GB2118291A - Plate-type heat exchanger - Google Patents

Abstract

The plate-type heat exchanger comprises bars (2, 2a) disposed in sandwich between the plates (1, 1a... 1n) of the heat exchanger for defining superimposed channels (3, 4). The bars are formed of substantially C-shaped sections rigidly connected to a part (5) forming a stiffening element by one at least of its walls. The C-shaped section and the stiffening element have substantially parallel axes, possibly bent or angled. <IMAGE>

Description

SPECIFICATION Plate-type heat exchanger The present invention relates to plate-type heat exchangers which are formed by a succession of plane plates forming primary heat exchange elements spaced apart by small bars alternately arranged in transverse directions for defining sets oftransverse channels in which are possibly disposed secondary heat exchange elements, for example corrugated sheets, which improve the thermal exchange characteristics of the heat exchanger.

In some applications, it is necessary to design the plate-type heat exchangers with shapes different from rectangular. In particular, it isfrequentthatthe plate-type heat exchangers have to be designed with one rectangular portion and two triangular-shaped end portions. This arrangement is easily provided by using solid small bars which can be easily folded or bent.

However, it has been proved that the use of solid bars offers various disadvantages. Actually, their thermal inertia is very high relative to that ofthe plates and the secondary heat exchange elements connected to them. It results therefrom differential expansions which are a serious disadvantage, mainly for large sized heat exchangers. Moreoverthesolid bars are heavy, thereby increasing the cost price ofthe heat exchangei-.

The present invention provides a new heat exchan gersolving the problems hereabove discussed by making possible to manufacture heat exchangers of the hereinbefore mentioned type, which are of a light construction, which can be easily conformed according to needs, and which can be brazed in a simple way, possibly at the same time as collecting flanges, which can also exhibit a low thermal inertia. Moreover, the plate-type heat exchanger ofthe invention can be constructed for operating eitherwith a circulation of the crossed type or ofthe counter-flow type.

The invention uses sections in the shape of hollow beams which are extremely resistant to compression efforts.

Moreover, it is possible with the invention to avoid a high temperature gradient between the bars and other parts, the effect of which is to facilitate the manufacturing operations, particularly those relating to brazing.

According to the invention, the plate-type heat exchanger of the type comprising bars arranged in sandwich between the plates ofthe heat exchanger for defining superimposed channels, the bars being formed by substantially C-shaped sections, is characterized in that each ofthe C-shaped sections is rigidly connected to a part forming a stiffening element by one at least of its walls, the C-shaped section and the stiffening element having substantially parallel axes, possibly bent of angled.

Various other features ofthe invention will become more apparent from the detailed description which follows.

Embodiments of the invention are shown byway of non limiting examples, in the appended drawings wherein: Figure lisa partial broken away perspective view of part of a plate-type heat exchanger constructed according to the invention; Figure 2 is a partial perspective view showing a detail of Figure 1; Figures 3 and 4 are perspective views showing two alternative embodiments; Figure 5 is a longitudinal sectional perspective view of another embodiment; Figure 6 is a partial perspective view of a heat exchanger embodying the invention; Figures7to 10 are partial perspective views showing various embodiments of one ofthe elements constituent ofthe heat exchanger of FigureS.

The plate-type heat exchanger shown in Figure 1 comprises plates 1, la, 1 b,. . . which are kept apart from each other by composite bars 2, 2a extending respectively in the longitudinal direction and the transverse direction. The plates and bars thus define longitudinal channels 3 and transverse channels 4.

The composite bars 2 are made from U-shaped sections in which is arranged a stiffening element5.

In Figure 1, the stiffening element 5 is formed by a calibrated wire which is advantageously disposed so asto betangentthe plane defining the ends ofthe C-shaped sections. The diameter of the wire 5 corresponds exactly to the spacing between the wings ofthe C-shaped section.

The hereabove arrangement which allows using commercially available calibrated wires, is particularly little costly to realize and permits, before placing the wire 5, bending orfoiding the sections 2, 2a when the heat exchanger has to be of a shape different than a rectangular shape.

In order to join the stiffening element 5 and the section containing it, it is advantageous to ruse a glue, and moreparticularlyaglueformed byanorganic binder containing in suspension a powdered brazing alloy.

As is shown in the drawings it is advantageous to provide the channels 3 and 4 with corrugated sheets 6, Saforming secondary heat exchange elements of same nature or different nature than the plates, therebyforming a pile which can be brazed in a single operation while it is maintained under a slight over pressure, the stiffening element 5 with which the composite bars 2, 2a are provided preventing a deformation and crushing of the pile formed.

The stiffening element Scan be provided by other means than by a wire and can also obviously be a tube.

Figure 3 shows an embodiment in which the stiffening element5 is formed by a ribbon 5a. The ribbon 5a is p ref era bly corrugated as shown, or zigzag-shaped which imparts to ita good stability when placed in the section.

As in the previous case, the stiffening element 5 is advantageously connected to the section by an organic binder containing in suspension a powdered brazing alloy. The arrangement described with refer enceto Figure 3 enablesto make channels 3 or4 of greater heightthan in the embodiment of Figure 1.The stiffening element 5 can also be formed by a tube, at least in the rectil inea r portions of the sections.

Figures 1 and 2 show that collecting flanges 60 can be easily put in place on the pileforming the plate-type heat exchanger. According to Figures 1 and 2, the collecting flanges comprise T-shaped uprights 7 and angle-shaped cross-pieces 8. The central portion 7a of the T is notched at its two ends as shown in Figure Z, at 9, in orderto provide an interlocking fit ofthe cross-piece 8, which can be for example soldered or glued in the same way as the stiffening element 5 in the sections 2, 2a. The width of the halfwing 7b of the T-shaped section is chosen for matins the length of the wings of the C-shaped sections 2.In this way, the halfwings7bcomein engagementwiththe ends of the sections and with the ends ofthe stiffening elements 5 at th e same time as the core 7a of the T-shaped section covers the end of the section 2a.

It is advantageous to braze the heat exchanger assembly after having put in place the collecting flanges 6. In this way, there is provided a particularly resistant unitary assembly to which various parts can be connected, either by soldering or only by mechanical means by using to this end the wing 7c of the T-shaped section and the side 8a of the angles 8.

In some cases, it is possible, as is shown in Figure 4, to arrange the stiffening element 5, formed advantageously by a corrugated ribbon 5a, not inside the C-shaped section 2 but outside the section. The assembly of the core is performed as previously, preferably after eventually shaping the section 2.

Figure 5 shows an other embodiment in which the plates 1,1.... 1 nare formed with holes 9 and kept spaced apart, on the one hand, by means of sections 2 having stiffening elements 5 and, on the other hand, by means of ring-shaped braces 10. The braces 10 can be formed in the same way as sections 2.By disposing the braces 10 in the channels 4 and the sections forming the bars in the channels 3, there is the possibility of providing a heat exchangerwith a counter-current circulation as is shown by arrows f1 and f2. Other bar forming sections can of course be placed on the lateral sides ofthe channels 4, and also annular braces possiblyformedwith holes can be arranged inthe channeis 3 in orderto makethe brazing of the pile easier. Figure shows also that the ducts formed by the braces 10 and the holes 9 of plates 1, la... In can be provided on the one hand with unions 11 and on the other hand with plugs 12.The drawings showthatthe braces 10 can also be provided with stiffening elements 51.

The stiffening element 5 of Figure 6 is a calibrated wire extending over the whole length of the C-shaped section, and having, from place to place, notches 13 formed in those of its generating lines which are in contact with the wings of the C-shaped section. The notches 13 can be in alignment with each other or, on the contrary, off-set relative to each other.

The wire 5 is connected and fixed to the corresponding C-shaped section by a glue before carrying out the brazing of the heat exchanger which provides the final fixation of the wire 5 forming the stiffening element with the corresponding section 2.

Figures 7 to 10 show various other alternative embodiments. According to Figure 7, the stiffening element is formed by a corrugated band 14 in which are formed apertures 15. The corrugated band has a height corresponding to the distance between the two wings ofthe section 2, thereby allowing the edges of the band 14to be first glued and then brazed to the section 2.

In Figure 8, the stiffening element is formed by a C-shaped section 16, the wings of which come to bear by their outersurface against the inner surface ofthe wings of the sections 2. The section 2 and 16 have the same length. Apertures 15 are provided in the bottom ofthesection 16.

Figure 9 shows an alternative embodiment which is similar to the embodiment shown with reference to Figure 7, but the corrugated band 14is formed with notches 13 starting from the edges forming the end faces of said band 14.

Figure 10 corresponds to Figure8, but the C-shaped section 16 comprises also notches 13 which are formed concurrently in the bottom of the section and in the wings.

As results from the various embodiments described, the space 17 defined between the inner walk of the bottom of the section 2 and the opposite face of the stiffening element 5, 14 or 16 is always in communication with the inside ofthe corresponding channel 3 or 4, so thatthe brazing flux can flow without being trapped in the space 17. Likewise, during the operation of the heat exchanger, a high temperature gradient cannot exist between the space 17 and the inside of channels 3 or 4. The possiblewashing operations, after the brazing, are carried out more easily when the stiffening element isformed with the notches 13.

Claims (19)

1. A plate-type heat exchamger ofthetype comprising bars disposed in sandwich between the plates ofthe heat exchanger for defining superimposed channels, the bars being formed of substantially C-shaped sections, characterized in that each ofthe C-shaped sections is rigidly connected to a part forming a stiffening element by one at least of its walls,the C-shaped section and the stiffening element having substantially parallel axes, possibly bent or angled.

2. A heat exchanger according to claim 1, wherein the stiffening element ofthe sections is formed of a wire or a tube, and preferably a calibrated wire.

3. A heat exchanger according to either claims 1 or 2, wherein the stiffening element ofthe sections is formed of a ribbon.

4. A heat exchanger according to anyone of claims 1 to 3, wherein the ribbon is connected by its edges to the innerwall ofthewings of the C-shaped section.

5. A heat exchanger according to anyone of claims 1 to 4, wherein the stiffening section is formed of a corrugated or a zigzag-shaped ribbon.

6. A heat exchanger according to anyone of claims 1 to 3 and 5, wh erei n th e stiff eni ng element formed of a corrugated band, is fixed by the apex of its corrugations to the inner wall of the bottom wall of the C-shaped section.

7. A heat exchanger according to anyone of claims 1 to 6, wherein the stiffening element is putin position in the section after bending orfolding said section.

8. A heat exchanger according to anyone of claim 1 to 7, wherein the stiffening element is connected to the section by an organic binder containing a powdered brazing alloy.

9. A heat exchanger according to anyone of claims 1 to 8, wherein a pile of the plates and bars made of composite sections is connected to collecting flanges.

10. A heatexchangeraccording to anyone of claims 1 to 9, wherein the collecting flanges comprise two T-shaped uprights and two angle-shaped crosspieces, said flanges being connected by brazing to said pile.

11. A heat exchanger according to anyone of claims 1 to 10, wherein the plates are formed with holes corresponding to annular braces disposed in one at least of series of channels which are defined by the plates.

12. A heat exchanger according to anyone of claims 1 to 11,wherein braces, possiblyformedwith holes, are placed in alignment with those in one ofthe series of channels.

13. A heat exchanger according to anyone of claims 1 to 12, characterized by unions and plugs provided on the end plates in alignment with the annular braces.

14. A heat exchanger according to anyone of claims 1 to 13, wherein the annular braces are provided with stiffening elements.

15. A heat exchanger according to anyone of claims 1 to 14, wherein the channels are provided with secondary heat exchange elements.

16. A heat exchanger according to anyone of claims 1 to 15whereinthestiffening elements are formed with at least one series of notches or apertures communicating the inside of said C-shaped section with the channel which is formed by said section.

17. A heat exchanger according to anyone of claims 1 to 16, wherein the stiffening elements are formed with notches which open at the level ofthe surface of the wings ofthe C-shaped sections which contain said stiffening elements.

18. A heat exchanger according to anyone of claims 1 to 17, wherein the stiffening elements have a height corresponding to the space between the wings of the C-shaped section, said stiffening elements being brazed to said C-shaped section.

19. A plate-type heat exchanger, substantially as hereinbefore described with reference to any one of the embodiments shown in the accompanying drawings.