Modeling of heat transfer and reactive chemistry for particles in gas-solid flow utilizing continuum-discrete methodology (CDM)

A comprehensive multi-phase flow model requires coupled hydrodynamics, boundary conditions, heat and mass transfer, and chemical reaction kinetics. A model must also capture the multi-scale nature of these problems. Computational fluid dynamics-discrete element method (CFD-DEM) provides an accurate description of chemical reactions and heat and mass transfer at the particle scale. Currently, MFIX-DEM, the existing CFD-DEM used as the foundation for this work, can only model coupled hydrodynamics. This dissertation extends the functionality of MFIX-DEM by addressing the remaining deficiencies in three separate efforts.;The first effort outlined in this dissertation focuses on the algorithmic development of discrete mass inflow and outflow boundary conditions. This approach allows for the construction of more dynamic models of gas-solid systems. It permits the amount and type of particles to fluctuate during a simulation. Examples illustrating the added functionality are provided.;The second investigation explores the three modes of heat transfer in gas-solids systems. Models for particle-particle contact conduction, particle-fluid-particle conduction, particle-gas convection, and particle-particle radiation are selected. Model selection is based on model simplicity, acceptance in existing CFD-DEM heat transfer models, extendibility to particles of different sizes, and computational expense. Modifications are made to selected models before implementing them into MFIX-DEM. The implementation of each model is verified for simple two particle test cases, or in the case of gas-particle convection, a single fixed particle in a flowing gas. Strong agreement is observed between the simulation data and the analytic or numerical solution.;Finally, a mathematical interface for managing user-defined particle-gas chemical reactions is developed. The shrinking, unreacted core model is selected as the particle reaction model for its accurate physical account of particle-gas reactions and ability to allow particles to initially contain inert material. The implementation of the reactive chemistry interface is verified for a single reacting particle. Strong agreement is observed between simulation data and the analytic solutions for the particle\u27s mass, species mass fraction, and internal energy equations. Agreement between the simulation data and analytic solution for the shrinking, unreacted core is considered acceptable