US2308319A - Heat exchange surface - Google Patents

Description

Jan. 12, 1943 M. J. STANTON HEATEXCHANGE SURFACE Filed Nov. 25, 1939 lrwventpr: My es J. Scarwton,

HI S Attorney.

Patented Jan. 12, 1943 2,308,319 near EXCGE suaracn Myles J. Stanton, Bloomfield, N. 3., assignor to General Electric Company; a corporation of New York Application November 25, 1939, Serial No. 306,089

4 Claims. (01. 29-1573) My invention relates to heat exchange surfaces.

Objects and advantages of my invention will become apparent as the following description proceeds, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed toand forming a part of this specification.

For a better understanding of my inventon, reference may be had to the accompanying drawing inwhich Fig. 1 is a view showing a fluid conveying conduit equipped with a heat exchange surface formed according to my invention;,Fig. 2 is-a view of one of the heat exchange members shown in Fig. 1; Fig. 3 is an enlarged detail view of a part used in the assembly of the heat exchanger shown in Fig. *1; Fig. 4 is an enlarged perspective view of a portion of the heat exchange element illustrating the method of assembly; Fig.5 is a view of a modification of the arrangement illustrated in Figs. 1 to 4'; and Fig. 6 illustrates another embodiment of the invention.

I have provided a heat exchanger or body to or from which heat is to be transferred such as a fluid conducting member ID having heat transfer members II. The heat transfer members H are fastened to the member ID as by means of a base member or securing strip l2, the edges thereof being rolled over the securing or anchoring portions l3 of the'heat transfer or fin members H, the assembly being soldered or otherwise suitably secured to the fluid conducting member l0.

A large portion of the temperature drop from the temperature of a fin surface to the temperature of the fluid flowing in contact with the fin surface occurs in the region immediately adjacent the fin, this region often being called the boundary'layer. The thickness of this layer is a function of the distance from the leading edge of the fin in the direction of 'fluid flow. The heat flow in this region decreases as the thickness of the boundary layer increasesr For high rates of heat exchange it is desirable to keep the boundary layer thin and to mix frequently the boundary layer and the main body of fluid. This may be accomplished by providing a plurality of spaced-apart fins of relatively small perimeter or cross section at various angles to the air flow and arranged to present as many edges as possible to mix or divide the flow of fluid into alarge number of thin strata, The accomplishmentof these purposes is described hereinafter.

I have illustrated a suitable type of fin, best shown in Fig. 2, having an inverted substantially U-shape. The fin II is provided with a. heat transferring portion [4. The free ends of the fin II are formed into anchoring portions Ilin any suitable manner as loops, for example. The fln' H as illustrated in the drawing may be formed of wire, the anchoring portions l3 being illustrated in the form of eyelets. A fin such as that illustrated in the drawing may be suitably formed in an automatic wire, bending machine. Any suitable material may be used for the fin H, copper being particularly suitable for it is easily fastened to a heat exchange body 10 such as a tube as by soldering and is a relatively good heat conductor.

In order to secure the fins H to a heat exchange member such as the conduit I0, I have provided strips II of suitable material, such as copper for example. The strips I2 are provided with longitudinally spaced openings l5, illustrated as transverse substantially parallel slits, for purposes to be described, the slits or openings l8 being disposed so as to leave a margin around the edges of the strip l2. As shown in Fig. 4, the edges of the strip l2 are suitably bent, as by a rolling process in an automatic machine, into engagement with the eyelet or anchoring portion".

Thus, in assembling the heat exchanger according to my invention, a plurality of fins or heat transfer members II are arranged in spaced-apart substantially parallel positions as by means of a suitable fixture having slots therein to receive and support fins H in the desired positions. The slotted strip I2 is then placed in engagement with the anchoring portions l3. Next, the edges of the strip 12 are shaped as by rolling or bending around the anchoring portions l3 in order to secure the fins l I to the base member or strip l2. A strip of solder i6 is placed transversely of the slits l5 and extending through the aligned fins l l adjacent the anchoring portions 13 thereof.

The above described assembly'may be formed of any length and wound on reels, if desired. The assembly may be placed on a heat exchange member, such as the-tube III, in any suitable arrangement, as a helically wound one, at any suitable pitch, as illustrated in Fig. 1. At this stage, the assembly is heated until the solder l6 melts, and runs through the slits l5 thereby soldering the base member or strip l2 tothe heat exchange member ID.

In Fig. 5 I have illustrated a modification of the above-described invention in which strips H are rolled at the edges thereof before the flns ll are applied. The fins ll may be: formed as above and slid along the troughs formed at either edge of the strip ll. It will'be seen that the finished product will be similar to that illustrated in Figs.

' l to 4, inclusive, although it may be desirable to ments ll illustrated in Figs. 1 to 5, inclusive. Instead of using a strip l2 to assist in assembling the heat exchanger and to help maintain the members II in intimate thermal association with the body It to which or from which heat is to be transferred, I provide wires l8 which, during assembly, are associated with the anchoring porti ons iii of the elements ll. invention illustrated in Fig. 6, the elements II are preferably arranged with portions IS in the form of eyelets or loops in alignment, as by means of a suitable slotted fixture, and wires i8 passed through-the loops. The assembly is' then deposited on the surface of the body Ill, a strip of solder I 6 passed between the ends of the members II adjacent the body Ill and securing portions l3 and the assembly heated until the solder flows into engagement with portions l3, wires l8 and body Ill. The portions l3 may be of any suitable design, and if the eyelet form is chosen, the wire defining the eyelet or loop may be pressed into engagement with wires l8, and thereby hold the assembled members II in the desired spaced-apart relationship following which the assembly may be soldered to the. body i.

While I have shown a particular embodiment of my invention. I do not desire: my invention to be limited to the particular construction shown and described and I intend in the appended claims to cover all modifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is: I

1. A method of forming a heat exchanger including a body to or from which heat is to be transferred comprising forming a plurality of heat transfer members with heat transfer portions and anchoring portions, providing a strip of heat conductive material with a plurality .of longitudinally spaced openings, assembling a plurality of said members in spaced-apart relationship, bending the edges of said strip into engagement with said anchoring portions of said members, placing solder adjacent said openings and said anchoring portions, disposing said as- In the-form of my.

sembled members and strip adjacent said body and fastening saidassembly to said body by heating said' assembly until said solder runs through said openings into contact with the surface of said body.

2. A method of forming a heat exchanger including a, body to or from which heat is to be transferred comprising forming a plurality of heat transfer members with heat transfer portions and anchoring portions, providing a strip of heat conductive material with a plurality of transversesubstantially parallel slits, assembling a plurality of said members in spaced-apart relationship, bending the edges of said strip into engagement with said anchoring portions of said members, placing solder adjacent said slits and said anchoring portions, disposing said assembled members and strip adjacent said body and fastening said assembly to said body member by a heating said assembly until said solder runs through said siitsintocontact with the surface of said body. i

' 3. The method of forming aheat exchanger f including a heat exchange member having a helica'lly wound heat transmitting element 'comprising, forming a plurality of wire members into 4 an inverted substantially U-shape with anchoring portions on the ends thereof, providing a strip of relatively good heat conductive material with a plurality of transverse substantially parallel slits, assembling a plurality of said members in spaced-apart relationship, enclosing said anchoring portions of said'membersin said strip by bending the edges of said strip into engagement with-said portions, placing a strip of solder along said strip and adjacent the open ends of said members, winding said assembly on said heat exchange body-to the desired length, and fastening said assembly to said body, said lastmentioned step comprisingheating said. assem bly and melting said solder whereby said solder runs through said slits into contact with the surface of said body adjacent said strip.

4. In'a heat exchanger comprising a fluid con veying conduit, a base element disposed in intimate thermal association with said conduit and having edges, and a plurality of spaced-apart wire members bent to form -substantially U- I shaped heat transfer members, the ends of said members being provided with anchoring portions, the edges of said base member being constructed and arranged to engage said anchoring portions,

said anchoring portions and said base member being fastened by soldering or the like to said conduit.

MYLEs J.- STANTON.

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