An acute-elliptical static mixing spoiler element and heat exchange tube

Abstract

The application discloses an acute sharp ellipse static mixing disturbance element and a heat exchange pipe, and belongs to the technical field of heat exchange equipment. The element is characterized by the following technical scheme: a special acute sharp ellipse spiral array structure is arranged in the heat exchange pipe to realize efficient radial mixing of cold and hot fluids and rapid homogenization of a temperature field. The element comprises a plurality of spiral flow guide units arranged in a circumferential array, and the cross section of each unit is an inner concave curved surface. The element presents a contraction-expansion structure with wide ends and narrow middle part in the axial profile, and a fluid accelerating throat is formed in the middle part of the element. The application utilizes the throttling acceleration effect caused by the variable cross section and the secondary vortex flow induced by the meniscus type curved surface to construct a strong shear flow field in the pipe, significantly destroys the thermal boundary layer, improves the radial mixing efficiency and the convective heat transfer coefficient of the fluid, and simultaneously realizes self-cleaning by the high-speed flushing action of the throat, thereby solving the problems of low mixing efficiency and easy scaling of the traditional static mixer in the laminar flow or transition flow.

Description

Technical Field

[0001] This invention belongs to the technical field of heat exchange equipment, and particularly relates to a sharply pointed elliptical static mixing and turbulence element and an enhanced heat exchange tube. Background Technology

[0002] In heat exchange systems used in chemical and energy industries, improving heat transfer efficiency often requires striking a balance between equipment performance and operational economy. For example, higher heat transfer coefficients are often accompanied by significant pumping energy consumption or potential blockage risks. Therefore, built-in passive enhanced heat transfer technology has attracted widespread attention. Its core lies in achieving effective disturbance of the thermal boundary layer through optimized design of the flow channel structure without significantly increasing external energy consumption.

[0003] Among commonly used static mixers, the Kenics-type spiral structure has the characteristic of low pressure drop. However, under laminar flow or low Reynolds number conditions, the fluid mainly moves forward along the spiral channel, and the radial mixing effect is limited, which to some extent affects the heat exchange efficiency between the core and the fluid near the wall. While grid structures such as the SMX type can achieve strong fluid separation and mixing effects, their flow resistance is relatively high, and they may face the risk of clogging during long-term operation in media containing particles or prone to fouling. In addition, most existing spiral mixing elements adopt a constant cross-section design, which fails to fully utilize the velocity changes and pressure pulsation effects caused by cross-sectional changes in variable cross-section flow, thus limiting further enhancement of flow field shear and turbulence. Therefore, there is an urgent need to develop a mixing heat exchange tube that achieves a balance between heat transfer enhancement and flow resistance and has self-cleaning properties. Summary of the Invention

[0004] The purpose of this invention is to provide a pointed elliptical static mixing and turbulence element and an enhanced heat exchange tube. Through a unique multi-channel array arrangement and a "waisted" axial profile, a complex contraction and expansion spiral flow field is constructed inside the tube, achieving efficient radial mixing of cold and hot fluids and rapid homogenization of the temperature field.

[0005] To achieve the above objectives, the present invention provides a sharply pointed elliptical static hybrid flow disturbance element, comprising multiple elliptical spiral flow guiding units evenly distributed in a circular array around the central axis of the element.

[0006] Furthermore, the main body of each of the sharply pointed elliptical spiral guide units is formed by extending sharply pointed elliptical blades along the axial direction and twisting them at a preset spiral angle; the sharply pointed elliptical spiral guide unit adopts a biomimetic elliptical leaf-shaped streamlined structure, the ratio of its major axis to minor axis in its cross-section is 1.5~3.0, both ends are designed with sharp angles, the included angle of the tangents on both sides of the tip is 5~45°, and the ratio of the transition fillet radius at the tip to the length of the major axis is less than 0.02, forming a sharp edge; the spiral twist angle of a single elliptical spiral guide unit along the axial direction is 90~270°, and the spiral helix angle changes continuously with the axial position;

[0007] Furthermore, the multiple pointed elliptical spiral guide units are evenly distributed in a circular array with the central axis of the element as the axis of symmetry, forming multiple independent spiral flow channels; in the pointed elliptical static mixing turbulence element, the multiple pointed elliptical spiral guide units converge towards the central axis in the middle, presenting a contraction and expansion structure in the axial profile, forming a throat, so that the outer circle diameter in the middle of the pointed elliptical static mixing turbulence element is smaller than the outer circle diameter at both ends, thereby forming a variable cross-section flow field that expands, contracts, and then expands again when the fluid flows through it.

[0008] Furthermore, the cross-section of the sharply pointed elliptical spiral flow guiding unit is a concave meniscus surface, with the concave surface of the meniscus facing the center of the flow channel and the backflow surface being a convex surface.

[0009] Furthermore, the multiple elliptical spiral guide units are interconnected at the contraction position, i.e., the throat, in the middle of the element to form a self-supporting central node; at both ends of the element, there is a radial gap between adjacent spiral guide units.

[0010] Furthermore, the shrinkage ratio of the element, that is, the ratio of the smallest circumscribed circle diameter in the middle to the largest circumscribed circle diameter at both ends, is 0.5 to 0.8.

[0011] Furthermore, the edges of the elliptical spiral flow guiding unit have a sharp blade-like structure, which is used to physically cut the fluid boundary layer and further thin the laminar sublayer.

[0012] Furthermore, the blade body region of the sharply pointed elliptical spiral guide unit is provided with a through-type guide hole / groove array; the guide hole / groove array is distributed at equal or variable intervals along the spiral extension trajectory of the elliptical spiral guide unit, and is located between the central node and the edge guide edge of the elliptical spiral guide unit; each guide hole / groove connects the concave curved surface of the blade and the backflow convex surface, forming a pressure balance channel for the fluid on both sides of the blade; the guide hole / groove is a long strip slit, circular micropore or polygonal hole extending along the spiral streamline direction.

[0013] Another object of the present invention is to provide an enhanced mixing heat exchange tube, comprising a heat exchange tube body and a sharply pointed elliptical static mixing turbulence element as described in any one of claims 1-6; the sharply pointed elliptical static mixing turbulence elements are arranged in series along the axial direction, and the spiral directions of two adjacent sharply pointed elliptical static mixing turbulence elements are opposite and staggered by 45~90°.

[0014] Compared with the prior art, the beneficial technical effects of the present invention are:

[0015] (1) This invention constructs a "wide at both ends and narrow in the middle" contraction-expansion structure in the axial profile. Utilizing the Bernoulli effect generated by the contraction of the throat flow channel, the fluid velocity increases sharply, forming a high-intensity shear stress field. This can efficiently break up droplets or bubbles in multiphase flow, achieving microscopic uniform dispersion, and effectively remove dirt from the pipe wall and component surface by utilizing the scouring action of high-speed fluid, solving the problem of scaling and clogging of traditional mixing elements at low flow rates.

[0016] (2) This invention induces a strong secondary circulation of Dean's vortex through a macroscopically shaped concave surface, which, combined with a local array of guide holes / grooves on the blade surface, achieves multi-scale synergistic enhancement of heat transfer. The concave structure draws the central fluid to the tube wall, while the guide holes / grooves utilize the pressure difference on both sides of the blade to form penetrating flow, directly disrupting the laminar sublayer attached to the blade surface. This structure greatly improves the radial mixing efficiency and Nusselt number of the fluid, eliminating heat transfer dead zones.

[0017] (3) The flow guiding unit adopts a biomimetic elliptical leaf streamline design and a sharp angle design, which effectively reduces the flow resistance and pressure drop loss when the fluid impacts the blade. At the same time, multiple spiral units converge at the throat to form a self-supporting central node, which significantly enhances the overall mechanical rigidity of the component. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a pointed elliptical static mixing turbulence element and an enhanced heat exchange tube according to the present invention.

[0019] Figure 2 This is a schematic diagram of a sharply pointed elliptical static hybrid turbulence element structure according to the present invention.

[0020] Figure 3 This is an axial top view (inlet end) of a sharply pointed elliptical static mixing turbulence element described in this invention.

[0021] Figure 4 This is an axial bottom view (outlet end) of a sharply pointed elliptical static mixing turbulence element described in this invention.

[0022] Figure 5 This is a schematic diagram of the opening of a sharply pointed elliptical static hybrid turbulence element according to the present invention.

[0023] Among them, 1, heat exchange tube shell; 2, a pointed elliptical static mixing turbulence element; 2-1, elliptical spiral flow guiding unit; 2-2, throat; 2-3, concave curved surface; 2-4, radial gap; 2-5, center node; 2-6, flow guiding hole / groove. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments:

[0025] like Figures 1 to 5 As shown, the present invention provides a sharply pointed elliptical static mixing turbulence element, which is composed of multiple elliptical spiral flow guiding units.

[0026] Example 1

[0027] See Figures 1 to 5 The aforementioned sharply pointed elliptical static hybrid flow-disrupting element 2 comprises multiple elliptical spiral flow-guiding units 2-1 with identical structures. These multiple elliptical spiral flow-guiding units 2-1 are arranged at 90° intervals around the major axis of the element, forming a 2×2 matrix channel layout in space. Further, as... Figure 2 As shown, the axial profile of element 2 is not cylindrical, but exhibits a significant "waist" characteristic. Specifically, the middle portion of the element contracts towards the center, forming a fluid acceleration throat 2-3. When fluid flows through this location, the flow cross-sectional area decreases, and the flow velocity increases sharply. According to Bernoulli's principle, high flow velocity generates strong shear force, which can break up droplets or bubbles in the fluid. Furthermore, as... Figure 1 As shown, the cross-section of each elliptical spiral guide unit 2 is crescent-shaped, forming a concave surface 2-3. This design allows the fluid to be captured and drawn back by the concave surface 2-3 under the centrifugal force generated by the spiral motion, forming a strong local vortex, thereby enhancing the heat exchange between the pipe wall and the central fluid.

[0028] Example 2

[0029] Example 2, based on Example 1, aims to improve the structural stability and mixing strength. Further, as... Figure 2 and Figure 3 As shown, multiple elliptical spiral guide units 2 are solidly connected to each other at the narrowest throat 2-2 in the middle, forming a high-strength central node 2-5. This allows element 2 to withstand the impact of high-pressure fluid without twisting or deformation. Furthermore, at the upper and lower ends of element 2, adjacent elliptical spiral guide units 2-1 are not closed off, but rather have radial gaps 2-4. These radial gaps 2-4 allow the fluid to laterally mix between different spiral channels as it flows out of one element and into the next.

[0030] Example 3

[0031] This embodiment, based on Embodiments 1 and 2, further optimizes the local flow field and heat transfer boundary layer on the blade surface. For example... Figure 5 As shown, the blade surface of the elliptical helical flow guiding unit 2-1 is not a completely closed solid, but rather has permeable flow guiding holes / grooves 2-6. These flow guiding holes / grooves 2-6 are spaced apart along the helical extension direction of the helical flow guiding unit, and can be designed as elongated slits or arrayed circular holes. The fluid dynamics principle of this design is that when the fluid flows at high speed within the helical channel, a significant pressure difference is generated between the concave curved surface 2-3 of the elliptical helical flow guiding unit 2-1 and the convex surface on the back. Furthermore, driven by this pressure difference, some fluid is ejected at high speed from the high-pressure side to the low-pressure side through the flow guiding holes / grooves 2-6, forming a penetrating "micro-jet." This micro-jet directly impacts and disrupts the laminar sublayer attached to the blade surface, not only eliminating heat transfer dead zones but also effectively preventing the deposition and fouling of tiny particles on the blade surface. By combining the macroscopic helical secondary flow with the microscopic perforated jet, multi-scale synergistic turbulence is achieved, thereby further improving the overall heat transfer performance of the element without significantly increasing flow resistance.

[0032] Example 4

[0033] This embodiment relates to the arrangement of the aforementioned components in a heat exchange tube. Further, within heat exchange tube 1, multiple components are arranged in series along the axial direction. The rotation directions of adjacent components are opposite. Further, adjacent components are staggered by 45° in circumferential installation angle. This staggered arrangement allows multiple streams of fluid flowing out from the previous stage to directly impact the leading edge of the blades of the next stage component, resulting in further intense cutting and splitting. Through this repeated axial shearing and splitting process, the fluid is continuously subjected to radial mixing and secondary flow disturbance, continuously disrupting the thermal boundary layer and significantly improving the convective heat transfer efficiency and overall heat transfer performance within the heat exchange tube.

[0034] The embodiments of this invention do not describe well-known technical solutions and characteristics in detail. Those skilled in the art can make modifications and improvements without departing from the technical solutions of this invention, and all such modifications and improvements fall within the protection scope of this invention.

Claims

1. A sharp-edged elliptical static mixing spoiler element characterized by: The system comprises multiple identical, sharply pointed elliptical spiral guide units. Each unit's main body is formed by a sharply pointed elliptical blade extending axially and twisting at a preset spiral angle. The sharply pointed elliptical spiral guide unit adopts a biomimetic elliptical leaf-shaped streamlined structure with a cross-sectional major axis to minor axis ratio of 1.5 to 3.

0. Both ends are designed with sharp angles, with the included angle between the tangents at the tip being 5 to 45°. Furthermore, the ratio of the transition fillet radius at the tip to the major axis length is less than 0.02, forming a sharp edge. The spiral twist angle of a single elliptical spiral guide unit along the axial direction is 90 to 270°, and the spiral angle continuously changes with the axial position. The multiple pointed elliptical spiral guide units are evenly distributed in a circular array with the central axis of the element as the axis of symmetry, forming multiple independent spiral flow channels; in the pointed elliptical static mixing turbulence element, the multiple pointed elliptical spiral guide units converge towards the central axis in the middle, presenting a contraction and expansion structure in the axial profile, forming a throat, so that the outer circle diameter in the middle of the pointed elliptical static mixing turbulence element is smaller than the outer circle diameter at both ends, thereby forming a variable cross-section flow field that expands, contracts, and then expands again when the fluid flows through it.

2. An acute ovoid static mixing spoiler element according to claim 1, wherein: The cross-section of the sharply pointed elliptical spiral flow guiding unit is a concave meniscus surface, with the concave side of the meniscus facing the center of the flow channel and the back flow surface being a convex surface.

3. An acute ovoid static mixing spoiler element according to claim 1, wherein: The multiple elliptical spiral flow guiding units are interconnected at the contraction position, i.e., the throat, in the middle of the element to form a self-supporting central node; at both ends of the element, there is a radial gap between adjacent elliptical spiral flow guiding units.

4. An acute ovoid static mixing spoiler element according to claim 1, wherein: The shrinkage ratio of the component, i.e., the ratio of the smallest circumscribed circle diameter in the middle to the largest circumscribed circle diameter at both ends, is 0.5 to 0.

8.

5. The sharply pointed elliptical static hybrid turbulence element according to claim 1, characterized in that: The edges of the elliptical spiral flow guiding unit have a sharp blade-like structure.

6. The sharply pointed elliptical static hybrid turbulence element according to claim 1, characterized in that: The blade body of the sharply pointed elliptical spiral guide unit is provided with a through-type array of guide holes / grooves; the array of guide holes / grooves is distributed at equal or variable intervals along the spiral extension trajectory of the elliptical spiral guide unit and is located between the central node and the edge of the elliptical spiral guide unit; each guide hole / groove connects the concave curved surface of the blade and the convex surface of the backflow, forming a pressure balance channel for the fluid on both sides of the blade; the guide holes / grooves are elongated slits, circular micropores or polygonal holes extending along the spiral streamline direction.

7. A heat exchange tube for enhanced mixing, characterized in that: It includes a heat exchange tube body and a pointed elliptical static mixing turbulence element as described in any one of claims 1-6; the pointed elliptical static mixing turbulence elements are arranged in series along the axial direction, and the spiral directions of two adjacent pointed elliptical static mixing turbulence elements are opposite and staggered by 45~90°.

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