Mass interchange

Here it is supposed, that the crystals of each fraction contribute to the total current independently, i.e. the mass interchange between separate cells is disregarded. The latter is possible in the case when the packing density of the reagent crystals in a porous matrix is low and the distance between the crystals is much greater than the average radius of the crystals. 

A realistic treatment of mass transfer between the gas and solid phases requires consideration of the bed structure comprising the bubble phase and the emulsion phase (see 9.4). Considering bubbles containing species A passing through a fluidized bed where species A is in depletion, the mass transfer, or the mass interchange coefficient from the bubble phase to the emulsion phase, K, can be related to the difference in the concentration of species A in the bubble phase, CAib, and that in the emulsion phase, CA,e, by [Kunii and Levenspiel, 1968]... 

A balance on mechanical energy can be written on a microscopic basis for an elemental volume by taking the scalar product of the local velocity and the equation of motion. After integration over the entire volume of the system the steady-state mechanical energy balance for a system with mass interchange with the surroundings becomes, on a per unit mass basis,... 

Even mass spectroscopists use the terms exact mass and accurate mass interchangeably when they probably should not. An exact molecular mass is the mass calculated from the accepted exact atomic masses of the isotopes for a specified empirical formula. It is the value that one would expect to observe if one could measure a molecular mass exactly. An accurate mass is a value measured carefully, with high precision, on an instrument capable of making such precise measurements, typically expressed to at least four decimal places—the nearest 0.1 mDa. An accurate mass measurement is compared to the exact masses of empirical formulae being considered. Sufficiently accurate measurements can be used to assign empirical formulae to peaks in a mass spectrum. Knowing that these two terms are commonly used interchangeably, but that there may be subtle differences in the way practitioners use them, is sufficient for our discussions here. We will comment more on the utility of accurate mass measurements later. 

Boukalouch, M., J. Elezgaray, A. Ameodo, J. Boissonade P. De Kepper. 1987. Oscillatory instability induced by mass interchange between two coupled steady-state reactors. J. Phys. Chem. 91 5843-5. 

The first approach, which considers a single phase, proposes conventional multiphase flow models, such as ideal flow, dispersion, and residence time distribution models. The second approach, which takes into account two phases as bubble and emulsion, suggests different governing equations for each phase and considers a term for describing mass interchange between the two phases. 

Boukalouch, M. Elezgaray, J. Arneodo, A. Boissonade, J. De Kepper, P. 1987. Oscillatory Instability by Mass Interchange between Two Coupled Steady-State Reactors, J. Phys. Chem. 91, 5843-5845. 

The additional terms must be added to the right-hand side of E. (1) in this case (mass interchanges and energy release due to burning). New equations of combustion kinetics have also to be added. 

Chemists often use the terms atomic weight and atomic mass interchangeably. Explain why it would be more accurate if, in place of either of these terms, we used the phrase average atomic mass. ... 

In most two-phase models, a fluidized bed is considered to consist of two distinct phases, i.e., a bubble phase and an emulsion phase. Each phase is represented by a separate governing equation with a term in each equation describing mass interchange between the two phases. A general expression of the two-phase models, therefore, consists of the following two equations (from Wen and Fan, 1975). For the bubble phase we have... 

Gas interchange takes place between the two phases. The overall mass interchange coefficient per unit volume of gas bubbles is given by... 

The above equation can be converted to. fiioT, the mass interchange coefficient per unit volume of bubble, based on the appropriate surface-to-volume ratio, i.e.. 

Heat exchangers allow thermal interchange (but not necessarily mass interchange) between flowing streams. The streams are usually separated from each other by a solid wall. Hence, we have a combination of convection heat transfer (the flowing streams) together with conduction heat transfer (through the solid surfaces). 

Z-5.2.2 Turbulent Flow Regime. With turbulent flow there is mass interchange in both the radial and axial directions, due to turbulent eddies. Radial mixing has been summarized extensively by Gray (1986). The study by Ger and... 

Bubble-cloud mass interchange coeflhcient (m /m s) Interfacial mass transfer coefficient (m/s)... 

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