Visualize ultra-thin flat plate heat pipe flow resistance experiment table and experimental method

Abstract

The application discloses a visual ultra-thin flat-plate heat pipe flow resistance experiment table and an experiment method thereof, and relates to the fields of pressure measurement and flat-plate heat pipe technology. The experiment table comprises an experiment table body, a high-speed camera, a front-end pressure gauge, a rear-end pressure gauge and an electric heating film. The experiment table body comprises a top plate, an upper cover plate and a base plate. The upper cover plate is made of quartz glass and is etched with a support column structure below. The electric heating film is fixedly arranged below the base plate and is used for heating the middle test cavity. The front-end pressure gauge and the rear-end pressure gauge are used for measuring the pressures on the front and rear sides of the middle test cavity respectively. The support column and the wire mesh wick can be used for observing and studying the liquid capillary force reconstruction phenomenon. The verification and correction of the steam flow resistance relationship of the ultra-thin flat-plate heat pipe in the actual working condition can be realized, and the method has important practical significance and technical development significance for optimizing the design of the ultra-thin flat-plate heat pipe.

Description

Technical Field

[0001] This invention relates to the fields of pressure measurement and flat plate heat pipe technology, specifically to a visual ultrathin flat plate heat pipe flow resistance test bench and experimental method. Background Technology

[0002] Currently, the rapid development of microelectronics technology has injected new vitality into the development of high-performance electronic devices. Chip manufacturing processes have been optimized from 15nm to 4nm, resulting in smaller transistor sizes, increased density, and further increased heat flux density. Poor temperature control not only affects chip performance but also increases chip power consumption, thus impacting the overall performance of the electronic device. The increasing heat generation power and decreasing size of electronic devices necessitate innovation and development in thermal management technologies. Ultra-thin flat heat pipes, with their advantages of small size, light weight, thinness, and variable shape, have become an important solution for heat dissipation in electronic devices.

[0003] Considering strength issues, the number of support columns increases dramatically as the thickness decreases. The capillary effect of the support columns on the liquid is very significant, and this phenomenon needs to be studied. Meanwhile, because the vapor inside the heat pipe is saturated, the pressure drop and temperature drop caused by the saturated vapor flowing from the evaporation section to the condensation section are very small, making it difficult to measure the minute internal pressure difference using existing pressure measuring mechanisms.

[0004] Chinese invention patent application number CN114210382 A discloses a flow resistance test platform for an ultrathin flat plate heat pipe with adjustable cavity height. However, the experimental environment described in this patent is not the working environment of the heat pipe. It can only study the influence of the wire mesh structure on the vapor pressure drop, but it does not address the influence of the numerous support structures inside the ultrathin flat plate heat pipe. Furthermore, it cannot be improved without changing the test platform itself. In addition, the structure in this patent cannot add liquid to the bottom, meaning that it is impossible to study the liquid distribution, capillary remodeling phenomenon, and the influence of the liquid on the vapor pressure drop under the working conditions of the ultrathin flat plate heat pipe without changing the test platform itself. Summary of the Invention

[0005] To address the above problems, this invention proposes a visual ultrathin flat plate heat pipe flow resistance test bench, which can accurately simulate and measure the influence of the support column and liquid wick on capillary force reconstruction under the operating conditions of the ultrathin flat plate heat pipe, and can also measure the vapor pressure drop under the influence of the support column and the bottom liquid, providing a theoretical basis for numerical simulation.

[0006] The technical solution of this invention is as follows:

[0007] A visualization-based ultrathin flat heat pipe flow resistance test bench includes a test bench body, a high-speed camera, a front-end pressure gauge, a rear-end pressure gauge, and an electric heating film. The test bench body includes a top plate, a top cover plate, and a base plate. The top plate is hollow and detachably connected to the base plate. The upper surface of the top cover plate contacts the top plate, and the bottom surface of the top cover plate is etched with support columns. The support columns contact a liquid-absorbing core plate below to fix the liquid-absorbing core plate. A liquid-absorbing core placement groove is formed on the top surface of the base plate for placing the liquid-absorbing core plate. The liquid-absorbing core plate is placed in the liquid-absorbing core placement groove, and an intermediate test cavity is formed between the liquid-absorbing core plate and the top cover plate with etched support columns. A steam inlet is provided at the front of the base plate, and a steam inlet is provided at the rear of the base plate. The steam outlet cavity, steam inlet cavity, intermediate test cavity, and steam outlet cavity are all located below the upper cover plate. The upper cover plate has pressure gauge mounting threaded holes on its front and rear sides. The front and rear pressure gauges extend into these two threaded holes to measure the pressure on the front and rear sides of the intermediate test cavity. A portion of the electric heating film is fixed below the substrate, heating the substrate portion of the intermediate test cavity. The other portion is a transparent heating film attached to the upper surface of the upper cover plate to heat it. This design allows for better temperature control of the intermediate test cavity and prevents steam condensation on the upper cover plate, which would affect the study of capillary force reconstruction phenomena.

[0008] The high-speed camera is fixed above the experimental platform and is used to photograph the distribution of liquid around the support column.

[0009] Preferably, the wire mesh absorbent core and the bottom copper sheet constitute the absorbent core plate; the bottom surface of the upper cover plate is etched with support columns to restore the real internal structure of the ultra-thin flat heat pipe; the support columns fix the absorbent core plate in the absorbent core placement groove above the substrate; water or other liquid working fluid can be added above the absorbent core plate to simulate the real working conditions inside the ultra-thin flat heat pipe.

[0010] Preferably, the bottom surface of the top plate is provided with an annular upper gasket groove, and the top surface of the substrate is provided with an annular lower gasket groove. The upper gasket groove is located directly above the lower gasket groove, and an annular silicone sealing ring is provided between the two. The steam inlet chamber, the intermediate test chamber, and the steam outlet chamber are all located inside the silicone sealing ring.

[0011] Preferably, the upper cover plate and the upper cover plate mounting groove located on the top plate are sealed with glass glue.

[0012] Preferably, the bottom surface of the upper cover plate, the etched support pillars, the wire mesh liquid-absorbing core, and the bottom copper sheet are all surface modified to make their surface contact angles consistent.

[0013] Preferably, the upper cover plate is structurally independent of the top plate, making it easy to disassemble and replace. This allows for changes in the height of the support columns etched on the lower surface of the upper cover plate, thereby altering the height of the intermediate test chamber and facilitating the study of the influence of the support column arrangement and height.

[0014] Preferably, the top plate has multiple upper positioning holes and multiple upper fastening threaded holes, and the base plate has multiple lower positioning holes and multiple lower fastening threaded holes; the upper positioning holes and lower positioning holes correspond one-to-one, and the upper fastening threaded holes and lower fastening threaded holes correspond one-to-one; the experimental platform body also includes multiple positioning pins that simultaneously pass through the upper positioning holes and lower positioning holes, and multiple fastening bolts that simultaneously threadedly connect the upper fastening threaded holes and lower fastening threaded holes.

[0015] Preferably, the upper cover plate is provided with pressure gauge mounting threaded holes on the front and rear sides respectively, and the front pressure gauge and the rear pressure gauge are respectively inserted into the two pressure gauge mounting threaded holes to measure the pressure on the front and rear sides of the middle test chamber respectively.

[0016] This invention also discloses an experimental method for a visual ultrathin flat plate heat pipe flow resistance experimental stage, comprising the following steps: Step 1, setting up the experimental setup: placing the upper cover plate in the upper cover plate mounting groove of the top plate, and sealing the two together with glass glue; placing the absorbent core plate in the absorbent core placement groove of the substrate, and adding calculated water or other liquid working fluid to the wire mesh absorbent core; connecting the top plate and the upper cover plate together with the substrate via fastening threads, and firmly fixing the absorbent core plate between the upper cover plate and the substrate via the support column below the upper cover plate; the experimental stage body is connected via a front connection... The steam generation system and flow regulation system provide steam to the test bench body, and the pressure of the steam chamber inside the test bench is controlled by the negative pressure system connected at the rear; Step 2: Before the experiment, the experimental system and the test bench body should be sealed; Step 3: At the beginning of the experiment, the heating film is used to heat the substrate and the top cover plate to make them reach the working temperature of the ultra-thin flat plate heat pipe; During the experiment, the pressure drop of steam passing through the test section is measured by two negative pressure transmitters installed before and after the top cover plate, and the influence of the support column structure on the capillary force reconstruction phenomenon is recorded by a high-speed camera fixed above.

[0017] Beneficial effects

[0018] (1) Based on the experimental platform disclosed in this invention, it is possible to clearly observe and record the influence of the large number of support structures inside the ultrathin flat plate heat pipe on the capillary suction effect of the liquid, and to measure the pressure difference in the vapor chamber of the ultrathin flat plate heat pipe more accurately, thus providing a theoretical basis for numerical simulation.

[0019] (2) Based on the experimental platform disclosed in this invention, it is possible to verify and correct the vapor flow resistance relationship of ultrathin flat plate heat pipe, and to optimize the size arrangement of the internal support structure of ultrathin flat plate heat pipe, which has important practical significance and technological development significance.

[0020] (3) Based on the experimental platform disclosed in this invention, the internal structure of the ultrathin flat plate heat pipe can be completely restored, and the influence of each parameter on the vapor pressure drop can be studied.

[0021] (4) Based on the experimental platform disclosed in this invention, it is possible to conduct experimental research on the liquid capillary force reconstruction phenomenon of the composite structure of support column and liquid core, and guide the simplification of the simulation model of gas-liquid two-phase flow inside ultrathin flat plate heat pipe.

[0022] (5) Based on the experimental platform disclosed in this invention, the effect of the support column structure and the amount of filling on the vapor flow resistance inside the ultrathin flat plate heat pipe can be studied, the simulation results can be verified, and the optimization design of the support column arrangement and size can be guided. This is of great significance for the study of vapor flow resistance of ultrathin flat plate heat pipe. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the present invention.

[0024] Figure 2 yes Figure 1 Left view,

[0025] Figure 3 yes Figure 2 This is a sectional view along the DD direction.

[0026] Figure 4 yes Figure 1 Sectional view along line AA,

[0027] Figure 5 This is the orthogonal triaxial projection of the present invention.

[0028] Figure 6 This is a top view of the top plate in this invention.

[0029] Figure 7 This is a bottom view of the top plate in this invention.

[0030] Figure 8 This is a bottom view of the upper cover plate in this invention.

[0031] Figure 9 This is a top view of the substrate in this invention.

[0032] In the figure, 1 is the top plate, 11 is the upper positioning hole, 12 is the upper fastening threaded hole, 13 is the upper gasket groove, and 14 is the upper cover plate mounting groove; 2 is the upper cover plate, 21 is the pressure gauge mounting threaded hole, and 22 is the support column; 3 is the liquid suction core plate, 31 is the wire mesh liquid suction core, and 32 is the bottom copper sheet; 4 is the base plate, 41 is the lower positioning hole, 42 is the lower fastening threaded hole, 43 is the lower gasket groove, and 44 is the liquid suction core placement groove. Detailed Implementation

[0033] To clearly illustrate the technical features of this patent, the following detailed description is provided through specific embodiments and in conjunction with the accompanying drawings.

[0034] As attached Figure 1-9 As shown, the pressure drop test bench consists of four parts: top plate 1, upper cover plate 2, liquid absorption core plate 3, and base plate 4. All threaded holes use national standard thread dimensions. (See attached image) Figure 1 As shown, positioning holes 11 are provided diagonally, and fastening threaded holes 12 are provided along the length direction, with a size of M6. To ensure the airtightness of the device and prevent steam leakage, an upper gasket groove 13, 4mm wide and 1.5mm high, is laser-etched on the lower surface of the top plate.

[0035] To clearly observe the influence of the support column structure on the capillary force reconstruction of the liquid, the upper cover plate 2 is made of quartz glass and has a transparent electric heating film attached to it to prevent steam condensation. A pressure gauge mounting threaded hole 21 with a D15 internal thread is arranged on the upper cover plate 2. A cavity with a depth of 0.8 mm and 1 mm high, 4 mm diameter support columns 22 is laser-etched on the lower surface of the upper cover plate 2, and the surface is modified to make its surface contact angle the same as that of the wire mesh and copper sheet. A cavity with a depth of 0.5 mm is milled at the center of the middle substrate of the top plate using a CNC machine tool to serve as a liquid suction core placement groove 44. A silicone sealing ring groove with a width of 4 mm and a height of 1.5 mm is milled between the cavity and the threaded hole. The top plate and the substrate are connected by bolts. A liquid suction core plate 3, consisting of a surface-modified wire mesh liquid suction core 31 and a 0.2 mm thick bottom copper sheet 32, is placed at the bottom of the liquid suction core placement groove 44, and water is added on top. Above the liquid-absorbing core plate 3 is the steam chamber space for steam flow. The liquid-absorbing core plate 3 is manufactured by pressing the modified wire mesh liquid-absorbing core 31 and the bottom copper sheet 32 ​​together using a hot press. The overall thickness of the liquid-absorbing core test piece is 0.3 mm.

[0036] The height of the internal vapor chamber is adjusted by changing the cavity depth of the upper cover plate 2 and the height of the support column 22. The influence of the number and arrangement of the support columns 22 on the capillary force reconstruction of the ultra-thin flat plate heat pipe support columns is also observed by changing the number and arrangement of the support columns 22 on the upper cover plate 2. To ensure airtightness and prevent vapor leakage in the pressure drop test bench, a silicone sealing ring is used between the top plate 1 and the base plate 4, and glass glue is used to seal between the upper cover plate mounting groove 14 of the top plate 1 and the upper cover plate 2. In addition to the fixing threads, the relatively high atmospheric pressure during vacuuming also compresses the upper and lower plates, ensuring the airtightness of the test bench.

[0037] To achieve a good airtight seal, the thickness of the sealing ring should be slightly greater than the total thickness of the upper and lower sealing ring grooves, and the width should be slightly less than the width of the sealing ring grooves. A silicone sealing ring with a thickness of 4mm and a width of 3mm was obtained by laser cutting on a rectangular silicone sheet.

[0038] The substrate 4 is divided into three parts: a steam inlet section, an intermediate testing section, and a steam outlet section. Positioning holes 41 are provided diagonally on the substrate 4, and fastening threaded holes 42, with a size of M6, are provided around the perimeter. A gasket groove 43, 4mm wide and 1.5mm high, is cut into the substrate 4. When the system is evacuated, atmospheric pressure presses the top plate 1, the upper cover plate 2, and the substrate 4 together. A liquid-absorbing core placement groove 44, 40mm wide and 0.5mm high, is cut into the intermediate testing section.

[0039] This invention also discloses an experimental method for a visual ultrathin flat plate heat pipe flow resistance test bench, comprising the following steps: Step 1, setting up the experimental facilities: placing the upper cover plate 2 in the upper cover plate mounting groove 14 of the top plate 1, and sealing the two with glass glue; placing the liquid absorption core plate 3 in the liquid absorption core placement groove 44 of the substrate 4, and adding calculated water or other liquid working fluid to the wire mesh liquid absorption core; connecting the top plate 1 and the upper cover plate 2 together with the substrate 4 by fastening threads, and firmly fixing the liquid absorption core plate 3 between the upper cover plate and the substrate by the support column below the upper cover plate 2; the test bench body provides steam to the test bench body through a steam generation system and a flow regulation system connected to the front, and controls the pressure of the steam chamber inside the test bench through a negative pressure system connected to the rear;

[0040] Step 2: Before the experiment begins, a sealing test should be performed on the experimental system and the experimental platform itself.

[0041] Step 3: At the beginning of the experiment, the heating film is used to heat the substrate 4 and the top cover plate 2 to reach the working temperature of the ultra-thin flat plate heat pipe. During the experiment, two negative pressure transmitters installed before and after the top cover plate are used to measure the pressure drop of steam passing through the test section. A high-speed camera fixed above is used to record the effect of the support column structure on the capillary force reconstruction phenomenon.

[0042] This invention can be used to measure vapor pressure drop under the operating conditions of ultrathin flat plate heat pipes, and to observe and study the phenomenon of liquid capillary force reconstruction caused by the support column and wire mesh wick structure. It provides a more realistic reconstruction of the internal conditions of ultrathin flat plate heat pipes during operation, and considers the influence of important factors such as the support column and bottom liquid in the study of vapor flow resistance of ultrathin flat plate heat pipes. It can more accurately measure the vapor chamber pressure drop of ultrathin flat plate heat pipes with smaller heights. In the example, the vapor chamber height measured is 1.2 mm, and by replacing the upper cover plate 2, the vapor chamber height measurement can be achieved to 0.5 mm, providing a theoretical basis for numerical simulation.

[0043] There are many specific ways to implement this invention. The above description is only a preferred embodiment of this invention. It should be noted that for those skilled in the art, several improvements can be made without departing from the principle of this invention, and these improvements should also be considered within the scope of protection of this invention.

Claims

1. A visual ultrathin flat plate heat pipe flow resistance experimental stage, characterized in that, It includes the experimental platform body, high-speed camera, front pressure gauge, rear pressure gauge, and electric heating film; The experimental platform has a three-layer structure, consisting of a top plate (1), an upper cover plate (2), and a base plate (4) from top to bottom. The top plate (1) is hollow and detachably connected to the base plate (4). The upper surface of the upper cover plate (2) is in contact with the top plate. The bottom surface of the upper cover plate (2) is etched with a support column (22). The support column (22) is in contact with the liquid absorption core plate (3) below to fix the liquid absorption core plate (3). The top surface of the base plate (4) is provided with a liquid absorption core placement groove (44) for placing the liquid absorption core plate (3). The liquid absorption core plate (3) is placed in the liquid absorption core placement groove (44). An intermediate test chamber is formed between the liquid absorption core plate (3) and the upper cover plate (2). The front and rear parts of the base plate (4) are respectively provided with a steam inlet chamber and a steam outlet chamber. The steam inlet chamber, the intermediate test chamber, and the steam outlet chamber are all located below the upper cover plate (2). The upper cover plate (2) is equipped with pressure gauges on both the front and rear sides, which can measure the pressure on both the front and rear sides of the middle test chamber; One part of the electric heating film is fixedly disposed below the substrate (4) and the substrate part of the middle test cavity is heated by the electric heating film. The other part is a transparent heating film, which is attached to the upper surface of the upper cover plate (2) to heat the upper cover plate (2). The high-speed camera is fixed above the experimental platform and is used to photograph the distribution of liquid around the support column.

2. The visual ultrathin flat plate heat pipe flow resistance experimental stage according to claim 1, characterized in that, The wicking core (31) and the bottom copper sheet (32) constitute the wicking core plate (3); the bottom surface of the upper cover plate (2) is etched with support columns (22) to restore the real internal structure of the ultra-thin flat heat pipe; the support columns (22) fix the wicking core plate (3) in the wicking core placement groove (44) above the substrate (4); water is added above the wicking core plate to simulate the real working conditions inside the ultra-thin flat heat pipe.

3. The visual ultrathin flat plate heat pipe flow resistance experimental stage according to claim 2, characterized in that, The structure of the upper cover plate (2) is independent of the top plate (1), which makes it easy to disassemble and replace, and facilitates the study of the influence of the arrangement and height of the support columns, thereby changing the height of the intermediate test cavity.

4. The visual ultrathin flat plate heat pipe flow resistance experimental stage according to claim 3, characterized in that, The bottom surface of the top plate (1) is provided with an annular upper gasket groove (13), and the top surface of the substrate (4) is provided with an annular lower gasket groove (43). The upper gasket groove (13) is located directly above the lower gasket groove (43), and an annular silicone sealing ring is provided between the two. The steam inlet chamber, the intermediate test chamber, and the steam outlet chamber are all located inside the silicone sealing ring.

5. The visual ultrathin flat plate heat pipe flow resistance experimental stage according to claim 4, characterized in that, The upper cover plate (2) and the upper cover plate mounting groove located on the top plate (1) are sealed with glass glue.

6. The visual ultrathin flat plate heat pipe flow resistance experimental stage according to claim 5, characterized in that, The bottom surface of the upper cover plate (2), the etched support column (22), the wire mesh liquid absorption core (31), and the bottom copper sheet (32) are all surface modified to make their surface contact angles consistent.

7. The visual ultrathin flat plate heat pipe flow resistance experimental stage according to claim 6, characterized in that, The top plate (1) is provided with multiple upper positioning holes (11) and multiple upper fastening threaded holes (12), and the base plate (4) is provided with multiple lower positioning holes (41) and multiple lower fastening threaded holes (42); the upper positioning holes (11) and the lower positioning holes (41) correspond one-to-one, and the upper fastening threaded holes (12) and the lower fastening threaded holes (42) correspond one-to-one; the experimental platform body also includes multiple positioning pins that simultaneously penetrate the upper positioning holes (11) and the lower positioning holes (41) and multiple fastening bolts that simultaneously thread the upper fastening threaded holes (12) and the lower fastening threaded holes (42).

8. The visual ultrathin flat plate heat pipe flow resistance experimental stage according to claim 7, characterized in that, The upper cover plate (2) is provided with pressure gauge mounting threaded holes (21) on the front and rear sides respectively. The front pressure gauge and the rear pressure gauge are respectively inserted into the two pressure gauge mounting threaded holes (21) to measure the pressure on the front and rear sides of the middle test chamber respectively.

9. An experimental method for a visual ultrathin flat plate heat pipe flow resistance experimental stage, characterized in that, The experimental method is the working method of the flow resistance test bench as described in claim 1, specifically including the following steps: Step 1, set up the experimental setup: Place the top cover plate (2) in the top cover plate mounting groove (14) of the top plate (1), and seal the two with glass glue; place the liquid absorption core plate (3) in the liquid absorption core placement groove (44) of the base plate (4), and add calculated water or other liquid working medium to the wire mesh liquid absorption core; connect the whole consisting of the top plate (1) and the top cover plate (2) to the base plate (4) with fastening threads, and firmly fix the liquid absorption core plate (3) between the top cover plate and the base plate through the support column below the top cover plate (2); the experimental platform body provides steam to the experimental platform body through the steam generation system and flow regulation system connected in front, and controls the pressure of the steam chamber inside the experimental platform through the negative pressure system connected in the rear; Step 2: Before the experiment begins, a sealing test should be performed on the experimental system and the experimental platform itself. Step 3: At the beginning of the experiment, the heating film is used to heat the substrate (4) and the top cover plate (2) to reach the working temperature of the ultra-thin flat plate heat pipe. During the experiment, the pressure drop of steam passing through the test section is measured by two negative pressure transmitters installed before and after the top cover plate, and the influence of the support column structure on the capillary force reconstruction phenomenon is recorded by a high-speed camera fixed above.

Images