US2991047A - Heat exchanger - Google Patents

Description

July 4, 1961 c. BAILYS HEAT EXCHANGER 2 Sheets-Sheet 1 Filed July 26, 1957 C. BAILYS HEAT EXCHANGER July 4, 1961 2 Sheets-Sheet 2 Filed July 26, 1957 United States Patent 2,991,047 HEAT EXCHANGER Carl Barlys, Detroit, Mich., assignor to Borg-Warner COI'POl'fitlOH, Chicago, 111., a corporation of Illinois Filed July 26, 1957, Ser. No. 674,516 2Claims. (Cl. 257-130) This invention relates to heat exchangers and, more particularly, to a heat exchanger of the tube sheet type fabricated from a plurality of sheets of metal selectively bonded each to the other at predetermined zones to define intermediate unbonded zones which may be complementally shaped, as by hydroformin-g and the like, to form spaced tubes for passage of fluid.

This invention is primarily directed to a heat exchanger of the stated type in which a portion of the web between the tubes remains unbonded, in which a plurality of fins are formed in the web and in whichthe several plies forming the fins are separated to form single-thickness panels so that the total heat exchange surface area is substantially increased.

A primary object of the invention is, therefore, to provide a heat exchanger of the stated type having all of the advantages of the multiple-sheet construction, yet exhibiting a substantial increase in heat transfer area.

Another object of the invention is to provide a heat exchanger of the multiple-sheet type having a plurality of parallel integral tubes separated by webs having a plurality of angularly extending integral fins in heat conductive relation thereto, in which the several plies forming the fins are separated to reduce the effective thickness of the fins and to form passages therebetween for the flow of air so that eflicient heat transfer is aiforded.

Another object of the invention is to provide a heat exchanger of the type described, in which the fins are integral with the tubes, in intimate heat conducting relation thereto and are so formed to eflfect turbulence in the heat exchange fluid during the course of its passage therethrough.

A further object of the invention is to provide a heat exchanger of the stated type characterized by ease of manufacture, efllciency and facility of use, convenience in form, and improved functional characteristics.

A more particular object of the invention is to provide a heat exchanger of the tube sheet type in which a plurality of sheets of similar metal are integrally bonded at preselected zones, in which tubular passages are formed in certain of said unbonded zones for the flow of heat exchange fluid, in which the sheets in others of said unbonded zones are slit or partially severed therefrom to form strips which are bent to assume an angular relation with respect to the plane of the sheets thus forming a plurality of openings for the flow of heat exchange fluid and in which each strip is separated to form a plurality of single fins for secondary heat exchange between the tubular passages and fluid flowing through the fins.

A final object of the invention is to devise a method for making a heat exchanger of the stated type in which the fin formation is effected in such a manner that torsional stresses are substantially reduced and in which the formation of single-thickness fins is facilitated.

Other objects and features of the invention will be readily apparent to those skilled in the art from the specification and appended drawings illustrating certain preferred embodiments in which:

FIGURE 1 is a front elevational view of a heat exchanger made in accordance with the present invention;

FIGURE 2 is an edge view showing a preform of the present heat exchanger, in an intermediate state of formation, in which parallel bonded zones of a multiple-sheet unit are illustrated;

FIGURE 3 is a view similar to FIGURE 2, but showing a heat exchanger preform in the next subsequent stage of development in which certain of the unbonded zones are formed into spaced parallel tubes forpassage of fluid;

FIGURE 4 is an enlarged fragmentary sectional plan view of a heat exchanger fin made in accordance with the present invention;

FIGURE 5 is a sectional plan view taken substantially on line 5-5 of FIGURE 4; and

FIGURE 6 is an enlarged elevational sectional view taken substantially on line 6-6 of FIGURE 4.

Referring now to the drawings and more particularly to FIGURE 1, the heat exchanger of the present invention is in the form of a tube sheet indicated generally by reference numeral 10 and in the illustrated embodiment includes a first sheet 6 of metal, such as aluminum or the like, and a second sheet 8 of similar metal bonded to the sheet 6 at predetermined zones to define headers consisting of an upper manifold 12 and a lower manifold 14, and a fin unit or matrix 16 interposed therebetween and having a plurality of integrally formed parallel tubes 18 connecting the manifold 12 and the manifold 14 and spaced each from the other by webs 19.

The tubular passages 18 of the present heat exchanger may be integrally formed by the process of the Reynolds Metals Co. described in the February 1956 issue of the magazine Modern Metals, or by similar processes, such as the Roll-Bond process. In the present disclosure the term tube sheet has the same meaning as in those processes and refers to an integral combination of tubing and webs connecting the tubing, the tubing and webs being formed from a blank comprising a plurality of sheets of metal integrally bonded at preselected zones to define unbonded Zones therebetween.

According to the present invention certain of the unbonded zones are expanded to form the tubular passages 18 while intervening unbonded zones, forming major portions of the webs 19 joining adjacent tubes 18, are slit along parallel lines to form contiguous strips. The strips of each web 19 are shaped, by bending or the like, to form a fin section 20 having a plurality of multi-ply fins 22 spaced each from the other to define openings 23 therebetween for free passage of cooling fluid, or fluid to be cooled, such as air or the like, in a direction substantially perpendicular to the plane of the web 19. It will be noted that the unbonded fin matrix constitutes substantially all of the unbonded areas between the conduits to enhance heat transfer. In the present instance, the fins 22 are angularly disposed with respect to the plane of the web 19 and are desirably bent into the configuration illustrated by stamping or the like. The particular shape of the fins 22 shown is characterized by rigidity and freedom from torsional stresses, and in accordance with the present invention, this construction is amendable to separation of the sheets 6 and 8 in the area of the fins 22 so that the effective heat transfer area is substantially increased.

Referring now more particularly to FIGURES 4 and 5, each of the multi-ply fins 22 includes separate panels 24 spaced each from the other to form therebetween passage 26 substantially equal in width to the openings 23. Each of the fin panels 24 may be considered a single-thickness fin and includes a pair of curved portions 28 extending outwardly in both directions from the plane of the web 19, and a central portion 32 extending substantially perpendicular to the plane of the web 19 and joining the portions 28. It will be noted that the several fin panels 24 diverge each from the other to form the passage 26. The portions 32 are shown as being parallel each to the other but it will be appreciated that they may assume any relation. For instance, the portions 32 may be bowed.

In forming the heat exchanger of the present invention, the sheets 6 and 8 are provided with a suitable parting compound along parallel paths. Certain of these paths are for the formation of the passages 18 while alternate paths are for the formation of the fins 22. The sheets are then juxtaposed and subjected to a hot rolling operation to join the sheets in the zones between the paths of parting compound. The passages 18 are then hydraulically formed in the conventional manner so that the blank assumes the configuration shown in FIGURE 3. The blank is then provided with a plurality of spaced parallel slits between each pair of tubes 18. The strips between each pair of slits are then bent to form the multiply fins 22. Then the fins 22 are split by means of a wedge, drift, or other suitable means to form the separate panels or single-thickness fins 24. It is contemplated that the panels 24 of the several fins 22 may be conveniently separated simultaneously.

It will be apparent from the foregoing description that when the present device is used, for example, as a heat exchanger for an air conditioning system that fluid to be cooled or liquified may pass into the upper manifold 12 and thence downwardly through the several tubes 18 to the manifold 14. During the course of its passage, the fluid is subject to heat exchange with air flowing through the openings between the several multi-ply fins 22 and through the passages 26 defined by the several singlethickness panels forming a part of each fin 22. It will be appreciated that the air may be at a temperature level higher or lower than the temperature level of the fluid. The air flows into contact with the several tubes 18 to elfect primary heat exchange, while secondary heat exchange is afiorded by contact of the air with the several panels 24 of the fins 22. In the present construction free flow of heat between the tubes 18 and the fins 22 is made possible by the fact that the portions of the intervening webs are integrally bonded, there being no solder or brazing therebetween to hinder this flow of heat. The gradual curvature of the distorted portions 28 assumes freedom from torsional stress in these areas.

The heat exchanger of the present invention exhibits important advantages over prior constructions in that the conduction of heat from the walls defining the passages 18 to the fins 22 is facilitated, since both sides of the fin panels 24 are exposed to the flow of air. Since the thickness of each section is only a fraction of the thickness of the composite blank, the passage of heat from the fin panels is enhanced. The present heat exchanger is a unitary structure which may be conveniently formed. According to the present method, the passages 18 may be formed after the slitting step, if desired.

While I have described my invention in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not by way of limitation and the scope of my invention is defined solely by the appended claims which should be construed as broadly as the prior art will permit.

I claim:

1. A heat exchange element comprising at least one pair of relatively spaced conduits and a fin matrix joined to said conduits and extending therebetween, said fin matrix comprising two plies of heat conductive sheet material bonded together in areas at their junction with said conduits and unbonded in the areas intermediate said conduits, all of the unbonded areas of said plies being provided with spaced parallel fin elements partially severed therefrom and extending thereacross substantially normal to said conduits and disposed in relatively spaced confronting pairs between and at lateral angles to said conduits, said fin elements being joined to one another and to the conduits in the bonded areas adjacent to said conduits.

2. A heat exchange element as defined in claim 1, wherein the fin elements are joined to one another and to the conduits in the bonded areas adjacent to said conduits by adjacent distorted portions of the fin elements.

References Cited in the file of this patent UNITED STATES PATENTS 1,823,003 Replogle Sept. 15, 1931 2,375,334 Valyi et al. May 8, 1945 2,582,358 Schoellerman Jan. 15, 1952 2,647,731 Ludlow Aug. 4, 1953 2,652,233 Przyborowski Sept. 15, 1953 2,690,002 Grenell Sept. 28, 1954 2,759,247 Grenell et a1. Aug. 21, 1956 2,779,086 Rieppel et a1. Jan. 29, 1957

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