GOALI: Segregation of Sheared Particle Mixtures

Rutgers University New Brunswick, New Brunswick NJ

Investigators

Abstract

National Science Foundation - Division of Chemical &Transport Systems ? Particulate & Multiphase Processes Program (1415) Proposal Number: 0730767 Principal Investigators: Glasser, Benjamin Affiliation: Rutgers University Proposal Title: GOALI: Segregation of Sheared Particle Mixtures Particulate processing operations in a wide variety of industries are often poorly understood compared to their fluid processing counterparts. Product quality and consistency is frequently threatened by problems such as non-uniform flow and segregation of constituent components, the latter being especially significant in pharmaceutical manufacture in which maintenance of a homogenous particle mixture is critical. Traditionally, heuristic rules-of-thumb have been used to limit these problems, but these have not reliably predicted and prevented segregation from occurring during scale-up or commissioning. A more desirable approach, from either a quality control, commercial, or regulatory perspective, is the ability to quantitatively predict flow inhomogeneities and segregation rates from fundamental principles, material properties and small-scale laboratory tests, and then to engineer processes accordingly to limit detrimental effects on performance and product uniformity. While there is a growing theoretical basis for granular flow, this has not yet been applied widely to non-uniform or unsteady flows which are typical of industrial situations. Intellectual Merit: Fundamentally, segregation stems from variations in velocity and flow properties, such as granular temperature, between adjacent regions of a system, preferentially driving particles of a certain type to particular locations. In this university-industry collaborative project we will numerically and experimentally study segregation occurring in the Couette and Taylor-Couette geometries, and cylindrical mixers. Couette and Taylor-Couette flows are perhaps the simplest model geometries encompassing both shear and physical boundary interactions ? essential ingredients of practical flows. While somewhat more complex, cylindrical mixers also encompass both shear and boundary interactions; we will examine flow and segregation in a cylindrical mixer geometry agitated by four pitched blades. Particle dynamic simulation techniques will be used to model particle properties and resulting flows will be compared to results from kinetic theory. Experimental flows will be examined using Particle Image Velocimetry (PIV), stream sampling, and image analysis techniques. The subsequent role of instabilities as triggers for segregation will then be investigated, culminating in calculations of segregation flux for a given particle species. Computational and physical experiments will be used to characterize mixing-segregation transitions in terms of relevant dimensionless groups. Mechanisms of particle segregation triggered by the inhomogeneities will be characterized, for high- and intermediate-shear flows typical of mixing or transport operations. Broader Impacts: The research initiatives in this proposal will be integrated with educational and outreach initiatives including graduate, undergraduate and high school research training in particle technology. Training in particle technology has been recognized as an area of national need but has traditionally been neglected in the US. As part of this proposal, the PI will continue to advance particle technology into the curriculum at Rutgers. High school students will be given the opportunity for research experience through the Governor's School of Engineering, which attracts New Jersey high school students to Rutgers for a high school-university exchange program. Finally, the PI will continue to target the recruitment of women and minorities.