High-efficiency evaporation heat exchange tube with mesh axial spiral groove on outer surface
By designing a mesh-like axial spiral channel on the outer surface of the evaporative heat exchange tube, the problem of insufficient bubble nucleation number was solved, achieving more efficient heat exchange performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SUZHOU XINTAI COPPER HIGH-EFFICIENCY TUBE CO LTD
- Filing Date
- 2025-06-23
- Publication Date
- 2026-06-12
AI Technical Summary
Existing evaporative heat exchange tubes have limitations in improving boiling heat transfer performance, especially due to insufficient bubble nucleation, which affects heat transfer efficiency.
A mesh-like axial spiral channel is designed on the outer surface of the evaporative heat exchanger tube, including T-shaped outer fins, mesh-like outer channels, side channels and grooves, forming a complex channel network that promotes liquid flow and uniform distribution and increases the number of vaporization nuclei.
By optimizing the channel structure, the uniformity of liquid flow and the density of vaporization cores were improved, significantly enhancing heat transfer performance, especially the heat transfer efficiency under high heat flux density conditions.
Smart Images
Figure CN224353663U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of heat exchange tubes, and in particular to a high-efficiency evaporative heat exchange tube with a mesh-like axial spiral groove on its outer surface. Background Technology
[0002] Evaporative heat exchange tubes are commonly used in evaporators, such as flooded evaporators in chiller units of central air conditioning systems. Currently commercially available evaporative heat exchange tubes consist of a tube body with an inner cavity and fins spirally distributed along the tube's axis on its outer surface, along with spiral channels formed between the fins. The tops of the fins are machined with cuts along the spiral direction, and bosses are formed between the evenly distributed cuts on the same fin. Through mechanical pressing, the bosses extend to both sides of the fins, covering the channels between the fins and forming a cavity structure. Gaps are left between the extended portions of adjacent bosses as vents for the cavities.
[0003] During the heat exchange process, water flows through the tube and transfers heat to the refrigerant on the outside of the heat exchange tube. When the refrigerant is heated, it boils and produces a large number of bubbles. Thus, the refrigerant uses phase change to remove the heat from the water, thereby achieving the purpose of producing low-temperature cold water.
[0004] According to heat transfer theory, boiling heat transfer mainly involves three processes: bubble nucleation, bubble growth, and bubble detachment from the heat transfer surface. The number of nucleated bubbles is a key factor. According to Cassie theory, when the heat transfer surface is rough, the liquid cannot completely fill the depressions on the rough surface; air remains trapped beneath the droplet, becoming vaporization nuclei. After boiling, even after the bubbles detach from the surface, some vapor remains trapped in the depressions, preparing for the next boiling cycle. In short, the air or vapor trapped in the depressions beneath the liquid increases the nucleation density, increases the number of bubble nuclei, and improves the boiling heat transfer coefficient.
[0005] The falling film evaporator tube with a mesh outer surface, as described in Announcement No. CN 103047891 B, employs "T"-shaped fins and a cavity structure on the outer surface of the heat exchange tube, and adds mesh grooves to the outer surface. This enhances the flow of the falling film liquid on the surface, overcomes the disadvantage of the liquid not flowing easily along the axial direction, and achieves uniform distribution of the liquid on the surface of the heat exchange tube. However, the bottom of the cavity is a smooth and flat surface, which limits the number of bubble nuclei generated and affects further improvement of the evaporator tube performance. Utility Model Content
[0006] To address the shortcomings of existing technologies, the main objective of this invention is to overcome these deficiencies by disclosing a high-efficiency evaporative heat exchange tube with a mesh-like axial spiral channel on its outer surface. The tube includes a tube body with an inner cavity and outer fins spirally wrapped around its outer surface.
[0007] The outer fin has a T-shaped cross-section, and the outer surface of the outer fin is provided with a grid-like outer channel. A cavity is formed between axially adjacent outer fins, and the outer surface of the tube is recessed with a grid-like groove. The outer fin includes a vertical part and a horizontal part. Side channels are recessed on both sides of the vertical part. A gap is provided between axially adjacent horizontal parts.
[0008] Furthermore, the outer channel includes a first outer channel, a second outer channel, and a third outer channel. The angle between the first outer channel and the axis is 45°±5°; the angle between the second outer channel and the axis is 135°±5°; and the angle between the third outer channel and the axis is 5°-40°.
[0009] Furthermore, the width of the outer channel is 0.02-0.5mm and the depth is 0.02-0.4mm.
[0010] Furthermore, the trench includes a first trench and a second trench, the first trench and the second trench are intersecting, and the intersection point between the first trench and the second trench forms a vaporization nucleus.
[0011] Furthermore, the number of vaporization cores is 50-100 per square centimeter.
[0012] Furthermore, the width of the groove is 0.05-0.5 mm and the depth is 0.02-0.2 mm.
[0013] Furthermore, the side channel includes a first side channel and a second side channel, which intersect to form a mesh structure.
[0014] Furthermore, the width of the side channel is 0.05-0.5mm and the depth is 0.02-0.2mm.
[0015] Furthermore, the inner surface of the tube is provided with a spirally extending inner channel, the depth of which is 0.1-0.6 mm.
[0016] Furthermore, the gap width is 0.2-1mm.
[0017] The beneficial effects achieved by this utility model are as follows:
[0018] This invention features T-shaped outer fins on the surface, along with grooves on the tube body, external channels on the outer fins, and side channels on the sidewalls of the outer fins. These features promote surface liquid flow, effectively preventing the reduction of dry-evaporation zones under high heat flux density and improving heat exchange performance. The external channels are relatively large, while the side channels and grooves are narrow. The external channels facilitate liquid replenishment, while the side channels and grooves utilize capillary pressure differences to drive liquid flow from areas with abundant liquid to areas with scarce liquid, improving the uniformity of the surface liquid film and thus significantly enhancing heat exchange efficiency. Furthermore, the external channel surface, with its numerous channels in three directions, forms a comprehensive channel network, further promoting liquid flow. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of the overall structure of a high-efficiency evaporative heat exchange tube with a mesh-like axial spiral groove on its outer surface, according to the present invention.
[0020] Figure 2 This is a partial unfolded schematic diagram of a high-efficiency evaporative heat exchange tube with a mesh-like axial spiral groove on its outer surface, according to the present invention.
[0021] Figure 3 for Figure 2 Enlarged view of A in the middle;
[0022] Figure 4 for Figure 2 The main view;
[0023] Figure 5 for Figure 3 AA section view;
[0024] Figure 6 for Figure 5 Enlarged view of A in the middle;
[0025] Figure 7 for Figure 5 BB section view;
[0026] Figure 8 for Figure 2 Top view;
[0027] Figure 9 for Figure 8 Enlarged view of A in the middle;
[0028] Figure 10 This is a comparison chart of the performance test data of the evaporation heat exchanger tube in this embodiment with high-performance evaporation heat exchanger tubes and conventional flooded evaporation heat exchanger tubes;
[0029] The attached figures are labeled as follows:
[0030] 1. Tube body, 2. Outer fins, 21. Vertical part, 22. Horizontal part, 3. Outer channel, 31. First outer channel, 32. Second outer channel, 33. Third outer channel, 4. Cavity, 5. Gap, 6. Groove, 61. First groove, 62. Second groove, 7. Side channel, 71. First side channel, 72. Second side channel, 8. Inner channel. Detailed Implementation
[0031] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this utility model and are not intended to limit this utility model.
[0032] A high-efficiency evaporative heat exchange tube with a mesh-like axial spiral channel on its outer surface, such as... Figures 1-9 As shown, the device includes a tube body 1 with an inner cavity, and outer fins 2 spirally wrapped around the outer surface of the tube body. The outer fins are in a "T" shape and include a vertical portion 21 and a horizontal portion 22. A grid-like outer channel 3 is provided on the outer surface of the outer fins 2. A cavity 4 is formed between axially adjacent outer fins 2, i.e., a cavity 4 with an upper opening is formed by the vertical portions 21 on both sides and the horizontal portion 22 at the top. A gap 5 is provided between adjacent horizontal portions 22. A grid-like groove 6 is recessed on the outer surface of the tube body 1, and the groove 6 is located within the cavity 4; that is, between two axially adjacent outer fins 2. Side channels 7 are recessed on the sides of the vertical portions 21. The outer channels 3, side channels 7, and grooves 6 on the surface induce liquid flow, increase the liquid replenishment rate, thereby reducing the dry-evaporation area under high heat flux density and improving heat exchange efficiency.
[0033] In one embodiment, such as Figures 1-9 As shown, the outer channel 3 includes a first outer channel 31, a second outer channel 32, and a third outer channel 33. The angle between the first outer channel 31 and the axis is 45°±5°; the angle between the second outer channel 32 and the axis is 135°±5°; and the angle between the third outer channel 33 and the axis is 5°-40°. The first outer channel 31, the second outer channel 32, and the third outer channel 33 intersect each other, forming a network of channels that converge at the gap 5, allowing the liquid to be quickly guided to the gap 5 and rapidly fill the cavity 4. The first outer channel 31 and the second outer channel 32 form an intersecting grid-like channel network, and the addition of the third outer channel 33 further increases the area of the channel network, further promoting liquid flow.
[0034] In one embodiment, such as Figures 1-9 As shown, the width of the outer channel is 0.02-0.5 mm, and the depth is 0.02-0.4 mm. In this embodiment, the width of the outer channel is 0.3 mm, and the depth is 0.25 mm. This allows the liquid on the surface to quickly disperse and flow into the cavity 4.
[0035] In one embodiment, such as Figures 1-9 As shown, the trench 6 includes a first trench 61 and a second trench 62. The first trench 61 and the second trench 62 are intersected, and the intersection of the first trench 61 and the second trench 62 forms a vaporization nucleus. The grid-distributed vaporization nucleus ensures uniform distribution and promotes heat exchange.
[0036] In the above embodiments, such as Figures 1-9 As shown, the number of vaporization nuclei is 50-100 per square centimeter.
[0037] In one embodiment, such as Figures 1-9 As shown, the width of the groove 5 is 0.05-0.5 mm and the depth is 0.02-0.2 mm. In this embodiment, the width of the groove 5 is 0.06046-0.1 mm and the depth is 0.05 mm. The narrow groove promotes the capillary effect. By setting the groove 5, a dense network of microchannels is formed. Using the capillary pressure difference, the liquid flows from areas with more liquid to areas with less liquid, improving the uniformity of the surface liquid film and thus greatly improving the heat exchange efficiency.
[0038] In one embodiment, such as Figures 1-9 As shown, the side channel 7 includes a first side channel 71 and a second side channel 72, which intersect to form a mesh structure.
[0039] In one embodiment, such as Figures 1-9 As shown, the width of the side channel is 0.05-0.5 mm and the depth is 0.02-0.2 mm. In this embodiment, the width of the groove 5 is 0.06046-0.1 mm and the depth is 0.05 mm. Similarly, narrow channels are used to create a capillary effect, promoting liquid flow.
[0040] In one embodiment, such as Figures 1-9 As shown, the inner surface of the tube 2 is surrounded by spirally extending inner channels 8, with a depth of 0.1-0.6 mm. The inner channels have axially continuous ribs, with adjacent ribs forming the inner channels 8. The inner channels 8 effectively disrupt the boundary layer of the flow within the tube, thereby enhancing heat transfer. They also increase the heat transfer area within the tube, improving heat transfer performance.
[0041] In one embodiment, such as Figures 1-9 As shown, the width of gap 5 is 0.2-1mm. In this embodiment, the width of gap 5 is set to 0.8mm. This facilitates liquid inflow while trapping small air bubbles to form larger bubbles, thus promoting bubble expulsion.
[0042] Figure 10This paper compares the performance experimental data of the heat exchange tube in this embodiment with those of a high-efficiency evaporative heat exchange tube and a conventional flooded evaporative heat exchange tube. In the experiment, the refrigerant was R134a, the water flow velocity inside the tube was 2.14 m / s, and the heat flux density ranged from 16 kW / m² to 47 kW / m². The experimental results show that the average comprehensive heat transfer coefficient of the heat exchange tube in this embodiment is significantly better than that of the high-efficiency evaporative heat exchange tube and the conventional flooded evaporative heat exchange tube.
[0043] The above are merely preferred embodiments of the present utility model and are not intended to limit the scope of implementation of the present utility model. Any modifications or equivalent substitutions to the present utility model without departing from the spirit and scope thereof should be covered within the protection scope of the claims of the present utility model.
Claims
1. A high-efficiency evaporative heat exchange tube with a mesh-like axial spiral channel on its outer surface, comprising a tube body with an inner cavity and outer fins spirally wrapped around the outer surface of the tube body. Its features are, The outer fin has a T-shaped cross-section, and the outer surface of the outer fin is provided with a grid-like outer channel. A cavity is formed between axially adjacent outer fins, and the outer surface of the tube is recessed with a grid-like groove. The outer fin includes a vertical part and a horizontal part. Side channels are recessed on both sides of the vertical part. A gap is provided between axially adjacent horizontal parts.
2. The high-efficiency evaporative heat exchange tube with a mesh-like axial spiral channel on its outer surface according to claim 1, characterized in that, The outer channel includes a first outer channel, a second outer channel, and a third outer channel. The angle between the first outer channel and the axis is 45°±5°; the angle between the second outer channel and the axis is 135°±5°; and the angle between the third outer channel and the axis is 5°-40°.
3. A high-efficiency evaporative heat exchange tube with a mesh-like axial spiral channel on its outer surface according to claim 1, characterized in that, The width of the outer channel is 0.02-0.5mm and the depth is 0.02-0.4mm.
4. A high-efficiency evaporative heat exchange tube with a mesh-like axial spiral channel on its outer surface according to claim 1, characterized in that, The trench includes a first trench and a second trench, the first trench and the second trench are intersecting, and the intersection point between the first trench and the second trench forms a vaporization nucleus.
5. A high-efficiency evaporative heat exchange tube with a mesh-like axial spiral channel on its outer surface according to claim 4, characterized in that, The number of vaporization cores is 50-100 per square centimeter.
6. A high-efficiency evaporative heat exchange tube with a mesh-like axial spiral channel on its outer surface according to claim 1, characterized in that, The width of the groove is 0.05-0.5 mm and the depth is 0.02-0.2 mm.
7. A high-efficiency evaporative heat exchange tube with a mesh-like axial spiral channel on its outer surface according to claim 1, characterized in that, The side channel includes a first side channel and a second side channel, which intersect to form a mesh structure.
8. A high-efficiency evaporative heat exchange tube with a mesh-like axial spiral channel on its outer surface according to claim 1, characterized in that, The width of the side channel is 0.05-0.5mm and the depth is 0.02-0.2mm.
9. A high-efficiency evaporative heat exchange tube with a mesh-like axial spiral channel on its outer surface according to claim 1, characterized in that, The inner surface of the tube is surrounded by a spirally extending inner channel with a depth of 0.1-0.6 mm.
10. A high-efficiency evaporative heat exchange tube with a mesh-like axial spiral channel on its outer surface according to claim 1, characterized in that, The gap width is 0.2-1mm.