US2610835A

US2610835A - Plate heat exchanger

Info

Publication number: US2610835A
Application number: US771299A
Authority: US
Inventors: Hytte Robert P Larsson
Original assignee: Separator AB
Current assignee: Alfa Laval Holdings Amsterdam AB
Priority date: 1942-02-10
Filing date: 1947-08-29
Publication date: 1952-09-16
Anticipated expiration: 1969-09-16
Also published as: FR892866A; NL60352C; DE843094C

Description

Sept 16, 1952 R. P. L. HYTTE 2,610,835

PLATE HEAT EXCHANGER Filed Aug. 29, 1947 3 Sheets-Sheet 1 M'vudm'f Sept. 16, 1952 R. P. L. HYTTE PLATE HEAT EXCHANGER Filed Aug. 29, 1947 3 Sheets-Sheet 2 Sept. 16, 1952 R. P. L. HYTTE PLATE HEAT EXCHANGER I5 Sheets-Sheet 3 Filed Aug. 29, 1947 F/G. IZ.

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and 3 positioned in invention the distributing device comprises a rib I5, running right across the channel.

The construction and effect of the distributing rib I5 is illustrated in Fig. 3, which shows the plate I2 in which the rib is pressed, and an adjacent plate I6 forming the opposite wall of the channel I4. Together with the plate I6 the said rib I5 forms a throttled slit I1. The rib I5 is advantageously of different height at the two ends, so that at the one end IB in front ofA the inlet opening 2 the width of the slit I1 is less than at the opposite end I9. It will be understood that the width of the slit at diiferent parts of the rib may be so determined that the greater resistance to the iiow in front of the opening 2 compensates that otherwise greater resistance to which the liquid flowing past I9 is exposed, or in other words a uniform iiowacross the width of the plate may be established. In the neighborhood of the opening 3 is a rib 20 which coopcrates with the plate I6 for the formation of a slit. This slit, too, should advantageously be narrower at I8 than at I9. The rib 20 may sometimes be omitted.

That part of the interspace or the channel I4 which is positioned between the ribs I5 and shouldbe provided, at suitable places, with pressed-up distance lugs or ribs 2|, which contact with the plate I6. Contact lugs in the slit I1 should be avoided, because such lugs together with the highvrate of flow would cause liquidfree spaces behind the lugs.

Fig. 4 shows another embodiment of the distributing device, according to which both plates I2 and IS are provided with rib-shaped portions |50 and the slit, or throttled passage between them, I 10, is formed by their lateral walls.

Fig. 5 illustrates a modification of theembodiment according to Fig. 4. The rib I5I, functioning like the rib I5 of Fig. 3, is in this case of V shape and provided with slopingvlateral walls, and a corresponding pressed portion 22 is provided in the plate I6. Between the sloping walls the slit I1I is formed. When the plate I6 is turned 180? relative to the plate I2 in the manner indicated, the slit I1I is still obtained in its unchanged form. As the width of the slit I1I should increase from the one end of the rib to t the other, the ribs I 5I and 22 should form a small angle.

Fig. 6 shows the embodiment of Fig. 5 but provided with supporting lugs 25 and 2G. However, as the lug 25 is located in the slit or throttle passage I12 it may be omitted and only the lug 25 provided.

Sometimes it is desirable that the heat transmitting surface should be plaited or corrugated steplike, that is so thatthe channel formed between two adjacent plates becomes zigzagshaped. The plaits or corrugations will then extend right across the plate and will have the character of ribs pressed in the sheet. They will be parallel with the distributing ribs I5 and 20. All the ribs mayhave the same contour. lOne such embodiment of the distributing ribs is shown in Fig. 7, where 28 and 29 are the plates having the describedfzig-zag shape. In Fig. 8 Ihave shown a sectional view `of one of the pairs of plates forming between them a slit I13 corresponding to the slit I1 of Fig. 3, the width of which is reduced towards one end.

I have illustrated in Fig. 9 a modification of the plate shown in Fig. 2. The plate, instead of having a` rectangular shape, has the shape of a parallelogram with sloping sides. Whereas according to Fig. 2 one plate is a reiiected image of the other plate, the symmetry between the upper plate and the plate below it of Fig. 9 is of another character. It is, however, possible, in the construction of Fig. 9 as well as in the construction of Fig. 2, to obtain the desired paths of flow by turning every second plate of the set 180 around an axis at right angles to the plane of the plate. As may be seen more clearly from Fig. 9 than from Fig. 2, the

openings

60 and 10 are each enclosed by a packing which separates the portion around the opening from the space M0 on one side of the plate |20, whereas the openings 2D and 30 communicate with the said space. The openings and 10 should not com-ry municate with said space but with the corresponding space on the opposite side of the plate 20.

vReferring to Fig. l, which is a perspective view of part ofa heat exchanger showing an assembly of three plates, the plates are cut away parallel to one edge of the exchanger and at such distance therefrom as to intersect two series openings (say 2 and 3) In plate heat exchangers it is generally necessary to take measures in order to insure that the plates are kept in the right position relative to each other.l The distance between the plates should be accurately iixed, since the iiuid layer should be of a predetermined thickness. The plates, therefore, generally are held in xed relative positions by distance pieces, usually in the form of lugs or ribs on the surfaces of the plates. If the plates are made of thin pressed sheet steel, the distance pieces are generally pressed in the material in the form of lugs. In the cleaning of the plates it has, however, been found diilcult to reach the cavities formed on the rear side of the lugs, because a brush does not penetrate thereinto. With aview to facilitating the cleaning ofthe cavities, the lugs have been made oblong, but this measure, too,l has proved unsatisfactory.

The invention relates to the distance pieces oi' particularly such plates, the heat transmitting surface of which is stepwise undulated or corrugated. With plates of this type the distance lugs vwere heretofore placedl on plane surfaces between the undulations or-on the sloping surfaces of the undulations. In both cases the cavity formed on the rear side of the lug has proved to bev accessible only with diiiiculty for brushing and other mechanical cleaning. According to the invention the distance pieces are formed by pressing areas of the bottom of the undulation, not to the full depth of the undulation, but only to a depth which corresponds to the position of the bottom of the undulation of'the adjacent plate. The said areas will thus form a support for the adjacent plate. In the latter plate are again corresponding areas which, however, are displaced so much in the direction of the undulations that vthey'lcontact with the'bottoms of the undulations of the next plate. The distance pieces of the'following `plate may be positioned right over those of the rst plate. The distance Apieces are thusalternately displaced, that ls in .5 one nterspace they are positioned at a given place and `in the next at another place.

Thel undulated plates |0.-| and |02 are of substantially similar shape and form a zigzagshaped channel lfor one of the -uids between which heat is to be exchanged. -That portion Iof the plate |02 which lies in the plane of thesectional view provided, in thev bottom of the u-ndulatiens.v with higher areas; .|03 which contact with the u-ndulations of the plate |-0z| and thus support it. The higher areas |03 ron the bottom |04 of the plate |02 may be looked upon as pressed-up lugs in the. bottom. which however entails that in front of the supporting lug the undulation has a smaller depth. than at other places., or in other wordsthe. undulation is flattened ofi at the place ofthe supporting lug.

In Fig. 11, I have shown a sectional view along the undulations in frontof the supporting lug. The bottom |04 of the undulation in the plate |02 slowly rises towards the bottom of the undulation in plate |0| and forms-an area or lug |03 which contacts with the bottom of the undulation in plate |l. The plateA |02 isI provided with a greater or lesser number ciA such supporting pieces. The plate |0| is in turn provided with a number of similar pressed-up portions- |05, whichA are not positionedfin thefplane of. the'section according to Fig. 10 but: some distance therebehind. The supports |05 `maycontactwith the bottoms of the undulationsY of a. plate not'represented on the drawingy whichis provided with pressed-up areas in front of the areas |03. The higher area |03 forms a depression |06 in the bottom |04. By locating the depressions of the adjacent undulations in line with each other, the

.surfaces of the depressions become accessible with a brush which is moved along the depressions across the undulations. The direction 0f movement of the brush is then in the plane of the section according to Fig. and at right angles to the plane of the section of Fig. 11. It will be clearly understood from Fig. 10 that the brush may freely be moved through the depressions |06, so that the surfaces at |03 are efliciently cleaned.

The depressions cause a reduction of the resistance to the flow owing to the increase of the sectional area of the channels resulting from the depressions in the zigzag channel below. Due to this circumstance a number of paths are formed at the depressions having a smaller resistance of flow than at other places of the undulations. These paths with reduced resistance cause socalled accelerated flow, which implies that those parts of the liquid which happen to move along this path reach the outlet of the zigzag channel quicker than the other parts of the liquid. This in turn results in some parts of the liquid not getting the same high temperature as the bulk of the fluid. Such accelerated flow is therefore a very serious inconvenience. It is true that a too quick ilow may be avoided by reducing the average speed of the fluid, but this entails considerable disadvantages in two respects. Partly, the capacity of the heat exchanger is reduced, and partly, in some cases, the main portion of the fluid is heated or cooled more than is intended and advantageous.

I have shown in Fig. 12 how the accelerated flow caused by the impressions may be avoided. Below the plate |02 is a plate |01 forming the lower wall of the zigzag channel. The sectional area of the channel in front of the depression |00 is larger than at other parts of the channel.

In'order to compensate for this increase of the area. the top |08 of the 'undulation in the plate .l0-1 is so widened that `a throttling of the zigzag channel resultsV at H0. The widened portion form-s a plane surface. `ofy the shape .shown Fig. 13. :Since the. depressionsy |06 ,l-iein line with each other, the depressionsA will also form lines.

In Figs. l0 and. 1-2 .all the undwulations areprovided with supporting .members or widened portions rI but it will be understood that-only some of the undulationa for instance every second .or thirdL may beprovided therewith..k

The subject lof this applieati'onisdisclosed in my yapplication Serial No. .475;240, filed February 9, 1943, now abandoned.

,I claim:

1. In a heat exchanger comprising a plurality of plates oi like, contour, eachhaving a face forming with the faces of the adjacent plates, apair of separate flow channels. eachv plate being identical to the othersv and having four fluid ow openings therethrough near 4its four corners. packing so arranged on plates carrying thesame that when the plates are assembled communication is afforded, through each chamber formed by 'two :adjacent plates. and between pairs of openings" along the same edge of. the exchanger. saidplates being so assembled. that the. two pairs of communicating openingsiin adiacentchambers are. along; opposite edges: of. the4 exchanger, and a distributing device extendingvvlaterally within each chamber providing a passage progressively widening from the edge of the chamber to which said openings are adjacent toward the opposite edge to thereby eifect a substantially equal distribution of the fluid in the part of the chamber beyond the distributing device.

2. In a heat exchanger comprising a plurality of plates of like contour. each having a face forming with the faces of the adjacent plates, a pair of separate flow channels, each plate being identical to the others and having four fluid flow openings therethrough near its four corners, packing so arranged on plates carrying the same that when the plates are assembled communication is afforded, through each chamber formed by two adjacent plates. and between pairs of openings along the same edge of the exchanger, said plates being so assembled that the two pairs of communicating openings in adjacent chambers are along opposite edges of the exchanger, and ridges extending laterally within each chamber near opposite ends thereof adapted to throttle the flow of fluid from the fluid inlet opening to the main body of the chamber and from the main body of the chamber to the iluid outlet opening, each ridge dening a passage gradually widening toward the edge of the plate remote from said last openings.

3. A heat exchanger comprising a series of superposed plates of like contour, namely substantially that of a parallelogram; the plates having like openings having like locations therein, namely, near each of the four corners of each plate; each plate being a duplicate of the others, a gasket applied to one face of each plate, said gasket defining a fluid chamber covering the major area of the plate and enclosing the two openings near the same longitudinal edge of the plate at opposite ends thereof but not enclosing the other two openings; other gaskets, applied to the same face of each plate, surrounding the other two openings; the gaskets of one plate having thev same location and arrangement as the gaskets of the other plates; said plates being so assembled that the chamber-defining gasket applied to one plate encloses a pair of openings near one longitudinal edge of the exchanger While the chamber defining gasket applied to an adjacent plate encloses a pair of openings near the opposite longitudinal edge of the exchanger, and identical fluid distributing devices on the several plates. the device on each plate forming with the adjacent plate a fluid now passage substantially progressively widening from the edge of the chamber to which the communicating openings are adjacent toward the opposite edge thereof, to thereby effect a substantially equal distribution of the iluid across the chamber in the course of its ow therethrough.

4. A heat exchanger comprising a plurality of heat exchanging plates in the shape of a parallelogram and each having four flowv openings, one on each corner of the plate, for conducting the heat exchanging iiuids, the plates consisting exclusively of identical plates each pressed in its entirety from thin sheet metal, gaskets on one face of each plate, said gaskets being identically arranged on the plates and with one gasket of each plate enclosing a pair of openings at one edge of the plate and the major part of the plate surface, said last openings being the inlet and the outlet openings for one fluid, the pair of openings at the opposite edge being the inlet and the outlet opening for the other fluid and being located outside the space enclosed by said gasket, a separate gasket enclosing each of the latter 8 openings, every secondfo'f said plates being revolved, relative to the others, 180 about an axis perpendicular to the face of the plate and passing through the center of said face.

5. A heat exchanger according to claim 4, in which each plate has a plurality of spaces consisting of deformations of the plate, the deformations being unsymmetrically positioned relative to the center line of the plate, each deformation of one plate being opposite non-deformed portions of the adjacent plates.

ROBERT P. LARSSON HY TI'E.

REFERENCES CITED The following references are of record in the i'lle of this patent:

UNITED STATES PATENTS Number Name Date 448,521 Horner Mar. 17, 1891 1,992,097 Seligman Feb. 19, 1935 2,281,754 Dalzell May 5, 1942 2,428,880 Kintner Oct. 14, 1947 FOREIGN PATENTS Number Country Date 396,696 Great Britain July 3l, 1933 494,009 Great Britain Oct. 19, 1938 838,905 France Dec. 16, 1938 63,757 Germany Aug. 10, 1892 216,789 Germany Dec. 2, 1909 692,730 Germany May 30, 1940