FR2817332A1 - Tubular coil for heat exchanger consists of two horizontal spirals, each connected to its own vertical connecting pipe and linked by connecting section, coils being connected to vertical pipes on their outside or inside surface - Google Patents

Abstract

The tubular coil for a heat exchanger consists of a first horizontal spiral (9) connected to a first vertical connecting pipe (11) and a second horizontal spiral (10) connected to a second vertical connecting pipe (12). The two spirals are linked by a connecting section (8). The coils are connected to the vertical pipes on their outside or inside surface. Independent claims are included for: (a) a heat exchanger incorporating the coil; and (b) a method for making the coil.

Description

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 The invention relates to the technical field of heat exchangers intended to allow heat exchanges between two fluids.

 In the above field, the invention relates more particularly but not exclusively to the exchangers used for the preparation of domestic hot water by circulation of a heat transfer fluid inside a tubular coil which plunges into a heat-insulated tank containing water to heat.

 In general, the coil comprises one or more windings in the form of a spiral or helix. In order to increase the performance of the coil and more particularly the surface for exchange with the water to be heated, the coil most often comprises at least two windings. Thus, application EP-0 825 386 has proposed to use a coil comprising two stages of turns wound in a spiral around the central axis of the coil. The first turn of the lower stage is connected at the level of an external face of the coil to a first branch connecting the coil to a heating installation, while the last turn of the second stage is connected at the level of the internal face of the coil to a second branch connecting the coil to the installation. Finally, according to this document, the first and second stages are connected by a connecting element connected to the lower stage at the level of the external face of the coil and to the upper stage at the level of the internal face of the coil.

 Such a coil gives full satisfaction in that it relates to its function as a heat exchanger between the liquid circulating inside the coil and the liquid in which the coil plunges.

 However, the structure of the coil is not fully satisfactory insofar as the two connecting branches of the coil, to a central heating installation for example, are located on the one hand at the interior face of the coil and on the other hand at the outer face so that these two branches are particularly distant from each other and it is then necessary to bend them to bring their connection ends together and thus allow connection to the installation of heating in a low volume space.

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 Furthermore, the structure adopted makes it necessary to produce the coil by manufacturing, on the one hand, the lower stage of turns wound in a spiral and, on the other hand, the upper stage of turns wound in a spiral and then to proceed subsequently to the connection. of two winding stages of turns by means of the connecting element which must then be connected by welding to the two stages of turns. However, the execution of this welding operation on the coil then requires checking the quality of the weld and performing a coil test in order to eliminate any risk of leakage at the connection between the first and second stages of coil turns. However, the welding control and the coil test significantly increase the cost price of a coil and the risk of leakage cannot be completely ruled out.

 The need therefore appears to have a coil having a structure which, on the one hand, makes it possible to reduce the connection space of the coil to an installation for supplying heat-transfer fluid and, on the other hand, is suitable for a seamless manufacturing.

 In order to achieve these objectives, the invention relates to a coil for heat exchanger having an axis x-x ', an inner face and an outer face and comprising: a first spiral-shaped turn, connected to a first branch of connection of the coil to an installation and located partly at least in a plane perpendicular to the axis x-x ', - a last spiral-shaped turn, connected to a second branch connecting the coil to an installation, and located partly at less in a plane perpendicular to the axis x-x 'and distant from the plane of the first turn, and - at least one connecting element between the first turn and the last turn.

 According to the invention, the coil is characterized in that the first turn and the last turn are connected to their respective connecting branch at the same face of the coil.

 According to a characteristic of the invention, the first and the last turns are connected to their respective connecting branch at the level of the internal face of the coil.

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 According to another characteristic of the invention, the first turn and the last turn are connected to their respective connecting branch at the level of the external face of the coil.

 According to a preferred embodiment of the coil, the latter comprises at least two stages of turns preferably arranged in a spiral but not exclusively in the form of an Archimedes spiral.

 According to another characteristic of the invention, the coil comprises at least two stages of successive concentric turns, of generally rectangular shape.

 According to a preferred characteristic of the invention, the coil consists of the first to the last turns by a continuous tubular element such as for example but not exclusively a metal tube.

 The invention also relates to a heat exchanger intended to allow heat exchanges between two fluids and using a coil according to the invention. Such a heat exchanger then comprises a tank which is connected, on the one hand, to an inlet pipe for a first fluid and, on the other hand, to an outlet pipe for this first fluid and in which is disposed a coil according to the invention, the first branch and the second branch of which extend outside the tank and are intended to be connected to an inlet pipe and to an outlet pipe for the second fluid.

 Preferably, the coil is adapted in the tank so that its turns are placed in the lower part of the exchanger.

 The invention also relates to a method of manufacturing a coil made from a single tubular element.

 According to the invention, the method of manufacturing the coil consists notably in: - producing, from a tubular element, at least one substantially U-shaped pin having two branches connected by a core, the free ends of the pin being intended to define the connecting branches of the coil, - wind the pin on itself substantially in a turn to form the coil of axis x-x '.

 According to another characteristic of the invention, the method for manufacturing a coil for a heat exchanger from a single tubular element notably consists in:

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- mettre en oeuvre un élément tubulaire, - enrouler l'élément tubulaire sur lui-même à partir d'une région centrale pour définir au moins deux étages d'enroulement en spirale qui forment le serpentin et qui présentent chacun une extrémité libre destinée à former une branche de raccordement du serpentin.

- use a tubular element, - wind the tubular element on itself from a central region to define at least two stages of spiral winding which form the coil and which each have a free end intended to form a branch connecting the coil.

 Various other characteristics of the invention emerge from the description above with reference to the drawings which present different nonlimiting examples of embodiment of the invention and implementation of the method for manufacturing a coil according to the invention.

 Figure 1 is a schematic view of a heat exchanger using a tubular coil according to the invention.

 FIG. 2 is a longitudinal section of the coil of the exchanger as illustrated in FIG. 1.

 Figure 3 is a cross section along line 111-111 of Figure 2.

 FIG. 4 is a schematic elevation of a tubular element used for the manufacture, in accordance with the method according to the invention, of the coil as illustrated in FIG. 1.

 Figure 5 is a perspective illustrating an alternative embodiment of a coil according to the invention.

 FIG. 6 illustrates another possible form for a tubular element intended for the production of a tubular coil according to the method according to the invention.

 FIG. 7 is a longitudinal section of a tubular coil obtained from the element as illustrated in FIG. 6.

 FIG. 8 illustrates another embodiment of a flat tubular element, intended for the manufacture of a coil according to the invention.

 Figure 9 is a schematic view similar to Figure 1, showing another embodiment of a tubular coil, according to the invention, arranged inside a heat exchanger.

 FIG. 10 illustrates yet another embodiment of a tubular coil according to the invention, obtained thanks to a variant implementation of the manufacturing method according to the invention.

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 A heat exchanger, intended to allow heat exchanges between two fluids, in accordance with the invention as illustrated in FIG. 1 and generally designated by the reference 1, comprises a tank 2 connected, on the one hand, to a inlet pipe 3 and, on the other hand, to an outlet pipe 4 of a first fluid. The pipes 3 and 4 are, for example, intended to be connected to a drinking water supply pipe and to a water distribution pipe when the heat exchanger is used for the preparation and storage of domestic hot water. . In order to ensure thermal insulation of the tank 2, the exchanger 1 generally comprises an insulation, not shown, surrounding the tank.

 To ensure the heating of the water contained in the tank, the exchanger 1 further comprises a tubular coil 5 preferably arranged so as to be placed in the lower part of the tank and to bathe in the liquid contained in the tank. 2. As can be seen more particularly in FIGS. 2 and 3, the exchanger 5 has a central axis x-x ′ around which two stages 6,7 surround spiral-shaped turns. The turns of a first stage 6 are substantially all located in a first plane P, substantially perpendicular to the axis x-x't while the turns of the second stage 7 are all substantially located in a second plane P2 perpendicular to the axis x-x 'and distant from the plane P ,. Depending on a position relative to the central axis x-x ', it is possible to define an interior face 1 and an exterior face E of the coil 5.

 According to the example illustrated, the two winding stages 6 and 7 are connected by a connecting element 8 forming an elbow having the shape of a U and extending substantially in a vertical plane at the interior face of the coil 5. Furthermore, the first turn 9 of the coil and the last turn 10 are each connected respectively to a first branch 11 and a second branch 12 for connecting the coil to an installation such as for example a heating installation not shown. Of course, the coil is adapted in the tank 2 so that the connecting branches 11, 12 pass through the tank 2 so that their end is accessible from the outside of the tank.

 As is apparent from FIG. 3 and in accordance with an essential characteristic of the invention, the first 9 and last 10 turns are connected to their respective connecting branch 11 and 12 at

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 on the same face of the coil and according to the example illustrated on the external face E. This arrangement of the invention advantageously makes it possible to place the first and second close to one another. connecting branches so that their ends are located in the vicinity of one another to allow easy connection of the coil 5 to an installation for supplying heat transfer fluid.

 The coil 5, as described above, is manufactured in accordance with the invention in the following manner.

 First of all, a substantially U-shaped pin 15 as illustrated in FIG. 4 is made from a continuous tubular element such as for example a steel tube of type E24.2 / RST 37.2 with outside diameter 33, 7 mm and 2 mm thick. The pin 15 has two branches 16, 17 which are substantially parallel and connected at one end by a rounded core 18. The free ends 19, 20 respectively of the branches 16 and 17 situated opposite the core 18, are shaped to define the connecting branches of the coil 5. According to the example illustrated, the two free ends 19 and 20 are bent at right angles to define the two substantially parallel connecting branches 11, 12.

 The coil 5 is then formed from the pin 15 by winding the latter on itself from the core 18. This winding is, for example but not necessarily, carried out by placing the core 18 on a mandrel and progressively winding the pin 15 so as to obtain two stages of winding spiral-shaped turns as illustrated in FIGS. 2 and 3. This procedure has the advantage of obtaining two stages of winding 6.7 from a single continuous tubular element without the need to resort to any welding operation between one or other of the constituent elements of the coil 5.

This absence of welding then guarantees perfect sealing of the coil 5.

 According to the example illustrated above, the free ends of the pin 15 are bent to make the connecting branches of the coil before the spiral branches of the pin are shaped. However, the bending of the connecting branches could occur after the shaping of the turns.

 As is apparent from FIGS. 2 and 3, when the pin 15 is wound on itself, starting with the core 18,

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 the latter is then located at the inner face 1 of the coil 5 while the connecting branches 11, 12 are located at the outer face E of the coil. However, it could be envisaged to proceed otherwise by winding the pin 15 on itself from the free ends 19 and 20 of the branches 16 and 17. In this case, the connecting branches 11, 12 of the coil 5 would be placed and connected to the first 9 and last 10 turns of the coil, at the interior face 1 of the latter, while the connection of the two stages of turns by the core 18 forming the connecting element 8 would be placed at the outer face E of the coil as illustrated in FIG. 5.

 Furthermore, according to the example illustrated in FIG. 5, the connecting core 18, forming the connecting element 8 between the two stages of the coil, is produced in the form of a sort of expansion lyre. This way of proceeding makes it possible to increase the radius of curvature of the tube at the level of the connecting element 8 and thus to avoid excessive stresses in the tube.

 According to the previous examples, the coil 5 is produced from a pin 15, the two branches of which are parallel. However, in accordance with the invention, it could be envisaged to produce the coil 5 from a pin, the two branches of which are not parallel.

Thus, FIG. 6 illustrates a pin 15 whose two branches 16, 17 are not parallel and converge, one towards the other, opposite the connecting core 18. The coil 5, obtained from of the pin as illustrated in Figure 6, then has two stages of winding spiral-shaped turns which are not located in parallel planes.

As shown in Figure 7, the first winding stage 6 is then located substantially in a plane perpendicular to the axis x-x 'of the coil while the second stage 7 has the shape of a helix of axis x- x '.

 In the examples above, the coil is made from a pin 15 having two branches. However, it is possible to produce a coil according to the invention from a pin having more than two parallel branches. Thus, FIG. 8 presents an example of a pin 15 produced from a single tubular element to present the shape of a boustrophedon and to comprise six parallel branches, connected to each other successively by rounded cores. So the winding of

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 the pin 15 according to FIG. 9 gives rise to a serpentine having six stages of spiral-shaped turns.

 According to the invention, the term spiral should be understood in the broad sense, that is to say as designating any winding on itself of successive turns capable of having various form factors. Thus, Figure 9 illustrates a coil according to the invention, the turns of which have a generally rectangular shape.

 Of course, other forms of winding could be envisaged compatible with the mechanical characteristics of the tube constituting the tubular element shaped for obtaining the coil according to the invention.

 Finally, in accordance with the invention, the coil 15 could not be produced from a pin but, on the contrary, from a tubular element whose two opposite branches are wound on themselves to constitute the two stages spiral winding as shown in figure 10.

 The invention is not limited to the examples described above because various modifications can be made thereto without departing from its scope.

Claims (17)

 CLAIMS 1. Tubular coil for heat exchanger, having a central axis x-x ', an inner face (1) and an outer face (E) and comprising: a first spiral-shaped turn (9), connected to a first branch (11) connecting the coil to an installation and located at least in part in a plane (P,) perpendicular to the axis x-x ', - a last spiral-shaped turn (10), connected to a second branch (12) connecting the coil to an installation, and located at least in part in a plane (P2) perpendicular to the axis x-x 'and distant from the plane (P,) of the first turn, and - at least one connecting element (8) between the first turn and the last turn. characterized in that the first turn (9) and the last turn (10) are connected to their respective connecting branch (11,12) at the same face (1 or E) of the coil.  2. Coil according to claim 1, characterized in that the first turn (9) and the last turn (10) are connected to their respective connecting branch (11,12) at the inner face (1) of the coil.  3. Coil according to claim 1, characterized in that the first turn (9) and the last turn (10) are connected to their respective connecting branch (11, 12) at the outer face (E) of the coil.  4. Coil according to one of claims 1 to 3, characterized in that it comprises at least two stages (6,7) of turns arranged in a spiral.  5. Coil according to one of claims 1 to 3, characterized in that it comprises at least two stages (6,7) of successive concentric turns of generally rectangular shape.  6. Coil according to claim 4 or 5, characterized in that two successive stages (6,7) of turns are connected by a connecting element <Desc / Clms Page number 10>  (8) U-shaped located at the inner (1) or outer (E) face of the coil.  7. A coil according to claim 4 or 5, characterized in that two successive stages are connected by a connecting element (8) in the form of a helix.  8. Coil according to one of claims 1 to 7, characterized in that it consists of the first turn to the last turn by a continuous tubular element.  9. Heat exchanger intended to allow heat exchangers between two fluids comprising a tank (2) which is connected, on the one hand, to an inlet pipe (3) of a first fluid and, on the other hand, to a outlet pipe (4) of this first fluid and in which is disposed a coil according to one of claims 1 to 8, the first branch (11) and the second branch (12) of which extend outside the tank and are intended to be connected to an inlet pipe and to an outlet pipe for the second fluid.  10. Exchanger according to claim 9, characterized in that the coil (5) is adapted in the tank (2) so that its turns are placed in the lower part.  11. A method of manufacturing a coil for a heat exchanger according to claim 8, characterized in that it consists in particular in: - producing, from a tubular element, at least one pin (15) substantially in a U having at at least two branches connected by a core (18), the free ends (19,20) of the pin (15) being intended to define the connecting branches (11,12) of the coil (5), - winding up the pin (15) on itself substantially in a spiral to form the coil on the axis x-x '.  12. The manufacturing method according to claim 11, characterized in that it consists in: shaping the free ends of the pin to define the connecting branches of the coil, - winding the pin on itself by placing the branches (11, 12) of connection inside the winding. <Desc / Clms Page number 11>  13. The manufacturing method according to claim 11, characterized in that it consists in winding the pin (15) on itself by placing the core (18) of the pin inside the pin.  14. The manufacturing method according to one of claims 11 to 13, characterized in that it consists in winding the pin (15) by continuously varying the radius of curvature of the winding.  15. The manufacturing method according to one of claims 11 to 14, characterized in that it consists in winding the pin, giving the successive turns a substantially rectangular shape.  16. The manufacturing method according to one of claims 11 to 15, characterized in that it consists in winding the pin so as to define at least two stages of substantially coplanar turns.  17. A method of manufacturing a coil for a heat exchanger according to claim 8, characterized in that it consists in: using a tubular element, - winding the tubular element on itself from a central region to define at least two stages of spiral winding which form the coil and which each have a free end intended to form a branch for connecting the coil.