Fin-tube heat exchanger

Claim 1

A fin-tube heat exchanger comprising: a plurality of fins arranged parallel to one another at predetermined intervals, wherein an air flow passes between any two adjacent ones of said fins, said air flow having a direction that defines windward and leeward directions; a plurality of cylindrical fin collars formed on each of said fins in columns and rows at a predetermined column pitch and a predetermined row pitch; a plurality of heat transfer tubes extending through said fin collars on said fins and secured to said fin collars in intimate contact with said fin collars, respectively, wherein a fluid flows through each of said heat transfer tubes; a plurality of seat portions formed on each of said fins to encircle concentrically said fin collars, respectively; a plurality of straight protuberances of a generally angular cross-section formed on each of said fins between any two adjacent rows of said fin collars, each of said straight protuberances having a ridge and having a leeward side located in said leeward direction from said ridge; and a plurality of curved protuberances of a generally angular cross-section formed on each of said fins adjacent to said seat portions, wherein each of said seat portions corresponds to one of said curved protuberances in one-to-one correspondence, each of said curved protuberances including at least two sections, said at least two sections each having an arcuate ridge substantially equal in height to said ridges of said straight protuberances, said at least two sections comprising two sections disposed on opposite sides of a corresponding one of said seat portions and together extending at least partially around the corresponding one of said seat portions between two straight protuberances that are adjacent to said one of said seat portions.