US2526135A - Gas regenerator - Google Patents

Description

Qct. )17'9 H950 J. R. HOLMES Erm.

GAS REGENERATOR Filed April l2, 1946 '3 sheets-sheet n d c/a/r, W @www l h//nl v u l., a Q

J- R'HoLMEs ET AL GAS REGENERATOR 3 Sheecs-SheefgI g Filed `xpril 12, 1946.

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'l GAS REGENERATOR med April 12, 194e sheets-sheets Patented Oct. 17,7l950 GAS REGENERATOR l I John Ralph Holmes, Howard F. May, and John.

R. Hayden, Lockport, N. Y., assgnors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application April 12, 1946, Serial No. 661,482

1 Y This invention relates to heat exchangers of the type having a multiplicity of narrow long passages, certain of which provide flow paths for a fluid of different temperature than the iiuid flowing through other of the passages whereby transference of heat between the fluids occurs through the walls of the several passages.

The structure is especially adapted for handling gases under moderate pressures and neither intensely hot nor intensely cold and which fac- A- tors make feasible the use of relatively lightweight and thin walled sheet metal core units. By special design a standard unit has been devised to consist of a number of spaced like tubes inexpensively formed of simple easily shaped ribbon stock or sheets brazed together with indirect radiating surfaces afforded by longitudinally corrugated separators which brace the tube walls and subdivide both the interior of the tubes and the spaces between neighboring tubes. A case made up largely of vparts of standard size and shape can be built up to enclose one or several ofthe standard core. units arranged side by side as a core assembly, the number of units to be employed for any given installation being dependent upon the volume of gas to be handled and the temperature change desired.

The casing in addition to confining and defining llow paths for the gases exteriorly of the tubes protects assembly and is joined thereto through relatively stiff tube spacers at opposite ends of the core so that the stili spacers suspend the thin tube walls within the heavy protective casing. Since the thin metal of the core becomes hotter than the metal of the outside casing there is a diierential in expansion which needs tof be accommodated to free the parts from undue stress. Because the casing interior should be fluid tight a satisfactory vform of connection between the core and the casing is here disclosed as a fixed and sealed connection at the one end or bottom of the core and a sealed expansion joint at the opposite end or top of the core. A preferred embodiment of the expansion joint is in the form of a peripheral ring surrounding the core and extending laterally therefrom for connection at opposite edges withA the core and casing respectively. It includes superposed strips, one of which is a flat perforated flexible leaf to provide lateral strength and the other of which is an imperforate bowed cap to withstand internal pressure.

For an exchanger whose case has the `approximate dimensions of 100 inches long, 50 inches wide and 60 inches high, and which operates the more fragile walls of the core y 8 Claims. (C1. 257-245) under an internal pressure of approximately 80 pounds per square inch. the expansion joint needs to be designed to take care of about .048 inchY differential between the core and the casing at full load. Thus it must be strong enough to hold the case laterally in line withthe core and resist a load of 80 pounds per square inch without creating excessive stress in the point but it must be flexible enough so that deflection of the metal does not excessively stress the joint and-so that minimum load during expansion is placedon the welded joint between the bottom of the case and the core.

For a more detailed explanation reference will be made to the accompanying drawings wherein Figure 1 isa perspective viewA of the interchanger assembly; lFigure 2 is a perspective view ena larger scale and shows a fragment of the assembly at an upper cornerv with parts in section; Figure 3 is a Vfragmentary transverse vertical section, as on line 3--3v of Figure l; Figure 4 is a fragmentary horizontal sectional view of the f assembly; Figure 5 is a detail section, as on linev 5--5 of Figure l; Figure 6 is a transverse section illustrating two standard core units'placed one ahead of the other and Figure 7 is a detail section on a large scale to illustrate tube wall and separator relation.

Referring to the drawing, Figure 1 illustrates .a four sided casing having near the bottom on one side an inlet manifold I and near the top of the opposite side an outlet manifold 2, both manifolds terminating in attachment fianges'ior connection with suitable conduits for heat ex-Y change air or gas. Extending vertically through the casing are a series of open ended tubes or pipes held apart by end spacers which close the interior of the casing. Suitable conduits, if desired, may be attached to the top and bottom of the casing for the air or gas which is to pass through the tubes.

Each narrow long tube 3, vas bestl seen in Figure 4, is formed by a pair of lmetal ribbons, one

pressed to channel shape with outturned end flanges to be received within reversely bent portions along opposite edges of the companion ribbon which otherwise is a simple flat plate'. The

' tubes arepreformed individually andhave their edge seams brazed together.- Inside each tubev and extended'the full lengthv thereof is a longitudinal corrugated or zigzag separator 4 which stiffens the tube by bracing the walls against inwardV collapse and subdivides the interior tube space 3a into `a large number of small air cell passages withY maximum exposure of heat transfer surface area. On the outside tube walls are additional separators 5, also corrugated longitudinally but of half size in relation to tube spacing. In cooperation with adjacent half centers on neighboring tubes the intervening space 3b between adjacent tubes 3 is subdivided into numerous passages with an abundance of surface radiation areas for assisting heat transfer through the tube walls.

As will be noted in Figure 6 the half centers 5 extend throughout the intermediate portion of the tubes but do not run the full length of the tubes as do the tube interior full centers 4. They terminate on diagonal lines-in spaced relation to the tube ends and closer to one tube end than the other. Deflectors or vanes 6 carried by a mounting strip "I may be interposed between the tubes along the inclined ends of the separators 5 to reduce the static loss of the right angle turn and insure a more equalized distribution of air through the passage subdivisions. Similar vanes, although not shown, may be provided at the opposite or outgoing end of the separators 5.

At opposite ends each tube is embraced by a heavy collar or spacer afforded by bands 8-8 which seal or close the casing space between the tubes and cooperate to suspend the tubes and relieve them from strain in assembly and use. These spacer or header bands 8--8 are brazed to the tube walls and afford the means by which the several tubes are joined together and to the casing. For convenience of manufacture each band is made in sections consisting of a straight portion on one side of the iiat tube and a channel portion on the other'side of the flat tube with the channel portion having the side legs 8a against which short length ller pieces 8b are laid to complete the end closing of the casing' exteriorly of the spaced tubes 3. About twenty of the tubes are joined by welding together the opposite end collars to form thereby a core unit. In the drawings ten of the units are shown assembled in two banks of ive units each, those in each bank being placed side by side. In the front or A bank as seen in Figure l, the core units are designated AI 'to A5, inclusive, and, in the rearV or B bank the core units are designated BI to B5, inclusive. With the standard construction of the parts making up the individual units those of one bank may be turned upside down in relation to those in the other bank whereby the diagonal endings of the half centers 5 5 of the front and rear banks will be in substantial align-- ment for cooperation with each other and with the inlet and outlet connections, as seen in Figure 6.

It will be noted that a central plate or Vertical splitter S runs between the two banks of tubes and connects with the end plates II] and that additional splitter plates I -I I extend outwardly on cach side at right angles to the main splitter S to connect with side plates I2--I2. Abutting edges of the several splitter plates are welded together and to the side and end plates so that the plates cooperate to box in each core unit and thereby lend reinforcement against internal pressures. rIro strengthen the several joints and give more ruggedness to the assembly reinforcing strips I3V of standard angle section or the like may be added, particularly at the exterior corner joints.

It will be noted further that the splitter plates, the casing and the lower stiffening spacers 8--8 of the core are all welded together at the bottom of the assembly but that the core units are free at the top except for an expansion joint connection afforded essentially by superposed thin metal strips or bands I4 and I5 which surround or extend continuously around the sides of the casing in the form of endless rings projected laterally therefrom. The opposite edges of the strips I4 and I5 are welded to a rib I6 rigid with the casing and to a rib` Il fastened to the upper core tube spacers 8. The upper strip I4 is imperforate and upwardly curved in section while the strip I5 is perforated and at and the two strips cooperate in giving lateral stability with suicient vertical exbility to accommodate relative expansion of the core in respect to the casing. The perforations, one of which is illustrated at I8 in Figure 2 and which'are spaced apart throughout the fiat strip 55,. and free the strip from internal pressures which might buckle or otherwise interfere with its function of lateral stability and vertical Iiexibility while the bowed imperforate strip being inherently more exible and independent of lateral stability properly seals the joint against leakage.

Air to be heatedenters the enclosed casing through the inlet manifold I. It flows 'upwardly in the channels 3b between the spaced tubes and leaves the casing through the outlet manifold 2. The air to be cooled may be delivered through a suitable duct joined to the peripheral attachment flange I 5 and iiows downwardly through the channels Sa afforded by the interior surfaces of the several open ended tubes 3 for discharge at the bottomA of the exchanger with the exchange of heat taking place through the thin metal of the tube walls and the separators 4 and 5.

We claim:

1. In a heat exchanger, a group of spaced tubes, spacers between the tubes near opposite ends, bounding and securing the tube ends in uidtight relation for sealing the intervening space between the tubes, a casing surrounding the tube assembly and having inlet and outlet connections for uid ow through said space, means at one end of the tube group for rigidly joining and sealing thel casing with the adjacent tube spacers and a pair of superposed exible seal strips having opposite edges in rigid joining and sealing relation with the casing and the spacers at the other end of the tube group, the inner of the strips being flat and perforated and the outer strips being centrally bowed outwardly of the casing to expose a surface area on the outer face of the dat strip substantially equal to that exposed on its inner face.

2. In a heat exchanger, a casing having inlet and outlet connections for fluid fow, an assembly of fluid-flow conduits extending through the casing, conduit spacers near opposite ends or" the conduits closing the casing spaced between the conduits, and sealing connections between the casing and said spacers, the sealing connection at one end being fixed and the sealing connection at the other end including a pair of hexible walls superposed on one another, the inner of which is flat andperforate and the other of which is centrally bowed away from the perforate wall.

3. In a heat exchanger, a tube assembly, a casing sleeved thereon, means rigidly joining and spacing the tubes at one end with the casing, casing closure and tube spacing means at the other end, an imperforate flexible strip projected laterally from and secured to the last mentioned means in complete encircling relation thereto, said strip being outwardly bowedln a direction transverse to the lateral direction in which it projects, a strut bridging the space within the bowed strip to resist collapse thereof and being bendable transversely to the direction of lateral projection of said bowed strip and means to secure and seal the peripheral portion of said strip to the casing.

4. In a heat exchanger, a casing having an inlet and an outlet, two or more identical tube units enclosed by the casing and each comprising a bank of spaced tubes and means at opposite ends spacing the tubes and closing the intervening space, means securing adjacent spacers of side by side units to one another and to said casing, the connection to the casing being rigid at one end of the units and embodying a double walled flexible expansion seal at the other end, the inner of which is flat and perforated fand the other of which is imperforate and centrally bowed outwardly from the inner Wall.

5. In a heat exchanger of the character described, a core and a casing therefor, means joining the core and casing at spaced apart places axially of the core and sealing the casing space therebetween, the sealing joint at one of said places anchoring the casing and core against relative displacement and the sealing joint at the other place being constructed and arranged to accommodate relative expansion and including a flat flexible metal ring projecting laterally from the core periphery, an imperforate concave-con- Vex flexible metal ring superposed on the flat ring to enclose a space over the outer face of the flat ring and which space is in open communicationwith the casing interior so that said outer face is exposed to casing internal pressure and exing action of the flat ring transversely of its plane is free of uid pressure differential on opposite faces thereof, means sealing and fastening the adjacent inner edges of said rings to the core and means sealing and fastening the adjacent outer edges of said rings to the casing.

6. In a heat exchanger, a core, a casing enclosing the core, sealing means between the core and casing at one end, a at flexible ring projecting laterally the other end, said ring being'secured along opposite edges to the casing and the core and having perforations of casing internal pressure on opposite faces of the fiat ring and a transversely bowed ring overlying the outer face of the flat ring and being between the casingr and core at sealed at opposite edges to said .a-t ring beyond the said perforations.

7. In a heat exchanger, a casing, a core housed within the casing, a transversely bowed flexible sealing ring secured along one edge to the casing and along its other edge to the core, a spring strut projected across the hollow interior of the transversely bowed ring and fixed to the opposite edges thereof to tie said edges against spreading, said strut being rigid in the transverse direc- `tion of the bow in said ring to provide lateral stability between the core and casing and being yieldable in a direction transverse to said direction of rigidity for cooperating with the bowed ring in accommodating relative core and casing expansion.

8. In a casing and core structure, means to stabilize the core laterally in the casing and to seal the casing interior while yielding to expansion forces, comprising a pair of cooperating superposed rings secured in a leakproof manner to the core along one edge and to the casing along the "other edge, the innermost of said rings b'eing flat and perforated and the outermost ring being imperforate and bowed outwardly to provide a hollow space between the rings and being so constructedr and arranged that the surface area of the'innermost ring exposed thereinfor insuring equalization to said hollow space'is substantially equal to that exposed to the interior of the casing.

J OI-IN RALPH HOLMES. HOWARD F. MAY. JOHN R. HAYDEN.

maFnRENCla:sy CITED The following references are of record in the leof this patent:

UNITED STATES PATENTS Germany Jan. 29, 1904

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