Pressure drops and void fractions in horizontal two-phase flows of potassium

Abstract

Vapor-liquid flow of a potassium-8% sodium mixture was studied with the use of a boiling heat transfer test loop. Pressure drop data were obtained from a 36-in. long, 0.495-in. I.D. unheated test section. Void fractions were measured at the midpoint of the test section with gamma ray attenuation. Flows were essentially frictional. Quality, total flow rate, and absolute pressure were the principal variables affecting the pressure drop results, which were correlated in terms of a two-phase friction factor. A metallic void fraction correlation was developed from previously reported data for other metallic fluids together with the potassium data of this study. The potassium two phase friction factors fall substantially lower than values predicted by well-known frictional pressure drop correlations. Metallic void friction values are appreciably lower than data for other fluid systems. Velocity slip ratios appear to be much higher than for other fluid systems due to high liquid-to-vapor density ratios and low void fractions.