Multi-field coupling enhanced phase change heat transfer visualization experiment research device

Abstract

The invention relates to the technical field of phase change heat transfer, and particularly discloses a multi-field coupling enhanced phase change heat transfer visualization experiment research device which comprises a vacuum cavity provided with a heat exchange block mounting hole, an auxiliary cooling device mounting hole, first to fifth thermocouple mounting holes, a wire mounting hole, an electric field, a magnetic field mounting position and an electromagnetic wave incident port. The heat exchange block is mounted in the heat preservation sleeve; the auxiliary cooling device is mounted in the auxiliary cooling device mounting hole; a heating rod mounting hole is formed in the bottom of the end cover; the heating rod is mounted in the heating rod mounting hole; the heat preservation sleeve is installed in the heat exchange block installation hole and provided with an ultrasonic oscillation generating device installation position. The electric field-magnetic field generating device is provided with an electric field generating device and a magnetic field generating device. The influence of the superheat degree and the supercooling degree on enhanced thin liquid film boiling heat transfer and enhanced condensation heat transfer can be researched by changing the heating rod and the heat exchange fluid flow.

Description

Technical Field

[0001] The present invention relates to the technical field of phase change heat transfer, and in particular to a multi-field coupling enhanced phase change heat transfer visualization experimental research device. Background Art

[0002] In recent years, with the rapid development of electronic information technology, especially the increasing power density of high-power electronic devices (such as data center servers, 5G base station radio frequency modules, and new energy vehicle electric drive systems), heat fluxes have exceeded 1000 W / cm², and local temperature rise rates can reach 50°C / s. Therefore, thermal management of electronic chips has become increasingly important. Heat pipes, as highly efficient heat dissipation devices, have been widely used in electronic devices. Their main structure consists of a shell, a wick, and a working fluid. When the heat source temperature rises, heat rapidly diffuses across the entire evaporation surface. The working fluid in the wick, which is in a wet state, begins to undergo a phase change and removes heat. The vapor releases heat at the condensation stage and condenses into liquid, which is then transported back to the evaporation stage via capillary transport, repeating this cycle of heat transfer. Therefore, the capillary limit and the condensation limit are the main factors limiting the maximum heat transfer capacity of heat pipes. The condensation stage absorbs heat from the gaseous working fluid, converting it into liquid. This liquid then flows back to the evaporation stage through the pore structure of the porous medium. The quality of the resulting liquid has a significant impact on the performance of heat pipe-type heat dissipation components. To further enhance the heat transfer performance of heat pipes, researchers have focused on improving the heat transfer performance of the evaporation and condensation sections. The thermal performance of the evaporation and condensation sections can be characterized by the heat transfer coefficient (HTC) and heat transfer capacity (Q). For the evaporation section, evaporation performance is characterized by the critical heat flux (CHF), the onset of nucleate boiling (ONB), and the heat transfer coefficient (HTC). The capillary driving force plays a key role in the CHF, which is inversely proportional to the effective capillary radius, thus requiring a capillary structure with a smaller pore size. However, a smaller pore size leads to a decrease in permeability and an increase in liquid flow resistance, thereby reducing the CHF or HTC. For the condensation section, the heat transfer coefficient for beaded condensation is generally much larger than that for film condensation. This is related to the surface energy of the surface: higher surface energy leads to a more favorable formation of film condensation, while lower surface energy leads to a more favorable formation of beaded condensation. However, for heat pipes, the reflux of the working fluid is also a very critical factor. Surfaces with low surface energy are not easy to absorb liquids, so some of the working fluid may not be able to flow back to the evaporation section to participate in the overall heat exchange of the heat pipe, thereby reducing the heat transfer performance of the heat pipe.

[0003] External physical fields (such as magnetic fields, electric fields, ultrasound, and electromagnetic waves) can further optimize the heat transfer performance of the evaporation section. The introduction of an electric field can increase the formation and shedding rate of droplets, enhance capillary suction, and thus delay the onset of CHF. Ultrasound improves the microscopic disturbance of the liquid, reduces the thickness of the liquid film, and enhances the boiling heat transfer coefficient. External physical fields also play an important role in optimizing the condensation section. For example, applying electric or magnetic fields can promote the rapid shedding of condensate and facilitate its return to the evaporation section. The application of ultrasound can also enhance the drainage of condensate and the detachment of droplets, thereby improving condensation efficiency. Furthermore, the use of low-surface-energy coatings can further optimize the heat transfer efficiency of the evaporation and condensation sections by adjusting the surface hydrophilicity and hydrophobicity. However, the extent and mechanism of the influence of these external physical fields and their combined effects on evaporation and condensation remain to be determined. Therefore, research into the structural design of different wicks within a series of heat pipes, various physical and chemical surface modification methods, and the mechanisms by which external physical fields enhance the evaporation and condensation heat transfer characteristics of porous media, combined with visualization experiments, is crucial for optimizing the design and application of these heat pipes. This research will not only improve the heat transfer performance of heat pipes but also promote their efficient application in practical engineering, and is a key technical issue that needs to be addressed urgently. Summary of the Invention

[0004] In view of the above problems, the present invention provides a multi-field coupling enhanced phase change heat transfer visualization experimental research device.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A multi-field coupling enhanced phase change heat transfer visualization experimental research device, including The vacuum chamber comprises a vacuum chamber body with an opening at one end and an end cap for sealing the opening. The vacuum chamber is provided with a vacuum pumping and liquid injection system installation hole and a drain port, a working fluid area at the bottom of the vacuum chamber, and an observation position on the end cap; The heat exchange block is installed on the vacuum chamber, wrapped by a thermal insulation sleeve, with its end face exposed in the vacuum chamber. The test piece is welded to the end face, and the heat exchange block is connected to a set of temperature control equipment. An auxiliary cooling device is installed on the vacuum chamber to control the temperature of the working medium inside the vacuum chamber. The auxiliary cooling device is connected to an external cooling device and is used to adjust the working medium pressure to the required saturation pressure. The heating rod is installed on the vacuum chamber and immersed in the working fluid to heat the working fluid; An electric field-magnetic field generating device is installed on the vacuum chamber near the test piece, and comprises an electric field generating device and a magnetic field generating device; As a further preferred solution, an electromagnetic wave incident port is further provided on the vacuum cavity, the electromagnetic wave incident port faces the test piece, and the electromagnetic wave transmitter is used to transmit electromagnetic waves to the test piece through the electromagnetic wave incident port.

[0006] As a further preferred solution, an ultrasonic oscillation generating device is provided in the vacuum chamber.

[0007] As a further preferred solution, the heat exchange block includes a horizontally connected heat exchange end and a heat exchange cavity. The test piece is welded to the outer end face of the heat exchange end. The heat exchange cavity contains heat exchange space. The rear end of the heat exchange cavity is sealed with a rear cover plate to seal the heat exchange space. A heat exchange liquid inlet pipe and a heat exchange liquid outlet pipe are provided through the rear cover plate to connect the heat exchange space. The heat exchange liquid inlet pipe and the heat exchange liquid outlet pipe are connected to a set of external temperature control equipment.

[0008] As a further preferred solution, the vacuum chamber is a horizontal barrel structure; A heat exchange block mounting hole is provided at the center of the end surface of the vacuum cavity, and the heat exchange block is installed at the heat exchange block mounting hole in the vacuum cavity; A pair of auxiliary cooling device mounting holes are provided on the vacuum chamber, and the auxiliary cooling device in the vacuum chamber is connected to an external cooling device through the pair of auxiliary cooling device mounting holes; The end cover includes an end cover body, an observation window mounting port at the center of the end cover body, and a heating rod mounting hole at the bottom. A high-speed camera is provided on the outside of the observation window mounting port for observation, and the heating rod is installed at the heating rod mounting hole in the vacuum chamber.

[0009] As a further preferred solution, a first thermocouple mounting port and a second thermocouple mounting port are provided on the heat exchange end, and a third thermocouple mounting port is provided on the heat exchange cavity. The first thermocouple mounting port, the second thermocouple mounting port, and the third thermocouple mounting port are replaced with the hot end thermocouple originals to collect the temperature at various positions of the heat exchange block; The vacuum cavity is equipped with a liquid working medium temperature thermocouple element and a gaseous working medium temperature thermocouple element, which are located above the vacuum cavity and in the working medium liquid respectively.

[0010] As a further preferred embodiment, the insulation cover includes an insulation cover body, on which an upper bolt mounting hole and a lower bolt mounting hole are provided, which correspond to a first fixing hole and a second fixing hole on the inner side of the end surface of the vacuum chamber, respectively, for fixing the insulation cover; An ultrasonic oscillation generating device mounting hole is provided on the insulation cover body for mounting the ultrasonic oscillation generating device. The ultrasonic oscillation generating device corresponds to the third fixing hole on the inner side of the end face of the vacuum cavity, and the third fixing hole is used to fix the ultrasonic oscillation generating device. The insulation sleeve body is also provided with a first thermocouple mounting hole corresponding to the first thermocouple mounting port, a second thermocouple mounting hole corresponding to the second thermocouple mounting port, a third thermocouple mounting hole corresponding to the third thermocouple mounting port, a heat exchange liquid inlet pipe mounting hole corresponding to the heat exchange liquid inlet pipe, and a heat exchange liquid outlet pipe mounting hole corresponding to the heat exchange liquid outlet pipe.

[0011] As a further preferred solution, the end surface of the vacuum chamber is provided with: The first thermocouple mounting hole is used to lead out the data line of the thermocouple component at the heat exchange end in the first thermocouple mounting opening; The second thermocouple mounting hole is used to lead out the data line of the thermocouple original component at the heat exchange end in the second thermocouple mounting port; The third thermocouple installation hole is used to lead out the data line of the thermocouple original component at the heat exchange end in the third thermocouple installation port; The fourth thermocouple mounting hole is used to lead out the data line of the liquid working medium temperature thermocouple original component; The fifth thermocouple mounting hole is used to lead out the data line of the gaseous working medium temperature thermocouple element; The wire installation hole is used to lead out the power supply line of the ultrasonic oscillation generating device.

[0012] The present invention provides a visualization experimental research device for enhancing evaporation / condensation heat transfer under the coupled effects of heat, electromagnetic waves, magnetic fields, and ultrasound. This device can be used to observe the evaporation and condensation heat transfer mechanisms of test pieces. The device utilizes a separate heat exchange block, consisting of a heat exchange end and a heat exchange cavity. This separate design allows the test piece to be sintered directly onto the upper surface of the heat exchange end, reducing contact thermal resistance. Furthermore, the heat exchange block utilizes shielding gases (hydrogen and nitrogen) during the welding process to prevent oxidation of the test piece. This method ensures that the test piece is constantly under the shielding gas, maintaining a high surface energy. The present invention allows the effects of superheat and subcooling on enhanced thin film boiling and condensation heat transfer to be studied by varying the flow rate of the heating rod and heat exchange fluid. The present invention also allows the effects of electric, magnetic, and ultrasonic fields on enhanced thin film boiling and condensation heat transfer to be studied by varying their intensity and position. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2A Schematic diagram of the external structure of the present invention; Figure 2B This is a schematic diagram of the end structure of the present invention; Figure 3 Schematic diagram of the heat exchange block structure; Figure 4 Schematic diagram of the end cover structure; Figure 5 Schematic diagram of the insulation sleeve structure; In the figure: 10 vacuum chamber; 11 vacuum chamber body; 12 heat exchange block mounting hole; 13 auxiliary cooling device mounting hole; 14 electromagnetic wave incident port; 15 drain port; 16 vacuum injection system mounting hole; 17-I first thermocouple mounting hole; 17-II second thermocouple mounting hole; 17-III third thermocouple mounting hole; 17-IV fourth thermocouple mounting hole; 17-V fifth thermocouple mounting hole; 17-VI wire mounting hole; 18-I first fixing hole; 18-II second fixing hole; 18-III third fixing hole; 19-I electric field mounting position; 19-II magnetic field mounting position; 20 heat exchange block; 21 heat exchange end; 22 heat exchange chamber; 23 rear cover; 24 heat exchange liquid Body inlet pipe; 25 heat exchange liquid outlet pipe; 26 first thermocouple installation port; 27 second thermocouple installation port; 28 third thermocouple installation port; 30 auxiliary cooling device; 40 end cover; 41 end cover body; 42 observation window installation port; 43 heating rod installation hole; 50 heating rod; 60 insulation sleeve; 61 insulation sleeve body; 62-I upper bolt installation hole; 62-II lower bolt installation hole; 63 ultrasonic oscillation generating device installation hole; 64-I first thermocouple installation hole; 64-II second thermocouple installation hole; 64-III third thermocouple installation hole; 65-I heat exchange liquid inlet pipe installation hole; 65-II heat exchange liquid outlet pipe installation hole; 70 electric field-magnetic field generating device. DETAILED DESCRIPTION

[0014] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0015] like Figure 1 As shown, the visualization experimental research device for enhancing evaporation / condensation heat transfer under the coupling of heat-electromagnetic wave-magnetic field-ultrasound provided by the present invention includes: The vacuum chamber 10 has a heat exchange block mounting hole on the right side wall, an auxiliary cooling device mounting hole, first to fifth thermocouple mounting holes, and a wire mounting hole on the side wall, first to third fixing holes on the inside, electric field and magnetic field mounting positions on the outside, and an electromagnetic wave incident port on the top side; The vacuum chamber 10 includes a vacuum chamber body 11 with an opening at one end and an end cap 40 for sealing the opening. The vacuum chamber 11 and the end cap 40 form a sealed inner space. A heating rod mounting hole is provided at the bottom of the end cap 40, and an observation position is provided on the end cap 40. The vacuum chamber 11 is provided with a vacuum pumping and liquid injection system installation hole 16 and a drain port 15, and a working medium liquid area at the bottom of the vacuum chamber 11; The heat exchange block 20 is installed in the insulation sleeve 60, and the cooling block should be kept horizontal and higher than the working fluid in the vacuum chamber 10. The end face of the heat exchange block 20 is exposed in the vacuum chamber 10, and the test piece is welded to the end face. The heat exchange block 20 is connected to a set of temperature control equipment. The test piece can be at least one of various wick structures, micro-nanostructured surfaces, super-hydrophobic / super-hydrophobic structures, coated surfaces, and electrochemically deposited surfaces. When studying condensation, the sintered surface dimensions are consistent with those of the upper heat exchange end. When studying evaporation, the sintered surface length needs to be appropriately adjusted so that it hangs below the experimental liquid pool. The specific sintered dimensions can be set based on actual needs and are not limited here.

[0016] The auxiliary cooling device 30 is installed in the auxiliary cooling device installation hole and is located at a position higher than the working fluid in the vacuum chamber 10. The auxiliary cooling device 30 is installed on the vacuum chamber body 11 and is used to control the working fluid temperature inside the vacuum chamber 10. The auxiliary cooling device 30 is connected to a set of cooling equipment outside. The auxiliary cooling device 30 is used to adjust the working fluid pressure to the required saturation pressure; The heating rod 50 is installed in the heating rod installation hole and immersed in the working fluid to heat the working fluid; The thermal insulation sleeve 60 is installed in the installation hole of the heat exchange block.

[0017] The electric field-magnetic field generating device 70 is installed on the vacuum chamber 11 near the test piece. The electric field-magnetic field generating device 70 has an electric field mounting position 19-I and a magnetic field mounting position 19-II. The electric field generating device installed at the electric field mounting position 19-I can polarize polar molecules, reduce the surface tension of the liquid, reduce the surface energy of the liquid, and increase the evaporation rate. At the same time, polarization may promote the spreading of droplets, increase the evaporation area, and significantly accelerate evaporation. The electric field generating device installed at the electric field mounting position 19-I can also attract charged steam molecules to the condensation surface, or change the surface hydrophilicity and hydrophobicity through electrowetting, promote the adsorption and nucleation of steam molecules on the condensation surface, and improve the condensation efficiency. The magnetic field generating device installed at the magnetic field mounting position 19-II can reduce the viscosity and surface tension of the working fluid, and increase the evaporation rate. The magnetic field generating device installed at the magnetic field mounting position 19-II can also affect the distribution of nucleation points during steam condensation, promote uniform nucleation, and reduce condensation lag.

[0018] An electromagnetic wave incident port 14 is also provided on the vacuum chamber 11. The electromagnetic wave incident port 14 faces the test piece. The electromagnetic wave transmitter is used to emit electromagnetic waves to the test piece through the electromagnetic wave incident port 14. The electromagnetic waves are directly acted on the polar molecules through dielectric heating, so that the molecules generate heat by high-frequency oscillation friction, or absorb energy through molecular vibration and rotational energy level resonance, so that the internal temperature rises rapidly and the evaporation rate is enhanced. The electromagnetic waves passing through the electromagnetic wave incident port 14 can also induce surface hydrophilization, drive the steam to migrate directionaly to the low-temperature zone, promote the increase of droplet nucleation density, and enhance the condensation heat exchange efficiency.

[0019] An ultrasonic oscillation generating device is provided in the vacuum cavity 11. Ultrasonic waves generate periodic pressure changes in the liquid, triggering violent oscillation and collapse of cavitation bubbles, destroying the liquid-gas interface layer, enhancing the probability of molecular escape, and increasing the evaporation rate. The ultrasonic oscillation generating device provided in the vacuum cavity 11 can also reduce the nucleation barrier of condensed droplets, increase the density of nucleation points, promote uniform distribution of droplets, and at the same time weaken the adhesion of the liquid film, reduce the thickness of the liquid film, and enhance the condensation heat exchange capacity.

[0020] The diameter of the vacuum chamber 10 in this embodiment is 200-250 mm, and the material can be any one of stainless steel, aluminum alloy or PEEK. The material of the heat exchange block 20 can be oxygen-free copper, and the heat exchange block 40 is mainly used to conduct heat and provide the required heat flux density. The height of the portion of the heat exchange block 20 that is higher than the inner wall of the vacuum chamber 10 can also be set to 75-120 mm. When the heat exchange block mounting hole is square, the distance between the heat exchange liquid inlet pipe and the heat exchange liquid outlet pipe behind the heat exchange block 20 is 10-25 mm, slightly smaller than the heat exchange block mounting hole, so that the heat exchange liquid inlet pipe and the heat exchange liquid outlet pipe behind the heat exchange block can be extended into the heat exchange block mounting hole, avoiding the heat exchange liquid inlet pipe and the heat exchange liquid outlet pipe extending into the interior of the vacuum chamber 10 too long, affecting the device effect. The heat exchange block 20 in this embodiment is externally connected to a set of temperature control equipment, which can provide cooling and heat. In this embodiment, the auxiliary cooling device 30 is connected to the low-temperature thermostat. The auxiliary cooling device can be a vacuum-brazed water-cooled plate, which is used to cool the phase-change working fluid within the vacuum chamber 10 and maintain the dynamic equilibrium of the working fluid level. The diameter of the end cap 40 is 200-250 mm and can be made of any material such as stainless steel, aluminum alloy, or PEEK. The diameter of the heating rod is 10-20 mm and can be made of any material such as stainless steel, aluminum alloy, or PEEK. The insulation sleeve 60 can be made of any material such as phenolic resin, polytetrafluoroethylene, or polystyrene, and is primarily used to maintain the temperature of the heat exchange block 20. In this embodiment, sealing elements are provided at the joints of each component. The sealing elements can be at least one of an O-ring, a vacuum screw, or a pneumatic seal. The O-ring is made of a material such as nitrile rubber, fluororubber, silicone rubber, or fluorosilicone rubber. The working fluid can be any of distilled water, electronic fluoride liquid, deionized water, ethanol, liquid metal, high-temperature lava, or refrigerant. It is used to maintain the dynamic equilibrium of the working fluid level within the vacuum chamber 10.

[0021] The visualization experimental research device for enhancing evaporation / condensation heat transfer under the coupled effects of heat, electromagnetic waves, magnetic fields, and ultrasound, provided by the present invention, can be used to observe the evaporation and condensation heat transfer mechanisms of different test pieces under different physical fields. It utilizes a separate heat exchange block, which is divided into a heat exchange end and a heat exchange cavity. This separate design allows the test piece to be sintered directly onto the upper surface of the heat exchange end, reducing contact thermal resistance. Furthermore, the heat exchange block provided by the present invention uses protective gases (hydrogen and nitrogen) during the welding process to prevent oxidation of the test piece. This method keeps the test piece under the protective gas, ensuring that its surface maintains a high surface energy. The present invention also allows the effects of superheat and subcooling on enhanced thin-film boiling heat transfer and condensation to be studied by varying the flow rates of the heating rod and the water exchange water.

[0022] Figure 2A and Figure 2B The schematic diagram shows the structure of the vacuum chamber of a multi-field coupling enhanced phase change heat transfer visualization experimental research device provided by one embodiment of the present invention.

[0023] like Figure 2A and Figure 2B As shown, in one embodiment of the present invention, the vacuum chamber 11 is a horizontal barrel structure; a heat exchange block mounting hole 12 is provided at the center position of the end surface of the vacuum chamber 11, and the heat exchange block 20 is installed at the heat exchange block mounting hole 12 in the vacuum chamber 11; a pair of auxiliary cooling device mounting holes 13 are provided on the vacuum chamber 11, and the auxiliary cooling device 30 in the vacuum chamber 11 is connected to a set of external cooling equipment through a pair of the auxiliary cooling device mounting holes 13; the end cover 40 includes an end cover body 41, and an observation window mounting port 42 at the center of the end cover body 41 and a heating rod mounting hole 43 at the bottom, wherein a high-speed camera is provided on the outside of the observation window mounting port 42 for observation, and the heating rod 50 is installed at the heating rod mounting hole 43 in the vacuum chamber 11.

[0024] The end surface of the vacuum chamber 11 is provided with: a first thermocouple mounting hole 17-I, for leading out the data line of the thermocouple element at the heat exchange end in the first thermocouple mounting port 26; a second thermocouple mounting hole 17-Ⅱ, for leading out the data line of the thermocouple element at the heat exchange end in the second thermocouple mounting port 27; a third thermocouple mounting hole 17-Ⅲ‌, for leading out the data line of the thermocouple element at the heat exchange end in the third thermocouple mounting port 28; a fourth thermocouple mounting hole 17- ‌Ⅳ, for leading out the data line of the liquid working fluid temperature thermocouple element; a fifth thermocouple mounting hole 17-V, for leading out the data line of the gaseous working fluid temperature thermocouple element; and a wire mounting hole 17-VI, for leading out the power supply line of the ultrasonic oscillation generating device.

[0025] The liquid injection system mounting hole 16 is used to inject the working fluid into the vacuum chamber 10. An electromagnetic wave incident port 14 is provided on the vacuum chamber. The size of the electromagnetic wave incident port 14 is 10~50mm. The sample inside the vacuum chamber can be irradiated by an electromagnetic wave generating device through the electromagnetic wave incident port 14. A drain port 15 is provided at the bottom of the vacuum chamber to discharge the liquid inside the vacuum chamber 10.

[0026] like Figure 3 The heat exchange block 20 includes a horizontally connected heat exchange end 21 and a heat exchange cavity 22. The test piece is welded to the outer end surface of the heat exchange end 21. There is a heat exchange space in the heat exchange cavity 22. The rear end of the heat exchange cavity 22 is sealed by a rear cover plate 23 to seal the heat exchange space. A heat exchange liquid inlet pipe 24 and a heat exchange liquid outlet pipe 25 are provided through the rear cover plate 23 to connect the heat exchange space. The heat exchange liquid inlet pipe 24 and the heat exchange liquid outlet pipe 25 are connected to a set of external temperature control equipment.

[0027] A first thermocouple mounting port 26 and a second thermocouple mounting port 27 are provided on the heat exchange end 21, and a third thermocouple mounting port 28 is provided on the heat exchange cavity 22. The first thermocouple mounting port 26, the second thermocouple mounting port 27, and the third thermocouple mounting port 28 are replaced with hot end thermocouple elements for collecting the temperature at various positions of the heat exchange block 20; specifically, the thermocouples at the first thermocouple mounting port 26 and the second thermocouple mounting port 27 are used to collect the temperature of the cooling block, and the thermocouple at the third thermocouple mounting port 28 is used to determine the heat transfer of the heat exchange block.

[0028] The length and width of the heat exchange end 21 are 20-60 mm, and the thickness is 30-50 mm. The thickness of the heat transfer cavity 22 is 30-50 mm, and the thickness of the cover plate 23 is 5-10 mm. After applying solder paste between the upper heat exchange block, the heat transfer cavity, and the cover plate, they are placed in a furnace with a protective gas atmosphere for welding. The welding method can be any of thermal diffusion welding and brazing. Figure 3The three thermocouple mounting openings 26-28 are 1-1.5 mm in size and 5-20 mm apart. In this embodiment, the thermocouple elements are armored T-type thermocouples. After installation, the thermocouple elements are secured with elastic bands. They can be used with an Agilent data acquisition system to collect the temperature of the cooling block. Combined with the condensation phenomenon within the vacuum chamber captured by a high-speed camera, changes in temperature, supercooling, and pressure can be analyzed. The diameters of the heat transfer liquid inlet 24 and the heat transfer liquid outlet 25 are 4-6 mm, with a spacing of 10-25 mm. During testing, a test piece is sintered on the upper surface of the upper heat exchange end 21. The test piece can be at least one of various types of wick structures, micro-nanostructured surfaces, superphilic / hydrophobic structured surfaces, coated surfaces, and electrochemically deposited surfaces. When studying condensation, the sintered surface size is consistent with that of the upper heat exchange end 21. When studying evaporation, the length of the sintered surface needs to be appropriately adjusted so that the sintered surface hangs below the liquid pool during the experiment. The specific sintered size can be set according to actual needs and is not limited here. During the test, the vacuum degree and the temperature of the heat transfer liquid in the vacuum chamber were adjusted to study the evaporation heat transfer under different vacuum degrees and superheat degrees, and the condensation heat transfer under different vacuum degrees and subcooling degrees. The vacuum cavity 11 also has a built-in thermocouple element for the temperature of the liquid working medium and a built-in thermocouple element for the temperature of the gas working medium, which are located above the vacuum cavity 11 and in the working medium liquid respectively.

[0029] like Figure 4 As shown, in one embodiment of the present invention, an observation window mounting groove 42 is provided in the middle of the end cover body 41 , and a heating rod mounting hole 43 is provided at the bottom.

[0030] In this embodiment, the end cap 10 includes an end cap body 41. Figure 4 An observation window mounting slot 42 is defined in the center of the end cap body 41. The size of the observation window mounting slot 42 is 80-120 mm. The specific size of the observation window mounting slot can be adjusted based on actual needs. A cold light source can be used through the observation window mounting slot 42 to illuminate the interior of the vacuum chamber and observe condensation on the surface of the cooling block. A transparent heating film can also be applied to the side observation windows 42 to prevent the working fluid inside the vacuum chamber from generating mist during phase changes, which could affect visualization. A heater rod mounting hole 43 is defined below the end cap body. A heater rod installed in this hole heats the liquid pool within the vacuum chamber 10 to saturation.

[0031] An electromagnetic wave incident port is set on the top of the vacuum chamber, and electric field and magnetic field installation positions are opened on the outside. During the test, electromagnetic waves are emitted to the sample surface through the electromagnetic wave incident port. During the test, the position and intensity of the electric field and magnetic field are changed to affect the sample surface, such as changing the wavelength and frequency of the electromagnetic wave, so as to obtain the influence of the wavelength and frequency of the electromagnetic wave in the vacuum chamber on the evaporation and condensation heat transfer effects.

[0032] In one embodiment of the present invention, a top observation window can be opened on the side of the vacuum chamber 10 to enlarge the size of the top observation window, and a high-speed camera can be fixed on the top of the vacuum chamber 10, and the high-speed camera can be located above the top observation window to facilitate observation of the situation inside the vacuum chamber using the high-speed camera.

[0033] like Figure 5 The insulation cover 60 includes an insulation cover body 61, and an upper bolt mounting hole 62-I and a lower bolt mounting hole 62-II are provided on the insulation cover body 61, which correspond to the first fixing hole 18-I and the second fixing hole 18-II on the inner side of the end surface of the vacuum chamber 11, respectively, for fixing the insulation cover 60; The insulation cover body 61 is provided with an ultrasonic oscillation generating device mounting hole 63 for mounting the ultrasonic oscillation generating device. The ultrasonic oscillation generating device corresponds to the third fixing hole 18-III on the inner side of the end surface of the vacuum chamber 11. The third fixing hole 18-III is used to fix the ultrasonic oscillation generating device. The insulation sleeve body 61 is further provided with a first thermocouple mounting hole 64-I corresponding to the first thermocouple mounting port 26, a second thermocouple mounting hole 64-II corresponding to the second thermocouple mounting port 27, a third thermocouple mounting hole 64-III corresponding to the third thermocouple mounting port 28, a heat exchange liquid inlet pipe mounting hole 65-I corresponding to the heat exchange liquid inlet pipe 24, and a heat exchange liquid outlet pipe mounting hole 65-II corresponding to the heat exchange liquid outlet pipe 25; The sizes of the first fixing hole 18 -I and the second fixing hole 18 -II are 4 to 12 mm, the size of the third fixing hole 18 -III is 5 to 50 mm, and the number of the third fixing hole 18 -III can be 1 to 8.

[0034] The thickness of the insulation cover body 61 is 15~30mm, the diameter of the upper threaded mounting hole 62-I and the lower threaded mounting hole 62-II is 4~12mm, the number of ultrasonic oscillation generating device mounting holes 63 is 1~8, and the diameter is 5~50mm. In this example, the ultrasonic generator mounting holes can be installed with multiple distributed ultrasonic generating devices. The specific number of ultrasonic oscillation generating device mounting holes can be set according to actual needs and is not limited here. Continue to refer to Figure 5 The diameters of the first thermocouple mounting holes 64-I, the second thermocouple mounting holes 64-II, and the third thermocouple mounting holes 64-III range from 1.5 to 2 mm, with a spacing of 5 to 20 mm. The diameters of the heat exchange liquid inlet pipe mounting holes 65-I and the heat exchange liquid outlet pipe mounting holes 65-II range from 4.5 to 6.5 mm, with a spacing of 10 to 25 mm. During testing, the number, location, and intensity of the ultrasonic generators can be adjusted. The evaporation and condensation heat transfer under different ultrasonic distributions and intensities can be studied by combining the temperature of the heat exchange block collected by an Agilent data logger with the evaporation and condensation phenomena captured by a high-speed camera within the vacuum chamber.

[0035] When using the device provided by the present invention to perform a test, the test can be performed according to the following steps: In the first step, the test sample is installed and the vacuum chamber is sealed, and then degassed deionized water is injected into the vacuum chamber so that the liquid level of the deionized water is lower than the height of the test sample but higher than the height of the heating rod.

[0036] In this step, in order to completely remove non-condensable gases, the deionized water needs to be heated to a vigorous boiling for at least 2 hours.

[0037] The second step is to heat the liquid pool in the vacuum chamber to the saturation temperature of the current pressure. At the same time, the pressure in the vacuum chamber is adjusted so that the pressure in the vacuum chamber is slightly higher than the atmospheric pressure.

[0038] In the third step, the pressure was kept constant during the test while the deionized water level was kept at the same level.

[0039] The fourth step is to lower (raise) the temperature of the heat exchange block and determine the test status based on the temperature of the upper heat exchange block. When the temperature change of the upper cooling block does not exceed 0.1°C within 10 minutes, it is determined that the steady state has been reached and all data are recorded.

[0040] Step 5: Continue to lower (raise) the temperature of the heat exchange block until film condensation occurs on the surface of the heat exchange block (the working fluid on the surface is completely burned out), and then end the test.

[0041] The film condensation in this step means that the surface of the upper heat exchange block is completely covered by liquid, and the complete drying means that the temperature of the three thermocouples on the upper heat exchange block suddenly rises.

[0042] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A multi-field coupling enhanced phase change heat transfer visualization experimental research device, characterized by: include The vacuum chamber (10) comprises a vacuum chamber body (11) with an opening at one end and an end cover (40) for sealing the opening, the vacuum chamber body (11) being provided with a vacuum pumping and liquid injection system mounting hole (16) and a drain port (15), a working fluid area at the bottom of the vacuum chamber (11), and an observation position on the end cover (40); The heat exchange block (20) is mounted on the vacuum chamber (11), is externally wrapped by a heat-insulating sleeve (60), has an end face exposed in the vacuum chamber (10), and a test piece is welded to the end face. The heat exchange block (20) is externally connected to a set of temperature control equipment; An auxiliary cooling device (30) is installed on the vacuum chamber (11) and is used to control the temperature of the working medium inside the vacuum chamber (10). The auxiliary cooling device (30) is externally connected to a set of cooling equipment. The auxiliary cooling device (30) is used to adjust the working medium gas pressure to a desired saturation pressure. A heating rod (50) is mounted on the vacuum chamber (11) and immersed in the working fluid for heating the working fluid; The electric field-magnetic field generating device (70) is installed on the vacuum chamber (11) at a position close to the test piece, and the electric field-magnetic field generating device (70) has an electric field generating device and a magnetic field generating device.

2. The multi-field coupling enhanced phase change heat transfer visualization experimental research device according to claim 1, characterized in that: The vacuum cavity (11) is further provided with an electromagnetic wave incident port (14), which faces the test piece, and an electromagnetic wave transmitter is used to transmit electromagnetic waves to the test piece through the electromagnetic wave incident port (14).

3. The multi-field coupling enhanced phase change heat transfer visualization experimental research device according to claim 1, characterized in that: An ultrasonic oscillation generating device is provided in the vacuum cavity (11).

4. The multi-field coupling enhanced phase change heat transfer visualization experimental research device according to claim 1, 2 or 3, characterized in that: The heat exchange block (20) includes a heat exchange end (21) and a heat exchange cavity (22) connected horizontally. The test piece is welded to the outer end surface of the heat exchange end (21). A heat exchange space is formed in the heat exchange cavity (22). The rear end of the heat exchange cavity (22) is sealed with a rear cover plate (23). A heat exchange liquid inlet pipe (24) and a heat exchange liquid outlet pipe (25) are provided through the rear cover plate (23) and connected to the heat exchange space. The heat exchange liquid inlet pipe (24) and the heat exchange liquid outlet pipe (25) are connected to an external set of temperature control equipment.

5. The multi-field coupling enhanced phase change heat transfer visualization experimental research device according to claim 4, characterized in that: The vacuum chamber (11) is a horizontal barrel structure; A heat exchange block mounting hole (12) is provided at a center position on an end surface of the vacuum cavity (11), and the heat exchange block (20) is mounted at the heat exchange block mounting hole (12) in the vacuum cavity (11); A pair of auxiliary cooling device mounting holes (13) are provided on the vacuum cavity (11), and the auxiliary cooling device (30) in the vacuum cavity (11) is connected to an external cooling device through the pair of auxiliary cooling device mounting holes (13); The end cover (40) includes an end cover body (41), an observation window mounting opening (42) at the center of the end cover body (41), and a heating rod mounting hole (43) at the bottom, wherein a high-speed camera is provided outside the observation window mounting opening (42) for observation, and the heating rod (50) is installed at the heating rod mounting hole (43) in the vacuum chamber (11).

6. The multi-field coupling enhanced phase change heat transfer visualization experimental research device according to claim 4, characterized in that: The heat exchange end (21) is provided with a first thermocouple mounting port (26) and a second thermocouple mounting port (27), and the heat exchange cavity (22) is provided with a third thermocouple mounting port (28). The first thermocouple mounting port (26), the second thermocouple mounting port (27), and the third thermocouple mounting port (28) are provided with replacement hot end thermocouples for collecting temperatures at various positions of the heat exchange block (20); The vacuum cavity (11) has a built-in liquid working medium temperature thermocouple element and a gaseous working medium temperature thermocouple element, which are located above the vacuum cavity (11) and in the working medium liquid, respectively.

7. The multi-field coupling enhanced phase change heat transfer visualization experimental research device according to claim 6, characterized in that: The thermal insulation sleeve (60) comprises a thermal insulation sleeve body (61), and the thermal insulation sleeve body (61) is provided with an upper bolt mounting hole (62-I) and a lower bolt mounting hole (62-II), which respectively correspond to a first fixing hole (18-I) and a second fixing hole (18-II) on the inner side of the end surface of the vacuum chamber (11), and are used to fix the thermal insulation sleeve (60); An ultrasonic oscillation generating device mounting hole (63) is provided on the insulation sleeve body (61) for mounting the ultrasonic oscillation generating device. The ultrasonic oscillation generating device corresponds to a third fixing hole (18-III) on the inner side of the end surface of the vacuum cavity (11). The third fixing hole (18-III) is used to fix the ultrasonic oscillation generating device. The insulation sleeve body (61) is further provided with a first thermocouple mounting hole (64-I) corresponding to the first thermocouple mounting port (26), a second thermocouple mounting hole (64-II) corresponding to the second thermocouple mounting port (27), a third thermocouple mounting hole (64-III) corresponding to the third thermocouple mounting port (28), a heat exchange liquid inlet pipe mounting hole (65-I) corresponding to the heat exchange liquid inlet pipe (24), and a heat exchange liquid outlet pipe mounting hole (65-II) corresponding to the heat exchange liquid outlet pipe (25).

8. The multi-field coupling enhanced phase change heat transfer visualization experimental research device according to claim 7, characterized in that: The end surface of the vacuum cavity (11) is provided with: A first thermocouple mounting hole (17-I) is used to lead out a data line of a thermocouple component at a heat exchange end in the first thermocouple mounting opening (26); The second thermocouple mounting hole (17-Ⅱ) is used to lead out the data line of the thermocouple original component at the heat exchange end in the second thermocouple mounting port (27); A third thermocouple mounting hole (17-III‌) is used to lead out a data line of a thermocouple component at a heat exchange end in the third thermocouple mounting port (28); The fourth thermocouple mounting hole (17- ‌Ⅳ) is used for leading out the data line of the liquid working medium temperature thermocouple original component; The fifth thermocouple mounting hole (17-V) is used to lead out the data line of the gaseous working medium temperature thermocouple original component; The wire installation hole (17-VI) is used to lead out the power supply line of the ultrasonic oscillation generating device.

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