CN115656256A - Thermal resistance measurement experiment device and method for high-temperature heat pipe liquid absorption core - Google Patents
Thermal resistance measurement experiment device and method for high-temperature heat pipe liquid absorption core Download PDFInfo
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- CN115656256A CN115656256A CN202211329499.1A CN202211329499A CN115656256A CN 115656256 A CN115656256 A CN 115656256A CN 202211329499 A CN202211329499 A CN 202211329499A CN 115656256 A CN115656256 A CN 115656256A
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Abstract
The invention discloses a thermal resistance measurement experiment device and an experiment method for a high-temperature heat pipe liquid absorption core, wherein the device comprises a pressure regulator, a thermocouple fixing piece, a condenser, heat preservation cotton, the liquid absorption core, an air inlet valve, a stainless steel gasket, a copper plate, a G-shaped fastening clamp, a stainless steel upper plate, a germanium glass wall surface, a K-shaped thermocouple, a vacuum pump, an exhaust valve, a vacuum gauge, a heater, a long-wave infrared thermal imager and a data analysis system; the pressure regulator can provide different heating powers; the K-type thermocouple is fixed at a corresponding position in the chamber through a thermocouple fixing piece to realize real-time monitoring of temperature; the stainless steel gasket fixes the liquid absorption core through a bolt, so that the liquid absorption core is completely flattened; the condenser provides enough cooling capacity for the stainless steel upper plate; the vacuum pump can pump the gas in the closed cavity to form a negative pressure environment; the long-wave thermal infrared imager can observe the temperature distribution at the gas-liquid phase interface in the closed cavity through the germanium glass wall surface, so that the measurement result is accurate and effective.
Description
Technical Field
The invention relates to the technical field of phase change heat exchange equipment, in particular to a thermal resistance measurement experiment device and an experiment method for a high-temperature heat pipe liquid absorption core.
Background
A typical heat pipe is comprised primarily of a shell, a wick, end caps, and a working medium that can flow within the pipe. The two ends of the heat pipe are respectively an evaporation section and a condensation section, and the evaporation section and the condensation section are independent and can be exchanged with each other, so that the heat transfer direction of the heat pipe is reversible. The heat load is in contact with the evaporator end housing. Heat is transferred radially through the housing into the wick. This causes the liquid to evaporate, transferring mass from the wick into the enclosure. The added mass in the shell increases the pressure of the vapor at the evaporator end of the tube, creating a pressure differential that drives the vapor flow to the condenser end of the heat pipe. Heat is removed by a heat sink connected at the condensation end. This causes the vapor to condense, displacing the mass of liquid that previously evaporated to the tube envelope. The radial thermal resistance of the heat pipe mainly comprises the heat conduction thermal resistance and the evaporation thermal resistance of the liquid absorption core, and one high-performance heat pipe requires small radial impedance, so that the heat exchange performance is enhanced. Therefore, it is particularly important to study thermal resistance measurements of wicks.
The existing experimental devices for measuring the thermal resistance of the wick include: chinese patent CN202210472196.9 proposes a method for testing the performance of a micro heat pipe and a platform for implementing the method: the method is characterized in that axial temperature distribution and axial thermal resistance are obtained through the design of a heating system, a condensing system, a heat insulation system and a data acquisition system. However, the measuring method can only research the axial thermal resistance of the heat pipe, cannot measure the radial thermal resistance of the liquid absorption core, and cannot represent the thermal performance of the liquid absorption core.
Disclosure of Invention
In order to realize the research on the thermal resistance of the heat pipe liquid absorption core, the invention provides a thermal resistance measurement experimental device and an experimental method of the high-temperature heat pipe liquid absorption core, which are used for researching the thermal resistance of liquid absorption cores in different forms, guiding the selection of the heat pipe liquid absorption core and effectively preventing the occurrence of heat transfer limit.
In order to achieve the purpose, the invention adopts the following design scheme:
a thermal resistance measurement experiment device for a high-temperature heat pipe liquid absorption core comprises a pressure regulator 1, a thermocouple fixing part 2, a condenser 3, heat preservation cotton 4, a liquid absorption core 5, an air inlet valve 6, a stainless steel gasket 7, a copper plate 8, a G-shaped fastening clamp 9, a stainless steel upper plate 10, a germanium glass wall 11, a K-shaped thermocouple 12, a vacuum pump 13, an exhaust valve 14, a vacuum gauge 15, a heater 16, a long-wave thermal infrared imager 17 and a data analysis system 18; the liquid absorption core 5, the pressure regulator 1, the stainless steel gasket 7, the copper plate 8, the stainless steel upper plate 10, the germanium glass wall surface 11 and the K-type thermocouple 12 form an internal test loop; the voltage regulator 1 is connected to a heater 16 through a connecting element, the heater 16 is in direct contact with a copper plate 8 to provide different heating powers, a stainless steel upper plate 10 is positioned on the upper portion of the copper plate 8, a germanium glass wall surface 11 is used for sealing between the stainless steel upper plate 10 and the copper plate 8 to form a closed cavity, and a liquid absorption core 5 is arranged in the closed cavity and placed on the copper plate 8; the K-type thermocouples 12 are respectively arranged on the surface of the liquid absorption core 5 and the bottom of the copper plate 8, and the surface temperature of the liquid absorption core 5 and the bottom temperature of the copper plate 8 are measured; a K-type thermocouple 12 arranged on the surface of the liquid absorption core 5 is fixed at a corresponding position in the closed cavity through a thermocouple fixing piece 2 and is connected to a data acquisition system to realize real-time monitoring of temperature; the stainless steel gasket 7 fixes the liquid absorption core 5 through a bolt, so that the liquid absorption core 5 is completely flattened; the G-shaped fastening clamp 9 is designed in a threaded screwing mode, the range to be clamped can be freely adjusted, the clamping force is large, the copper plate 8 and the stainless steel upper plate 10 are fixed through the movable arm rotating bolt, and the sealing performance of the closed cavity environment is guaranteed; the condenser 3 provides enough cooling capacity on the stainless steel upper plate 10 by a circulating water chilling unit through a cooling channel drilled on the stainless steel upper plate 10; the vacuum pump 13 is used for pumping gas in the closed cavity by controlling the opening and closing of the exhaust valve 14 to form a negative pressure environment and simulate the real pressure in the heat pipe; the air inlet valve 6 controls the balance of the air pressure inside and outside the closed cavity, so that the repeatability of the experiment is ensured; the vacuum gauge 15 monitors the pressure in the closed cavity in real time; the heat insulation cotton 4 is arranged on the outer side of the internal test loop, so that the heat loss of the internal test loop is reduced; the long-wave thermal infrared imager 17 observes temperature distribution at a gas-liquid phase interface in the closed cavity through the germanium glass wall surface 11 and transmits the temperature distribution to the data analysis system 18, so that a measurement result is accurate and effective.
The thickness of the stainless steel gasket 7 is 1.5-2.0 mm, and the stainless steel gasket is in a hollow circular ring shape; four fixing screws are uniformly arranged around the circular ring, and the liquid absorption core 5 is fully fixed and flattened; the thickness of the stainless steel gasket 7 can ensure that sufficient liquid working medium completely infiltrates the liquid absorption core 5 to form an evaporation pool and prevent the working medium from leaking; meanwhile, the stainless steel washer 7 can adjust the tightness up and down through the adjusting nut, so that the evaporation pool is easily compatible with a wide range of types and thicknesses of the liquid absorption cores 5.
The contact surface of the copper plate 8 and the heater 16 is coated with a layer of heat-conducting adhesive, so that the adhesion degree of the contact surface is enhanced, and the heat conductivity is improved.
The heat insulation cotton 4 is made of aerogel, so that the heat insulation effect is good, light, thin and smooth; the heat insulation cotton 4 covers the heater 16, the copper plate 8 and the germanium glass wall surface 11, so that a heat insulation environment is formed, heat loss is reduced, and measurement accuracy is improved.
The thermocouple fixing part 2 is provided with a through hole, and a K-type thermocouple 12 can be arranged in an inner cavity; four K-type thermocouples 12 are uniformly arranged on the surface of the wick 5 and the bottom of the copper plate 8.
The inner wall of the stainless steel upper plate 10 is coated with a super-hydrophobic coating to enhance condensation reflux and accelerate the condensation reflux to reach a steady state; the preparation method of the super-hydrophobic coating comprises the following steps: using organic silicon modified acrylic resin as a film forming substance, n-butanol and xylene as solvents, and nano SiO 2 The light calcium carbonate, the talcum powder and the titanium dioxide are added particles to prepare the coating, wherein the organic silicon modified acrylic resin, the n-butyl alcohol, the dimethylbenzene and the nano SiO 2 The mass ratio of the light calcium carbonate, the talcum powder and the titanium dioxide is 18-22: 22 to 28:38 to 42:1 to 3:2 to 4:4 to 8: 3-5, ultrasonically dispersing the prepared coating for 30-45 min to obtain a super-hydrophobic coating; the upper surface of the copper plate 8 is treated by a peroxidation process: heating the metal oxide solution at 85-95 ℃ for 45-60 min to obtain a micro-nano structure surface and enhance wettability; the metal oxidizing solution is prepared as follows: sodium hypochlorite NaClO 2 NaOH, trisodium phosphate Na 3 PO 4 Mixing with deionized water according to the mass ratio of 2-3: 4-7: 6-9: 81-87, and stirring for 10-15 min by using a magnetic stirrer to obtain the metal oxidation liquid.
The maximum flow rate of the vacuum pump 13 is 3.4-4L/s, and the allowable maximum vacuum pressure is 3.0 multiplied by 10 -2 ～4.5×10 -2 torr, sufficient pumping capacity; the measuring precision of the vacuum gauge 15 is 0.001-0.003 Mpa, the temperature range is-40-100 ℃, the precision is high, and the measurement of the pressure at high temperature is met; the air inlet valve 6 and the air outlet valve 14 are ball valves, are small in friction resistance and good in sealing performance, and are suitable for being quickly opened and closed and accurately controlled.
The germanium glass wall surface 11 is made of optical germanium crystals; an optical film is plated on the outer layer of the germanium glass wall surface 11, so that the transmission capacity of infrared signals is improved; the long-wave thermal infrared imager 17 can convert radiation signals into visual images, and the intensity of radiation is positively correlated with the temperature, and the imaging brightness is also positively correlated with the temperature of an object, so that the long-wave thermal infrared imager can be used for testing the surface temperature distribution of the object; the working spectrum range is 8-14 μm, the highest frame frequency is 200-240 Hz, the temperature measuring range is up to 0-1500 ℃, the thermal sensitivity is 30-50 mK, and the accurate real-time temperature measurement is realized.
A small-sized visual window is reserved on one side between the heat-preservation cotton 4 and the germanium glass wall surface 11, so that the heat loss is reduced as much as possible, and the temperature of a gas-liquid interface in the closed cavity is monitored by a long-wave thermal infrared imager 17; in consideration of the difference in the temperature distribution of the gas-liquid interface, a level monitoring line is set at the gas-liquid interface, and the average value of the temperature at the gas-liquid interface is calculated as the actual temperature by using system analysis software in the data analysis system 18.
The experimental method of the experimental device for measuring the thermal resistance of the high-temperature heat pipe liquid absorption core comprises the steps of fixing a clean liquid absorption core 5 on the upper surface of a copper plate 8 by using a stainless steel gasket 7 and screws, pouring deionized water to completely immerse the liquid absorption core 5, covering a stainless steel upper plate 10 and a germanium glass wall surface 11 on the copper plate 8, and tightly pressing and fixing the copper plate 8 by using a G-shaped fastening clamp 9; closing the air inlet valve 6, opening the exhaust valve 14, opening the vacuum pump 13, and closing the exhaust valve 14 and the vacuum pump 13 in sequence when the indication number of the vacuum gauge is-98 to-95 kPa; opening the pressure regulator 1 and the condenser 3, adjusting the heating power P, and recording the temperature; closing the pressure regulator 1 and the condenser 3 when the temperature of each temperature measuring point is not changed; selecting the average value of a plurality of K-type thermocouples 12 on the surface of the liquid absorption core 5 and at the bottom of the copper plate 8 as the surface temperature T of the liquid absorption core w And temperature T of the lower surface of the copper plate c Measuring the temperature of a gas-liquid interface to be T by a long-wave thermal infrared imager 17 v (ii) a Due to the condensation and reflux effects of the stainless steel upper plate 10, the working medium circulation reaches a relatively stable state, the temperature difference tends to be constant although the temperature continues to rise, and when the difference values of the surface temperature of the liquid absorption core, the lower surface temperature of the copper plate and the gas-liquid interface temperature tend to be constant, the temperature at the moment is selected for calculation, and the evaporation thermal resistance R is calculated eva And thermal conductivity resistance R cond The following formula is provided:
compared with the prior art, the invention has the following advantages:
an internal test loop consisting of the liquid absorption core 5, the pressure regulator 1, the stainless steel gasket 7, the copper plate 8, the stainless steel upper plate 10, the germanium glass wall surface 11 and the K-type thermocouple 12 is compact in structure; the G-shaped fastening clamp 9 is designed in a threaded screwing mode, the range to be clamped can be freely adjusted, the clamping force is large, the copper plate 8 and the stainless steel upper plate 10 are fixed through the movable arm rotating bolt, and the sealing performance of the closed cavity environment is guaranteed; the condenser 3 provides enough cooling capacity on the stainless steel upper plate 10 by using a circulating water chilling unit through a cooling channel drilled on the stainless steel upper plate 10; the air inlet valve 6 controls the air pressure balance inside and outside the closed cavity, so that the experimental repeatability is ensured; the vacuum gauge 15 monitors the pressure in the closed cavity in real time; the heat insulation cotton 4 is arranged on the outer side of the internal test loop, so that the heat loss of the internal test loop is reduced; the inner wall of the stainless steel upper plate 10 is coated with a super-hydrophobic coating through special process treatment to enhance condensation reflux and accelerate the condensation reflux to reach a stable state; the thickness of the stainless steel gasket 7 can be compatible with a wide range of liquid filling amount, and working medium leakage is prevented; meanwhile, the stainless steel gasket 7 can be adjusted up and down by adjusting the tightness of the nut, so that the evaporation pool is easily compatible with the types and thicknesses of the liquid absorption cores 5 in a wide range; four K-type thermocouples 12 are uniformly arranged on the surface of the liquid absorption core 5 and the bottom of the copper plate 8, and the average value of the four K-type thermocouples is calculated, so that the error is reduced, and the measurement precision is improved; the upper surface of the copper plate 8 is treated by a special oxidation process to obtain a micro-nano structure surface, so that the wettability is enhanced; the negative pressure environment of a real heat pipe is simulated, so that the measurement result is more in line with the actual situation; the long-wave thermal infrared imager adopts non-contact measurement, has high response speed and high sensitivity, can realize accurate real-time temperature measurement on a gas-liquid interface, and overcomes the defect that the conventional thermocouple is difficult to capture the gas-liquid interface.
Aiming at the problem that the thermal resistance of the heat pipe liquid absorption core is difficult to measure, the invention provides a thermal resistance measurement experimental device of the high-temperature heat pipe liquid absorption core, and the device has the advantages of reducing heat loss, accurately measuring temperature, avoiding working medium leakage and the like; the structure is compact, and the special structural design can accurately measure the thermal resistance of the liquid absorption core.
Drawings
Fig. 1 is a schematic diagram of a thermal resistance measurement experimental apparatus for a high-temperature heat pipe wick.
Detailed Description
The invention will now be further described with reference to the following examples, and the accompanying drawings:
as shown in figure 1, the thermal resistance measurement experiment device for the high-temperature heat pipe liquid absorption core comprises a pressure regulator 1, a thermocouple fixing part 2, a condenser 3, heat preservation cotton 4, a liquid absorption core 5, an air inlet valve 6, a stainless steel gasket 7, a copper plate 8, a G-type fastening clamp 9, a stainless steel upper plate 10, a germanium glass wall surface 11, a K-type thermocouple 12, a vacuum pump 13, an exhaust valve 14, a vacuum gauge 15, a heater 16, a long-wave thermal infrared imager 17 and a data analysis system 18; the liquid absorption core 5, the voltage regulator 1, the stainless steel gasket 7, the copper plate 8, the stainless steel upper plate 10, the germanium glass wall surface 11 and the K-type thermocouple 12 form an internal test loop; the voltage regulator 1 is connected to a heater 16 through a connecting element, the heater 16 is in direct contact with a copper plate 8 and can provide different heating powers, a stainless steel upper plate 10 is positioned on the upper portion of the copper plate 8, a germanium glass wall surface 11 is used for sealing between the stainless steel upper plate 10 and the copper plate 8 to form a closed cavity, and a liquid absorption core 5 is arranged in the closed cavity and placed on the copper plate 8; the four K-type thermocouples 12 are respectively arranged on the surface of the liquid absorption core 5 and the bottom of the copper plate 8, and the surface temperature of the liquid absorption core 5 and the bottom temperature of the copper plate 8 are measured; the K-type thermocouple 12 arranged on the surface of the liquid absorption core 5 is fixed at a corresponding position in the closed cavity through the thermocouple fixing piece 2 and is connected to a data acquisition system to realize real-time monitoring of temperature; the stainless steel gasket 7 fixes the liquid absorption core 5 through a bolt, so that the liquid absorption core 5 is completely flattened; the G-shaped fastening clamp 9 adopts a threaded precession type design, can freely adjust the range to be clamped, has large clamping force, and ensures the sealing property of the closed cavity environment by fixing the copper plate 8 and the stainless steel upper plate 10 through the rotating bolt of the movable arm; the condenser 3 provides enough cooling capacity on the stainless steel upper plate 10 by a circulating water chilling unit through a cooling channel drilled on the stainless steel upper plate 10; the vacuum pump 13 can pump the gas in the closed cavity by controlling the opening and closing of the exhaust valve 14 to form a negative pressure environment and simulate the real pressure in the heat pipe; the air inlet valve 6 can control the air pressure balance inside and outside the closed cavity, so that the repeatability of the experiment is ensured; the vacuum gauge 15 can monitor the pressure in the closed cavity in real time; the heat insulation cotton 4 is arranged on the outer side of the internal test loop, so that the heat loss of the internal test loop is reduced; the long-wave thermal infrared imager 17 can observe the temperature distribution at the gas-liquid phase interface in the closed cavity through the germanium glass wall surface 11 and transmits the temperature distribution to the data analysis system 18, so that the measurement result is accurate and effective.
As a preferred embodiment of the present invention, the stainless steel gasket 7 has a thickness of 1.5mm and a hollow circular ring shape; four fixing screws are uniformly arranged around the circular ring, so that the liquid absorption core 5 is fully fixed and flattened; the thickness of the stainless steel gasket 7 can ensure that sufficient liquid working medium completely infiltrates the liquid absorption core 5 to form an evaporation pool and prevent the working medium from leaking; meanwhile, the stainless steel washer 7 can adjust the tightness up and down through the adjusting nut, so that the evaporation pool is easily compatible with a wide range of types and thicknesses of the liquid absorption cores 5.
As a preferred embodiment of the invention, the contact surface of the copper plate 8 and the heater 16 is coated with a layer of heat-conducting adhesive, so that the adhesion degree of the contact surface is enhanced and the heat conductivity is greatly improved.
As a preferred embodiment of the invention, the heat-insulating cotton 4 is made of aerogel, so that the heat-insulating effect is good, light, thin and smooth; the heat insulation cotton 4 covers the heater 16, the copper plate 8 and the germanium glass wall surface 11, so that a heat insulation environment is formed, heat loss is greatly reduced, and measurement accuracy is improved.
As a preferred embodiment of the present invention, a through hole is installed in the thermocouple fixing part 2, and a K-type thermocouple 12 may be disposed in the inner chamber; four K-type thermocouples 12 are uniformly arranged on the surface of the wick 5 and the bottom of the copper plate 8.
As a preferred embodiment of the present invention, the inner wall of the stainless steel upper plate 10 is coated with a super-hydrophobic coating to enhance the condensation reflux and accelerate the steady state; the preparation method of the super-hydrophobic coating comprises the following steps: using organic silicon modified acrylic resin as a film forming substance, n-butanol and xylene as solvents, and nano SiO 2 The light calcium carbonate, the talcum powder and the titanium dioxide are used as additive particles to prepare the coating, wherein the organic silicon modified acrylic resin is prepared from n-butyl alcohol, dimethylbenzene and nano SiO 2 The mass ratio of the light calcium carbonate to the talcum powder to the titanium dioxide is 20:25:40:2:3:6:4, ultrasonically dispersing the prepared coating for 30min to obtain a super-hydrophobic coating; the upper surface of the copper plate 8 is treated by a peroxidation process: heating the metal oxide solution at 85-95 ℃ for 45-60 min to obtain a micro-nano structure surface and enhance wettability; the metal oxidizing solution is prepared as follows: sodium hypochlorite NaClO 2 NaOH, trisodium phosphate Na 3 PO 4 Mixing with deionized water at a mass ratio of 2: 5: 8: 85, and stirring with a magnetic stirrer for 10min to obtain metal oxide solution.
As a preferred embodiment of the present invention, the maximum flow rate of the vacuum pump 13 is 3.4L/s, and the maximum allowable vacuum pressure is 4.5X 10 -2 torr, sufficient pumping capacity; the measuring precision of the vacuum gauge 15 is 0.001Mpa, the temperature range is-40 to 100 ℃, the precision is high, and the pressure measurement under high temperature is met; the air inlet valve 6 and the exhaust valve 14 are ball valves, are small in friction resistance and good in sealing performance, and are suitable for being rapidly switched on and switched off and accurately controlled.
In a preferred embodiment of the present invention, the germanium glass wall surface 11 is made of optical grade germanium crystal; an optical film is plated on the outer layer of the germanium glass wall surface 11, so that the transmission capacity of infrared signals is improved; the long-wave thermal infrared imager 17 can convert the radiation signals into visual images, and the intensity of radiation is positively correlated with the temperature, and the imaging brightness is also positively correlated with the temperature of the object, so that the long-wave thermal infrared imager can be used for testing the surface temperature distribution of the object; the working spectrum range is 8-14 μm, the highest frame frequency is 240Hz, the temperature measuring range is up to 0-1500 ℃, the thermal sensitivity is 30mK, and accurate real-time temperature measurement is realized.
As a preferred embodiment of the invention, a small-sized visual window is reserved on one side between the heat-insulating cotton 4 and the germanium glass wall surface 11, so that the heat loss is reduced as much as possible, and the temperature of a gas-liquid interface in the closed cavity is monitored by a long-wave thermal infrared imager 17; in consideration of the difference in the temperature distribution of the gas-liquid interface, a level monitoring line is set at the gas-liquid interface, and the average value of the temperature at the gas-liquid interface is calculated as the actual temperature by using system analysis software in the data analysis system 18.
As shown in fig. 1, the experimental method of the experimental apparatus for measuring the thermal resistance of the high-temperature heat pipe wick of the present invention is that a clean wick 5 is fixed on the upper surface of a copper plate 8 by using a stainless steel gasket 7 and screws, 5ml of deionized water is poured to completely immerse the wick 5, a stainless steel upper plate 10 and a germanium glass wall surface 11 are covered on the copper plate 8 and are compressed and fixed by using a G-shaped fastening clamp 9; closing the inlet valve 6, opening the outlet valve 14, openingThe air pump 13, when the indication number of the vacuum gauge is-95 kPa, the exhaust valve 14 and the vacuum pump 13 are closed in sequence; opening the pressure regulator 1 and the condenser 3, adjusting the heating power P, and recording the temperature; closing the pressure regulator 1 and the condenser 3 when the temperature of each temperature measuring point is not changed; selecting the average value of four K-type thermocouples 12 on the surface of the liquid absorbing core 5 and at the bottom of the copper plate 8 as the surface temperature T of the liquid absorbing core w And temperature T of the lower surface of the copper plate c Measuring the gas-liquid interface temperature T by a long-wave thermal infrared imager 17 v (ii) a Due to the condensation and reflux effects of the stainless steel upper plate 10, the working medium circulation reaches a relatively stable state, the temperature difference tends to be constant although the temperature continues to rise, and when the difference values of the surface temperature of the liquid absorption core, the lower surface temperature of the copper plate and the gas-liquid interface temperature tend to be constant, the temperature at the moment is selected for calculation, and the evaporation thermal resistance R is calculated eva And thermal conductivity resistance R cond The following formula is provided:
Claims (10)
1. the utility model provides a thermal resistance measurement experimental apparatus of high temperature heat pipe imbibition core which characterized in that: the device comprises a pressure regulator (1), a thermocouple fixing piece (2), a condenser (3), heat-insulating cotton (4), a liquid absorption core (5), an air inlet valve (6), a stainless steel gasket (7), a copper plate (8), a G-shaped fastening clamp (9), a stainless steel upper plate (10), a germanium glass wall surface (11), a K-shaped thermocouple (12), a vacuum pump (13), an exhaust valve (14), a vacuum gauge (15), a heater (16), a long-wave thermal infrared imager (17) and a data analysis system (18); the liquid absorption core (5), the voltage regulator (1), the stainless steel gasket (7), the copper plate (8), the stainless steel upper plate (10), the germanium glass wall surface (11) and the K-type thermocouple (12) form an internal test loop; the voltage regulator (1) is connected to a heater (16) through a connecting element, the heater (16) is in direct contact with a copper plate (8) to provide different heating powers, a stainless steel upper plate (10) is positioned at the upper part of the copper plate (8), a germanium glass wall surface (11) is used for sealing between the stainless steel upper plate (10) and the copper plate (8) to form a closed cavity, and a liquid absorption core (5) is arranged in the closed cavity and placed on the copper plate (8); the K-type thermocouples (12) are respectively arranged on the surface of the liquid absorbing core (5) and the bottom of the copper plate (8), and the surface temperature of the liquid absorbing core (5) and the bottom temperature of the copper plate (8) are measured; a K-type thermocouple (12) arranged on the surface of the liquid suction core (5) is fixed at a corresponding position in the closed cavity through a thermocouple fixing piece (2) and is connected to a data acquisition system to realize real-time monitoring of temperature; the stainless steel gasket (7) fixes the liquid absorbing core (5) through a bolt, so that the liquid absorbing core (5) is completely flattened; the G-shaped fastening clamp (9) adopts a threaded precession type design, can freely adjust the range to be clamped, has large clamping force, and ensures the sealing property of the closed cavity environment by fixing the copper plate (8) and the stainless steel upper plate (10) through the rotating bolt of the movable arm; the condenser (3) provides enough cooling capacity on the stainless steel upper plate (10) by utilizing a circulating water chilling unit through a cooling channel drilled on the stainless steel upper plate (10); the vacuum pump (13) is used for pumping gas in the closed cavity by controlling the opening and closing of the exhaust valve (14) to form a negative pressure environment and simulate the real pressure in the heat pipe; the air inlet valve (6) controls the balance of the air pressure inside and outside the closed cavity, so that the repeatability of the experiment is ensured; the vacuum gauge (15) monitors the pressure in the closed cavity in real time; the heat insulation cotton (4) is arranged on the outer side of the internal test loop, so that the heat loss of the internal test loop is reduced; the long-wave thermal infrared imager (17) observes the temperature distribution at the gas-liquid phase interface in the closed cavity through the germanium glass wall surface (11) and transmits the temperature distribution to the data analysis system (18), so that the measurement result is accurate and effective.
2. The experimental apparatus for measuring thermal resistance of a wick for a high temperature heat pipe according to claim 1, wherein: the thickness of the stainless steel gasket (7) is 1.5-2.0 mm, and the stainless steel gasket is in a hollow circular ring shape; four fixing screws are uniformly arranged around the circular ring, and the liquid absorption core (5) is fully fixed and flattened; the thickness of the stainless steel gasket (7) can ensure that sufficient liquid working medium completely infiltrates the liquid absorption core (5) to form an evaporation pool and prevent the working medium from leaking; meanwhile, the stainless steel gasket (7) can be adjusted up and down in tightness through the adjusting nut, so that the evaporation pool can be compatible with wide-range types and thicknesses of the liquid absorbing core (5).
3. The experimental apparatus for measuring thermal resistance of a wick for a high temperature heat pipe according to claim 1, wherein: the contact surface of the copper plate (8) and the heater (16) is coated with a layer of heat-conducting adhesive, so that the adhesion degree of the contact surface is enhanced, and the heat conductivity is improved.
4. The experimental apparatus for measuring thermal resistance of a wick for a high temperature heat pipe according to claim 1, wherein: the heat-preservation cotton (4) is made of aerogel; the heat insulation cotton (4) covers the heater (16), the copper plate (8) and the germanium glass wall surface (11) to form a heat insulation environment.
5. The experimental apparatus for measuring thermal resistance of a wick for a high temperature heat pipe according to claim 1, wherein: a through hole is arranged in the thermocouple fixing piece (2), and a K-type thermocouple (12) can be arranged in the inner cavity; four K-type thermocouples (12) are uniformly arranged on the surface of the liquid absorbing core (5) and the bottom of the copper plate (8).
6. The experimental apparatus for measuring thermal resistance of a wick for a high temperature heat pipe according to claim 1, wherein: the inner wall of the stainless steel upper plate (10) is coated with a super-hydrophobic coating to enhance condensation reflux and accelerate the condensation reflux to reach a steady state; the preparation method of the super-hydrophobic coating comprises the following steps: using organic silicon modified acrylic resin as a film forming substance, n-butanol and xylene as solvents, and nano SiO 2 The light calcium carbonate, the talcum powder and the titanium dioxide are added particles to prepare the coating, wherein the organic silicon modified acrylic resin, the n-butyl alcohol, the dimethylbenzene and the nano SiO 2 The mass ratio of the light calcium carbonate, the talcum powder and the titanium dioxide is 18-22: 22 to 28:38 to 42:1 to 3:2 to 4:4 to 8: 3-5, ultrasonically dispersing the prepared coating for 30-45 min to obtain a super-hydrophobic coating; the upper surface of the copper plate (8) is treated by a peroxidation process: heating the metal oxide solution at 85-95 ℃ for 45-60 min to obtain a micro-nano structure surface and enhance wettability; the metal oxidizing solution was prepared as follows: sodium hypochlorite NaClO 2 Hydrogen, hydrogenNaOH sodium oxide, trisodium phosphate Na 3 PO 4 Mixing with deionized water according to the mass ratio of 2-3: 4-7: 6-9: 81-87, and stirring for 10-15 min by using a magnetic stirrer to obtain the metal oxidation liquid.
7. The experimental apparatus for measuring thermal resistance of a wick for a high temperature heat pipe according to claim 1, wherein: the maximum flow rate of the vacuum pump (13) is 3.4-4L/s, and the allowable maximum vacuum pressure is 3.0 multiplied by 10 -2 ～4.5×10 -2 torr, sufficient pumping capacity; the measuring precision of the vacuum gauge (15) is 0.001-0.003 Mpa, the temperature range is-40-100 ℃, the precision is high, and the measurement of the pressure at high temperature is met; the air inlet valve (6) and the air outlet valve (14) are ball valves, so that the valve is small in friction resistance, good in sealing performance and suitable for being quickly opened and closed and accurately controlled.
8. The experimental apparatus for measuring thermal resistance of a wick for a high temperature heat pipe according to claim 1, wherein: the germanium glass wall surface (11) is made of optical germanium crystals; the outer layer of the germanium glass wall surface (11) is plated with an optical film, so that the transmission capacity of infrared signals is improved; the long-wave thermal infrared imager (17) can convert radiation signals into visual images, and the intensity of radiation is positively correlated with the temperature, and the imaging brightness is also positively correlated with the temperature of an object, so that the temperature distribution of the surface of the object can be tested; the working spectrum range is 8-14 μm, the highest frame frequency is 200-240 Hz, the temperature measuring range is up to 0-1500 ℃, the thermal sensitivity is 30-50 mK, and accurate real-time temperature measurement is realized.
9. The experimental apparatus for measuring thermal resistance of a wick of a high-temperature heat pipe according to claim 1, wherein: a small-sized visual window is reserved on one side between the heat-preservation cotton (4) and the germanium glass wall surface (11), so that the heat loss is reduced as much as possible, and meanwhile, the temperature of a gas-liquid interface in the closed cavity is monitored through a long-wave thermal infrared imager (17); in consideration of the temperature distribution difference of the gas-liquid interface, a horizontal monitoring line is arranged on the gas-liquid interface, and the average value of the temperature at the gas-liquid interface is calculated by using system analysis software in a data analysis system (18) and is used as the actual temperature.
10. The method of testing a thermal resistance measurement test apparatus for a high temperature heat pipe wick according to any one of claims 1-9, wherein: fixing a clean liquid absorption core (5) on the upper surface of a copper plate (8) by using a stainless steel gasket (7) and a screw, pouring deionized water to completely immerse the liquid absorption core (5), covering a stainless steel upper plate (10) and a germanium glass wall surface (11) on the copper plate (8) and tightly pressing and fixing the copper plate (8) by using a G-shaped fastening clamp (9); closing the air inlet valve (6), opening the exhaust valve (14), opening the vacuum pump (13), and closing the exhaust valve (14) and the vacuum pump (13) in sequence when the indication number of the vacuum meter is-98 to-95 kPa; opening the pressure regulator (1) and the condenser (3), adjusting the heating power P, and recording the temperature; closing the pressure regulator (1) and the condenser (3) when the temperature of each temperature measuring point is not changed; the average value of a plurality of K-type thermocouples (12) on the surface of the liquid absorbing core (5) and at the bottom of the copper plate (8) is selected as the surface temperature T of the liquid absorbing core w And temperature T of the lower surface of the copper plate c Measuring the temperature T of a gas-liquid interface by a long-wave thermal infrared imager (17) v (ii) a Due to the condensation reflux effect of the stainless steel upper plate (10), the working medium circulation reaches a relatively stable state, the temperature continues to rise at the moment, but the temperature difference tends to be constant, and when the difference values of the surface temperature of the liquid absorption core, the lower surface temperature of the copper plate and the temperature of a gas-liquid interface tend to be constant, the temperature at the moment is selected for calculation, and the evaporation thermal resistance R is calculated eva And thermal conductivity resistance R cond The following formula is provided:
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