TWO-PHASE CRITICAL FLOW WITH APPLICATION TO LIQUID-METAL SYSTEMS (MERCURY, CESIUM, RUBIDIUM, POTASSIUM, SODIUM, AND LITHIUM)

Existing data and models for critical two-phase flow of steam-- water mixtures are examined. One model in particular shows considerable success in predicting the phenomena of critical flow. A Fortran program for an IBM-704 digital computer, for the application of this model to predict void fraction, slip ratio, and critical flow rates to the flashing flow for various liquid-vapor metal systems inpipes when the conditions are such that critical flow may be experienced, was developed. Calculations were made for the following liquid- metal systems: mercury (temperature range, 450 to 1600 deg F), cesium (temperature range, 500 to 2300 deg F), rubidium (temperature range, 500 to 2300 deg F), potassium (temperature range, 900 to 2500 deg F), sodium (temperature range, 950 to 2500 deg F), and lithium (temperature range, 2000 to 3500 deg F). The vapor fraction or quality ranges from 0 to 100%. It is shown that the critical flow rates for liquid-metal systems calculated from the best model describing steam--water data are considerably higher in the low-quality region than predicted from a socalled homogeneous flow model.'' This is explained by the large slippage between the liquid and the vapor phases, because the ratio of the densities of the liquid state to the vapor state is usually large for metallic fluids. (auth