阅读说明：本技术 一种强化珠状冷凝换热的slips定向输运传热管及其制备方法 (SLIPS (slip induced polarization) directional transport heat transfer pipe for enhancing beaded condensation heat exchange and preparation method thereof ) 是由 吕凤勇 林思帆 聂寒璐 程道来 赵芳 董智广 解董军 于 2021-07-22 设计创作，主要内容包括：本发明公开了一种强化珠状冷凝换热的SLIPS定向输运传热管的制备方法,采用机械加工法在传热管外壁面加工环形螺纹结构,该环形螺纹结构增加了冷凝换热面积,有利于液滴冷凝,螺纹侧面、顶端和螺纹沟槽表面具有纳米结构,植入润滑液之后形成稳定的SLIPS表面,由于润滑液的表面能非常低且与冷凝液滴互不相溶,所以冷凝液滴会漂浮在SLIPS表面上,降低SLIPS表面上液滴的迟滞角,进一步减小冷凝液滴与SLIPS表面之间的粘滞力,促使微液滴在螺纹侧壁和沟槽中发生聚集合并与迁移运动,液滴从核化形成到脱离定向输运槽道表面的时间周期变短,加速冷凝核化过程,削弱换热热阻,显著增强冷凝换热能力。(The invention discloses a preparation method of a SLIPS directional transport heat transfer pipe for strengthening bead-shaped condensation heat exchange, which adopts a mechanical processing method to process an annular thread structure on the outer wall surface of the heat transfer pipe, the annular thread structure increases the condensation heat exchange area, is beneficial to the condensation of liquid drops, the thread side surface, the thread top end and the thread groove surface are provided with nano structures, a stable SLIPS surface is formed after the lubrication liquid is implanted, because the surface energy of the lubrication liquid is very low and is mutually incompatible with condensate liquid drops, therefore, condensed liquid drops can float on the SLIPS surface, the lag angle of the liquid drops on the SLIPS surface is reduced, the viscous force between the condensed liquid drops and the SLIPS surface is further reduced, micro-liquid drops are promoted to be gathered, merged and moved in the thread side wall and the groove, the time period from nucleation formation of the liquid drops to separation from the surface of the directional transport channel is shortened, the condensation nucleation process is accelerated, the heat exchange resistance is weakened, and the condensation heat exchange capacity is remarkably enhanced.)

1. A preparation method of a SLIPS directional transport heat transfer pipe for reinforcing bead-shaped condensation heat exchange is characterized by comprising the following steps:

s1: providing a heat transfer pipe, and processing an annular thread structure on the outer wall of the heat transfer pipe;

s2: heat transfer pipe pretreatment, in which the heat transfer pipe treated in step S1 is subjected to cleaning treatment to remove organic matter and oxides on the surface of the heat transfer pipe;

s3: super-hydrophilic treatment, preparing NaOH and (NH)₄)₂S₂O₈The mixed alkaline solution of (1) is to place the heat transfer pipe processed in the step (S2) in the mixed alkaline solution for constant temperature oxidation, then to clean the heat transfer pipe with distilled water, and then to dry the heat transfer pipe at constant temperature, so as to obtain the super-hydrophilic heat transfer pipe with the nano structure;

s4: performing super-hydrophobic treatment, namely preparing a fluorosilane solution, soaking the heat transfer pipe treated in the step S3 in the fluorosilane solution, and then baking the heat transfer pipe at constant temperature to obtain a super-hydrophobic heat transfer pipe;

s5: preparing a SLIPS surface, implanting lubricating liquid into the outer surface of the super-hydrophobic heat transfer pipe, erecting the heat transfer pipe after the outer surface is completely soaked, so that redundant lubricating liquid flows away, and finally obtaining the directional transport thread groove heat transfer pipe with the SLIPS surface.

2. The method of claim 1 wherein the molar mass concentration of NaOH and (NH) in the mixed alkaline solution of step S3 is higher than that of NaOH₄)₂S₂O₈The molar mass concentration ratio of (a) to (b) is 25: 1.

3. the method for preparing a SLIPS oriented transport heat transfer tube for enhancing beaded condensation heat exchange according to claim 1, wherein the concentration of tridecafluorooctyltriethoxysilane or heptadecafluoroquinyltriethoxysilane in the fluorosilane solution in the step S4 is 0.5-1.5 wt%.

4. The method for preparing the SLIPS oriented transport heat transfer tube for enhancing the bead-shaped condensation heat exchange according to claim 1, wherein the constant-temperature oxidation temperature in the step S3 is 65-75 ℃, the constant-temperature oxidation time is 30-40 min, the constant-temperature drying temperature is 40-50 ℃, and the constant-temperature drying time is 55-65 min.

5. The method for preparing the SLIPS oriented transport heat transfer pipe for enhancing the bead-shaped condensation heat exchange according to claim 1, wherein the soaking time of the heat transfer pipe in the fluorosilane solution in the step S4 is not less than 12h, the baking temperature is 110-130 ℃, and the baking time is 55-65 min.

6. The method for preparing a SLIPS oriented transport heat transfer tube with enhanced bead condensation heat exchange function according to claim 1, wherein the lubricating liquid is perfluoropolyether lubricating oil or silicone oil or ionic liquid with low surface energy.

7. The SLIPS directional transportation heat transfer pipe is characterized in that an annular thread structure is formed on the outer wall of the heat transfer pipe, a directional transportation groove is formed between adjacent threads, and the side face, the top and the bottom of the directional transportation groove are SLIPS surfaces.

8. The enhanced beaded heat condensing and exchanging SLIPS oriented transport heat transfer tube of claim 7, wherein the heat transfer tube is made of copper or a copper alloy.

9. The enhanced beaded condensate heat exchange SLIPS s directional transport heat transfer tube of claim 7, wherein the thread cross-section is triangular or rectangular or trapezoidal.

10. The enhanced beaded condensate heat exchange SLIPS s directional transport heat transfer tube of claim 7, wherein the helical angle of the annular thread structure is 0 ° to 90 °.

Technical Field

The invention belongs to the field of heat transfer pipe design, and particularly relates to a SLIPS directional transport heat transfer pipe for strengthening beaded condensation heat exchange and a preparation method thereof.

Background

The condensation heat exchange is widely applied to the fields of refrigeration, electronic equipment cooling, chemical industry, nuclear industry and the like. The heat is exchanged between the two media through the heat transfer pipe, the cold energy is transferred to the pipe wall when the working medium in the pipe flows through the heat transfer pipe, and the phase change latent heat released by the condensation of the steam on the pipe wall is absorbed, so that the purpose of heat exchange is achieved. The surface of a common heat transfer pipe is easy to form film-shaped condensation, the additional thermal resistance of a condensed liquid film seriously weakens the condensation heat exchange performance of the surface, and the bead condensation forms independent condensed liquid drops, so that the condensation thermal resistance is obviously reduced, and researches show that the bead condensation is higher than the film-shaped condensation heat exchange performance by one order of magnitude. Therefore, maintaining a continuous and stable bead-like condensation condition is particularly important to enhance the condensate phase transition heat transfer performance of the heat transfer tube.

As the surface of the conventional metal heat transfer pipe is easy to form film-shaped condensation, the condensed liquid film cannot be drained in time, the phase change heat exchange resistance of condensation is increased, and the further enhancement of the condensation heat exchange performance is limited. If the beaded condensation is realized on the surface, the condensed micro-droplets are promoted to be gathered and merged, and then the directional transportation is spontaneously formed, so that the droplets are favorably and quickly separated from the wall surface and the wall surface is cleaned, an enough condensation heat exchange area is provided for secondary condensation nucleation, and finally, the condensation phase-change heat exchange capacity of the surface is remarkably improved, so that the thread groove structure with SLIPS directional transportation is formed on the outer surface of the heat transfer pipe for enhancing and maintaining the high-efficiency condensation heat exchange capacity, and the method has important significance.

Disclosure of Invention

The invention aims to provide a SLIPS directional transport heat transfer pipe for strengthening bead-shaped condensation heat exchange and a preparation method thereof, which not only increase the condensation heat exchange area of the heat transfer pipe, but also can continuously and efficiently promote condensation nucleation of steam, spontaneous gathering and merging of micro liquid drops, directional transport and cleaning of the liquid drops, reduce the thermal resistance of condensation heat exchange and obviously strengthen the condensation heat exchange capability of the heat transfer pipe.

In order to solve the problems, the technical scheme of the invention is as follows:

a preparation method of a SLIPS directional transport heat transfer pipe for reinforcing bead-shaped condensation heat exchange comprises the following steps:

s1: providing a heat transfer pipe, and processing an annular thread structure on the outer wall of the heat transfer pipe;

s2: heat transfer pipe pretreatment, in which the heat transfer pipe treated in step S1 is subjected to cleaning treatment to remove organic matter and oxides on the surface of the heat transfer pipe;

s3: super-hydrophilic treatment, preparing NaOH and (NH)₄)₂S₂O₈The mixed alkaline solution of (1) is to place the heat transfer pipe processed in the step (S2) in the mixed alkaline solution for constant temperature oxidation, then to clean the heat transfer pipe with distilled water, and then to dry the heat transfer pipe at constant temperature, so as to obtain the super-hydrophilic heat transfer pipe with the nano structure;

s4: performing super-hydrophobic treatment, namely preparing a fluorosilane solution, soaking the heat transfer pipe treated in the step S3 in the fluorosilane solution, and then baking the heat transfer pipe at constant temperature to obtain a super-hydrophobic heat transfer pipe;

s5: preparing a SLIPS surface, implanting lubricating liquid into the outer surface of the super-hydrophobic heat transfer pipe, erecting the heat transfer pipe after the outer surface is completely soaked, so that redundant lubricating liquid flows away, and finally obtaining the directional transport thread groove heat transfer pipe with the SLIPS surface.

Preferably, in the mixed alkaline solution in step S3, the molar mass concentration of NaOH is equal to (NH)₄)₂S₂O₈The molar mass concentration ratio of (a) to (b) is 25: 1.

preferably, the concentration of tridecafluorooctyltriethoxysilane or heptadecafluoroquinyltriethoxysilane in the fluorosilane solution in step S4 is 0.5-1.5 wt%.

Preferably, the constant-temperature oxidation temperature in the step S3 is 65-75 ℃, the constant-temperature oxidation time is 30-40 min, the constant-temperature drying temperature is 40-50 ℃, and the constant-temperature drying time is 55-65 min.

Preferably, the soaking time of the heat transfer pipe in the fluorosilane solution in the step S4 is not less than 12 hours, the baking temperature is 110-130 ℃, and the baking time is 55-65 min.

Preferably, the lubricating liquid is a perfluoropolyether lubricating oil or silicone oil or ionic liquid having a low surface energy.

Based on the same inventive concept, the invention also provides a SLIPS directional transportation heat transfer pipe for strengthening bead-shaped condensation heat exchange, wherein the outer wall of the heat transfer pipe is provided with an annular thread structure, a directional transportation groove is formed between adjacent threads, and the side surface, the top and the bottom of the directional transportation groove are SLIPS surfaces.

Preferably, the heat transfer pipe is made of copper or copper alloy.

Preferably, the thread cross-section is triangular or rectangular or trapezoidal.

Preferably, the helix angle of the annular thread structure is 0 to 90 °.

Due to the adoption of the technical scheme, compared with the prior art, the invention has the following advantages and positive effects:

1) compared with the conventional heat transfer pipe, the heat transfer pipe adopts a mechanical processing method to process the annular thread structure on the outer surface of the pipe wall, and the annular thread structure increases the condensation heat exchange area and is beneficial to liquid drop condensation; the thread side face, the top end and the thread groove surface are provided with the nano structures, a stable SLIPS surface is formed after lubricating oil is implanted, and as the surface energy of the lubricating oil is very low and is mutually immiscible with condensate droplets, the condensate droplets can float on the SLIPS surface, the hysteresis angle of the droplets on the SLIPS surface is reduced, the viscous force between the condensate droplets and the SLIPS surface is further reduced, and micro-droplets are promoted to move in the thread side wall and the groove.

2) Compared with a conventional heat transfer pipe, the directional conveying threaded groove heat transfer pipe provided by the invention has the advantages that the annular threaded structure not only increases the heat exchange area, but also a directional conveying channel which is beneficial to separation of condensed liquid drops is formed between adjacent annular threads, micro liquid drops formed on the SLIPS surface of the side surface of the thread can move and gather in the directional conveying threaded groove to form larger liquid drops, the directional movement is carried out along the threaded groove and the small liquid drops in the groove are cleaned, the condensation area is provided for secondary condensation nucleation, the time period from nucleation of the liquid drops to separation of the surface of the directional conveying channel is shortened, the condensation nucleation process is accelerated, the heat exchange resistance is weakened, and the condensation heat exchange capacity is obviously enhanced. Therefore, the SLIPS directional conveying threaded groove heat transfer pipe has wide application prospect.

Drawings

Fig. 1 is a flow chart of a method for manufacturing a SLIPS directional transport heat transfer tube with enhanced beaded condensation heat exchange according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a SLIPS directional transport heat transfer pipe for enhancing beaded condensation heat exchange according to an embodiment of the present invention;

FIG. 3 is an SEM image of a SLIPS oriented transport heat transfer tube for enhanced beaded heat exchange condensation provided by an embodiment of the present invention;

fig. 4 is a contact angle of a SLIPS surface of a SLIPS-oriented transport heat transfer tube for enhancing beaded condensation heat exchange according to an embodiment of the present invention;

fig. 5a to 5c are diagrams of processes of microscopic condensate droplet formation, polymerization, detachment and droplet reformation on a slip directional transport heat transfer tube for enhancing beaded condensation heat exchange according to an embodiment of the present invention.

Description of reference numerals:

1: a heat transfer tube; 2: an annular thread structure; 3: a directional transport trench; S1-S5: and (5) carrying out the following steps.

Detailed Description

The present invention provides a SLIPS directional transport heat transfer tube with enhanced beaded condensation heat exchange and a method for manufacturing the same, which will be described in further detail with reference to the accompanying drawings and specific examples. Advantages and features of the present invention will become apparent from the following description and from the claims.

Example 1

Referring to fig. 1, this embodiment provides a method for preparing a SLIPS directional transport heat transfer tube with enhanced bead condensation heat exchange, which includes the following steps:

s1: providing a heat transfer pipe, and processing an annular thread structure on the outer wall of the heat transfer pipe;

specifically, a heat transfer pipe is provided, the material of the heat transfer pipe is copper or copper alloy, the pipe diameter of the heat transfer pipe can be any size, and annular thread structures with various thread pitches, heights and cross-sectional shapes are processed on the outer wall surface of the heat transfer pipe in a thread tapping mode, as shown in fig. 2, in the embodiment, the outer diameter of the heat transfer pipe is 8mm, a continuous annular thread rib with a thread pitch of 1.25mm and a thread angle of 60 degrees is processed on the outer wall surface of the heat transfer pipe, wherein the height of the thread rib is 0.812mm, the thickness of the rib root is 1.042mm, the thickness of the rib top is 0.156mm, and the width of the groove at the root is 0.208 mm;

s2: heat transfer pipe pretreatment, in which the heat transfer pipe treated in step S1 is subjected to cleaning treatment to remove organic matter and oxides on the surface of the heat transfer pipe;

the method comprises the following steps of firstly, ultrasonically cleaning a heat transfer pipe by acetone and ethanol for 10-15 min, then cleaning by distilled water, immersing in a hydrochloric acid solution with the concentration of 5 wt% for 10-20 min, finally cleaning by distilled water and rapidly drying by nitrogen, thereby removing impurities such as organic matters, oxides and the like on the surface of the heat transfer pipe and obtaining a clean heat transfer pipe;

s3: super-hydrophilic treatment, preparing NaOH and (NH)₄)₂S₂O₈Preferably, the molar mass concentration of NaOH with (NH)₄)₂S₂O₈The molar mass concentration ratio of (a) to (b) is 25: placing the heat transfer pipe treated in the step S2 in a mixed alkaline solution for constant-temperature oxidation, then cleaning the heat transfer pipe with distilled water, and then drying the heat transfer pipe at constant temperature to obtain the super-hydrophilic heat transfer pipe with the nano structure, wherein preferably, the constant-temperature oxidation temperature is 65-75 ℃, the constant-temperature oxidation time is 30-40 min, the constant-temperature drying temperature is 40-50 ℃, and the constant-temperature drying time is 55-65 min;

specifically, first, NaOH and (NH) are prepared₄)₂S₂O₈The mixed alkaline solution of (1), wherein NaOH and (NH)₄)₂S₂O₈Respectively at concentrations of 2.5mol/L and 0.1mol/L, sealing both ends of the heat transfer tube pretreated in step S2, placing the heat transfer tube into a glass test tube, and injecting prepared NaOH and (NH)₄)₂S₂O₈The mixed alkaline solution is oxidized for 30-40 min at a constant temperature of 70 ℃, then washed by distilled water, and dried for 60min at a constant temperature of 40-50 ℃ again, so that a super-hydrophilic CuO film with a sheet-shaped nano structure is formed on the outer surface of the heat transfer pipe, as shown in figure 3;

s4: performing super-hydrophobic treatment, preparing a fluorosilane solution, wherein the solute in the solution is preferably tridecafluorooctyl triethoxysilane or heptadecafluoroquinyl triethoxysilane, the concentration of the tridecafluorooctyl triethoxysilane or the heptadecafluoroquinyl triethoxysilane in the fluorosilane solution is 0.5-1.5 wt%, soaking the heat transfer pipe treated in the step S3 in the fluorosilane solution, and then baking the heat transfer pipe at constant temperature to obtain the super-hydrophobic heat transfer pipe, wherein preferably, the soaking time of the heat transfer pipe in the fluorosilane solution is not less than 12h, the baking temperature is 110-130 ℃, and the baking time is 55-65 min;

specifically, firstly, preparing a fluorosilane solution, injecting heptadecafluoroquinyltriethoxysilane into absolute ethyl alcohol, stirring for 5-8 hours by using a magnetic stirrer to obtain a fluorosilane solution with the concentration of 1.0 wt%, immersing the annular threaded heat transfer pipe with the nano structure, which is treated in the step S3, into the fluorosilane solution, soaking at room temperature for at least 12 hours, and then baking at 120 ℃ for 60 minutes at constant temperature to obtain a super-hydrophobic heat transfer pipe;

s5: preparing a SLIPS surface, implanting lubricating liquid into the outer surface of a super-hydrophobic heat transfer pipe, erecting the heat transfer pipe after the outer surface is completely soaked, so that redundant lubricating liquid flows off, and finally obtaining the directional transport thread groove heat transfer pipe with a liquid-containing smooth surface (SLIPS), wherein the lubricating oil is preferably perfluoropolyether lubricating oil or silicone oil or ionic liquid or other lubricating oil with low surface energy;

specifically, the perfluoropolyether lubricating oil is implanted into the outer surface of the super-hydrophobic heat transfer pipe processed in the step S4, because the perfluoropolyether lubricating oil and the super-hydrophobic surface have similar intermiscibility, the lubricating oil can rapidly infiltrate the super-hydrophobic heat transfer pipe, the nano-structure capillary action can fix the lubricating oil inside the structure, and the redundant lubricating oil can flow off from the surface of the heat transfer pipe in a vertical heat transfer pipe mode, and finally the directional transportation thread groove heat transfer pipe with the SLIPS surface is obtained.

Referring to fig. 4, the contact angle of the SLIPS heat transfer pipe obtained by the method is 107 ° ± 0.4 °, and fig. 5a to 5c show the processes of vapor condensation nucleation formation, droplet aggregation and merging, migration movement, in-groove droplet sweeping and droplet re-nucleation formation on the SLIPS directional transportation threaded groove pipe, and the processes further enhance the bead condensation heat exchange performance.

Compared with the conventional heat transfer pipe, the annular thread structure is processed on the outer surface of the pipe wall by adopting a mechanical processing method, and the annular thread structure increases the condensation heat exchange area and is beneficial to liquid drop condensation; the thread side, the top end and the thread groove surface are provided with nano structures, a stable SLIPS surface is formed after lubricating oil is implanted, as the surface energy of the lubricating oil is very low and is mutually incompatible with condensate droplets, condensate droplets can float on the SLIPS surface, the lag angle of the droplets on the SLIPS surface is reduced, the viscous force between the condensate droplets and the SLIPS surface is further reduced, micro droplets are promoted to generate migration motion in the thread side wall and the groove, meanwhile, the annular thread structure not only increases the heat exchange area, but also a directional transport channel beneficial to separation of the condensate droplets is formed between adjacent annular threads, the micro droplets formed on the thread side SLIPS surface can generate migration motion and converge in the directionally transported thread groove to form larger droplets, the directional motion is generated along the thread groove and the small droplets in the groove are cleaned, and a condensation area is provided for recondensing and coring, the time period from the nucleation of the liquid drops to the separation of the liquid drops from the surface of the directional conveying channel is shortened, the condensation nucleation process is accelerated, the heat exchange resistance is weakened, and the condensation heat exchange capacity is obviously enhanced.

Example two

Based on the same inventive concept, the present embodiment provides a SLIPS directional transportation heat transfer pipe for enhancing beaded condensation heat exchange, and as shown in fig. 2, an annular thread structure 2 is formed on an outer wall of a heat transfer pipe 1, a directional transportation groove 3 is formed between adjacent threads, and side surfaces, a top portion and a bottom portion of the directional transportation groove are all surfaces of the SLIPS.

In a preferred embodiment of the present invention, the heat transfer pipe is made of copper or a copper alloy, the cross section of the thread is triangular, rectangular or trapezoidal, and the helix angle of the annular thread structure is 0 ° to 90 °.

The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, it is still within the scope of the present invention if they fall within the scope of the claims of the present invention and their equivalents.