Condensation of vapor mixtures. 1. Nonequilibrium models and design procedures

Abstract

Nonequilibrium models of multicomponent condensation are reviewed with particular attention to the various ways in which the rates of condensation can be calculated. Ways of solving the mixed set of differential and algebraic equations that constitute the model are discussed, and it is suggested that differential conservation equations be approximated by finite differences and the resulting set of only algebraic equations solved simultaneously (using Newton's method) with the nonlinear equations representing the processes of Interphase transport and interfacial ' equilibrium. With regard to the various models of vapor-phase transport, it is shown that simple effective dlffusivity models may lead to significant over-or underdesign when compared to more soundly based models which take vapor-phase diffusional interaction effects into account. It Is also demonstrated that there is little to distinguish models based on the use of the Chilton-Colburn analogy to obtain the heatand mass-transfer coefficients from turbulent eddy diffusivity models when both are used to predict the performance of multicomponent condensers.

Condensers

“…A rigorous formulation of the general multi-component condensation problem has been presented by Taylor et al [33]. Due to the inherent complexity of the model, however, it has not been widely used for equipment design.…”

Numerical study of heat and mass transfer of binary mixtures condensation in mini-channels

“…They reached the conclusion that there can be a very considerable different between these two extremes at the higher percentages of vapor condensed if all the components are condensable. Moreover, it is was also stated that there is no significant difference between the two extremes if there is a non-condensing or sparingly soluble gas present in the vapor stream in the works by Krishna et al [72], Webb and Sardesai [124], Taylor and Noah [111], and Taylor et al [110].…”

“…Taylor et al [110] stated that the former is applicable to vertical condensers where the two phases remain in close proximity, the latter to horizontal condensers where the condensate is continuously separated from the vapor. They reached the conclusion that there can be a very considerable different between these two extremes at the higher percentages of vapor condensed if all the components are condensable.…”

“…In order to calculate multicomponent gas phase mass transfer coefficients and transfer rates, they also developed a general matrix method for solving the Maxwell-Stefan equations [73]. A series of relating works improved the modeling and design procedures for condensation of multicomponent can found in Krishna [71], and Taylor et al [110], etc.…”

Numerical Study of the Condensation Length of Binary Zeotropic Mixtures

“…Additionally, the heat and mass resistances discussed in the following sections are restricted to the resistances in the vapor phase. Most prior work in the literature used two limiting conditions, namely perfect-mixing and no-mixing, to evaluate the mass diffusion in the liquid phase (for example [6]), and it is stated that the former is applicable to vertical condensers where the two phases remain in close proximity, while the latter is applicable to horizontal condensers where the condensate is continuously separated from the vapor [7]. Therefore, the perfect-mixing assumption is reasonable for the in-tube condensation in the present study.…”