The present research project aims to develop suitable fluid dynamic models for the simulation of hydrodynamic conditions established in chemical engineering equipment, such as spinning disk reactor (SDR) and stirred tank reactor (STR). The research activity will deeply investigate the operative parameters (rotational velocity, temperature, inlet flowrate, feed lines position, impeller clearance) and geometry (disk roughness and dimension, impeller geometry, baffle presence, vessel dimension) influence on mixing conditions (macro, meso and micro-mixing) generated in the above-mentioned reactors. The computational fluid dynamics simulations (CFDS) will be performed to interpret the experimental results obtained in the nanoparticles production field. Several nanoparticle¿s characteristics i.e. mean dimension, diameter distribution, aggregation and morphological structure, are directly influenced by the local mixing conditions established in the specific reactor. Polymeric and metallic nanoparticles employment in environmental, pharmaceutical, medical and food industries was widely increased in the last decade and the physical-chemical characteristics of the produced nanoparticles have to conform to stringent specifications. The experimental data regarding nanoparticles production (mainly metallic iron, titania, magnetite, hydroxyapatite) will be obtained from lab-scale equipment whereas the hydrodynamics experimental results will be taken from the literature. Therefore, the CFDS can be successfully used to compare the results obtained by SDR and STR providing the necessary parameters and knowledge for the industrial scale-up of these technologies and for the prevision of the most suitable operating parameter values to obtain a product with the required specifications.
The simulation of rotating thin fluid film in spinning disk reactor applied to the modeling of nanoparticles production represents a chemical engineering field not still deeply investigated. Considering the wide industrial interest in this intesified production technology and the necessity to provide knowledge and data for a suitable and effective industrial scale-up of SDR equipment, the present proposal may represent a first mile-stone in this field. The potential outstanding of CFD, coupled with lab-experimentations and the knowledge and experience of the research team are a remarkable starting point for the success of the project. The increasing demand of cost-effective and more efficient industrial technologies, that needs to comply with severe environmental and safety regulations, requires the industrial implementation of the most innovative process intensification equipment. SDR represents an effective equipment for the production of innovative nano-materials, that, nowadays, represent a notable incoming for several producing countries. For instance, nano and micro-size titania represents a three-quarters share of the global white pigment market and equates to annual sales of £7 billion (5 million tonnes) in over 170 countries (Hill, market report 2009).
The present research deals with a comprehensive study based on CFD simulations and lab-experiments of SDR and STR application for the production of valuable nanoparticles, employed in various industrial and environmental sectors. The following main achievements are expected:
_ suitable CFD models implementation and validation on commercial codes, able to predict the nanoparticles production performance of SDR;
_ a comparison among the performances of SDR and STR varying the geometries and the operating parameters, mainly in terms of nanoparticles yield/hour, particle size distribution, mean dimension and surface morphology;
_ necessary data and knowledge for the industrial scale-up of the SDR technology applied to the production of nanoparticles.
The obtained results are expected to contribute to a significant knowledge improvement with regards to the hydrodynamic conditions established in SDR of various geometries, their influence on the key-characteristics of the produced nanoparticles (particle size distribution, surface morphology, aggregation tendency) and the effective industrial scale-up of this intensified production technology. These topics still require several and in-depth researches, considering the great potentiality and industrial interest in the SDR technology.