Tube fin type heat exchanger core group

Abstract

The invention discloses a tube fin type heat exchanger core group which comprises a plurality of layers of independent and parallel fins and a plurality of enhanced heat exchange tubes connected with the plurality of layers of fins, each fin comprises a plurality of concave units and a plurality of convex units, and the concave units and the convex units are alternately connected to form a wavy section. The section of the enhanced heat exchange tube is of a special-shaped structure defined by a semicircle and a semiellipse, the section of the incident flow side of the enhanced heat exchange tube is semicircular, and the section of the back flow side of the enhanced heat exchange tube is semiellipse. The problems that an existing finned tube heat exchanger core set is low in heat transfer efficiency, prone to dirt accumulation, poor in corrosion resistance and the like are solved, the heat exchange efficiency is improved, and meanwhile the dirt deposition resistance and the corrosion resistance are enhanced.

Description

Technical Field

[0001] The invention belongs to the technical field of heat exchange equipment, and in particular relates to a tube-fin heat exchanger core group with high efficiency in heat exchange and anti-fouling and anti-corrosion. Background Art

[0002] As the core component of the tube heat exchanger to enhance heat transfer, the tube-fin heat exchanger core group occupies an important position in the fields of power engineering, chemical processes, HVAC and refrigeration systems due to its compact structure and high heat transfer efficiency. The basic heat transfer unit of this type of heat exchanger consists of a base tube and a fin. The base tube is mostly a circular, elliptical or flat tube structure, which is integrated with the fin through brazing, expansion or inlaying. However, in actual engineering applications, this technology faces many performance limitations. In terms of heat transfer performance, the contact thermal resistance generated at the interface between the fin and the base tube is as high as 15%-25% of the overall thermal resistance. This value will be further increased under high temperature conditions due to differences in the thermal expansion coefficient of the material. At the same time, limited by the 50-100W / (m 2 ·K), the fin surface temperature distribution is obviously non-uniform, resulting in the effective heat dissipation area utilization rate generally being less than 60%, forming an obvious "thermal dead corner" phenomenon.

[0003] The problems in operation and maintenance are also prominent. During long-term operation, the continuous deposition of particulate matter, oil and scale in the air on the surface of the fins will significantly increase the heat transfer thermal resistance. Traditional mechanical cleaning or chemical descaling methods are not only difficult to completely remove micron-level dirt particles, but may also cause damage to the fin surface. The more serious problem is the corrosion problem. In corrosive media such as marine environments or chemical waste gas treatment, the average annual corrosion rate of conventional aluminum or copper fins reaches 0.1-0.5mm / y (ASTM G48 standard test results), and the existing anti-corrosion coating technology is prone to peeling under high temperature or mechanical impact conditions, accelerating the local corrosion process.

[0004] The current technical improvement schemes each have obvious limitations: in terms of heat transfer enhancement, although structures such as corrugated fins and window fins can enhance the turbulent effect, the cost is a 20%-40% increase in system pressure drop; in terms of anti-fouling technology, although the use of hydrophobic coatings can delay the deposition of dirt, the coating will fail after long-term use and cause the heat transfer coefficient to decrease by 10%-15%; in terms of anti-corrosion measures, cathodic protection technology requires additional energy consumption and is completely ineffective against non-metallic dirt, while stainless steel alternatives face high costs and complex welding processes. The existence of these technical bottlenecks has made the development of a new tube-fin heat exchanger core group with efficient heat transfer, long-lasting anti-fouling and reliable anti-corrosion performance a key technical problem that needs to be solved in the current field of heat exchange equipment. Summary of the invention

[0005] The object of the present invention is to provide a tube-fin heat exchanger core group aiming at the deficiencies of the prior art. This tube-fin heat exchanger core group can solve the problems existing in the prior tube-fin heat exchanger core group, such as low heat transfer efficiency, easy fouling, and poor corrosion resistance, improve the heat exchange efficiency, and enhance the anti-fouling deposition and corrosion resistance at the same time.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A tube-fin heat exchanger core group includes a plurality of independent and parallel fins and a plurality of enhanced heat transfer tubes connecting the plurality of fins. Among them, the fin includes a plurality of concave units and a plurality of convex units, and the concave units and the convex units are alternately connected to form a wavy cross-section. The cross-section of the enhanced heat transfer tube is a special-shaped structure formed by enclosing a semi-circle and a semi-ellipse. The cross-section of the upstream side of the enhanced heat transfer tube is semi-circular, and the cross-section of its downstream side is semi-elliptical.

[0008] Furthermore, the edges of adjacent concave units and convex units on the fin are tangent.

[0009] Furthermore, the cross-sections of both the concave units and the convex units are regular hexagons.

[0010] Furthermore, the vertical distance H from the vertex of the concave unit or convex unit on the fin to the fin plane, the side length r of the regular hexagon, and the spherical radius R formed by connecting the concave and convex units satisfy:

[0011]

[0012] Furthermore, the minor axis of the semi-ellipse on the cross-section of the enhanced heat transfer tube is perpendicular to the oncoming flow direction, and the length of the minor axis is equal to the diameter of the semi-circle. The major axis of the semi-ellipse is arranged parallel to the oncoming flow direction.

[0013] Furthermore, the ratio of the major axis length to the minor axis length of the semi-ellipse is between 1.0 and 2.0.

[0014] Furthermore, the plurality of enhanced heat transfer tubes form an enhanced heat transfer tube bundle, and the arrangement form of the enhanced heat transfer tube bundle is staggered arrangement or in-line arrangement.

[0015] Furthermore, the distance between the enhanced heat transfer tubes along the main flow direction is 1.5 to 2.5 times the diameter of the semi-circle of its cross-section, and the distance between the enhanced heat transfer tubes perpendicular to the main flow direction is 1.2 to 2.0 times the diameter of the semi-circle of its cross-section.

[0016] Furthermore, the fin is made of a copper-based material, and its surface is provided with a corrosion-resistant coating.

[0017] Furthermore, the enhanced heat transfer tubes pass through a plurality of fins by an expansion joint method.

[0018] Working principle:

[0019] The present invention achieves a performance breakthrough through the organic combination of structural optimization and surface treatment technologies. When a fluid medium containing dust and oil flows through the heat exchange channel, the alternately arranged raised units and sunken units in the fin surface structure design will produce a significant flow regulation effect: the raised units accelerate the fluid to form a local high-speed jet area, and the adjacent sunken units induce longitudinal vortices. This periodic disturbance structure can effectively destroy the thermal boundary layer and significantly improve the convective heat transfer coefficient. In terms of anti-fouling and anti-corrosion, the streamlined spherical structure ensures uniform distribution of surface shear stress, the secondary flow field generated by the special cross-sectional tube type, and the combined action of the low-surface-energy functional coating significantly reduce the particulate deposition rate. In terms of the anti-fouling mechanism, the design of the curvature radius of the spherical structure increases the shear force on the particulate matter, and at the same time, the low-surface-energy characteristics of the surface coating work together to achieve the self-cleaning effect of dirt. In terms of anti-corrosion, a gradient coating technology is adopted, with a plasma-enhanced chemical vapor deposition transition layer at the bottom and a fluoropolymer composite coating on the surface layer, forming a double protection barrier. This design realizes the anti-fouling and anti-corrosion functions through the synergistic action of multiple mechanisms.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) The alternately arranged raised units and sunken units in the fin surface structure design will produce a significant flow regulation effect: the raised units accelerate the fluid to form a local high-speed jet area, and the adjacent sunken units induce longitudinal vortices. This periodic disturbance structure can effectively destroy the thermal boundary layer and significantly improve the convective heat transfer coefficient;

[0022] (2) The optimized flow channel design and surface treatment technology reduce the dirt deposition rate and significantly enhance the corrosion resistance;

[0023] (3) This special structure design (the elliptical shape on the backflow side) causes stronger disturbance when the fluid flows in the pipe. Compared with the standard circular pipe, the fluid in the pipe with a circular front and elliptical rear will form different distributions and flow states during the flow process, which promotes the thinning of the boundary layer, thereby reducing the thermal resistance, making the heat transfer smoother and increasing the heat transfer coefficient.

[0024] (4) This design can be directly applied to the existing heat exchanger system, with good compatibility and popularization value. These technical advantages make the present invention have broad application prospects in heat exchange equipment in fields such as chemical engineering, electric power, and HVAC. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic structural diagram of the tube-fin heat exchanger core group of the embodiment of the present invention;

[0026] Figure 2 It is a sectional view of the tube-fin heat exchanger core group of the embodiment of the present invention;

[0027] Figure 3 This is a top view of the tube-fin heat exchanger core group according to an embodiment of the present invention;

[0028] Figure 4 This is a schematic diagram of the spherical surface of the concave and convex parts of the fin according to an embodiment of the present invention.

[0029] Figure 5 This is a top view of the enhanced heat transfer tube according to an embodiment of the present invention;

[0030] Figure 6 This is a schematic diagram of the spacing of the enhanced heat transfer tubes according to an embodiment of the present invention. Detailed implementation manners

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0032] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0033] Next, the present invention will be further described in conjunction with specific embodiments, but it is not a limitation of the present invention.

[0034] As Figure 1 、 2 and shown in 3, an embodiment of the present invention discloses a tube-fin heat exchanger core group, which includes a plurality of independent and parallel layers of fins 1 and a plurality of enhanced heat transfer tubes 2 connecting the plurality of fins 1. Among them, the enhanced heat transfer tubes pass through a plurality of layers of fins by expansion joint method. The spacing between the multiple layers of fins 1 is kept as the same as possible. The working fluid between the fins 1 is a fluid containing dust and oil, and the working fluid in the enhanced heat transfer tubes 2 is water. The fin 1 includes a plurality of concave units 11 and a plurality of convex units 12. Among them, the concave units 11 and the convex units 12 are alternately connected to form a wavy cross-section, as Figure 4 shown. The cross-sections of both the concave unit 11 and the convex unit 12 are regular hexagons. When manufacturing the concave unit 11 and the convex unit 12, a concave spherical surface or a convex spherical surface is formed by stamping upward or downward from the center of the regular hexagon, and the edges of the adjacent concave unit 11 and convex unit 12 on the fin 1 are tangent to each other.

[0035] When the dusty and oily fluid passes between the fins 1, due to the regular concave-convex structure on the surface of the fins 1, periodic jets and swirls are formed, which break the boundary layer, improve the flow mixing, and enhance the heat transfer efficiency. The structural shape of the fins 1 can guide the fluid flow to a certain extent, making the pressure change of the fluid between the fins 1 more gentle, avoiding the situations of too high or too low local pressure, reducing the flow separation and energy loss caused by uneven pressure, and further improving the efficiency and stability of the fluid flow.

[0036] Moreover, since the concave units 11 and the convex units 12 on the fins are periodically distributed, the fluid velocity and pressure distributions on the surface of the fins 1 also change periodically, enhancing the fluid disturbance compared with the surface of general fins. To ensure the fluid disturbance effect, see Figure 4 , the vertical distance H from the vertex of the concave unit 11 or the convex unit 12 on the fins to the fin plane, the side length r of the regular hexagon, and the radius R of the sphere formed by connecting the concave-convex units satisfy: The periodic jets and swirls continuously scour the smooth curve-shaped fin surface, making it difficult for dirt to adhere and deposit, thereby maintaining good heat transfer performance and reducing the problems of heat transfer efficiency decline and equipment maintenance cost increase caused by fouling.

[0037] In this embodiment, the fins are made of copper-based materials. The streamlined surface design of the fins and the special cross-sectional structure of the enhanced heat transfer tubes work together to reduce the flow dead zone, and it is not easy for oil stains and dust to stay. Further, an anti-corrosion coating is applied on the fin surface. When the dusty and oily fluid impacts the fin surface, the fin surface will come into contact with various corrosive media, such as acids, salt solutions, etc. The anti-corrosion material can form a protective film on the fin surface to isolate the direct contact between these corrosive media and the fin metal, thereby greatly slowing down the speed of chemical corrosion, extending the service life of the fins and even the entire heat exchanger, ensuring the smoothness of the flow channels between the fins, enabling the fluid to flow normally according to the design requirements, and ensuring that the performance of the heat exchanger core group is not affected.

[0038] See Figure 5 , the cross-section of the enhanced heat transfer tube 2 is a special-shaped structure formed by enclosing a semi-circle 21 and a semi-ellipse 22. Among them, the cross-section of the upstream side of the enhanced heat transfer tube is a semi-circle 21, and the cross-section of its downstream side is a semi-ellipse 22. This special structural design (the elliptical shape on the downstream side) makes the fluid generate stronger disturbance when flowing in the tube. Compared with the standard circular tube, the fluid in the tube with a circular front and an elliptical rear will form different distributions and flow patterns during the flow process, which promotes the thinning of the boundary layer, thereby reducing the thermal resistance, making the heat transfer more smooth, and increasing the heat transfer coefficient.

[0039] The minor axis of the semi-ellipse 22 on the cross-section of the enhanced heat transfer tube is perpendicular to the oncoming flow direction, and the length of the minor axis is equal to the diameter of the semi-circle 21. The major axis of the semi-ellipse 22 is arranged parallel to the oncoming flow direction. Further, the ratio of the major axis length to the minor axis length of the semi-ellipse 22 is between 1.0 and 2.0. In this way, under the conditions of the same pipe diameter and pipe length, the surface area of the elliptical part relatively increases, making the contact area between the fluid and the pipe wall larger, providing more paths and space for heat transfer, so that more heat can be absorbed or released, and the heat transfer efficiency is further improved. Compared with the standard elliptical tube, the circular design at the inlet section of the enhanced heat transfer tube can reduce the initial flow resistance and the pressure drop. When the major axis of the front-round and rear-elliptical tube is consistent with the flow direction, the pressure drop reaches the minimum state.

[0040] In this embodiment, multiple enhanced heat transfer tubes 2 pass through the fins to form an enhanced heat transfer tube bundle, and the arrangement form of the enhanced heat transfer tube bundle is staggered arrangement or in-line arrangement. Among them, as Figure 6 shown, the spacing Sp between the enhanced heat transfer tubes 2 along the mainstream direction is 1.5 to 2.5 times the diameter of the semi-circle of its cross-section, and the spacing Lp between the enhanced heat transfer tubes perpendicular to the mainstream direction is 1.2 to 2.0 times the diameter of the semi-circle of its cross-section. Due to the flow pattern optimization of the enhanced heat transfer tube 2 and the guiding effect on the fluid, its resistance coefficient is relatively lower than that of the traditional standard circular tube. This means that under the conditions of the same flow rate and flow velocity, the resistance that the fluid needs to overcome when passing through the enhanced heat transfer tube 2 is smaller, so that the energy consumption of power equipment such as pumps or fans can be reduced, and the operation cost can be saved. The structure of the elliptical part increases the structural strength and stability of the heat transfer tube to a certain extent. Compared with a simple circular tube, the semi-circle and semi-ellipse shape can better withstand loads such as fluid pressure and external mechanical forces, reducing the occurrence probability of pipeline deformation, rupture and other failures, and improving the reliability and service life of the heat exchanger.

[0041] During the manufacturing process, the structure of the semi-circle and semi-ellipse cross-section can make more reasonable use of materials on the premise of ensuring performance. By optimizing the size and shape of the elliptical part, while meeting the heat transfer and strength requirements, the material usage can be reduced, the manufacturing cost can be lowered, and the material utilization rate can be improved. The stable and efficient operation of the heat exchanger performance helps to achieve the energy-saving goal and improve the energy utilization efficiency. At the same time, preventing the leakage of corrosive media and avoiding environmental pollution helps to achieve sustainable development.

[0042] The above are only preferred embodiments of the present invention, and do not limit the implementation manners and protection scope of the present invention accordingly. For those skilled in the art, it should be able to realize that all the equivalent replacements and obvious changes made by using the content of the specification of the present invention should be included in the protection scope of the present invention.

Claims

1. A tube-fin heat exchanger core group, characterized in that, It includes a number of independent and parallel fin layers and multiple enhanced heat transfer tubes connecting the fin layers. Among them, the fins include multiple concave units and multiple convex units, and the concave units and the convex units are alternately connected to form a wavy cross-section; the cross-section of the enhanced heat transfer tube is a special-shaped structure formed by enclosing a semi-circle and a semi-ellipse. The cross-section of the enhanced heat transfer tube on the flow-facing side is semi-circular, and the cross-section of its back-flow side is semi-elliptical.

2. The finned tube heat exchanger core group according to claim 1, wherein The edges of adjacent concave units and convex units on the fins are tangent to each other.

3. The finned tube heat exchanger core group according to claim 1, wherein The cross-sections of both the concave units and the convex units are regular hexagons.

4. The finned tube heat exchanger core group according to claim 3, characterized in that, The vertical distance H from the vertex of the concave unit or convex unit on the fin to the fin plane, the side length r of the regular hexagon, and the spherical radius R formed by the connection of the concave and convex units satisfy:

5. The finned tube heat exchanger core group according to claim 1, wherein The minor axis of the semi-ellipse on the cross-section of the enhanced heat transfer tube is perpendicular to the oncoming flow direction, and the length of the minor axis is equal to the diameter of the semi-circle. The major axis of the semi-ellipse is arranged parallel to the oncoming flow direction.

6. The finned tube heat exchanger core group according to claim 5, wherein, The ratio of the major axis length to the minor axis length of the semi-ellipse is between 1.0 and 2.

0.

7. The finned tube heat exchanger core group according to claim 1, characterized in that, Multiple enhanced heat transfer tubes form an enhanced heat transfer tube bundle, and the arrangement form of the enhanced heat transfer tube bundle is staggered arrangement or in-line arrangement.

8. The finned tube heat exchanger core group according to claim 1, characterized in that The distance between the enhanced heat transfer tubes along the mainstream direction is 1.5 to 2.5 times the diameter of the semi-circular cross-section thereof, and the distance between the enhanced heat transfer tubes perpendicular to the mainstream direction is 1.2 to 2.0 times the diameter of the semi-circular cross-section thereof.

9. The finned tube heat exchanger core group according to claim 1, wherein The fins are made of a copper-based material, and a corrosion-resistant coating is provided on its surface.

10. The finned tube heat exchanger core group according to claim 1, characterized in that, The enhanced heat transfer tubes pass through a number of fin layers by expansion joint method.

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