Heat exchanger

Abstract

The present invention relates to a heat exchanger (1') comprising: - an airtight casing (2); - at least one tube (4) made of a thermally good conductive material and inside which a heated fluid can circulate; - means for conveying and / or generating hot gases inside the casing (2), such as a burner (3) so as to define a combustion chamber (26) therein, the helical winding (40) of which is arranged to provide a gap (45) between two adjacent turns, said at least one tube (4) having opposite front (41) and rear (42) faces, a bottom side (43) oriented towards a longitudinal axis (X-X') and a top side (44) oriented towards said casing (2), said front (41) and said rear (42) faces of the tube (4) being planar or substantially planar and located on either side of the gap (45). This exchanger is notable in that the at least one tube (4) has a shoulder (46) on its front face (41) and / or on its rear face (42), which shoulder (46) extends from the bottom side (43) of the tube towards its top side (44) over a portion of the height (H1) of the straight section of the tube (4) and also over the entire length or substantially the entire length of the tube (4).

Description

[Technical field]

[0001] The invention is in the field of heat exchangers, in particular those used to generate water for domestic hot water or heating networks.

[0002] The invention more particularly relates to a heat exchanger comprising a casing, means for supplying and / or generating hot gas within said casing to define a combustion chamber therein, and at least one spirally wound tube arranged in said combustion chamber and inside which a heated fluid, such as water, circulates. Summary of the Invention

[0003] technical level Such heat exchangers are already known in the state of the art. In this type of exchanger, the helical winding of the tube is arranged with a small gap between adjacent turns. The hot gases generated or brought into the winding pass through the gap from the inside to the outside and are then discharged to the outside of the heat exchanger by a sleeve for discharging the burnt gases provided for this purpose.

[0004] As the hot gas passes through these gaps it heats the walls of the tube turns located on either side of the gap and in so doing it also heats the fluid circulating in this tube.

[0005] However, it is observed that the gap between two adjacent turns can become clogged and even blocked over time, especially when the tube has an oblong cross section with flat or substantially flat front and rear faces, because slag, i.e. soot or unburned particles carried by the hot gases, accumulates there.

[0006] This total or partial blockage of some gaps has the effect of causing an increase in the pressure of the gases circulating in the combustion chamber, which requires an increase in the speed of the fan blowing the air / fuel mixture to the burner or the fan blowing the hot air into the combustion chamber, and therefore an increase in the electrical consumption of this fan.

[0007] This blocking of some gaps has the effect of reducing the heat exchange surface between the heated fluid and the hot gas and therefore causing a heating of the fluid circulating in the tubes which is not homogeneous over the entire length of the latter, leading to a reduction in the efficiency of the heat exchanger.

[0008] Furthermore, the efficiency of the exchanger deteriorates over time as the gaps become clogged.

[0009] Finally, due to the blockages, it is also necessary to clean these gaps periodically, a maintenance task that is labor-intensive and time-consuming.

[0010] A heating device with a door having an integrated burner is already known from the document US2015 / 0153067. The device comprises a tube, inside which the fluid to be heated can circulate. The tube is wound helically to form a helical winding, the turns of which are spaced apart from one another by gaps that allow the passage of hot gases produced by the burner. These gaps are calibrated using embossed points made in one of the planes of the tube, as can be seen in the figures of this document.

[0011] However, this document does not describe or suggest providing a soot and slag collection shoulder on the front and / or rear face of the tube extending from the intrados side of the tube over a portion of the height of the straight section of the tube and over the entire length of the tube or nearly the entire length of the tube.

[0012] A heat exchanger with spirally wound tubes, arranged inside a housing and around a burner, is also known from EP 3 141 838. The gaps between the turns are calibrated by a comb provided with teeth, arranged on the outer ring side of the tube.

[0013] This tube also has, on its inner ring side, a number of wings intended to increase the contact surface and heat transfer between the tube, and therefore the heated fluid circulating therein, and the hot gases produced by the burner. These wings are formed at the inner ring end of the tube (on its short side).

[0014] This document does not mention having shoulders on the front and / or rear of the tubes to collect soot and slag. Disclosure of the Invention One object of the invention is therefore to propose a heat exchanger making it possible to solve the aforementioned problems, and in particular to suppress clogging of the gap between two adjacent turns of the tubes of this exchanger.

[0015] To this end, the invention comprises: - an airtight casing in which a sleeve for discharging burnt gases is provided; - at least one tube made of a thermally good conducting material, inside which a heated fluid, such as water, can circulate, said tube being spirally wound so as to form a helical winding having a longitudinal axis X-X', said helical winding being arranged inside said casing; - means for supplying and / or generating hot gas inside said casing, such as a gas or oil burner, so as to define a combustion chamber therein; The spiral windings are arranged with a gap between two adjacent turns, the at least one tube has opposite front and rear faces, an inner ring side oriented toward the longitudinal axis X-X′, and an opposite outer ring side oriented toward the casing, the front and rear faces of the tube being planar or substantially planar and located on either side of the gap; Regarding heat exchangers.

[0016] According to the invention, the at least one tube has a shoulder on its front and / or rear face, which shoulder extends over a part of the height of the straight section of the tube in the direction from the inner ring side of the tube to its outer ring side, and which also extends over the entire length of the at least one tube located in the combustion chamber or over the entire length of the at least one tube located in the combustion chamber except for the first or last turn of the helical winding, and each gap between two adjacent turns is calibrated on the outer ring side of the tube using teeth of a comb introduced into the gap between the two turns or using a number of protruding elements, such as bosses, formed on the front and / or rear face of the at least one tube, each protruding element formed on a turn of the tube leans against the rear and / or front face of the adjacent turn, respectively, whereby the shoulder makes it possible to collect soot and slag entrained in the hot gas passing through the gap.

[0017] This shoulder allows the gap between two adjacent turns to remain open, allowing the soot and slag resulting from the combustion of gases by the burner to be collected, while allowing hot gases to continue passing through the gap and heat the water circulating in the helical winding.

[0018] This shoulder therefore slows down the clogging of the turns, limits the pressure rise in the combustion chamber, prevents electrical overconsumption of the exchanger, maintains its efficiency and allows for delayed spacing of maintenance / cleaning interventions carried out on the heat exchanger tubes.

[0019] According to other advantageous, non-limiting features of the invention taken alone or in combination: - The shoulder extends over a height up to approximately one-third of the height of the straight section of the tube, measured from the inner ring. - the gap between two adjacent turns measured where one or more shoulders are located is wider than the gap between two adjacent turns measured where there are no shoulders. - a disk-shaped deflector is mounted gas-tightly inside the helical winding, which provides inside the casing a condensation chamber extending between said disk-shaped deflector and the bottom of the casing and a combustion chamber extending between said disk-shaped deflector and a front part of the casing on which a door carrying said hot gas supply means and / or generation means is mounted, the shoulder being formed only on the tube or tube parts which are located in the combustion chamber. - the gap between adjacent turns is calibrated using a number of protruding elements, such as bosses, formed on the front and / or rear face of said at least one tube, each protruding element being formed on a turn of the tube that rests respectively against the rear and / or front face of an adjacent turn, each protruding element being formed on a part of the front and / or rear face that does not have a shoulder. - the gaps between adjacent turns are calibrated using a number of protruding elements, such as bosses, formed on the front or rear surface of said at least one tube, the protruding elements and a shoulder formed on the opposite surface of the tube, the protruding elements resting against a portion of the surface of the tube that does not have a shoulder. The tube is hydroformed. [Brief description of the drawings]

[0020] Other characteristics, objects and advantages of the invention will become apparent from the following description, which is purely illustrative and not limiting, and which should be read in conjunction with the accompanying drawings, in which: [Figure 1]FIG. 1 shows a longitudinal section through a heat exchanger according to the invention, in which there is only one combustion chamber. [Diagram 2] FIG. 2 is a perspective view of a portion of a heat exchanger tube according to the invention. [Diagram 3] FIG. 3 is a longitudinal sectional view of a condensing heat exchanger according to the invention. [Figure 4] FIG. 4 is a perspective view of the comb-shaped portion. [Diagram 5] FIG. 5 is a detailed view of a cross section of three turns of a tube according to the invention, the cross section being made at the level of the boss. [Figure 6] FIG. 6 is a detailed view of a cross section of a three-turn tube according to the invention, the cross section being made at a portion of the tube without a boss. [Figure 7] FIG. 7 is a detailed cross-sectional view of three turns of a tube according to another embodiment of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Detailed Description of the Invention A first embodiment of the invention will now be described with reference to figure 1, which represents a heat exchanger 1 equipped only with a combustion chamber. In this figure, the heat exchanger is represented in its normal use position.

[0022] This heat exchanger 1 comprises a casing 2, means for supplying and / or generating hot gas inside said casing, and at least one tube 4 inside which a fluid to be heated, in particular water, circulates. A pump, not visible in the figures, ensures this water circulation.

[0023] The casing 2 has a generally tubular shape and extends along a longitudinal axis X-X'. In known manner, it has, at its upper part, a sleeve 21 for discharging the burnt gases and, at its lower part, an outlet orifice connected to a duct 22 for discharging the condensate.

[0024] The casing 2 is closed at its rear end by a bottom 23, on the inner circumferential surface of which is fitted a disk 230 made of a thermally insulating material.

[0025] A front part 24 is fixed to the front of the casing 2. It is provided with a central opening which can be closed by a door 25.

[0026] The tube 4 is made of a material with good thermal conductivity, such as metal. It is wound spirally on itself to form a helical winding 40, which is placed inside the casing 2 so that its longitudinal axis X-X' coincides with the longitudinal axis X-X' of the casing 2.

[0027] The hot gas generating means is preferably a burner 3, for example a gas or oil burner. This burner 3 is preferably of tubular shape and it is arranged inside the casing 2 and inside the windings 40, so that its longitudinal axis X-X' coincides with the longitudinal axis X-X' of the casing 2.

[0028] Burner 3 is fixed to the inside surface of door 25 .

[0029] The hot gas supply means (not shown in the figure) comprises a burner arranged outside the exchanger and a fan fixed to the door 25 and introduces hot gas inside the casing 2 in a helical winding 40.

[0030] Thus, the space extending inside the windings 40 constitutes the combustion chamber 26.

[0031] The tube 4 has two ends forming an inlet and an outlet port through which the heated fluid is introduced and removed, respectively. One of these ports 400 is visible in FIG.

[0032] The tube 4 has an oblong straight section which may be oval, or rectangular, or rectangular with short sides which may be convex and curved (as shown in the figure) or may be convex and V-shaped.

[0033] Thus, the tube 4 has opposite front and rear faces 41 and 42 .

[0034] By convention, in the remainder of this specification and in the claims, the term "front face" means the face directed towards the front of the exchanger, i.e., towards the front part 24, and the term "rear face" means the face directed towards the rear of the exchanger, i.e., towards the bottom part 23.

[0035] Furthermore, the tube 4 has an inner ring side 43 oriented towards the axis X-X' and towards the combustion chamber 26 (towards the burner 3, if the latter is present), and an opposite outer ring side 44 oriented towards the casing 2. These inner ring side 43 and outer ring side 44 correspond to the short sides of the tube 4.

[0036] Preferably, as shown in the figures, the front surface 41 and the rear surface 42 are planar and parallel to each other, but depending on the shape of the straight section of the tube 4, these front surface 41 and rear surface 42 may not be strictly planar, but may be substantially planar (e.g. slightly curved).

[0037] Preferably, and to simplify the assembly of the winding 40 between the front part 24 and the bottom part 23 or the disk 230, the winding of the tube 4 is performed so that the major axis Y-Y' of the straight section of the tube is perpendicular to the longitudinal axis X-X' of the helical winding 40. However, this major axis Y-Y' can also be slightly inclined with respect to the longitudinal axis X-X' of the helical winding 40 without departing from the scope of the invention.

[0038] The helical winding 40 has a series of adjacent turns with a gap 45 between two adjacent turns, the value of which is calibrated as will be described in more detail below. In this winding 40, the front face 41 and the rear face 42 of the tube 4 are located on either side of the gap 45, as can be seen in Figures 1 and 3.

[0039] The hot gas leaves the combustion chamber 26 by passing through the gap 45, from inside to outside, as symbolized by the arrow i. In doing so, it heats the walls of the tube 4, in particular the front faces 41 and 42, and thus the water circulating in this tube. The gas is then discharged to the outside through the sleeve 21 (see arrow ii).

[0040] According to the invention, as can be better seen in Figures 2, 5 and 6, the tube 4 has at its front face 41 and / or its rear face 42 a shoulder 46. This shoulder 46 extends in the direction from the inner ring side 43 to the outer ring side 44 over a portion of the height H1 of the straight section of the tube 4.

[0041] In Figure 2 it can be seen that this shoulder 46 extends over a height H2 (measured from the inner ring side 43) which is less than H1. In other words, as can be seen in Figures 5 and 6, the presence of the shoulder 46 means that the outer width L2 of a cross-section of the tube 4 taken at the level of the shoulder 46 is less than the outer width L1 of a cross-section of the tube 4 taken at a portion of the tube without the shoulder 46.

[0042] Preferably, height H2 is up to about one third of height H1.

[0043] The shoulder 46 may extend the entire length of the tube 4. Preferably, this shoulder 46 is uninterrupted, as can be seen in FIG.

[0044] However, preferably, it does not extend over this entire length (but almost over the entire length), in order to simplify the mounting of this winding in the casing 2, and in particular not over the first and / or last turn of the winding 40. Thus, for example, in Figure 1 it can be seen that the first turn of the winding applied to the front part 24 does not have this shoulder 46. The same could be true for the last turn of the winding applied to the bottom part 23 and to the plate 230, if the shoulder 46 is provided on the rear face 42.

[0045] It is also conceivable to provide a shoulder 46 on the front face 41 of the tube 4 and another shoulder 46 on the rear face 42, as shown in Figure 7. In this case, the external width of the cross section of the tube 4 taken at the level of the shoulder 46 is referenced L3, L3 being smaller than the width L1.

[0046] The shoulder 46 makes it possible to create a housing for collecting soot and slag entrained in the hot gases passing through the gap 45. The gap (or width) between two adjacent turns, measured at the level of this shoulder 46, is referenced E1 if there is a shoulder 46 only at the front face 41 (see Figures 5 and 6) or only at the rear face 42, and E2 if there is a shoulder 46 at the front face 41 and a shoulder 46 at the rear face 42 (see Figure 7).

[0047] This gap E1, E2 is therefore wider than the gap (or width) E3 between two adjacent turns, measured in the absence of the shoulder 46, which makes it possible to trap the slag in the shoulder 46 and leave space for the passage of hot gases, so that the clogging of the winding 40 is slower, which makes it possible to reduce the frequency of cleaning operations.

[0048] The gaps 45 between two adjacent turns are advantageously calibrated to be all identical and therefore so that the hot gas flow circulating therein is homogeneous and the heating of the fluid is uniform over the entire length of the tube.

[0049] According to a first alternative embodiment of the invention, the gap 45 can be calibrated using one or more combs 5, such as the one depicted in FIG.

[0050] The comb 5 has a number of parallel teeth 50. To calibrate the gap 45, the comb 5 is placed relative to the winding 40 so that each of its teeth 50 is introduced into the gap 45 at the outer ring side 44 of the tube 4. Each tooth 50 thus contacts the front face 41 of a turn of the tube 4 and the rear face 42 of the adjacent turn of the tube 4. Preferably, the teeth 50 do not extend to the height of the shoulder 46.

[0051] According to a second alternative embodiment of the invention, the gap 45 can be calibrated using protruding elements such as bosses 47 (corrugations) formed on the front face 41 of the tube 4 (as represented in Figures 1, 2 and 5) or on the rear face 42 (not visible in the figures). These bosses are preferably uniformly distributed over the entire length of the tube so as to obtain a gap 45 of constant width.

[0052] Each projecting element formed on the front face 41 and / or on the rear face 42 of the tube 4 rests against the rear face 42 and / or the front face 41, respectively, of the adjacent turn.

[0053] If the boss 47 and the shoulder 46 are made on the same front or rear face of the tube 4, for example on the front face 41 as represented in FIG. 2, the boss 47 is advantageously made on the part of the face of the tube not comprising the shoulder 46, referenced 49 (see also FIG. 5).

[0054] If a protruding element (such as a boss 47) and a shoulder 46 are made on opposite faces of the tube 4 (e.g., the shoulder 46 on the front face 41 and the protruding element on the rear face 42 or vice versa), the protruding element rests against a portion 49 of the face of the tube that does not include the shoulder 46.

[0055] A second embodiment of a heat exchanger according to the invention will now be described with reference to figure 3. In the latter there can be seen a condensing heat exchanger with the general reference 1'.

[0056] The same elements as those described with respect to heat exchanger 1 are given the same reference numbers and will not be described in detail again.

[0057] This exchanger 1' differs from the exchanger 1 in that it comprises a disk-shaped deflector 6 arranged inside the helical winding 40 of the tube 4 and perpendicular to the axis X-X', so as to provide, inside the casing 2, a combustion chamber 26 extending, on the one hand, between the door 25 and this deflector 6 and in which the hot gases are generated or introduced, and, on the other hand, a condensation chamber 27 extending between the deflector 6 and the bottom 23 of the casing 2.

[0058] It is noted that in this case the gas exhaust sleeve 21 is connected to the condensation chamber 27 .

[0059] The deflector 6 comprises a disk 61 made of thermally insulating material carried by a thin sheet metal frame 62 provided with a radial peripheral flange 63 .

[0060] The deflector 6 is attached to the inside of the windings 40 of the tube 4 so that its flange 63 is positioned airtightly inserted into the gap 45 existing between the last turn of the tube 4 located in the combustion chamber 26 and the first turn of the tube 4 located in the condensation chamber 27.

[0061] Preferably, the shoulder 46 is formed only in the turns of the tube 4 located in the combustion chamber 26 and not in the turns of the tube located in the condensation chamber 27 .

[0062] In fact, as previously mentioned, the hot gases produced by the burner 3 leave the combustion chamber 26 through the gaps 45 in the turns of the tubes 4 located in this combustion chamber 26 (see arrow i), and the slag is trapped in the shoulder 46. The hot gases then impinge on the casing 2 and are directed towards the outer ring side 44 of the turns of the tubes 4 located in the condensation chamber 27 (see arrow iii). These hot gases then pass through the gaps 45 formed between the turns, this time from outside to inside, in the direction of the condensation chamber 27 (see arrow iv). As these hot gases no longer contain slag, the shoulder 46 is no longer necessary.

[0063] In the two embodiments just described, the heat exchanger 1 or 1' comprises one spirally wound tube 4. In the case of the condensation heat exchanger 1', some of the turns of the single tube 4 extend into the combustion chamber 26 and other parts of the turns extend into the condensation chamber 27.

[0064] However, it would also be possible to have several tubes 4, each spirally wound and arranged side by side, such that their respective longitudinal axes X-X' are coaxial. In this case, the different tubes 4 are connected to each other by a manifold.

[0065] In the specific case of a condensation heat exchanger 1 ′, it is also possible to have one or more tubes 4 in the combustion chamber 26 and one or more tubes 4 in the condensation chamber 27 .

[0066] The tube 4 can be manufactured in a variety of ways, two non-limiting examples of which are given below.

[0067] It can be obtained, for example, by metal extrusion, for example aluminium extrusion.

[0068] Advantageously, it can also be obtained by hydroforming.

[0069] On this topic reference may be made, for example, to the applicant's patent FR2700608.

[0070] Such a method has the advantage that it is possible to vary the cross-sectional profile of the tube 4 over the entire helical winding 40 and in particular to form the shoulder 46 only over a certain part of the length of the tube 4. In particular, this method makes it possible to create the shoulder 46 only in the turn located in the combustion chamber 26 in the case of the condensing heat exchanger 1'.

[0071] In addition, this method also makes it possible to have tubes where the faces of the first and last turns are flat, which allows for a simplified design of the bottom and front parts of the exchanger.

Claims

1. A heat exchanger (1, 1'), comprising: - An airtight casing (2) provided with a sleeve (21) for discharging the burned gas; - At least one tube (4) made of a material with good thermal conductivity and through which a heated fluid such as water can circulate inside, the tube (4) being wound helically so as to form a helical winding (40) having a longitudinal axis (X-X'), and the helical winding (40) being arranged inside the casing (2); - Means for supplying and / or generating high-temperature gas inside the casing (2), such as a gas burner or an oil burner (3), so as to define a combustion chamber (26) therein; The helical winding (40) is arranged so as to provide a gap (45) between two adjacent turns; The at least one tube (4) has opposite front (41) and rear (42) faces, an inner side (43) oriented towards the longitudinal axis (X-X'), and an opposite outer side (44) oriented towards the casing (2). The front (41) and rear (42) faces of the tube (4) are planar or substantially planar and are located on both sides of the gap (45); This exchanger further comprises: The at least one tube (4) having a shoulder (46) on its front face (41) and / or on its rear face (42); The shoulder (46) extends from the inner side (43) to the outer side (44) of the tube over a part of the height (H1) of the straight section of the tube (4), and the shoulder (46) also extends over the entire length of the at least one tube (4) located in the combustion chamber (26), or over the entire length of the at least one tube located in the combustion chamber (26) except for the first or last turn of the helical winding (40). and each gap (45) between two adjacent turns is calibrated at the outer ring side (44) of the tube (4) using the teeth (50) of the comb-shaped part (5) introduced into the gap between two turns, or using a plurality of protruding elements such as bosses formed on the front surface (41) and / or the rear surface (42) of the at least one tube (4), and each protruding element formed on the turn of the tube (4) hangs against the rear surface (42) and / or the front surface (41) of the adjacent turn, thereby enabling the shoulder (46) to collect soot and slag entrained by the high-temperature gas passing through the gap (45). Heat exchanger (1, 1'). **Claim 2** The heat exchanger (1, 1') according to claim 1, characterized in that the shoulder (46) extends over a height (H2) up to about one-third of the height (H1) of the straight section of the tube (4) measured from the inner ring side (43). **Claim 3** The heat exchanger (1') according to claim 1 or 2, characterized in that the gap (E1, E2) between two adjacent turns measured at the location where the one or more shoulders (46) are located is wider than the gap (E3) between two adjacent turns measured at a location where there is no shoulder (46). **Claim 4** A disc-shaped deflector (6) is airtightly attached inside the spiral winding (40), and this disc-shaped deflector (6) has a condensation chamber (27) extending between the disc-shaped deflector (6) and the bottom of the casing (2) inside the casing (2), and a combustion chamber (26) extending between the disc-shaped deflector (6) and the front part (24) of the casing (2) where the door (25) having the high-temperature gas supply means and / or the high-temperature gas generation means is attached. The heat exchanger (1, 1') according to claim 1 or 2, characterized in that the shoulder (46) is formed only on one or more tubes (4) or tube portions (4) positioned in the combustion chamber (26). **Claim 5** The gap (45) between adjacent turns is calibrated using a plurality of protruding elements such as bosses formed on the front face (41) and / or the rear face (42) of the at least one tube (4), each protruding element being formed on a turn of the tube (4) that leans against the rear face (42) and / or the front face (41) of adjacent turns respectively, each protruding element being formed on a portion (49) of the front face and / or the rear face that does not include the shoulder (46), the heat exchanger (1, 1') according to claim 1 or 2, characterized in that.

6. The gap (45) between adjacent turns is calibrated using a plurality of protruding elements such as bosses (47) formed on the front face (41) or the rear face (42) of the at least one tube (4), the protruding elements and the shoulder (46) being formed on opposite faces of the tube (4), the protruding elements leaning against a portion (49) of the face of the tube that does not include the shoulder (46), the heat exchanger (1, 1') according to claim 1 or 2, characterized in that.

7. The tube (4) is hydroformed, the heat exchanger (1, 1') according to claim 1 or 2, characterized in that.

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