Experimental Study on Flow Patterns and Pressure Drop of Decaying Swirling Gas-Liquid Flow in a Vertical Pipe

Abstract Vertical swirling gas-liquid flow is a kind of complex two-phase flow containing a nonzero tangential velocity component in engineering applications. The accurate flow regime characterization, phase distribution information and pressure drop data about vertical swirling flow are the basis for the optimization of steam generator (SG), which can greatly reduce the cost and improve the safety of nuclear plants. To get these key parameters of swirling vertical flow, we have made a comprehensive visualization experiment in a vertical pipe with 30mm diameter and 5m length by high-speed camera. The experimental pipe is separated into swirling part and non-swirling part. We have set three observation section with different vertical heights in the swirling part. Changing the flow rate of water and gas, different swirling flow pattern photos can be captured by high-speed camera. Based on the photos of different positions and image-processing MATLAB code, we can get three flow regime maps and figure out the decaying law of swirling gas-liquid flow. The pressure drop can be recorded by rotameter at each position. The decaying law of pressrure drop can be concluded from it. These data can be a guide for designing gas-liquid separator in SG to improve the efficiency of nuclear plant.

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Gas-Liquid Flow and Interphase Mass Transfer in LL Microreactors

Fluids ◽

10.3390/fluids5040223 ◽

2020 ◽

Vol 5 (4) ◽

pp. 223

Author(s):

Brendon J. Doyle ◽

Frederic Morin ◽

Jan B. Haelssig ◽

Dominique M. Roberge ◽

Arturo Macchi

Keyword(s):

Experimental Data ◽

Mass Transfer ◽

Pressure Drop ◽

Flow Regime ◽

Liquid Flow ◽

Immiscible Fluids ◽

Bubble Flow ◽

Interphase Mass Transfer ◽

Gas Liquid Flow ◽

The Impact

This work investigates the impact of fluid (CO2(g), water) flow rates, channel geometry, and the presence of a surfactant (ethanol) on the resulting gas–liquid flow regime (bubble, slug, annular), pressure drop, and interphase mass transfer coefficient (kla) in the FlowPlateTM LL (liquid-liquid) microreactor, which was originally designed for immiscible liquid systems. The flow regime map generated by the complex mixer geometry is compared to that obtained in straight channels of a similar characteristic length, while the pressure drop is fitted to the separated flows model of Lockhart–Martinelli, and the kla in the bubble flow regime is fitted to a power dissipation model based on isotropic turbulent bubble breakup. The LL-Rhombus configuration yielded higher kla values for an equivalent pressure drop when compared to the LL-Triangle geometry. The Lockhart–Martinelli model provided good pressure drop predictions for the entire range of experimental data (AARE < 8.1%), but the fitting parameters are dependent on the mixing unit geometry and fluid phase properties. The correlation of kla with the energy dissipation rate provided a good fit for the experimental data in the bubble flow regime (AARE < 13.9%). The presented experimental data and correlations further characterize LL microreactors, which are part of a toolbox for fine chemical synthesis involving immiscible fluids for applications involving reactive gas–liquid flows.

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Holdup and pressure drop with gas-liquid flow in a vertical pipe

AIChE Journal ◽

10.1002/aic.690070429 ◽

1961 ◽

Vol 7 (4) ◽

pp. 677-682 ◽

Cited By ~ 51

Author(s):

G. A. Hughmark ◽

B. S. Pressburg

Keyword(s):

Pressure Drop ◽

Liquid Flow ◽

Vertical Pipe ◽

Gas Liquid Flow

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Pressure drop in gas-liquid flow at microgravity conditions

International Journal of Multiphase Flow ◽

10.1016/s0301-9322(97)88366-8 ◽

1996 ◽

Vol 22 ◽

pp. 122

Author(s):

L Zhao

Keyword(s):

Pressure Drop ◽

Liquid Flow ◽

Microgravity Conditions ◽

Gas Liquid Flow

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

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19850745 ◽

1985 ◽

Vol 50 (3) ◽

pp. 745-757 ◽

Cited By ~ 3

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.

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