduction structure.

[0010] Preferably, the micro-nano drag reduction structure is a shark skin micro-nano bionic drag reduction structure, a lotus leaf surface bionic drag reduction structure or a rectangular groove drag reduction structure.

[0011] Preferably, the solid-liquid phase change material is any one of crystalline hydrated salts, paraffin waxes and fatty acids, or a nano-composite phase change material composed of carbon nano-materials and metal nano-materials with a thermal conductivity greater than 0.55 W / (m·K) and a viscosity less than 80 mPa·s.

[0012] Preferably, the carbon nano-material is graphite, graphene, carbon nanotubes or carbon fibers; the metal nano-material is alumina, iron tetroxide, copper oxide or titanium dioxide.

[0013] Preferably, the liquid storage cavity is provided with a temperature control module for maintaining the liquid phase change material in the liquid storage cavity.

[0014] Preferably, the temperature control module includes: a heat insulation material provided on the outer surface of the liquid storage cavity, and a heating sheet provided on the bottom of the liquid storage cavity.

[0015] The present invention also provides a method for using the above high-power density solid-liquid phase change cooling system based on the force-thermal coupling effect, including a heat pulse stage and a heat pulse intermittent stage;

[0016] In the heat pulse stage, the contact melting method is adopted, that is, the servo motor I drives the solid-liquid phase change cavity piston to move downward, and then drives the solid phase change material in the solid-liquid phase change cavity to closely contact the heat source and melt; at the same time, the servo motor II synchronously drives the liquid storage cavity piston to move upward, so as to prompt the liquid phase change material in the solid-liquid phase change cavity to be discharged into the liquid storage cavity through the infusion tube in time;

[0017] In the heat pulse intermittent stage, the dynamic solidification method is adopted, that is, the servo motor II moves downward, extrudes the liquid phase change material in the liquid storage cavity and transports it to the solid-liquid phase change cavity, and cools and solidifies layer by layer under the action of the refrigeration module. After each layer is solidified, the servo motor I drives the pin fins at the bottom of the solid-liquid phase change cavity piston to lift the solidified phase change material upward.

[0018] Preferably, in the heat pulse stage, the thickness of the liquid phase change material in the solid-liquid phase change cavity is maintained below a hundred micrometers.

[0019] Preferably, during the thermal pulse intermittent stage, only one layer of the liquid phase change material with a thickness of 1-20 mm is solidified each time.

[0020] Beneficial effects:

[0021] (1) The present invention mainly includes a solid-liquid phase change module, a motor module and a refrigeration module. During the thermal pulse stage, the servo motor actively drives the solid phase change material to closely contact the heat source and melt, and efficiently discharges the low-thermal-conductivity liquid phase change material after endothermic melting into the liquid storage cavity, so that the solid phase change material in the solid-liquid phase change cavity can maintain contact melting; during the thermal pulse intermittent stage, a dynamic solidification method is adopted, and the liquid phase change material is actively pushed into the solid-liquid phase change cavity by the servo motor, so that it solidifies under the action of the refrigeration module, and the solidified phase change material is lifted upward by the pin fins at the bottom of the piston of the solid-liquid phase change cavity, realizing dynamic step-by-step solidification layer by layer, reducing the heat transfer thermal resistance during the solidification process, and greatly shortening the solidification time; at the same time, step-by-step solidification layer by layer can inhibit the development of cavities, improve the cyclic use performance of the phase change material, and realize more efficient and stable reciprocating operation. The solid-liquid phase change method with force-thermal coupling effect of the present invention makes up for the deficiencies of the traditional passive solid-liquid phase change, such as large melting thermal resistance, slow solidification rate and low heat flux density. The solid-liquid phase change power density > 1.5 W / cm 3 , the heat flux density > 10 W / cm 2 , the temperature uniformity < 2 °C, and it has a reciprocating characteristic, realizing long-term stable cyclic cooling operation.

[0022] (2) Micro-nano drag reduction structures are arranged on the inner surface of the flange of the solid-liquid phase change cavity and the inner surface of the bottom flange of the liquid storage cavity to reduce the flow resistance of the liquid phase change material and further improve the power density of the solid-liquid phase change.

[0023] (3) The liquid storage cavity is subjected to temperature control and heat insulation treatment to ensure that the temperature of the phase change material in the liquid storage cavity is always higher than the melting point and remains liquid during the thermal pulse intermittent stage, so that dynamic solidification can be carried out quickly during the thermal pulse intermittent stage.

[0024] (4) During the thermal pulse stage, the thickness of the liquid phase change material in the solid-liquid phase change cavity is maintained below a few hundred micrometers to further reduce the liquid film thermal resistance and strengthen heat transfer; during the thermal pulse intermittent stage, only one thin layer (1-20 mm) of the liquid phase change material is solidified each time, which can effectively reduce the heat transfer thermal resistance during the solidification process, greatly shorten the solidification time, and inhibit the development of cavities. Description of the drawings

[0025] Figure 1 It is a schematic diagram of the cooling system of the present invention; wherein, Figure 1 (a) is an isometric view of the cooling system of the present invention, Figure 1 (b) is a front view of the cooling system of the present invention, Figure 1(c) is a side view of the cooling system of the present invention;

[0026] Figure 2 is a sectional view of the cooling system of the present invention;

[0027] Figure 3 is a flow chart of the force-thermal coupling solid-liquid phase change cooling cycle of the present invention;

[0028] Figure 4 is a schematic diagram of the piston of the present invention; wherein, Figure 4 (a) is a schematic diagram of a cylindrical pin-fin piston, Figure 4 (b) is a schematic diagram of a triangular prism pin-fin piston, Figure 4 (c) is a schematic diagram of a cuboid pin-fin piston, Figure 4 (d) is a schematic diagram of a flat piston;

[0029] Figure 5 is a schematic diagram of the micro-nano drag reduction structure on the inner surface of the solid-liquid phase change chamber flange; wherein, Figure 5 (a) is an isometric view of the solid-liquid phase change chamber flange, Figure 5 (b) is a sectional view of the solid-liquid phase change chamber flange.

[0030] Among them, 1 - Servo motor I, 2 - Servo motor II, 3 - Support top plate, 4 - Top flange of the liquid storage chamber, 5 - Top flange of the solid-liquid phase change chamber body, 6 - Solid-liquid phase change chamber piston (with pin fins), 7 - Liquid storage chamber piston (flat bottom), 8 - Support frame, 9 - Fastening bolt, 10 - Solid-liquid phase change chamber body, 11 - Liquid storage chamber body, 12 - Bottom flange of the liquid storage chamber, 13 - Bottom flange of the solid-liquid phase change chamber body, 14 - Liquid delivery pipe, 15 - Ceramic heating sheet I, 16 - Ceramic heating sheet II, 17 - TEC refrigeration sheet, 18 - Fin radiator, 19 - Small fan, 20 - Solid phase change material, 21 - Liquid phase change material. Detailed implementation manners

[0031] The present invention will be described in detail below with reference to the accompanying drawings and by way of examples.

[0032] The present invention provides a high-power density solid-liquid phase change cooling system based on the force-thermal coupling effect, as Figure 1 and Figure 2 shown, which includes a solid-liquid phase change module, a motor module and a refrigeration module;

[0033] In the force-thermal coupling of the present invention, the "force" is the motor module, which realizes the pressure supply and lifting movement during the melting and solidification processes; the "heat" is the solid-liquid phase change module and the refrigeration module, which realize the solid-liquid phase change process of the phase change material; the force-thermal coupling jointly realizes the contact melting in the melting stage and the dynamic solidification in the solidification stage of the solid-liquid phase change material, with a high cooling power density and the characteristic of being able to work reciprocally.

[0034] The solid-liquid phase change module includes a solid-liquid phase change cavity 10, a liquid storage cavity 11, and an infusion tube 14. Among them, the solid-liquid phase change cavity 10 and the liquid storage cavity 11 are made of materials such as glass and acrylic, and the top and bottom are fixed to the support frame 8 by flanges made of aluminum alloy materials; the cavity and the flange are connected by bolts to ensure firm sealing between the cavity and the flange; the solid-liquid phase change cavity 10 and the liquid storage cavity 11 are connected through the infusion tube 14. The bottom of the solid-liquid phase change cavity 10 is closely attached to the heat source 16; a phase change material is stored in the solid-liquid phase change cavity 10, and the liquid phase change material flows between the two cavities through the infusion tube 14.

[0035] The refrigeration module is installed at the solid-liquid phase change cavity 10 and is used to provide the cooling capacity required to cool the phase change material during the solidification process. A TEC refrigeration module, a water-cooled plate, a small loop heat pipe, a small water-cooled circuit, etc. can be used. Finned radiators 18, fans 19, etc. can be further provided on the TEC.

[0036] The motor module includes a servo motor and a piston; the servo motors are respectively placed on the upper parts of the solid-liquid phase change cavity and the liquid storage cavity and are fixed to the support frame 8 through the support top plate 3; the center of the motor lead screw is concentric with the cavity; one end of the piston is connected to the motor lead screw, and the other end extends into the cavity through the top flange of the cavity; O-ring seals are provided on the sides of the solid-liquid phase change cavity piston 6 and the liquid storage cavity piston 7 for vacuum sealing.

[0037] Among them, pin fins are provided at the bottom of the solid-liquid phase change cavity piston 6, and the pin fins are used to fix the solidified solid phase change material, so that the solid phase change material closely follows the piston during the dynamic solidification process, and the solid phase change material is lifted when the solid-liquid phase change cavity piston 6 moves upward under the drive of the servo motor I1.

[0038] Preferably, a micro-nano drag reduction structure, such as a micro-nano bionic drag reduction structure like shark skin, a bionic drag reduction structure like the drag reduction structure of a lotus leaf surface, a drag reduction structure such as a rectangular groove, etc., can be provided on the inner surface of the solid-liquid phase change cavity flange 13 and / or the inner surface of the bottom flange 12 of the liquid storage cavity, so as to reduce the resistance when the liquid phase change material flows and realize the rapid flow of the liquid phase change material between the solid-liquid phase change cavity 10 and the liquid storage cavity 11.

[0039] Preferably, the flanges 4, 5, 12, 13, the pistons 6, 7, the support top plate 3, the finned radiator 18, the infusion tube 14, the bolts 9, and the support frame 8 are made of aluminum, aluminum alloy, or magnesium alloy, which have the characteristics of light weight and high thermal conductivity and meet the mechanical properties standards;

[0040] Preferably, the phase change material is any one of crystalline hydrated salts, paraffin wax, fatty acids, or a nano composite phase change material with high thermal conductivity and low viscosity composed of the above materials and carbon nano materials such as graphite, graphene, carbon nanotubes, carbon fibers, and metal nano materials such as alumina, iron oxide, copper oxide, titanium dioxide (the thermal conductivity in the liquid state is greater than 0.55 W / (m·K), and the viscosity is less than 80 mPa·s);

[0041] Preferably, the O-ring is made of perfluorinated material, silicone rubber, fluororubber, etc. This material has no chemical reaction with the phase change material and has good material compatibility.

[0042] Preferably, the liquid storage cavity is subjected to temperature control and heat preservation treatment. For example, heat preservation materials such as polyimide or polyethylene are added outside the liquid storage cavity, and a heating sheet is installed at the bottom for constant temperature control to ensure that the temperature of the phase change material in the liquid storage cavity is always higher than the melting point and remains liquid during the thermal pulse intermittent stage.

[0043] The system of the present invention actively drives the solid phase change material to contact the heat source and melt by using a servo motor, and efficiently discharges the melted liquid phase change material with low thermal conductivity to the liquid storage cavity, maintaining the continuous and close contact between the high thermal conductivity solid phase change material in the solid-liquid phase change cavity 10 and the heat source for melting. At the same time, the system of the present invention has good internal sealing, and the phase change material can be reused: the liquid phase change material in the liquid storage cavity is actively pushed into the solid-liquid phase change cavity by using the servo motor and the piston, and the liquid phase change material in the solid-liquid phase change cavity is dynamically cooled and solidified layer by layer step by step through the refrigeration module and the servo motor to achieve repeated heat absorption. The system of the present invention realizes long-term stable cyclic cooling operation through reciprocating contact melting and dynamic solidification.

[0044] Specifically, the operation process of this system includes a thermal pulse stage and a thermal pulse intermittent stage:

[0045] In the thermal pulse stage, the motor on the solid-liquid phase change cavity side starts to work, actively applies pressure to the solid phase change material, induces it to continuously and closely contact the heat source and melt into a liquid. At the same time, the motor on the liquid storage cavity side moves upward synergistically at the same speed, realizing the efficient discharge of the melted liquid phase change material with low thermal conductivity to the liquid storage cavity for storage, thereby preventing the liquid film in the solid-liquid phase change cavity from thickening, reducing the thermal resistance between the solid phase change material and the heat source, maintaining the high thermal conductivity of the solid phase change material in the solid-liquid phase change cavity 10, and strengthening the phase change heat transfer process. Preferably, the thickness of the liquid phase change material in the solid-liquid phase change cavity can be maintained below a few hundred micrometers.

[0046] During the intermittent stage of the heat pulse, the solid phase change material in the solid-liquid phase change cavity begins a dynamic solidification process: the motors on the solid-liquid phase change cavity side and the liquid storage cavity side adopt the opposite movement to the melting process, and the motor on the liquid storage cavity side squeezes the liquid phase change material into the solid-liquid phase change cavity, and solidifies dynamically layer by layer under the action of the refrigeration module; dynamic layer by layer step solidification, that is, after the refrigeration module solidifies a layer of phase change material, the servo motor 1 drives the pin-fin piston to pull the solidified phase change material upward. Dynamic solidification reduces the heat transfer resistance and greatly shortens the solidification time; at the same time, layer by layer step solidification can inhibit the development of cavitation and improve the recycling performance of the phase change material. Preferably, only a thin layer (1-20mm) of liquid phase change material is solidified each time.

[0047] Preferably, when there are different heat flux densities and different heat dissipation requirements at the heat source, the pressure of the extruded liquid film can be controlled by changing the motor movement speed, thereby controlling the discharge speed and the liquid film thickness (20\40\60μm) to achieve different heat flux density control requirements.

[0048] When faced with different heat flow rest time requirements, the solidification rate or solidification layer thickness of the liquid phase change material can be controlled by changing the cooling capacity or changing the step-by-step solidification height (1-20 mm) during the solidification process to achieve different heat flow rest time requirements. At the same time, step-by-step solidification can inhibit the development of voids, improve the recycling performance of phase change materials, and achieve more efficient and stable reciprocating operation.

[0049] In addition to the configuration of N (N≥1) solid-liquid phase change cavities, N liquid storage cavities and 2N servo motors, the configuration of N solid-liquid phase change cavities, 2N liquid storage cavities and 3N servo motors can also be adopted, with two liquid storage cavities connected on both sides of one solid-liquid phase change cavity to achieve temperature control of more heat sources.

[0050] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-power density solid-liquid phase change cooling system based on the coupling action of force and heat, characterized in that, It includes: A solid-liquid phase change module, a motor module, and a refrigeration module; among them, the solid-liquid phase change module includes a solid-liquid phase change cavity (10), a liquid storage cavity (11), a liquid delivery pipe (14), and a support frame (8); the motor module includes a servo motor I (1), a servo motor II (2), a solid-liquid phase change cavity piston (6), and a liquid storage cavity piston (7); Among them, the solid-liquid phase change cavity (10) and the liquid storage cavity (11) are fixed on the support frame (8), and the solid-liquid phase change cavity (10) and the liquid storage cavity (11) are connected through the liquid delivery pipe (14); the solid-liquid phase change cavity (10) is in close contact with the heat source and is filled with a solid-liquid phase change material inside; The refrigeration module is arranged at the bottom of the solid-liquid phase change cavity (10) and is used for the solidification of the liquid phase change material; The servo motor I (1) and the servo motor II (2) are respectively installed on the tops of the solid-liquid phase change cavity (10) and the liquid storage cavity (11); one end of the solid-liquid phase change cavity piston (6) / liquid storage cavity piston (7) is connected to the servo motor I (1) / servo motor II (2), and the other end extends into the cavity of the solid-liquid phase change cavity (10) / liquid storage cavity (11) in a sealed manner; needle fins are provided at the bottom of the solid-liquid phase change cavity piston (6).

2. The system according to claim 1, characterized in that The inner surface of the bottom of the solid-liquid phase change cavity and / or the inner surface of the bottom of the liquid storage cavity is provided with a micro-nano drag reduction structure.

3. The system according to claim 2, wherein The micro-nano drag reduction structure is a shark skin micro-nano bionic drag reduction structure, a lotus leaf surface bionic drag reduction structure, or a rectangular groove drag reduction structure.

4. The system according to claim 1, characterized in that The solid-liquid phase change material is any one of crystalline hydrates, paraffins, and fatty acids, or a nano-composite phase change material composed of carbon nano-materials and metal nano-materials with a thermal conductivity greater than 0.55 W / (m·K) and a viscosity less than 80 mPa·s.

5. The system according to claim 4, wherein The carbon nano-materials are graphite, graphene, carbon nanotubes, or carbon fibers; the metal nano-materials are alumina, iron tetroxide, copper oxide, or titanium dioxide.

6. The system according to claim 1, characterized in that, The liquid storage cavity is provided with a temperature control module for maintaining the liquid phase change material inside the liquid storage cavity in a liquid state.

7. The system according to claim 1, wherein The temperature control module includes: a heat insulation material provided on the outer surface of the liquid storage cavity, and a heating sheet provided at the bottom of the liquid storage cavity.

8. A method for a high-power density solid-liquid phase change cooling system based on the coupling effect of force and heat as described in any one of claims 1 to 7, characterized in that, It includes a heat pulse stage and a heat pulse intermittent stage; In the heat pulse stage, the contact melting method is adopted, that is, the servo motor I (1) drives the solid-liquid phase change cavity piston (6) to move downward, and then drives the solid-phase change material in the solid-liquid phase change cavity (10) to closely contact the heat source and melt; at the same time, the servo motor II (2) synchronously drives the liquid storage cavity piston (7) to move upward, so as to prompt the liquid phase change material in the solid-liquid phase change cavity (10) to be discharged into the liquid storage cavity (11) through the liquid delivery pipe (14) in time; In the heat pulse intermittent stage, the dynamic solidification method is adopted, that is, the servo motor II (2) moves downward, squeezes the liquid phase change material in the liquid storage cavity (11) and transports it into the solid-liquid phase change cavity, and cools and solidifies layer by layer under the action of the refrigeration module. After each layer solidifies, the servo motor I (1) drives the needle fins at the bottom of the solid-liquid phase change cavity piston (6) to lift the solidified phase change material upward.

9. The method according to claim 8, wherein In the heat pulse stage, the thickness of the liquid phase change material in the solid-liquid phase change cavity (10) is maintained below a hundred micrometers.

10. The method according to claim 8, characterized in that, During the hot pulse intermittent stage, only one layer of the liquid phase change material with a thickness of 1 - 20 mm solidifies each time.

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