US2661191A - Heat exchanger - Google Patents

Description

ec. 1, 1953 R. A. SANDBERG HEAT EXCHANGER Filed Feb. 8, 1950 JHVEJYL UP 53: Eag M5az2dbezg Z HLi E Patented Eec. l, 1953 HEAT EXCHAN GER Bay A. Sandberg, Waukegan, Ill., assignor to Houdaille-Hershey Corporation, Detroit, Mich., a corporation of Michigan Application February 8, 1950, Serial No. 143,010

Claims. (Cl. 257-256) The present invention relates to a heat exchanger and to a method of making the same. More particularly, the present invention relates to a heat exchanger of the plate and tube type provided with means for greatly increasing the effective area of the exchanger, and to a method for making such an exchanger.

Tube and plate type exchangers of the prior art typically comprise a heat conductive backing plate on which a continuous length of tubing is secured, as by brazing or welding, to provide a conduit for the flow of heated or refrigerated fluid. In my copending application Serial No. 80,240, filed March 8, 1949, now abandoned, and entitled Heat Exchanger and Method of Making the Same, I have disclosed the employment of a backing plate which is deformed into tightly gripping effective heat transfer relation with a tube to eliminate the necessity of a separate welding or brazing step. Reference is also made to my copending application Serial No. 206,531, filed January 18, 1951, disclosing common subject matter.

The present invention now provides an improved heat exchanger in which the effective heat exchange area of the unit is greatly increased while at the same time maintaining highly efficient heat transfer contact between the plate surfaces and the exchanger tube.

More particularly, the present invention contemplates the provision of a main backing plate of good heat conductive properties and an auxiliary heat conductive plate having spaced elongated portions secured to the backing plate and intermediate portions spaced from the backin plate to provide an additional heat exchange surface. The heat exchanger tube is secured in the assembly at the area of contact between the two heat conductive surfaces, so that effective heat transfer between the tube and each of the heat conductive members is attained. In addition, these cooperating heat conductive members provide channels or stacks for the flow of a gaseous medium, such as air, into contact therewith to increase the heat transfer efficiency of the unit.

The method of the present invention contemplates the formation of elongated spaced parallel grooves in contacting portions of the main and auxiliary plate members, the positioning of a tube within the grooves, and the deformation of each of the plate members to overlie a median diameter of the tube portions bottomed in the grooves to securely lock both of the heat dissipating members andthe tube into a secure, thermally efficient assembly.

The advantages of the present invention reside in the increased efficiency of the exchanger due to the effective channeling of the gaseous medium to be heated or cooled and to the effective heat transfer relation between the tube and each of the plate members.

It is, therefore, an important object of the present invention to provide an improved heat exchanger of the plate and tube type having a greatly increased heat exchange area.

Another important object of the present invention is to provide an improved method of making a heat exchanger by the securing of a tube to the exchanger by the deformation of a plurality of plate members into greater than semi-peripheral contact with the tube.

A further important object of the present invention is to provide an improved heat exchange panel including a pair of plate members and a tube secured to the members in effective heat transfer relation, the plate members cooperating to define therebetween gaseous flow passages and a heat transfer surface of increased area.

It is still another important object of the pres ent invention to provide an improved method for making a tube and plate type heat exchanger including the steps of grooving a pair of heat conductive plates, positioning a heat exchange tube in the grooves thus formed, and deforming grooved portions of both of the plates to overlie a median diameter of the tube, thereby interlocking the tube and the plates into a thermally eificient assembly.

Other and further important objects of this invention will be apparent from the disclosures in the specification and the accompanying drawings.

On the drawings:

Figure l is a plan view of a heat exchanger of the present invention;

Figure 2 is a fragmentary, enlarged sectional view taken along the plane II-II of Figure l and Figure 3 is a fragmentary, enlarged sectional view, similar to Figure 2, illustrating a step in the method of making the heat exchanger of Figure 1.

As shown on the drawings:

In Figure 1, the reference numeral It! refers generally to a heat exchanger of the present invention including a sinuous tube ll having straight parallel portions 12 extending along the length of the exchanger [0 and arcuate portions l3 joining the straight portions [2 and extending beyond the confines of the heat exchanger it.

In Figure 2, it will be seen that the straight 3 parallel portions I2 of the tube II are secured to a backing plate I4 and a supplementary plate I5. Both plates are formed of thin sheet metal having good thermal conductive properties, such as mild steel. The backing plate I4 is provided with parallel marginal upstanding flanges I6 deformed from the plane of the plate Id. The flanges I6 are apertured as at H at spaced points along their length to facilitate assembly of the heat exchanger ID in a desired position, as on a refrigerator or the like.

The supplementary heat conductive plate. I5, which is preferably of lighter gauge than the plate I4, is provided with parallel, longitudinally extending raised portions I8 which extend along the length of the backing plate It between the flanges I6 and generally parallel to the: flanges I6 and the tube straight portions I2. The raised portions I8 of the member I are provided" with transversely extending raised reinforcing ribs I9. The height of the. raised portions: I281- is such that the. upper. surface of the ribs; is. displaced from the mean plane of the. plate I4: tov a distance approximately equal to or slightly less; than the height of the end flanges IS.

The auxiliary plate I5 is provided with inclined web portions joining the raised portions I8 to intermediate web portions 2| of the plate I5. The web portions 2| of the auxiliary plate 45 and a corresponding portion of the backing plate I4 are employed to lock the straight tube portions I2 within the assembly as. hereinafter described.

The method of assembly (Figure 3) includes, first, the initial deformation of each of the plates I4 and I5 to provide a plurality of parallel, spaced depressions or grooves 22 and 23 in the plates I4 and I5, respectively. The grooves 22 and 23 have arcuate bottoms 22a and 23a, respectively, and upstanding parallel side walls. 22b and 231), respectively. The grooves 22 and 23 may be formed simultaneously following the positioning of the supplementary plates I5 upon the backing plate It, or the grooves. may be separately formed in each. of the plates; for. registry upon initial assembly. In any event, each of the I grooves extends uniformly along. the length of the respective plates so that. upon assembly; the coextensive grooves 22 and 23. are nested,. as shown in. Figure 3.

The straight tube portions I2. are inserted in the grooves 23 which, in turn, are nested in the grooves 22. The radius of curvature ofv the.- arcuate bottom 23a of the groove 23. is. substantially that of the exterior surface of. the: tube. while the radius of curvature of. the interior surface of the groove 22 is substantially that of the exterior surface of the groove 23 so that smooth mating engagement is attained. It' will also. be noted that the depth of the groove 23. is substantially greater than. the diameter: of the tube II.

It will be seen that only the straight portions I2 of the tube II are. bottomed within the groove 23. This eliminates the necessity of forming sinuous grooves in the plates I4 and I5, inasmuch as the arcuate joining portions L3 of the tube II are allowed. to project beyond the side extremities of the plates I4 and I5 of the finished exchanger I0.

The securing of the tube II to the plates I4 and [5 within the grooves. 22 and 23- may be carried out by means of apparatus such as that illustrated in the above-identified copending application or by other suitable means for swaging or otherwise deforming the upstanding side walls 221) and 23b of the grooves 22 and 23, respectively, to overlie a median diameter of the straight tube portions I2. This deformation of the grooved side walls may be carried out by either a rolling or a stamping operation. As a result of the deformation of both plates, the mating portions of the plates I4 and I5 are deformed to overlie greater than semi-peripheral portions of the tube I2. The deformation is such that a pair of additional grooves 25 and 25 are formed alongside of and parallel to the main grooves 22 and 23 in the plates I4 and I5, respectively. These additional or supplementary grooves 24 and 25. are contiguous to and coextensive with the lengths of the main grooves 22 and 23, and metal intermediate the supplemental grooves and the main groove of each plate is actually deformed inwardly of the tube to overlie the tube I2, as at 2B and 21.

The area of contact. of the plates I4 and I5 is coextensive withthe area of the. grooves. 22 and 25 of the backing plate I4 and the area of the grooves 23 and 25 of theplate l5- The con.- tact area thus includes the metal of; the plates I4 and I5 partially surrounding the. tube I2- and the immediately contiguous. plate areas. of the supplemental grooves formed: on; interlocking the plates andthe grooves.

There is no actual surface. contact between the backing plate. I4 and the tube. portion; I52: However, the backing plate portions 26 are de-- formed so as to overlie. a median diameter" of the tube, thereby locking the. plate through. the tube in a firm interlocking engagement. Tl'xese same interlocking portions 26; of the plate. H3; in combination withthe tube: portions I2. secure the auxiliary plate IE to the plate. I 4.

Upon the assembly of the: heat exchanger. Ii] in operative position, as, for instance, supported upon the back surface of a. refrigerator or the like, with the' parallel lengths: of tubing extending vertically, the supporting. surface cooperates with the ribs I9 formed on the raised auxiliary plate portions It to defln'etherewith azplurallty of channels with the: tube portions I2. in one; of the channel walls. Also, the raised. portions; [8 andthe backing plate I4 cooperate to defineadditionalchannels therebctween. The raised. ribs I 9 not only serve to reinforce the. raised portions I8 of the plate I4 but these ribs'serve: to space the raised portions. [8 from a supporting surfaceso that minimum interferencewith heat transfer from theportion If) isolfered; It. will be seen that the auxiliary heat exchanger plate I5 serves to divide air flow between the flanges I6 into a plurality of different columns'or stacks. Thus, each side of the-surfaces I8: and 20,.and those surfaces of the auxiliary plate overlying the backing plate, may effectively serve. as heat dissipation surfaces. In addition, those surfaces of the backing plate I i underlying the raised portions I2 of the plate Iii alsoserve. as heat dissipating surfaces. The auxiliary plate. thus more than doubles the effective heat dissipating surface ofthe heat exchanger. The channeled separation of air or other gaseous coolant: also increases air circulation and turbulence, so that all of the coolant mediumis effectively employed.

It will be understood that modifications and variations may be efiected. without departing from the scope of the novel concepts of the present invention,

I claim as my invention:

1 The method of. making a heat. exchanger which comprises forming a pair of parallel grooves in a first metal plate spaced a preselected extent of the first plate apart, forming a pair of parallel grooves in a second metal plate spaced a preselected extent of said second plate apart, said last mentioned extent being greater than said first mentioned extent and with respective grooves of said first and second plates nesting one within the other, bottoming a tube in the inner of said nesting grooves, and deforming the side walls of each of said grooves and intermediate contiguous portions of each of said plates radially inward of the tube to overlie a median diameter of said tube, thereby securely locking the tube in said grooves and said plates to one another in efficient heat transfer relation.

2. A heat exchanger comprising a backing plate, an auxiliary plate having spaced portions contacting said backing plate and intermediate offset portions forming a coolant flow channel therebetween, and a sinuous tube for confining a flowing heat exchange fiuid having portions secured within coextensive nesting grooves formed in contacting portions of said auxiliary plate and said backing plate, said tube being in greater than semi-peripheral surface contact with said auxiliary plate and in efficient heat transfer relation with both said auxiliary plate and said backing plate.

3. A heat exchanger comprising a backing plate having a plurality of elongated parallel grooves extending thereacross, an auxiliary plate also having a plurality of grooves extending thereacross and nested within the grooves of said backing plate in surface contact therewith, said auxiliary plate having portions intermediate the grooves therein spaced from corresponding portions of said backing plate and a sinuous tube seated in said nesting grooves and secured therein by being in greater than semi-peripheral surface contact With the grooves of said plates.

4. A heat exchanger comprising a sinuous tube having straight parallel portions joined by arouate intermediate portions, a first heat conducting plate having spaced grooves receiving the straight parallel tube portions with said arcuate intermediate portions of the tube extending beyond said first plate, said grooves being in greater than semi-peripheral surface contact with said tube to secure the same thereto, and a heat conductive backing plate having parallel spaced grooves eX- tending thereacross receiving the grooved portions of said first plate coextensive and interlocked therewith to secure said backing plate to said first plate, said plates having other portions spaced apart to define coolant flow passages therebetween intermediate the straight portions of said tube.

5. In a heat exchanger including a backing plate having parallel spaced grooves, a sinuous tube having parallel portions secured within said grooves, an auxiliary heat dissipating plate comprising spaced parallel groove portions nesting with the grooves of said backing plate and interposed between said backing plate and said tube, said grooved portions being interlocked with said backing plate in effective heat transfer relationship therewith and in extended surface contact with said tube, and said auxiliary plate having additional portions intermediate said grooved portions offset from the plane of said backing plate and cooperating therewith to define a gas flow passage.

6. A heat exchanger comprising a backing plate, an auxiliary plate having spaced portions contacting portions of said backing plate and an intermediate ofiset portion forming with said backing plate a coolant flow channel, said backing plate and said auxiliary plate having elongated nesting grooves in the contacting portions of said auxiliary plate and said backing plat-e, and a tube for confining a flowing heat exchanger fluid, said tube having portions secured within said elongated nesting grooves in efficient heat transfer relation with both said auxiliary plate and said backing plate.

'7. A heat exchanger for attachment to a substantially plane supporting surface, comprising a thermally conductive metal backing plate having end flanges for contacting said supporting surface, said flanges and said backing plate cooperating with said surfaces to define a primary coolant fiow channel, an auxiliary plate having spaced portions contacting portions of said backing plate and intermediate offset portions forming with said backing plate a secondary coolant flow channel, said backing plate and said auxiliary plate having elongated nesting grooves formed in the contacting portions of said auxiliary plate and said backing plate, and a tube for confining a flowing heat exchanger fluid, said tube having portions secured within said coextensive nesting grooves in eficient heat transfer relationship with both said auxiliary plate and said backing plate.

8. A heat exchanger for attachment to a substantially plane supporting surface, comprising a thermally conductive metal backing plate having end flanges for contacting said supporting surface, said flanges and said backing plate cooperating with said surface to define a first coolant channel, an auxiliary plate having spaced portions contacting portions of said backing plate and intermediate offset portions forming with said backing plate a second coolant fiow channel, said contacting portions of said auxiliary plate and said tube backing plate having elongated nesting grooves therein, and a tub-e for confining a flowing heat exchange fluid, said tube having portions secured within said elongated nesting grooves in efficient heat transfer relation with both said auxiliary plate and said backing plate.

9. A heat exchanger for attachment to a substantially plane supporting surface, comprising a thermally conductive metal backing plate having end flanges for contacting said supporting surface, said flanges and said backing plate cooperating with said surface to define a primary coolant flow channel, an auxiliary plate having spaced portions contacting portions of said backing plate and intermediate offset portions forming with said backing plate a secondary coolant flow channel, said backing plate and said auxiliary plate having elongated nesting grooves formed in the contacting portions of said auxiliary plate and said backing plate, and a tube for confining a flowing heat exchange fluid, said tube having portions secured within said elongated nesting grooves and in efiicient heat transfer relationship with both said auxiliary plate and said backing plate.

10. In a heat exchanger including a backing plate having parallel spaced grooves, a sinuous tube having parallel portions secured within said grooves, an auxiliary heat dissipating plate hav ing a grooved portion nesting with one of said grooves of said backing plate and interposed between said backing plate and said tube, said grooved portions being interlocked with each other and with said tube portion secured therein and in effective heat transfer relationship there- 7 with and u said auxiliary plate h-atvingzprojeetinns extending from the plane oi'saidz backingfplate and at a substantial angle thereto between; acljatcent grooves and cooperating with said-backing plate 'to' increase theiheatiexchangiemefi'lci'ency of the heat exchanger;

RAYA. SANDBERG;

ReferencesCited in thefile of thispatent UNITED STATES PATENTS Number Name Date.

1,707,655 Cohn ,Apr; 2,: 1929 Number Name Date Whitesel Dec. 8, 1936 Brown Aug. 31, 1937 Steenstrup Apr. 28, 1942 Schoen July 14, 1942 Herter Dec, 29, 1942 Lynn Nov. 11, 1947 FOREIGN PATENTS Country Date Great Britain Jan. 4, 1934 GreatJB'ritain' Aug; 25, 1937

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