VOID FRACTION MEASUREMENT IN SUBCOOLED FORCED CONVECTIVE BOILING WITH REFRIGERANT 12

Abstract

This article presents investigations and results of void fraction and pressure drop of dichlordifluormethane (CCl₂ in forced convective, subcooled boiling. The data were taken at different heal fluxes in a 12- to 25-bar pressure range, the mass fluxes have been varied from 500 to 3000 kg/ m2 s with an inlet subcooling in the range from 10 to SO K. The experiments have been conducted in an annular test channel with a 0.016-m inner diameter and a 0.03-m outer diameter. The inner tube of the annulus was heated by direct current. The void fraction data were gauged with a γ -densitometer and a specially designed impedance void meter. The experimental results reveal that the void fraction is nearly constant from the onset of nucleation boiling to a subcooling of about δ T = 10 K. A method for predicting the void fraction based on the drift flux model will also be presented.