US 1902350 A
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March 21, 1933. L. P. WHITAKER HEAT EXCHANGER Original Filed Jan. 31, 1931 2 Sheets-Sheet INVENTOR Patented Mar. 21, 1933 UNITED STATES PATENT OFFICE LOUIS PREVOST WHITAKER, OF NEW YORK, N. Y., ASSIGNOR TO S. R. DRESSER MANU- FACTURING COMPANY, OF BRADFORD, PENNSYLVANIA, A CORPORATION OF PENN- SYLVANIA HEAT EXCHANGEB My invention consists in the novel features hereinafter described, reference being had to the accompanying drawings which show one embodiment of my invention, selected by me for purposes of illustration, and the said invention is fully disclosed in the following description and claims.
My invention relates to heat exchangers adapted especially for the transmission of heat, in heating oricooling systems. The process by which my improved heat exchangers are preferably manufactured as hereinafter described, forms no part of my present invention and is not claimed herein, as it forms the subject matter of myformer application for Letters Patent of the United States filed January 31, 1931, Serial No. 512,577, of which this application is a divi- 5101].
Heat exchangers of this kind ordinarily comprise a plurality offins or plates in' spaced parallel relation and extending in ;all directions from a fluid conducting passage or conduit with which the fins are united. It has been proposed heretofore to form a heat exchanger of this kind by employing a plurality of apertured plates provided with spacing elements, usually integral with the plates, and in the form of a cylindrical flange coaxial with the central aperture therein, the flanges of said plates being placed upon a heavy supporting pipe which forms the conducting passage, and the plates and supporting galvanizing, soldering, brazing or welding the flanges of the plates to the supporting pipe. This construction presents a number of disadvantages, one of which is the difficulty in securing and maintaining a satisfactory union between the supporting pipe and the plates, to insure rapid conductivity of heat from the interior of the pipe to the fins, or vice versa, and the production of such heat exchangers 0r fin units is very expensive. particularly where the plate flanges are welded or brazed to the pipe. I am also aware of the fact that it has been proposed to assemble in a built up structure a plurality of apertured plates or fins with alternating spacing members between them, provid- '-sembled tube and P p being united by Divided. and this application filed October Serial No. 568,008.
ing a removable internal core of less external diameter than the internal diameter of the longitudinal space formed within said apertured plates, and spacing members, and casting a cylindrical body between said core and he spacing members in such manner that portions of the plates will be anchored or embedded in the casting, for the purpose of uniting the plates with the cast portion, which provides the fluid conducting passage of the unit and becomes the supporting member thereof. I
According to my present'invention in its preferred form I employ a plurality of apertured plates provided with spacing members coaxial with the apertures therein, and formed conveniently integrally with the plates. These plates are arranged in a built up structure, with cylinder, which is preferably formed of metal of high heat conducting capacity, the spacing members of the plates being spaced annularly from the interior tube coaxial relation therewith. The spacing members are conveniently provided with inwardly extending separated lugs or projections engaging the interior tube at separated points, while the space between the tube and the spacing members of all of the plates of the series is in direct communication throughout the length of the unit. The as- 7 plates are preferably clamped in assembled relation. and supported in a vertical position upon a suitable supand maintained in end of the annular space between the interior tube and the spacing elements of the plates, and cast metal ispoured into this annular space so as to rigidly and permanently unite the plates and also the inner tube, which forms the inner mold wall, while the outer mold wall is formed by the spacing members. Wherethe spacing members are provided with centering lugs to engage and center the inner tube, such lugs would be anchored or embedded in the cast metal. The built up structure is preferably heated before or during the casting operation to facilitate the flow of the metal. I prefer to introduce a .end of the inner tube, so as to facilitate the casting operation.
By forming the heat exchanger or fin heating unit in this manner, a comparatively thin body of cast metal may be formed which reinforces the light inner tube and unites it and the plates or fins into a substantiallyintegral structure, which readily transmits heat from the interior of-the inner tube to the fins, or vice versa. Suitable internally threaded. collars are preferably inserted in 'theopposite ends of the thin inner tube, by
pressing them into the'same, or otherwise securing them thereto, either before or after the casting operation, but preferably before the cast metal is poured, which collars facilitate the connection of pipe fittings of usual character to the unit. A plain end plate, or plates, may be applied to the built up structure and secured in any desired manner thereto, or to the screw collars, to give a desired finish to the unit. V
My invention also comprises the novel features of construction and combination of parts hereinafter fully described and partieularly pointed out in the claims.
Referring to theaccompanying drawings,
Fig. 1 is a sectional view, with the central portion omitted, and indicated by dotted lines, showing a plurality of plates or fins assembled upon an interior thin walled tubular member and supported in position for casting the annular connecting body between said tubular member and the spacing mem-- bers of the plates.
Fig. 2 is a top plan view of one of said plates.
Fig. 3 is a perspective view, partly in section, of a portion of two of the'plates in as- I sembled relation.
Fig. 4 isa side view, partly in section and partly broken away, of a completed heat exchanger or fin heating unit.
Fig. 5 is a top plan View of a modified form of plate.
Fig. '6 represents a section on the line 66 of Fig. 5.
In carrying out my invention, I form plurality of plates or fins, indicated at l, which are preferably pressed or stamped from sheet metal. such as copper, aluminum, iron or steel, for example. The plates may be circular or rectangular or of any other desired form. Each plate is provided with 'stitute the outer mold wall.
an aperture, indicated at la, although it will be understood that each plate may have more than one aperture if the plates are to be provided with a plurality of tubular passages. As shown, the aperture, 1a, is centrally located, and the plate, 1, is provided with an annular substantially cylindrical fiange,,2, surrounding the aperture, 1a, and coaxial therewith. These annular flanges form integral spacing members for spacing the plates longitudinally 'with respect to the tubular passage, and I prefer to provide said spacing members at their free edges with inwardly extending separated lugs, 3, 3, three of which are indicated in the drawings, see Fig. 21, and which serve the function of centering the plates with respect to the inner tube. These lugs, however, may be omitted and the tube may be centered in other ways. Each late is also preferably provided with auxl lary spacing elements,
indicated at 4, which may be conveniently formed by struck-up portions of the metal of the plate extending at right angles thereto and of a proper length to serve as the spacing elements, in the manner indicated in the drawings. The plates, 1, are also provided,preferably with aplurality of bolt holes, 5, the bolt holes of the several plates being in alignment when the plates are assembled, so that the plates may be temporarily united by suitable bolts, one of which is indicated at 6 in Fig. .1, for example. 7 represents a tubular member of cylindrical or other preferred form corresponding with the form of the apertures in the plates and being sufficiently smaller in cross section than said apertures, so as to form a space, indicated at 8, betweenthe inner face of the spacing members, 2, of the assembled plates, and the outer surface of the tube.
I find it convenient to assemble the desired number of plates to form a unit of desired length, in the manner illustrated in Fig. 1, upon a removable base plate, indicated at 9, which is provided with a central aperture, 10, conforming to-the exterior surface of'the tube 7, and having an annular recess, 11, to accommodate the spacing member, 2, of the lowermost plate of the series, the bottom of said recess forming in effect the bottom of the mold of which the thin tubular member, 7, is the inner mold wall, and the spacing elements of the plates con- The spacing elements, 2, when formed integrally with the plates may be made of slightly smaller diameter at the ends remote from the body of the plate. so as to enter to a greater or less extent, as desired, the upper portion of the next adjacent spacing member, thus enabling the plates to be nested to a certain extent. This arrangement will assist in preventing any leakage of the molten metal. but it is not essential, and the spacing mem- Ill bers, 2, may be of uniform diameter throughout and have their lower ends abut directly against the main body of the adj acent plate, so as to bring the spacing members into direct alignment, if desired. The
' before the casting operation.
bottom supporting plate, 9, will also be provided with recesses or pockets, 12, to accommodate the auxiliary spacing elements, 4, of the lowest plate of the series, if desired, and will also be provided with means,as threaded apertures, 5, one of which is shown in Fig. 1, for engaging threaded portions, 15a, of the bolts, 6, which clamp the plates in assembled relation. I prefer to provide the thin tubular member, 7, at each end with an internally threaded collar indicated at 13, which may be and preferably is pressed therein or otherwise connected therewith. It will be understood that the built up structure illustrated in Fig. 1, may be assembled in quantity and may be readily transported from the place of assembly to the place where the casting operation is to be performed.
The central tubular member forming the inner mold wall is held in centered position in the apertures of the plates by the inwardly extending lugs, 3, if they are provided. It will-be understood, however, that the plates alone may be built up, secured together in the manner described, and transported to the place where the casting operation is to be performed, and that the central tubular member, 7, may be inserted just It will also be understood that the tubular member may be held in centered relation to the plate apertures by the aperture, 10, at the bottom of the supporting plate, 9, and by any suitable means engaging the upper end of the tubular member, and held in fixed relation with the plates, if it is desired to omit the lugs, 3.
I prefer to heat the built up structure preparatory to or during the casting operation. Obviously this can be done by passing the built up structures through a heating chamber on a suitable conveyor, on their way to the point of casting. I find it convenient, however, to provide a heating burner, 14, or burners, below the lower end of the tubular member, which presents an uninterrupted passage for a heating medium such as the products of combustion from said burner, the heating medium passing from the bottom upwardly, while the cast metal will flow from the upper part of the built up structure downwardly, thus preventing the casting metal from cooling too rapidly, and insuring the formation of substantially uniform castings. The cast metal, which is preferably a metal or alloy having a lower melting point than the metal forming the inner tubular member and the spacing elements, is poured into the annular space between the inner and outer mold walls, and upon cooling forms a substantially' cylindrical cast metal body,which is firmly. united to both the inner tubular member, 7, and the spacing members of the plates, the centering lugs, 3, of the plates, if they are employed, being firmly anchored and embedded in the bodyof the cast metal. I prefer, as before stated, to apply the heating medium to the interior of the tubular member, 7, during the pouring of the. cast metal, to facilitate the casting operation, and'in this'way acomparatively thin cast metal body or wall may be formed, it being only necessary that this cast' metal wall, as reinforced by the inner tubular member, 7, and the spacing members, shall have sulficient strength to support the unit. I am thus able to obtain the necessary strength for the tubular member of the unit, with a comparatively thin body of cast metal, rigidly uniting the inner tube and the plates and their spacing elements into an integral structure; In this way the unit can not only be made lighter than would be the case where the thick cast wall is formed which alone must provide practically 'all the strength required for the tubular member of the unit, but the thinning of the cast wall greatly facilitates the exchange of heat between the tubular member and the plates and fins. Furthermore, the inner tube element, which is preferably made of copper or other metal having high heat conducting properties, can be made very thin, comparatively, as it is not required to furnish the strength for the tubular member, this also increasing the conductivity of the unit and keeping down the cost of the same.
The bond between the cast metal and the tubular member, plates and spacing members, will depend upon the character of the metals employed. For example, the bond may be formed by the shrinkage of the metal in cooling, in which case'the surfaces will be held in mechanical contact in a man ner similar to mechanical clamping. On the other hand, there may be a direct adhesion between the cast metal and the contacting portions of the tube, and plates, analogous to brazing or soldering, and in some instances, as where the cast metal is of the same or nearly the same type, as the metal from which the plates are made, and projecting portions of the plates or the spacing elements thereof, project into the cast metal, there may even be fusion, that is to say union analogous to welding between the cast metal and portions of the plates or spacing members. In such cases, however, it may be desirable or necessary to support the inner and outer mold walls, as by embedding them I in sand, for example, or otherwise to previded each with a single tubular conducting passage, units may be formed in like manner with two or more tubular passages, if
desired. I prefer, however, to form them as shown, as it enables the use of plates of comparatively small dimensions, which permits them to be stamped, pressed or formed from scrap plate or other waste material with corresponding economy of production.
For the cast metal body I may employ aluminum or an alloy of the same or any other desired fusible metal having the necessary characteristics to enable it to be poured between the tube, and the exterior mold wall formed by the plates and their spacing elements, and uniting the tube, cast metal body and plates and spacing elements, into a substantially integral body. Fig. 4 shows one of the completed units, the tube member being shown provided at each end with the internally threaded collars, 13, for the attachment of pipe connections, but it is to be understood that the connectin pipes may be attached in any other desire manner. The cast metal body, which unites the tube member and plate and spacing members therewith, to form the integral structure, is indicated at 16, the inwardly projecting portions, 3, of the spacing elements being shown embedded in the cast metal body. In some instances, if desired, plain apertured finishing plates or end plates, indicated at 17, may be provided at each end of the unit and secured to the unitary structure, by being pressed over projecting portions of the tube, 7, or of the collars, 13, or they may be held in position in any other desired manner.
In Figs. 5 and 6, in which the corresponding parts are given the same reference numerals with the addition of 100, I have illustrated a modified form of plate, 101, which in this instance is rectangular in form, provided with a central aperture, 101a, and annular spacing element, 102, surrounding the same, two parallel edges of each plate being bent angularly on the same side of the plate as the spacing element, 102, to form lateral flanges, 104, constituting the auxiliary spacing elements, and the marginal edges of the spacing elements, 102, are also shown as provided with the inwardly extending centering projections, 103, to engage and center the tube element in the built up structure. The plate, 101, is also shown provided with two oppositely disposed bolt holes, 105, to receive the clamping bolts for clamping the plates in assembled relation in the manner indicated in Fig. 1.
\Vhile I have shown a heating burner for heating the interior of the tube element, any other suitable heating means may be employed.
What I claim and desire to secure byLetters Patent is:
ing the only connection between said plates and said tube.
2. A heat exchanger comprising a thin 'metal tube, a plurality of parallel plates surrounding the same and provided with spacing elements located between said plates and surrounding said tube, and an integral cylindrical reinforcing cast metal body be tween said tube and said spacing elements, connecting said tube, plates and the spacing elements, therewith, to form an integral structure.
3. A heat exchanger comprising a thin tube, a plurality of apertured plates provided with integral spacing elements surrounding the apertures therein, and an integral cylindrical reinforcing cast metal body located between said tube and said spacing elements, and uniting the tube, plates and spacing elements therewith, to
orm an integral structure.
4. A heat exchanger comprising a thin metal tube, a plurality of apertured plates surrounding said tube, and provided with' integral spacing elements surrounding the tube and having inwardly extending separated projections engaging the tube, and an integral cylindrical reinforcing cast metal body located between the spacing elements and the tube, and having said separated projections of the plates embedded therein, and unitingthe tube, spacing elements and plates therewith, to form a unitary structure.
5. A heat exchanger comprising a thin metal tube, a plurality of spaced parallel plates disposed perpendicularly to the axis of said tube and extending outwardly therefrom, and an integral cylindrical reinforcing cast metal body interposed between the outer surface of said tube and the inner edge portions of said plates, united to said tube and to said plates and forming a unitary structure, said cast metal body forming the ontly connection between said plates and said tu e.
6. A heat exchanger comprising a thin metal tube, a plurality of parallel plates disposed perpendicularly to the axis of said tube and extending outwardly therefrom, and plates having separated inwardly extending centering projections engaging said tube, and an integral cylindrical reinforcing cast metal body between the outer surface of said tube and the inner edge portions of said plates, united to said tube and plates and enclosing said centering projections and forming a unitary structure.
7. A heat exchanger comprising a thin metal tube, a series of. parallel plates of sheet metal having apertures substantially surrounding said tube but of greater diam- LOUIS PREVOST WHITAKER.