Complexes mass transfer coupled with chemical

BIOUPTAKE WHEN MASS TRANSFER IS COUPLED WITH CHEMICAL REACTION (COMPLEX MEDIA)... 

Finally, to conclude our discussion on coupling with chemistry, we should note that in principle fairly complex reaction schemes can be used to define the reaction source terms. However, as in single-phase flows, adding many fast chemical reactions can lead to slow convergence in CFD simulations, and the user is advised to attempt to eliminate instantaneous reaction steps whenever possible. The question of determining the rate constants (and their dependence on temperature) is also an important consideration. Ideally, this should be done under laboratory conditions for which the mass/heat-transfer rates are all faster than those likely to occur in the production-scale reactor. Note that it is not necessary to completely eliminate mass/heat-transfer limitations to determine usable rate parameters. Indeed, as long as the rate parameters found in the lab are reliable under well-mixed (vs. perfect-mixed) conditions, the actual mass/ heat-transfer rates in the reactor will be lower, leading to accurate predictions of chemical species under mass/heat-transfer-limited conditions. 

When we react a gas with a liquid or react two immiscible liquids, mass transfer occurs simultaneously with reaction. Thus, chemical kinetics is coupled with mass transport, which means we are no longer conducting a reaction, rather, we are managing a complex chemical-physical process. Such processes are usually diffusion rate limited, especially if the gas is sparingly soluble in the liquid or if one liquid is sparingly soluble in a second liquid. 

Perhaps the most remarkable feature of PTR-MS is the special Cl mode through well-controlled proton transfer reaction, in which the neutral molecule M may be converted to a nearly unique protonated molecular ion MH+. This ionization mode is completely different from traditional mass spectrometry (MS) where electron impact (El) with energy of 70 eV is often used to ionize chemicals like VOCs. Although the El source has been widely used with the commercial MS instruments most coupled with a variety of chromatography techniques, these MS platforms have a major deficiency in the course of ionization, the molecule will be dissociated to many fragment ions. This extensive fragmentation may result in complex mass spectra especially when a mixture... 

Combustion of synthetic (polymeric) polymer materials is characterized by a complex coupling between condensed and gas phase phenomena. Furthermore, the phenomena in each phase consist of a complex coupling of chemical reactions with heat and mass transfer processes. 

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