Chul Kwak

Frequency response of continuous-flow adsorber for multicomponent system

In this paper, we present a theoretical analysis of the frequency response of a continuous-flow adsorber with periodic modulation of the inlet flow-rate to measure multicomponent diffusion kinetics in porous media. Micropore diffusion kinetics is assumed for the intraparticle mass transfer mechanism and three different shapes of microparticle are considered: slab, cylinder, and sphere. Simulation results for a binary system show that the frequency response of the faster diffusing component is strongly influenced by the slower component. The out-of-phase characteristic function of the frequency response of the faster diffusing component shows maximum and minimum points. The deviation between these maximum and minimum values becomes smaller when the cross-terms of diffusivity go to zero, while the deviation becomes larger when the cross-terms of the adsorption equilibrium constant go to zero. Contrary to the behaviour of the out-of-phase function of the faster diffusing component, the out-of-phase function of the slower diffusing component shows no extrema at all. The in-phase characteristic function of the frequency response of the continuous-flow adsorber is not affected by the overflow parameter.

Frequency response of adsorption of a gas onto bidisperse pore-structured solid with modulation of inlet molar flow-rate

We present a theoretical analysis of the frequency response of a continuous-flow adsorber for adsorption of a gas onto bidisperse pore-structured solid, forced by the periodic modulation of the inlet flow-rate. Spherical macroparticle and spherical microparticle geometries are considered. A local adsorption equilibrium of the gas on the exterior surface of microparticle is assumed. It is confirmed that the in-phase characteristic function of the frequency response of a flow adsorber is independent of the overflow parameter, but that the out-of-phase characteristic function is a strong function of the overflow in the lower frequency region. The overall characteristic functions in the microparticle diffusion regime have information of both microparticle diffusion and macropore diffusion. Hence, in this regime we can extract the macropore diffusion parameter as well as the microparticle diffusion parameter from the experimental data of the overall characteristic functions. In the microparticle diffusion regime the capacity parameter of microparticle affects also the characteristic functions.

Application of peng-Robinson equation to high-pressure aqueous systems containing gases and sodium chloride

A novel approach is proposed for modeling vapor-liquid equilibria in systems containing aqueous NaCl and supercritical gases. The Peng-Robinson equation of state is used for all species, with the salt treated as a hypothetical liquid component. To correctly model the highly non-ideal liquid solution, a two-fluid model is used for the mixing rules in the equation of state. Effective pure-component parameters are reported for NaCl as well as binary interaction parameters for all possible binaries. Representation of high-pressure phase equilibria data show good agreement with experimental data. The principal advantage of this approach is the ability to treat high pressure systems containing non-volatile salts, while maintaining the simplicity of a cubic equation of state.