Fin heat exchanger comprising improved louvres

Abstract

The invention relates to a heat exchanger comprising: at least one row of tubes (2), at least one fin (4) disposed transversely to said row of tubes (2), the tubes being connected to the fin (4) by clamping the tubes (2) in a collar (6) formed in the fin (4); and at least one row (10) of louvers (12), said row (10) being formed in the fin (4) and interposed between two tubes (2) in the row of tubes. With the fin (4) having a flat rectangular overall shape, the ratio between the number of louvers (12) and the width of the fin (4) is between 0.73 and 1.13.

Claims

1. A heat exchanger comprising: at least one row of tubes; fins disposed transversely to said row of tubes; the tubes being connected to the fins by clamping the tubes in a collar formed in the fins; and at least one row of louvers, said row being formed in the fins and interposed between two tubes in the row of tubes, wherein, with the fins having a flat rectangular overall shape, a ratio between a number of louvers and a width of the fin is between 0.73 and 1.13 louvers/mm; and a first fin and a second fin of the fins superposed together, the first fin comprising an oblong hole for a tube to pass through and at least one spacer for spacing apart from the second fin, wherein a length of each row of louvers of each of the first fin and the second fin is equal to a length of the oblong hole, and each row of louvers of each of the first fin and the second fin comprises a narrow end, extending between the oblong hole and the spacer, wherein the spacer is only at the narrow end, wherein each row of louvers of each of the first fin and the second fin comprises, and wherein the narrow ends of two consecutive rows of louvers are arranged in each case close to opposite edges of the fins.

2. The heat exchanger as claimed in claim 1, wherein the ratio between the number of louvers and the width of the fins is between 0.87 and 1 louvers/mm.

3. The heat exchanger as claimed in claim 1, wherein at least one spacer comprises two mutually parallel flat tabs.

4. The heat exchanger as claimed in claim 3, further comprising: an orientation vector directed substantially parallel to the tabs and substantially parallel to the fins and directed from the narrow end toward a second end referred to as a wide end; and a reference vector directed substantially transverse to the fins and directed from the narrow end toward the wide end, wherein an angle between the orientation vector and the reference vector is between 10 degrees and 20 degrees, and wherein the angle is negative when an air flow, which is initially flowing in the same direction as the reference vector, is diverted by the at least one spacer toward a tube closest to the at least one spacer, and is positive in the opposite case.

5. A heat exchanger comprising: at least one row of tubes, the tubes comprising an elongate shape overall and a substantially oblong cross section; a plurality of fins, each fin comprising a substantially flat rectangular overall shape, arranged substantially parallel to one another and substantially perpendicular to a longitudinal direction of the tubes, and connected to the at least one row of tubes; at least one row of louvers formed in each fin and interposed between two of the tubes; at least one spacer formed in each fin, each spacer comprising two mutually parallel flat tabs, wherein a ratio of a number of louvers in each fin to a width of each fin is greater than or equal to 0.73 louvers/mm and less than or equal to 1.13 louvers/mm, wherein the spacer is only at a narrow end of each row of louvers of each fin, wherein each row of louvers of fin comprises a wide end at an end opposite the narrow ends, wherein the wide end is wider than the narrow end, and wherein the narrow ends of two consecutive rows of louvers are arranged in each case close to opposite edges of the fins.

6. The heat exchanger as claimed in claim 5, wherein each tab is in the overall shape of a half-disk.

7. The heat exchanger as claimed in claim 5, wherein each fin comprises a plurality of oblong through-holes, each through-hole shaped to receive one tube, and wherein a length of the at least one row of louvers is equal to a length of the oblong through-hole.

8. A method of heat exchange comprising: flowing a first fluid through at least one row of tubes; flowing a second fluid substantially parallel to a plurality of fins, each fin connected to each tube in the at least one row of tubes and disposed substantially perpendicular to each tube, wherein each fin comprises a flat rectangular overall shape, wherein at least one row of louvers is formed in each fin and is interposed between two of the tubes, wherein a ratio of a number of louvers in each fin to a width of each fin is greater than or equal to 0.73 louvers/mm and less than or equal to 1.13 louvers/mm, wherein at least one spacer formed in each fin is only positioned at a narrow end of each row of louvers of each fin, wherein a wide end of each row of louvers of each fin is at an end opposite the narrow end, wherein the wide end is wider than the narrow end, and wherein the narrow ends of two consecutive rows of louvers are arranged in each case close to opposite edges of the fins.

9. The method of heat exchange as claimed in claim 8, wherein the first fluid is a heat transfer fluid and the second fluid is air.

Description

(1) The invention will be understood better from reading the following description, which is given solely by way of example and with reference to the drawings, in which:

(2) FIG. 1 is a perspective view of part of a fin and tubes of a heat exchanger according to a first embodiment of the invention;

(3) FIG. 2 is a top view of the fin from FIG. 1;

(4) FIG. 3 is a top view of a row of louvers of the heat exchanger from FIG. 1;

(5) FIG. 4 is a view similar to FIG. 3 showing a row of louvers of a heat exchanger according to a second embodiment;

(6) FIG. 5 is a schematic view of a heat exchanger according to the invention.

(7) FIG. 5 shows a mechanical heat exchanger 1 intended to equip a motor vehicle.

(8) The heat exchanger comprises a row of tubes 2 (shown in a truncated manner for reasons of clarity), through which a conventional heat transfer fluid is intended to flow, and superposed fins 4 (only one of which is shown for reasons of clarity) connected to these tubes 2.

(9) The tubes 2 are connected to the fins 4 by clamping the tubes in collars 6 formed in the fins 4. To this end, the fins 4 are provided with through-holes 8 for the tubes to pass through. These through-holes 8 have an oblong overall shape. In the following, they will be referred to as oblong holes 8.

(10) In the example described, the tubes 2 each have an elongate overall shape and have a substantially oblong cross section. The tubes 2 are arranged substantially parallel to one another, so as to form a single row.

(11) The fins 4 have a substantially flat rectangular overall shape and are arranged in the heat exchanger 1 in a manner substantially parallel to one another and perpendicular to the longitudinal directions of the tubes 2.

(12) The heat exchanger 1 is intended to be passed through from upstream to downstream by a flow of air, the fins 4 being intended to extend through this flow. Arrows F indicate the direction of travel of the flow.

(13) In order to increase the heat exchange between the flow F and the fins 4, the heat exchanger 1 also comprises rows 10 of louvers 12, which are formed in each fin 4 and are each interposed between two tubes 2.

(14) In the embodiments shown in FIGS. 1 to 4, the ratio between the number of louvers 12 and the width of the fin 4 is between 0.73 and 1.13. The ratio is expressed in louvers per mm.

(15) Preferably, this ratio is between 0.87 and 1, and is for example equal to 0.93. The latter choice constitutes a good compromise between performance of the heat exchanger 1 and pressure losses.

(16) Specifically, tests have for example shown that, with a ratio above 1.13, the gain in performance compared with a ratio of 0.93 is 0.4%, this not being advantageous with regard to the increase in external pressure losses, which is 3.4%.

(17) By contrast, other tests have revealed that, with a ratio less than 0.73, a satisfactory heat exchange power is not obtained since the latter decreases, compared with a ratio of 0.93, by 3.6%.

(18) With the aid of these tests, it was determined that a particularly satisfactory ratio was 0.93. Above 1.13, there is a gain in power, but the cost in terms of pressure losses is too high. By contrast, below 0.73, the power level is insufficient.

(19) The heat exchanger 1 also comprises spacers 13 between two superposed fins 4.

(20) More particularly, the spacers 13 comprise two flat, mutually parallel tabs 14.

(21) The spacers 13 are produced for example from a punched hole in the fin 4.

(22) In the example shown in the figures, the tabs 14 are each in the overall shape of a half-disk.

(23) In the embodiments shown in FIGS. 1 to 4, the length of the row 10 of louvers is equal to the length of the oblong through-holes 8 for the tubes 2 to pass through.

(24) Each row 10 of louvers of the fin 4 comprises an end 16 referred to as a narrow end, extending between the oblong hole 8 and the spacer 13.

(25) On account of the presence of the spacers 13, the louvers 18 at the narrow end 16 are less long than all the other louvers 12 in the row 10.

(26) For each row 10 of louvers, the number of narrow-end louvers 18 extending between the hole 8 and the spacers 14 is an integer.

(27) For example, as can be seen in FIG. 2, exactly three narrow-end louvers 18 extend between an oblong hole 8 and a spacer 13.

(28) Furthermore, each row 10 of louvers 10 of the fin 4 comprises an end 20 referred to as a wide end, in which the louvers 22 are longer than those at the narrow end 16.

(29) Thus, in the example shown, the fin 4 is provided with a single spacer 13 between two consecutive tubes 2 in the row of tubes 2, and not two between two consecutive tubes 2 as in the prior art.

(30) The narrow ends 16 of two consecutive rows 10 of louvers are more particularly arranged in each case close to opposite edges 24 of the fin 4, as can be seen in FIGS. 1 and 2.

(31) As illustrated in FIGS. 3 and 4, an orientation vector O is defined as being a vector, the direction of which is a direction substantially parallel to a tab 14 and the fin 4 and the sense of which is the sense running from the narrow end 16 toward the wide end 17.

(32) Likewise, a reference vector R is defined as being a vector, the direction of which is the direction transverse to the fin 4 and the sense of which is the sense running from the narrow end 16 toward the wide end 17.

(33) In all the embodiments shown in the figures, the angle between the orientation vector O and the reference vector R is between 10 degrees and 20 degrees.

(34) In the following text, the angle will be considered to become negative when the air flow F, which is oriented in the same sense as the reference vector, tends to deviate from the adjacent row 10 of louvers, that is to say toward the tube 2 closest to the spacer 13 in the examples shown.

(35) In particular, in the first embodiment of the invention that is illustrated in FIGS. 1 to 3, this angle is zero. Thus, the tabs 14 of the spacers 13 are substantially parallel to the transverse direction of the fin 4.

(36) By contrast, the angle becomes positive when the air flow F redirected by the spacers 13 tends to be directed further toward the adjacent row 10 of louvers, as is the case in FIG. 4, which illustrates a second embodiment of the invention.

(37) In this second embodiment, the angle between the orientation vector O and the reference vector R is, in accordance with the convention defined above, equal to 15 degrees.

(38) This final configuration provides good results with regard to the performance of the heat exchanger 1.

(39) The invention is not limited to the embodiments presented, and further embodiments will be clearly apparent to a person skilled in the art.

(40) In particular, a combination of the different embodiments can also be envisioned in order to obtain the desired effects.