Particle flow boiling two-way circulating flow enhanced heat exchange device

Abstract

The invention provides a flow boiling two-way circulating flow enhanced heat exchange device for particles. The flow boiling two-way circulating flow enhanced heat exchange device comprises a boiling heating device, a positive and negative circulating system, a visual experiment section and a monitoring system. The boiling heating device is used for heating the working medium in the visual experiment section to a boiling state; particles are arranged in the visual experiment section, and a filtering device for preventing the particles from escaping is arranged at an inlet and an outlet of the visual experiment section; an observation device is arranged outside the visual experiment section and is used for observing a vapor-liquid-particle three-phase flow behavior in a boiling process in the experiment section; the positive and negative circulation system is communicated with the visual experiment section, so that the working medium drives the particles to directionally flow in the visual experiment section; the monitoring system is used for monitoring the temperature change of the contact surface of the boiling heating device and the visual experiment section. The flow boiling device can be used for adding and discharging millimeter-level particles at any time, and the dynamic behaviors of large particles and bubbles can be observed in a visual window.

Description

Technical Field

[0001] The invention relates to the field of heat exchange, in particular to a particle flow boiling bidirectional circulation flow enhanced heat exchange device. Background Art

[0002] The miniaturization and high integration of equipment have led to a continuous increase in energy density, which will bring great challenges to the heat dissipation of equipment components. High power density equipment means that more heat is generated in the same time, so how to achieve high heat flux density cooling in a limited space becomes the key to ensure the stable operation of the system. Flow boiling can improve heat transfer performance, so it is widely used in the cooling and heat exchange systems of electronic equipment and power machinery to ensure the stable operation of the equipment. In order to enhance heat transfer, adding particles to the fluid can increase the heat transfer interface of the solid-liquid two-phase system and enhance the effective thermal conductivity of the solid-liquid two-phase. Finally, the interaction between particles and bubbles generated in flow boiling will also affect bubble nucleation and its dynamic evolution behavior, especially the growth and detachment behavior of bubbles, so particles can directly affect the boiling heat transfer performance.

[0003] In existing particle fluid flow boiling devices, the particles are mainly nanoparticles. When nanoparticles are added to fluid, they usually appear in the state of suspension. Therefore, the process of nanofluid circulating in the pipeline is similar to that of conventional fluid. However, when the flow conditions of nanofluid are not suitable or the flow time is too long, the particles may be deposited on the inner wall of the pipeline. In addition, the existing experimental device does not consider the impact of bubbles after boiling on the pipeline pressure. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a particle flow boiling bidirectional circulation flow enhanced heat exchange device, which can be used to add and discharge millimeter-sized particles at any time, and the behavior of large particles and bubble dynamics can be observed in the visualization window.

[0005] The present invention achieves the above technical objectives through the following technical means.

[0006] A particle flow boiling bidirectional circulation flow enhanced heat exchange device comprises a boiling heating device, a forward and reverse circulation system, a visual experimental section and a monitoring system; the boiling heating device is used to heat the working medium in the visual experimental section to a boiling state; particles are arranged in the visual experimental section, and a filtering device is provided at the inlet and outlet of the visual experimental section to prevent the particles from escaping; an observation device is provided outside the visual experimental section to observe the vapor-liquid-particle three-phase flow behavior of the boiling process in the experimental section; the forward and reverse circulation system is connected to the visual experimental section, so that the working medium drives the particles in a directional flow channel in the visual experimental section; the monitoring system determines the boiling heat exchange efficiency of the particle-containing working medium according to the temperature change of the surface in contact with the boiling heating device and the visual experimental section.

[0007] Furthermore, the boiling heating device includes a heating block, a thermocouple and a heating rod, and a plurality of heating rods are symmetrically arranged on the heating block for heating the heating block; the heating block is in contact with the visualization experiment section; the contact surface between the heating block and the visualization experiment section is provided with an array-distributed thermocouple, and the monitoring system obtains the measurement value of the thermocouple.

[0008] Furthermore, the contact surface of the heating block is divided into several layers of measuring surfaces, and the array-distributed thermocouples on each layer of measuring surface are used to calculate the heat flux density inside the heating copper block.

[0009] Furthermore, the forward and reverse circulation system includes a first self-priming pump, a second self-priming pump, a liquid storage tank, a diaphragm accumulator and a heat exchanger, wherein the inlet and outlet of the first self-priming pump are connected in parallel with the outlet and inlet of the second self-priming pump; the first self-priming pump, the diaphragm accumulator, the heat exchanger, the liquid storage tank and the visualization experiment section in sequence form a closed-loop system; the diaphragm accumulator is used to reduce the pressure fluctuation of the closed-loop system during three-phase flow; the heat exchanger is used to change the working fluid temperature in the closed-loop system.

[0010] Furthermore, the monitoring system also includes a turbine flowmeter, a pressure sensor and a temperature sensor; the closed-loop system is provided with a turbine flowmeter for measuring the flow of the closed-loop system; the inlet and outlet of the visualization experiment section are respectively provided with a pressure sensor and a temperature sensor.

[0011] Furthermore, the visualization experiment section includes a transparent pipe, a particle addition section and a particle recovery section; a first filter screen and a second filter screen are respectively provided at both ends of the transparent pipe, and a particle addition section is provided between the first filter screen and one end of the transparent pipe for adding particles; a four-way interface is provided between the second filter screen and the other end of the transparent pipe, and a particle recovery section is provided on one side of the four-way interface for recovering particles; the other side of the four-way interface is connected to the first filter screen and the particle addition section through a particle circulation pipeline.

[0012] Furthermore, the visualization experiment section also includes a second needle valve, a first check valve, a second check valve, a third needle valve and a fourth needle valve; a fourth needle valve is provided between the other end of the transparent pipe and the four-way interface, and a second check valve is installed on one side of the second filter; a third needle valve is provided between the particle recovery section and one side of the four-way interface; a second needle valve is provided between the first filter and the particle addition section; and a first check valve is installed on the particle circulation pipeline.

[0013] Furthermore, the third needle valve is controlled to be closed and the second needle valve is controlled to be opened, so that the particles circulate between the transparent pipe and the particle circulation pipeline.

[0014] The beneficial effects of the present invention are:

[0015] 1. The particle flow boiling bidirectional circulation flow enhanced heat exchange device of the present invention adds metal particles in the visualization experimental section, and the contact between the particles and the boiling steam bubbles can increase the solid-liquid two-phase heat transfer interface and enhance the effective thermal conductivity of the solid-liquid two-phase. The boiling heat exchange efficiency of the particle-containing working medium can be determined by the monitoring system according to the temperature change of the surface in contact with the boiling heating device and the visualization experimental section.

[0016] 2. The particle flow boiling bidirectional circulation flow enhanced heat exchange device described in the present invention can reduce the pressure fluctuation of the closed-loop system during three-phase flow by providing a diaphragm accumulator in the pipeline.

[0017] 3. In the particle flow boiling bidirectional circulation flow enhanced heat exchange device described in the present invention, the contact surface of the heating block is divided into several layers of measuring surfaces, and the array-distributed thermocouples on each layer of measuring surface are used to calculate the heat flux density inside the heating copper block.

[0018] 4. The particle flow boiling bidirectional circulation flow enhanced heat exchange device described in the present invention has a visualized experimental section including a transparent pipe, a particle adding section and a particle recovery section for the convenience of experimental operation, which greatly reduces unnecessary time during the operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. The drawings described below are some embodiments of the present invention. For ordinary technicians in this field, it is obvious that other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 This is a schematic diagram of the particle flow boiling bidirectional circulation flow enhanced heat exchange device described in the present invention.

[0021] Figure 2 This is a schematic diagram of the visualization experiment section described in the present invention.

[0022] In the figure:

[0023] 1-Visualization experiment section; 2-High-speed camera; 3-Temperature controller; 4-First needle valve; 5-Electric heater; 6-Liquid storage tank; 7-Heat exchanger; 8-Chiller; 9-Filter; 10-Third ball valve; 11-Diaphragm accumulator; 12-First self-priming pump; 13-Second self-priming pump; 14-Turbine flowmeter; 15-Pressure sensor; 16-Temperature sensor; 17-Thermocouple; 18-Heating rod; 19-Power supply; 20-Temperature inspection instrument; 21-Heating block; 22-First ball valve; 23-Working fluid A port; 24-First filter; 25-Second needle valve; 26-First check valve; 27-Second check valve; 28-Working fluid B port; 29-Second filter; 30-Third needle valve; 31-Fourth needle valve; 32-Second ball valve. DETAILED DESCRIPTION

[0024] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0025] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "axial", "radial", "vertical", "horizontal", "inner", "outer" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0026] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] like Figure 1As shown, the particle flow boiling bidirectional circulation flow enhanced heat exchange device described in the present invention includes a boiling heating device, a forward and reverse circulation system, a visual experiment section 1 and a monitoring system; the boiling heating device is used to heat the working medium in the visual experiment section 1 to a boiling state; particles are arranged in the visual experiment section 1, and the inlet and outlet of the visual experiment section 1 are provided with a filtering device to prevent particles from escaping; an observation device is arranged outside the visual experiment section 1 to observe the vapor-liquid-particle three-phase flow behavior of the boiling process in the experimental section; the forward and reverse circulation system is connected to the visual experiment section 1, so that the working medium drives the particles in the directional flow channel of the visual experiment section 1; the monitoring system determines the boiling heat exchange efficiency of the working medium containing particles according to the temperature change of the surface where the boiling heating device contacts the visual experiment section 1. In the present invention, millimeter-sized particles are arranged in the visual experiment section 1. The present invention adds metal particles in the visualization experimental section, and the contact between the particles and the boiling steam bubbles can increase the solid-liquid two-phase heat transfer interface and enhance the effective thermal conductivity of the solid-liquid two-phase. The boiling heat transfer efficiency of the particle-containing working fluid can be determined by monitoring the temperature change of the surface of the boiling heating device in contact with the visualization experimental section.

[0028] The boiling heating device includes a heating block 21, a thermocouple 17 and a heating rod 18. A plurality of heating rods 18 are symmetrically arranged on the heating block 21 for heating the heating block 21. The heating block 21 is in contact with the visualization experiment section 1. The contact surface between the heating block 21 and the visualization experiment section 1 is provided with an array of thermocouples 17. The voltage signal data generated by all thermocouples are collected by the temperature inspection instrument 20 and input into the monitoring system, and the monitoring system obtains the measurement value of the thermocouple 17. The contact surface of the heating block 21 is divided into several layers of measuring surfaces. The array of thermocouples 17 on each layer of measuring surface is used to calculate the heat flux density inside the heating copper block.

[0029] The forward and reverse circulation system includes a first self-priming pump 12, a second self-priming pump 13, a liquid storage tank 6, a diaphragm accumulator 11 and a heat exchanger 7. The inlet and outlet of the first self-priming pump 12 are connected in parallel with the outlet and inlet of the second self-priming pump 13; the first self-priming pump 12, the diaphragm accumulator 11, the heat exchanger 7, the liquid storage tank 6 and the visualization experiment section 1 form a closed-loop system in sequence; the diaphragm accumulator 11 is used to reduce the pressure fluctuation of the closed-loop system during three-phase flow; the heat exchanger 7 is used to change the working medium temperature in the closed-loop system. The liquid storage tank 6 can provide liquid medium to the forward and reverse circulation system. In the embodiment, an electric heater 5 is provided in the liquid storage tank 6, which can heat the liquid medium in the liquid storage tank 6 to increase the initial liquid medium temperature. The temperature controller 3 is used to adjust the heating temperature of the electric heater 5.

[0030] The monitoring system also includes a turbine flowmeter 14, a pressure sensor 15 and a temperature sensor 16; the closed-loop system is provided with a turbine flowmeter 14 for measuring the flow of the closed-loop system; the inlet and outlet of the visualization experiment section 1 are respectively provided with a pressure sensor 15 and a temperature sensor 16.

[0031] The visualization experiment section 1 includes a transparent pipe, a particle addition section and a particle recovery section; the two ends of the visualization experiment section 1 are respectively provided with a working fluid B port 28 and a working fluid A port 23. The working fluid B port 28 is installed with a second filter screen 29, and the working fluid A port 23 is installed with a first filter screen 24; a particle addition section is provided between the first filter screen 24 and one end of the transparent pipe for adding particles; a four-way interface is provided between the second filter screen 29 and the other end of the transparent pipe, and a particle recovery section is provided on one side of the four-way interface for recovering particles; the other side of the four-way interface is connected to the first filter screen 24 and the particle addition section through a particle circulation pipeline. A high-speed camera 2 is provided on the outside of the transparent pipe, which can observe the transparent pipe and obtain graphic videos. A first ball valve 22 is provided on the particle addition section, and a second ball valve 32 is provided on the particle recovery section. A fourth needle valve 31 is provided between the other end of the transparent pipe and the four-way interface, a second check valve 27 is installed between the second filter screen 29 and the working medium B port; a third needle valve 30 is provided between the particle recovery section and one side of the four-way interface; a second needle valve 25 is provided between the first filter screen 24 and the particle adding section; and a first check valve 26 is installed on the particle circulation pipeline. A diaphragm pump or a pressure pump can be installed on the particle circulation pipeline to increase the pressure in the particle circulation pipeline.

[0032] Example

[0033] Before the test begins, liquid is added to the liquid storage tank 6, the third ball valve 10 is opened, and the first self-priming pump 12 is started, and the cooling medium is driven to circulate under the boost pressure of the pump. The maximum flow rate of the first self-priming pump is 4L / min, and the flow rate is changed by the stepless speed knob. The pressure fluctuation of the cooling medium in the loop is adjusted by the diaphragm accumulator 11. The air bag in the diaphragm accumulator 11 is pre-filled with 1 bar of nitrogen, and the pressure is stabilized by the Boyle principle. A pressure sensor 15 is arranged before the entrance of the visualization experiment section 1 to monitor the pressure fluctuation during the operation of the loop, and the volume flow rate of the loop is measured by the vortex flowmeter 14. A temperature sensor 16 is arranged at the entrance and exit of the visualization test section 1 to measure the inlet and outlet temperature changes of the test section. In order to meet the inlet supercooling requirements, an electric heater 5 needs to be installed in the liquid storage tank 6, and the electric heater 5 is connected to the temperature controller 3. The heat exchanger 7 can heat the medium in the forward and reverse circulation system, and can also cool the medium in the forward and reverse circulation system.

[0034] The first self-priming pump 12 is a self-priming pump that makes the fluid flow in a clockwise direction, and the second self-priming pump 13 is a self-priming pump that makes the fluid flow in a counterclockwise direction. The two water pumps are not turned on at the same time. When a particle fluid flow boiling experiment is required, the first self-priming pump 12 is turned on; when the experiment is terminated and the particles inside the small cycle are cleaned, the second self-priming pump 13 is turned on to make the fluid flow in the reverse direction.

[0035] like Figure 2 As shown, when conducting the experiment, particles can be added from the first ball valve 22. After adding, the first ball valve 22 is closed, and the third needle valve 30 is closed. Finally, the first self-priming pump 12 is opened, and the fluid begins to flow in a clockwise direction. The fluid first flows in from the working fluid B port 28, passes through the second check valve 27 and the second filter screen 29 in sequence. Due to the first check valve 26 and the closed third needle valve 30, the fluid can only flow through the fourth needle valve 31, the visualization experiment section 1 and the second needle valve 25. Then, part of the fluid passes through the first filter screen 24 and then flows to the mainstream circuit. Another part of the fluid passes through the first check valve 26 with particles, and then flows to the left to the needle valve 31 when passing through the four-way channel and circulates in this way. The above is the entire clockwise circulation process.

[0036] When conducting the experiment, turn on the chiller 8 and set the predetermined cooling temperature. Then turn on the electric heater 5 in the liquid storage tank 6, and set the preheating temperature through the temperature controller 3. Finally, turn on the knob of the power supply 19 to start the 6 200W power heating rods pre-inserted in the copper block, and then observe the temperature of the thermocouple 17 in the array inserted in the middle of the copper block displayed by the temperature inspection instrument 20. Through the cooperation of the two, the system inlet supercooling reaches the expected and remains stable. By adjusting the output voltage of the AC voltage regulating power supply 19, adjust the simulated heat source heating power. After waiting for the heating power to stabilize, start recording data. Record the current flow rate, inlet supercooling, and use the high-speed camera 2 to record the bubble behavior. Install the high-speed camera 2 and the LED light source directly above the high borosilicate glass of the heating flow channel test section. Connect the high-speed camera 2 and the computer, adjust the position, aperture and focal length of the high-speed camera. Adjust the angle and position of the LED light source, and the two cooperate to make the image effect presented by the computer reach the best state. According to the test plan, adjust the preset temperature of the chiller 8 and the speed of the first self-priming pump 12, change the working conditions, and repeat the above test steps.

[0037] After the experiment, the used particles need to be discharged. Therefore, the second needle valve 25, the fourth needle valve 31, the third needle valve 30 and the second ball valve 32 are opened, and finally the second self-priming pump 13 is opened. The fluid flows in from the working medium A port 23 in a counterclockwise direction, and the particles are finally discharged through the second ball valve 32.

[0038] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0039] The series of detailed descriptions listed above are only specific descriptions of feasible embodiments of the present invention. They are not intended to limit the scope of protection of the present invention. All equivalent embodiments or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A particle flow boiling bidirectional circulation flow enhanced heat exchange device, characterized in that: The invention comprises a boiling heating device, a forward and reverse circulation system, a visual experiment section (1) and a monitoring system; the boiling heating device is used to heat the working medium in the visual experiment section (1) to a boiling state; particles are arranged in the visual experiment section (1), and a filtering device is arranged at the inlet and outlet of the visual experiment section (1) to prevent particles from escaping; an observation device is arranged outside the visual experiment section (1) to observe the three-phase flow behavior of vapor-liquid-particles in the boiling process in the experiment section; the forward and reverse circulation system is connected to the visual experiment section (1), so that the working medium drives the particles in a directional flow channel of the visual experiment section (1); The monitoring system determines the boiling heat transfer efficiency of the particle-containing working medium according to the temperature change of the surface of the boiling heating device in contact with the visualization experimental section (1).

2. The particle flow boiling bidirectional circulation flow enhanced heat exchange device according to claim 1 is characterized in that: The boiling heating device comprises a heating block (21), a thermocouple (17) and a heating rod (18); a plurality of heating rods (18) are symmetrically arranged on the heating block (21) for heating the heating block (21); the heating block (21) is in contact with the visualization experiment section (1); the contact surface between the heating block (21) and the visualization experiment section (1) is provided with array-distributed thermocouples (17); and the monitoring system obtains the measurement value of the thermocouple (17).

3. The particle flow boiling bidirectional circulation flow enhanced heat exchange device according to claim 1 is characterized in that: The contact surface of the heating block (21) is divided into several layers of measuring surfaces, and each layer of measuring surface is provided with array-distributed thermocouples (17) for calculating the heat flux density inside the heating copper block.

4. The particle flow boiling bidirectional circulation flow enhanced heat exchange device according to claim 1, characterized in that: The forward and reverse circulation system comprises a first self-priming pump (12), a second self-priming pump (13), a liquid storage tank (6), a diaphragm accumulator (11) and a heat exchanger (7); the inlet and outlet of the first self-priming pump (12) are connected in parallel with the outlet and inlet of the second self-priming pump (13); the first self-priming pump (12) is sequentially connected with the diaphragm accumulator (11), the heat exchanger (7), the liquid storage tank (6) and the visual experimental section (1) to form a closed-loop system; the diaphragm accumulator (11) is used to reduce pressure fluctuations of the closed-loop system during three-phase flow; and the heat exchanger (7) is used to change the temperature of the working fluid in the closed-loop system.

5. The particle flow boiling bidirectional circulation flow enhanced heat exchange device according to claim 4 is characterized in that: The monitoring system further comprises a turbine flowmeter (14), a pressure sensor (15) and a temperature sensor (16); the closed-loop system is provided with a turbine flowmeter (14) for measuring the flow of the closed-loop system; the inlet and outlet of the visualization experiment section (1) are respectively provided with a pressure sensor (15) and a temperature sensor (16).

6. The particle flow boiling bidirectional circulation flow enhanced heat exchange device according to claim 1, characterized in that: The visualization experiment section (1) comprises a transparent pipe, a particle adding section and a particle recovery section; a first filter screen (24) and a second filter screen (29) are respectively provided at both ends of the transparent pipe, and a particle adding section is provided between the first filter screen (24) and one end of the transparent pipe for adding particles; a four-way interface is provided between the second filter screen (29) and the other end of the transparent pipe, and a particle recovery section is provided on one side of the four-way interface for recovering particles; the other side of the four-way interface is connected to the first filter screen (24) and the particle adding section through a particle circulation pipeline.

7. The particle flow boiling bidirectional circulation flow enhanced heat exchange device according to claim 6, characterized in that: The visualization experiment section (1) also includes a second needle valve (25), a first check valve (26), a second check valve (27), a third needle valve (30) and a fourth needle valve (31); a fourth needle valve (31) is provided between the other end of the transparent pipe and the four-way interface, and a second check valve (27) is installed on one side of the second filter (29); a third needle valve (30) is provided between the particle recovery section and one side of the four-way interface; a second needle valve (25) is provided between the first filter (24) and the particle addition section; and a first check valve (26) is installed on the particle circulation pipeline.

8. The particle flow boiling bidirectional circulation flow enhanced heat exchange device according to claim 7, characterized in that: The third needle valve (30) is controlled to be closed and the second needle valve (25) is controlled to be open, so that the particles circulate between the transparent pipe and the particle circulation pipeline.

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