In-pipe cable conductor friction coefficient testing device and testing method thereof

Abstract

The invention relates to an in-pipe cable conductor friction coefficient testing device and method, and belongs to the field of in-pipe cable conductor thermal hydraulic parameter testing, and the device comprises water, a heating water tank, a frequency conversion type centrifugal pump, a flow sensor, a flow regulator, a thermometer, a pressure sensor, a valve, a pipeline and a data acquisition system. The internal flow friction coefficient of the CICC conductor is measured by using water in a loop as a medium. A stable pressure head is provided through the variable-frequency centrifugal pump, the loop flow is accurately adjusted through the variable-frequency centrifugal pump and the flow adjuster, and the water temperature in the test loop can be adjusted through the heating water tank, so that the physical properties such as the viscosity of water are changed, and the effect of testing a larger Reynolds number range is achieved. According to the test method, the friction coefficient of the CICC conductor is calculated through the pressure difference of the inlet and the outlet of the CICC conductor and the flow in a loop. According to the invention, basic parameters can be provided for the thermal hydraulic research of liquid helium in the CICC conductor.

Description

Technical Field

[0001] The present invention belongs to the field of measuring the thermohydraulic parameters of in-tube cable conductors (CICC conductors), and measures the friction coefficient of CICC-type conductors. In particular, it relates to a device and a method for testing the friction coefficient of in-tube cable conductors. Background Art

[0002] Due to the excellent structural performance of CICC conductors, CICC conductors are generally used in the winding of large superconducting magnets. CICC conductors mainly consist of superconducting wires, central cooling tubes, and stainless steel armors. Since superconducting materials such as Nb 3 Sn and NbTi need to enter the superconducting state at liquid helium temperature, combined with the mechanical characteristics of CICC conductors, the cooling method during the operation of superconducting magnets is supercritical helium forced-flow cooling. Supercritical helium flows in the gaps between the superconducting strands and the flower packs of the conductor. Accurately calculating the resistance loss of supercritical helium in the conductor is of great significance for issues such as the selection of supercritical helium circulation pumps, the determination of supercritical helium inlet and outlet pressures, the cooling of CICC conductors, the design of cryogenic systems, the regulation and control of supercritical helium flow rates, etc.

[0003] Currently, nitrogen is generally used to measure the friction coefficient of CICC conductors. When using nitrogen for testing, a cylinder group is used as the nitrogen source. During this measurement method, the pressure is often not stable enough. The physical properties of nitrogen are sensitive to changes in pressure and temperature, resulting in large test errors. Moreover, the measurement range of nitrogen is small, and it is difficult to reach the Reynolds number range of supercritical helium flowing inside the CICC conductor under its actual operating conditions. The present invention uses water in the loop as the medium for testing. A stable head can be provided by a centrifugal pump, the loop flow rate can be precisely adjusted through the pump and branches, and the physical properties such as the viscosity of water can be changed by adjusting the water temperature in the test loop, thereby achieving the effect of testing a larger Reynolds number range. The test results of the friction coefficient inside the CICC conductor can intuitively reflect the flow resistance of the flowing medium inside the conductor. The friction coefficient of the CICC conductor can be obtained through experimental measurement, providing a reference for the design and optimization of the CICC conductor. Summary of the Invention

[0004] The purpose of the present invention is to establish a device for testing the friction coefficient of in-tube cable conductors and provide a method for testing the friction coefficient of conductors, which is used to measure the flow friction coefficient inside the CICC conductor, study the flow resistance of the flowing medium inside the conductor, and provide a reference for the design and optimization of the CICC conductor, the winding of superconducting magnets, and the cooling design and thermal analysis of superconducting magnets.

[0005] The present invention is achieved through the following technical solutions:

[0006] The present invention calculates the friction coefficient between the fluid in the CICC conductor and the strands and the central cooling tube by measuring the mass flow rate of the fluid flowing through the sample to be measured, the pressure or pressure difference at the inlet and outlet of the sample to be measured, and fits the relationship between the friction coefficient and the Reynolds number. According to the principle of fluid similarity, the flow situation of liquid helium in the CICC conductor is deduced.

[0007] Advantages of the present invention: The present invention uses water in the loop as the medium for testing, can provide a stable head through a centrifugal pump, precisely adjust the loop flow rate through a variable-frequency centrifugal pump and a flow regulator, and can change the physical properties such as the viscosity of water by adjusting the water temperature in the test loop, so as to achieve the effect of testing a larger Reynolds number range. The test results of the friction coefficient in the CICC conductor can intuitively reflect the flow resistance of the cooling medium inside the conductor. The friction coefficient of the CICC conductor can be obtained through experimental measurement, providing a reference for the design and optimization of the CICC conductor. Brief Description of the Drawings

[0008] Figure 1 It is a schematic diagram of the loop of the friction coefficient test device for the cable conductor in the pipe;

[0009] Figure 2 It is a diagram of a friction coefficient test device for the cable conductor in the pipe of the present invention.

[0010] In the figure, 1 - heating water tank, 2 - first thermometer, 3 - variable-frequency centrifugal pump, 4 - flow regulator, 5 - safety valve, 6 - second thermometer, 7 - flow sensor, 8 - filter valve, 9 - third thermometer, 10 - hose, 11 - sample to be measured, 12 - pressure sensor, 13 - fourth thermometer, 14 - data acquisition system. Detailed Embodiments

[0011] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. To achieve the above objectives, the present invention adopts the following technical solutions.

[0012] Figure 1 It is a friction coefficient test device for the cable conductor in the pipe of the present invention. Figure 2 It is a diagram of a friction coefficient test device for the cable conductor in the pipe of the present invention. As Figure 1 、 Figure 2As shown in the figure, the device includes a heating water tank 1, a first thermometer 2, a variable frequency centrifugal pump 3, a flow regulator 4, a safety valve 5, a second thermometer 6, a flow sensor 7, a filter valve 8, a third thermometer 9, a hose 10, a sample to be measured 11, a pressure sensor 12, a fourth thermometer 13, a data acquisition system 14, and pipelines. The pipelines include a first pipeline, a second pipeline, a third pipeline, and a fourth pipeline; water is used as the pipeline circulating medium.

[0013] The heating water tank 1 is connected to the variable frequency centrifugal pump 3 through the first pipeline. The first thermometer 2 is arranged on the first pipeline. The first thermometer 2 is a PT100 temperature sensor and is used to monitor the water temperature of this section of the pipeline; the first pipeline is a stainless steel pipeline.

[0014] The variable frequency centrifugal pump 3 is connected to the sample to be measured 11 through the second pipeline. The following are arranged in sequence on the second pipeline: a safety valve 5, a second thermometer 6, a flow sensor 7, a filter valve 8, a third thermometer 9, and a hose 10; the second and third thermometers 6 and 9 are PT100 temperature sensors; the second pipeline is a stainless steel pipeline.

[0015] The third pipeline connects the outlet and the inlet of the variable frequency centrifugal pump. The flow regulator 4 is arranged on the third pipeline. The reflux flow is controlled through the flow regulator to adjust the main flow. The flow regulator 4 consists of two groups of flow regulating valves. The third pipeline is made of stainless steel.

[0016] The sample to be measured is connected to the heating water tank 1 through the fourth pipeline. The fourth thermometer 13 is arranged on the fourth pipeline; the fourth thermometer 13 is a PT100 temperature sensor; the third pipeline is a stainless steel pipeline.

[0017] The sample to be measured 11 is a CICC type superconducting conductor, and pressure sensors 12 are installed at both ends of the sample to be measured.

[0018] The heating water tank 1 includes a water tank body, a heater, and a control cabinet; the inner layer material of the water tank body is 304 stainless steel, the outer layer material is carbon steel, and the middle sandwich is a heat insulation material; the water outlet of the water tank body is connected to the variable frequency centrifugal pump 3, and the water inlet is connected to the conductor to be measured; the temperature of the loop water can be adjusted through the heater, and the temperature adjustment range is from room temperature to 70 °C. The control cabinet is independent of the water tank body and the heater and is placed at the data acquisition system for opening and closing the heater and adjusting the heating power of the heater. The variable frequency centrifugal pump 3 can adjust the frequency in the range of 10 - 200 Hz, and its material is 304 stainless steel.

[0019] The flow regulator 4 includes a first flow regulating valve and a second flow regulating valve. The first flow regulating valve and the second flow regulating valve are respectively installed on different branches of the third pipeline. When both flow regulating valves are at 0%, the main flow is the largest. When the valve openings of both flow regulating valves are 100%, the main flow is the smallest.

[0020] The flow sensor 7 includes a first flow sensor and a second flow sensor. The first flow sensor and the second flow sensor are installed on different branches of the second pipeline, and the ranges of the two flow sensors are different, respectively applicable to large flow conditions and small flow conditions.

[0021] The sample to be measured 11 is a CICC-type conductor, and the sample to be measured 11 is connected to the loop through a flange; pressure sensors 12 are installed at both ends of the sample to be measured.

[0022] The pressure sensor 12 includes a first differential pressure sensor, a second differential pressure sensor, a first pressure sensor, and a second pressure sensor, and is used to measure the differential pressure or pressure at the inlet and outlet of the sample to be measured. The pressure sensors 12 are all installed on both sides of the sample to be measured. The first differential pressure sensor and the second differential pressure sensor work independently, or the first pressure sensor and the second pressure sensor work together to measure the pressure drop at the inlet and outlet of the sample to be measured. Their ranges are different and are respectively applicable to different pressure drop situations.

[0023] Before the sample to be measured is installed in the test device, it is wrapped with heat-insulating materials to reduce heat loss.

[0024] The data acquisition system 14 is used to collect and record the values of the flow regulator 4, the flow sensor 7, the pressure sensor 12, and all the thermometers in this device.

[0025] On the other hand, the present invention proposes a method for testing the friction coefficient of a CICC conductor by using the above device, including the following steps:

[0026] Step 1, System preparation stage: Connect the sample to be measured 11 to the device, connect and debug; turn on the heater of the heating water tank 1 and control the water to reach the temperature required for the experiment;

[0027] Step 2: Turn on the variable-frequency centrifugal pump 3, and control the loop flow by adjusting the pump frequency and the flow regulator 4; when the loop temperature and flow are stable, start measuring the temperature, pressure or differential pressure at the inlet and outlet of the sample to be measured; then gradually increase or decrease the loop flow. After each adjustment, wait for the loop temperature and flow to be stable, and monitor the temperature, pressure or differential pressure at the inlet and outlet of the sample to be measured;

[0028] Step 3: Combine the structural parameters of the sample to be measured 11 and the physical properties of water, process the data of the data acquisition system 14, calculate the friction coefficient and Reynolds number through the flow and pressure drop in the loop, fit the corresponding relationship between the friction coefficient of the sample to be measured and the fluid Reynolds number, and deduce the flow situation of liquid helium in the CICC conductor according to the principle of fluid similarity;

[0029] Further, step 1 specifically includes the following steps:

[0030] A. Pre-calculate the test sample 11, select a flow sensor 7, a pressure sensor or a differential pressure sensor with an appropriate range; and turn off the rest.

[0031] B. Perform end treatment on the sample under test 11, and weld flanges at the inlet and outlet.

[0032] C. Connect the sample under test 11 to the test device.

[0033] D. Turn on the heating water tank 1 and set the target temperature.

[0034] E. Wait until the water temperature in the system reaches the target temperature and stabilizes, then open the control valves at both ends of the sample under test 11.

[0035] Furthermore, step 2 specifically includes the following steps:

[0036] F. Turn on the variable frequency centrifugal pump 3, set the frequency to 10 Hz, and monitor the temperature, pressure or differential pressure at the inlet and outlet of the sample under test 11 when the flow rate is stable.

[0037] G. Adjust the loop flow rate. Coarse adjustment can be performed by adjusting the variable frequency centrifugal pump 3, and fine adjustment can be performed by adjusting the opening degrees of the two bypass valves. After each adjustment, wait until the loop temperature and flow rate are stable, and monitor the temperature, pressure or differential pressure at the inlet and outlet of the sample under test 11.

[0038] Furthermore, step 3 specifically includes the following steps:

[0039] By reading the experimental data recorded by the data acquisition system, querying the density ρ and viscosity η of water at the corresponding temperature and pressure, and based on the flow-through area A of the sample under test He 、hydraulic diameter D h 、length L of the sample under test, conductor porosity void, mass flow rate m flowing through the sample under test, inlet and outlet pressures P in and P out , calculate the friction coefficient f and Reynolds number Re of the sample under test under various pressure drop and flow rate conditions through the following formula, and finally fit the relationship between the friction coefficient f and Reynolds number Re of the sample under test according to the Katheder model, where a, b, c, and d are constants.

[0040] ,

[0041] ,

[0042] .

[0043] Although the above-described illustrative specific embodiments of the present invention have been described to facilitate the understanding of those skilled in the art of the present technology, and it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions made using the concept of the present invention are within the scope of protection.

Claims

1. A device for testing the friction coefficient of cable conductors in pipes, characterized in that: The device includes a heating water tank, water, pipelines, a variable frequency centrifugal pump, a flow sensor, a pressure sensor, a first thermometer, a second thermometer, a third thermometer, a fourth thermometer, a flow regulator, a data acquisition system, and a sample to be tested; wherein water is used as a pipeline circulation medium, and the pipeline includes a first pipeline, a second pipeline, a third pipeline, and a fourth pipeline; The heating water tank is connected to the variable frequency centrifugal pump through a first pipeline, and a first thermometer is arranged on the first pipeline. The first thermometer is a PT100 temperature sensor, which is used to monitor the water temperature of the first pipeline; the first pipeline is a stainless steel pipeline; The variable frequency centrifugal pump is connected to the sample to be tested through the second pipeline, and the second pipeline is arranged in sequence: a safety valve, a second thermometer, a flow sensor, a filter valve, a third thermometer, and a hose; the second and third thermometers are PT100 temperature sensors; the second pipeline is a stainless steel pipeline; The third pipeline is connected to the outlet and inlet of the variable frequency centrifugal pump. The flow regulator is installed on the third pipeline. The opening of the third pipeline is controlled by the flow regulating valve therein, so as to control the flow of the main pipeline. The flow regulator is composed of two groups of regulating valves. The third pipeline is a stainless steel pipeline. The sample to be tested is connected to the heating water tank through the fourth pipeline, and a fourth thermometer is arranged on the fourth pipeline; the fourth thermometer is a PT100 temperature sensor; the fourth pipeline is a stainless steel pipeline; The sample under test is a CICC conductor, and pressure sensors are installed at both ends of the sample under test; The data acquisition system is used to collect and record the values ​​of the flow sensor, pressure sensor, flow regulator and thermometer in the device.

2. The friction coefficient testing device for cable conductors in pipes according to claim 1, characterized in that: The heating water tank includes a water tank body, a heater and a control cabinet; the inner layer of the water tank body is made of 304 stainless steel, the outer layer is made of carbon steel, and the middle layer is made of insulation material; the water outlet of the water tank body is connected to a variable frequency centrifugal pump, and the water inlet is connected to the conductor to be measured; the temperature of the loop water can be adjusted by the heater, and the temperature adjustment range is from room temperature to 90°C. The control cabinet is independent of the water tank body and the heater, and is placed at the data acquisition system, which is used to start and close the heater and adjust the heating power of the heater.

3. The friction coefficient testing device for cable conductors in pipes according to claim 1, characterized in that: The variable frequency centrifugal pump adjusts the frequency within the range of 10-200 Hz and is made of 304 stainless steel.

4. The friction coefficient testing device for cable conductors in pipes according to claim 1, characterized in that: The flow regulator includes a first flow regulating valve and a second flow regulating valve.

5. The friction coefficient testing device for cable conductors in pipes according to claim 1, characterized in that: The flow sensor includes a first flow sensor and a second flow sensor.

6. The friction coefficient testing device for cable conductors in pipes according to claim 1, characterized in that: The sample under test is a CICC type conductor, and the sample under test is connected to the loop through a flange; pressure sensors are installed at both ends of the sample under test; the pressure sensors include a first differential pressure sensor, a second differential pressure sensor, a first pressure sensor, and a second pressure sensor, which are used to measure the pressure difference or pressure at the inlet and outlet of the sample under test; a third thermometer and a fourth thermometer are used to measure the temperature of the inlet and outlet of the sample under test; before the sample under test is installed on the test device, it is wrapped with an insulating material to reduce heat loss.

7. A method for testing the friction coefficient of a conductor using the device of claims 1-6, characterized in that: The following steps are involved: Step 1: In the preparation stage, the sample to be tested is connected to the test device, and the test device is connected and debugged; Turn on the heater of the heating water tank and control the water to reach the required temperature; Step 2, turn on the variable frequency centrifugal pump, and control the loop flow by adjusting the water pump frequency and flow regulator; when the loop temperature and flow are stable, start measuring the temperature, pressure or pressure difference of the inlet and outlet of the sample to be tested; then gradually increase or decrease the loop flow, and after each adjustment, wait for the loop temperature and flow to be stable, and monitor the temperature, pressure or pressure difference of the inlet and outlet of the sample to be tested; Step 3: Combine the structural parameters of the sample under test and the physical properties of water to process the data of the data acquisition system, calculate the friction coefficient and Reynolds number through the flow rate and pressure drop in the loop, fit the corresponding relationship between the friction coefficient of the sample under test and the fluid Reynolds number, and deduce the flow of liquid helium in the CICC conductor.

8. The method according to claim 7, characterized in that Step 1 includes the following steps: A. Pre-calculate the test sample and select a flow sensor, pressure sensor or differential pressure sensor with a suitable range; and close the valves of other flow sensors, pressure sensors or differential pressure sensors; B. Carry out end treatment on the sample to be tested and weld the inlet and outlet flanges; C. Connect the tested sample to the test device; D. Turn on the heating water tank and set the target temperature; E. When the water temperature in the system reaches the target temperature and stabilizes, open the control valves at both ends of the sample to be tested.

9. The method according to claim 8, characterized in that Step 2 includes the following steps: F. Turn on the variable frequency centrifugal pump and set the frequency to 10 Hz. When the flow rate is stable, monitor the temperature, pressure or pressure difference at the inlet and outlet of the sample being tested; G. Adjust the loop flow rate by adjusting the variable frequency centrifugal pump for coarse adjustment and the flow regulator for fine adjustment; after each adjustment, wait for the loop temperature and flow rate to stabilize and monitor the temperature, pressure or pressure difference at the inlet and outlet of the sample being tested.

10. The method according to claim 9, characterized in that Step 3 specifically includes the following steps: By reading the experimental data recorded by the data acquisition system and querying the density ρ and viscosity η of water at the corresponding temperature and pressure, according to the flow area A of the sample being tested He , hydraulic diameter D h , length of the sample to be tested L, conductor porosity void, mass flow rate m flowing through the sample to be tested, inlet pressure P in and outlet pressure P out , the friction coefficient f and Reynolds number Re of the tested sample under various pressure drop and flow conditions are calculated by the following formula, and finally the relationship between the friction coefficient f and Reynolds number Re of the tested sample is fitted according to the Katheder model to deduce the flow of liquid helium in the CICC conductor; ， ， 。

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