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In engineering, the mass transfer coefficient is a diffusion rate constant that relates the mass transfer rate, mass transfer area, and concentration change as driving force: [1] = ˙ Where: is the mass transfer coefficient [mol/(s·m 2)/(mol/m 3)], or m/s
Mass transfer is the net movement of mass from one location (usually meaning stream, phase, fraction, or component) to another. Mass transfer occurs in many processes, such as absorption , evaporation , drying , precipitation , membrane filtration , and distillation .
Here, is the overall mass transfer coefficient, which could be determined by empirical correlations, is the surface area for mass transfer (particularly relevant in membrane-based separations), and ˙ is the mass flowrate of bulk fluid (e.g., mass flowrate of air in an application where water vapor is being separated from the air mixture). At ...
The basic mechanisms and mathematics of heat, mass, and momentum transport are essentially the same. Among many analogies (like Reynolds analogy , Prandtl–Taylor analogy) developed to directly relate heat transfer coefficients, mass transfer coefficients and friction factors, Chilton and Colburn J-factor analogy proved to be the most accurate.
B = diffusion coefficient of the eluting particles in the longitudinal direction, resulting in dispersion [m 2 s −1] C = Resistance to mass transfer coefficient of the analyte between mobile and stationary phase [s] u = speed [m s −1] In open tubular capillaries, the A term will be zero as the lack of packing means channeling does not occur ...
The same restrictions described in the heat transfer definition are applied to the mass transfer definition. The Sherwood number can be used to find an overall mass transfer coefficient and applied to Fick's law of diffusion to find concentration profiles and mass transfer fluxes.
The diffusion in the bulk fluide compensate the utilisation of B at the surface of the catalyst. k g is the mass transfer coefficient. Ṅ diff,B =k g (y B,1 -y B,2 ) Although the mixture is stationary due to the molar flow rate and velocity being zero, the net mass flow rate of the mixture is not equal to zero unless the molar mass of A is ...
This is known as the charge transfer rate. The second is the rate at which reactants are provided, and products removed, from the electrode region by various processes including diffusion, migration, and convection. The latter is known as the mass-transfer rate [Note 1]. These two rates determine the concentrations of the reactants and products ...