CN200944011Y

CN200944011Y - Fractal serrated fin

Info

Publication number: CN200944011Y
Application number: CN 200620071991
Authority: CN
Inventors: 陈亚平
Original assignee: Southeast University
Current assignee: Southeast University
Priority date: 2006-06-01
Filing date: 2006-06-01
Publication date: 2007-09-05
Anticipated expiration: 2016-06-01

Abstract

The utility model discloses a fractal sawtooth fin for a twist heat exchanger, which is composed of N stages (N equals to two to five) of continuously distributed rounded rectangle wavy fin segments. The adjacent rounded rectangle wavy fin segments reciprocally offset, each first stage wavy fin segment is composed of three second stage wavy fin segments, each second stage wavy fin segment is composed of three third stage wavy fin segments, the rest can be deduced by analogy; each N-1 stage wavy fin segment contains three N stage wavy fin segments and the offsetting direction is opposite to the offsetting direction of the N-1 stage, the offsets of all stages s <i> (i equals to one to N) step by step reduces with the increase of the stages. The utility model uses the offsets with different scales to realize the mutual rotation and perturbation of a mainstream and a boundary layer fluid inside a twist heat exchanger, which is beneficial to produce air bubbles and well distribute and cover the spray liquid films on a heat transfer surface for acquiring a good flow and intensifying the heat transfer and mass transfer properties.

Description

Parted saw tooth fin

Technical field

The utility model relates to a kind of fin of plate-fin heat exchanger, refers in particular to the parted saw tooth fin that a kind of plate-fin heat exchanger is used.

Technical background

Plate-fin heat exchanger is considered to one of the most rising novel heat-exchange apparatus because of its compact conformation, characteristics light and handy, that heat transfer efficiency is high.Fin form commonly used comprises flat type fin, porous type fin, flap type fin, rippled fin and serrated fin etc.Wherein, serrated fin (off-set fin) is that a kind of heat-transfer effect is better, the adaptability broad of fluid medium, and the good fin of load performance.But along with the progressively expansion of plate-fin heat exchanger range of application, particularly at aspects such as the cooling of strengthening electronic device and boiling, liquid film heat and mass transfer processes, to the fin demands for higher performance, the demand of development of new fin is also more and more urgent.

Summary of the invention

The utility model provides a kind of parted saw tooth fin that can improve heat and mass efficient.

The utility model adopts following technical scheme:

A kind of parted saw tooth fin that is used for plate-fin heat exchanger, form by 3 rank continuously arranged round rectangle corrugated fin section, adjacent round rectangle corrugated fin section is offset mutually, is offset s between the 1st rank odd wave corrugated fin section that its skew rule is 3 rank parted saw tooth fins and the 1st rank even number corrugated fin section ₁, each the 1st rank corrugated fin section is made up of 3 the 2nd rank corrugated fin sections, is offset s between the 2nd rank corrugated fin section that the 2nd rank corrugated fin section in the middle of it is adjacent ₂, the offset direction is opposite with the offset direction, the 1st rank of place corrugated fin section; Each the 2nd rank corrugated fin section is made up of 3 the 3rd rank corrugated fin sections, is offset s between the 3rd rank corrugated fin section that the 3rd rank corrugated fin section in the middle of it is adjacent ₃, the offset direction is opposite with the offset direction, the 2nd rank of place corrugated fin section; The side-play amount s on each rank _i(i=1～3) progressively reduce along with the raising of exponent number.

Compared with prior art, the utlity model has following advantage:

Surface with fractal pattern design fluid passage and heat and mass is to meet the mobile shortcut that gets twice the result with half the effort that reaches the element of the rule of heat and mass transfer process own of fluid with the similar creation of bionics to a certain extent.

1. strengthen convection heat transfer' heat-transfer by convection: because of the side-play amount on each rank of fractal fin unequal, fluid in the flow field, periodically experience asymmetric around fin shunting and converge.The skew of parted saw tooth fin low order large scale has guaranteed in flow process main flow fluid and the constantly conversion of nearly wall stagnation fluid " role "; And the side-play amount of high-order small scale is because close with the order of magnitude of fluid boundary layer thickness, the fluid that comes from the wall opposite side may go deep into this side interlayer inside in the segmentation aperture, this disturbance and renewal for boundary layer fluid can play an important role, can increase the augmentation of heat transfer effect greatly that produces under few condition in flow resistance, this is that common saw tooth fin is not available.

2. enhanced boiling heat transfer: when adopting as shown in Figure 8 parted saw tooth fin upper and lower surface to form the structure of groove, can make the contact-making surface of assembling back fin and dividing plate form numerous tunnel shape groove, and these many just researchers deliberately plan structure, but suffer from one of effective measures that are difficult to the enhanced boiling heat transfer realized with economic method.Simultaneously, fractal fin has formed the aperture that varies in size naturally at the corrugated sections place, and the microstome that the skew of high-order small scale forms is very beneficial for the generation of bubble, and the big aperture that the skew of low order large scale forms helps flowing of bubble and breaks away from; Add the slype of plate-fin heat exchanger itself has bubble is flattened, the effect of the enhanced boiling heat transfer that the liquid phase contact angle diminishes, therefore very favourable for the heat transfer of strengthening boiling process.This reeded parted saw tooth fin not only has using value for the plate-fin evaporator that air-separating plant is used, and the heat and mass transfer process that seethes with excitement under the little temperature difference in the lithium-bromide absorption-type refrigerating machine generator of using for solar airconditioning also will have good invigoration effect.

3. the heat and mass of forced fluid membrane process: the segmentation aperture of little side-play amount and horizontal channel help under tension force and gravity effect, make the spray liquid film well distributed and implicit at heating surface, extend one's stay, be difficult for dry spot takes place, this evaporimeter and absorber for lithium bromide refrigerator is all quite important.Solution continuous counter-rotating liquid film when parted saw tooth fin surface falling liquid film flows in addition, make concentration height, temperature low, the dark stronger absorbability solution that has of ensconcing liquid film inside is turned to and absorbs steam on the boundary, impel the film surface solution of exposure to bring in constant renewal in, keep bigger absorption potential difference, absorbability is strengthened.

Description of drawings

Fig. 1 is the structural upright schematic diagram of the utility model embodiment 1.

Fig. 2 is common (1 rank are fractal) saw tooth fin front view.

Fig. 3 is common (1 rank are fractal) saw tooth fin vertical view.

Fig. 4 is 2 rank parted saw tooth fin front views.

Fig. 5 is 2 rank parted saw tooth fin vertical views.

Fig. 6 is 3 rank parted saw tooth fin front views.

Fig. 7 is 3 rank parted saw tooth fin vertical views.

Fig. 8 is the structural upright schematic diagram of the utility model embodiment 2.

The specific embodiment

Embodiment 1: a kind of parted saw tooth fin that is used for plate-fin heat exchanger, form by 3 rank continuously arranged round rectangle corrugated fin section, adjacent round rectangle corrugated fin section is offset mutually, is offset s between the 1st rank odd wave corrugated fin section that its skew rule is 3 rank parted saw tooth fins and the 1st rank even number corrugated fin section ₁, each the 1st rank corrugated fin section 1 is made up of 3 the 2nd rank corrugated fin sections 2, is offset s between the 2nd rank corrugated fin section that the 2nd rank corrugated fin section in the middle of it is adjacent ₂, the offset direction is opposite with the offset direction, the 1st rank of place corrugated fin section; Each the 2nd rank corrugated fin section 2 is made up of 3 the 3rd rank corrugated fin sections 3, is offset s between the 3rd rank corrugated fin section that the 3rd rank corrugated fin section in the middle of it is adjacent ₃, the offset direction is opposite with the offset direction, the 2nd rank of place corrugated fin section; The side-play amount s on each rank _i(i=1～3) progressively reduce along with the raising of exponent number.

Embodiment 2: a kind of 3 rank parted saw tooth fins that are used for the plate-fin heat exchanger of enhanced boiling heat transfer, except the method by embodiment 1 is provided with the skew of corrugated fin section, also make the ripple height of centre the 3rd rank bellows segment that belongs to the 2nd rank bellows segment be lower than other 2 sections, promptly form groove in the fin upper and lower surface, be connected smoothly between interlude and other 2 sections, make it be formed with the tunnel-like groove that is beneficial to the enhanced boiling heat transfer process after the assembling with on the dividing plate contact-making surface.

With reference to the accompanying drawings the utility model being done one describes in detail:

(Fig. 2 is every a segment distance corrugated fin section alternately to be offset 1/4 ripple pitch to the left or to the right Fig. 3) to common saw tooth fin; And the skew rule of the corrugated fin section of parted saw tooth fin (Fig. 4 to Fig. 7) is determined by fractal self similarity rule.The parted saw tooth fin of this plate-fin heat exchanger, form by N rank (N=2～5) continuously arranged round rectangle corrugated fin section, it is characterized in that adjacent round rectangle corrugated fin section is offset mutually, be offset s between the 1st rank odd wave corrugated fin section that its skew rule is a N rank parted saw tooth fin and the 1st rank even number corrugated fin section ₁, each the 1st rank corrugated fin section is made up of 3 the 2nd rank corrugated fin sections, is offset s between the 2nd rank corrugated fin section that the 2nd rank corrugated fin section in the middle of it is adjacent ₂, the offset direction is opposite with the offset direction, the 1st rank of place corrugated fin section; Each the 2nd rank corrugated fin section is made up of 3 the 3rd rank corrugated fin sections, is offset s between the 3rd rank corrugated fin section that the 3rd rank corrugated fin section in the middle of it is adjacent ₃, the offset direction is opposite with the offset direction, the 2nd rank of place corrugated fin section; The rest may be inferred; Each N-1 rank corrugated fin section comprises 3 N rank corrugated fin sections, is offset s between the N rank corrugated fin section that the N rank corrugated fin section in the middle of it is adjacent _N, the offset direction is opposite with the offset direction, N-1 rank of place corrugated fin section, the side-play amount s on each rank _i(i=1～N) progressively reduce along with the raising of exponent number.

Occasion for enhanced boiling heat transfer, on above-mentioned parted saw tooth fin basis, can make the ripple height of N rank bellows segment of the centre that belongs to N-1 rank bellows segment of N rank parted saw tooth fin be lower than other 2 sections again, promptly form groove (as shown in Figure 8), be connected smoothly between interlude and other 2 sections in the fin upper and lower surface.

Exponent number N of the present utility model can 2,3,4 or 5, and for now, 3 rank parted saw tooth fins are proper selections.

Claims

1. parted saw tooth fin that is used for plate-fin heat exchanger, by the N rank, N=2～5, continuously arranged round rectangle corrugated fin section is formed, it is characterized in that adjacent round rectangle corrugated fin section is offset mutually, be offset s between the 1st rank odd wave corrugated fin section that its skew rule is a N rank parted saw tooth fin and the 1st rank even number corrugated fin section ₁, each the 1st rank corrugated fin section is made up of 3 the 2nd rank corrugated fin sections, is offset s between the 2nd rank corrugated fin section that the 2nd rank corrugated fin section in the middle of it is adjacent ₂, the offset direction is opposite with the offset direction, the 1st rank of place corrugated fin section; Each the 2nd rank corrugated fin section is made up of 3 the 3rd rank corrugated fin sections, is offset s between the 3rd rank corrugated fin section that the 3rd rank corrugated fin section in the middle of it is adjacent ₃, the offset direction is opposite with the offset direction, the 2nd rank of place corrugated fin section; The rest may be inferred; Each N-1 rank corrugated fin section comprises 3 N rank corrugated fin sections, is offset S between the N rank corrugated fin section that the N rank corrugated fin section in the middle of it is adjacent _N, the offset direction is opposite with the offset direction, N-1 rank of place corrugated fin section, the side-play amount S on each rank _i, i=1～N progressively reduces along with the raising of exponent number.

2. according to the described parted saw tooth fin of claim 1, the ripple height of N rank corrugated fin section that it is characterized in that belonging to the centre of N-1 rank corrugated fin section is lower than other 2 sections, and they are connected smoothly each other.