Article

Film‐penetration model for mass and heat transfer

Carnegie Institute of Technology, Pittsburgh, Pennsylvania
AIChE Journal (Impact Factor: 2.49). 06/2004; 4(1):97 - 101. DOI: 10.1002/aic.690040118
0 Bookmarks
 · 
127 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Film and penetration models for simultaneous heat and mass transfer are developed for the absorption of gas with a first-order chemical reaction in the liquid phase with temperature-dependent solubility and reaction rate coefficient. These two models represent two extreme conditions of interfacial temperature rise and gas solubility and they are compared with some previous models (Allan and Mann, 1979; Asai et al., 1985). The approximate analytical expressions of the penetration model of Asai et al. (1985) are in good agreement with the numerical results of this work. The results reveal that under many practical circumstances the gas-liquid interfacial temperature may be several degrees Kelvin higher than the bulk liquid temperature. The degree of deviation of the enhancement factor from its isothermal value at the bulk liquid temperature depends on the degree of difference of a certain dimensionless activation energy group from zero, which confirms the previous finding of Asai et al. (1985).On a mis au point un modèle de pénétration et un modèle de films pour le transfert de matière et de chaleur simultané afin d'étudier l'absorption d'un gaz en présence d'une réaction chimique de premier ordre dans la phase liquide; dans ces modèles, la constante de vitesse de réaction et la solubilité dépendent de la température. Ces deux modèles représentent deux conditions extrěmes d'augmentation de la empérature interfaciale et de solubilité du gaz et sont comparés à des modèles précédents (Allan et Mann, 1979, Asai et coll., 1985). Les expressions analytiques approximatives du modèle de pénétration de Asai et coll. (1985) sont en bon accord avec les résultats numériques de ce travail. Les résultats montrent que dans de nombreuses situations pratiques la température de l'interface gaz-liquide peut ětre supérieure de plusieurs degrés Kelvin à la température du liquide. Le degré de déviation du facteur d'accéleration par rapport à sa valeur isotherme à la température du liquide, dépend de l'écart d'un certain groupe adimensionnel comportant l'énergie d'activation par rapport à la valeur zéro, ce qui confirme les résultats précédents d'Asai et coll. (1985).
    The Canadian Journal of Chemical Engineering 03/2009; 65(3):454 - 461. · 1.00 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The aim of this study is to quantify the mass transfer velocity using turbulence parameters from simultaneous measurements of oxygen concentration fields and velocity fields. The surface divergence model was considered in more detail, using data obtained for the lower range of β (surface divergence). It is shown that the existing models that use the divergence concept furnish good predictions for the transfer velocity also for low values of β, in the range of this study. Additionally, traditional conceptual models, such as the film model, the penetration-renewal model, and the large eddy model, were tested using the simultaneous information of concentration and velocity fields. It is shown that the film and the surface divergence models predicted the mass transfer velocity for all the range of the equipment Reynolds number used here. The velocity measurements showed viscosity effects close to the surface, which indicates that the surface was contaminated with some surfactant. Considering the results, this contamination can be considered slight for the mass transfer predictions. © 2009 American Institute of Chemical Engineers AIChE J, 2010
    AIChE Journal 12/2009; 56(8):2005 - 2017. · 2.49 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Steady state simulation of the hydrodynamics and mass transfer in bubbly flow in an axisymmetric internal airlift loop reactor (IALR) with the special treatment of interphase decoupling and outlet boundary conditions is performed, which is based on a Favre averaging two-fluid model for multiphase flow. Different models of mass transfer coefficient are compared and validated with the literature data. A model for describing the mass transfer for a wide range of superficial gas velocity is chosen and the predicted mass transfer coefficient agrees well with the experimental data in the literature. The numerical procedure can be used as a tool for the design and scale-up of IALRs.
    Chemical Engineering Science. 01/2010;