US2379671A - Heat exchanger - Google Patents

Description

y 3, 1945- I A. v. WETHERBY-WILLIAMS ,379,671

HEAT EXGHA NGE'R Filed Dec. 31, .1942 6 Sheets-Sheet l FlGl-A.

QfifiLNATER COOL WATER F162; EF

[W UIMWHWWWUI H LR INVEQOR.

UL! I \3/ g ARTHUR VIVIAN WET/IERBY-W/LL/AMS v a i J w Wl a ATTDRNEY COOL L/oum July 3, 1945- A v. WETHERBY-WILLIAMS 2,379,671

HEgAT EXCHANGER Filed Dec. 31, 1942. 6 Sheets-Sheet 3 FIG, 8. 5

FRAME PLA TE FlG.l3.,

FIG.I5.I FM Fl G16. m

ARTHUR ww/w gvfruimv-mzuus r ATT ORNE Y July 1945 A. v. WETHERBYTWILLIAMS 2,379,671 7 HEAT EXCHANGER Filed Dec. 31, 1942 e Sheets-Sheet 4 INVENTOR.

ARTHUR V/l/IAN WETIIERBY-IWLLIIWS ATTORNEY July 3, 1945., A; v. WETHERBY-WILLIAMS I 2,379,671

HEAT EXCHANGER Filed Dec. 51, .1942 a Sheets-Sheet s AR THUR V/ V/A N WE THERBV- mu MMS J y 3, 1945- Y A. V: WETHERBY-WILLIAIMS 2,379,671

HEAT EXCHANGER Filed Dec. 31, 1942 6 Sheets-Sheet 6 V fig r N m A O O :1 [l r J 1 R '/N O O I L o o :1 RE 1 O O LL (D INVEN TOR. ART/12m V/V/Al/ wzmmaymum/4s wag.

kl ATTORNEY posite one.

divide the space between adjacent pairs of dividing sheets into a seriesrof parallel channels connected at alternate ends to permit zig-zag Patented July 3, 1945 HEAT EXCHANGER e Arthur Vivian Wetherby-Williams, New York, N. Y., assignor to Walker-Wallace, Incorporated, Bufialo, Y., a corporation of New York Application December 31, 1942, SerialNo. 470,800

rolaim. (01. 257-245) My inventionrelates to heat exchangers of the type in which the heating fluid and the fluid to be heated are caused to flow in part countercurrent over opposite sides of a series of plates. 1

The principal object of the present invention: is to improve, simplify and cheapen the construc 1 tion of such typeof heat exchangers.

NOne feature of the invention is to construct:

the apparatus in such a way andwith such materials that maximum heat transfer is obtained with minimum heat loss. present invention, the heat transfer is made through separable sheets or platesof good conducting material such as stainless steel. As the sheets do not have to'be cast as part of a unit,

they can be made very thin and hence caused to act as very efficient conductors of heat from According to the y the fluid on one side of the sheets to the fluid on the other side. i On either side of each sheet separating it from the adjacent sheets are spacer frames, usually rectangular in shape.

Means are provided for admitting fluid to the interior of each frame at one corner andexhausting it from anothercorner, usually, the up- A removable grid is provided to flow of fluid from one channel to the next across the grid from one corner'to the other corner.

The function of the frames and grids isto produce tortuous turbulent flow of the two ;fluids over opposite sides of each plate. No heat has to pass through the frames or grids in the transference of heat from one fluid tolthe other. On

remain there. Consequently they are heated from the warmed zoutside layers in contact with the heated surfaces only by conduction through the fluid. When the velocity of flow exceeds such critical figure the flow is turbulent, so that 1 theparticles in the middleofthe stream at one time are very shortly thereafter brought? to the outsidezof. thestream where they canccontact and be heated by the hot surfaces over which theyare moving. 1

One suitable form of construction embodying the features of myyinvention is shown,.by.way of 'example, in the accompanying drawings,

wherein: A i 1 Figure 1 is a: side elevationof the left- -hand end andmiddle of the preferred form of the apparatusasa whole? i 1 Figure lA isi a sideelevation of the-right hand end of a modified form of construction"; w 1 Figure 2 is a diagrammatic vertical. section through the apparatus designed to illustrate the plates and four frames in the order in which the'other; hand, transference of heat from. the

peripheryof the frames to the outside air means thatthere remains much less heat capable of being transferred to the fluid to be heated. According to the'present invention, therefore, the outer parts at least of the frameare formed of p001 heat conducting material such as a plastic of the synthetic resin type. i

To. obtain rapid transfer of heat to a surface over which a hot fluid is flowing, and transfer a Figure 3 is a plan view of -one of the dividing platesy I 1 Figure 41is an edge view of the same; a

Figure 5 is a plan viewofone of the spacer frames; W

i i i it Figure 6 is anedge view of the same;

Figure 7 is a section on the line 1-1-1 of Figure-5;

Figures 8 to 16 inclusive are plan views of five they have to be stacked to produce the desired counter-current flow of hot and cool fluids; L 1

Figure 17 isa-section onthe line "-11 of Figurel; it i Figure 17A is a section onthe line PIA- HA ofFigurelA; x Figure 18 is a section on the line Illa-l8 of Figure 17;: i i i i x FigurelSA is a section on the line I BA-IBA of Figure 17A;

Figure 19 is a plan view of one of the grids removed from its frame; i

of heat from suchsurface in the case of acold fluid; it is necessary to have turbulent flow, so

that all parts of the fluid stream are brought into contact with the surface in a relatively short interval of time. If the velocity of flo'w for any given fluid is below a certain critical figure, the flow is laminar, that is to say the particles forming the stream move in parallel lines. As a result the particles in the :middleof the stream Figure 20 is a section on the line 210-40101? Figure19; M m l Figure 21 is a section on the line 2I-2I of Figure 20; i i i Figure '22 is a view similar to Figure 21 showing.

the form of 'the ,grid after compression asthe result of the assembly of all the parts of the ap-. paratus; i

: Figure 23 is a bottom plan view of the underside of the top member of the apparatus; and i Figure 24 is a section on the line 24-24 of Figure23. i i

. with a flanged pipe coupling 32'.

has two lugs 26 at each end and the intervening web 33 is provided with an aperture 34 for the above-mentioned aligning pin 35.

One diametricallyopposite pairof lugs 26 of each frame have holes 21 through them. The

other pair of lugs are slotted at 28, the slots extending into the interior of the frame. The holes 21 are to permit fluid, eitherhot or cold as the edge, with spacer strips 31 extending perpendicularly through the first set of strips to hold the latter in spaced parallel relation.

The grid has the same length as the interior I of the frame, the alternate ends of the strips being apertured or cut off to permit zig-zag flow of fluid from one channel to the next across the grid. The two outer strips 36 each have an extension 39at one end adapted to: enter one or other of the slots '28 in the frame in which the grid is to be used. These ends arefloffset so. as

to yieldingly press against the walls of the slots in which they are located to hold the grid in place while the apparatus is being assembled and disassembled.

Desirably the strips 36 are arcuate in-section Y and have a width slightly greater than the thick-' case may be, to by-pass that particular frame and pass from the frame above to the frame beneath it; and vice versa. The slots 28 are to permit fiuid to enter the interiorof the frame, pass across it and then flow out at the opposite corner.

fO f the four lugs 29 On each of the dividing plates, two are drilled with holes 30 to register with either a hole 21v or the end of a slot 28 in the 7 adjacent frames. The other two lugs are left frames.

In Figures 8 to 16 inclusive is shown a-series of fiveplates and four frames in-the order in solid to prevent undesired by-passing of. the

' which they have to be'stacked to produce the desired counter-current flow of hot and cold fluids. The element in Fig. 8 rests on that shown in Fig. 9,"and so on down to the plate shown in Fig. 16. The legends and arrows indicate the down path of the hot fluid to be cooled and the u'p pat h of the cooling fluid.

It will be noted that the plates of Figures 8 and 12 are identical, except-that one has been turned over, top to bottom. Also the plates of Figures 10 and 14 are identical, except that one has been turned over, end to end. Likewise the frames of Figures 9 and 13 are identical with those of Figures 11 and 15, except that the second pair have been turned over, top to bottom.

d It will be obviousfrom examination of Figures 8 to 16 that the position 'of the. inlet and outlet connections to the top 22 and base will depend on how many'plates and frames it is desiredto place in the stack. Hence, to enable one construction of the top section and one construction of base section to be used for all installations, such sectionshave four apertures each provided These apertures are located so as to register with either the holes 27 or the outer ends of the slots 28- in the adjacent spacer frames. The pair'of'cou-plings not used can be closed with screw caps in well known manner.

Figure 2 shows diagrammatically, the vertical and horizontal flow of the fluids through the apparatus as a whole. i i i 7 Flow diagonally across the interior of the frames; as suggested by the arrows in the diagrammatic Figures 9, 11, 13 and 15 would not be satisfactory. The velocity would be toolow to ness of the spacerframe 25 in which the grid is .to be used, plus the thickness of the gasket between each face of the frame and the adjacentdividing plates. So proportioned and constructed the ends of the strips are bent inwards by con tact with the dividing plates 24 when the apparatus is assembled, as in'dicatedin Figure 22. There is then metal-to-metal contact between the grid and the plates throughout the entire apparatus.

The spacer strips 31 which hold the channel forming strips 36 inspaced relation are also to advantage, arcuate in cross'-section.- This-0on structi'on is advantageous, not only for the reason that it gives a much stiffer structure, but also because'the curved form'aids in producing the desired turbulent how offluid.

The use of grids made separate from the frames whichre'ceive them not only simplifies.construc-. tion and cleaning but also enables the frame'and grid to be made of different materials. The same is true with regard to the dividing plates'and the frame.

The object of any heat ex'ohangeris to conserve heat; This involvestransferring as'much of the i heat in one fluid to another as is practicable. In

the present apparatusthis heat transfer takes place" through the dividing plates. Hence such fluids passing through the heat exchanger.

The function of the frames and grids is to producetortuous turbulent flow of the two fluids over j opposite sides of each plate. No heat hasto pass through the frames or grids in the transference also be unacted upon by the fluids passingv through give turbulent flow and the fluid in the corners I .away from the slots would remain more or less the heat exchanger. Plastics of the synthetic resin type fulfill these requirements for most purposes: 7

On the other hand, as the grids are wholly sur rounded by the fluids from and to which heat is beingwtransferred, their heat conductivity is of small consequence; -Metal strips are convenient material forthis purpose. As however, the grids do" not have to withstand any pressure except i i that between spaced points in the flow path of a o the same fluid, instead of making them of metal,

To prevent this the frames are provided with peripheral projection 42, 43 which extend both upthey may be constructed of thin woodstrips or the like.

Fluid-tight joints between the dividing plates and spacer frames are obtained by means of gaskets 40 cut to register with the parts of, the frame which would otherwise contact with the adjacent dividing plate.

The stack of plates, frames and interposed gaskets are clamped together under pressure by To simplify and cheapen the construc- 1 bolts 41. tion these bolts, where the size of; the exchanger and theother factors permit, pass outside of the 1:;

peripheries of both the plates and the frames, as shown in Figure 1. With that construction the wardly and downwardly so as tooverlie the mar gins of the adjacent dividing plate and the gaskets under and over the same. These projections therefore, act as abutments to restrain outward f movement of the gaskets. It will be noted that I the projections are staggered with respect to top and bottom sections are made larger than the plates and frames to provide a projecting margin for the rejection of such bolts. So arranged, the bolts are notheated up to same degree as the frames with the result that if the bolts are tightened when the apparatus is cold, they will unduly strain or break the frames and other parts when the apparatus is expanded by the hot fluids. If the nuts 48 on the bolts are adjusted latter.

so thatthe requisite clamping pressure will be obtained when the apparatus is hot, the joints are apt to leak when it is cold. To minimize this difficulty, very heavy springs 49 may be put under the nuts. This is particularly useful where the terial has a much higher coefiicient of heat expansion than metals, such as steel.

the projections 42, so that when every other frame is turned over, top to bottom, asindicated in Figures9, ll, 13 and 15, there willbenointerference between the projections on adjacentframes.

Toreduce the likelihood of fluid under pressure, either that to be cooled or that used for cooling, entering the frames through which the other fluid is circulating, grooves 44 are provided, as shown in Figures ,5 and 7. Any fluid forced under pressure between one ofthe gaskets and, its adjacent frame will escape through the groove a in such frame and not enter the interior of the "What I claim is: a

A heat exchanger comprising a series of alternately arranged dividing sheets and spacer frames having substantially rectangular open-centers, a

\ removable grid in each frame'of substantiall the same thickness as the frame in which it is 10- frames are made of plastic, as that type of ma- Unequal expansion of the bolts and the stack of plates, frames and gaskets may be reduced somewhat by enlarging. the frame so that the bolts pass, as shown in Figure 1A, through the, margins 3 of the frames as well as through the margins of r the top and bottom sections. With such construction the bolts take thetemperature of the outer parts of-the frame air. o

The spacer frames are rectangular in shape with longitudinally extending lugs 26, at both ends. Two of these lugs have holes 2'! through them not connected with the interior of the frame.

The other two lugs are slotted at 28. The outer ends of these two; slots have the same relative position as the holes 21 in the frames above and below it. Each dividing plate has longitudinal extensions 29 with holes 30 therein.

The long strips of gasket material which run rather than that of the outside dividing sheets into a series of parallel channels,

the alternate ends of the strips being cutaway to 1 permit zigzag flow, of fluid fromone channelto: r the next across the grid, a sheet of substantially incompressible packing arranged on each side of each dividing sheet, each grid prior to assembly being of slightly greater thickness than the dis tance betweenthe dividing sheets on either side,

thereof when the exchanger; isassembled and a the stripsare arranged so that their edges con along the two sides of the frames may, unless re strained, be blown out when theapparatus is;used for cooling liquids under considerable pressure.

tact with the dividing sheets on either side of the gridand at least oneedge contacts obliquely with its adjacent dividing sheets to permit the strips to bend underthe pressureproducedby forcing 3 together the alternate series of dividing sheets f and spacer frames and thereby reduce the thick- 'ne ss of the grid. to the requisite extent, and means for introducing and discharging fluid into and out of the interior of saidframes atopposite corners i of each of said frames n a a ARTHUR WETHERBY-W ILLIAMS.

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