Study of a Quench Device for the Synthesis and Hydrolysis of Zn Nanoparticles: Modeling and Experiments

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Tareq Abu Hamed ◽  
Luke Venstrom ◽  
Aiman Alshare ◽  
Marc Brülhart ◽  
Jane H. Davidson
Keyword(s):  
Particle Deposition ◽  
Tubular Reactor ◽  
Numerical Data ◽  
Dynamics Modeling ◽  
Computational Fluid Dynamics Modeling ◽  
Confined Jets ◽  
Zinc Nanoparticles ◽  
Modeling And Experiments ◽  
The Impact ◽  
Hydrolysis Of

The synthesis and hydrolysis of zinc nanoparticles are carried out in a tubular reactor. A key component of the reactor is a coaxial jet quench device. Three coaxial and multi-inlet confined jets mix Zn(g), steam, and argon to produce and hydrolyze zinc nanoparticles. The performance of the quench device is assessed with computational fluid dynamics modeling and measurements of hydrogen conversion and particle size and composition. Numerical data elucidate the impact of varying jet flow rates on temperature and velocity distributions within the reactor. Experiments produce hydrogen conversions of 61–79%. Particle deposition on sections of the reactor surface above 650 K favors hydrolysis. Residence time for in-flight particles is less than 1 s and these particles are partially hydrolyzed.

Design of a Quench Device for Synthesis and Hydrolysis of Zn Nanoparticles: Flow Modeling and Experiments

2008 ◽  
Author(s):  
Aiman Alshare ◽  
Tareq Abu Hamed ◽  
Marc Bru¨lhart ◽  
Luke Venstrom ◽  
Jane H. Davidson
Keyword(s):  
Particle Deposition ◽  
Fluid Dynamic ◽  
Tubular Reactor ◽  
Numerical Data ◽  
Confined Jets ◽  
Zinc Nanoparticles ◽  
Modeling And Experiments ◽  
The Impact ◽  
Hydrolysis Of ◽  
Reactor Surface

The synthesis and hydrolysis of zinc nanoparticles are carried out in a tubular reactor. A key component of the reactor is a coaxial jet quench device. Three co-axial and multi-inlet confined jets mix Zn(g), steam and argon to produce and hydrolyze zinc nanoparticles. The performance of the quench device is assessed with computational fluid dynamic modeling and measurements of hydrogen conversion and particle size and composition. Numerical data elucidate the impact of varying jet flow rates on temperature and velocity distributions within the reactor. Experiments produce hydrogen conversions of 61 to 79%. Particle deposition on sections of the reactor surface above 650 K favors hydrolysis. Residence time for in-flight particles is less than one second and these particles are partially hydrolyzed.

CFD Simulation of Heating a Cu Pipe with a Safe H2/O2 Flame

2014 ◽  
Vol 611-612 ◽  
pp. 1553-1559
Author(s):  
Lars Kjäldman ◽  
Jouni Syrjänen
Keyword(s):  
Reasonable Agreement ◽  
Cfd Simulation ◽  
Temperature History ◽  
Measured Temperature ◽  
Dynamics Modeling ◽  
Computational Fluid Dynamics Modeling ◽  
History Of ◽  
Modeling And Experiments ◽  
Simulation Results ◽  
The Eu

As part of the EU/SME project SafeFlame (www.safeflameproject.eu ) the heating of a Cu pipe by a H2/O2 flame has been modeled and the results are compared to experiments. CFD (Computational Fluid Dynamics) modeling has been utilized to study the flow and combustion in the flame and the heat transfer from the flame to the pipe. The simulation results are compared with the measured temperature history of the pipe at different locations and with the visual flame. The influence of distance between the burner and the pipe and of using two opposite H2/O2 flames on the heating rate of the pipe has been investigated. Reasonable agreement between modeling and experiments has been obtained. The reasons for differences between modeling and experimental results are discussed.

Quantitative Computational Fluid Dynamics Analyses of Particle Deposition on a Transonic Axial Compressor Blade—Part I: Particle Zones Impact

2014 ◽  
Vol 137 (2) ◽  
Author(s):  
Alessio Suman ◽  
Rainer Kurz ◽  
Nicola Aldi ◽  
Mirko Morini ◽  
Klaus Brun ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Particle Deposition ◽  
Fluid Dynamic ◽  
Axial Compressor ◽  
Numerical Data ◽  
Suction Side ◽  
Continuous Phase ◽  
Industrial Applications ◽  
Compressor Rotor ◽  
The Impact

Solid particle ingestion is one of the principal degradation mechanisms in the turbine and compressor sections of gas turbines. In particular, in industrial applications, the microparticles that are not captured by the air filtration system cause fouling and, consequently, a performance drop of the compressor. This paper presents three-dimensional numerical simulations of the microparticle ingestion (0 μm–2 μm) on an axial compressor rotor carried out by means of a commercial computational fluid dynamic (CFD) code. Particles of this size can follow the main air flow with relatively little slip, while being impacted by flow turbulence. It is of great interest to the industry to determine which areas of the compressor airfoils are impacted by these small particles. Particle trajectory simulations use a stochastic Lagrangian tracking method that solves the equations of motion separate from the continuous phase. Then, the NASA Rotor 37 is considered as a case study for the numerical investigation. The compressor rotor numerical model and the discrete phase treatment have been validated against the experimental and numerical data available in literature. The number of particles, sizes, and concentrations are specified in order to perform a quantitative analysis of the particle impact on the blade surface. The results show that microparticles tend to follow the flow by impacting at full span with a higher impact concentration on the pressure side (PS). The suction side (SS) is affected only by the impact of the smaller particles (up to 1 μm). Particular fluid dynamic phenomena, such as separation, stagnation point, and tip leakage vortex, strongly influence the impact location of the particles.

Modeling and Experiments of Laser Cladding With Droplet Injection

2005 ◽  
Vol 127 (9) ◽  
pp. 978-986 ◽  
Author(s):  
J. Choi ◽  
L. Han ◽  
Y. Hua
Keyword(s):  
Fluid Flow ◽  
Laser Cladding ◽  
Dynamic Motion ◽  
Cladding Layer ◽  
Melt Pool ◽  
Material Deposition ◽  
Modeling And Experiments ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
The Impact

Laser aided Directed Material Deposition (DMD) is an additive manufacturing process based on laser cladding. A full understanding of laser cladding is essential in order to achieve a steady state and robust DMD process. A two dimensional mathematical model of laser cladding with droplet injection was developed to understand the influence of fluid flow on the mixing, dilution depth, and deposition dimension, while incorporating melting, solidification, and evaporation phenomena. The fluid flow in the melt pool that is driven by thermal capillary convection and an energy balance at the liquid–vapor and the solid–liquid interface was investigated and the impact of the droplets on the melt pool shape and ripple was also studied. Dynamic motion, development of melt pool and the formation of cladding layer were simulated. The simulated results for average surface roughness were compared with the experimental data and showed a comparable trend.

scholarly journals Retraction: Computational fluid dynamics modeling of the millisecond methane steam reforming in microchannel reactors for hydrogen production

RSC Advances ◽  
2021 ◽  
Vol 11 (21) ◽  
pp. 12531-12531
Author(s):  
Junjie Chen ◽  
Xuhui Gao ◽  
Longfei Yan ◽  
Deguang Xu
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Hydrogen Production ◽  
Steam Reforming ◽  
Methane Steam Reforming ◽  
Dynamics Modeling ◽  
Computational Fluid Dynamics Modeling ◽  
Microchannel Reactors ◽  
Methane Steam

Retraction of ‘Computational fluid dynamics modeling of the millisecond methane steam reforming in microchannel reactors for hydrogen production’ by Junjie Chen et al., RSC Adv., 2018, 8, 25183–25200, DOI: 10.1039/C8RA04440F.

scholarly journals Salivary Digestion Extends the Range of Sugar-Aversions in the German Cockroach

Insects ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 263
Author(s):  
Ayako Wada-Katsumata ◽  
Coby Schal
Keyword(s):  
Rapid Evolution ◽  
German Cockroach ◽  
Gustatory System ◽  
Resistance Trait ◽  
Cockroach Blattella Germanica ◽  
Behavioral Resistance ◽  
Gustatory Information ◽  
The Impact ◽  
Hydrolysis Of ◽  
Glucose Aversion

Saliva has diverse functions in feeding behavior of animals. However, the impact of salivary digestion of food on insect gustatory information processing is poorly documented. Glucose-aversion (GA) in the German cockroach, Blattella germanica, is a highly adaptive heritable behavioral resistance trait that protects the cockroach from ingesting glucose-containing-insecticide-baits. In this study, we confirmed that GA cockroaches rejected glucose, but they accepted oligosaccharides. However, whereas wild-type cockroaches that accepted glucose also satiated on oligosaccharides, GA cockroaches ceased ingesting the oligosaccharides within seconds, resulting in significantly lower consumption. We hypothesized that saliva might hydrolyze oligosaccharides, releasing glucose and terminating feeding. By mixing artificially collected cockroach saliva with various oligosaccharides, we demonstrated oligosaccharide-aversion in GA cockroaches. Acarbose, an alpha-glucosidase inhibitor, prevented the accumulation of glucose and rescued the phagostimulatory response and ingestion of oligosaccharides. Our results indicate that pre-oral and oral hydrolysis of oligosaccharides by salivary alpha-glucosidases released glucose, which was then processed by the gustatory system of GA cockroaches as a deterrent and caused the rejection of food. We suggest that the genetic mechanism of glucose-aversion support an extended aversion phenotype that includes glucose-containing oligosaccharides. Salivary digestion protects the cockroach from ingesting toxic chemicals and thus could support the rapid evolution of behavioral and physiological resistance in cockroach populations.

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