Turbulent flow insert and enhanced heat transfer tube

Abstract

The application belongs to the technical field of heat exchange equipment, and particularly discloses a turbulence plug-in and a heat exchange pipe with the turbulence plug-in. The turbulence plug-in comprises a fixed shaft and a plurality of turbulence elements, and the plurality of turbulence elements are connected in series on the fixed shaft. The turbulence element comprises a plurality of turbulence fins and a center column, the turbulence fins are connected with the center column, the center column is connected with the fixed shaft, and the axis of the center column coincides with the axis of the fixed shaft. The included angle between the turbulence fin and the negative direction of the axis of the center column is 20-80°, the turbulence fin is fan-shaped and inwardly curved, and the arc length of the fixed end of the turbulence fin is smaller than the arc length of the free end of the turbulence fin. The heat exchange pipe comprises a pipe body and the above-mentioned turbulence plug-in, and the fixed shaft is arranged in the pipe body and extends along the axial direction of the pipe body. The application can significantly improve the heat exchange performance with a small increase in the flow resistance of the heat exchanger, and has simple structure, wide application range, high economic practicability and popularization value.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of heat exchange equipment, and particularly relates to a turbulence plug-in and a heat exchange pipe with the turbulence plug-in. BACKGROUND

[0002] As an important heat and mass transfer process equipment, heat exchangers are widely used in common processes in the industries of nuclear energy, refrigeration, heating, chemical industry, metallurgy, petroleum, aerospace, etc. Improving the thermal performance of heat exchange pipes is of great significance to improving the energy utilization rate of heat exchangers.

[0003] Under a certain heat exchange range, the goal of heat exchange enhancement is to reduce the volume of heat exchange equipment while reducing energy consumption as much as possible and improving economic benefits. Heat exchange technology mainly includes active heat transfer enhancement technology, passive heat transfer enhancement technology and composite heat transfer technology. Active technology requires additional pump work for the heat exchange system, increasing the complexity of the system; passive heat transfer enhancement technology refers to modifying the heat transfer surface or adding enhancement devices in the fluid, and using passive heat transfer enhancement technology to improve the working efficiency of heat exchange pipes is an important topic.

[0004] According to the theory of convective heat transfer, 70% to 90% of the heat transfer resistance in the convective heat transfer process in the heat exchange pipe is concentrated in the boundary layer of the fluid near the inner wall of the heat exchange pipe. Therefore, destroying the boundary layer of the fluid can effectively reduce the thermal resistance and increase the heat exchange capacity of the heat exchange pipe.

[0005] Inserting a turbulence plug into the pipe is a simple and effective passive heat transfer enhancement method. The turbulence plug is mainly used in the heat exchange pipe of the shell-and-tube heat exchange equipment. By splitting or swirling the fluid in the pipe, the boundary layer of the fluid in the pipe is thinned, the deposition of dirt is always at a low level, and the convective heat transfer coefficient of the fluid in the pipe is increased, thereby achieving the effect of heat transfer enhancement. However, the existing turbulence plug causes a significant increase in flow resistance while enhancing heat transfer. SUMMARY

[0006] An object of the present application is to provide a turbulence plug-in that effectively solves the problem of a significant increase in flow resistance while enhancing heat transfer of the existing turbulence plug.

[0007] To solve the above technical problems, the technical solution adopted by the present application is as follows:

[0008] A turbulence plug-in includes a fixed shaft and a plurality of turbulence elements, and the plurality of turbulence elements are connected in series on the fixed shaft.

[0009] The turbulence element includes a plurality of turbulence fins and a center column, the turbulence fins are connected with the center column, the center column is connected with the fixed shaft, and the axis of the center column coincides with the axis of the fixed shaft.

[0010] The included angle between the spoiler fin and the negative direction of the axis of the central column is 20-80 degrees, the spoiler fin is fan-shaped and inwardly curved, and the arc length of the fixed end of the spoiler fin is smaller than that of the free end of the spoiler fin.

[0011] Further, the fixed shaft is cylindrical or prismatic.

[0012] Further, the spoiler element comprises 2-4 spoiler fins and one central column.

[0013] Further, the spoiler fins of the spoiler element are uniformly arranged along the central column in the circumferential direction.

[0014] Further, the adjacent spoiler elements are arranged in a staggered manner, and the staggered angle of the adjacent spoiler elements is 0-90 degrees.

[0015] Another object of the present application is to provide a heat exchange tube, which effectively solves the problem of large flow resistance and wall fouling caused by the existing heat transfer enhancement.

[0016] A heat exchange tube, comprising a tube body and a spoiler insert as described in the above embodiments, the fixed shaft is arranged in the tube body and extends along the axial direction of the tube body.

[0017] Further, a support is further included, which is fixed in the tube body, and the inner part of the support is provided with a fixing frame for sleeving the spoiler insert.

[0018] Further, the distance between the outer edge of the spoiler element and the axis of the tube body is 0.50-0.98 times the inner diameter of the tube body.

[0019] Further, the distance between the adjacent spoiler elements is 0.5-4.0 times the inner diameter of the tube body.

[0020] Further, the axis of the fixed shaft coincides with the central axis of the tube body.

[0021] Compared with the prior art, the present application has the following beneficial technical effects:

[0022] (1) The present application sets a spoiler insert in the tube body to strengthen the disturbance of the fluid medium in the tube, enhance the heat exchange between the fluid medium and the inner wall of the tube, and strengthen the scouring of the fluid medium on the inner wall of the tube, which effectively prevents the inner wall of the tube from being fouled and ensures that the heat exchange efficiency of the heat exchange tube does not decrease significantly during use.

[0023] (2) The application can significantly improve the heat exchange performance with less increase of flow resistance of the heat exchanger, and has simple structure, wide application range, high economic practicability and popularization value. In practical application, by changing the included angle of the spoiler fin and the center column, the number of the spoiler fin on the spoiler element and the connection position of the spoiler fin, the heat exchange performance and pressure drop of the enhanced heat exchange tube can be adjusted, so that the comprehensive heat exchange effect and resistance of the heat exchanger can reach the optimal application requirement, and the energy utilization rate is improved. BRIEF DESCRIPTION OF DRAWINGS

[0024] The application will be further described in detail below in combination with the drawings and specific embodiments.

[0025] Figure 1 is a structural schematic diagram of the spoiler insert of the application;

[0026] Figure 2 is a partial structural schematic diagram of the spoiler insert of the application;

[0027] Figure 3 is a structural schematic diagram of the enhanced heat exchange tube of the application, wherein the hollow arrow indicates the flow direction of the fluid medium in the enhanced heat exchange tube;

[0028] Figure 4 is the variation law of the resistance coefficient f of the embodiment 1 and the comparative example 1 with the Reynolds number Re;

[0029] Figure 5 is the variation law of the Nusselt number Nu of the embodiment 1 and the comparative example 1 with the Reynolds number Re;

[0030] Figure 6 is the variation law of the comprehensive performance evaluation index PEC of the embodiment 1 with the Reynolds number Re;

[0031] Figure 7 is the variation law of the resistance coefficient f of the embodiment 2 and the comparative example 2 with the Reynolds number Re;

[0032] Figure 8 is the variation law of the Nusselt number Nu of the embodiment 2 and the comparative example 2 with the Reynolds number Re;

[0033] Figure 9 is the variation law of the comprehensive performance evaluation index PEC of the embodiment 2 and the comparative example 2 with the Reynolds number Re. DETAILED DESCRIPTION

[0034] Embodiment 1:

[0035] In combination with Figure 1 and Figure 2A turbulence insert includes a fixed shaft 1 in the shape of a cylinder or prism and a plurality of turbulence elements 2 connected in series on the fixed shaft 1. The turbulence element 2 includes 2-4 turbulence fins 3 and a central column 4, the turbulence fins 3 are connected to the central column 4, the central column 4 is connected to the fixed shaft 1, and the axis of the central column 4 coincides with the axis of the fixed shaft 1.

[0036] The angle between the turbulence fin 3 and the negative direction of the axis of the central column 4 is 20°-80°, and the specific angle can be determined according to the actual situation. However, it is worth noting that the larger the angle between the turbulence fin 3 and the negative direction of the axis of the central column 4, the better the heat transfer enhancement effect, but the greater the fluid resistance.

[0037] The turbulence fin 3 is fan-shaped and inwardly curved, and the arc length of the fixed end of the turbulence fin 3 is smaller than that of the free end of the turbulence fin 3. The turbulence fins 3 of the turbulence element 2 are evenly arranged circumferentially along the central column 4. The adjacent turbulence elements 2 are arranged in a staggered manner, and the staggered angle of the adjacent turbulence elements 2 is 0°-90°.

[0038] In some embodiments, the number of turbulence fins 3 on each turbulence element 2 of the turbulence insert is the same, and the angle between the turbulence fin 3 and the negative direction of the axis of the central column 4 is also the same.

[0039] Embodiment 2:

[0040] A heat transfer enhancement tube, in combination Figure 3 , includes a tube body 5, a support 6, and the turbulence insert of embodiment 1, the fixed shaft 1 is arranged in the tube body 5 and extends along the axial direction of the tube body 5. The axis of the fixed shaft 1 coincides with the central axis of the tube body 5, the support 6 is fixed in the tube body 5, and the inside of the support 6 is provided with a fixed frame 7 for matching the turbulence insert. In this embodiment, the support 6 has two, and the two supports 6 are located at the two ends of the turbulence insert.

[0041] The distance between the outer edge of the turbulence element 2 and the axis of the tube body 5 is 0.50-0.98 times the inner diameter of the tube body 5, and the number of turbulence elements 2 is 1-20.

[0042] The distance between adjacent turbulence elements 2 is 0.5-4.0 times the inner diameter of the tube body 5. The specific distance can be determined according to the actual situation, but it is worth noting that the smaller the distance between the turbulence elements 2, the better the heat transfer enhancement effect, but the greater the fluid resistance.

[0043] The thickness of the spoiler fin 3 and the diameter of the fixing frame 7 are not greater than 0.1 times the inner diameter of the pipe body 5. When the inner diameter of the pipe body 5 is 40 mm, the thickness of the spoiler fin 3 is not greater than 4.0 mm. The thickness of the spoiler fin 3 is determined according to the actual situation and the processing condition.

[0044] The manufacturing method of the heat transfer enhanced pipe is as follows: first, connecting the spoiler fin 3 to the center column 4, then connecting the center column 4 to the fixed shaft 1, then respectively sleeving the two supporting members 6 to the two ends of the spoiler fin 3 through the fixing frame 7, then inserting the supporting member 6 and the spoiler fin 3 into the pipe body 5, and finally screwing the supporting member 6 and the inner wall of the pipe body 5.

[0045] In the present application, the connection mode of the spoiler fin 3 and the center column 4 and the connection mode of the center column 4 and the fixed shaft 1 can adopt movable connection forms such as a flat key, a bolt, a buckle, a hinge, etc., so as to realize the angle adjustment of the spoiler fin 3 and the center column 4 and the position adjustment of the spoiler element 2 on the fixed shaft 1; or can adopt fixed connection forms such as welding, etc.

[0046] In the present application, the spoiler fin 3 and the center column 4 are connected, and the center column 4 and the fixed shaft 1 are connected, so as to realize the angle adjustment of the spoiler fin 3 and the center column 4 and the position adjustment of the spoiler element 2 on the fixed shaft 1.

[0047] The spoiler element 2 of the present application is coupled with the inner wall of the pipe body 5 to induce the generation of hairpin vortex and radial secondary flow, so as to realize the reduction of the wall friction and the thickness of the temperature boundary layer. Therefore, the present application can significantly improve the heat transfer performance with little increase of the flow resistance of the heat transfer pipe, and has simple structure, wide application range, high economic practicability and popularization value.

[0048] In practical application, by changing the angle between the spoiler fin 3 and the center column 4, the number of the spoiler fin 3 on the spoiler element 2 and the connection position of the spoiler fin 3, the heat transfer performance and the pressure drop of the heat transfer enhanced pipe can be adjusted, so as to make the comprehensive heat transfer effect and the resistance of the heat transfer pipe optimal, and improve the energy utilization rate.

[0049] Example 1

[0050] In the embodiment, the full length L of the enhanced heat exchange tube is 852 mm, and the inner diameter D of the tube body is 40 mm. The enhanced heat exchange tube is provided with the turbulence insert of the application, wherein each turbulence element 2 is provided with three turbulence fins 3, and the turbulence fins 3 are circumferentially and uniformly arranged along the central column 4. The full length of the turbulence insert is 732 mm. The thickness of the turbulence fin 3 is 2 mm, and the included angle between the turbulence fin 3 and the negative direction of the axis of the central column 4 is 60°. The diameter of the central column 4 is 10 mm. The fixed shaft 1 is a prism with a size of 3 mm*3 mm*732 mm, and the distance between adjacent turbulence elements 2 on the fixed shaft 1 is 60 mm. The working medium in the enhanced heat exchange tube is water.

[0051] Comparative Example 1

[0052] In the comparative example, the size specifications of the enhanced heat exchange tube and the working medium in the enhanced heat exchange tube are completely the same as those of Example 1, but no turbulence insert is arranged in the enhanced heat exchange tube in the comparative example.

[0053] Under the laminar flow condition, the resistance and heat transfer of the enhanced heat exchange tube provided with the turbulence insert (Example 1) are numerically calculated, and are compared and analyzed with the enhanced heat exchange tube without the turbulence insert (Comparative Example 1), and the results are shown in Figure 4 , Figure 5 and Figure 6 .

[0054] Figure 4 The variation law of the resistance coefficient f with the Reynolds number Re is shown. As shown in Figure 4 , under the same working condition, the resistance coefficient of Example 1 is higher than that of Comparative Example 1. According to the simulation results, it can be obtained that the resistance coefficient of Example 1 is increased by 466.7% to 1203.5% than that of Comparative Example 1.

[0055] Figure 5 The variation law of the Nusselt number Nu with the Reynolds number Re is shown. As shown in Figure 5 , under the same working condition, the Nusselt number of Example 1 is much higher than that of Comparative Example 1. According to the simulation results, it can be obtained that the Nusselt number of Example 1 is increased by 468.6% to 994.1% than that of Comparative Example 1.

[0056] Figure 6 The variation law of the comprehensive performance evaluation index PEC with the Reynolds number Re is shown. As shown in Figure 6 , the PEC value of Example 1 is as high as 3.19 to 4.65, and the comprehensive enhanced heat exchange performance is high.

[0057] Example 2

[0058] In this embodiment, compared with embodiment 1, the total length of the enhanced heat exchange tube is changed from 852 mm to 850 mm, the fixed shaft 1 is changed from 3 mm*3 mm*732 mm to 3 mm*3 mm*720 mm, and other parameters are the same as those in embodiment 1. The working medium in the enhanced heat exchange tube is water.

[0059] Comparative example 2

[0060] In this comparative example, the size specification of the enhanced heat exchange tube and the working medium in the enhanced heat exchange tube are completely the same as those in embodiment 2, but the difference is that the enhanced heat exchange tube in this comparative example is provided with a conventional turbulence insert, an SK type static mixer. In the SK type static mixer, the turbulence elements are rectangular blade rotated by 180°, and the left and right rotating arrangements are placed in the empty tube. The length of each turbulence element is 60 mm, the distance between adjacent elements is 60 mm, a total of 6 turbulence elements are placed, the length of the turbulence section is 720 mm, and the blade thickness is 2 mm.

[0061] In the range of Re = 300-1500, the resistance and heat transfer of the enhanced heat exchange tube provided with the SK type static mixer as the turbulence insert (comparative example 2) are numerically simulated, and compared with the numerical simulation results of embodiment 2. The results are shown in Figure 7 , Figure 8 and Figure 9 .

[0062] Figure 7 The change law of the resistance coefficient f with the Reynolds number Re is shown. As can be seen from Figure 7 , under the same working conditions, the resistance coefficient of embodiment 2 is lower than that of comparative example 2. According to the simulation results, it can be obtained that the resistance coefficient of comparative example 2 is increased by 178.91%-968.58% than that of embodiment 2.

[0063] Figure 8 The change law of the Nusselt number Nu with the Reynolds number Re is shown. As can be seen from Figure 8 , under the same working conditions, the Nusselt number of comparative example 2 is higher than that of embodiment 2. According to the simulation results, it can be obtained that the Nusselt number of comparative example 2 is increased by 30.12%-78.78% than that of embodiment 2.

[0064] Figure 9 The change law of the comprehensive performance evaluation index PEC with the Reynolds number Re is shown. As can be seen from Figure 9 , under the same working conditions, the PEC value of embodiment 2 is higher than that of comparative example 2. According to the simulation results, it can be obtained that the PEC value of embodiment 2 is increased by 7.25%-19.66% than that of comparative example 2.

[0065] In summary, the heat exchange tube with the spoiler insert can strengthen heat transfer while increasing flow resistance, but compared with the conventional heat exchange tube with the spoiler insert (SK static mixer), the heat exchange tube has the advantages of high efficiency, low resistance and high comprehensive performance of heat transfer.

[0066] The above examples are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and to implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made according to the spirit and essence of the present application shall be covered within the protection scope of the present application.

Claims

1. A spoiler insert, characterized in that, The fixed shaft and a plurality of turbulence elements are connected in series. The turbulence element comprises a plurality of turbulence fins and a central column, and the turbulence fins and the central column are movably connected with the central column and the fixed shaft, and the axis of the central column coincides with the axis of the fixed shaft. The included angle between the turbulence fins and the negative direction of the axis of the central column is 20°-80°, the turbulence fins are fan-shaped and inwardly curved, and the arc length of the fixed end of the turbulence fins is smaller than that of the free end of the turbulence fins.

2. The spoiler insert of claim 1, wherein, The fixed shaft is cylindrical or prismatic.

3. The spoiler insert of claim 2, wherein, The turbulence element comprises 2-4 turbulence fins and one central column.

4. The spoiler insert of claim 3, wherein, The turbulence fins of the turbulence element are uniformly arranged circumferentially along the central column.

5. The spoiler insert of claim 4, wherein, The adjacent turbulence elements are arranged in a staggered manner, and the staggered angle of the adjacent turbulence elements is 0°-90°.

6. A heat exchange tube, characterized by The fixed shaft is arranged in the pipe body and extends along the axial direction of the pipe body.

7. The enhanced heat transfer tube of claim 6 wherein, A support is further arranged in the pipe body, and the inside of the support is provided with a fixing frame for sleeving the turbulence insert.

8. The strengthened heat exchange tube of claim 7, wherein The distance between the outer edge of the turbulence element and the axis of the pipe body is 0.50-0.98 times the inner diameter of the pipe body.

9. The enhanced heat transfer tube of claim 8 wherein, The distance between the adjacent turbulence elements is 0.5-4.0 times the inner diameter of the pipe body.

10. The strengthened heat exchange tube of claim 6, wherein The axis of the fixed shaft coincides with the central axis of the pipe body.

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