Heat transfer surfaces with flanged apertures

1. A heat exchanger comprising:

a generally flat tube having first and second, spaced-apart walls;

a corrugated heat transfer surface located in said tube, the heat transfer surface including parallel, spaced-apart ridges with planar fins extending therebetween, alternating ridges being in contact respectively with the first and second walls;

the planar fins being formed with spaced-apart apertures having opposed peripheral edge portions; and

said opposed edge portions of each aperture including respective flanges that extend outwardly from a single side of the planar fin forming said aperture and terminate at a free end;

wherein the apertures are elongated, having a longitudinal axis extending in a direction transverse to the ridges; and

wherein the flanges associated with each aperture are disposed at an angle towards each other.

2. A heat exchanger as claimed in claim 1 wherein the planar fins are inclined with respect to the spaced-apart walls.

3. A heat exchanger as claimed in claim 1 wherein the planar fins are perpendicular to the spaced-apart walls.

4. A heat exchanger as claimed in claim 1 wherein the tube has a longitudinal axis, the ridges of the heat transfer surface being orientated perpendicular to said longitudinal axis.

5. A heat exchanger as claimed in claim 1 wherein the tube has a longitudinal axis, the ridges of the heat transfer surface being orientated parallel to said longitudinal axis.

6. A heat exchanger as claimed in claim 1 wherein the tube has respective end portions defining a fluid inlet and a fluid outlet for the heat exchanger.

7. A heat exchanger as claimed in claim 2 wherein all of said flanges extend generally in the same direction inside the tube.

8. A heat exchanger as claimed in claim 4 wherein the flanges associated with each aperture are continuous around the periphery of the aperture.

9. A heat exchanger as claimed in claim 4 wherein the flanges associated with each aperture are interrupted around the periphery of the aperture.

10. A heat exchanger as claimed in claim 9 wherein the flanges associated with each aperture are angled with respect to one another.

11. A heat exchanger comprising:

a generally flat tube having first and second, spaced-apart walls;

a corrugated heat transfer surface located in said tube, the heat transfer surface including parallel, spaced-apart ridges with planar fins extending therebetween, alternating ridges being in contact respectively with the first and second walls;

the planar fins being formed with spaced-apart apertures having opposed peripheral edge portions; and

said opposed edge portions of each aperture including respective flanges symmetrical to each other that extend outwardly from a single side of the planar fin forming said aperture and terminate at a free end;

wherein the flanges associated with each aperture are disposed at an angle towards each other; and

wherein the tube has a longitudinal axis and respective end portions defining a fluid inlet and a fluid outlet for the flow of a fluid through the heat exchanger, the ridges of the heat transfer surface being orientated perpendicular to said longitudinal axis such that the ridges of the heat transfer surface are oriented perpendicular to the direction of fluid flow.

12. A heat exchanger as claimed in claim 11 , wherein the apertures being elongated and have a longitudinal axis extending in a direction transverse to the ridges.

13. A heat exchanger as claimed in claim 11 , wherein the apertures formed in adjacent planar fins are aligned in the direction of the longitudinal axis of the tube.

14. A heat exchanger as claimed in claim 11 , wherein the apertures formed in adjacent planar fins are offset in the direction of the longitudinal axis of the tube.