A plate-type pulsating heat pipe electric component heat sink with synergistically enhanced heat transfer

Abstract

The present application belongs to the technical field of heat dissipation of electrical components, and particularly relates to a plate-type pulsating heat pipe electrical component heat radiator with synergistically enhanced heat transfer. In the present application, a porous copper wire mesh capillary core structure is brazed on the inner wall surface of the evaporation section to provide strong capillary force, and meanwhile, the multiple-loop large bends in the condensation section are interconnected through tapered connecting grooves and micro-groove channels to form a global pressure and working medium distribution composite condensation flow channel network. Compared with the traditional pulsating heat pipe, the present application can effectively solve the problems of flow stagnation or pressure imbalance due to uneven local heating or increased flow resistance, and effectively improve the operation stability and reliability of the system under non-uniform heat load through the capillary enhancement of the evaporation section and the multiple-loop synergy of the condensation section.

Description

Technical Field

[0001] This invention belongs to the field of heat dissipation technology for electrical components, and specifically relates to a plate-type pulsating heat pipe heat sink for electrical components that synergistically enhances heat transfer. Background Technology

[0002] Current electrical components are developing towards high power, high integration, and microscale, making heat dissipation problems increasingly prominent. Pulsating heat pipes are a new type of heat pipe that emerged in the 1990s. Due to their advantages such as good temperature uniformity and high heat dissipation efficiency, they have provided an effective heat dissipation technology for many high-power electrical components. However, traditional pulsating heat pipes face multiple technical challenges in engineering applications, with their disadvantages mainly manifested in the following aspects: First, the system's startup and operation are highly dependent on external operating conditions. The oscillating flow of the working fluid inside the pulsating heat pipe not only requires sufficient initial temperature difference for driving but is also affected by the installation angle. When installed horizontally or inverted, the imbalance in the working fluid distribution can easily lead to continuous gas or liquid blockage, resulting in system startup failure or a significant increase in the time required to reach a stable operating state. Second, due to the random oscillating characteristics of the internal flow, bubble splitting and generation are uncontrollable, and the system operation is often accompanied by large temperature fluctuations, leading to a decrease in overall temperature uniformity. In addition, the flat microgrooves of the plate structure usually have insufficient capillary reflux driving force. As the heat flux density increases, when the working fluid replenishment rate in the evaporation section cannot meet the evaporation demand, it is very easy to cause local drying. This phase change interruption not only limits the maximum heat transfer capacity but also causes irreversible performance degradation. Finally, traditional manufacturing processes often use simple grooving or mechanically processed channels, making it difficult to form capillary structures with controllable pore size and wettability, resulting in uneven working fluid distribution and insufficient fluid reflux capacity. Summary of the Invention

[0003] To address the problems of insufficient boiling heat transfer in the evaporation section, uneven flow in the condensation section, and high overall thermal resistance in existing pulsed heat pipes, this invention proposes a plate-type pulsed heat pipe radiator for electrical components that synergistically enhances heat transfer through a composite evaporation layer and microgroove condensation channels. Through the synergistic effect of capillary enhancement in the evaporation section and microgroove regulation in the condensation section, it effectively improves the stability of the working fluid oscillation and temperature uniformity, reduces the overall thermal resistance of the system, and achieves heat transfer with small temperature differences. This enhances the phase change heat transfer effect of the system and is suitable for heat dissipation of high heat flux density, integrated, and microscale electrical components.

[0004] A plate-type pulsating heat pipe electrical component radiator that synergistically enhances heat transfer through a composite evaporation layer and microgroove condensation channels. This invention builds upon traditional pulsating heat pipes by brazing a porous copper wire mesh onto the inner wall of the evaporation section to provide strong capillary force. Simultaneously, multiple loops in the condensation section are interconnected via tapered connecting grooves and microgroove channels, forming a globally integrated composite condensation flow channel network that regulates pressure and working fluid. The radiator includes a plate-type pulsating heat pipe substrate, a condensation section, an insulation section, and an evaporation section mounted on the substrate, and components encapsulated within the condensation section, insulation section, and evaporation section. The working fluid of the heat pipe is as follows: the condensation section consists of a main channel and micro-channels, which are interconnected by a tapered connecting groove to form a composite condensation flow channel network; the evaporation section is equipped with a brazed copper wire mesh capillary core structure. This structure integrates a vacuum-brazed copper wire mesh capillary layer on the inner wall of the evaporation section to construct a capillary reflux channel and enhance the phase change boiling process. It can generate high capillary pressure and good wettability in the evaporation section, enabling stable liquid reflux, thereby avoiding local drying under high heat flux density and improving the reliability of the pulsating heat pipe. The composite condensation flow channel network formed by the interconnection of the main channel and micro-channels through tapered connecting grooves in the condensation section can significantly reduce flow resistance and improve the uniformity of condensation heat transfer. It can effectively alleviate the gas slugging and liquid slugging that are prone to occur in traditional pulsating heat pipes, improve the oscillation frequency and controllability of the heat transfer process in the pulsating heat pipe, and make the overall temperature fluctuation smaller and the thermal resistance lower.

[0005] Furthermore, the capillary wick structure in the evaporation section is made of 100-150 mesh woven copper mesh with a wire diameter of 0.08mm-0.10mm and a single layer thickness of 0.1mm, and is fixed to the inner wall of the evaporation section by vacuum brazing.

[0006] Furthermore, the condensation section is composed of a main channel and micro channels, wherein the main channel has a width of 2.0 mm and a depth of 2.0 mm, and the micro channels have a width of 0.3 mm and a depth of 0.2 mm.

[0007] Furthermore, the main channel and the micro-channel are connected by tapered grooves to form a composite condensation flow channel network with multiple bends and closed loops. This structure creates a self-adjusting pressure distribution effect at the bend nodes.

[0008] Furthermore, a polycarbonate (PC) or acrylic transparent plate is used as a sealing cover on the plate-type pulsating heat pipe substrate to enable visual testing and optical observation; polycarbonate is preferred to balance mechanical strength and high temperature resistance, but the same material as the plate-type pulsating heat pipe substrate can also be used for sealing.

[0009] To ensure that the microgroove channel only relieves pressure at adjacent bends without affecting the oscillation of the working fluid inside the pipe, the microgroove channel design must meet the following requirements:

[0010] ;

[0011] ;

[0012] ;

[0013] ;

[0014] In the formula, P cap —Capillary pressure, Pa; s —Surface tension, N / m; i —Wetting contact angle, cos i Set the value to 1.0; —Microgroove height, m; P h — hydrostatic pressure, Pa; —Liquid phase density, kg / m³; g —Acceleration due to gravity, m / s² 2 ; z —Difference in liquid level between the two sides, in meters; P d — Dynamic pressure of the liquid plug, Pa; —Acceleration of the liquid plug / liquid column, m / s²; L eff — The equivalent liquid column length affected by acceleration, in meters (m).

[0015] This invention enables efficient phase change heat transfer, and features fast start-up, low thermal resistance, uniform heat diffusion, and multi-angle installation. It is suitable for heat dissipation of high heat flux density, integrated, and microscale electrical components.

[0016] Compared with traditional pulsed heat pipes, the plate-type pulsed heat pipe electrical component radiator proposed in this invention, which synergistically enhances heat transfer through a composite evaporation layer and microgroove condensation channels, achieves adaptive distribution of the working fluid flow and multi-scale enhanced heat transfer in the condensation section by arranging a composite evaporation layer with a copper wire mesh capillary core structure in the evaporation section and introducing a composite condensation flow channel network in the condensation section. This significantly improves phase change heat transfer efficiency and enhances system cycle stability, and has the following characteristics and beneficial effects:

[0017] 1. In the evaporation section, the invention uses a vacuum-brazed copper wire mesh capillary reinforcement layer to form a stable liquid film reflux region and a multi-point bubble nucleation interface within a microscale range. This promotes the formation of a dense capillary core structure, enabling the working fluid to quickly reflux to the heat source region of the evaporation section. This enhances the liquid working fluid replenishment capacity, prevents local drying, significantly strengthens the phase change boiling process, and effectively improves the heat flux and heat transfer effect of the evaporation section.

[0018] 2. In the condensation section, the present invention adopts a composite condensation flow channel network formed by interconnecting the main channel and the micro-channel through a gradually narrowing connecting groove. This allows the working fluid liquid plug and gas plug to achieve local pressure buffering in the micro-channel between adjacent large bends, effectively prolonging the condensation time of the gaseous working fluid in the condensation section, thereby reducing local condensation resistance and temperature gradient, improving the uniformity of condensation heat transfer and circulation stability, and thus improving the overall heat transfer performance of the pulsating heat pipe.

[0019] The synergistic mechanism of the composite evaporation enhancement layer and the microgroove condensation channel in this invention improves heat transfer performance in the following ways:

[0020] 1. Pressure equalization and anti-clogging: The micro-groove channel forms an additional parallel channel in the composite condensation flow channel network, which can achieve rapid adaptive pressure balance between different bend channels. This mechanism effectively suppresses flow blockage caused by local pressure unevenness or gas-liquid plug accumulation.

[0021] 2. Efficient management of condensate: On the one hand, the microchannel structure promotes the lateral diffusion and redistribution of the condensate film, ensuring the stability of the return path; on the other hand, the microchannel accelerates the overall migration speed of condensate to the evaporation section by reducing flow stagnation dead zones and local stagnant zones.

[0022] By combining the aforementioned pressure equalization and liquid film management capabilities, this invention can maintain a stable and efficient self-excited oscillation cycle even when electrical components experience significant heat fluctuations at high power, thus achieving efficient heat dissipation. Attached Figure Description

[0023] Figure 1 This is a front view of a plate-type pulsating heat pipe electrical component radiator that uses a composite evaporation layer and a microgroove condensation channel to synergistically enhance heat transfer, according to an embodiment of the present invention.

[0024] Figure 2 The thermal resistance of the plate-type pulsating heat pipe with synergistic enhancement according to the present invention and the traditional pulsating heat pipe are compared under different heating powers.

[0025] Explanation of reference numerals in the attached diagram: 1. Condensation section; 2. Insulation section; 3. Evaporation section; 4. Microchannel; 5. Capillary wick structure; 6. Liquid inlet hole; 7. Main channel; 8. Plate-type pulsating heat pipe substrate; 9. Gradient connecting groove; 10. Composite condensation flow channel network. Detailed Implementation

[0026] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

[0027] Please see Figure 1 This invention provides a plate-type pulsating heat pipe electrical component radiator that synergistically enhances heat transfer through a composite evaporation layer and microgroove condensation channels. Its core innovation lies in the integrated structure of an evaporation section with a composite capillary core structure and a multi-scale microgroove condensation section, aiming to improve the system's heat transfer performance and operational stability. Specifically, the structure consists of a copper wire mesh capillary core structure 5 fixed to the inner wall of the evaporation section 3 via vacuum brazing, providing strong resistance to dry burning and enhancing the phase change boiling process. In the condensation section 1, a composite condensation flow channel network 10 is formed by interconnecting main channels 7 and microgroove channels 4 through tapered connecting grooves 9. This structure significantly reduces flow resistance and improves the uniformity of condensation heat transfer. Finally, a transparent polycarbonate (PC) plate is used for encapsulation, providing conditions for visual research on the two-phase flow of the working fluid. This invention effectively solves the problems of localized drying and flow instability of the working fluid under high heat flux in traditional pulsating heat pipes by strengthening capillary force drive and optimizing condensation reflux, thereby achieving efficient and reliable two-phase heat dissipation.

[0028] In an embodiment, the present invention includes a plate-type pulsating heat pipe substrate 8 and a condensation section 1, an insulation section 2, and an evaporation section 3 arranged on the plate-type pulsating heat pipe substrate 8.

[0029] The inner wall of the evaporation section 3 is provided with a capillary core structure 5 fixed by brazing, which is used to form a composite evaporation enhancement layer.

[0030] The condensation section 1 is mainly composed of a main channel 7 and a micro channel 4. The main channel 7 has a cross-sectional width of 2.0 mm and a depth of 2.0 mm; the micro channel 4 has a cross-sectional width of 0.3 mm and a depth of 0.2 mm. The two are interconnected by a tapered connecting channel 9 to form a composite condensation flow channel network 10.

[0031] The adiabatic section 2 is located between the condensing section 1 and the evaporating section 3. Its main function is to reduce axial heat conduction and maintain the continuous oscillating flow of the working fluid between the evaporating section 3 and the condensing section 1.

[0032] When electrical components operate, they generate a large amount of heat. The liquid working fluid in the evaporation section 3 absorbs the heat and vaporizes, forming bubbles and causing a sharp increase in local pressure. The high pressure drives the gas-liquid working fluid mass to flow to the condensation section 1, where the pressure is lower. In the condensation section 1, the bubbles cool, contract, and burst, releasing the latent heat of vaporization, which causes the local pressure to drop. Driven by the periodic pressure difference between the evaporation section 3 and the condensation section 1, the working fluid generates a self-excited oscillating flow in the pulsating heat pipe, thereby efficiently transferring heat from the evaporation section 3 to the condensation section 1.

[0033] After the condensing section 1, the adiabatic section 2 and the evaporation section 3 are prepared on the plate-type pulsed heat pipe substrate 8 by mechanical processing, they are vacuum-sealed and filled with liquid using a high-vacuum sealing process. An appropriate amount of working fluid (such as deionized water) is filled inside through the liquid inlet 6, and the liquid filling rate is controlled between 40% and 60% to achieve the best heat transfer effect.

[0034] In this embodiment, the innovative structure of the condensation section 1 is mainly reflected in the micro-groove channels 4 at its bend nodes. Specifically, the micro-groove channels 4 are arranged at each bend of the condensation section 1, and adjacent large bends are connected to each other through tapered connecting grooves 9, thereby constructing a closed and interconnected composite condensation flow channel network 10.

[0035] This invention employs a multi-scale composite condensation flow channel network 10 coupled with a main channel 7 and microchannels 4. This structure enables rapid backflow of liquid plugs within the condensation section 1, while reducing local liquid stagnation and ensuring smoother backflow. This significantly reduces flow resistance within the condensation section 1 and improves condensation efficiency. The microchannels 4 balance the pressure between bends in the condensation section 1. The main channel 7 serves as the primary channel for working fluid flow, allowing the condensation section 1 to adaptively distribute pressure and enhancing the stability of the working fluid circulation. Through pressure optimization in the condensation section 1, the liquid working fluid supply to the evaporation section 3 is more sufficient. Through the synergistic effect of evaporation and condensation, not only is the overall thermal resistance reduced, but the heat transfer efficiency and reliability of the plate-type pulsating heat pipe are also improved in various complex heat loads and microscale structural heat dissipation applications.

[0036] In this embodiment, the inner wall of the evaporation section 3 is fixed with a multi-layer capillary wick structure 5 by vacuum brazing. The capillary wick structure 5 has a mesh size of 100-150, a wire diameter of 0.08-0.10 mm, and a single layer thickness of approximately 0.1 mm. This structure can form multi-point bubble nucleation interfaces and capillary reflux channels within a microscale range. There are at least 360 mesh openings within a 2.0 mm × 2.0 mm channel. Within a 10 mm range of this single-loop pulsating heat pipe, the evaporation section 3 will have more than 10,000 mesh openings, effectively promoting the replenishment of liquid working fluid and bubble generation, thereby enhancing the boiling phase change heat transfer capability of the evaporation section 3.

[0037] In the preferred embodiment, a capillary core structure 5 formed by brazing multiple layers of copper wire mesh is arranged within the evaporation section 3. This structure provides significant capillary force, which can significantly improve the liquid working fluid replenishment efficiency. It not only increases the bubble nucleation rate and liquid film rupture frequency in the evaporation section 3, but also accelerates the formation and evaporation of the liquid film. This effectively solves the problems of difficult start-up, localized dry burning due to working fluid desiccation, and unstable heat transfer under low heat flux density inherent in traditional pulsating heat pipes. Furthermore, the three-dimensional capillary network formed by the multiple layers of copper wire mesh provides a uniform distribution of liquid working fluid and a stable return path, ensuring that the evaporation section 3 can maintain a stable two-phase cycle even under high heat flux or complex load conditions, achieving rapid and efficient phase change heat transfer.

[0038] In this embodiment, the plate-type pulsating heat pipe substrate 8 can be sealed and encapsulated using a transparent polycarbonate (PC) plate or the same material as the substrate, with a thickness of 3.0 mm. The sealing plate can ensure mechanical strength and high-temperature resistance while also enabling visual observation of gas-liquid oscillation behavior. The PC cover plate is bonded and fixed to the bottom of the plate-type pulsating heat pipe substrate 8 with high-temperature epoxy adhesive or vacuum-sealed silicone, forming a seal along the upper part of the plate-type pulsating heat pipe substrate 8 to prevent working fluid leakage.

[0039] In this invention, the microgroove channel 4 only relieves pressure at adjacent bends during operation without affecting the oscillation of the working fluid inside the pipe. Its design must meet the following requirements:

[0040] ;

[0041] ;

[0042] ;

[0043] ;

[0044] In the formula, P cap —Capillary pressure, Pa; s —Surface tension, N / m; i —Wetting contact angle, cos i Set the value to 1.0; —Microgroove height, m; P h — hydrostatic pressure, Pa; —Liquid phase density, kg / m³; g —Acceleration due to gravity, m / s² 2 ; z —Difference in liquid level between the two sides, in meters; P d— Dynamic pressure of the liquid plug, Pa; —Acceleration of the liquid plug / liquid column, m / s²; L eff — The equivalent liquid column length affected by acceleration, in meters (m).

[0045] In summary, the capillary pressure of the microchannel 4 is greater than the sum of the hydrostatic pressure (49.0 Pa) and the dynamic pressure of the liquid plug (158.0 Pa), and its main function is to balance the pressure between the circuits.

[0046] The working principle of this invention is as follows: When the electrical components located on the lower surface of the evaporation section 3 generate heat, the working fluid in the capillary wick structure 5 located on the inner wall of the evaporation section 3 absorbs heat and rapidly vaporizes to form a gas plug. The expansion of the gas plug generates pressure, pushing it along the pipe to the condensation section 1, realizing the effective migration of the working fluid and heat transfer. In the condensation section 1, the gas plug encounters a lower temperature flow channel, and the gaseous working fluid condenses into a liquid working fluid and releases the latent heat of vaporization. Since the condensation section 1 is composed of a multi-scale composite condensation flow channel network 10 consisting of the main channel 7 and the micro-channel 4, this structure allows the working fluid flow direction to be adaptively adjusted according to the local pressure distribution, achieving a uniform distribution of the liquid working fluid. Under the combined action of capillary force and pressure difference, the liquid working fluid flows back to the evaporation section 3, absorbs heat, and vaporizes again, forming a stable reciprocating oscillating cycle. This invention, through the synergistic effect of the composite evaporation enhancement layer and the microgroove condensation channel, enables the system to not only achieve efficient heat transfer and phase change cycle, but also significantly improve oscillation stability, condensation uniformity, and overall phase change heat transfer efficiency. Even under high heat flux or complex heat load, this invention can still maintain reliable phase change heat transfer performance.

[0047] The present invention has a compact overall structure, low thermal resistance, and uniform temperature distribution. Through the synergistic mechanism of the composite evaporation enhancement layer and the micro-groove condensation channel, the local heat exchange capacity of the evaporation section 3 and the condensation section 1 is significantly improved.

[0048] Furthermore, the visualization structure design of this invention makes it suitable for observing and studying the gas-liquid two-phase flow patterns inside pulsating heat pipes, and is especially suitable for the efficient heat dissipation of high-power, integrated, and microscale electrical components.

[0049] Figure 2The figure compares the thermal resistance of the plate-type pulsed heat pipe with the synergistic enhancement of this invention with that of a traditional pulsed heat pipe at heating power of 20W, 40W, 60W, 80W, 100W, and 120W. As can be seen from the figure, the thermal resistance of both types of pulsed heat pipes decreases with increasing heating power. Compared with the traditional pulsed heat pipe, the thermal resistance of the plate-type pulsed heat pipe with the synergistic enhancement of this invention is reduced by an average of 35.3% and a maximum of 46.1%, demonstrating its superior heat transfer performance. This is because the copper wire mesh capillary core structure arranged in the evaporation section of the plate-type pulsed heat pipe with the synergistic enhancement of this invention can generate more vaporization nuclei. This structure can effectively improve the liquid absorption capacity of the evaporation section, making its heat transfer efficiency higher during stable operation. In particular, when the single bend pipe in the evaporation section experiences burn-out, leading to an increase in local pipe pressure, the composite condensation flow channel network structure can effectively balance the pressure in each bend channel, thereby improving the system's anti-burn-out capability and making the system operate more smoothly and reliably.

[0050] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A plate-type pulsating heat pipe electrical component radiator that synergistically enhances heat transfer through a composite evaporation layer and a microgroove condensation channel, comprising a plate-type pulsating heat pipe substrate (8) and a condensation section (1), an insulation section (2), and an evaporation section (3) arranged on the plate-type pulsating heat pipe substrate (8), characterized in that: The condensation section (1) adopts a composite condensation flow channel network (10) consisting of a main channel (7), a micro-channel (4), and a tapered connecting channel (9) connecting the two; the condensation section (1) consists of a multi-bend closed loop composed of the main channel (7), the micro-channel (4), and the tapered connecting channel (9); and the evaporation section (3) is provided with a capillary core structure (5) formed by brazing multiple layers of copper wire mesh, which is fixed to the bottom of the evaporation section (3) by vacuum brazing; when designing the micro-channel (4), the following requirements must be met to achieve pressure relief only at adjacent bends without affecting the oscillation of the working fluid inside the pipe: ； ; ; ; In the formula, P cap —Capillary pressure, Pa; σ —Surface tension, N / m; θ —Wetting contact angle, cos θ Set the value to 1.0; —Microgroove height, in meters; P h — hydrostatic pressure, Pa; —Liquid phase density, kg / m³; g —Acceleration due to gravity, m / s² 2 ; z —Difference in liquid level between the two sides, in meters; P d — Dynamic pressure of the liquid plug, Pa; —Acceleration of the liquid plug / liquid column, m / s²; L eff — The equivalent liquid column length affected by acceleration, in meters.

2. The plate-type pulsating heat pipe electrical component radiator with composite evaporation layer and microgroove condensation channel synergistically enhanced heat transfer as described in claim 1, characterized in that: The main channel (7) has a width of 2.0 mm and a depth of 2.0 mm, and the micro-channel (4) has a width of 0.3 mm and a depth of 0.2 mm.

3. The plate-type pulsating heat pipe electrical component radiator with composite evaporation layer and microgroove condensation channel synergistically enhanced heat transfer as described in claim 1, characterized in that: The capillary core structure (5) uses 100-150 mesh woven copper wire mesh with a wire diameter of 0.08 mm-0.10 mm and a single layer thickness of 0.1 mm.

4. The plate-type pulsating heat pipe electrical component radiator with composite evaporation layer and microgroove condensation channel synergistically enhanced heat transfer as described in claim 2, characterized in that: The main channel (7) and the micro channel (4) form a composite condensation flow channel network (10) with self-adjusting pressure distribution through the gradually narrowing connecting groove (9) along the lower flow channel of the bend.

5. The plate-type pulsating heat pipe electrical component radiator with composite evaporation layer and microgroove condensation channel synergistically enhanced heat transfer as described in claim 1, characterized in that: The upper part of the plate-type pulsating heat pipe substrate (8) is sealed with a transparent polycarbonate or acrylic plate to achieve visual testing and optical observation.

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