Researches on New Heat Transmitting Tubes (1st Report)

Abstract

We have obtained the heat transmitting tubes of a new type which are easy to make and superior in point or heat transmission. These new tubes are the ones equipped with one or two plane axial fins perpendicularly on the outer surface of circular tubes. Our researches were carried out measuring the heat quantity absorbed in water, flowing through the tubes which were held perpendicularly to the flow of air of 80°C. The main results of our researches are as follows : (1) The characteristic of the tube having two fins, stretching in axial direction on its front surface is influenced by air velocity, the angle 2θ between the two fins, holding at the center of tube and fin height. Among these factors the second must be attended especially. The tubes having the fins of proper angle (2θ=20°∼60°) and proper height on its front surface are most useful. (2) The tube having an axial fin of larger height on its front surface against the air flow is also useful.