Experiment and Modeling of Interfacial Area Concentration of Liquid Film in Upward Annular Two-Phase Flow

Abstract

To accurately quantify the interfacial transfer terms in the two-fluid model, the reliable prediction of the interfacial area concentration (IAC) is crucial. The IAC in annular flow, especially the interface between the liquid film and gas core, is particularly important due to its relevance to critical heat flux and reactor operation safety. However, very few experimental and analytical studies have been performed that focus on the IAC of the liquid film in annular flow. In this work, the IAC of the liquid film is measured using a parallel-wire conductance probe for upward annular flow in a 25.4-mm one-dimensional pipe. A total of 25 flow conditions are measured with the range of superficial liquid velocity from 0.15 to 2.00 m/s and the range of superficial gas velocity from 10.0 to 29.6 m/s. The IAC radial profile is obtained from the liquid film time trace measured by the conductance probe, and the accuracy of this method is verified by flow visualization. The effects of the inlet gas and liquid flow rates on the characteristics of the IAC radial distribution as well as area-averaged IACs are analyzed. A new model is developed to predict the IAC radial distribution of the liquid film. The IAC profiles predicted by the model agree very well with the measured IAC profiles for typical annular flow conditions and have a reasonable agreement for the wispy annular flow conditions.

Keywords:

• Annular flow
• interfacial area concentration
• wave structure
• wispy annular flow
• liquid film

Nomenclature

ai	=	= IAC (1/m)
DH	=	= hydraulic diameter (m)
d	=	= distance to the wall (m)
$\hat{d}$	=	= nondimensional distance to the wall, d/R
g	=	= gravity acceleration (m/s2)
$j_f$	=	= superficial liquid velocity (m/s)
$j_g$	=	= superficial gas velocity (m/s)
$j_{g0}$	=	= superficial gas velocity at the inlet (m/s)
k	=	= parameter in the log-normal distribution (1/m)
z	=	= axial distance (m)

Greek

μ	=	= parameter in the log-normal distribution
${\mu }_f$	=	= liquid viscosity (Pa·s)
σ	=	= parameter in the log-normal distribution
σs	=	= surface tension (N/m)
δavg	=	= average film thickness (m)
δbase	=	= base film thickness (m)
${\rho }_f$	=	= liquid density (kg/m3)
${\rho }_g$	=	= gas density (kg/m3)
$\mathrm{\Delta }\rho$	=	= density difference between liquid and gas (kg/m3)

Disclosure Statement

No potential conflict of interest was reported by the authors.