GOALI: Fluid Dynamics, Heat Transfer, and Crystal Growth in Solvothermal Reactors: Modeling, Scaling, and Validation

点击翻译按钮获取中文摘要

CBET-1336700PI: Chandy This industry-university collaborative project will develop and experimentally validate a computational fluid dynamics (CFD)-based model for crystal growth in supercritical fluids, with the goal of: (i) creating an integrated predictive thermofluid-mass transfer methodological approach and tool for crystal growth modeling, and (ii) demonstrating and applying the tools to optimization of an ammonothermal process for growth of single crystal gallium nitride (GaN), laying the groundwork for scale up of prototype and small scale reactors to a bulk manufacturing process and capability. Three critical areas will be considered: crystal growth numerical model, apparatus scale-up, and reactor optimization for enhanced mass transport. While several CFD simulations of hydrothermal and ammonothermal crystal growth processes have been conducted in the past, they have involved restrictive, simplified assumptions, extremely crude crystal growth models, and have not been validated experimentally. Not only does this research propose to create a more realistic growth model, but most importantly it intends to validate it experimentally. Like in many hybrid numerical/experimental undertakings, the strategy will be to use the experimental work for providing added insight for modeling while at the same time looking at the numerical work to guide the experimental work. This approach will advance a multi-scale, multi-physics phenomena modeling whereby the crystal growth model will benefit from seamless integration of 3-D momentum, energy and mass transfer 3-D equations (rather than 2-D axisymmetric) applied to a free convection environment. This research will for the first time, offer: (a) an experimentally 3-D computational tool for solvothermal crystal growth accounting jointly for turbulence, heat transfer, mass etching and deposition in a realistic reactor architecture of crystal seeds and porous nutrient; (b)concomitant experimental validation of the integrated multiphysics code (c) use experimental work to establish valid rules for geometric and dynamic similitude scaling for flows and reactor design; and (d) establish an assignment map between the calculated Rayleigh numbers and the types of flow regimes experimentally observed in cylindrical geometries with axisymmetric lateral heating.Fundamentally, the integrated experimental and numerical research will make a significant contribution to the general understanding of thermally driven fluid mechanics interacting with porous media as well as the associated surface reaction chemistry. In particular the model will be applied to closed cylindrical enclosures with laterally axisymmetric heated walls. The study will enable substantial process development through optimization of flow, heat and mass transfer, confident scale-up of processes in large, capital-intensive reactors, lower cost of design and construction of ammonothermal process reactors. SORAA and possibly other new entrants will stand to benefit significantly from the availability of a validated predictive and design numerical tool. The experiments developed in this program will form the basis of fluid mechanics training workshops for students at various levels with the added potential of providing some useful insights into other applications related to free convection. The broader impact and outreach activities that are centered on the experiments and simulations are aimed at increasing graduate research in Engineering at University of Akron, through enhancement of research and education partnerships. The knowledge gained from this study are expected to impact diverse processes in supercritical fluids, including synthesis of nanoparticles, zeolites, and novel materials and pyrolysis of waste materials.