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Journal of Enhanced Heat Transfer

Theory and Application in High Performance Heat and Mass Transfer

ISSN for PRINT: 1065-5131

Institutional price:	$577.00
Issues per year:	4

Best Paper Award Selection - Editorial Board Site

2005, Volume12

126 pages

DOI: 10.1615/JEnhHeatTransf.v12.i1

Issue price - $138.00

Analysis of Annular Two-Phase Flow Dynamics Under Heat Transfer Conditions

I. V. Kazachkov
Department of Energy Technology, Royal Institute of Technology, Brinellvagen 60,100 44 Stockholm, Sweden

B. Palm
Royal Institute of Technology (KTH); Department of Energy Technology, Brinellvagen 60,100 44 Stockholm, Sweden

ABSTRACT

An analytical investigation was performed for the instability phenomenon of two-phase annular flow with a thin film flow on the channel wall under heat transfer conditions. The analyses of heat transfer behaviors of two-phase annular flow showed that the overall heat transfer behaviors between the fluids and the channel wall were dominated by the thickness of a thin liquid film. The mass, momentum, and energy equations for two phases were employed to study the perturbation behaviors in both fluids. Two different boundary conditions at the wall were considered: heat transfer with constant temperature along the wall and conditions of constant heat transfer along the wall. Basic equations were solved on both hydrodynamic and thermal perturbations in two fluids for the two boundary conditions. Scrupulous analysis was done for the axially symmetrical wave at the two-phase interface. The results showed that in the case of low flow rate, the hydrodynamic perturbations in both fluids always decreased. Only kinematic waves at the gas/liquid interface could exist, but did not grow. The waves moved at the same velocity as the gas phase in the channel core. However, the thermal perturbations might grow in some conditions. They finally caused hydrodynamic perturbations, which might also grow, causing a flow instability. The solutions for characteristics of the interface waves such as wavelength and increment of perturbations were obtained. More interestingly, for the isothermal boundary conditions it was found that the maximum increment of perturbations (most unstable) was only dependent on the thermodynamical property ratios of the gas and liquid.