Pressure drop, liquid holdup, and flow regime transition in trickle flow

AIChE Journal ◽  
1993 ◽  
Vol 39 (2) ◽  
pp. 302-321 ◽  
Author(s):  
R. A. Holub ◽  
M. P. Duduković ◽  
P. A. Ramachandran
Keyword(s):  
Pressure Drop ◽  
Flow Regime ◽  
Regime Transition ◽  
Liquid Holdup ◽  
Flow Regime Transition

Investigation of a Two-Phase Siphon: Pressure Drop Characteristics, Flow Prediction, and Flow Regime Change Prediction

Volume 3 ◽  
2004 ◽  
Author(s):  
J. Howard Arthur ◽  
Charles D. Morgan ◽  
Cory D. Engelhard ◽  
Berton Austin
Keyword(s):  
Pressure Drop ◽  
Flow Regime ◽  
Distribution Parameter ◽  
Regime Transition ◽  
Two Phase ◽  
Flow Rates ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Flow Regime Transition ◽  
Flux Model

In some nuclear power plants, a passive siphon breaking system is used to prevent the spent fuel tank from draining in the event of a break in the vertical leg of the heat exchanger piping. A hole is drilled in the horizontal leg of the piping. When the water level in the tank drops below the pipe level air is sucked into the system. When sufficient air is entrained in the pipe the siphon will break. A model to predict the flow rate in a vertical siphon was developed in reference 1 using the homogeneous flow model. The predicted flow rates were greater than measured flow rates. In order to improve the predictive capability, pressure drop measurements were obtained from ten foot vertical test sections with nominal diameters of 0.5, 0.75, 1.0, 1.25, 1.5, and 2.0 inches. Values of the distribution parameter, Co, for the drift flux model were determined from the pressure drop data. When the model of reference 1 is changed from homogeneous flow to drift flux model with the distribution parameter determined from the pressure drop data, good agreement with measured liquid flow rates is obtained. The improved model, along with the correlation for the siphon break condition obtained provides a good method for determining the hole size required to break the siphon. There is a paucity of data for two-phase flow regime transition where the flow is in the downward direction that is typical in a siphon. Flow regime transition data were obtained using the test sections listed above. The flow map of Oshinowo2 et al. gave a reasonable prediction of the transition from bubbly to slug flow. None of the references investigated gave an adequate prediction of the point where the siphon would break. A correlation for the siphon break point was developed.

The effect of two-phase flow regime on hydrodynamics and mass transfer in a horizontal-tube gas-liquid reactor

1985 ◽  
Vol 50 (3) ◽  
pp. 745-757 ◽  
Author(s):  
Andreas Zahn ◽  
Lothar Ebner ◽  
Kurt Winkler ◽  
Jan Kratochvíl ◽  
Jindřich Zahradník
Keyword(s):  
Mass Transfer ◽  
Pressure Drop ◽  
Flow Regime ◽  
Liquid Flow ◽  
Horizontal Tube ◽  
Liquid Holdup ◽  
Two Phase ◽  
Flow Rates ◽  
Type Relation ◽  
Good Agreement

The effect of two-phase flow regime on decisive hydrodynamic and mass transfer characteristics of horizontal-tube gas-liquid reactors (pressure drop, liquid holdup, kLaL) was determined in a cocurrent-flow experimental unit of the length 4.15 m and diameter 0.05 m with air-water system. An adjustable-height weir was installed in the separation chamber at the reactor outlet to simulate the effect of internal baffles on reactor hydrodynamics. Flow regime maps were developed in the whole range of experimental gas and liquid flow rates both for the weirless arrangement and for the weir height 0.05 m, the former being in good agreement with flow-pattern boundaries presented by Mandhane. In the whole range of experi-mental conditions pressure drop data could be well correlated as a function of gas and liquid flow rates by an empirical exponential-type relation with specific sets of coefficients obtained for individual flow regimes from experimental data. Good agreement was observed between values of pressure drop obtained for weirless arrangement and data calculated from the Lockhart-Martinelli correlation while the contribution of weir to the overall pressure drop was well described by a relation proposed for the pressure loss in closed-end tubes. In the region of negligible weir influence values of liquid holdup were again succesfully correlated by the Lockhart-Martinelli relation while the dependence of liquid holdup data on gas and liquid flow rates obtained under conditions of significant weir effect (i.e. at low flow rates of both phases) could be well described by an empirical exponential-type relation. Results of preliminary kLaL measurements confirmed the decisive effect of the rate of energy dissipation on the intensity of interfacial mass transfer in gas-liquid dispersions.

Low Bond Number Two-Phase Flow Regime Transition from Slug to Annular Wavy Flow in a Microchannel

2003 ◽  
Vol 125 (4) ◽  
pp. 544-544 ◽  
Author(s):  
Sang Young Son ◽  
Jeffrey S. Allen ◽  
Kenneth O. Kihm
Keyword(s):  
Flow Regime ◽  
Two Phase Flow ◽  
Bond Number ◽  
Phase Flow ◽  
Regime Transition ◽  
Two Phase ◽  
Flow Regime Transition

Influence of Operating Pressure on Gas Holdup and Flow Regime Transition in a Bubble Column

2010 ◽  
Vol 43 (10) ◽  
pp. 829-832 ◽  
Author(s):  
Hiroaki Matsubara ◽  
Kiyoshi Naito ◽  
Hideharu Kuwamoto ◽  
Toshiyuki Sakaguchi
Keyword(s):  
Flow Regime ◽  
Bubble Column ◽  
Gas Holdup ◽  
Operating Pressure ◽  
Regime Transition ◽  
Flow Regime Transition
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