Regenerator / heat exchanger

Abstract

 A heat exchanger (1) for heating devices, such as for example boilers, comprises a plurality of pipes (10) inserted in a containment structure (50) and traversed by a first fluid. The containment structure is traversed internally by a second fluid introduced and emptied out by means of appropriate openings (80, 90). Said pipes (10) have externally a longitudinal finned portion and are inserted in the containment structure (50) with the longitudinal axis oriented according to the path followed by the second fluid during its passage within the containment structure (50).

Description

[0001] The present invention relates to a heat exchanger to be used in making heating devices and preferably as secondary heat exchanger for boilers designed for domestic or industrial use.

[0002] Heat exchangers, as is known, are equipments that enable transfer of a certain amount of thermal energy from a hotter fluid to a colder fluid without the two fluids coming into contact with one another. To separate the two fluids chemically, preventing mixing thereof, metal walls are normally used which by their nature facilitate heat exchange. Equipments of this sort are hence already widely used in the manufacture of heating plants.

[0003] In the patent application No. EP 0945688 a heating equipment is, for example, described which uses a first heat exchanger, defined as primary, positioned substantially up against the combustion chamber, and a second heat exchanger, defined as secondary, positioned, instead, between the source of water to be heated and the primary heat exchanger. The first heat exchanger enables heating of the water via the flame coming from the gas nozzles, whilst the secondary heat exchanger exploits as heat-vector fluid the fumes deriving from the combustion for the purpose of carrying out a pre-heating of the water before this reaches the primary heat exchanger. The use of a secondary heat exchanger for this purpose is hence very important in so far as it enables an improvement in the efficiency and overall performance of the entire heating plant, optimizing and at the same time reducing the consumption of gas or other combustible substance.

[0004] Despite their widespread use, heat exchangers currently employed in any case present certain drawbacks that limit their use and possible performance. An example of secondary heat exchanger currently used is given in the patent application referred to above. In this embodiment, the heat exchanger consists of a battery of pipes housed inside a containment chamber. The pipes are traversed internally by the water and are externally impinged upon by the fumes produced by combustion. Through a phenomenon of convection-conduction, the thermal energy is thus transferred from the fumes to the water, exploiting precisely the metal wall of the pipes. To enable the fumes to follow a given path within the containment chamber the use of a partition wall that substantially separates the inlet from the outlet is envisaged.

[0005] The solution just described presents, however, various limits linked in particular to the operations of construction and assembly of the components, which appear rather problematical and far from economically advantageous.

[0006] Another example of heat exchangers currently used is presented in the patent application No. EP 1 243 866. In this second case, the heat exchanger consists principally of a series of pipes maintained in the positions with respect to one another through the use of two flanges mounted at the ends thereof. The two flanges are externally shaped to enable communication between the different pipes for the purpose of providing a pre-set circuit, in which the water is forced to pass. The products of combustion lap externally the battery of pipes in a direction substantially orthogonal to the longitudinal axis of the pipes themselves, thus bringing about heating of the water.

[0007] Also this solution, albeit being quite effective from the functional standpoint, presents drawbacks that can be identified prevalently in the use of the two flanges. The use of external shapings or in any case external unions, leads to an increase in the overall dimensions of the heat exchanger that has adverse repercussions in terms of an increase in the costs of construction thereof.

[0008] In order to increase heat exchange, in almost all heat exchangers currently used the pipes dedicated to the passage of the water have a plurality of finned portions associated to the outer surface of the pipes themselves according to a substantially comb-like arrangement. Such a solution is presented, for example, in the patent application No. EP 0 905 457. In the latter document, there is noted also the use of deviators, substantially parallel to the longitudinal axis of the pipes, which have the purpose of deflecting the fumes in pre-set directions.

[0009] The solution indicated in the latter patent application referred to presents as major drawback the high head losses that occur both on account of the use of the aforesaid deviators and because the hot fumes impinge upon the pipes in a direction substantially orthogonal to the longitudinal axis thereof.

[0010] On the basis of these considerations, the main task of the present invention is to provide a heat exchanger to be used in making heating devices that will enable the drawbacks referred to above to be overcome.

[0011] In the framework of this task, a purpose of the present invention is to provide a heat exchanger in which the heat exchange between the two fluids used for the purpose of obtaining a high overall efficiency is optimized.

[0012] A further purpose of the present invention is to provide a heat exchanger that is structurally compact and obtained using components that can be easily assembled together.

[0013] Not the least important purpose of what forms the subject of the present invention is to provide a heat exchanger that presents high reliability, relative ease of construction and competitive costs.

[0014] This task, as well as the above-mentioned purposes and others that will appear more clearly from what follows, are achieved through a heat exchanger for heating devices which comprises:

• a plurality of pipes, which are connected together and are equipped on the outside with finned portions, designed to enable the passage of a first fluid;
• a containment structure designed to contain the plurality of pipes; said containment structure comprises at least one first opening and one second opening, which are designed, respectively, to enable introduction of a second fluid into the structure itself and emptying of said fluid therefrom.

[0015] The heat exchanger according to the invention is characterized in that the finned portions develop along the longitudinal direction of the pipes and in that said plurality of pipes is located within the containment structure so as to have one end set in the proximity of said first opening and the opposite end set in the proximity of said second opening.

[0016] The arrangement of the pipes in a direction that substantially reflects the path followed by the heat-vector fluid within the containment structure and the particular longitudinal finned portion obtained externally on the pipes advantageously enable optimization of heat exchange, at the same time reducing the head losses and the phenomena of turbulence that will inevitably occur.

[0017] Further characteristics and advantages of the invention will emerge more clearly from the description of preferred, but non-exclusive, embodiments of the heat exchanger according to the invention, illustrated as non-limiting example in the annexed drawings, in which:

• Figures 1a and 1b are cross-sectional views, according to different and parallel planes of observation, of a first embodiment of the heat exchanger according to the invention;
• Figures 2a, 2b are cross-sectional views, according to different and parallel planes of observation, of the heat exchanger of figures 1a and 1b;
• Figures 3a, 3b are two views in orthogonal projection, according to different points of observation, of a possible embodiment of a containment structure for a heat exchanger according to the invention;
• Figures 4a, 4b are two views in orthogonal projection, according to different points of observations, of a possible embodiment of the pipes for a heat exchanger according to the invention;
• Figures 5a, 5b are views in orthogonal projection of a possible embodiment of two components for a heat exchanger according to the invention;
• Figures 6a, 6b, 6c, 6d, 6e and 6f are views in orthogonal projection of a possible embodiment of further components for a heat exchanger according to the invention;
• Figure 7 is an expanded view of a second embodiment of the heat exchanger according to the invention;
• Figures 7a, 7b are perspective views of components for the heat exchanger of Figure 7.

[0018] With reference to the above figures, the heat exchanger 1 according to the invention comprises a plurality of pipes 10, internally traversed by a first fluid, which are housed within a containment structure 50; the latter comprises at least one first opening 80 and one second opening 90, which are provided for the purpose of enabling, respectively, introduction of a second fluid into the containment structure 50 and emptying thereof. As may be noted from Figures 4a and 4b, the plurality of pipes 10 is formed by individual constitutive elements which, according to the invention, have particular external finned portions 100 that develop continuously in the longitudinal direction of said pipes 10. The finned portions 100, if viewed according to a plane substantially orthogonal to the longitudinal axis of the pipes 10, develop according to a sheaf of planes having as centre the longitudinal axis of each pipe.

[0019] By exploiting, for example, traditional processes of extrusion, there is thus advantageously obtained a different profiling of the finned portions that replaces the traditional "comb-like" arrangement already referred to above. For this reason, for construction of the individual pipes 10 it is possible to use easily extrudable materials, such as, for example, aluminium. The form and the process of production of these pipes 10 advantageously meet the various requirements of production linked, for example, to the dimensions of the heat exchanger. In fact, from a single extruded bar it is possible to obtain longitudinally finned pipes 10 having different dimensions with a considerable reduction in the costs of construction and assembly.

[0020] Also the number of pipes 10 may vary according to the requirements, as likewise it is possible to vary the distance apart from one another of each pipe, which is maintained through the use of an appropriate frame, described hereinafter. Hence the pipes 10 assume the form of modular elements to be used advantageously for the construction of heat exchangers of different dimensions according to the desired performance.

[0021] According to the invention, the plurality of pipes 10 is inserted within the containment structure 50 so as to have a first end located in the proximity of the first opening 80 and the opposite end located in the proximity of the second opening 90. This arrangement leads to having a longitudinal axis of the pipes 10 oriented in a direction substantially coinciding with the path that is followed by the second fluid during its passage within the same structure 50. In this way, each finned portion is externally lapped by the second fluid in a uniform way throughout its length, thus optimizing the heat exchange that is obtained.

[0022] The heat exchanger 1 according to the invention is realized in such a way that the passage of the first fluid from a first pipe to a second pipe is carried out through the use of first means for mutual connection of the pipes that are entirely contained within the containment structure 50. In particular, according to a preferred embodiment of the invention, represented in figures 1a and 1b, said first means for mutual connection provide a communication between two adjacent pipes 10a and 10b in positions corresponding to the respective adjacent ends 9a and 9b.

[0023] The latter said figures show in detail also a possible embodiment of said first means for mutual connection. In particular, these means may advantageously comprise a first element 11 of union and a second element 12 of union associated to each of said adjacent ends 9a and 9b, and a third element 13 for connection between the first element 11 of union and the second element 12 of union.

[0024] For the purpose of reducing the costs of manufacture, the invention advantageously envisages a common embodiment, illustrated for example in Figures 6e and 6f, for the elements of union 11 and 12 defined above. As may be noted from Figures 6f and 6c, said elements of union, together with the third element 13 of connection, have a hollow shape in order to enable passage of the first fluid. Appropriate seal means 130, such as for example annular gaskets, enable a secure connection between the different components constituting the first means of mutual connection, at the same time preventing mixing of the two fluids.

[0025] Through the use of connections of this sort, there is in practice provided a hydraulic circuit, within which the first fluid is forced to pass. The heat exchange that is achieved between the first fluid and the second fluid occurs in conditions of the same direction of flow and at the same time also in conditions of counter current. The second fluid maintains in fact always the same direction whilst it internally traverses the containment structure; the first fluid, albeit maintaining a direction substantially coinciding with that of the second fluid, varies each time its own direction of flow as a result precisely of the first means of mutual connection. This particularity, combined with the creation of an appropriately designed hydraulic circuit, enables a sensible increase in the overall efficiency of the heat exchanger 1.

[0026] The figures 2a, 2b, 3a, 3b, show a possible embodiment of a containment structure 50, according to the invention, which advantageously comprises a box 70 and a closing plate 60 associated thereto so as to create an internal space, in which said plurality of pipes 10 can be housed, as referred to above. The containment box 70 has an advantageously prismatic shape comprising four lateral surfaces 71, 72, 73, 74 and a fifth bottom surface 75 substantially orthogonal to the previous ones. In particular, it emerges from the figures that the first lateral surface 71 is opposite to the second lateral surface 72; the third lateral surface 73 is orthogonal to the first lateral surface 71 and to the second lateral surface 72 and is substantially opposite to the fourth lateral surface 74.

[0027] With specific reference to Figure 2a and 2b, the closing plate 60 is associated to the box 70 in a position substantially opposite to the bottom surface 75, so as to obtain a convenient containment structure 70 of a closed prismatic shape.

[0028] With reference, instead, to the already cited Figures 3a and 3b, the first opening 80 and the second opening 90, for the passage of the second fluid from the inside to the outside of the containment structure 50 and vice versa, can be obtained on one or more of the walls forming the containment structure or else on the closing plate 60 or on one or more of the surfaces of the box 70. According to a preferred embodiment of the invention, said openings are provided both on one of the said lateral surfaces, for example, on said first lateral surface 71.

[0029] Once again from the latter mentioned figures, it may be noted that the heat exchanger according to the invention comprises a first inlet part 81 associated to the first opening 80 and a second discharge part 91 associated instead to the second opening 90. The first inlet part 81 is shaped so as to favour entry of the second fluid into the containment structure 50, whilst the second discharge part 91 is shaped so as to favour its exit.

[0030] With reference to Figures 2a and 2b, the containment structure 50 comprises at least a third opening dedicated to receiving second means of connection associated to said plurality of pipes 10 and dedicated to introducing the first fluid into the pipes and to emptying said fluid therefrom. In practice, this opening and these second means of connection are indispensable for defining the inlet and the outlet of the hydraulic circuit formed through the use of the aforesaid first means of connection. According to a preferred embodiment, the positioning of said second means occurs through a fourth opening 95 and a fifth opening 96 provided on said closing plate 60 and belonging to said containment structure 50.

[0031] The second means of connection comprise preferably a fourth element 14 and a fifth element 15 associated respectively to the adjacent ends 9c and 9d belonging to two adjacent pipes 10c and 10d, as well as a third part 101 and a fourth part 102 associated, respectively, to the element defined as fourth element 14 and the element defined as fifth element 15. Said third part 101 and said fourth part 102 conveniently exit from said containment structure 50 through said third opening 95 and said fourth opening 96, respectively.

[0032] In a way similar to what has been described regarding the first means of connection, the invention advantageously envisages the use of a common embodiment, illustrated for example in Figures 6a and 6b, for said third element 14 and said fourth element 15, as well as a common embodiment also for said third part 101 and fourth part 102, illustrated, for example, in Figure 6d.

[0033] Figure 5a relates to a possible embodiment of the closing plate 60 forming the containment structure 50. In particular, the closing plate 60, in addition to the already defined fourth opening 95 and fifth opening 96, advantageously comprises also grooves 62 designed to convey products deriving from phenomena of condensation that develop within the containment structure 50. As may be noted from Figure 5a, the invention also envisages a sixth opening 63, to which said condensed products are conveyed, for example, by providing the grooves 63 so as to present slight inclinations in the direction of the sixth opening 63.

[0034] The heat exchanger 1 according to the invention also comprises a frame dedicated to enabling a stable positioning of the plurality of pipes 10 within said containment structure 50. According to a preferred embodiment, which may be seen, for example, in Figure 1b, the frame is obtained through a first flange 56 and a second flange 57 that intercept the plurality of pipes 10 in positions corresponding to opposite ends. In particular, the flanges 56 and 57 are anchored to the aforementioned first and second means of connection through the use, for example, of bolted joints. Said joints enable the pipes to maintain a stable position with respect to one another and can be obtained, for example, by exploiting threaded ends 105 projecting from said elements of union 11, 12, 14, 15 and can be inserted within appropriate seats 106 obtained on the two flanges 95 and 96. The use then of nuts 107 completes the joint.

[0035] The working principle of the heat exchanger 1 according to the invention thus appears immediately and readily understandable. Assuming, for example, that the heat exchanger acts as secondary heat exchanger in a boiler, through the first opening 80 the fumes coming from the combustion chamber are conveyed into the containment structure 90. At the same time, the water traverses the hydraulic circuit obtained with said plurality of pipes and with said first and second means of connection. The hot fumes traverse the inside of the containment structure 50, lapping the outside of the pipes throughout their length and in a direction substantially coinciding with that of the longitudinal axis of the pipes themselves.

[0036] In order to facilitate direction of flow of the fumes, i.e., to enable them to be easily oriented according to the longitudinal axis of the pipes, the heat exchanger 1 according to the invention may also comprise appropriate conveyors, not illustrated in the figures, formed, for example, by thin bent plates of metal. Said conveyors advantageously limit the phenomena of turbulence that may occur, thus increasing the efficiency of the heat exchanger.

[0037] With reference, for example, to Figure 1a or Figure 1b, it is moreover to be noted, according to a preferred embodiment of the invention, that the internal walls forming the containment structure 50 are appropriately radiused to limit any intense head losses and the phenomena of recirculation of fumes, which would occur in the presence of sharp edges. The latter expedients referred to above thus enable high performance to be obtained, as well as optimization of operation of the heat exchanger above all in the areas of entry and exit of the fumes, where, that is, the major head losses would occur.

[0038] Figure 7 relates to a further embodiment of the heat exchanger according to the invention. According to this embodiment, the containment structure 50 comprises a first containment element 51 designed to be stably connected to a second containment element 52 through the use of means for mutual locking that, for example, can be tension rods 200 positioned along the same direction of said elements.

[0039] According to the invention, the above-defined first 80 and second 90 opening for the introduction and discharge in/from the containment structure 50, are made on a first part of said first containment element 51 and on a second part of said second containment element 52, each of said parts being close to one end of pipes 10. Also in this embodiments, the heat exchanger 1 comprises moreover conveying means 92 designed to facilitate introduction and discharge of said second fluid in/from the exchanger 1.

[0040] In order to allow the mutual connection of the pipes 10, according to this embodiment of the invention, the above-defined first means for mutual connection comprise a first 58 and a second 59 tank which are respectively realized inside said first 51 and second 52 containment element. Each of said tanks 58, 59 is advantageously delimited by a first wall 61a which is use for stable anchoring an end of the pipes 10 and by a second wall 61b, preferably removable, which can be fixed to the corresponding containment element through the use, for example, of simple screw connection 62. Each first wall 61 a has the purpose of hermetically separating each tank 58 or 59 from the remaining part of the containment structure 50 so as to avoid mixing of the two fluids circulating in the exchanger 1.

[0041] The introduction/discharge of the second fluid from the tanks 58 and 59 can be advantageously carried out by using a first 53 and a second 54 opening, respectively made on the first 51 and second 52 containment element so as to communicate with the outside.

[0042] Figures 7a and 7b allow to see a possible embodiment of said containment elements 51 and 52 and the corresponding tanks 58 and 59, according to the invention. In particular, each tank comprises partitioning means designed to allow the mutual passage of said first fluid between the pipes 10 according to a predetermined path. The use, for example, of a partitioning wall 99 allows to create a first and a second region in the tank, which are separated from each other in such a way that only the pipes 10 belonging to the same region are in mutual connection with each other. By properly positioning the partitioning walls 99 in the two tanks 58 and 59 it is possible to impose to the first fluid an alternating passage inside the pipes 10, so as to guarantee a heat exchange which is alternatively equicurrent and counter-current, thereby improving the performances of the heat exchanger 1.

[0043] The technical solutions adopted enable the pre-set tasks and purposes to be fully achieved. In particular, the heat exchanger according to the invention has a compact structure and is easy to assemble. The particular arrangement of the components described moreover enables a high overall efficiency to be achieved through an optimization of heat exchange and a reduction in head losses.

[0044] The heat exchanger thus conceived may undergo numerous modifications and variations, all falling within the scope of the inventive idea. Furthermore, all the items may be replaced by other technically equivalent ones.

[0045] In practice, the materials used, as well as the dimensions and the contingent shapes, may be any whatsoever according to the requirements and the state of the art.

Claims

1. A heat exchanger (1) for heating devices comprising:

- a plurality of pipes (10), which are connected together and are designed to enable the passage of a first fluid, each of said pipes comprising finned external portions (100);

- a containment structure (50) designed to contain said plurality of pipes, said structure (50) comprising at least one first opening (80) and one second opening (90), which are designed to enable, respectively, introduction of a second fluid into said containment structure (50) and emptying of said fluid therefrom,

said heat exchanger being characterized in that said finned portions (100) develop along the longitudinal direction of said pipes, one end of said plurality of pipes (10) being located within said containment structure (50) in the proximity of said first opening (80), and the opposite end of said plurality of pipes (10) being located within said containment structure (50) in the proximity of said second opening (90).

2. The heat exchanger (1) according to Claim 1, characterized in that said finned portions (100) develop continuously along the longitudinal direction of said pipes (10).

3. The heat exchanger (1) according to Claim 1 or Claim 2, characterized in that it comprises first means for mutual connection of said pipes (10), said first means being entirely contained within said containment structure (50).

4. The heat exchanger (1) according to Claim 3, characterized in that said first connection means enable mutual connection of two adjacent pipes (10a, 10b) at the respective adjacent ends (9a, 9b).

5. The heat exchanger (1) according to any of Claims from 1 to 4, characterized in that said first means comprise a first inlet part (81) associated to said first opening (80) and a second part (91) of union associated to said second opening (90), said first part of union (81) being shaped so as to favour entry of said second fluid into said containment structure (50), said second part of union (91) being designed to favour emptying of said second fluid from said containment structure (50).

6. The heat exchanger (1), according to one or more of Claims from 1 to 5, characterized in that said containment structure (50) comprises a box (70) and a closing plate (60) associated thereto, said box (70) having a substantially prismatic shape comprising a first lateral surface (71), a second lateral surface (72) substantially opposite to said first lateral surface (71), a third lateral surface (73) substantially orthogonal to said first and to said second lateral surfaces (71, 72), a fourth lateral surface (74) substantially opposite to said third lateral surface (73), a fifth bottom surface (75) substantially orthogonal to said lateral surfaces (71, 72, 73, 74), said closing plate (60) being associated to said box (70) in a position substantially opposite to said bottom surface (75), said first (80) and second (90) opening being provided on one or more of said surfaces forming said containment structure (50).

7. The heat exchanger (1) according to Claim 6, characterized in that said first opening (80) and said second opening (90) are provided on said first lateral surface (71) and/or on said second lateral surface (72).

8. The heat exchanger (1), according to one or more of Claims from 4 to 7, characterized in that said first connection means comprise at least one first element (11) of union and one second element (12) of union associated to each of said adjacent ends (9a, 9b) and a third element (13) for connection between said first element (11) of union and said second element (12) of union.

9. The heat exchanger (1) according to one or more of Claims 6 to 8, characterized in that said containment structure (50) comprises at least one third opening dedicated to receiving second means of connection designed to enable introduction and emptying of said first fluid into/from said plurality of pipes (10).

10. The heat exchanger (1) according to Claim 9, characterized in that said containment structure (50) comprises at least one fourth opening (95) and one fifth opening (96) dedicated respectively to receiving said second means of connection, said fourth opening (95) and said fifth opening (96) being provided on said closing plate (60).

11. The heat exchanger (1) according to Claim 10, characterized in that said second means of connection comprise a fourth element (14) and a fifth element (15) associated respectively to the adjacent ends (9c, 9d) of two adjacent pipes (10c, 10d) belonging to said plurality of pipes (10), said second means of connection further comprising a third part (101) and a fourth part (102) associated, respectively, to said fourth element (14) and to said fifth element (15).

12. The heat exchanger (1) according to Claim 11, characterized in that said third part (14) and said fourth part (15) exit from said containment structure (50) through said third opening (95) and fourth opening (96).

13. The heat exchanger (1) according to one or more of claims from 6 to 12, characterized in that said closing plate (60) comprises grooves (62) designed to convey products deriving from phenomena of condensation that develop within said containment structure (50), said closing plate (60) further comprising a fifth opening (63) dedicated to emptying said condensed products.

14. The heat exchanger (1) according to one or more of claims from 1 to 13, characterized in that it comprises a frame designed to enable a stable positioning of said plurality of pipes (10) within said containment structure (50).

15. The heat exchanger (1) according claim 14, characterized in that said frame comprises a first flange (56) and a second flange (57) that intercept said plurality of pipes (10) in positions corresponding to opposite ends, said first flange (56) and said second flange (57) being anchored to said first means and to said second means of connection through bolted joints.

16. The heat exchanger (1) according to one or more of claims from 1 to 15, characterized in that said finned portions (100), viewed in a plane substantially orthogonal to the longitudinal axis of said pipes (10), develop according to a sheaf of directions having as centre of the sheaf said longitudinal axis.

17. The heat exchanger (1) according to one or more of claims from 1 to 16, characterized in that it comprises appropriate conveyors designed to orient the path of said second fluid according to the longitudinal axis of the pipes (10).

18. The heat exchanger (1) according to one or more of claims from 1 to 5, characterized in that said containment structure (50) comprises a first containment element (51) designed to mutually couple to a second containment element (52), said first opening (80) and said second opening (90) being respectively made on a first part of said first element (51) and on a second part of said second element (52), said first (51) and second (52) containment elements being operatively connected through means for mutual locking.

19. The heat exchanger (1) according to claim 18, characterized in that said first connection means of said pipes (10) comprises a first (58) and second (59) tank respectively made inside said first (51) and second (52) containment element.

20. The heat exchanger (1) according to claim 19, characterized in that each of said tanks (58, 59) is delimited by a first wall (61a) designed to stably lock one end of said pipes (10) and by a second wall (61b) manually removable.

21. The heat exchanger (1) according to one or more of claims from 18 to 20, characterized in that said first (58) and/or second (59) tank comprise a first (53) and a second (54) inlet designed to allow introduction and discharge of said first fluid in/from said heat exchanger (1).

22. The heat exchanger (1) according to one or more of claims from 18 to 21, characterized in that said first (58) and/or second (59) tank comprise partitioning means designed to allow the passage of said first fluid between said plurality of pipes according to a predetermined path.

Drawing