Heat exchanger

Abstract

The present invention relates to a heat exchanger (1'), comprising: - a gas-tight casing (2), - at least one tube (4) made from a good thermally conducting material and inside which a fluid to be heated can circulate, this tube (4) being helically wound so as to form a helical winding (40) having a longitudinal axis (X-X') which is arranged inside said casing (2), - means for conveying and / or for producing hot gases inside said casing (2), such as a burner (3), so as to define a combustion chamber (26) therein, this helical winding (40) being arranged so as to form a gap (45) between two adjacent turns, said at least one tube (4) having a front face (41) and a rear face (42) which are opposing, a bottom side (43) oriented towards the longitudinal axis (X-X') and a top side (44) oriented towards the casing (2), said front face (41) and said rear face (42) of the tube (4) being planar or substantially planar and being located on either side of the gap (45). This heat exchanger is noteworthy in that said at least one tube (4) has, on the front face (41) thereof and / or the rear face (42) thereof, a shoulder (46) which extends from the bottom side (43) of the tube towards the top side (44) thereof, over part of the height (H1) of the straight section of this tube (4) and also over the whole, or virtually the whole, length of this tube (4).

Description

DOMAINE DE L'INVENTION

[0001] The invention relates to the field of heat exchangers, in particular those used to produce domestic hot water or water for a heating network.

[0002] The invention relates more particularly to a heat exchanger as defined in the preamble of claim 1, and as illustrated in document US 2015 / 153067A. ETAT DE LA TECHNIQUE

[0003] Such a heat exchanger is already known in the state of the art. In this type of exchanger, the helical winding of the tube is arranged so as to provide a small gap between its adjacent turns. The hot gases, produced or brought into the winding, pass through the gaps, from the inside to the outside and are then evacuated to the outside of the heat exchanger through a flue gas evacuation sleeve, provided for this purpose.

[0004] When the hot gases pass through these gaps, they heat the walls of the coils of the tube, located on either side of the gap, and in doing so, they also heat the fluid circulating in this tube.

[0005] However, it is observed, particularly in the case where the tube has an oblong cross-section with a front face and a rear face, which are flat or substantially flat, that the gap between two neighboring turns can become clogged and even blocked over time, because slag, that is to say soot or unburned particles carried by the hot gases, is deposited there.

[0006] This total or partial obstruction of certain gaps has the effect of creating an increase in the pressure of the gases circulating inside the combustion chamber, which requires increasing the speed of the fan bringing the air / fuel mixture into the burner or bringing hot air into the chamber and therefore increasing the electrical consumption of this fan.

[0007] This obstruction of certain interstices also has the effect of reducing the heat exchange surface between the fluid to be heated and the hot gases and therefore of generating a heating of the fluid circulating in the tube, which is not uniform over the entire length of the latter and of resulting in a reduction in the efficiency of the heat exchanger.

[0008] In addition, the exchanger's performance deteriorates over time as the interstices become clogged.

[0009] Finally, due to this obstruction, it is also necessary to regularly clean these gaps. This maintenance operation is costly in terms of time and labor.

[0010] We already know from document US 2015 / 0153067, a heating appliance equipped with a door with an integrated burner. This appliance comprises a tube inside which a fluid to be heated can circulate. This tube is wound in a helix so as to form a helical winding whose turns are spaced apart by a gap allowing the passage of hot gases produced by the burner. These gaps are calibrated using point bosses formed on one of the flat faces of the tube as can be seen in the figures of this document.

[0011] However, this document does not describe or suggest the provision of a soot and slag recovery shoulder, formed on the front and / or rear face of this tube over part of the height of the cross-section of this tube from the intrados side of the tube and over the entire length of the tube or almost the entire length of the tube.

[0012] Also known from document EP 3 141 838 is a heat exchanger comprising a tube wound in a helix and arranged inside an enclosure and around a burner. The gaps between the turns are calibrated by a comb provided with teeth, arranged on the extrados side of the tube.

[0013] This tube also has, on the intrados side, a plurality of wings intended to increase the contact surface and the heat transfer between the hot gases produced by the burner and the tube and therefore the fluid to be heated which circulates therein. These wings are formed at the intrados ends of the tube (on the short sides of the latter).

[0014] This document does not describe having a shoulder on the front and / or rear face of the tube, in order to collect soot and slag. EXPOSE DE L'INVENTION

[0015] An aim of the invention is therefore to propose a heat exchanger making it possible to solve the aforementioned problems and in particular to limit the fouling of the interstices between two neighboring turns of the tube of this exchanger.

[0016] For this purpose, the invention relates to a heat exchanger comprising: a gas-tight casing, provided with a sleeve for discharging burnt gases, at least one tube, made of a thermally good conductive material and inside which a fluid to be heated, such as water, can circulate, this tube being wound in a helix so as to form a helical winding with longitudinal axis X-X', this helical winding being arranged inside said casing, means for supplying and / or producing hot gases inside said casing, such as a gas or fuel oil burner, so as to define a combustion chamber therein, this helical winding being arranged so as to provide a gap between two adjacent turns, said at least one tube having an opposite front face and rear face, an intrados side oriented towards the longitudinal axis XX' and an opposite extrados side oriented towards the casing, said front face and said rear face of the tube being flat or substantially flat and located on either side of the gap.

[0017] According to the invention, said at least one tube has on its front face and / or its rear face, a shoulder, this shoulder extends from the intrados side of the tube towards its extrados side, over a part of the height of the cross section of this tube and this shoulder also extends either over the entire length of said at least one tube located in said combustion chamber, or over the entire length of said at least one tube located in said combustion chamber with the exception of the first or last turn of the helical winding, and each gap between two neighboring turns is calibrated either using a tooth of a comb introduced into the gap between two turns, on the extrados side of the tube, or using several projecting elements, such as bosses, formed on the front face and / or on the rear face of said at least one tube,each projecting element formed on a turn of the tube bearing respectively against the rear face and / or the front face of the adjacent turn, so that the shoulder makes it possible to recover the soot and slag entrained in the hot gases which pass through the interstices.,

[0018] This shoulder allows the soot or slag resulting from the combustion of gases by the burner to be recovered, while keeping the gap between two neighboring turns clear. The hot gases can thus continue to pass through this gap and heat the water circulating in the helical winding.

[0019] This shoulder therefore makes it possible to delay the speed of fouling of the coils, to limit the increase in pressure in the combustion chamber, to avoid generating excess electrical consumption of the exchanger, to maintain the efficiency of the exchanger and to delay and space out maintenance / cleaning operations carried out on the heat exchanger tube.

[0020] According to other advantageous and non-limiting characteristics of the invention, taken alone or in combination: the shoulder extends over a height, measured from the intrados, which measures up to approximately one third of the height of the cross-section of the tube. the gap between two neighboring turns, measured where the shoulder(s) is located is wider than the gap between two neighboring turns, measured where there is no shoulder. a discoidal deflector is mounted inside the helical winding in a gas-tight manner, this discoidal deflector provides inside the casing, a condensation chamber which extends between said discoidal deflector and the bottom of the casing and a combustion chamber which extends between said discoidal deflector and a front of the casing on which is mounted a door carrying said means for supplying and / or producing hot gases and the shoulder is formed exclusively on the tube or tubes or the portion of tube which is positioned in the combustion chamber.the gap between adjacent turns is calibrated using several projecting elements, such as bosses, formed on the front face and / or on the rear face of said at least one tube, each projecting element formed on a turn of the tube bearing respectively against the rear face and / or the front face of the adjacent turn and in that each projecting element is formed on the part of the front face and / or of the rear face which does not include the shoulder. the gap between adjacent turns is calibrated using several projecting elements, such as bosses, formed on the front face or on the rear face of said at least one tube, in that the projecting elements and the shoulder are formed on opposite faces of the tube and in that the projecting elements bear against the portion of the face of the tube which does not include the shoulder. said tube is hydroformed. . DESCRIPTION DES FIGURES

[0021] Other characteristics, aims and advantages of the invention will emerge from the following description, which is purely illustrative and non-limiting, and which must be read in conjunction with the appended drawings in which: there figure 1 represents a longitudinal sectional view of a heat exchanger according to the invention, in which there is only one combustion chamber; the figure 2 is a perspective view of a portion of a heat exchanger tube according to the invention; figure 3 is a longitudinal sectional view of a condensation heat exchanger according to the invention; figure 4 is a perspective view of a comb; the figure 5 is a detailed view of a cross-section of three turns of the tube according to the invention, the section being made at the level of the bosses; the figure 6 is a detailed view of a cross-section of three turns of the tube according to the invention, the section being made at a point of the tube free of bosses; the figure 7 is a detail view of a cross-section of three turns of the tube according to another embodiment of the invention. DESCRIPTION DETAILLEE DE L'INVENTION

[0022] A first embodiment of the invention will now be described with reference to the figure 1 , which represents a heat exchanger 1 comprising only a combustion chamber. In this figure, it is shown in its normal position of use.

[0023] This heat exchanger 1 comprises a casing 2, means for supplying and / or producing hot gases inside said casing and at least one tube 4, inside which circulates the fluid to be heated, in particular water. A pump not visible in the figures ensures this circulation of water.

[0024] The casing 2 has a generally tubular shape and extends along a longitudinal axis X-X'. In a 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 condensate discharge conduit 22.

[0025] The envelope 2 is closed at its rear end by a bottom 23, equipped on its internal face with a disc 230 made of thermally insulating material.

[0026] A facade 24 is fixed to the front of the envelope 2. It includes a central opening, capable of being closed by a door 25.

[0027] The tube 4 is made of a thermally good conductive material, such as metal. It is wound on itself in a helix, so as to form a helical winding 40 and it is arranged inside the casing 2 so that its longitudinal axis XX' coincides with the longitudinal axis X-X' of the casing 2.

[0028] The means for producing hot gases are preferably a burner 3, for example a gas or fuel oil burner. This burner 3 is preferably tubular in shape, and it is arranged inside the casing 2 and inside the winding 40, so that its longitudinal axis XX' coincides with the longitudinal axis X-X' of the casing 2.

[0029] Burner 3 is fixed on the internal face of door 25.

[0030] The hot gas supply means (not shown in the figures) comprise a burner arranged outside the exchanger and a fan fixed to the door 25 to introduce the hot gases inside the casing 2, into the helical winding 40.

[0031] The space which extends inside the winding 40 thus constitutes a combustion chamber 26.

[0032] The tube 4 has two ends forming an inlet mouth and an outlet mouth, from which the fluid to be heated is respectively introduced and extracted. One of these mouths 400 is visible on the figure 2 .

[0033] The tube 4 has an oblong cross-section, which may be oval or rectangular or rectangular with small sides which may be protruding and curved (as shown in the figures) or protruding and V-shaped.

[0034] The tube 4 thus has an opposite front face 41 and a rear face 42.

[0035] By convention, in the remainder of the description and the claims, the term “front face” designates the face facing the front of the exchanger, i.e. towards the facade 24, while the term “rear face” designates the face facing the rear of the exchanger, i.e. towards the bottom 23.

[0036] Furthermore, the tube 4 has an intrados side 43, oriented towards the axis XX' and towards the combustion chamber 26 (or towards the burner 3 when the latter is present) and an opposite extrados side 44, oriented towards the casing 2. These intrados 43 and extrados 44 sides correspond to the short sides of the tube 4.

[0037] Preferably and as shown in the figures, the front 41 and rear 42 faces are flat and parallel to each other. However, depending on the shape of the cross-section of the tube 4, these front 41 and rear 42 faces could not be strictly flat but substantially flat (for example slightly curved).

[0038] Preferably, and in order to simplify the assembly of the winding 40 between the front 24 and the bottom 23 or the disc 230, the winding of the tube 4 is carried out in such a way that the major axis YY' of the cross-section of the tube is perpendicular to the longitudinal axis XX' of the helical winding 40. However, this major axis YY' could also be slightly inclined relative to the longitudinal axis XX' of the helical winding 40 without departing from the scope of the invention.

[0039] The helical winding 40 has a series of neighboring turns and there is a gap 45 between two neighboring turns, the value of which is calibrated as will be detailed later. Within 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 seen in the figures 1 And 3 .

[0040] The hot gases exit the combustion chamber 26 by passing through the gaps 45, from the inside to the outside, as symbolized by the arrows i. In doing so, they heat the walls of the tube 4 and in particular the front faces 41 and 42 and therefore the water circulating in this tube. The gases are then evacuated to the outside through the sleeve 21, (see the arrows ii).

[0041] In accordance with the invention, and as best appears on the figures 2 , 5 And 6 , the tube 4 has on its front face 41 and / or its rear face 42, a shoulder 46. This shoulder 46 extends from the intrados side 43 towards the extrados side 44 over a part of the height H1 of the straight section of the tube 4.

[0042] On the figure 2 , we can see that this shoulder 46 extends over a height H2 (measured from the intrados 43) less than H1. In other words, and as we can see on the figures 5 And 6, the presence of the shoulder 46 means that the external width L2 of the cross-section of the tube 4 taken at the level of the shoulder 46 is less than the external width L1 of the cross-section of the tube 4 taken in the part of the tube where there is no shoulder 46.

[0043] Preferably, the height H2 measures up to about one-third of the height H1.

[0044] The shoulder 46 may extend over the entire length of the tube 4. Preferably, and as can be seen in the figure 2 , this shoulder 46 is continuous.

[0045] However, preferably, it may also not extend over the entire length of this length, (but over almost all of it) in particular not extend over the first and / or the last turn of the winding 40, in order to simplify the mounting of this winding in the casing 2. Thus, for example, on the figure 1 , we can see that the first turn of the winding applied against the front 24 does not have this shoulder 46. It could be the same on the last turn of the winding applied against the bottom 23 and the plate 230, in the case where the shoulder 46 is provided on the rear face 42.

[0046] It would also be possible to provide a shoulder 46 on the front face 41 and another shoulder 46 on the rear face 42 of the tube 4, as shown in the figure 7 In this case, the external width of the cross-section of the tube 4 taken at the level of the shoulders 46 is referenced L3, with L3 less than the width L1.

[0047] The shoulder 46 makes it possible to create a housing for recovering the soot and slag which are entrained in the hot gases which pass through the interstices 45. The gap (or the width) between two neighboring turns, measured at the level of this shoulder 46 is referenced E1 when there is a shoulder 46 only on the front face 41 (see figures 5 And 6 ) or only on the rear face 42 and is referenced E2 when it has a shoulder 46 on the front face 41 and a shoulder 46 on the rear face 42 (see figure 7 ).

[0048] This gap E1, E2 is therefore wider than the gap (or width) E3 between two neighboring turns, measured where there is no shoulder 46, which makes it possible both to trap the slag in the shoulder 46 and to keep space for the passage of hot gases. The winding 40 therefore becomes clogged less quickly, which makes it possible to reduce the frequency of cleaning operations.

[0049] The gaps 45 between two neighboring turns are advantageously calibrated so as to be all identical and thus so that the flows of hot gases circulating there are homogeneous and the heating of the fluid is regular over the entire length of the tube.

[0050] According to a first variant embodiment of the invention, the interstices 45 can be calibrated using one or more combs 5, such as that shown for example in the figure 4 .

[0051] This comb 5 has a plurality of teeth 50 parallel to each other. This comb 5 is arranged relative to the winding 40, so that each of its teeth 50 is introduced into a gap 45, on the extrados side 44 of the tube 4, in order to calibrate this gap 45. Each tooth 50 is thus in contact with the front face 41 of a turn of the tube 4 and the rear face 42 of the neighboring turn of the tube 4. Preferably, the teeth 50 do not extend to the level of the shoulder 46.

[0052] According to a second variant embodiment of the invention, the gaps 45 can be calibrated using projecting elements, such as bosses 47 (corrugations) formed on the front face 41 of the tube 4, (as shown in the figures 1 , 2 And 5 ) or on the rear face 42 (not visible in the figures). These bosses are preferably distributed uniformly over the entire length of the tube to obtain gaps 45 of a constant width.

[0053] Each projecting element formed on the front face 41 and / or on the rear face 42 of the tube 4 bears respectively against the rear face 42 and / or the front face 41 of the adjacent turn.

[0054] In the case where the bosses 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 shown in the figure 2 , then the bosses 47 are advantageously made on the portion referenced 49 of the face of the tube which does not include the shoulder 46, (see also figure 5 ).

[0055] In the case where the projecting elements (such as the bosses 47) and the shoulder 46 are produced on opposite faces of the tube 4 (for example the shoulder 46 on the front face 41 and the projecting elements on the rear face 42 or vice versa), then the projecting elements bear against the portion 49 of the face of the tube which does not include the shoulder 46.

[0056] A second embodiment of the heat exchanger according to the invention will now be described in connection with the figure 3 . On this one, we can see a condensation heat exchanger which bears the general reference 1'.

[0057] Elements identical to those described in connection with heat exchanger 1 bear the same numerical references and will not be described again in detail.

[0058] This exchanger 1' differs from the exchanger 1, in that it comprises a discoidal deflector 6, arranged inside the helical winding 40 of the tube 4, perpendicular to the axis X-X', so as to provide inside the casing 2, on the one hand the combustion chamber 26 which extends between the door 25 and this deflector 6 and where the hot gases are produced or brought, and on the other hand, a condensation chamber 27, which extends between the deflector 6 and the bottom 23 of the casing 2.

[0059] In this case, it will be noted that the gas discharge sleeve 21 is connected to the condensation chamber 27.

[0060] The deflector 6 comprises a disc 61 made of thermally insulating material, carried by a thin metal sheet frame 62, provided with a radial peripheral collar 63.

[0061] The deflector 6 is mounted inside the winding 40 of the tube 4, so that its collar 63 is inserted and positioned in a gas-tight manner, in 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.

[0062] Preferably, the shoulder 46 is formed only on the turns of the tube 4 which are located in the combustion chamber 26 and not on the turns of the tube which are located in the condensation chamber 27.

[0063] Indeed, as mentioned previously, the hot gases produced by the burner 3 leave the combustion chamber 26 by passing through the gaps 45 formed in the turns of the tube 4 which are located in this combustion chamber 26, (see arrows i) and the slag is trapped in the shoulder 46. Then, the hot gases abut against the casing 2 and are guided towards the extrados side 44 of the turns of the tube 4 located in the condensation chamber 27 (see arrows iii). These hot gases then pass through the gaps 45 formed between the turns, this time from the outside to the inside, towards the condensation chamber 27 (see arrows iv). These hot gases then no longer contain slag, so that the shoulder 46 is not necessary.

[0064] In the two embodiments just described, the heat exchanger 1 or 1' comprises a single tube 4 wound in a helix. In the case of the condensing heat exchanger 1', a portion of the turns of the single tube 4 extends into the combustion chamber 26 and the other portion of the turns into the condensation chamber 27.

[0065] However, it would also be possible to have several tubes 4, each wound in a helix and arranged side by side, so that their respective longitudinal axes XX' are coaxial. In this case, the different tubes 4 are connected to each other by collectors.

[0066] In the particular case of the condensing heat exchanger 1', it is possible to have one or more tubes 4 in the combustion chamber 26 and one or more tubes 4 in the condensation chamber 27.

[0067] The tube 4 can be manufactured by different processes. Two non-limiting examples of manufacturing processes are given below.

[0068] It can for example be obtained by extrusion of metal, for example by extrusion of aluminum.

[0069] Advantageously, it can also be obtained by hydroforming.

[0070] On this subject, we can refer, for example, to the applicant's patent FR 2700608.

[0071] Such a method has the advantage of being able to vary the profile of the section of the tube 4 along the entire length of the helical winding 40 and in particular of forming 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 on the turns which are located in the combustion chamber 26, in the case of the condensation heat exchanger 1'.

[0072] In addition, this process also makes it possible to have a tube whose faces of the first turn and the last turn are flat, which simplifies the design of the bottom and the front of the exchanger.

Claims

1. A heat exchanger (1, 1') comprising: - a gas-tight casing (2), provided with a sleeve (21) for discharging burnt gases, - at least one tube (4), made of a thermally good conductive material and inside which a fluid to be heated, such as water, can circulate, this tube (4) being helically wound so as to form a helical winding (40) with a longitudinal axis (X-X'), this helical winding (40) being disposed inside said casing (2), - means for supplying and / or producing hot gases inside said casing (2), such as a gas or oil burner (3), so as to define a combustion chamber (26) therein, this helical winding (40) being arranged so as to provide an interstice (45) between two adjacent turns, said at least one tube (4) having an front face (41) and a rear face (42) opposite to each other, an intrados side (43) oriented towards the longitudinal axis (X-X') and an opposite extrados side (44) oriented towards the casing (2), said front face (41) and said rear face (42) of the tube (4) being planar or substantially planar and being located on either side of the interstice (45), said at least one tube (4) having a shoulder (46) on its front face (41) and / or its rear face (42), this shoulder (46) extending from the intrados side (43) of the tube in the direction of its extrados side (44), over part of the height (H1) of the straight section of this tube (4), this heat exchanger being characterized in that this shoulder (46) also extends either over the entire length of said at least one tube (4) located in said combustion chamber (26), or over the entire length of said at least one tube (4) located in said combustion chamber (26) with the exception of the first or last turn of the helical winding (40), and in that each interstice (45) between two neighboring turns is calibrated either using a tooth (50) of a comb (5) introduced into the interstice (45) between two turns, on the extrados side (44) of the tube (4), or using several protruding elements, such as bosses (47), formed on the front face (41) and / or on the rear face (42) of said at least one tube (4), each protruding element formed on a turn of the tube (4) bearing respectively against the rear face (42) and / or the front face (41) of the adjacent turn, so that the shoulder (46) makes it possible to recover the soot and the slag entrained in the hot gases that pass through the interstices (45).

2. The heat exchanger (1, 1') according to claim 1, characterized in that the shoulder (46) extends over a height (H2), measured from the intrados (43), which measures up to approximately one third of the height (H1) of the straight section of the tube (4).

3. The heat exchanger (1') according to claim 1 or 2, characterized in that the gap (E1, E2) between two neighboring turns, measured where the shoulder(s) (46) are located, is wider than the gap (E3) between two neighboring turns, measured where there is no shoulder (46).

4. The heat exchanger (1, 1') according to any one of the preceding claims, characterized in that a discoid deflector (6) is mounted inside the helical winding (40) in a gas-tight manner, in that this discoid deflector (6) provides inside the casing (2), a condensation chamber (27) which extends between said discoid deflector (6) and the bottom of the casing (2) and a combustion chamber (26) which extends between said discoid deflector (6) and a facade (24) of the casing (2) on which a door (25) carrying said hot gas supply and / or production means is mounted and in that the shoulder (46) is formed exclusively on the tube(s) (4) or the tube portion (4) which is positioned in the combustion chamber (26).

5. The heat exchanger (1, 1') according to any one of the preceding claims, characterized in that the interstice (45) between the adjacent turns is calibrated using several protruding elements, such as bosses (47), formed on the front face (41) and / or on the rear face (42) of said at least one tube (4), each protruding element formed on a turn of the tube (4) bearing respectively against the rear face (42) and / or the front face (41) of the adjacent turn and in that each protruding element is formed on the part (49) of the front face and / or of the rear face which does not comprise the shoulder (46).

6. The heat exchanger (1, 1') according to any one of claims 1 to 4, characterized in that the interstice (45) between the adjacent turns is calibrated using several protruding elements, such as bosses (47), formed on the front face (41) or on the rear face (42) of said at least one tube (4), in that the protruding elements and the shoulder (46) are formed on opposite faces of the tube (4) and in that the protruding elements are bearing against the portion (49) of the face of the tube which does not comprise the shoulder (46).

7. The heat exchanger (1, 1') according to any one of the preceding claims, characterized in that said tube (4) is hydroformed.

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