Pore-Scale Modeling of Mineral Growth and Nucleation in Reactive Flow

A fundamental understanding of mineral precipitation kinetics relies largely on microscopic observations of the dynamics of mineral surfaces exposed to supersaturated solutions. Deconvolution of tightly bound transport, surface reaction, and crystal nucleation phenomena still remains one of the main challenges. Particularly, the influence of these processes on texture and morphology of mineral precipitate remains unclear. This study presents a coupling of pore-scale reactive transport modeling with the Arbitrary Lagrangian-Eulerian approach for tracking evolution of explicit solid interface during mineral precipitation. It incorporates a heterogeneous nucleation mechanism according to Classical Nucleation Theory which can be turned “on” or “off.” This approach allows us to demonstrate the role of nucleation on precipitate texture with a focus at micrometer scale. In this work precipitate formation is modeled on a 10 micrometer radius particle in reactive flow. The evolution of explicit interface accounts for the surface curvature which is crucial at this scale in the regime of emerging instabilities. The results illustrate how the surface reaction and reactive fluid flow affect the shape of precipitate on a solid particle. It is shown that nucleation promotes the formation of irregularly shaped precipitate and diminishes the effect of the flow on the asymmetry of precipitation around the particle. The observed differences in precipitate structure are expected to be an important benchmark for reaction-driven precipitation in natural environments.

Significance of heat conduction in binary reactive flow of Walter’s B fluid with radiative flux and activation energy

The prime objective of binary chemical reaction (BCR) is concentrated on the study and optimization of chemical reaction to accomplish finest reactor design and performance, which elaborated the interfaces of flow phenomena, reaction kinetics and heat and mass transport. The reactor performance is likely to be linked to the reaction operating constraints and feed composition through the aforementioned factors. The applications of BCR are generally in the petroleum and petrochemical regions, but with the help of chemical engineering and reaction chemistry concepts, it could be used in different areas, like waste treatment, chemical pharmaceuticals, nanoparticles in advanced materials, microelectronics, enzyme technology, biochemical engineering, living systems, renewable energy systems, sustainable development, environment/pollution prevention, as well as to optimize a different reaction framework via simulation and modeling methodology. Owing such physical applications in mind, this research deals with the binary chemical reactive flow of non-Newtonian fluid (Walter’s B) subject to activation energy. Stagnation point is accounted. Radiative flux and ohmic heating effects are considered in the development of energy expression. Concentration and microorganism equations are considered. The governing system is altered to ordinary one through the important similarity variables. Results are obtained through bvp4c technique. All results are discussed graphically. Furthermore, surface drag force (skin friction) and heat and mass transfer (Nusselt and Sherwood) rates are calculated and displayed graphically. Significant results are listed in conclusion.

Using In Situ Measurements to Experimentally Characterize TiO2 Nanoparticle Synthesis in a Turbulent Isopropyl Alcohol Flame

The objective of the present work is to show the potential of in situ measurements for the investigation of nanoparticles production in turbulent spray flames. This is achieved by considering multiple diagnostics to characterize the liquid break-up, the reactive flow and the particles production in a spray burner for TiO2 nanoparticle synthesis. The considered liquid fuel is a solution of isopropyl alcohol and titanium tetraisopropoxide (TTIP) precursor. Measurements show that shadowgraphy can be used to simultaneously localize spray and nanoparticles, light scattering allows to characterize the TiO2 nanoparticles distribution in the flame central plane, and spontaneous CH* and OH* chemiluminescences, as well as global light emission results, can be used to visualize the reactive flow patterns that may differ with and without injection of TTIP. Concerning the liquid, it is observed that it is localized in a small region close to the injector nozzle where it is dispersed by the oxygen flow resulting in droplets. The liquid droplets rapidly evaporate and TTIP is quasi-immediately converted to TiO2 nanoparticles. Finally, results show high interactions between nanoparticles and the turbulent eddies.