CN102679789A

CN102679789A - Spiral corrugated pipe

Info

Publication number: CN102679789A
Application number: CN2012101485706A
Authority: CN
Inventors: 杨金国; 刘佳驹; 刘伟; 范爱武; 刘志春; 杨昆; 黄晓明; 方海生
Original assignee: Huazhong University of Science and Technology
Current assignee: Huazhong University of Science and Technology
Priority date: 2012-05-14
Filing date: 2012-05-14
Publication date: 2012-09-19

Abstract

The invention discloses a spiral corrugated pipe which comprises a hollow pipe body and 1 to 4 spiral head structure(s), wherein the spiral head structures are connected with spiral channels to form rotational flow in the hollow pipe body when fluid flows through the hollow pipe body; the depth of the spiral channel is 1mm to 500mm; the number of the spiral channels is equal to that of the spiral head structures; waves on the inner and outer surfaces of the hollow pipe body are in continuous spiral shapes with the same pitch and wave form; the inner diameter of the hollow pipe body is 1mm to 1,000mm, and the wall thickness of the hollow pipe body is 0.1mm to 20mm; and the pitch of the waves on the inner and outer surfaces of the hollow pipe body is 10mm to 500mm. In the invention, the fluid in the pipe is forced to flow ahead in an overall rotation manner through the spiral channels with certain depth, a synergic relationship between a velocity field and a temperature field is changed, and the generation of local resistance of in-pipe flow is effectively suppressed; and if the on-way resistance is increased little, a heat transfer enhancement effect is realized.

Description

A kind of helical bellows

Technical field

The invention belongs to the heat transfer unit (HTU) field, more specifically, relate to a kind of helical bellows.

Background technology

Helical bellows is a kind of good efficient special-shaped enhanced heat exchange pipe fitting, and the heat transfer process of convection cell has significant invigoration effect, and is widely used in the heat exchanger manufacturing.

Yet traditional helical bellows forces tube fluid to produce strong Secondary Flow through the spiral channel structure of tube wall, with the attenuate boundary layer; Enhanced heat exchange; Helical bellows has also produced bigger local resistance when heat exchange is strengthened, comprehensive heat exchange effect is remarkable inadequately.

Summary of the invention

Defective to prior art; The object of the present invention is to provide a kind of helical bellows; Be intended to solve the not enough distinct issues of local resistance excessive, the comprehensive heat exchange property of increase that flow in the existing helical bellows pipe; The effectively generation of mobile local resistance in the killer tube improves comprehensive heat exchange property, and realizes the two-sided strengthened effect of helical bellows heat exchange.

For realizing above-mentioned purpose, the invention provides a kind of helical bellows, comprise hollow tube and spiral head structure, the spiral head structure is connected with helical channel, is used at fluid through the out-of-date eddy flow that in hollow tube, forms, and the degree of depth of helical channel is 1～500mm.

The quantity of helical channel equates with the quantity of spiral head structure.

The quantity of spiral head structure is 1～4.

Ripple on the surfaces externally and internally of hollow tube is that pitch, waveform are identical, and the spirality of moving towards continuously.

The internal diameter of hollow tube is 1～1000mm, and wall thickness is 0.1～20mm.

The pitch of ripple is 10～500mm on the surfaces externally and internally of hollow tube.

Compared with prior art, the present invention has following beneficial effect:

(1) the helical bellows cross-sectional area equates all the time, the generation of the local resistance of flowing in can reducing to manage;

(2) helical channel with certain depth at helical corrugation tube wall place, but tub of tissue inner fluid integral body eddy flow forward, thereby the radially mixing of enhance fluid; Reduce the angle between velocity and the thermograde vector; Improve the heat exchange effect, integral cyclone does not produce strong Secondary Flow in the pipe simultaneously, and local resistance is very little; On-way resistance increases less, and comprehensive heat exchange effect improves outstanding;

(3) integral cyclone in the helical bellows pipe can effectively suppress the generation of tube wall incrustation, improves the service life and the security performance of heat exchanger, is specially adapted to adopt the occasion of high viscosity, unholiness and easy coking heat-exchange working medium;

(4) helical channel plays the flow-disturbing effect to extratubal fluid, thereby realizes the two-sided strengthened effect of helical bellows heat exchange.

Description of drawings

Fig. 1 is the structural representation of helical bellows of the present invention.

Fig. 2 is the front view of Fig. 1.

Fig. 3 is the left view of Fig. 2.

Fig. 4 is the change curve of Nu-number under the Reynolds number of the different flow fields of the present invention.

Fig. 5 is the change curve of coefficient of frictional resistance under the Reynolds number of the different flow fields of the present invention.

Fig. 6 is the change curve of performance evaluation coefficient under the Reynolds number of the different flow fields of the present invention.

The specific embodiment

In order to make the object of the invention, technical scheme and advantage clearer,, the present invention is further elaborated below in conjunction with accompanying drawing and embodiment.Should be appreciated that specific embodiment described herein only in order to explanation the present invention, and be not used in qualification the present invention.

As shown in Figure 1, helical bellows of the present invention comprises hollow tube 1 and spiral head structure 2, and the spiral head structure is connected with helical channel 3, be used for fluid through out-of-date hollow tube 1 in the formation eddy flow, the depth H of helical channel 3 is 1～500mm.

The quantity of helical channel 3 equates with the quantity of spiral head structure 2.In this embodiment, the quantity of spiral head structure 2 is 1～4.

Ripple on the surfaces externally and internally of hollow tube 1 is that pitch, waveform are identical, and the spirality of moving towards continuously.The inner diameter d of hollow tube 1 is 1～1000mm, and wall thickness is 0.1～20mm.

The pitch of ripple is 10～500mm on the surfaces externally and internally of hollow tube 1.

Below helical bellows is carried out numerical simulation calculation, specified criteria is following:

The degree of depth of helical channel is 1～5mm, and the length of helical bellows is 600mm, and the pitch of ripple is 30mm; The quantity of spiral head structure is 4; Fluid is a water, and the scope of reynolds number Re is 300～1800, and boundary condition is: given wall heat flow density and speed u; Outlet is the condition of effluenting, wall heat flow density q=10000W/m ²

The flow field reynolds number Re is given by following formula:

Re = \frac{u \times d_{m}}{&upsi;}

In the formula, υ is the fluid motion viscosity, d _mBe the equivalent diameter of helical corrugation bore, and be defined as

d_{m} = \frac{4 A}{P}

In the formula, A is the area of section of helical corrugation bore, and P is the moistening girth in the cross section of helical corrugation bore.

For heat exchange in the analyzer tube and drag characteristic, resistance coefficient f is defined as:

f = \frac{2 d_{m} ΔP}{ρL V_{m}^{2}}

In the formula, Δ P is the import and export pressure drop of helical bellows, and ρ is a fluid density, and L is the length of helical bellows, V _mBe fluid average speed.

Convection transfer rate h and Nu-number Nu are defined as:

h = \frac{q}{T_{w} - T_{f}}

Nu = \frac{{hd}_{m}}{λ}

In the formula, T _wBe wall surface temperature, T _fBe the fluid mean temperature, λ is the fluid thermal conductivity factor.

The performance evaluation coefficient of heat exchange and resistance (Performance Evaluation Criterion is called for short PEC) is defined as:

PEC = \frac{Nu / {Nu}_{0}}{{(f / f_{0})}^{1 / 3}}

In the following formula, Nu ₀The Nu-number of the light pipe that expression equates with helical bellows equivalent diameter and heat exchange area, f ₀Be the light pipe resistance coefficient.

Helical bellows heat exchange and calculation of resistance result such as Fig. 4～shown in Figure 6.Visible by Fig. 4, Fig. 5, it is several more than 1.5 times that 3mm helical bellows Nu number can reach 1mm helical bellows Nu, and it is several more than 2 times that 5mm helical bellows Nu number can reach 1mm helical bellows Nu; And that coefficient of frictional resistance f deep trouth helix tube and shallow slot helix tube are compared amplification is little.Visible by Fig. 6, the comprehensive heat exchange property evaluation coefficient of deep trouth helical bellows PEC value reaches as high as about 2.4.

The PEC value of the degree of depth correspondence of different helical channels is as shown in the table, and eddy flow is difficult for forming in

pipe when the degree of depth of helical channel is more shallow; To cross when dark

tube fluid flow resistance excessive when the degree of depth of helical channel; Comprehensive heat exchange property is neither outstanding; When the ratio of the degree of depth of helical channel and hollow tube internal diameter is between 0.1 and 1; It is thus clear that comprehensive heat exchange property is comparatively outstanding, this is owing to formed tangible longitudinal cyclone in the pipe.

Those skilled in the art will readily understand; The above is merely preferred embodiment of the present invention; Not in order to restriction the present invention, all any modifications of within spirit of the present invention and principle, being done, be equal to and replace and improvement etc., all should be included within protection scope of the present invention.

Claims

1. a helical bellows is characterized in that, comprises hollow tube and spiral head structure, and said spiral head structure is connected with helical channel, is used in said hollow tube, forming eddy flow through out-of-date at fluid, and the degree of depth of said helical channel is 1～500mm.

2. helical bellows according to claim 1 is characterized in that, the quantity of said helical channel equates with the quantity of said spiral head structure.

3. helical bellows according to claim 2 is characterized in that, the quantity of said spiral head structure is 1～4.

4. helical bellows according to claim 1 is characterized in that, the ripple on the surfaces externally and internally of said hollow tube is that pitch, waveform are identical, and the spirality of moving towards continuously.

5. helical bellows according to claim 4 is characterized in that, the internal diameter of said hollow tube is 1～1000mm, and wall thickness is 0.1～20mm.

6. helical bellows according to claim 4 is characterized in that, the pitch of ripple is 10～500mm on the surfaces externally and internally of said hollow tube.