FR2608746A1 - HEAT EXCHANGER WITH SPIRAL EXCHANGE CIRCUITS; RIB PLATE FOR SUCH AN EXCHANGER - Google Patents

Abstract

HEAT EXCHANGER WITH A STACK OF SPIRAL RIBBED PLATES. EACH RIBBED PLATE INCLUDES ON BOTH SIDES OF THE RIBS IN SPIRAL 2, 3 FORMING AN INTEGRAL PART OF BASE 4 OF PLATE 1, AND ON ONE SIDE, FOR ONE OF THE FLUIDS, OF SPIRAL RIBS 2 WITH DEXTRORSUM WINDING AND ON THE OTHER SIDE, FOR THE OTHER FLUID C, THE SAME NUMBER OF RIBS IN A SPIRAL 3 HAS SENESTRORSUM WINDING, THESE RIBS BEING EXACTLY COINCIDENT BY THEIR BASES, SO THAT THE RIBS 2 OF ONE FACE OF PLATE 1 ARE IN THE EXACT EXTENSION OF THE RIBS 3 ON THE OTHER SIDE.

Description

Heat exchanger with spiral exchange circuits

  Ribbed plate for such an exchanger.

  The present invention firstly relates to a heat exchanger with spiral exchange circuits, of the type comprising a stack of conductive plates of

  heat separated by a rib extending from each

  that side of these plates and defining said circuits

  spiral exchange, these plates thus separating

  watertight lesson, the two fluids between which heat exchange must take place, and the exchange circuits of each of the two fluids being connected in

  parallel, at the ends respectively

  dull and external spirals, on the one hand to at least one inlet manifold of the fluid considered, on the other hand

  at least one outlet manifold for this fluid.

  Such heat exchangers are already known, for example from German patent no. 669,442. In these exchangers, however, only one spiral rib is provided on each face of the base plate, this

  which only has the favorable effect of lengthening the

  course of the fluid on the exchange plate. In other words, each side of the plate has only one

  path for all the fluid entering or leaving it.

  This has the disadvantage of increasing the pressure drop.

  Furthermore, it should be noted that in known exchangers the ribs, which moreover are not always vis-à-vis on the two opposite faces

  plates, only constitute partitions

  tion which, as indicated above, is intended only

  to lengthen the paths of the fluids, and that they do not

  do not directly participate in heat exchange, do

  able to transmit calories by conductivity.

  The object of the present invention is to remedy these drawbacks of known exchangers, in particular exchangers with spiral exchange circuits, and,

  Indeed, an exchanger of the type defined at the beginning will,

  formally with the invention, essentially characterized in that it comprises several ribs developed in the form of heat exchange surfaces and which form an integral part of the base of said plates, which are therefore ribbed plates on their two faces, and in what the same plate has on one side, for one of the

  fluids, spiral ribs with winding dextror-

  sum and on the other side, for the other fluid, the same

  number of spirally wound ribs senestror-

  sum, these ribs being in exact coincidence by their bases, so that the ribs of one face of the plate

  are respectively in the exact extension of the nerves

vures on the other side.

  Thanks to these provisions, it is possible first of all to reduce the pressure losses of the fluids inside the exchanger because, on each face of the plates, each

  fluid will divide into a number of paths pa-

  rows, depending on the number of spirals.

  Furthermore, while in conventional exchangers the calories are exchanged through a thin wall of the base plate, according to the present

  invention most of the calorie exchange is done

  kills by the conductivity of the ribs which face each other, and which are produced, in the same material as that which constitutes the base plate, by casting, by machining

  mechanical, EDM or stamping.

  According to the invention, the base plate and its ribs form a one-piece assembly promoting maximum heat exchange and giving the entire exchanger a

  excellent rigidity, much higher, for example

  ple, to that of thin plate exchangers. That at-

  will check for significant pressure differences between

  both fluids, without fear of deformation.

  In addition, while in the classi-

  that the only parameters are the distances between

  plates, which prevents any optimization, according to the

  note the number of ribs, their spacing as well

  that their shape and height, determined by the cal-

  ass, will allow to choose, independently of one another, the Reynolds number and the Mach number, and

  * therefore optimize the exchange and mini-coefficients

  put pressure losses on each of the flows.

  Other characteristics of a heat exchanger according to the invention, as well as other advantages, will be mentioned below, with reference to the drawings. It will be the same for the ribbed plates

  intended to equip such exchangers and whose character-

  main fact is that each

  of them comprises on the two faces of the ribs in spi-

  rale forming an integral part of the base of the plate, and in that it bears on one side, for one of the

  fluids, spiral ribs with winding dextror-

  sum and on the other side, for the other fluid, the same

  number of spirally wound ribs senestror-

  sum, these ribs being in exact coincidence by their base, so that the ribs on one side of the plate are in the exact extension of the ribs on the other side.

  Modes of carrying out the invention will main-

  holding be described by way of examples not limited to

  tifs, with reference to the figures of the accompanying drawing in which: - Figure 1 is an axial sectional view of a heat exchanger according to the invention, in a first embodiment comprising flat intermediate plates; - Figure 2 is a plan view of a face of a ribbed plate according to the invention; - Figure 3 is a plan view of the opposite face of the plate of Figure 2; - Figure 4 is a partial sectional view

  radial to a larger scale of a base plate, my-

  trant possible shape for the ribs; and

  - Figure 5 is a view in axial section analog-

  gue to that of Figure 1, showing a heat exchanger according to the invention, in a second form

  of realization, namely without intermediate plates.

  In the various figures the plates nei'u-

  rees were referenced 1. In the exchanger of the fig-

  re 1 all the plates 1 can be identical and

  are circular and oriented in the same direction, except

  see that the cold fluid to be heated flows between the spiral ribs 2 of their left face and the fluid

  hot to cool flows between the ribs in spiral

  3 of their straight face, these ribs being carried by a common base 4. The plates 1 can be made of any suitable heat exchange material and in particular

  may be of materials capable of withstanding weather

  very high peratures, such as carbides and nitru-

  silicon res, etc, and also having excellent

  resistance to corrosive fluids. We can also

  Also consider using metals such as Mg, Al, Cu, Fe, Ni, or any suitable metal alloy. Between the

  ribbed and circular exchange plates 1 are inter-

  wedged flat and circular intermediate plates, conductive of heat, and which aim to separate the flow of a fluid from the neighboring flow

  of the other fluid; they too can be

  in any suitable material and be tightly fixed to the ribbed plates I by soldering

supporting no mechanical effort.

  A cylindrical stack of alternating plates 1 and 5 is thus obtained, with a perfect seal between these plates, which is clamped between two extreme flanges 6 by means of a central bolt 7 screwed into a central and guide core 8 integral with the carcass 9

  of the exchanger, and thanks to the peripheral bolts 10.

  The cold fluid (to be heated) enters the water.

  changer through the lateral inlet 11, accesses the central part of the ribbed plates 1 by central and axial inlet manifolds 12 A, passes between the spiral ribs 2 of the plates, escapes from the periphery of the plates Par axial and external outlet manifolds 13A, and the exchanger by a lateral outlet 14, which is arranged, relative to the stack of plates, on the side opposite to the inlet 11. This course of the

  cold fluid to be heated has been represented by the arrows

  ches F. As for the hot fluid which transfers the calories, it enters the exchanger by the axial inlet 15 located

  on the side of exit 14, access the periphery of the

  ques 1 by axial and external inlet manifolds 12B, passes between the spiral ribs 3 of the plates, escapes from the central part of the plates 1 by

  central and axial outlet manifolds 13B, and of the

  changer by an axial outlet 16, opposite the inlet

  15. This course of the hot fluid to be cooled has been shown

  felt by the arrows C. It can be seen that a counter-current exchanger is thus obtained, since on the plates 1, the spiral path of the fluids is centrifugal for the cold fluid F and centripetal for the hot fluid C; countercurrent heat exchanges also extend at the ends of the exchanger, due to the opposition

  inputs 11.15 and outputs 14.16.

  This counter-current arrangement, known per se, is not compulsory, but has, as we know, the advantage of making it possible to obtain a coefficient

optimal exchange.

  We indicated above that in the mode of

  realization of figure 1 all the plates 1 for

  will be identical and oriented in the same direction.

  Furthermore, to obtain the essential arrangement of the invention, it is appropriate, in this case, that, if we consider two neighboring ribbed plates 1 situated on either side of the same intermediate plate 5, the ribs which on one of the plates define a part of the exchange circuit of one (F) of the fluids are in coincidence with the ribs which on the other plate define a part of the exchange circuit of the other

fluid (C).

  To achieve these conditions, it is necessary that on one face of the plates 1 the ribs determining

  the spiral path of one of the fluids are wound

  ment, for example dextrorsum, opposite to that (then

  senestrorsum) of the ribs which on the opposite side

  end the spiral path of the other fluid.

  This arrangement is best seen in Figures 2 and 3, which are respectively a plan view of a

  side and a plan view of the other side of the nerve plates

  vures 1 of figure 1. We see on these figures that we chose for the ribs 2 of the cold flow the direction of winding dextrorsum and for the ribs 3

  from the hot flow the sense of winding senestror-

  sum, which results in a perfect layout-

  symmetrically of the ribs and therefore an exact coincidence of the bases of the ribs on one side with those of

  the opposite side, as also shown in FIG. 4.

  We also see in these figures 2 and 3 that each

  face carries nine ribs in parallel spirals, deca-

  one of 40 over the next. This arrangement makes it possible, as already mentioned above, to reduce the pressure losses, by obtaining a better distribution of the fluids on each face of the plates. Figures 2 and 3 also clearly show how one can obtain, by simple stacking of the plates 1, the inlet manifolds 12A, 12B and the outlet manifolds 13A, 13B, respectively for the fluids F and C. These manifolds are formed by aligned cells which have the plates 1 in their center and at their periphery and which, to facilitate understanding, have been designated respectively by the same references as the collectors oa'ils they constitute, but with the

  lowercase a, b to the liceu uppercase A, B.

  Thus, considering Figure 2 we see that the spirals formed by the nine ribs 2 connect three central inlet cells 12a to three peripheral outlet cells 13a for the flow of fluid F. Similarly, considering Figure 3 we sees that the spirals formed by the nine ribs 3 connect

  three peripheral input cells 12b with three cells -

  the central output 13b for the flow of the fluid C. The central cells 12a, 13b have the shape of sectors of a circle, and the peripheral cells 12b, 13a have the shape of arcs of a circle. The central cells 12a are interposed with the central cells 13b, and it is the same for the peripheral cells 12b and 13a, so that both at the periphery and in the center, a cell traversed by the fluid F is between two cells crossed by the fluid C and vice versa. This further improves heat exchange considerably in a given space. It should be noted in this regard that an excellent distribution of the different flows is obtained by providing that the number of ribs on each face of the plates is equal to the number of cells or to a small multiple of this number. This is the case in the example described, since we

  has nine ribs for groups of three cells.

  To further improve heat exchange

  inlet and outlet ducts, we can still pre-

  see that the rays, such as 17 or 18, that separate these

alveoli are ribs.

  It may also be advantageous, to take account of the differences in flow rates, to ensure that the passage section offered to the hottest fluid C is significantly greater than that which is offered to the coldest fluid F. To do this. and as is clearly visible

  in figure 4, which shows how the heat is transmitted

  their between the two faces of the same plate, one can advantageously provide that the height of the ribs 3 on one of the faces of the plate, namely that which

  receives the spiral flow of the hot fluid to be cooled

  dir C, is significantly greater than the height of the ribs 2 on the other face of the plate, namely that which receives the spiral flow of the cold fluid

F to reheat.

  The shape of the cross section of the ribs

  which is shown in Figure 4 is of course not

  limiting. This shape could be triangular-

  re, trapezoidal or rectangular, as required.

  Correlatively, it is expected that the cells 12b

  and 13b of the hot fluid C have a notable angle at the center-

  ment more important than that of the cells 12a and 13a of the cold fluid F, as is also clearly visible

in Figures 2 and 3.

  It should also be noted, regarding these

  figures, that the surfaces S which in FIG. 2 surround

  rent the large cells 12b, 13b protrude from the base 4 and are perfectly flat, being intended to constitute sealing surfaces on the

  intermediate plates 5; the same applies to surfa-

  these S 'which in FIG. 3 surround the small cells 12a, 13a. The central and peripheral cells can be produced in the form of cylindrical openings in certain applications where lowering of the manufacturing cost is sought. The plate then has

  circular section openings, on the one hand an opening

  central structure for one of the fluids, surrounded by a section

  line of smaller diameter openings for the other fluid, and secondly peripheral openings,

  alternately for one and for the other fluids.

  As for the course of the spirals, one can choose the Archimedes spiral, as shown in Figures 2 and 3, which delimits for each flow a

  very substantially constant passage section. However

  However, thanks to numerically controlled machines, the use of

  chemical or electroerosion swimming we can consider any more complex curve, in particular the logarithmic spiral, providing an enlarged section towards the

  exit of the spirals for the two fluids, which

  would keep the Mach number of each of the flows substantially constant and would constitute

  further advantage over known exchangers.

  In the embodiment of FIG. 5, the e-

  heat changer, still according to the invention, is devoid of intermediate plates. We assumed here that

  the exchanger was incorporated into a compressor-

  turbine, these devices being housed in a common casing

  20. Cold air (or any other fluid) arrives at the sample

  geur by the peripheral passage 11, is distributed in

  plates 1 by the three central collectors

  12A inlet and escapes through the three external collectors

  13A output laughers (for the sake of simplification, the same references have been used in FIG. 5 as in FIG. 1 to designate the same or similar parts of the exchanger). The hot air (or any other fluid) enters the exchanger through the axial passage 15,

  which distributes it in the plates 1 by the three collectors

  external inlet manifolds 12B, and from which it escapes through the three central outlet manifolds 13B, then through

an axial duct 21.

  Given the elimination of the intermediate plates

  diaries 5, it is appropriate that a “cold” face of a ribbed plate 1 now opposes a “cold” face (and no longer a hot face, as in the case of FIG. 1) of the neighboring ribbed plate , and that its "hot" side opposes the "hot" side of the neighboring ribbed plate located on the other side. To do this, and to keep the essential arrangement of the invention, consisting in ensuring that the spiral ribs

  are exactly in line with each other

  very, it should, in accordance with another provision

  of the invention, to provide a stack of nerve plates

  which are alternately of two different types

  rents, namely of a first type in which the same plate 1 carries on one face, for one F of the fluids, spiral ribs 2 with dextrorsum winding and on the other face, for the other fluid C, the same number of spiral ribs 3 with senestrorsum winding, and of a second type in which, for the same fluids, the directions of winding of the ribs are respectively

opposed to the previous ones.

  We will therefore have to use alternately on the one hand plates 1 similar to those of FIGS. 2 and

  3, and on the other hand plates having winding directions-

  opposite spirals (senestrorsum for the face

  "cold" and dextrorsum for the "hot" side).

  It can be seen in FIG. 5 that one thus obtains between the plates spiral flows of cross section on average double that of the flows of FIG. 1, but these flows are half the number,

for the same number of plates.

  Of course, it will be possible to connect the exchangers according to the invention in series or in parallel, as

  conventional exchangers: in series when

  hait obtain significant efficiency without

  both achieve prohibitive plate diameters, in parallel for large flows, the exchangers can then be mounted in batteries. In this case we will get

  a particularly important compactness and robustness

  aunts using hexagonal plates, allowing a perfect interlocking of the exchangers.

Claims (13)

  1. Heat exchanger with spiral exchange circuits, of the type comprising a stack of heat conducting plates, separated by a rib extending on each side of these plates and defining   said spiral exchange circuits, these separate plates   rant thus, in a sealed manner, the two fluids between which the heat exchangers are to be carried out, and the exchange circuits of each of the two fluids being   connected in parallel, at the respective ends   internally and externally of the spirals, on the one hand to at least one inlet manifold of the fluid considered, on the other hand to at least one outlet manifold of this   fluid, characterized in that it comprises several nerves   vures (2,3) produced in the form of sample surfaces   thermal age and which form an integral part of the base (4) of said plates, which are therefore ribbed plates on their two faces, and in that the same plate (1) bears on one face, for one (F) of   fluids, spiral ribs (2) with dex winding   trorsum and on the other face, for the other fluid (C), the same number of spiral ribs (3) with senestrorsum winding, these ribs being in exact coincidence by their bases, so that the ribs (2) d 'one side of the plate (1) are respectively in the exact   extension of the ribs (3) on the other side.   - 2. Heat exchanger according to claim 1, characterized in that it comprises a stack of   identical ribbed plates (1) separated by plates   ques planar intermediates (5), and in that, if we consider two neighboring ribbed plates (1) located on either side of the same intermediate plate (5),   ribs which on one of the plates define a part   tie of the exchange circuit of one (F) of the fluids are in coincidence with the ribs which on the other plate define a part of the exchange circuit of the other fluid (C).   3. Heat exchanger according to claim   1, characterized in that it does not have any plates   intermediate, and in that it comprises a stack of ribbed plates which are alternately of two different types, namely of a first type in which the same plate (1) bears on one face, for one (F) of   fluids, spiral ribs (2) with dex winding   trorsum and on the other side, for the other fluid (C), a   same number of spiral ribs (3) with winding   nestrorsum, and of a second type in which, for the same fluids, the directions of winding of the ribs are   respectively opposed to the previous ones.   4. Heat exchanger according to any one   of the preceding claims, characterized in that   the internal ends of the spirals constituting the circuits for exchanging one (F) of the fluids are connected to at least one inlet manifold (12A) of this fluid and the external ends of the same spirals are connected to at least one manifold ( 13A) outlet of this fluid, the arrangement being reversed for the exchange circuits of the other fluid (C), so that the exchanges are counter-current. 5. Ribbed plate intended to be used in a heat exchanger in accordance with any one of   Claims 1 to 4, characterized in that it comprises   te on both sides of the spiral ribs (2,3) do   sant integral part of the base (4) of the plate (1), and- in that it bears on one side, for one (F) of   fluids, spiral ribs (2) with dex winding   trorsum and on the other side, for the other fluid (C), a   same number of spiral ribs (3) with winding   nestrorsum, these ribs being in exact coincidence by their bases, so that the ribs (2) of a face of   the plate (1) are in the exact extension of the nerves vures (3) on the other side.   6. ribbed plate according to claim 5, characterized in that on each of its faces, the spirals connect at least one central cell (12a, 13b) to at least one peripheral cell (12b, 13a), these cells being intended to constitute by their alignment-   ment, when several plates (1) are stacked,   pectively input collectors (12A, 12B) and fluid outlet (13A, 13B).   7. ribbed plate according to claim 6, ca-   characterized in that it comprises several central cells (12a, 13b) having the shape of sectors of a circle, and the same number of peripheral cells (12b, 13a) in form of arcs of a circle.   8. ribbed plate according to claim 6, characterized in that said cells are of circular shape.   9. ribbed plate according to claim 7, ca-   characterized in that the central cells (12a) and   ripherics (13a) which, on one of the faces of the plate   (1), are connected by several spirals for the flow-   ment of one (F) fluids are inserted respectively with the central (13b) and peripheral (12b) cells   which, on the other side of the plate, are connected by more   spirals for the flow of the other fluid (C).   10. ribbed plate according to claim 7 or 9, characterized in that the central (12a) and peripheral (13a) cells which, on one of the faces of the plate   (1), are connected by several spirals for the flow-   ment of the cold fluid (F) to be heated have a significantly smaller center angle than that of the central (13b) and peripheral (12b) cells which, on the other side of the plate, are connected by several spirals   for the flow of the hot fluid (C) to be cooled.   11. Ribbed plate according to any one of   claims 5 to 10, characterized in that the height   ribs (3) on one of the faces of the plate, namely that which receives the spiral flow of the hot fluid which transfers the calories (C), is notably greater than the height of the ribs (2) on the other face of the plate, namely that which receives the spiral flow of the cold fluid (F) to be heated. 12. Ribbed plate according to any one of   claims 5 to 11, characterized in that each fur   opposite the ribs have a spiral course of Archi-   meditate. 13. Ribbed plate according to any one of   claims 5 to 11, characterized in that on each   opposite the ribs have a logarithmic spiral course than.