Pulsating heat pipe heat dissipation device based on heterogeneous turbulent flow and variable-diameter structure strengthening

Abstract

The invention discloses a pulsating heat pipe heat dissipation device based on heterogeneous turbulent flow and variable-diameter structure strengthening, and a variable-diameter pulsating heat pipe heterogeneous turbulent flow unit is of an asymmetric snakelike pipeline structure formed by connecting multiple pulsating heat pipe evaporation sections and multiple pulsating heat pipe condensation sections end to end, wherein the multiple pulsating heat pipe evaporation sections and the multiple pulsating heat pipe condensation sections are formed by bending capillary tubes with non-uniform inner diameters. According to the variable-diameter pulsating heat pipe heterogeneous turbulent flow unit, more intense pulsating heat exchange and phase change circulation can be excited, then the one-way oscillation and gas-liquid phase change process of working medium fluid in the pipe is promoted, the multiple turbulent flow enhancing structures are periodically arranged in the variable-diameter pulsating heat pipe heterogeneous turbulent flow unit in the axial direction, the multiple turbulent flow enhancing structures are arranged in a staggered mode, local turbulent flow and pulsating flow are enhanced, and the heat exchange efficiency is improved. Therefore, the turning frequency and the heat exchange rate of the gas-liquid phase change medium between the evaporation section and the condensation section are obviously enhanced. According to the heterogeneous turbulent flow and variable diameter structure, the Nusselt number (Nu) can be remarkably improved, so that the heat transfer efficiency is improved, the temperature uniformity is improved, the cycle life of the battery is prolonged, and the system safety is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of heat dissipation of new energy battery packs, and in particular to a pulsating heat pipe heat dissipation device based on heterogeneous turbulence and variable diameter structure reinforcement. Background Art

[0002] In recent years, environmental concerns and energy shortages have become increasingly prominent, driving traditional automakers to pursue breakthroughs in new energy vehicle technology. Power batteries provide energy for the entire vehicle. During normal operation, they naturally generate heat, causing their temperature to rise. If this heat cannot be dissipated promptly and effectively, the overall battery temperature may become too high or the temperature differences between individual batteries may become too large. High temperatures not only degrade lithium-ion battery performance but, in severe cases, can lead to thermal runaway, resulting in fires and significant damage. Therefore, to ensure consistent battery safety and efficiency, it is essential to design a heat dissipation system that improves heat dissipation efficiency and ensures safe driving.

[0003] Currently, electric vehicle battery systems primarily use two cooling methods: air cooling and liquid cooling. Air cooling primarily relies on air as a cooling medium, but air has low specific heat capacity and thermal conductivity, resulting in limited heat exchange efficiency and difficulty responding quickly to rapidly rising battery temperatures. Furthermore, air cooling systems primarily act on the surface of the battery module, failing to effectively control the core heat source within the battery. This can easily lead to uneven temperature distribution and significant local overheating, which in turn affects the overall performance and safety of the module. Furthermore, its heat exchange capacity is limited by the external ambient temperature and airflow conditions. In extreme scenarios such as high temperatures, enclosed areas, or high altitudes, the cooling effect is severely reduced, significantly increasing the risk of thermal runaway.

[0004] At the same time, in actual operation, both air-cooled and liquid-cooled systems suffer from uneven heat dissipation, delayed response, complex structural integration, or high system energy consumption, making it difficult to achieve the required performance of "thermal response speed, balanced heat distribution, structural integration, and operational stability." This is especially true during the full lifecycle and multi-scenario dynamic operation of electric vehicles. Traditional heat dissipation methods struggle to establish a fast, efficient, and three-dimensional heat flow control path, making them a key obstacle to upgrading battery safety management systems.

[0005] In summary, there is an urgent need to propose a new battery thermal management strategy with multi-dimensional heat conduction paths, high-frequency dynamic heat exchange capabilities, structural self-driven stable operation, and adaptability to multiple cooling boundaries, so as to break the limitations of existing heat dissipation modes, comprehensively improve the system's thermal response speed, thermal field uniformity and safety control level, and provide a more reliable and advanced thermal management solution for the new generation of high-performance electric vehicles. Summary of the Invention

[0006] In order to overcome the shortcomings of the existing technology, the present invention proposes a pulsating heat pipe cooling device based on heterogeneous turbulence and variable diameter structure reinforcement, which has significant advantages such as high heat transfer efficiency, balanced temperature distribution, and fast startup speed.

[0007] In order to achieve the above object, the technical solutions specifically adopted by the present invention are as follows: A pulsating heat pipe heat dissipation device based on heterogeneous turbulence and variable diameter structure reinforcement includes a base heat conducting plate, a cooling interface plate, and an inter-cell heat conducting plate and a variable diameter pulsating heat pipe heterogeneous turbulence unit arranged between two rows of battery cells; the base heat conducting plate is arranged horizontally and is tightly connected to the bottom of the inter-cell heat conducting plate and the bottom of the battery cell respectively; the cooling interface plate is arranged horizontally and is tightly connected to the top of the inter-cell heat conducting plate and the top of the battery cell respectively; the variable diameter pulsating heat pipe heterogeneous turbulence unit is an asymmetric serpentine pipe structure formed by bending a capillary tube with a non-uniform inner diameter, and each pipe of the asymmetric serpentine pipe structure The difference in length and diameter of the pipe causes an obvious local pressure gradient to be formed between the evaporation section and the condensation section of the pulsating heat pipe, which will cause differences in the flow paths between the pipes, and then generate non-uniform flow resistance and pressure difference driving force during the flow of the working medium, which can stimulate stronger pulsating heat exchange and phase change cycles, and improve the overall heat transfer performance; the upper end of the variable diameter pulsating heat pipe heterogeneous spoiler unit passes through the cooling interface plate and leaks out, and the lower end passes through the heat conduction plate between the battery cells and extends to the base heat conduction plate, and the interior of the variable diameter pulsating heat pipe heterogeneous spoiler unit is periodically provided with multiple spoiler enhancement structures along the axial direction, and the multiple spoiler enhancement structures are arranged in a staggered manner.

[0008] Furthermore, the variable-diameter pulsating heat pipe heterogeneous turbulence unit is composed of multiple sections of pulsating heat pipe evaporation sections and multiple sections of pulsating heat pipe condensation sections connected end to end. The pulsating heat pipe evaporation section and the pulsating heat pipe condensation section are independently interconnected and have a stable liquid-gas phase change space to ensure efficient circulation of the fluid under pulsation action, thereby realizing rapid absorption and release of heat from the power battery.

[0009] Furthermore, the battery cells are arranged in two rows, front and rear. An inter-cell heat conduction plate is vertically positioned between the two rows of battery cells, with its bottom perpendicular to the base heat conduction plate and internally provided with a groove structure. The pulsating heat pipe evaporation section is located below the cooling interface plate, forming an "L"-shaped, asymmetrical arrangement front to back, with the vertical portion located in the groove structure and the horizontal portion arranged in the base heat conduction plate. The upper end of the pulsating heat pipe condensation section is exposed to the upper portion of the cooling interface plate, and in conjunction with an external air or liquid cooling system, achieves rapid heat dissipation.

[0010] Furthermore, the pulsating heat pipe evaporator and condenser sections are periodically provided with multiple turbulence enhancement structures along the axial direction, with the multiple turbulence enhancement structures arranged in a staggered manner. These turbulence enhancement structures consist of a series of semicircular ribs, periodically arranged axially along the inner wall of the variable-diameter pulsating heat pipe's heterogeneous turbulence unit. They are used to break up the laminar boundary layer within the tube and induce localized secondary vortices, thereby enhancing the turbulence of the working fluid within the tube and improving the heat transfer efficiency between the pulsating heat pipe evaporator and condenser sections.

[0011] Furthermore, the internal cavity of the variable diameter pulsating heat pipe heterogeneous turbulence unit needs to be vacuumed before assembly, and an appropriate amount of phase change working fluid, such as deionized water, methanol or ethanol, needs to be injected. This process ensures the formation of a stable gas and liquid two-phase flow environment inside the pulsating heat pipe, which is conducive to achieving efficient phase change heat transfer during operation, thereby significantly improving the heat dissipation performance. The setting of the internal turbulence element of the variable diameter pulsating heat pipe heterogeneous turbulence unit makes the flow in the pulsating heat pipe present an unstable pulsation and local turbulence state, which can significantly improve the heat transfer performance, and its wall surface heat transfer coefficient It is characterized by the following formula: , where is the heat transfer coefficient of the wall surface of the heterogeneous turbulent flow unit of the variable diameter pulsating heat pipe, W / (m 2 K); is the complementary error function; t is the heating time, s; λ is the thermal conductivity, W / (m·K); ρ is the density of the working fluid in the pipe, kg / m³; c p is the specific heat capacity at constant pressure, J / (kg·K); T 0 is the initial temperature of the working medium in the tube, K; T g is the working medium temperature in the tube, K; T w is the wall temperature of the heterogeneous turbulence unit of the variable diameter pulsating heat pipe, K.

[0012] Compared with the traditional pulsating heat pipe, the heterogeneous turbulence and variable diameter structure of the present invention can significantly improve the Nusselt number ( Nu ), thereby improving heat transfer efficiency, improving temperature uniformity, extending battery cycle life and improving system safety, with the following characteristics and beneficial effects: This invention utilizes heterogeneous turbulence and a variable diameter structure within the pulsating heat pipe to induce more intense oscillations and localized turbulence in the working fluid, thereby accelerating the phase change process and enabling rapid heat transfer between the evaporation and condensation zones. This structure not only improves the heat transfer efficiency between the evaporation and condensation sections but also optimizes the heat pipe's startup performance and temperature response characteristics. It offers advantages such as low thermal resistance, uniform heat transfer, and high heat dissipation efficiency, significantly enhancing the radiator's overall heat exchange performance.

[0013] The present invention periodically arranges a semicircular rib turbulence enhancement structure along the axial direction on the inner wall of the heterogeneous turbulence unit of the variable-diameter pulsating heat pipe, which can effectively destroy the laminar boundary layer and induce local eddy currents in the groove area, thereby significantly enhancing the churning frequency and heat exchange rate of the gas-liquid phase change medium between the evaporation section and the condensation section of the pulsating heat pipe.

[0014] In this invention, the semicircular rib spoiler enhancement structure reduces the thermal driving force required during startup, allowing the heat load in each area of ​​the pulsating heat pipe to be rationally regulated, effectively reducing local hot spots and lowering temperature differences, allowing the device to quickly enter a stable operating state under a low initial heat load. Furthermore, the optimization of the overall heat transfer channel ensures that the heat generated by the power battery is quickly absorbed and transferred to the interior of the heat pipe, shortening the thermal response time and ensuring that the battery maintains excellent heat dissipation capabilities under high-load conditions.

[0015] Due to their unique structure, traditional pulsating heat pipes are prone to uneven distribution of the working fluid and localized imbalances in the vapor-liquid ratio, which can lead to dry-burning or circulation problems. To address this issue, the present invention employs an asymmetric "L"-shaped pipe structure, creating a more rational return path for the working fluid between the evaporation and condensation sections. The turbulent structure also stimulates localized interfacial disturbances, enhancing vapor-liquid mixing and further improving phase change efficiency and pulsation driving force. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is an external structural diagram of a pulsating heat pipe heat dissipation device based on heterogeneous turbulence and variable diameter structure enhancement according to an embodiment of the present invention; Figure 2 This is a diagram showing the internal structure of a pulsating heat pipe heat dissipation device based on heterogeneous turbulence and variable diameter structure enhancement according to an embodiment of the present invention; Figure 3 This is a comparison chart of the battery surface temperature after the battery operating power is 3C and the operating time is 30 minutes, showing the heat dissipation of the variable diameter pulsating heat pipe heterogeneous turbulent unit of the present invention and the heat dissipation of the conventional pulsating heat pipe; Figure 4 A comparison chart of the thermal resistance of the variable-diameter pulsating heat pipe heterogeneous turbulent unit heat dissipation element of the present invention and the traditional pulsating heat pipe heat dissipation element versus temperature; Figure 5This is a comparison chart of the equivalent thermal conductivity of the variable-diameter pulsating heat pipe heterogeneous turbulent unit heat dissipation element of the present invention and the traditional pulsating heat pipe heat dissipation element as a function of temperature.

[0017] In the figure: 1. Variable diameter pulsating heat pipe heterogeneous turbulence unit; 1-1. Pulsating heat pipe evaporation section; 1-2. Pulsating heat pipe condensation section; 1-3. Turbulence enhancement structure; 2. Heat conduction plate between battery cells; 2-1. Bottom of heat conduction plate between battery cells; 3. Base heat conduction plate; 3-1. Top of base heat conduction plate; 4. Cooling interface plate; 5. Groove structure; 6. Battery cell; 6-1. Front row battery cell; 6-2. Rear row battery cell. DETAILED DESCRIPTION

[0018] The present invention is described in detail below in conjunction with specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0019] In order to solve the problems that traditional pulsating heat pipes usually adopt equal-diameter channels, and the internal flow is mainly composed of naturally formed gas and liquid plugs, resulting in startup delay, high thermal resistance and uneven temperature distribution, the present invention provides a pulsating heat pipe heat dissipation device based on heterogeneous turbulence and variable diameter structure reinforcement. The pulsating heat pipe heat dissipation device effectively breaks the laminar flow state in the pulsating heat pipe by arranging heterogeneous turbulence structures of different sizes or arrangements inside the pulsating heat pipe, improves the formation frequency and flow stability of bubbles and liquid plugs, and at the same time, enhances the local pressure difference through the variable diameter structure, optimizes the circulation path of the working medium, and significantly improves the heat exchange efficiency of the pulsating heat pipe, thereby improving the overall heat dissipation performance of the power battery.

[0020] See Figure 1 、 Figure 2The present invention is a pulsating heat pipe heat dissipation device based on heterogeneous turbulence and variable diameter structure reinforcement, comprising a variable diameter pulsating heat pipe heterogeneous turbulence unit 1, a heat conducting plate 2 between battery cells, a base heat conducting plate 3 and a cooling interface plate 4, all of which are made of copper with a thermal conductivity of 398.7. W / (m·K), the inter-cell heat conduction plate 2 is vertically placed between the front battery cell 6-1 and the rear battery cell 6-2, with the bottom orthogonal to the base heat conduction plate 3, and a groove structure 5 is provided inside it; the base heat conduction plate 3 is arranged horizontally, and is tightly connected to the bottom of the inter-cell heat conduction plate 2 and the bottom of the battery cell 6 respectively; the cooling interface plate 4 is arranged horizontally, and is tightly connected to the top of the inter-cell heat conduction plate 2 and the top of the battery cell 6 respectively; the variable diameter pulsating heat pipe heterogeneous perturbation unit 1 is an asymmetric serpentine pipe structure formed by bending a capillary tube with non-uniform inner diameter, and connecting multiple sections of pulsating heat pipe evaporation sections 1-1 and multiple sections of pulsating heat pipe condensation sections 1-2 end to end. The upper end passes through the cooling interface plate 4 and leaks out, and the lower end passes through the cooling interface plate 4. The heat conducting plate 2 passing through the battery cells extends into the base heat conducting plate 3. The different lengths and diameters of the various pipes in the asymmetric serpentine pipe structure will cause differences in the flow paths between the pipes, thereby generating non-uniform flow resistance and pressure difference driving force during the flow of the working fluid, which can stimulate stronger pulsating heat exchange and phase change cycles, and improve the overall heat transfer performance. Specifically, the pulsating heat pipe evaporation section 1-1 is located at the lower part of the cooling interface plate 4, and is asymmetrically distributed in an "L" shape front to back. The vertical part is located in the groove structure 5, and the horizontal part is arranged in the base heat conducting plate 3. The upper end of the pulsating heat pipe condensation section 1-2 is exposed to the outside of the upper part of the cooling interface plate 4, and cooperates with an external air cooling or liquid cooling system to achieve rapid heat dissipation. Among them, the pulsating heat pipe evaporation section 1-1 can also be designed to be a shape in which the vertical section and the L-shaped section are arranged at intervals, and the L-shaped section is asymmetrically distributed front to back.

[0021] To significantly enhance the churning frequency and heat exchange rate of the gas-liquid phase change medium between the evaporator and condenser sections of the pulsating heat pipe, the evaporator section 1-1 and the condenser section 1-2 of the pulsating heat pipe are periodically provided with multiple turbulence enhancement structures 1-3 along the axial direction. These turbulence enhancement structures 1-3 are staggered and, in conjunction with the variable diameter flow channels, form multi-stage disturbance zones on the inner wall, promoting more intense oscillatory flow and non-uniform phase change behavior of the working fluid within the pulsating heat pipe. In this embodiment, the turbulence enhancement structures 1-3 are composed of a series of semicircular ribs, each rib height being 0.3 to 0.5 times the inner diameter of the corresponding pulsating heat pipe evaporator section 1-1 and the multi-section pulsating heat pipe condenser section 1-2.

[0022] As the temperature of the power battery rises during operation, the heat generated by the battery is rapidly transferred to the evaporation area of ​​the variable diameter pulsating heat pipe heterogeneous turbulence unit 1, namely the pulsating heat pipe evaporation section 1-1, through the base heat conduction plate 3 in close contact with the battery. The working fluid in this area absorbs heat and undergoes a gas-liquid phase change. The present invention adopts a heterogeneous turbulence and variable diameter structure to effectively promote the circulation of steam in the pipe, thereby achieving a balanced distribution of heat in the entire pulsating heat pipe vacuum cavity. The design of the heterogeneous turbulence destroys the traditional laminar flow state, introduces local turbulence and pulsating flow, and enhances the heat exchange efficiency between the pulsating heat pipe evaporation section 1-1 and the pulsating heat pipe condensation section 1-2. At the same time, heat is transferred from the pulsating heat pipe evaporation section 1-1 to the pulsating heat pipe condensation section 1-2, and the steam releases latent heat and condenses into liquid. The liquid flows back to the pulsating heat pipe evaporation section 1-1 under the action of gravity, forming a stable circulation system.

[0023] By leveraging the periodic phase change behavior and unsteady oscillatory flow of the working fluid within the tube, this power battery heat dissipation device effectively reduces the temperature gradient on the surface of the pulsating heat pipe and improves heat dissipation. In this embodiment, the pulsating heat pipe achieves excellent overall heat transfer performance through the coupling effect of structural perturbations and working fluid phase changes. The device is compact and easy to integrate, making it suitable for a variety of power battery module thermal management scenarios.

[0024] Specifically, the variable-diameter pulsating heat pipe heterogeneous turbulence unit 1 of the present invention adopts an upper and lower asymmetric tube diameter design: the upper pulsating heat pipe condensation section 1-2 uses a copper tube with an inner diameter of 3mm, while the lower pulsating heat pipe evaporation section 1-1 adopts a copper tube structure with an inner diameter of 4mm. This variable-diameter layout helps to form a natural potential difference under the gravitational field, improve the reflux stability of the working fluid, and effectively guide the vapor-liquid phase change working fluid to form a non-uniform flow path within the heat pipe, thereby enhancing the pulsation excitation and continuous circulation capabilities. This tube diameter scheme has been calculated to meet the typical pulsating heat pipe startup criterion—the Bond number (Bo) must be greater than 2.0. This helps to ensure an effective balance between capillary force and gravity, enhance the working fluid interface disturbance and bubble generation, and ultimately significantly improve the heat exchange startup response speed and heat transfer efficiency.

[0025] Specifically, the pulsating heat pipe condenser section 1-2 of the present invention is tightly coupled with an external air or liquid cooling system to rapidly release heat. Meanwhile, the pulsating heat pipe evaporator section 1-1 forms a well-coupling interface with the inter-cell heat conducting plate 2 and the base heat conducting plate 3, ensuring a stable and uniform thermal environment for the battery cells 6 even under high-power operation. This device not only reduces the risk of localized overheating but also improves the thermal responsiveness and operational reliability of the battery system. It is particularly suitable for thermal management applications in new energy vehicles, which require stringent temperature control under conditions such as high-rate discharge or fast charging.

[0026] The present invention is designed based on the principle of nonlinear oscillation and alternating driving of working fluid gas-liquid plug. The internal channel structure introduces a combination of heterogeneous turbulence and variable diameter configuration to break the laminar boundary and enhance the local phase change activity. Specifically, the interior of the pulsating heat pipe is pre-evacuated and infused with an appropriate amount of working fluid, such as water, methanol or ethanol. The selected working fluid can achieve rapid boiling and condensation under the working state, thereby efficiently circulating heat transfer between the evaporation zone and the condensation zone, reducing the thermal resistance of the system. When the power battery generates heat during operation, the heat is first transferred through the inter-cell heat conduction plate 2 that is tightly fitted with the battery cell 6, and then through the base heat conduction plate 3 to the pulsating heat pipe evaporation section 1-1 of the variable diameter pulsating heat pipe heterogeneous turbulence unit 1. The phase change working fluid pre-filled in the pulsating heat pipe evaporation section 1-1 will produce violent vapor-liquid alternating motion and generate bubbles after absorbing heat. These bubbles will break the original flow field balance during the rapid expansion process, causing high-frequency pulsating disturbances, causing the working fluid to oscillate in the variable diameter pulsating section 1-1. Irregular oscillations and reflux paths are formed inside the heat pipe heterogeneous perturbation unit 1, forming high-pressure working fluid vapor; driven by the internal pressure difference, the high-pressure working fluid vapor will flow to the pulsating heat pipe condensation section 1-2, and release latent heat to condense into liquid during contact with the cooling interface plate 4. Driven by gravity, the condensed liquid flows back to the pulsating heat pipe evaporation section 1-1, completing a closed-loop thermal cycle process. During this process, the steam carries heat to achieve rapid transfer within the cavity, thereby effectively improving the thermal diffusion capacity of the system. At the same time, the nonlinear oscillation mechanism provides a continuous self-excited driving force for the working fluid, thereby significantly reducing the temperature gradient of the heat exchange surface and improving the overall heat transfer efficiency of the pulsating heat pipe. In order to further expand the heat dissipation area, multiple parallel variable-diameter pulsating heat pipe heterogeneous perturbation units 1 can be arranged in the heat dissipation structure to form a compact and efficient thermal management module, which is suitable for thermal control scenarios of high-power power batteries.

[0027] Figure 3In order to compare and analyze the battery surface temperature under the condition of continuous discharge of the power battery at a 3C rate for 30 minutes, the heat dissipation of the battery by the variable diameter pulsating heat pipe heterogeneous turbulent unit and the conventional pulsating heat pipe was compared. The results showed that under the traditional pulsating heat pipe heat dissipation condition, the battery temperature continued to rise with the working time, and there was obvious heat accumulation. The maximum surface temperature was measured to be 48.73℃ and the average temperature was 48.27℃. Under high-rate discharge conditions, it is easy to cause local overheating of the battery cell, and there is a high risk of thermal runaway. In contrast, after adopting the variable diameter pulsating heat pipe heterogeneous turbulent unit heat dissipation element of the present invention, the battery surface temperature was significantly reduced, and the overall temperature tended to be average. The maximum temperature was measured to be 45.7℃ and the average temperature was 45.61℃. Compared with the conventional pulsating heat pipe heat dissipation, the device can reduce the maximum temperature of the battery by about 6.22% and the average temperature by about 5.51%, effectively suppressing heat accumulation and significantly improving the heat dissipation efficiency and thermal field uniformity. It can be seen that the present invention introduces a variable-diameter channel and a periodic heterogeneous turbulence structure inside the pulsating heat pipe and adopts an asymmetric structural arrangement, which can effectively regulate the oscillation behavior of the working medium between the evaporation section and the condensation section, enhance the flow disturbance and phase change process in the heat transfer path, and thus achieve synergistic optimization of the flow characteristics and heat transfer performance.

[0028] Figure 4 The graph of thermal resistance of the variable diameter pulsating heat pipe heterogeneous turbulent unit heat dissipation element and the conventional pulsating heat pipe heat dissipation element with temperature changes is shown in FIG. Figure 4 It can be seen that as the heat source temperature increases, the thermal resistance of the variable-diameter pulsating heat pipe heterogeneous turbulent flow unit heat dissipation element of the present invention decreases significantly, and the heat transfer capacity shows a performance trend that is better than that of conventional pulsating heat pipe heat dissipation elements. When the heat source temperature rises to 80°C, the minimum thermal resistance of the conventional pulsating heat pipe heat dissipation element is 0.0223 K / W, while the minimum thermal resistance of the variable-diameter pulsating heat pipe heterogeneous turbulent flow unit heat dissipation element implemented by the present invention is 0.00848 K / W, a decrease of 61.97%; Figure 5 The graph of the equivalent thermal conductivity of the variable diameter pulsating heat pipe heterogeneous turbulent unit heat dissipation element and the conventional pulsating heat pipe heat dissipation element with temperature changes is shown in FIG. Figure 5It can be seen that the maximum equivalent thermal conductivity of the heat dissipation element of the conventional pulsating heat pipe is 215.42 W / (m·K), while the maximum equivalent thermal conductivity of the heat dissipation element of the variable diameter pulsating heat pipe heterogeneous turbulence unit implemented by the present invention can reach 587.5 W / (m·K), an increase of 172.7% compared with the previous embodiment. The main reason is that the present invention introduces a heterogeneous turbulence structure inside the pulsating heat pipe, combined with the structural optimization of the variable diameter channel, to form a driving environment where flow asymmetry and potential difference coexist. The resistance and pressure difference encountered by the working fluid in different areas of the channel are inconsistent, causing it to deviate and flow in the direction of less resistance, forming a stable unidirectional pulsating path. This design not only speeds up the startup response speed of the heat pipe, but also effectively improves the heat exchange rate between the evaporation section and the condensation section, reduces the overall thermal resistance, and improves the thermal conductivity.

[0029] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely preferred examples of the present invention and are not intended to limit the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and improvements fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A pulsating heat pipe heat dissipation device based on heterogeneous turbulence and variable diameter structure reinforcement, characterized by: The invention comprises a base heat conduction plate (3), a cooling interface plate (4), an inter-cell heat conduction plate (2) and a variable diameter pulsating heat pipe heterogeneous perturbation unit (1) arranged between two rows of battery cells (6); the variable diameter pulsating heat pipe heterogeneous perturbation unit (1) is an asymmetric serpentine pipe structure formed by bending a capillary tube with a non-uniform inner diameter; the upper end of the variable diameter pulsating heat pipe heterogeneous perturbation unit (1) passes through the cooling interface plate (4) and leaks outward, and the lower end passes through the inter-cell heat conduction plate (2) and extends into the base heat conduction plate (3); and the interior of the variable diameter pulsating heat pipe heterogeneous perturbation unit (1) is periodically provided with a plurality of perturbation enhancement structures (1-3) along the axial direction, and the plurality of perturbation enhancement structures (1-3) are arranged in a staggered manner.

2. The pulsating heat pipe heat dissipation device based on heterogeneous turbulence and variable diameter structure enhancement according to claim 1, characterized in that: The base heat conduction plate (3) is tightly connected to the bottom of the inter-cell heat conduction plate (2) and the bottom of the battery cell (6), respectively; the cooling interface plate (4) is tightly connected to the top of the inter-cell heat conduction plate (2) and the top of the battery cell (6).

3. The pulsating heat pipe heat dissipation device based on heterogeneous turbulence and variable diameter structure enhancement according to claim 1, characterized in that: The variable diameter pulsating heat pipe heterogeneous turbulence unit (1) is formed by connecting multiple sections of pulsating heat pipe evaporation sections (1-1) and multiple sections of pulsating heat pipe condensation sections (1-2) end to end, and the pulsating heat pipe evaporation sections (1-1) and the pulsating heat pipe condensation sections (1-2) are independently interconnected and have a stable liquid-gas phase change space; the inter-cell heat conduction plate (2) is vertically placed between two rows of battery cells (6), and a groove structure (5) is provided inside the inter-cell heat conduction plate.

4. The pulsating heat pipe heat dissipation device based on heterogeneous turbulence and variable diameter structure enhancement according to claim 3, characterized in that: The pulsating heat pipe evaporation section (1-1) is located at the lower part of the cooling interface plate (4), and is asymmetrically distributed in an "L" shape front to back, with the vertical portion located in the groove structure (5) and the horizontal portion arranged in the base heat conduction plate (3); the upper end of the pulsating heat pipe condensation section (1-2) is exposed to the upper part of the cooling interface plate (4), and cooperates with an external air cooling or liquid cooling system to achieve rapid heat dissipation.

5. The pulsating heat pipe heat dissipation device based on heterogeneous turbulence and variable diameter structure enhancement according to claim 3, characterized in that: A plurality of flow disturbance enhancement structures (1-3) are periodically provided in the axial direction inside the pulsating heat pipe evaporation section (1-1) and the pulsating heat pipe condensation section (1-2), and the plurality of flow disturbance enhancement structures (1-3) are arranged in a staggered manner.

6. The pulsating heat pipe heat dissipation device based on heterogeneous turbulence and variable diameter structure enhancement according to claim 5, characterized in that: The turbulence enhancement structure (1-3) is composed of a series of semicircular ribs, the rib height of the semicircular ribs is 0.3 to 0.5 times the corresponding inner pipe diameter, and is periodically arranged along the axial direction of the inner wall of the pulsating heat pipe evaporation section (1-1) and the pulsating heat pipe condensation section (1-2).

7. The pulsating heat pipe heat dissipation device based on heterogeneous turbulence and variable diameter structure enhancement according to claim 1, characterized in that: The plurality of flow enhancement structures (1-3) make the flow in the variable diameter pulsating heat pipe heterogeneous flow enhancement unit (1) present an unstable pulsation and local turbulence state, and the wall surface heat transfer coefficient It is characterized by the following formula: ，， Where, is the heat transfer coefficient of the wall surface of the heterogeneous turbulent flow unit of the variable diameter pulsating heat pipe, W / (m 2 K); is the complementary error function; t is the heating time, s; λ is the thermal conductivity, W / (m·K); ρ is the density of the working fluid in the pipe, kg / m³; c p is the specific heat capacity at constant pressure, J / (kg·K); T 0 is the initial temperature of the working medium in the tube, K; T g is the working medium temperature in the tube, K; T w is the wall temperature of the heterogeneous turbulence unit of the variable diameter pulsating heat pipe, K.

Images