Patent Grant
10948244
This application is a National Stage Application of International Patent Application No. PCT/IB2015/058784, filed 13 Nov. 2015, which claims benefit of Serial No. VR2014A000284, filed 14 Nov. 2014 in Italy and which applications are incorporated herein by reference. To the extent appropriate, a claim of priority is made to each of the above disclosed applications.
The present invention relates to a fin for a finned pack for heat exchangers, a finned pack and a heat exchanger including the latter.
Heat exchangers are used in many applications for heating or cooling a first fluid, by placing it in heat exchange communication with a second fluid. This is usually obtained by conveying a first fluid into tubes which cross passage zones of the second fluid.
Different types of heat exchangers have been proposed, including those so-called “with finned pack”, which comprise a plurality of packed fins; such fins comprise plate-like elements having a plurality of holes in which tubes are engaged for conveying a first fluid, while a second fluid is sent between the fins for the heat exchange with the first fluid.
The fins can have substantially smooth or corrugated geometry, in particular if it is desired to increase the surface area or the efficiency of the heat exchange.
Nevertheless, the heat exchange efficiency in the exchangers according to the state of the prior art is often limited and therefore it is necessary to improve the performances obtainable in heat exchangers.
One object of the present invention is to provide a new fin of a finned pack for heat exchangers as well as a new finned pack and a new heat exchanger obtainable starting from one such fin.
Another object of the present invention is to provide a new fin of a finned pack that is able to ensure an improved heat exchange efficiency.
Another object of the present invention is to provide a fin as stated above which allows affecting the external surface of the tubes of the exchanger in a uniform manner.
In accordance with one aspect of the invention, a fin is provided according to claim 1.
In accordance with one aspect of the invention, a finned pack is provided according to claim 13.
In accordance with one aspect of the invention, a heat exchanger is provided according to claim 15.
The dependent claims refer to preferred and advantageous embodiments of the invention.
Other characteristics and advantages of the invention will be clearer from the description of embodiments of fins, of a finned pack and of heat exchangers, illustrated by way of example in the enclosed drawings in which:
In the set of drawings, equivalent parts or components are marked by the same reference numbers.
With reference to
The plate 2 has an edge 5 as well as two main faces 6 each intended to be licked or affected by a second heat exchange fluid, such as air, in a crossing direction A-A from an inlet portion 5a to an outlet portion 5b of the edge 5 of the plate 2. For such purpose, the facing main faces 6 of two adjacent and successive fins 1 delimit, between them, a respective area of passage or crossing of a second fluid which hits respective sections of the tubes 4 engaged in such fins.
The edge 5 actually constitutes an external connection face between the two main faces 6 and the same can be provided with two main sides main sides 5a, 5b, e.g. parallel, which are connected like a bridge by means of secondary or smaller sides 5c, 5d, if desired these too parallel and orthogonal to the main sides. The main sides 5a, 5b actually respectively constitute the inlet portion 5a and the outlet portion 5b.
The holes 3 are delimited by a respective inner delimiting wall 7 of the plate 2, which includes a first portion 7a facing towards the inlet portion 5a and a second portion 7b facing towards the outlet portion 5b. The delimiting wall 7 of the holes 3 can be substantially cylindrical.
The fin 1 then comprises one or more confinement units 8, 9 for the flow of the second fluid, each confinement unit being arranged around a respective section of the second portion 7b of the delimiting wall 7 of a hole 3 of the plurality of holes so as to obtain or define a partially surrounded hole or better yet a respective partially surrounded hole 3. Preferably, a confinement unit 8, 9 is provided for each hole 3 of the fin 1 or in any case for most of the holes 3 of the fin itself. Still more preferably, the confinement units do not affect or better yet are not arranged around the first portion 7a of the respective delimiting wall 7.
More particularly, at least one confinement unit comprises two first baffles 8, 9 or two through housing recesses for housing second baffles arranged one opposite the other with respect to a respective partially surrounded hole 3, as well as each surrounding and spaced from a respective section of the second portion 7b of the delimiting wall 7 of the partially surrounded hole 3, so as to confine, during use, on the plate 2 a first flow zone FZ1 of the second fluid between each baffle 8 or recess and a respective section of the second portion 7b of the delimiting wall 7.
The configuration that will be described with reference to the first baffles is in substance also applied to the second baffles and vice versa, if it is considered that, once a finned pack is assembled, such components (first or second baffles) are intended to carry out the same task in substantially the same manner.
The first flow zone FZ1 comprises an introduction mouth for the second fluid, delimited between the plate 2, the first baffles 8, 9 and a part of the delimiting wall 7 as well as a delivery mouth for the second fluid leading into an area downstream of the respective hole 3, i.e. an area subsequent to the hole 3 in the sense of the crossing direction A-A. The first flow zone FZ1 or better yet the walls thereof are fluid-tight so as to prevent leaks or exits of liquid between the introduction mouth and the delivery mouth.
With regard to the introduction mouth, this is preferably delimited between the plate 2, a first end 8a, 9a of the first baffles 8, 9 or recesses and a part of the second portion 7b of the delimiting wall 7.
Advantageously, the first baffles 8 or the recesses can also be extended beyond a respective hole, i.e. have end sections closer to the outlet portion 5b with respect to a respective hole and hence define a second flow zone FZ2, which actually constitutes a continuation of the first flow zone FZ1, such second flow zone FZ2 being delimited between end sections of the first baffles 8, 9 or recesses.
In such a manner, a confinement of the second fluid is obtained downstream of the partially surrounded hole 3, with the expression confinement “downstream” indicating a confinement of the second fluid in the area or zone of the fin 1 that such fluid crosses after having affected the hole 3 or better yet hit the tube 4 engaged in the hole 3.
The second flow zone FZ2 has a feeding mouth corresponding to the delivery mouth of the first flow zone FZ1 as well as a mouth for discharging the second fluid towards subsequent holes or parts of the fin with reference to the crossing direction A-A. The second flow zone FZ2 or better yet the walls thereof are fluid-tight so as to prevent leaks or exits of fluid between the delivery mouth and the discharge mouth.
Advantageously, the holes 3 are each extended around a respective axis of symmetry x-x, with the axes of symmetry x-x of the holes 3 being substantially parallel to each other, while the first baffles 8, 9 or the housing recesses for second baffles of a confinement unit 8, 9 are substantially symmetrical to one another with respect to a plane passing through the crossing direction A-A from an inlet portion 5a to an outlet portion 5b of the edge 5 and (passing) through the axis of symmetry x-x of the respective at least partially surrounded hole 3.
In addition, the delimiting wall 7 can have a collar section 7c projecting upward with respect to one of the main faces 6, while the first baffles 8, 9 of the partially surrounded hole 3 with collar section 7c are extended around at least one part of the collar section 7c distal from the inlet portion 5a and facing towards the outlet portion 5b, the first or second baffles having height or thickness equal to or less than the collar section 7c. The collar section 7c of the delimiting walls 7 mainly carries out the function of spacer between two adjacent and successive fins 1 of a finned pack.
Advantageously, the first baffles 8, 9 or the recesses of one or more confinement units 8, 9 have a first end 8a, 9a proximal to the inlet portion 5a as well as a second end 8b, 9b distal from the inlet portion 5a of the plate 2. The proximal ends 8a, 9a of the first baffles 8, 9 or housing recesses are at a first distance D1 from each other, while the distal ends 8b, 9b of the first baffles 8, 9 or recesses of a confinement unit are at a second distance D2 from each other which is advantageously less than the first distance D1, such that the first baffles or recesses delimit between them a first area substantially tapered going away from the inlet portion 5a. In addition, in such case, preferably there are no intermediate sections of the first baffles 8, 9 with distance between them greater than the first distance D1 between the proximal ends 8a, 9a.
If desired, the distance between the first baffles 8 could initially decrease going away from the inlet portion 5a and then, once a minimum value is attained at an intermediate portion of the first baffles, once again increase up to the second end 8b, 9b, in which case the distance between the first baffles at the respective second end 8b, 9b could also be greater than the distance D1. In such case, the area between the proximal ends and the intermediate portions of the first baffles or of the housing recesses is substantially tapered in the direction going away from the inlet portion 5a, while a second area would be provided between the intermediate portions and the second ends of the first baffles or of the housing recesses with an initial section with decreasing cross section and then an end section with increasing cross section going away from the inlet portion 5a.
In addition, the (first and/or second) baffles can have a flat or slightly curved laminar body with position, preferably, orthogonal or projecting upward with respect to the plate 2. In addition, the (first and/or second) baffles are, preferably, fluid-tight (if desired they are not perforated) so as to prevent the passage of the second fluid through them. In addition, each baffle is preferably formed in a single piece.
If desired, the first baffles comprise a drawn portion, or sheared and bent portion of the plate 2, i.e. the baffles 8, 9 are obtained by means of drawing of the plate 2 itself. If a collar section 7c is provided, then both the first baffles 8, 9 and the collar sections 7c are obtained by means of drawing of a respective plate 2.
Alternatively, the (first and/or second) baffles 8, 9 can comprise a laminar body with position substantially orthogonal to the plate 2; such laminar body can be in part or separately formed with respect to the plate 2 and connected, if desired via welding or fitting, with the plate 2. In addition, second baffles could be separately formed, each inserted in a respective housing recess of a confinement unit 8, 9; such baffles could have configuration and, during use, arrangement substantially corresponding to the baffles 8, 9.
The height or thickness of the (first and/or second) baffles 8, 9 could vary from about 0.1 mm to about 12 mm.
In addition, in order to define the position of the baffles, one or more holes 3 with substantially circular cross section, and the first portion 7a and the second portion 7b with substantially semi-circular cross section, will be considered.
The following will also be defined in a plane transverse or orthogonal to the axis x-x: first straight line L1, that defined by the crossing direction A-A and passing through the axis of symmetry x-x, and second straight line L2, that orthogonal to the first straight line L1 and always passing through the axis of symmetry x-x.
Quadrants will then be defined, which are always delimited in a plane transverse or orthogonal to the axis x-x, between the first L1 and the second L2 straight line and, more particularly, first Q1 and second Q2 quadrant are those defined between first L1 and second L2 straight line and enclosing a respective half or part of the first portion 7a (or within which such portion lies), and third Q3 and fourth Q4 quadrant are those defined between first L1 and second L2 straight line and enclosing a respective half or part of the second portion 7b.
On the basis of the considerations and definitions provided up to now, the baffles 8, 9 or the housing recesses can then each be advantageously positioned with one in the third quadrant Q3 and the other in the fourth quadrant Q4, and still more advantageously, each in a circular-sector shaped area defined by a straight line coming out from the axis x-x and tilted at a tilt angle IA1 between 10° and 80° with respect to the second straight line L2.
In addition, each baffle 8, 9 or recess can be at a third distance D3 from the delimiting wall 7 and more particularly from a section of the second portion 7b of the delimiting wall 7 between about 1 mm and about 10 mm.
A fin like that illustrated in
The baffles 8, 9 or in any case the baffles engageable in the housing recesses in fact determine, as can be ascertained, a conveying or confinement of the second fluid on the second portion 7b of the respective delimiting wall 7 and then towards the respective tube 4, which ensures that each portion of the delimiting wall 7 and hence of the respective tube is affected by the second fluid.
With reference now to the embodiment illustrated in
The baffles 81, 91, in addition to reducing the “dead zone”, increase the surface heat exchange coefficient around the zones of the tubes 4 with high temperature.
Such baffles 81, 91 could be metal sections obtained via extrusion, molding or shaping and mechanically inserted in the fins of a finned pack or better yet in the plates thereof, e.g. with forced insertion or insertion via interference or by means of the use of welding materials or alloys that facilitate the adhesion and transmission of the heat.
On the basis of the considerations and definitions provided above, the first section 81c, 91c of the baffles 81, 91 or respective housing recesses are each advantageously positioned with one in the third quadrant Q3 and the other in the fourth quadrant Q4, and still more advantageously, each in a circular-sector shaped area defined by a straight line coming out from the axis x-x and tilted at a tilt angle IA2 between 0° and 80° with respect to the second straight line L2.
The first section 81c, 91c can also be substantially straight or curved or, if desired, with multiple sections that are slightly tilted from one other, but each tilted at an angle between 0° and 80° with respect to the second straight line L2.
In addition, each baffle 81, 91 or recess or better yet the first section 81c, 91c of each baffle 81, 91 can be at a fourth minimum distance D4 from the delimiting wall 7 and more particularly from a part of the second portion 7b of the delimiting wall 7 between about 1 mm and about 15 mm.
The second section 81d, 91d can instead have extension less than or equal to the distance between two successive rows of holes 3, wherein by row of holes 3 or tubes 4 it is intended the set of holes of a fin or of the tubes engaged therein at a same distance from the inlet portion 5a and by successive rows it is intended rows arranged one after the other in the sense of the crossing direction A-A and that thus, during use, are affected by the flow of the second fluid one after the other.
For such purpose, a fin according to the present invention preferably comprises two or more rows of holes 3 offset with respect to one another with respect to the crossing direction A-A, such that each row of holes 3 is at a different distance from the inlet portion 5a with respect to the other rows of holes 3.
The thickness of a baffle, as now described, can vary between 0.1 and 5 mm.
With reference now to the embodiment illustrated in
According to such embodiment, the first section 82c, 92c is substantially rectilinear, while the second section 82d, 92d has a configuration that is curved or with two sections slightly tilted with respect to one other and defining, with the reinforcement section 82e, 92e, an opening or first opening 11, e.g. with substantially triangular section, if desired extended substantially parallel to the axis of symmetry x-x of the respective hole 3.
Such opening 11 is typically used for the passage through the respective baffle, i.e. in direction substantially parallel to the axis x-x, of a third fluid such to increase the exchange efficiency of the exchanger or for complementary functions such as to the melting of frost in the case of operation of the exchanger as air heater. In addition, the opening 11 could also be fed with the first fluid.
It should also be observed that the baffles 8, 9 and 81, 91, previously described, could have an opening 11, so as to have a substantially tubular structure with through opening extended substantially parallel to the axis of symmetry x-x of the respective hole 3. With regard to the baffles 81, 91, these could have the first 81c, 91c and/or the second section 81d, 91d substantially tubular.
The first opening 11 of one or more baffles could have a section with any suitable shape. e.g. circular, elliptical, rectangular or polygonal.
In addition, two or more openings or micro-channels 11 could also be provided in each baffle.
Clearly, an opening 11 as indicated above can in particular be present if the baffles comprise metal sections obtained—via extrusion, molding or shaping—separately with respect to the plates 2 and hence mechanically inserted in the plates 2 themselves.
Due to such baffles 82, 92, a fin according to the embodiment of the
The baffles 82, 92 can comprise profiles or sections, e.g. metal, obtained via extrusion or shaping, if desired with longitudinal welding, which can be mechanically inserted by means of interference or fixed to the fins or better yet to the plates thereof with high-conductivity welding materials.
Each baffle 82, 92 or recess can be at a fifth distance D5 from the delimiting wall 7 and more particularly from a section of the second portion 7b of the delimiting wall 7 between about 1 mm and about 15 mm.
Each baffle 82, 92 in a respective third Q3 or fourth Q4 quadrant then has tilt angle IA3 between 0° and 50° with respect to the straight line L2.
The first flow zone FZ1 between each baffle 82, 92 and a respective section of the second portion 7b can vary between 5 mm2 and the value of the passage section of the tube for the passage of the primary fluid or first fluid.
The thickness of a baffle 82, 92, as now described, can also vary between 0.1 and 12 mm.
With reference now in particular to the geometry and distribution of the holes in a fin according to the present invention, the following will be defined:
Based on such definitions, a fin according to the present invention could have A×B between 10×10 and 100×100.
Hereinbelow, the table reports several possible geometries and sizes for a fin according to the present invention as well as for the tubes to be engaged therein.
For such purpose, by C and D it is intended the distances between the holes at the edges of the plate 2 and the sides of the edge of the respective plate 2. The above-reported values for C and D are naturally merely given for exemplifying purposes.
In addition, a fin could also have A×B equal to 48×41.75 or 50×40 with tubes of diameter equal to 12 mm or 16 mm, or A×B equal to 20×20 with tubes having 5 mm diameter.
With regard instead to the definition of “offset” of the tubes or holes: it is intended that the holes of adjacent and successive rows are offset with reference to the crossing direction A-A, while the definition “squared pitch” indicates that the holes or the tubes of adjacent and successive rows are aligned, always with reference to the crossing direction A-A. For such purpose, in a fin according to the present invention, each row of holes 3 comprises at least one hole aligned along the crossing direction A-A with a respective hole of the other rows of holes and/or at least one hole offset with respect to the holes 3 of the other rows of holes 3, always with reference to the crossing direction A-A.
In substance, a fin according to the present invention comprises two or more lines or rows of holes 3, i.e. groups of holes substantially at a same distance from the inlet portion 5a. In addition, the holes of adjacent and successive rows can be offset or aligned with reference to the crossing direction A-A.
In addition, in a fin according to the present invention, holes for the positioning of heating elements could also be provided (or not provided), e.g. through holes with diameter equal to 9.5 mm.
The thickness of a fin according to the present invention can vary between 0.1 mm and 0.4 mm.
The pitch or distance between the fins can vary between 1.2 and 12 mm.
A fin 1 according to the present invention can then have a smooth surface or so-called “w_vaffle”, “pyramid” or “turbulent” surface. Such fin can also have a so-called “jagged” or “smooth” edge.
The fin 1 could be made of any suitable material, e.g. aluminum, aluminum alloys, copper, copper alloys, steel, stainless steel in different alloys, such as AISI 304, AISI 316, etc.
In addition, the fin 1 could be finished with surface treatments, e.g. varnishing, cataphoresis or other treatments.
With reference now to
The finned pack 10 then comprises an introduction opening 10a for a second fluid between pairs of fins of the plurality of fins, and an outlet opening 10b for the second fluid between the pairs of fins. The fins 1 have their inlet portions 5a at the introduction opening 10a and their outlet portions 5b at the outlet opening 5b.
A plurality of tubes 4 inserted in the aligned through holes of the plurality of fins 1 are also provided in the exchanger, the tubes 4 having a first sector 4a facing towards the inlet opening 10a as well as a second sector 4b facing towards the outlet opening 10b, the fins 1 having the confinement unit or units 8, 9 around a portion of a second sector of a respective tube 4.
As already stated above, the facing main faces 6 of two adjacent and successive fins 1 delimit, between them, a respective area of passage or crossing of a second fluid which hits respective sections of the tubes 4 engaged in such fins, and such tubes 4 along with the baffles are extended through the passage areas so as to be hit by the flow of the second fluid.
The finned pack 10 can then comprise an upper tile 10c, a lower tile 10d and, additionally, at one side manifolds 10f for the tubes 4 and on the other side small forks 10g for sending the first fluid between two tubes 4.
If desired, each fin has at least one confinement unit with two through recesses for positioning baffles and each through recess of each confinement unit is aligned with a respective recess of the other fins. In such case, the finned pack also comprises two baffles for each confinement unit, each inserted in a respective series of aligned through recesses of the fins 1, preferably of all the fins of the finned pack 10.
According to such variant, the baffles or bars could constitute a load-bearing mechanical element of the finned pack 10. This is particularly applied to the embodiments illustrated in
In addition, if the baffles delimit an opening 11, the finned pack 10 or better yet the respective heat exchanger could comprise means for feeding a third fluid or the first fluid into the opening 11 of one or more baffles 8, 9, 81, 91, 82, 92. In such case, at the ends of the baffles 8, 9, 81, 91, 82, 92, pipe unions could be provided, along with tubular connection elements between the end of one baffle and a respective end of another baffle. In substance, in such case a feed circuit could be provided for a third fluid constituted by the baffles connected together in series and/or in parallel. Alternatively, the baffles could be connected in series and/or in parallel with each other and with the tubes 4, such that baffles and tubes would be fed with the first fluid.
The tubes 4 of a finned pack 10 could for example be made of copper and alloys thereof, stainless steel and alloys thereof, iron and alloys thereof, aluminum and alloys thereof or other suitable materials.
The tubes could also have an internal wall that is smooth, or grooved, e.g. tilted groove, helical grooved or grooved with crossed spirals.
The tubes could then have a diameter between 4 and 35 mm, advantageously between 5 and 22 mm, preferably 5 mm, 6.35 mm, 7.2 mm, 7.9 mm, 9.5 mm, 12 mm, 14, 16 mm or 22 mm.
The thickness of the tubes instead preferably varies between 0.15 and 1.50 mm, and, still more preferably, it is equal to 0.25 mm, 0.28 mm, 0.32 mm, 0.35 mm, 0.4 mm or 0.5 mm.
A finned pack according to the present invention can be integrated or installed in:
As will be understood, a fin and a finned pack according to the present invention allow conveying the second fluid around the entire surface of the holes and hence of the tubes of the fin, also in the zone of each tube that faces towards the outlet portion.
For such purpose, in fact, the applicants of the present patent application have been able to establish that with fins and finned packs according to the state of the art, the second fluid correctly and uniformly hits and affects the part of the tubes facing towards the inlet portion of the fins, but in the zone between the tubes of one row and the tubes of a subsequent row, the second fluid is “detached” from the external surface of the tubes, hence not affecting that part of the tubes facing towards the outlet portion of the fins. Naturally, this involves a considerable reduction of the heat exchange efficiency, since most of the external face of the tubes crossed by the first fluid is not in heat exchange contact with the second fluid.
Due to the confinement units of a fin according to the present invention and of a respective finned pack, the second fluid is instead in fact guided and maintained next to the tubes, even in the zone downstream thereof, so as to affect the second fluid and place it in heat exchange with the entire external face of the tubes, considerably improving the obtainable heat exchange efficiency.
Modifications and variants of the invention are possible within the protective scope defined by the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| VR2014A0284 | Nov 2014 | IT | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2015/058784 | 11/13/2015 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2016/075666 | 5/19/2016 | WO | A |
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| 4984626 | Esformes | Jan 1991 | A |
| 6578627 | Liu et al. | Jun 2003 | B1 |
| 8381802 | Nishino | Feb 2013 | B2 |
| 8613307 | Kim | Dec 2013 | B2 |
| 20040194936 | Torii | Oct 2004 | A1 |
| 20040200608 | Baldassarre | Oct 2004 | A1 |
| Number | Date | Country |
|---|---|---|
| 102 135 388 | Jul 2011 | CN |
| 496733 | Apr 1930 | DE |
| 2 072 939 | Jun 2009 | EP |
| 61110889 | May 1986 | JP |
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| 2011082922 | Jul 2011 | WO |
| 2014104576 | Jul 2014 | WO |
| Entry |
|---|
| International Search Report and Written Opinion from corresponding International Patent Application No. PCT/IB2015/058784, dated Feb. 19, 2016. |
| Number | Date | Country | |
|---|---|---|---|
| 20170321969 A1 | Nov 2017 | US |
