A non-uniform channel array micro-pillar flat plate heat pipe

Abstract

The present application relates to a kind of non-uniform channel array microcolumn flat plate heat pipe, it includes bottom plate and cover plate, the rib is machined on the bottom plate to form several mutually parallel, unequal interval axial channel, a certain width transverse channel is left at one end.Heat pipe is divided into evaporation section and condensing section, evaporation section is axial channel, condensing section is processed on the basis of rib transverse groove and forms the spaced cubic array microcolumn.Cover plate is sealed with bottom plate welding and forms closed cavity, liquid working substance is filled in the cavity, and constitutes non-uniform channel array microcolumn flat plate heat pipe.The non-uniform channel of the flat plate heat pipe reduces liquid backflow resistance, improves the backflow efficiency of working medium, and the array microcolumn of condensing section further increases the contact heat exchange area on the basis of channel, accelerates liquid backflow, and improves heat exchange efficiency.

Description

Technical Field

[0001] This invention belongs to the field of heat pipe technology and relates to a novel flat plate heat pipe, specifically a flat plate heat pipe with non-uniform channels and arrayed micropillars inside. Background Technology

[0002] A heat pipe is a two-phase heat exchange element that can operate spontaneously without external pumping power, and is hailed as a superconductor in the field of heat transfer. With continuous technological advancements, the types of heat pipes have proliferated, gradually evolving into tubular heat pipes, loop heat pipes, and flat plate heat pipes. Among these, flat plate heat pipes, due to their ability to fit tightly against the heating element and achieve efficient heat dissipation within a confined space, have rapidly become a key research focus in the field of heat pipes, as their outstanding thermal performance can simultaneously meet the heat dissipation and packaging requirements of high-power components such as computers and batteries.

[0003] Based on their internal structure, flat plate heat pipes can be divided into two main categories: sintered metal powder heat pipes and channel heat pipes. The manufacturing process of sintered metal powder heat pipes is more complex, and the shedding of internal metal powder can easily cause blockage and failure. Compared to sintered metal flat plate heat pipes, channel heat pipes have a simpler manufacturing process and offer advantages such as controllable liquid filling rate, high radial heat transfer rate, and simple manufacturing process, maintaining a certain level of reliability even under complex and demanding operating conditions.

[0004] Because the cover plate of the channel heat pipe is in direct contact with the base plate, the channel serves as both a storage area for the working fluid and a flow area for steam. Under the simultaneous action of counter-current steam and liquid, the working fluid tends to stagnate within the channel, reducing heat transfer efficiency. Current patented technologies mainly increase capillary pressure by reducing the channel width, but this can only increase the heat transfer limit of the heat pipe to a certain extent and cannot resolve the aforementioned contradiction. Summary of the Invention

[0005] To address the aforementioned existing problems, this invention proposes a non-uniform channel array micropillar flat plate heat pipe. The non-uniform channels of this flat plate heat pipe reduce liquid reflux resistance and improve the reflux efficiency of the working fluid. The array micropillars in the condensation section further increase the contact heat exchange area based on the channels, accelerating liquid reflux and improving heat exchange efficiency.

[0006] The above-mentioned objective of this invention is achieved through the following technical solutions:

[0007] This invention relates to a non-uniform channel array micropillar flat plate heat pipe, comprising a base plate and a cover plate. The base plate and the cover plate are welded together to form a sealed cavity, which is filled with a liquid working fluid. Ribs are machined on the base plate to form several parallel, unequally spaced axial channels, one end of which has a transverse channel of a certain width. The heat pipe is divided into an evaporation section and a condensation section. The evaporation section consists of partial axial channels, while the condensation section has transverse grooves machined on the ribs to form a spaced cubic array of micropillars. The cover plate and the base plate are welded together to form a sealed cavity, which is filled with a liquid working fluid, constituting a non-uniform channel array micropillar flat plate heat pipe.

[0008] Several ribs, all of which are straight ribs with rectangular cross-sections, are machined into the base plate. The length, width, and height of the ribs are all consistent.

[0009] The base plate is machined with several ribs to form parallel axial channels with varying intervals, ranging in width from 0.92mm to 2.85mm. These are straight channels with a consistent depth, and the width ratio of two adjacent axial channels is 1:2.

[0010] The bottom plate has transverse channels of a certain width at both ends of the axial channel, with a width ratio of 1:1 and a width range of 2 to 4 mm.

[0011] The length ratio of the evaporation section to the condensation section of the heat pipe is 3:2. The condensation section is formed by machining transverse grooves into spaced cubic micropillars on a ribbed base, with the micropillar portion accounting for 1 to 3:3 of the entire condensation section. The ratio of the micropillar width to the groove width between the micropillars is 1:1. The depth of the transverse grooves ranges from 0.3 to 0.8 mm.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] (1) For the design of the evaporation section, the capillary force generated by different channel sizes is different, and the working fluid rise rate is also different. Therefore, they will not meet in the transverse channel of the condensation section and hinder the return flow. Therefore, the heat pipe adopts a non-uniform channel structure design in order to obtain better flow characteristics.

[0014] (2) As for the condensing section, the groove design not only increases the contact heat exchange area and improves the heat exchange efficiency, but also breaks the oscillating liquid column in this section, so that it can quickly and evenly flow back to the evaporation section without going to the top of the condensing section.

[0015] (3) The working fluid remaining in the trench can continue to absorb cold in the condensation section. When the next pulse occurs, this part of the working fluid can be carried away, and new working fluid will fill the trench. Therefore, the working fluid stays in the condensation section for a longer time and the heat exchange is greater. Under high heating power, the array of micropillars can provide a carrier for the generation of condensate droplets and increase the condensation efficiency.

[0016] (4) The channel depth retained in the micro-column section allows the working fluid to still have a certain liquid column rising after moving to the condensation section, increasing the utilization rate of the condensation section. Attached Figure Description

[0017] Figure 1 This is a three-dimensional structural schematic diagram of the non-uniform channel array micropillar flat plate heat pipe of the present invention;

[0018] Figure 2 This is a front view schematic diagram of the non-uniform channel array micropillar flat plate heat pipe of the present invention, namely Embodiment 1;

[0019] Figure 3 This is an enlarged schematic diagram of the base plate of the non-uniform channel array micropillar flat plate heat pipe of the present invention, namely Embodiment 1;

[0020] Figure 4 This is a comparison diagram of the thermal resistance of the non-uniform channel array micro-pillar flat plate heat pipe (Example 1), the uniform channel flat plate heat pipe (Example 2), and the non-uniform channel flat plate heat pipe (Example 3) of the present invention.

[0021] Figure 5 This is a comparison chart of the thermal conductivity of the non-uniform channel array micro-pillar flat plate heat pipe (Example 1), the uniform channel flat plate heat pipe (Example 2), and the non-uniform channel flat plate heat pipe (Example 3) of the present invention.

[0022] Reference numerals in the attached drawings: 1-bottom plate, 2-cover plate, 3-rib, 4-axial channel, 5-transverse channel, 6-transverse groove, 7-micro-column, 8-condensation section, 9-evaporation section. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0024] Example 1

[0025] like Figures 1-3 As shown, this embodiment is a non-uniform channel array micropillar flat plate heat pipe, which includes a base plate 1 and a cover plate 2. Ribs 3 are machined on the base plate 1 to form several parallel axial channels 4 with unequal intervals, and a transverse channel 5 of a certain width is left at one end. The heat pipe is divided into an evaporation section 9 and a condensation section 8. The evaporation section 9 is part of the axial channels 4, and two-thirds of the condensation section 8 has transverse grooves 6 machined on the basis of the ribs 3 to form spaced cubic array micropillars 7. The base plate 1 and the cover plate 2 are welded and sealed to form a closed cavity, and a liquid working fluid is filled into the cavity to form a non-uniform channel array micropillar flat plate heat pipe.

[0026] Several ribs 3 are machined on the base plate 1. All of them are straight ribs with rectangular cross-sections. The length, width and height of the ribs 3 are 144mm×1.5mm×1mm.

[0027] Several ribs 3 are machined on the base plate 1 to form parallel axial grooves 4 with varying widths of 1 mm and 2 mm, and a depth of 1 mm.

[0028] The bottom plate 1 has transverse grooves 5 with a width of 3mm at both the upper and lower ends of the axial groove 4.

[0029] The length ratio of the evaporation section 9 to the condensation section 8 of the heat pipe is 3:2. The condensation section is formed by processing transversely spaced cubic micropillars 7 on the basis of rib 3, and the micropillars 7 account for 2 / 3 of the entire condensation section. The width of the micropillars 7 and the width of the grooves between the micropillars 7 are both 1.5mm, and the depth of the transverse grooves 6 is 0.5mm.

[0030] Example 2

[0031] Referring to Example 1, this example is a uniform channel heat pipe. The only difference from Example 1 is that several ribs 3 with a length, width, and height of 144mm × 1mm × 1mm are machined on the base plate 1. At the same time, the condensation section does not have transverse grooves 6 to form micropillars 7.

[0032] Example 3

[0033] Referring to Example 1, this example is a non-uniform channel heat pipe. The only difference from Example 1 is that the condensation section does not have transverse grooves 6 to form micropillars 7.

[0034] All the above embodiments use R141b as the working fluid, employ a 20% filling rate, and are manufactured using existing technology.

[0035] The above embodiments were tested and calculated to collect the temperature of the outer wall of the heat pipe, thereby analyzing the thermodynamic performance of the heat pipe.

[0036] Depend on Figure 4 It is known that non-uniform channel heat pipes without micropillars only perform well in the first 20W, while the thermal resistance of arrayed micropillar non-uniform flat plate heat pipes has surpassed that of uniform channel flat plate heat pipes, reaching as low as 0.136℃ / W at 60W. Because different channel sizes generate different capillary forces, the working fluid moves at different speeds within different channels. Therefore, the working fluid in adjacent channels will not meet in the transverse channels of the condensation section, thus preventing flow obstruction. The heat pipe exhibits unidirectional flow, improving flow efficiency. Furthermore, the arrayed micropillar design increases the contact heat transfer area, further enhancing heat transfer efficiency.

[0037] Depend on Figure 5 It can be seen that, under a heating power of 10W, the thermal conductivity of the non-uniform channel flat plate heat pipe is relatively high, reaching 2779.32 W·m. -1 ·℃ -1However, this excellent thermal conductivity begins to decrease after 30W, making it unsuitable for high-power heating elements or high-temperature environments. The 2 / 3 array micro-pillar flat plate heat pipe, on the other hand, boasts the best overall thermal conductivity, exhibiting no weaknesses across low, medium, and high heating power levels. Compared to conventional microchannel flat plate heat pipes, its thermal conductivity is comprehensively surpassed, reaching a maximum of 3723 W·m. -1 ·℃ -1 .

[0038] In summary, the thermal performance of the non-uniform channel array micropillar flat plate heat pipe of Embodiment 1 is significantly better than that of Embodiments 2 and 3.

[0039] This invention is not limited to this specific embodiment. For those skilled in the art, simple copying and improvement without creative effort are all within the scope of protection of the claims of this invention.

Claims

1. A non-uniform channel array micropillar flat plate heat pipe, characterized in that: The heat pipe includes a base plate and a cover plate. The base plate and the cover plate are welded together to form a sealed cavity, which is filled with a liquid working fluid. The heat pipe is divided into an evaporation section and a condensation section. The evaporation section consists of a portion of axial channels, and the condensation section consists of a portion of axial channels and transverse channels. The base plate has parallel axial channels with unequal intervals. The axial channels are ribs machined on the base plate. All ribs are straight ribs with a rectangular cross-section. The width of the parallel axial channels with unequal intervals ranges from 0.92 mm to 2.85 mm. The width ratio of two axial channels of different widths is 1:2, and the axial channels of different widths are alternately arranged. A transverse channel of a certain width is left at one end of the base plate. The transverse channel has a spaced array of cubic micropillars. The transverse channel is formed by machining transverse grooves on the straight ribs to form a spaced array of cubic micropillars.

2. The non-uniform channel array micropillar flat plate heat pipe as described in claim 1, characterized in that: The length, width, and height of the ribs machined on the base plate are all kept consistent.

3. The non-uniform channel array micropillar flat plate heat pipe as described in claim 1, characterized in that: The ribs machined on the base plate form parallel, unequally spaced axial grooves that are all straight grooves with a consistent depth.

4. The non-uniform channel array micropillar flat plate heat pipe as described in claim 1, characterized in that: The depth of the transverse grooves ranges from 0.3 to 1 mm.

5. The non-uniform channel array micropillar flat plate heat pipe as described in claim 1, characterized in that: The length ratio of the evaporation section to the condensation section of the heat pipe is 3:

2.

6. The non-uniform channel array micropillar flat plate heat pipe as described in claim 5, characterized in that: In the condensation section, the ratio of the cubic array of micropillars to the entire condensation section is 1 to 3:

3.

7. The non-uniform channel array micropillar flat plate heat pipe as described in claim 1, characterized in that: The ratio of the microcolumn width to the groove width between the microcolumns is 1:1.

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