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

Abstract

The application discloses a spiral rod bundle multi-channel experimental device and an experimental method based on additive manufacturing, 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 clamping piece structure on the outer surface of the spiral rod can ensure that the thermocouple accurately measures the wall surface temperature.The sub-channel temperature measuring assembly is arranged near the inlet and outlet of the experimental device, the fluid temperature of the typical sub-channel is measured, the sub-channel analysis program is combined, the mixing coefficient of the spiral rod bundle multi-channel can be obtained, the experimental data of different experimental conditions can be obtained by adjusting the flow of the experimental loop and the fluid temperature in the lower chamber, and the Darcy friction resistance coefficient of the spiral rod bundle multi-channel can be obtained by recording the indication of the differential pressure transmitter.The experimental data of the application can provide support for the development of the design program of the spiral type rod bundle nuclear fuel.

Description

Technical Field

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

[0002] Helical nuclear fuel has been used in pressurized water reactors (PWRs) and space nuclear power plants. Its advantages include enhanced heat transfer, increased reactor power density, and the elimination of spacer grids. As a fourth-generation reactor, the lead-bismuth (PB) reactor (Bismuth) boasts low pressure, high temperature, and inherent safety. Applying helical fuel to PWRs can further enhance its advanced capabilities. The crossflow mixing intensity of a helical rod bundle is much greater than that of a cylindrical rod bundle. To calculate the crossflow mixing coefficient, previous studies have used water as the medium, injecting high-temperature water into low-temperature water and measuring the temperature of different subchannels at the outlet to calculate the crossflow mixing coefficient. However, no crossflow mixing experiments using a lead-bismuth alloy as the working fluid have been reported. Furthermore, the method of mixing a low-temperature lead-bismuth alloy with a high-temperature lead-bismuth alloy does not accurately simulate reactor heating boundary conditions, and the crossflow mixing coefficient obtained has certain limitations. Therefore, for crossflow mixing experiments in helical rod bundles, a design suitable for Pb-bismuth alloys and capable of realistically simulating heating conditions is needed. 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 rod bundle multi-channel experimental device and experimental method based on additive manufacturing, and carry out experiments using a 2×2 spiral rod bundle multi-channel experimental device; one of the heating rods is processed using additive manufacturing technology to form a clamping device for a thermocouple for measuring the wall temperature, and the spiral rod is heated by assembling it with a cylindrical heating rod to simulate the actual heating conditions of spiral nuclear fuel; the remaining three spiral rods are non-heating rods; the cross-flow mixing coefficient is indirectly calculated according to different sub-channel temperatures and the sub-channel analysis program, which can provide data support for spiral nuclear fuel design and sub-channel analysis.

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

[0005] The spiral rod bundle multi-channel experimental device based on additive manufacturing includes a rod bundle assembly 1, an upper chamber 2, an upper chamber temperature measurement assembly 3, an upper flange 4, an outlet sub-channel temperature measurement assembly 5, a low-pressure end pressure-inducing assembly 6, a high-pressure end pressure-inducing assembly 7, a middle cylinder 8, an inlet sub-channel temperature measurement assembly 9, a lower flange 10, a lower chamber 11, a lower chamber temperature measurement assembly 12 and a pressure differential transmitter 13; the middle cylinder 8 is located in the middle of the experimental device, the upper chamber 2 is located on the upper part of the middle cylinder 8, the lower chamber 11 is located on the lower part of the middle cylinder 8, the upper chamber 2 and the middle cylinder 8 are connected by the upper flange 4, and the lower chamber 11 and the middle cylinder are connected by the upper flange 4. 8 is connected through the lower flange 10; the low-pressure end pressure-leading assembly 6 and the high-pressure end pressure-leading assembly 7 are located on the side of the middle cylinder 8 and are vertically welded to the middle cylinder 8; the low-pressure end pressure-leading assembly 6 is located on the upper part of the high-pressure end pressure-leading assembly 7; the differential pressure transmitter 13 is respectively connected to the low-pressure end pressure-leading assembly 6 and the high-pressure end pressure-leading assembly 7 using flanges; the outlet sub-channel temperature measurement assembly 5 is located on the upper part of the inlet sub-channel temperature measurement assembly 9, and the outlet sub-channel temperature measurement assembly 5 and the inlet sub-channel temperature measurement assembly 9 are respectively close to the outlet and inlet positions of the experimental device; during the experiment, the upper chamber 2 and the lower chamber 11 are connected to the experimental circuit;

[0006] The rod bundle assembly 1 has a lead-bismuth alloy medium in the channels between the rod bundles. The rod bundle assembly 1 includes a first group of heating rods 1-1-1, a first group of spiral rods No. 1 1-1-2, a first group of spiral rods No. 2 1-1-3, a first group of spiral rods No. 3 1-1-4, a second group of round rods 1-2-1, a second group of spiral rods No. 1 1-2-2, a second group of spiral rods No. 2 1-2-3, a second group of spiral rods No. 3 1-2-4, a third group of round rods 1-3-1, a third group of spiral rods No. 1 1-3-2, a third group of spiral rods No. 2 1-3-3, a third group of spiral rods No. 3 1-3-4, a fourth group of round rods 1-4-1, a fourth group of spiral rods No. 1 1-4-2, a fourth group of spiral rods No. 2 1-4-3, a fourth group of spiral rods No. 3 1-4-4 and rods Grid 1-5-1; the first group of spiral rods 1-1-2, the second group of spiral rods 1-2-2, the third group of spiral rods 1-3-2 and the fourth group of spiral rods 1-4-2 are located at the upper part of the middle cylinder 8, the first group of spiral rods 1-1-3, the second group of spiral rods 1-2-3, the third group of spiral rods 1-3-3 and the fourth group of spiral rods 1-4-3 are located in the middle of the middle cylinder 8, the first group of spiral rods 1-1-4, the second group of spiral rods 1-2-4, the third group of spiral rods 1-3-4 and the fourth group of spiral rods 1-4-4 are located at the lower part of the middle cylinder 8; the bottom end of the first group of spiral rods 1-1-2 and the top end of the first group of spiral rods 1-1-3 are welded together, the first group of spiral rods 1-2-3 and the third group of spiral rods 1-3-3 are welded together, and the first group of spiral rods 1-2-4 and the third group of spiral rods 1-3-4 are welded together. The bottom end of spiral rod 1-1-3 is welded to the top end of spiral rod 1-1-4 of the first group three, the bottom end of spiral rod 1-2-2 of the second group one is welded to the top end of spiral rod 1-2-3 of the second group two, the bottom end of spiral rod 1-2-3 of the second group two is welded to the top end of spiral rod 1-2-4 of the second group three, the bottom end of spiral rod 1-3-2 of the third group one is welded to the top end of spiral rod 1-3-3 of the third group two, the bottom end of spiral rod 1-3-3 of the third group two is welded to the top end of spiral rod 1-3-4 of the third group three, the bottom end of spiral rod 1-4-2 of the fourth group one is welded to the top end of spiral rod 1-4-3 of the fourth group two, and the bottom end of spiral rod 1-4-3 of the fourth group two is welded to the top end of spiral rod 1-4-4 of the fourth group three Connection; the first group of heating rods 1-1-1 is located in the center inner holes of the first group of spiral rods 1-1-2, the first group of spiral rods 1-1-3, and the first group of spiral rods 1-1-4. The top ends of the first group of heating rods 1-1-1 pass through the upper chamber 2 and are fixedly connected with a ferrule; the second group of round rods 1-2-1, the third group of round rods 1-3-1, and the fourth group of round rods 1-4-1 are respectively located in the center inner holes of the top ends of the second group of spiral rods 1-2-2, the third group of spiral rods 1-3-2, and the fourth group of spiral rods 1-4-2; the first group of heating rods 1-1-1, the second group of round rods 1-2-1, the third group of round rods 1-3-1, and the fourth group of round rods 1-4-1 are arranged in a square and fixedly connected with a rod grid 1-5-1;The first set of three spiral rods are assembled with the first set of heating rods to achieve heating of the spiral rods, simulating the actual heating conditions of spiral nuclear fuel;

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

[0008] The experimental device also includes a first temperature measuring section AA, a second temperature measuring section BB, a third temperature measuring section CC, a fourth temperature measuring section DD and a fifth temperature measuring section EE for measuring the wall temperature of the spiral heating rod and the temperature of the sub-channel fluid. The outlet sub-channel temperature measurement component 5 is located on the fifth temperature measuring section EE, and the inlet sub-channel temperature measurement component 9 is located on the first temperature measuring section AA.

[0009] The first group of spiral rods No. 1 1-1-2, the first group of spiral rods No. 2 1-1-3, the first group of spiral rods No. 3 1-1-4, the second group of spiral rods No. 1 1-2-2, the second group of spiral rods No. 2 1-2-3, the second group of spiral rods No. 3 1-2-4, the third group of spiral rods No. 1 1-3-2, the third group of spiral rods No. 2 1-3-3, the third group of spiral rods No. 3 1-3-4, the fourth group of spiral rods No. 1 1-4-2, the fourth group of spiral rods No. 2 1-4-3 and the fourth group of spiral rods No. 3 1-4-4 are all Made of additively manufactured 316L stainless steel; the first group of spiral rods 1-1-2 are axially parallel to the second group of spiral rods 1-2-2 and the third group of spiral rods 1-3-2, and the minimum gap on the outer surface of the spiral is zero; the fourth group of spiral rods 1-4-2 are axially parallel to the second group of spiral rods 1-2-2 and the third group of spiral rods 1-3-2, and the minimum gap on the outer surface of the spiral is zero; the positional relationship between the No. 2 and No. 3 spiral rods in the four groups is the same as the positional relationship between the No. 1 spiral rod in the four groups.

[0010] The measuring points of the first temperature measuring section AA include a first fluid temperature measuring point A-1, a second fluid temperature measuring point A-2, and a third fluid temperature measuring point A-3; the first fluid temperature measuring point A-1 is located in the corner channel area close to the second group of third spiral rods 1-2-4, the second fluid temperature measuring point A-2 is located in the side channel area formed by the third group of third spiral rods 1-3-4 and the fourth group of third spiral rods 1-4-4, and the second fluid temperature measuring point A-3 is located in the center channel area formed by the first group of third spiral rods 1-1-4, the second group of third spiral rods 1-2-4, the third group of third spiral rods 1-3-4, and the fourth group of third spiral rods 1-4-4;

[0011] The measuring points of the second temperature measuring section BB include a first wall temperature measuring point B-1 and a second wall temperature measuring point B-2; the first wall temperature measuring point B-1 is located at the center line of the lobe of the first group of second spiral rods 1-1-3, and the second wall temperature measuring point B-2 is located at the center line of the lobe valley of the first group of second spiral rods 1-1-3;

[0012] The measuring points of the third temperature measurement section CC include a third wall temperature measuring point C-1 and a fourth wall temperature measuring point C-2; the third wall temperature measuring point C-1 is located at the center line of the blade valley of the first group of spiral rods 1-1-2, and the fourth wall temperature measuring point C-2 is located at the center line of the blade of the first group of spiral rods 1-1-2;

[0013] The measuring points of the fourth temperature measuring section DD include a fifth wall temperature measuring point D-1 and a sixth wall temperature measuring point D-2; the fifth wall temperature measuring point D-1 is located at the center line of the blade valley of the first group of spiral rods 1-1-2, and the sixth wall temperature measuring point D-2 is located at the center line of the blade of the first group of spiral rods 1-1-2;

[0014] The measuring points of the fifth temperature measuring section EE include the fourth fluid temperature measuring point E-1, the fifth fluid temperature measuring point E-2, the sixth fluid temperature measuring point E-3, the seventh fluid temperature measuring point E-4, the eighth fluid temperature measuring point E-5 and the ninth fluid temperature measuring point E-6; the fourth fluid temperature measuring point E-1 is located in the side channel area formed by the first group of No. 1 spiral rods 1-1-2 and the second group of No. 1 spiral rods 1-2-2, the fifth fluid temperature measuring point E-2 is close to the corner channel area of ​​the first group of No. 1 spiral rods 1-1-2, and the sixth fluid temperature measuring point E-3 is located in the first group of No. 1 spiral rods 1-1-2. The central channel area is formed by the spiral rods 1-1-2, the second group of spiral rods No. 1 1-2-2, the third group of spiral rods No. 1 1-3-2 and the fourth group of spiral rods No. 1 1-4-2. The seventh fluid temperature measuring point E-4 is located in the side channel area formed by the first group of spiral rods No. 1 1-1-2 and the third group of spiral rods No. 1 1-3-2. The eighth fluid temperature measuring point E-5 is located in the side channel area formed by the third group of spiral rods No. 1 1-3-2 and the fourth group of spiral rods No. 1 1-4-2. The ninth fluid temperature measuring point E-6 is close to the corner channel area of ​​the third group of spiral rods No. 1 1-3-2.

[0015] The experimental method of the additively manufactured spiral rod bundle multi-channel experimental device is achieved by the following steps:

[0016] Step 1: Connect the upper chamber 2 and the lower chamber 11 of the experimental device to the pipe of the experimental circuit, and conduct the experiment after testing the air tightness of the experimental circuit.

[0017] Step 2: Conduct resistance test of the helical rod bundle multi-channel experimental device:

[0018] Step 1: Adjust the electromagnetic pump current to obtain the specified experimental loop flow;

[0019] Step 2: Adjust the power of the heating section of the experimental circuit and stop heating after the temperature of the lower chamber 11 of the helical rod bundle multi-channel experimental device reaches the specified temperature;

[0020] 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 11 of the spiral rod bundle multi-channel experimental device is less than 1.5°C;

[0021] Step 4: Record the pressure difference Δp1 under the specified flow condition for no less than 60 seconds;

[0022] Step 5: Stop the electromagnetic pump and record the pressure difference Δp2 under static conditions of the lead-bismuth alloy medium.

[0023] Step 6: Repeat steps 1 to 5 to obtain experimental data under different flow rates and inlet temperatures.

[0024] Step 7: Calculate the Darcy friction coefficient using the following formula:

[0025]

[0026] Where f is the Darcy friction coefficient; ρ is the density, kg / m 3 ; l the distance between the low-pressure end pressure-leading assembly 6 and the high-pressure end pressure-leading assembly 7, m; u is the inlet velocity, m / s; D h is the hydraulic diameter, m; Δp1 and Δp2 are the pressure differences under operating and static conditions, respectively;

[0027] Step 3: Conduct cross-flow mixing experiments in a multi-channel experimental device with spiral rod bundles:

[0028] Step 1: Adjust the electromagnetic pump current to obtain the specified experimental loop flow;

[0029] Step 2: Adjust the power of the heating section of the experimental circuit and stop heating after the temperature of the lower chamber 11 of the helical rod bundle multi-channel experimental device reaches the specified temperature;

[0030] 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 11 of the spiral rod bundle multi-channel experimental device is less than 1.5°C;

[0031] Step 4: Adjust the cylindrical heating rod 1-1 in the helical rod bundle multi-channel experimental device to the specified heating power;

[0032] Step 5: When the sub-channel temperature 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;

[0033] Step 6: Repeat steps 1 to 5 to obtain experimental data under different flow rates, sub-channel temperatures, and heating power conditions;

[0034] Step 7: Process the experimental data, assuming multiple cross-flow mixing coefficient values ​​β k , substituted into the sub-channel analysis program, and the calculated values ​​of the outlet temperatures of different sub-channels T are obtained. pi ;

[0035] Step 8: Use the following formula to calculate the experimental measured value T of the outlet temperature of different sub-channels under each experimental condition ei The calculated values ​​of the subchannel outlet temperature T obtained by the subchannel analysis program are different from those of the subchannel outlet temperature T pi The sum of squared deviations R k (β k );

[0036]

[0037] Step 9: Draw R k (β k )-β curve, when R k (β k ) takes the minimum value, the corresponding β value is the cross-flow mixing coefficient value of the helical rod bundle multi-channel.

[0038] Compared with the prior art, the present invention has the following advantages:

[0039] 1. The spiral rod in the experimental device of this invention utilizes additive manufacturing technology, enabling the fabrication of complex structures. The use of thermocouple clips allows for accurate wall temperature measurement. 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 compatible with cylindrical heating rods, allowing it to approximately simulate the heating conditions of spiral nuclear fuel.

[0040] 2. The experimental method of the present invention can calculate the cross-flow mixing coefficient by measuring the temperatures of different sub-channels at the inlet and outlet and combining it with a sub-channel analysis program. This method is simple and feasible and can save experimental costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a schematic diagram of the main structural view of the rod bundle multi-channel experimental device of the present invention.

[0042] Figure 2 This is a schematic structural diagram of a top view of the rod bundle multi-channel experimental device of the present invention along the FF direction.

[0043] Figure 3a and Figure 3b This is a schematic diagram of the rod bundle assembly structure of the rod bundle multi-channel experimental device of the present invention.

[0044] Figure 4 This is a schematic diagram of the surface structure of the first group of first spiral rods in the rod bundle multi-channel experimental device of the present invention.

[0045] Figure 5 This is a schematic diagram of the first temperature measurement section AA of the rod bundle multi-channel experimental device of the present invention.

[0046] Figure 6 Schematic diagram of the second temperature measurement section BB of the rod bundle multi-channel experimental device of the present invention.

[0047] Figure 7 Schematic diagram of the third temperature measurement section CC of the rod bundle multi-channel experimental device of the present invention.

[0048] Figure 8 This is a schematic diagram of the fourth temperature measurement section DD of the rod bundle multi-channel experimental device of the present invention.

[0049] Figure 9 This is a schematic diagram of the fifth temperature measurement section EE of the rod bundle multi-channel experimental device of the present invention.

[0050] Figure 10 This is a fluid temperature distribution diagram of the fifth temperature measurement section of the rod bundle multi-channel experimental device of the present invention based on numerical calculation results. DETAILED DESCRIPTION

[0051] The present invention provides a spiral rod bundle multi-channel experimental device and experimental method based on additive manufacturing, which will now be further described in detail with reference to the accompanying drawings.

[0052] like Figure 1 and Figure 2As shown, the experimental device includes a rod bundle assembly 1, an upper chamber 2, an upper chamber temperature measuring assembly 3, an upper flange 4, an outlet sub-channel temperature measuring assembly 5, a low-pressure end pressure-leading assembly 6, a high-pressure end pressure-leading assembly 7, a middle cylinder 8, an inlet sub-channel temperature measuring assembly 9, a lower flange 10, a lower chamber 11, a lower chamber temperature measuring assembly 12 and a pressure differential transmitter 13; the middle cylinder 8 is located in the middle of the experimental device, the upper chamber 2 is located on the upper part of the middle cylinder 8, the lower chamber 11 is located on the lower part of the middle cylinder 8, the upper chamber 2 and the middle cylinder 8 are connected by the upper flange 4, and the lower chamber 11 and the middle cylinder 8 are connected by the lower flange 10; the low-pressure end pressure-leading assembly 6 and the high-pressure end pressure-leading assembly 7 The pressure-side pressure-guiding assembly 7 is located on the side of the middle cylinder 8 and is vertically welded to the middle cylinder 8. The low-pressure-side pressure-guiding assembly 6 is located above the high-pressure-side pressure-guiding assembly 7. The differential pressure transmitter 13 is flanged to connect the low-pressure-side pressure-guiding assembly 6 and the high-pressure-side pressure-guiding assembly 7. The outlet sub-channel temperature measurement assembly 5 is located above the inlet sub-channel temperature measurement assembly 9. The outlet sub-channel temperature measurement assembly 5 and the inlet sub-channel temperature measurement assembly 9 are respectively close to the outlet and inlet positions of the experimental device. This design can measure the temperature distribution of the fluid in different sub-channels before and after heating by the spiral heating rod. The temperature gradient near the outlet position is larger, making the measurement more accurate. During the experiment, the upper chamber 2 and the lower chamber 11 are both connected to the experimental circuit.

[0053] like Figure 3a and Figure 3bAs shown, the rod bundle assembly 1 has a lead-bismuth alloy medium in the channels between the rod bundles. The rod bundle assembly 1 includes a first group of heating rods 1-1-1, a first group of spiral rods No. 1 1-1-2, a first group of spiral rods No. 2 1-1-3, a first group of spiral rods No. 3 1-1-4, a second group of round rods 1-2-1, a second group of spiral rods No. 1 1-2-2, a second group of spiral rods No. 2 1-2-3, a second group of spiral rods No. 3 1-2-4, a third group of round rods 1-3-1, a third group of spiral rods No. 1 1-3-2, a third group of spiral rods No. 2 1-3-3, a third group of spiral rods No. 3 1-3-4, a fourth group of round rods 1-4-1, a fourth group of spiral rods No. 1 1-4-2, a fourth group of spiral rods No. 2 1-4-3, a fourth group of spiral rods No. 3 1-4-4, and a rod grid 1 -5-1; the first group of spiral rods 1-1-2, the second group of spiral rods 1-2-2, the third group of spiral rods 1-3-2 and the fourth group of spiral rods 1-4-2 are located at the upper part of the middle cylinder 8, the first group of spiral rods 1-1-3, the second group of spiral rods 1-2-3, the third group of spiral rods 1-3-3 and the fourth group of spiral rods 1-4-3 are located in the middle of the middle cylinder 8, the first group of spiral rods 1-1-4, the second group of spiral rods 1-2-4, the third group of spiral rods 1-3-4 and the fourth group of spiral rods 1-4-4 are located at the lower part of the middle cylinder 8; the bottom end of the first group of spiral rods 1-1-2 and the top end of the first group of spiral rods 1-1-3 are welded together, and the first group of spiral rods 1-1- The bottom end of the third group of spiral rods is welded to the top of the first group of spiral rods 1-1-4, the bottom end of the second group of spiral rods 1-2-2 is welded to the top of the second group of spiral rods 1-2-3, the bottom end of the second group of spiral rods 1-2-3 is welded to the top of the second group of spiral rods 1-2-4, the bottom end of the third group of spiral rods 1-3-2 is welded to the top of the third group of spiral rods 1-3-3, the bottom end of the third group of spiral rods 1-3-3 is welded to the top of the third group of spiral rods 1-3-4, the bottom end of the fourth group of spiral rods 1-4-2 is welded to the top of the fourth group of spiral rods 1-4-3, the bottom end of the fourth group of spiral rods 1-4-3 is welded to the top of the fourth group of spiral rods 1-4-4; the first group of heating rods 1 -1-1 is located in the center inner holes of the first group of spiral rods 1-1-2, the first group of spiral rods 1-1-3 and the first group of spiral rods 1-1-4, and forms a clearance fit. The top end of the first group of heating rods 1-1-1 passes through the upper chamber 2 and is fixedly connected with a ferrule; the second group of round rods 1-2-1, the third group of round rods 1-3-1 and the fourth group of round rods 1-4-1 are respectively located in the center inner holes of the top ends of the second group of spiral rods 1-2-2, the third group of spiral rods 1-3-2 and the fourth group of spiral rods 1-4-2, forming a clearance fit; the first group of heating rods 1-1-1, the second group of round rods 1-2-1, the third group of round rods 1-3-1 and the fourth group of round rods 1-4-1 are arranged in a square and fixedly connected with a rod grid 1-5-1;The first set of three spiral rods are assembled with the first set of heating rods to heat the spiral rods, simulating the actual heating conditions of spiral nuclear fuel.

[0054] like Figure 4 As shown, the surface of the first group of spiral rods 1-1-2 is processed with a thermocouple clamping device using additive manufacturing technology, and the thermocouple clamping device includes a thermocouple probe lobe clip J-1, a thermocouple probe groove J-2, a thermocouple probe lobe valley clip J-3 and a thermocouple sleeve clip J-4; the thermocouple probe lobe clip J-1 is located near the center line of the lobe surface of the first group of spiral rods 1-1-2, the thermocouple probe groove J-2 is located on the inner side of the thermocouple probe lobe clip J-1; the thermocouple probe lobe valley clip J-3 is located Near the center line of the leaf valley surface of the first group of spiral rod No. 1-1-2, the thermocouple probe lobe clip J-1 and the thermocouple probe lobe valley clip J-3 are located on the same height cross-section; the thermocouple sleeve clip J-4 is located near the center line of the leaf valley surface of the spiral rod, and the thermocouple sleeve clip J-4 is located above the thermocouple probe lobe clip J-1 and the thermocouple probe lobe valley clip J-3; the surface of the first group No. 2 spiral rod 1-1-3 is processed with additive manufacturing technology to have the same thermocouple clamping device as the first group No. 1 spiral rod 1-1-2.

[0055] like Figure 5 、 6 As shown in Figures 7, 8 and 9, the experimental device also includes a first temperature measurement section AA, a second temperature measurement section BB, a third temperature measurement section CC, a fourth temperature measurement section DD and a fifth temperature measurement section EE. The outlet sub-channel temperature measurement component 5 is located on the fifth temperature measurement section EE, and the inlet sub-channel temperature measurement component 9 is located on the first temperature measurement section AA.

[0056] As a preferred embodiment of the present invention, the first group of spiral rods No. 1 1-1-2, the first group of spiral rods No. 2 1-1-3, the first group of spiral rods No. 3 1-1-4, the second group of spiral rods No. 1 1-2-2, the second group of spiral rods No. 2 1-2-3, the second group of spiral rods No. 3 1-2-4, the third group of spiral rods No. 1 1-3-2, the third group of spiral rods No. 2 1-3-3, the third group of spiral rods No. 3 1-3-4, the fourth group of spiral rods No. 1 1-4-2, the fourth group of spiral rods No. 2 1-4-3 and the fourth group of spiral rods No. 3 1-4-4 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; the first group of No. 1 spiral rods 1-1-2 are axially parallel to the second group of No. 1 spiral rods 1-2-2 and the third group of No. 1 spiral rods 1-3-2, and the minimum gap on the outer surface of the spiral is zero; the fourth group of No. 1 spiral rods 1-4-2 are axially parallel to the second group of No. 1 spiral rods 1-2-2 and the third group of No. 1 spiral rods 1-3-2, and the minimum gap on the outer surface of the spiral is zero; the positional relationship of the No. 2 and No. 3 spiral rods in the four groups is the same as the positional relationship of the No. 1 spiral rod in the four groups.

[0057] 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 fluid temperature measuring point A-1, the second fluid temperature measuring point A-2 and the third fluid temperature measuring point A-3; the first fluid temperature measuring point A-1 is located in the corner channel area close to the second group of No. 3 spiral rods 1-2-4, the second fluid temperature measuring point A-2 is located in the side channel area formed by the third group of No. 3 spiral rods 1-3-4 and the fourth group of No. 3 spiral rods 1-4-4, and the second fluid temperature measuring point A-3 is located in the central channel area formed by the first group of No. 3 spiral rods 1-1-4, the second group of No. 3 spiral rods 1-2-4, the third group of No. 3 spiral rods 1-3-4 and the fourth group of No. 3 spiral rods 1-4-4; this design can measure the fluid temperatures of three types of sub-channels to ensure experimental accuracy without measuring the fluid temperatures of all sub-channels.

[0058] As a preferred embodiment of the present invention, Figure 6 As shown, the measuring points of the second temperature measuring section BB include the first wall temperature measuring point B-1 and the second wall temperature measuring point B-2; the first wall temperature measuring point B-1 is located at the center line of the lobe of the first group of second spiral rods 1-1-3, and the second wall temperature measuring point B-2 is located at the center line of the lobe valley of the first group of second spiral rods 1-1-3; this design can obtain the wall temperature of the spiral heating rod at a typical position of the second temperature measuring section BB, making the experimental conclusion more widely applicable.

[0059] As a preferred embodiment of the present invention, the diameter of the wall temperature measuring thermocouple is 0.5 mm, and the length of the thermocouple sleeve is 1.5 m. This type of thermocouple can reduce the impact on the flow field and improve measurement accuracy.

[0060] As a preferred embodiment of the present invention, Figure 7 As shown, the measuring points of the third temperature measuring section CC include the third wall temperature measuring point C-1 and the fourth wall temperature measuring point C-2; the third wall temperature measuring point C-1 is located at the center line of the blade valley of the first group of spiral rods 1-1-2, and the fourth wall temperature measuring point C-2 is located at the center line of the blade of the first group of spiral rods 1-1-2; this design can obtain the wall temperature of the spiral heating rod at a typical position of the third temperature measuring section CC, so that the experimental conclusions have more extensive applicability.

[0061] As a preferred embodiment of the present invention, Figure 8 As shown, the measuring points of the fourth temperature measuring section DD include the fifth wall temperature measuring point D-1 and the sixth wall temperature measuring point D-2; the fifth wall temperature measuring point D-1 is located at the center line of the blade valley of the first group of spiral rods 1-1-2, and the sixth wall temperature measuring point D-2 is located at the center line of the blade of the first group of spiral rods 1-1-2; this design can obtain the wall temperature of the spiral heating rod at a typical position of the fourth temperature measuring section DD, so that the experimental conclusions have more extensive applicability.

[0062] As a preferred embodiment of the present invention, Figure 9 As shown, the measuring points of the fifth temperature measuring section EE include the fourth fluid temperature measuring point E-1, the fifth fluid temperature measuring point E-2, the sixth fluid temperature measuring point E-3, the seventh fluid temperature measuring point E-4, the eighth fluid temperature measuring point E-5 and the ninth fluid temperature measuring point E-6; the fourth fluid temperature measuring point E-1 is located in the side channel area formed by the first group of No. 1 spiral rods 1-1-2 and the second group of No. 1 spiral rods 1-2-2, the fifth fluid temperature measuring point E-2 is close to the corner channel area of ​​the first group of No. 1 spiral rods 1-1-2, and the sixth fluid temperature measuring point E-3 is located in the first group of No. 1 spiral rods 1-1-2. The central channel is formed by spiral rods 1-1-2, the second group of spiral rods 1-2-2, the third group of spiral rods 1-3-2, and the fourth group of spiral rods 1-4-2. The seventh fluid temperature measurement point, E-4, is located in the side channel formed by spiral rods 1-1-2 and 1-3-2. The eighth fluid temperature measurement point, E-5, is located in the side channel formed by spiral rods 1-3-2 and 1-4-2. The ninth fluid temperature measurement point, E-6, is located near the corner channel of spiral rods 1-3-2. This design reduces the number of thermocouple fluid temperature measurement points, reduces thermocouple interference with the flow field, and improves measurement accuracy while ensuring experimental accuracy.

[0063] The experimental method of the additively manufactured helical rod bundle multi-channel experimental device is achieved through the following steps:

[0064] Step 1: Connect the upper chamber 2 and the lower chamber 11 of the experimental device to the pipe of the experimental circuit, and conduct the experiment after testing the air tightness of the experimental circuit.

[0065] Step 2: Conduct resistance test of the helical rod bundle multi-channel experimental device:

[0066] Step 1: Adjust the electromagnetic pump current to obtain the specified experimental loop flow;

[0067] Step 2: Adjust the power of the heating section of the experimental circuit and stop heating after the temperature of the lower chamber 11 of the helical rod bundle multi-channel experimental device reaches the specified temperature;

[0068] 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 11 of the spiral rod bundle multi-channel experimental device is less than 1.5°C;

[0069] Step 4: Record the pressure difference Δp1 under the specified flow condition for no less than 60 seconds;

[0070] Step 5: Stop the electromagnetic pump and record the pressure difference Δp2 under static conditions of the lead-bismuth alloy medium.

[0071] Step 6: Repeat steps 1 to 5 to obtain experimental data under different flow rates and inlet temperatures.

[0072] Step 7: Calculate the Darcy friction coefficient using the following formula:

[0073]

[0074] Where f is the Darcy friction coefficient; ρ is the density, kg / m 3 ; l the distance between the low-pressure end pressure-leading assembly 6 and the high-pressure end pressure-leading assembly 7, m; u is the inlet velocity, m / s; D h is the hydraulic diameter, m; Δp1 and Δp2 are the pressure differences under operating and static conditions, respectively.

[0075] Step 3: Conduct cross-flow mixing experiments in a multi-channel experimental device with spiral rod bundles:

[0076] Step 1: Adjust the electromagnetic pump current to obtain the specified experimental loop flow;

[0077] Step 2: Adjust the power of the heating section of the experimental circuit and stop heating after the temperature of the lower chamber 11 of the helical rod bundle multi-channel experimental device reaches the specified temperature;

[0078] 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 11 of the spiral rod bundle multi-channel experimental device is less than 1.5°C;

[0079] Step 4: Adjust the cylindrical heating rod 1-1 in the helical rod bundle multi-channel experimental device to the specified heating power;

[0080] Step 5: When the sub-channel temperature 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;

[0081] Step 6: Repeat steps 1 to 5 to obtain experimental data under different flow rates, sub-channel temperatures, and heating power conditions;

[0082] Step 7: Process the experimental data, assuming multiple cross-flow mixing coefficient values ​​β k , substituted into the sub-channel analysis program, and the calculated values ​​of the outlet temperatures of different sub-channels T are obtained. pi ;

[0083] Step 8: Use the following formula to calculate the experimental measurement value of the outlet temperature of different sub-channels under each experimental condition (T ei ) and the calculated values ​​of different subchannel outlet temperatures (T pi ) of the sum of squared deviations R k (β k );

[0084]

[0085] Step 9: Draw R k (β k )-β curve, when R k (β k ) takes the minimum value, the corresponding β value is the cross-flow mixing coefficient value of the helical rod bundle multi-channel.

[0086] Mature numerical calculation tools are used to obtain the numerical simulation results of the spiral rod bundle multi-channel experimental device. The positions of the fluid temperature measurement points are determined according to the temperature distribution of different sub-channels of the spiral rod bundle, the number of thermocouple fluid temperature measurement points is simplified, and the measurement accuracy is improved.

[0087] like Figure 10 As shown in the figure, according to the fluid temperature distribution of the fifth temperature measurement section of the helical rod bundle multi-channel experimental device, it is known that it is not necessary to measure the temperature of all sub-channels. At this time, the fluid temperature measurement points are as follows: Figure 9 shown.

Claims

1. A multi-channel experimental device based on spiral rod bundles manufactured with additive manufacturing, characterized by: The experimental device comprises a rod bundle assembly (1), an upper chamber (2), an upper chamber temperature measurement assembly (3), an upper flange (4), an outlet sub-channel temperature measurement assembly (5), a low-pressure end pressure-inducing assembly (6), a high-pressure end pressure-inducing assembly (7), a middle cylinder (8), an inlet sub-channel temperature measurement assembly (9), a lower flange (10), a lower chamber (11), a lower chamber temperature measurement assembly (12) and a pressure differential transmitter (13); the middle cylinder (8) is located in the middle of the experimental device, the upper chamber (2) is located at the upper part of the middle cylinder (8), the lower chamber (11) is located at the lower part of the middle cylinder (8), the upper chamber (2) and the middle cylinder (8) are connected by the upper flange (4), and the lower chamber (11) and the middle cylinder (8) are connected by the upper flange (4). ) are connected via a lower flange (10); the low-pressure end pressure-leading assembly (6) and the high-pressure end pressure-leading assembly (7) are located on the side of the middle cylinder (8) and are vertically welded to the middle cylinder (8); the low-pressure end pressure-leading assembly (6) is located on the upper part of the high-pressure end pressure-leading assembly (7); the differential pressure transmitter (13) is respectively connected to the low-pressure end pressure-leading assembly (6) and the high-pressure end pressure-leading assembly (7) using flanges; the outlet sub-channel temperature measurement assembly (5) is located on the upper part of the inlet sub-channel temperature measurement assembly (9), and the outlet sub-channel temperature measurement assembly (5) and the inlet sub-channel temperature measurement assembly (9) are respectively close to the outlet and inlet positions of the experimental device; during the experiment, the upper chamber (2) and the lower chamber (11) are both connected to the experimental circuit; The rod bundle assembly (1) has a lead-bismuth alloy medium in the channels between the rod bundles. The rod bundle assembly (1) comprises a first group of heating rods (1-1-1), a first group of spiral rods No. 1 (1-1-2), a first group of spiral rods No. 2 (1-1-3), a first group of spiral rods No. 3 (1-1-4), a second group of round rods (1-2-1), a second group of spiral rods No. 1 (1-2-2), a second group of spiral rods No. 2 (1-2-3), a second group of spiral rods No. 3 (1-2-4), a third group of round rods (1-3-1), a third group of spiral rods No. 1 (1-3-2), a third group of spiral rods No. 2 (1-3-3), a third group of spiral rods No. 3 (1-3-4), a fourth group of round rods (1-4-1), a fourth group of The first spiral rod (1-4-2), the fourth group of the second spiral rod (1-4-3), the fourth group of the third spiral rod (1-4-4) and the rod grid (1-5-1); the first group of the first spiral rod (1-1-2), the second group of the first spiral rod (1-2-2), the third group of the first spiral rod (1-3-2) and the fourth group of the first spiral rod (1-4-2) are located at the upper part of the middle cylinder (8); the first group of the second spiral rod (1-1-3), the second group of the second spiral rod (1-2-3), the third group of the second spiral rod (1-3-3) and the fourth group of the second spiral rod (1-4-3) are located at the middle part of the middle cylinder (8); the first group of the third spiral rod (1-1-4), the second group of the third spiral rod (1-2 -4), the third group of No. 3 spiral rods (1-3-4) and the fourth group of No. 3 spiral rods (1-4-4) are located at the lower part of the middle cylinder (8); the bottom end of the first group of No. 1 spiral rods (1-1-2) and the top end of the first group of No. 2 spiral rods (1-1-3) are welded together, the bottom end of the first group of No. 2 spiral rods (1-1-3) and the top end of the first group of No. 3 spiral rods (1-1-4) are welded together, the bottom end of the second group of No. 1 spiral rods (1-2-2) and the top end of the second group of No. 2 spiral rods (1-2-3) are welded together, the bottom end of the second group of No. 2 spiral rods (1-2-3) and the top end of the second group of No. 3 spiral rods (1-2-4) are welded together, the bottom end of the third group of No. 1 spiral rods (1-3-2) and the top end of the third group of No. 2 spiral rods ( The top of the third group of spiral rods (1-3-3) is welded and connected, the bottom of the third group of spiral rods (1-3-3) is welded and connected to the top of the third group of spiral rods (1-3-4), the bottom of the fourth group of spiral rods (1-4-2) is welded and connected to the top of the fourth group of spiral rods (1-4-3), and the bottom of the fourth group of spiral rods (1-4-3) is welded and connected to the top of the fourth group of spiral rods (1-4-4); the first group of heating rods (1-1-1) is located in the central inner holes of the first group of spiral rods (1-1-2), the first group of spiral rods (1-1-3) and the first group of spiral rods (1-1-4), and the top of the first group of heating rods (1-1-1) passes through the upper chamber (2) and is fixedly connected with a ferrule;The second group of round rods (1-2-1), the third group of round rods (1-3-1), and the fourth group of round rods (1-4-1) are respectively located in the top center inner holes of the second group of spiral rods No. 1 (1-2-2), the third group of spiral rods No. 1 (1-3-2), and the fourth group of spiral rods No. 1 (1-4-2); the first group of heating rods (1-1-1), the second group of round rods (1-2-1), the third group of round rods (1-3-1), and the fourth group of round rods (1-4-1) are arranged in a square and fixedly connected by a rod grid (1-5-1); the first group of three spiral rods are assembled with the first group of heating rods to achieve heating of the spiral rods, simulating actual spiral nuclear fuel heating conditions; The surface of the first group of spiral rods (1-1-2) is processed with a thermocouple clamping device using additive manufacturing technology, and the thermocouple clamping device includes a thermocouple probe lobe clip (J-1), a thermocouple probe groove (J-2), a thermocouple probe lobe valley clip (J-3) and a thermocouple sleeve clip (J-4); the thermocouple probe lobe clip (J-1) is located near the center line of the lobe surface of the first group of spiral rods (1-1-2), the thermocouple probe groove (J-2) is located on the inner side of the thermocouple probe lobe clip (J-1); the thermocouple probe lobe valley clip (J-3) is located on the first group of spiral rods (1-1-2) Near the midline of the valley surface of the first spiral rod (1-1-2), the thermocouple probe lobe clip (J-1) and the thermocouple probe valley clip (J-3) are located on the same height cross section; the thermocouple sleeve clip (J-4) is located near the midline of the valley surface of the spiral rod, and the thermocouple sleeve clip (J-4) is located above the thermocouple probe lobe clip (J-1) and the thermocouple probe valley clip (J-3); the surface of the first group No. 2 spiral rod (1-1-3) is processed by additive manufacturing technology with a thermocouple clamping device identical to that of the first group No. 1 spiral rod (1-1-2); The experimental device also includes a first temperature measuring section (AA), a second temperature measuring section (BB), a third temperature measuring section (CC), a fourth temperature measuring section (DD) and a fifth temperature measuring section (EE) for measuring the wall temperature of the spiral heating rod and the temperature of the sub-channel fluid. The outlet sub-channel temperature measuring component (5) is located on the fifth temperature measuring section (EE), and the inlet sub-channel temperature measuring component (9) is located on the first temperature measuring section (AA).

2. The additive manufacturing-based helical rod bundle multi-channel experimental device according to claim 1, characterized in that: The first group of spiral rods No. 1 (1-1-2), the first group of spiral rods No. 2 (1-1-3), the first group of spiral rods No. 3 (1-1-4), the second group of spiral rods No. 1 (1-2-2), the second group of spiral rods No. 2 (1-2-3), the second group of spiral rods No. 3 (1-2-4), the third group of spiral rods No. 1 (1-3-2), the third group of spiral rods No. 2 (1-3-3), the third group of spiral rods No. 3 (1-3-4), the fourth group of spiral rods No. 1 (1-4-2), the fourth group of spiral rods No. 2 (1-4-3) and the fourth group of spiral rods No. 3 (1- 4-4) are all made of additively manufactured 316L stainless steel; the first group of spiral rods No. 1 (1-1-2) are axially parallel to the second group of spiral rods No. 1 (1-2-2) and the third group of spiral rods No. 1 (1-3-2), and the minimum gap on the outer surface of the spiral is zero; the fourth group of spiral rods No. 1 (1-4-2) are axially parallel to the second group of spiral rods No. 1 (1-2-2) and the third group of spiral rods No. 1 (1-3-2), and the minimum gap on the outer surface of the spiral is zero; the positional relationship of the No. 2 and No. 3 spiral rods in the four groups is the same as the positional relationship of the No. 1 spiral rod in the four groups.

3. The additive manufacturing-based helical rod bundle multi-channel experimental device according to claim 1, characterized in that: The measuring points of the first temperature measurement section (AA) include a first fluid temperature measuring point (A-1), a second fluid temperature measuring point (A-2), and a third fluid temperature measuring point (A-3); the first fluid temperature measuring point (A-1) is located in a corner channel region close to the second group of three spiral rods (1-2-4), the second fluid temperature measuring point (A-2) is located in a side channel region formed by the third group of three spiral rods (1-3-4) and the fourth group of three spiral rods (1-4-4), and the second fluid temperature measuring point (A-3) is located in a central channel region formed by the first group of three spiral rods (1-1-4), the second group of three spiral rods (1-2-4), the third group of three spiral rods (1-3-4), and the fourth group of three spiral rods (1-4-4); The measuring points of the second temperature measuring section (BB) include a first wall temperature measuring point (B-1) and a second wall temperature measuring point (B-2); the first wall temperature measuring point (B-1) is located at the center line of the lobe of the first group of second spiral rods (1-1-3), and the second wall temperature measuring point (B-2) is located at the center line of the lobe valley of the first group of second spiral rods (1-1-3); The measuring points of the third temperature measuring section (CC) include a third wall temperature measuring point (C-1) and a fourth wall temperature measuring point (C-2); the third wall temperature measuring point (C-1) is located at the center line of the blade valley of the first group of spiral rods (1-1-2), and the fourth wall temperature measuring point (C-2) is located at the center line of the blade of the first group of spiral rods (1-1-2); The measuring points of the fourth temperature measuring section (DD) include a fifth wall temperature measuring point (D-1) and a sixth wall temperature measuring point (D-2); the fifth wall temperature measuring point (D-1) is located at the center line of the blade valley of the first group of spiral rods (1-1-2), and the sixth wall temperature measuring point (D-2) is located at the center line of the blade of the first group of spiral rods (1-1-2); The measuring points of the fifth temperature measuring section (EE) include a fourth fluid temperature measuring point (E-1), a fifth fluid temperature measuring point (E-2), a sixth fluid temperature measuring point (E-3), a seventh fluid temperature measuring point (E-4), an eighth fluid temperature measuring point (E-5) and a ninth fluid temperature measuring point (E-6); the fourth fluid temperature measuring point (E-1) is located in the side channel area formed by the first group of spiral rods (1-1-2) and the second group of spiral rods (1-2-2); the fifth fluid temperature measuring point (E-2) is close to the corner channel area of ​​the first group of spiral rods (1-1-2); the sixth fluid temperature measuring point (E-3) is located in the first group of spiral rods (1-1-2) and the corner channel area of ​​the second group of spiral rods (1-2-2); The central channel area is formed by the spiral rod (1-1-2), the second group of spiral rod No. 1 (1-2-2), the third group of spiral rod No. 1 (1-3-2) and the fourth group of spiral rod No. 1 (1-4-2); the seventh fluid temperature measuring point (E-4) is located in the side channel area formed by the first group of spiral rod No. 1 (1-1-2) and the third group of spiral rod No. 1 (1-3-2); the eighth fluid temperature measuring point (E-5) is located in the side channel area formed by the third group of spiral rod No. 1 (1-3-2) and the fourth group of spiral rod No. 1 (1-4-2); and the ninth fluid temperature measuring point (E-6) is close to the corner channel area of ​​the third group of spiral rod No. 1 (1-3-2).

4. The experimental method of the additively manufactured spiral rod bundle multi-channel experimental device according to any one of claims 1 to 3, characterized in that: The method is achieved by the following steps: Step 1: Connect the upper chamber (2) and the lower chamber (11) of the experimental device to the pipe of the experimental circuit, and conduct the experiment after testing the airtightness of the experimental circuit. Step 2: Conduct resistance test of the helical rod bundle multi-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 (11) of the helical rod bundle multi-channel experimental device reaches a specified temperature; 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 (11) of the spiral rod bundle multi-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 alloy 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 the following formula: Where f is the Darcy friction coefficient; ρ is the density, kg / m 3 ; l is the distance between the low-pressure end pressure-inducing assembly (6) and the high-pressure end pressure-inducing assembly (7), m; u is the inlet velocity, m / s; D h is the hydraulic diameter, m; Δp1 and Δp2 are the pressure differences under operating and static conditions, respectively; Step 3: Conduct cross-flow mixing experiments in a multi-channel experimental device with spiral rod bundles: 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 (11) of the helical rod bundle multi-channel experimental device reaches a specified temperature; 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 (11) of the spiral rod bundle multi-channel experimental device is less than 1.5°C; Step 4: Adjust the cylindrical heating rod (1-1) in the helical rod bundle multi-channel experimental device to the specified heating power; Step 5: When the sub-channel temperature 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; Step 6: Repeat steps 1 to 5 to obtain experimental data under different flow rates, sub-channel temperatures, and heating power conditions; Step 7: Process the experimental data, assuming multiple cross-flow mixing coefficient values ​​β k , substituted into the sub-channel analysis program, and the calculated values ​​of the outlet temperatures of different sub-channels T are obtained. pi ; Step 8: Use the following formula to calculate the experimental measured value T of the outlet temperature of different sub-channels under each experimental condition ei The calculated values ​​of the subchannel outlet temperature T obtained by the subchannel analysis program are different from those of the subchannel outlet temperature T pi The sum of squared deviations R k (β k ); Step 9: Draw R k (β k )-β curve, when R k (β k ) takes the minimum value, the corresponding β value is the cross-flow mixing coefficient value of the helical rod bundle multi-channel.

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