FR3058787B1 - HEAT EXCHANGER - Google Patents

Abstract

Heat exchanger for the heat exchange between a first fluid (1 ') and a second fluid (2') at at least one heat exchange zone, the heat exchanger comprising at least a first duct (1) arranged for the circulation of the first fluid (1 ') and at least one second duct (2) arranged for the circulation of the second fluid (2'), the at least one first duct (1) and the at least one second duct ( 2) being separated at the level of the at least one heat exchange zone by at least a first wall (4 ') delimiting at least partially the first duct and at least a second wall (4) delimiting at least partially the second duct at least a portion of the first wall (4 ') being configured to be brought into contact with the second wall (4) by the pressure of the first fluid and for a flow caused by leakage of the second fluid through the second fluid wall flows between the two walls.

Description

The present invention relates to the field of heat exchangers, and more particularly that of heat recovery systems for domestic hot water production installations.

There are known products that use the heat of the water discharged into the drain of a shower or bath, to preheat the cold water supplying the thermostatic mixing valve of the shower and / or the balloon of the production installation domestic hot water. These products consist of a heat exchanger and a connection system to the gray or dirty water drainage system and to the cold water supply.

The regulations applying to these products require that the heat exchange be done through a double wall, with a means of leak detection to prevent the contamination of cold drinking water by greywater. The regulations also require that the materials used for the drinking water circuit inside the heat exchanger are compatible with the potable nature of this water. Finally, the regulations require that the materials used for the greywater circuit inside the exchanger be resistant to chemicals, especially known, present in these greywater.

These various technical and regulatory constraints lead to high costs for the manufacture of existing products, particularly because of the cost of the material part with the use of double-walled stainless steel or copper heat exchangers, which is difficult to maintain. improve the performance without increasing the exchange surface and therefore the cost of the material part.

The present invention aims to solve all or some of the disadvantages mentioned above. For this purpose the invention relates to a heat exchanger for the heat exchange between a first fluid and a second fluid at at least one heat exchange zone, the exchanger comprising at least a first conduit arranged for circulation of the first fluid and at least one second duct arranged for the circulation of the second fluid, the at least one first duct and the at least one second duct being separated at the level of the at least one heat exchange zone by at least a first wall at least partially defining the first duct and at least one second wall at least partially delimiting the second duct, at least a portion of the first wall being configured to be brought into contact with the second wall by the pressure of the first fluid and for a flow caused by a leakage of the second fluid through the second wall flows between the two walls.

The fluids considered are mainly liquids.

A conduit means a tube allowing the flow of fluids, the section of which does not have a division between the inlet and the outlet of the tube.

According to one aspect of the invention, the pressure of the first fluid in the first conduit maintains at least a portion of the outer surface of the flexible portion of the wall of the first conduit in contact with the second conduit wall.

According to one aspect of the invention, said at least one second conduit is arranged in at least one plate, which can be rigid or flexible.

According to one aspect of the invention the second wall comprises a complex component.

According to one aspect of the invention the complex component comprises a metal film and an organic film.

According to one aspect of the invention the metal film comprises an aluminum foil.

According to one aspect of the invention the complex component comprises an aluminum foil having a thickness of 10 to 20 microns.

According to one aspect of the invention, the organic film comprises a layer of food heat-sealing material; a material is said to be food if the regulation authorizes the contact of this material with a product intended for food.

According to one aspect of the invention the food heat-sealing material is a food polyethylene.

According to one aspect of the invention the complex component comprises an organic film having a thickness of 30 to 50 microns.

According to one aspect of the invention the second wall consists of a simple organic food film.

According to one aspect of the invention the simple organic food film is food polyethylene of 100 to 200 microns thick, preferably 150 microns.

According to one aspect of the invention the complex component comprises a metal film and an organic film bonded together.

According to one aspect of the invention the second wall comprises a first portion and a second portion facing each other and welded together so as to delimit ducts of 1 to 3 mm in diameter, preferably 2 mm in diameter, for the circulation of the second fluid.

According to one aspect of the invention at least one plate has a rectangular shape.

According to one aspect of the invention at least one plate has a length of between 100 and 1000 mm, preferably between 450 and 700 mm.

According to one aspect of the invention at least one plate has a width between less than the length, preferably between 100 and 250 mm.

According to one aspect of the invention, said at least one first conduit is a flexible sheath.

This aspect of the invention makes it possible to replace stainless steel or copper with thin plastic films, with the advantage of significantly reducing the material cost.

According to one aspect of the invention the at least one first wall comprises a complex film with an inner layer of PE or PVC.

According to one aspect of the invention the inner layer of PE or PVC has a thickness of 10 to 100 microns, preferably 20 to 50 microns.

According to one aspect of the invention, the constituent film of the first or second wall is simple (monolayer) or complex (multilayer), with a total thickness of 50 to 200 microns, and comprises at least one heat-sealing inner layer. On the other hand, by replacing the double wall usually made of metal with thermal bridges between the two walls, by at least one plastic film, the heat exchange surface is maximized by ensuring a contact of the two walls on a larger portion of their respective surface thanks to the fluid pressure.

According to one aspect of the invention, the pressure of the first fluid in the first conduit is less than the pressure of the second fluid to be protected in the second conduit. Thus in case of leakage, the upper pressure of the second fluid allows it to flow between the two walls and to be collected by a leak detection device.

According to another aspect of the invention, bonding points are disposed between the outer surface of said at least a portion of the first wall of said first conduit and the second wall, to further optimize the heat exchange surface by supplementing the effect of fluid pressure.

According to another aspect of the invention, said first conduit is disposed between two plates.

According to another aspect of the invention, the walls of the ducts are configured to be impermeable to the fluids that pass through them; in the event of leakage of one of the ducts, the wall of the other duct is impermeable to the leaking fluid; in particular, the at least one flexible portion of the at least one first conduit is impervious to the second fluid passing through, under the effect of a leak, the wall of the second conduit. Thus is avoided the contamination of the drinking water circulating in the second conduit of the exchanger by the gray water of the first conduit.

According to another aspect of the invention, the heat exchanger comprises a leak detection device, so that the second fluid passing through the wall of the second conduit under the effect of a leak is collected by a leak detection device .

According to another aspect of the invention, the at least one first conduit is a single first conduit, and the at least one second conduit is arranged in a plurality of plates, the location and the backside of each plate being contact with at least a portion of the wall of said first conduit.

This configuration makes it possible to avoid the disadvantage of known plate heat exchangers, in which the flows of the two fluids are each divided into several layers after their entry into the exchanger and before passing through the different plates, and are then reassembled at the same time. exit of the exchanger; these zones of division and of meeting of the flow constitute as many obstacles to this one and favor the clogging of the conduits. In the device according to the invention, only the drinking water circuit is divided, the greywater will circulate around the plates in a single layer of water, which avoids clogging despite fluids loaded with various fibers, such as hair, hair, and soap; this aspect is all the more advantageous as the gravitational flow slope of these waters is often low due to specific integration constraints, particularly in the case of shower or bath type installations. This advantage makes it unnecessary to add a filter and a backwash cleaning system that are often required in conventional plate heat exchangers.

According to another aspect of the invention, the plates of said plurality of plates are made of rigid or flexible material.

According to another aspect of the invention, the plates of said plurality of plates are superimposed.

According to one aspect of the invention the superimposed plates are spaced from 1 to 5 mm, preferably from 1 to 3 mm.

According to another aspect of the invention, said single first conduit is serpentine disposed between the superimposed plates of said plurality of plates, thereby providing unobstructed flow between the superimposed plates of said plurality of plates.

According to another aspect of the invention, the ducts arranged in the plates of said plurality of plates are fed in series or in parallel.

A heat exchanger according to one or the other of the preceding configurations can be used to preheat a second fluid input to a domestic hot water production installation with a first fluid discharged by said installation.

A heat exchanger according to one or the other of the preceding configurations can also be used to heat any type of food fluid to be protected with a non-food fluid, such as, for example, the brine of a solar installation. The domestic hot water production installation can be combined with a shower or a bath, or with a hot water tank. The invention will be better understood with the aid of the description which follows with reference to the appended diagrammatic drawings, representing by way of nonlimiting examples one or more embodiments of the invention.

Figure 1 shows a schematic cross-sectional view of the flexible wall of a first conduit in contact with a plate.

Figure 1A shows a more detailed schematic view of the plate of Figure 1.

Figure 2 shows a schematic sectional view of the flexible wall of a first conduit in contact with two superposed plates.

Figure 3 shows a sectional view of a first duct that winds between the plates of a plurality of superposed plates.

Figure 4 shows an example of use of a heat exchanger according to the invention for recovering the heat of the water at the outlet of a shower installation for heating the cold water at the inlet of this installation.

Figure 5 shows a schematic view of the exchanger of Figure 3 in a sealed recovery tank with a leak detection member.

Figure 6 shows a perspective view of an embodiment of flexible sheath.

Figure 7 shows a perspective view of the flexible sheath of Figure 6 interposed between two superimposed plates.

Figure 8 shows a perspective view of an embodiment of an exchanger comprising a serpentine duct disposed around ten superimposed plates.

In FIG. 4, the shower tray 13 is identified with its drain 14 which collects greywater and discharges it to the heat recuperator, which preheats the cold water that is conducted 17 in the heat recovery unit before it rallys. 18 the mixer 19 which feeds the shower 22 with the mixture of hot water 20 and preheated cold water 18. The gray water is then permanently discharged 21 after passing through the heat recovery unit 16. The heat exchanger described below with reference to Figures 1, Ibis, 2, and 3 constitutes the main component of the heat recovery unit 16, whose function is to preheat the cold water in contact with gray water still hot.

FIGS. 1 and 2 schematically show a double-walled exchanger adapted to components with a flexible wall, or to components whose at least one of the walls is flexible, at least in part, and applied to the production of a recuperator of heat for the production of domestic hot water for supplying a hot water tank, or a shower or bath mixer, or even both types of installation simultaneously.

The walls of the plates 2 and 3 of Figure 2 are made of material promoting heat transfer; the material may be rigid, stainless steel or copper for example, or flexible; in this case, the plate comprises at least one plastic sheet, and / or a coated or coated textile support, and / or a coated grid; in all cases, the plate has an internal geometry defining flow channels for distributing and circulating a fluid 2 'inside the plate, to promote a heat exchange between the fluid 2' and a fluid 1 'flowing inside a duct 1 whose flexible wall is in contact with the surface of the plate in the shape of the external geometry of this surface.

For the intended application, it is the cold potable water entering the shower that circulates 2 'inside the plate or plates 2, 3. For this application, the regulation requires that the material chosen for the realization the walls of the plates are compatible with the potable nature of the water. According to one embodiment, the wall 4 comprises an organic component 22 and metal component 21 as shown in FIG. In this case the drinking water is in contact only with the organic component. The metal material may be an aluminum foil 10 to 20 microns thick, the organic material a food grade polyethylene, or other food heat sealing material 30 to 50 microns thick; the metallic material and the organic material are glued together according to a known method of bonding to create a complex film; the complex films vis-à-vis are then welded together to define channels of about 2 mm in diameter. It is also possible to make the wall of the plates of entirely organic material, for example a simple polyethylene film of about 150 microns thick. Preferably, a plate is between 450 and 700 mm long by 100 to 250 mm wide, the plates can be assembled together, superimposed, leaving a space between the plates of 2 to 3 mm. The hot water recovered at the outlet of the installation of the shower, evacuated by the receiver of the installation, is called gray, that is to say dirty, and in particular charged with various fibers, such as hair, hair, soap, which can clog or foul the heat exchanger. These gray waters constitute the fluid 1 'which circulates in the duct 1 in the form of a flexible sheath, arranged between two plates 2, 3. The material constituting the wall (4') of this duct must be resistant to the chemicals present in these ducts. gray water. Thus, according to one embodiment, the wall of the greywater sheath is composed of a complex film with an inner PVC layer of 20 to 50 microns.

Figures 6 and 7 show an embodiment of flexible sheath for greywater and plates for drinking water, corresponding to schematic views 1, Ibis and 2 and described above.

The pressure of the fluid 1 'is less than that of the fluid 2' which constitutes the fluid to be protected. When the fluid 1 'flows, its pressure makes it possible to fill the entire space between the plates containing the fluid 2', and thus to ensure a maximum exchange surface between the two walls 4 and 4 '. It is also possible to supplement the effect of pressure with additional bonding points to further maximize the exchange surface.

The plates, rigid or flexible, 2, 3 are sealed and have an inlet and an outlet for the fluid 2 'circulating inside. Nevertheless, in the event of leakage of the fluid 2 ', its pressure greater than that of the fluid 1' allows the fluid 2 'to flow between the two walls and to be collected in a sealed tank 24 to detect the leak 23, thanks to example to a filling detection device incorporating a safety member that will alert as soon as possible on the presence of a leak. In particular two options are possible: the walls are not fixed together, and in this case the leakage water can flow freely. the walls are fixed together by bonding points, and the drinking water under pressure can flow between the bonding points; in this case a leak on greywater will take longer to detect.

According to one aspect of the invention, represented in FIG. 3, at least two plates 9, 10, 11 are superimposed, in which the cold drinking water circulates, and the flexible duct 6 in which the gray water 6 'of circulation circulates. snakes around the stacked plates. This arrangement makes it possible to benefit from the performance of a plate heat exchanger with a fluid loaded with fibers without risk of clogging.

According to another aspect of the invention, the duct 6 is made of elements of rigid or flexible material assembled in series so as to form a coil without hindrance to the flow of greywater 6 '.

FIG. 8 is a perspective view of an exemplary embodiment of an exchanger composed of ten superimposed plates in which drinking water circulates to be heated, with gray water circulating without obstacle in a serpentine duct 6.1, disposed between the superimposed plates 9, 10, 11, 2, according to the further illustrations of Figures 6 and 7.

Claims (10)

1. Heat exchanger for the heat exchange between a first fluid (Γ) and a second fluid (2 ') at at least one heat exchange zone, the exchanger comprising at least a first pipe (1) arranged for the circulation of the first fluid (Γ) and at least a second conduit (2) arranged for the circulation of the second fluid (2 '), at least one of the ducts of the at least one first duct (1) being a sheath flexible, the at least one first conduit (1) and the at least one second conduit (2) being separated at the level of the at least one heat exchange zone by at least a first wall (4 ') delimiting at least partially the first duct and at least one second wall (4) defining at least partially the second duct, at least a portion of the first wall (4 ') being configured to be brought into contact with the second wall (4) by the pressure of the first fluid and for a flow caused by a leak of the second fluid e through the second wall flows between the two walls. 2. Heat exchanger according to the preceding claim, wherein said at least one second duct is formed in at least one plate (2, 9, 10, 11). 3. Heat exchanger according to the preceding claim, wherein the at least one plate (2) comprises at least two superposed plates (9,10,11). 4. Heat exchanger according to one of the preceding claims, wherein bonding points are disposed between the outer surface of said at least a portion of the first wall (4 ') of said first conduit and the second wall (4). 5. Heat exchanger according to one of claims 2 to 5 as far as they depend on claim 2, wherein said at least one first conduit (1) is disposed between two plates (2,3). 6. Heat exchanger according to one of the preceding claims wherein the at least one first conduit is a single first conduit (6). 7. Heat exchanger according to one of claims 2 to 7 as far as dependent on claim 2, wherein the location and the back of each plate of the at least one plate (2,9,10, 11) is in contact with at least a portion of the wall of the at least one first conduit. 8. Heat exchanger according to claim 8 as dependent on claim 7, as far as dependent on claim 3, wherein said single first conduit (6) is arranged in a serpentine between the superimposed plates of the at least two superimposed plates (9,10,11). 9. Heat exchanger according to one of the preceding claims comprising a leak detection device (23). 10. Domestic hot water production installation comprising at least one heat exchanger according to the preceding claims for preheating a second fluid input (17) of said installation with a first fluid discharged (15) by said installation.