FR2741426A1 - COMBINED COILING HEATER WITH COMPLEX STRAIGHT SECTION - Google Patents

Abstract

The combination heater consists of a hot water circuit and a central heating circuit. The circuit consists of pipes made from outer (2) and inner (3) elements, connected at their ends to manifolds. The inner elements, which have a complex cross-section, create a series of contact surfaces (6) between the two elements of the pipe which form thermal bridges. The central heating water circulates through the spaces between the outer and inner elements. The outer elements of the pipes are round or oval in section. The inner elements have a complex cross-section, e.g. cross-shaped, X-shaped or Y-shaped, and provide a heat exchange surface which is sufficient to disperse the whole of the thermal power produced by the burner. The outer elements are made from sheet metal with brazed or welded seams, and the inner ones from shaped tubing.

Description

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  The present invention relates to improvements made to boiler heating bodies, in particular gas central heating. These boilers for domestic or industrial use must provide the user with both domestic hot water, the temperature of which must not exceed 65 ° C, and hot heating water which is circulated in a closed circuit within the network. central heating of the house. These heating bodies are commonly called mixed heating bodies because they have two separate water circuits, one for domestic water, the other for heating water, which are made integral so that 'there is an intimate thermal contact between them. Generally, these are tubular circuits arranged one inside the other, and comprising either means for making the thermal bridges between the two circuits, or separate tubular circuits but flattened and joined one against each other. These heating bodies also have a bundle of fins responsible for transmitting to the tubular circuits, the heat flux conveyed by the fumes resulting from combustion within a

  burner placed in the lower part of the heating body.

  A main constraint which acts on this type of exchanger lies mainly in the fact that the various water circuits circulate alternately. Each of the circulating circuits must be able to evacuate all the calories present in the fumes, without the other stagnant circuit not

  rises excessively in temperature or pressure.

  At present, normative regulations impose temperature thresholds not to be exceeded, mainly on the domestic water heating circuit, this barrier being very difficult to observe with the type of mixed heating body

known from the prior art.

  In order to meet these standards, however, the designers of the mixed heating body solve this problem by incorporating clipping devices in the installation, which considerably complicate the structure of the exchanger. Another way to solve this problem is to impose closed loop recirculations within the heating circuit on the heating water circuit.

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  boiler when drawing sanitary water. This solution requires that there is a three-way valve and a connecting pipe on the heating circuit, which increases the cost.

manufacturing and maintenance.

  The present invention therefore aims to overcome these drawbacks by proposing a heating body which has both a domestic water heating circuit and a central heating water circuit, these circuits being nested one in the other but with an optimization in terms of

  flows and heat exchanges within the exchanger.

  According to another characteristic of the invention, it relates to a process for the preparation of this type of mixed heating body. To this end, the mixed heating body, comprising a sanitary heating circuit and a central heating circuit, the latter being arranged one inside the other, characterized in that it comprises a plurality of first elements for the central heating circuit, connected by their ends to manifolds and within which winds a plurality of second elements with complex cross-section, intended for the domestic heating circuit, these second elements also opening into said manifolds, the mounting of the second element in the first element further delimiting a plurality of generators of contact between said second elements and said first elements in order to achieve

  at the level of these generators thermal bridges.

  Other features and advantages of this

  invention will emerge from the description given below, in

  reference to the accompanying drawings which illustrate an embodiment thereof devoid of any limiting character. In the figures: - Figure 1 is a perspective and cutaway view, illustrating the mounting in a wall-mounted boiler of a mixed heating body according to the invention; - Figure 2 is a perspective view of a mixed heating body according to the invention; - Figure 3 is a sectional view, in side elevation, of a mixed heating body according to the invention;

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  FIG. 4 is a sectional view, in front elevation,

in Figure 3.

  According to a preferred embodiment of the mixed heating body 1, object of the invention, it comprises a plurality of first elements 2 produced in the form of a tube of circular or oval cross section, within which are incorporated a plurality of second elements 3 being in the form of a tube of complex cross section, such as in particular in cross, in X, in Y. The first element 2 constitutes the heating circuit, the heating water circulates in the sections delimited between the outer walls 4 of the tube of complex cross section and

  the inner wall 5 of the first element 2.

  The second element 3 constitutes the sanitary heating circuit, the sanitary water flows inside the section

complex right.

  According to an advantageous characteristic, the mounting of the second element 3 in the first element 2 delimits a plurality of contact generators 6 between the tube of complex cross section 3 and the external tube 2; these contact generators 6 are made integral at the level of the first 2 and second elements 3 by means of known means such as in particular by a brazing or welding operation, in order to

  make thermal bridges at these generators.

  Thanks to this assembly between these two elements 2, 3, during sanitary operation, the heat flow goes largely directly by conduction between sanitary water and the material in contact with the fumes, without using unduly

  the heating water circuit as the heat transfer fluid.

  According to another advantageous characteristic of the invention, the complex profile of the second element 3 guarantees that it has a sufficient exchange surface to allow all of the thermal power delivered by the

  burner 7, positioned in its lower part.

  On the other hand, the particular arrangement between the first 2 and second 3 elements ensures that, during operation in central heating, the wall temperature of the peripheral channels 8 - these being delimited by the first element

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  and the connection zones of the second element - reaches a homogeneous temperature at their wet section very close to that of the first element, which makes it possible to reach, thanks to the high exchange coefficient and the large developed surface, level of efficiency on the heating side required by standards. The industrialization and manufacturing constraints of a central heating boiler equipped with a mixed heating body i according to the invention require that the circulator or the accelerator mounted on the heating circuit be dimensioned as accurately as possible. The power of the latter is calculated so as to compensate for the hydraulic head losses of the entire circuit. With regard to the pressure drops, these are noted at the level of the piping and the radiators constituting the central heating installation, but also at the level of the boiler and very particularly at the level of the heating body, mainly on the pipes forming the

first 2 and second 3 elements.

  These first 2 and second 3 elements, the hydraulic diameter of which is optimized so as to reduce the size of the heating body 1, generate the major part of the hydraulic head losses and, in order to minimize the installed power of the circulator, the first elements 2 of the central heating circuit are connected to feeders 9, 10 arranged

on either side of the exchanger.

  The circulation of the central heating water takes place in parallel within these tanks, so as to guarantee a

  identical flow in each channel 8.

  On the other hand, the circulation of sanitary water is carried out in series and successively within the plurality of second

elements 3.

  According to a process for developing a heating body 1 according to the invention, it comprises a succession of simple steps, broken down into:

  - A first step which consists in carrying out two half

  shells 11, 12. Each half-shell 11, 12 essentially comprises a plurality of first elements 2 extending in the form of semi-cylindrical or semi-oval tubes,

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  preferably five to eight in number, arranged in parallel and connected at each of their ends to a manifold 9, 10. These various elements are made as appropriate, of copper

or stainless steel.

  According to a first method of obtaining, these half-shells 11, 12 are produced directly by stamping a metal sheet, it being understood that there are two different dies respectively depending on the obtaining of a half-shell

  upper and a lower half-shell.

  According to a second embodiment, the various elements (the first semi-cylindrical or semi-oval elements 2, the side half-nurses 9, 10) are produced separately, in particular by stamping, and are made integral by a second operation consisting of example in a welding phase

or soldering.

  The lower and upper half-shells 11, 12 differ from each other mainly in that one of them has on the external wall of the side housings 9, 10, orifices 13 allowing connection to the various circuits of heating

sanitary and central heating.

  - A second step consisting in the manufacture of the second elements 3 intended for the circulation of the water of the circuit

sanitary heating.

  These second elements 3, the cross section of which is complex, in particular of cruciform profile, are obtained from cylindrical tubes delivered in a crown, by a cycle of either cross profiling then bending of the latter so as to conform a succession of pins forming a serpentine, either bending

  of cylindrical tube followed by a hydroforming step.

  These processes for developing the second elements 3 make it possible to obtain a constant thickness all along the coil, which guarantees the absence of weak points at the level of corrosion. It can also be noted that the use of a one-piece coil eliminates any brazed connection between the domestic water heating circuit and the water heating circuit

central heating.

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  - A third step consists in having, within half

  shells 11, 12 consisting essentially of first elements 2 connected at their ends to nurses 9, 10, the

second element coil 3.

  Advantageously, the coil is arranged in the lower half-shell 12 because the latter has the orifices

  13 for connection to the various circuits.

  - A fourth step consists in interposing between the joint planes 14 delimited by the lower and upper half-shells 11, 12, brazing rods 15 and placing above the cylindrical or oval tubes of the first elements 1, a plurality of 'fins 16, and to bring the folded edges of the fins initially perpendicular above the tubes so as to conform a mixed heating body 1 which can be manipulated,

mechanically united.

  - A fifth step consists in positioning at the base of the fins 16 and in contact with the first elements 2 forming the heating body, brazing rods and placing the assembly in a brazing furnace operating advantageously

  under neutral or reducing atmosphere.

  At the outlet of this furnace, the exchangers are ready to supply the assembly line of the boilers without recourse to subsequent steps for the assembly of fittings, various elbows, manifolds ... According to another method of assembling the heating body object of the invention, the so-called "strong" soldering step is replaced by a so-called "soft" soldering step, essentially consisting of a tinning phase by dipping. The entire heating body 1 is soaked in a tin bath so as to have, on the one hand a tin film which protects the exchanger against corrosion and on the other hand, keeping the building material from the 'together, like copper, its hardened nature, to prevent the fins 16 from deforming easily during handling. According to another method of obtaining the fins, these instead of being in the form of separate fins, are presented under

the shape of an accordion.

  The heating body as described above allows perfect heat exchange between the fluids contained in the two circuits, via a large exchange surface between the conduits, obtained by virtue of their relative arrangement. Furthermore, the absence of added bends on each of the circuits, the changes in direction being obtained by bending the tubes of the different circuits, simplifies the method of manufacturing the exchanger, no more soldering or soldering, which

avoids the risk of leaks.

  Of course, the present invention is not

  limited to the exemplary embodiments described and represented below

  above, but that it encompasses all variants.

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Claims (9)

I - Mixed heating body (1), comprising a domestic heating circuit and a central heating circuit, the latter being arranged one inside the other, characterized in that it comprises a plurality of first elements (2) for the central heating circuit, connected at their ends to feeders (9, 10) and within which meanders a plurality of second elements (3) with complex cross-section, intended for the domestic heating circuit, these second elements (3) also opening into said manifolds (9, 10), the mounting of the second element (3) in the first element (2) further delimiting a plurality of contact generators (6) between said second elements (3) and said first elements (2) in order to produce thermal bridges at these generators.   2 - mixed heating body according to claim 1, characterized in that the first elements (2) are made in the form of a tube of circular or oval cross section, within which are incorporated a plurality of second elements (3) in the form of a tube of complex cross section, such as in particular cross, X, Y.   3 - mixed heating body according to one of claims 1   or 2, characterized in that the heating water circulates in the sections delimited between the outer walls (4) of the complex straight section tube and the inner wall (5) of the first element (2).   4 - Mixed heating body according to any one of   previous claims, characterized in that the profile   complex of the second element (3) guarantees that it has a sufficient exchange surface to allow all of the thermal power delivered by the burner (7) to be removed,   positioned in its lower part.   - Mixed heating body according to any one of   previous claims, characterized in that the circulation   central heating water is carried out in parallel within the manifolds (9, 10), so as to guarantee an identical flow in each of the channels (8), the circulation of sanitary water 9 2741426   being carried out in series and successively within the   plurality of second elements (3).   6 - Heating body according to any one of   previous claims, characterized in that the half   lower and upper shells (11, 12) differ from each other mainly in that one of them has on the external wall of the side housings (9, 10), orifices (13) allowing the connection various heating circuits sanitary and central heating.   7 - Process for developing a mixed heating body according to   any one of the preceding claims, characterized in what it includes:   - A first step consisting in making two half   shells (11, 12), each half-shell (11, 12) essentially comprising a plurality of first elements (2)   extending in the form of semi-cylindrical or semi-cylindrical tubes   ovals, preferably five to eight in number, arranged in parallel and connected at each of their ends to a nurse (9, 10), these various elements being produced as appropriate, in copper or stainless steel.   - A second step consisting in the manufacture of the second elements (3) intended for the circulation of the water of the domestic heating circuit.   - A third step consisting in placing, within the half-shells (11, 12) essentially consisting of first elements (2) connected at their ends to nurses (9, 10)   the coil of second elements (3).   - A fourth step consisting in interposing between the joint planes (14) delimited by the lower and upper half-shells (11, 12), brazing rods (15) and placing above the cylindrical or oval tubes of the first elements (1), a plurality of fins (16), and to bring the   folded edges of the fins initially perpendicular to the   above the tubes so as to form a heating body   mixed (1) manipulable, mechanically integral.   - A fifth step consisting of positioning at the base of the fins (16) and in contact with the first elements (2) forming the heating body, brazing rods and having 2741426   1 set in a brazing furnace operating advantageously   under neutral or reducing atmosphere.   8 - Process for developing a mixed heating body according to   any one of claims 1 to 6, characterized in that   the so-called "strong" brazing step is replaced by a so-called "soft" brazing step, essentially consisting of a phase tinning by soaking.   9 - Method of preparation according to one of claims 7   or 8, characterized in that the separate fins (16) are   replaced by fins in the form of an accordion.   - Method of preparation according to any one of   claims 7 & 9, characterized in that the half-shells   (11, 12) are produced directly by stamping a metallic foil.   11 - Method of preparation according to any one of   claims 7 to 9, characterized in that the various elements   (the first semi-cylindrical or semi-oval elements (2), the lateral deminourrices (9, 10) are produced separately, in particular by stamping, and are made integral by a second operation consisting for example of a welding phase or soldering.   12 - Method of developing a heating body according to one   any of claims 7 to 9, characterized in that the   second elements (3), the cross section of which is complex, in particular of cruciform profile, are obtained from cylindrical tubes delivered in a crown, by a cycle of either cross profiling and then bending of the latter so as to conform a succession of pins forming a serpentine, either bending   of cylindrical tube followed by a hydroforming step.