An experimental investigation of critical flow rates of subcooled water through short pipes with small diameters

Abstract

Critical two-phase flow rates of subcooled water through short pipes ( L < 400 mm) with small diameters ( D < 7.15 mm) have been experimentally investigated for wide ranges of subcooling (0 ∼ 199 ° C) and pressure (0.5 ∼ 2.0 MPa). To examine the effects of various parameters (i.e., the location of flashing inception, the degree of subcooling, the stagnation temperature and pressure, and the pipe size) on the critical two-phase flow rates of subcooled water through short pipes with small diameters, a total of 135 runs were made for various combinations of test parameters using four different L D test sections. Experimental results that show effects of various parameters on subcooled critical two-phase flow rates are presented in the form of graphs such as the dimensionless mass flux ( G ∗ ) versus the dimensionless subcooling ( ΔT ∗ sub ) curve. An empirical correlation expressed in terms of a dimensionless subcooling ( ΔT ∗ sub ) is also obtained for subcooled two-phase flow rates through present test sections. Comparisons between the mass fluxes calculated by present correlation and a total of 679 selected experimental data points of 9 different investigators show that the agreement is fairly good except for very low subcooling data obtained from small L D (less than 10) orifices.