CN108020110A - There is the heat exchanger tube for managing outer microflute group for function of mechanical steam recompression system - Google Patents

Abstract

The invention discloses a heat exchange tube with micro-grooves outside the tube used in a mechanical vapor recompression system, which is used to improve the evaporation and boiling heat exchange capacity outside the heat exchange tube of the mechanical vapor recompression system. Many microgroove groups arranged according to certain rules are processed by mechanical processing or other processing methods on the outside of the hot heat exchange tube. The micro-grooves outside the tube play two roles: one is liquid distribution. The liquid is sprayed outside the heat exchange tube by spraying or dripping. There are small micro-grooves on the outer wall of the tube. Depending on the surface tension of the liquid, the liquid can The relatively uniform expansion increases the effective heat transfer area; the second is to enhance the heat transfer capacity. Studies have shown that the combination of high-intensity evaporation and nucleate boiling in the micro-groove complex phase change heat mechanism can greatly improve the heat transfer capacity.

Description

Heat Exchange Tubes with Outer-Tube Microgrooves for Mechanical Vapor Recompression Systems

technical field

The invention relates to a heat exchange tube with grooves outside the tube, in particular to a micro-groove group heat exchange tube outside the tube used in a mechanical vapor recompression system.

Background technique

Evaporation is a process of high energy consumption. Since the secondary steam in the traditional evaporator is condensed and discharged directly, the whole evaporation process needs to consume more fresh steam, circulating water and electric energy. Especially for materials with large processing capacity and low concentration, steam The consumption is quite huge. Compared with the traditional multi-effect evaporation method, the mechanical vapor recompression system does not require additional steam after it is stabilized. By inputting a small amount of adiabatic compression work, the heat grade of the steam is improved, thereby effectively utilizing a large amount of heat of the low-pressure steam. Evaporating 1kg of water in the same way, the energy consumption of the mechanical vapor recompression system is 37.4-57.4kJ, and the energy consumption of the multi-effect evaporation technology is 465.3-581.7kJ.

The mechanical vapor recompression system is especially suitable for occasions that require a large amount of steam, such as food and drug concentration, purification, and seawater desalination. Its main features: ① Negative pressure and low temperature evaporation (50-90 ° C), preventing high-temperature denaturation of materials (proteins, drug components) ; ②The emission of waste heat steam is almost zero, the unit energy consumption is low, and the evaporation is gentle; ③It only needs a small amount of steam or electric energy to start, and no steam is needed after startup, and the energy saving effect is good; ④There are fewer supporting equipment and a small footprint , simple structure and stable operation.

There are many and complex factors affecting the mechanical vapor recompression system. Scholars at home and abroad have conducted a lot of research on this, mainly investigating factors such as spray density, heat flux density, evaporation temperature, heat transfer temperature difference, heat transfer tube material and its geometry. Impact.

Contents of the invention

(1) Technical problems to be solved

In order to improve the uniformity of the distribution of the liquid film outside the heat exchange tube of the mechanical vapor recompression system and the ability to enhance evaporation and boiling heat transfer outside the tube, the present invention provides a micro-groove group outside the tube for the mechanical vapor recompression system heat exchange tubes.

(2) Technical solutions

In order to solve the problems of the technologies described above, the present invention is achieved through the following technical solutions:

A heat exchange tube for a mechanical vapor recompression system with a group of microgrooves outside the tube. The outer surface of the heat exchange tube is formed with a group of microgrooves arranged regularly, and heat exchange is enhanced on a micro scale outside the heat exchange tube.

In the above solution, the microgroove group includes an axial groove group and a radial groove group.

In the above solution, the axial groove group includes a plurality of axial grooves, and the radial groove group includes a plurality of radial grooves, and the axial grooves and radial grooves are arranged in a crossed manner to form a "well" shape distributed.

In the above solution, the included angle between the axial groove and the axis of the heat exchange tube is less than 90°.

In the above solution, the included angle between the radial groove and the axis of the heat exchange tube is greater than 0°. Preferably, the included angle between the radial groove and the axis of the heat exchange tube is 90°.

In the above solution, the included angle matches the viscosity, concentration and surface tension of the liquid to be evaporated.

In the above solution, the width of the micro-channels of the micro-groove group is in the range of 0.05-2 mm, the depth is in the range of 0.05-2 mm, and the distance between adjacent micro-channels is in the range of 0.05-5 mm.

In the above scheme, the inside of the heat exchange tube is passed through high-temperature steam, and the outside is sprayed with the solution to be evaporated.

(3) Beneficial effects

In the present invention, micro-grooves are provided outside the heat-exchanging tubes to enhance heat exchange on a microscale. In a mechanical vapor recompression system, micro-grooves can not only enhance heat exchange, but also distribute liquid evenly. The micro-groove group channels outside the heat exchange tube rely on capillary force to evenly spread the liquid droplets or liquid pools falling outside the tube to achieve the purpose of increasing the effective heat exchange area. At the same time, the micro-scale evaporation and boiling complex phase transfer heat of the working medium in the capillary micro-groove has extremely high heat transfer intensity. Therefore, the application of the micro-groove group heat exchange tube in the mechanical vapor recompression system can significantly improve the heat transfer efficiency of the heat exchange tube. heat transfer efficiency.

Description of drawings

Fig. 1 is a schematic diagram of a mechanical vapor recompression system according to an embodiment of the present invention.

Fig. 2 is a schematic diagram of a heat exchange tube in which the included angle between the axial channel and the axis of the heat exchange tube is 0° according to an embodiment of the present invention.

Fig. 3 is a schematic diagram of the heat exchange tube in which the angle between the axial channel and the axis of the heat exchange tube is 30° according to the embodiment of the present invention.

Detailed ways

The invention provides a heat exchange tube with microgroove groups outside the tube used in a mechanical vapor recompression system. The microgroove groups arranged regularly are formed on the outer surface of the heat exchange tube, and micro-scale enhanced heat exchange is performed outside the tube. . The microgroove group on the outer surface of the heat exchange tube includes an axial groove group and a radial groove group, the axial groove group includes a plurality of axial grooves, the radial groove group includes a plurality of radial grooves, the axial groove and the radial groove group Arranged across the channels to form a "well" shape distribution.

The material of the heat exchange tubes can be steel tubes, copper tubes, aluminum tubes, cast iron tubes and other tubes with certain thermal conductivity.

The shape of the microgrooves can be rectangular microgrooves, triangular microgrooves, trapezoidal microgrooves, semicircular microgrooves and the like.

The included angle between the axial channel and the axis of the heat exchange tube is greater than or equal to 0° and less than 90°. The included angle between the axial channel and the axis of the heat exchange tube refers to the axis of the heat exchange tube and the axis The included angle between the projections to the plane is determined according to the viscosity, concentration and surface tension properties of the liquid to be evaporated. In principle, the smaller the viscosity and concentration of the liquid to be evaporated, the greater the surface tension of the liquid. The longer the time spent outside the tube, the smaller the included angle.

The angle between the radial groove and the axis of the heat exchange tube is greater than 0° and less than or equal to 90°. The angle between the radial groove and the axis of the heat exchange tube refers to the axis of the heat exchange tube and the radial groove of the radial groove group on the axis The included angle between the projections to the plane, preferably, the included angle between the radial groove and the axis of the heat exchange tube is 90°.

The microgroove group can be processed by milling, wire electric discharge cutting, electrolytic etching, high-energy beam photoetching, etc. The more mature process is milling machining.

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

As shown in Figure 1, it is a schematic diagram of a mechanical vapor recompression system. The heat exchange tube of the embodiment of the present invention can be used in this system. The mechanical vapor recompression system includes: a compressor 1, an evaporation chamber 2, a liquid distributor ₃ , a Heat pipe 4 , circulation pipe pump 5 , plate heat exchanger 6 , liquid storage tank 7 , first circulation pump 8 and second circulation pump 9 .

The feed liquid is sent to the top of the evaporation chamber 2 through the circulation tube pump 5, and the heat exchange tube 4 with the micro-groove group outside the tube of the present invention is arranged in the evaporation chamber 2, and the feed liquid is distributed by the liquid distributor 3 in a gravity and negative pressure environment. It flows from top to bottom in the form of a film, flows through the outer surface of the heat exchange tube, and uses the micro-groove group to exchange heat with the steam in the heat exchange tube. The steam evaporated from the feed liquid is sucked by the compressor 1 and returned to the evaporation chamber after treatment. 2 circulation is used as steam for evaporating feed liquid. If the concentration of the concentrated solution reaches the standard, it will be directly collected into the liquid storage tank 7, otherwise the solution will continue to be sent from the bottom to the liquid distributor 3 through the circulation pump 8, so as to achieve the purpose of concentration of the solution and finally complete the discharge of the concentrated solution.

Example 1

As shown in Figure 2, the angle of the axial channel 42 on the outer surface of the heat exchange tube 41 of the embodiment of the present invention is 0°, the angle of the radial channel is 90°, the width of the axial channel 42 is 0.4 mm, and the depth is 0.9 mm. mm, a plurality of axial channels 42 are arranged in parallel, and the distance between two axial channels 42 is 0.4 mm. The capillary micro-grooves 42 in this range have capillary force effects on absolute ethanol or distilled water. The micro-channel "well" structure can evenly spread the liquid film under the joint action of capillary force and gravity, and increase the time that the liquid film stays on the heat exchange tube. This embodiment is more suitable for solutions with higher concentration and viscosity or more impurities.

Example 2

As shown in Figure 3, the angle of the axial channel 44 on the outer surface of the heat exchange tube 43 of this embodiment is 30°, the angle of the radial channel is 90°, the width of the axial channel 44 is 0.4mm, and the depth is 0.9mm , a plurality of axial grooves 44 are arranged in parallel, and the distance between two axial grooves 44 is 0.4 mm. The capillary micro grooves 44 in this range have capillary force effects on absolute ethanol or distilled water. This embodiment is more suitable for solutions with less concentration and viscosity or less impurities. The helical microgroove group can increase the residence time of the liquid in the heat exchange tube, thereby increasing the heat exchange time and improving the heat exchange efficiency.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention, and are not intended to limit the present invention. Within the spirit and principles of the present invention, any modifications, equivalent replacements, improvements, etc., shall be included in the protection scope of the present invention.

Claims (9)

1. there is the heat exchanger tube for managing outer microflute group for function of mechanical steam recompression system, it is characterised in that the heat exchanger tube Microflute group of the outer surface formed with regular array, carries out micro-scale enhanced heat exchange outside heat exchanger tube.

2. heat exchanger tube as claimed in claim 1, it is characterised in that the microflute group includes axial groove group and radial slot group.

3. heat exchanger tube as claimed in claim 2, it is characterised in that the axial groove group includes a plurality of axial slot, the footpath Include a plurality of radial channels, axial slot and radial channels cross arrangement to groove group, form the distribution of " well " font.

4. heat exchanger tube as claimed in claim 3, it is characterised in that the axial slot and the angle of heat exchanger tube axis are less than 90°。

5. heat exchanger tube as claimed in claim 3, it is characterised in that the radial channels and the angle of heat exchanger tube axis are more than 0°。

6. heat exchanger tube as claimed in claim 5, it is characterised in that the angle of the radial channels and heat exchanger tube axis is 90 °.

7. heat exchanger tube as described in claim 4 or 5, it is characterised in that the viscosity of the angle and liquid to be evaporated, concentration and Surface tension matches.

8. heat exchanger tube as claimed in claim 1, it is characterised in that the width of the micro-channel of the microflute group is in 0.05~2mm In the range of, depth is in the range of 0.05~2mm, and the spacing of adjacent micro-channel is in the range of 0.05~5mm.

9. heat exchanger tube as claimed in claim 1, it is characterised in that logical high-temperature steam inside the heat exchanger tube, outside spray are treated Evaporate solution.