US2277921A

US2277921A - Heat exchange unit

Info

Publication number: US2277921A
Application number: US294310A
Authority: US
Inventors: William E Mccullough; Allen L Goldsmith
Original assignee: Bohn Aluminum and Brass Corp
Current assignee: Bohn Aluminum and Brass Corp
Priority date: 1939-09-11
Filing date: 1939-09-11
Publication date: 1942-03-31
Anticipated expiration: 1959-03-31

Description

2 Sheets-Sheet 1 HEAT EXCHANGE UNIT Filed Sept.- 11, 1939 W. E2M CULLOUGH ETAL March 31, 1942.

Emb 0 s n W C A ac, H 2. i 1

March 31, 1942. w MCCULLOUGH ET AL 2,277,921

HEAT EXCHANGE UNIT Filed Sept. 11, 1939 2 Sheets-Sheet 2 L Y %/:;Z/77E/VcCu//0u 5% ATTORNE Patented Mar. 31, 1942 I William E. McCullough and Allen L. Goldsmith,

.Detroit, Mich., assignors to Bohn Aluminum & Brass Corporation, Detroit, Mich., a corpo- Q ration of Michigan 1 Application September 11, 1939 Serial No. 294,310 7 2 Claims. (011257-150) This invention relatesto a heat exchange unit of the coiled type. A principal'object of the in-' vention is the provision of a heat'exchange unit formed of a strip of extruded metal, such as aluminum, in which lateral fins are 'formed homogeneous with the tubing of the heat exchange strip.' The strip is coiled sothat the finished unit has a substantially circular shape corresponding to the air stream from -a fan, and the laterally extending fins are deformed so as spirally with-adjacent convolutions spaced from 1 each other as shown in Fig. '2. v The-fins =1 l which face to the front in Fig. -1' are" then bent out-- wardly so that each annulus of the fin N forms a substantially funnel-shapedfmeinb er. The fins l2 on the opposite side of the strip are coned in the opposite direction so as to form a continuation of the funnel'shape on -the opposite side of the tubular section ill.

to project into-the space between adjacent runs of the strip to increase the efficiency of heat transfer between the moving air column and the heat exchange unit.

In one form of the invention the fins are bent so as to form a series of funnel-shaped rings, and in another form the outer edges of the fins are fluted, both of these constructions serving as inclined surfaces upon which the air stream impinges.

While preferred forms of the device are disclosed. herein for purposes of illustration, it should be understood that various changes may be made in the structure and arrangement of parts without departing from the spirit of the invention as herein set forth and claimed.

In the drawings:

The heat exchange unit thus formed, which is particularly useful as acondenser for mechanical refrigeration'systems", may be provided with Fig. l is a side elevation of a heat exchange unit made according to the present invention.

Fig. 2 is a section on line 2-2 of Fig. 1.

Fig.3 is a fragmentary section of the device of Fig. 1. s

Fig. 4 is a perspective view of a fragment of extruded strip of modified form.

Fig. 5 is a view similar to Fig. 4 showing another form.

Fig. 6 is a view similar to Fig. 1 but showing another arrangement of the fins.

Fig. 'l is a view similar to Fig. 6 illustrating an additional modification.

Fig. 8 is a section taken on line a-8 of Fig. 6..

Referring 'to the drawings more particularly,

Figs. 1 and 2 illustrate aform of the invention in which the'unit is made from an extruded strip which, as originally extruded, consists of a cylindrical tubular section It! from which fins ii and I2 extend in, opposite directions and parallel to each other. A piece of this extruded strip of length sufiicient to give thedesired'heat exchange capacity is then prepared by removing the'fins II and I2 from the ends of the strip so as to expose-the tubular part It), and these ends are suitably prepared for connection to other conduits as by having the flare tube couplings tfiiriountedthereon. .The strip is then wound any suitable means for mounting it in the vertical position illustrated in Fig; 1. The means illustrated consists ofa strap 14 having a T- shaped cross-section including a head l5 and a leg l6. Part of the leg I6 is removed at an intermediate part of the strap M for a distance corresponding to the thickness of the coil of extruded strip. The strap 14 is then bent into substantially U-shape as illustrated in Fig. 3. A groove corresponding to the size of the leg I6 is milled straight across the coil on both sides, and the bent strap I4 is then assembled over the coil by sliding the legs [6 into the slots formed in the fins II and I2 as illustrated in Fig. 3. The strap I4 is attached to the fins ll and I! in any suitable manner as by oven brazing. This latter process is particularly advantageous in this connection because each individual coil of the strip is thereby rigidly connected to both parts of the strap Id. The lower ends of the strap l8 are formed in any suitable way for mounting on a base as, for example, by bending the ends outwardly to form feet 11 which may be suitably braced and mounted on a support.

The heat exchange unit is preferably mounted with a. fan directing an air stream against the front face of the coil as shown in Fig. 1. The air stream from the fan thus strikes against the cone-shaped fins H, wipes around the cylindrical tube l0, and then impinges upon the cone-shaped fins l2'before emerging from the heat exchange unit. This arrangement provides for a positive wiping action of the air across the fins H and I2 as well as around'the tubular section II), thus inducing emcient heat exchange between the air and the unit.

In the form just described the central tubular portion was made cylindrical because that section is best adapted" to installations where a fluid passing through the tube is under a relatively high pressure. However, it will be understood strip l8 illustrated in Fig. 4 has a substantially oval tubular section. and in the strip 18 illustrated in Fig. 5, the central section has an angular outer periphery pierced by a cylindrical tubular opening. The strip may or course be extruded from other suitable materials, but aluminum is at present the preferred material.

It is particularly advantageous to have the lateral fins bent so as to extend beyond the lateral boundaries of the central tubular section so as to increase the area of the heat exchange unit upon which the air stream impinges. This object was accomplished in the form of Figs. 1 and 2 by bending the fins into coned or funnel shape. This result can, of course, be obtained by other arrangements. For example, in the form illustrated in Fig. 6 the lateral flanges the extruded strip are ruilled or fluted so that while the part of each fin adjacent the tube I0 forms a straight line, its outer end is fluted or ruiiied with the crests 20 of the flutes extending beyond the lateral boundaries of the tube section In. In manufacturing this form of the invention the ruflles or flutes are preferably rolled into the fins while the strip is in fiat condition so that when the strip is coiled into the shape illustrated in Fig. 6, the crests of the flutes are in hit or miss" relation to each other.

On the other hand, in the modification illustrated in Figs. 7 and 8 the flutes are pressed into the fins by fixtures after the strip has been coiled, and the crests of one turn of the coil are arranged in radial alignment with the crests of the turn beyond. In this way the ruilies form a series oi Venturi openings which narrow down toward the tube parts It), and then expand again on the back side of the unit. The advantages of these Venturi openings in increasing the velocity 01' air flow over the tubes In is well known in the art. In order to have this orderly arrangement of the crests 20, it is necessary to form the ruflles of increasing length going from the center turn of the coil toward the periphery so that entrances to the Venturi throats are larger in the outer turns than they are in the inner turns.

The arrangement in which the ruiiles of ad- {lacent runs of tubing are alined to provide enturi openings is claimed in co-pending application Serial No. 279,617, filed June 17, 1939 by William E. McCullough.

We claim:

1. A heat exchange unit comprising a single legnth or stock having a tube section and homogeneous fins, a fin extending laterally from each side of the tube section, the strip being formed into a coil with adjacent turns spaced apart so as to provide space for air streams, at least one of the lateral fins being deformed into a substantially conical rim extending from the tube section.

2'. A heat exchange unit comprising a single length of stock having a tube section and homogeneous fins, a fin extending laterally from each side of the tube section, the strip being formed into a coil with adjacent turns spaced apart so as to provide space for air streams, both lateral fins being bent so as to form substantially funnel-shaped openings through the unit.

ALLEN L. GOLDSMITH. WILLIAM E. McCULLOUGH.