Experimental device for testing liquid in-situ conductivity in ultrahigh-pressure low-temperature environment

Abstract

The invention discloses a liquid in-situ conductivity test experiment device in an ultrahigh-pressure low-temperature environment, which comprises an experiment table and an impedance analyzer placed on one side of the upper end of the experiment table, a placement frame is arranged at the upper end of the experiment table, and the upper end of the placement frame is detachably connected with a pressure-bearing cavity. A vacuum pump is installed on one side of the upper end of the experiment table, a pressurizing assembly is arranged on the other side of the upper end of the experiment table, an in-situ conductivity detection module is installed at the position, close to the lower end of the pressure-bearing cavity, of the outer wall of the pressure-bearing cavity, and a temperature control assembly is arranged on one side of the upper end of the experiment table. A heating compensation assembly is arranged on the outer wall of the temperature control assembly, a control cabinet is arranged on one side of the upper end of the experiment table, and a control panel is arranged in the control cabinet. According to the invention, the in-situ conductivity of the liquid can be tested, the test temperature and the change of the pressure environment can be controlled, and the in-situ conductivity test in the ultrahigh-pressure low-temperature environment can be realized.

Description

Technical Field

[0001] This invention relates to the field of materials testing technology, and in particular to an experimental device for testing the in-situ conductivity of liquids under ultra-high pressure and low temperature conditions. Background Technology

[0002] Liquid conductivity measurement systems are used to measure the conductivity of water, both aqueous and non-aqueous, in environmental, medical, industrial, and other applications where an indication of the ion content of the liquid is required. Measuring liquid conductivity in various scenarios provides a relatively inexpensive parameter that may be related to bulk ionic concentration. In the presence of a single type of ion, conductivity may indeed be related to the concentration of that specific ion. Even in the presence of multiple different ionic compounds, the measurement of liquid bulk conductivity can still provide very useful information.

[0003] Therefore, conductivity measurement has been widely adopted and utilized in various industries for different purposes. High pressure and low temperature are two extremely important conditions for regulating the state of matter and studying novel physical properties. Under the synergistic effect of ultra-high pressure and low temperature, many liquids (especially water) will exhibit unique properties that are not present at normal pressure and temperature, such as high-pressure dense ice and superionic conductor phase. Conductivity is a key physical parameter for studying these phase transitions and ion transport behavior. At present, the technology for measuring the conductivity of liquids is relatively mature, but it is mostly limited to normal pressure or medium and low pressure, and normal temperature or limited temperature range. It cannot test the in-situ conductivity under ultra-high pressure and low temperature environments. Summary of the Invention

[0004] The purpose of this invention is to provide an experimental device for testing the in-situ conductivity of liquids under ultra-high pressure and low temperature conditions. This device can not only test the in-situ conductivity of liquids, but also control the changes in the temperature and pressure environment during testing, and achieve in-situ conductivity testing under ultra-high pressure and low temperature conditions.

[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution: An experimental apparatus for testing the in-situ conductivity of liquids under ultra-high pressure and low temperature conditions includes an experimental table, an impedance analyzer placed on one side of the upper part of the experimental table, a placement rack at the upper end of the experimental table, and a hollow pressure-bearing cavity detachably connected to the upper end of the placement rack. An inlet hole and an outlet hole are respectively opened at the middle positions of the upper and lower ends of the outer wall of the pressure-bearing cavity. The inlet hole is connected to a solenoid valve, and the outlet hole is connected to a vacuum valve. A piezoelectric pressure sensor connected to the inlet hole is installed. A vacuum pump is installed on one side of the upper part of the experimental table, and a vacuum tube is detachably connected between the vacuum pump's suction port and the vacuum valve. A pressurization component connected to the solenoid valve is provided on the other side of the upper part of the experimental table. A temperature sensor extending into the upper part of the outer wall of the pressure-bearing cavity is installed on one side of the upper part of the outer wall, and an observation hole is opened downward on the other side of the upper part of the outer wall. An observation window is embedded in the observation hole and sealed to it. The observation window is interference-fitted with the observation hole by an oxygen-free sealing ring. A modified polytetrafluoroethylene gasket is attached to the outer wall of the oxygen-free sealing ring. Multiple equally spaced mounting holes are opened on the outer wall of the pressure-bearing cavity near its lower end. An in-situ conductivity detection module that is sealed to the mounting holes and extends into the pressure-bearing cavity is embedded in the mounting holes. A temperature control component that is sleeved on the outer wall of the pressure-bearing cavity is provided on one side of the upper part of the experimental table. A heating compensation component that is sealed to the outer wall of the temperature control component is provided on the outer wall of the temperature control component. A control cabinet is provided on the upper part of the experimental table next to the impedance analyzer. A control panel is provided in the control cabinet.

[0006] By adopting the above technical solution, when using the device, first power it on, operate the control panel to make the vacuum pump work, close the solenoid valve and open the vacuum valve. The vacuum pump will extract the air from the pressure chamber. After the vacuuming is completed, close the vacuum valve. Then, the temperature control component will work to cool the pressure chamber. The temperature sensor will detect the temperature change in the pressure chamber in real time. While cooling the pressure chamber, the heating compensation component will work simultaneously to maintain temperature stability. Next, the pressurization component will deliver the detected liquid into the pressure chamber. The piezoelectric pressure sensor will provide real-time feedback of the pressure value. After reaching the target pressure value, the conductivity detection module will detect the conductivity of the liquid. At the same time, the impedance analyzer will measure the impedance in a wide frequency range from µHz to GHz. The detected signal will be transmitted to the control panel in the control cabinet for processing, and the conductivity of the detected liquid will be calculated.

[0007] A further feature of the present invention is that one-way valves are provided at the ends of the solenoid valve and the vacuum valve that extend into the pressure-bearing cavity.

[0008] A further embodiment of the present invention is that the temperature control assembly includes a liquid nitrogen tank, a reflux tank, a heat exchange coil, a liquid nitrogen pump disposed on one side of the liquid nitrogen tank, an inlet pipe connected to the inlet of the liquid nitrogen pump and extending to the bottom of the inner wall of the liquid nitrogen tank, an outlet pipe disposed between the outlet of the liquid nitrogen pump and the lower end of the heat exchange coil and connected thereto, and a reflux pipe disposed between the upper end of the heat exchange coil and the upper end of the outer wall of the reflux tank and connected thereto.

[0009] A further embodiment of the present invention is that the heating compensation component includes a heating film disposed on the outer wall of the heat exchange coil, a heat insulation pad disposed between the heating film and the heating coil, and a heat insulation sleeve disposed on the outer wall of the heating film.

[0010] By adopting the above technical solution, the heating film generates heat through electricity to compensate for the temperature fluctuations caused by liquid nitrogen refrigeration. The heat insulation pad and insulation sleeve can prevent moisture in the outside air from condensing on the surface of the coil, thus avoiding the impact of low temperature on other components.

[0011] A further configuration of the present invention is as follows: the in-situ conductivity detection module includes an insulating ring, two working electrodes mounted opposite to each other on the inner wall of the insulating ring, two auxiliary electrodes respectively disposed between the two working electrodes, and insulating sleeves respectively disposed on the outer walls of the working electrodes and the auxiliary electrodes. The working electrodes, the auxiliary electrodes and the corresponding insulating sleeves are fixed together by high-temperature resistant sealant. The included angle between the two working electrodes is 180°, and the included angle between the two auxiliary electrodes is 180°.

[0012] By adopting the above technical solution and utilizing the four-electrode anti-polarization principle, electrode polarization caused by DC is avoided, and interference between electrode polarization resistance and wire resistance is eliminated.

[0013] A further feature of the present invention is that the insulating ring and the insulating sleeve are both made of alumina ceramic material, and the working electrode and the auxiliary electrode are both made of 99.99% platinum wire.

[0014] A further feature of the present invention is that each insulating sleeve is wrapped with expanded polytetrafluoroethylene tape on its outer side, forming a flexible seal with the inner wall of the corresponding mounting hole.

[0015] A further embodiment of the present invention is that the pressurizing assembly includes a pressurizing pump, a pressure buffer connected to the outlet of the pressurizing pump, a high-pressure pipeline connected to the pressure buffer, and a double compression fitting connected to the free end of the high-pressure pipeline.

[0016] A further feature of the present invention is that the pressure-bearing cavity is made of 18Ni300 martensitic aging steel.

[0017] In summary, the present invention has the following beneficial effects: Firstly, this invention can only test the conductivity of liquids in situ, and can control the changes in the temperature and pressure environment of the test, and realize in-situ conductivity testing under ultra-high pressure and low temperature environment. Secondly, the temperature control component and heating compensation component of the present invention can not only achieve the cooling effect of the pressure chamber, but also compensate for the temperature fluctuation of liquid nitrogen refrigeration during cooling. The heat insulation pad and heat insulation sleeve can prevent moisture in the outside air from condensing on the surface of the coil, avoiding the impact of low temperature on other components. Thirdly, before testing, the present invention uses a vacuum pump and vacuum tube to extract the air from the pressure chamber, which can prevent bubbles from dissolving or expanding under high pressure and low temperature, thus affecting the conductivity test. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 It is mainly used to show the positional connection relationship of each component; Figure 3 This is a schematic diagram of the temperature control component of the present invention; Figure 4 This is a schematic diagram of the heating compensation component of the present invention; Figure 5 It is mainly used to demonstrate the pressure-bearing cavity; Figure 6 This is a schematic diagram of the structure of the in-situ conductivity detection module of the present invention; Figure 7 It is mainly used to demonstrate the positional connection relationship between high-temperature resistant sealant, expanded polytetrafluoroethylene tape and electrodes; Figure 8 This is a schematic diagram of the pressurization component of the present invention.

[0019] In the diagram: 1. Experimental table; 11. Impedance analyzer; 12. Placement rack; 13. Pressure chamber; 14. Liquid inlet; 15. Solenoid valve; 16. Piezoelectric pressure sensor; 17. Liquid outlet; 18. Vacuum valve; 19. Check valve; 2. Vacuum pump; 21. Vacuum tube; 22. Temperature sensor; 23. Observation hole; 24. Observation window; 25. Oxygen-free sealing ring; 26. Modified polytetrafluoroethylene gasket; 3. Mounting hole; 31. In-situ conductivity detection module; 32. Insulating ring; 33. Working electrode 34. Auxiliary electrode; 35. Insulating sleeve; 36. High-temperature resistant sealant; 37. Expanded PTFE tape; 4. Pressurization assembly; 41. Pressurization pump; 42. Pressure buffer; 43. High-pressure pipeline; 5. Temperature control assembly; 51. Liquid nitrogen tank; 52. Reflux tank; 53. Heat exchange coil; 54. Liquid nitrogen pump; 55. Inlet pipe; 56. Outlet pipe; 57. Reflux pipe; 6. Heating compensation assembly; 61. Heating film; 62. Thermal insulation pad; 63. Insulation sleeve; 7. Control cabinet; 71. Control panel. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to the accompanying drawings.

[0021] In the description of this invention, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0022] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0023] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; or they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0024] Example, refer to Figure 1-8 An experimental apparatus for in-situ liquid conductivity testing under ultra-high pressure and low temperature conditions includes an experimental table 1, an impedance analyzer 11 placed on one side of the upper end of the experimental table 1, a placement rack 12 provided at the upper end of the experimental table 1, and a pressure-bearing cavity 13 with a hollow interior made of 18Ni300 martensitic aging steel detachably connected to the upper end of the placement rack 12. A liquid inlet 14 and a liquid outlet 17 are respectively opened at the middle positions of the upper and lower ends of the outer wall of the pressure-bearing cavity 13. The liquid inlet 14 is opened at the upper end of the pressure-bearing cavity 13, and the liquid outlet 17 is opened at the lower end of the pressure-bearing cavity 13. A solenoid valve 15 is connected to the liquid inlet 14, and a vacuum valve 18 is connected to the liquid outlet 17. A one-way valve 19 is provided at the end of the solenoid valve 15 and the vacuum valve 18 that extends into the pressure-bearing cavity 13 to prevent liquid backflow during operation, which would affect the conductivity test. A piezoelectric pressure sensor 16 is installed in the liquid inlet 14 and connected to it.

[0025] A vacuum pump 2 is installed on one side of the upper end of the experimental table 1. A vacuum tube 21 is detachably connected between the suction port of the vacuum pump 2 and the vacuum valve 18. On the other side of the upper end of the experimental table 1, a pressurizing assembly 4 is installed, which is connected to the solenoid valve 15. The pressurizing assembly 4 includes a pressurizing pump 41, a pressure buffer 42 connected to the outlet of the pressurizing pump 41, and a high-pressure pipeline 43 connected to the pressure buffer 42. The pressurizing pump 41 and the solenoid valve 15 at the bottom of the pressure-bearing chamber 13 are positioned at an elevated position to avoid pressure loss due to pipeline bends. The outer wall of the pressure-bearing chamber 13... A temperature sensor 22 is installed on one side of the upper end and extends into it. An observation hole 23 is opened downward on the other side of the upper end of its outer wall. The distance between the lower end of the temperature sensor 22 and the bottom of the inner wall of the pressure chamber 13 is 5-8mm. An observation window 24 is embedded in the observation hole 23 and sealed to it. The observation window 24 is press-fitted to the observation hole 23 through an oxygen-free sealing ring 25. The oxygen-free sealing ring 25 is made of copper or silver. A modified polytetrafluoroethylene gasket 26 is attached to the outer wall of the oxygen-free sealing ring 25. The double setting prevents leakage of pressure medium.

[0026] Four equally spaced mounting holes 3 are provided on the outer wall of the pressure chamber 13 near its lower end. An in-situ conductivity detection module 31 is embedded in the mounting holes 3 and sealed to it, extending into the pressure chamber 13. The in-situ conductivity detection module 31 includes an insulating ring 32, two working electrodes 33 mounted opposite each other on the inner wall of the insulating ring 32, two auxiliary electrodes 34 respectively disposed between the two working electrodes 33, and insulating sleeves 35 respectively disposed on the outer walls of the working electrodes 33 and the auxiliary electrodes 34. The insulating ring 32 and the insulating sleeves 35 are both made of alumina ceramic material. The working electrodes 33 and the auxiliary electrodes 34 are both made of 99.99% platinum wire. The working electrodes 33, the auxiliary electrodes 34 and the corresponding insulating sleeves 35 are fixed with high-temperature resistant sealant 36. The included angle between the two working electrodes 33 is 180° and the included angle between the two auxiliary electrodes 34 is 180°. Each insulating sleeve 35 is wrapped with expanded polytetrafluoroethylene tape 37 on the outside, forming a flexible seal with the inner wall of the corresponding mounting hole 3.

[0027] A temperature control component 5, fitted over the outer wall of the pressure-bearing cavity 13, is installed on one side of the upper end of the experimental table 1. The temperature control component 5 includes a liquid nitrogen tank 51, a reflux tank 52, a heat exchange coil 53, a liquid nitrogen pump 54 located on one side of the liquid nitrogen tank 51, an inlet pipe 55 connected to the inlet of the liquid nitrogen pump 54 and extending to the bottom of the inner wall of the liquid nitrogen tank 51, an outlet pipe 56 located between the outlet of the liquid nitrogen pump 54 and the lower end of the heat exchange coil 53 and connected to both, and a reflux pipe 57 located between the upper end of the heat exchange coil 53 and the upper end of the outer wall of the reflux tank 52 and connected to both. A heating compensation component 6, which is sealed and connected to the outer wall of the temperature control component 5, is installed on the outer wall of the temperature control component 5. The heating compensation component 6 includes a heating film 61 disposed on the outer wall of the heat exchange coil 53, a heat insulation pad 62 made of aerogel disposed between the heating film 61 and the heating coil, and a heat insulation sleeve 63 disposed on the outer wall of the heating film 61. A control cabinet 7 is disposed on one side of the impedance analyzer 11 at the upper end of the experimental table 1. A control panel 71 is disposed inside the control cabinet 7. The temperature sensor 22, vacuum valve 18, solenoid valve 15, vacuum pump 2, pressurization pump 41, piezoelectric pressure sensor 16, in-situ conductivity detection module 31, liquid nitrogen pump 54 and heating film 61 are all electrically connected to the control panel 71 through shielded cables (not shown).

[0028] Usage: When using, first power on the device, open the control panel 71 of the control cabinet 7 to start the vacuum pump 2, close the solenoid valve 15 and open the vacuum valve 18, and extract the air from the pressure chamber 13 on the placement rack 12 through the vacuum tube 21 to prevent bubbles from dissolving or expanding under high pressure and low temperature, which would affect the conductivity test. After the vacuum is completed, close the vacuum valve 18, and then start the temperature control component 5 to cool the pressure chamber 13. The temperature sensor 22 will detect the temperature change in the pressure chamber 13 in real time. The liquid nitrogen pump 54 will draw liquid nitrogen from the liquid nitrogen tank 51 through the liquid inlet pipe 55, and then flow into the heat exchange coil 53 through the liquid outlet pipe 56. After that, it will flow into the return tank 52 through the return pipe 57. Since the liquid nitrogen flows from bottom to top in the heat exchange coil 53, the residence time of the liquid nitrogen in the heat exchange coil 53 can be increased, thus improving the cooling effect.

[0029] When cooling the pressure chamber 13, when the temperature sensor 22 detects that the chamber temperature is close to the target value, the control panel 71 sends a signal to the heating film 61. The heating film 61 is energized to generate heat, compensating for the temperature fluctuations caused by liquid nitrogen refrigeration and stabilizing the temperature within an appropriate range, thereby maintaining temperature stability. Meanwhile, the heat insulation pad 62 and insulation sleeve 63 on the outside of the heat exchange coil 53 prevent condensation of moisture from the outside air on the surface of the heat exchange coil 53, avoiding the impact of low temperature on other components. Then, the detected liquid is transported into the pressure chamber 13 through the pressurization assembly 4. The solenoid valve 15 is opened, and the pressurizing pump 41 is activated. The liquid to be tested is delivered to the bottom of the pressure chamber 13 through the high-pressure pipeline 43. The incompressibility of the liquid is used to evenly distribute the pressure throughout the pressure chamber 13, avoiding uneven force distribution within the pressure chamber 13. The pressure buffer 42 can absorb pressure pulsations during the pressurization process, keeping the pressure fluctuations within the pressure chamber 13 within the allowable range. When the pressure reaches the target value, the pressurizing pump 41 stops working, and the piezoelectric pressure sensor 16 provides real-time feedback of the pressure value. If the pressure drops, the pressurizing pump 41 automatically replenishes the pressure.

[0030] Then, the conductivity of the liquid can be detected through the conductivity detection module on the mounting hole 3. The working electrode 33 and auxiliary electrode 34 on the insulating ring 32 start to work. The two working electrodes 33 are supplied with AC power to avoid DC changes caused by DC, while the two auxiliary electrodes 34 collect potential difference without current to eliminate the interference of electrode polarization resistance. Then, temperature, pressure and conductivity signals are collected through the control panel 71 to avoid data misalignment caused by the time difference of different parameter collection. At the same time, the impedance is measured in a wide frequency range from µHz to GHz through the impedance analyzer 11, and the detected signal is transmitted to the control panel 71 in the control cabinet 7 for processing and calculation of the conductivity of the detected liquid.

[0031] Throughout the entire testing process, the changes within the pressure chamber 13 can be observed through the observation window 24. The double-layered combination of the oxygen-free sealing ring and the modified polytetrafluoroethylene gasket 26 through the observation window 24 improves its sealing performance. After the test is completed, the solenoid valve 15 at the liquid inlet 14 is opened to control the pressure relief rate and prevent excessive pressure relief from causing the liquid in the pressure chamber 13 to boil or the pressure chamber 13 to be damaged due to sudden pressure changes. At the same time, the operation of the liquid nitrogen pump 54 and the heating film 61 is stopped, allowing the pressure chamber 13 to naturally heat up to room temperature to prevent the pipeline from freezing due to the discharge of liquid at low temperature. Then, the liquid to be tested is discharged, the chamber is cleaned with deionized water, and then dried for later use.

[0032] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make inventive modifications to this embodiment as needed, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. An experimental apparatus for testing the in-situ conductivity of liquids under ultra-high pressure and low temperature conditions, comprising an experimental table (1) and an impedance analyzer (11) placed on one side of the upper end of the experimental table (1), characterized in that: The experimental table (1) is provided with a placement rack (12) at the upper end. The upper end of the placement rack (12) is detachably connected to a hollow pressure-bearing cavity (13). The upper and lower ends of the outer wall of the pressure-bearing cavity (13) are respectively provided with an inlet hole (14) and an outlet hole (17). The inlet hole (14) is connected to a solenoid valve (15), and the outlet hole (17) is connected to a vacuum valve (18). The inlet hole (14) is equipped with a piezoelectric pressure sensor (16) connected to it. A vacuum pump (2) is installed on one side of the upper end of the experimental table (1). The vacuum pump (2) and the vacuum valve (18) are detachably connected with a vacuum tube (21). The other side of the upper end of the experimental table (1) is provided with a pressurizing component (4) connected to the solenoid valve (15). A temperature sensor (22) extending into the upper part of the outer wall of the pressure-bearing cavity (13) is installed on one side. An observation hole (23) is opened downward on the other side of the upper part of the outer wall. An observation window (24) is embedded in the observation hole (23) and sealed to it. The observation window (24) is press-fitted to the observation hole (23) by an oxygen-free sealing ring (25). A modified polytetrafluoroethylene gasket (26) is attached to the outer wall of the oxygen-free sealing ring (25). A plurality of equally spaced safety devices are opened on the outer wall of the pressure-bearing cavity (13) near its lower end. The mounting hole (3) is fitted with an in-situ conductivity detection module (31) that is sealed to and extends into the pressure chamber (13). A temperature control component (5) is provided on one side of the upper end of the experimental table (1) and is fitted to the outer wall of the pressure chamber (13). A heating compensation component (6) is provided on the outer wall of the temperature control component (5) and is sealed to it. A control cabinet (7) is provided on one side of the impedance analyzer (11) at the upper end of the experimental table (1). A control panel (71) is provided inside the control cabinet (7).

2. The experimental apparatus for testing the in-situ conductivity of liquids under ultra-high pressure and low temperature conditions according to claim 1, characterized in that: Both the solenoid valve (15) and the vacuum valve (18) are provided with a one-way valve (19) communicating with one end of the end that extends into the pressure chamber (13).

3. The experimental apparatus for testing the in-situ conductivity of liquids under ultra-high pressure and low temperature conditions according to claim 1, characterized in that: The temperature control component (5) includes a liquid nitrogen tank (51), a reflux tank (52), a heat exchange coil (53), a liquid nitrogen pump (54) disposed on one side of the liquid nitrogen tank (51), an inlet pipe (55) connected to the inlet of the liquid nitrogen pump (54) and extending to the bottom of the inner wall of the liquid nitrogen tank (51), an outlet pipe (56) disposed between the outlet of the liquid nitrogen pump (54) and the lower end of the heat exchange coil (53) and connected to both, and a reflux pipe (57) disposed between the upper end of the heat exchange coil (53) and the upper end of the outer wall of the reflux tank (52) and connected to both.

4. The experimental apparatus for testing the in-situ conductivity of liquids under ultra-high pressure and low temperature conditions according to claim 3, characterized in that: The heating compensation component (6) includes a heating film (61) disposed on the outer wall of the heat exchange coil (53), a heat insulation pad (62) disposed between the heating film (61) and the heating coil, and a heat insulation sleeve (63) disposed on the outer wall of the heating film (61).

5. The experimental apparatus for testing the in-situ conductivity of liquids under ultra-high pressure and low temperature conditions according to claim 1, characterized in that: The in-situ conductivity detection module (31) includes an insulating ring (32), two working electrodes (33) installed opposite to each other on the inner wall of the insulating ring (32), two auxiliary electrodes (34) respectively disposed between the two working electrodes (33), and insulating sleeves (35) respectively disposed on the outer walls of the working electrodes (33) and the auxiliary electrodes (34). The working electrodes (33), the auxiliary electrodes (34) and the corresponding insulating sleeves (35) are fixed together by high-temperature resistant sealant (36). The included angle between the two working electrodes (33) is 180° and the included angle between the two auxiliary electrodes (34) is 180°.

6. The experimental apparatus for testing the in-situ conductivity of liquids under ultra-high pressure and low temperature conditions according to claim 5, characterized in that: The insulating ring (32) and the insulating sleeve (35) are both made of alumina ceramic material, and the working electrode (33) and the auxiliary electrode (34) are both made of 99.99% platinum wire.

7. The experimental apparatus for testing the in-situ conductivity of liquids under ultra-high pressure and low temperature conditions according to claim 6, characterized in that: Each insulating sleeve (35) is wrapped with expanded polytetrafluoroethylene tape (37) on the outside, forming a flexible seal with the inner wall of the corresponding mounting hole (3).

8. The experimental apparatus for testing the in-situ conductivity of liquids under ultra-high pressure and low temperature conditions according to claim 1, characterized in that: The pressurization assembly (4) includes a pressurization pump (41), a pressure buffer (42) connected to the outlet of the pressurization pump (41), and a high-pressure pipeline (43) connected to the pressure buffer (42).

9. The experimental apparatus for testing the in-situ conductivity of liquids under ultra-high pressure and low temperature conditions according to claim 1, characterized in that: The pressure-bearing cavity (13) is made of 18Ni300 martensitic aging steel.

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