Spiral single-rod single-channel experimental device and experimental method based on additive manufacturing

Abstract

The application discloses a spiral single-rod single-channel experimental device based on additive manufacturing and an experimental method, and relates to the technical field of experimental devices.The spiral rod in the experimental device is processed by using additive manufacturing technology, and the surface clamping piece structure of the spiral rod can realize wall temperature measurement.The heating rod and the spiral rod processed by additive manufacturing can be matched to form a spiral heating rod.Different working condition experiments can be carried out by controlling the heating power of the spiral heating rod, the experimental loop flow and the temperature of the lower chamber.Through collecting and recording the differential pressure transmitter, the wall temperature and the fluid temperature data, the flow heat transfer characteristics of the spiral single-rod single-channel can be obtained, thereby providing support for the design and safety analysis of the spiral nuclear fuel.

Description

Technical Field

[0001] The present invention relates to the technical field of experimental devices, and in particular to a spiral single-rod single-channel experimental device and an experimental method based on additive manufacturing. Background Art

[0002] Helical nuclear fuel offers the advantages of enhanced heat transfer and self-aligning support, potentially increasing the core power density of lead-bismuth reactors and eliminating the need for a positioning grid. To support the design of helical nuclear fuel, flow heat transfer experiments involving helical rods using lead-bismuth alloy as the medium are necessary. Due to the high electrical conductivity of lead-bismuth alloy, good electrical insulation is required between the helical heating rod and the medium. Existing experimental setups for flow heat transfer in lead-bismuth alloys use cylindrical heating rods, which are easy to manufacture. Helical heating rods have not been reported, and traditional manufacturing methods for helical heating rods are difficult. Existing experimental setups for helical heating rods are machined using turning and rely on a DC power supply for resistive heating. This manufacturing method is suitable for insulating fluids but not for lead-bismuth alloys. Furthermore, the wall temperature of the heating rod is a key measurement parameter in flow heat transfer experiments. Existing experimental setups primarily measure this temperature using deeply embedded thermocouple probes, a method suitable for cylindrical heating rods but not for irregularly shaped helical heating rods. Therefore, a new manufacturing and wall temperature measurement method is needed for helical heating rods used in flow heat transfer experiments in lead-bismuth alloys. Summary of the Invention

[0003] To overcome the aforementioned problems of the prior art, the present invention aims to provide a spiral single-rod, single-channel experimental apparatus and method based on additive manufacturing. This apparatus utilizes additive manufacturing technology to fabricate a thermocouple clamping device for measuring wall temperature, enabling convenient and accurate wall temperature measurement. Furthermore, the spiral rod can be assembled with a heating rod to heat the spiral rod. The present experimental apparatus enables experiments on the flow and heat transfer characteristics of a lead-bismuth alloy medium, generating flow and heat transfer data that can support spiral nuclear fuel design and reactor safety analysis.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A spiral single-rod single-channel experimental device based on additive manufacturing, the experimental device includes a spiral heating rod 1, an upper chamber 2, an upper chamber temperature measuring component 3, an upper flange 4, a middle cylinder 5, a lower flange 6, a lower chamber temperature measuring component 7, a lower chamber 8, a high-pressure end pressure leading component 9, a low-pressure end pressure leading component 10 and a differential pressure transmitter 11; the middle cylinder 5 is located in the middle of the experimental device, the upper chamber 2 is located on the upper part of the middle cylinder 5, the lower chamber 8 is located on the lower part of the middle cylinder 5, the upper chamber 2 and the middle cylinder 5 are connected by the upper flange 4, and the lower chamber 8 and the middle cylinder 5 are connected by the lower flange 6; the high-pressure end The pressure-leading assembly 9 and the low-pressure-end pressure-leading assembly 10 are located on the side of the middle cylinder 5 and close to the upper chamber 2. The low-pressure-end pressure-leading assembly 10 is located on the upper part of the high-pressure-end pressure-leading assembly 9. The high-pressure-end pressure-leading assembly 9 and the low-pressure-end pressure-leading assembly 10 are vertically welded to the middle cylinder 5. The high-pressure end and the low-pressure end of the differential pressure transmitter 11 are flange-connected to the high-pressure-end pressure-leading assembly 9 and the low-pressure-end pressure-leading assembly 10 respectively; the upper chamber temperature measuring assembly 3 is vertically welded to the outside of the upper chamber 2, and the lower chamber temperature measuring assembly 7 is vertically welded to the outside of the lower chamber 8; during the experiment, the upper chamber 2 and the lower chamber 8 are both connected to the experimental circuit;

[0006] The spiral heating rod 1 includes a cylindrical heating rod 1-1, a first spiral rod 1-2, a second spiral rod 1-3 and a third spiral rod 1-4; the first spiral rod 1-2, the second spiral rod 1-3 and the third spiral rod 1-4 are respectively located at the upper, middle and lower parts of the inner side of the middle cylinder 5, the bottom end of the first spiral rod 1-2 and the top end of the second spiral rod 1-3 are welded together, and the bottom end of the second spiral rod 1-3 and the top end of the third spiral rod 1-4 are welded together; the cylindrical heating rod 1-1 is located in the central inner hole of the first spiral rod 1-2, the second spiral rod 1-3 and the third spiral rod 1-4, and the top end of the cylindrical heating rod 1-1 passes through the first spiral rod 1-2 and is fixedly connected to the upper chamber 2 by a ferrule;

[0007] The first spiral rod 1-2, the second spiral rod 1-3 and the third spiral rod 1-4 are all manufactured using additive manufacturing technology. The surface of the first spiral rod 1-2 is processed with a thermocouple clamping device using additive manufacturing technology. The thermocouple clamping device includes a thermocouple probe lobe clip 1-2-1, a thermocouple probe groove 1-2-2, a thermocouple probe lobe valley clip 1-2-3 and a thermocouple sleeve clip 1-2-4; the thermocouple probe lobe clip 1-2-1 is located near the center line of the lobe surface of the first spiral rod 1-2, the thermocouple probe groove 1-2-2 is located on the inner side of the thermocouple probe lobe clip 1-2-1; the thermocouple probe lobe valley clip 1-2-3 is located on the first spiral rod 1-2 Near the midline of the valley surface of spiral rod 1-2, thermocouple probe lobe clip 1-2-1 and thermocouple probe lobe clip 1-2-3 are located on the same height cross section of the first spiral rod 1-2; thermocouple sheath clip 1-2-4 is located near the midline of the valley surface of the first spiral rod 1-2. Two thermocouple sheath clips 1-2-4 are located on the same height cross section of the first spiral rod 1-2. Thermocouple sheath clip 1-2-4 is located above thermocouple probe lobe clip 1-2-1 and thermocouple probe lobe clip 1-2-3; the surface of the second spiral rod 1-3 is processed using additive manufacturing technology with a thermocouple clamping device identical to that of the first spiral rod 1-2;

[0008] The experimental device also includes a first temperature measuring section AA, a second temperature measuring section BB and a third temperature measuring section CC for measuring the wall temperature of the spiral heating rod and the temperature of the fluid outside the spiral heating rod; the fluid outside the spiral heating rod is liquid lead-bismuth fluid.

[0009] The first temperature measuring section AA and the second temperature measuring section BB are located on the first spiral rod 1 - 2 , and the third temperature measuring section CC is located on the second spiral rod 1 - 3 .

[0010] The measuring points of the first temperature measuring section AA include the first wall temperature measuring point A-1, the second wall temperature measuring point A-2, the first fluid temperature measuring point A-3 and the second fluid temperature measuring point A-4. The first wall temperature measuring point A-1 is located at the center line of the lobe of the first spiral rod 1-2, the second wall temperature measuring point A-2 is located at the center line of the leaf valley of the first spiral rod 1-2, the first fluid temperature measuring point A-3 and the second fluid temperature measuring point A-4 are located in the fluid area near the leaf valley of the first spiral rod 1-2; the second temperature measuring section BB and the third temperature measuring section CC have the same measuring point arrangement as the first temperature measuring section AA.

[0011] The thermocouple probe at the first wall temperature measuring point A-1 is placed in the thermocouple probe groove 1-2-2 on the inner side of the thermocouple probe lobe clip 1-2-1, and pressing the thermocouple probe lobe clip 1-2-1 inward can fix the thermocouple probe; the thermocouple probe at the second wall temperature measuring point A-2 is placed on the inner side of the thermocouple probe valley clip 1-2-3, and pressing the thermocouple probe valley clip 1-2-3 inward can fix the thermocouple probe; the thermocouple sleeve is placed on the inner side of the thermocouple sleeve clip 1-2-4, and pressing the thermocouple sleeve clip 1-2-4 inward can fix the thermocouple sleeve, and the thermocouple sleeve is wrapped around the surface of the spiral rod and led out from the top of the first spiral rod 1-2.

[0012] The first spiral rod 1-2, the second spiral rod 1-3 and the third spiral rod 1-4 are all made of additively manufactured 316L stainless steel material.

[0013] The experimental method of the spiral single-rod single-channel experimental device based on additive manufacturing is achieved by the following steps:

[0014] Step 1: Test the working performance of the thermocouples on the first temperature measuring section AA, the second temperature measuring section BB and the third temperature measuring section CC. If they meet the requirements, proceed to the next step.

[0015] Step 2: Connect the upper chamber 2 and the lower chamber 8 of the experimental device to the pipe of the experimental circuit. After testing the air tightness of the experimental circuit and confirming that there is no problem, proceed to the next step;

[0016] Step 3: Conduct flow resistance experiment of spiral single-rod single-channel experimental device:

[0017] The first step is to adjust the electromagnetic pump current to obtain the specified experimental loop flow;

[0018] The second step is to adjust the power of the heating section of the experimental circuit and stop heating after the temperature of the lower chamber 8 of the spiral single-rod single-channel experimental device reaches the specified temperature;

[0019] The third step is to control the heating power of the experimental circuit heating wire to ensure that the temperature deviation between the upper chamber 2 and the lower chamber 8 of the spiral single-rod single-channel experimental device is less than 1.5°C;

[0020] Step 4: Record the pressure difference Δp1 under the specified flow condition for no less than 60 seconds;

[0021] Step 5: Stop the electromagnetic pump and record the pressure difference Δp2 under static conditions of the lead-bismuth medium;

[0022] Step 6: Repeat steps 1 to 5 to obtain experimental data under different flow rates and inlet temperatures.

[0023] Step 7: Calculate the Darcy friction coefficient using experimental data:

[0024]

[0025] Where f is the Darcy friction coefficient; ρ is the density, kg / m 3 ; l is the distance between the high-pressure end pressure-leading assembly 9 and the low-pressure end pressure-leading assembly 10, m; u is the inlet velocity, m / s; D h is the hydraulic diameter, m;

[0026] Step 4: Conduct heat transfer experiments on the spiral single-rod single-channel experimental device:

[0027] Step 1: Adjust the electromagnetic pump current to obtain the specified experimental loop flow;

[0028] Step 2: Adjust the power of the heating section of the experimental circuit and stop heating after the temperature of the lower chamber 8 of the spiral single-rod single-channel experimental device reaches the specified value;

[0029] Step 3: Control the heating power of the experimental circuit heating wire to ensure that the temperature deviation between the upper chamber 2 and the lower chamber 8 of the spiral single-rod single-channel experimental device is less than 1.5°C;

[0030] Step 4: Adjust the cylindrical heating rod 1-1 in the spiral single-rod single-channel experimental device to the specified heating power P;

[0031] Step 5: When the temperature of the upper chamber 2 and the lower chamber 8 does not change by more than 0.5°C within 60 seconds, record the temperature and flow rate experimental data under the specified flow rate condition for no less than 60 seconds;

[0032] Step 6: Repeat steps 1 to 5 to obtain experimental data under different flow rates, inlet temperatures, and heating powers.

[0033] Step 7: Use the experimental data to calculate the average wall heat transfer coefficient and Nusselt number of the experimental device:

[0034]

[0035]

[0036] Where A is the wall area of ​​the spiral heating rod, m 2 ;T w,ave is the average temperature of the experimental device wall; T w,ave is the average fluid temperature of the experimental device, °C; Nu is the Nusselt number; h is the average wall heat transfer coefficient of the experimental device, W / m 2 ;λ thermal conductivity, W / (m·K).

[0037] Compared with the prior art, the present invention has the following advantages:

[0038] 1. The spiral heating rod in the experimental device of this invention utilizes additive manufacturing technology, enabling the fabrication of complex structures, including wall temperature measurement structures. Existing spiral heating rods are machined using turning methods and rely on a DC power supply for resistive heating. This manufacturing method is suitable for insulating fluids but not for lead-bismuth alloys. The spiral heating rod of this invention utilizes additive manufacturing technology, with a central inner hole that can be compatible with cylindrical heating rods, meeting the requirements of convective heat transfer experiments.

[0039] Existing technologies for measuring the wall temperature of heating rods primarily rely on deeply embedded thermocouple probes, which are suitable for cylindrical heating rods but not for spiral ones. This invention utilizes additive manufacturing technology to create a wall temperature measurement structure, enabling accurate measurement while minimizing interference from the thermowell.

[0040] 2. The experimental device of the present invention can still be used to carry out flow heat transfer characteristic experiments on electrically insulating heat transfer fluids.

[0041] 3. The flow resistance test method of the present invention can eliminate the influence of the gravity pressure difference at different temperatures; the heat transfer test method of the present invention can eliminate the influence of heat loss of the experimental device, and can obtain more accurate experimental results. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a schematic diagram of the main structure of the single-rod single-channel experimental device of the present invention.

[0043] Figure 2 This is a schematic diagram of the top view of the single-rod single-channel experimental device of the present invention.

[0044] Figure 3 This is a schematic diagram of the spiral heating rod structure of the single-rod single-channel experimental device of the present invention.

[0045] Figure 4 This is a schematic diagram of the spiral rod surface clamp structure of the single-rod single-channel experimental device of the present invention.

[0046] Figure 5 This is a distribution diagram of measuring points in the first temperature measurement section AA of the single-rod single-channel experimental device of the present invention.

[0047] Figure 6a and Figure 6b They are the fluid domain and wall temperature distribution diagrams of the numerical calculation results of the single-rod single-channel experimental device of the present invention. DETAILED DESCRIPTION

[0048] The present invention provides a spiral single-rod single-channel experimental device and experimental method based on additive manufacturing, which will now be further described in detail with reference to the accompanying drawings.

[0049] like Figure 1 and Figure 2As shown, the present invention is a spiral single-rod single-channel experimental device based on additive manufacturing, which includes a spiral heating rod 1, an upper chamber 2, an upper chamber temperature measuring assembly 3, an upper flange 4, a middle cylinder 5, a lower flange 6, a lower chamber temperature measuring assembly 7, a lower chamber 8, a high-pressure end pressure leading assembly 9, a low-pressure end pressure leading assembly 10 and a differential pressure transmitter 11; the middle cylinder 5 is located in the middle of the experimental device, the upper chamber 2 is located on the upper part of the middle cylinder 5, and the lower chamber 8 is located on the lower part of the middle cylinder 5. The upper chamber 2 and the middle cylinder 5 are connected by the upper flange 4, and the lower chamber 8 and the middle cylinder 5 are connected by the lower flange 6. The high-pressure end pressure-leading assembly 9 and the low-pressure end pressure-leading assembly 10 are located on the side of the middle cylinder 5 and close to the upper chamber 2. The low-pressure end pressure-leading assembly 10 is located on the upper part of the high-pressure end pressure-leading assembly 9. The high-pressure end pressure-leading assembly 9 and the low-pressure end pressure-leading assembly 10 are vertically welded to the middle cylinder 5. The high-pressure end and the low-pressure end of the differential pressure transmitter 11 are flange-connected to the high-pressure end pressure-leading assembly 9 and the low-pressure end pressure-leading assembly 10 respectively; the upper chamber temperature measuring assembly 3 is vertically welded to the outside of the upper chamber 2, and the lower chamber temperature measuring assembly 7 is vertically welded to the outside of the lower chamber 8; during the experiment, the upper chamber 2 and the lower chamber 8 are both connected to the experimental circuit.

[0050] like Figure 3 As shown, the spiral heating rod 1 includes a cylindrical heating rod 1-1, a first spiral rod 1-2, a second spiral rod 1-3 and a third spiral rod 1-4; the first spiral rod 1-2, the second spiral rod 1-3 and the third spiral rod 1-4 are respectively located at the upper, middle and lower parts of the inner side of the middle cylinder 5, the bottom end of the first spiral rod 1-2 and the top end of the second spiral rod 1-3 are welded together, and the bottom end of the second spiral rod 1-3 and the top end of the third spiral rod 1-4 are welded together; the cylindrical heating rod 1-1 is located in the central inner hole of the first spiral rod 1-2, the second spiral rod 1-3 and the third spiral rod 1-4, and the top end of the cylindrical heating rod 1-1 passes through the first spiral rod 1-2 and is fixed to the upper chamber 2 by a sleeve.

[0051] like Figure 4As shown, the first spiral rod 1-2, the second spiral rod 1-3 and the third spiral rod 1-4 are all made by additive manufacturing technology. The surface of the first spiral rod 1-2 is processed with a thermocouple clamping device by additive manufacturing technology. The thermocouple clamping device includes a thermocouple probe lobe clip 1-2-1, a thermocouple probe groove 1-2-2, a thermocouple probe lobe valley clip 1-2-3 and a thermocouple sleeve clip 1-2-4; the thermocouple probe lobe clip 1-2-1 is located near the center line of the lobe surface of the first spiral rod 1-2, and the thermocouple probe groove 1-2-2 is located on the inner side of the thermocouple probe lobe clip 1-2-1; the thermocouple probe lobe valley clip 1-2-3 is located on the first spiral rod 1-2. Near the midline of the leaf valley surface of the spiral rod 1-2, the thermocouple probe lobe clip 1-2-1 and the thermocouple probe lobe valley clip 1-2-3 are located on the same height cross section of the first spiral rod 1-2; the thermocouple sleeve clip 1-2-4 is located near the midline of the leaf valley surface of the first spiral rod 1-2, and there are two thermocouple sleeve clips 1-2-4 on the same height cross section of the first spiral rod 1-2, and the thermocouple sleeve clip 1-2-4 is located above the thermocouple probe lobe clip 1-2-1 and the thermocouple probe lobe valley clip 1-2-3; the surface of the second spiral rod 1-3 is processed with a thermocouple clamping device identical to that of the first spiral rod 1-2 using additive manufacturing technology.

[0052] like Figure 1 As shown, the experimental device also includes a first temperature measuring section AA, a second temperature measuring section BB and a third temperature measuring section CC for measuring the wall temperature of the spiral heating rod and the temperature of the fluid outside the spiral heating rod; the fluid outside the spiral heating rod is liquid lead-bismuth fluid.

[0053] As a preferred embodiment of the present invention, the first temperature measuring section AA and the second temperature measuring section BB are located on the first spiral rod 1-2, and the third temperature measuring section CC is located on the second spiral rod 1-3. This design can reduce the mutual influence of different temperature measuring sections, and the processed measurement data can be verified with each other, thereby improving the measurement accuracy.

[0054] As a preferred embodiment of the present invention, Figure 5 As shown, the measuring points of the first temperature measurement section AA include the first wall temperature measuring point A-1, the second wall temperature measuring point A-2, the first fluid temperature measuring point A-3, and the second fluid temperature measuring point A-4. The first wall temperature measuring point A-1 is located at the centerline of the lobe of the first spiral rod 1-2, the second wall temperature measuring point A-2 is located at the centerline of the lobe valley of the first spiral rod 1-2, and the first fluid temperature measuring point A-3 and the second fluid temperature measuring point A-4 are located in the fluid region near the lobe valley of the first spiral rod 1-2. This design can obtain fluid and wall temperatures at typical locations in the spiral single-rod single-channel experimental device, making the experimental conclusions more widely applicable. The measuring point arrangement of the second temperature measurement section BB and the third temperature measurement section CC is the same as that of the first temperature measurement section AA.

[0055] As a preferred embodiment of the present invention, the thermocouple probe at the first wall temperature measurement point A-1 is placed in the thermocouple probe groove 1-2-2 inside the thermocouple probe lobe clip 1-2-1. Pressing the thermocouple probe lobe clip 1-2-1 inwardly secures the thermocouple probe. The thermocouple probe at the second wall temperature measurement point A-2 is placed inside the thermocouple probe valley clip 1-2-3. Pressing the thermocouple probe valley clip 1-2-3 inwardly secures the thermocouple probe. The thermocouple sheath is placed inside the thermocouple sheath clip 1-2-4. Pressing the thermocouple sheath clip 1-2-4 inwardly secures the thermocouple sheath. The thermocouple sheath is wrapped around the surface of the spiral rod and leads out from the top of the first spiral rod 1-2. This design can utilize the characteristics of the outer wall of the spiral heating rod to reduce the influence of the thermocouple sheath on the flow field, thereby improving measurement accuracy. In addition, by fixing the thermocouple probe lobe clip 1-2-1, the thermocouple sleeve clip 1-2-2 and the thermocouple probe valley clip 1-2-3 together, the thermocouple is fixed more firmly, reducing the risk of the thermocouple being washed away by the fluid.

[0056] As a preferred embodiment of the present invention, the first spiral rod 1-2, the second spiral rod 1-3 and the third spiral rod 1-4 are all made of additively manufactured 316L stainless steel, which has low processing cost and a relatively mature additive manufacturing technology with higher manufacturing precision.

[0057] The experimental method of the spiral single-rod single-channel experimental device based on additive manufacturing is achieved by the following steps:

[0058] Step 1: Test the working performance of the thermocouples on the first temperature measuring section AA, the second temperature measuring section BB and the third temperature measuring section CC. If they meet the requirements, proceed to the next step.

[0059] Step 2: Connect the upper chamber 2 and the lower chamber 8 of the experimental device to the pipe of the experimental circuit. After testing the air tightness of the experimental circuit and confirming that there is no problem, proceed to the next step;

[0060] Step 3: Conduct flow resistance experiment of spiral single-rod single-channel experimental device:

[0061] The first step is to adjust the electromagnetic pump current to obtain the specified experimental loop flow;

[0062] The second step is to adjust the power of the heating section of the experimental circuit and stop heating after the temperature of the lower chamber 8 of the spiral single-rod single-channel experimental device reaches the specified temperature;

[0063] The third step is to control the heating power of the experimental circuit heating wire to ensure that the temperature deviation between the upper chamber 2 and the lower chamber 8 of the spiral single-rod single-channel experimental device is less than 1.5°C;

[0064] Step 4: Record the pressure difference Δp1 under the specified flow condition for no less than 60 seconds;

[0065] Step 5: Stop the electromagnetic pump and record the pressure difference Δp2 under static conditions of the lead-bismuth medium;

[0066] Step 6: Repeat steps 1 to 5 to obtain experimental data under different flow rates and inlet temperatures.

[0067] Step 7: Calculate the Darcy friction coefficient using experimental data:

[0068]

[0069] Where f is the Darcy friction coefficient; ρ is the density, kg / m 3 ; l is the distance between the high-pressure end pressure-leading assembly 9 and the low-pressure end pressure-leading assembly 10, m; u is the inlet velocity, m / s; D h is the hydraulic diameter, m;

[0070] Step 4: Conduct heat transfer experiments on the spiral single-rod single-channel experimental device:

[0071] Step 1: Adjust the electromagnetic pump current to obtain the specified experimental loop flow;

[0072] Step 2: Adjust the power of the heating section of the experimental circuit and stop heating after the temperature of the lower chamber 8 of the spiral single-rod single-channel experimental device reaches the specified value;

[0073] Step 3: Control the heating power of the experimental circuit heating wire to ensure that the temperature deviation between the upper chamber 2 and the lower chamber 8 of the spiral single-rod single-channel experimental device is less than 1.5°C;

[0074] Step 4: Adjust the cylindrical heating rod 1-1 in the spiral single-rod single-channel experimental device to the specified heating power P;

[0075] Step 5: When the temperature of the upper chamber 2 and the lower chamber 8 does not change by more than 0.5°C within 60 seconds, record the temperature and flow rate experimental data under the specified flow rate condition for no less than 60 seconds;

[0076] Step 6: Repeat steps 1 to 5 to obtain experimental data under different flow rates, inlet temperatures, and heating powers.

[0077] Step 7: Use the experimental data to calculate the average wall heat transfer coefficient and Nusselt number of the experimental device:

[0078]

[0079]

[0080] Where A is the wall area of ​​the spiral heating rod, m2 ;T w,ave is the average temperature of the experimental device wall; T w,ave is the average fluid temperature of the experimental device, °C; Nu is the Nusselt number; h is the average wall heat transfer coefficient of the experimental device, W / m 2 ;λ thermal conductivity, W / (m·K).

[0081] like Figure 6a and Figure 6b As shown, the spiral heating rod wall has the same temperature value in the leaf valley region and the leaf lobe region. Therefore, only one thermocouple is required within the same height section of the thermocouple probe to measure the leaf lobe and leaf valley wall temperatures. The temperature distribution of the fluid outside the spiral heating rod shows that the fluid temperature in the leaf valley and leaf lobe regions is closer to the wall temperature. Therefore, a thermocouple probe placed close to the wall can obtain a more accurate wall temperature.

Claims

1. A spiral single-rod single-channel experimental device based on additive manufacturing, characterized by: The experimental device comprises a spiral heating rod (1), an upper chamber (2), an upper chamber temperature measuring assembly (3), an upper flange (4), a middle cylinder (5), a lower flange (6), a lower chamber temperature measuring assembly (7), a lower chamber (8), a high-pressure end pressure-inducing assembly (9), a low-pressure end pressure-inducing assembly (10) and a differential pressure transmitter (11); the middle cylinder (5) is located in the middle of the experimental device, the upper chamber (2) is located in the upper part of the middle cylinder (5), the lower chamber (8) is located in the lower part of the middle cylinder (5), the upper chamber (2) and the middle cylinder (5) are connected by the upper flange (4), and the lower chamber (8) and the middle cylinder (5) are connected by the lower flange (6); the high-pressure end pressure-inducing assembly ( 9) and the low-pressure end pressure-leading assembly (10) are located on the side of the middle cylinder (5) and close to the upper chamber (2), the low-pressure end pressure-leading assembly (10) is located on the upper part of the high-pressure end pressure-leading assembly (9), the high-pressure end pressure-leading assembly (9) and the low-pressure end pressure-leading assembly (10) are vertically welded to the middle cylinder (5), and the high-pressure end and the low-pressure end of the differential pressure transmitter (11) are respectively flange-connected to the high-pressure end pressure-leading assembly (9) and the low-pressure end pressure-leading assembly (10); the upper chamber temperature measuring assembly (3) is vertically welded to the outside of the upper chamber (2), and the lower chamber temperature measuring assembly (7) is vertically welded to the outside of the lower chamber (8); during the experiment, the upper chamber (2) and the lower chamber (8) are both connected to the experimental circuit; The spiral heating rod (1) comprises a cylindrical heating rod (1-1), a first spiral rod (1-2), a second spiral rod (1-3) and a third spiral rod (1-4); the first spiral rod (1-2), the second spiral rod (1-3) and the third spiral rod (1-4) are respectively located at the upper part, the middle part and the lower part of the inner side of the middle cylinder (5); the bottom end of the first spiral rod (1-2) and the top end of the second spiral rod (1-3) are welded together, and the bottom end of the second spiral rod (1-3) and the top end of the third spiral rod (1-4) are welded together; the cylindrical heating rod (1-1) is located at the central inner hole of the first spiral rod (1-2), the second spiral rod (1-3) and the third spiral rod (1-4); the top end of the cylindrical heating rod (1-1) passes through the first spiral rod (1-2) and is fixedly connected to the upper chamber (2) by a ferrule; The first spiral rod (1-2), the second spiral rod (1-3) and the third spiral rod (1-4) are all manufactured using additive manufacturing technology. A thermocouple clamping device is processed on the surface of the first spiral rod (1-2) using additive manufacturing technology. The thermocouple clamping device includes a thermocouple probe lobe clip (1-2-1), a thermocouple probe groove (1-2-2), a thermocouple probe valley clip (1-2-3) and a thermocouple sleeve clip (1-2-4); the thermocouple probe lobe clip (1-2-1) is located near the center line of the lobe surface of the first spiral rod (1-2), the thermocouple probe groove (1-2-2) is located on the inner side of the thermocouple probe lobe clip (1-2-1); the thermocouple probe valley clip (1-2-3) is located on the first spiral rod (1-2) Near the midline of the leaf valley surface of the spiral rod (1-2), the thermocouple probe leaf lobe clip (1-2-1) and the thermocouple probe leaf valley clip (1-2-3) are located on the same height cross section of the first spiral rod (1-2); the thermocouple sleeve clip (1-2-4) is located near the midline of the leaf valley surface of the first spiral rod (1-2), and there are two thermocouple sleeve clips (1-2-4) on the same height cross section of the first spiral rod (1-2), and the thermocouple sleeve clip (1-2-4) is located on the upper part of the thermocouple probe leaf lobe clip (1-2-1) and the thermocouple probe leaf valley clip (1-2-3); the surface of the second spiral rod (1-3) is processed with a thermocouple clamping device identical to that of the first spiral rod (1-2) using additive manufacturing technology; The experimental device also includes a first temperature measuring section (AA), a second temperature measuring section (BB) and a third temperature measuring section (CC) for measuring the wall temperature of the spiral heating rod and the temperature of the fluid outside the spiral heating rod; the fluid outside the spiral heating rod is liquid lead-bismuth fluid.

2. The spiral single-rod single-channel experimental device based on additive manufacturing according to claim 1, characterized in that: The first temperature measuring section (AA) and the second temperature measuring section (BB) are located on the first spiral rod (1-2), and the third temperature measuring section (CC) is located on the second spiral rod (1-3).

3. The spiral single-rod single-channel experimental device based on additive manufacturing according to claim 1, characterized in that: The measuring points of the first temperature measuring section (AA) include a first wall temperature measuring point (A-1), a second wall temperature measuring point (A-2), a first fluid temperature measuring point (A-3) and a second fluid temperature measuring point (A-4); the first wall temperature measuring point (A-1) is located at the center line of the lobe of the first spiral rod (1-2); the second wall temperature measuring point (A-2) is located at the center line of the leaf valley of the first spiral rod (1-2); the first fluid temperature measuring point (A-3) and the second fluid temperature measuring point (A-4) are located in the fluid area near the leaf valley of the first spiral rod (1-2); and the measuring points of the second temperature measuring section (BB) and the third temperature measuring section (CC) are arranged in the same manner as the first temperature measuring section (AA).

4. The spiral single-rod single-channel experimental device based on additive manufacturing according to claim 3, characterized in that: The thermocouple probe at the first wall temperature measuring point (A-1) is placed in a thermocouple probe groove (1-2-2) on the inner side of a thermocouple probe lobe clip (1-2-1), and the thermocouple probe can be fixed by pressing the thermocouple probe lobe clip (1-2-1) inwardly; the thermocouple probe at the second wall temperature measuring point (A-2) is placed on the inner side of a thermocouple probe valley clip (1-2-3), and the thermocouple probe can be fixed by pressing the thermocouple probe valley clip (1-2-3) inwardly; the thermocouple sleeve is placed on the inner side of a thermocouple sleeve clip (1-2-4), and the thermocouple sleeve can be fixed by pressing the thermocouple sleeve clip (1-2-4) inwardly; the thermocouple sleeve is wound on the surface of the spiral rod and is led out from the top end of the first spiral rod (1-2).

5. The spiral single-rod single-channel experimental device based on additive manufacturing according to claim 1, characterized in that: The first spiral rod (1-2), the second spiral rod (1-3) and the third spiral rod (1-4) are all made of additively manufactured 316L stainless steel material.

6. The experimental method of the additively manufactured spiral single-rod single-channel experimental device according to any one of claims 1 to 5, characterized in that: The method is achieved by the following steps: Step 1: Test the working performance of the thermocouples on the first temperature measurement section (AA), the second temperature measurement section (BB), and the third temperature measurement section (CC). If they meet the requirements, proceed to the next step; Step 2: Connect the upper chamber (2) and the lower chamber (8) of the experimental device to the pipe of the experimental circuit, and proceed to the next step after testing the airtightness of the experimental circuit. Step 3: Conduct flow resistance experiment of spiral single-rod single-channel experimental device: The first step is to adjust the electromagnetic pump current to obtain the specified experimental loop flow; The second step is to adjust the power of the heating section of the experimental circuit and stop heating after the temperature of the lower chamber (8) of the spiral single-rod single-channel experimental device reaches the specified temperature; The third step is to control the heating power of the experimental circuit heating wire to ensure that the temperature deviation between the upper chamber (2) and the lower chamber (8) of the spiral single-rod single-channel experimental device is less than 1.5°C; Step 4: Record the pressure difference Δp1 under the specified flow condition for no less than 60 seconds; Step 5: Stop the electromagnetic pump and record the pressure difference Δp2 under static conditions of the lead-bismuth medium; Step 6: Repeat steps 1 to 5 to obtain experimental data under different flow rates and inlet temperatures. Step 7: Calculate the Darcy friction coefficient using experimental data: Where f is the Darcy friction coefficient; ρ is the density, kg / m 3 ; l is the distance between the high-pressure end pressure-inducing assembly (9) and the low-pressure end pressure-inducing assembly (10), m; u is the inlet velocity, m / s; D h is the hydraulic diameter, m; Step 4: Conduct heat transfer experiments on the spiral single-rod single-channel experimental device: Step 1: Adjust the electromagnetic pump current to obtain the specified experimental loop flow; Step 2: Adjust the power of the heating section of the experimental circuit and stop heating after the temperature of the lower chamber (8) of the spiral single-rod single-channel experimental device reaches a specified value; Step 3: Control the heating power of the heating wire in the experimental circuit to ensure that the temperature deviation between the upper chamber (2) and the lower chamber (8) of the spiral single-rod single-channel experimental device is less than 1.5°C; Step 4: Adjust the cylindrical heating rod (1-1) in the spiral single-rod single-channel experimental device to the specified heating power P; Step 5: When the temperature of the upper chamber (2) and the lower chamber (8) does not change by more than 0.5°C within 60 seconds, record the temperature and flow rate experimental data under the specified flow rate working condition, and the recording time shall not be less than 60 seconds; Step 6: Repeat steps 1 to 5 to obtain experimental data under different flow rates, inlet temperatures, and heating powers. Step 7: Use the experimental data to calculate the average wall heat transfer coefficient and Nusselt number of the experimental device: Where A is the wall area of ​​the spiral heating rod, m 2 ; T w,ave is the average temperature of the experimental device wall; T f,ave is the average fluid temperature of the experimental device, °C; Nu is the Nusselt number; h is the average wall heat transfer coefficient of the experimental device, W / m 2 ;λ thermal conductivity, W / (m·K).

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