Composite two-stage core flat plate type loop heat pipe evaporator and loop heat pipe system

Abstract

The utility model discloses a composite two-stage core flat plate type loop heat pipe evaporator and a loop heat pipe system, and relates to the technical field of heat dissipation, the composite two-stage core flat plate type loop heat pipe evaporator comprises an evaporation mechanism and a loop pipeline mechanism, the evaporation mechanism comprises an evaporator upper shell, an evaporator lower shell, a first-stage liquid absorption core and a second-stage liquid absorption core, the evaporator upper shell is of a flat plate type cavity structure, and the loop pipeline mechanism comprises a first steam pipeline, a second steam pipeline, a third steam pipeline, a stainless steel ferrule type elbow, a liquid pipeline and jacket type condensing equipment. Efficient heat dissipation of a high-heat-flux and complex heat source environment is achieved, the heat transfer performance and stability of the loop heat pipe system are remarkably improved, and the loop heat pipe system can be widely applied to the fields of electronic equipment heat dissipation, spacecraft thermal control, industrial thermal management and the like.

Description

Technical Field

[0001] This utility model relates to the field of heat dissipation technology, and in particular to a composite two-stage core flat plate type loop heat pipe evaporator and loop heat pipe system. Background Technology

[0002] Loop heat pipes are a highly efficient thermal control technology widely used in aerospace, electronic device heat dissipation, and industrial thermal management. Loop heat pipes achieve efficient heat transfer through phase change heat transfer and capillary actuation; the performance of its core component—the evaporator—directly determines the system's heat transfer efficiency and stability.

[0003] Flat-plate evaporators are widely used for heat dissipation in electronic devices due to their compact structure and suitability for contact with planar heat sources. As electronic devices and spacecraft evolve towards higher power density and miniaturization, higher demands are placed on the heat transfer performance and structural compactness of thermal control systems. Traditional loop heat pipe systems struggle to simultaneously achieve high heat transfer efficiency and miniaturized design, failing to meet the heat dissipation requirements of new high-performance equipment. Therefore, it is necessary to develop a loop heat pipe system with both high heat transfer efficiency and miniaturization advantages, where the liquid storage chamber and gas collection chamber are distributed on the left and right sides of the wick to reduce thickness and increase space utilization.

[0004] Evaporators in flat-plate loop heat pipes typically employ a single capillary wick structure. While this structure offers decent heat transfer performance in low heat flux density scenarios, it is prone to drying out under high heat flux density conditions, leading to increased thermal resistance and decreased system performance. Furthermore, the single-wick structure has poor adaptability to complex heat source conditions, limiting its application in high-performance heat dissipation.

[0005] With the increasing severity of thermal problems in electronic components, and the fact that they cannot be simply considered as ideal conditions with a single stable heat source during operation, it is crucial to develop a flat-plate loop heat pipe that can respond quickly and dissipate heat from multiple or unstable high heat flux density heat sources. Utility Model Content

[0006] The purpose of this invention is to provide a composite two-stage core flat-plate loop heat pipe evaporator and loop heat pipe system to solve at least one of the problems mentioned in the background art.

[0007] To achieve the above objectives, this utility model provides the following technical solution: a composite two-stage core flat plate type loop heat pipe evaporator and loop heat pipe system, including an evaporation mechanism and a loop pipe mechanism;

[0008] The primary and secondary liquid-absorbing cores are described. The primary liquid-absorbing core is located in the middle left side of the evaporation chamber, and the secondary liquid-absorbing core is located in the channel at the top of the primary liquid-absorbing core. The bottom of the primary liquid-absorbing core has multiple equally spaced vapor channels, which are rectangular grooves and each vapor channel has the same specifications.

[0009] Preferably, the evaporation mechanism further includes an upper evaporator shell and a lower evaporator shell. The upper evaporator shell has a flat cavity structure. The bottom of the upper evaporator shell is fixedly connected to the top of the lower evaporator shell, and the upper evaporator shell and the lower evaporator shell together form an evaporation chamber. The right side of the primary liquid absorption core and the secondary liquid absorption core in the evaporation chamber is a liquid storage chamber, and the left side of the primary liquid absorption core and the secondary liquid absorption core in the evaporation chamber is a gas collection chamber. An air outlet is provided at the middle position on the left side of the upper evaporator shell, and a liquid inlet is provided at the middle position near the right side of the front end of the upper evaporator shell.

[0010] Preferably, the primary suction core is made of a highly thermally conductive porous material with a pore size range of 5-20 μm and a porosity of 50%-70%. The secondary suction core is made of a material with high capillary driving force, with a width of 1-2 mm and a length of 1-2 mm for each vapor channel.

[0011] Preferably, the tops of the primary and secondary liquid suction cores abut against the upper outer shell of the evaporator, the bottom of the primary liquid suction core and the steam channel abut against the lower outer shell of the evaporator, both the primary and secondary liquid suction cores are connected to the liquid storage chamber, and the gas collection chamber is connected to the steam channel.

[0012] Preferably, the lower outer shell of the evaporator is made of copper, and the upper outer shell of the evaporator is made of stainless steel. The lower outer shell and the upper outer shell of the evaporator are connected by silver solder to ensure their airtightness, and the thickness of the silver solder is 1.5mm-3.0mm.

[0013] The loop piping system includes a first steam line, a second steam line, and a third steam line, a stainless steel compression elbow, a liquid line, and a jacketed condenser. The first steam line, the second steam line, the third steam line, and the liquid line form a loop piping system. One end of the first steam line is connected to the steam outlet, and the third steam line is detachably connected to the stainless steel compression elbow. The other end of the stainless steel compression elbow is detachably connected to the liquid line, and the other end of the liquid line is connected to the liquid inlet of the upper shell of the evaporator. The jacketed condenser is detachably connected to the liquid line.

[0014] Preferably, a heat source is provided on the lower outer shell of the evaporator directly below the primary liquid absorption core. The heat source is adhered to the bottom of the lower outer shell of the evaporator by applying thermally conductive silicone grease with a thermal conductivity of 10-16.8 W / m·K.

[0015] Preferably, the first steam pipeline, the second steam pipeline, and the third steam pipeline are all made of copper. The copper pipeline is bent at the bending points of the first and second steam pipelines using a pipe bender. The liquid pipeline is made of copper.

[0016] Preferably, the first steam pipeline is connected to the gas outlet on the left side of the upper outer shell of the evaporator by silver soldering, and the liquid pipeline is connected to the liquid inlet at the front end of the upper outer shell of the evaporator by argon arc welding.

[0017] The beneficial effects of this utility model are as follows:

[0018] 1. This utility model adopts a composite two-stage core structure design. The first-stage wick absorbs heat and provides initial capillary driving force, while the second-stage wick enhances the liquid reflux capability and provides additional capillary driving force. The two work together to improve the liquid supply efficiency, solve the problem of easy drying under high heat flux density in single capillary core structures, reduce the risk of drying, and significantly improve the heat transfer performance of the system. The structure of the first-stage and second-stage wicks and their coordination with other components optimize the working fluid circulation path, making heat transfer more efficient.

[0019] 2. The composite two-stage core structure of this utility model can be customized according to the distribution of different heat sources. Whether it is a dynamic heat source or a high power density scenario, it can respond quickly and achieve stable heat dissipation. It shows good adaptability in complex heat source environments and broadens the application range of loop heat pipe systems.

[0020] 3. By optimizing the capillary wick material, the design of the guide groove, and the layout of the working fluid flow channel, this utility model enables the system to have excellent heat transfer uniformity. During operation, it can effectively control the temperature fluctuation of the heat source and reduce the impact of temperature changes on the system performance. Compared with traditional systems, the stability is greatly improved. Attached Figure Description

[0021] Figure 1 This is a three-dimensional structural diagram of the present invention;

[0022] Figure 2 This is a cross-sectional view of the evaporator of this utility model;

[0023] Figure 3 This is a three-dimensional structural diagram of the primary and secondary liquid absorption cores of this utility model;

[0024] Figure 4 This is a front cross-sectional view of the primary and secondary suction cores of this utility model;

[0025] Figure 5 This is a sectional view of the evaporator of this utility model;

[0026] Figure 6 This is a sectional view of the liquid absorption core of this utility model;

[0027] Figure 7 This is a side sectional view of the evaporator of this utility model;

[0028] Figure 8 This is a cross-sectional view of the gas collection chamber of this utility model.

[0029] In the diagram: 1. Upper outer shell of the evaporator; 2. Lower outer shell of the evaporator; 3. Jacketed condenser; 4. Second steam pipeline; 5. Bend point of the first steam pipeline; 6. Third steam pipeline; 7. First steam pipeline; 8. Gas collection chamber; 9. Steam channel; 10. Primary liquid suction core; 11. Secondary liquid suction core; 12. Liquid storage chamber; 13. Gas outlet; 14. Liquid inlet; 15. Liquid pipeline; 16. Stainless steel compression elbow; 17. Bend point of the second steam pipeline. Detailed Implementation

[0030] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0031] This utility model provides, for example Figure 1-8 The invention relates to a composite two-stage core flat-plate loop heat pipe evaporator and loop heat pipe system, including an evaporation mechanism and a loop pipe mechanism.

[0032] The evaporation mechanism includes an upper evaporator shell 1, a lower evaporator shell 2, a primary liquid suction core 10, and a secondary liquid suction core 11. The upper evaporator shell 1 has a flat, hollow structure. The bottom of the upper evaporator shell 1 is fixedly connected to the top of the lower evaporator shell 2, and the upper evaporator shell 1 and the lower evaporator shell 2 together form an evaporation chamber. The primary liquid suction core 10 is located in the middle left side of the evaporation chamber. The secondary liquid suction core 11 is located in the channel at the top of the primary liquid suction core 10. The bottom of the primary liquid suction core 10 has multiple steam channels 9 at equal intervals. The steam channels 9 are rectangular grooves, and each steam channel 9 has the same specifications. To the right of the primary liquid suction core 10 and the secondary liquid suction core 11 in the evaporation chamber is a liquid storage chamber 12, and to the left of the primary liquid suction core 10 and the secondary liquid suction core 11 in the evaporation chamber is a gas collection chamber 8. An outlet 13 is located at the middle left side of the outer casing 1, and a liquid inlet 14 is located at the middle right side of the front end of the upper outer casing 1 of the evaporator. The loop piping mechanism includes a first steam line 7, a second steam line 4, a third steam line 6, a stainless steel compression elbow 16, a liquid line 15, and a jacketed condenser 3. The first steam line 7, the second steam line 4, the third steam line 6, and the liquid line 15 form a loop piping system. One end of the first steam line 7 is connected to the outlet 13, and the third steam line 6 is detachably connected to the stainless steel compression elbow 16. The other end of the stainless steel compression elbow 16 is detachably connected to the liquid line 15, and the other end of the liquid line 15 is connected to the liquid inlet 14 of the upper outer casing 1 of the evaporator. The jacketed condenser 3 is detachably connected to the liquid line 15.

[0033] When using this evaporator, the heat source transfers heat to the working fluid (which can be any one of water, R141b, acetone, etc.) through the primary wick 10. The working fluid evaporates to form steam and is discharged into the gas collection chamber 8 through the steam channel 9. It then overflows from the outlet 13 and flows along the first steam pipeline 7, the second steam pipeline 4, the third steam pipeline 6 and the stainless steel compression elbow 16 into the liquid pipeline 15, which is enclosed by the jacketed condenser 3. The jacketed condenser 3 condenses the steam in the liquid pipeline 15 into liquid. The condensed working fluid flows into the liquid storage chamber 12 through the inlet 14 and, under the action of the heat source, flows back into the gas phase through the primary wick 10 and the secondary wick 11, forming a complete flow cycle.

[0034] The primary liquid suction core 10 is made of a highly thermally conductive porous material with a pore size range of 5-20 μm and a porosity of 50%-70%. The secondary liquid suction core 11 is made of a material with high capillary driving force and a width of 1-2 mm. The steam channel 9 has a size of 1-2 mm.

[0035] The primary wick 10, made of a highly thermally conductive porous material, can quickly transfer heat from the heat source to the working fluid, accelerating the vaporization rate of the working fluid and improving the heat transfer efficiency of the evaporator. Its suitable pore size and porosity provide a favorable vaporization environment for the working fluid, ensuring a balance between heat transfer and liquid supply, which is beneficial to the vaporization process. The secondary wick 11, made of a material with high capillary driving force, enhances the liquid reflux capability, allowing the condensed liquid working fluid to return more smoothly to the evaporator cavity, ensuring the circulation efficiency of the working fluid within the system and maintaining stable system operation. Furthermore, the secondary wick 11 provides additional capillary driving force, working in conjunction with the primary wick 10 to further promote the circulation of the working fluid within the system. Especially under high heat flux density conditions, it can effectively supplement power and prevent drying out. In addition, the secondary wick 11 can also prevent vapor generated by unfavorable heat leakage from flowing back into the liquid storage chamber 12. The steam channel 9 is designed with a size of 1-2mm, which meets the requirements for sufficient nucleation points and gas phase channels, while increasing the contact area with the uniform heat source of the bottom copper plate and improving the gasification efficiency.

[0036] The tops of the primary liquid suction core 10 and the secondary liquid suction core 11 abut against the upper outer shell 1 of the evaporator, and the bottom of the primary liquid suction core 10 and the steam channel 9 abut against the lower outer shell 2 of the evaporator.

[0037] The primary wick 10 and secondary wick 11 are tightly abutted against the upper and lower outer shells of the evaporator, providing stable support for the internal structure of the evaporator; reducing heat loss during the transfer process and improving the heat transfer performance of the entire system; the primary wick 10 abuts against the lower outer shell 2 of the evaporator, ensuring that the gaseous working fluid in the steam channel 9 can flow smoothly into the gas collecting chamber 8 without leakage or mixing; the secondary wick 11 abuts against the upper outer shell 1 of the evaporator, effectively guiding liquid backflow and preventing liquid from entering the gas collecting chamber, ensuring the stability of vapor-liquid separation, thereby improving the operating efficiency of the system; the tight abutment connection enhances the airtightness of the evaporator to a certain extent.

[0038] The primary liquid suction core 10 and the secondary liquid suction core 11 are both connected to the liquid storage chamber 12, and the gas collection chamber 8 is connected to the steam channel 9.

[0039] The liquid storage chamber 12 is used to collect and evenly distribute the condensate generated during condensation. The primary wicking core 10 and the secondary wicking core 11 are connected to the liquid storage chamber 12, ensuring that the liquid working fluid can be continuously replenished to the wicking core, preventing the wicking core from drying out, and avoiding the impact of improper condensate distribution on system performance. The gas collecting chamber 8 is connected to the steam channel 9, preventing the accumulation of gaseous working fluid in the evaporator, ensuring the smooth progress of the evaporation process, facilitating the continuous transfer of heat from the heat source to the working fluid, and then cooling through the flow of the gaseous working fluid, ensuring the continuity of heat transfer in the system, achieving efficient heat transfer, and completing the working fluid circulation process.

[0040] The lower outer shell 2 of the evaporator is made of copper, and the upper outer shell 1 of the evaporator is made of stainless steel. The lower outer shell 2 and the upper outer shell 1 of the evaporator are connected by silver solder to ensure their airtightness, and the thickness of the silver solder is 1.5mm-3.0mm.

[0041] The evaporator is machined using CNC metal welding, facilitating integration with other components of the loop heat pipe system and improving the ease of system assembly and maintenance. Copper, with its excellent thermal conductivity, is used in the lower outer shell 2 of the evaporator, enabling rapid heat transfer from the heat source to the working fluid inside, thus improving the evaporator's heat absorption efficiency. Stainless steel, with its good strength, corrosion resistance, and high-temperature resistance, is used in the upper outer shell 1, ensuring long-term stable operation in complex environments, resisting corrosion damage, and withstanding certain pressures to guarantee system safety. Silver soldering connects the upper outer shell 1 and the lower outer shell 2, with the solder thickness controlled between 1.5mm and 3.0mm. This effectively ensures the evaporator's airtightness, preventing working fluid leakage and maintaining a stable working fluid quantity within the system. Furthermore, the silver soldering strengthens the connection between the upper and lower shells, preventing loosening or separation when the evaporator is subjected to external factors such as vibration and temperature changes.

[0042] The first steam pipeline 7, the second steam pipeline 4, and the third steam pipeline 6 are all made of copper. The copper pipeline is bent at the bending point 5 of the first steam pipeline and the bending point 17 of the second steam pipeline using a pipe bender. The liquid pipeline 15 is made of copper.

[0043] Using a single copper tube bent to form multiple steam pipelines significantly reduces the number of connection points compared to using multiple independent pipes. Reducing the number of connection points improves the airtightness and stability of the entire loop heat pipe system, ensuring long-term reliable operation. It also simplifies the pipe manufacturing process, eliminating the need for complex processing and connection operations on multiple independent pipes, reducing processing steps and material waste, and lowering production costs.

[0044] A heat source is provided on the lower outer shell 2 of the evaporator directly below the primary liquid suction core 10. The heat source is adhered to the bottom of the lower outer shell 2 of the evaporator by applying thermally conductive silicone grease, which has a thermal conductivity of 10-16.8 W / m·K.

[0045] When the heat source generates heat, the thermally conductive grease can quickly transfer the heat to the lower outer shell 2 of the evaporator, and then to the working fluid in the primary wick 10, promoting the evaporation of the working fluid and improving the heat dissipation efficiency of the entire loop heat pipe system. On the other hand, by applying thermally conductive grease to bond the heat source and the lower outer shell 2 of the evaporator, not only is good heat conduction achieved, but the connection stability between the two is also enhanced. The thermally conductive grease has a certain degree of viscosity, which allows the heat source to adhere tightly to the lower outer shell 2 of the evaporator, reducing relative displacement caused by vibration or other external forces. In practical applications, such as when electronic equipment is subjected to vibration during operation, this stable connection method ensures continuous and stable heat transfer, preventing the heat dissipation effect from being affected by loose connections.

[0046] The first steam pipeline 7 is connected to the gas outlet 13 on the left side of the upper outer shell 1 of the evaporator by silver soldering, and the liquid pipeline 15 is connected to the liquid inlet 14 at the front end of the upper outer shell 1 of the evaporator by argon arc welding.

[0047] Both silver soldering and argon arc welding offer excellent welding results, ensuring joint strength and sealing to prevent working fluid leakage. The tight welded connection reduces thermal resistance, allowing heat to be transferred more smoothly from the evaporator to the first steam line 7 via the outlet for the steam line. For the liquid line 15, the heat carried by the liquid working fluid can be transferred more efficiently to the evaporator via the inlet 14. This optimizes the heat transfer path of the entire loop heat pipe system, improving its heat dissipation performance and enabling the heat source to cool down more quickly.

[0048] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A composite secondary loop heat pipe (2) flat-plate evaporator characterized by: The evaporation mechanism comprises a primary wick (10) and a secondary wick (11), the primary wick (10) is arranged in the middle left position in the evaporation cavity, the secondary wick (11) is arranged in the groove on the top of the primary wick (10), the bottom of the primary wick (10) is provided with a plurality of steam grooves (9) at equal intervals, and each steam groove (9) is a rectangular groove with the same specification. The evaporation mechanism further comprises an upper evaporation shell (1) and a lower evaporation shell (2), the upper evaporation shell (1) is in a flat cavity structure, the bottom of the upper evaporation shell (1) is fixedly connected with the top of the lower evaporation shell (2), and the inside of the upper evaporation shell (1) and the lower evaporation shell (2) forms an evaporation cavity, the right side of the primary wick (10) and the secondary wick (11) in the evaporation cavity is a liquid storage chamber (12), the left side of the primary wick (10) and the secondary wick (11) in the evaporation cavity is a gas collection chamber (8), the middle left side of the upper evaporation shell (1) is provided with an air outlet (13), and the middle right side of the front end of the upper evaporation shell (1) is provided with a liquid inlet (14).

2. A composite secondary loop heat pipe flat-plate evaporator according to claim 1, wherein: The primary wick (10) is made of high-thermal-conductivity porous material, the pore size of the primary wick (10) ranges from 5 to 20 μm, and the porosity ranges from 50% to 70%, the secondary wick (11) is made of high-capillary-driving-force material, the width of the secondary wick (11) ranges from 1 to 2 mm, and the length of each steam groove (9) ranges from 1 to 2 mm.

3. A composite secondary loop heat pipe flat-plate evaporator according to claim 2, wherein: The top of the primary wick (10) and the secondary wick (11) abuts against the upper evaporation shell (1), the bottom of the primary wick (10) and the steam groove (9) abuts against the lower evaporation shell (2), the primary wick (10) and the secondary wick (11) are in communication with the liquid storage chamber (12), and the gas collection chamber (8) is in communication with the steam groove (9).

4. A composite secondary loop heat pipe flat-plate evaporator according to claim 3, wherein: The lower evaporation shell (2) is made of red copper, the upper evaporation shell (1) is made of stainless steel, the lower evaporation shell (2) and the upper evaporation shell (1) are connected by silver welding to ensure the air tightness, and the thickness of the silver welding is 1.5 mm-3.0 mm.

5. A composite secondary loop heat pipe flat-plate evaporator according to claim 4, wherein: ​ 6. A loop heat pipe system based on a composite secondary loop heat pipe evaporator, characterized in that, The evaporator based on the composite secondary wick flat plate type loop heat pipe according to any one of claims 1-5 further comprises a first steam pipeline (7), a second steam pipeline (4), a third steam pipeline (6), a stainless steel sleeve elbow (16), a liquid pipeline (15) and a jacketed condensing device (3), the first steam pipeline (7), the second steam pipeline (4), the third steam pipeline (6) and the liquid pipeline (15) form a loop along pipeline, one end of the first steam pipeline (7) is communicated with the gas outlet (13), the third steam pipeline (6) is detachably connected with the stainless steel sleeve elbow (16), the other end of the stainless steel sleeve elbow (16) is detachably connected with the liquid pipeline (15), the other end of the liquid pipeline (15) is communicated with the liquid inlet (14) of the evaporator upper shell (1), and the jacketed condensing device (3) is detachably connected on the liquid pipeline (15).

7. A loop heat pipe system based on a composite two-phase core flat-plate loop heat pipe evaporator according to claim 6, characterized in that: A heat source is arranged outside the evaporator lower shell (2) directly below the primary wick (10), the heat source is adhered to the bottom of the evaporator lower shell (2) by applying heat-conducting silicone grease, and the heat-conducting coefficient of the heat-conducting silicone grease is 10-16.8 W / m·K.

8. A loop heat pipe system based on a composite two-phase core flat-plate loop heat pipe evaporator according to claim 6, characterized in that: The first steam pipeline (7), the second steam pipeline (4) and the third steam pipeline (6) are a red copper pipe, the red copper pipe is bent at the first steam pipeline bending point (5) and the second steam pipeline bending point (17) by using a pipe bender, and the liquid pipeline (15) is made of red copper.

9. A loop heat pipe system based on a composite secondary loop heat pipe evaporator according to claim 6, characterized in that: The first steam pipeline (7) and the gas outlet (13) on the left side of the evaporator upper shell (1) are connected by silver welding, and the liquid pipeline (15) and the liquid inlet (14) at the front end of the evaporator upper shell (1) are welded by argon arc welding.

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