T-finned tube or low fin tube is composed of the light pipe through the rolling process forming an efficient heat transfer tubes. Its structure is characterized by an outer surface of the tube to form a series of spiral ring T-tunnel. When the heat medium outside the tube to form a series of cell nuclei in the tunnel, since the chamber is surrounded by a tunnel heated state, the rapid expansion of cell nuclei filled cavity, continuously heated rapidly increases the inner pressure of the bubble, the bubble from the tube surface to promote slit the rapid discharge. With larger bubbles ejected erosion force and a certain partial vacuum, so that the surrounding liquid into a lower temperature T type tunnels, forming continuous boiling. This boiling manner in unit time per unit surface area of the heat away much larger than the light pipe, so this tube has a high boiling heat transfer capability. As long as the shell side of the medium is relatively clean, no solids, no gum, may be employed as a T-finned tube heat exchanger components, forming a T-shaped fin tube type heat pipe heat exchanger efficiency, to improve the shell-side boiling heat transfer.