A heat transfer tube bundle heat exchanger with a double helix heat pipe baffle

Abstract

The application discloses a heat pipe shell-and-tube heat exchanger with a double-helix baffle reinforced heat transfer pipe, and belongs to the technical field of high-efficiency heat exchange equipment.The double-helix structure is used to replace the traditional baffle, the section inside the heat exchanger is a heat pipe evaporation section, heat exchange is directly conducted with the shell fluid, the shell fluid disturbance is strengthened, and the working medium inside the heat pipe is evaporated; the section of the spiral baffle exposed to the shell is a heat pipe condensation section, and the heat absorbed by the evaporation section is efficiently led out to the outside through phase change heat transfer.The application has the fluid disturbance and flow guide support functions of the spiral baffle and the phase change efficient heat transfer characteristics of the heat pipe, can significantly thin the boundary layer of the shell fluid, eliminate the flow dead zone, realize the coupling of the shell flow field disturbance and the heat pipe phase change heat transfer, improve the heat transfer efficiency and reduce the shell pressure drop.The comprehensive heat exchange efficiency of the heat pipe shell-and-tube heat exchanger is effectively improved, the flow resistance is reduced, and the application is suitable for high-efficiency heat exchange scenes in the fields of petroleum chemical industry, energy power and the like.

Description

Technical Field

[0001] This invention relates to the field of high-efficiency heat exchange equipment technology, specifically to a shell-and-tube heat exchanger with enhanced heat transfer using a double-helix heat pipe baffle. Background Technology Shell-and-tube heat exchangers, due to their reliable structure, strong adaptability, and ability to handle complex industrial conditions such as high temperature, high pressure, and multiple media, have been widely used in core heat exchange fields such as petrochemicals, energy and power, and waste heat recovery, making them indispensable key equipment in industrial production. However, the bow-shaped baffle design used in traditional shell-and-tube heat exchangers has significant drawbacks: the fluid is prone to bypassing and short-circuiting in the shell side, and the traditional bow-shaped baffle structure easily leads to significant fluid stagnation areas near the wall and on the leeward side of the baffle. This not only wastes heat transfer area but also causes local fluid retention and scaling problems. At the same time, the abrupt fluid reversal generates a high pressure drop, increasing energy consumption. Patent CN221484271U describes a spiral baffle and shell-and-tube heat exchanger. Even though the improved spiral baffle can optimize the flow field distribution and reduce dead zones, it still relies on a single convection heat transfer mechanism and has not broken through the limitations of the heat transfer mode, making it difficult to meet the needs of high efficiency and energy saving in industry.

[0002] Existing improvements to heat pipe shell-and-tube heat exchangers also have shortcomings: most designs simply replace traditional heat exchange tubes with heat pipes, or add independent heat pipe assemblies to the shell side, leading to increased structural complexity, increased installation and maintenance difficulty, and poor matching between heat pipe arrangement and shell-side flow field, easily creating new flow obstructions. Patent CN117346570A describes a low-cost vacuum heat pipe heat exchanger with high heat absorption density. This solution fails to utilize the structural space and functional potential of baffles, and fails to deeply integrate the turbulence effect of baffles with the phase change heat transfer function of heat pipes, making it difficult to achieve the synergistic effect of "enhanced fluid turbulence + efficient phase change heat transfer," thus restricting further improvement of the heat exchanger's overall performance. Therefore, there is an urgent need to develop a novel shell-and-tube heat exchanger structure that is compact, functionally integrated, and possesses both the advantages of efficient turbulence and phase change heat transfer to address the pain points of existing technologies. Summary of the Invention

[0003] To overcome the above-mentioned technical problems, the present invention provides a shell-and-tube heat exchanger with enhanced heat transfer using a double-helix heat pipe baffle.

[0004] To achieve the above-mentioned technology, one aspect of the present invention provides: The housing 1 has tube sheets 3 installed at both ends inside the housing 1; The heat exchange tube assembly includes several heat exchange tube bundles 6 disposed in the shell 1, each heat exchange tube bundle 6 extending along the length of the shell 1 and passing through the tube sheets 3 at both ends. A double-helix heat pipe baffle 2 is coaxially arranged along the axial direction of the shell 1. The double-helix heat pipe baffle 2 includes a condensation section and an evaporation section that are interconnected. The evaporation section is located inside the shell 1, and the condensation section is located outside the shell 1. The evaporation section has a preset number of channels, and the heat exchange tube bundle 6 passes through the channels and is closely attached to the evaporation section.

[0005] In one embodiment, the double-helix heat pipe baffle 2 is composed of two spiral blades with opposite spiral directions, equal leads, and a phase angle difference of a preset angle; at the same time, the spiral tilt angle of the double-helix heat pipe baffle 2 is set to 15°~30° to adapt to different heat exchange load requirements.

[0006] In one embodiment, the evaporation section is a hollow structure with a liquid diffusion layer of honeycomb or sponge-like porous material inside.

[0007] In one embodiment, the liquid diffusion layer is fixed to the inner wall of the evaporation section, and the phase change working fluid is uniformly distributed in the evaporation section by capillary force.

[0008] In one embodiment, the porous material has a porosity of 40% to 70% and an average pore size of 20 to 100 μm to improve capillary diffusion performance.

[0009] In one embodiment, the condensation section divides the portion of the evaporation section extending outside the housing 1 along the axial and circumferential directions to form a set of independent heat dissipation units.

[0010] In one embodiment, the heat dissipation unit has a flow-guiding wall with a preset slope; The segmentation angle of the segmentation operation is the angle between the guide wall and the horizontal direction, which is 5° to 90°, and the segmentation spacing is the axial distance between two adjacent heat dissipation units, which is 50 mm to 150 mm.

[0011] In one embodiment, the double-helix heat pipe baffle 2 has a hollow interior forming a heat pipe chamber, which is filled with a phase change working fluid, and the internal absolute pressure of the heat pipe chamber is lower than the standard atmospheric pressure, thus being in a negative pressure state.

[0012] In one embodiment, the two evaporation sections inside the double-helix heat pipe baffle 2 are interconnected.

[0013] In one embodiment, sealing flanges 4 are provided at both axial ends of the outer shell 1, and the tube sheet 3 and the sealing flanges 4 form a tube-side fluid inlet and outlet channel; sealing flanges 4 are provided at both radial ends of the outer shell 1 as inlet and outlet interfaces for shell-side fluid.

[0014] In one embodiment, the present invention also provides a method for using a shell-and-tube heat exchanger with enhanced heat transfer via a double-helix heat pipe baffle, comprising: Assembly and fixing: Fix the double helix heat pipe baffle 2 coaxially along the shell 1, and pass the heat exchange tube bundle 6 through the reserved hole of the double helix heat pipe baffle 2 and fix it to the tube sheet 3 at both ends; Working fluid filling: A liquid diffusion layer is set in the heat pipe cavity of the double helical heat pipe baffle 2, and then a preset amount of phase change working fluid is filled in. After ensuring that the absolute pressure inside the cavity is lower than the standard atmospheric pressure and is in a negative pressure state, the cavity is sealed to maintain the negative pressure state of the cavity. Heat exchange operation: The shell-side fluid flows along the double-helix flow channel formed by the double-helix heat pipe baffle 2, and exchanges heat with the evaporation section. The working fluid inside the heat pipe absorbs heat and evaporates. The working fluid vapor flows to the condensation section outside the shell and condenses into liquid upon contact with the external cooling medium. Circulation reflux: The liquid in the condensation section flows back to the evaporation section along the guide wall formed by the segmented structure, continuously completing the phase change cycle; Tube-side heat exchange: The tube-side fluid flows inside the heat exchange tube bundle 6 and exchanges heat with the shell-side fluid through the heat exchange tube bundle 6 and the double-helix heat pipe baffle 2.

[0015] In the working fluid filling step, the heat pipe chamber of the evaporation section is equipped with a honeycomb or sponge-like porous material, which uses its capillary effect to make the phase change working fluid evenly distributed in the evaporation section. During the heat exchange operation, the external cooling medium is air or cooling water.

[0016] Beneficial effects of the present invention Functional composite innovation: The double helix baffle's functions of turbulence, flow guidance, and support are deeply coupled with the heat pipe's efficient phase change heat transfer function. This breaks through the limitations of traditional baffles that can only turbulence and the poor structural compatibility of traditional heat pipe heat exchangers, achieving a multi-functional integrated design without the need for additional auxiliary components, thus simplifying the overall structure.

[0017] Significantly improved heat transfer efficiency: The shell-side fluid is guided by the double helix structure to form a stable helical flow, which greatly enhances the disturbance effect, thins the boundary layer, promotes fluid mixing, and effectively eliminates flow dead zones; the heat pipe phase change heat transfer efficiency is much higher than that of conventional convection heat transfer, and the condenser section segmented structure further increases the heat transfer surface area. The combined effect of these two factors increases the overall heat transfer efficiency by more than 10%.

[0018] The low-resistance operation has outstanding advantages: the double-helix flow channel design avoids fluid short-circuiting and sharp turning caused by traditional baffles. The flow resistance is reduced to a certain extent compared with the traditional bow-shaped baffles. The shell-side dead zone can be eliminated by nearly 30%, achieving a dynamic balance between efficient heat exchange and low-energy operation, and reducing energy consumption in industrial applications.

[0019] Strong circulation stability: The sloping guide wall formed by the division of the condensation section guides the condensate to flow back to the evaporation section evenly and smoothly, avoiding the accumulation of working fluid or local drying, which significantly improves the continuity and stability of the heat pipe phase change cycle and extends the continuous operating life of the equipment.

[0020] Wide adaptability and practicality: It can be adapted to different working conditions by adjusting the spiral tilt angle, working fluid type, and condensation section parameters. It is compatible with complex industrial environments such as high temperature, high pressure, and corrosiveness. It has a compact structure and is easy to install and maintain. It is suitable for the retrofit and upgrade of existing heat exchangers. Its application scenarios cover multiple fields such as petrochemical, energy and power, and waste heat recovery. Attached Figure Description

[0021] Figure 1 This is an overall schematic diagram of the present invention; Figure 2 This is a schematic diagram of the double-helix heat pipe baffle of the present invention; Figure 3 This is a cross-sectional view of the double-helix heat pipe baffle shell heat exchanger of the present invention; Figure 4 This is a side view and tube bundle distribution diagram of the double-helix heat pipe baffle shell-and-tube heat exchanger of the present invention; In the diagram: 1. Shell; 2. Double-helix heat pipe baffle; 3. Tube sheet; 4. Flange; 5. Support; 6. Heat exchange tube bundle. Detailed Implementation In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0022] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0023] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0024] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0025] In this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0026] Please see Figures 1-4 This invention provides a shell-and-tube heat exchanger with enhanced heat transfer using a double-helix heat pipe baffle plate, specifically comprising: a shell 1, a double-helix heat pipe baffle plate 2, tube sheets 3, flanges 4, supports 5, and heat exchange tube bundles 6; the shell 1 is fixedly connected to the supports 5, and tube sheets 3 are respectively provided at both ends inside the shell 1, the heat exchange tube bundles 6 extend along the length direction of the shell 1 and pass through the tube sheets 3 at both ends, the double-helix heat pipe baffle plate 2 is coaxially arranged along the length direction of the shell 1; sealing flanges 4 are provided at both axial ends outside the shell 1, and the tube sheets 3 and sealing flanges 4 form a tube-side fluid inlet and outlet channel; sealing flanges 4 are provided at both radial ends outside the shell 1 as inlet and outlet interfaces for shell-side fluid.

[0027] Furthermore, the double-helix heat pipe baffle 2 is divided into an evaporation section located inside the shell and a condensation section extending to the outside of the shell. The evaporation section is located inside the shell 1 and is in direct contact with the shell-side fluid. The double-headed helical curved surface structure enhances the disturbance of the shell-side fluid, destroys the fluid boundary layer, and absorbs heat from the shell-side fluid to cause the working fluid inside the heat pipe to evaporate.

[0028] Furthermore, the double-helix heat pipe baffle 2 has a hollow interior forming a heat pipe chamber, which is filled with a phase change working fluid. The phase change working fluid is selected from one or more combinations of water, acetone, ethanol, methanol, ammonia, etc., which can be used as heat pipe working fluids.

[0029] Furthermore, the tube-side fluid flows within the heat exchanger tube bundle 6.

[0030] Furthermore, the liquid diffusion layer is selected from one or a composite structure of porous sintered metal, porous ceramic material, and porous polymer material, and is fixed to the inner wall of the heat pipe cavity of the evaporation section by sintering, bonding or embedding.

[0031] Furthermore, the condensation section extends to the outside of the shell 1 and comes into contact with the external cooling medium, condensing the working fluid vapor generated in the evaporation section into a liquid. The external cooling medium is air or cooling water.

[0032] Furthermore, the guide wall allows the condensed heat pipe working fluid to flow back evenly to the evaporation section along the wall, while the segmented structure increases the convective heat transfer surface area between the condensation section and the external cooling medium.

[0033] Furthermore, a tightly fitted heat conduction structure is formed between the heat exchange tube bundle 6 and the wall of the reserved channel, allowing part of the heat of the tube-side fluid to be transferred to the inside of the heat pipe through the heat conduction effect between the tube wall of the heat exchange tube bundle 6 and the double helical heat pipe baffle 2.

[0034] In one embodiment of the present invention, the shell 1 is made of a cylindrical structure of high-strength corrosion-resistant alloy material. Its inner diameter is designed according to the heat exchange load requirements, and its length is adapted to the industrial site installation space to ensure stable flow field and easy maintenance.

[0035] Specifically, the shell can be made of corrosion-resistant materials such as 316L stainless steel; for example, the inner diameter of the shell 1 is designed to be 800 mm and the total length is 5000 mm. Those skilled in the art can scale the above dimensions according to the actual heat exchange power requirements; two shell-side inlet and outlet flanges are provided on both sides of the shell 1 at axially symmetrical positions. The flange specifications are DN200 and PN16, which serve as the shell-side fluid inlet and outlet; two saddle supports 5 are welded to the bottom of the shell, with a spacing of 3000 mm between the supports 5, which can be adapted to the installation space in the industrial site and ensure the stability of the equipment operation.

[0036] In one embodiment of the present invention, the heat exchange tube bundle 6 is arranged through the shell along the axial direction and is fixed in the tube holes of the tube sheets at both ends by expansion or welding. The tube-side fluid flows in a directional manner along the internal flow channel of the heat exchange tube bundle. The heat exchange tube bundle is made of high-efficiency heat transfer tube material and is arranged in a regular hexagonal pattern. The tube-side fluid flows along the internal channel of the tube bundle and forms a counter- or forward heat exchange with the shell-side fluid, ensuring the continuity and stability of the heat exchange process. The heat exchange tube bundle 6 passes through the pre-reserved channels on the double-helix heat pipe baffle 2, and a close-fitting heat conduction structure is formed between the heat exchange tube bundle 3 and the wall of the pre-reserved channels. This allows some of the heat generated by the fluid flowing in the tube bundle to be transferred to the inside of the heat pipe through the heat conduction between the tube bundle wall and the double-helix heat pipe baffle. The heat pipe phase change heat transfer mechanism efficiently removes some of the tube-side heat, achieving coordinated heat removal from both the tube and shell sides. At the same time, the double-helix structure guides the shell-side fluid to flow along the helical path through continuous helical curved surfaces, avoiding fluid short-circuiting and local eddies caused by traditional baffles, effectively eliminating flow dead zones, reducing energy loss caused by fluid turning, and lowering flow resistance. Inside the heat pipe, the phase change process of working fluid evaporation and condensation achieves rapid heat transfer, with a certain degree of improvement in heat transfer efficiency compared to conventional metal heat conduction. This, together with the enhanced shell-side fluid disturbance and coordinated heat removal from the tube sides, forms a synergistic effect mechanism of "flow field optimization + phase change heat transfer + two-way heat conduction," significantly improving the overall heat exchange efficiency of the heat exchanger.

[0037] Specifically, tube sheet 3 is made of 316L stainless steel, the same material as the shell, with a thickness of 40 mm. 196 hexagonal mounting holes are formed on tube sheet 3, with a hole diameter of 25 mm and a hole spacing of 32 mm. The tube sheet and shell are welded using argon arc welding, and a penetration test is performed after welding to ensure there are no welding defects. The heat exchanger bundle 6 is made of high-efficiency copper tubes, with an outer diameter of 25 mm, an inner diameter of 22 mm, and a length of 4800 mm per tube. The copper tube surface is micro-ribbed with a ribbed coefficient of 1.8 to enhance convective heat transfer between the tube side and the shell side. A total of 196 heat exchanger tubes are arranged in a hexagonal pattern and inserted into the tube sheet holes. They are fixed to tube sheet 3 using a double fixing method of expansion joint and welding to ensure the connection strength and heat transfer efficiency between the heat exchanger bundle 6 and tube sheet 3.

[0038] In one embodiment of the present invention, the double-helix heat pipe baffle 2 adopts an integrated double-helix heat pipe baffle structure. The plate body has pre-set tube holes arranged according to the tube bundle, replacing the traditional bow-shaped baffle with an integral structure. It is continuously arranged along the axial direction of the shell. The helix degree and thickness of the helix baffle are reasonably set according to actual needs, which not only ensures the structural support strength, but also meets the heat pipe heat transfer efficiency requirements. This component has three core functions: guiding flow, supporting the heat exchange tube bundle, and high-efficiency heat transfer. Among them, the helix baffle section located inside the shell 1 is the heat pipe evaporation section, directly... In contact with the shell-side fluid, a special curved surface structure enhances the disturbance of the shell-side fluid, disrupting the fluid boundary layer. Simultaneously, it absorbs heat from the shell-side fluid, causing the working fluid inside the heat pipe to evaporate. A sealed heat pipe chamber is formed inside the evaporation section. After evacuation to reduce the absolute pressure inside the chamber to below standard atmospheric pressure and creating a negative pressure state, the chamber is sealed. The chamber is filled with a honeycomb or sponge-like porous material, which is selected from one or a composite structure of porous sintered metals, ceramic porous materials, and polymer porous materials. The porosity of the porous material is 40%~70%, and the pore size is 20~100 μm, exhibiting excellent high capillary diffusion performance. The porous filling material is fixed to the inner wall of the heat pipe chamber in the evaporation section by sintering, bonding, or embedding, ensuring a tight fit with the chamber structure and not affecting the phase change cycle and heat transfer of the working fluid inside the heat pipe. The chamber is also filled with a phase change working fluid adapted to the operating conditions. The phase change working fluid is selected from one or more combinations of heat pipe working fluids such as water, acetone, ethanol, methanol, and ammonia. The filling amount is 30% to 60% of the chamber volume. Through the high capillary diffusion structure of the porous filling material, the working fluid inside the heat pipe can be uniformly distributed in the evaporation section based on capillary force, avoiding local drying and improving the phase change heat transfer efficiency. When the high-temperature fluid in the shell side flows through the evaporation section, heat is transferred to the inside of the heat pipe through convection heat transfer, so that the working fluid absorbs heat and evaporates rapidly to form high-temperature and high-pressure steam. The spiral baffle section extending to the outside of the shell 1 is the heat pipe condensation section. Through contact with the external cooling medium, the steam generated in the evaporation section is condensed into liquid. The spiral-shaped condensation section, divided at certain angles and distances, forms a sloping guide wall, allowing the condensed heat pipe working fluid to flow evenly back to the evaporation section along this wall, preventing working fluid accumulation and ensuring the continuity and stability of the phase change cycle. At the same time, the segmented structure creates multiple independent heat dissipation units on the outer surface of the condensation section, increasing the convective heat transfer surface area compared to a traditional smooth condensation section, significantly improving the heat exchange efficiency with the external cooling medium, and accelerating the steam liquefaction process. Heat dissipation fins can be added to the outside of the condensation section according to cooling requirements to further enhance the heat dissipation effect.

[0039] Specifically, the double-helix heat pipe baffle 2, as the core innovative component of this invention, is made of copper in one piece forging, which has both high strength and high thermal conductivity. The whole is a double-helix structure, which is continuously arranged along the axial direction of the shell, with a total length of 4500 mm, a baffle thickness of 50 mm, and a helix lead of 1200 mm. It is divided into two parts: an evaporation section inside the shell and a condensation section outside the shell. The interior is hollow to form a sealed heat pipe chamber with a wall thickness of 6 mm and no additional connecting gaps to avoid working fluid leakage.

[0040] The double-helix heat pipe baffle 2 of this invention adopts a double-headed helical structure, that is, within the same axial length range, two helical blades with equal helical direction, lead, and phase angle difference of a preset angle are arranged to form a helical baffle. The hollow chambers inside the two helical baffles are interconnected in the evaporation section and also maintain gas path interconnection in the condensation section, forming a complete heat pipe circulation system. Compared with the single-headed helix, this double-headed helical structure increases the frequency of fluid direction change under the same shell-side length, further enhancing the intensity of secondary flow in the flow field, thereby more effectively reducing the thermal resistance of the laminar boundary layer; the shell-side flow dead zone area of ​​this double-headed helical structure heat exchanger is reduced by nearly 34% compared with the bow-shaped structure baffle heat exchanger of the same size and under the same operating conditions, and at the same time, the two helical flow channels support each other, improving the overall structural strength of the baffle.

[0041] The double-helix heat pipe baffle of this invention features an integrated hollow molding structure, with the evaporation section directly exposed to the shell-side fluid. Its wall thickness has been optimized through thermal conductivity calculations (6 mm in this embodiment), ensuring structural strength while maintaining a thermal resistance of less than 0.001 m²·K / W, thus guaranteeing efficient heat transfer from the shell-side fluid to the working fluid inside the heat pipe. Simultaneously, the double-helix structure forces the shell-side fluid into a helical flow, increasing the convective heat transfer coefficient between the fluid and the outer wall of the baffle by more than 30% compared to an arc-shaped baffle, sufficient to maintain continuous boiling conditions in the heat pipe evaporation section.

[0042] The evaporation section, located inside the shell, is 4000 mm long with a spiral angle of 20° (within the optimal range of 15° to 30°) to ensure a stable spiral flow field for the shell-side fluid. The heat pipe chamber of the evaporation section is filled with a composite porous material with a porosity of 55% and a pore size of 60 μm, possessing high strength, high thermal conductivity, and high capillary diffusion performance. This material is fixed to the inner wall of the chamber by sintering. The chamber is filled with deionized water as the phase change working fluid, at a filling volume of 45% (30% to 60%) of the chamber volume. After filling, the chamber is evacuated to a vacuum level of 1×10⁻⁶. - ³ Pa, then seal.

[0043] The condensing section extends to the outside of the shell and is symmetrically distributed at both ends of the shell. The condensing section adopts a segmented structure design, divided along the axial and circumferential directions at a segment angle of 30° and a segment spacing of 80 mm (50~100 mm range), forming a guide wall with a preset slope. The segmented structure increases the heat exchange surface area of ​​the condensing section by 30% (20%~40%) compared to the traditional smooth condensing section. Annular heat dissipation fins are welded to the outer surface of the condensing section, with a fin thickness of 2 mm and a fin spacing of 10 mm, further enhancing the heat exchange efficiency with the external cooling medium. Verification shows that, with the above-mentioned integrated structural design, under the conditions of the same Reynolds number and pressure drop for the shell-side fluid flow rate, the overall heat exchange efficiency can be improved by 13% compared to a single-baffle heat exchanger with the same heat exchange area. The condensing section and the outer wall of the shell are welded and sealed to ensure no leakage of the shell-side fluid.

[0044] The segmented structure of the condensing section involves physically dividing its outer wall axially and circumferentially while maintaining the continuous flow of the hollow cavity, forming multiple independent heat dissipation units. After segmentation, the outer wall of the condensing section has a discontinuous finned or blocky structure, but the internal steam channels remain connected, ensuring that the steam generated in the evaporation section can flow unimpeded to all areas of the condensing section. The guide walls formed by the segmentation utilize gravity and the slope structure of the condensing section's outer wall to allow the condensed liquid working fluid to flow back evenly along the outer wall, preventing liquid accumulation.

[0045] Pre-reserved channels with a diameter of 25.2 mm are opened on the double-helix heat pipe baffle plate according to the arrangement of the heat exchange tube bundle. The channels are interference-fitted with the outer diameter of the heat exchange tube bundle, and the channel wall is tightly attached to the tube wall of the heat exchange tube bundle to form a high-efficiency heat conduction structure, realizing the transfer of heat from the tube side to the heat pipe chamber.

[0046] The heat exchanger assembly of this invention follows the principle of "inside before outside, fixing before sealing, and step-by-step testing," and the specific assembly steps are as follows: Fixing the double-helix heat pipe baffle 2: The integrally formed double-helix heat pipe baffle 2 is hoisted into the shell and positioned axially along the inner wall of the shell. The baffle is then welded and fixed to the inner wall of the shell. After welding, the continuity of the spiral flow channel is checked to ensure that there is no blockage or deviation.

[0047] Heat exchanger tube bundle 6. Installation and fixing: Arrange the 196 heat exchanger tube bundles in a regular hexagonal pattern and insert them one by one into the reserved channels of the double-helix heat pipe baffle and the mounting holes of the tube sheets at both ends. First, use a hydraulic tube expander to expand the tube bundles and tube sheets. After completion, check the tube bundles to ensure that they are not bent or loose and that they fit tightly against the walls of the reserved channels of the baffle.

[0048] Tube sheet 3 is welded to shell 1: The tube sheet 3 with the heat exchange tube bundle 6 assembled is argon arc welded to the bevels at both ends of the shell 1. After welding, the weld joint is subjected to penetrant testing (PT) to ensure that there are no defects such as cracks and pores.

[0049] Flange 4 and support 5 assembly: Fasten the sealing flange to the outside of the tube sheet with bolts; weld the saddle support to the preset position at the bottom of the shell 1.

[0050] Heat pipe chamber working fluid filling and sealing: Through the filling port reserved in the condenser section, a preset amount of deionized water is filled into the hollow chamber of the double helix heat pipe baffle. Then, the chamber is evacuated to a preset vacuum level. After that, the filling port is sealed by welding. After completion, the airtightness is tested.

[0051] End cap and interface installation: Fasten the end cap to the outside of the sealing flange with bolts to complete the pipe-side seal; install valves and connecting pipelines at the shell-side inlet and outlet flanges, and set the pipe-side fluid inlet and outlet at the tube sheet flange to complete the overall interface assembly.

[0052] Overall inspection: Perform a hydrostatic test on the assembled heat exchanger, with the shell side and tube side tested separately. It is considered qualified if there is no leakage or deformation.

[0053] The heat exchanger operation procedure in this embodiment is suitable for light hydrocarbon condensation heat exchange in the petrochemical industry. High-temperature light hydrocarbon medium (temperature 120℃, pressure 1.0 MPa) is introduced into the shell side, and cooling water (temperature 25℃, pressure 0.8 MPa) is introduced into the tube side. Industrial cooling water (temperature 20℃) is used as the external cooling medium to cool the condensation section. The specific operating steps are as follows: Preheating start-up: First, slowly introduce cooling water into the tube side to fill the heat exchange tube bundle flow channel, and then slowly introduce high-temperature light hydrocarbon medium into the shell side. Control the medium heating rate to ≤10℃ / min to avoid thermal stress caused by sudden temperature changes in the equipment. At the same time, start the industrial cooling water circulation system of the condensation section and control the cooling water flow rate to 50 m³ / h.

[0054] Shell-side heat exchange and heat pipe evaporation: The high-temperature light hydrocarbon medium in the shell flows along the spiral flow channel formed by the double-helix heat pipe baffle. Due to the disturbance of the double-helix structure, the fluid boundary layer is broken, and it fully contacts the outer surface of the evaporation section for heat exchange. The heat is transferred to the heat pipe chamber through the copper baffle. The deionized water in the chamber absorbs the heat and evaporates rapidly to form high-temperature and high-pressure steam (temperature 115℃, pressure 0.1 MPa). After heat exchange, the temperature of the shell-side medium drops to 40℃, realizing the condensation of light hydrocarbons.

[0055] Heat pipe condensation and working fluid reflux: The high-temperature and high-pressure steam generated in the evaporation section flows along the heat pipe chamber to the condensation section outside the shell. The condensation section comes into full contact with the industrial cooling water. After releasing heat, the steam condenses into liquid water. Under the guidance of the sloping guide wall formed by the segmented structure of the condensation section, the condensed liquid water flows back to the evaporation section evenly and smoothly with the help of gravity and capillary force. There is no accumulation of working fluid or local drying, thus realizing the continuous and stable operation of the heat pipe phase change cycle.

[0056] Tube-side heat exchange and dual-pass heat removal: The tube-side cooling water flows inside the heat exchange tube bundle and exchanges heat with the shell-side high-temperature light hydrocarbon medium through the tube bundle wall. At the same time, part of the heat between the tube-side fluid and the tube bundle wall is transferred to the evaporation section of the double-helix heat pipe baffle through the tight fit structure between the tube bundle and the reserved channels of the baffle. It is then efficiently removed to the condensation section through the heat pipe phase change heat transfer mechanism and exchanges heat with the external cooling medium. This achieves the synergistic removal of heat from the tube side and shell side, enhancing the overall heat exchange effect.

[0057] Key points for operation and maintenance: Regularly check the sealing performance of the heat exchanger, focusing on the welded joints between the tube sheet and the shell, the flange sealing surface, and the welded seals of the condenser section. No media leakage is acceptable. Regularly clean the scale on the shell-side flow channels and the surface of the heat exchange tube bundle to avoid scale affecting heat exchange efficiency.

[0058] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

[0059] The above description is merely an optional embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A shell-and-tube heat exchanger with enhanced heat transfer using a double-helix heat pipe baffle, characterized in that, include: The housing (1) has tube sheets (3) installed at both ends inside the housing (1); The heat exchange tube assembly includes several heat exchange tube bundles (6) disposed in the shell (1), each heat exchange tube bundle (6) extending along the length of the shell (1) and passing through the tube sheets (3) at both ends. A double-helix heat pipe baffle (2) is coaxially arranged along the axial direction of the shell (1). The double-helix heat pipe baffle (2) includes a condensation section and an evaporation section that are interconnected. The evaporation section is located inside the shell (1), and the condensation section is located outside the shell (1). The evaporation section has a preset number of channels, and the heat exchange tube bundle (6) passes through the channels and is closely attached to the evaporation section.

2. The shell-and-tube heat exchanger with enhanced heat transfer using a double-helix heat pipe baffle plate according to claim 1, characterized in that: The double-helix heat pipe baffle (2) is composed of two spiral plates with opposite spiral directions, equal leads and a phase angle difference of a preset angle; at the same time, the spiral tilt angle of the double-helix heat pipe baffle (2) is set to 15°~30° to adapt to different heat exchange load requirements.

3. A shell-and-tube heat exchanger with enhanced heat transfer using a double-helix heat pipe baffle plate according to claim 2, characterized in that: The evaporation section has a hollow structure and is equipped with a liquid diffusion layer of honeycomb or sponge-like porous material inside.

4. A shell-and-tube heat exchanger with enhanced heat transfer using a double-helix heat pipe baffle plate according to claim 3, characterized in that: The liquid diffusion layer is fixed to the inner wall of the evaporation section, and the phase change working fluid is uniformly distributed in the evaporation section by capillary force.

5. A shell-and-tube heat exchanger with enhanced heat transfer using a double-helix heat pipe baffle plate according to claim 4, characterized in that: The porous material has a porosity of 40% to 70% and an average pore size of 20 to 100 μm to improve capillary diffusion performance.

6. A shell-and-tube heat exchanger with enhanced heat transfer using a double-helix heat pipe baffle plate according to claim 5, characterized in that: The condensation section divides the portion of the evaporation section extending outside the shell (1) along the axial and circumferential directions to form a set of independent heat dissipation units.

7. A shell-and-tube heat exchanger with enhanced heat transfer using a double-helix heat pipe baffle plate according to claim 6, characterized in that: The heat dissipation unit has a flow guide wall with a preset slope; The segmentation angle of the segmentation operation is the angle between the guide wall and the horizontal direction, which is 5° to 90°, and the segmentation spacing is the axial distance between two adjacent heat dissipation units, which is 50 mm to 150 mm.

8. A shell-and-tube heat exchanger with enhanced heat transfer using a double-helix heat pipe baffle plate according to claim 7, characterized in that: The double-helix heat pipe baffle (2) has a hollow interior forming a heat pipe chamber, which is filled with a phase change working fluid. The internal absolute pressure of the heat pipe chamber is lower than the standard atmospheric pressure and is in a negative pressure state.

9. A shell-and-tube heat exchanger with enhanced heat transfer using a double-helix heat pipe baffle plate according to claim 8, characterized in that: The two evaporation sections inside the double-helix heat pipe baffle (2) are interconnected.

10. A shell-and-tube heat exchanger with enhanced heat transfer using a double-helix heat pipe baffle plate according to claim 9, characterized in that: The outer axial ends of the shell (1) are provided with sealing flanges (4), and the tube sheet (3) and the sealing flanges (4) form a tube fluid inlet and outlet channel; The outer radial ends of the shell (1) are provided with sealing flanges (4) as inlet and outlet interfaces for shell-side fluid.

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