WO2005064259A1

WO2005064259A1 - Heat exchanger for water-heating apparatuses

Info

Publication number: WO2005064259A1
Application number: PCT/IT2003/000883
Authority: WO
Inventors: Rocco Gionnoni; Remo Castelli
Original assignee: Giannoni S.P.A.
Priority date: 2003-12-31
Filing date: 2003-12-31
Publication date: 2005-07-14
Also published as: AU2003300767A1

Abstract

A heat exchanger (1), preferably intended for water-heating apparatuses (101) provided with a combustion chamber (23), which comprises: a finned tube bundle (11), comprising a plurality of tubular ducts (2) for circulating at least one heat carrier liquid and a plurality of fins (10) externally associated to the tubular ducts (2); a first and a second manifolds (4, 5) of the heat carrier liquid, positioned at opposite ends of the tube bundle (11) and associated to the tubular ducts (2). The manifolds (4, 5) are provided with a substantially planar rear wall (19) positioned near to an axially outermost fin of the plurality of fins (10) so as to pack the plurality of fins (10) at axially opposite ends. The manifolds (4, 5) comprise at lest one support surface (16) defined at an axially outer position with respect to the rear wall (19) and adapted to cooperate with a wall (12) of the combustion chamber (23) to support the heat exchanger (1) in the water-heating apparatus (101). It is therefore possible to reduce the size of the structural support elements, thus obtaining, in a simple and cost-effective way, and advantageous reduction of the overall size of the heat exchanger.

Description

Heat exchanger for water-heating apparatuses

DESCRIPTION

Background of the invention

The present invention refers to a heat exchanger. In particular, the invention refers to a gas-liquid heat exchanger, which has a preferred although not exclusive use as a gas- water exchanger in water-heating intended for both domestic use and utilization in residential areas.

The invention also refers to a water-heating apparatus incorporating the aforementioned exchanger.

Prior art

In the field of gas-liquid heat exchangers in general, and in particular in the field of gas- water exchangers for water-heating apparatuses, one of the most felt needs is that of realizing thermally compact exchangers (i.e. characterized by a high ratio between the heat exchange surface and the overall size of the heat exchanger), while ensuring at the same time a high heat exchange efficiency.

To this end, tube heat exchangers are known, of the type comprising a plurality of tubular ducts for circulating a suitable heat carrier liquid and two manifolds, to which the end of each tubular duct is connected, for distributing and collecting the heat carrier liquid. The tubular ducts are usually provided with outer fins in order to improve the heat exchange between a hot gas that licks the outside of such ducts and the heat carrier liquid that flows inside them. In connection with known exchangers of this type, the manufacturers have tried to give the desired characteristics of thermal compactness essentially intervening on the heat exchange surfaces, but leaving unchanged the structural elements not directly participating in the heat exchange, such as for example the manifolds of the heat carrier liquid or the hydraulic fitting elements. This was done to leave as unchanged as possible the support structures, as well as the fittings provided in the water-heating apparatus for supporting, and connecting with, the heat exchanger itself.

Summary of the invention

The technical problem underlying the present invention is that of providing a gas-liquid heat exchanger, in particular a gas- water exchanger for a water-heating apparatus, which has improved thermal compactness with respect to known exchangers having equal power.

According to the invention, the Applicant has perceived that the aforementioned problem can be solved not by acting upon the heat exchange surfaces, but by suitably intervening on those elements that do not directly participate in the heat exchange so as to reduce the overall size of the exchanger leaving unchanged the exchange surface.

According to a first aspect, the invention thus provides a heat exchanger for a water- heating apparatus provided with a combustion chamber, said exchanger comprising: a finned tube bundle, comprising a plurality of tubular ducts for circulating at least one heat carrier liquid and a plurality of fins externally associated to said plurality of tubular ducts; a first and a second manifolds of the heat carrier liquid, positioned at opposite ends of said tube bundle and associated to said plurality of tubular ducts, said first and second manifolds being provided with a substantially planar rear wall positioned near to an axially outermost fin of said plurality of fins so as to pack said plurality of fins at axially opposite ends,

wherein said manifolds comprise at least one support surface defined at an axially outer position with respect to said rear wall and adapted to cooperate with a wall of the combustion chamber to support the heat exchanger in the water-heating apparatus.

Within the framework of the present description and of the following claims, the term: heat carrier liquid, is used to indicate any liquid which is capable to receive/release heat from/to external heat sources and to transport heat to different points of a system where such fluid flows.

According to the invention, it is advantageously possible to eliminate the portions of the tubular ducts or of the manifolds, which are usually provided between the finned tube bundle and the axially outer portion of the manifolds to form the necessary support surfaces on the walls of the combustion chamber. This advantageously allows to arrange said manifolds in direct contact with the finned tube bundle, so that the manifolds pack the aforementioned plurality of fins at axially opposite ends, thus obtaining a substantial reduction in the overall size of the exchanger along the axial direction.

According to a first preferred embodiment, the first and second manifolds comprise a box-shaped body, whereas the aforementioned at least one support surface is defined on at least one portion of a side wall of the box-shaped body. This embodiment is particularly simple and cost-effective and has a preferred use whenever it is desired to obtain the maximum cost reduction of the exchanger.

According to a further preferred embodiment, the first and second manifolds are provided with a support element associated to their rear wall, whereas the aforementioned at least one support surface is defined on at least one portion of the support element.

Such an embodiment offers the advantage of freeing the shape and position of the support surface from the particular geometry of the manifold walls. In fact, the support element can be shaped in a plurality of shapes independently of the configuration of the manifolds, and can thus be adapted to the size and shape of different combustion chambers, with an advantageous increase in flexibility of use of the exchanger.

Preferably, said support element integrally extends from the rear wall of the manifolds. In such a way, the support element can be produced together with the rear wall, using essentially the same type of mechanical processing, with an advantage in terms of processing time and costs.

In an alternative preferred embodiment, the manifolds comprise a frame at least partially peripherally associated to their rear wall. In this case, the support element is formed on the frame. Preferably, the frame essentially consists of a substantially plate-shaped body in which a suitably shaped opening is formed so as to receive the manifold, preferably with a substantial shape mating..

This embodiment of the present invention advantageously allows to achieve the maximum versatility of the coupling between the exchanger and the combustion chamber. In this case, in fact, it is possible to realize exchangers with a single manifold configuration and then to associate to the manifolds a suitably shaped frame, on which a support element having the desired shape is formed.

The exchanger can thus be adapted for an insertion within various types of water-heating apparatuses and can be arranged to satisfy possible particular requirements of the manufacturers of said water-heating apparatuses.

In a preferred embodiment, the frame is irreversibly associated to the rear wall of the manifolds. This solution ensures a more secure stability of coupling between the frame and the manifolds.

The frame is preferably made of a suitable metallic material having suitable characteristics of mechanical strength, such as for example stainless steel, so as to provide the desired stiffness and mechanical strength to the frame and to the support element formed thereon.

Advantageously, the support element can be shaped according to a plurality of shapes among which the man skilled in the art can choose the most suitable ones according to specific application requirements.

In a preferred embodiment, the support element comprises at least one substantially L- shaped portion.

In a further preferred embodiment, the support element comprises at least one substantially Z-shaped portion.

These features advantageously allow to define a support and abutment surface on the support element, adapted to ensure a stable support of the exchanger on the walls of the combustion chamber and, moreover, adapted to facilitate the assembly of the exchanger inside the water-heating apparatus, which assembly may be carried out, for example, by means of a drawer-type insertion.

According to a further preferred embodiment of the invention, the support element can be provided with reference means adapted to cooperate with respective reference counter means formed in a wall of the combustion chamber to allow a correct positioning of the heat exchanger.

Preferably, the reference means comprises at least one opening or at least one ridge formed in the support element.

Preferably, the reference counter means comprises at least one pin extending from or at least one recess formed in an upper face of a wall of the combustion chamber.

Such reference means and counter means advantageously allow to ensure that the exchanger is correctly positioned above the combustion chamber during the assembly operations.

The manifolds are preferably provided at the top with a fitting element with a lower portion of a fume hood of the water-heating apparatus. Preferably, the fitting element is associated to the rear wall of the manifolds. This advantageously allows to associate the exchanger to the fume hood reducing to a minimum possible leaks of the combustion gases out of the water-heating apparatus.

In a preferred embodiment, such a fitting element integrally extends from the rear wall of the manifolds. This solution is advantageous whenever it is desired to realize the maximum cost reduction of the exchanger itself. In an alternative preferred embodiment and in the case in which the manifolds comprise a frame at least partially peripherally associated to the rear wall of the manifolds, the fitting element with the fume hood is formed on the frame.

This solution offers advantages of high flexibility and adaptability to fume hoods having different shapes and/or sizes, which advantages are analogous to those outlined above in relation to the support element on the walls of the combustion chamber.

Advantageously, also the fitting element with the fume hood can be shaped according to a plurality of shapes, in order to allow a connection with the fume hood that is stable and simple to realize. In a preferred embodiment, the fitting element comprises at least one substantially L-shaped portion. In another preferred embodiment, the fitting element comprises at least one substantially Z-shaped portion.

According to a further preferred embodiment of the invention, the fitting element with the fume hood as well can be provided with reference means adapted to cooperate with respective reference counter means formed in the lower portion of the fume hood to allow a correct positioning of the heat exchanger.

Preferably, the reference means comprises at least one opening or at least one ridge formed in the fitting element.

Preferably, the reference counter means comprises at least one pin extending from or at least one recess formed in the lower portion of the fume hood.

In this case, such reference means and counter means advantageously allow to ensure that the exchanger is correctly positioned below the fume hood during the assembly operations. According to a second aspect, the present invention also refers to a water-heating apparatus, such as for example a boiler, characterized in that it comprises a heat exchanger of the type described above.

Brief description of the drawings

Additional features and advantages of a heat exchanger according to the present invention shall become clearer from the following description of some preferred embodiments thereof, made hereafter, for indicating and not limiting purposes, with reference to the attached drawings. In such drawings: figure 1 is a perspective view of a preferred embodiment of a heat exchanger according to the present invention;

- figure 2 is a schematic side view of the exchanger of figure 1 housed in a water- heating apparatus that is only partially represented;

- figure 3 is a schematic partial side view of some details of a further embodiment of the heat exchanger of figure 1, housed in a water-heating apparatus that is only partially represented; figures 4a and 4b are schematic partial side views of a detail of the exchanger of figure 1, which show different preferred embodiments of support elements of the exchanger; figures 5a, 5b and 5c are schematic partial side views of a detail of the exchanger of figure 1, which show different embodiments of fitting elements to the fume hood; figures 6a, 6b and 6c are partial side views of some details of additional embodiments of the heat exchanger of figure 3.

Detailed description of the preferred embodiments of the invention

In figures 1-3, a gas- water heat exchanger for water-heating apparatuses, in particular of the bi-thermal type, i.e. adapted to simultaneously heat primary water or water for room heating and sanitary water intended for domestic use, is generally indicated at 1.

The exchanger 1 comprises (figure 1) a plurality of tubular ducts 2 that are substantially rectilinear and parallel to each other. Inside the tubular ducts 2 a corresponding plurality of tubular ducts 3, of suitable section and preferably substantially coaxial with the tubular ducts 2, is housed.

Between each tubular duct 2 and the corresponding tubular duct 3 a hollow space 26 is therefore defined in which primary water or water for room heating is circulated, whereas sanitary water is circulated in the tubular ducts 3 .

A first and second manifolds 4, 5 are associated, at axially opposite ends, to the tubular ducts 2 and are in fluid communication with the hollow space 26 intended for the circulation of primary water. Such manifolds comprise a box-shaped body 6, on which a plurality of openings adapted to receive the tubular ducts 2 are formed.

In the illustrated embodiment, the manifold 5 is provided with a pair of inlet and, respectively, outlet fittings 7 for the primary water, whereas the manifold 4 is provided with a pair of inlet and outlet fittings 8 for the sanitary water.

A plurality of U-shaped bends 9, adapted to connect the tubular ducts 3 together, which thus constitute a single substantially coil-shaped continuous duct extending between the two fittings 8, is also associated to the manifolds 4, 5.

A plurality of fins 10 (only partially shown in figure 1), substantially parallel and pitchwise spaced apart from each other, extend on the outside of the tubular ducts 2, to which they are stably associated, for example by brazing. The fins 10 are packed, at axially opposite ends, between rear walls 19 of the manifolds 4, 5 which are preferably substantially planar and act as terminal plates for the aforementioned plurality of fins 10.

The plurality of tubular ducts 2, together with the associated plurality of tubular ducts 3, and the plurality of fins 10 constitute as a whole a finned tube bundle 11 extending between the manifolds 4, 5.

Preferably, the tubular ducts 2, the tubular ducts 3, the fins 10 and the manifolds 4, 5 are made of a suitable metal having good characteristics of heat conductivity, for example copper.

The exchanger 1 is associated to a water-heating apparatus 101, for example a boiler, equipped with a combustion chamber 23, as shown schematically in figure 2. Typically, the exchanger 1 is positioned downstream of the combustion chamber 23, of which only the side walls 12 are partially represented here, and upstream of a fume hood 13.

In this context, the expressions "downstream" and "upstream" are to be understood with reference to the direction along which combustion gases 14 cross the boiler, a direction which is represented by the arrow 15 in figure 2.

The installation of the exchanger 1 in the boiler is accomplished by resting the former on the side walls of the combustion chamber 23. Such resting is accomplished by means of the support surfaces 16, which, according to the present invention, are defined on the manifolds 4, 5 at an axially outer position with respect to the rear walls 19 thereof.

According to a preferred embodiment of the present invention (figures 1, 2, 4a and 4b), the support surfaces 16 are defined on support elements 17 formed on portions of frames 18, which can be applied around the manifolds 4, 5 in a step following their production. In figure 1, the frame associated to the manifold 5 is shown in a perspective partial section view, whereas the frame associated to the manifold 4 is only shown with a broken line for the sake of clarity.

The frames 18 essentially consist of a substantially plate-shaped body 181 in which a suitably shaped opening 182 is formed so as to receive a respective manifold 4, 5. The frames 18 are preferably applied to the manifolds 4, 5 by mechanical shape coupling with the respective rear walls 19. Such a coupling is preferably realized irreversibly, for example by plastically deforming the body 181 at some points of the peripheral edge of the opening 182, so as to create corresponding projections extending from the peripheral edge and adapted to hold the frames 18 in position around the rear walls 19 of the manifolds 4, 5.

The frames 18 are preferably made of stainless steel, so as to ensure the necessary stiffness and mechanical strength.

The support elements 17 can be shaped according to a plurality of shapes, preferably they can be substantially L-shaped or Z-shaped (figures 4a, b).

The manifolds 4, 5 are also preferably provided with fitting elements 20 with a lower portion 13a of the fume hood 13. In a preferred embodiment, also such fitting elements 20 are formed on the frames 18 and can be shaped according to a plurality of shapes to improve the coupling with the fume hood 13. Such shapes are preferably: substantially planar (figures 1, 2 and 5a), substantially L-shaped (figure 5b) or substantially Z-shaped (figure 5c).

The assembly of the heat exchanger 1 in the water-heating apparatus 101 can, for example, be accomplished by means of a drawer-type insertion of the exchanger above the combustion chamber 23. To ease such an operation, the support element 17 is advantageously substantially L-shaped or substantially Z-shaped.

To ensure the correct positioning of the heat exchanger 1 above the combustion chamber 23, the support elements 17 can advantageously be provided with suitable reference means, for example consisting of slots 21 (partially visible in figure 1), adapted to cooperate with corresponding reference counter means, for example consisting of pins 22 extending from an upper face of the side walls 12 of the combustion chamber 23 (see, for example, figure 2).

In a preferred embodiment and in order to ensure the correct positioning of the heat exchanger 1 below the fume hood 13, the fitting elements 20 can also be provided with suitable reference means, for example consisting of pins 24 (partially visible in figure 2), adapted to cooperate with corresponding reference counter means, for example consisting of reference slots 25 formed in the lower portion 13a of the fume hood 13 (see, for example, figures 2 and 5a).

According to another preferred embodiment of the present invention (figures 3, 6b and 6c), the support surfaces 16 are defined on support elements 17 integrally extending from the rear walls 19 of the manifolds 4, 5. Also in this embodiment, the support elements 17 can be shaped according to a plurality of shapes, preferably substantially L-shaped or substantially Z-shaped (figures 6b and 6c), so as to ease the assembly operations by drawer-type sliding of the heat exchanger 1.

Also in this embodiment, the support elements 17 can be provided with slots 21 adapted to engage reference pins 22 extending from an upper face of the side walls 12 of the combustion chamber 23 for a correct positioning of the exchanger, such as for example illustrated in figure 3.

In this embodiment, fitting elements 20 with the fume hood 13 are provided which also preferably integrally extend from the rear walls 19 of the manifolds 4, 5. Similarly to what has been outlined above in relation to the fitting elements 20 of the previous embodiment, the aforementioned fitting elements integrally formed with the rear walls 19 of the manifolds 4, 5 can advantageously be shaped according to a plurality of shapes (not illustrated), such as for example substantially L-shaped or substantially Z-shaped.

Finally, according to a further preferred embodiment of the invention (figure 6a), particularly simple and inexpensive, it is possible to define the support surface 16 directly on at least a portion and preferably on the entire length of the lower side walls 61 of the manifolds 4, 5.

Obviously, those skilled in the art may introduce variants and modifications in the above described invention, in order to satisfy specific and contingent requirements, which variants and modifications fall anyhow within the scope of protection as is defined by the appended claims.

Claims

1. Heat exchanger (1) for a water-heating apparatus (101) provided with a combustion chamber (23), said exchanger comprising:

a finned tube bundle (11), comprising a plurality of tubular ducts (2) for circulating at least one heat carrier liquid and a plurality of fins (10) externally associated to said plurality of tubular ducts (2);

a first and a second manifolds (4, 5) of the heat carrier liquid, positioned at opposite ends of said tube bundle (11) and associated to said plurality of tubular ducts (2), said first and second manifolds (4, 5) being provided with a substantially planar rear wall (19) positioned near to an axially outermost fin of said plurality of fins (10) so as to pack said plurality of fins (10) at axially opposite ends,

wherein said manifolds (4, 5) comprise at least one support surface (16) defined at an axially outer position with respect to said rear wall (19) and adapted to cooperate with a wall (12) of the combustion chamber (23) to support the heat exchanger (1) in the water- heating apparatus (101).

2. Heat exchanger (1) according to claim 1, wherein said first and second manifolds (4, 5) comprise a box-shaped body (6), and wherein said at least one support surface (16) is defined on at least one portion of a side wall (61) of said box-shaped body (6).

3. Heat exchanger (1) according to claim 1, wherein said first and second manifolds (4, 5) are provided with a support element (17) associated to said rear wall (19), and wherein said at least one support surface (16) is defined on at least one portion of said support element (17).

4. Heat exchanger (1) according to claim 3, wherein said support element (17) integrally extends from said rear wall (19) of said first and second manifolds (4, 5).

5. Heat exchanger (1) according to claim 3, wherein said first and second manifolds (4, 5) comprise a frame (18) at least partially peripherally associated to said rear wall (19), and wherein said support element (1 ) is formed on said frame (18).

6. Heat exchanger (1) according to claim 5, wherein said frame (18) is irreversibly associated to said rear wall (19) of said first and second manifolds (4, 5).

7. Heat exchanger (1) according to claim 5, wherein said frame (18) is made of stainless steel.

8. Heat exchanger (1) according to any one of claims 3 to 7, wherein said support element (17) comprises at least one substantially L-shaped portion.

9. Heat exchanger (1) according to any one of claims 3 to 7, wherein said support element (17) comprises at least one substantially Z-shaped portion.

10. Heat exchanger (1) according to any one of claims 3 to 9, wherein said support element (17) is provided with reference means (21) adapted to cooperate with respective reference counter means (22) formed in the combustion chamber (23) to allow a correct positioning of the heat exchanger (1).

11. Heat exchanger (1) according to claim 10, wherein said reference means (21) comprises at least one opening or at least one ridge formed in said support element (17).

12. Heat exchanger (1) according to claim 10, wherein said reference counter means (22) comprises at least one pin extending from or at least one recess formed in an upper face of a wall (12) of the combustion chamber (23).

13. Heat exchanger (1) according to claim 1, wherein said first and second manifolds (4, 5) are provided with a fitting element (20) with a lower portion of a fume hood (13) of the water-heating apparatus (101), said fitting element (20) being associated to said rear wall (19).

14. Heat exchanger (1) according to claim 13, wherein said fitting element (20) integrally extends from said rear wall (19) of said first and second manifolds (4, 5).

15. Heat exchanger (1) according to claim 13, wherein said first and second manifolds (4, 5) comprise a frame (18) at least partially peripherally associated to said rear wall (19), and wherein said fitting element (20) is formed on said frame (18).

16. Heat exchanger (1) according to claim 13, wherein said fitting element (20) comprises at least one substantially L-shaped portion.

17. Heat exchanger (1) according to claim 13, wherein said fitting element (20) comprises at least one substantially Z-shaped portion.

18. Heat exchanger (1) according to any one of claims 13 to 17, wherein said fitting element (20) is provided with reference means (24) adapted to cooperate with respective reference counter means (25) formed in the lower portion of the fume hood (13) to allow a correct positioning of the heat exchanger (1).

19. Heat exchanger (1) according to claim 18, wherein said reference means (24) comprises at least one opening or at least one ridge formed in said fitting element (20).

20. Heat exchanger (1) according to claim 18, wherein said reference counter means (25) comprises at least one pin extending from or at least one recess formed in a lower portion of the fume hood (13).

21. Water-heating apparatus (101) comprising a heat exchanger (1) according to any one of the previous claims.