US 3805889 A
A unitary plate type heat exchanger structure in which stacked manifold segments, tube sheets, continuous nose pieces and strip fin material are joined together as by brazing to form a one-piece construction with integral manifold. The tube sheets combine with the manifold segments and with the nose pieces in a manner facilitating assembly and obviating separate attachment of a manifold means. The parts and particularly the tube sheets are made for a self-fixturing relationship in the brazing or other joining process.
Claims available in
Description (OCR text may contain errors)
United States Patent [191 Coolidge [4 1 Apr. 23, 1974 PLATE TYPE HEAT EXCHANGER  inventor: Anson S. Coolidge, Centerville, Ohio  Assignee: United Aircraft Products, Inc.,
Dayton, Ohio  Filed: May 4, 1973  App]. No.: 357,488
 US. Cl 165/153, 165/130, 165/172  Int. Cl. F28b 9/26  Field of Search 165/130, 131, 148, 152,
 References Cited UNITED STATES PATENTS 2,169,993 8/1939 Booth 165/153 2,596,008 5/1952 Collins..... 2,858,112 10/1958 Gerstung 165/153 3,104,701 9/1963 Jacoby, Jr 165/148 Primary Examiner-Manuel A. Antonakas Assistant Examiner-Theophil W. Streule, Jr. Attorney, Agent, or Firm-J. E. Beringer 57 ABSTRACT A unitary p1ate type heat exchanger structure in which stacked manifold segments, tube sheets, continuous nose pieces and strip fin material are joined together as by brazing to form a one-piece construction with integral manifold. The tube sheets combine with the manifold segments and with the nose pieces in a manner facilitating assembly and obviating separate attachment of a manifold means. The parts and particularly the tube sheets are made for a self-fixturing relationship in the brazing or other joining process.
14 Claims, 7 Drawing Figures PATENTED APR 2 3 1974 EZZEHHHU FIG-3 PLATE TYPE HEAT EXCHANGER BACKGROUND OF THE INVENTION This invention relates to platetype and particularly plate and fin type heat exchangers.
Engineers and designers in the heat transfer arts turn frequently to plate and fin type heat exchangers, especially in applications coupling the need for high performance with size or volume limitations. Plate and fin heat exchangers are not, however, inherently inexpensive of construction. There are usually a large number of different parts requiring careful assembly and handling. Also, at least one of the fluids put through the heat exchanger will usually require manifolding and it is conventionally the practice to build a heat exchanger core, braze or otherwise join the parts together, and then weld or bolt separate manifold members to selected core faces. The separate manifold member, separately applied, obviously increases the total cost of the heat exchanger and affects the reliability factor in introducing a further part or parts and in adding to the number of joints required to be sealed.
In the prior art, therefore, plate and fin heat exchangers have seen their greatest use in aircraft and like installations where costs involved in their fabrication can be justified on the basis of performance results measured against size and weight considerations. They are not unknown in what may be regarded as commercial or industrial usage but appear less frequently in these applications. 1
SUMMARY OF THE INVENTION The present invention extends the benefits of plate and fin exchanger construction to a greater range of heat transfer applications. Also, the proposed construc-' tion lends itself to mass production concepts and is highly flexible in configurations that can be achieved and in heat transfer specifications that may be met. Reliability is improved and at the same time fewer process steps and component parts are required. There is contemplated a manifold means which is integrated into the core structure in a manner to make possible an all brazed heat exchanger, that is, one in which the core and manifold are constructed as a part of a single assembly process and in a single brazing or like process are made into a unitary structure. The need for separate manifold members-separately welded to the-core, is eliminated. According to a feature of the invention, parts are self-fixturing. Problems of alignment and of retention of one part relative to another preparatory to and during the brazing process are lessened. The invention is particularly characterized in 'a structural sense, by a use of manifold segments, tube sheetsand continuous nose pieces uniquely interrelating one with another to form segregated flow passages, including manifold chambers at opposite ends of one set of flow passages. The construction does not require but lends itself advantageously to a use of extrusion parts as the manifold segments or nose pieces, or both. Devices made according to the invention may variously be used as gas to gas, gas to liquid or liquid to liquid heat exchangers in any of many heat transfer applications but particularly those having low cost and high performance requirements. I
To provide a heat exchanger construction characterized as in the foregoingis an object of .the invention.
Other objects and structural details of the invention will appear from the following description, when read in conjunction with the accompanying drawings.
illustrated embodiment of the invention;
FIG. 2 is a view in end elevation, partly broken away,
of the heat exchanger of FIG. 1;
FIG. 3 is a view in longitudinal section, taken substantially along the line 3--3 of FIG. 1;
FIG, 4 is a detail top plan view of a tube sheet comprised in the heat exchanger structure of the illustrated embodiment;
FIG. 5 is a view in side elevation of the tube sheet of FIG. 4;
FIG. 6 is a view in end elevation of the tube sheet; and
FIG. 7 is a detail view in horizontal section of a manifold segment comprised in the illustrated embodiment of the invention.
Referring to the drawings, the invention has for illustration purposes been shown in an after cooler embodiment suitable for use in an industrial air compressor or the like to reduce the temperature of compressed air by flowing it in heat transfer relation to a relatively cooler, for example ambient, air. The heat exchanger structure of the illustrative embodiment accordingly is a gas to gas, or in the present instance an air to air, heat exchanger. As will be more clear hereinafter, however, the structural principles involved are independent of the fluids put through the heat exchanger, only proportions of the parts being affected.
Opposite ends of the embodiment structure are represented, in part diagrammatically, by core sheets 10 and 11. These are flat, plate-like elements made-suffic'iently strong to withstand fluid pressures which may be applied to interior sides thereof. Either one or both of the core sheets 10 and 11 may have openings adjacent their ends over which fluid inlet and outlet bosses are mounted. In the illustrated instance, core sheet 10 is without any such openings while core sheet 11 has end openings 12 and 13 over which an inlet boss 14 and an outlet boss 15 are respectively mounted.
In adjacent parallel relation to the core sheet 10 is a pair of longitudinally spaced apart manifold segments 16. Correspondingly positioned with respect to core sheet 11 is a longitudinally spaced apart pair of like manifold segments 17. Intermediate the pairs of segments l6 and 17 and longitudinally-spacedtherefrom as well as longitudinally spaced from one another are additional pairs of manifold segments 18, 19 and 20. The segments 18, 19 and 20 are identical to one another and are substantially identical to manifold seg ments l6 and 17 except for having a greater thickness, or as it is usually expressed, except for having a greater height. Disregarding the matter of height, which varies in accordance with the required height of related airflow passages, each manifold segment 16-20 is a flat plate-like element. It is arigid element having a thickness or height detennining the height of a related airflow passage and includesa body portion 21. In the latter is a through, half round opening 22. The body 21 has a rounded extremity conforming approximately to the curved portion of, opening 22. At what may be regarded as its base portion it is formed with a transverse bar means 23 closing opening 22. At opposite ends of bar means 23 are short length marginal protrusions 24 effectively defining between them a recess 25. At one side thereof the body 21 is formed with an upstanding tongue 26 having a bent over extremity 27. At least in the case of manifold segments 16 and 17, the tongue 26 is formed with an aperture 28 and extremity 27 with an aperture 29. The tongue means 26-27, with its apertures 28-29, serves a handling and attachment function, as is obvious.
Between adjacent pairs of manifold segments are superposing tube sheets 31 which are or may be identical to one another. The sheets 31 have a thin, flat construction and are or may be generally rectangular with straight parallel sides and ends which are rounded substantially in correspondence with the rounded shape of manifold segments 16-20. in at least one of its opposite ends each tube sheet has a half round opening corresponding substantially to half round opening 22. In the instance illustrated in FIG. 4', the tube sheet has such half round openings at each end, the openings being there indicated at 32 and 33. The curving marginal edge of tube sheet opening 32 is turned upward to define a lip or flange 34. A similar lip or flange 35 is formed on the half round opening 33, both flanges 34 and 35 projecting upward out of the plane of the tube sheet in the same direction or to the same side of the sheet. At its straight parallel sides, marginal edges of each tube sheet are turned over to define lips or flanges 36 and 37, these projecting to the opposite side of the tube sheet or in a direction opposed to the direction in which flanges'34 and 35 project. i
The tube sheets 31 position in pairs between adjacent pairs of.manifold segments. Between each positioned pair of tube sheets is a nose piece, here separately designated at 38, 39, 40 and 41. The nose pieces 38-41 are identical. Each has an outline configuration substantially corresponding to that of a tube sheet 31; Each piece 38-41, however, has a continuous strip form, being comprised of a rod-like or bar-like member bent to a race track configuration with abutting ends suitably joined together. The piece is square-like in cross section to have flat sides paralleling the tube sheets 31 and faces of the manifold segments. What may be considered a body portion of each nose piece is comprised of straight parallel sides 42 and 43. Ends 44 and 45 are curved in correspondence with curved portions of the manifold segment bodies and with curved extremities of the tube sheets 31.
Completing the heat exchanger structure are fin strips 46 and 47 which have a height corresponding respectively to heights as defined by related manifold segments and by nose pieces 38-41. The-fin'st rips are thin metallic or like sheets which in a crimping or'likeprocess are formedto the'convoluted configurationillustrated. They-are designed to occupy fluid flow'passa'ge's within the heatexchanger andhave' adual purpose in that they provide extended or secondary heat transfer surface and at the same time act as ties between opposing passageway walls for greater structural integrity.
In a structural sense, afeature of the invention resides in that the manifold segments 16-20 may be formed by an extrusion process in which an extruded section has segments cut on in lengths corresponding to desired segment heights. The nose pieces 3841 may likewise be extrusions, with an extrusion of desired length being cutoff and formed to the race track configuration illustrated. All parts are made of a material or materials readily bonded together in a brazing or like process. It will be understood in this connection that between parts which are to be joined together braze material is inserted, as for example, by a suitable cladding of juxtaposed surfaces. In the construction of a heat exchanger substantially as illustrated, previously formed parts are brought together and in effect stacked in the relationships illustrated. So stacked or so assembled, a heat exchanger is held in a fixture and placed in a furnace or otherwise subjected to temperatures and environments whereby contacting parts are joined to one another by means constituting a seal and a bond.
In the assembly process, bosses l4 and 15 are overlaid by a core sheet '11, with openings 12 and 13 in the core sheet aligning with respective through openings in the bosses. There is then placed on the core sheet 11 a longitudinally spaced pair of manifold segments 17 arranged in a manner opposed to one another so that the tongues 26 project outwardly beyond the ends of the core sheet. Between the oppositely facing inner ends of the manifold segments and on top of the core sheet is placed a fin strip 46, opposite ends of which are received in respective segment recesses 25. Next a tube sheet 31 is placed over the manifold segment 17 and over the installed fin strip 46 in a position toalign its openings 32 and 33 with the half round openings 22 of the manifold segments. The orientation of the tube sheet is such as to place lips or flanges 34 and 35 in a facing relation to the manifold segments, with such lips or flanges being received immediately within the curving marginal edge of segment openings 22.20ver the tube sheet 31 there is placed a nose piece 41 in a manner substantially aligning curved extremities thereof with the curved ends of the tube sheet and with the curved ends of manifold segment bodies 21. Afin strip 47 is placed within the nose piece 4] to seat on an underlying wall of tube sheet 31. The stripv47 has a width to extend from side 42 to side 43 of the nose piece and has a length to be substantially coextensive with such sides. The result is to leave at opposite ends of the nose piece half round openings 48 and 49 which correspond to and substantially align with tube sheet openings 32 and 33. In mounting nose piece 41 to an underlying tube sheet 31 sides of the nose piece are substantially embraced by the side flanges 36 and 37 on the tube sheet.
An installed nose piece is overlaidby another tube sheet 31, the orientation of which is the reverse of the one underlying the nose piece. Side flanges 36 and 37 of the overlying tube ,sheet accordingly also embrace the nose piece'41 and project toward flanges 36 and 37 of the underlying tube sheet. I On top of the described overlying tube sheet is placed a pair of longitudinally spaced apart segments 20,,the openings 22 of which interengage with tube sheet flanges 34 'and35. The segments-are accordingly'self aligning with res'pect to underlying parts and openings 22 therein substantially register with underlying openings 48-49 and 32-33as well as with openings 22 of an underlying manifold. segment. Fin strip means 46 is placed between the manifold segments 20 andhas a self-locating engagement in recesses -25 thereof. In the illustrated instancethis fin strip means takes the form of two fin strips 46 separated by a fin splitter sheet 51. The use of a pair of fin strips 46 and an interposed splitter sheet 51 is merely for the convenience of being able to use fin strips of standard heightnlf desired, a single fin strip having a height substantially corresponding to the thickness or height of the manifold segments could be used.
The installation of the manifold segments 20 is followed by overlying tube sheets, nose pieces and other manifold segments until a heat exchanger structure of the desired height is achieved whereupon the core sheet 10 is mounted on the last installed pair of manifold segments as an end closure. Then, while the assembly of parts is gripped in a jig or fixture it is placed in a brazing furnace or otherwise heated in such manner that brazing material between contacting parts flows.
When allowed to cool, the parts are unitarily joined together and all joints between the parts are sealed. in this connection, it is to be noted that the manifold segments and the nose pieces have extensive contact with the tube sheets so that the heat exchanger structure at its end is strong and self-supporting. The long bearing contact, additionally, makes for strong secure joints. Between the manifold segments, the tube sheets are sustained at their peripheries by contact with the relatively broad surfaces of the nose pieces and between side edges of the nose pieces are supported by the convolutions of fin strips 46. The latter have a density in terms of convolutions per unit of measure appropriate to heat transfer objectives and pressure drop limitations and desirably have a height to be lightly compressed by the assembly of the heat exchanger. Accordingly, the peaks and valleys of the convolutions bear against opposing tube sheet walls and are soundly brazed thereto. Good heat conductivity is promoted and a beam-like structure between tube sheet walls established.
A completed heat exchanger according to the illustrated embodiment of the invention has two sets of flow passages. The passageways of one set, as occupied by fin strips 46, is open from side to side of the heat exchanger and there will ordinarily be a ducted or controlled flow of cooling air for delivery to one side of the heat exchanger for flow through and beyond the described open passageways. These described passageways, which are in the illustrated instance cooling passageways, are identified as passageways 52. The other set of passageways, as occupied by fin strips 47, are in a transverse or cross flow relation to the passages 52 and provide for flow of a confined fluid. These passageways, identified as passages 53, are closed at their sides by side edges 42 and 43 of the nose pieces and are closed at top and bottom by blank walls of the tube sheets 31. At their ends passageways 53 communicate with nose piece openings 48 and 49 and accordingly open into what may be termed interior manifold chambers. The latter are created by the several registering openings in manifold segments 16-20, nose pieces 38-41 and tube sheets 31 and constitute chambers in common communication with the ends of passageways 53 but in a segregated relation to passageways 52. The latter, it will be noted, are at their sides closed by the bar-like portions 23 of the manifold segments. These bar-like portions accordingly serve as channel members closing the sides of passageways 52 while the sides of alternating passageways 53 are closed by the sides of nose pieces 38-41.
Communication with the respective manifold chambers is through the bosses 14 and 15. A fluid under pressure entering the heat exchanger by way of boss 14, for example, flows into-and 'fills the communicating interior manifold chamber, flows across the heat exchanger by way of passageways 53 to the interior manifold at the other end of the heat exchanger structure and exits the device by way of the other boss 15. If, at the same time, a fluid of different temperature is caused to flow through the passageways 52 a transfer of heat from the fluid of higher temperature to the fluid of lower temperature takes place, there being involved a conduction-convection process in which the fin strips 46 and 47 perform as extended heat transfer surface. It will be recognized that the invention lends itself to a utilization in various forms in accordance with heat transfer specifications to be met and physical considerations to be adapted to. For example, a heat exchanger assembly can be made to any desired height, incorporating any number of fluid flow passageways, merely by stacking a greater or lesser number of manifold segments and associated parts one upon another. The manifold segments may, as has been indicated, be cut to various heights depending upon the desired height of the fluid flow passageways to be defined between spaced apart pairs of segments. They are, moreover, structural members which lend inherent strength and rigidity to the heat exchanger structure and may variously be used. The incorporation of mounting tongues 26 therein has been noted. Also, the bodies 21 may be selectively bored if desired to establish inlet and outlet connections which may function additionally to or in lieu of the bosses 14 and 15. The latter, as has also been noted, may variously be positioned in accordance with system connections to be made. For example, either the inlet boss 14 or the outlet boss 15, or both, might be mounted on the opposite core sheet 10.
Additionally, the structure lends itself readily to use as a single pass heat exchanger, which is the embodiment illustrated, or as a'multi pass heat exchanger. in the latter instance, it is required merely to incorporate into the heat exchanger one or more tube sheets 31 having an opening 32 or 33 at only one end thereof.'
Thus, fluid entering a manifold chamber at one end of the heat exchanger and finding an adjacent tube sheet to be closed is required to flow reversely to the other manifold chamber whereby to complete its travel through the several passageways 53in a zigzag pattern. A designer accordingly has available to him the option of either a single pass or multiple pass heat exchanger with but a slight change in selected parts.
The illustrated heat exchanger is disclosed as having a somewhat eliptical shape which may be found useful and convenient of application. It can, of course, assume other configurations, including one in which the manifold segments are more square-like with openings 22 therein of a corresponding configuration or shaped in any other manner which might be found desirable in the fonning of a manifold chamber and in defining of a channel closing the passageways 52 at the sides.
The core sheet 10 provides a broad flat surface adapting to fit flushly to companion structure and providing a particularly appropriate surface whereby another, like heat exchanger may be joined thereto in a modular concept. For example, two heat exchanger units constructed substantially as shown, could be joined together in a back to back relation using the same flowof ambient or ducted air for cooling purposes and with the fluid tobe cooled being in one instance a high temperature air and in the other instance a hydraulic or lubricating oil or the like. The two units would be substantially identical, with the cooling air passages being selected as to height in accordance with need by a selecting of manifold segments of appropriate height. The nose pieces 38-41 are also variable of height and in the case of an air to liquid heat exchanger unit as described would have usually a somewhat lesser height than here illustrated.
The protrusions 24 on the manifold segments, the lips or flanges 34 and 35 on the tube sheets 31 and the side flanges 36 and 37 on the tube sheets are a part of a selffixturing concept. The parts in their assembly become inherently self-aligning or self-fixturing, greatly reducing the need for human skill in locating the parts during assembly and obviating many of the problems occurring in handling a completed assembly preparatory to and during the brazing process.
The openings formed in and provided by the manifold segments may with respect to the heat exchanger structure generally be regarded as end enclosures. The nose pieces of race track configuration have a spacing function and may be regarded as a means spacing apart adjacent pairs of tube sheets.
The invention has been disclosed with respect to a particular embodiment. Structural modifications have been discussed and these and others obvious to a person skilled in the art to which this invention relates are considered to be within the intent and scope ofthe invention.
What is claimed-is: I
l. A unitary plate type heat exchanger structure in- 4. A plate type structure according to claim 3, characterized by fin strip means positioned in said other flow paths and having a self-fixturing interengagement with said manifold segments, said means for uniting said assembly serving simultaneously to join said fin strip means at least to overlying and underlying tube sheets.
eluding at each of opposite ends thereof a plurality of manifold segments stacked one upon another in a superposing relation and each forming an end enclosure, a pair of tube sheets positioning between corresponding adjacent pairs-of manifold segments at each end and at least certain of said tube sheets having end openings aligning with end enclosures of said manifold seg-. ments to define therewith intercommunicating manifold chambers, means for spacing apart at least certain adjacent pairs of said tube sheets and defining therewith flow paths intercommunicating manifold chambers at opposite ends of the structure, tube sheets positioning between said manifold segments and said spacing means seating flushly thereto, and means for uniting the .assembly comprising said manifold segments, said tube sheets and said spacing means into a one-piece unitary structure. 3
2. A plate type structure according to claim 1, wherein said spacing means has a continuous loop-like configuration and cooperates with said tube sheets in closing sides of said flow paths, opposite ends of said spacing means defining enclosures aligning with the end enclosuresof said manifold segments and communicating therewith through saidend openings in said tube sheets, saidenclosures defined by said spacingmeans being in acommon plane with and communicating with the-ends ofrespective flow paths." 5
3. A plate type structure according to claim 2, wherein corresponding manifold segments at opposite ends of said structure are in a common plane and longitudinally spaced apart, said segments having transverse bar portions cooperating in defining said end enclosures and definingwith said tube sheets other flow paths orienting in a cross flow relation to the first said flow paths.
5. A plate type structure according to claim 4, characterized by other fin strip means in the first said flow paths, said means for uniting said assembly serving simultaneously to join. said other fin strip means at least to overlying and underlying .tube sheets.
6. A plate type structure according to claim 5, characterized by top and bottom closure sheets mounting to uppermost and lower most manifold segments and defining therewith and with respective adjacent tube sheets uppermost and lower most of said other flow paths, and external boss means mounted to at least one of said closure sheets to communicate therethrough with interior manifold chambers for inflow and outflow of a fluid to pass through the first said flow paths.
, 7. A plate type structure according to claim 6, wherein said other flow paths-are open at their ends for passage of another'fluid therethrough, said fluids being in he'attransfer relation through said tube sheets with 'said fin strip means providing extended heat transfer surface and acting as ties between adjacent tube sheets.
8. A plate type structure according to claim I, wherein said tube sheets have a self-fixturing interengagement with adjacent manifold segments.
9. A plate. type structure according to claim 1, wherein said tube sheets have a self-fixturing interengagement with adjacent spacing means.
10. A plate type structure according to claim 1, wherein said tube sheets have a self-fixturing interengagement with said manifold segments and with said spacing means. j
s 11. A plate type structure according to claim 1, wherein each of said tube sheets has upturned lip means at the location of said end opening therein received in the end enclosures of manifold segments adjacent thereto for.self-fixturing purposes, adjacent tube sheets being oriented reversely of one another.
12. A plate type structure according to claim 11, wherein each of said tubesheets has other oppositely directed lip means extensible into an overlapping relation to spacing means adjacent thereto for self-fixturing Purposes. 5
13. A plate type structure according to claim 1,-
wherein all said tube sheets have end openings therein whereby said manifold chambers are continuous at each end of saidstructure, flow fromone end to another of said structure through said flow paths occurring in a single pass, said chambers communicating,
with the exterior, of said structure for in-flowand out- .chambers communicating with the exterior of said structure for the in-flow and out-flow of a flowing fluid.