A device for enhancing heat transfer of thin liquid film boiling

Abstract

The present disclosure provides a thin liquid film boiling heat transfer enhancement device, comprising: a vacuum cavity, a first mounting hole is opened in the bottom; an evaporation base is installed in the first mounting hole, and the upper surface of the evaporation base is higher than the inner bottom surface of the vacuum cavity, and the upper surface of the evaporation base is provided with a second mounting hole; a liquid dam is arranged on the upper surface of the evaporation base, a test hole with a predetermined size is arranged at the center of the liquid dam, and the size of the test hole is larger than that of the second mounting hole; an upper heating block is installed in the second mounting hole, and the upper surface of the upper heating block is located in the same horizontal plane as the upper surface of the evaporation base; a lower heating block is arranged in the evaporation base, and the lower heating block is sleeved on the bottom of the upper heating block; a spiral condensing pipe is arranged in the vacuum cavity, and the lower end of the spiral condensing pipe is spaced apart from the upper surface of the evaporation base by a predetermined distance; the centers of the spiral condensing pipe, the evaporation base, the liquid dam, the upper heating block and the lower heating block are located on the same straight line, and the straight line is perpendicular to the horizontal plane.

Description

Technical Field

[0001] This disclosure relates to the field of phase change heat transfer technology, and in particular to a thin liquid film boiling heat transfer enhancement device. Background Technology

[0002] In recent years, with the rapid development of electronic information technology, thermal management of high-power electronic systems (such as lasers, light-emitting diodes, radar, microprocessors, and power inverters) has become increasingly important. The performance of these devices is largely limited by the heat absorbed by the surrounding environment. Flat plate heat pipes and vapor chambers are passive heat dissipation elements developed from heat pipes. The main structure of a flat plate heat pipe or vapor chamber includes a shell, a wick, and a working fluid. When the heat source temperature rises, heat rapidly diffuses to the entire surface of the evaporation end. The working fluid in the wick, which is in a wetted state, begins to undergo a phase change and carries away heat. The vapor releases heat at the condensation end and condenses into liquid, then returns to the evaporation end through capillary transport, thus repeating the heat transfer cycle. Therefore, the capillary limit is the main factor limiting the maximum heat transfer capacity of flat plate heat pipes and vapor chambers. The capillary suction effect within the porous wick structure provides the driving force for the flow circulation, which has a significant impact on the performance of heat pipe-type heat dissipation elements. To further enhance the critical heat flux density of flat plate heat pipes or vapor chambers, improving the capillary-driven thin-film boiling performance within porous media has garnered significant attention from researchers. The thermal performance of the wick can be characterized by the critical heat flux (CHF), nucleus boiling initiation point (ONB), and heat transfer coefficient (HTC). Typically, capillary driving force plays a crucial role in CHF, being inversely proportional to the effective capillary radius, thus requiring a wicking structure with a smaller pore size. However, reducing the pore size leads to decreased permeability and increased liquid flow resistance, thereby lowering CHF or HTC. The trade-off between the high capillary force and high permeability of porous wick structures is a major factor limiting the heat transfer limit of heat pipe elements.

[0003] Therefore, the influence of different liquid absorber structural designs and various physical / chemical surface modification methods on the boiling heat transfer characteristics of porous media are technical problems that urgently need to be solved. Summary of the Invention

[0004] In view of the above problems, this disclosure provides a thin liquid film boiling heat transfer enhancement device.

[0005] According to one aspect of this disclosure, a thin-film boiling heat transfer enhancement device is provided, comprising:

[0006] The vacuum chamber has a first mounting hole at the bottom;

[0007] An evaporation base is installed in the first mounting hole, and the upper surface of the evaporation base is higher than the inner bottom surface of the vacuum chamber. A second mounting hole is provided on the upper surface of the evaporation base.

[0008] A liquid dam is set on the upper surface of the evaporation base, and a test hole of a preset size is opened at the center of the liquid dam. The size of the test hole is larger than the size of the second mounting hole.

[0009] The upper heating block is installed in the second mounting hole, and the upper surface of the upper heating block and the upper surface of the evaporation base are located on the same horizontal plane.

[0010] The lower heating block is installed inside the evaporation base and is fitted over the bottom of the upper heating block;

[0011] The spiral condenser is installed inside the vacuum chamber, with the lower end of the spiral condenser spaced at a predetermined distance from the upper surface of the evaporation base;

[0012] The centers of the spiral condenser, evaporator base, liquid dam, upper heating block, and lower heating block are located on the same straight line, and the straight line is perpendicular to the horizontal plane.

[0013] Optionally, the vacuum chamber includes:

[0014] The vacuum chamber has a first mounting hole at its bottom and an auxiliary heating rod mounting hole and a first thermocouple mounting hole on one side. The auxiliary heating rod mounting hole is used to install an auxiliary heating rod to heat the liquid pool in the vacuum chamber to saturation. Side observation windows are provided on the sides of the vacuum chamber that do not have auxiliary heating rod mounting holes.

[0015] Optionally, the vacuum chamber further includes:

[0016] The condenser cover is connected to the top of the vacuum chamber. The condenser cover has a spiral condenser tube mounting hole, a pressure gauge mounting hole, and a vacuum system connection hole. The liquid inlet and outlet of the spiral condenser tube extend to the outside of the vacuum chamber through the spiral condenser tube mounting hole. The pressure gauge mounting hole is used to connect a pressure sensor, and the vacuum system connection hole is used to connect a vacuum system.

[0017] Optionally, a first groove is formed on the lower surface of the evaporation base, a second groove is formed at the bottom of the first groove, a second mounting hole is formed at the bottom of the second groove, and the lower heating block is disposed in the first groove;

[0018] A third groove is provided on the upper surface of the evaporation base, and the third groove and the second groove are connected through a second mounting hole;

[0019] The width of the first groove is greater than the width of the second groove and the third groove. The width of the second groove and the third groove is greater than the width of the second mounting hole. The width of the third groove is greater than or equal to the width of the second groove.

[0020] The inner surface of the first groove is provided with a thermocouple wire fixing groove. One end of the thermocouple wire fixing groove is connected to the second groove, and the other end of the thermocouple wire fixing groove is connected to the lower surface of the evaporation base.

[0021] Optionally, the upper heating block includes:

[0022] The heating plate is installed in the third groove, and the upper surface of the heating plate is on the same horizontal plane as the upper surface of the evaporation base.

[0023] The connecting pipe has one end connected to the lower surface of the heating plate and the other end fitted with a lower heating block. The connecting pipe has three second thermocouple mounting holes, which are equidistant from each other. Thermocouple elements are installed in the second thermocouple mounting holes and are used to collect the temperature of the heating plate.

[0024] Optionally, a fourth groove is provided on the upper surface of the lower heating block, and the lower heating block is sleeved on the bottom of the upper heating block through the fourth groove;

[0025] The bottom of the fourth groove has a first heating wire mounting hole.

[0026] Optionally, the device further includes:

[0027] Plate heating elements are located on the side of the lower heating block;

[0028] An insulating sleeve covers the surface of the lower heating block, which is equipped with plate heating elements.

[0029] Optionally, an observation window is provided on the upper surface of the vacuum chamber, and the device further includes:

[0030] A high-speed camera is fixed to the upper surface of the vacuum chamber and positioned above the observation window.

[0031] Optionally, the device further includes:

[0032] The evaporator base cover is connected to the lower surface of the evaporator base, and a second heating wire mounting hole is provided on the evaporator base cover.

[0033] Optionally, the device further includes:

[0034] The vacuum chamber is mounted on the bracket.

[0035] The thin-film boiling heat transfer enhancement device disclosed herein includes: a vacuum chamber with a first mounting hole at the bottom; an evaporation base installed in the first mounting hole, with the upper surface of the evaporation base higher than the inner bottom surface of the vacuum chamber, and a second mounting hole on the upper surface of the evaporation base; a liquid dam disposed on the upper surface of the evaporation base, with a test hole of a preset size at the center of the liquid dam, the size of the test hole being larger than the size of the second mounting hole; an upper heating block installed in the second mounting hole, the upper surface of the upper heating block being on the same horizontal plane as the upper surface of the evaporation base; a lower heating block disposed in the evaporation base, and the lower heating block being fitted onto the bottom of the upper heating block; and a spiral condenser disposed in the vacuum chamber, with the lower end of the spiral condenser being spaced a preset distance from the upper surface of the evaporation base; the centers of the spiral condenser, the evaporation base, the liquid dam, the upper heating block, and the lower heating block are located on the same straight line, and the straight line is perpendicular to the horizontal plane. The thin-film boiling heat transfer enhancement device disclosed herein can be used to observe the thin-film boiling heat transfer mechanism of different test pieces. This disclosure employs a separate heating block, dividing the heating block into an upper heating block and a lower heating block. This separate design allows the test piece to be directly sintered onto the upper surface of the upper heating block, reducing contact thermal resistance. Furthermore, the device uses physical confinement (i.e., a liquid dam) to prevent liquid immersion at the top of the test piece. This method maintains the surrounding liquid level slightly higher than the test piece, ensuring continuous liquid replenishment to the evaporation center from the side via capillary suction, while avoiding any risk of immersion. This disclosure can also investigate the effect of the heat source on enhancing thin-film boiling heat transfer by changing the shape and area of ​​the upper surface of the separate heating block. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments in this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This schematic diagram illustrates the structure of a thin liquid film boiling heat transfer enhancement device according to an embodiment of the present disclosure;

[0038] Figure 2A and Figure 2B This schematic diagram illustrates the structure of a vacuum chamber in a thin-film boiling heat transfer enhancement device according to an embodiment of the present disclosure.

[0039] Figure 3 This schematic diagram illustrates the structure of the vacuum chamber of another thin liquid film boiling heat transfer enhancement device provided in an embodiment of the present disclosure;

[0040] Figure 4A and Figure 4B This schematic diagram illustrates the structure of an evaporation base for a thin liquid film boiling heat transfer enhancement device according to an embodiment of the present disclosure.

[0041] Figure 5 This schematic diagram illustrates the structure of a thin liquid film boiling heat transfer enhancement device according to an embodiment of the present disclosure;

[0042] Figure 6A and Figure 6B This schematic diagram illustrates the structure of the lower heating block of a thin liquid film boiling heat transfer enhancement device according to an embodiment of the present disclosure;

[0043] Figure 7 This schematic diagram illustrates the structure of another thin liquid film boiling heat transfer enhancement device provided in an embodiment of the present disclosure;

[0044] Figure 8 This schematically illustrates a structural diagram of another thin-film boiling heat transfer enhancement device provided in an embodiment of the present disclosure; and

[0045] Figure 9 The schematic diagram illustrates the structure of another thin liquid film boiling heat transfer enhancement device provided in an embodiment of the present disclosure.

[0046] Explanation of reference numerals in the attached figures:

[0047] 1. Bracket; 10. Vacuum chamber; 12. Vacuum chamber body; 13. Auxiliary heating rod mounting hole; 14. First thermocouple mounting hole; 15. Side observation window; 16. Condensation cover plate; 17. Spiral condenser mounting hole; 18. Pressure gauge mounting hole; 19. Vacuum system connection hole; 20. Evaporation base; 22. First groove; 23. Second groove; 24. Third groove; 25. Thermocouple wire fixing groove; 26. Evaporation base cover plate; 27. Second heating wire mounting hole; 30. Liquid dam; 31. Test hole; 40. Upper heating block; 41. Heating plate; 42. Connecting pipe; 43. Second thermocouple mounting hole; 50. Lower heating block; 51. Fourth groove; 52. First heating wire mounting hole; 60. Spiral condenser; 70. Insulating sleeve. Detailed Implementation

[0048] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0049] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0050] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0051] It should be noted that similar or identical parts are referred to by the same reference numerals in the accompanying drawings or description. Implementations not shown or described in the drawings are forms known to those skilled in the art. Furthermore, while this document provides examples of parameters containing specific values, it should be understood that the parameters need not be exactly equal to the corresponding values, but can approximate the corresponding values ​​within acceptable error tolerances or design constraints. Additionally, directional terms mentioned in the following embodiments, such as "up," "down," "front," "back," "left," "right," "inner," and "outer," are merely for reference to the directions in the accompanying drawings. Therefore, the directional terms used are for illustrative purposes and not for limiting the scope of this disclosure.

[0052] Figure 1 The schematic diagram illustrates the structure of a thin liquid film boiling heat transfer enhancement device according to an embodiment of the present disclosure.

[0053] like Figure 1 As shown, the thin liquid film boiling heat transfer enhancement device provided in this disclosure includes: a vacuum chamber 10 with a first mounting hole at the bottom; an evaporation base 20 installed in the first mounting hole, with the upper surface of the evaporation base 20 higher than the inner bottom surface of the vacuum chamber 10, and a second mounting hole on the upper surface of the evaporation base 20; a liquid dam 30 disposed on the upper surface of the evaporation base 20, with a test hole 31 of a preset size at the center of the liquid dam 30, the size of the test hole 31 being larger than the size of the second mounting hole; and an upper heating block 40 installed in the second... Inside the mounting hole, the upper surface of the upper heating block 40 and the upper surface of the evaporation base 20 are on the same horizontal plane; the lower heating block 50 is set inside the evaporation base 20 and is fitted onto the bottom of the upper heating block 40; the spiral condenser tube 60 is set inside the vacuum chamber 10, and the lower end of the spiral condenser tube 60 is spaced at a preset distance from the upper surface of the evaporation base 20; the centers of the spiral condenser tube 60, the evaporation base 20, the liquid dam 30, the upper heating block 40 and the lower heating block 50 are located on the same straight line, and the straight line is perpendicular to the horizontal plane.

[0054] In this embodiment, the thin liquid film boiling heat transfer enhancement device includes a vacuum chamber 10 and an evaporation base 20 installed in a first mounting hole at the bottom of the vacuum chamber 10, such as... Figure 1 As shown, the evaporation base 20 is installed in the first mounting hole. The upper surface of the evaporation base 20 is higher than the inner bottom surface of the vacuum chamber 10. A liquid dam 30 is installed on the upper surface of the evaporation base 20, and a test hole 31 is opened at the center of the liquid dam 30. When using the device provided in this disclosure for testing, the liquid dam 30 can be fixed to the upper surface of the evaporation base 20 with bolts. At the same time, a gap with the same thickness as the test piece is left between the liquid dam 30 and the evaporation base 20 for capillary suction of the test piece. An upper heating block 40 is installed in the second mounting hole opened on the upper surface of the evaporation base 20. The upper surface of the upper heating block 40 is located on the same horizontal plane as the upper surface of the evaporation base 20. During testing, the test piece is sintered onto the upper surface of the upper heating block 40. A lower heating block 50 is fitted at the bottom of the upper heating block 40 and is located inside the evaporation base 20. A spiral condenser tube 60 is also provided in the vacuum chamber 10. The lower end of the spiral condenser tube 60 is spaced at a preset distance from the evaporation base 20. This distance can be determined according to the testing needs. The spiral condenser 60, evaporator base 20, liquid dam 30, upper heating block 40, and lower heating block 50 are all centered on the same straight line, which is perpendicular to the horizontal plane. (For reference...) Figure 1 .

[0055] In this embodiment, the height of the vacuum chamber 10 is 100–300 mm, and the material can be any of stainless steel, aluminum alloy, or PEEK. The evaporation base 20 can be made of any of stainless steel, aluminum alloy, or PEEK. The height of the portion of the evaporation base 20 above the inner bottom surface of the vacuum chamber 10 can be 30–80 mm. When the first mounting hole is square, the side length of the portion of the evaporation base 20 above the inner bottom surface of the vacuum chamber 10 is 120–200 mm, slightly larger than the first mounting hole, to ensure a tight fit between the evaporation base 20 and the first mounting hole, preventing liquid injected into the vacuum chamber 10 from leaking out through the gap between the evaporation base 20 and the first mounting hole, thus affecting the device's performance. The height of the liquid dam 30 can be 2–10 mm, and the diameter is 60–100 mm. The material is either polytetrafluoroethylene (PTFE) or PEEK. The liquid dam 30 is mainly used to prevent liquid from submerging the test surface. The upper heating block 40 and the lower heating block 50 can be made of oxygen-free copper. The upper heating block 40 and the lower heating block 50 are mainly used for heat conduction and providing the required heat flux density. In this embodiment, the spiral condenser 60 is connected to the low-temperature thermostatic bath. The spiral condenser 60 can be spring-type and is used to cool the phase change working fluid in the vacuum chamber 10, maintaining the dynamic balance of the working fluid level. In this embodiment, sealing elements are provided at the connections of each component. The sealing elements can be at least one of O-rings, vacuum screws, and pneumatic seals. The O-rings are made of nitrile rubber, fluororubber, silicone, or fluorosilicone rubber. The working fluid can be any one of distilled water, electronic fluorinated liquid, deionized water, ethanol, or a refrigerant.

[0056] The thin-film boiling heat transfer enhancement device disclosed herein can be used to observe the thin-film boiling heat transfer mechanism of different test pieces. It employs a split heating block, dividing the heating block into an upper heating block and a lower heating block. This split design allows the test piece to be directly sintered onto the upper surface of the upper heating block, reducing contact thermal resistance and enabling a deep replication of the internal working conditions of the heat pipe. Furthermore, the device uses physical confinement (i.e., a liquid dam) to prevent liquid immersion at the top of the test piece. This method maintains the surrounding liquid level slightly higher than the test piece, ensuring continuous replenishment of liquid to the evaporation center from the side via capillary suction, while avoiding any risk of immersion. Therefore, no active, precise liquid level control is required to match the height of the test piece. This disclosure can also investigate the effect of the heat source on enhancing thin-film boiling heat transfer by changing the shape and area of ​​the upper surface of the split heating block.

[0057] Figure 2A and Figure 2B The schematic diagram illustrates the structure of the vacuum chamber of a thin liquid film boiling heat transfer enhancement device according to an embodiment of the present disclosure.

[0058] like Figure 2A and Figure 2BAs shown, in one embodiment of this disclosure, the vacuum cavity includes a vacuum cavity body 12. The bottom of the vacuum cavity body 12 is provided with the first mounting hole. An auxiliary heating rod mounting hole 13 and a first thermocouple mounting hole 14 are provided on one side of the vacuum cavity body 12. The auxiliary heating rod mounting hole 13 is used to install an auxiliary heating rod to heat the liquid pool in the vacuum cavity 10 to a saturated state. Side observation windows 15 are provided on the side of the vacuum cavity body 12 where the auxiliary heating rod mounting hole 13 is not provided.

[0059] In this embodiment, the vacuum chamber 10 includes a vacuum chamber body 12, as referenced. Figure 2A and Figure 2B An auxiliary heating rod mounting hole 13 and a first thermocouple mounting hole 14 are provided on one side of the vacuum chamber 12. The auxiliary heating rod mounting hole 13 is used to install an auxiliary heating rod, which is mainly used to heat the liquid pool in the vacuum chamber 10 to a saturated state. In this embodiment, two first thermocouple mounting holes 14 are provided, and a thermocouple is installed in each first thermocouple mounting hole 14. One thermocouple is used to measure the temperature of the liquid pool, and the other thermocouple is used to measure the vapor temperature in the vacuum chamber 10. The specific number of first thermocouple mounting holes can be set according to actual needs and is not limited here. Continue to refer to Figure 2A and Figure 2B Side observation windows 15 are provided on the other sides of the vacuum chamber 12 that do not have auxiliary heating rod mounting holes 13 and first thermocouple mounting holes 14. The side observation windows 15 on both the left and right sides facilitate the illumination of the interior of the vacuum chamber using a cold light source. A transparent heating film can also be attached to the side observation windows 15 to prevent water mist generated during the phase change of the working fluid inside the vacuum chamber from affecting the visualization effect.

[0060] The thin liquid film boiling heat transfer enhancement device disclosed herein has a side observation window on the side of the vacuum chamber, which facilitates observation of the situation inside the vacuum chamber during testing. For example, the vacuum level inside the vacuum chamber can be changed to observe the thin liquid film boiling heat transfer effect when the vacuum level inside the vacuum chamber is different.

[0061] In one embodiment of this disclosure, a top observation window can be opened on the upper surface of the vacuum cavity 10, and a high-speed camera can be fixed on the upper surface of the vacuum cavity 10, with the high-speed camera positioned above the top observation window, so as to facilitate observation of the situation inside the vacuum cavity using the high-speed camera.

[0062] Figure 3 The schematic diagram illustrates the structure of the vacuum chamber of another thin liquid film boiling heat transfer enhancement device provided in an embodiment of the present disclosure.

[0063] like Figure 3As shown, in one embodiment of this disclosure, the vacuum chamber further includes a condenser cover plate 16 connected to the top of the vacuum chamber 12. The condenser cover plate 16 has a spiral condenser tube mounting hole 17, a pressure gauge mounting hole 18, and a vacuum system connection hole 19. The liquid inlet and liquid outlet of the spiral condenser tube 60 extend to the outside of the vacuum chamber 10 through the spiral condenser tube mounting hole 17. The pressure gauge mounting hole 18 is used to connect a pressure sensor, and the vacuum system connection hole 19 is used to connect a vacuum system.

[0064] In this embodiment, in addition to the vacuum chamber body 12 described above, the vacuum chamber 10 also includes a condenser cover plate 16. The condenser cover plate 16 is connected to the top of the vacuum chamber body 12, and the condenser cover plate 16 is also provided with a spiral condenser tube mounting hole 17, a pressure gauge mounting hole 18, and a vacuum system connection hole 19. The liquid inlet and liquid outlet of the spiral condenser tube 60 extend to the outside of the vacuum chamber 10 through the spiral condenser tube mounting hole 17, as can be seen from... Figure 9 The pressure gauge mounting hole 18 is used to install a pressure gauge, and the vacuum system connection hole 19 is used to connect a vacuum system. In this embodiment, the thickness of the condenser cover plate 16 can be 5-20 mm, and the length can be 60-300 mm.

[0065] Figure 4A and Figure 4B The schematic diagram illustrates the structure of an evaporation base of a thin liquid film boiling heat transfer enhancement device according to an embodiment of the present disclosure.

[0066] like Figure 4A and Figure 4B As shown, in one embodiment of this disclosure, the lower surface of the evaporation base 20 is provided with a first groove 22, the bottom of the first groove 22 is provided with a second groove 23, the bottom of the second groove 23 is provided with a second mounting hole, and the lower heating block 50 is disposed in the first groove 22; the upper surface of the evaporation base 20 is provided with a third groove 24, and the third groove 24 and the second groove 23 are connected through the second mounting hole; the width of the first groove 22 is greater than the width of the second groove 23 and the third groove 24, the width of the second groove 23 and the third groove 24 is greater than the width of the second mounting hole, and the width of the third groove 24 is greater than or equal to the width of the second groove 23; the inner surface of the first groove 22 is provided with a thermocouple wire fixing groove 25, one end of the thermocouple wire fixing groove 25 is connected to the second groove 23, and the other end of the thermocouple wire fixing groove 25 is connected to the lower surface of the evaporation base 20.

[0067] In this embodiment, the evaporation base 20 has a first groove 22, a second groove 23, and a third groove 24. The first groove 22 is located at the bottom of the evaporation base 20, the second groove 23 is located at the bottom of the first groove 22, and the third groove 24 is located at the top of the evaporation base 20. The third groove 24 and the second groove 23 are connected through a second mounting hole. Specifically, the width of the third groove 24 is greater than or equal to the width of the second groove 23, and the widths of both the third groove 24 and the second groove 23 are less than the width of the first groove 22. A thermocouple wire fixing groove 25 is also provided on the inner surface of the first groove 22. Figure 4B One end of the thermocouple wire fixing groove 25 extends to the second groove 23, and the other end extends to the bottom surface of the first groove 22.

[0068] Figure 5 The schematic diagram illustrates the structure of a thin liquid film boiling heat transfer enhancement device according to an embodiment of the present disclosure.

[0069] like Figure 5 As shown, in one embodiment of this disclosure, the upper heating block 40 includes a heating plate 41 installed in the third groove 24, the upper surface of the heating plate 41 and the upper surface of the evaporation base 20 being in the same horizontal plane; a connecting pipe 42, one end of which is connected to the lower surface of the heating plate 41, and the other end of which is fitted with a lower heating block 50; three second thermocouple mounting holes 43 are provided on the connecting pipe 42, the three second thermocouple mounting holes 43 are equidistantly arranged, and thermocouple elements are installed in the second thermocouple mounting holes 43 for collecting the temperature of the heating plate 41.

[0070] In this embodiment, the upper heating block 40 includes an upper heating plate 41 and a connecting pipe 42. The connecting pipe 42 is connected to the lower surface of the upper heating plate 41. The upper heating plate 41 is located in the third groove 24 opened on the evaporation base 20. The connecting pipe 42 extends through the second mounting hole and the second groove 23 into the first groove 22 of the evaporation base 20. The connecting pipe 42 is provided with three equally spaced second thermocouple mounting holes 43. The three second thermocouple mounting holes 43 are located on the part of the connecting pipe 42 located in the second groove 23. The three second thermocouple mounting holes 43 are all used to install thermocouple elements. The thermocouples in the three second thermocouple mounting holes 43 are all used to collect the temperature of the upper heating plate 41.

[0071] In this embodiment, the upper heating block 40 includes an upper heating plate 41 with a thickness of 1-2 mm and a connecting tube 42 with a length of 25 mm. 10 mm of the tube extends into the lower heating block 50 for cooperation, and the remaining 15 mm is arranged with second thermocouple mounting holes 43 at 5 mm intervals. The size of the second thermocouple mounting holes 43 is 0.5-1 mm. In this embodiment, the thermocouple element is a T-type thermocouple. After installation, the thermocouple element is fixed with copper foil tape. It can be used with an Agilent data acquisition device to collect the temperature of the upper heating plate. Combined with the boiling phenomenon in the vacuum chamber captured by a high-speed camera, changes in bubbles, temperature, and pressure can be analyzed. During testing, a test piece is sintered on the upper surface of the upper heating plate 41. The test piece can be at least one of various liquid-absorbing wick structures, micro / nano structures, superphilic / hydrophobic structures, coating surfaces, and electrochemically deposited surfaces. During testing, the vacuum level in the vacuum chamber is adjusted to study the boiling heat transfer of thin liquid films under different vacuum levels.

[0072] Figure 6A and Figure 6B The schematic diagram illustrates the structure of the lower heating block of a thin liquid film boiling heat transfer enhancement device according to an embodiment of the present disclosure.

[0073] like Figure 6A and Figure 6B As shown, in one embodiment of this disclosure, a fourth groove 51 is provided on the upper surface of the lower heating block 50, and the lower heating block 50 is sleeved on the bottom of the upper heating block 40 through the fourth groove 51; a first heating wire mounting hole 52 is provided at the bottom of the fourth groove 51.

[0074] In this embodiment, the lower heating block 50 is provided with a fourth groove 51 and a first heating wire mounting hole 52, wherein the first heating wire mounting hole 52 is opened at the bottom of the fourth groove 51, and the lower heating block 50 is sleeved on the lower end of the upper heating block 40 through the fourth groove 50.

[0075] Figure 7 The schematic diagram illustrates the structure of another thin liquid film boiling heat transfer enhancement device provided in an embodiment of the present disclosure.

[0076] like Figure 7 As shown, in one embodiment of this disclosure, the thin liquid film boiling heat transfer enhancement device further includes: a plate heating element disposed on the side of the lower heating block 50; and an insulating sleeve 70 covering the surface of the lower heating block 50 on which the plate heating element is disposed.

[0077] In this embodiment, a plate-type heating element is provided on the side of the lower heating block 50, which is in close contact with the perimeter of the lower heating block 50. An insulating material is also wrapped around the outside of the plate-type heating element, and an insulating sleeve 70 is provided outside the insulating material. The upper surface of the insulating sleeve 70 is directly connected to the evaporation base 20. The insulating material can be aerogel felt or thermal insulation cotton, and the material of the insulating sleeve 70 can be epoxy resin or polytetrafluoroethylene. Providing plate-type heating elements and an insulating sleeve on the outside of the lower heating block can better ensure the temperature of the upper surface of the upper heating block.

[0078] Figure 8 The schematic diagram illustrates the structure of another thin liquid film boiling heat transfer enhancement device provided in an embodiment of the present disclosure.

[0079] like Figure 8 As shown, in one embodiment of this disclosure, the thin liquid film boiling heat transfer enhancement device further includes: an evaporation base cover plate 26, which is connected to the lower surface of the evaporation base 20, and a second heating wire mounting hole 27 is provided on the evaporation base cover plate 26.

[0080] In this embodiment, the lower surface of the evaporation base 20 is covered by an evaporation base cover plate 26. The evaporation base cover plate 26 has a second heating wire mounting hole 27. In this embodiment, the evaporation base cover plate 26 is bolted to the lower surface of the vacuum chamber 10. Providing an evaporation base cover plate on the lower surface of the evaporation base further ensures the temperature of the upper heating block mounted on the evaporation base.

[0081] Figure 9 The schematic diagram illustrates the structure of another thin liquid film boiling heat transfer enhancement device provided in an embodiment of the present disclosure.

[0082] like Figure 9 As shown, in one embodiment of this disclosure, the thin liquid film boiling heat transfer enhancement device further includes a support 1, and a vacuum chamber 10 is mounted on the support 1.

[0083] To further ensure the performance of the device, in this embodiment, the vacuum chamber 10 is mounted on the bracket 1, which can ensure that the device remains stable during testing. The bracket 1 can be made of stainless steel, aluminum alloy, or other metal materials, with a side length of 70–320 mm and a support leg height of 30–100 mm.

[0084] When using the apparatus provided in this disclosure for testing, the following steps can be followed:

[0085] The first step is to install the test sample and seal the vacuum chamber. Then, degassed deionized water is injected into the vacuum chamber so that the level of the deionized water is slightly higher than the upper surface of the test sample but lower than the upper surface of the liquid dam.

[0086] To completely remove non-condensable gases, this step requires heating the deionized water to a vigorous boil for at least 2 hours.

[0087] The second step is to heat the liquid pool inside the vacuum chamber to the saturation temperature at the current pressure. Simultaneously, the pressure inside the vacuum chamber is adjusted to be slightly higher than atmospheric pressure.

[0088] The third step is to keep the pressure constant during the test, while keeping the deionized water level at the same position.

[0089] The fourth step is to increase the temperature of the upper heating block and determine the test status based on the temperature of the upper heating block. When the temperature change of the upper heating block does not exceed 0.1℃ within 10 minutes, it is determined that a steady state has been reached, and all data are recorded.

[0090] Fifth, continue to increase the temperature of the upper heating block until the deionized water on the upper surface of the upper heating block is completely dried, and the test ends.

[0091] Completely burning out in this step refers to a sudden and rapid increase in the temperature of the three thermocouples on the upper heating block.

[0092] Those skilled in the art will understand that the features described in the various embodiments and / or claims of this disclosure can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in this disclosure. In particular, the features described in the various embodiments and / or claims of this disclosure can be combined and / or combined in various ways without departing from the spirit and teachings of this disclosure. All such combinations and / or combinations fall within the scope of this disclosure.

[0093] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although this disclosure has been shown and described with reference to specific exemplary embodiments, those skilled in the art will understand that various changes in form and detail may be made to this disclosure without departing from the spirit and scope of this disclosure as defined by the appended claims and their equivalents. Therefore, the scope of this disclosure should not be limited to the above embodiments, but should be determined not only by the appended claims but also by their equivalents.

Claims

1. A thin-film boiling heat transfer enhancement device, characterized in that, include: The vacuum chamber (10) has a first mounting hole at the bottom; An evaporation base (20) is installed in the first mounting hole, and the upper surface of the evaporation base (20) is higher than the inner bottom surface of the vacuum chamber (10). A second mounting hole is provided on the upper surface of the evaporation base (20). A liquid dam (30) is disposed on the upper surface of the evaporation base (20). A test hole (31) of a preset size is provided at the center of the liquid dam (30). The size of the test hole (31) is larger than the size of the second mounting hole. The upper heating block (40) is installed in the second mounting hole, and the upper surface of the upper heating block (40) and the upper surface of the evaporation base (20) are located in the same horizontal plane; The lower heating block (50) is disposed inside the evaporation base (20), and the lower heating block (50) is sleeved on the bottom of the upper heating block (40); A spiral condenser tube (60) is disposed in the vacuum chamber (10), and the lower end of the spiral condenser tube (60) is spaced at a predetermined distance from the upper surface of the evaporation base (20). The centers of the spiral condenser (60), the evaporation base (20), the liquid dam (30), the upper heating block (40), and the lower heating block (50) are located on the same straight line, and the straight line is perpendicular to the horizontal plane.

2. The thin liquid film boiling heat transfer enhancement device according to claim 1, characterized in that, The vacuum chamber (10) includes: A vacuum chamber (12) is provided with the first mounting hole at the bottom of the vacuum chamber (12). An auxiliary heating rod mounting hole (13) and a first thermocouple mounting hole (14) are provided on one side of the vacuum chamber (12). The auxiliary heating rod mounting hole (13) is used to install an auxiliary heating rod to heat the liquid pool in the vacuum chamber (10) to a saturated state. A side observation window (15) is provided on the side of the vacuum chamber (12) where the auxiliary heating rod mounting hole (13) is not provided.

3. The thin liquid film boiling heat transfer enhancement device according to claim 2, characterized in that, The vacuum chamber (10) further includes: A condenser cover (16) is connected to the top of the vacuum chamber (12). The condenser cover (16) has a spiral condenser tube mounting hole (17), a pressure gauge mounting hole (18), and a vacuum system connection hole (19). The liquid inlet and liquid outlet of the spiral condenser tube (60) extend to the outside of the vacuum chamber (10) through the spiral condenser tube mounting hole (17). The pressure gauge mounting hole (18) is used to connect a pressure sensor, and the vacuum system connection hole (19) is used to connect a vacuum system.

4. The thin liquid film boiling heat transfer enhancement device according to claim 1, characterized in that, The evaporation base (20) has a first groove (22) on its lower surface, a second groove (23) is provided at the bottom of the first groove (22), a second mounting hole is provided at the bottom of the second groove (23), and the lower heating block (50) is disposed in the first groove (22). The evaporation base (20) has a third groove (24) on its upper surface, and the third groove (24) and the second groove (23) are connected through the second mounting hole; The width of the first groove (22) is greater than the width of the second groove (23) and the third groove (24), the width of the second groove (23) and the third groove (24) is greater than the width of the second mounting hole, and the width of the third groove (24) is greater than or equal to the width of the second groove (23). The inner surface of the first groove (22) is provided with a thermocouple wire fixing groove (25). One end of the thermocouple wire fixing groove (25) is connected to the second groove (23), and the other end of the thermocouple wire fixing groove (25) is connected to the lower surface of the evaporation base (20).

5. The thin liquid film boiling heat transfer enhancement device according to claim 4, characterized in that, The upper heating block (40) includes: A heating plate (41) is installed in the third groove (24), and the upper surface of the heating plate (41) and the upper surface of the evaporation base (20) are located in the same horizontal plane; A connecting pipe (42) is provided, one end of which is connected to the lower surface of the heating plate (41), and the other end of which is fitted with the lower heating block (50). Three second thermocouple mounting holes (43) are provided on the connecting pipe (42), and the three second thermocouple mounting holes (43) are equidistantly arranged. A thermocouple element is installed in the second thermocouple mounting hole (43), and the thermocouple element is used to collect the temperature of the heating plate (41).

6. The thin-film boiling heat transfer enhancement device according to claim 1, characterized in that, The upper surface of the lower heating block (50) is provided with a fourth groove (51), and the lower heating block (50) is sleeved on the bottom of the upper heating block (40) through the fourth groove (51); The bottom of the fourth groove (51) is provided with a first heating wire mounting hole (52).

7. The thin liquid film boiling heat transfer enhancement device according to claim 1, characterized in that, The device further includes: Plate heating elements are disposed on the side of the lower heating block (50); An insulating sleeve (70) covers the surface of the lower heating block (50) on which the plate heating element is provided.

8. The thin liquid film boiling heat transfer enhancement device according to claim 1, characterized in that, An observation window is provided on the upper surface of the vacuum chamber (10), and the device further includes: A high-speed camera is fixed to the upper surface of the vacuum cavity (10) and located above the observation window.

9. The thin liquid film boiling heat transfer enhancement device according to claim 1, characterized in that, The device further includes: An evaporation base cover plate (26) is connected to the lower surface of the evaporation base (20), and a second heating wire mounting hole (27) is provided on the evaporation base cover plate (26).

10. The thin liquid film boiling heat transfer enhancement device according to claim 1, characterized in that, The device further includes: The bracket (1) is on which the vacuum chamber (10) is mounted.

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