Abstract:This work covers experimental and theoretical investigation of thermal oscillation in forced convection boiling in a vertical single-channel system, with Freon-11 as the working fluid. Experiments with various heat inputs and inlet fluid temperatures, as well as for different heater tube sizes, have been conducted to investigate the effects of these parameters on the oscillation. Under the experimental conditions of the study, pressure-drop type oscillation and thermal oscillation have been observed. In the theoretical study, a numerical model has been developed to predict both the steady-state and transient behavior of the forced convection two-phase flows in a single-channel system. The conditions under which thermal oscillation occurs are aslo predicted. The periods and amplitudes predicted with the model are in good agreement with the experimental results.