EP2236952B1

EP2236952B1 - Tubular device for the transit of a heat exchange fluid particularly for heat exchangers, and a liquid/gas heat exchanger, particularly for boilers,comprising a series of tubular devices

Info

Publication number: EP2236952B1
Application number: EP10158755.8A
Authority: EP
Inventors: Bortolo Zen
Original assignee: Sari - Stampi Articoli Industriali Di Zen Bortolo
Current assignee: Sari - Stampi Articoli Industriali Di Zen Bortolo
Priority date: 2009-03-31
Filing date: 2010-03-31
Publication date: 2016-03-23
Anticipated expiration: 2030-03-31
Also published as: SI2236952T1; PL2236952T3; HUE030761T2; DK2236952T3; HRP20160712T1; IT1393847B1; ES2576989T3; EP2236952A1; ITPD20090071A1

Description

The present invention refers to a tubular device for the transit of a heat exchange fluid particularly for heat exchangers. The invention also refers to a liquid/gas heat exchanger, particularly for boilers, comprising a series of such tubular devices.
Nowadays, liquid/gas heat exchangers, particularly for boilers, with excellent yield are known and widespread and they meet with great satisfaction from installers. Such boilers comprise a passage chamber for a first heat exchange fluid, crossed by passage ducts for a second heat exchange fluid, the particularity of which lies in the fact that at least part of such ducts is provided by a plurality of tubes, each of which has a cross section with a profile that is formed by a plurality of lobes arranged in a substantially radial direction.
The particular shape of such tubes makes it possible to considerably increase the turbulence of the gas that has to cross them, compared with tubes with a circular or a lenticular cross section.
Nonetheless, such tubes with a lobar cross section may be improved.
Indeed, insofar as the blending zones between two successive lobes of a tube are close to the axis of the tube, around such axis a channel always remains from which the hot gas escapes without having optimally washed around the internal surfaces of the channels with a lobar cross section of the tube, and thus having substantially yielded very little of the heat it possesses.
In addition, such known tubes, precisely because they present a cross section that is very narrow at the center, are difficult to clean and relatively prone to clogging. Document US 2008/0029243 A1 discloses such tubes with a lobar cross-section that is very narrow at the center.
A heat exchange tube for a heat exchanger is known from US 2 445 471 . The tube has a pleated surface and is provided, inside, with a core that forces gas or fluid passing through the tube into radially outward projecting interstices formed by the pleated outer wall of the tube. US 2 445 471 discloses a tubular device for the transit of a heat exchange fluid, particularly for heat exchangers, comprising a tube that has at least one portion of its cross-section with a profile that is formed by a plurality of lobes arranged in a substantially radial direction, such that it comprises a removable rod-like flow redirection element inserted in the axial space between the blending portions between two successive lobes, and designed to redirect laterally the flow of heat exchange fluid introduced in said tube toward the heat exchange channels of said tube that have a lobate cross-section.
The aim of the present invention is to provide a tubular device for the transit of a heat exchange fluid, particularly for heat exchangers, that is capable of overcoming the drawbacks of tubes with a lobar cross section of the known type.
Within this aim, an object of the invention is to provide a liquid/gas heat exchanger, particularly for boilers, fitted with a plurality of tubular devices.
Another object of the invention is to provide a tubular device in which the gas that crosses it is subjected to a turbulence that improves the heat exchange compared to what can be achieved with tubes of the known type.
Another object of the invention is to provide a tubular device that is easy to clean.
Another object of the invention is to device a liquid/gas heat exchanger of greater yield than similar exchangers of the known type.
A further object of the invention is to provide a tubular device for the transit of a heat exchange fluid, particularly for heat exchangers, and a liquid/gas heat exchanger particularly for boilers, comprising a series of such tubular devices, structurally simple and easy to use, which can be made using known systems and technologies,
This aiim, as well as these and other objects which will become better apparent hereinafter, are achieved by a tubular device for the transit of a heat exchange fluid, particularly for heat exchangers, according to the invention, that has the features set forth in claim 1.
Advantageously, a liquid/gas heat exchanger, particularly for boilers, comprises a passage chamber for a first heat exchange fluid and passage ducts for a second heat exchange fluid, said passage chamber being crossed by said passage ducts, and is characterised in that at least part of said passage ducts are formed by a plurality of tubular devices according to the invention.
Further characteristics and advantages of the invention will become better apparent from the following detailed description of three preferred, but not exclusive, embodiments of the tubular device for the transit of a heat exchange fluid, particularly for heat exchangers according to the invention, as well as of a liquid/gas heat exchanger fitted with a plurality of said tubular devices, illustrated by way of non-limiting example in the accompanying drawings, wherein:

Figure 1 is a perspective view of a tube of the tubular device according to the invention in a first embodiment thereof;
Figure 2 is a longitudinal sectional view of the tubular device according to the invention of Figure 1;
Figure 3 is a transverse sectional view, taken along the line III-III of Figure 2, of the tubular device according to the invention in its first embodiment;
Figure 4 is a transverse sectional view, taken along the line IV-IV of Figure 2, of the tubular device according to the invention in its first embodiment;
Figure 5 is a transverse sectional view, taken along the line V-V of Figure 2, of the tubular device according to the invention in its first embodiment;
Figure 6 is a view of a tubular device;
Figure 7 is a view of another tubular device;
Figure 8 is a side sectional view of a heat exchanger according to the invention, fitted with tubular devices according to the invention;
Figure 9 is a transverse sectional view of the exchanger according to the invention, taken along the line IX-IX of Figure 8.

The embodiments of figures 6-7 are not covered by the presently claimed invention. They are examples of possible tube configurations that are useful for understanding the invention.
A tubular device for the transit of a heat exchange fluid, particularly for heat exchangers, according to the invention, is shown in a first embodiment thereof in Figures 1 through 5, and is designated therein by the reference numeral 10.
The tubular device 10 is of the type comprising a tube 11 having a series of tube portions 11a, 11b and following, each of which in cross section 12 (Figure 4) has a profile that is formed by three lobes 13, 14 and 15, arranged in a substantially radial direction.
The tubular device 10 according to the invention comprises a removable rod-like flow redirection element 16 inserted in the axial space between the blending zones 17, 18 and 19 between two successive lobes.
The rod-like element 16 is designed to redirect laterally the flow of heat exchange fluid introduced into the tube 11, toward the heat exchange channels 20, 21, 22 of the same tube portion 11a, 11b, 11c and following, of the tube 11 having a lobar cross section.
The portions 11a, 11b and following are made in such a way that the cross sections of two successive tube portions 11a, 11b and following are rotated with respect to the axis of the tube 11 by a certain angle, for example 60° as shown by the cross section 12a in Figure 5, of the tube portion 11b, and with respect to the cross section 12 in Figure 4, of the tube portion 11a.
The rod-like redirection element 16 has a contoured grip end 23, clearly visible in Figure 2, for the extraction of the rod-like element 16 from the tube 11, for cleaning the tube 11.
In such first embodiment of the tubular device 10 according to the invention described up to now, the tube 11 has a cross section that comprises three lobes 13, 14 and 15 arranged substantially at 120 sexagesimal degrees with respect to each other.
It should be appreciated that the lobes, in alternative embodiments, can also be different in number.
In such first embodiment of the tubular device 10 according to the invention described up to now by way of non-limiting example of the invention, the tube 11 has a rectilinear longitudinal extension, and the portions 11a, 11b and following with a cross section 12 that comprises three lobes alternate with portions 11e, 11f and following with a cross section that is substantially circular, as can be seen in Figures 1 and 2.
In a second embodiment, not part of the invention, schematically shown in Figure 6, the tubular device according to the invention, indicated therein with the reference numeral 110, comprises a tube 111 with a cross section that comprises three lobes, with continuous rectilinear longitudinal extension, with no portions having a circular cross section.
The corresponding rod-like element 116 with the contoured grip end 123 is schematically shown inside the tube 111.
In a third embodiment of the tubular device, not according to the invention, indicated in Figure 7 with the reference numeral 210, the tube 211 has a helical longitudinal extension.
The tube 11, as well as 111 and 211, have end portions 24 and 25 that are substantially cylindrical, and therefore relatively simple to be welded onto.
Figure 3 shows a cross section 12b of a first end 24.
The tube 11, 111, 211 can easily be obtained by processing involving pressing of a metal tube.
The rod- like element 16 and 116 can be obtained from a metal bar. The invention also refers to a liquid/gas heat exchanger, designated in Figures 8 and 9 with the reference numeral 30.
The exchanger 30, particularly for boilers for example powered by diesel fuel or by co-generation, comprises a passage chamber 35 for a first heat exchange fluid, crossed by passage ducts 32 for a second heat exchange fluid.
Part of such ducts is provided by a plurality of tubular devices 10 or 110 or 210 as described above.
The exchanger 30 comprises a main external body 33 containing an intake chamber for the gas 34, which forms, together with the main body 33, the passage chamber 35 for a first heat exchange fluid.
The gas intake chamber 34 is surrounded by a series of heat exchange ducts 36, circular in cross section, and by a series of the tubular devices 10.
The two series of ducts are arranged on two concentric circumferences.
The gas is conveyed from the intake chamber 34 to the ducts 36 with circular cross section by means of a first redirection and exchange bottom 37.
The same gas that exits from the ducts 36 with circular cross section is conveyed to the tubular devices 10 by means of an annular chamber 38 surrounding the inlet of the gas intake chamber 34.
The exchanger 30 is closed in an upper region by a flange 39 with a hole for the passage of gas, and in a lower region by a second condensation collecting bottom 40 with an inlet 41 for a flue.
At least one of the flange 39 and the second bottom 40 is designed to be removed for the extraction of the rod-like redirection elements 16 of the tubular devices 10 for cleaning the tubes 11 thereof.
In practice it has been found that the invention fully achieves the intended aim and objects.
In particular, with the invention a tubular device has been provided in which the gas that crosses it is subjected to a turbulence that improves the heat exchange compared to what can be achieved with tubes of the known type, and consequently a liquid/gas heat exchanger has been devised, particularly for boilers, fitted with a plurality of tubular devices as per the aim of the invention, of improved yield compared to similar exchangers of the known type.
In addition, as a result of the presence of the removable rod-like element 16, a tubular device has been provided that is easy to clean, since it is sufficient to remove the rod-like element 16 in order to have sufficient space inside the tube 11 to manoeuvre a cleaning instrument.
Moreover, with the invention a liquid/gas heat exchanger has been devised that has a greater yield than similar exchangers of the known type.
Further, with the invention a tubular device for the transit of a heat exchange fluid, particularly for heat exchangers, and a liquid/gas heat exchanger, particularly for boilers, comprising a series of such tubular devices, have been devised, that are structurally simple, easy to use, and can be made using known systems and technologies.
In practice the materials employed, as well as the dimensions and the contingent shapes, may be any according to requirements and to the state of the art.
Where technical features mentioned in any claim are followed by reference signs, such reference signs have been inserted for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims

A tubular device (10) for the transit of a heat exchange fluid, particularly for heat exchangers, comprising a tube (11) that has a series of tube portions (11a, 11b, 11c, 11d) each with a cross-section having a profile that is formed by a plurality of lobes arranged in a substantially radial direction, each lobe defining a heat exchange channel (20,21,22) of said tube portion (11a, 11b, 11c, 11d), the cross-sections (12,12a9 of two successive tube portions (11a, 11b, 11c, 11d) being rotated relative to one another with respect to the axis of the tube by a certain angle, and the tubular device (10) comprising a removable rod-like flow redirection element (16) inserted in the axial space between blending portions (17,18,19) between two successive lobes of the cross-section of each tube portion (11a, 11b, 11c, 11d), and designed to redirect laterally the flow of heat exchange fluid introduced into said tube (11) toward the heat exchange channels (20,21, 22) of the tube portions (11a, 11b, 11c, 11d).
The device according to claim 1, characterized in that said rod-like redirection element (16) has at least one contoured grip end (23) for extraction from said tube (11).
The device according to the preceding claims, characterized in that said tube portions (11a, 11b, 11c, 11d) have each a cross-section that comprises three lobes (13,14,15) arranged substantially at 120 sexagesimal degrees with respect to each other.
The device according to the preceding claims, characterized in that said tube (111) has a rectilinear longitudinal extension.
The device according to the preceding claims 2, 3 and 4, characterized in that said tube portions (11a, 11b, 11c, 11d) alternate with other tube portions (11e, 11f, 11g) having a cross section that is substantially circular.
A liquid/gas heat exchanger (30), particularly for boilers, comprising a passage chamber (35) for a first heat exchange fluid and passage ducts (32) for a second heat exchange fluid, said passage chamber (35) being crossed by said passage ducts (32), characterized in that at least part of said passage ducts (32) are formed by a plurality of tubular devices (10) as set forth in any of the claims 1-5.
The heat exchanger according to claim 6, characterized in that it comprises a main external body (33), which contains an intake chamber (34) for said second heat exchange fluid being gas, which forms, together with said main body (33), said passage chamber (35) tor a first heat exchange fluid, said intake chamber (34) for the gas being surrounded by said passage ducts (32) which are formed by a series of heat exchange ducts (36) having a circular cross section and by a series of said tubular devices (10), the gas being conveyed from said intake chamber (34) toward said heat exchange ducts (36) having a circular cross section by means of a first redirection and exchange bottom (37), said gas that exits from said heat exchange ducts (36) having a circular cross section being conveyed to the tubular devices (10) by means of an annular chamber (38) that surrounds the inlet of said intake chamber for the gas (34).
The heat exchanger according to claim 7, characterized in that it is closed in an upper region by a flange (39) with a hole for the passage of gas and in a lower region by a second condensation collecting bottom (40) with an inlet (41) for a flue, at least one of said flange (39) and said bottom (40) being designed to be removed for extraction of the rod-like redirection elements (16) of the tubular devices (10) for cleaning the tubes (11) thereof.