Heat exchanger plate fin

A plate fin (12) for a plate fin and tube heat exchanger (10) used in an application in which the tubes run generally horizontally and in which condensation of a vapor entrained in the air flowing over and around the plate fins and tubes is likely to occur. The plate fin is configured to promote efficient and effective drainage of condensate that forms on the fin during heat exchanger operation. The fin is sinusoidally corrugated and has raised lance elements. There is a corrugated drainage channel section (32) between each vertical pair of adjacent fin collars (17). The drainage channel sections provide a path for condensate to run down the vertical plate fin to the bottom of the heat exchanger. By facilitating condensate drainage, the drainage channel sections serve to reduce the tendency of condensate to blanket the plate fins and tubes and interfere with air flow around the plate fins and the external surfaces, thus promoting heat transfer between the fluids flowing inside and outside the heat exchanger tubes.