CN2624158Y

CN2624158Y - Intensified heat transfer fin

Info

Publication number: CN2624158Y
Application number: CNU032189648U
Authority: CN
Inventors: 陶文铨; 屈治国; 程永攀; 何雅玲
Original assignee: Xian Jiaotong University
Current assignee: Xian Jiaotong University
Priority date: 2003-05-26
Filing date: 2003-05-26
Publication date: 2004-07-07
Anticipated expiration: 2013-05-26

Abstract

A reinforced heat exchange fin, which is used in evaporators and condensers of refrigeration and air conditioning devices and in interstage coolers of air compressors, is provided. The utility model comprises a uropatagium and bridge-shaped gibbous tablets arranged on the uropatagium. The bridge-shaped gibbous tablet comprises legs connecting the uropatagium and a square peak. Separated by the middle of flow direction of the uropatagium, the space in the bridge-shaped tablets in the upper part of air flow is greater than that of the lower part. When a fluid flows, the fluid is ruined at the edge level on the surface of the fin at the positions of the bridge-shaped tablets, and turbulence of fluid is enhanced, which improves the synergy of the speed of the fluid and temperature gradient, thus improving heat exchange. As the bridge-shaped tablets are properly located, the resistance of fluid increases little, the utility model greatly enhances the function of heat transfer of finned tube heat exchangers, reduces the volume of heat exchange device, and lowers the costs of products.

Description

The enhanced heat exchange fin

One, technical field

The utility model relates to a kind of heat exchange fin, particularly a kind ofly is applied to freeze and the evaporimeter of air-conditioning equipment and the heat exchange fin in condenser and the air compressor charge air cooler.

Two, background technology

In the evaporimeter that in refrigeration and air-conditioning, uses and the charge air cooler of condenser and air compressor, cold-producing medium or cooling medium flow in pipe, air flows outside pipe, because the most of thermal resistance in the diabatic process all concentrates on air side, so in order to strengthen heat exchange, just fin is installed,, is reduced the thermal resistance of air side to increase heat exchange area in air side.But in the present plain fin pipe that uses, because along the mobile direction of air, air makes the concertedness variation of speed and thermograde, thereby heat transfer property is descended at the boundary layer meeting progressive additive that fin surface forms.In order further to improve the heat transfer property of finned tube exchanger, adopted the better fin of enhanced heat exchange performance, slitted fin is wherein a kind of more effective enhanced heat exchange mode.So far there are many documents and patent that slitted fin is studied.Patent 96113217.5 is provided with 6 row's silvers at fin surface, but the shape more complicated of each silver silver parallel to each other, comprise three kinds of shapes, be respectively rectangle, parallelogram and trapezoidal, also used trapezoidal venetian blind type silver in the patent 96113216.7, and the arranged direction of trapezoidal length of a film limit and minor face has been carried out requirement.Patent 97117302.8 provides four kinds of multi-form type of incision at fin surface, although above-mentioned several method can improve the heat exchange property of fin, processing is difficulty relatively, and the fluid flow resistance increase is also fairly obvious.Because straight slitted fin processing is fairly simple, so be widely used.United States Patent (USP) 732903 and document [1] [document 1:Wang C C, Tao W H, Chang C J.Aninvestigation of the airside performance of the slit fin-and-tube heatexchangers.Int J ofRefrigeration, 1999,22:595-603.] provided a kind of slitted fin form of using on the air-conditioning, but these fins all are unidirectional cracking, and the seam of some is combined, being arranged on the fin between the adjacent pipe, also is evenly to arrange on fluid flow direction.Document [2] [document 2:Du Y J, Wang C C.An experimental study of theairside performance of the superslit fin-and-tube heat exchangers.Int J Heatand Mass Transfer, 2000,43:4475-4482, .] and document [3] [document 3:Yun J Y, Lee K S.Influence of design parameters on the heat transfer and flow frictioncharacteristics of the heat exchanger with slit fins.Int J Heat and MassTransfer, 2000,43:2529-2539.] some two-way fins that crack have been proposed, but also be evenly to arrange.Document [4] [document 4:Kang H C, Kim M H.Effect of strip location on theair-side pressure drop and heat transfer in strip fin-and-tube heat exchanger.Int J Refrigeration, 1998,22:302-312.] then studied two kinds of inhomogeneous slitted fins, a kind of is to crack to concentrate on the first half of fin entirely, a kind of is to crack to concentrate on the latter half of fin entirely, makes that like this some part of fin is not strengthened.Above-mentioned slitted fin in enhanced heat exchange, often is accompanied by the increase of bigger resistance, and operating cost is increased.Document [5-10] [document 5:Guo Z Y is seen in field synergistic principle and the exploitation that utilizes numerical computation method to carry out strengthening surface under the guidance of this principle, Li D Y, Wang B X.A novel concept for convectiveheat transfer enhancement.Int J Heat Transfer, 1998,41:2221-2225], [document 6:Wang S, Li Z X, Guo Z Y.Novel concept and device of heat transferaugmentation.In:Proceedings of 11 ^#International Conference of HeatTransfer, 1998.Philadelphia.Taylor ﹠amp; Francis, 5:405-408.], [document 7:Tao WQ, Guo Z Y, Wang B X.Field synergy principle for enhancing convective heattransfer-its extension and numerical verification.Int J Heat and Mass Transfer.2002,45 (18): 3849-3856.], [document 8:Tao WQ, He YL, Wang QW, et al.Aunified analysis on enhancing single phase convective heat transfer with fieldsynergy principle.Int J Heat and Mass Transfer.2002,45 (24): 3871-4879.], [document 9: inscription on pottery select, He Yaling. the application in strengthening heat convection and vascular improvement in performance of synergistic principle (on), XI AN JIAOTONG UNIVERSITY Subject Index, 2002,36 (11): 1101-1105], [document 10: He Yaling, the application (descend) of inscription on pottery select .. field synergistic principle in strengthening heat convection and vascular improvement in performance, XI AN JIAOTONG UNIVERSITY Subject Index, 2002,36 (11): 1106-1110].Fewer if crack, the disturbance of its convection cell and will be smaller to the destruction of the flow boundary layer of air, a concertedness is improved not enough, can not strengthen heat exchange effectively.If but it is many to crack, in the circulation passage of air, seam leg and silver are many, have hindered flowing of air, and the resistance of whole heat exchanger is increased often, can not meet the demands.

Three, summary of the invention

The purpose of this utility model is to provide a kind of heat transfer that can increase air fin exchanger, reduces resistance, reduces to freeze and the evaporimeter of air-conditioning equipment the enhanced heat exchange fin of the volume of condenser and charge air cooler.

For achieving the above object, the technical solution adopted in the utility model is: comprise substrate and the bridge shape silver that is opened in on-chip projection, the bridge shape silver of projection is made up of leg that is connected with substrate and rectangular top, be characterized in that the center with the substrate flow direction is the boundary, the spacing of each bridge shape silver of the mobile upstream of air is greater than the spacing of each bridge shape silver of air flow downstream, and promptly the sum of the bridge shape silver of the mobile upstream of air is less than the sum of air flow downstream bridge shape silver.

Another characteristics of the present utility model are: the height of bridge shape silver is half of spacing of fin that is sleeved on heat exchanger tube; Bridge shape silver alternatively up and down on substrate is offered; Symmetrical along air-flow direction by the bridge shape silver of the center line of heat exchanger tube.

The utility model is the boundary with the center of substrate flow direction, the spacing of the bridge shape silver of the mobile upstream of air is greater than the spacing of the bridge shape silver of air flow downstream, upstream end is at entrance because the substrate air flows, exchange capability of heat itself is just more intense, so the gap ratio between the bridge shape silver is bigger, air flow downstream at fin, because exchange capability of heat is more weak, so the gap ratio between the bridge shape silver is less, the boundary layer of air is effectively destroyed, strengthened heat exchange, adopted the utility model can strengthen heat exchange effectively, made the resistance of whole fin be unlikely to increase too many again.

Four, description of drawings

Fig. 1 is a kind of structural representation of the present utility model;

Fig. 2 is the A-A cutaway view of Fig. 1;

Fig. 3 is the B-B cutaway view of Fig. 1;

Fig. 4 is the heat exchange property comparison diagram of the utility model and plain film;

Fig. 5 is the resistance performance comparison diagram of the utility model and plain film;

Fig. 6 is at the comparison diagram that consumes the utility model and plain film exchange capability of heat under the identical pump merit.

Five, the specific embodiment

Below in conjunction with accompanying drawing the utility model is described in further detail.

Referring to Fig. 1,2,3, the utility model comprises the bridge shape silver 2 of substrate 1 and the projection that alternatively up and down is offered on substrate 1, the bridge shape silver 2 of projection is made up of leg 3 that is connected with substrate 1 and rectangular top 4, center with substrate 1 flow direction is the boundary, the spacing of the bridge shape silver 2 of the mobile upstream of air is greater than the spacing of the bridge shape silver 2 of air flow downstream, just the sum of the bridge shape silver 2 of the mobile upstream of air should be less than the sum of air flow downstream bridge shape silver 2, bridge shape silver 2 along the center line of air-flow direction by heat exchanger tube 5 is symmetrical, and the height of bridge shape silver 2 is half of heat exchange fin spacing that is sleeved on heat exchanger tube 5.

The utility model is optimized for cracking of fin surface under the collaborative guide of theory in the field of augmentation of heat transfer, make it to compare with fin in the past, under identical exchange capability of heat, resistance ratios is less, perhaps under the situation that consumes identical pump merit, exchange capability of heat is bigger, i.e. the ratio that heat exchange increases is greater than the ratio that resistance increases.

The inventor carries out The results of numerical simulation to the mobile and heat transfer of flat fin and shows: in the mobile upstream of fin air, the concertedness in velocity field and temperature field is relatively good, the angle of speed and thermograde is smaller, and in fin air flow downstream, the concertedness in velocity field and temperature field is poor, and promptly the angle of the two is bigger.On this basis, calculate after plain film cracked, find that the existence of cracking can obviously change the collaborative situation in velocity field and temperature field, the angle of the near zone that reduced to crack has strengthened heat exchange.Under the situation of taking all factors into consideration heat exchange and resistance, the utility model utilization field synergistic principle is optimized for the layout of cracking, optimizing the result shows, in order to improve the heat transfer property of fin effectively, should be in fin air flow downstream, promptly more seam is opened in the collaborative poor place of situation in velocity field and temperature field, the reason of the utility model dredges before fin surface adopts the afterwards close mode of cracking that Here it is.

By the resulting conclusion of numerical computations, with traditional augmentation of heat transfer theory be on all four.Dredge the close mode of cracking in back before fin surface has adopted, the fin air flows upstream end at entrance, and heat exchange itself is just more intense, so the gap ratio between cracking is bigger.In fin air flow downstream, because exchange capability of heat is more weak,, the boundary layer of air is destroyed effectively so the gap ratio between cracking is less, strengthened heat exchange.Adopt the utility model can strengthen heat exchange effectively, make the resistance of whole fin be unlikely to increase too many again.

The utility model is compared with plain film, the ratio that this slitted fin heat exchange increases will be higher than the ratio that resistance increases, and combination property is higher than other reinforcement fin surface, and whole heat exchanger volume can be dwindled about 1/3, under the situation that does not increase operating cost, saved investment.

Fig. 4 is the comparison diagram of the heat exchange property of the utility model and plain film, and abscissa is the Re number, and ordinate is a j factor number.This shows that in different speed, under the promptly different Re numbers, exchange capability of heat of the present utility model exceeds plain film 60%～100%.

Fig. 5 is the comparison diagram of the resistance performance of the utility model and plain film, and abscissa is the Re number, and ordinate is resistance coefficient f.This shows that in different speed, under the promptly different Re numbers, resistance ratios plain film of the present utility model exceeds about 40%.

Fig. 6 is at the comparison diagram that consumes the utility model and plain film exchange capability of heat under the different pump merits, abscissa fRe ³Having represented the pump merit that is consumed, is the NU number, and ordinate is the Nu number.In the scope of being investigated, under the same pump merit, exchange capability of heat of the present utility model exceeds plain film 55%～80%, has proved the superior of this kind slitted fin performance.

By above analysis as can be known: the ratio that the utility model heat exchange increases is much higher than the ratio that resistance increases, and uses heat exchanger of the present utility model can save 1/3 material.

Claims

1, a kind of enhanced heat exchange fin, comprise substrate [1] and be opened in the bridge shape silver [2] of the projection on the substrate [1], the bridge shape silver [2] of projection is made up of leg [3] that is connected with substrate [1] and rectangular top [4], it is characterized in that: the center with substrate [1] flow direction is the boundary, the spacing of each bridge shape silver [2] of the mobile upstream of air is greater than the spacing of each bridge shape silver [2] of air flow downstream, and promptly the sum of the bridge shape silver [2] of the mobile upstream of air is less than the sum of air flow downstream bridge shape silver [2].

2, enhanced heat exchange fin according to claim 1 is characterized in that: the height of said bridge shape silver [2] is for being sleeved on half of spacing of fin of heat exchanger tube [5].

3, enhanced heat exchange fin according to claim 1 is characterized in that: said bridge shape silver [2] is gone up alternatively up and down at substrate [1] and is offered.

4, enhanced heat exchange fin according to claim 1 is characterized in that: said symmetrical by the bridge shape silver [2] of the center line of heat exchanger tube [5] along air-flow direction.