Influence on Mass Transfer

For a given film thickness Sf, the important parameter is the concentration at the film surface. If this concentration tends toward zero, the film has a negligible influence on mass transfer. Otherwise, the influence of the film cannot be neglected. 

The polydisperse effect had very little influence on mass transfer behavior (see Fig. 4.3). 

Temperature has only a modest influence on mass transfer rates under a given conceniraiion driving force. 

By viscous interaction with the continuous phase, oscillating shape variations of liquid drops and gas bubbles occur, and for Re 1. mobile surface fluid particles in free-rising or falling conditions move in a wobbling or spirial-like manner, which has a marked influence on mass transfer rates. As before, we can arrive at different correlations for different bulk flow regions. These are summarized below ... 

The superficial gas velocity Uq is a description of the amount of gas present in the reactor volume and is defined as the volumetric gas flow rate per unit cross-sectional area of the reactor. This definition is easily quantifiable and has been used by many researchers as a correlation parameter for gas holdup and gas-liquid mass transfer. Most researchers cited in this chapter, with the exception of Linek et al. (2005a), have proposed a positive correlation of superficial gas velocity with gas-liquid mass transfer however, its specific influence on mass transfer is often confusing. 

Besides this bulk phase elfects surfactants will adsorb at the liquid-liquid interface. Their influence on mass transfer may then be on different mechanism. A blocking effect of adsorption layers in a diffusional transport regime is well known and results in a reduction of mass transfer [54-57] and even Marangoni instabilities [58,59] are found. However, in the kinetical mass-transfer regime, both an enhancement and retartion of mass transfer [59] is with Gibbs surfactant layers. With extracting ionic species, ionic surfactants will induce an electrostatic double layer, which can be related to the -potential. As a result, there exists, in addition to the chemical potentials, an... 

The first two chapters of this book, which serve as the preparatory materials on computational methodology, cover the fundamentals of CFD and CHT. Chapters 3-7 discuss the process computation of various gas-Uquid contacting and catalytic reaction processes and equipments in chemical engineering. Chapters 8 and 9 introduce the computation of Marangoni and Rayleigh convections and their influence on mass transfer by using differential equations and the lattice-Boltzmann method. 

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