The Influence of the Roughness of Surface on the Transmission of Heat, When Heated Gas flows across the Periphery of Heat Transmitting Tubes

Abstract

In studying the heat transmitting phenomena when heated gas flows across the periphery of heat transmitting tubes, the roughness of tube surface has been taken into consideration. In almost all expressions for the heat transmission hitherto publislaed, the roughness of the surface of beat transmitting tubes has been neglected, but the surface roughness of some degree actually exists in steam boilers and waste heat boilers ; for this fact it is necessary to ascertain the adaptability of these published formulae. In the present experiment, the heat transmission was first measured for tubes with smooth surfaces and the results were compared with those already published. Then, the measurement for heat transmission of tubes with rough surfaces was carried out under various conditions, and from these results the formulae for heat transmission different from those hitherto published have been determined.