Patent ID: 8448698

Claim:
A tube for a heat exchanger, the tube extending in a longitudinal direction and having a flat shape in cross section along a width direction substantially perpendicular to the longitudinal direction, the tube comprising: a first plate portion; and a second plate portion located opposite to the first plate portion, wherein the first plate portion and the second plate portion each include base plate portions which are bonded to each other and a plurality of protruding portions having at least a first protruding portion and a second protruding portion, the plurality of protruding portions protruding from the bonded portion of the base plate portions toward an outside of the tube, wherein a protruding dimension of the first protruding portion from the base plate portion is larger than a protruding dimension of the second protruding portion from the base plate portion, wherein the base plate portion and the plurality of protruding portions are configured to respectively extend in the longitudinal direction, wherein the second plate portion and the plurality of protruding portions of the first plate portion are configured to have a clearance therebetween defining an internal fluid passage in which an internal fluid flows in the longitudinal direction, wherein the second protruding portion and the base plate portion are configured to define an external fluid passage in which an external fluid flows in the width direction; and wherein the bonded portion of the base plate portions of the first and second plate portions extends continuously in the longitudinal direction between adjacent first protruding portions in the width direction to separate the adjacent first protruding portions from each other in the width direction.