Heat exchanger fin

1. A heat exchanger fin comprising:

a base having a fin leading edge and a fin trailing edge and a substantially flat base plane extending between the fin leading edge and the fin trailing edge, wherein the fin is configured such that the fin leading edge is upstream of the fin trailing edge during use and wherein the base comprises a plurality of apertures each configured to receive a heat transfer tube;

a first louver coupled to the base at a first end and a second end of the first louver and comprising a leading edge and a trailing edge, wherein the first louver leading edge and the first louver trailing edge are spaced apart from the base plane a first distance, and wherein the first louver leading edge is convex and the first louver trailing edge is concave; and

a first winglet-type vortex generator coupled to the base and located between the fin leading edge and the first louver leading edge.

2. The heat exchanger fin of claim 1 comprising a second louver coupled to the base at a first end and a second end of the second louver and located between the fin trailing edge and the first louver trailing edge, the second louver comprising a leading edge and a trailing edge, wherein the second louver leading edge and the second louver trailing edge are spaced apart from the base plane a second distance that is greater than the first distance.

3. The heat exchanger fin of claim 1 comprising a second winglet-type vortex generator located between the fin leading edge and the first louver leading edge.

4. The heat exchanger fin of claim 3 , wherein the first winglet-type vortex generator and the second winglet-type vortex generator are coupled to the base along a longer side of the first and second winglet-type vortex generator.

5. The heat exchanger fin of claim 3 , wherein the first winglet-type vortex generator and the second winglet-type vortex generator each comprise a rectangular winglet that is perpendicular to the base plane.

6. The heat exchanger fin of claim 3 , wherein the first winglet-type vortex generator and the second winglet-type vortex generator extend along a respective ray of an acute angle and the rays extend toward the fin trailing edge.

7. The heat exchanger fin of claim 6 , wherein the acute angle is between 35 and 70 degrees.

8. The heat exchanger fin of claim 3 , wherein the first winglet type vortex generator and second winglet type vortex generator are each proximate an aperture that is the same shape as each respective vortex generator.

9. The heat exchanger fin of claim 3 , further comprising a pair of leading edge winglet-type vortex generators flanking each aperture of the plurality of apertures and located nearer the fin leading edge than the fin trailing edge.

10. The heat exchanger fin of claim 9 , wherein the pair of winglet-type vortex generators extend along a respective ray of a second acute angle and each of the respective rays extend toward the fin trailing edge.

11. The heat exchanger fin of claim 10 , wherein the second acute angle is between 35 and 75 degrees.

12. The heat exchanger fin of claim 9 , further comprising a pair of trailing edge winglet-type vortex generators flanking each aperture of the plurality of apertures and located nearer the fin trailing edge than the fin leading edge.

13. The heat exchanger fin of claim 12 , wherein the pair of trailing edge winglet-type vortex generators extend along a respective ray of a third acute angle and each of the respective rays extend toward the fin leading edge.

14. The heat exchanger fin of claim 13 , wherein the third acute angle is between 35 and 75 degrees.

15. The heat exchanger fin of claim 1 wherein each aperture of the plurality of apertures is oblong and configured so that a longitudinal axis of the aperture is parallel with an average direction of upstream to downstream flow of gas over the heat exchanger fin when implemented in a heat exchanger.

16. The heat exchanger fin of claim 1 , wherein each section of the fin leading edge that is between two apertures of the plurality of apertures is concave.

17. The heat exchanger fin of claim 1 , wherein each section of the fin leading edge that is upstream of an aperture of the plurality of apertures is convex and each section of the fin trailing edge that is downstream of an aperture of the plurality of apertures is concave.

18. The heat exchanger fin of claim 1 , wherein the heat exchanger fin is implemented as one of a plurality of parallel heat exchanger fins in a heat exchanger; and a plurality of heat transfer tubes are arranged substantially perpendicular to the plurality of heat exchanger fins, each heat transfer tube passing through an aperture in the plurality of heat exchanger fins.

19. The heat exchanger fin of claim 3 , wherein the first winglet-type vortex generator and the second winglet-type vortex generator are triangular.

20. The heat exchanger fin of claim 2 , wherein the second louver leading edge is convex and the second louver trailing edge is also convex.