Device and method for measuring oxygen content in sodium heat pipe working medium

Abstract

This invention discloses a device and method for extracting and measuring the oxygen content in the working fluid of a sodium heat pipe. The device includes a power supply, a heat pipe shell, a heat pipe filling tube, an oxygen content averaging tube, a sodium filling tube, a vanadium wire, an electromagnetic induction coil, an electromagnetic shielding cover, an angle adjuster, a pressure welding machine, and an oxygen element analyzer. By placing a vanadium wire inside the heat pipe and utilizing the good compatibility between vanadium and oxygen, this invention can extract the oxygen content from a fully assembled, filled, and initially operated sodium heat pipe. The device is compact, simple in principle, safe, and reliable, and can extract the oxygen content of the working fluid after heating and testing the sodium heat pipe after filling. This provides a microscopic and feasible solution for studying the influence of impurities in heat pipes.

Description

Technical Field

[0001] This invention relates to the field of phase change heat exchange equipment technology, specifically to a device and method for extracting and measuring the oxygen content in the working fluid of a sodium heat pipe. Background Technology

[0002] High-temperature sodium heat pipes use sodium as the working medium and utilize the two-phase change of metallic sodium for heat transfer. They offer advantages such as high heat transfer efficiency, simple structure, and passive operation. Since only the internal working fluid moves during heat transfer, they possess the advantage of silent heat transfer, making them suitable for many specialized fields, such as waste heat removal systems in the secondary loop of nuclear reactors, space reactors, small nuclear power plants, industrial boilers, wing thermal protection, and silent underwater vehicles. The influence of oxygen in sodium heat pipes has a significant impact on heat transfer performance, making oxygen measurement an important part of research on the effects of impurities. Summary of the Invention

[0003] To achieve the extraction of oxygen from high-temperature sodium heat pipes after sealing and operation, the present invention aims to provide a device and method for extracting and measuring the oxygen content in the working fluid of sodium heat pipes. Utilizing the principle that vanadium and oxygen are highly compatible, the device extracts the oxygen content from a fully assembled, filled, and initially operated sodium heat pipe. The device is compact, simple in principle, safe, and reliable, and can extract the oxygen content of the working fluid after the sodium heat pipe has been filled and heated for testing. This provides a feasible microscopic solution for studying the influence of impurities in heat pipes.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] An oxygen content extraction and measurement device for a sodium heat pipe working fluid includes a power supply 1, a heat pipe shell 2, a heat pipe filling tube 3, an oxygen content averaging tube 4, a sodium filling tube 5, a vanadium wire 6, an electromagnetic induction coil 7, an electromagnetic shielding cover 8, an angle adjuster 9, a pressure welding machine 10, and an oxygen element analyzer 11. The heat pipe shell 2, the heat pipe filling tube 3, the oxygen content averaging tube 4, and the sodium filling tube 5 are connected in sequence and installed inside the electromagnetic induction coil 7. The electromagnetic induction coil 7 is used for heating and heat preservation. The electromagnetic induction coil 7 is powered by the power supply 1. An electromagnetic shielding cover 8 and an angle adjuster 9 are set externally to ensure the safety of electromagnetic induction and the adjustment of the experimental angle. The device also includes a pressure welding machine 10 and an oxygen element analyzer 11 for experimental operations after heating. The vanadium wire 6 passes through the sodium filling tube 5, the heat pipe filling tube 3, and the oxygen content averaging tube 4 in sequence and extends into the heat pipe shell 2.

[0006] The heat pipe shell 2, the heat pipe filling tube 3, the oxygen content averaging tube 4, and the sodium filling tube 5 are made of metal materials compatible with liquid sodium.

[0007] The metal material compatible with liquid sodium is stainless steel, niobium-zirconium alloy, Haynes 233 alloy, Inconel nickel, molybdenum, or tungsten.

[0008] The vanadium wire 6 is electron-beam welded to one side of the oxygen-average tube 4, with a diameter of 0.1 inches to prevent its influence on heat transfer in the heat pipe. The length of the vanadium wire 6 varies with the length of the heat pipe shell 2. The length of the vanadium wire 6 is the sum of the length of the evaporation section of the heat pipe shell 2 and the lengths of the liquid filling tube 3, the oxygen-average tube 4, and the sodium filling tube 5.

[0009] The pressure welding machine 10 employs forging welding, contact welding, friction welding, or gas pressure welding to ensure the sealing of the filling tube 3 after pressure welding.

[0010] The oxygen element analyzer 11 is used to measure the oxygen content in vanadium wire, and a paramagnetic oxygen analyzer, a zirconium oxide analyzer, or a laser oxygen analyzer can be selected.

[0011] The measurement method for the oxygen content extraction and measurement device in the working fluid of a sodium heat pipe includes the following steps:

[0012] Step 1: Using electron beam welding, vanadium wire 6 is welded to the inner wall of oxygen content averaging tube 4. Then, heat pipe shell 2, heat pipe filling tube 3, oxygen content averaging tube 4, and sodium filling tube 5 are welded sequentially. Vanadium wire 6 extends into heat pipe shell 2 through heat pipe filling tube 3, oxygen content averaging tube 4, and sodium filling tube 5 to form a whole. Helium testing is performed on the whole to ensure its airtightness. Then, a metered amount of liquid sodium is filled into heat pipe shell 2 through sodium filling tube 5. After filling is completed, pressure welding machine 10 is used to press and heat seal the upper part of sodium filling tube 5.

[0013] Step 2: The heat pipe shell 2 is placed inside the electromagnetic induction heating chamber, and a thermocouple is placed on the outside to measure the temperature during the test. The heat pipe is heated to 800℃-1000℃ using electromagnetic induction heating for 4-24 hours to ensure that the heat pipe is completely wetted. Then the device is inverted with the liquid filling tube 5 at the bottom to ensure that the vanadium wire 6 is immersed in liquid sodium. The heat pipe shell 2 is heated to 750℃-900℃ and kept at that temperature for 4-12 hours. During this process, the oxygen element in the sodium will gradually transfer to the vanadium wire to achieve an average oxygen content between the sodium and the vanadium wire.

[0014] Step 3: Turn the heat pipe shell 2 over again, heat the heat pipe to 100℃-150℃ and keep it at that temperature for 4-8 hours to solidify the liquid sodium into solid sodium, melt the solid sodium and let it flow back to the heat pipe evaporation section to ensure that there is no solid sodium in the tube 4 with average oxygen content.

[0015] Step 4: Use a pressure welding machine 10 to press the heat pipe filling tube 3 under an inert gas protection environment with a pressure of 30-50 tons, then heat and seal it. The heat pipe shell 2 part is a normal high-temperature sodium heat pipe. The vanadium wire 6 left there has no effect on the heat transfer capacity of the heat pipe due to its small diameter.

[0016] Step 5: Cut open the oxygen content averaging tube 4 under an inert gas protective environment and remove the vanadium wire 6;

[0017] Step 6: Place the vanadium wire 6 in ethanol at room temperature for 30-40 minutes to clean it, then rinse it with distilled water for 10-15 minutes to remove the sodium adhering to the vanadium wire; then polish the surface to 0.01 mm in an inert gas environment to remove surface contamination that occurred during the treatment and sodium removal, then rinse it with distilled water for 10-15 minutes and dry it, then cut it into 1 cm lengths and place it in a clean vial;

[0018] Step 7: Place the sample into the oxygen element analyzer 11 and repeat the measurement using samples from different parts to obtain the average oxygen content.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] The oxygen extraction device used in this invention utilizes the principle that most impurities in the sodium heat pipe have lower activity for oxygen than vanadium wire. The experimental steps are cleverly designed to ensure that the oxygen in the liquid sodium is balanced with the oxygen in the vanadium wire after operation. Then, existing technology is used to extract oxygen. The oxygen content is balanced and extracted using the oxygen content averaging tube 4. Afterward, the heat pipe filling tube 3 is pressure welded using the pressure welding machine 10, and the heat pipe structure is completed, which can still perform heat transfer.

[0021] To achieve the extraction of oxygen from the working fluid of a high-temperature sodium heat pipe after sealing and operation, this invention proposes a device and method for measuring the oxygen content in the working fluid of a sodium heat pipe. This method can ensure the accurate extraction of oxygen from the working fluid sodium after the heat pipe has been in operation, providing a microscopic and feasible solution for the study of the influence of impurities in the heat pipe. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a device for extracting oxygen from the working fluid of a sodium heat pipe.

[0023] Figure 2 This is a schematic diagram of a method for extracting oxygen from the working fluid of a sodium heat pipe. Detailed Implementation

[0024] To better illustrate the present invention, it will now be further described in conjunction with examples and accompanying drawings:

[0025] like Figure 1As shown, this invention discloses a device for extracting and measuring the oxygen content in a sodium heat pipe working fluid. The device includes a power supply 1, a heat pipe shell 2, a heat pipe filling tube 3, an oxygen content averaging tube 4, a sodium filling tube 5, a vanadium wire 6, an electromagnetic induction coil 7, an electromagnetic shielding cover 8, an angle adjuster 9, a welding machine 10, and an oxygen element analyzer 11. The heat pipe shell 2, heat pipe filling tube 3, oxygen content averaging tube 4, and sodium filling tube 5 are sequentially connected and installed inside the electromagnetic induction coil 7. The electromagnetic induction coil 7 is used for heating and heat preservation. It is powered by the power supply 1. An electromagnetic shielding cover 8 and an angle adjuster 9 are externally installed to ensure the safety of electromagnetic induction and the adjustment of the experimental angle. The welding machine 10 and the oxygen element analyzer 11 are located beside the system for experimental operations after heating. The vanadium wire 6 passes through the heat pipe filling tube 3, the oxygen content averaging tube 4, and the sodium filling tube 5 and extends into the heat pipe shell 2.

[0026] In a preferred embodiment of the present invention, the heat pipe shell 2, the heat pipe filling pipe 3, the oxygen content averaging pipe 4, and the sodium filling pipe 5 are made of metal materials compatible with liquid sodium, such as 310S stainless steel, 316 stainless steel, niobium-zirconium alloy, Haynes 233 alloy, etc.

[0027] In a preferred embodiment of the present invention, the vanadium wire 6 is electron-beam welded to one side of the oxygen content averaging tube 4, with a diameter of 0.1 inches to prevent its influence on heat transfer in the heat pipe. The length of the vanadium wire 6 varies with the length of the heat pipe shell 2, and the total length is the sum of the length of the evaporation section of the heat pipe shell 2 and the lengths of the liquid filling tube 3, the oxygen content averaging tube 4, and the sodium filling tube 5. This ensures that the heat pipe's sealing performance is not affected by the oxygen extraction operation and also ensures that the vanadium wire can fully contact the liquid sodium.

[0028] As a preferred embodiment of the present invention, the welding method of the pressure welding machine 10 can be forging welding, contact welding, friction welding, gas pressure welding, etc. to ensure the sealing of the filling tube 3 after pressure welding.

[0029] In a preferred embodiment of the present invention, the oxygen element analyzer 11 is used to measure the oxygen content in the vanadium wire. Using a paramagnetic oxygen analyzer, a zirconium oxide analyzer, or a laser oxygen analyzer can ensure the accuracy and reliability of oxygen element measurement, while not affecting the vanadium wire.

[0030] like Figure 2 As shown, the working principle of this invention is as follows: Vanadium wire 6 is welded to the inner wall of the oxygen-average tube 4 using electron beam welding. Then, the heat pipe shell 2, heat pipe filling tube 3, oxygen-average tube 4, and sodium filling tube 5 are welded sequentially. Vanadium wire 6 extends into the heat pipe shell 2 through the heat pipe filling tube 3, oxygen-average tube 4, and sodium filling tube 5 to form a whole. Helium testing is performed on the whole to ensure its airtightness. Then, a measured amount of liquid sodium is filled into the heat pipe shell 2 through the sodium filling tube 5. After filling, a pressure welding machine 10 is used to press and heat-seal the upper part of the sodium filling tube 5.

[0031] The heat pipe shell 2 is placed inside the electromagnetic induction heating element, and thermocouples are arranged on the outside to measure the temperature during the test. The heat pipe is heated to 800°C using electromagnetic induction heating and operated for 24 hours to ensure that the heat pipe is completely wetted. Then the device is inverted with the liquid filling tube 5 at the bottom, ensuring that the vanadium wire 6 is immersed in liquid sodium. The heat pipe shell 2 is heated to 750°C and held for 12 hours. During this process, oxygen in the sodium will gradually transfer to the vanadium wire to achieve an average oxygen content between the sodium and the vanadium wire.

[0032] The heat pipe shell 2 is flipped over again, and the heat pipe is heated to 100°C and kept at that temperature for 4 hours. This causes the liquid sodium to solidify into solid sodium, which then melts and flows back to the heat pipe evaporation section, ensuring that the oxygen content is average and that there is no solid sodium in the tube 4.

[0033] The heat pipe filling tube 3 is pressed and heated under an inert gas protection environment using a pressure welding machine 10. After heating, it is sealed. The heat pipe shell 2 is a normal high-temperature sodium heat pipe. The vanadium wire 6 left in it has no effect on the heat transfer capacity of the heat pipe due to its small diameter.

[0034] The oxygen content averaging tube 4 was cut open under an inert gas protective environment, and the vanadium wire 6 was removed.

[0035] Vanadium wire 6 was cleaned in ethanol at room temperature for 30 minutes, followed by rinsing with distilled water for 10 minutes to remove any sodium adhering to the vanadium wire. The surface was then polished to a layer of 0.01 mm in an inert gas environment to remove any surface contamination that occurred during the treatment and sodium removal process. It was then rinsed with distilled water for 10 minutes and dried. Samples were then cut into 1 cm lengths and placed in clean vials.

[0036] The sample is placed in the oxygen element analyzer 11, and the measurement is repeated using samples from different parts to obtain the average oxygen content.

[0037] Paramagnetic oxygen analyzers utilize the paramagnetic property of oxygen molecules. The gas being measured is drawn into a built-in magnetic field, where the oxygen molecules move in accordance with the magnetic field, generating a thrust on a suspended dumbbell ball. The oxygen content in the gas is determined by measuring the deflection of the dumbbell ball. Zirconia analyzers work by attaching porous platinum electrodes to both sides of a zirconia plate and subjecting it to high temperatures. If the oxygen content in the gases on both sides differs, an electromotive force (EMF) will appear between the electrodes, and the concentration difference can be obtained through this EMF. Laser oxygen analyzers determine gas concentration by analyzing the selective absorption of laser light by the gas. The greater the attenuation of the semiconductor laser light intensity as it passes through the gas being measured, the higher the gas concentration.

Claims

1. A device for extracting and measuring oxygen content in the working fluid of a sodium heat pipe, characterized in that: The device includes a power supply (1), a heat pipe shell (2), a heat pipe filling tube (3), an oxygen content averaging tube (4), a sodium filling tube (5), a vanadium wire (6), an electromagnetic induction coil (7), an electromagnetic shielding cover (8), an angle adjuster (9), a pressure welding machine (10), and an oxygen element analyzer (11). The heat pipe shell (2), the heat pipe filling tube (3), the oxygen content averaging tube (4), and the sodium filling tube (5) are connected in sequence and installed inside the electromagnetic induction coil (7). The electromagnetic induction coil (7) is used for heating and heat preservation. The electromagnetic induction coil (7) is powered by the power supply (1). An electromagnetic shielding cover (8) and an angle adjuster (9) are installed externally to ensure the safety of electromagnetic induction and the adjustment of the experimental angle. The device also includes a pressure welding machine (10) and an oxygen element analyzer (11) for experimental operations after heating. The vanadium wire (6) passes through the sodium filling tube (5), the heat pipe filling tube (3), and the oxygen content averaging tube (4) in sequence and extends into the heat pipe shell (2).

2. The oxygen content extraction and measurement device in the working fluid of a sodium heat pipe according to claim 1, characterized in that: The heat pipe shell (2), heat pipe filling pipe (3), oxygen content averaging pipe (4), and sodium filling pipe (5) are made of metal materials compatible with liquid sodium.

3. The oxygen content extraction and measurement device in the working fluid of a sodium heat pipe according to claim 2, characterized in that: The metal material compatible with liquid sodium is stainless steel, niobium-zirconium alloy, Haynes 233 alloy, Inconel nickel, molybdenum, or tungsten.

4. The oxygen content extraction and measurement device in the working fluid of a sodium heat pipe according to claim 1, characterized in that: The vanadium wire (6) is electron-beam welded to one side of the oxygen content averaging tube (4) with a diameter of 0.1 inches to prevent its influence on heat transfer in the heat pipe. The length of the vanadium wire (6) varies with the length of the heat pipe shell (2). The length of the vanadium wire (6) is the sum of the length of the evaporation section of the heat pipe shell (2) and the lengths of the heat pipe filling tube (3), the oxygen content averaging tube (4), and the sodium filling tube (5).

5. The oxygen content extraction and measurement device in the working fluid of a sodium heat pipe according to claim 1, characterized in that: The pressure welding machine (10) employs forging welding, contact welding, friction welding, or gas pressure welding to ensure the sealing of the filling pipe (3) after pressure welding.

6. The oxygen content extraction and measuring device in the working fluid of a sodium heat pipe according to claim 1, characterized in that: The oxygen element analyzer (11) is used to measure the oxygen content in vanadium wire. A paramagnetic oxygen analyzer, a zirconium oxide analyzer, or a laser oxygen analyzer may be selected.

7. The method for measuring the oxygen content extraction and measuring device in the working fluid of a sodium heat pipe according to any one of claims 1 to 6, characterized in that: The steps are as follows: Step 1: Using electron beam welding, vanadium wire (6) is welded to the inner wall of oxygen content averaging tube (4). Then, heat pipe shell (2), heat pipe filling tube (3), oxygen content averaging tube (4), and sodium filling tube (5) are welded in sequence. Vanadium wire (6) extends into heat pipe shell (2) through heat pipe filling tube (3), oxygen content averaging tube (4), and sodium filling tube (5) to form a whole. The whole is subjected to helium testing to ensure airtightness. Then, quantitative liquid sodium is filled into heat pipe shell (2) through sodium filling tube (5). After filling is completed, pressure welding machine (10) is used to press and heat seal the upper part of sodium filling tube (5). Step 2: The heat pipe shell (2) is placed inside the electromagnetic induction heating, and a thermocouple is arranged on the outside to measure the temperature during the test. The heat pipe is heated to 800℃-1000℃ using electromagnetic induction heating for 4-24 hours to ensure that the heat pipe is completely wetted. Then the device is inverted, with the liquid filling tube (5) at the bottom, to ensure that the vanadium wire (6) is immersed in liquid sodium. The heat pipe shell (2) is heated to 750℃-900℃ and kept at that temperature for 4 to 12 hours. During this process, the oxygen element in the sodium will gradually transfer to the vanadium wire, so that the oxygen content between the sodium and the vanadium wire is averaged. Step 3: Turn the heat pipe shell (2) over again, heat the heat pipe to 100℃-150℃ and keep it at that temperature for 4-8 hours, so that the liquid sodium solidifies into solid sodium, and the solid sodium melts and flows back to the heat pipe evaporation section, ensuring that there is no solid sodium in the tube (4) with average oxygen content. Step 4: Use a pressure welding machine (10) to press the heat pipe filling tube (3) under an inert gas protection environment with a pressure of 30-50 tons, then heat and seal it. The heat pipe shell (2) part is a normal high temperature sodium heat pipe. The vanadium wire (6) left there has no effect on the heat transfer capacity of the heat pipe due to its small diameter. Step 5: Cut open the oxygen content averaging tube (4) under an inert gas protection environment and remove the vanadium wire (6); Step 6: Place the vanadium wire (6) in ethanol at room temperature for cleaning, then rinse with distilled water to remove sodium adhering to the vanadium wire; then polish the surface 0.01 mm in an inert gas environment to remove surface contamination that occurred during the processing and sodium removal, then rinse and dry with distilled water, and cut into 1 cm length samples and place them in clean vials. Step 7: Place the sample into the oxygen element analyzer (11) and repeat the measurement using samples from different parts to obtain the average oxygen content.

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