hydrodynamic parameters for gas-liquid cocurrent flow in packed beds
TL;DR: In this article, the hydrodynamics of cocurrent gas-liquid flow in packed beds is analyzed by extending the concept of relative permeability to the inertial regime, where the relative permeabilities of the gas and liquid phases are functions of the saturation of the liquid phase.
Abstract: The hydrodynamics of cocurrent gas-liquid flow in packed beds is analyzed by extending the concept of relative permeability to the inertial regime.
The relative permeabilities of the gas and liquid phases are functions of the saturation of the liquid phase. These functions are found from an analysis of experimental data. The relations obtained are used to develop empirical correlations for predicting liquid holdup and pressure drop in gas-liquid cocurrent downflow in packed beds over a wide range of operating conditions. The correlations proposed give very good results when compared to experimental data yielding, in general, mean relative deviations lower than existing correlations. In addition, a new equation is proposed for predicting static holdup in packed beds which is based on a more physically realistic characteristic length than that used in previous studies.
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TL;DR: The chapter concludes that the studies of heat transfer in multicomponent porous media systems are only at the initial stage, and very extensive research is needed in this technologically important and fundamentally intricate subfield ofHeat transfer.
Abstract: Publisher Summary This chapter outlines several theoretical models currently prevailing for multiphase flow and heat transfer in porous media. In particular, a multiphase mixture model is elaborated and compared with the traditional multiphase flow model and unsaturated flow theory. This model is rigorously derived from the traditional multiphase flow model (MFM) without making further approximations. The new model views the multiple phases as constituents of a mixture, and thus consists only of the conservation equations for the whole multiphase mixture. All primary variables in this model are mixture properties; therefore, complex tasks to track phase interfaces separating various subregions and handle phase appearance or disappearance are avoided. The chapter discusses fundamental systems rather than specific applications. To establish a fundamental theoretical framework, basic concepts associated with multiphase transport in porous media are discussed. The chapter reviews both theoretical and experimental work for single component two-phase systems with major applications to thermal engineering, while general multiphase, multicomponent systems in connection with a wide variety of engineering applications, such as drying of porous materials, groundwater contamination, and remediation. The chapter concludes that the studies of heat transfer in multicomponent porous media systems are only at the initial stage, and very extensive research is needed in this technologically important and fundamentally intricate subfield of heat transfer.
226 citations
TL;DR: In this paper, a continuum model of two-phase channel flow based on Darcy's law and the M 2 formalism is developed to estimate the parameters key to fuel cell operation such as overall pressure drop and liquid saturation profiles along the axial flow direction.
186 citations
TL;DR: In this article, a phenomenological, pore-scale, hydrodynamic model is developed for representation of the uniform, two-phase, gas-liquid cocurrent flow in the low interaction regime in trickle bed reactors.
185 citations
TL;DR: In this article, a physical model is developed to predict the hydrodynamic parameters of steady-state cocurrent gas-liquid flow through trickle-bed reactors operating in the trickle flow regime.
170 citations
Cites background or result from "hydrodynamic parameters for gas-liq..."
...Several authors have used the representation of the capillary pressure p C "p G !p L by the Leverett’s function which has found extensive use in the analysis of multiphase flow through porous media to provide a relation between p G and p L (Saez and Carbonell, 1985; Grosser et al., 1988; Dankworth et al., 1990)....
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...However, the experimental studies of Wammes and Westerterp (1990), Wammes et al....
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...The advantage and disadvantages of the trickle-bed reactor are discussed by Satterfield (1975), Gianetto and Specchia (1992) and Saroha and Nigam (1996)....
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TL;DR: In this article, a fractal analysis of porous media, both saturated and unsaturated, is presented based on the fractal nature of pores in the media, and both the phase and relative permeability are derived and found to be a function of the tortuosity fractal dimension.
Abstract: A fractal analysis of permeabilities for porous media, both saturated and unsaturated, is presented based on the fractal nature of pores in the media. Both the fractal-phase permeability and the fractal relative permeability are derived and found to be a function of the tortuosity fractal dimension, pore-area fractal dimension, phase fractal dimension, saturation, and microstructural parameters. The proposed models for permeabilities— both the phase permeability and the relative permeability— do not contain any empirical constant. The validity of the present analysis is verified by a comparison with the existing measurements, and excellent agreement between the model predictions and experimental data is found. In addition, the present work reveals that the relative permeability depends not only on saturation but also on the two fractal dimensions, pore fractal dimension (at porosity greater than 0.90), and tortuosity fractal dimension, which characterize the fractal characters of capillaries in porous media. The two fractal dimensions may be the two of the important mechanisms affecting the relative permeability in porous media, and this is a supplement to the available conclusion on relative permeability. © 2004 American Institute of Chemical Engineers AIChE J, 50: 46 –57, 2004
165 citations