Flow visualizations during top venting from a small vessel

Visualization of emergency viscous two-phase venting behaviors

“…This is the time of fully vapor-liquid disengagement occurred and thus vapor venting began. Besides the two-phase flow behaviors and oscillations of pressure, the experimental observations in water agreed well with previous studies (Bell & Morris, 1992;Chang & Shey, 1999). The vented water was 30.3% in volume ratio.…”

“…An emergency relief, pure vapor or two-phase flow-passing orifice depended on the rising level of the liquid. Previous studies confirmed that the venting of pure water was a vapor phase flow due to the volume ratios to vessels at the value of 0.6 or 0.75 (Bell & Morris, 1992;Chang & Shey, 1999) where the liquid cannot overflow the orifice. This agreed with the pressure trace decreasing sharply after the venting of valve at 5 s (Chang & Shey, 1999).…”

“…10 1402.011/T À 9.671 insufficient vapor pressure above the liquid. The pressure rising after boiling was also called the pressure recovery phase (Bell & Morris, 1992). After the boiling delay, the liquid started to boil, the bubbles generated from about one third of height above the bottom of vessel.…”

“…Other studies concerning the void fraction, mass flow rate, and hydrodynamic model for viscous flow relieved at the venting nozzle were proposed in the literature (Bell, Morris, & Oster, 1993;Frundt, Steiff, & Weinspach, 1997;Oster, Bell, & Kottowski, 1990;Oster, Kottoski, & Schroer, 1989;Skouloudis & Kottowski, 1991). Microscopic visualization of twophase flow at the instant of blow-down provides another approach to investigate the transient behaviors of viscous fluid in reactor (Bell & Morris, 1992;Chang & Shey, 1999;Duh, Hu, Lee, Kao, & Chang, 1999). This is important to determine the bubble rise velocity, bubble sizes, and liquid floating behavior in order to check the models or parameters suitable for using in SAFIRE program.…”

“…Besides checking the viscous effect on the blow-down phenomena, the second purpose lies on investigating the microscopic behavior of viscous at the instant of blow-down by using fast photographic technique. The result will be compared with the ''two-phase emulsion'' proposed by Bell and Morris (1992).…”