A feasibility-based algorithm for Computer Aided Molecular and Process Design of solvent-based separation systems

Computer-aided molecular and product design (CAMPD) can in principle be used to find simultaneously the optimal conditions in separation processes and the structure of the optimal solvents. In many cases, however, the solution of CAMPD problems is challenging. In this paper, we propose a solution approach for the CAMPD of solvent-based separation systems in which implicit constraints on phase behaviour in process models are used to test the feasibility of the process and solvent domains. The tests not only eliminate infeasible molecules from the search space but also infeasible combinations of solvent molecules and process conditions. The tests also provide bounds for the optimization of the process model (primal problem) for each solvent, facilitating numerical solution. This is demonstrated on a prototypical natural gas purification process

Modelling of droplet absorption and evaporation during pharmaceutical tablet coating

The shelf life of a pharmaceutical tablet is affected by the amount of water that interacts with it during the aqueous film coating process. The purpose of this work is to simulate the spreading, absorption and evaporation of water droplets after impact on a porous tablet core. We divided the spreading, absorption and evaporation phenomena into three separate phases: the kinematic, the capillary and the evaporation phases. For the kinematic phase, we modified 1-D spreading models found in the literature which solve the kinetic energy balance equation. Subsequently, for the capillary phase we solved the Navier-Stokes equation using the lubrication approximation theory. For the evaporation phase, we developed a novel model that treats the tablet as a particle with a wet core surrounded by a dry crust. Our numerical results were in good agreement with recent experimental data found in the literature