CN209763840U

CN209763840U - internal thread heat transfer pipe structure of fractal structure

Info

Publication number: CN209763840U
Application number: CN201920495796.0U
Authority: CN
Inventors: 杨玉; 顾正萌; 高炜; 张磊; 李红智; 姚明宇
Original assignee: Thermal Power Research Institute
Current assignee: Xian Thermal Power Research Institute Co Ltd
Priority date: 2019-04-12
Filing date: 2019-04-12
Publication date: 2019-12-10
Anticipated expiration: 2029-04-12

Abstract

The utility model discloses an internal thread heat transfer tube structure with a fractal structure, which comprises a tube body and fractal thread teeth on the inner wall surface of the tube body, wherein the shape of the fractal thread teeth on the cross section of the tube body is a Koch curve or is formed by deforming a standard Koch curve, and the inner wall surface of the tube body of the heat transfer tube is formed by axially rotating and stretching the Koch curve or is formed by deforming the inner wall surface of the tube body from the standard Koch curve; the contact area between the fluid and the pipe wall is increased, so that the heat transfer power between the fluid and the pipe wall is increased under the condition that the heat transfer coefficient and the heat transfer temperature difference are not changed, and the heat transfer performance is obviously improved; the fractal internal thread teeth are deeply arranged in the fluid, the guiding effect of the fractal internal thread teeth on the fluid is stronger than that of the common internal thread teeth, and the fluid working medium generates stronger rotary flow, so that the fluid in the pipe is better mixed, the cooling effect on the wall surface is better, the heat transfer deterioration generated when the physical property of the fluid is violently changed can be inhibited, and the operation of the heat transfer pipe is safer and more reliable.

Description

Internal thread heat transfer pipe structure of fractal structure

Technical Field

The utility model belongs to the heat transfer field, concretely relates to internal thread heat transfer tube structure of fractal structure.

Background

Compared with the traditional water/steam Rankine cycle power generation system, the supercritical carbon dioxide Brayton cycle power generation system has the advantages of higher efficiency, higher flexibility, smaller equipment size and the like, so that research on the supercritical carbon dioxide Brayton cycle power generation system is successively carried out by national and international research institutes and energy institutions.

the supercritical carbon dioxide Brayton cycle system can be applied to the fields of photo-thermal power generation, nuclear power, coal-fired power generation, waste heat power generation and the like, wherein a carbon dioxide working medium is heated to 10-30 MPa and 400-700 ℃ in a heater and then enters a turbine to do work. The heat absorption performance of the carbon dioxide working medium in the heater is poorer than that of the water working medium, namely the cooling capacity of the carbon dioxide working medium on the heat transfer pipe is poorer, and the temperature of the pipe wall of the heat transfer pipe cooled by the carbon dioxide working medium can be higher under the condition of the same wall surface heat flux density, so that the safety of a crisis unit is guaranteed.

At present, a working medium heater in a water/steam working medium Rankine cycle power generation system adopts an internal threaded pipe for strengthening heat transfer, the number of the heads of the internal threaded pipe is generally 4-6, the shape of a thread is trapezoidal or rectangular, and the lead angle of the thread is 30-60 ℃. Although the internal thread heat transfer pipe with the simple structure can also be used for enhancing the heat transfer performance of the supercritical carbon dioxide working medium in the heater, the degree of improving the heat transfer capacity is still limited, and the heat transfer performance of the water working medium cannot be achieved. Therefore, it is of great engineering and practical significance to develop a novel heat transfer pipe to improve the heat transfer capacity of the supercritical carbon dioxide in the heater.

In view of this, the utility model provides a fractal structure's internal thread heat-transfer pipe is showing the heat transfer performance who promotes supercritical carbon dioxide working medium, improves the cooling capacity of carbon dioxide working medium to the wall, improves the performance and the security of system.

Disclosure of Invention

The utility model aims to solve the problem that the heat transfer capacity of supercritical carbon dioxide working medium in the heater is not enough, provide an internal thread heat transfer tube structure of fractal structure, increase the heat transfer area between pipe wall and fluid, strengthen intraductal fluidic mixture to strengthen intraductal working medium and conduct heat.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

The inner thread heat transfer pipe structure of a fractal structure comprises a pipe body 2 and fractal thread teeth on the inner wall surface of the pipe body 2, wherein the shape of the fractal thread teeth on the cross section of the pipe body 2 is a Koch curve 1 or is formed by deforming a standard Koch curve, and the inner wall surface of the pipe body 2 of the heat transfer pipe is formed by axially rotating and stretching the Koch curve 1 or the inner wall surface of the pipe body 2 is formed by deforming the standard Koch curve.

The Koch curve 1 of the inner wall surface of the tubular body 2 forming the heat transfer pipe is a 2 th to 6 th order Koch curve.

The helix angle of the internal thread of the fractal thread tooth is 30-60 degrees.

The adjacent two edges of the cross section pattern of the heat transfer pipe are smoothly transited by chamfers.

The utility model discloses following beneficial effect has: the fractal thread tooth structure on the inner wall surface of the heat transfer pipe adopts a Koch curve with more than 2 orders, so that the contact area between the fluid and the pipe wall is increased, and the heat transfer power between the fluid and the pipe wall is greatly increased under the condition that the heat transfer coefficient and the heat transfer temperature difference are not changed; the fractal internal thread teeth penetrate into the fluid, the guiding effect on the fluid is stronger than that of the common internal thread teeth, namely, the working medium in the internal thread heat transfer pipe with the fractal structure flows more strongly in a rotating manner, so that the fluid in the heat transfer pipe is better mixed, the cooling effect on the wall surface is better, and the heat transfer deterioration generated when the physical property of the fluid is changed violently can be inhibited.

Drawings

Fig. 1 is a schematic cross-sectional view of an internally threaded heat transfer tube structure of a fractal structure of a koch curve.

Fig. 2 is a schematic diagram of an internal thread heat transfer tube with a fractal structure.

Fig. 3 is a schematic cross-sectional view of an internally threaded heat transfer tube structure deformed by a standard koch curve to form a fractal structure.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings:

As shown in fig. 1, in the internally threaded heat transfer pipe structure of the fractal structure according to the present embodiment, the shape of the inner wall surface of the pipe body 2 is a koch curve 1 in any cross section, and the order of the curve is greater than 2. As shown in fig. 2, the inner wall surface of the pipe body 2 is generated by rotation and translation of the koch curve 1.

As shown in fig. 3, the inner wall surface of the pipe body 2 may be deformed from a standard koch curve to have a shape similar to that of the koch curve 3, so as to reduce the processing difficulty and cost.

The utility model discloses a concrete working process does:

When a fluid working medium flows in the heat transfer tube, the heat transfer between the fluid and the wall of the heat transfer tube follows the following equation:

Q＝hAΔT

in the formula, Q is heat transfer power, h is heat transfer coefficient, A is heat transfer area, and Delta T is heat transfer temperature difference. The utility model provides a fractal thread tooth structure and ordinary pipe and internal thread pipe compare, have bigger heat transfer area A, under the condition of the same pipeline circulation sectional area promptly, 3 grades of koch curve fractal thread tooth's heat transfer area is about 2 ~ 2.5 times of ordinary fluorescent tube and internal thread pipe. Therefore, the internal thread heat transfer pipe with the fractal structure improves the heat transfer power by 2-2.5 times under the condition that the heat transfer coefficient h and the heat transfer temperature difference delta T are not changed, and the heat transfer performance of the heat transfer pipe is greatly improved.

in addition, the thread of the fractal thread tooth is deeply inserted into the fluid, when the fluid flows in the pipe, the fluid working medium can generate stronger rotary flow under the flow guiding effect of the fractal thread tooth, the strong rotary flow can enhance the cooling of the working medium on the pipe wall, and meanwhile, the heat transfer deterioration generated when the physical property of the fluid is changed violently can be inhibited, so that the operation of the heat transfer pipe is safer and more reliable.

Claims

1. The utility model provides a fractal internal thread heat transfer tube structure which characterized in that: the fractal spiral tooth heat transfer tube comprises a tube body (2) and fractal spiral teeth on the inner wall surface of the tube body (2), wherein the shape of the fractal spiral teeth on the cross section of the tube body (2) is a Koch curve (1) or is formed by deforming a standard Koch curve, and the inner wall surface of the tube body (2) of the heat transfer tube is formed by axially rotating and stretching the Koch curve (1) or the inner wall surface of the tube body (2) is formed by deforming the standard Koch curve.

2. The internal thread heat transfer tube structure of a fractal structure as set forth in claim 1, wherein: the Koch curve (1) of the inner wall surface of a pipe body (2) forming the heat transfer pipe is a 2-order to 6-order Koch curve.

3. The internal thread heat transfer tube structure of a fractal structure as set forth in claim 1, wherein: the helix angle of the internal thread of the fractal thread tooth is 30-60 degrees.

4. The internal thread heat transfer tube structure of a fractal structure as set forth in claim 1, wherein: the adjacent two edges of the cross section pattern of the heat transfer pipe are smoothly transited by chamfers.