CN102890100A - Experiment device for boiling two-phase flow heat transfer characteristic of liquid metal sodium - Google Patents

Abstract

The invention discloses an experimental device for liquid metal sodium boiling two-phase flow heat transfer characteristics. The upper end of the outer pipeline of the experimental section is welded and connected to the center hole of the bottom surface of the upper expansion tank, and the lower end of the outer pipeline of the experimental section is welded and connected to the central hole of the lower header surface; the lower part The center hole of the bottom of the header is welded with an outer casing of the electric heating element; the electric heating element is inserted from the lower side of the outer casing of the electric heating element, and passes through the lower header, the outer pipe of the experimental section in turn, and reaches the center hole at the bottom of the upper expansion tank; the upper expansion tank The top surface is welded with liquid level probe connection, pressure gauge connection and gas line connection; the side of the upper expansion tank is welded with the first thermocouple sleeve, the first pressure guide tube and the outlet connection of liquid metal sodium; the side of the lower header is welded with the second The second pressure guide tube, the second thermocouple sleeve and the inlet of liquid metal sodium are connected. The device can be used at high temperature, has good sealing performance, and can effectively measure key parameters such as pressure and temperature during the two-phase flow process of liquid metal sodium boiling.

Description

Experimental device for heat transfer characteristics of liquid metal sodium boiling two-phase flow

【Technical field】

The invention belongs to the technical field of experimental devices for liquid metal sodium, in particular to an experimental device for boiling two-phase flow heat transfer characteristics of liquid metal sodium.

【Background technique】

Liquid metal sodium is the preferred coolant material for fast neutron reactors, and its boiling two-phase flow heat transfer characteristics are of great significance for the safe operation of sodium-cooled fast neutron reactors and the prediction and analysis of accident conditions. In order to accurately and objectively obtain the data of the heat transfer characteristics of liquid metal sodium boiling two-phase flow, corresponding experimental devices are necessary. Due to the high boiling point of liquid metal sodium (close to 900°C under normal pressure) and its very active chemical properties, the requirements for high temperature resistance and sealing performance of the corresponding experimental devices are very high.

The basic working principle of the liquid metal sodium boiling two-phase flow heat transfer characteristics experimental device is that when the liquid metal sodium flows through the experimental device, it is heated by its internal electric heating element until boiling occurs. At the same time, the temperature at the corresponding position is collected through the thermocouple arranged on the outer wall of the electric heating element and the flow channel, the flow pressure drop is collected through the pressure difference sensor at the inlet and outlet of the flow channel, and the absolute pressure of the system when boiling occurs is read through the pressure gauge. Based on the obtained data, the heat transfer characteristics of liquid metal sodium boiling two-phase flow were analyzed and studied.

For example, Chinese patent ZL201120227659.2 provides a water vapor distillation experimental device, which consists of an upper bottle for holding samples, a lower bottle for generating water vapor, a y-shaped tee, a spherical condenser, an elbow, a straight condenser, It consists of a liquid receiving pipe, a safety tube and a liquid receiving bottle. The feature is that 1/8~2/3 of the volume of the upper bottle is embedded in the lower bottle, the upper and lower bottles are separated by the bottom wall of the upper bottle, and connected by an external Y-shaped tee; the first port of the Y-shaped tee is connected to the lower bottle The upper part of the y-shaped tee leads out water vapor, and the second port of the y-shaped tee is connected to an elbow with an angle of 10° to 80°, which is directly inserted into the sample in the upper bottle to introduce water vapor for steam distillation. The third port is valved and connected to a bulb condenser. The advantage is that the Y-shaped tee can flexibly introduce water vapor into the sample or vent it, but it will not leak out, which is convenient for operation and high in safety; during the distillation process, water can be directly added to the lower bottle, and the distillation efficiency is high; the upper and lower bottles share a heat source, The structure is simple, it can prevent the bottle from accumulating water, and the thermal efficiency is high. This patent lacks the function of measuring pressure and temperature, and the manufacturing materials cannot be safely used in the high temperature environment when liquid metal sodium boils, so it is not suitable for the experiment of flow heat transfer characteristics of liquid metal sodium boiling two-phase fluid.

【Content of invention】

The purpose of the present invention is to overcome the above-mentioned shortcomings of the prior art, and to provide a method that can ensure normal use and sealing performance under high temperature conditions, and can realize accurate measurement of physical quantities such as temperature and pressure during the two-phase flow process of liquid metal sodium boiling. Experimental device for the heat transfer characteristics of liquid metal sodium boiling two-phase flow.

The purpose of the present invention is achieved through the following technical solutions:

An experimental device for the heat transfer characteristics of liquid metal sodium boiling two-phase flow, including a lower header, an outer pipe in the experimental section, an upper expansion tank and an electric heating element; the upper end of the outer pipe in the experimental section is welded to the center hole on the bottom of the upper expansion tank, The lower end of the outer pipe is welded to the center hole on the top surface of the lower header; the center hole on the bottom surface of the lower header is welded with an electric heating element outer sleeve; the electric heating element is inserted from the lower side of the electric heating element outer sleeve, passing through the lower header and the experimental section The outer pipeline reaches the center hole at the bottom of the upper expansion tank; the top of the upper expansion tank is welded with a liquid level probe connection, a pressure gauge connection and a gas line connection; the side of the upper expansion tank is welded with a first thermocouple sleeve and a first pressure guide. Pipe and liquid metal sodium outlet connection; the side of the lower header is welded with a second pressure guide tube, a second thermocouple sleeve and a liquid metal sodium inlet connection.

The further improvement of the present invention lies in that the electric heating element is sealed and connected with the bottom of the outer casing of the electric heating element through a ferrule.

The further improvement of the present invention is that: the electric heating element is positioned at the inlet and outlet of the pipeline outside the test section by three support points with angular intervals of 120°, so that the electric heating element is concentrically arranged with the pipeline outside the test section.

The further improvement of the present invention lies in that: both the outer sleeve of the electric heating element and the connecting pipe of the liquid level probe are equipped with cooling fins.

The further improvement of the present invention is that: the material of the lower header, the pipeline outside the experimental section and the upper expansion tank is Incoloy800.

The present invention has the following advantages and beneficial effects:

1. The experimental device for liquid metal sodium boiling two-phase flow heat transfer characteristics is made of high-temperature steel, which can work at high temperatures and meets the requirements of liquid metal sodium boiling two-phase flow heat transfer experiments;

2. The pipes of the liquid metal sodium boiling two-phase flow heat transfer characteristic experiment device are connected by welding, which has good sealing performance and ensures the safety of the liquid metal sodium boiling two-phase flow heat transfer experiment;

3. The lower part of the electric heating element of the liquid metal sodium boiling two-phase flow heat transfer characteristic experiment device is connected with the outer tube with heat dissipation fins by a ferrule, where the liquid metal sodium solidifies due to the temperature drop to achieve self-sealing, and the ferrule has a good Sealing, double-tightness, good effect, to ensure the safety of liquid metal sodium boiling two-phase flow heat transfer experiment;

4. Three-point precise positioning is adopted between the electric heating element and the pipe outside the experimental section, which can ensure the concentricity and improve the reliability of the experimental data;

5. The experimental device for liquid metal sodium boiling two-phase flow heat transfer characteristics is equipped with several pressure guide tubes, thermocouple sleeves and liquid level probes at specific positions, which can realize effective measurement of pressure, temperature, liquid level and other data. It provides a guarantee for the study of the heat transfer characteristics of liquid metal sodium boiling two-phase flow.

In a word, the device can be used at high temperature, has good sealing performance and can effectively measure key parameters such as pressure and temperature during the boiling two-phase flow of liquid metal sodium. It is suitable to be assembled in the liquid metal sodium circuit to analyze and study the heat transfer characteristics of liquid metal sodium boiling two-phase flow.

【Description of drawings】

Fig. 1a is a schematic diagram of the overall structure after assembly of the present invention; Fig. 1b is a partially enlarged view of the center hole at the bottom of the upper expansion tank; Fig. 1c is a partially enlarged view of the center hole on the top surface of the lower header;

Figure 2a is a schematic structural view of the upper expansion tank of the present invention; Figure 2b is a schematic top view of Figure 2a;

Fig. 3a is a schematic diagram of the structure of the lower header of the present invention; Fig. 3b is a schematic top view of Fig. 3a;

Fig. 4 is a schematic diagram of the three-point fixing structure of the present invention.

Among them: 1 is the lead end of the electric heating element; 2 is the electric heating element; 3 is the outer casing of the electric heating element; 4 is the thermocouple sleeve; 5 is the lower header; 6 is the pressure guide tube; 7 is the pipe outside the experimental section; 8 is the wall temperature thermocouple; 9 is the thermocouple casing; 10 is the pressure guide tube; 11 is the upper expansion tank; 12 is the liquid level probe connection; 13 is the pressure gauge connection; 14 is the gas circuit connection; 15 is the liquid state The metal sodium outlet takes over; 16 is the liquid metal sodium import connection; 17 is a supporting point.

【Detailed ways】

Please refer to Fig. 1a to Fig. 4, a kind of liquid metal sodium boiling two-phase flow heat transfer characteristic experimental device of the present invention, comprises lower header 5, the outer pipeline 7 of experiment section, upper expansion tank 11, electric heating element 2, pressure Introductory tubes (6, 10), thermocouple sleeves (4, 9), liquid level probe connection 12 and gas path connection 14. The experimental device for heat transfer characteristics of liquid metal sodium boiling two-phase flow of the present invention is made of Incoloy800, which can be used normally at 1200°C.

1a to 1c, several temperature measuring thermocouples 8 are arranged on the outer wall of the outer pipeline 7 in the experimental section; The center hole of the top surface is welded and connected; the center hole of the bottom surface of the lower header 5 is welded with the outer casing 3 of the electric heating element with cooling fins; The pipe 7 outside the test section reaches the center hole at the bottom of the upper expansion tank 11 .

2a and 2b, the top of the upper expansion tank 11 is welded with a liquid level probe connector 12 with cooling fins, a pressure gauge connector 13 and a gas path connector 14; Pipe 10 and liquid metal sodium outlet connecting pipe 15.

3a and 3b, the side of the lower header 5 is welded with the pressure guide pipe 6, the thermocouple sleeve 4 and the liquid metal sodium inlet connection 16; the electric heating element 2 and the bottom of the electric heating element outer casing 3 are connected through a ferrule to ensure sealing.

In combination with Fig. 4, the electric heating element 2 is positioned at the inlet and outlet of the outer pipeline 7 in the experimental section using three support points 17 with an angular interval of 120° to ensure the concentricity with the outer pipeline.

Preparatory work before the experiment: connect the experimental device of the present invention with the liquid metal sodium circuit, so that the liquid metal sodium flows in from the liquid metal sodium inlet connection 16 and flows out from the liquid metal sodium outlet connection 15; A liquid level probe suitable for liquid metal sodium is installed inside; a pressure gauge is installed on the pressure gauge connecting pipe 13; a corresponding differential pressure sensor is connected between the pressure guide tube 6 and the pressure guide tube 10; Insert high-temperature thermocouples into 9 and seal them with ferrules; connect the signal leads of measuring devices such as liquid level probes, thermocouples, and differential pressure sensors; connect the lead wire 1 of the electric heating element with the system power supply; the lower header 5, the pipe outside the experimental section 7. The upper expansion tank 11 is wrapped with thermal insulation material.

When the experiment is in progress: the liquid metal sodium is heated up by the experimental circuit preheating device to the required inlet temperature, and driven by the circuit electromagnetic pump, the liquid metal sodium inlet connection pipe 16 flows into the lower header 5 and rectifies here, and passes through the electric heating element 2 and The annular channel formed by the pipeline 7 outside the experimental section is heated by the electric heating element 2 until boiling occurs, and then enters the upper expansion tank 11. After the sodium vapor is cooled and condensed in the upper expansion tank 11, it flows out of the experiment through the liquid metal sodium outlet connection 15 device. During the experiment, the temperature is read by the thermocouple signals on the experimental device, the pressure drop and pressure are read by the differential pressure sensor and pressure gauge, the liquid level is measured by the liquid level probe, and the flow rate is read by the loop flowmeter.

After the experiment is completed: the temperature, pressure, pressure difference, flow rate and other data obtained from the experiment can be used to analyze and study the heat transfer characteristics of liquid metal sodium boiling two-phase flow.

After being installed and used in a liquid metal sodium experimental circuit, it is proved that the experimental device can meet the requirements of analyzing and researching the heat transfer characteristics of liquid metal sodium boiling two-phase flow. The device is resistant to high temperature, has good sealing performance, is easy to use, and has reasonable and reliable data. Therefore, the invention is very suitable for assembly in the circuit of liquid metal sodium used in experiments and used for the analysis and research work of the heat transfer characteristics of liquid metal sodium boiling two-phase flow.

The above content is a further detailed description of the present invention in conjunction with specific preferred embodiments. It cannot be determined that the specific embodiments of the present invention are limited thereto. Under the circumstances, some simple deduction or replacement can also be made, all of which should be regarded as belonging to the scope of patent protection determined by the submitted claims of the present invention.

Claims (5)

1. An experimental device for heat transfer characteristics of liquid metal sodium boiling two-phase flow, characterized in that it includes a lower header (5), an outer pipe (7) in the experimental section, an upper expansion tank (11) and an electric heating element (2) ;The upper end of the pipe (7) outside the test section is welded to the center hole on the bottom surface of the upper expansion tank (11), and the lower end of the pipe (7) outside the test section is welded to the center hole on the top surface of the lower header (5); the lower header (5) The center hole of the bottom surface is welded with an electric heating element outer casing (3); the electric heating element (2) is inserted from the lower side of the electric heating element outer casing (3), and passes through the lower header (5) and the outer pipe (7) of the experimental section in sequence , until the center hole at the bottom of the upper expansion tank (11); the top surface of the upper expansion tank (11) is welded with a liquid level probe connection (12), a pressure gauge connection (13) and a gas line connection (14); the upper expansion tank ( 11) The first thermocouple casing (9), the first pressure guide tube (10) and the liquid metal sodium outlet connection tube (15) are welded on the side; the second pressure guide tube (6) is welded on the side of the lower header (5) , the second thermocouple casing (4) and the liquid metal sodium inlet connection (16). 2. The experimental device for liquid metal sodium boiling two-phase flow heat transfer characteristics according to claim 1, characterized in that the electric heating element (2) is connected to the bottom of the electric heating element outer casing (3) through a ferrule seal. 3. The experimental device for liquid metal sodium boiling two-phase flow heat transfer characteristics according to claim 1, characterized in that, the electric heating element (2) adopts three angle intervals at the inlet and outlet of the pipeline (7) outside the experimental section respectively The 120° support point (17) is positioned so that the electric heating element (2) is set concentrically with the pipe (7) outside the test section. 4. The experimental device for heat transfer characteristics of liquid metal sodium boiling two-phase flow according to claim 1, characterized in that the electric heating element outer casing (3) and the liquid level probe connection (12) are equipped with cooling fins piece. 5. The experimental device for liquid metal sodium boiling two-phase flow heat transfer characteristics according to claim 1, characterized in that, the lower header (5), the outer pipeline (7) of the experimental section and the upper expansion tank (11) The material is Incoloy800.

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