EP0045257B1 - Plate-like heat exchanger with rigid structure - Google Patents

Description

The present invention relates to a rigid structure heat exchanger.

Heat exchangers are the devices used to pass a heat flow from a first fluid flow, which cools, to a second which heats. The plate exchangers consist of a stack of suitably spaced plates, between which the two flows circulate in an alternate arrangement. To obtain the most efficient heat exchange, it is known to adopt the counter-current arrangement of the flows, the speeds in these then being substantially parallel and opposite, but this arrangement makes the constitution of the collection zones quite complex. at the ends of the exchange routes. The less thermally efficient cross-current arrangement is often adopted for this reason.

To allow the economical manufacture of counter-current plate heat exchangers, it has previously been proposed to constitute a manifold by a line of chimneys of circular section for example, perpendicular to the plates, arranged side by side along an edge of stacking and open in a space out of two between the plates, these chimneys being obtained thanks to holes in the plates and to watertight connections. One of the flows is thus collected by the chimneys while the other flow ends, between the chimneys, at the corresponding face of the stack.

The four collectors, for the entry and exit of the two flows, are constituted by the two chimney lines and the two corresponding faces of the flow, where the plates are in pairs in contact. One can choose to collect a flow by the two chimney lines and the other by the faces, or to collect each flow by a chimney line and a face, arrangement adopted for the following description and the figures. The two flows can be substantially equal in mass and volume and a uniform spacing spacing between plates is then adopted. The explanations below correspond to this case but easily extend to different spacings e _i and e ₂ for the two flows.

In the exchangers of this type, the distribution chimneys are preferably of elongated section in the direction of circulation of the fluids from one distribution zone to the other, which makes it possible to obtain large passage sections vis-à-vis -screw of the section corresponding to the thickness between plates.

A plate heat exchanger of this type is described in French Patent No. 1,038,859. It describes a heat exchanger for two media circulating against the current. Plates arranged in parallel provide passages for the fluid media. The end parts of these plates are connected by perpendicular transverse conduits which can have, according to a particular embodiment, a pear-shaped cross section.

However, an exchanger of this type does not have a rigid structure. Indeed, a plate of the stack rests on the plate immediately below by its periphery only. There is no intermediate support point of a plate 1 on the lower plate 2 in the exchange zone. Flanges 1 c, 2 c constitute the edges of chimney perforations. The collars 1c are relatively short while the collars 2c are relatively long. A plate 1 therefore rests on the plate 2 which is lower by the periphery of the collar 2c.

It is therefore necessary to stiffen this exchanger by means of spacers such as the crosspieces 3a.

The exchanger of the invention, on the contrary, relates to a plate exchanger which by itself has a rigid structure. The plates of this exchanger have two planar surfaces, an upper planar surface and a lower planar surface. One of the planar surfaces is formed by the plane of the distribution zone while the other planar surface, on the same side of the exchanger is formed by the plane of the edge of the chimney perforations. When these plates are stacked one on the other, a rigid structure is produced by itself without the aid of any spacer.

More specifically, the plate exchanger of the invention, of the type which includes a stack of suitably spaced parallel plates, said plates comprising a central exchange zone and two parallel edges forming by their stack two distributor blocks, the distribution taking place in a block for one space out of two by direct outlet on the face of the stack, and for the other space out of two, by outlet on a chimney line obtained by perforations of elongated shape in the direction of the flow of fluids from one distributor block to the other carried out across the entire stack, is characterized in that the planes of the parallel edges of the plates are offset on either side of the plane of the central zone of exchange, so that when the stacking of the plates is carried out, one of the edges of a plate is in plan-on-plane contact with the edge of the immediately superior plate, while the other edge of this plate that is in contact with the edge of the immediately lower plate, which achieves a so-called “accordion” structure which closes every second space in each distributor block, and in that the edges of the perforations in the chimneys are deformed in the opposite direction at the offset of the edge relative to the central zone to come into contact with the edge of the perforation of the chimney of the adjacent plate, the plan-to-plan contact of the parallel distribution edges extending to the part of the regions located between the fireplaces, but not to the region opposite the central exchange zone.

The contact of the two plates over a large part of the distribution zone makes it possible to obtain a better robustness of the assembly, in particular when using very thin sheets. The plane of one or two distribution zones is offset from that of the exchange zone, which results in two-to-two contact of these distribution zones, subject to the maintenance of the normal gap between the distribution zone. exchange and the opposite end of each perforation, and subject to the locally raised parts to constitute the walls of the chimneys.

According to the invention, the plates are linked two by two by assembling their edges and / or the edges of the chimneys located in contact. An accordion chain is thus formed. The connections are made all around the chimneys. These connections can be obtained by crimping added or stamped rivets, or they can be obtained directly from the plates themselves by bonding pre-coated areas, by welding plastic films deposited on the plates, by welding the plates themselves. - even when made from an appropriate material. You can still use plastic inserts assembled "in situ".

Lines of distribution chimneys are thus formed, the passage section of which can be as large as desired, in order to supply the entire stack while allowing a fine distribution of the fluid between the plates. The distribution chimneys open only by their short side which is oriented towards the exchange zone. The rigidity of the stack is thus ensured by the two long sides and by the short side of the opening, the walls of which are parallel to the crushing forces.

According to another characteristic of the invention, elongated bosses are formed in the exchange zone. These bosses can be inclined relative to the axis of the plate, in particular oriented alternately, for example at 45 degrees, on either side of the general direction of flow of the gas streams. The height of these bosses can be equal to the spacing pitch of the plates. In this case, each boss then rests on a smooth part of the exchange zone. The height of the bosses can also be equal to the half spacing step of the plates. Thus, when these plates are superimposed in the stack after rotation of one plate out of two by 180 degrees around its transverse axis, these bosses come into contact with each other, for example at a right angle. The continuity of the walls parallel to the axis of the crushing forces is thus ensured. In addition, these bosses increase the length of the path of the gas streams in the exchange zone.

The plate heat exchanger produced in accordance with the invention has its own rigidity qualities which make it possible to considerably reduce the thickness of the plates used, and consequently their weight.

• - la figure 1 représente une vue en perspective d'un échangeur réalisé conformément à l'invention,
• - la figure 2 représente une vue en perspective d'une plaque de l'échangeur représenté sur la figure 1,
• - la figure 3 représente une section longitudinale de la plaque représentée sur la figure 2,
• - les figures 4a et 4b représentent une section longitudinale de l'échangeur selon les lignes A-A et B-B de la figure 1,
• - les figures 5 à 7 représentent différentes variantes de réalisation de l'assemblage des rebords de cheminée de distribution,
• - les figures 8 et 9 représentent les sections longitudinales de variantes de réalisation de l'invention,
• - la figure 10 représente une vue en perspective d'un mode de réalisation dans lequel l'isolation latérale des plaques est réalisée au moyen d'une mousse à porosité fermée, dans laquelle sont noyés des profilés de renforcement,
• - la figure 11 représente une vue en perspective de l'échangeur de la figure 10 montrant la forme du carter seul,
• - la figure 12 représente une vue de détail de l'isolation des plaques de l'échangeur des figures 10 et 11 dans laquelle on a noyé une texture métallique de renforcement.

Other characteristics and advantages of the invention will appear better after the description which follows, given by way of illustration and without limitation with reference to the appended drawings in which:

• FIG. 1 represents a perspective view of an exchanger produced in accordance with the invention,
• FIG. 2 represents a perspective view of a plate of the exchanger shown in FIG. 1,
• FIG. 3 represents a longitudinal section of the plate shown in FIG. 2,
• FIGS. 4a and 4b represent a longitudinal section of the exchanger along the lines AA and BB of FIG. 1,
• FIGS. 5 to 7 represent different alternative embodiments of the assembly of the flanges of the distribution chimney,
• FIGS. 8 and 9 show the longitudinal sections of alternative embodiments of the invention,
• FIG. 10 represents a perspective view of an embodiment in which the lateral insulation of the plates is carried out by means of a foam with closed porosity, in which reinforcement profiles are embedded,
• FIG. 11 represents a perspective view of the exchanger of FIG. 10 showing the shape of the housing alone,
• - Figure 12 shows a detailed view of the insulation of the plates of the exchanger of Figures 10 and 11 in which a metallic reinforcement texture has been embedded.

FIG. 1 shows a perspective view of an exchanger 2 produced in accordance with the invention. This exchanger is a static heat recovery exchanger operating between two gas streams circulating against the current. It can be used in particular for air conditioning and for the recovery of heat lost through the ventilation of premises.

The exchanger 2 is constituted by a stack of stamped rectangular sheets 4. The sheets 4 are stacked with a spacing pitch e (see Fig. 3) and clamped together to determine two separate circuits in which the fluid streams flow. Each sheet 4 has a central zone 6, called the exchange zone, in which the actual heat exchange takes place, and two distribution zones 8 and 10, located on either side of the exchange zone. 6 in which distribution chains 12 and 14 are formed. These chimneys are formed by stamps of elongated shape, arranged in the direction of flow of the fluids. A first gas stream 16 enters the exchanger via the distribution chimneys 12. The fluid 16 circulates along the exchange zone 6 then leaves the exchanger at 17. A second fluid 18 enters the exchanger 2 by the distribution chimneys 14, circulates along the exchange surface 6 and then leaves the exchanger in 19.

According to the invention, the planes of the distribution zones 8 and 10 are offset on either side of the plane of the exchange zone 6 by an amount equal to half the spacing pitch e of the plates 4. As can be seen in FIG. 1, the plane of the distribution zone 8 of the cladding 4 is located lower than the plane of the exchange zone 6, while the plane of the distribution zone 10 is on the contrary elevated from it. The stack of the exchanger plates is produced by alternately superimposing plates such as plate 4 and identical plates turned 180 ° around their transverse axis. Thus, the distribution zone 8 comes into contact with the distribution zone of the immediately lower plate. Likewise, the distribution zone 10 will come into contact with the distribution zone of the plate immediately above.

The exchange zone 6 comprises elongated bosses inclined on either side with respect to the longitudinal axis of the plate 4. In the described embodiment, these bosses are inclined at 45 ° on either side of the general direction of flow of the gas veins. As will be described in more detail in the following text, the height of these bosses is preferably equal to the spacing pitch e of the plates. Thus, when these plates are superimposed, after rotation of one plate out of two, the bosses 20 bear on each other by forming right angles. In addition, the bosses 20 make it possible to substantially increase the length of the path of the gas streams in the exchange zone 6.

According to another embodiment, one could have formed bosses 20 on each of the faces of the exchange zone 6, their height being equal to half the spacing step e. The bosses formed on the upper face of a plate thus come into contact after turning, with those of the upper plate. The continuity of the walls parallel to the axis of the crushing forces is thus also ensured.

FIG. 2 shows a perspective view of a plate 4 of the exchanger shown in FIG. 1. We recognize the exchange zone 6, the distribution zones 8 and 10, the distribution chimneys 12 and 14 and the bosses 20. This figure shows in particular the shape of the distribution chimneys 12 and 14. Elongated openings, respectively 12a and 14a through which the fluids circulate are formed at the top of the stamping. The passage section of exchange chimneys can be as large as desired, which makes it possible to supply the entire stack while retaining a fine distribution of the gas flow. As can be seen in FIG. 2, one end of each distribution chimney, respectively 12b and 14b is formed in the exchange zone 6. This arrangement determines an orifice through which the fluid can flow between the zones of exchange of two successive plates. Thus, the distribution chimneys 12 and 14 only open by their short side 12b and 14b oriented towards the exchange zone 6. The rigidity of the stack is thus ensured along the long sides and the short side remaining. plates thus come to bear one against the other two by two by the edges 1 2c and 14c of the distribution chimneys 12 and 14. The edge 12c comes into contact with the edge of the distribution chimney of the immediately upper plate. The rim 14c of the distribution chimney 14 comes into contact with that of the immediately lower plate.

There is shown in FIG. 3, a longitudinal section of the plate 4 represented in FIG. 2. The respective heights have been indicated in this figure as a function of the spacing pitch e of the plates, the distribution chimneys 12 and 14 and the bosses 20. As can be seen, the planes of the distribution zones 8 and 10 are offset on either side of the plane of the exchange zone 10 by an amount equal to half the spacing step e of the plates. On the other hand, the height of the distribution chimneys 12 and 14 relative to the plane of the exchange zone 6 is equal to the spacing pitch e. Finally, we note that the height of the bosses 20 is equal to the spacing step e. A highly rigid exchanger is thus obtained. This arrangement makes it possible to considerably reduce the thickness of the plates 4 and consequently their weight. In the case of the embodiment described, satisfactory rigidity in all respects was obtained with aluminum sheets 0.2 mm thick.

There is shown in Figure 4 a longitudinal section of the exchanger shown in Figure 1. Figure 4a shows a longitudinal section taken along the line AA which passes in the middle of the distribution chimneys.

FIG. 4b represents a longitudinal section of this same exchanger taken along the line BB which does not cut the distribution chimneys 12 and 14. In order not to overload the drawing, the bosses 20 have not been shown in these figures.

FIG. 4a makes it possible to see the two separate flow circuits for the fluids 16 and 18. The fluid 16 circulates from right to left, in the figure, to exit at 17 from the exchanger while the fluid 18 circulates against flow of fluid 16, that is to say from left to right to exit at 19 from the exchanger.

FIG. 4b shows the connection of the distribution chimneys such as 12 and 14. These connections, carried out all around the chimneys, can be obtained by crimping added or stamped rivets directly from the plates themselves, or by gluing . The manner in which the sealing is achieved between the two gas streams in the distribution zones at the level of the distribution chimneys will be described in more detail with reference to FIGS. 5 to 7.

The exchanger 2 produced in accordance with the invention can be placed directly in a single operation in a housing provided with suitable fixing and connection means. The lateral sealing of the plates 4 is obtained by means of a flexible foam sheet or any other suitable known means.

The longitudinal sealing of these same plates 4 can be ensured as shown in FIGS. 4a and 4b by turning the edges 25 over, or by any other suitable means.

There are shown in Figures 5 to 7 different embodiments of the seal between the edges of the distribution chimneys. The qualification of a heat exchanger being linked to the seal between the two streams of gas flowing against the current, the achievement of this seal is an important characteristic of the exchanger produced in accordance with the invention.

As mentioned above, according to the embodiment described, the plates of the exchanger are made of aluminum sheet with a thickness of 0.2 mm. Three methods are possible for ensuring the connection of the edges 12c of the distribution chimneys. In FIG. 5, these edges are assembled by gluing. This bonding can be carried out with a quick cold glue. It is also possible to deposit a polyethylene film on one of the faces of the plate. The coated faces of the two successive plates are then bonded and they are placed under a hot press so as to melt the polyethylene film. After cooling, it forms a weld. However, the latter method is expensive.

There are shown in Figures 6 and 7, two methods of assembly by riveting. FIG. 6 shows an attached oblong rivet 30, made of aluminum or plastic, while FIG. 7 shows a rivet 32 formed in one of the plates during manufacture and consequently integral with the latter. These two processes have given the best results, both from the point of view of the manufacturing price and of the speed of execution.

In the case of a plate heat exchanger according to the invention made of plastic material, either a hot bonding under press of the edges is carried out in the case where a polyethylene film is used, or by induction, for PVC . It is also possible to use added aluminum rivets 30 as described with reference to FIG. 6.

A heat exchanger has been described in FIGS. 1 to 4, the planes of the distribution zones being offset on either side of the plane of the exchange zone by a quantity spread at half the spacing pitch plates.

Obviously, this is not an obligation and FIGS. 8 and 9 show, in a manner analogous to FIG. 4a, a longitudinal section of a heat exchanger whose planes of the distribution zones are offset by any amount of on either side of the exchange zone plan.

In FIG. 8, each plate has in its distribution zones stamped reliefs of different heights 34, 36, 38 and 40 constituting the chimneys, the edges of the chimneys cooperating with each other.

In FIG. 9, a single distribution zone is provided with a stamped relief 12. In this case, the flange of the chimney cooperates with the edge of the opening made in the distribution zone.

The invention thus described makes it possible to constitute counter-current exchangers with integrated collectors obtained by stacking stamped plates, in which the collectors can take up a large section relative to the section of passage of an elementary flow between two plates. , which allows the stacking of many plates and obtaining very compact one-piece exchangers for given applications. They are used in particular for air conditioning of premises, with small pressure differences from one flow to another, which makes it possible to form the plates of a thin metal sheet, material mainly envisaged for assemblies which have been described.

The exchanger 2 shown in perspective in Figure 10 is constituted by a stack of stamped rectangular sheets 4. The sheets 4 are stacked with a spacing step ₂ .0t clamped together to determine two separate circuits in which the fluid streams flow. A first gas stream 16 enters the upper part of the exchanger. The gas stream 16 circulates along the exchange zone of the exchanger, then emerges at 17. A second fluid 18 enters the upper part of the exchanger via the distribution chimneys 14, circulates along the surface d exchange then spring from the exchanger according to arrow 19. At the upper part of the exchanger 2 are mounted two distributors 16a and 18a which distribute the fluids 16 and 18 inside the respective distribution chimneys. Collectors, of which only the manifold 17a is shown, channel the fluids 17 and 19 which exit from the exchanger. Tie rods 50 hold these two collectors.

According to the invention, the lateral sealing of the plates 4 is obtained by means of a foam 52 with closed porosity. Longitudinal profiles such as 54 are embedded in the foam 52 with closed porosity. These profiles are visible more particularly in FIG. 11. The foam 52 can be an epoxy resin, a prepolymer foam or a phenolic foam.

In FIG. 11, we also note the presence of two rectangular openings 53, made at the level of the distribution chimneys in order to allow the passage of the streams of fluid 16 and 18. In addition to the advantages listed above, the insulation 52 ensures the 'thermal insulation and total sealing between the veins 16 and 18, thanks to the two components of this foam which produces closed cells. This is an important characteristic, because the qualification of a heat exchanger is linked to the seal between the two gas streams circulating against the current. Thanks to the reinforcement by the sections 54, it is possible to eliminate the metal casing of the prior art. This results in a lowering of the cost price of the exchanger in which the casing intervened for a large fraction. In addition, the coating 52 constitutes at the same time the packaging for the purposes of shipping the exchanger.

FIG. 12 shows an alternative embodiment in which a texture 56 has been embedded in the foam 52. The texture 56 may be metallic or plastic. It improves the rigidity of the whole.

The coating 52 can be produced either by injection or by molding.

In an exemplary embodiment, a two-component injectable thermosetting foam was used which became semi-hard in a very short time. The characteristics of this foam are indicated in the appendix below. This foam is deposited using a gun that automatically mixes the two components. To isolate a face, it suffices to place vertically 3 cm from the wall of the exchanger a rigid panel which occupies the surface of this wall. In this panel are made cylindrical openings of 8 mm in diameter which are used both for injecting the foam and for evacuating the air when the foam is injected. After about 60 seconds, this thermosetting foam is dry. It only remains to remove the panel. The side wall of the exchanger is insulated.

Claims (12)

1. Plate-type exchanger of the sort comprising a stack of suitably spaced parallel plates (4) said plates comprising a central exchange zone (6) and two parallel borders (8, 10) forming two distributor blocks by being stacked, distribution being effected in one block, for each alternate space, by direct outflow over the face of the stack, and for the other alternate spaces by outflow from a line of ducts obtained by perforations (12, 14) of elongated form with respect to the direction of fluid flow from one distributor block to the other in respect of each stack, characterized in that the planes of the parallel borders of the plates are offset on either side of the central exchange zone, such that, when a stack of plates is formed, one border of each plate is in face to face contact with the border of the plate immediately above, while the other border of said plate is in face to face contact with the border of the plate immediately below, whereby forming an «accordeon» structure closing alternate spaces in each distributor block, and in that the rims of perforations (12a, 14a) of the ducts (12,14) are deformed in a sense opposite to that in which the border is offset with respect to the central zone, whereby to contact the rim of the perforation of the adjacent plate, the face to face contact of the parallel distribution borders extending to part of the regions located between the ducts, but not to the region (12b, 14b) located facing the central exchange zone (6).

2. Heat exchanger according to claim 1 characterized in that the central zones (6) comprise bosses (20) whose height is equal to the distance between plates, cooperating with a flat surface of one or other of the adjacent plates.

3. Heat exchanger according to claim 1 characterized in that the central zones (6) comprise bosses (20) whose height is less than the distance between plates, cooperating with other bosses located on adjacent plates.

4. Heat exchanger according to either of claims 1 and 2 characterized in that the bosses (20) have an elongated form and are orientated slantwise with respect to the general direction of flow.

5. Heat exchanger according to claim 1 characterized in that deformation of the rims of the perforations (12a, 14a) is produced by pressing, thereby forming at the rim of the perforation a flat portion that is offset with respect to the plane of the exchange zone (6), face to face contact between two adjacent plates thereby being assured.

6. Heat exchanger according to claim 5 characterized in that said flat portions at the rims of the perforations (12a, 14a) are held together two by two by means of detachable oblong crimping means(30).

7. Heat exchanger according to claim 5 characterized in that said flat portions at the rims of the perforations (12a, 14a) are held together two by two by adhesive means.

8. Heat exchanger according to claim 1 characterized in that the deformation of the rims of the perforations (12a, 14a) is brought about by pressing, forming at least one raised portion thereby permitting liaison between adjacent plates by interpenetration and crimping.

9. Heat exchanger according to any one of claims 1 to 8 characterized in that the distance between adjacent flat plates (4) in the exchange zone (6) is constant over the entire stack.

10. Plate type exchanger according to any one of claims 1 to 9, characterized in that it comprises lateral insulation (52) for plates (4), said insulation being formed from closed-cell foam in which are embedded reinforcing profiles (54).

11. Exchanger according to claim 10 characterized in that it additionally comprises a metallic or plastic mesh (56) embedded in the foam (52).

12. Exchanger according to either of claims 10 and 11 characterized in that the closed-cell foam (52) is selected from the group comprising epoxy resins, prepolymer foams and phenolic foams.

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