US 1920800 A
Description (OCR text may contain errors)
J. W. M CAUSLAND Aug. 1, 1933.
HEAT EXCHANGER Filed Aug. 7, 1931 0mg w ATTORNEYS Patented Aug. 1, 19 33- PATENT? OFFICE 1,920,800 nnar EXCHANGEB John Woods McCausla-n to The Griscom-R ussell Comp 6, Chicago, Ill., asslgnor New York,
N. Y., a Corporation of Delaware Application August 7, 1931. Serial No. 555,700
This invention relates to heat exchangers and more particularly concerns an improved heat exchange device for use in transferring heat between two confined fluids.
In certain operations involving the compression or other treatment of fluids which result in the heating thereof, it is necessary or desirable to subsequently cool the fluids by heat exchange with a suitable cooling medium. Thus, in air 10 compressors, it is the usual practice to cool the compressed air leaving the pump or other compressing device, and when multi-stage compressors are employed, to cool the compressed air between successive compression stages. It is also desirable to cool inflammable gases and other fluids which are conveyed by pipe lines after such'fluids have been heated by compression in pipe line pumps or otherwise.
With the above and other considerations in mind, it is an object-of the present invention to provide an improved heat exchange device or cooler which is so constructed and arranged as to be extremely compact and highly eiiicient. More specifically, it is proposed to provide a heat exchanger of the type in which one of the fluids is carried in one or more tubes and to provide improved heat radiating projections or fins on the tubes, the fins being constructed to present a comparatively large heat dissipating or absorbing surface to the fluid surrounding the tubes while at the same time, occupying a comparatively small space.
In general, the above and other objects of the invention are carried out by providing a shell type heat exchanger having at least one and preferably a plurality of tubes passing therethrough and by providing improved heat transferring projections or fins on such tubes. At least some of the fins employed on each tube comprise flank portions fixed to the tube surface and extending outwardly therefrom and in addition, outer edge or lip portions extending at an angle to the flank portions along the outer edges of the flank portions. The fins preferably extend longitudinally 15 of the tubes and the bent lip portions of the fins may occupy part or all of the space between each adjacent pair of fins. With this arrangement, the over-all cross sectional dimensions of the finned tubes is materially reduced without reducing the surface area of the heat radiating projections thereon, and a larger number of such tubes can be accommodated in a shell of given cross sectional dimensions. Viewed in another way, the angularly disposed lip portions of the fins act to increase the total heat absorbing or dissipating surface exposed to the fluid surrounding the tubes without increasing the over-all dimensions of the finned tubes.
In accordance with one embodiment of the invention, the finned tubes are arranged to have a rectilinear cross sectional contour and when this arrangement is used, the several finned tubes making up the tube bundle of the heat exchanger may be very closely grouped and the space between adjacent flnned tubes through which the fluid surrounding the tubes may pass without intimate contact with the fins is reduced to a minimum.
The heat exchanger embodying the present in-' vention is preferably of the type in which the fluid surrounding the tubes passes longitudinally along the tubes within an elongated shell or other container. It is usually desirable to introduce and withdraw such fluid through ports in the shell which extend transversely with respect to the axes of the tubes. In order that the fluid passed through the shell may readily flow into and along the spaces between the longitudinally extending fins on the tubes, it is generally preferred to omit the fins from those portions of the tubes which are adjacent the transverse inlet or outlet ports of the shell, thereby providing transverse passages between the bare tubes for the flow of fluid between the ports and the spaces between the fins.
In describing the invention in detail, reference will be made to the accompanying drawing, in which;
Figure 1 is a sectional si changer embodying the inv Fig. 2 is a cross sectional changer of Fig. 1;
Fig. 2a is an enlarged partial sectional view of the fin construction employed in the embodiment of Fig. 2;
Fig. 3 is a sectional view similar to Fig. 2 showing a modified form of fin construction;
Fig. 3a is an enlarged partial sectional view of the fin construction employed in the modification of Fig. 3; and
de view of a heat exention;
view of the heat exand 6 are respectively cross sectional vidwssimilartong.3showin8twofurthermodifled forms of fin construction. Referring to the drawing, the heat exchanger therein shown to illustrate an embodiment of the invention comprises generally a container having a substantially cylindrical shell 4. A transverse inlet port is provided in the shell 4 adjacent one end thereof and a transverse outlet port 6 is disposed adjacent the other end of the shell, these ports being preferably located on opposite sides of the shellas shown. It should be understood that the shell may take various forms other than the cylindrical form shown, and that the inlet and outlet ports may in certain cases be both disposed adjacent the same end of the shell. A tube sheet 7 having a head 8 fixed thereon is fixed in fluid-tight engagement with one end of the shell 4 by suitable means such as the bolts 9. An inlet port 10 is provided in the head 8 to admit cooling liquid or other fluids to the outer surface of the tube sheet '7. A floating tube sheet 11 is preferably employed at the opposite end of the shell 4, this sheet being carried within the fixed head 12 by suitable means, such as a pipe 13, which is fixed to the sheet 11 through the bonnet 14. The pipe 13 extends through an opening 15in the head 12 and is slidably carried in fluid-tight engagement with this opening by means of a packed joint of any suitable construction, as shown at 16.
A plurality of substantially parallel spaced conduits or tubes 1'1 pass longitudinally through the shell 4, and the opposite ends of these tubes pass through and are connected in fluid-tight engagement with the tube sheets '7 and 11. Each tube 17 is provided with a plurality of heat transferring projections or fins F on the outer surface thereof. Although integral fins may be used, it
| is generally preferred to employ separate fins formed of a metal of high thermal conductivity such as copper or an alloy of copper and to anchor these fins to the outer surfaces of the tubes. The fins F extend longitudinally-of the tubes 17 and are preferably straight or substantially straight. In other words, the flank portion 18 of each fin F may lie in a plane passing through or parallelto the axis of its tube, or the fin F 'may be curved to form along pitch helix so that each fin is wrapped around its tube a few times in the length of the fin. In the appended claims, the statement that the fins extend longitudinally of the tubes means, as explained above, that the fins are either straight with their flank portions 18 lying in planes passing through or parallel to the tube axes, or these fins are slightly curved helically about the tubes.
In the form of the invention disclosed in Figs. 1, 2 and 2a, the fins F employed on the tubes 17 comprise flank portions 18 having their inner edges anchored to or formed integrally with the tubes 1'1 and outer edge portions or lips 19 disposed at a substantial angle to the flank portions 18. The lips 19 of the several fins on each tube may occupy a portion only of the space between adjacent fins, as shown in Fig. 2, or the lip 19' may extend entirely across the space between adjacent fins and come into contact with the flank portion 18 of the adjacent fin, as shown in Figs. 3 and 3a.
It is not essential to the invention that every fln on each tube be provided with a bent lip at its outer end. Thus, for example, in the forms of the invention shown in Figs. 4 and 5, the fins are proportioned and arranged in such a manner astoformfinnedtubeshavingrectilinear cross sectional contours and the fins 20 and 21, the outer ends of which terminate at the points of juncture of the rectilinear portions'of the finned structure contour, are not provided with lips. The fin construction shown in Fig. 4 is arranged to provide finned tubes of square cross section and a plurality of fins having flank portions 22 and lip portions 23 disposed at an angle to the flank portions is dispomd between each pair of straight fins 20. The finned structure employed in the embodiment of Fig. 5 is arranged to provide finned-tubes of helical contour and this is accomplished by using six equally spaced straight edged fins 21 and by mounting between each pair of straight edged fins a plurality of fins having flank portions 24 and lips 25 disposed at an angle to the flank portions.
The finned tubes of rectilinear cross sectional contour are particularly useful in forming compact tube bundles. Thus, as shown in Figs. 4 and 5, finned tubes of this type may be com- .pactly grouped within heat exchanger shells 26 and 27 and when so arranged, the tubes and their fins occupy a large proportion of the crow section of the shells. With the compact tube bundle arrangement of the modifications of the invention shown in Figs. 4 and 5, the clearance between the fins of adjacent tubes is extremely small, and accordingly, the by-passing of fluid between the tubesis reduced to a minimum.
If desired, the exchanger shell may be of rectilinear section in order that the shell walls may lie very close to the outer ends of the tube fins, and by-pass spaces between the tube fins and the shell may be practically eliminated. Thus as shown in Fig. 4, the shell 26 is of substantially square section, the four shell walls lying very close to the outer ends of the fins comprising the square finned tube bundle.
If desired, the lip portions 19, 19', 23 and 25 may be curved outwardly or inwardly, or may be corrugated to increase the heat-transferring surface area thereof.
'It is preferred to so arrange the fins on their tubes that the portions of the tubes disposed in the paths of the fluid entering and leaving the container shell are bare. This arrangement is clearly shown in Fig. 1, wherein the fins F extend between the inlet and outlet ports 5 and 6 of the shell 4 and terminate just short of these ports. With this arrangement, the bare end portions of the tubes are disposed in the path of the fluid entering and leaving the shell 4 through the transverse ports 5 and 6, and accordingly, the fins F do not obstruct or retard the flow of fluid into or out of the container.
Although various fluids may be passed through the tubes 1'1 and the shell 4, it is generally preferred to pass a hot gaseous fluid, such as compressed'air, illuminating gas, etc., throughthe shell and to cool this gas by passing a liquid cooling medium, such as refrigerated water or some other cooled liquid, through the tubes 1'1.
The finned tube construction of the present invention is adapted for use in various heat exchangers other than the particular device disclosed. Thus, for example, the finned, tubes of the present invention may be employed in exchangers having a single tube sheet in which both ends of each tube are secured, the tubes being bent to substantially U-shape. When employed in heat exchangers of this type, my improved fins extend along the straight portions of the t w the bent po oi the tubes being leit here oi fins.
prising a plurality of tubes and e plurality of dricel container having inlet and outlet ports in the cylindrical wall thereof, a plurality of spaced tubes extending longitudinally through said container and a plurality of radial fins on each of said tubes, said fins exten he: longitudinally of mid container terminating at points more remote from the ends of said eonteiner than said ports, at least some of said fins hevlnu r portions with lip portions extending et an angle to the iv =11 portions from the outer edges of the portions, said finned tubes each having e rectilinear cross sectional contour whereby the finned tubes may he nested in close proximity to each other with a :rit u um 01 space for the hy-passing oi fluid therebetween.
I JO WOODS MGCAU net