Enhanced heat exchanger apparatus and method

1. A heat exchanger for heating, ventilation, air conditioning and refrigeration applications, the heat exchanger having

one or more tubes for carrying a first heat transfer fluid;

one or more fins, each having a first surface and a second surface in thermal communication with the tubes, at least some of the fins having

a plurality of annular fin collar bases that are located around the outside perimeters of the tubes, the bases extending from the first surface, at least some of the plurality of fin collar bases being provided with a plurality of bumps that extend at least partially convexly from the first surface for disturbing the heat transfer fluid.

2. The heat exchanger of claim 1 wherein the first heat transfer fluid comprises a refrigerant.

3. The heat exchanger of claim 1 wherein the second heat transfer fluid comprises air.

4. The heat exchanger of claim 1 wherein the plurality of bumps comprises four bumps.

5. The heat exchanger of claim 1 wherein at least some of the plurality of bumps have a shape that is selected from the group consisting of spherical, cone-shaped, pyramidal, and combinations thereof.

6. The heat exchanger of claim 5 wherein at least some of the bumps define one or more perforations in order to reduce the airside pressure drop across a fin's surface.

7. The heat exchanger of claim 1 wherein the one or more fins have a surface topography that is selected from the group consisting of a plane, a louver, a corrugation, a wave, and combinations thereof.

8. The heat exchanger of claim 1 , wherein at least some of the bumps are characterized by spherical arc length and a sector length, the arc length being about 1.3 times the sector length.

9. The heat exchanger of claim 1 , wherein at least some of the bumps have a shape that is selected from the group consisting of an ellipsoid and a faceted sphere.

10. The heat exchanger of claim 1 , wherein a plurality of bumps comprises four bumps, at least one being-oriented at 30 degrees from an incoming airflow direction through a tube center line.

11. The heat exchanger of claim 1 , wherein the plurality of bumps comprise two bumps that are spaced 180 degrees apart in relation to a tube center line.

12. The heat exchanger of claim 1 , wherein the first heat transfer fluid comprises a combustion gas.

13. The heat exchanger of claim 1 , wherein the second heat transfer fluid comprises water.

14. The heat exchanger of claim 13 , wherein the water is supplemented with an antifreeze.

15. A method for improving the efficiency of a fin-tube heat exchanger, comprising the steps of:

providing tubes for carrying a first heat transfer fluid;

fabricating one or more fins to accommodate the tubes;

forming a collar with an annular fin collar base in the one or more fins so that a predefined pattern of protrusions is formed in the fin collar base and extends at least partially convexly from one side of the fins

placing one or more of the fins in thermal communication with the tubes;

positioning the fin collar bases around the outside perimeters of at least some of the tubes, so that at least some of the protrusions disturb a second heat transfer fluid that passes over the fins and the tubes.

16. A heat exchanger for heating, ventilation, air conditioning and refrigeration applications, the heat exchanger having

one or more tubes for carrying a first heat transfer fluid;

one or more fins, each having a first surface and a second surface in thermal communication with the tubes, at least some of the fins having

a plurality of annular fin collar bases that are located around the outside perimeters of the tubes, the bases extending from the first surface, at least some of the plurality of fin collar bases being provided with a plurality of bumps that extend at least partially convexly from the second surface for disturbing the heat transfer fluid.