  Simulations of Structures in Packed Columns and Validation by X-ray Tomography; ; et al in Industrial & Engineering Chemistry Research (2009), 48(1), 202-213 Packing simulations of generic, nonspherical pellets were performed and compared with experimental data sets obtained using X-ray Computerized tomography (CT). Two modified versions of what was previously ... [more ▼] Packing simulations of generic, nonspherical pellets were performed and compared with experimental data sets obtained using X-ray Computerized tomography (CT). Two modified versions of what was previously a purely geometrical, digitally based packing algorithm were implemented. Both are aimed at incorporating the effects of particle interaction forces, one utilizing the distinct element method (DigiDEM) and the other an intermediate solution (collision-guided packing or DigiCGP). This article summarizes the models and the simulations performed using these two modified versions of DigiPac and, for model validation purposes, compares the predicted results with the corresponding X-ray tomographic scans of packed columns, in terms of bulk density, local packing density profiles, and pellet orientation distributions. For packed beds of relatively large and identical pellets, the simulation results indicate that particle-particle and particle-wall interactions cannot be ignored if realistic packing structures are to be obtained by simulation and even a simplistic treatment of these interactions can produce significantly more realistic packing structure than none at all. [less ▲] Detailed reference viewed: 76 (9 ULg)New Insights into Pervaporation Mass Transport under Increasing Downstream Pressure Conditions: Critical Role of Inert Gas Entrance.; ; et al in Industrial & Engineering Chemistry Research (2001), 40 The influence of the total downstream pressure on the pervaporation flux of a pure compound through a dense polymer membrane has been the subject to controversial debates recently. Experimental arguments ... [more ▼] The influence of the total downstream pressure on the pervaporation flux of a pure compound through a dense polymer membrane has been the subject to controversial debates recently. Experimental arguments in favor of either the solution−diffusion model or the newly proposed pore-flow model are alternatively reported on different systems. To critically reexamine this debate, an experimental study under controlled downstream conditions has been performed for pure methanol and pure 2-propanol pervaporation through a poly(dimethylsiloxane) film, the latter having been previously reported to follow pore-flow model predictions. It is shown that a rational analysis of the effects of the downstream pressure on the results can be achieved according to the classical solution−diffusion model, provided that the influence of air leaks in the installation is properly taken into account. Based on this observation, the implications of an inert gas contribution, generally speaking, on pervaporation operation are discussed. [less ▲] Detailed reference viewed: 52 (9 ULg) |
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