Heat transfer tubes, including methods of fabrication and use thereof

A method of fabricating a heat transfer tube, the method comprising:

• (a) forming a plurality of fins on the outer surface of the tube, wherein a plurality of channels extend between adjacent fins;
• (b) notching at least some of the fins to a notch depth to form a plurality of notches;
• (c) flattening at least a first portion of a notched fin to approximately the notch depth, wherein a first nucleate boiling cavity is at least partially defined by a channel, a notch, and the first portion of the notched fin;
• and
• (d) bending over or further flattening at least a second portion of the notched fin to form a second nucleate boiling cavity in communication with the first nucleate boiling cavity.

An improved refrigerant evaporator, comprising:

• a. a shell;
• b. a refrigerant within the shell;
• and
• c. at least one heat transfer tube within the shell and in contact with the refrigerant, the heat transfer tube comprising:
• i. an outer surface comprising a plurality of fins and a plurality of channels extending between the fins, the fins being grooved to a notch depth to define notches, wherein each notched fin comprises a first portion flattened approximately to the notch depth and a second portion bent over or flattened;
• and
• ii. at least one dual cavity nucleate boiling pore comprising a first nucleate boiling cavity and a second nucleate boiling cavity, wherein the first nucleate boiling cavity is at least partially defined by at least a portion of a notch and of the first portion of a notched fin extending at least partially over a channel and wherein the second nucleate boiling cavity is at least partially defined by at least a portion of the second portion of the notched fin extending at least partially over the notch.