US1992097A

US1992097A - Surface heat exchange apparatus for fluids

Info

Publication number: US1992097A
Application number: US689149A
Authority: US
Inventors: Seligman Richard
Original assignee: Individual
Current assignee: Individual
Priority date: 1933-04-04
Filing date: 1933-09-12
Publication date: 1935-02-19
Anticipated expiration: 1952-02-19

Description

Feb. 19, 1935. R. sELlGMAN SURFACEl HEAT EXCHANGE APPARATUS FOR FLUIDS Filed Sept. l2, 1933 4 Sheets-Sheet l MVE/VTR l ATToR/vD/S l'feb. 1'9, :1935. R. sELlGMAN SURFACE HEAT EXCHANGE APPARATUS FOR FLUIDS Filed sept. 12, i955 4 sheets-sheet 2 I lllllrl/l/l lll/1111 ,arras/VEZ,

Feb. 19, 1935. R. sELlGMAN SURFACE'HEAT EXCHANGE APPARATUS FOR FLUIDS Filed Sept. 12, 1933" 4 Sheets-Sheet 3 lll/111171) /NvENT0R WSW B y mmm ATTORNE x5 Feb. 19, 1935. R SELIGMAN 1,992,097

SURFACE HEAT EXCHANGE APPARATUS FOR FLUIDS Filed Sept. l2, 1953 4 Sheets-Sheet 4 Wigs/[NMR mmm Patented Feb. 19,. 1935 UNITED STATES SURFACE HEAT EXCHANGE APPARATUS FOR FLUIDS Richard Seligman, Wimbledon, London, England Application september 12, 1933. serial No. 689,149 In Great Britain April 4, 1933 6 Claims.

'I'he present invention concerns improvements in or relating to surface heat exchange apparatus for iiuids, of the type in which the uids between which heat exchange is to be eiected ilow on opposite sides of a conductive heat exchanging surface of .extended area.

In the design of heat exchange apparatus hitherto known it has been the` practice to try to obtain the maximum possible speed of the fluids over the heat exchanging surface with the object of promoting a high rate of heat exchange. Such apparatus has the disadvantage that a considerable consumption of power is required to maintain the speed of the iiuids. As a further means of enhancing the rate of heat exchange baiiles or other obstacles have been arranged in the path of the fluids, or the fluids have been caused to reverse their direction of flow at frequent intervals, all of which devices cause an increase in the amount of power consumed in operating the heat exchanger.

'Ihe object of the present invention is, therefore, to provide a heat exchange apparatus in which the above disadvantages are largely obviated, and in which the power consumption in relation to known systems is comparatively small. Such an apparatus is obviously of considerable technical and industrial importance, and the invention may be said to provide heat exchange apparatus for fluids in which it is possible to obtain a high rate of heat exchange between the re spective hot and cold uids with a very small drop in the pressure of the uids in passing over the heat exchanging surfaces. In other words, the present invention permits a very high rate of heat exchange to be achieved at comparatively low linear rates of fluid flow, and in consequence the drop of pressure in the fluid between the inlet 'and outlet to the apparatus is small which as stated above is a very advantageous result.

According to the present invention heat exchange apparatus for uids, of the type in which the fluids between which heat exchange is to be effected flow on opposite sides of a heat exchanging surface, is characterized by the features that the said heat exchanging surface is so shaped that there are formed with one or both adjacent heat exchanging surfaces or with one or both end walls of the apparatus, a plurality of restricted passages interconnecting a series of chambers, which passages are of such shape as to impart a dened directional flow to the fluid jet issuing therefrom, for example, against one or more heat exchanging walls of the succeeding chamber.

Another feature rof the present invention comprises heat exchange apparatus for fluids, of the type in which the fluids between which heat exchange is to be eifected ow on opposite sides of a heat exchanging surface, characterized by 5 the feature that the said heat exchanging surface is so shaped that there are formed with one or both adjacent heat exchanging surfaces or with one or both end walls of the apparatus a plurality of restricted passages interconnecting a l0 series of chambers, the said passages having such shape and .dimensions in relation to the chambers that their profileY is substantially that of a Venturi-tube, whereby 'loss of fluid pressure in passing from chamber to chamber is reduced to a Further limportant features of the present invention will be apparent from the following description and the appended claims.

The present invention, together with the preferred modes of carrying it into effect, will now be described with reference to the accompanying drawings. These are directed to describing a form of apparatus which may be readily taken apart for cleaning, which is essential when dealing with some liquids, e. g., milk or beer. It will be clear, however, to those skilled in the art that the principles involved can be readily applied to constructions in which such provision is not necessary as, for instance, for steam condensers and the like.

1n the drawings:-

Fig. 1 shows a sectional view on the line 1-1 of Fig. 2 of a frame memberfor a heat exchanger according to the present invention; the frame being in elevation and the packing in section.

Fig. 2 is a cross section of Fig. 1 on the line 2 2.

Fig. 3 is a plate for use in conjunction with the frame of Fig. 1 as hereinafter described. 40

Fig. 4 is a central vertical section of Fig. 3.

Fig. 5 shows one end of the plates and frames assembled in position in a heat exchanger and Fig. 5a shows the other end. 45

Fig. 6 shows an enlarged section of one of the chambersv and the inlet and outlet passages thereto.

Fig. 7 shows a cross section of the plate of Fig. 3 on the line '7A-7 of Fig. 3, the frame being 50 shown between two plates.

Fig. 8 shows a modified form of frame and plate.

Fig. 9 shows a further alternative arrangement of frames and plates. 66

` 1o. snowsps -modmcstioamfwnicni the frameand plate are combined.

. t @P10-m mt 11 shows an v plates. ,Y f

Figs. 12 and 13 show cross sections of alterna- .tive'forms of plates according'to the presentin.

- vention.

,Corresponding elements are indicated by the same reference number in the drawings.

'I'he frame 1,-shown in Fig. vl., consists of open rigid frame ofthe shapel shown, containing on both sides channels for the reception of resilient packing material, such as rubber rings 2.

4 Inlet and outlet ports3-and 4 respectively are provided in each frame -forone fluid, together with transfer ports 5 and'6 respectively for the second amd.` Adjacent the inlet and 'outlet ports supporting grids 7 are provided to prevent the pressure of the fluid from deforming the thinplates 8 and thus causing leakage of the fluids. Lugs '9 are provided whereby a number of frames and plates may be carried and/or clamped together by bolts, for example, in asingle unit.

'I'he plate 8 of Fig. 3 comprisesa thin metal plate for example, of copper, tinned copper, stainless steel etc., accordingto the nature .and properties of the fluid .or liquids to be treated. It

- has the same overall shape as the frame 1 and contains four ports 10, 1.15,- 12, 13.

Ports

10 and 11 register with the inlet and outlet ports 3 and 4. of the frame 1. and

ports

12 and 13 register withv y r the transfer ports 5 and 6. Ifdesired one or more of the ports 10,

l

11, 12, .13 may be leftuncut according to the, direction of flow which' it is intended the fluids s'houldtake. Indentations 14,

` or troughs as they will be hereinafter called, are

formed in the plate, conveniently by preing, castingy or machining, so that the plate has the cross section shown in Fig. 4. The shape of a trough is shown on an enlarged scale in Fig. 6.

'Ihe frames and plates are assembled alternately as shown in the longitudinal section of Fig. 5, a suiiicient number being provided to deal lwith the quantities of liquid to be treated. It will be seen that when so assembled there are formed a plurality of chambers 15, interconnected by constricted passages 16 forming throat between each two chambers. One fluid or liquid (e. g. hot water) passes through one set. of chambers and passages in series as indicated by the arrows H. W. (Fig. 5) and the other yfluid or liquid (e. g. milk) passes through the chambers and passages on theother side of the heat exchange surface formed` by the plate 8 preferably in contraow as indicatedby the arrows M, heat exchange taking place between the 'two uds or liquids which are kept entirely separate by the rubber sealing devices 2, any small leakage round the ports escaping through the channel 2a, formed between the ports and the sealing means round the body of the frame. l

In order that the invention may be applied to the elements adjacent the end pieces or walls of the apparatus, between which `.end walls the plates and -frames are normally positioned, one

-. :mausi4 Y l 8. In this case the end walls of thev apparatus cooperate directly with the single plate. and are Vformed with troughs or projections in their lsurfaces as'above described. If, however, in anycase it'is desired to submit only one of the fluids to the `passage. through the constrictions and chambers then, ini this case, the plate or end wall on the i opposite side of.A the heat exchanging plate may` be plane.

Referring to Figs. s and e it is seen um the profile-,or cross section of the passage or ,throa 16 resembles that of a Venturi-tube in that the passage gradually narrows to a minimum cross' ing therethrough is aminimum, and it is believed that `forming the passages in this shape is an important contributory cause of the small loss of pressure in fluids ilowing throughA the apparatus of the present invention.-

Itis not necessary, according to the present invention, that the profile ofthe passage 16 should be exactly that oi' a venturi; it is quite sumcient that the shape of the passageshould approximate thereto and I have found that very good results can be obtained if the profile of the passage apchamber 15: the wall 14a is in contact with the other fluid in the corresponding chamber and the result of the jetlof'uidissuing with considerable velocity from the aperture 16 andimpinging directlyon the surface 14a is to effect a high degree of heat exchange through the cham' ber wall 14a with the other fluid on the opposite side of the wall. I have performed experiments to show the flow-lines of the fluid through the passages 16 and through the chamber 15 and I have found that it is possible with'the arrangements of the present invention, if the proportions are suitably chosen to direct the jet of fluid against the wall 14a, and thence the main part of the fluid against the wall 17, whilst portions of the stream are reflected on to the wall 14, thus providing that in each chamber and for each fluid there is at least one point at which'a fluid jet impinges directly on a heat. exchanging wall, and that impingement at two or more points can be. obtained whilst areas of stagnation are reduced to a minimum thus providing a very high degree of heat exchanging eiiiciency coupled with a very low vpressure drop in the uids passing through the apparatus, two highly desirable features in heat exchanging apparatus.

proximates'to the Venturi shape, i. e., i! -it pro- A The size and shape of the passages 16 are controlled by the shape of the sides 17 of the trough,

and the angle at which the fluid jet strikes the wall or walls of the chamber- 15 is also controllable by the same factors. I have found that in order to provide a construction which shall 17 of the trough makes with the plane o! the plate 8 should not be more than 80 nor less than 60. 'I'he sides oi' the trough are preferably (but not necessarily) flat over the greater portion of their extent, as shown in Fig. 6` and merge into the bottom of the trough and into the plate in smooth curves which provide the approximate Venturishaped passage already described.

The shape of' the chamber 15 and of the passages 16 are further controlled by the ratio of dimensions 8 and (see Fig. 6.) I have found that desirable ratios for for liquids having a viscosity approximating to that of water are between 4 and 5.5 in order to obtain ease of cleaning and convenient manufacturing conditions consistent with high rates of heat exchange and low pressure drop. As regards the rate klo ratios between A and 1/i give satisfactory results, but my invention is not limited to these ratios. The size of the passage 16 will naturally depend on the character of the liquid to be treated-for example, when treating brewers wort containing hops, or milk which under the influence of heat deposits casein, the passage may have to be larger than where water is concerned to prevent choking, while viscous liquids, such as cream, may also need a comparatively wide passage. It will be, clear from the foregoing that by some sacrifice of rate of heat exchange the pressure required can be varied over a wide range.

Under certain circumstances it may be desirable to arrange that the major axes of the ports 3 and 4 are inclined to the direction of the troughs, instead of being parallel thereto as in Fig. 1. This may ensure more uniform distribution of the fiuid over the plates, particularly where the width of the port is only about half the length of the troughs, as in Figs. 1 and 8. The ports 5 and 6 and the apertures l0, 11, 12 and 13 in the plate of Fig. 2 will be similarly inclined. Alternatively a tapered obstruction may be interposed between the ports and the rst trough. This may take the form of a swage on the plate or a bar on the plate or on the frame.

Fig. 7 shows a cross section of the plate and frame assembly on a line transverse to the direction of flow of the fluid. 'Ihe shape of the ends of the trough 14 is here illustrated. It is desirable that the ends 18 of the trough, which are parallel to the direction of the flow of the fluids, should have substantially the same angle of inclination to the plane of the plate as the sides 17 of the trough which are transverse to the direction of flow of the fluid, in order to minimizeleakage of the iiuid past the troughs and through the space 19 between the end of the trough and the co-operating frame, while not making cleaning of the troughs unduly diiiicult. The inner edge of the frame may also be bevelled so as to assume the shape of the area 19 shown in Fig. 7 and thereby minimize leakage by filling up the space which would otherwise be open.

Fig. 8 shows a modied form oi' frame and plate, in which the fiuid takes a U shaped path over the plate. The troughs are arranged in two groups side by side as shown and the iiuid is guided over the two groups in succession by the projecting rib 20, which extends from the main frame 1 and separates the two groups oi' troughs,

but leaving a gap 21 for the uid topass from one group to the other. Rubber packing may be provided on the rib 20 as on the frame 1. Instead of using a projecting rib on the frame to guide the fluid the rib may be replaced by a swagev or a raised groove formed in the plate, and occupying the position o1' the rib. If desired the top of the groove may contain a channel in which packing can be inserted.

Fig. 9 shows a further type of frame and plate ac cording to the present invention. In this case the troughs are arranged in three groups, and ribs 20 extending from the frame cause the fiuid to make three passes over the plate between the inlet and outlet ports. If desired the ribs 20 may be replaced by grooves on the plates as described with reference to Fig. 8. The

ports

3a, 4a, 5a, 6a.' are preferably of the same length in the direction of their major axes as the length of the troughs, as shown, in order to ensure uniform distribution of the fluid over the plates, and to` reduce as far as may be the loss of pressure on entering and leaving the plate. It will be clear that any number of such reversals of flow may be adopted.

Fig. 10 shows an alternative arrangement in which the frames 23 are welded to or formed integral with the plates 8 as shown. This enables the number of rubber packings required to be reduced by one half, and may be advantageous in certain circumstances.

Fig. 11 illustrates the application of cast plates to the present invention, the use of frames being eliminated. 'I'he plates 24 are cast in the shape shown with projecting ribs 25 transverse to the direction of the flow of the fluid, so that when the plates are assembled chambers 15 interconnected by approximately Venturi-shaped passages 16 are formed as in the case of Fig. 5. If desired, however, the disposition of the ribs may vary on the two sides of the plate. For example. co-operating ribs on the two adjacent plates may be spaced so that the chambers on one side of a plate have different dimensions from those on the other side, or the direction of the ow of, the iiuids on the two sides of the plate need not be parallel in this embodiment; for example, the

two uids may iiow at right angles one to the other, the ribs being arranged accordingly. The plates contain inlet, outlet and transfer ports for the iiuids, as in the preceding embodiments.

Figs. l2 and 13 show alternative shapes for the troughs according to the present invention. In Fig. 12 the troughs have a saw-tooth cross section, the angle 26 being approximately 90 or a little greater. In Fig. 13 the plates areshaped to form Vena contracta passages with the adjacent plate when assembled. It will be seen that the fluid jet issuing from the passage 28, for example, is directed against the heat exchanging walls 29 of the succeeding chamber and the jet of the second iiuid issuing from the passage 30 is also directed against the other side of the plate 29, thus promoting good heat exchange between the two fluids, with a very low pressure loss.

A method of applying the invention to heat exchange apparatus which may be convenient in certain circumstances is to form a heat exchang- 'ing or welding on side plates toclose the ends 18 of the troughs 14. It several plates are assembled to form a heat exchanger, one plate attached across each side will serve to hold the whole series of plates in position. Alternatively, the edge of the heat exchanging Plate either formed as above or as in Fig. 3 may be bent up and soldered or welded to the succeeding lplate to form a uid tight joint. In addition, in any 'of the Aarrangements described above, additional small indentations. or projections may be provided on the plates,which indentations or projections may be arranged at intervals along the sides or bottoms of the troughs 14. These' contact with adjoining plates and serve to maintain the correct spacing of the plates. They prevent the plates bending under an excess of pressure on one side, which would change the dimensions of the throat 16. If applied to the construction described in the preceding paragraph, the use of separate frames for spacing the plates may be dispensed with.

While certain preferred embodiments of the is to be understood that I do not wish theinvention to be considered as limited thereto, and that` modifications may'be made therein whilst retaining the principle and spirit of the invention spaced relation to each other that a plurality of iluid conduits are formed through which the iluids are made to flow transversely to the corrugations and of which each conduit comprises a plurality of heat exchangechambers being connected with each other by means of restricted passages and in which the chambers formed by the corrugations have the form of wide, shallow grooves with inclined lateral walls, and the restricted passages which connect the chambers with each other are of nozzle-like cross-section with' their axes and the longitudinal direction of the heat exchange chambers forming an obtuse angle.

2. In a heat exchange apparatus for uids, a plurality of spaced plate-like ow controlling and heat exchange elements assembled side by side, means for closing the spaces between adjacent elements at the margin thereof to provide heat exchange passages for uids between'each two elements, each said element having a plurality of offset portions for providing in the assembly a, succession of heat exchange chambers with plane parallel walls, each'said element also having portions presenting surfaces angularly directed at angles between' 60 and 80 degrees relative to said walls and connecting said offset portions, said angular portions operating in the assembly to `restrict the cross-section of passage for fluid t'o a convergent-divergent form with the minimum spacing between said angular portions less than one-half the spacing in the chambers, saidA chambers having a ratio of length in the direction of flow to cross-sectional spacing between the walls which is between 4 to l and 5.5 to k1, and means for admitting uids to the spaces between the elements and withdrawing the same therefrom after passage through the successive chambers.

3. In heat exchange apparatus for fluids, at

`least three wall elements in juxtaposed relation for providing flow passages for two fluids which are in heat exchanging relation through the wall of the central o ne of said three elements, the central one of said elements having a plurality of substantially plane portions which are wide in which the said one iluidviiows, said chambers being successively connected by restricted passages of convergent-divergent formation having walls thereof formed by said angular portions and having their axes'disposed at oblique angles to the said plane portionsso that the fluid is directed across each succeeding heat exchange `chamberand against at least one heat exchanging wall thereof and whereby abrupt changes in the direction of fluid flow are avoided.

4. In heat exchange apparatus for fluids, at least three wall elements in juxtaposed relation for providing now passages for two fluids in heat exchanging relation through the central one of said three elements, the centralone of said elementshaving a plurality of substantially plane portions which are wide in the direction o f uid flow and are connected together by portions arranged at oblique anglesto said plane portions and form therewith a succession of wide shallow grooves extending transversely to the direction of flow of one said fluid, said central element presenting its said portions for cooperation with another said wall element to form from said grooves and the adjacent surface portions of said other Wall element a succession of heat exchange chambers through which the said one iluid flows,

said chambers being successively connected by restricted passages of convergent-divergent formation having the walls formed by 'said angular portions and having their axes disposed at oblique angles to the said plane portions so that the fluid is directed across each succeeding heat exchange chamber and against at least one heat exchanging wall thereof and whereby abrupt changes in the direction of fluid flow are avoided, the length of each said chamber being at least twice the separation of the parallel portion thereof from the adjacent surface portion oi' the other wall element.

-5. In heat exchange apparatus for uids, at least three. wall elements in juxtaposed relation for providing flow passages for two fluids in heat exchanging relation through the central one of said three elements, the central one of said elements having a plurality of substantially plane portions which are wide in the direction of fluid ilow and are connected together by portions arranged at angles to said plane `portions and form therewith a succession of wide shallow grooves extending transversely to the direction of now of one said iluid, said central element presenting its said portions for cooperation with another said wall element to formfrom said grooves and the adjacent surface of said other wall element a succession of heat exchange chambers through which the corresponding fluid ilows, said chambers being successively connected by restricted passages of convergent-divergent formation having the walls formed by said angular portions and having their axes disposed at oblique angles to the said plane portions so that the uid is directed across the succeeding heat exchange chamberand against at least one heat exchanging wall thereof and whereby abrupt changes in the direction of fluid flow are avoided, the length of each said chamber being between 4 and 5.5 times the separation of the parallel portion from the adjacent surface of the other wall element.

6. In heat exchange apparatus for-fluids, a series of elements each formed with a series of parallel trough-shaped depressions, the said elements being arranged side'by side in spaced relationship so that the space formed between each pair of juxtaposed elements comprises a plurality of heat exchange chambers which have a length in the direction of fluid now at least twice that of the distance between the elements at the corresponding chamber and which chambers are interconnected by restricted passages of convergentdivergent formation, the passages being formed and arranged to cause the issuing uid therefrom vto be directed transversely across the succeeding