Scaling and correlation of subcooled void growth for circular and finned annular geometries at low pressure

Void growth measurements in subcooled flow boiling for two finned annuli and two circular annuli were obtained for flow rates between 0.02 and 0.2 kg-1 (mass fluxes between 80 and 1400 kg m-2s), for outlet pressures of 105, 200 and 300 kPa, and for inlet temperatures of 30 to 90 C. A parametric study of the influence of outlet pressure, velocity, geometry, subcooling, and power on void growth is presented, new scaling parameters for void growth are introduced, and a non-dimensional linear correlation based on the Nusselt number and the onset of nucleate boiling is developed. It is found that at a flow rate of 0.02 kgs-1, the onset of significant void is independent of input parameters. Scaling of void growth showed that the region before the onset of significant void is important and that void fraction increases linearly in this region. (orig.)