POOL BOILING HEAT TRANSFER AND BUBBLE FORMATION OF NATURAL REFRIGERANTS ON HORIZONTAL TUBES

摘要

Experiments with Propane boiling on a horizontal copper tube (25.4 mm O.D.) in a wide pressure range have recently been started, in which local heat transfer along the circumference of the tube, the roughness topography of the tube surface, and bubble formation and motion are measured in order to study the convective and evaporative contributions to heat transfer in nucleate boiling. First results show that the local superheat of the tube wall can be measured very accurately along the whole circumference. They reflect the variation of convective effects with heat flux, pressure and azimuthal position. The data are compared with superheat and bubble formation for a finned tube with large diameter (90 mm).