Computational Modeling of Compressible Gas flow through a High Temperature Reducing Jet Reactor
Martin, Gary Floriano
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This thesis presents a modeling study of a novel reactor used for the production of nano-particles of copper, silver and other metals. In this High Temperature Reducing Jet (HTRJ) process, a metal salt solution is injected into a high temperature gas stream consisting of a uniform mixture of hydrogen, nitrogen and water vapor (produced by hydrogen combustion), flowing at high velocity, which leads to the evaporation of the solvent, and the evaporation or sublimation of the metal salt precursor. The resultant gas-phase molecules then decompose to produce metal atoms or metal oxide molecules, from which particles nucleate. The fluid dynamics inside the reactor is of vital importance to this process, and the behavior of the gases inside the reactor needs to be studied. Using computational modeling, incorporated in ANSYS CFX, a uniform mixture of hydrogen, nitrogen and oxygen gases are passed in through the main inlet of the reactor at varying temperatures and under steady state conditions and water vapor is passed in through the side inlets. The non-reacted fluid mass and heat transfer characteristics are studied. The multi-domain analysis tool available in ANSYS CFX enables the inclusion of the solid wall domain around the fluid domain, which aids in the study of the heat loss through the stainless steel walls of the reactor. Finally, the reactor simulation is run at the theoretical adiabatic flame temperature with the combustion products that are nitrogen, excess unreacted hydrogen and water vapor flowing into the reactor and the fluid mass and heat transfer characteristics are again studied, along with the heat flux through the walls of the reactor.