Integral finned tube for submerged boiling applications having special O.D. and/or I.D. enhancement

Claim 2

Heat transfer tubing modified for the enhancement of heat transfer to liquid in contact with the exterior surface thereof in submerged boiling applications, said tubing having a multiplicity of helically extending axially spaced fin convolutions extending around said tubing, said tubing having a continuous cylindrical wall, said fin convolutions having inner base portions extending generally radially outwardly from said wall and having outer portions inclined towards the side of the adjacent convolutions to define therewith partially enclosed spaces of substantially uniform cross-section extending around the tubing, the transverse dimensions of said fin convolutions measured from the base to the tips thereof being substantially uniform except for a plurality of uniformly circumferentially spaced recesses extending inwardly from the tips of said convolutions, said recesses in total occupying 10-30% of the circumferential extent of said fin convolutions, the outer tips of said convolutions being closely spaced from the sides of adjacent convolutions to define therewith effectively continuous circumferentially extending elongated restricted openings communicating with said spaces, said openings having an average substantially uniform width intermediate said recesses of not more than 0.007 inches, said recesses defining with the side walls of adjacent fin convolutions enlargements in said continuous openings having a width at least 50% greater than the average width of opening intermediate said enlargements.

Claim 3

Tubing as defined in claim 1 in which all of said enlargements are of substantially uniform shape and dimensions.

Claim 4

Tubing as defined in claim 1 in which said recesses extend inwardly from the tip of said fins 10-20% of the width of said fins measured from root to tip.

Claim 5

Tubing as defined in claim 1 in which said elongated restricted openings intermediate said enlargements have an average width of not more than 0.005 inches.

Claim 6

Tubing as defined in claim 4 in which said elongated restricted opening intermediate said enlargements have an average width of 0.001-0.005 inches.

Claim 7

Tubing as defined in claim 1 in which said tubing is provided with internal helically extending ribs which extend at a helix angle of less than 45° measured with respect to the tube axis.

Claim 8

Tubing as defined in claim 6 in which the helix angle of said fins is related to the helix angle of said ribs such that each rib convolution extends axially of the tube to cross a multiplicity of fin convolutions.

Claim 9

Tubing as defined in claim 6 in which the series of enlargements of said restricted openings occupy helical paths conforming to the internal helical ribs.

Claim 10

Heat transfer tubing modified for the enhancement of heat transfer to liquid in contact with the exterior surface thereof in submerged boiling applications, said tubing having a multiplicity of helically extending axially spaced fin convolutions formed up out of the material of the tubing to a height and at an axial spacing between adjacent convolutions which provide for inclining the tip of the fin convolutions into close proximity with the sides of adjacent fin convolutions, said tubing having a continuous cylindrical wall, said fin convolutions having base portions extending generally radially outwardly from said wall and having outer portions inclined toward the sides of the adjacent convolutions to define therewith helically extending substantially enclosed spaces of substantially uniform cross-section extending around the tubing, the transverse dimension of the fin convolutions measured from the base to the tip thereof being substantially uniform except for a plurality of circumferentially uniformly spaced recesses extending inwardly from the tips of said convolutions, said recesses in total occupying 10-30% of the circumferential extent of said fin convolutions, the tips of said convolutions being closely spaced from the sides of adjacent convolutions to define therewith effectively continuous circumferentially extending elongated restricted openings communicating with said spaces, said openings having an average width intermediate said recesses of 0.001-0.005 inches, said recesses defining with the side wall of adjacent convolutions enlargements in said continuous openings having a width at least 50% greater than the average width of opening intermediate said enlargements, said tubing having internal helically extending ribs having a much smaller helix angle measured with respect to the tube axis than said helical fin convolutions so that each internal rib crosses a multiplicity of external fin convolutions in a helical path, said recesses in the tips of said fin convolutions being located opposite the point where the fin convolutions cross the internal ribs.

Claim 11

Heat transfer tubing modified for the enhancement of heat transfer to liquid in contact with the exterior surface thereof in submerged boiling applications, said tubing having a multiplicity of helically extending axially spaced fin convolutions formed up out of the material of the tubing to a height and at an axial spacing between adjacent convolutions which provide for inclining the tip of the fin convolutions into close proximity with the sides of adjacent fin convolutions, said tubing having a continuous cylindrical wall, said fin convolutions having base portions extending generally radially outwardly from said wall and having outer portions inclined toward the sides of the adjacent convolutions to define therewith helically extending substantially enclosed spaces of substantially uniform cross-section extending around the tubing, the transverse dimension of the fin convolutions measured from the base to the tip thereof being substantially uniform except for a plurality of circumferentially uniformly spaced recesses extending inwardly from the tips of said convolutions, said recesses in total occupying 10-30% of the circumferential extent of said fin convolutions, the tips of said convolutions being closely spaced from the sides of adjacent convolutions to define therewith effectively continuous circumferentially extending elongated restricted openings communicating with said spaces, said openings having an average width intermediate said recesses of 0.001-0.005 inches, said recesses defining with the side wall of adjacent convolutions enlargements in said continuous openings having a width at least 50% greater than the average width of opening intermediate said enlargements, said tubing having internal helically extending ribs having a much smaller helix angle measured with respect to the tube axis than said helical fin convolutions so that each internal rib crosses a multiplicity of external fin convolutions in a helical path, said recesses in the tips of said fin convolutions being located opposite the point where the fin convolutions cross the internal ribs.