US2400737A - Finned tube - Google Patents

Description

May 21, 1946. J, w. BROWN, JR 2,400,737

FINNED TUBE Filed July 14, 1942 2 Sheets-Sheet l INVILNI OR. J'OHN WBPOWNJE.

BY x

44 TTQPNFYS May 21, 1946.

J. w. BROWN, JR 2,400,737

FINNED TUBE Filed July 14, 1942 2 Sheets-Sheet 2 I, s T 3043 34 INVENTOR. o/wv W-BEOW/V, we.

A 770 PNEYS Patented May 21, 1946 FINNED TUBE.

John W. Brown, Jr., Lakewood, Ohio, assignor to Brown Fintube Company, Elyria, Qhio, a corporation of Ohio Application July 14, 1942, Serial No. 450,841

1 Claim. (Cl. 257-262) This invention relates to finned tubesand more particularly to finned tubes adapted for use in heat exchangers where the flow of fiuid on the exterior of the tubes is transversely of theaxis of the tubes. For example, finned tubes made according to the present invention are suitable for use in radiators for autoinobileatrucks; tractors and the like.

In my prior patents, Nos. 2,261,136 and 2,261,137 both issued November 4, 1941, I disclose finned tubeswherein fin members are welded longitudinally to the exterior of .the tubes. These patents specifically disclose continuous channel section fin members wherein the members are welded to the tube's in a manner to provide adequate paths for the flow of heat from the flanges to the tubes. According to the present invention, I provide fin members having continuous base portions secured to a tube and extending preferably longitudinally thereof. The fin members are formed with fin portions projecting from the base portions and preferably formed integrally therewith. The fin portions are bent or twisted so as to lie in planes extending substantially at right angles to the axis of -the base portions and the tube, thus adapting the fins for transverse flow of fluid on the exmethod described and claimed in my copending application Serial No. 388,835, filed April 16, 1941,

now Patent No. 2,298,250.

A general object of my present invention is to provide a finned tube particularly adapted for transverse flow of fiuid on the exterior thereofand which can be manufactured economically scription of prefer :ed forms thereof, reference being made to the accompanying drawings in which Figure 1 is a' perspective illustrating one form of finned tube made according to my invention; Figure 2 is a side elevation of the tube shown in Figure 1; Figure 3is a perspective showing a modified type of finned tube Figure 4 is a side elevation of the tube shown in Figure 3; Figure 5 is an elevation showing a section of a heat exchanger made up of a plurality of tubes shown in Figures 3 and 4; Figure 6 is a fragmentary section through the heat exchanger of Figure 5; Figure 7 is aperspective showing a further modification of my invention; Figures 8 and 9 are views of. the fin members employed in the modification shown in Figure '7 before they are welded to the tube; and Figure 10 is a transverse section through a heat exchanger embodying a plurality of tubes may'comprise a tube T having a plurality of fin members indicated generally at l0, welded there to. Each of the fin members l0 consists of a base portion ll preferably welded to the tube T by a which are preferably at right angles to the axis of and rapidly from inexpensive materials such as steel. Another object is to provide a finned tube having one or more fin members extending generally longitudinally thereof, with fins extending therefrom. and lying in planes substantially norpaths are provided for the flow of heat between the fins and the tube. A further object is to provide such a finned tube in which large radiatin: surfaces can be provided in a compact space.

Another object is to provide finned tubes which can be arranged compactly to provide a heat exchanger having a large radiating surface.

Further objects and advantages of my inventhe tube.

It will be noted that the fins are shaped so that each complete fin member can be formed from strip stock by slitting the stock inwardly from both edges toward the centerbase portion to form the separate fins l3 and then bending or twisting the fins adjacent their juncture with the base portion II, as indicated at it, into planes at right angles to their original plane and also at right angles to the longitudinal axis of the base portion. This operation can be carried out in a punch press, and preferably the forming operation in the modification shown in Figures 1 and 2 is carried out before the fin members are welded to the tube. The bending'of the fin members is preferably carried out so that the space left between oppositely disposed fins extending-from each baseportion is wide enough to receive a welding electrode so that the welding operation can be carried out tion will become apparent from the following dein accordance with the disclosure of my application aforesaid. In the present instance the tube is shown as having four fin members In secured thereto. However, a greater or lesser number may be employed depending upon the service i or which the tube is intended.

The structure just described provides a very efficient heat exchange element, for none of the metal is wasted and an adequate path is provided for the fiow of heat between the fins through the base and into the tube. The fins l3 are full width throughout, 'and the J'unctures between the fins and the base members H are preferably of the same width as the fins themselves. Thus heat can flow between the fins and the base member a rapidly as it can fiow along the fins themselves for the crosssectional area of the junctures is as great as the maximum crosssectional area of the fins in any plane normal to the direction of flow of heat between fins and case. Further, the. welding operation carried as described in my aforesaid patent provides a path between the base and the tube which as great in total cross-sectional area as the ath between the fins and the base. Thus an efiicieut structure is provided in which full advantage can be taken of the heat transferring ability of the fins.

The structure offers low resistance to the fiow of commodities on the exterior thereof because of the fact that the fins present only their edges in the direction of fiow. The fins as well as the tube may be made of various thicknesses and materials. Because of the large fin areas obtainable and because of the efiiciency of the structure, finned tubes made of light gauge steel have sufiicient heat transferring capacity to enable them to be used in cooling radiators for internal combustion engines. This may be accomplished, for example, by connecting a plurality of tubes arranged parallel to each other into suitable headers at their ends.

A type of tube especially adapted for service in such radiators is shown in Figures 3 and 4. Here the tube T has two fin members indicated generally at [5 welded thereto. Each of these fin members comprises a base portion l6 and a plurality of fins ll, the fins being formed integrally with the base portions and the base portions preferably being welded to the tube in accordance with my aforesaid patents and application as indicated diagrammatically at lB. In this modification, however, the fins ll instead of extending radially outwardly as in the previous modification, project outwardly in such manner that the edges l9 and 20 of each of the fins are preferably parallel to each other. Also the fins are bent in such manner that the edges l9 lie in substantially the plane of the base portions l8 so that the Over-all dimension of the finned tube between the edges is of opposite fins is substantially the same as the diameter of the tube plus the thickness of the base portions.

This arrangement makes it possible to provide a compact heat exchanger wherein the ends of fins on adjacent tubes can abut each other-as indicated at 2! in Figures 5 and 6 and the edges is of the fin of adjacent tubes can engage each other as indicated at 22 in Figure 6. Thus an assembly of the tubes such as shown in Figures 5 and 6 provides a heat exchanger having an extensive finned area in very compact form and in such form that the resistance to flow of air or other fiuid through the exchanger is kept at a minimum. The exchanger shown in Figures 5 and 6 may be completed by using any convenlent type of header or any other convenient connection (not shown). I

In Figures '1 to 10, inclusive, I have illustrated a iurther modification of my invention wherein the tube T" has finned members indicated generally at 30 and 3| welded thereto. This modification is quite similar to the form shown in Figures 3 to 6 except that each tube has four finned members instead of two, thus giving a greater surface of fin. Here the members 30 comprise, as shown in Figure 7 and 8, base portions 31 and integrally formed fin 33, The fins are formed preferably by slitting a strip from its edges toward the center as shown in the lower part of Figure 8, and then twisting the resultant fins as indicated in the upper part of Figure 8 so that the main body of each fin lies on the side of the base portion away from the tube. The base portions 32 are welded to the tube is beforev the welded-areas being indicated maticaliy at N. Thi produces a corral-nu which the edges 34 and. 35 of the fins are parallel to each other.

The fin members 3! are disposed between the fin members 36 and consist of portions 38 from which the fins 37 extend. As illustrated in Figures 7 and 9, these fin members are generally similar to the fin members Iii shown in Figure 1 except that the bending operation is carried out so that the edges 38 and 39 of the several fins are parallel to each other. When welded to the tube by the welds 43, the outer edges 38 of the fins 31 contact the inner edges 35 of the fins 33. Preferably the fins 31 are shorter than the fins 33 so that the ends 41 and 42 of the fins 33 and 31, respectively, terminate in this same line. This arrangement makes it possible to assemble a plurality of tubes into a compact arrangement as shown in Figure 10 with the ends of fins of adia- -cent tubes in contact with each other as at 43,

and the outer edges 34 of fins on adjacent tubes contact each other as at 44. In elevation a heat exchanger as shown in Figure 10 appears generally similar to that shown in Figure 5, and as in the previous case, the heat exchanger may be.

completed by providing suitable headers for the several tubes.

From the foregoing description of preferred forms of my invention it will be seen that my finned tubes are particularly adapted for transverse fiow of fiuid on the exterior thereof and provide an extensive area for heat transfer with relative low resistance to fiow. My invention contemplates various arrangements and shapes of fins, and finne'd tubes made according thereto can be incorporated into heat exchangers of different types. Because of the construction wherein a plurality of fins are formed integrally with an elongated base portion, finned tubing can be made according to my invention rapidly and. at relatively low cost. The structure is such that adequate paths are provided for the flow of heat from the several fins into the base of the fin members and to the tube, thus insuring a, tube which is highly efllclent from the heat exchange standpoint.

Those skilled in the art will appreciate that various changes and modifications in my inven tion may be made without departing from the spirit and scope thereof. Accordingly it is to be understood that my patent is not to be limited to the preferred forms described herein, or in any manner other than by the scope of the appended claim.

I claim:

A heat exchange element comprising a tube having a pair of longitudinally extending finned members welded thereto, each finned member comprising an elongated base portion weldedvtc a tube and two rows of spaced fins integral with the base portion and the fins having substantially plane portions lying in planes parallel to each other and normal to the axis of the tube, the longitudinal edges of the fins-in each row being parallel to each other, and lying in planes par-.

allel to and spaced from the planes of the longitudinal edges of the flnsin the other rows.

JOHN W. BROWN, JR.

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