CIRCULATION DUCT FOR CONVEYING A FLUID OF A HEAT EXCHANGER, AND HEAT EXCHANGER

Abstract

Circulation duct for conveying a fluid of a heat exchanger, and heat exchanger.

The duct (1) comprises two surfaces (s1, s2), each with a plurality of protruding elements (p) which project inside the duct (1), and are arranged adjacent to one another, forming a row which includes protruding elements (p) with a different form, and extends in a longitudinal direction according to the main direction of circulation Y of the fluid circulating, such that the flow of fluid encounters protruding elements (p) which are different sequentially both in space, according to this longitudinal direction, and in time, thus generating a plurality of disordered current lines (L).

The heat exchanger comprises circulation ducts for a fluid, at least one of which is formed according to the circulation duct of the present invention.

Claims

1. Circulation duct (1) for conveying a fluid of a heat exchanger in a main direction of circulation Y, which comprises two surfaces (s1, s2) of the heat exchanger substantially opposite one another, wherein each of the said surfaces (s1, s2) comprises a plurality of protruding elements which project inside the circulation duct (1), and are arranged adjacent to one another, forming at least one row which includes protruding elements (p) which are different, characterized in that the said row extends at least in a longitudinal direction according to the main direction of circulation Y, such that the flow of fluid encounters protruding elements (p) which are different sequentially both in space, according to this longitudinal direction, and in time, thus generating a plurality of disordered current lines (L).

2. Circulation duct according to claim 1, wherein the said protruding elements (p) have forms which are different from one another.

3. Circulation duct according to claim 1 or 2, wherein the said protruding elements (p) have orientations which are different from one another.

4. Circulation duct according to any one of the preceding claims, wherein the said protruding elements (p) have dimensions which are different from one another.

5. Circulation duct according to any one of the preceding claims, wherein the said row also includes protruding elements (p) with the same form and dimensions.

6. Circulation duct according to any one of the preceding claims, wherein the said row also includes protruding elements (p) with the same form but different dimensions and/or different orientations.

7. Circulation duct according to any one of the preceding claims, wherein the row comprises a series of protruding elements (p) which follow a pattern of repetition or a sequence of two or more different protruding elements (p) which are repeated twice or more along the row.

8. Circulation duct according to any one of the preceding claims, wherein the row includes at least two sub-rows of protruding elements (p) which extend longitudinally in the main direction of circulation Y.

9. Circulation duct according to claim 6, wherein at least one of these two or more sub-rows includes protruding elements (p) with different forms, different dimensions and/or a different orientation.

10. Circulation duct according to claim 8 or 9, wherein at least one of the sub-rows includes protruding elements (p) which invade spatially another one of the sub-rows, such that a portion of them is interposed between the protruding elements (p) of this other sub-row.

11. Circulation duct according to any one of the preceding claims, wherein the row includes protruding elements (p) which are arranged displaced transversely within the row, or one of these sub-rows, and are staggered in a direction transverse to the main direction of circulation Y.

12. Circulation duct according to any one of the preceding claims, wherein the row includes protruding elements (p) with at least two of the following forms, when seen in plan view, or a combination of these: circle, oval, rhombus, triangle, rectangle, and elongate elements which follow one or more straight and/or curved trajectories.

13. Circulation duct according to any one of the preceding claims, wherein the row includes protruding elements (p) with an elongate form which follow more than one straight and/or curved trajectory, and are formed by segments with different angles of orientation.

14. Circulation duct according to claim 12 or 13, wherein the row includes protruding elements (p) with a form which is a combination of two or more of the said forms.

15. Circulation duct according to any one of the preceding claims, wherein the ends and/or vertices of the forms of the protruding elements (p) are rounded.

16. Circulation duct according to any one of the preceding claims, wherein at least one of the protruding elements (p) of one (s1) of the said two surfaces (s1, s2) is superimposed by at least one protruding element (p) of the other surface (s2), the said superimposed protruding elements (p) being different in terms of at least dimensions.

17. Heat exchanger, in particular to cool exhaust gases of an engine, which comprises ducts for circulation of a fluid, characterized in that at least one circulation duct (1) is formed according to one of the preceding claims.

18. Heat exchanger according to claim 17, wherein the circulation ducts are formed by tubes inside which these exhaust gases circulate, and around which a coolant fluid circulates for heat exchange with the exhaust gases, and wherein at least the heat exchanger surfaces (s1, s2) which comprise protruding elements (p) do so as tube walls.

19. Heat exchanger according to claim 18, wherein the said tube walls are flat.

20. Heat exchanger according to claim 17, wherein the circulation ducts are formed by stacking of plates or discs, wherein at least the heat exchanger surfaces (s1, s2) which comprise protruding elements (p) do so as opposite walls of at least two of the said plates or discs.

Description

DETAILED DESCRIPTION OF SOME EMBODIMENTS

[0063] FIGS. 1 to 5 illustrate different embodiments of the circulation duct 1 proposed by the first aspect of the present invention, all of them having in common the fact that they relate to a circulation duct 1 for conveying a fluid of a heat exchanger in a main direction of circulation Y, which comprises two heat exchanger surfaces s1, s2 substantially opposite one another, wherein each of the surfaces s1, s2 comprises a plurality of protruding elements p which project inside the circulation duct 1, arranged adjacent to one another and forming at least one row which includes protruding elements p which are different in terms of their form and/or dimensions and/or orientation, and extend in a longitudinal direction according to the main direction of circulation Y.

[0064] In particular, in the embodiments illustrated by these FIGS. 1 to 5, the heat exchanger surfaces s1, s2 are the inner surfaces of flat main walls of a tube with a rectangular cross section which forms the circulation duct, although the same (or similar) distributions of protruding elements p illustrated can be applied to surfaces, whether flat or not, of another class of circulation ducts different from those illustrated.

[0065] The embodiments in FIGS. 1 to 5 are differentiated from one another by the different types with reference to the form and/or dimensions and/or orientation of protruding elements p included in them, as well as by the number and distribution of the elements along the row.

[0066] In particular, in the embodiment illustrated in FIGS. 1a, 1b, 1c and 1d, protruding elements are included with forms (in plan view) of a: rhombus, circle and elongate elements (similar to pegs) with different lengths and orientations which each follow a single straight trajectory. All of the forms illustrated have their ends and/or vertices rounded.

[0067] It can be seen from FIGS. 1a, 1b and 1d that the arrangement of protruding elements p not only follows a pattern according to a row in the direction Y, but that there are also sub-patterns grouped around some of the protruding elements according to different arrangements, in particular inclined groups of protruding elements p, the forms of which correspond to those of two pairs of circles with a rhombus in the middle arranged alternately (according to the row in the direction Y) with inclined groups of forms of two pairs of short pegs with a rhombus in the middle, separated by protruding elements p in the form of inclined long pegs.

[0068] As can be seen in FIG. 1d, as the protruding elements p project from the surface s1 onto those of the surface s2, silhouettes substantially in the form of an “X” are defined, both for each pair of elongate protruding elements (pegs), and for each inclined group of protruding elements.

[0069] As can be seen from FIG. 1c, the protruding elements p in question are made of respective stampings formed from the outer faces of the larger flat walls of the tubular duct 1, so that in reality FIG. 1a (and also FIGS. 2a, 3a, 4a and 5a) show, indicated as p, the depressions caused by these stampings which form the protrusions in the inner face of the duct 1. Any other method of configuring and arranging these protruding elements in the surfaces s1, s2 other than stamping is also possible, and is covered by the present invention.

[0070] In the embodiment in FIGS. 2a, 2b, 2c and 2d, protruding elements are included with forms (in plan view) of a rhombus and elongate elements (similar to pegs) with different lengths which each follow a single straight trajectory. All the forms illustrated have their ends and/or vertices rounded.

[0071] In this embodiment, the row of protruding elements includes three sub-rows, i.e. a central row formed by the forms in the shape of a rhombus (where, unlike the embodiment in FIG. 1, these are slightly offset spatially alternately), an upper row formed by a sequence of pairs of pegs with a different length and orientation, and a lower row similar to the upper one, wherein both respective end portions of the protruding elements p of the upper sub-row and the lower sub-row invade the space between each of the two rhombuses of the central sub-row.

[0072] As shown in FIG. 2d, as the protruding elements p project from the surface s1 onto those of the surface s2, in this case also silhouettes substantially in the form of an “X” are defined for each pair of elongate protruding elements (pegs).

[0073] In the embodiment in FIGS. 3a, 3b, 3c and 3d, protruding elements are included with forms (in plan view) of an oval, and elongate elements (similar to pegs) with different lengths each formed by straight segments with different angles of orientation.

[0074] In this embodiment, as can be seen in FIG. 3d, as the protruding elements p project from the surface s1 onto those of the surface s2, there is also definition of silhouettes substantially in the form of an “X” for each pair of elongate protruding elements (pegs).

[0075] The embodiment in FIGS. 4a, 4b, 4c and 4d differs from the one in FIGS. 3a, 3b, 3c and 3d only in that it does not include the protruding elements with a form (in plan view) of an oval.

[0076] FIGS. 5a, 5b and 5c illustrate another embodiment of the circulation duct proposed by the first aspect of the invention, which includes protruding elements only with elongate forms (similar to pegs), but with different dimensions and different orientations, grouped according to different sub-rows, including protruding elements p which invade spatially another one of the sub-rows, in particular the lower ends of the protruding elements p of the upper sub-row (according to the position illustrated in FIG. 5a) are interposed between the upper ends of the protruding elements p of the lower sub-row, and vice versa.

[0077] In this case, as shown in FIG. 5c, as the protruding elements p of the surface s1 project onto those of the surface s2, there is also definition of silhouettes substantially in the form of an “X”, for each pair of elongate protruding elements with the same dimensions.

[0078] The present inventors have carried out a series of digital simulations for a circulation duct as illustrated in FIGS. 1a, 1b, 1c and 1d, and the results of these are illustrated in FIGS. 6 to 9 graphically on a portion of the circulation duct 1 (although the simulations were carried out for the complete duct).

[0079] The simulations were carried out for a circulation duct with a tubular form and a rectangular cross section, with dimensions substantially 100 mm long, 14.5 mm high and 4.35 mm wide, with a wall thickness of 0.4 mm, and for protruding elements with a maximum height of substantially 1.3 mm (measured from the inner face of the wall from which they extend).

[0080] In particular, FIG. 6 shows the disordered current lines generated by the flow of fluid circulating through the duct when it encounters the protruding elements p along the duct. The current lines illustrated are more tortuous, and there are a larger number of them than those generated in the circulation ducts according to the prior art, meaning that the fluid emerges from the duct at a temperature lower than that obtained with the ducts according to the prior art (for a duct with the same dimensions).

[0081] FIGS. 7 and 8 represent in a scale of greys the values of the speed (m/s) in terms of magnitude (modulus) of the fluid circulating through the circulation duct, for three transverse regions spaced along the duct, and FIG. 9 represents the vectorial vorticity values (/s) for the same three transverse regions.

[0082] The results obtained show the validity of the arrangement along the duct of protruding elements with different forms, which applies not only to the embodiment for which the digital simulation results have been represented graphically (FIGS. 6 to 9), but also to the remaining embodiments illustrated (FIGS. 2 to 5), and in general to any embodiment which includes different protruding elements along the circulation duct.

[0083] Persons skilled in the art could introduce changes and modifications to the embodiments described without departing from the scope of the invention as defined in the appended claims.