Heat transfer pipe

Abstract

A heat transfer pipe having in an inner surface thereof a plurality of first internal grooves formed in parallel with each other and having a generally rectangular cross sectional shape, and a plurality of second internal grooves formed in parallel with each other and crossing the first internal grooves, the second internal grooves having a cross section which is generally in the shape of an inverted trapezoid, the heat transfer pipe further having the following portions defined by the above first and second internal grooves; tunnel portions formed in the portions where the first internal grooves cross the second internal grooves, the tunnel portions each having a space; discontinuous projecting portions formed at the portions crossing the portions between the first internal grooves, the discontinuous projecting portions being parallel to the second internal grooves and each having a generally triangular cross section; and including opening portions of the first internal grooves formed in the intermittent portions of the projecting portions.

Dependencies are inferred from the claim text.