DK151357B

DK151357B - HEAT EXCHANGE

Info

Publication number: DK151357B
Application number: DK516682A
Authority: DK
Inventors: Gert Aake Elof Aakerman
Original assignee: Wirsbo Bruks Ab
Priority date: 1981-03-20
Filing date: 1982-11-19
Publication date: 1987-11-23
Also published as: DK151357C; DE3262274D1; EP0074384B1; FI74806C; FI823977A0; FI823977L; EP0074384A1; FI74806B; WO1982003270A1; SE445138B; DK516682A; SE8101808L; JPS58500378A

Description

i 151357in 151357

Opfindelsen angår en varmeveksler til overføring af varme mellem to medier, hvilken varmeveksler omfatter en rørformet kappe og et i denne anbragt rør, som på ydersiden er forsynet med ribber, hvilke ribber er i hovedsagen vinkel-5 rette på rørets længderetning. Det ene medium passerer gennem kappen uden for ribberøret, og det andet medium passerer gennem ribberøret. Varmeveksleren er beregnet til at kunne bruges til kondensering af damp, f.eks. i forbindelse med varmepumper og lignende indretninger,hvor damp passerer 10 gennem kappen uden for et ribberør, og et kølemedium passerer gennem ribberøret.BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a heat exchanger for transferring heat between two media, the heat exchanger comprising a tubular sheath and a tube disposed therein which is provided on the outside with ribs which are generally perpendicular to the longitudinal direction of the tube. One medium passes through the sheath outside the rib tube and the other medium passes through the rib tube. The heat exchanger is intended to be used for condensing steam, e.g. in connection with heat pumps and similar devices, where steam passes through the casing outside a rib tube and a refrigerant passes through the rib tube.

Det er kendt at anvende ribberør til varmevekslere med henblik på at tilvejebringe overføring af varme mellem to strømmende medier, se f.eks. fransk patentskrift nr. 2 083 547.It is known to use rib pipes for heat exchangers in order to provide heat transfer between two flowing media, see e.g. French Patent Specification No. 2 083 547.

15 Ribberørene er fordelagtige ved, at de har store varmeoverfø-rende flader. Selv om disse kendte varmevekslere kan anvendes til at kondensere damp, har de i dette tilfælde den ulempe, at kondensatet har tilbøjelighed til at blive tilbage på ribbernes flader, hvilket mindsker varmevekslerens effektivi-20 tet og medfører et langsommere kondenseringsforløb.The rib pipes are advantageous in that they have large heat transferring surfaces. Although these known heat exchangers can be used to condense steam, in this case they have the disadvantage that the condensate tends to remain on the surfaces of the ribs, which reduces the efficiency of the heat exchanger and results in a slower condensation process.

Det er formålet med opfindelsen at anvise en varmeveksler af den ovenfor nævnte art, som udnytter de fordele, der ligger i, at ribberørene har store varmeoverførende flader, men eliminerer eller i det mindste formindsker kondensatets tilbøjelig-25 hed til at blive tilbage på disse rørs flader.SUMMARY OF THE INVENTION It is an object of the invention to provide a heat exchanger of the kind mentioned above which takes advantage of the advantages of the ribs having large heat transferring surfaces but eliminating or at least reducing the tendency of the condensate to remain on these tubes. surfaces.

Dette formål opnås ifølge opfindelsen ved de kendetegn, som er angivet i patentkravene.This object is achieved according to the invention by the features set forth in the claims.

Ved at kappen er delt i to rum, som befinder sig på hver sin side af ribberøret, kan det ene medium bringes til at passere 30 mellem ribberne på ribberøret i god varmeoverførende kontakt med disse, så at der opnås en god varmeveksling mellem det me- 2 151357 medium, som passerer gennem kappen uden for ribberøret, og det medium, som passerer inden i ribberøret.By dividing the sheath into two compartments located on one side of the rib tube, one medium can be passed between the ribs of the rib tube in good heat transferring contact with them so as to obtain a good heat exchange between the ribs. 2 media which passes through the casing outside the rib tube and the medium which passes inside the rib tube.

Hvis rørets ribber ligger an imod to modstående vægge i kappen, opnås en god varmeledende forbindelse mellem ribberøret og kap-2 pen, så at også kappen fungerer som varmeoverføringsflade, hvilket yderligere forbedrer varmevekslingen mellem de to gennem varmeveksleren passerende medier.If the ribs of the pipe abut against two opposing walls of the casing, a good heat-conducting connection is obtained between the ribs and the casing, so that the casing also acts as a heat transfer surface, which further improves the heat exchange between the two media passing through the heat exchanger.

Ved at anbringe ribberøret på skrå i kappen, så at det forholds-vis store rum uden for ribberøret nær ved kappens indløbsende svarer til det første af de to rum, og det forholdsvis store rum ved kappens udløbsende svarer til det andet af de to rum, er det muligt at gøre indløb og udløb forholdsvis store, selv hvis kappen har forholdsvis små tværdimensioner. Herved kan for-^5 holdsvis store mængder af det første medium indføres i kappen, hvorved store varmemængder kan overføres mellem de to medier.By disposing the rib tube obliquely in the casing so that the relatively large space outside the rib tube near the inlet end of the casing corresponds to the first of the two compartments and the relatively large compartment at the outlet end of the casing corresponds to the second of the two compartments. it is possible to make inlet and outlet relatively large, even if the jacket has relatively small cross-dimensions. Hereby, relatively large quantities of the first medium can be introduced into the jacket, whereby large quantities of heat can be transferred between the two media.

Når varmeveksleren bruges til kondensering af damp, idet dampen tilføres til kappen, og et koldt medium, f.eks. kold væske, ledes 20 ind i ribberøret, vil den damp, som strømmer ind mellem ribberne fjerne (medrive) kondensat fra ribbernes overflade, så at der ikke bliver noget kondensat tilbage på ribberne. Desuden vil yderligere dannelse af kondensat på ribberne hindres. Denne effekt er særlig tydelig, såfremt det første rum, d.v.s. indløbsrummet, i kappen 25 placeres oven over det andet rum, d.v.s. udløbsrummet.When the heat exchanger is used for the condensation of steam, the steam being supplied to the jacket, and a cold medium, e.g. cold liquid, conducted into the rib tube, the steam flowing between the ribs will remove (entrain) condensate from the ribs surface so that no condensate remains on the ribs. Furthermore, further formation of condensate on the ribs will be prevented. This effect is particularly evident if the first compartment, i.e. the inlet compartment, in the casing 25, is placed above the second compartment, i.e. outlet space.

Såfremt kappen udformes som en opretstående skruelinie med stor stigning, kan man opnå, at kondensatet samles i skrueliniens nedre del og dér omstrømmer ribberøret, så at der sker en underkøling 30 af kondensatet.If the casing is formed as an upright screw line with a large pitch, the condensate can be obtained in the lower part of the helix and there flowed the rib tube so that a subcooling 30 of the condensate occurs.

Opfindelsen forklares neden for under henvisning til tegningen, hvor ^ fig. 1 viser en varmeveksler bestående af et rør, som er omsluttet af en lige kappe - set fra siden, fig 2 samme - set i et tværsnit efter linien II-II i fig. 1, og 3 151357 fig. 3 en anden udførelsesfonn for varmeveksleren ifølge opfindelsen, som er bygget efter samme princip som ifølge fig.l og 2,idet dog kappen er viklet til skruelinieform.The invention is explained below with reference to the drawing, in which: FIG. 1 shows a heat exchanger consisting of a pipe enclosed by a straight casing - viewed from the side, FIG. 2 the same - seen in a cross-section along the line II-II in FIG. 1 and 3 FIGS. 3 shows another embodiment of the heat exchanger according to the invention, which is built on the same principle as in FIGS. 1 and 2, however, the casing is wound into helical form.

Den i fig. 1 viste varmeveksler består af en rørformet ydre 5 kappe 10, som har i hovedsagen oval tværsnitsform, således som det også fremgår af fig. 2. I kappen 10 er der monteret et ribberør 11. Ribberne 12 på dette rør udgøres af ringformede plader, som er anbragt i hovedsagen vinkelret på ribberørets længderetning. Ribberne på rør af denne type 10 tilvejebringes sædvanligvis ved valsning og vulstfoldning af tykvæggede rør, så at ribberne bliver en integrerende del af røret. Alternativt kan ribberne forløbe efter en skruelinie uden på røret i hele dettes længde. Ribberøret 11 er monteret således, at dets ribber 12 ligger an mod to modstå-15 ende vægge i kappen 10, således som det fremgår af fig. 2.The FIG. 1 is a tubular outer casing 10 having generally oval cross-sectional shape, as is also apparent from FIG. 2. In the casing 10 is mounted a rib tube 11. The ribs 12 on this tube are formed by annular plates which are arranged generally perpendicular to the longitudinal direction of the rib tube. The ribs of tubes of this type 10 are usually provided by rolling and beading of thick-walled tubes so that the ribs become an integral part of the tube. Alternatively, the ribs may extend along a screw line outside the tube throughout its length. The rib tube 11 is mounted such that its ribs 12 abut against two opposing walls of the casing 10, as shown in FIG. 2nd

Ved dette anlæg tilvejebringes der god varmeledende forbindelse mellem ribberøret 11 og kappen 10, så at også kappens indre flade danner en varmeoverføringsflade, via hvilken der kan ske en varmeoverføring mellem de to gennem kappen og ribbe-20 røret passerende medier. Idet kappen har større tværsnitsareal end ribberøret, deler ribberøret 11 kappen i to rum 13, 14, som hver for sig strækker sig fra kappens ene ende til kappens modsatte ende. Som det ses, strækker disse rum sig på hver sin side af ribberøret, så at det medium, som løber 25 ind i det ene rum 13, må passere ind mellem rørets ribber 12 for at komme ind i det andet rum 14. I den i fig. 1 og 2 viste udførelsesform er kappen 10 et lige rør, hvori der er indlagt et ligeledes lige ribberør 11. Ribberøret 11 er anbragt på skrå i kappen. Det forholdsvis store rum uden for ribbe-30 røret nær ved kappens indløbsende svarer til det første rum 13, medens det forholdsvis store rum ved kappens udløbsende svarer til det andet rum 14. Herved kan de to rum lettere forsynes med en indløbsrørledning 15 henholdsvis udløbsrør-lednihg 16, hvortil kommer, at rørledningerne let kan gøres 4 151357 forholdsvis tykke, også selv om kappen har små tværdimensioner. Også ribberøret 11 er forsynet med en indløbsrørledning 17 og en udløbsrørledning 18 for det gennem ribberøret passerende medium. Indløbet og udløbet er dog i dette tilfælde ombytte-5 de i forhold til, hvad der gælder for indløb og udløb for kappen, således at de to medier kommer til at strømme i modstrøm gennem varmeveksleren. Strømningsretningerne for medierne er angivet ved pile i fig. 1.This system provides good heat conducting connection between the rib tube 11 and the casing 10, so that the inner surface of the casing also forms a heat transfer surface, through which a heat transfer between the two through the casing and the rib tube 20 can take place. As the sheath has greater cross-sectional area than the rib tube, the rib tube 11 divides the shell into two compartments 13, 14, each extending from one end of the sheath to the opposite end of the sheath. As can be seen, these compartments extend on either side of the rib tube so that the medium running 25 into one compartment 13 must pass between the ribs 12 of the tube to enter the other compartment 14. FIG. 1 and 2, the sheath 10 is a straight tube in which an equally straight sheath tube 11 is inserted. The sheath tube 11 is disposed obliquely in the sheath. The relatively large space outside the rib tube near the inlet end of the sheath corresponds to the first compartment 13, while the relatively large space at the outlet end of the sheath corresponds to the second compartment 14. Hereby the two compartments can be more easily provided with an inlet pipe 15 and outlet pipe respectively. line 16, in addition to which the pipelines can easily be made relatively thick, even if the sheath has small cross-dimensions. Also the rib tube 11 is provided with an inlet duct 17 and an outlet duct 18 for the medium passing through the rib tube. However, the inlet and outlet are in this case interchangeable with respect to what applies to the inlet and outlet of the jacket, so that the two media flow countercurrently through the heat exchanger. The flow directions of the media are indicated by arrows in FIG. First

Varmeveksleren ifølge opfindelsen kan anvendes til kondensering 10 af damp. I så fald er kappen fortrinsvis formet som en opretstående skruelinie (eventuelt spiral) med stor stigning. En sådan udførelsesform ses i fig. 3, hvor de anvendte henvisningstal svarer til de i fig. 1 anvendte. Også i denne udførelsesform er ribberøret 11 anbragt på skrå indvendigt i kappen 10, 15 så at ribberørets tilslutningsledning 17 Ved kappens udløbsende ligger i kappens øvre del, og tilslutningsledningen 18 ved kappens indløbsende ligger i kappens nedre del. Herved kommer det første rum 13 i kappen til at ligge oven over det andet rum 14. Dette er specielt hensigtsmæssigt ved kondense-20 ring, eftersom den gennem kappen passerende damp da effektivt bidrager til medrivning af kondensatet fra ribbernes overflade.The heat exchanger according to the invention can be used for condensation of steam. In this case, the sheath is preferably shaped as an upright helical (possibly spiral) helical line. Such an embodiment can be seen in FIG. 3, where the reference numerals used are similar to those in FIG. 1 used. Also in this embodiment, the rib tube 11 is inclined internally in the casing 10, 15 so that the rib pipe connection 17 at the outlet end of the casing lies in the upper portion of the casing and the connection line 18 at the inlet end of the casing lies in the lower portion of the casing. Hereby, the first compartment 13 of the casing will lie above the second compartment 14. This is particularly useful in condensation, since the steam passing through the casing then effectively contributes to entraining the condensate from the surface of the ribs.

I dette tilfælde vil dampen nemlig strømme frem mellem ribberne i i hovedsagen samme retning som kondensatet skal løbe, nemlig nedad. Da kappen 10 har form som en opretstående skrue linie 25 (spiral) med stor stigning, vil kondensatet samle sig ved skrueliniens nedre del. I dette tilfælde vil en forholdsvis lille mængde kondensat være tilstrækkelig til at sikre, at ribberøret omskylles af kondensat. Derved sikres, at kondensatet underkøles, d.v.s. at dets temperatur kan sænkes til under den tem-30 peratur, ved hvilken kondenseringen sker, idet yderligere afkøling tilvejebringes ved hjælp af mediet i ribberøret. Ved' skrueliniens nedre ende findes et udløb 19 til aftapning af kondensat.In this case, the steam will flow between the ribs in substantially the same direction as the condensate must flow, namely downwards. Since the casing 10 is in the form of an upright screw line 25 (spiral) with a large pitch, the condensate will collect at the lower part of the helix. In this case, a relatively small amount of condensate will be sufficient to ensure that the rib tube is flushed by condensate. This ensures that the condensate is undercooled, i.e. that its temperature may be lowered to below the temperature at which the condensation occurs, further cooling being provided by the medium in the rib tube. At the lower end of the helical line there is an outlet 19 for draining condensate.

Claims

Although only two embodiments of the heat exchanger according to the invention have been shown and described, there is nothing in the way of using other embodiments. Thus, the sheath need not have an oval or oblong cross-section, but the cross-section may be round, in which case sealing means must be arranged between the rib tube and the walls of the sheath so that two separate spaces are formed in the sheath, which are only interconnected through one another. the spaces between the ribs of the tube. Such sealing means may also be used when the sheath has an oval or oblong cross section. The rib tube need not extend obliquely through the sheath, but may alternatively extend along the central axis of the sheath, in which case, however, the sheath may be closed at the ends by special walls. In the embodiments shown in the drawing, the end of the casing at the ends can be provided by deformation of the casing so that it abuts against the inlet and outlet pipelines, with complete sealing being provided by e.g. soldering. When the sheath is wound into helical shape, the longitudinal cross-section of the sheath may preferably have its major axis lying parallel to the axis of the helix because it makes it easier to wrap the helical line so that it has a small diameter. It is important that the lower wall surface of the sheath has a shape that at least differs somewhat from the shape of the ribs, so that condensate can run through the sheath throughout its length. The heat exchanger can also advantageously be used for evaporation if a hot medium is passed through the rib tube. Claims. 30 ---------------------

A heat exchanger for transferring heat between two media for the purpose of condensing steam, said heat exchanger 35 comprising a tubular sheath (10) and a tube (11) disposed therein, which is provided on the outside with ribs (12) which generally perpendicular to the longitudinal direction of the tube, and where the cross-sectional area of the sheath is greater than the area defined by the outer circumference of the individual rib (12), and in addition the first medium available in vapor form can pass through the sheath. outside the rib tube, and the second medi-2 µm, which is a refrigerant, can pass through the rib tube, characterized in that the sheath (10) is divided into two compartments (13, 14), which are located on either side of the rib tube ( 11) and that the first compartment (13) is positioned above the second compartment (14) so that the vapor passing through the casing (10) outside the rib tube (11) first enters the first compartment (11). compartment (13) and thence passes downwardly between the ribs (12) of the pipe (11) and then into the second compartment (14).

Heat exchanger according to claim 1, characterized in that the casing (10) has an elongated cross-sectional area and that the ribs (12) of the pipe (11) abut two opposite walls of the casing.

Heat exchanger according to claim 1 or 2, characterized in that the sheath (10) has an inlet (15) at one end and 2Q an outlet (16) at the other end for the first medium, and that the rib tube (11) is the inlet end of the sheath (10) is mounted in the lower half of the sheath and near the outlet end of the sheath is mounted in the upper half of the sheath, and the relatively large space outside the rib tube near the inlet end 25 of the sheath corresponds to said first space (13), and the relatively larger space at the outlet end of the sheath corresponds to said second space (14).

Heat exchanger according to claim 3, characterized in that the casing (10) is wound so as to follow an upright helical (cylindrical spiral) helical line.

Heat exchanger according to claim 4, characterized in that the cross-sectional area of the sheath (10) has its large axis lying parallel to the axis of the helical line. 151357

Heat exchanger according to claim 4 or 5, characterized in that the inlet (15) for the first medium is arranged in the upper part of the screw line and that an inlet (17) is arranged so that cold liquid can be passed through it. the rib tube (11) in the lower part of the helical line containing means (19) for draining the condensate.

Heat exchanger according to claim 6, characterized in that the lower wall surface of the casing (10) has a shape which at least differs somewhat from the shape of the ribs (12), so that the condensate can run within the casing throughout its length.

Heat exchanger according to claim 1, characterized in that each of the compartments (13, 14) extends from one end of the sheath (10) to the opposite end of the sheath.