Polydisperse Model Research Articles

Polydisperse model of the VPE extractor hydrodynamics

A computer simulation model of the dispersed phase holdup in the vibrating-plate extractor was developed. Drop transport, breakage and coalescence equation were solved simultaneously, the stage being divided in the internal part and in the dense-packed layer of dispersion at the plate. The verified simulator can be used to predict and to analyse both steady state holdup and its dynamics and it can help to design a VPE extractor or a pulsed sieve-plate extractor. Holdup measured in a VPE column with toluene dispersed in water without mass transfer was simulated by the model with a standard deviation 6% rel. in the whole range from the mixer-settler region to the emulsion region.

Critical point measurements on nearly polydisperse fluids

AbstractThe critical temperatures, pressures and volumes of several mixtures containing CO2, C2H6, C3H8, and C4H10 have been measured using a heavy walled, variable volume, cylindrical glass vessel. In each mixturre the relative proportions of the three hydrocarbon solutes to one another were changed; total solute mole fraction never exceeded 0.1. A detailed study of the mixture CO2 + C3H8 shows that the critical temperature exhibits a minimum at a C3H8 mole fraction of 0.0265. Our mixture data are analyzed using a polydisperse model of dilute solutions.

A Model of dispersion hydrodynamics in a vibrating plate extractor

A stagewise polydisperse model of the Karr vibrating plate extractor hydrodynamics is presented. It describes the drop size distribution and the dispersed phase hold-up as functions of drop transport, breakage and coalescence. 1 1 Binary system without mass transfer is considered. The predicted stationary hold-up profiles and drop size distributions are proved to be in good agreement with the experimental data.

Counter-current flow of dispersed and continuous phase—III Measurements of hold-up profiles and particle size distributions in a vibrating plate contactor

This paper reports on measurements of hold-up profiles and particle size distributions in a Karr vibrating plate contactor. A wide range of working conditions of the contactor has been investigated and results confirming the simulations by means of a discrete polydisperse model[1,2] have been obtained. A quantitative comparison of experimental results with the lumped parameter model derived from the polydisperse one has shown that, having considered the inhomogeneity of the hold-up within the stages a good agreement between the measured and calculated hold-up profiles can be obtained. The lumped parameter model has also been employed to calculate the distribution of particle sources and sinks along the column.

Counter-current flow of dispersed and continuous phase—II: Simulation of hold-up and particle size distribution profiles

An iterative algorithm is proposed for the solution of the discrete polydispersed model presented in proceeding paper[1]. Case studies are used to demonstrate the influence of individual model parameters on the hold-up of the dispersed phase particle size distribution profiles. The impact is discussed of these phenomena on the operation of a continuous column extractor. Discrete particle size distributions with various numbers of size classes are studied in order to assess the effect of this parameter on the adequacy of the simulation. A possibility is shown of simulating the state of column flooding in order to examine the influence of selected parameters on the limiting flow rates of phases.

Counter-current flow of dispersed and continuous phase—I: Discrete polydispersed model

A discrete mathematical model has been proposed of the counter-current gravitational flow of a continuous and a polydispersed phase in vertical column contactors. Allowances have been made for particle entrainment, newly defined back flow of particles in relation to the back flow of the continuous phase, particle dispersion and coalescence. Appropriate solutions enable profiles to be obtained of local hold-up of the dispersed phase as well as those of particle size distribution along the contactor's length. The model with the parameters distributed with respect to particle size has served to derive in turn a lumped parameter modification whose limits of applicability have been shown.

Pressure drop and diffusional deposition of aerosol in polydisperse model filter

The pressure drop, flow field, and diffusional deposition of aerosols in the simplest model of polydisperse fibrous filter consisting of rows of parallel cylinders with different radii arranged perpendicular to the flow direction has been studied at low Reynolds numbers. It has been shown that the pressure drop and the diffusional particle deposition can be calculated from the mean cylinder radius even when the radii differ several times.