阅读说明：本技术 一种研究可视化环形通道内流动沸腾的系统及其工作方法 (System for researching flow boiling in visual annular channel and working method thereof ) 是由 杜静宇 任鑫 王�华 王恩民 赵鹏程 于 2021-07-16 设计创作，主要内容包括：本发明公开的一种研究可视化环形通道内流动沸腾的系统及其工作方法,属于流动沸腾换热技术领域。储水装置内部设有温控设备,储水装置的出口与主泵连接,储水装置的出口与主泵之间设有稳压装置,主泵与预热装置连接,预热装置与可视化环形通道沸腾装置的入口连接,预热装置出口与分离装置的入口连接,分离装置的汽相出口与冷凝装置连接,分离装置(14)的液相出口与冷凝装置的出口均与储水装置的入口连接；高速摄像机(18)正对可视化环形通道沸腾装置设置。本发明能够模拟不同实验工况下的沸腾现象,并得到局部沸腾汽泡动力学特征,能够提升对沸腾机理的认识并建立沸腾传热的机理模型。(The invention discloses a system for researching flow boiling in a visual annular channel and a working method thereof, and belongs to the technical field of flow boiling heat exchange. A temperature control device is arranged in the water storage device, an outlet of the water storage device is connected with a main pump, a pressure stabilizing device is arranged between the outlet of the water storage device and the main pump, the main pump is connected with a preheating device, the preheating device is connected with an inlet of a visual annular channel boiling device, an outlet of the preheating device is connected with an inlet of a separating device, a vapor phase outlet of the separating device is connected with a condensing device, and a liquid phase outlet of the separating device (14) and an outlet of the condensing device are both connected with an inlet of the water storage device; the high-speed camera (18) is arranged opposite to the visual annular channel boiling device. The invention can simulate the boiling phenomenon under different experimental working conditions, obtain the dynamic characteristics of local boiling bubbles, improve the understanding of the boiling mechanism and establish a mechanism model of boiling heat transfer.)

1. A system for researching flow boiling in a visual annular channel is characterized by comprising a water storage device (1), a pressure stabilizing device (4), a main pump (7), a preheating device (9), a visual annular channel boiling device, a separating device (14), a condensing device (15) and a high-speed camera (18);

a temperature control device is arranged in the water storage device (1), an outlet of the water storage device (1) is connected with a main pump (7), a pressure stabilizing device (4) is arranged between the outlet of the water storage device (1) and the main pump (7), the main pump (7) is connected with a preheating device (9), the preheating device (9) is connected with an inlet of a visual annular channel boiling device, an outlet of the preheating device (9) is connected with an inlet of a separating device (14), a vapor-phase outlet of the separating device (14) is connected with a condensing device (15), and a liquid-phase outlet of the separating device (14) and an outlet of the condensing device (15) are both connected with an inlet of the water storage device (1); the high-speed camera (18) is arranged right opposite to the visual annular channel boiling device;

the visual annular channel boiling device comprises a heating rod (11) and a transparent circular tube (12), wherein the heating rod (11) is coaxially arranged inside the transparent circular tube (12), and an even annular channel is formed between the heating rod (11) and the transparent circular tube (12); an inlet parameter detection device (10) and an outlet parameter detection device (13) are respectively arranged at the inlet and the outlet of the visual annular channel boiling device.

2. The system for researching flow boiling in the visual annular channel according to claim 1, wherein the temperature control device inside the water storage device (1) comprises a heating wire (2) and a cooling coil (3), the heating wire (2) is connected with a temperature controller, and the cooling coil (3) is connected with a cooling water circulation system; a temperature detection device is arranged at the outlet of the water storage device (1).

3. The system for researching flow boiling in a visual annular channel according to claim 1, wherein the pressure stabilizer (4) comprises a pressure stabilizer tank, the outlet of the pressure stabilizer tank is provided with a pressure stabilizer tank outlet valve, the pressure stabilizer tank is provided with a compressed air pipe (5), a pressure gauge and a safety valve (6), and the compressed air pipe (5) is connected with a compression system.

4. The system for studying flow boiling in a visualization annular channel according to claim 1, characterized in that the main pump (7) is a centrifugal pump, and a flow meter (8) is arranged between the main pump (7) and the preheating device (9).

5. The system for studying flow boiling in a visual annular channel according to claim 1, characterized in that the inlet pipeline of the water storage means (1) is provided with a main valve (17).

6. The system for studying flow boiling in a visual annular channel according to claim 1, characterized in that the preheating means (9) comprise a heat exchanger, the cold side inlet of which is connected to the main pump (7), the cold side outlet of which is connected to the inlet of the visual annular channel boiling means, the hot side inlet of which is connected to the vapour phase outlet of the separation means (14), and the hot side outlet of which is connected to the condensation means (15).

7. The system for studying flow boiling in a visual annular channel according to claim 1, characterized in that a heating wire and a plurality of thermocouples are arranged inside the heating rod (11); the heating wires are spirally distributed in the heating rod (11) and are not contacted with the inner wall of the heating rod (11); the thermocouples are uniformly distributed.

8. The system for studying flow boiling in a visual annular channel according to claim 1, characterized in that the inlet parameter detection means (10) and the outlet parameter detection means (13) comprise both pressure detection means and temperature detection means.

9. The system for studying flow boiling in a visual annular channel according to claim 1, characterized in that the high speed camera (18) is arranged on a height-adjustable support, and a lens capable of correcting the curvature of the circular tube is arranged in front of the lens of the high speed camera (18).

10. The method for studying the system for visualizing flow boiling in an annular channel according to any of the claims 1 to 9, comprising:

the water in the water storage device (1) is maintained at a preset temperature through a temperature control device, flows through a main pump (7), is heated through a preheating device (9) to be heated, then enters a visual annular channel boiling device, is heated to boil to generate steam bubbles after entering the visual annular channel boiling device, detects related parameters through an inlet parameter detection device (10) and an outlet parameter detection device (13), the outlet of the visual annular channel boiling device is in steam-liquid two-phase flow, is separated through a separation device (14), steam is condensed through a condensation device (15) to become liquid water again, and is merged with the water separated by the separation device (14) and then returns to the water storage device (1) again; the pressure in the system is regulated in real time through a pressure stabilizer (4); when the inlet temperature and the outlet temperature of the visual annular channel boiling device reach stability, a high-speed camera (18) is adopted to shoot a picture of the bubbles, and the activated core density, the bubble separation diameter and the bubble separation frequency are obtained through image processing.

Technical Field

The invention belongs to the technical field of flow boiling heat exchange, and particularly relates to a system for researching flow boiling in a visual annular channel and a working method thereof.

Background

The boiling phenomenon is widely applied to high-power density equipment such as nuclear reactors, boilers and the like, and the understanding of the boiling heat transfer characteristic has important guiding significance and application value for industrial engineering. Generally, the boiling heat transfer is divided into four stages: natural convection zone, nucleate boiling zone, transition boiling zone, and film boiling zone.

From a microscopic perspective, the flow boiling heat transfer process generally includes three parts, latent heat of vaporization, transient heat conduction and single-phase convective heat transfer. The calculation of the models needs to seal characteristic parameter information of the bubbles, specifically comprises the bubble separation diameter describing the size of the bubbles, the activation core density describing the number of the bubbles and the bubble separation frequency representing the cycle period of the bubbles, the parameters are influenced by a plurality of factors, and the accuracy directly influences the calculation of the heat exchange characteristics.

Disclosure of Invention

In order to solve the above problems, the present invention aims to provide a system for studying flow boiling in a visual annular channel and a working method thereof, which can simulate boiling phenomena under different experimental conditions, obtain dynamic characteristics of local boiling bubbles, improve understanding of boiling mechanism, and establish a mechanism model of boiling heat transfer.

The invention is realized by the following technical scheme:

the invention discloses a system for researching flow boiling in a visual annular channel, which comprises a water storage device, a pressure stabilizing device, a main pump, a preheating device, a visual annular channel boiling device, a separating device, a condensing device and a high-speed camera, wherein the main pump is connected with the preheating device;

a temperature control device is arranged in the water storage device, an outlet of the water storage device is connected with a main pump, a pressure stabilizing device is arranged between the outlet of the water storage device and the main pump, the main pump is connected with a preheating device, the preheating device is connected with an inlet of a visual annular channel boiling device, an outlet of the preheating device is connected with an inlet of a separating device, a vapor phase outlet of the separating device is connected with a condensing device, and a liquid phase outlet of the separating device and an outlet of the condensing device are both connected with an inlet of the water storage device; the high-speed camera is arranged right opposite to the visual annular channel boiling device;

the visual annular channel boiling device comprises a heating rod and a transparent circular tube, wherein the heating rod is coaxially arranged in the transparent circular tube, and an even annular channel is formed between the heating rod and the transparent circular tube; an inlet parameter detection device and an outlet parameter detection device are respectively arranged at the inlet and the outlet of the visual annular channel boiling device.

Preferably, the temperature control device in the water storage device comprises a heating wire and a cooling coil, the heating wire is connected with a temperature controller, and the cooling coil is connected with a cooling water circulation system; a temperature detection device is arranged at the outlet of the water storage device.

Preferably, the pressure stabilizer comprises a pressure stabilizing tank, a pressure stabilizing tank outlet valve is arranged at the outlet of the pressure stabilizing tank, a compressed air pipe, a pressure gauge and a safety valve are arranged on the pressure stabilizing tank, and the compressed air pipe is connected with the compression system.

Preferably, the main pump is a centrifugal pump, and a flow meter is arranged between the main pump and the preheating device.

Preferably, a main valve is arranged on an inlet pipeline of the water storage device.

Preferably, the preheating device comprises a heat exchanger, a cold side inlet of the heat exchanger is connected with the main pump, a cold side outlet of the heat exchanger is connected with an inlet of the visual annular channel boiling device, a hot side inlet of the heat exchanger is connected with a vapor phase outlet of the separation device, and a hot side outlet of the heat exchanger is connected with the condensing device.

Preferably, a heating wire and a plurality of thermocouples are arranged inside the heating rod; the heating wires are spirally distributed in the heating rod and are not contacted with the inner wall of the heating rod; the thermocouples are uniformly distributed.

Preferably, the inlet parameter detection means and the outlet parameter detection means each comprise pressure detection means and temperature detection means.

Preferably, the high-speed camera is arranged on the height-adjustable support, and a lens capable of correcting the curvature of the circular tube is arranged in front of the lens of the high-speed camera.

The invention discloses a working method of the system for researching flow boiling in the visual annular channel, which comprises the following steps:

the water in the water storage device is maintained at a preset temperature through a temperature control device, flows through a main pump, is heated by a preheating device to be heated, then enters a visual annular channel boiling device, enters the visual annular channel boiling device and is heated to be boiled to generate steam bubbles, relevant parameters are detected through an inlet parameter detection device and an outlet parameter detection device, the outlet of the visual annular channel boiling device is in a steam-liquid two-phase flow, the steam is separated through a separation device, the steam is condensed through a condensation device and is changed into liquid water again, and the liquid water is merged with the water separated by the separation device and then returns to the water storage device again; the pressure in the system is regulated in real time through a pressure stabilizer; when the inlet temperature and the outlet temperature of the visual annular channel boiling device reach stability, a high-speed camera is adopted to shoot a picture of the vapor bubble, and the activated core density, the vapor bubble separation diameter and the vapor bubble separation frequency are obtained through image processing.

Compared with the prior art, the invention has the following beneficial technical effects:

the invention discloses a system for researching flow boiling in a visual annular channel, wherein working medium water enters a visual annular channel boiling device after being preheated, the working medium water is gradually heated to boiling by a heating rod along the length of the heating rod to generate steam to form boiling two-phase flow, the steam and the water at an outlet are separated in a separation device, the steam is firstly condensed by a condensing device to become liquid water again, and the liquid water is converged with the separated water and then returns to a water storage device again. The flow condition and different flow patterns in the boiling device of the visual annular channel can be observed through the high-speed camera, and parameters representing the characteristics of the bubbles including the density of the activated core, the bubble separation diameter and the bubble separation frequency can be obtained through subsequent image analysis. Pressure stabilizer can the inside pressure of governing system, and the main pump can flow and the velocity of flow in the governing system, and the water storage device and the preheating device that have temperature control equipment can be jointly the temperature in the governing system, and separator can separate the steam and the water of visual annular channel export to adopt the condenser to condense the steam that produces, thereby improve entire system's circulation efficiency. The invention can simulate the boiling phenomenon under different experimental working conditions, obtain the dynamic characteristics of local boiling bubbles, improve the understanding of the boiling mechanism and establish a mechanism model of boiling heat transfer.

Furthermore, the heating wires and the cooling coil pipes in the water storage device can efficiently adjust the water temperature so as to keep the temperature balance of the system under the steady-state working condition.

Further, the surge tank can control the pressure change inside the pressure stabilizer through regulating the flow of the compressed air, the pressure gauge can read in real time, and safety is guaranteed through the safety valve.

Furthermore, the main pump adopts a centrifugal pump, provides a lift for the working medium water entering the visual annular channel boiling device, can adjust the flow velocity of the water, and reads the flow parameter of the water in real time through the flowmeter.

Furthermore, a main valve is arranged on an inlet pipeline of the water device, so that the speed of the whole system can be controlled, and the emergency closing can be realized.

Furthermore, the heat exchanger of the preheating device can preheat the working medium water by utilizing the heat of the water vapor of the separation device, and the energy in the system is fully utilized.

Furthermore, heating wires in the heating rod are distributed in a spiral mode and are heated uniformly; the heating wire is not contacted with the inner wall of the heating rod, so that the local overhigh temperature is avoided; the thermocouples are uniformly distributed, and can measure the temperature values of all positions of the heating rod.

Furthermore, the high-speed camera is arranged on the height-adjustable bracket and can adjust the observation height; because the transparent circular tube outside the circular tube has a certain curvature, the shape and the size of the shot bubble can be influenced, and the lens capable of correcting the curvature of the circular tube is arranged in front of the lens of the high-speed camera, so that the problem of distortion caused by the fact that the transparent circular tube shoots the shape and the size of the bubble is effectively solved.

The working method for researching the system for flow boiling in the visual annular channel disclosed by the invention has high automation degree, can simulate the boiling phenomenon under different experimental working conditions, obtains the dynamic characteristics of local boiling bubbles, and can promote the understanding of the boiling mechanism and establish a boiling heat transfer mechanism model.

Drawings

Fig. 1 is a schematic view of the overall structure of the present invention.

In the figure: 1. a water storage device; 2. heating wires; 3. a cooling coil; 4. a voltage stabilizer; 5. a compressed air pipe; 6. a safety valve; 7. a main pump; 8. a flow meter; 9. a preheating device; 10. an entrance parameter detection device; 11. a heating rod; 12. a transparent circular tube; 13. an outlet parameter detection device; 14. a separation device; 15. a condensing unit; 16. cooling water; 17. a main valve; 18. high-speed cameras.

Detailed Description

The present invention will now be described in further detail with reference to the accompanying drawings, which are included to illustrate and not to limit the invention:

as shown in fig. 1, for the system for researching flow boiling in the visual annular channel, a temperature control device is arranged inside a water storage device 1, an outlet of the water storage device 1 is connected with a main pump 7, a pressure stabilizing device 4 is arranged between the outlet of the water storage device 1 and the main pump 7, the main pump 7 is connected with a preheating device 9, the preheating device 9 is connected with an inlet of the visual annular channel boiling device, an outlet of the preheating device 9 is connected with an inlet of a separation device 14, a vapor phase outlet of the separation device 14 is connected with a condensing device 15, and a liquid phase outlet of the separation device 14 and an outlet of the condensing device 15 are both connected with an inlet of the water storage device 1; the high speed camera 18 is positioned directly opposite the visualization annular channel boiling device.

The visual annular channel boiling device comprises a heating rod 11 and a transparent circular tube 12, wherein the heating rod 11 is coaxially arranged inside the transparent circular tube 12, and an even annular channel is formed between the heating rod 11 and the transparent circular tube 12; an inlet and an outlet of the visual annular channel boiling device are respectively provided with an inlet parameter detection device 10 and an outlet parameter detection device 13, and the inlet parameter detection device 10 and the outlet parameter detection device 13 both comprise a pressure detection device and a temperature detection device.

The transparent circular tube 12 may be a glass circular tube or a quartz circular tube, or a circular tube made of another heat-resistant transparent material.

In a preferred embodiment of the present invention, the temperature control device inside the water storage device 1 comprises a heating wire 2 and a cooling coil 3, the heating wire 2 is connected with a temperature controller, and the cooling coil 3 is connected with a cooling water circulation system; a temperature detection device is arranged at the outlet of the water storage device 1.

In a preferred embodiment of the present invention, the pressure stabilizer 4 comprises a pressure stabilizer tank, the outlet of the pressure stabilizer tank is provided with a pressure stabilizer outlet valve, the pressure stabilizer tank is provided with a compressed air pipe 5, a pressure detection device and a safety valve 6, and the compressed air pipe 5 is connected with the compression system.

In a preferred embodiment of the present invention, the main pump 7 is a centrifugal pump, a flow meter 8 is arranged between the main pump 7 and the preheating device 9, and the flow meter 8 can be an electromagnetic flow meter.

In a preferred embodiment of the invention, a main valve 17 is provided on the inlet line of the water storage device 1.

In a preferred embodiment of the invention, the preheating means 9 comprises a heat exchanger, the cold side inlet of which is connected to the main pump 7, the cold side outlet of which is connected to the inlet of the visual annular channel boiling means, the hot side inlet of which is connected to the vapour phase outlet of the separating means 14, and the hot side outlet of which is connected to the condensing means 15. The preheating device 9 can also be additionally provided with a heating device connected with the hot side outlet of the heat exchanger to heat the working medium water of which the temperature of the hot side outlet does not reach the preset requirement.

In a preferred embodiment of the present invention, a heating wire and a plurality of thermocouples are arranged inside the heating rod 11; the heating wires are spirally distributed in the heating rod 11 and are not contacted with the inner wall of the heating rod 11; the thermocouples are uniformly distributed.

In a preferred embodiment of the present invention, the high-speed camera 18 is mounted on a height-adjustable support, and a lens capable of correcting the curvature of the circular tube is disposed in front of the lens of the high-speed camera 18.

The following further explains the principle in connection with the working method of the present invention:

since the boiling phenomenon is very complex, the research on the boiling mechanism from the movement of microscopic bubbles is an effective and accurate method. In order to establish a boiling mechanism model with strong universality, the system disclosed by the invention can simulate the boiling phenomenon under different experimental working conditions and obtain the dynamic characteristics of local boiling bubbles.

Before the experiment is carried out, enough working medium water needs to be stored in the water storage device 1, and the bottom of the water storage device 1 is provided with a built-in heating wire 2 and a built-in cooling coil 3. Before the experiment begins, the opening of each valve is checked, and then the centrifugal pump 7 is started to circulate the loop. Firstly, reading the system pressure of a test channel through an inlet pressure gauge, pressurizing by opening a compressed air valve and adjusting the flow of compressed air, and reducing the pressure by adjusting the valve opening of a safety valve 6 until the inlet pressure of the channel is stabilized at a set experimental working condition value. Then, the built-in heating wire 2 and the preheating device 9 of the water storage device 1 are started to heat the circularly flowing working medium water, when the inlet temperature of the visual annular channel boiling device is about to reach the set experimental working condition, the cooling coil 3 is started and gradually adjusted to ensure that the thermal balance stable state is reached, and at the moment, the inlet temperature of the visual annular channel boiling device is stabilized near the set temperature value. In the whole system loop, preheated working medium water enters the annular channel of the visual annular channel boiling device from bottom to top through the main pump 7 and the flowmeter 8, and the internal flow condition of the annular pipe can be observed. Along the length of the heating rod 11, the working medium water is gradually heated to boiling by the heating rod 11 to generate steam, and two-phase flow of boiling is formed. The steam and the water at the outlet of the visual annular passage boiling device are separated in the steam-water separator, the steam is firstly condensed by the cooling water through the condensing device 15, and then is changed into liquid water again, and the liquid water is merged with the separated water and then returns to the water storage device 1 again. When the inlet temperature and the outlet temperature of the water reach stability, the position of the high-speed camera 18 is adjusted, a light source is supplemented for focusing until a clear picture of the bubbles is shot, and the activated core density, the bubble separation diameter and the bubble separation frequency are obtained through image processing. After the experiment is finished, the built-in heating wire 2, the preheating device 9 and the heating rod 11 are firstly closed until the working medium water in the channel returns to the state of single-phase flow again, then the separation device 14 and the condensing device 15 are closed, finally the main pump 7 is closed, the switch stops the circulation, the system main valve 17 is closed, and the experiment process is ended.

The above description is only a part of the embodiments of the present invention, and although some terms are used in the present invention, the possibility of using other terms is not excluded. These terms are used merely for convenience in describing and explaining the nature of the invention and are to be construed as any additional limitation which is not in accordance with the spirit of the invention. The foregoing is merely an illustration of the present invention for the purpose of providing an easy understanding and is not intended to limit the present invention to the particular embodiments disclosed herein, and any technical extensions or innovations made herein are protected by the present invention.