Visual saturated nuclear working medium boiling heat transfer coefficient measuring device and method

Abstract

The invention provides a visual saturated nuclear working medium boiling heat transfer coefficient measuring device and method. The visual saturated nuclear working medium boiling heat transfer coefficient measuring device comprises an experimental instrument main body, a master controller, a constant temperature controller and a power supply, the experiment instrument main body comprises an upper cover, a boiling pool, a boiling pool base, a first heat preservation layer, a second heat preservation layer, a tray, a heat conduction copper column, a bottom heating rod, a first temperature sensor, a second temperature sensor, an auxiliary heating rod and a condensation pipe; the invention provides a visual saturated nuclear working medium boiling heat transfer coefficient measuring method. The visual saturated nuclear working medium boiling heat transfer coefficient measuring device is adopted for testing. The modules are convenient to mount, dismount and debug; a linear temperature measurement mode is adopted, and temperature measurement errors are reduced through an algorithm; real-time visual monitoring of boiling heat exchange is realized by adopting the visual boiling pool, parameters can be flexibly set according to experimental requirements, and the problems of inaccurate input heat, inaccurate measured temperature, single test working condition and sample and difficulty in changing and the like in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to a teaching experiment device in thermology and heat transfer, and particularly to a visualization device for measuring the boiling heat transfer coefficient of saturated nucleate working fluid for teaching and scientific research purposes. Background Art

[0002] In the teaching of thermology and heat transfer, understanding the boiling mechanism of liquids and their heat transfer characteristics is an important and complex content. However, in the current college physics experiment teaching in China, there are few experiments related to thermology, especially the experiment on the boiling heat transfer performance of saturated nucleate boiling. The main reason is the lack of relevant teaching instruments, and the teaching instruments for studying boiling heat transfer are blank; the existing experimental instruments also have problems such as inaccurate input heat, inaccurate measured temperature, and single test conditions and samples. Therefore, it is particularly important to develop a multifunctional experimental instrument that can not only provide an intuitive teaching experience but also realize parameter adjustment and reading and has strong operability for visualizing the measurement of the boiling heat transfer coefficient of working fluid, especially an experimental instrument applied to college physics experiment teaching. Summary of the Invention

[0003] To solve the above technical problems, the present invention provides a visualization device for measuring the boiling heat transfer coefficient of saturated nucleate working fluid, including an experimental instrument main body, a total controller, a constant temperature controller, and a power supply;

[0004] The experimental instrument main body includes an upper cover, a boiling pool, a boiling pool base, a first heat insulation layer, a second heat insulation layer, a tray, a heat conduction copper column, a bottom heating rod, a first temperature sensor, a second temperature sensor, an auxiliary heating rod, and a condensing tube;

[0005] The upper cover is arranged above the boiling pool, and the boiling pool base is arranged below the boiling pool. The upper cover, the boiling pool, and the boiling pool base are sequentially and hermetically connected;

[0006] A sample installation hole is provided in the middle of the boiling pool base, and the sample to be measured is arranged at the sample installation hole and is hermetically fixed;

[0007] The first heat insulation layer and the second heat insulation layer are sequentially arranged below the boiling pool base and above the tray; through holes are provided in the middle of the first heat insulation layer and the second heat insulation layer. The heat conduction copper column is arranged in the through holes of the first heat insulation layer and the second heat insulation layer and is tightly fitted with the first heat insulation layer and the second heat insulation layer. The top of the heat conduction copper column is in close contact with the bottom surface of the sample to be measured, and the top surface area of the heat conduction copper column is greater than or equal to the bottom surface area of the sample to be measured. The first heat insulation layer and the second heat insulation layer play the roles of heat insulation, support, and fixation, and the tray plays the roles of support and fixation.

[0008] A blind hole is provided at the lower end of the heat conduction copper column, and the bottom heating rod is arranged in the blind hole of the heat conduction copper column and is tightly connected with the heat conduction copper column. The bottom heating rod is connected to the total controller through a signal line;

[0009] The first thermal insulation layer is provided with temperature measuring row holes which penetrate into the center of the heat-conducting copper columns. The temperature measuring row holes are vertically arranged at equal intervals downward from the upper surface of the heat-conducting copper columns. Temperature probes are respectively arranged in the temperature measuring row holes to measure the temperature gradient on the upper surface and at the internal center of the heat-conducting copper columns. The temperature probes are respectively connected to the main controller through signal lines.

[0010] The first temperature sensor, the second temperature sensor and the auxiliary heating rod are respectively connected to the upper cover and penetrate into the boiling pool. The first temperature sensor is connected to the main controller through a signal line. The second temperature sensor and the auxiliary heating rod are respectively connected to the constant temperature controller through signal lines. The first temperature sensor and the second temperature sensor are used to measure the temperature of the liquid medium, and the auxiliary heating rod is used to heat the liquid medium.

[0011] A through hole is provided in the middle of the upper cover. The lower end of the condensing pipe is fixedly connected to the through hole of the upper cover. The condensing pipe is internally communicated with the boiling pool.

[0012] The main controller and the constant temperature controller are respectively connected to the power supply. The main controller is used to collect the temperature of the liquid medium and the temperature of the heat-conducting copper columns, and control the heating power of the bottom heating rod. The constant temperature controller heats the liquid medium by controlling the auxiliary heating rod and keeps it at a constant temperature.

[0013] Furthermore, the boiling pool is provided with a transparent rectangular plane observation window, aiming to reduce optical distortion, such as visual deviation of the position and shape of bubbles caused by refraction, facilitating observation and data collection, and improving data accuracy.

[0014] Furthermore, several corresponding through holes are provided on the upper cover and the tray. The upper cover and the tray are connected by double-headed studs. The upper and lower ends of the double-headed studs respectively pass through the through holes on the upper cover and the tray, and the outer ends are fastened by nuts to tightly fix the upper cover, the boiling pool and the boiling pool base.

[0015] Furthermore, several threaded support columns are screwed to the lower part of the tray, and the height is adjusted by screwing the threaded support columns.

[0016] Furthermore, a silica gel gasket is provided between the second thermal insulation layer and the tray, which plays a role in heat insulation, anti-slip, shock absorption and fixing the bottom heating rod.

[0017] Furthermore, the lower part of the upper cover is an annular protrusion. A groove is provided on the lower end surface of the annular protrusion. A silica gel sealing gasket is provided in the groove. The annular protrusion of the upper cover is hermetically connected to the upper port of the boiling pool through the silica gel sealing gasket.

[0018] Further, the boiling pool base is a polyether ether ketone base; the first thermal insulation layer is a polyether ether ketone thermal insulation layer, and the second thermal insulation layer is a ceramic thermal insulation layer. The polyether ether ketone material is convenient for drilling and processing but has a high cost, while the ceramic material is not easy to process too much but has a low cost, and the thermal insulation performance of both is similar. The two thermal insulation layers made of the two materials are arranged in an upper and lower layer, which not only reduces the manufacturing cost but also facilitates processing. The two thermal insulation layers can be connected by pins.

[0019] Further, the total controller includes a housing, a processor, a terminal block, a control input module, and a display module. The processor is arranged inside the housing, and the terminal block, the control input module, and the display module are respectively arranged outside the housing and are respectively connected to the processor; the total controller has a temperature acquisition function and a heating control function.

[0020] Further, the condenser tube is a serpentine condenser tube, which includes an outer tube and a serpentine inner tube. The upper and lower ends of the outer tube are open, and the lower port is fixedly connected to the through hole of the upper cover and is communicated with the inside of the boiling pool; the serpentine inner tube is arranged inside the outer tube, and the two ends of the serpentine inner tube are respectively a water inlet and a water outlet, both of which are arranged at the upper part of the condenser tube; the water inlet and the water outlet of the serpentine inner tube are respectively connected to the condensate inlet pump and the water tank; the steam in the boiling pool enters the outer tube of the condenser tube, is cooled and condensed by passing through the serpentine inner tube, and flows back into the boiling pool to prevent the reduction of the liquid medium in the boiling pool.

[0021] Further, the first temperature sensor, the second temperature sensor, and the temperature probe are all PT100 platinum thermal resistance temperature sensors.

[0022] The present invention also provides a method for measuring the visualization saturated nucleate boiling heat transfer coefficient of a working medium, which is tested by using the above-mentioned device for measuring the visualization saturated nucleate boiling heat transfer coefficient of a working medium, and includes the following steps:

[0023] After fixing the sample to be tested in the sample mounting hole in the middle of the boiling pool base, add an appropriate amount of liquid medium into the boiling pool so that the liquid level of the liquid medium submerges the heating part of the auxiliary heating rod and does not fill the boiling pool;

[0024] Assemble the main body of the experimental instrument, and adjust the height of the threaded support column under the tray until the main body of the experimental instrument is horizontal and stable;

[0025] Connect the condensate inlet and outlet of the condenser tube to the condensate inlet pump and the water tank respectively, and start the condensate pump;

[0026] Start the constant temperature controller, set the target temperature value. At this time, the auxiliary heating rod starts to heat, and heat until the liquid medium reaches the target temperature value. After the temperature is stable, continue to heat for at least ten minutes to ensure that the liquid medium reaches a stable saturated state;

[0027] Start the main controller, collect the temperature of the liquid medium in the boiling pool through the first temperature sensor, and collect the temperature values at each temperature measurement position downward from the upper surface of the heat-conducting copper column through the temperature probes in the temperature measurement row holes;

[0028] Adjust the heating current and voltage of the bottom heating rod through the main controller to adjust the heating power to the working conditions required for experimental research;

[0029] After reaching thermal equilibrium, read the real-time temperatures of each temperature probe;

[0030] The theoretical calculation formula for the heat flux density of the sample to be measured:

[0031]

[0032] q is the heat flux density; K Cu is the thermal conductivity of the heat-conducting copper column; T i is the temperature measurement value from bottom to top of the temperature probes on the heat-conducting copper column except for the upper surface; n is the number of temperature probes on the heat-conducting copper column except for the upper surface; Δx i is the temperature measurement point distance between two temperature probes. The bottom area of the sample to be measured is A w , and the top area of the heat-conducting copper column is A Cu , because the heat flux density cannot be completely transferred to the sample surface, so multiply by the area ratio.

[0033] The calculation formula for the superheat ΔT:

[0034] ΔT = T w -T sat

[0035] T w is the upper surface temperature of the sample to be measured, approximately the lower surface temperature of the sample to be measured, that is, the temperature measured at the uppermost hole of the temperature measurement row hole; T sat is the temperature of the saturated boiling state of the liquid medium in the boiling pool, collected through the first temperature sensor;

[0036] The calculation formula for the heat transfer coefficient:

[0037]

[0038] h is the heat transfer coefficient, q is the heat flux density, and ΔT is the superheat.

[0039] The beneficial effects of the present invention:

[0040] The present invention is an experimental instrument applied to the teaching of college physics experiments. The various structures of the present invention (such as boiling pool, thermal insulation layer, heating rod, temperature sensor, etc.) adopt modular design, which is convenient for installation and disassembly, and convenient for debugging. Users can easily assemble and disassemble the instrument, which is convenient for understanding the internal structure and working principle of the instrument, convenient for instrument maintenance and upgrade, and reduces costs; the present invention adopts a linear temperature measurement method to reduce the error of temperature measurement through algorithms; the use of a visual boiling pool realizes real-time visual monitoring of boiling heat transfer, and parameters can be flexibly set according to experimental needs, such as heating power, material of the sample to be measured, surface structure of the sample, etc. The content for exploration is rich and closely combined with frontier applications, overcoming problems in the prior art such as inaccurate input heat, inaccurate measured temperature, single test condition, and difficult-to-change samples, filling the gap in boiling heat transfer teaching instruments.

[0041] In addition to carrying out basic experiments on boiling heat transfer, the present invention can also be used as a convenient operation practice platform for teaching experiments. In traditional thermal experiments, students usually can only understand boiling phenomena through data or charts, lacking intuitive feelings. This device adopts a transparent glass boiling pool and observation window, and students can observe the generation, movement and heat transfer phenomena of bubbles during the boiling process in real time. This visual design makes the abstract boiling heat transfer theory intuitive, helping students better understand the boiling mechanism and heat transfer characteristics. The modular design enables students to participate in the assembly and debugging of experimental instruments by hand, cultivating their practical ability and experimental skills, and facilitating the understanding of the internal structure and working principle of the instrument. At the same time, the modular design is also convenient for teachers to maintain and upgrade the instrument, reducing teaching costs. This device supports multi-parameter adjustment to meet the needs of hierarchical teaching, and is not only suitable for basic experimental teaching, but also can be used for exploratory experiments and design experiments. The heat preservation and sealing design of this instrument provides the safety and stability of the device, ensuring that students can carry out experimental operations in a safe environment. The total controller of this device has temperature acquisition function and heating control function, can display data information such as current, voltage, temperature in real time, and adjusts parameters through the control input module (buttons, knobs or touch screen). The real-time data acquisition and display function enables students to quickly obtain experimental data and conduct real-time analysis. This design not only improves the experimental efficiency, but also helps students better understand experimental phenomena and theoretical formulas. Brief Description of the Drawings

[0042] Figure 1 It is a schematic diagram of the overall structure of the experimental instrument body of the present invention;

[0043] Figure 2 It is a schematic diagram of the structure of the experimental instrument body of the present invention;

[0044] Figure 3 It is a schematic diagram of the structure of the total controller of the present invention;

[0045] 1. Main body of the experimental instrument 2. Upper cover 3. Boiling pool 4. Base of the boiling pool 5. First insulation layer 6. Second insulation layer 7. Tray 8. Heat-conducting copper column 9. Bottom heating rod 10. First temperature sensor 11. Second temperature sensor 12. Auxiliary heating rod 13. Condensing tube 14. Sample to be measured 15. Temperature measurement row holes 16. Double-headed stud 17. Nut 18. Threaded support column 19. Silicone gasket 20. Silicone sealing gasket 21. Total controller 22. Terminal block 23. Control input module 24. Display module 25. Outer tube 26. Serpentine inner tube 27. Rectangular plane observation window. Detailed implementation method

[0046] Example 1

[0047] Refer to Figures 1-3 As shown in the figure: This example provides a device for measuring the heat transfer coefficient of visual saturated nucleate boiling of working fluid, including the main body 1 of the experimental instrument, the total controller 21, the constant temperature controller, and the power supply;

[0048] The main body 1 of the experimental instrument includes an upper cover 2, a boiling pool 3, a base 4 of the boiling pool, a first insulation layer 5, a second insulation layer 6, a tray 7, a heat-conducting copper column 8, a bottom heating rod 9, a first temperature sensor 10, a second temperature sensor 11, an auxiliary heating rod 12, and a condensing tube 13.

[0049] The upper cover 2 is an aluminum upper cover, the boiling pool 3 is a cylindrical glass boiling pool with an observation window, and the base 4 of the boiling pool is a polyether ether ketone base; the upper cover 2 is arranged above the boiling pool 3, the base 4 of the boiling pool is arranged below the boiling pool 3, and the upper cover 2, the boiling pool 3, and the base 4 of the boiling pool are sequentially sealed and connected.

[0050] A sample installation hole is provided in the middle of the base 4 of the boiling pool. The sample 14 to be measured is in the shape of a sheet, with the same shape as the sample installation hole and a flat bottom surface. The sample 14 to be measured can be embedded at the sample installation hole, sealed and fixed to prevent liquid leakage; in this example, the sample 14 to be measured is a copper sample.

[0051] The first insulation layer 5 is a polyether ether ketone insulation layer, and the second insulation layer 6 is a ceramic insulation layer. The first insulation layer 5 and the second insulation layer 6 are sequentially arranged below the base 4 of the boiling pool and above the tray 7; through holes are provided in the middle of the first insulation layer 5 and the second insulation layer 6. The outer shape of the heat-conducting copper column 8 is the same as the shape of the through hole. The heat-conducting copper column 8 is embedded in the through holes of the first insulation layer 5 and the second insulation layer 6 and is in close fit with the first insulation layer 5 and the second insulation layer 6. The top surface of the heat-conducting copper column 8 is flat, and the top surface of the heat-conducting copper column 8 is evenly coated with heat-conducting silicone grease and is in close contact with the bottom surface of the sample 14 to be measured;

[0052] The lower end of the heat-conducting copper column 8 is provided with a blind hole. The shape of the bottom heating rod 9 is the same as that of the blind hole. The bottom heating rod 9 is embedded in the blind hole of the heat-conducting copper column 8 and is closely connected to the heat-conducting copper column 8. The bottom heating rod 9 is connected to the main controller 21 through a signal line; the maximum power of the bottom heating rod 9 is 300W.

[0053] The first heat-insulating layer 5 is provided with a temperature-measuring row of holes 15. Five temperature-measuring holes are arranged vertically and equidistantly from the upper surface of the heat-conducting copper column 8 downward. The temperature-measuring row of holes 15 penetrates into the center of the heat-conducting copper column 8. Temperature probes are respectively arranged in the temperature-measuring row of holes 15 to measure the temperature gradient at the center of the heat-conducting copper column 8. The temperature probes are respectively connected to the main controller through signal lines; the temperatures at different positions of the heat-conducting copper column 8 are measured in sequence.

[0054] Two threaded holes and a pipe threaded hole are provided on the upper cover 2; the upper ends of the first temperature sensor 10 and the second temperature sensor 11 are respectively threadedly connected to the two threaded holes of the upper cover 2; the upper end of the auxiliary heating rod 12 is threadedly connected to the pipe threaded hole of the upper cover 2; the first temperature sensor 10, the second temperature sensor 11 and the auxiliary heating rod 12 respectively penetrate into the boiling pool 3; the first temperature sensor 10 is connected to the main controller through a signal line, and the second temperature sensor 11 and the auxiliary heating rod 12 are respectively connected to the constant temperature controller through signal lines. The maximum power of the auxiliary heating rod 12 is 200W.

[0055] The first temperature sensor 10, the second temperature sensor 11 and the temperature probes are all PT100 platinum resistance temperature sensors.

[0056] A tapered hole is further provided in the middle of the upper cover 2. The lower end of the condenser tube 13 is fixedly connected to the tapered hole of the upper cover 2. The condenser tube 13 is internally communicated with the boiling pool 3; the condenser tube 13 is a serpentine condenser tube, including an outer tube 25 and a serpentine inner tube 26. The upper and lower ends of the outer tube 25 are open. The lower port is fixedly connected to the through hole of the upper cover 2 and is internally communicated with the boiling pool 3; the serpentine inner tube 26 is arranged inside the outer tube 25. The two ends of the serpentine inner tube 26 are respectively a water inlet and a water outlet, both of which are arranged at the upper part of the condenser tube 13; the water inlet and the water outlet of the serpentine inner tube 26 are respectively connected to the condensate inlet pump and the water tank; the steam in the boiling pool 3 enters the outer tube 25 of the condenser tube 13 and is cooled and condensed by the serpentine inner tube 26 and then flows back into the boiling pool.

[0057] The boiling pool is provided with a transparent rectangular planar observation window 27.

[0058] The main controller 21 and the constant temperature controller are respectively connected to the power supply, and the power supply provides electric energy.

[0059] The upper cover 2 and the tray 7 are provided with several corresponding through holes. The upper cover 2 and the tray 7 are connected by double-headed studs 16. The upper and lower ends of the double-headed studs 16 respectively pass through the through holes on the upper cover 2 and the tray 7, and the outer ends are fastened by nuts 17 to tightly fix the upper cover 2, the boiling pool 3 and the boiling pool base 4.

[0060] The tray 7 is further provided with 4 threaded holes, and 4 threaded support columns 18 are screwed thereon, and the height is adjusted by screwing the threaded support columns 18.

[0061] A silica gel gasket 19 is provided between the second heat insulation layer 6 and the tray 7, which plays a role in heat insulation, anti-slip, shock absorption and fixing the bottom heating rod 9.

[0062] The lower part of the upper cover 2 is an annular protrusion. The lower end surface of the annular protrusion is provided with a groove, and a silica gel sealing gasket 20 is arranged in the groove. The annular protrusion of the upper cover 2 is hermetically connected to the upper port of the boiling pool 3 through the silica gel sealing gasket 20.

[0063] The general controller 21 includes a housing, a processor, a memory, a terminal block 22, a control input module 23 and a display module 24. The processor and the memory are arranged inside the housing, and the terminal block, the control input module and the display module are respectively arranged outside the housing and are respectively connected to the processor; the signal lines of the bottom heating rod 9, the first temperature sensor 10, the second temperature sensor 11 and the temperature probe are connected to the processor through the terminal block for data transmission; the control input module includes buttons, knobs or touch screens for inputting values or adjusting values or inputting control instructions to the processor; the display module includes a display screen for displaying data information such as current, voltage and temperature; the general controller has a temperature acquisition function and a heating control function.

[0064] The condenser tube 13 is connected to a condensation system such as a condensate pump and a water tank. The condensation system such as the condensate pump and the water tank are all existing devices, and the structures will not be described in detail here.

[0065] The constant temperature controller is an existing device, and the structure will not be described in detail here.

[0066] The working principle of the present invention:

[0067] An appropriate amount of distilled water is added to the boiling pool 3 of the present invention as a liquid medium, so that the liquid medium level submerges the heating part of the auxiliary heating rod 12 and the temperature measuring parts of the first temperature sensor 10 and the second temperature sensor 11, and does not fill the boiling pool 3;

[0068] The constant temperature controller controls the auxiliary heating rod 12 to heat the liquid medium and keep it at a constant temperature. The second temperature sensor 11 collects the temperature of the liquid medium in real time and feeds it back to the constant temperature controller to help the constant temperature controller master and control the heating temperature of the auxiliary heating rod 12.

[0069] After the liquid medium in the boiling pool 3 reaches a stable saturated state, the total controller activates the heating function and adjusts the power to the working conditions required for experimental research by regulating the heating current and voltage of the bottom heating rod 9. After reaching thermal equilibrium, the temperature probe measures the temperatures at different positions of the heat-conducting copper column 8, and the temperature data at thermal equilibrium is read from the total controller.

[0070] After the liquid medium reaches a stable saturated state, the boiling heat transfer coefficient of the working fluid can be determined based on the temperature data.

[0071] Example 2

[0072] This example provides a method for measuring the boiling heat transfer coefficient of a visual saturated nucleate working fluid. The method uses the device for measuring the boiling heat transfer coefficient of a visual saturated nucleate working fluid described in Example 1 for testing, and includes the following steps:

[0073] After fixing the sample to be tested 14 in the sample mounting hole in the middle of the boiling pool base 4, an appropriate amount of distilled water is added to the boiling pool 3 so that the liquid level of the distilled water submerges the heating part of the auxiliary heating rod 12 and does not fill the boiling pool 3. In this example, the sample to be tested 14 is a copper sample.

[0074] Assemble the main body of the experimental instrument 1, and adjust the height of the threaded support column 18 under the tray 7 until the main body of the experimental instrument 1 is horizontal and stable.

[0075] Connect the condensate inlet and outlet of the condenser 13 to the condensate inlet pump and the water tank respectively, and start the condensate pump.

[0076] Start the constant temperature controller, set the target temperature value to 100 °C. The second temperature sensor 11 collects the temperature of the liquid medium in real time and feeds it back to the constant temperature controller. The constant temperature controller activates the auxiliary heating rod 12 to start heating until the distilled water reaches the target temperature value. After the temperature is stable, continue heating for at least ten minutes to ensure that the distilled water reaches a stable saturated state.

[0077] Start the total controller 21. The temperature of the distilled water in the boiling pool 3 is collected through the first temperature sensor 10, and the temperature values at each temperature measurement position from the upper surface down of the heat-conducting copper column 8 are sequentially collected through 5 temperature probes in the temperature measurement holes.

[0078] Adjust the heating power to the working conditions required for experimental research by regulating the heating current and voltage of the bottom heating rod 9 through the total controller 21.

[0079] After reaching thermal equilibrium, read the real-time temperatures of each temperature probe; record them from bottom to top as T 1 、T 2 、T 3 、T 4 、T 5 ; T 1、T 2 、T 3 、T 4 Used to calculate the sample heat flux; T 5 is the upper surface temperature of the heat-conducting copper column 8, that is, the lower surface temperature of the sample to be tested, which is used to calculate the superheat.

[0080] Theoretical calculation formula for heat flux density of the sample to be tested:

[0081]

[0082] q is the heat flux, K Cu is the thermal conductivity of copper, T 1 、T 2 、T 3 、T 4 The temperature probe measures the temperature value of the thermal conductive copper column 8 from bottom to top, Δx i is the distance between the two temperature probes. The bottom area of ​​the sample to be tested is A w , the top surface area of ​​the thermal conductive copper column is A Cu , because the heat flux density cannot be completely transferred to the sample surface, it is multiplied by the area ratio.

[0083] Superheat ΔT calculation formula:

[0084] ΔT=T w -T sat

[0085] T w is the upper surface temperature of the sample to be tested, which is approximately equal to the lower surface temperature of the sample to be tested. In this embodiment, it is equal to the temperature T measured by the uppermost temperature probe of the temperature measuring hole. 5 ; When thermal equilibrium is reached, the upper surface temperature and the lower surface temperature of the sample to be tested are approximately the same, that is, the temperature measured by the uppermost hole of the temperature measuring holes. Because the temperature probe of the uppermost hole is arranged between the upper surface of the thermally conductive copper column and the lower surface of the sample to be tested, the two temperatures are equal to the temperature measured by the uppermost hole of the temperature measuring holes. The thickness of the sample to be tested is as thin as possible, and the thickness will affect the time to reach thermal equilibrium. The greater the thickness, the longer the time to reach thermal equilibrium, and the smaller the thickness, the shorter the time to reach thermal equilibrium. When the experimental instrument is used for experiments in this embodiment, the thickness of the sample to be tested is set to 3mm. If the experimental conditions are different, such as if it is necessary to depict a microstructure on the surface of the sample to be tested for experiments, the thickness of the sample to be tested can be appropriately changed according to the experimental conditions. The thickness of the sample to be tested is preferably 0.5mm-5mm.

[0086] T sat is the temperature of the saturated boiling state of the liquid medium in the boiling pool, which is collected by the first temperature sensor; the heat transfer coefficient calculation formula is:

[0087]

[0088] h is the heat transfer coefficient, q is the heat flux density, and ΔT is the degree of superheat;

[0089] The memory in the total controller 21 stores a computer program. When the processor executes the computer program, the above calculation steps are implemented to calculate the heat flux density, the degree of superheat, and the heat transfer coefficient of the sample to be measured.

Claims

1. A visual saturated nucleate state working fluid boiling heat transfer coefficient measuring device, characterized in that: Including the main body of the experimental instrument, the main controller, the constant temperature controller, and the power supply; The main body of the experimental instrument includes an upper cover, a boiling pool, a boiling pool base, a first insulation layer, a second insulation layer, a tray, a heat-conducting copper column, a bottom heating rod, a first temperature sensor, a second temperature sensor, an auxiliary heating rod, and a condenser; The upper cover is arranged on the upper part of the boiling pool, the boiling pool base is arranged on the lower part of the boiling pool, and the upper cover, the boiling pool and the boiling pool base are sealed and connected in sequence; A sample installation hole is provided in the middle of the boiling pool base, and the sample to be tested is placed at the sample installation hole and sealed and fixed; The first insulation layer and the second insulation layer are sequentially arranged below the base of the boiling pool and located on the upper part of the tray; through holes are arranged in the middle of the first insulation layer and the second insulation layer, and the heat-conducting copper column is arranged in the through holes of the first insulation layer and the second insulation layer, and is closely matched with the first insulation layer and the second insulation layer, and the top of the heat-conducting copper column is in close contact with the bottom surface of the sample to be tested; A blind hole is provided at the lower end of the heat-conducting copper column, and the bottom heating rod is arranged in the blind hole of the heat-conducting copper column and is closely connected to the heat-conducting copper column. The bottom heating rod is connected to the main controller through a signal line; The first insulation layer is provided with temperature measuring holes, which extend deep into the center of the heat-conducting copper column. The temperature measuring holes are arranged vertically from the upper surface of the heat-conducting copper column downward at intervals. Temperature probes are respectively arranged in the temperature measuring holes to measure the temperature gradient of the upper surface and the inner center of the heat-conducting copper column. The temperature probes are respectively connected to the main controller through signal lines. The first temperature sensor, the second temperature sensor, and the auxiliary heating rod are respectively connected to the upper cover and extend into the boiling pool; the first temperature sensor is connected to the main controller via a signal line, and the second temperature sensor and the auxiliary heating rod are respectively connected to the constant temperature controller via a signal line; the first temperature sensor and the second temperature sensor are used to measure the temperature of the liquid experimental medium, and the auxiliary heating rod is used to heat the liquid experimental medium; A through hole is provided in the middle of the upper cover, the lower end of the condenser tube is fixedly connected to the through hole of the upper cover, and the condenser tube is communicated with the inside of the boiling pool; The main controller and the thermostat are connected to the power supply respectively. The main controller is used to collect the temperature of the liquid experimental medium and the temperature of the heat-conducting copper column, and control the heating power of the bottom heating rod. The thermostat heats the liquid experimental medium and maintains a constant temperature by controlling the auxiliary heating rod.

2. A visual saturated nucleate state working fluid boiling heat transfer coefficient measuring device according to claim 1, characterized in that: The boiling pool is provided with a transparent rectangular plane observation window.

3. A visual saturated nucleate state working fluid boiling heat transfer coefficient measuring device according to claim 1, characterized in that: The upper cover and the tray are provided with several corresponding through holes, and the upper cover and the tray are connected by studs, the upper and lower ends of the studs pass through the through holes on the upper cover and the tray respectively, and the outer ends are fastened by nuts to press and fix the upper cover, the boiling pool and the boiling pool base.

4. A visual saturated nucleate state working fluid boiling heat transfer coefficient measuring device according to claim 1, characterized in that: A plurality of threaded support columns are screwed on the lower part of the tray, and the height can be adjusted by screwing the threaded support columns.

5. A visual saturated nucleate state working fluid boiling heat transfer coefficient measuring device according to claim 1, characterized in that: A silica gel gasket is provided between the second heat-insulating layer and the tray.

6. A visual saturated nucleate state working fluid boiling heat transfer coefficient measuring device according to claim 1, characterized in that: The lower part of the upper cover is an annular protrusion, the lower end surface of the annular protrusion is provided with a groove, a silicone sealing gasket is provided in the groove, and the annular protrusion of the upper cover is sealed and connected with the upper port of the boiling pool through the silicone sealing gasket.

7. The visual saturated nucleate state working fluid boiling heat transfer coefficient measuring device according to claim 1 is characterized by: The boiling pool base is a polyetheretherketone base; the first thermal insulation layer is a polyetheretherketone thermal insulation layer, and the second thermal insulation layer is a ceramic thermal insulation layer.

8. A visual saturated nucleate state working fluid boiling heat transfer coefficient measuring device according to claim 1, characterized in that: The master controller comprises a shell, a processor, wiring terminals, a control input module and a display module. The processor is arranged inside the shell, and the wiring terminals, the control input module and the display module are respectively arranged outside the shell and are respectively connected to the processor; the master controller has temperature acquisition function and heating control function.

9. A visual saturated nucleate state working fluid boiling heat transfer coefficient measuring device according to claim 1, characterized in that: The condenser is a serpentine condenser, comprising an outer tube and a serpentine inner tube. The upper and lower ends of the outer tube are open, and the lower end is fixedly connected to the through hole of the upper cover and communicated with the inside of the boiling pool; the serpentine inner tube is arranged in the outer tube, and the two ends of the serpentine inner tube are respectively a water inlet and a water outlet, both of which are arranged on the upper part of the condenser; the water inlet and the water outlet of the serpentine inner tube are respectively connected to the condensate inlet pump and the water tank.

10. A method for measuring a visualized saturated nucleate state working fluid boiling heat transfer coefficient, using a visualized saturated nucleate state working fluid boiling heat transfer coefficient measuring device as described in any one of claims 1 to 9 for testing, comprising the following steps: After fixing the sample to be tested in the sample mounting hole in the middle of the boiling pool base, add an appropriate amount of liquid experimental medium into the boiling pool so that the liquid experimental medium level covers the heating part of the auxiliary heating rod and does not fill the boiling pool; Assemble the main body of the experimental instrument and adjust the height of the threaded support column at the bottom of the tray until the main body of the experimental instrument remains level and stable; Connect the condensate inlet and outlet of the condenser pipe to the condensate inlet pump and the water tank respectively, and start the condensate pump; Start the thermostat and set the target temperature. The auxiliary heating rod starts to heat until the liquid experimental medium reaches the target temperature. When the temperature stabilizes, continue heating for at least ten minutes to ensure that the liquid experimental medium reaches a stable saturated state. The main controller is started, and the temperature of the liquid experimental medium in the boiling pool is collected through the first temperature sensor, and the temperature values ​​of the upper surface of the heat-conducting copper column and each temperature measuring position downward are collected through the temperature probe in the temperature measuring row hole; The heating current and voltage of the bottom heating rod are adjusted by the main controller to adjust the heating power to the working conditions required for the experimental research; After reaching thermal equilibrium, read the real-time temperature of each temperature probe; Theoretical calculation formula for heat flux density: q is the heat flux, K Cu is the thermal conductivity of copper, T i is the temperature value measured from top to bottom by the temperature probes other than the upper surface of the thermal conductive copper column, and n is the number of temperature probes other than the upper surface of the thermal conductive copper column; Δx i is the temperature measuring point distance between the two temperature probes; A w is the bottom area of ​​the sample to be tested, A Cu is the top surface area of ​​the thermal conductive copper column; Superheat ΔT calculation formula: ΔT=T w -T sat T w is the upper surface temperature of the sample to be tested; T sat is the temperature of the saturated boiling state of the liquid medium in the boiling pool, collected by the first temperature sensor; Heat transfer coefficient calculation formula: h is the heat transfer coefficient, q is the heat flux, and ΔT is the superheat.

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