Patrick M. Piccione

A framework for the design of reacting systems with phase transfer catalysis

Abstract A generic modelling framework for phase transition catalyst based reacting systems has been developed and converted into a software tool. The modelling framework accommodates models of different types representing different sub-systems of the PTC-based reactive system; databases of model parameters and carefully collected and checked (for thermodynamic consistency) experimentally measured data. The models, data and software have been tested on various PTC-based reactive systems. Illustrative examples are provided.

Modeling and design of reacting systems with phase transfer catalysis

Abstract Issues related to the design of biphasic (liquid) catalytic reaction operations are discussed. A chemical system involving the reaction of an organic-phase soluble reactant (A) with an aqueous-phase soluble reactant (B) in the presence of phase transfer catalyst (PTC) is modeled and based on it, some of the design issues related to improved reaction operation are analyzed. Since the solubility of the different forms of the PTC in the organic solvent affects ultimately the catalyst partition coefficients, therefore, the organic solvent plays an important role in the design of PTC-based reacting systems. A model-based strategy for the selection of the best organic solvent/catalyst that improves the reaction operation is highlighted for the reacting system: benzyl chloride (A) and sodium bromide (B) reacting through tetrabutylammonium bromide (PTC).

Industrial Reflections on Modelling of Fine Chemicals and Seeds Process/Product Design

Abstract Chemical engineering relies heavily on numerical, quantitative descriptions of physical and chemical processes. With the advent of modern hardware, all practising engineers have at their disposal computational power undreamed of half a century ago. Although software improvements have followed a similar trend, the expectations in terms of quality (cost, speed and accuracy of predictions, etc.) of process development have followed suit as well. Typical scientific problems addressed through modelling are exemplified within the agri-business company employing the author. Successes and limitations of various approaches are pinpointed through the lens of various application areas. Problems deserving further study are also delineated, as a challenge and opportunity to the modelling community. Implementation and education perspectives conclude these reflections. Modelling remains not only a critical enabler in the scientific workflow, but also an active, fertile area of research.

A two-layer identification strategy for the development of stochastic models of the travelling traders’ exchange problem

The travelling traders’ exchange problem (TTEP) is a general mathematical problem arising in a number of applications where the purpose is to characterise the distribution of money over time related to a population of traders which can move in space and interact with each other. Results from stochastic simulations of TTEP models can be analysed over time in terms of i) standard deviation (STD); ii) probability density function (PDF) of the observations in time. A two-layer model identification strategy is proposed in this paper for the development of time-dependent nonlinear regression models from the results of TTEP computational stochastic simulations. The models are capable of representing the money distribution as a function of the TTEP operating parameters, paving the way to a new framework for model identification.

Analysis of seed processing by the distinct element method

The undesirable breakage of seeds during processing may result in quality degradation. Seeds experience a portfolio of shear and impact stresses as they flow through various machinery, and this may cause surface damage as well as integral damage. An in-depth study and understanding of the microscopic mechanisms of the various processes is needed to investigate and address the problem of breakage. The main aim of this work is to carry out a parametric study of the effect of sliding and rolling friction on the flow field of seeds in a seed coater device by modeling particles motion using Distinct Element Method (DEM). It was found that sliding friction plays an important role in changing the flow pattern and particles solid fraction in a specified measurement cell. However, study of particle rolling friction showed that flow pattern and solid fraction of particles will not be affected once the coefficient of rolling friction exceeds a value of 0.1.