Evaporator component and loop heat pipe

Abstract

The application provides an evaporator component, which comprises an evaporator, a first liquid reservoir, a second liquid reservoir and a capillary core, the first liquid reservoir and the second liquid reservoir are arranged at the left and right ends of the evaporator, the evaporator is filled with the capillary core, the capillary core extends from the middle of the evaporator to the inside of the first liquid reservoir and the second liquid reservoir at the left and right sides, a liquid inlet is arranged at the left side of the first liquid reservoir and the right side of the second liquid reservoir respectively, and two steam outlets are arranged at the upper end of the evaporator. The evaporator is provided with double circuits, adopts a double-inlet and double-outlet form to make the two circuits operate simultaneously, compared with the double liquid reservoir single-inlet and single-outlet evaporator, the two circuits of the evaporator are completely same in the path length of supplementing the working medium, so that the supplement of the working medium is more stable.

Description

Technical Field

[0001] This invention relates to a novel dual-reservoir evaporator, belonging to the field of loop heat pipe technology, specifically the F28d15 / 02 heat pipe field. Background Technology

[0002] Heat pipe technology is a heat transfer element called a "heat pipe" invented by George Grover at Los Alamos National Laboratory in the United States in 1963. It makes full use of the principle of heat conduction and the rapid heat transfer properties of phase change media to quickly transfer the heat of the heated object to the outside of the heat source. Its thermal conductivity exceeds that of any known metal.

[0003] Heat pipe technology, previously widely used in aerospace and military industries, has revolutionized radiator manufacturing since its introduction. It has moved beyond the traditional design approach, moving beyond the reliance on high-airflow motors for optimal cooling. Heat pipe technology has enabled radiators to achieve satisfactory heat exchange, opening up new possibilities in the cooling industry. Currently, heat pipes are widely used in various heat exchange equipment, including in nuclear power and computer fields, such as the utilization of waste heat from nuclear power plants.

[0004] A loop heat pipe is a type of closed-loop heat pipe. It typically consists of an evaporator, a condenser, a liquid receiver, and vapor and liquid lines. Its working principle is as follows: a heat load is applied to the evaporator, causing the working fluid to evaporate on the outer surface of the evaporator capillary. The resulting vapor flows out of the vapor channel and into the vapor line, then enters the condenser where it condenses into liquid and is subcooled. The returning liquid flows through the liquid line into the liquid main to replenish the evaporator capillary. This cycle continues, driven by the capillary pressure generated by the evaporator capillary, requiring no external power. Because the condensation and evaporation sections are separate, loop heat pipes are widely used in integrated energy utilization and waste heat recovery.

[0005] Conventional dual-reservoir loop heat pipes are developed from single-reservoir loop heat pipes, with a reservoir at each end of the evaporator, effectively solving the problem of insufficient liquid supply to the capillary wick within the evaporator. However, the two reservoirs in a conventional dual-reservoir loop heat pipe are at different relative distances, leading to an imbalance in liquid supply to both ends of the capillary wick. This results in insufficient resistance to gravity, impact, and vibration, hindering the improvement of the loop heat pipe's stability under different orientations.

[0006] This invention designs a novel dual-reservoir evaporator component, improving upon the structure of traditional loop heat pipes by employing a symmetrical dual-loop design and a dual-reservoir liquid supply design. This novel evaporator component overcomes the shortcomings of insufficient liquid supply in traditional single-reservoir systems, effectively improving the cooling effect of the reflux liquid on the dual-reservoir structure under different postures in gravity fields or bumpy environments. It ensures that the evaporator component can achieve uniform temperature and stable liquid supply to the capillary wick inside the evaporator in any posture under gravity fields or bumpy environments, enhancing its resistance to gravity, impact, and bumps, and improving the stability of the device. Summary of the Invention

[0007] This invention aims to adapt to different orientations in gravitational or acceleration fields, greatly improving the applicability of heat pipe thermal control systems and at least solving one of the technical problems existing in the prior art or related technologies. This invention proposes a dual-reservoir evaporator component with good integration, high stability, resistance to gravity, vibration, impact, high pressure, and deformation.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows:

[0009] An evaporator component includes an evaporator, a first liquid reservoir, a second liquid reservoir, and a capillary wick. The first and second liquid reservoirs are located at the left and right ends of the evaporator. The evaporator is filled with a capillary wick that extends from the middle of the evaporator to the left and right sides into the first and second liquid reservoirs. Liquid inlets are located on the left side of the first liquid reservoir and the right side of the second liquid reservoir, respectively. Two vapor outlets are located at the upper end of the evaporator.

[0010] As an improvement, the two steam outlets are connected to the capillary wick at positions symmetrical about the middle of the capillary wick.

[0011] As an improvement, the steam outlet is connected to a steam pipe, which is inserted into the capillary wick in the evaporator from the top. The insertion position of the steam pipe into the capillary wick is symmetrical about the middle position of the capillary wick.

[0012] As an improvement, the liquid inlet is connected to a liquid pipeline.

[0013] As an improvement, two liquid lines are inserted into the first and second liquid reservoirs respectively, and holes are provided at the center of both ends of the capillary wick, with the first and second liquid phase lines inserted into the holes of the capillary wick.

[0014] As an improvement, non-connected holes are symmetrically opened at both ends of the capillary core inside the evaporator. A metal wire mesh sub-capillary core is installed inside the holes. Multiple rectangular steam channels of the same length as the capillary core are located around the periphery of the capillary core. Two annular steam channels are symmetrically opened on the left and right sides along the middle of the evaporator.

[0015] As an improvement, the liquid reservoir consists of a liquid storage component and an end cap. The end cap and the liquid storage component are coaxially arranged and connected by welding.

[0016] As an improvement, the bottom of the reservoir is rounded by 1mm.

[0017] As an improvement, the side wall of the reservoir is provided with a through hole.

[0018] A loop heat pipe includes the evaporator components described above.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1) This loop heat pipe has a dual loop, which adopts a dual-inlet and dual-outlet configuration to allow the two loops to operate simultaneously. Compared with a dual-reservoir single-inlet and single-outlet loop heat pipe, the two loops of this loop heat pipe have the same path length for replenishing the working fluid, making the replenishment of the working fluid more stable.

[0021] 2) This loop heat pipe has dual liquid reservoirs symmetrically arranged on both sides of the evaporator. Under special operating conditions such as tilting or acceleration, the contact area between the working fluid and the capillary wick in one liquid reservoir decreases, while the contact area between the working fluid and the capillary wick in the other liquid reservoir inevitably increases. This enables stable replenishment of the working fluid under special operating conditions and avoids the capillary wick from drying out. It can make up for the poor working stability of traditional single liquid reservoirs and has the ability to resist gravity, bumps, and impacts. It can adapt to different orientations in gravitational or acceleration fields, greatly improving the applicability of the heat pipe thermal control system. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a dual-reservoir heat pipe structure according to the present invention;

[0023] Figure 2 This is a front sectional view of a dual-reservoir heat pipe according to the present invention;

[0024] Figure 3 This is a schematic diagram of the connection structure between the gas phase pipeline and the saddle.

[0025] Figure 4 This is a schematic diagram of the dual liquid reservoir and saddle structure;

[0026] Figure 5 This is a schematic diagram of a symmetrical capillary wick structure;

[0027] Figure 6 This is a schematic diagram of the connection between the reservoir and the filling pipe;

[0028] Figure 7 This invention relates to a scanning electron microscope for superhydrophilic nickel-based capillary cores with functionalized capillary structures.

[0029] Figure 8It is a pure nickel capillary core scanning electron microscope without added PMMA;

[0030] Figure 9 This is a comparison chart of suction performance in capillary structure suction force;

[0031] Figure 10 This is a graph showing the results of FTIR functional group analysis;

[0032] Figure 11 This is the capillary wick preparation process.

[0033] Figure 1 In the diagram, 1-1 is the evaporator, 1-2 is the first liquid receiver, 1-3 is the second liquid receiver, 1-4 is the first charging port, 1-5 is the second charging port, 1-6 is the first vapor phase pipeline, 1-7 is the second vapor phase pipeline, 1-8 is the first condenser, 1-9 is the second condenser, 1-10 is the first liquid phase pipeline, and 1-11 is the second liquid phase pipeline.

[0034] Figure 2-3 In the middle, 2-1 is the capillary wick, 1-2-1 is the end cap of the first reservoir, 1-3-1 is the end cap of the second reservoir, 1-2-2 is the liquid storage component of the first reservoir, 1-3-2 is the liquid storage component of the second reservoir, 1-1-1 is the saddle, 1-1-2 is the hollow cylinder 1, 1-1-3 is the hollow cylinder 2, 1-2-3 is the hollow cylinder 3, and the symmetrical part on the right side 1-3-3 is the hollow cylinder 4;

[0035] Figure 5 In the diagram, 5-1 is a rectangular capillary steam channel, and 5-2 is an annular capillary steam channel. Detailed Implementation

[0036] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0037] Unless otherwise specified, in this article, " / " represents division, and "×" and "*" represent multiplication.

[0038] In the description of this invention, the terms "inner," "outer," "upper," "lower," "front," "rear," "left," and "right," etc., which indicate orientation or positional relationship, are based on the position or orientation relationship shown in the accompanying drawings. They do not indicate or imply a specific installation and operation orientation that the described device or element must have, and therefore should not be construed as a limitation of this invention.

[0039] It should be noted that in the description of this invention, the terms "set," "install," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. Furthermore, the terms "a," "two," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features.

[0040] The technical solutions in the embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0041] Figure 1 A dual-reservoir heat pipe is disclosed. For example... Figure 1 The dual-reservoir loop heat pipe shown includes an evaporator 1-1, a first condenser 1-8, a second condenser 1-9, a first liquid reservoir 1-2, a second liquid reservoir 1-3, a first vapor phase line 1-10, a second vapor phase line 1-7, a first liquid phase line 1-6, and a second liquid phase line 1-11. The evaporator 1-1, the first vapor phase line 1-6, the first condenser 1-8, the first liquid phase line 1-10, and the first liquid reservoir 1-2 are sequentially connected to form a first loop. The evaporator 1-1, the second vapor phase line 1-9, and the second liquid phase line 1-11 are connected in sequence to form a second loop. Pipeline 1-7, second condenser 1-9, second liquid phase pipeline 1-11 and second liquid reservoir 1-3 are connected in sequence to form a second circuit; the first liquid reservoir 1-2 and the second liquid reservoir 1-3 are located at the left and right ends of the evaporator 1; the evaporator is filled with capillary wick 2-1, and the first vapor phase pipeline 1-6 and the second vapor phase pipeline 1-7 are inserted into the evaporator 1 from the top, and the positions of the first vapor phase pipeline 1-6 and the second vapor phase pipeline 1-7 inserted into the evaporator 1 are symmetrical about the middle position of the evaporator 1.

[0042] This loop heat pipe features dual reservoirs symmetrically arranged on both sides of the evaporator. Under special operating conditions such as tilting or acceleration, the contact area between the working fluid and the capillary wick in one reservoir decreases, while the contact area between the working fluid and the capillary wick in the other reservoir inevitably increases. This ensures stable replenishment of the working fluid under special conditions, preventing the capillary wick from drying out. It overcomes the poor stability of traditional single reservoir systems and possesses resistance to gravity, bumps, and impacts. It can adapt to different orientations in gravitational or acceleration fields, greatly improving the applicability of the heat pipe thermal control system.

[0043] This loop heat pipe has a dual-loop design, with both loops operating simultaneously in a dual-inlet, dual-outlet configuration. Compared to a dual-reservoir single-inlet, single-outlet loop heat pipe, the two loops of this loop heat pipe have identical path lengths for replenishing the working fluid, resulting in more stable replenishment.

[0044] As an improvement, the capillary wick 2-1 extends from the middle of the evaporator 1 to the left and right sides into the interior of the first liquid reservoir 1-2 and the second liquid reservoir 1-3. The capillary wick is interference-fitted with the evaporator, and transitions are provided at both ends of the capillary wick, extending into the interior of the liquid reservoirs 1-2 and 1-3. This extended extension of the capillary wick into the liquid reservoir allows for sufficient contact with the liquid working medium, facilitating the capillary wick's ability to draw the liquid working medium from within the liquid reservoir and ensuring stable liquid drawing under various operating conditions.

[0045] As an improvement, the first liquid phase line 1-10 and the second liquid phase line 1-11 are respectively inserted into the first liquid reservoir 1-2 and the second liquid reservoir 1-3, and as follows: Figure 6 As shown, holes are provided at the center of both ends of the capillary wick, and the first and second liquid phase pipelines are inserted into the holes of the capillary wick. The liquid working fluid can be directly replenished into the capillary wick through the liquid phase pipelines, shortening the replenishment time and increasing the working fluid circulation rate.

[0046] As an improvement, the first and second liquid phase lines extend into the pores of the capillary wick inside the evaporator. Preferably, the distance extending into the evaporator is 30-40% of the evaporator length. This effectively reduces the flow resistance of the liquid working fluid, allowing it to quickly reach the inside of the capillary wick.

[0047] As an improvement, such as Figure 5 As shown, non-connected holes are symmetrically opened at both ends of the capillary core inside the evaporator. A metal wire mesh sub-capillary core is provided inside the holes. Multiple rectangular steam channels 5-1 of the same length as the capillary core are located around the capillary core. Two annular steam channels 5-2 are symmetrically opened on the left and right sides along the middle of the evaporator.

[0048] The capillary wick of this heat pipe is open on both sides and not connected in the middle, which allows for a certain degree of separation between the two circuits. However, due to the permeation effect of the porous structure of the capillary wick, when the pressure in one circuit is too high, the working fluid can also flow from the circuit with higher pressure to the other circuit through the porous structure, which plays a role in buffering the pressure and making the dual circuits of this heat pipe have operational stability.

[0049] The capillary core of this loop heat pipe is surrounded by rectangular vapor channels, which increases the total volume of the channels and facilitates the timely overflow of gaseous working fluid, thereby improving the heat exchange capacity. At the same time, as a passage between the two loops, it can balance the gas pressure when there is a large pressure difference between the two sides, thus improving the stability of the loop heat pipe operation.

[0050] The capillary core of this loop heat pipe has two symmetrically distributed annular vapor channels in the middle, which serve to store vapor, balance the gas pressure of each rectangular vapor channel, and further improve the stability of the loop heat pipe operation.

[0051] In this loop heat pipe, multiple rectangular steam channels run between the two annular channels of the capillary wick to balance the pressure on both sides of the capillary wick, thereby achieving stable steam input and output.

[0052] As an improvement, the ends of the first vapor phase pipeline 1-6 and the second vapor phase pipeline 1-7 are located above the left and right annular steam channels of the capillary core, respectively. The gaseous working fluid can flow into the steam pipeline quickly, effectively reducing the flow resistance of the gaseous working fluid.

[0053] As an improvement, the evaporator, first liquid receiver, and second liquid receiver are integrated into a single unit. The evaporator and liquid receiver of this loop heat pipe are designed and manufactured as a single unit, simplifying the manufacturing process and improving its resistance to pressure and deformation.

[0054] As an improvement, the liquid reservoir is composed of liquid storage components 1-2-2 and 1-3-2 and end caps 1-2-1 and 1-3-1. The end caps 1-2-1 and 1-3-1 are connected to the liquid storage components 1-2-2 and 1-3-2 by welding.

[0055] As an improvement, the vapor phase pipeline and the liquid phase pipeline are manufactured as a single unit. The liquid phase pipeline extends through a hollow cylindrical hole on the end cap and then through the reservoir into the central hole of the capillary core, preferably to a depth of 70 mm.

[0056] As an improvement, the upper part of the evaporator saddle is symmetrically equipped with hollow cylinders, each 5mm long and 1mm thick, with a distance of 13mm between the center points of the two hollow cylinders. The first vapor phase pipeline and the second vapor phase pipeline 2 extend 5mm into the saddle through the hollow cylinders.

[0057] The evaporator 1-1, liquid receiver 1-2, and liquid receiver 1-3 are an integrated structure. For example... Figure 2 , 3As shown, the evaporator 1-1 includes an external saddle 2-6 and an internal capillary wick 2-1, with the external saddle 1-1-1 and the internal capillary wick 2-1 having an interference fit. Both ends of the capillary wick 2-1 extend 15mm into the liquid reservoirs 1-2 and 1-3, respectively. Symmetrically positioned above the saddle 2-6 are two hollow cylinders 2-7 and 2-8, each 5mm long and 1mm thick, with 45° chamfered edges at their ends. The distance between the center points of the two hollow cylinders is 13mm. Vapor phase lines 1-6 and 1-7 extend 5mm into the saddle 1-1-1 through hollow cylinders 1-1-2 and 1-1-3, respectively. Liquid reservoir 1-2 includes a liquid storage portion 1-2-2 and an end cap 1-2-1. The end cap 1-2-1 has a 5mm long, 1mm thick hollow cylindrical protrusion 1-2-3 at its center. Both ends of the hollow cylindrical protrusion 1-2-3 have a 2mm 45° chamfer. Liquid reservoir 1-3 includes a liquid storage portion 1-3-2 and an end cap 1-3-1. The end cap 1-3-1 has a 5mm long, 1mm thick hollow cylindrical protrusion 1-3-3 at its center. Both ends of the hollow cylindrical protrusion 1-3-3 have a 2mm 45° chamfer. (The last sentence appears to be a repetition of the first and can be omitted.) Figure 5 As shown, the capillary wick 2-1 has symmetrically arranged non-connected holes at both ends, and multiple rectangular steam channels 5-1 of the same length as the capillary wick are arranged around its periphery. Annular steam channels 5-2 and 5-3 are symmetrically arranged in the middle. Figure 6 As shown, the filling tube 1-4 and the filling tube 1-5 are located in the reservoir 1-2 and the reservoir 1-3 respectively, and extend into the interior of the reservoir 1-2 and the reservoir 1-3.

[0058] As a preferred option, such as Figure 2 As shown, the evaporator consists of an external saddle and an internal capillary wick.

[0059] As a preferred option, such as Figure 2 As shown, the external saddle has a circular through hole.

[0060] As a preferred option, such as Figure 2 As shown, the capillary core is interference-fitted with the circular through hole of the saddle, and the capillary core extends 17mm from both sides of the circular through hole of the saddle. The capillary core and the saddle are arranged symmetrically.

[0061] The circular through hole of the saddle in this invention is coaxially arranged with the liquid storage parts 1-2-2 and 1-3-2, and the evaporator, liquid storage parts 1-2-2 and 1-3-2 are manufactured as a whole, which can simplify the processing flow, improve production efficiency, and improve the ability to resist pressure and deformation.

[0062] As a preferred option, such as Figure 2 As shown, the liquid reservoir 1-2 (1-3) consists of a liquid storage part 1-2-2 (1-3-2) and an end cap 1-2-1 (1-3-1).

[0063] As a preferred option, such as Figure 3 As shown, the bottom of the liquid reservoirs 1-2 and 1-3 has a 1mm rounded corner.

[0064] As a preferred option, such as Figure 2 As shown, the side walls of the liquid reservoirs 1-2 and 1-3 are provided with through holes.

[0065] As a preferred option, such as Figure 2 As shown, end caps 1-2-1 and 1-3-1 are provided on the outer side of the liquid storage parts 1-2-2 and 1-3-2, respectively. End caps 2-2 and 2-3 are coaxially arranged with the liquid storage parts 1-2-2 and 1-3-2 and are connected by welding.

[0066] As a preferred option, such as Figure 6 As shown, the filling pipes 1-4 and 1-5 are inserted into the reservoirs 1-2 and 1-3 respectively, and serve to fill the working fluid before the heat pipe in this loop is put into operation. After the working fluid is filled, the filling ports of the filling pipes 1-4 and 1-5 are sealed by welding.

[0067] Preferably, the capillary wick 2-1 is sintered using a volatile and soluble salt-based pore-forming agent to achieve the adhesion of organic functional groups, resulting in a superhydrophilic effect. The novel capillary wick has a specific surface area of ​​1.04 m² / g, which is 2.5 times higher than that of capillary wicks sintered using graphite-like carbon nitride as a pore-forming agent, exhibiting excellent suction performance.

[0068] Porous materials, with their well-developed pore structures, are now widely used in aerospace, transportation, environmental protection, and petrochemical industries. As an important application, the capillary wick in a loop heat pipe (LHP) evaporator utilizes the capillary suction and permeation properties of porous materials. The performance of the capillary wick is crucial to the overall performance of the loop heat pipe. A capillary wick with good suction and heat pipe operation requires not only a certain porosity and hydrophilicity, but also specific requirements for the microscopic distribution of pore size and mechanical strength. In traditional capillary wick sintering processes, parameters such as molding pressure and sintering temperature are typically used to modify the pore size and pore distribution, thereby altering the porosity and controlling suction performance. Another approach is to add pore-forming agents to control the pore size and porosity. Current research mostly employs soluble salt or volatile pore-forming agents to regulate the pore geometry and control the micropore diameter to optimize capillary force, such as sodium chloride, carbon nitride, and ammonium bicarbonate. However, adding such pore-forming agents only alters the pore size and shape at the microscopic level of the capillary wick, optimizing capillary suction by controlling surface tension. This method suffers from limitations in precise control during the sintering process and the inability to regulate micropores across scales, resulting in a low upper limit for capillary suction optimization. Furthermore, the pores generated by this method are generally large and unevenly distributed, making the pore-forming process difficult to control and preventing the acquisition of capillary wicks with uniform pore size distribution. Selecting pore-forming agents that can simultaneously control the physical properties of capillary wick micropores and the hydrophilic / hydrophobic chemical properties of the surface, and optimizing the sintering process, has the potential to simultaneously endow capillary wicks with high capillary suction performance and superhydrophilic properties, potentially becoming a method for further improving the suction performance of sintered capillary wicks.

[0069] The capillary core 2-1 material includes spherical powder of nickel chains, calcium chloride powder, and PMMA powder, wherein the mass fraction of each component is as follows: 8 parts of spherical powder of nickel chains, 0.5-1.5 parts of calcium chloride powder, and 0.5-1.5 parts of PMMA powder.

[0070] Metallic nickel has good chemical stability and is not easily oxidized in air; PMMA, as a carbon-based polymer, undergoes violent thermal decomposition, producing volatile gases that violently impact the metallic nickel powder, creating numerous meteorite-like pores, making it an excellent volatile pore-forming agent. Simultaneously, the decomposition process generates a large number of carbon-containing hydrophilic functional groups, and nickel and carbon readily form stable carbon-nickel bonds at high temperatures; calcium chloride powder has a melting point much higher than metallic nickel, is easily soluble in water, and has low corrosiveness, making it an excellent pore-forming agent for lava flows. Therefore, these three components were selected.

[0071] Compared to existing capillary core technologies, this technology can attach hydrophilic functional groups to the surface of metal capillary cores, forming a large number of nanoscale pores on the surface of micron-sized metal powders, achieving superhydrophilic properties. At the same time, compared to existing capillary cores sintered with volatile and soluble salt pore-forming agents of the same proportion, it effectively improves mechanical strength.

[0072] Reducing the proportion of calcium chloride or PMMA significantly decreases the capillary wick's suction performance and causes it to lose its superhydrophilic properties; increasing the proportion of calcium chloride or PMMA makes sintering impossible, greatly reducing the mechanical strength of the capillary wick and making it impossible to demold and process. Therefore, the above-mentioned mass fraction is a reasonable selection made through extensive experimentation, ensuring both processing technology and performance.

[0073] As an improvement, the spherical nickel chain powder has a size of 1μm-10μm, the calcium chloride powder has a particle size of 10μm-100μm, and the PMMA powder has a particle size of 500 mesh-3000 mesh. Nickel powder sizes outside this range will significantly reduce capillary suction performance; calcium chloride powder sizes smaller than this range will significantly reduce capillary suction performance, while sizes larger than this range will significantly reduce both suction performance and mechanical strength; PMMA powder sizes smaller than this range will significantly reduce the number of nanoscale pores, while sizes larger than this range will prevent capillary formation.

[0074] As an improvement, the spherical powder of the nickel chain has a size of 4μm-6μm, the calcium chloride powder has a particle size of 40μm-60μm, and the PMMA powder has a particle size of 1200 mesh-1800 mesh.

[0075] The preparation method of the above-mentioned surface-functionalized superhydrophilic nickel-based capillary core is as follows:

[0076] S1, The raw materials are placed in a vacuum drying oven and dried thoroughly;

[0077] S2, put the above raw materials into the mixer according to the proportion and mix them thoroughly;

[0078] S3, Place the thoroughly mixed raw materials into a mold and compact them on a vibrating table;

[0079] S4, use a pressure head and mold to perform manual pre-compression, and measure the amount of raw material filled;

[0080] S5. Repeat steps S3 and S4 until the raw material in the mold basically meets the pre-loaded value.

[0081] S6, the mold is placed in the sintering furnace for cold pressing to form the required blank;

[0082] S7, vacuum sintering of the shaped preform;

[0083] S8, after sintering and molding, the blank is demolded and the inner hole, outer circle and groove are machined.

[0084] In step S1, the drying vacuum degree is ≤0.01 Pa, the drying temperature is 70-90℃, and the time is 4-6 hours. If the vacuum degree does not meet the requirements, the raw material will undergo an oxidation reaction, changing the hydrophilicity of the material and altering the hydrophilic properties of the capillary core after sintering. If the drying temperature is lowered, the raw material powder will clump together, affecting the uniformity of mixing; if the temperature is higher, it will cause a thermal decomposition reaction of PMMA. If the time is too short, it will not be effectively dried, resulting in clumping and affecting the uniformity of mixing. Therefore, the above-mentioned suitable vacuum degree, drying time, and temperature were selected through extensive experiments.

[0085] The raw materials in step S2 are: 8 parts of nickel chain spherical powder, 0.5-1.5 parts of calcium chloride powder, and 0.5-1.5 parts of PMMA powder;

[0086] In step S6, the forming pressure is 5-25 MPa, and the holding time is 3000-6000 s. These pressures and times are reasonable selections made through extensive experiments. If the forming pressure is lower than this range, sintering will fail; if it is higher, the capillary core will become denser, reducing or eliminating its suction performance. If the holding time is too short, sintering will fail; if it is too long, the capillary core will become denser, reducing or eliminating its suction performance.

[0087] In step S7, the vacuum sintering pressure is ≤0.01Pa, the first sintering temperature is 500-600K, the heating rate is 5-15K / min, and the holding time is 0-30min; the second sintering temperature is 650-750K, the heating rate is 5-10K / min, and the holding time is 0-10min; and the third sintering temperature is 950-1000K, the heating rate is 5-15K / min, and the holding time is 60-90min.

[0088] As an improvement, the first sintering temperature is 600K, the heating rate is 10K / min, and the holding time is 0-30min; the second sintering temperature is 700K, the heating rate is 5-10K / min, and the holding time is 0-10min; and the third sintering temperature is 973K, the heating rate is 10K / min, and the holding time is 60min.

[0089] If the first sintering temperature is below this range, PMMA cannot decompose and form hydrophilic functional groups; if it is above this range, the decomposition is too vigorous, affecting capillary wick formation. Similarly, if the heating rate is too fast, PMMA decomposes too rapidly, also affecting capillary wick formation. If the second sintering temperature is too high or the heating rate is too fast, the reaction between carbon-containing functional groups and metallic nickel is affected, reducing or eliminating the adhesion of hydrophilic functional groups to the surface. If the third sintering temperature is too high or the holding time is too short, the capillary wick will not form, reducing or eliminating its suction performance. Therefore, the above-mentioned reasonable selection of sintering steps and times further improves processing efficiency and functionality.

[0090] The beneficial effects of this invention are as follows: By optimizing the sintering process of the nickel capillary wick, and innovatively selecting the salt-soluble pore-forming agent calcium chloride and the volatile pore-forming agent PMMA, a layer of 5-10 nm hydrophilic functional groups is formed on the surface of the capillary wick. Simultaneously, nanoscale pores of 2 nm-200 nm with an average pore size of 11 nm are formed on the surface of the nickel particles. Compared with traditional nickel capillary wicks, this invention exhibits superhydrophilic properties, significantly improving the capillary wick's water-pumping effect. Compared with traditional capillary wicks using salt-soluble and volatile pore-forming agents, this invention significantly improves the capillary wick's stiffness and enhances its machinability. It further improves the operational stability of the loop heat pipe and enhances its heat transfer capacity.

[0091] See Figure 10 Combined with XRD and XPS analysis results, it was demonstrated that the volatile pore-forming agent PMMA and the salt-soluble pore-forming agent CaCl2 had no phase residues, and that PMMA left behind many hydrophilic oxygen-containing functional groups after decomposition.

[0092] See Figure 7 , 8 SEM scanning electron microscopy and BET test results showed that a large number of nanoscale pores were generated during the sintering process, which more than doubled the specific surface area.

[0093] See Figure 9 The present invention has excellent suction performance and very fast suction speed, which is 200-400 seconds faster than capillary cores of the same size and with the same pore-forming agent ratio.

[0094] As an improvement, such as Figure 9 As shown, the mass percentage of calcium chloride powder is 5-15%, and the mass percentage of PMMA powder is 5-15%. More preferably, the mass percentage of calcium chloride powder is 15%, and the mass percentage of PMMA powder is 5%. At this point, the suction performance is optimal.

[0095] Example 1: Uniformly sized chain-like nickel powder (1 μm diameter), calcium chloride powder (10 μm diameter), and 500-mesh PMMA powder were used. The three raw materials were placed in a vacuum drying oven (0.01 Pa) at 90°C for 4 hours. After drying, the raw materials were removed and uniformly mixed in a mass ratio of Ni:CaCl2:PMMA of 8:0.5:1.5. After mixing, the mixture was placed in a sintering mold and manually pre-pressed and measured multiple times until it met expectations. Cold pressing was then performed at a pressure of 25 MPa. The vacuum sintering furnace was used (0.001 Pa). The sintering process was as follows: first step: 600 K, heating rate 15 K / min, holding time 0 min; second step: 750 K, heating rate 10 K / min, holding time 0 min; third step: 1000 K, heating rate 15 K / min, holding time 60 min. After cooling, the mixture was demolded, washed in clean water to remove the soluble pore-forming agent, and finally dried. Its final porosity is 72%.

[0096] Example 2: Uniformly sized chain-like nickel powder (2μm diameter), calcium chloride powder (20μm diameter), and PMMA powder (1500 mesh) were used. The three raw materials were placed in a vacuum drying oven (0.01 Pa) at 90°C for 4 hours. After drying, the raw materials were removed and uniformly mixed in a mass ratio of Ni:CaCl2:PMMA of 8:1:1. After mixing, the mixture was placed in a sintering mold and manually pre-pressed and measured multiple times until it met expectations. Cold pressing was then performed at a pressure of 10 MPa. The vacuum sintering furnace was used (0.001 Pa). The first sintering step was performed at 600K with a heating rate of 10K / min and a holding time of 20min; the second step was at 700K with a heating rate of 5K / min and a holding time of 10min; the third step was at 970K with a heating rate of 10K / min and a holding time of 70min. After cooling, the mixture was demolded, washed in clean water to remove the soluble pore-forming agent, and finally dried.

[0097] Its final porosity is 70%, as shown in the figure, and the surface of the capillary core is covered with a large number of nanoscale meteorite-like pores.

[0098] As a preferred option, such as Figure 5 As shown, the capillary wick 2-1 has symmetrical, non-connected holes at both ends extending into the capillary wick, each with a diameter of 8mm and a depth of 80mm. The periphery of the capillary wick 2-1 has multiple rectangular steam channels 5-1 of the same length as the capillary wick. At the same time, two annular steam channels 5-2 and 5-3, each 6mm long, are symmetrically opened at a distance of 7mm from the center of the capillary wick. The annular steam channels 5-2 and 5-3 divide the rectangular steam channels 5-1 into three parts, and the rectangular steam channels on both sides are symmetrical about the center of the capillary wick 2-1.

[0099] This invention designs and manufactures rectangular steam channels 5-1, increasing the overall volume of the channels and facilitating the timely overflow of gaseous working fluid, thereby improving heat exchange capacity. Simultaneously, as a passageway between the two loops, it can balance the gas pressure in situations with large pressure differences between the two sides, improving the stability of the loop heat pipe operation. The symmetrically arranged annular steam channels 5-2 and 5-3 are designed and manufactured to store steam and balance the gas pressure of each rectangular steam channel, further improving the stability of the loop heat pipe operation.

[0100] As a preferred option, this loop heat pipe is equipped with symmetrical dual reservoirs 1-2 and 1-3. Under special operating conditions such as tilting or acceleration, the contact area between the working fluid in one reservoir and the capillary wick 2-1 decreases, while the contact area between the working fluid in the other reservoir and the capillary wick 2-1 inevitably increases. This enables stable replenishment of the working fluid under special operating conditions, avoids the situation where the capillary wick 2-1 dries out, and can make up for the poor working stability of traditional single reservoirs. It also has the ability to resist gravity, bumps, and impacts, and can adapt to different orientations in gravitational or acceleration fields, greatly improving the applicability of the heat pipe thermal control system.

[0101] Preferably, the gas phase pipelines 1-6 and 1-7 and the liquid phase pipelines 1-10 and 1-11 are all manufactured as a single unit and have the same radius.

[0102] As a preferred option, such as Figure 4 As shown, the gas phase pipelines 1-6 and 1-7 extend into the cylindrical holes symmetrically opened above the saddle. The lower ends of the gas phase pipelines 1-6 and 1-7 are tangent to the inner wall of the through holes opened in the saddle. The gas phase pipelines 1-6 and 1-7 are connected and sealed to the cylindrical holes symmetrically opened above the saddle by welding.

[0103] Preferably, the condenser should be selected according to the actual operating conditions and can be installed on the gas-liquid phase junction pipeline to achieve efficient condensation of the gas phase working fluid.

[0104] Preferably, the liquid phase pipelines 1-10 and 1-11 extend 85mm into the liquid reservoirs 1-2 and 1-3 through the cylindrical holes 1-2-3 and 1-3-3 opened in the center of the end caps 1-2-1 and 1-3-1, respectively. The liquid phase pipelines 1-10 and 1-11 are connected and sealed to the cylindrical holes opened in the center of the end caps 1-2-1 and 1-3-1 by welding.

[0105] As a preferred option, such as Figure 2 As shown, the liquid phase pipelines 1-10 and 1-11 extend 70mm into the holes opened at the center on both sides of the capillary wick 2-1, so that the capillary wick 2-1 can fully absorb the working fluid and ensure the stable operation of the circuits on both sides of the heat pipe in this loop.

[0106] This invention employs a dual-loop design, using a dual-inlet, dual-outlet configuration to allow both loops to operate simultaneously. Compared to a dual-reservoir single-inlet, single-outlet loop heat pipe, the two loops of this loop heat pipe have identical path lengths for replenishing the working fluid, resulting in more stable replenishment of the working fluid.

[0107] The gas-liquid two-phase circuit and liquid storage tank structure described in this invention realizes the separation of gas and liquid working fluids, thereby improving heat exchange efficiency. After the evaporator is heated, the liquid working fluid is transformed into a gas working fluid, which is transported to the condenser via the vapor phase pipeline and condensed into a liquid working fluid, thus realizing long-distance heat transfer.

[0108] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. An evaporator component, comprising an evaporator, a first liquid reservoir, a second liquid reservoir, and a capillary wick, wherein the first and second liquid reservoirs are disposed at the left and right ends of the evaporator, the evaporator is filled with a capillary wick extending from the center of the evaporator to the left and right sides into the first and second liquid reservoirs, liquid inlets are respectively disposed on the left side of the first liquid reservoir and the right side of the second liquid reservoir, and two vapor outlets are disposed at the upper end of the evaporator; the liquid inlets are connected to liquid pipelines; two liquid pipelines are respectively inserted into the first and second liquid reservoirs, and holes are provided at the center of both ends of the capillary wick. The evaporator has holes for inserting the first and second liquid phase pipelines into the capillary wick; non-connecting holes are symmetrically opened at both ends of the capillary wick inside the evaporator, and a metal wire mesh sub-capillary wick is installed inside the holes. The outer periphery of the capillary wick has multiple rectangular steam channels of the same length as the capillary wick, and two annular steam channels are symmetrically opened at the middle of the evaporator; the two steam outlets are connected to the capillary wick at positions symmetrically aligned with the middle of the capillary wick; the steam outlets are connected to steam pipelines, which are inserted into the capillary wick in the evaporator from the top, and the insertion positions are symmetrically aligned with the middle of the capillary wick.

2. The evaporator component as claimed in claim 1, characterized in that, Each liquid reservoir consists of a liquid storage component and an end cap. The end cap and the liquid storage component are coaxially aligned and connected by welding.

3. The evaporator component as claimed in claim 1, characterized in that, The bottom of the reservoir has a 1mm rounded corner.

4. The evaporator component as claimed in claim 1, characterized in that, The reservoir has through holes on its side wall.

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