GOALI: Population Balance Modeling: Fundamental Closures and Experimental Validation

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In nature, the flow of solid particles in avalanches and landslides can lead to quite devastating effects. In industrial processing, the flow of solid particles is inherent to the production of pharmaceuticals, oil and gas, chemicals, and agricultural products. To avoid comparable adverse effects, such as industrial accidents and lost productivity, it is important to predict and control the flow of these granular systems. However, the flow of solid particles is poorly understood and not easily modeled. Whereas models of liquid flow are a basic tenant of engineering and derived from basic physical principles, current models of solid particle flow rely on adjustable parameters, are empirical, and incorporate a number of gross simplifications. This research project uses computer simulations and state-of-the-art experiments to develop and validate theoretical models of flows of solid particles that are based on measurable quantities. In addition, this work supports the involvement of underrepresented groups, the training of junior researchers and students, and the involvement of students in an industrial-academic research partnership. Results from the project will be communicated to the general public via blog posts and a Twitter account.This project is focusing on the reliable prediction of the mass flow rate of solids when they are fluidized by the upward motion of a flowing gas. Existing empirical correlations for particle entrainment rate constants may vary by many orders of magnitude when applied to the same system. Current models are primarily limited by empiricism and development to a very particular situation. To develop a predictive understanding of fluidized granular systems, this research is deriving a closure for the continuum theory that is based on population and kinetic theory balances. The resulting model for cohesive-particle flows will require only measurable, physical quantities as inputs. The new continuum framework is being applied to the case of humidity-induced agglomeration. Numerical modeling with discrete element method simulations is being combined with non-intrusive shadowgraphy experiments to validate the new theory. A unique aspect of the work is the development of a novel microscopic (particle-particle) cohesion model that drives the closure of the macroscopic (continuum) theory.