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

Abstract

The invention discloses a spiral single-rod single-channel experimental device and method based on additive manufacturing, and relates to the technical field of experimental devices. The spiral rod in the experimental device is processed by adopting an additive manufacturing technology, and a clamping piece structure on the surface of the spiral rod can realize wall surface temperature measurement. The heating rod and the additive manufactured spiral rod cooperate to be assembled into a spiral heating rod. Experiments under different working conditions can be carried out by controlling the heating power of the spiral heating rod, the flow of the experimental loop and the temperature of the lower chamber. By collecting and recording the pressure difference transmitter, the wall surface temperature and the fluid temperature data, the flow heat transfer characteristics of the spiral single-rod single-channel can be obtained, and support is provided for design and safety analysis of 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] Spiral nuclear fuel has the advantages of enhanced heat transfer and self-positioning support, which can improve the core power density of lead-bismuth reactors and eliminate the positioning grid. To support the design of spiral nuclear fuel, it is necessary to carry out spiral rod flow heat transfer experiments with lead-bismuth alloy as the medium. Lead-bismuth alloy has high electrical conductivity, and good electrical insulation is required between the spiral heating rod and the medium. The existing lead-bismuth alloy flow heat transfer experimental device uses easy-to-manufacture cylindrical heating rods, and there is no report on spiral heating rods. Spiral heating rods are difficult to manufacture using traditional methods. The existing spiral rod heating experimental pieces are processed by turning and rely on the introduction of DC power to achieve resistance heating. This manufacturing method is suitable for insulating fluids but not for lead-bismuth alloys. In addition, the wall temperature of the heating rod is a key measurement parameter for flow heat transfer experiments. The wall temperature of the existing experimental device is mainly measured by a deep buried thermocouple probe. This method is suitable for cylindrical heating rods, but not for irregularly shaped spiral heating rods. Therefore, for spiral heating rods for flow heat transfer experiments in lead-bismuth alloys, a new manufacturing and wall temperature measurement method needs to be designed. Summary of the invention

[0003] In order to overcome the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a spiral single-rod single-channel experimental device and experimental method based on additive manufacturing, and the thermocouple clamping device for measuring the wall temperature is processed by additive manufacturing technology, which can realize convenient and accurate measurement of the wall temperature, and the spiral rod can be assembled with the heating rod to realize the heating of the spiral rod. The experimental device of the present invention can be used to carry out the flow heat transfer characteristics experiment of the lead-bismuth alloy medium, and the flow heat transfer experimental data can be obtained, which provides data support for the design of spiral nuclear fuel and reactor safety analysis.

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

[0005] A spiral single-rod single-channel experimental device based on additive manufacturing, the experimental device comprises 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 at the upper part of the middle cylinder 5, the lower chamber 8 is located at 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-side pressure-leading assembly 10 are located on the side of the middle cylinder 5 and close to the upper chamber 2. The low-pressure-side pressure-leading assembly 10 is located on the upper part of the high-pressure-side pressure-leading assembly 9. The high-pressure-side pressure-leading assembly 9 and the low-pressure-side 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-side pressure-leading assembly 9 and the low-pressure-side 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 connected to the experimental circuit;

[0006] 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, 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 and connected, and the bottom end of the second spiral rod 1-3 and the top end of the third spiral rod 1-4 are welded and connected; 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, 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 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 midline 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 at the first spiral rod 1-2. Near the midline of the valley surface of the spiral rod 1-2, the thermocouple probe lobe clip 1-2-1 and the thermocouple probe lobe 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 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 lobe clip 1-2-1 and the thermocouple probe lobe 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 by using additive manufacturing technology;

[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 external fluid of the spiral heating rod; the external fluid of 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 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; 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 of 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 inwardly can fix the thermocouple probe; the thermocouple probe of 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 inwardly 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 inwardly can fix the thermocouple sleeve, and the thermocouple sleeve is wound on 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, and proceed to the next step after testing the air tightness of the experimental circuit;

[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 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;

[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 Darcy friction coefficient; ρ is 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 experiment of 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 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;

[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, and the recording time shall not be less than 60 seconds;

[0032] Step 6, repeating steps 1 to 5 to obtain experimental data under different flow rates, inlet temperatures and heating power conditions;

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

[0034]

[0035] Where A is the added wall area, 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).

[0036] Compared with the prior art, the present invention has the following advantages:

[0037] 1. The spiral heating rod of the experimental device of the present invention adopts additive manufacturing technology, which can realize the manufacturing of complex structures, including wall temperature measurement structures. The existing spiral heating rods are processed by turning and rely on the input of DC power supply to achieve resistance heating. This manufacturing method is suitable for insulating fluids but not for lead-bismuth alloys. The spiral heating rod of the present invention adopts additive manufacturing technology, and the central inner hole can cooperate with the cylindrical heating rod to meet the requirements of convection heat transfer experiments.

[0038] The existing heating rod wall temperature measurement technology mainly adopts the measurement method of deeply buried thermocouple probe, which is suitable for cylindrical heating rods but not for spiral heating rods. The present invention manufactures the wall temperature measurement structure based on additive manufacturing technology, which can achieve accurate measurement and reduce the interference degree of thermocouple sleeve.

[0039] 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.

[0040] 3. The flow resistance experimental method of the present invention can eliminate the influence of the gravity pressure difference at different temperatures; the heat transfer experimental method of the present invention can eliminate the influence of heat loss of the experimental device and obtain more accurate experimental results. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the front view structure of the single-rod single-channel experimental device of the present invention.

[0042] Figure 2 It is a schematic diagram of the top view structure of the single-rod single-channel experimental device of the present invention.

[0043] Figure 3 It is a schematic diagram of the spiral heating rod structure of the single-rod single-channel experimental device of the present invention.

[0044] Figure 4 It is a schematic diagram of the spiral rod surface clamp structure of the single-rod single-channel experimental device of the present invention.

[0045] Figure 5 This is a distribution diagram of measuring points in the first temperature measuring section AA of the single-rod single-channel experimental device of the present invention.

[0046] Figure 6a and Figure 6b They are respectively 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

[0047] The present invention provides a spiral single-rod single-channel experimental device and an experimental method based on additive manufacturing, and the present invention is now further described in detail in conjunction with the accompanying drawings.

[0048] like Figure 1 and Figure 2As shown, the present invention is a spiral single-rod single-channel experimental device based on additive manufacturing, 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 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 at the upper part of the middle cylinder 5, the lower chamber 8 is located at 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, and 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 connected to the experimental circuit.

[0049] 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 fixedly connected to the upper chamber 2 by a ferrule.

[0050] 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 manufactured 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 midline 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 at the first spiral rod 1-2. Near the midline of the valley surface of the spiral rod 1-2, the thermocouple probe lobe clip 1-2-1 and the thermocouple probe 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 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 lobe clip 1-2-1 and the thermocouple probe 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.

[0051] 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 external fluid of the spiral heating rod; the external fluid of the spiral heating rod is liquid lead-bismuth fluid.

[0052] 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 to improve the measurement accuracy.

[0053] As a preferred embodiment of the present invention, Figure 5 As shown, 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, and 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. This design can obtain the fluid temperature and wall temperature at typical positions of the spiral single-rod single-channel experimental device, so that the experimental conclusion has a wider applicability. 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.

[0054] As a preferred embodiment of the present invention, the thermocouple probe of 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 inwardly can fix the thermocouple probe; the thermocouple probe of 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 inwardly 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 inwardly can fix the thermocouple sleeve, and the thermocouple sleeve is wound on the surface of the spiral rod and led 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 sleeve on the flow field, thereby improving the measurement accuracy. In addition, by fixing the thermocouple probe leaf clip 1-2-1, the thermocouple sleeve clip 1-2-2 and the thermocouple probe leaf valley clip 1-2-3 together, the thermocouple is fixed more firmly, reducing the risk of the thermocouple being washed away by the fluid.

[0055] 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 material, which has low processing cost. In addition, the additive manufacturing technology using this material is relatively mature and has higher manufacturing precision.

[0056] The experimental method of the spiral single-rod single-channel experimental device based on additive manufacturing is achieved by the following steps:

[0057] 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;

[0058] 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 air tightness of the experimental circuit;

[0059] Step 3: Conduct flow resistance experiment of spiral single-rod single-channel experimental device:

[0060] The first step is to adjust the electromagnetic pump current to obtain the specified experimental loop flow;

[0061] 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;

[0062] The third step is to 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;

[0063] Step 4: Record the pressure difference Δp1 under the specified flow condition for no less than 60 seconds;

[0064] Step 5: Stop the electromagnetic pump and record the pressure difference Δp2 under static conditions of the lead-bismuth medium;

[0065] Step 6, repeat steps 1 to 5 to obtain experimental data under different flow rates and inlet temperatures;

[0066] Step 7: Calculate the Darcy friction coefficient using experimental data:

[0067]

[0068] Where f is Darcy friction coefficient; ρ is 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;

[0069] Step 4: Conduct heat transfer experiment of spiral single-rod single-channel experimental device:

[0070] Step 1: Adjust the electromagnetic pump current to obtain the specified experimental loop flow;

[0071] 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;

[0072] 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;

[0073] Step 4: Adjust the cylindrical heating rod 1-1 in the spiral single-rod single-channel experimental device to the specified heating power P;

[0074] 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, and the recording time shall not be less than 60 seconds;

[0075] Step 6, repeating steps 1 to 5 to obtain experimental data under different flow rates, inlet temperatures and heating power conditions;

[0076] Step 7: Use the experimental data to calculate the average wall heat transfer coefficient and Nusselt number of the experimental device:

[0077]

[0078] Where A is the added wall area, m 2 ; T w,ave is the average temperature of the experimental device wall; Tw,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).

[0079] like Figure 6a and Figure 6b As shown in the figure, the wall of the spiral heating rod has the same temperature value in the leaf valley area and the same temperature value in the leaf lobe area. Therefore, the thermocouple probe only needs to have one thermocouple to measure the wall temperature of the leaf lobe and the leaf valley in the same height section. According to the temperature distribution of the fluid outside the spiral heating rod, the fluid temperature in the leaf valley and leaf lobe area is closer to the wall temperature. Therefore, the thermocouple probe 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 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 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 via the upper flange (4), and the lower chamber (8) and the middle cylinder (5) are connected via 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); the upper chamber temperature measuring assembly (3) is vertically welded to the outer side of the upper chamber (2); the lower chamber temperature measuring assembly (7) is vertically welded to the outer side 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 comprises 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 inner side of the thermocouple probe lobe clip (1-2-1). 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 cross section at the same height 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 cross section at the same height 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) by 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 external fluid of the spiral heating rod; the external fluid of 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 of the first wall temperature measuring point (A-1) is placed in a thermocouple probe groove (1-2-2) on the inner side of the 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 of the second wall temperature measuring point (A-2) is placed on the inner side of the 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 the 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 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 spiral single-rod single-channel experimental device based on additive manufacturing 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 air tightness 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 a specified temperature; The third step is to 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: 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 Darcy friction coefficient; ρ is 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; Step 4: Conduct heat transfer experiment of spiral single-rod single-channel experimental device: Step 1: Adjust the electromagnetic pump current to obtain the specified experimental loop flow; Step 2: adjusting the power of the heating section of the experimental circuit, and stopping 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 a 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 condition, and the recording time shall not be less than 60 seconds; Step 6, repeating steps 1 to 5 to obtain experimental data under different flow rates, inlet temperatures and heating power conditions; 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 added wall area, 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).

Images