Heat transfer tubes, including methods of fabrication and use thereof

A method of fabricating a heat transferring tube for contacting a refrigerant and an inner surface for contacting a cool medium to be refreshed, the method comprising:

• (a) forming a plurality of radially outwardly extending fins on the outer surface of the tube;
• (b) forming a plurality of channels extending between adjacent fins in a first direction;
• (c) notching the fins to form a plurality of notches in a second direction, wherein at least one nucleate boiling pore is formed at the intersection of a channel and a notch;
• and
• (d) bending over or flattening the fins to provide a primary nucleate boiling cavity;
• (e) further bending over or flattening the fins to provide a secondary nucleate boiling cavity in communication with the primary nucleate boiling cavity.

An improved refrigerant evaporator, comprising:

• a shell;
• a refrigerant contained within said shell;
• and
• at least one heat transfer tube contained with said shell and submerged in said refrigerant, said heat transfer tube comprising:
• an outer surface, said outer surface comprising a plurality of radially outwardly extending helical fins with channels extending between adjacent fins, said fins being grooved to define notches;
• at least one nucleate boiling pore formed at the intersection of a notch and a channel;
• the fins being notched and bent such that adjacent fins form a channel extending between neighboring nucleate boiling pores, said pores thus defining a primary nucleate boiling cavity;
• and
• the fins further being bent over or flattened to define a secondary nucleate boiling cavity.