CN107906998A - A kind of high-performance condensing heat-exchanging pipe based on biomimetic features - Google Patents

Abstract

The invention discloses a high-performance condensing heat exchange tube based on a bionic structure, which is a high-performance condensing heat exchange tube based on a bionic structure, and is used for efficiently condensing water vapor or organic vapor and draining condensed liquid in time. The condensing heat exchange tube comprises a heat exchange tube base tube (1) with a hydrophobic microchannel structure, a superhydrophobic substrate (2) arranged on the surface of the heat exchange tube base tube (1), distributed on the superhydrophobic base tube The hydrophobic micro-channel structure (4) on (2) and the needle-like hydrophilic biomimetic structure (3) distributed on the hydrophobic micro-channel structure (4). The heat exchange tube base tube treated by the spray drying technology based on ultrasonic atomization effectively improves the surface properties of the material, reduces the surface energy, and forms more stable bead-like condensation on the surface of the heat exchange tube; the hydrophobic particles distributed on the condensation surface The microchannel can guide the liquid droplets moving to the root of the needle-shaped hydrophilic biomimetic structure in time, so as to ensure the smooth progress of the condensation cycle.

Description

A High Performance Condensation Heat Exchange Tube Based on Bionic Structure

technical field

The invention relates to a high-efficiency condensation heat exchange tube widely used in the fields of energy, electronics, refrigeration, etc., and specifically relates to a high-performance condensation heat exchange tube based on a bionic structure designed to improve condensation heat exchange efficiency.

Background technique

The steam condensation heat transfer process widely exists in energy, chemical industry, refrigeration and other industrial fields. Steam condensation can generate a large amount of latent heat, so the recovery of latent heat is very important for energy saving and emission reduction. In the refrigeration industry, the use of condensers with higher condensation efficiency can reduce the condenser area and save materials. In addition, when there is non-condensable gas in the steam, a layer of gas film will be formed between the liquid film or the liquid droplet and the mixed gas, which will increase the mass transfer resistance between the steam and the gas-liquid interface or the wall of the condenser, and seriously weaken the condensing heat transfer performance. To sum up, improving the condensation efficiency and efficiently recovering the heat in the steam condensation process are of great significance to the development of my country's industry and the promotion of energy conservation and emission reduction.

According to the microstructure and wetting characteristics of the solid surface, vapor condensation can be divided into film condensation and bead condensation. Compared with film condensation, bead condensation is a more efficient heat transfer method, and its condensation heat transfer coefficient is 1-2 orders of magnitude higher than that of film condensation. The realization of bead condensation can greatly reduce the heat transfer area, and obtain great benefits in terms of economy and environment. But in fact, bead condensation is a dynamic cycle process including droplet nucleation, growth, merging, and detachment, which has multi-scale characteristics and is affected by many factors. Bead condensation largely depends on the surface conditions of the heat exchange tubes, and is a difficult and unstable form of condensation in industry.

The cactus uses the super-hydrophilic material of the thorn structure distributed on the surface of the stem to collect water efficiently. Since the tip section radius of the needle-like thorns is smaller than the root section radius, the water droplets continue to pierce the cone under the action of the Laplace pressure difference. root movement. After gathering at the roots, the water droplets are transported along the spinal grooves with a hydrophobic waxy surface and gather other small water droplets to carry them away, thus completing a water collection cycle.

Using surface treatment technology on the surface of heat exchange tubes is one of the main technologies to improve the efficiency of condensation heat exchange. Usually, longitudinal grooves or low ribs are used to increase the heat exchange area, and at the same time, it is easier for the condensate to condense under the action of surface tension. The discharge reduces the thickness of the condensate film, thereby achieving the purpose of strengthening condensation heat transfer. However, the condensation methods achieved by the above methods are all film-like condensation, and the condensate film is attached to the tube wall to form a thermal resistance, so that the gas to be condensed cannot directly contact the tube wall, resulting in a low condensation heat transfer coefficient, which strengthens the condensation heat transfer room for improvement is limited.

Contents of the invention

Technical problem: The technical problem to be solved by the present invention is to provide a high-performance condensation heat exchange tube based on a bionic structure. The thermal coefficient achieves the purpose of high-efficiency heat exchange, and at the same time enhances the stability of the heat exchange structure and improves the promotion value of industrial production.

Technical solutions

Technical solution: In order to achieve the above purpose, a technical solution adopted by a high-performance condensing heat exchange tube based on a bionic structure of the present invention: the condensing heat exchange tube includes a heat exchange tube base tube with a hydrophobic micro-channel structure, which is arranged on A super-hydrophobic base on the surface of the heat exchange tube substrate, a hydrophobic micro-channel structure distributed on the super-hydrophobic base, and a needle-like hydrophilic biomimetic structure distributed on the hydrophobic micro-channel structure.

The tube type of the base tube of the heat exchange tube is a round tube, an oval tube, a rectangular channel, a rounded rectangular channel, a drip tube, a flat tube or a porous flat tube.

The material of the base tube of the heat exchange tube is copper, carbon steel, stainless steel, aluminum or ceramics with nanoporous structure.

The equivalent outer diameter of the base pipe of the heat exchange tube is 2-200 mm, and the equivalent inner diameter is 1-200 mm.

The outer wall of the base pipe of the heat exchange tube has a hydrophobic micro-channel structure, and the width of the hydrophobic micro-channel structure is 0.1-10 mm, and the depth is 0.1-5 mm.

The hydrophobic micro-channel structure connects each needle-shaped hydrophilic biomimetic structure together in a certain distribution manner, and its distribution mode depends on the arrangement of the needle-shaped hydrophilic biomimetic structures and the arrangement of the condensing heat exchange tubes; If the arrangement of the heat exchange tubes is horizontal, the structure of the hydrophobic microchannels should be distributed along the circumference of the base tube of the heat exchange tubes; if the arrangement of the condensation heat exchange tubes is vertical, the structure of the hydrophobic microchannels should be as Distributed along the axial direction of the heat exchange tube base pipe.

The super-hydrophobic substrate has a micro-nano binary surface structure, and the rolling angle is less than 6 degrees.

The needle-like hydrophilic biomimetic structures are arranged randomly or at equal intervals on the superhydrophobic substrate. Among them, the equidistant arrangement is divided into two structures: straight and fork, and the distance between adjacent needle-like hydrophilic biomimetic structures 0.5-40mm.

The angle β between the needle-shaped hydrophilic biomimetic structure and the base tube of the heat exchange tube is 0-90°, and the length is 0.1-30mm.

Beneficial effects: the present invention adopts the above-mentioned technical solution, and has the following advantages compared with the prior art:

1. The present invention adopts a super-hydrophobic substrate with a micro-nano structure, and its surface has the characteristics of small rolling resistance, which is conducive to the rolling of droplets. Under a certain steam flow rate, condensed droplets are easier to fall off from the surface of the heat exchange tube , more conducive to the removal of condensate.

2. When the non-condensable gas exists, the micro-nano structure of the super-hydrophobic base layer captures the non-condensable gas, thereby reducing the contact area between the substrate and the liquid, and reducing the viscosity of the solid surface to the droplet, achieving obvious The purpose of reducing heat transfer resistance.

3. The present invention adopts a needle-like hydrophilic bionic structure, and the hydrophilic material can quickly capture steam molecules and increase the condensation rate. At the same time, the Laplace pressure generated by it shortens the aggregation process of small liquid droplets and continuously moves to the root of the cone . The accumulation of water droplets is accelerated during the movement of small liquid droplets, which greatly promotes the condensation process.

4. The base pipe of the heat exchange tube of the present invention has a hydrophobic micro-channel structure, which can make use of the effect of gravity to make the liquid droplets gathered at the root of the needle-shaped hydrophilic bionic structure slide down along the groove and gather other small liquid droplets, shortening the flow rate of the liquid. The time for the beads to leave the condensation surface ensures the normal operation of the condensation cycle.

Description of drawings

Fig. 1 is a schematic diagram of the surface of a heat exchange tube in which needle-like hydrophilic biomimetic structures are equally spaced on a superhydrophobic substrate in a cross-row manner.

Fig. 2 is a schematic cross-sectional view of a heat exchange tube in which needle-like hydrophilic biomimetic structures are distributed equidistantly on a superhydrophobic substrate in a cross-row manner.

In the figure, there are: heat exchange tube substrate 1, super-hydrophobic substrate 2, needle-shaped hydrophilic bionic structure 3, and hydrophobic micro-channel structure 4.

Detailed ways

Carry out further detailed description below in conjunction with accompanying drawing:

As shown in FIG. 1 , the present invention prepares a superhydrophobic substrate and needle-shaped hydrophilic biomimetic structures distributed on the superhydrophobic substrate on the surface of a heat exchange tube substrate with hydrophobic microchannels. On the surface of the condensing heat exchange tube based on the biomimetic structure, the hydrophilic region and the superhydrophobic region are organically combined, and the needle-like hydrophilic biomimetic structure is distributed on the superhydrophobic substrate at equal intervals in a cross-row manner. The hydrophobic micro-channel structure is reasonably distributed according to the arrangement of the needle-like hydrophilic biomimetic structure and the arrangement of the condenser.

In addition, needle-like hydrophilic biomimetic structures can also be arranged on superhydrophobic substrates in a random, disordered or in-line manner.

In the above arrangement of needle-shaped hydrophilic bionic structures, the angle β between the needle-shaped hydrophilic bionic structures and the heat exchange tube base tube is 0-90°, and the length is 0.1-30mm. The pitch of the structure is 0.5-40mm.

The tube type of the heat exchange tube base tube of the present invention is a round tube, an oval tube, a rectangular channel, a rounded rectangular channel, a drip tube, a flat tube or a porous flat tube, and the material of the heat exchange tube base tube is copper, carbon steel, Stainless steel, aluminum or ceramics with nanoporous structure, the equivalent outer diameter of the heat exchange tube substrate is 2-200mm, and the equivalent inner diameter is 1-200mm. The width of the hydrophobic microchannel structure distributed on the heat exchange tube base pipe is 0.1-10mm, and the depth is 0.1-5mm.

As shown in Figure 2, when needle-like hydrophilic biomimetic structures are distributed on the superhydrophobic substrate at equal intervals in a fork row, viewed from the axial direction, it can be found that the distribution density of needle-like hydrophilic biomimetic structures is high, and the energy To achieve a better condensation effect.

The arrangement of the heat exchange tubes in the figure is horizontal, so the hydrophobic microchannels should be distributed along the circumferential direction of the circular tube as much as possible; if the arrangement of the heat exchange tubes is vertical, the hydrophobic microchannels should be arranged along the The circular tube is distributed axially. Ensure that condensate droplets can be drained smoothly under the action of gravity.

Claims (9)

1. A high-performance condensing heat exchange tube based on a bionic structure, characterized in that the condensing heat exchange tube includes a heat exchange tube base tube (1) with a hydrophobic micro-channel structure, which is arranged on the heat exchange tube base tube ( 1) a superhydrophobic substrate (2) on the surface, a hydrophobic microchannel structure (4) distributed on the superhydrophobic substrate (2) and acicular hydrophilic cells distributed on the hydrophobic microchannel structure (4) Water biomimetic structures (3). 2. The high-performance condensing heat exchange tube based on bionic structure according to claim 1, characterized in that, the tube type of the heat exchange tube base tube (1) is a round tube, an oval tube, a rectangular channel, and a rounded corner Rectangular channels, drip tubes, flat tubes or perforated flat tubes. 3. The high-performance condensing heat exchange tube based on bionic structure according to claim 1 or 2, characterized in that, the material of the base tube (1) of the heat exchange tube is copper, carbon steel, stainless steel, aluminum or nano porous ceramics. 4. The high-performance condensing heat exchange tube based on bionic structure according to claim 3, characterized in that, the equivalent outer diameter of the base tube (1) of the heat exchange tube is 2-200mm, and the equivalent inner diameter is 1-200mm . 5. The high-performance condensing heat exchange tube based on bionic structure according to claim 4, characterized in that, the outer wall of the base tube (1) of the heat exchange tube has a hydrophobic micro-channel structure (4), and the hydrophobic The micro-channel structure (4) has a width of 0.1-10mm and a depth of 0.1-5mm. 6. The high-performance condensing heat exchange tube based on bionic structure according to claim 5, characterized in that, the hydrophobic micro-channel structure (4) divides each needle-shaped hydrophilic bionic structure (3) in a certain distribution manner connected together, its distribution depends on the arrangement of the needle-like hydrophilic biomimetic structure (3) and the arrangement of the condensing heat exchange tubes; if the condensing heat exchange tubes are placed horizontally, the hydrophobic microchannel structure ( 4) It should be distributed along the circumferential direction of the heat exchange tube base tube (1) as much as possible; if the condensing heat exchange tube is placed vertically, the hydrophobic microchannel structure (4) should try to be along the heat exchange tube base tube ( 1) Axial distribution. 7. The high-performance condensing heat exchange tube based on bionic structure according to claim 1, characterized in that, the superhydrophobic substrate (2) has a micro-nano binary surface structure, and the rolling angle is less than 6 degrees. 8. The high-performance condensing heat exchange tube based on the bionic structure according to claim 6, characterized in that, the needle-shaped hydrophilic bionic structure (3) is arranged on the superhydrophobic substrate (2) randomly or at equal intervals ), wherein the equidistant arrangement is divided into two structures: straight row and fork row, and the distance between adjacent needle-like hydrophilic biomimetic structures (3) is 0.5-40mm. 9. The high-performance condensing heat exchange tube based on bionic structure according to claim 8, characterized in that, the included angle β of the tube axis between the needle-shaped hydrophilic bionic structure (3) and the base tube (1) of the heat exchange tube 0-90°, length 0.1-30mm.