Pulsating heat pipe capable of dynamically regulating and controlling liquid filling rate and working method of pulsating heat pipe

Abstract

The invention discloses a pulsating heat pipe capable of dynamically adjusting and controlling the liquid filling rate and a working method thereof.The pulsating heat pipe comprises a pipe body and a liquid amount adjusting unit, the pipe body comprises an evaporation section, a condensation section and a heat insulation section, the evaporation section and the condensation section are each provided with a sawtooth pipe structure, and the edge of the axial section of each sawtooth pipe structure is in a sawtooth shape; the pipe body is filled with working media, the condensation section is connected with the liquid amount adjusting unit, the liquid amount adjusting unit comprises a control module, a liquid storage device, a fluid conveying device and a valve, and the working media are controlled to enter and exit between the pipe body and the liquid storage device through the fluid conveying device and the valve. The gradually-expanding structure of the evaporation section is beneficial for increasing the fluid contact area and enhancing the heat transfer performance; the gradually-shrunk structure of the condensation section is beneficial for improving the condensation efficiency and enhancing the liquid backflow capacity; and the liquid volume adjusting unit can dynamically adjust the liquid filling rate. Through the design, the starting performance, the heat transfer efficiency and the fluid circulation stability of the pulsating heat pipe are remarkably improved, and the pulsating heat pipe is suitable for an efficient heat management system.

Description

Technical Field

[0001] The present invention relates to the field of enhanced heat transfer elements, and particularly to a pulsating heat pipe with dynamically adjustable liquid filling rate and its working method. Background Art

[0002] As Figure 1 shown, a conventional pulsating heat pipe generally consists of a slender pipe bent into multiple U-shaped or serpentine loops, with an appropriate amount of working liquid partially filled inside. When the heating end (evaporation section) is heated, the liquid inside starts to evaporate into steam. Due to the increasing pressure of the steam, it pushes the steam to move towards the cooling end (condensation section). At the condensation section, the steam condenses into liquid and may form liquid plugs. These liquid plugs and bubbles reciprocate in the pipe, forming a pulsating effect, thereby achieving efficient heat transfer. Compared with traditional heat pipes, pulsating heat pipes have the advantages of simple structure, low cost, high heat transfer efficiency, etc., and thus have received increasing attention in the field of heat dissipation technology.

[0003] However, there are still many problems with current pulsating heat pipes, such as difficult startup, insufficient heat transfer performance, poor system stability, etc. Traditional pulsating heat pipes mostly adopt a pipe structure with a fixed diameter and a fixed liquid filling rate. In different application scenarios, the design of a pipe structure with a fixed diameter and a fixed liquid filling rate cannot fully meet the requirements for optimizing the performance of the heat pipe. Especially under variable working conditions, the fixed liquid filling rate is prone to problems of limited heat transfer limit. Therefore, how to optimize the internal geometry of the pulsating heat pipe and adjust the liquid filling rate to promote more efficient flow and heat transfer has become an important direction for improving its performance. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art, and provide a pulsating heat pipe with dynamically adjustable liquid filling rate, which is mainly used for the heat dissipation of electronic devices and battery thermal management, and can significantly improve the startup performance, heat transfer efficiency and fluid circulation stability.

[0005] Another purpose of the present invention is to provide a working method for a pulsating heat pipe with dynamically adjustable liquid filling rate, which can dynamically adjust the liquid filling rate according to the working state of the heat pipe, thereby improving the thermal efficiency.

[0006] To achieve the above purposes, the present invention adopts the following technical solutions:

[0007] A pulsating heat pipe with dynamically adjustable liquid filling rate, comprising a pipe body and a liquid volume regulating unit. The pipe body includes an evaporation section, a condensation section, and an adiabatic section. Both the evaporation section and the condensation section are provided with a serrated pipe structure, and the edge of the axial cross-section of the serrated pipe structure is serrated. The pipe body is filled with a working medium. The condensation section is connected to the liquid volume regulating unit. The liquid volume regulating unit includes a control module, a liquid storage device, a fluid delivery device, and a valve. The liquid storage device is used to store excess working medium. The control module is electrically connected to the fluid delivery device and the valve, and controls the entry and exit of the working medium between the pipe body and the liquid storage device through the fluid delivery device and the valve.

[0008] As a preference, along the vapor diffusion direction of the pipe body axis, the serrated pipe structure is in an overall gradually expanding shape in the evaporation section and in an overall gradually contracting shape in the condensation section.

[0009] As a preference, the liquid storage device is a liquid storage tank. The condensation section is connected to the liquid storage tank through a direct connection pipe. The valve is an electromagnetic valve installed on the direct connection pipe. The height of the condensation section of the pipe body is higher than that of the evaporation section, and the installation height of the liquid storage tank is higher than that of the condensation section. The fluid delivery device is a micro diaphragm pump installed between the condensation section and the liquid storage tank, and is used to pump part of the liquid working medium in the condensation section into the liquid storage tank.

[0010] As a preference, the liquid storage tank is filled with a porous liquid absorption core. The condensation section also includes a main circuit at the highest position. The porous liquid absorption core extends from the liquid storage tank through the direct connection pipe to the interface of the main circuit. When the electromagnetic valve is opened, the liquid working medium in the liquid storage tank flows into the condensation section under the action of gravity and capillary force. When the electromagnetic valve is closed, the flow channel of the working medium in the direct connection pipe is blocked.

[0011] As a preference, the air extraction port of the micro diaphragm pump is connected to the condensation section through a first pipe, and the exhaust port of the micro diaphragm pump is connected to the inside of the liquid storage tank through a second pipe. An air-liquid separator is installed on the first pipe.

[0012] As a preference, the adiabatic section is a constant inner diameter pipe structure. The evaporation section also includes a first inlet pipe section and a first outlet pipe section. The larger end of the serrated pipe structure of the evaporation section is connected to the adiabatic section through the first outlet pipe section, and the smaller end of the serrated pipe structure of the evaporation section is connected to the first inlet pipe section. The condensation section also includes a second inlet pipe section and a second outlet pipe section. The larger end of the serrated pipe structure of the condensation section is connected to the adiabatic section through the second inlet pipe section, and the smaller end of the serrated pipe structure of the condensation section is connected to the second outlet pipe section. The first inlet pipe section, the first outlet pipe section, the second inlet pipe section, and the second outlet pipe section are all constant inner diameter pipe structures. The inner diameters of the first outlet pipe section and the second inlet pipe section are the same as that of the adiabatic section, and the inner diameter ratio of the first outlet pipe section to the first inlet pipe section is 5:4.

[0013] As a preference, the total pipe length ratio of the evaporation section to the condensation section is 1:(0.6 - 1).

[0014] As a preference, in the serrated tube structure, the cross-section of a single serration is an isosceles right triangle. Along the vapor diffusion direction of the tube body axis, the size of the serrations gradually increases in the evaporation section and gradually decreases in the condensation section.

[0015] In the above working method of the pulsating heat pipe for dynamically regulating the liquid filling rate, the control module includes a temperature sensor, and the temperature sensor is used to detect the temperature of the tube body;

[0016] When the control module detects that the temperature of the condensation section is higher than the set value, it drives the solenoid valve to open, and the liquid working medium in the liquid storage tank flows into the main circuit to achieve liquid filling;

[0017] When the control module detects that the temperature is lower than the set value, it closes the solenoid valve and starts the micro diaphragm pump, and uses the pressure difference to pump part of the liquid working medium in the condensation section to the liquid storage tank to complete the recovery of the working medium.

[0018] As a preference, the control module further includes a pressure sensor. The pressure sensor is used to monitor the pressure of the liquid storage tank and the condensation section in real time, and adopts a PID algorithm to dynamically adjust the pumping rate of the micro diaphragm pump, so that the pressure fluctuation in the tube body is within a controllable range.

[0019] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0020] 1. The design of the serrated shape can effectively increase the effective heat exchange area of the evaporation section. During the liquid evaporation process, a larger heat exchange area helps to improve the heat load bearing capacity of the heat pipe, thereby enhancing the overall heat transfer efficiency of the heat pipe.

[0021] 2. The serrated gradually expanding structure improves the fluidity of the working liquid in the evaporation section by increasing the turbulence degree of the local fluid. The generation of turbulence helps to promote more uniform heat transfer, reduces the residence time of the liquid during the heat transfer process, and improves the heat exchange rate.

[0022] 3. The serrated gradually expanding structure in the evaporation section can gradually increase the flow channel width, reduce the local flow resistance, avoid the increase in flow resistance caused by the rapidly changing flow channel in the traditional straight tube gradual change structure, and reduce the energy loss of the system.

[0023] 4. The serrated gradually shrinking structure in the condensation section enables the liquid to gradually gather in the condensation section, and guides the liquid to flow smoothly through the gradually shrinking structure, avoiding the formation of too much liquid film due to liquid retention, resulting in insufficient condensation. And adding the serrated structure effectively improves the problem of insufficient driving force, promotes the rapid reflux of the working medium, and thus optimizes the flow pattern distribution in the pulsating heat pipe.

[0024] 5. The control module can automatically and dynamically adjust the liquid filling rate according to different working conditions, breaking the problem that traditional pulsating heat pipes need manual adjustment, and is more simple and efficient.

[0025] 6. The self - adaptive regulation of the liquid filling rate can improve the problem that the liquid filling rate of the traditional pulsating heat pipe is fixed, which is prone to limit the heat transfer limit under variable working conditions. It can adaptively match the heat load, dynamically regulate to supplement the working medium at high temperature and recover the working medium at low temperature, and always maintain the optimal working medium distribution. Brief Description of the Drawings

[0026] Figure 1 Schematic diagram of the structure of the pulsating heat pipe of the prior art provided by the present invention;

[0027] Figure 2 Schematic diagram of the structure of the pulsating heat pipe for dynamically regulating the liquid filling rate provided by the present invention;

[0028] Figure 3 Partial three - dimensional model diagram of the pulsating heat pipe for dynamically regulating the liquid filling rate provided by the present invention, which contains a serrated tube structure;

[0029] The brief description of the drawings is as follows: 1 is the condensation zone, 2 is the adiabatic section, 3 is the evaporation zone, 4 is the liquid storage tank, 5 is the solenoid valve, 6 is the micro diaphragm pump, 7 is the serrated tube structure, 8 is the first inlet pipe section, 9 is the first outlet pipe section, 10 is the second inlet pipe section, 11 is the second outlet pipe section, 12 is the main loop, and 13 is the direct - connection pipeline.

[0030] The direction indicated by the arrow is the heat transfer direction. Detailed Embodiment

[0031] In order to more clearly understand the above - mentioned objects, features and advantages of the present invention, the present invention will be further described below with reference to the drawings and embodiments. It should be noted that, without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0032] Many specific details are set forth in the following description in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the present invention is not limited by the specific embodiments disclosed in the following specification.

[0033] As Figure 2-3 shown, a pulsating heat pipe for dynamically regulating the liquid filling rate includes a pipe body and a liquid volume regulating unit. The pipe body includes an evaporation section, a condensation section and an adiabatic section. The evaporation section and the condensation section are both provided with a serrated tube structure, and the edge of the axial section of the serrated tube structure is serrated; a working medium is filled in the pipe body, the condensation section is connected to the liquid volume regulating unit, and the liquid volume regulating unit includes a control module, a liquid storage device, a fluid conveying device and a valve. The liquid storage device is used to store the excess working medium, the control module is electrically connected to the fluid conveying device and the valve, and controls the entry and exit of the working medium between the pipe body and the liquid storage device through the fluid conveying device and the valve.

[0034] The tube body is bent into a serpentine shape with the head and tail connected. The two ends with elbows serve as the evaporation section and the condensation section respectively, and the multiple straight tube parts in the middle serve as the adiabatic section. The evaporation section is located in the evaporation area, and the condensation section is located in the condensation area.

[0035] In this embodiment, water is selected as the working medium. During use, the condensation section is placed vertically upward, and the evaporation section is placed vertically downward.

[0036] In some embodiments, along the vapor diffusion direction of the tube body axis, the serrated tube structure is in an overall gradually expanding shape in the evaporation section and in an overall gradually shrinking shape in the condensation section.

[0037] In some embodiments, the liquid storage device is a liquid storage tank. The condensation section is connected to the liquid storage tank through a direct connection pipe. The valve is a solenoid valve installed on the direct connection pipe. The height of the condensation section of the tube body is higher than that of the evaporation section, and the installation height of the liquid storage tank is higher than that of the condensation section; the fluid conveying device is a micro diaphragm pump, and the micro diaphragm pump is installed between the condensation section and the liquid storage tank for sucking a part of the liquid working medium in the condensation section into the liquid storage tank.

[0038] In some embodiments, the liquid storage tank is filled with a porous liquid absorption core. The condensation section further includes a main circuit at the highest position. The porous liquid absorption core extends from the liquid storage tank through the direct connection pipe to the interface of the main circuit. When the solenoid valve is opened, the liquid working medium in the liquid storage tank flows into the condensation section under the action of gravity and capillary force. When the solenoid valve is closed, the working medium flow channel in the direct connection pipe is blocked.

[0039] The porous liquid absorption core is a copper fiber sintered body. The porous liquid absorption core is divided into two sections. One section extends from the liquid storage tank to the inlet of the solenoid valve, and the other section extends from the outlet of the solenoid valve to the interface of the main circuit.

[0040] In some embodiments, the air suction port of the micro diaphragm pump is connected to the condensation section through a first pipe, the air exhaust port of the micro diaphragm pump is connected to the inside of the liquid storage tank through a second pipe, and a gas-liquid separator is installed on the first pipe. The air suction port of the micro diaphragm pump is connected to the main circuit of the condensation section through a first pipe.

[0041] In some embodiments, the adiabatic section is a constant inner diameter tube structure; the evaporation section further includes a first inlet pipe section and a first outlet pipe section. The larger end of the serrated tube structure of the evaporation section is connected to the adiabatic section through the first outlet pipe section, and the smaller end of the serrated tube structure of the evaporation section is connected to the first inlet pipe section; the condensation section further includes a second inlet pipe section and a second outlet pipe section. The larger end of the serrated tube structure of the condensation section is connected to the adiabatic section through the second inlet pipe section, and the smaller end of the serrated tube structure of the condensation section is connected to the second outlet pipe section; the first inlet pipe section, the first outlet pipe section, the second inlet pipe section, and the second outlet pipe section are all constant inner diameter tube structures. The inner diameters of the first outlet pipe section and the second inlet pipe section are the same as that of the adiabatic section, and the inner diameter ratio of the first outlet pipe section to the first inlet pipe section is 5:4.

[0042] The pipe diameter of the sealed pipe is calculated based on the surface tension in different working fluids. The pipe wall is made of copper material. The inner diameter of the first outlet pipe section is 5 mm, and the inner diameter of the first inlet pipe is 4 mm.

[0043] In some embodiments, the total length ratio of the pipes in the evaporation section to the condensation section is 1:(0.6 - 1). The total length of the condensation section is 80 mm, the total length of the evaporation section is 100 mm, and the total length of the adiabatic section is 40 mm. The liquid storage tank pre-stores 15% of the working fluid as a dynamic regulation reserve.

[0044] In some embodiments, in the serrated pipe structure, the cross-section of a single serration is an isosceles right triangle. Along the vapor diffusion direction of the pipe body axis, the size of the serrations gradually increases in the evaporation section and gradually decreases in the condensation section.

[0045] A working method of a pulsating heat pipe for dynamically regulating the liquid filling rate. The control module includes a temperature sensor, which is used to detect the temperature of the pipe body; when the control module detects that the temperature of the condensation section is higher than the set value, it drives the solenoid valve to open, and the liquid working fluid in the liquid storage tank flows into the main circuit to achieve liquid filling; when the control module detects that the temperature is lower than the set value, it closes the solenoid valve and starts the micro diaphragm pump, and uses the pressure difference to pump part of the liquid working fluid in the condensation section to the liquid storage tank to complete the recovery of the working fluid.

[0046] In some embodiments, the control module further includes a pressure sensor, which is used to monitor the pressures of the liquid storage tank and the condensation section in real time, and uses the PID algorithm to dynamically adjust the pumping rate of the micro diaphragm pump to make the pressure fluctuation in the pipe body within a controllable range.

[0047] The startup operation process and working principle of the above pulsating heat pipe for dynamically regulating the liquid filling rate are as follows:

[0048] Step 1: Fill an appropriate amount of working fluid in the sealed pipe and the liquid storage tank. In this embodiment, water is selected as the working fluid, and the working fluid forms an intermittent distribution of gas-liquid plugs under the action of surface tension;

[0049] Step 2: Heat the outside of the evaporation section with a resistance wire to heat up and evaporate the working fluid into steam, increasing the temperature and pressure inside the evaporation section. This process further improves the heat exchange area through the surface design of gradually expanding serrations, with higher evaporation efficiency, thereby increasing the steam pressure difference, promoting the phase change process of the working fluid, and stabilizing the formation of the gas-liquid two-phase flow;

[0050] Step 3: Use a water-cooled heat dissipation device outside the condensation section, where the cooling water absorbs the heat of the steam in the condensation section. The entire process increases the gas-liquid contact area in the evaporation section through the serrated structure, and increases the condensation area in the condensation section. The gradually shrinking serrated structure in the condensation section accelerates the aggregation of the liquid working fluid, enhances the reflux driving force through the gradually shrinking flow channel, and more liquid can condense and quickly flow back to the evaporation section to form a faster cycle;

[0051] Step 4: The control module monitors the temperature of the condensation section in real time through the temperature sensor. Under high-temperature conditions, when it detects that the temperature of the condensation section is greater than the set value, it outputs a signal to drive the solenoid valve to open. The liquid working medium in the liquid storage tank flows into the main circuit through the capillary force and gravity of the wick, realizing liquid filling and improving the liquid filling rate. The flow rate of the liquid working medium is dynamically adjusted by the valve opening. Under low-temperature conditions, when the detected temperature is less than the set value, it outputs a signal to close the solenoid valve to block the replenishment of the working medium, and starts the micro diaphragm pump. Part of the liquid working medium in the condensation section enters the liquid storage tank through the suction force of the pipeline connected to the micro diaphragm pump, reducing the liquid filling rate;

[0052] Step 5: During further heating, due to the addition of the sawtooth structure in the evaporation section, the area for bubble generation is increased, making the bubbly flow more evenly distributed, and the disturbance of the working medium is enhanced, effectively reducing the surface tension and capillary hysteresis resistance, solving the problem of insufficient driving force of the conventional heat pipe, thus significantly accelerating the startup speed of the heat pipe, improving the heat transfer efficiency of the heat pipe and enhancing the system stability. Compared with the traditional pulsating heat pipe, the sawtooth gradient structure enhances the overall heat conduction performance by expanding the formation area of the bubbly flow, ensuring the efficient operation of the heat pipe under different working conditions.

Claims

1. A pulsating heat pipe with dynamically controlled filling rate, characterized in that: It includes a tube body and a liquid volume regulating unit. The tube body includes an evaporation section, a condensation section and an insulation section. The evaporation section and the condensation section are both provided with a sawtooth tube structure. The axial cross-section edge of the sawtooth tube structure is sawtooth-shaped. The tube body is filled with working fluid, and the condensing section is connected to a liquid volume regulating unit. The liquid volume regulating unit includes a control module, a liquid storage device, a fluid conveying device and a valve. The liquid storage device is used to store excess working fluid. The control module is electrically connected to the fluid conveying device and the valve, and controls the flow of working fluid between the tube body and the liquid storage device through the fluid conveying device and the valve.

2. The pulsating heat pipe with dynamically controlled filling rate according to claim 1, characterized in that: Along the axial direction of the tube body in the direction of vapor diffusion, the sawtooth tube structure presents an overall gradually expanding shape in the evaporation section and an overall gradually contracting shape in the condensation section.

3. The pulsating heat pipe with dynamically controlled filling rate according to claim 1, characterized in that: The liquid storage device is a liquid storage tank, the condensing section is connected to the liquid storage tank through a direct-connected pipeline, the valve is a solenoid valve, and is installed on the direct-connected pipeline. The height of the condensing section of the pipe body is higher than that of the evaporating section, and the installation height of the liquid storage tank is higher than that of the condensing section. The fluid conveying device is a micro diaphragm pump, which is installed between the condensation section and the liquid storage tank and is used to pump part of the liquid working medium in the condensation section into the liquid storage tank.

4. The pulsating heat pipe with dynamically controlled filling rate according to claim 3, characterized in that: The liquid storage tank is filled with a porous liquid wick, and the condensation section also includes a main circuit located at the highest point. The porous liquid wick extends from the liquid storage tank through a direct-connected pipeline to the interface of the main circuit. When the solenoid valve is opened, the liquid working fluid in the liquid storage tank flows into the condensation section under the action of gravity and capillary force. When the solenoid valve is closed, the working fluid flow channel in the direct-connected pipeline is blocked.

5. The pulsating heat pipe with dynamically controlled filling rate according to claim 3, characterized in that: The suction port of the micro-diaphragm pump is connected to the condensation section through a first pipeline, the exhaust port of the micro-diaphragm pump is connected to the inside of the liquid storage tank through a second pipeline, and a gas-liquid separator is installed on the first pipeline.

6. The pulsating heat pipe with dynamically controlled filling rate according to claim 2, characterized in that: The insulation section is a constant inner diameter pipe structure; The evaporation section further includes a first inlet pipe section and a first outlet pipe section, the larger end of the sawtooth pipe structure of the evaporation section is connected to the insulation section via the first outlet pipe section, and the smaller end of the sawtooth pipe structure of the evaporation section is connected to the first inlet pipe section; The condensing section further includes a second inlet pipe section and a second outlet pipe section, the larger end of the sawtooth pipe structure of the condensing section is connected to the insulation section via the second inlet pipe section, and the smaller end of the sawtooth pipe structure of the condensing section is connected to the second outlet pipe section; The first inlet pipe section, the first outlet pipe section, the second inlet pipe section and the second outlet pipe section are all constant inner diameter pipe structures. The inner diameters of the first outlet pipe section and the second inlet pipe section are the same as the inner diameter of the insulation section. The inner diameter ratio of the first outlet pipe section to the first inlet pipe section is 5:

4.

7. The pulsating heat pipe with dynamically controlled filling rate according to claim 1, characterized in that: The total length ratio of the pipeline between the evaporation section and the condensation section is 1:(0.6~1).

8. The pulsating heat pipe with dynamically controlled filling rate according to claim 1, characterized in that: In the sawtooth tube structure, the cross section of a single sawtooth is an isosceles right triangle. Along the axial direction of the tube, the size of the sawtooth gradually increases in the evaporation section and gradually decreases in the condensation section.

9. A method for operating a pulsating heat pipe with dynamically controlled filling rate according to any one of claims 3 to 5, characterized in that: The control module includes a temperature sensor, which is used to detect the temperature of the pipe body; When the control module detects that the temperature of the condensing section is higher than the set value, the solenoid valve is driven to open, and the liquid working medium in the liquid storage tank flows into the main circuit to achieve liquid filling; When the control module detects that the temperature is lower than the set value, it closes the solenoid valve and starts the micro diaphragm pump, using the pressure difference to pump part of the liquid working medium in the condensation section to the liquid storage tank to complete the recovery of the working medium.

10. The method for operating a pulsating heat pipe with a dynamic liquid filling rate control according to claim 9, characterized in that: The control module also includes a pressure sensor, which is used to monitor the pressure of the liquid storage tank and the condensation section in real time, and uses a PID algorithm to dynamically adjust the suction rate of the micro diaphragm pump to keep the pressure fluctuation in the tube body within a controllable range.

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