Investigation of Nonstationary Heat Transfer in Boiling of Freon 113 on Dimpled Spherical and Cylindrical Surfaces under the Conditions of Free Convection

摘要

An experimental investigation of nonstationary heat transfer in boiling of Freon 113 on dimpled spherical and vertical cylindrical surfaces with free convection in a wide range of temperature differences is carried out. The influence of dimples on an increase in the heat transfer rate in the film and transient regimes of the boiling of liquids, as well as film boiling crisis have been revealed. With the aid of a high-speed video-filming the existence of the phases of nonlinear waves with time-varying amplitudes whose values are commensurable with the average thickness of the vapor film or exceed it has been revealed. The amplitude of these waves increased in motion of the vapor film to the sphere vertex and attained an order of 0.7 mm. In experiments with subcooling, secondary flows were observed near the interface due to the transfer of heat from the vapor-liquid interface.