A Tesla valve type ultra-thin planar thermal diode based on phase change heat transfer technology

Abstract

The present invention relates to a Tesla valve-type ultra-thin planar thermal diode based on phase change heat transfer technology. The diode comprises a tube body, within which are disposed an evaporation end, a liquid working fluid cavity, a Tesla valve flow channel, a liquid wick filled with liquid working fluid, and a condensation end. The wick is disposed within the liquid working fluid cavity. The condensation end, the wick, and the evaporation end are sequentially connected to form a liquid working fluid path, while the evaporation end, the Tesla valve flow channel, and the condensation end are sequentially connected to form a gaseous working fluid path. The Tesla valve utilizes the fluid acceleration characteristics and unidirectional conductivity of the fluid to improve the unidirectional thermal conductivity of the ultra-thin planar thermal diode. During forward heating, the gaseous working fluid flows from the evaporation end to the condensation end, flowing downstream within the Tesla valve with low air resistance and high thermal conductivity. During reverse heating, the gaseous working fluid flows from the condensation end to the evaporation end, flowing countercurrently within the Tesla valve with high air resistance and low thermal conductivity, thereby achieving the effect of a thermal diode. The diode can be widely used in the microelectronics industry.

Description

Technical Field

[0001] The present invention relates to the field of microelectronic components, and in particular to a Tesla valve type ultra-thin planar thermal diode based on phase change heat transfer technology. Background Art

[0002] Thermal management is a crucial component in various applications, particularly in the miniaturization of electronics. Thermal diodes, which exhibit asymmetric heat transfer characteristics along the axial direction, are a crucial component of thermal management systems. Currently, most thermal diodes are gravity-operated, relying on gravity to drive the recirculation of the working fluid within the heat pipe. These diodes are significantly affected by the tilt angle, have strict operating conditions, and are therefore limited in their application. There are also thermal diodes composed of two thermally conductive materials, where the thermal conductivity of these materials varies with temperature. However, these diodes transfer heat through conduction and have a lower thermal conductivity.

[0003] The applicant has discovered that Tesla valves are widely used in fluid control but rarely found in the field of microelectronic components. Therefore, to address the shortcomings of existing technologies, this patent proposes a Tesla valve-type ultra-thin planar thermal diode based on phase change heat transfer technology. This utilizes phase change heat transfer technology to improve thermal conductivity and introduces a highly efficient capillary wick structure to compensate for the shortcomings of gravity-type thermal diodes. Summary of the Invention

[0004] In response to the technical problems existing in the prior art, the purpose of the present invention is to provide a Tesla valve type ultra-thin planar thermal diode based on phase change heat transfer technology, which utilizes the acceleration characteristics and unidirectional conductivity of the Tesla valve on the fluid to improve the unidirectional thermal conductivity of the ultra-thin planar thermal diode.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A Tesla valve-type ultra-thin planar thermal diode based on phase change heat transfer technology includes a tube body, within which are disposed an evaporation end, a liquid working fluid cavity, a Tesla valve flow channel, a liquid wick filled with liquid working fluid, and a condensation end. The wick is disposed within the liquid working fluid cavity. The condensation end, the wick, and the evaporation end are sequentially connected to form a liquid working fluid passage. The evaporation end, the Tesla valve flow channel, and the condensation end are sequentially connected to form a gaseous working fluid passage. The liquid and gaseous working fluids within the tube body flow through the liquid working fluid passage and the gaseous working fluid passage, respectively, without interfering with each other, thereby reducing convection resistance between the gas and liquid. The working fluid reflux relies on capillary force, independent of gravity, and unaffected by the thermal diode's tilt angle, resulting in a flexible operating environment. The Tesla valve utilizes the fluid acceleration characteristics and unidirectional conductivity of the fluid to improve the unidirectional thermal conductivity of the ultra-thin planar thermal diode, thereby enhancing its sensitivity and accuracy and greatly expanding its application range.

[0007] Furthermore, there are multiple Tesla valve flow channels, each of which is provided with multiple stages of Tesla valves spliced in sequence, and the multiple Tesla valve flow channels are arranged in parallel.

[0008] Furthermore, the wick fits tightly with the Tesla valve channel.

[0009] Furthermore, the tube body includes an upper shell and a lower shell that are connected correspondingly, the gaseous working medium passage is arranged in the upper shell, the liquid working medium cavity is arranged in the lower shell, and the height of the liquid absorption core is greater than the depth of the liquid working medium cavity.

[0010] Furthermore, the area of the evaporation end and the condensation end in the upper shell accounts for ≤60%.

[0011] Furthermore, both the evaporation end and the condensation end are point column arrays.

[0012] Furthermore, in the dot column array, the center distance between every two adjacent dot columns is ≤2 mm.

[0013] Furthermore, the cross section of the point column is circular or rectangular.

[0014] Furthermore, the vacuum degree inside the tube body is 5-10Pa.

[0015] Furthermore, the liquid working medium is ultrapure water, and its resistivity is ≥18MΩ*cm.

[0016] In general, the present invention has the following advantages:

[0017] The Tesla valve-type ultra-thin planar thermal diode, based on phase-change heat transfer technology, is ≤1.3mm thick and is an ultra-thin flat-plate heat pipe widely applicable to the microelectronics industry. It utilizes the Tesla valve's fluid acceleration and unidirectional conductivity to improve unidirectional thermal conductivity. During forward heating, the gaseous working fluid flows forward within the Tesla valve, resulting in low air resistance and high thermal conductivity. During reverse heating, the gaseous working fluid flows backward within the Tesla valve, resulting in high air resistance and low thermal conductivity, achieving the effect of a thermal diode. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic structural diagram of the upper shell of Example 1.

[0019] Figure 2 This is a schematic structural diagram of the lower shell of Example 1.

[0020] Figure 3 Schematic cross-sectional view of the ultra-thin planar thermal diode of Example 1.

[0021] Figure 4 This is a schematic structural diagram of the upper shell of Example 2.

[0022] Reference numerals:

[0023] 1-upper shell, 2-lower shell, 3-Tesla valve flow channel, 41-evaporation end, 42-condensation end, 5-liquid suction core, 6-solder paste tank, 7-tin solder paste. DETAILED DESCRIPTION

[0024] The present invention will be described in further detail below.

[0025] Example 1

[0026] like Figure 1 As shown, the upper shell 1 is etched through an etching process to form a gaseous working medium cavity, an evaporation end 41 arranged in the gaseous working medium cavity, a Tesla valve channel 3 and a condensation end 42, and a solder paste groove 6 on the edge of the upper shell 1. Among them, the point column arrays of the evaporation end 41 and the condensation end 42 are cylindrical point columns. There are a total of 4 Tesla valve channels 3, which are arranged in parallel along the horizontal direction between the evaporation end 41 and the condensation end 42, accounting for 50% of the gaseous working medium cavity of the entire upper shell 1. Each Tesla valve of the Tesla valve channel 3 forms an angle of 30° with the horizontal direction, and the depth-to-width ratio of the air channel in each Tesla valve is 3:5. Among them, the point column arrays of the evaporation end 41 and the condensation end 42 are both 8 rows and 18 columns, with a point column diameter of 0.8 mm, accounting for 50% of the gaseous working medium cavity of the entire upper shell 1.

[0027] The acceleration characteristics and unidirectional conductivity of the Tesla valve structure on the fluid are utilized to improve the linear flow of the fluid in the gaseous working medium cavity and the unidirectional thermal conductivity of the ultra-thin planar thermal diode.

[0028] like Figure 2 As shown, the lower shell 2 is etched with a liquid working medium cavity through an etching process, which is used to fill the copper powder sintered structure liquid absorption core 5 with high capillary performance. A solder paste groove 6 is also etched at the corresponding edge of the upper shell 1.

[0029] like Figure 3As shown, to facilitate the positioning and metering of solder paste 7 during welding of the upper shell 1 and lower shell 2, a solder paste groove 6 with a depth-to-width ratio of 3:5 is provided at the edge of the upper shell 1 and lower shell 2. After welding, the thickness of the solder paste 7 is 0.1mm. The liquid working fluid cavity in the lower shell 2 is etched to a depth of 0.3mm. The hot slag structure wick 5 in the liquid working fluid cavity is manufactured by sintering copper powder and has a thickness of 0.4mm. The wick 5 is raised above the etching depth of the liquid working fluid cavity to ensure a close fit with the Tesla valve flow channel 3 in the upper shell 1. This compensates for the increased gap caused by the solder paste layer 7 after welding, ensuring that gaseous working fluid can only pass through the Tesla valve flow channel 3 of the gaseous working fluid cavity from the evaporation end 41 to the condensation end 42, while liquid working fluid passes through the heat absorption wick of the liquid working fluid cavity from the condensation end 42 to the evaporation end 41. The liquid and gaseous working fluids in the thermal diode flow through their respective channels, without generating convection between them, thus reducing the convection resistance between the gas and the liquid. The backflow of the working fluid relies on capillary force, not gravity, and is not affected by the tilt angle of the thermal diode. It has free working conditions, which is conducive to improving the sensitivity and accuracy of the ultra-thin planar thermal diode and greatly expanding the application range of the thermal diode.

[0030] The outer extensions of the upper and lower shells 1 and 2 are used for tube insertion, facilitating leak detection, fluid injection, vacuuming, and packaging. The liquid fluid injected is ultrapure water with a resistivity of 18.2 MΩ*cm. After vacuuming, the vacuum level inside the ultra-thin planar thermal diode is 7 Pa.

[0031] Example 2

[0032] The difference between this embodiment and embodiment 1 is that:

[0033] like Figure 4 As shown, the dot column arrays at the evaporation end 41 and condensation end 42 of the upper housing 1 have been changed from cylindrical dot columns to rectangular dot columns. Each rectangular dot column is 1 mm long and 0.1 mm wide, with a total of 8 rows and a row spacing of 1 mm. This improves the directionality of the gaseous working medium during heat pipe operation, reduces air resistance, and improves thermal conductivity.

[0034] The ultra-thin planar thermal diode of the present invention incorporates a Tesla valve structure into its airway design, utilizing the Tesla valve's fluid acceleration characteristics and unidirectional conductivity to improve unidirectional thermal conductivity and thermal conductivity efficiency. During forward heating, the gaseous working medium flows from the evaporation end 41 toward the condensation end 42, flowing downstream within the Tesla valve in the gaseous working medium cavity, resulting in low air resistance and high thermal conductivity. During reverse heating, the gaseous working medium flows from the condensation end 42 toward the evaporation end 41, flowing upstream within the Tesla valve in the gaseous working medium cavity, resulting in high air resistance and low thermal conductivity, thereby achieving the effect of a thermal diode. The ultra-thin planar thermal diode is also only 1.3 mm thick and can be widely used in microelectronic devices.

[0035] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A Tesla valve type ultra-thin planar thermal diode based on phase change heat transfer technology, characterized by: The tube body comprises an evaporation end, a liquid working medium cavity, a Tesla valve flow channel, a liquid wick filled with liquid working medium and a condensation end; The liquid wick is arranged in the liquid working medium cavity; The condensation end, the liquid absorption core and the evaporation end are connected in sequence to form a liquid working medium passage; The evaporation end, the Tesla valve flow channel and the condensation end are connected in sequence to form a gaseous working medium passage; There are multiple Tesla valve flow channels, each of which is equipped with multiple stages of Tesla valves spliced in sequence, and multiple Tesla valve flow channels are arranged in parallel; The wick fits tightly with the Tesla valve flow channel; The tube body includes an upper shell and a lower shell that are connected to each other. The gaseous working medium passage is provided in the upper shell, the liquid working medium cavity is provided in the lower shell, and the height of the liquid wick is greater than the depth of the liquid working medium cavity. The total area of the evaporation end and the condensation end in the upper shell is ≤ 60%; Both the evaporation end and the condensation end are point column arrays.

2. The Tesla valve type ultra-thin planar thermal diode based on phase change heat transfer technology according to claim 1, characterized in that: In the dot column array, the center distance between every two adjacent dot columns is ≤2mm.

3. The Tesla valve type ultra-thin planar thermal diode based on phase change heat transfer technology according to claim 1, characterized in that: The cross section of the point column is circular or rectangular.

4. The Tesla valve type ultra-thin planar thermal diode based on phase change heat transfer technology according to claim 1, characterized in that: The vacuum degree inside the tube is 5-10Pa.

5. The Tesla valve type ultra-thin planar thermal diode based on phase change heat transfer technology according to claim 1, characterized in that: The liquid working medium is ultrapure water, and its resistivity is ≥18MΩ·cm.

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