AbstractThe understanding of the heat and mass transfer phenomena between hot bubbles and a liquid is particularly relevant to the design of direct contact heating and evaporation systems such as submerged combustion equipment. In this process, exhaust gas from a burner is dispersed in a liquid to be heated or evaporated. Various models for the prediction of the temperature and vapor content of the bubbles as a function of their residence time in the liquid are presented. Based on the experimental measurements of the bubble size and of the heating time and evaporation rate in an actual submerged combustion system, models using spherical, ellipsoidal and spherical‐cap bubbles, with or without internal circulation, are discussed and assessed. It is found experimentally that the bubbles are of a spherical cap shape. Bubble equivalent diameters between 15 and 25 mm and bubble velocities between 0.4 and 1.2 m/s are observed. The proposed models are used to compute the heating time and evaporation rate of the bath during a submerged combustion operation; the predictions are then compared to the experimental values. The rigid spherical cap bubble model is found to predict satisfactorily the heat and mass exchanges between the bubbles and the liqui