US2985433A - Heat exchanger - Google Patents

Description

May 23, 1961 c. s. SIMPELAAR HEAT EXCHANGER Filed Jan. 22, 1957 HEAT EXCHAN GER Clyde S. Simpelaar, Racine, Wis., assignor to Modine Manufacturing Compay, Racine, Wis., a corporation of Wisconsin Filed Jan. 22, 1957, ser. No. 635,457

15 Claims. (Cl. 257245) The present invention relates generally to heat exchangers, and more particularly to very light weight heat exchangers of high surface density.

While high-density heat exchange structures have heretofore been developed, engineering advances in various fields, as for example, jet aviation, etc. have materially increased the problems attendant to heat exchanger design, and oftentimes the problems are relatively unrelated to the heat exchange requirements, but directly afiect the fabrication of a heat exchanger having the required characteristics.

In the case of aviation requirements, for example, while space and weight usually must be at a minimum, high resistance to operating pressures and high surface density and overall efficiency usually cannot be sacrificed. in the past, high density heat exchangers normally were not critical as to size and weight and in many cases the requirements were such that compromises could be effected which would satisfactorily answer the particular purpose. However, with present requirements, such as those above referred to, the possibility of effecting a compromise is practically entirely eliminated as substantially all the requirements are extreme ones and critical in the designs involved. It will be apparent to those skilled in the art, from the above design considerations, that such requirements cannot be met by prior exchanger structures, as for example, high density structures such as that illustrated in my prior Patent No. 2,606,007, issued on August 5, 1952 and entitled Heat Exchanger, involving the use of relatively heavy channel members, large, heavy con nections, numerous separate pieces, a relatively large amount of bonding material, etc. Similarly, while present requirements oftentimes dictate the use of small structures, a mere reduction in size of prior devices would not solve the problem, and in most cases, irregardless, practical considerations of manufacture and production would not permit such a solution, even if otherwise suitable. For example, while channel-shaped side closure members have been used in the past, where the fluid pass is very thin, say /5" or even less, channels would be impractical and solid bars would normally be used, even though these were heavier than operating pressures would require.

The importance of some of these considerations, as for example, weight, in present day considerations may be readily demonstrated. Thus, in the case of airborne heat exchange equipment, the total weight of the structure, in and of itself, may not be of extreme importance, but the supporting structure required therefor may have vital importance, as it has been estimated that the weight of such supporting structures in some instances involve up to ten times, and more, the weight of the exchanger structure. In such a case, a reduction of one pound of exchanger weight would save ten in supporting structure, and a saving in ten percent in exchanger weight would effect a total savings greater than the original total exchanger weight. These figures, translated into payloads and power requirements, etc. obviously can achieve considerable importance.

atent The present invention therefor has among its objects, the production of a heat exchange structure which will meet such requirements, and at the same time involve reasonable manufacture and production considerations, the present invention enabling the weight requirements to be reduced to practically an absolute minimum as dictated primarily by the heat transfer requirements, and affected only to a relatively negligible degree by constructional requirements relating to the provision of suitable connections between the exchanger and associated duct or equivalent structure, and resistance to operational pressures etc. 7

Another object of the invention is the production of such an exchanger structure which is inherently very resistant to high pressures, having substantially a bare minimum of bond joints, etc. and wherein between-pass joints may be relatively wide to eliminate the possibility of leak- 7 age between passes.

A further object of the invention is the production of such an exchanger structure, having a minimum of connector structure and at the same time being so designed that it may be readily dimensioned to close tolerances on all six sides, assuring easy assembly in accurately constructed supporting structures and replacement.

A further object of the invention is the production 0 such a heat exchanger structure wherein accurate fabrication of very-thin walled, elongated fluid passes, to vary close tolerances from sheet material, the width of which may vary by amounts considerably greater than the per- -mitted tolerances of the fluid pass dimensions.

A further object of the invention is the production of such a heat exchanger which may be so designed that it, in efiect, forms its own fixture or jig in the assembly thereof, which is particularly desirable in a structure such as that here involved utilizing very thin materials.

Many other objects will be apparent to those skilled in the art fromthe disclosure herein given.

In the drawings, wherein like reference characters indicate like or corresponding parts:

Fig. l is a perspective view of a heat exchange structure embodying the present invention;

Fig. 2 is an exploded perspective view of portions of a corner post, one fluid pass, and one fin and closure member;

Fig. 3 is a perspective view of an end portion of one of the fluid passes;

Fig. 4 is a transverse sectional view of a portion of the end frame and adjacent structure taken along a longitudinal line;

Fig. 5 is a perspective view, similar to Fig. 2, of a corner post structure having aligning pins thereon;

Fig. 6 is a top plan view of a corner portion of an exchanger utilizing a corner post construction as illustrated in Fig. 5, with portions of the pass and fin structures broken away to show details of construction; and

Fig. 7 is a transverse sectional View of a corner post constructed from sheet material or the like. v

The present invention generally contemplates the utilization of very thin metal for the formation of substantially the complete heat exchange structure, only the connecting structure utilizing heavier material, and in some cases even that may be fabricated from suitably formed thin wall material. Thus a single piece of material may be used for both pass separating walls defining a fluid pass, and the side closure members, as well as a pass reinforcement, and a plurality of passes may be assembled with suitable fin elements to produce a very light weight heat exchange structure.

Referring to the drawing, and more particularly to Figs. 1 through 4, the reference numeral 1 indicates generally a heat exchange core, having a plurality of elongated tubular-shaped fluid passes 2, assembled in spaced relation and having corrugated fin structures 3 interposed therebetween and along the exposed faces of the outermost passes. Associated with each fin structure at opposite ends thereof, are respective closure members 4. The core illustrated is completed by annular-shaped end-frames or connecting members indicated generally by the numeral 5, each illustrated as comprising a pair of spaced corner members 6, and upper and lower cross members 7. As illustrated in Fig. 3, each fluid pass 2 may be'provided with internal fin elements 8, the latter, together with the fin members 3 and end frames -5,'being bonded or otherwise joined into a unitary fluid-tight structure.

While the present invention may be applicable to heat exchange "structures of other dimensions, it is 'ofparticular advantage in applications where the dimensions of a unit such as that illustrated in Fig. 1 will normally run from 3" to 10" in width, 3" to 10"inheighth, and 6" to 30" in length, as therein viewed. In such cases, the material of the passes 2, fins 3 and 8 and closure members 4 will generally fall within a thickness range of from .003" to .010", the corner posts dfro'm W to 5 square, and the cross-members 7 proportionately dimensioned. In such cases the height of the fin elements 3 and Swill usually run from .030" to .250".

As illustrated in Figs. 2 and 3, each'fluid pass is generally tubular in shape, the transverse dimension or width, as viewed in Fig. 3, being considerably greater than its thickness or height, the latter being only a fraction of an inch, and the former several or more'inches. In the embodiment illustrated, each pass is formed from a single piece of sheet metal, reversely bent to form a single continuous wall 9 and a pair of aligned walls 11, each of which is connected along its outer edge to an edge of the wall 9 by an integral, rounded edge wall 12.

One of the opposed inner edges of the walls 11 is provided with a reversely bent U- haped flange 13, the web 14 of which is seated on the wall 9, thus forming spacing and reinforcing means for the pass. ing edge of the other wall 11 is provided with a single flange 15 which is adapted to nest in flange 13, as clearly illustrated in Fig. 3, and following the bonding operation, the flanges 13 and 15 will be joined into a unitary structure.

The fin elements 3 may be of ordinary construction, and the closure members 4 for the ends of the intermediate passes formed by the elements 3 may be formed as separate tubular members, having overlapped walls 16 and 17, as illustrated in Fig. 4, or, if practical in the particular application, may be fabricated as an integral part of the respective fin elements 3, as illustrated in Fig. 2, wherein the closure member 4' is a continuation of the fin element, having the wall 17' bearing against the corrugation wall16'. In either case, the outer edge wall 18, of the closure member is rounded in the same manner as the walls 12 of the fluid passes.

The corner members 6, as illustrated in Fig. 2, are generally L-shaped in transverse section and are each provided with recesses or notches 19 and 21 in their respective adjacent inner faces 22 and 23, the notches on one face being staggered with respect to the notches on the other face, whereby the notches 19 being complemental to the rounded edges 12 of the fluid passes and the notches 21 being complemental to the rounded edges 18 of the closure members 4 or 4, with the spacing being such that the passes, fin elements and closure members 4 may be assembled as illustrated with the latter seating on the adjacent fluid passes, andthe rounded edges 12 and 18 snugly seated in their particular notches, following which they may be bonded or joined together, along with the upper and lower members 7.

It will be appreciated that the joined elements must be connected in fluid tight relation which would require accurate dimensioning of parts, and obviously, 'a fluid pass having a circumference of approximately 6 to 20 or more inches would not permit the utilization of other The correspond-' 4 1 than minimum tolerances in fabrication. Thus while it might appear, at first glance, that the fluid pass structure is quite similar to flattened tubes with corrugated fins therein heretofore used in exchanger structures, which employed seamless tubes, or tubing formed from sheet stock and having a longitudinal-joint or seam, obviously, tubes of this type, for example, 5 in diameter, and .003" tube wall, would not be'produced in a seamless type commercially to tolerances here required, or in the case of seamed tubes, would not be practical in such light gauges,

and even if the latter could be overcome, unless overlapped, which would not be usual, a weak structure would result. It will be noted, however, that with the central flange construction illustrated, any variation in sheet width within commercial tolerances, of the stock from which the passes are formed may be readily accommodated in the flange 15, which need not have any definite length. Thus the flange 13, walls 9, 11 and 12 may be accurately formed, irrespective of such stock tolerances, even though a comparatively wide sheet'may be involved. Obviously, this result could not be so achieved by use of the usual seamless or seamed tube, in sizes here involved.

The corner members 6 may be formed in any suitable manner, one simple method being to employ square stock, drilling holes at the proper locations,'and then milling away the inner corner to form the inner faces 22 and 23.

Similarly, to provide an even superior connection between the corner members and the passes 2 and closure members 4, the corner members may be provided with short pins 24, as illustrated in Figs. 5 and 6,- which are concentrically arranged in the respective notches 19 and 21, so that the spacebe'tween the outer surface of each pin and the curved surface of the adjacent notch is of a width which will just permit the insertion-of the pass wall 12, or curved wall 18 of the closure member 4 to be inserted therein as illustrated in Fig. 6. Thus, the elements may beso assembled, temporarily elongating the fin elements 3 slightly, if necessary, in assembly the last two corner members, if the closure member is an integral part of the fin structure. It will be appreciated that the pins, in addition to providing an efiective joint, provided easy assembly, as the structure, inefiect forms its own jig or fixture,

and simplifies clamping operations etc. during the bonding operation. 7

While I have illustrated the corner posts as being of bar stock or the like, suitably shaped by machining or other operations, in some cases it may be desirable to also make the corner posts of sheet stock suitably formed, such a construction being illustrated in Fig. 7, wherein the corner post 6' is provided with notches or recesses 19 and 21 in the faces 22 and'23', the most being suitably die formed with the metal being coined as may be necessary to provide the desired sharp detail. At the same time if desired, a small projection or bars 25 may be formed in the end wall of each recess generally corresponding to the pins 24. Likewise, the post may be provided with suitable walls 26 and 27 for engagement with cooper-able connections, the walls being suitably formed to provide satisfactory rigidity therefor.

While I have illustrated the use of end frames, by means of which the exchanger, when inserted into a duct, could be attached to high pressure connections, in the event it is desired to attach connections to the inlet and outlet of the pass formed by the fin elements 3, longitudinally extending corner bars or members 28, as indicated in dotted lines in Fig. 4, could be employed, the upper and lower bar cross members 7 being enlarged as indicated, dotted lines, at -7' to provide regular faces. on all sides of the structure. It will be appreciated that in either event, the connecting frame structure may be readily machined or otherwise shaped to provide accurate overall dimensions, as well as parallel faces or edges on all sides of the structure, whereby low tolerances may be reasonably maintained. I

It will be noted, from the above disclosure, that I have provided a heat exchange structure, coupling high surface density, and compactness with substantially maximum possible weight reduction.

Likewise, the present invention enables the production of heat exchange structures almost completely from very thin sheet metal, at the same time utilizing relatively simple manufacturing techniques with the maintenance of very low tolerances, and wherein the structure itself may be utilized to function as its own fixture.

The invention also permits the production of elongated tubular structures having relatively large wall area from a single sheet of material, with substantially smooth, unbroken side walls, wherein the tolerances of the formed pass, in circumferential directions may be considerably less than the dimensional tolerance in width of the sheet from which the structure is formed.

Having thus described my invention, it is obvious that various immaterial modifications may be made in the same without departing from the spirit of my invention, hence I do not wish to be understood as limiting myself to the exact form, arrangement, or combination of elements shown and described, or uses mentioned.

What I claim as new and desire to secure by letters patent is:

1. In a heat exchange structure, the combination of a plurality of relatively flat fluid passes, each having a pair of substantially parallel side walls and relatively narrow edge walls, said flat fluid passes being similarly arranged in spaced relation, closure members interposed between successive flat fluid passes adjacent the open ends thereof, corner members at each corner of the passes so assembled, each corner member being generally L-shaped in transverse section, the adjacent faces of each corner member having notches therein of a size and shape to receive the edge portions of the respective flat fluid passes and closure members, said flat fluid passes, closure members and corner members being joined together in fluid tight relation.

2. A heat exchange structure as defined in claim 1, wherein said corner members are provided with projections extending outwardly from the respective end faces of said notches and adapted to extend into a cooperable closure member or fluid pass.

3. A heat exchange structure as defined in claim 1, wherein said notches in the corner members are semicylindrical and positioned in concentric relation with each notch is a pin adapted to engage a cooperable closure member or fluid pass.

4. In a heat exchange structure, the combination of a plurality of relatively flat fluid passes, each having a pair of substantially parallel side walls and relatively narrow edge walls, said flat fluid passes being similarly arranged in spaced relation, corner members at each corner of the flat fluid passes so assembled, each corner member being generally L-shaped in transverse section, a face of each corner member having notches therein of a size and shape to complementally receive the edge portions of the respective flat fluid passes, and means positioned between and engaged with adjacent flat fluid passes and with the corner members for sealing the spaces between the flat fluid passes, said flat fluid passes, corner members and the aforesaid means being positioned together in fluid tight relation.

5. A heat exchange structure as defined in claim 4, wherein each flat fluid pass is formed from a single sheet of material reversely bent along two parallel axes to form two substantially parallel side walls for reception in the aforesaid complementally formed notches for the fiat fluid passes and also complementally formed to the means for sealing the flat fluid passes, each of which is formed from the respective longitudinally extending edge portions of the sheet, one of such edge portions having an inwardly directed U-shaped flange, the web of which is seated on the inner face of the other side wall, the other edge portion having an inwardly directed flange thereon nested in said first-mentioned flange, the latter forming spacing and reinforcing means for the flat fluid pass irrespective of dimensional variations in the width of said second-mentioned flange.

6. In a heat exchange structure, the combination of a plurality ofrelatively flat fluid passes, each having a pair of substantially parallel side walls and relatively narrow edge walls, said flat fluid passes being similarly arranged in spaced relation, closure members interposed between successive flat fluid passes adjacent the open ends thereof, corner members at .each corner of the flat fluid passes so assembled, each corner member being generally L-shaped in transverse section, the faces of each corner member having notches therein of a size and shape to receive the edge portions of the respective closure members and the flat fluid passes, said flat fluid passes, closure members and corner members being bonded together in fluid tight relation.

7. In aheatexcha-nge structure, the combination of a plurality of relatively flat tubular fluid passes, each having a pair of substantially flat side walls and narrow rounded edge walls, said flat tubular fluid passes being similarly arranged in spaced relation with the side walls lying in parallel planes, the distances between faces of adjacent flat tubular fluid passes being of the order of the thickness of the passes, and annular end frames, positioned at the opposite open ends of the passes with a pair of opposed portions in engagement with the side walls of outermost flat tubular fluid passes, and with a second pair of opposed portions positioned at the corners of the assembled flat tubularrfluid passes, said last-mentioned second pair of opposed corner portions being L- shaped in transverse section and having notches in the adjacent inner faces thereof, the notches in the longitudinally extending faces being shaped complemental to the rounded edge walls of the associated flat tubular fluid passes, the notches in the adjacent inner face being staggered with respect to the first-mentioned notches, and a closure member positioned between each adjacent pair of flat tubular fluid passes, having its respective ends positioned in the adjacent second-mentioned notches and its longitudinal faces in abutting relation to the side walls of the adjacent flat tubular fluid passes, said flat tubular fluid passes and annular end frames and closure members being bonded into an integral structure.

8. A heat exchange structure, as defined in claim 7, wherein said closure members are of a tubular construction formed from sheet material similar to that comprising the flat tubular fluid passes, and a corrugated fin structure positioned in each of the flat tubular fluid passes and in the transverse passes formed by the intermediate spaces therebetween, those in the transverse passes extending transverse with respect to those in the first-mentioned flat tubular fluid passes and to the longitudinal axis of the fiat tubular fluid passes.

9. A heat exchange structure, as defined in claim 8, wherein the closure members and the corrugated fin structure associated therewith in a respective intermediate space are formed from a single sheet of material.

10. A heat exchange structure as defined in claim 7, wherein the end frames are rectangular in shape having parallel opposite outer side faces with the end faces lying in respective parallel planes and each pair of corresponding side faces positioned in common planes.

11. A heat exchange structure as defined in claim 7, wherein said corner portions are formed from sheet material which is deformed to provide the notches therein.

12. A heat exchange structure as defined in claim 7, wherein said corner members are provided with projections extending outwardly from the respective end walls of said notches.

13. A heat exchange structure as defined in claim 7, wherein said notches in the corner members are semicylindrical and positioned in concentric relation with each 7 notch is a pinadapted to engage a cooperable closure membe'rorfluidlpasfs, H 1,

14. A 'heat exchange "sitr'tidtiire as d'efi'ned in claim 8, wherein each flat tubular uid' bass is formed from a single sheet of'materialfeiiei'sely bent along two parallel axes to' form two substantially parallel sidewalls for reception in'th'e'afoiesaid co'rnple'rnentflly formed notches and also coinplementally formed to the closure member positioned between each adjacent pair of flat tubular fluid passes, one of which is formed from the respective opposed edge portions of the sheet, one of such edge portions having an inwardly directed u shap'ed flange, the web of which is seated on the inner fac'e of the other side wall, the other edge "portion having an inwardly directed 'fiange thereon nested in said first-mentioned flange, the latter fornli'n'g'spacing and reinforcing means for the passirr'espective of dimensional variations in the width of said second-mentioned flange.

ISQA heat exchange structure as defined in claim 7, wherein the annular and frames are rectangular in shape and connected at each com er by said L shaped and longitudinally extending bfipds'e'd chi e: fpbi'tio ns, said annular end frames having paralleldp'posi't'e ol'lterfside faces with'the fend faces l'yi'ng in' fsjjectivepar allel planes and each pair of 'corre'spbnding side fa'c's pds'iti'otfed in 'cornmon plane's.

References Cited in the file of this patent UNITED STATES PATENTS 1,460,805 7 Sway July 3, 1923 2,136,641 Smith Nov. 15, 1938 2,143,269 Hubbard Ian, 10, 1939 2,288,061 Arnold "June 30, 1942 2,360,123 "G'efstung et a1. Oct. 10, 1944 2,373,218 Arnold Apr. 10, 1945 2,480,706 Brinen Aug. 30, 1949 2,655,181 Cooper Oct. 13, 1953 2,782,009 Rippingille Feb. 19, 1957 2,782,010

Sinipelaar Feb. 19, 1957

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