Degree Type

Dissertation

Date of Award

2012

Degree Name

Doctor of Philosophy

Department

Chemical and Biological Engineering

First Advisor

Rodney O. Fox

Second Advisor

Michael G. Olsen

Abstract

Flash Nanoprecipitation (FNP) is a promising technique for mass production of nanoparticles for use in various areas. Mixing time is such a crucial factor that it affects the particle size distribution as well as the particle morphology. Turbulent mixing in microscale nanoprecipitation reactors, i.e., the planar conned impinging-jet reactor (CIJR) and the multi-inlet vortex reactor (MIVR), is therefore investigated by means of numerical simulations as well as experimental flow visualization methods. In the process of studying, the computational fluid dynamics (CFD) models are validated by comparing simulation results with experimental data. One of the experimental visualization techniques developed in this work uses the phenolphthalein as the tracer that characterizes the acid-base neutralization reaction. Mixing is qualitatively and, by applying a special image processing technique, also quantitatively evaluated. Coherent flow structures are also analyzed through spatial correlation and POD. For the MIVR, the microscopic particle velocimetry (micro-PIV or microPIV) is first employed to measure the velocity field. Results from Reynolds-averaged Navier-Stokes (RANS) simulations and large eddy simulations (LES) are compared to the micro-PIV results. Comparisons show LES is more suitable for simulating flow field in these reactors. In addition, another experimental method developed in this work is also applied to the MIVR, which couples the confocal laser scanning microscopy (CLSM) and the microscopic laser induced fluorescence (micro-LIF). More detailed and quantitatively accurate data are obtained for the CFD model validation. Passive scalar mixing and reactive mixing experiments are both accomplished to quantify the mixing at the maroscale and microscale respectively.

Copyright Owner

Yanxiang Shi

Language

en

File Format

application/pdf

File Size

150 pages

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