AN EXPERIMENTAL INVESTIGATION OF CRITICAL FLOW-RATES OF SUBCOOLED WATER THROUGH SHORT PIPES WITH SMALL DIAMETERS

Critical two-phase flow rates of subcooled water through short pipes ( L < 400 mm) with small diameters (D < 7.15 mm) have been experimentall y investigated for wide ranges of subcooling (0 similar to 199 degrees C) and pressure (0.5 similar to 2.0 MPa). To examine the effects of v arious parameters (i.e., the location of flashing inception, the degre e 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 v arious combinations of test parameters using four different L/D test s ections. Experimental results that show effects of various parameters on subcooled critical two-phase flow rates are presented in the form o f graphs such as the dimensionless mass flux (G) versus the dimension less subcooling (Delta T(sub)) curve. An empirical correlation expres sed in terms of a dimensionless subcooling (Delta T(sub)) is also obt ained for subcooled two-phase flow rates through present test sections . Comparisons between the mass fluxes calculated by present correlatio n and a total of 679 selected experimental data points of 9 different investigators show that the agreement is fairly good except for very l ow subcooling data obtained from small L/D (less than 10) orifices. Co pyright (C) 1996 Elsevier Science Ltd