CN104296584A - Spiral band passive enhancement heat exchanging pipe - Google Patents

Abstract

A spiral bond passively reinforced heat exchange tube, comprising a base pipe and a spiral bond, the spiral bond is coiled in the base pipe, characterized in that the spiral bond is made of metal foam material and is sintered on the inner wall of the base pipe . According to the basic principle of heat transfer enhancement, the invention combines the characteristics of the metal foam material with the theory of turbulent flow. When the fluid flows in the tube, under the conduction action of the spiral bond, a spiral vortex will be generated, which will destroy the boundary layer of the fluid, enhance the disturbance, and greatly improve the heat transfer coefficient. At the same time, because of the porous metal foam, a part Fluid can also pass through the bond pores, reducing flow resistance. In addition, sintering such high-porosity metal foam helical bonds in the tube can extend the heat exchange surface to the inside of the fluid, greatly expanding the heat exchange area between the fluid and the wall.

Description

A spiral bond passively enhanced heat exchange tube

technical field

The invention relates to an enhanced heat exchange tube, in particular to a metal foam spiral bond passively enhanced heat exchange tube in a fluid heat exchanger or radiator.

Background technique

Installing spiral ties in the tubes to enhance heat exchange tubes is a highly efficient enhanced heat exchange form that enhances fluid turbulence, mixing and descaling. At present, many scholars have carried out research on the installation of spiral ties in the tube. Installing the spiral ties of metal foam material in the tube is a more effective way to enhance heat transfer. Patent CN2568324 proposes a device for installing a spiral bond in the base pipe; Document: Application of spiral bond to enhance heat transfer and descaling in condenser (Mao Kun, Li Lianjie; Energy Saving, 2007) studied the effect of spiral bond on condensation of steam The application of enhanced heat transfer and descaling in the device; Literature: Research on the structural relationship of the horizontal pipe hydrodynamic automatic cleaning of the spiral bond (Liu Jizhao, Liu Zhiru, Yu Xiumin; Machine Tools and Hydraulics, 2003) studied the effect of the structural parameters of the spiral bond on the cleaning ability of the bond , Fluid resistance and the relationship between heat transfer enhancement. These studies have their own characteristics on the installation of the spiral bond in the tube, but this kind of enhanced heat exchange tube generally adopts the method of separating the spiral bond from the tube wall. The unfixed spiral bond increases the vulnerability of the heat exchange tube, and due to The thermal conductivity of the helical bond is greatly limited when it is not in contact with the tube wall. In addition, the materials used to manufacture the spiral bonds are basically metal sheets, so the fluid mixing of this type of enhanced heat exchange tube is limited to a certain extent.

Metal foam is a kind of ideal heat exchange material developed in recent years that integrates high thermal conductivity, high permeability, high surface area density, light weight, excellent mechanical properties and good fluid mixing ability. Because the metal foam has strong fluid disturbance ability and flow conductivity, it can greatly enhance the fluid turbulence. The enhanced heat exchange channels fully filled with metal foam have extremely strong heat transfer performance, but the pressure drop is also large, which greatly limits the application of such forms of enhanced heat exchange fully filled with metal foam. The partially filled metal foam reinforced heat exchange tube with metal foam as the swirling element can not only generate a large amount of secondary flow during the fluid flow process, but also have a small flow pressure drop. Compared with the traditional strengthened tube with metal sheet spiral bond, the metal foam spiral bond reinforced tube can not only improve the mixing effect of the fluid on both sides of the bond, but also the passive enhanced heat transfer form of metal foam sintered on the tube wall can effectively transfer the heat of the tube wall To the inside of the fluid, so as to achieve the fin-type enhanced heat transfer effect.

Contents of the invention

In order to solve the problems existing in the traditional enhanced heat exchange tube, the object of the present invention is to provide a passive enhanced heat exchange tube with spiral ties, which is firm and durable, has good thermal conductivity and strong fluid mixing ability.

The technical solution adopted in the present invention is: a spiral bond passively reinforced heat exchange tube, including a base pipe and a spiral bond coiled in the base pipe, characterized in that the spiral bond is made of metal foam material and is fixed to the base pipe on the inner wall.

Preferably, the spiral tie is fixed on the inner wall of the base pipe through material sintering technology.

The spiral bond can run through the entire pipe section of the enhanced heat exchange tube, and can also be preferably arranged at a distance of no more than 50 times the pipe diameter from the nozzle, especially preferably at a distance of 25 to 50 times the pipe diameter, so as to ensure that the disturbed fluid Some are fully developed segments.

Preferably, the metal foam material has a porosity in the range of 0.8-0.99 and a pore density in the range of 5PPI-300PPI.

Preferably, the metal foam material is a material with high thermal conductivity such as copper, aluminum and alloys thereof.

Preferably, the thickness δ of the helical bond is not greater than 0.3 times the inner diameter d _t of the base pipe, ie δ≦0.3d _t .

Preferably, the pitch of the helical bond is smaller than the length of the tube. For long tubes of conventional size (tube length L>30cm), the pitch (B) of the helical bond is in the range of 20mm≤B≤200mm.

Preferably, the diameter d of the helical tie is equal to the inner diameter _dt of the base pipe.

Preferably, the type of fluid in the enhanced heat exchange tube is non-corrosive fluid.

According to the basic principle of enhanced heat transfer, the invention combines the characteristics of the metal foam material with the theory of turbulent flow, and the enhanced tube provided is a passive enhanced heat exchange tube with metal foam helical ties. When the fluid flows in the tube, under the conduction action of the spiral bond, a spiral vortex will be generated, which will destroy the boundary layer of the fluid, enhance the disturbance, and greatly improve the heat transfer coefficient. At the same time, because of the porous metal foam, a part Fluid can also pass through the bond pores, reducing flow resistance. In addition, sintering such high-porosity metal foam helical bonds in the tube can extend the heat exchange surface to the inside of the fluid, greatly expanding the heat exchange area between the fluid and the wall. If such passive enhanced heat exchange tubes are applied to tube heat exchangers and radiators, not only can the heat exchange performance of the tube heat exchange equipment be improved, but also a lower pressure drop can be ensured. Moreover, this structure does not require additional additional equipment, and the operation is stable and reliable without major changes in the structure of the original equipment. It is also suitable for replacement of enhanced heat exchange pipes for heat exchange equipment.

Description of drawings

Fig. 1 is a schematic diagram of the axial section of the heat exchange tube of the present invention

Fig. 2 is a schematic diagram of a vertical axial section of a heat exchange tube of the present invention

Detailed ways

The technical principle of the present invention will be further described below in conjunction with the accompanying drawings.

Example 1

Referring to FIG. 1 and FIG. 2 , a spiral-bonded passively enhanced heat exchange tube according to the present invention includes: a base pipe 1 , a spiral bond 2 , a fluid inlet port 3 and a fluid outlet port 4 . Among them, the spiral bond 2 is made of porous metal foam material, which is sintered on the inner wall of the base pipe of the heat exchange tube through foam sintering technology. The diameter of the spiral bond 2 is the same as the inner diameter of the base pipe 1, and the two ends of the spiral bond 2 They are all set at a distance of 30 times the pipe diameter from the nozzle. When the tube wall is cooled or heated by the fluid, the heat exchange fluid enters the heat exchange tube from the fluid inlet port 3, and swirls under the guidance of the spiral bond, and the fluid passes through the pores of the metal foam, which significantly enhances the The disturbance of the fluid is reduced, the heat exchange performance is improved, and the fluid flows out from the outlet port 4 after exchanging heat.

Example 2

In this embodiment, the diameter of the spiral bond 2 is slightly smaller than the inner diameter of the base pipe 1, and both ends of the spiral bond are arranged at a distance of 50 times the pipe diameter from the nozzle. In addition, the metal foam material used is copper aluminum alloy, the porosity of the metal foam material is 0.85, and the pore density is 200PPI. The thickness of the spiral bond 2 is 0.2 times the inner diameter of the base pipe 1, and the applicable fluid is air and other gases with low thermal conductivity.

Example 3

In this embodiment, the diameter of the spiral bond 2 is equal to the inner diameter of the base pipe 1, and both ends of the spiral bond are arranged at a distance of 40 times the pipe diameter from the nozzle. In addition, the metal foam material used is copper or aluminum, the porosity range of the metal foam material is 0.9, and the hole density range is 20PPI. The thickness of the spiral bond 2 is 0.1 times of the inner diameter of the base pipe 1, and the applicable fluid is a liquid with relatively high viscosity and good thermal conductivity.

The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make many modifications and changes according to the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art shall be within the scope of protection defined by the claims.

Claims (10)

1. a spiral band passive facilitation heat exchanger tube, comprises base tube and spiral band, and described spiral band spirals in base tube, it is characterized in that, described spiral band is made up of metal foaming material, and is fixed on the inwall of base tube.

2. thermoexcell according to claim 1, is characterized in that: described spiral band is fixed on described base tube inwall by material sintering technology.

3. thermoexcell according to claim 1, is characterized in that: described spiral band is arranged at the distance being not more than 50 times of calibers apart from the described base tube mouth of pipe.

4. thermoexcell according to claim 1, is characterized in that: described spiral band is arranged at the distance apart from the described base tube mouth of pipe 25 ~ 50 times of calibers.

5. thermoexcell according to claim 1, is characterized in that: the porosity ranges of described metal foaming material is 0.8-0.99, and hole density range is 5PPI-300PPI.

6. thermoexcell according to claim 1, is characterized in that: described metal foaming material is copper, aluminium or its alloy.

7. thermoexcell according to claim 1, is characterized in that: the thickness δ of described spiral band and described base tube internal diameter d _tbetween pass be δ≤0.3d _t.

8. thermoexcell according to claim 1, is characterized in that: as the pipe range L > 30cm of described base tube, and the scope of the pitch B of described spiral band is 20mm≤B≤200mm.

9. thermoexcell according to claim 1, is characterized in that: the external profile diameter of described spiral band equals base tube internal diameter.

10. the application of the thermoexcell according to any one of claim 1-9 on heat exchanger or radiator.