Mass-transfer equipment, description

Abstract The computational mass transfer (CMT) aims to find the concentration profile in process equipment, which is the most important basis for evaluating the process efficiency as well as the effectiveness of an existing mass transfer equipment. This chapter is dedicated to the description of the fundamentals and the recently published models of CMT for obtaining simultaneously the concentration, velocity and temperature distributions. The challenge is the closure of the differential species conservation equation for the mass transfer in a turbulent flow. Two models are presented. The first is a two-equation model termed as model,... 

The present book is devoted to both the experimentally tested micro reactors and micro reaction systems described in current scientific literature as well as the corresponding processes. It will become apparent that many micro reactors at first sight simply consist of a multitude of parallel channels. However, a closer look reveals that the details of fluid dynamics or heat and mass transfer often determine their performance. For this reason, besides the description of the equipment and processes referred to above, this book contains a separate chapter on modeling and simulation of transport phenomena in micro reactors. 

In a sense, all the present papers treat problems in interphase contacting. On the theoretical and observational sides, respectively, Davies and Kintner explore the properties of two-phase systems undergoing mass transfer. In a third study, both the descriptive and the theoretical properties of cocurrent two-phase flow systems are presented by Scott. Longitudinal dispersion (or axial mixing), which has only recently been identified and analyzed as a substantial factor in equipment performance, is reviewed by Levenspiel and Bischoff. 

In this chapter, emphasis will be given to heat transfer in fast fluidized beds between suspension and immersed surfaces to demonstrate how heat transfer depends on gas velocity, solids circulation rate, gas/solid properties, and temperature, as well as on the geometry and size of the heat transfer surfaces. Both radial and axial profiles of heat transfer coefficients are presented to reveal the relations between hydrodynamic features and heat transfer behavior. For the design of commercial equipment, the influence of the length of heat transfer surface and the variation of heat transfer coefficient along the surface will be discussed. These will be followed by a description of current mechanistic models and methods for enhancing heat transfer on large heat transfer surfaces in fast fluidized beds. Heat and mass transfer between gas and solids in fast fluidized beds will then be briefly discussed. 

Included also in this chapter is a qualitative description of separations based on intraphase mass transfer (dialysis, permeation, electrodialysis, etc.) and discussions of the physical property criteria on which the choice of separation operations rests, the economic factors pertinent to equipment design, and an introduction to the synthesis of process flowsheets. 

Molecular engineering still suffers substantial development. Besides heat, mass, and momentum transfer phenomena, commonly used in classical chemical engineering, it is also necessary to introduce the electron transfer phenomenon. Description of the events is based on molecular mechanics, molecular orbits, and electrodynamics. Principal tools and equipment are micro-reactors, membrane systems, micro-analytical sensors, and micro-electronic devices. Output is, generally, demonstrated as molecules, chemicals (solutions), and biochemicals. 

Classical chemical engineering has been intensively developed during the last century. Theoretical backgrounds of momentum, mass, energy balances, and equilibrium states are commonly used as well as chemical thermodynamics and kinetics. Physical and mathematical formalisms are related to heat, mass, and momentum transfer phenomena as well as to homogeneous and heterogeneous catalyses. Entire object models, continuum models, and constrained continuum models are frequently used for the description of the events, and for equipment designing. Usual, principal. 

The description of a gas chromatograph modi ed for the snif ng of its ef uent to determine volatile odor activity was rst published by Fuller et al. [63]. In general, GC-olfactometry (GC-0) is carried out on a standard GC that has been equipped with a snif ng port, also denominated olfactometry port or transfer line, in substitution of, or in addition to, the conventional detector. When a FID or a mass spectrometer is also used, the analytical column ef uent is split and transferred to the conventional detector and to the human nose. GC-0 was a breakthrough in analytical aroma research, enabling the differentiation of a multitude of volatiles, previously separated by GC, in odor active and nonodor active, related to their existing concentrations in the matrix under investi gation. Moreover, it is a unique analytical technique that associates the resolution power of capillary GC with the selectivity and sensitivity of the human nose. 

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