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Mass transfer inside drop

Mass Transfer Inside Drop (Cavity) With a Volume Reaction... [Pg.225]

A light increase of viscosity at higher pressures is disadvantageous for the break-up of drops, but inside the spraying device a mixture of liquid and C02 is formed. The diminished viscosity of this mixture dominates and as a consequence the diffusive mass transfer inside the droplet will be enhanced. [Pg.250]

The last decision parameter concerning process operation is the viscosity. Process economy is influenced by the viscosity in two ways. The pressure drop of the system is proportional to the viscosity of the eluent and, in most cases, the pressure drop is the limiting factor for the flow rate and, thus, productivity. High viscosity mobile phases also show low diffusion of the solutes and thus a worse mass transfer inside the pore system. [Pg.119]

For long contact times and/or short distances between the interface and the core 5, the solution given above for the zero-flux coefficient does not apply. This situation may arise for mass transfer inside liquid droplets that stay sufficiently long in contact with the surrounding gas or liquid. For long contact times, the diffusing species will penetrate deep into the heart of the bubble (or drop), and it is important in such cases to define the mass transfer coefficient in terms of the driving forces Ax, = — , where represents... [Pg.235]

Qualitative Features of Mass Transfer Inside a Drop... [Pg.201]

Mass transfer inside a drop is described by Eq. (4.12.1) and the first two conditions (4.12.2). The fluid velocity field v = (vr,vg) at low Reynolds numbers is given by the Hadamard-Rybczynski stream function and, in the dimensionless variables, has the form... [Pg.201]

The inner problem of convective mass and heat transfer is essentially different from the similar outer problem, primarily, by the streamline pattern. This leads to a corresponding qualitative distinction between the dynamics of processes of transient mass transfer inside and outside a drop. In the outer problem considered in Section 4.12, all streamlines are open. The lines near the flow axis carry the... [Pg.201]

A more detailed analysis [352] shows that mass transfer inside the drop at high Peclet numbers develops through three consecutive stages. Each of them has its special features and different duration. [Pg.202]

Golovin, A. M. and Zhivotyagin, A. F., Influence of a volume chemical reaction on mass transfer inside a drop at large Peclet numbers, Moscow Univ. Math. Mech. Bull., No. 4, 1979. [Pg.355]

MASS TRANSFER TO DROPS AND BUBBLES. When small drops of liquid are falling through a gas, surface tension tends to make the drops nearly spherical, and the coefiBcients for mass transfer to the drop surface are often quite close to those for solid spheres. The shear caused by the fluid moving past the drop surface, however, sets up toroidal circulation currents in the drop that decrease the resistance to mass transfer both inside and outside the drop. The extent of the change depends on the ratio of the viscosities of the internal and external fluids and on the presence or absence of substances such as surfactants that concentrate at the interface. ... [Pg.673]

Stirred suspensions of droplets have proven to be a popular approach for studying the kinetics of liquid-liquid reactions [54-57]. The basic principle is that one liquid phase takes the form of droplets in the other phase when two immiscible liquids are dispersed. The droplet size can be controlled by changing the agitator speed. For droplets with a diameter < 0.15 cm the inside of the drop is essentially stagnant [54], so that mass transfer to the inside surface of the droplet occurs only by diffusion. In many cases, this technique can lack the necessary control over both the interfacial area and the transport step for determination of fundamental interfacial processes [3], but is still of some value as it reproduces conditions in industrial reactors. [Pg.343]

The intensity of mass transfer shown by the mass transfer coefficient depends on the flow processes inside the drop or in its surroundings and, thereby, on the various life stages of the drops. During the drop formation, new interfaces and high concentration gradients are produced near the interface. The contact times between liquid elements of the drop and the surroundings that are near the surface are then extremely short. According to Pick s second law for unsteady diffusion, it follows that for the phase mass transfer coefficient [19] ... [Pg.403]

For the mass transfer on the inside of the drop the equation by Handlos and Baron [20] for oscillating drops ... [Pg.405]

Kamei and Oishi (K2), 1954 waves, onset of rippling, effect of surfactants. Mass transfer agrees with theory only in absence of waves. Experimental determination of pressure drops in air stream flowing countercurrently to liquid films inside columns of 4.5 and 20.3 cm. diameter. Liquids included water, soap solutions, glycerol solutions, JVr = 0.2-250 = 4000-200,000. [Pg.216]

It will be assumed that the reaction A + B takes place only in the dispersed phase, the reactant A is assumed to be insoluble in the continuous phase, but the reactant B will diffuse into the drops. Further it is assumed that inside the drops there is no mixing but only pure molecular diffusion. The diffusivity of B in the dispersed phase is 33b while the mass transfer coefficient outside the drops is m. The partition coefficient of B is Hb and equals the ratio of the concentration of B in the dispersed phase at the interface over the concentration of B in the continuous phase at the interface. [Pg.258]

Thermodynamic non-idealities are taken into account while calculating necessary physical properties such as densities, viscosities, and diffusion coefficients. In addition, non-ideal phase equilibrium behavior is accounted for. In this respect, the Elec-trolyte-NRTL model (see Section 9.4.1) is used and supplied with the relevant parameters from Ref. [50]. The mass transport properties of the packing are described via the correlations from Refs. [59, 61]. This allows the mass transfer coefficients, specific contact area, hold-up and pressure drop as functions of physical properties and hydrodynamic conditions inside the column to be determined. [Pg.297]

Boston inside-out method. 172-177, 198 Bravo, et al. rfructured packing pressure drop, 447, 499, 500 Bravo Fair et al. mass transfer random packing, 528-530 structured packings, 474, 529, 531, 532 Brown-Martin method, 109 Bryoden method, 161, 162, 175, 176. 179... [Pg.693]

The second necessary condition is isothermal operation. This is apparent from the results of Sections 6.2.3.3 and 6.2.3.4 where it has been shown that heat and mass transport may drive the effective reaction rate in opposite directions. Normally, mass transfer control of a reaction means a drop of the effective reaction rate (for positive reaction order), whereas a limited heat transfer in the case of an exothermal reaction will cause the temperature inside the catalyst pellet to rise, and will thus increase the effective reaction rate. When both effects occur simultaneously, an increase as well as a decrease of the effective rate may be observed, indicating either a lower or a higher apparent activation... [Pg.346]


See other pages where Mass transfer inside drop is mentioned: [Pg.355]    [Pg.226]    [Pg.280]    [Pg.301]    [Pg.393]    [Pg.394]    [Pg.268]    [Pg.268]    [Pg.137]    [Pg.503]    [Pg.54]    [Pg.260]    [Pg.65]    [Pg.24]    [Pg.327]    [Pg.335]    [Pg.514]    [Pg.153]    [Pg.7]    [Pg.130]    [Pg.284]    [Pg.393]    [Pg.647]    [Pg.340]    [Pg.401]   
See also in sourсe #XX -- [ Pg.201 , Pg.225 , Pg.226 ]




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