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Journal ArticleDOI

Effective interfacial area in gas-liquid cocurrent downflow through packed beds

01 Sep 1991-Bioprocess Engineering (Springer Nature)-Vol. 7, Iss: 1, pp 29-34
TL;DR: In this article, the effective interfacial area in cocurrent gas-liquid downflow through packed beds is analyzed taking into consideration the specific surface of the packing and the interdispersion of the phases.
Abstract: The effective interfacial area in cocurrent gas-liquid downflow through packed beds is analysed taking into consideration the specific surface of the packing and the inter-dispersion of the phases. Predictive equations valid for low and high interaction regimes are developed based on the experimental data of the present study, and are satisfactorily compared with the data of the earlier investigations.
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Journal ArticleDOI
TL;DR: In this article, a model based on two-phase volume-averaged equations of motion is proposed to examine the gravity dependence of the bubble-to-pulse transition in gas-liquid cocurrent down-flow through packed beds.
Abstract: A model based on two-phase volume-averaged equations of motion is proposed to examine the gravity dependence of the bubble-to-pulse transition in gas-liquid cocurrent down-flow through packed beds. As input, the model uses experimental correlations for the frictional pressure drop under both normal gravity conditions and in the limit of vanishing gravity, as well as correlations for the liquid-gas interfacial area per unit volume of bed in normal gravity. In accordance with experimental observations, the model shows that, for a given liquid flow, the transition to the pulse regime occurs at lower gas-flow rates as the gravity level or the Bond number is decreased. Predicted transition boundaries agree reasonably well with observations under both reduced and normal gravity. The model also predicts a decrease in frictional pressure drop and an increase in total liquid holdup with decreasing gravity levels. © 2013 American Institute of Chemical Engineers AIChE J 60: 778–793, 2014

5 citations

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Journal ArticleDOI
TL;DR: In this article, a macroscopic model based on momentum balance is formulated for the condition of no radial pressure gradients, which includes the effect of bubble formation on the pressure drop and holdup and is compared with the experimental data of earlier investigators and of the present study.
Abstract: Pressure drop and liquid saturation are two important design parameters in cocurrent gas-liquid downflow through packed beds. A macroscopic model based on momentum balance is formulated for the condition of no radial pressure gradients. The model includes the effect of bubble formation on the pressure drop and holdup and is compared with the experimental data of the earlier investigators and of the present study. The model provides a functional form for correlating pressure drop and liquid saturation but some parameters have to be determined by fitting the experimental data.

72 citations

Journal ArticleDOI
TL;DR: In this paper, an empirical equation of liquid holdup and interfacial areas was presented in terms of Reynolds numbers of gas Reg( =dsGg/μg) and liquid Rel, surface shape factor of packing φ, void fraction e and ratio of packing to column diameter dp/T, where the ratio is smaller than 0.13.
Abstract: Liquid holdup and interfacial areas were measured in packed columns with cocurrent downward flow. An empirical equation of liquid holdup Φt is presented in terms of Reynolds numbers of gas Reg(=dsGg/μg) and liquid Rel, surface shape factor of packing φ, void fraction e and ratio of packing to column diameter dp/T, where the ratio is smaller than 0.13. This equation is different for the dispersed bubble flow and other flow regions. The empirical equation of interfacial area ap in the respective flow regions varies as follows: apdp/(1-Φl/e)=ωΦ-mRenlReqg(dp/T)-twhere ω=7.5×10-5, m=Q.2, n=Q.15, q=2/3, t=2.5 for spray flow; ω=2.2×10-4, m=0.3, n=2/3, q=0.2, t=2.5 for pulse flow; ω=3.9×10-3, m=0.1, n=0.4, q=p. t=2 for trickle flow; ω=2.8×10-7, m=0.9, n=1.8, q=0, t=3.3 for dispersed bubble flow. The equation of the boundary in the respective flow regions was found by equating the two of them. The predicted boundaries are in excellent agreement with the literature data given from the analysis of liquid pulse frequencies. The predictions for interfacial areas also agree well with the literature data.

66 citations


"Effective interfacial area in gas-l..." refers background or result in this paper

  • ...cylinders). The phenomena, observed also by earlier investigators [3, 6 , 8], may be attributed to the inter-dispersion of the phases as bubbles/droplets in the high interaction regime....

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  • ...While Fukushima and Kusaka [ 6 ] related the interfacial area to the flow rates G. S. Venkata Ratnam and Y. B. G. Varma: Effective interfacial area in gas-liquid cocurrent downflow through packed beds 31...

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  • ...Gianetto et al. [4] and Charpentier [5] related the interracial area to the two phase pressure drop for pulse flow and trickle flow regions, while Fukushima and Kusaka [ 6 ] related it to the gas holdup....

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Journal ArticleDOI
TL;DR: In this article, a flow pattern was visually observed for non-foaming and foaming Newtonian and non-Newtonian liquids under concurrent downflow with air in packed beds using different configurations of column geometry and packins.
Abstract: Flow pattern was visually observed for non-foaming and foaming Newtonian and non-Newtonian liquids under concurrent downflow with air in packed beds using different configurations of column geometry and packins. Flow maps delineating the different flow regions were presented based on the present study as well as that of earlier investigations. The total and dynamic liquid saturation were experimentally measured and correlations were presented in terms of (i) the Lockhart-Martinelli parameter, χ, and (ii) the flow variables. On a observe de maniere visuelle les profils d'ecoulement pour des liquides newtoniens ou non newtoniens, moussants et non moussants, dans le cas d'un acoulement descendant de liquides et d'air dans un lit a garnissage. On a fait varier la gaomatrie de la colonne et le garnissage. Les diagrammes d'ecoulement delimitant les differentes regions d'ecoulement, presentes dans cette etude, s'appuient sur le travail actuel ainsi que sur des recherches anterieures. On a mesure de maniere experimentale la saturation du liquide dynamique et to tale, et les correlations sont presentes en fonction (i) du parametre Lockhart-Martinelli, χ, et (ii) des variables d'ecoulement.

58 citations


"Effective interfacial area in gas-l..." refers background in this paper

  • ...Different flow patterns for the phases are identified in cocurrent gas-liquid downflow through packed beds [1, 2 ]. At low gas and liquid flow rates (G < 1; L w/G < 4), both the phases are continuous and the flow is broadly termed trickle flow (TF)....

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