Burnout during steam-liquid disperse annular flows in nonstationary conditions

Characteristics of gas-liquid dispersion-annular flows in heated tubes are considered within the frames of two-rate thermodynamically equilibrium non-stationary model. Occurrence conditions of of heat-transfer crisis at jump-like increase of heat loading and smooth decrease of liquid consumption at the tube inlet are investigated. System of differential equations of mass conservation of each mixture component (vapor, liquid film and drops) and pulse for a vapor-drop flow nucleus and by-wall liquid films is obtained. Results of numerical integrating of this equation system are given. Relations, describing mass and force interaction between the mixture components, model of the initial section of mixture flow in the tube, initial and boundary conditions for solving stationary and non-stationary problems, are considered. Experimental data on heat transfer crisis under non-stationary conditions are reviewed: during the decrease of liquid consumption at the channel inlet and during stage increase of heat loading. It is concluded on the base of the analysis of these data and their comparison, with calculation results, that the suggested approach is most accurate approximation as compared with homogeneous non-stationary model