CN217636944U - Reinforced heat transfer pipe - Google Patents
Reinforced heat transfer pipe Download PDFInfo
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- CN217636944U CN217636944U CN202123187350.8U CN202123187350U CN217636944U CN 217636944 U CN217636944 U CN 217636944U CN 202123187350 U CN202123187350 U CN 202123187350U CN 217636944 U CN217636944 U CN 217636944U
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Abstract
The utility model particularly relates to a strengthen heat-transfer pipe, including the heat-transfer pipe, the heat-transfer pipe surface is equipped with the micro-structure. The utility model provides a reinforce heat-transfer pipe through the microstructural on present smooth heat-transfer pipe surface, improves the boiling heat transfer capacity on heat-transfer pipe surface.
Description
Technical Field
The utility model relates to an strengthen heat transfer technical field, especially relate to an strengthen heat-transfer pipe.
Background
With the ever increasing power and volume of heat exchange devices and the limitation of the overall space size, compact arrangement is becoming the main direction of heat exchange device development. However, since the conventional heat exchanger is influenced by design ideas, concepts and the existing manufacturing process for a long time, most of the conventional heat exchangers adopt smooth heat transfer surfaces which are simple in structure and convenient to manufacture, so that the heat exchange effect is not ideal although the convenience in manufacturing is ensured, and the heat transfer area is designed according to the calculated value plus 20% of allowance, so that the design method not only causes the increase of equipment cost, but also causes the unsatisfactory heat exchange effect in actual production because the heat exchange capacity is not synchronously increased along with the increase of the heat exchange area.
Therefore, the key of heat exchange equipment miniaturization is to change the traditional heat transfer design concept, apply new technology and process, adopt certain heat transfer enhancement technology on the premise of guaranteeing the operation maintenance and convenient use of the heat exchange equipment, and reduce the heat transfer area and volume on the premise of guaranteeing the same heat exchange power. The intensified heat transfer technology aims to maximize the heat transferred by a heat transfer surface in unit time and unit area, namely, to improve the heat exchange coefficient of heat exchange equipment by certain measures so as to improve the heat exchange quantity in unit area. The heat transfer enhancement is divided into convection enhanced heat transfer and boiling enhanced heat transfer according to the heat transfer modes, and the heat transfer enhancement mechanism and the structure form are completely different. At present, the surface enhancement method is an ideal heat transfer enhancement technology, namely, the purpose of convection enhanced heat transfer and boiling heat transfer is achieved by improving the structure of a heat transfer surface.
SUMMERY OF THE UTILITY MODEL
Based on this, for the heat transfer effect of heat-transfer pipe in strengthening steam generator or other heat exchangers, the utility model provides a strengthen heat-transfer pipe, through the microstructuring on present smooth heat-transfer pipe surface, improve the boiling heat transfer capacity on heat-transfer pipe surface.
In order to achieve the above object, the present invention provides the following technical solutions:
the utility model provides a reinforce heat-transfer pipe, including the heat-transfer pipe, the heat-transfer pipe surface is equipped with the micro-structure.
The working principle is that the reinforced heat transfer pipe of the utility model realizes the reinforced heat transfer by improving the nucleate boiling heat transfer capability. By means of the surface strengthening method, namely a regular microstructure is added on the surface of the heat transfer pipe, on one hand, the recesses are greatly increased, the density of a vaporization core, namely a nucleation boiling point, is further improved, and the growth speed of bubbles is increased; on the other hand, the reasonable structure arrangement is favorable for the escape of bubbles on the surface of the heat transfer pipe, so that the bubble separation frequency is accelerated, the phenomenon that a vapor film is formed on the surface of the heat transfer pipe to block heat transfer is avoided, more water enters the surface of the heat transfer pipe, the heat transfer effect of the heat transfer pipe is enhanced, and the liquid heat transfer effect is far higher than that of a vapor state.
In one embodiment, the surface of the heat transfer pipe is provided with criss-cross micro-channels, and micro-structures are formed among the micro-channels.
Further, the depth and the width of the microstructure are both in micron order.
Further, the shape of the microstructure is one or a combination of square, circle, rectangle, triangle, diamond or trapezoid.
Typically, the microstructure size is between tens of microns to hundreds of microns. Further, the depth of the microstructure is 50 μm to 250 μm and the gap of the microstructure is 1 to 3 times the width of the microstructure in consideration of the actual processing conditions.
Furthermore, the microchannels on the surface of the heat transfer pipe are distributed at equal intervals and are arranged in a square or triangular mode.
In one embodiment, the heat transfer tube has a surface formed with micro-protrusions.
Further, the depth and the width of the micro-protrusions are both in micron-scale.
Further, the shape of the micro-protrusions is one or a combination of square, circle, rectangle, triangle, diamond or trapezoid.
Further, the depth of the micro-protrusions is 50-250 μm, and the gap of the micro-structure is 1-3 times of the width of the micro-structure.
Further, the micro-protrusions are formed on the surface of the heat transfer pipe by means of electric spark, laser or mechanical processing, preferably, the micro-protrusions are formed on the surface of the heat transfer pipe by means of mechanical processing, and the mechanical processing is the simplest and most convenient, and is also the manufacturing process of the enhanced heat transfer structure which is most suitable for engineering application.
Further, the criss-cross grooves are formed on the surface of the heat transfer pipe by means of electric spark, laser or mechanical machining, and preferably, the micro-protrusions are formed on the surface of the heat transfer pipe by means of mechanical machining, so that the mechanical machining is the simplest and most convenient, and is also the manufacturing process of the enhanced heat transfer structure which is most suitable for engineering application.
The utility model has the advantages of:
the micro-channel of the reinforced heat transfer pipe increases the density of the activated cavity, and the surface bulge and the surface recess are used as potential vaporization cores to reinforce the boiling heat transfer; meanwhile, due to the capillary action formed by the micro-channels, the escape of vapor bubbles and the supplement of liquid on the wall surface are facilitated, so that the boiling superheat degree is greatly reduced; the microstructure is beneficial to boiling heat transfer, so that the heat exchange strength of the reinforced surface is greatly improved compared with that of the traditional smooth surface.
Drawings
FIG. 1 is a schematic view of a heat transfer enhancement tube according to the present invention;
FIG. 2 is a schematic view of an enhanced heat transfer test performed on the enhanced heat transfer tube according to the first embodiment;
FIG. 3 is a schematic view of an enhanced heat transfer test conducted on a U-shaped heat transfer tube bundle comprised of enhanced heat transfer tubes according to the first embodiment.
In the figure, 1, a data acquisition unit; 2. a computer; 3. an external power supply; 4. a power conditioning device; 5. a vessel discharge; 6. an electric heater; 7. a thermocouple; 8. a copper electrode plate; 9. a reinforced heat transfer pipe; 10. a cooling water outlet header; 11. a pressure gauge; 12. a cooling water inlet; 13. a condenser coil; 14 a test vessel; I. a data acquisition system; II. A power supply system; III, testing a device system; 15. a steam outlet connection pipe; 16. a dryer; 17. a J-shaped tube; 18. a water supply ring pipe; 19. a support block; 20. a water chamber partition plate; 21. a hot side inlet connection pipe; 22. a hot side outlet connection pipe; 23. a water chamber end enclosure; 24. a tube sheet; 25. a U-shaped heat transfer tube bundle; 26. A descent sleeve; 27. a water supply connecting pipe; 28. a steam-water separator; 29. and (5) sealing the head.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples.
Example 1
Referring to fig. 1, the present embodiment provides a heat transfer enhancement tube 9, which includes a heat transfer tube having a microstructure formed on the surface thereof.
The method is characterized in that criss-cross micro-channels are formed on the surface of the heat transfer pipe in a micro electric spark wire cutting technology and a micro electric spark forming technology machining mode, the micro-channels are distributed at equal intervals and are arranged in a square shape, and a micro structure is formed among the micro-channels.
The shape of the microstructure is square, and the size of the microstructure is as follows: side length: 150-250 μm, height 50-150 μm, and gap 1-3 times of side length.
Referring to fig. 2, the heat transfer enhancement test of the heat transfer enhancement tube 9 of the present invention comprises the following steps:
(1) Both ends of the enhanced heat transfer tube 9 of the embodiment are fixed on the copper electrode plate 8;
(2) The thermocouple 7 is arranged on the inner wall of the reinforced heat transfer pipe 9 along the way, and boron nitride is filled in the thermocouple 7, so that the thermocouple 7 is tightly attached to the inner wall of the reinforced heat transfer pipe 9, and two ends of the reinforced heat transfer pipe 9 are sealed by adopting tetrafluoro rods;
(3) Filling water into the test container 14, wherein the water level reaches above the enhanced heat transfer pipe 9 but cannot reach the height of the condensing coil 13; the data acquisition system I is communicated with the power supply system II;
(4) Adjusting the power of the electric heater 6 to heat the water in the test container 14; during heating, the pressure within the test vessel 14 is monitored;
(5) When steam is generated, the pressure in the test container 14 is about 0.1MPa, an exhaust valve above the test container 14 is opened to remove non-condensable gas in the test container 14, and the opening time is about 1-2 minutes;
(6) When the pressure in the test container 14 reaches the test pressure, the test pressure is 1MPa or 2MPa, and the electric heater 6 at the lower end is closed; starting power supplies at two ends of the test piece;
(7) Adjusting the heating power according to the requirement of experimental test, such as experimental test heat flow density q =100kw/m 2 Heat transfer performance under operating conditions; heating power Q = UI = Q × pi × D × L;
(8) If the pressure in the test container 14 is higher than the required pressure, cooling water can be switched on, the flow of the cooling water is adjusted, and steam above the cooling water is cooled to reduce the pressure in the test container 14;
(9) Under the test working condition, when the system is stable, the data acquisition system I records and stores main test parameters including voltage, current, the temperature of the inner wall of the enhanced heat transfer pipe 9 and the like.
The heating voltage is adjusted to generate a certain heat flux density on the surface of the reinforced heat transfer pipe, after the reinforced heat transfer pipe is heated, bubbles are generated on certain specific points of a heating surface under the condition of a certain superheat degree, the smaller and smaller gas-storing micro-channels on the wall surface become a working vaporization core along with the increase of the superheat degree, the number of the bubbles is further increased, the liquid boundary layer is disturbed strongly, the heat exchange intensity between a heat release surface and liquid is improved, and the boiling heat release coefficient is gradually increased. Meanwhile, the pressure in the whole test process is ensured to be constant by adjusting the flow of cooling water, and finally the heat exchange equilibrium state is achieved.
The research of the enhanced heat transfer test shows that under normal pressure, the heat flow density is the same, the boiling heat transfer coefficient of the surface of the novel enhanced heat transfer structure is enhanced to a certain degree compared with that of a light plane, and the enhancement effect reaches about 50 percent; the heat transfer temperature difference is the same, the utility model discloses a novel reinforce heat transfer surface's heat transfer volume is compared and is improved more than 100% in the light plane. Meanwhile, the research on the influence of the size change of the microstructure on the enhanced heat transfer effect shows that the enhanced heat transfer effect is increased along with the increase of the height of the microstructure and is increased along with the decrease of the gap of the microstructure in the range of 50-250 um of the height of the microstructure; in the range of 50um-250um of the side length of the microstructure, increases with increasing side length of the microstructure. In addition, the change of the height and the gap of the microstructure has a great influence on the improvement of the enhanced heat transfer effect, and the change of the side length of the microstructure is relatively small.
Example 2
Referring to fig. 3, a U-shaped heat transfer tube bundle 25 composed of the enhanced heat transfer tubes 9 of the first embodiment was subjected to an enhanced heat transfer test, comprising the steps of:
(1) High-temperature high-pressure undersaturated water is introduced into the hot side inlet connecting pipe 21, and the shell side of the steam generator is filled with full water;
(2) Gradually increasing the temperature of the hot side water, heating the water in the shell side cylinder, increasing the temperature of the hot side water, and simultaneously increasing the running pressure of the hot side to ensure that the temperature of the hot side water has an under-heat degree of more than 20 ℃;
(3) As the shell side generates steam, water is evaporated, the water level is reduced, and then the operation water level and the steam pressure of the secondary side are controlled;
(4) Adjusting the parameters of the primary side and the secondary side to the test working conditions, and controlling the shell pass at 5MPa if the hot side is 290 ℃ on average;
(5) The test operating temperature, pressure and flow are recorded, and the heat transfer coefficient of the U-shaped heat transfer tube bundle 25 can be calculated.
In the same way, a contrast test is carried out on a smooth heat transfer tube bundle consisting of smooth heat transfer tubes, and the heat transfer coefficient of the heat transfer tube bundle is calculated. Test results show that the U-shaped heat transfer tube bundle 25 comprised of the enhanced heat transfer tubes 9 of example one can have a heat transfer coefficient that is improved by 6-15% over a smooth heat transfer tube bundle comprised of smooth heat transfer tubes. The U-shaped heat transfer tube bundle 25 comprised of the enhanced heat transfer tubes 9 of example one can maximize the heat transfer power by more than 10% over the smooth heat transfer tube bundle comprised of smooth heat transfer tubes at the same flow rate and inlet temperature.
Example 3
Referring to fig. 2, the present embodiment provides a bundle 9 of enhanced heat transfer tubes, which includes heat transfer tubes with microstructures on the surface.
The method is characterized in that criss-cross micro channels are formed on the surface of the heat transfer pipe in a micro electric spark wire cutting technology and micro electric spark forming technology processing mode, the micro channels are distributed at equal intervals and are arranged in a triangular mode, and micro structures are formed among the micro channels.
The shape of the microstructure is square, and the size of the microstructure is as follows: side length: 150-250 μm, height 50-150 μm, and gap 1-3 times of side length.
The reinforced heat transfer pipe of the utility model increases the concave cavities on the surface of the heat transfer pipe through the shape/size/arrangement of the reinforced heat transfer pipe, forms more vaporization cores and is easier to generate vapor bubbles; on the other hand, the reasonable structural style is beneficial to the escape of the bubbles, and the accumulation of the bubbles on the surface to form a vapor film to block the heat transfer is avoided.
The above-mentioned embodiments only represent several embodiments of the present invention, and the description thereof is more specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.
Claims (8)
1. The reinforced heat transfer pipe comprises a heat transfer pipe and is characterized in that the surface of the heat transfer pipe is provided with a microstructure; the surface of the heat transfer pipe is provided with criss-cross micro-channels, and microstructures are formed among the micro-channels; the depth and width of the microstructure are both micron-sized.
2. The enhanced heat transfer tube of claim 1, wherein the microstructures have a shape that is a combination of one or more of square, circular, rectangular, triangular, diamond, or trapezoidal.
3. The enhanced heat transfer tube of claim 1, wherein the microstructures have a depth of 50 μm to 250 μm and the microstructures have a gap of 1 to 3 times the width of the microstructures.
4. The enhanced heat transfer tube of claim 1, wherein the microchannels on the surface of the tube are equally spaced, and are arranged in a square or triangular pattern.
5. The enhanced heat transfer tube according to claim 1, wherein the heat transfer tube surface is formed with micro-protrusions.
6. The enhanced heat transfer tube of claim 5, wherein the depth and width of the micro-protrusions are on the order of microns.
7. The enhanced heat transfer tube of claim 5, wherein the shape of the micro-protrusions is one or a combination of square, circle, rectangle, triangle, diamond, or trapezoid.
8. The enhanced heat transfer tube of claim 5, wherein the depth of the micro-protrusions is 50 μm to 250 μm and the gaps of the microstructures are 1 to 3 times the width of the microstructures.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202123187350.8U CN217636944U (en) | 2021-12-17 | 2021-12-17 | Reinforced heat transfer pipe |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202123187350.8U CN217636944U (en) | 2021-12-17 | 2021-12-17 | Reinforced heat transfer pipe |
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| Publication Number | Publication Date |
|---|---|
| CN217636944U true CN217636944U (en) | 2022-10-21 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202123187350.8U Active CN217636944U (en) | 2021-12-17 | 2021-12-17 | Reinforced heat transfer pipe |
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| CN (1) | CN217636944U (en) |
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2021
- 2021-12-17 CN CN202123187350.8U patent/CN217636944U/en active Active
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