Heat, Mass, and Fluid Flow in a Solar Reactor for Fullerene Synthesis

2001 ◽  
Vol 123 (2) ◽  
pp. 153-159 ◽  
Author(s):  
T. Guillard ◽  
G. Flamant ◽  
D. Laplaze
Keyword(s):  
Numerical Simulation ◽  
Large Scale ◽  
Solar Furnace ◽  
Variable Pressure ◽  
Cooling Zone ◽  
Carbon Vapor ◽  
Solar Reactor ◽  
Wide Range ◽  
Vaporization Process ◽  
Temperature And Pressure

Experimental results with a 2 kW solar furnace, in a wide range of vaporization rates (0.1–4 g/h), under variable pressure and flow rate of argon, are used with numerical simulation to define key parameters for large scale synthesis of fullerenes with solar energy. The vaporization process is controlled by diffusion in the temperature and pressure ranges 3000-3700 K and 70-250 hPa respectively. In the solar reactor, fullerene yield is governed by the dilution of carbon vapor in argon and the temperature gradient in the cooling zone. Criteria for both parameters are suggested. Consequently, these data, combined with a validated numerical model of the reactor, may be used for the design of large-scale solar process.

scholarly journals Heat, Mass and Fluid Flow in a Solar Reactor for Fullerene Synthesis

2001 ◽  
Author(s):  
Tony Guillard ◽  
Gilles Flamant ◽  
Daniel Laplaze
Keyword(s):  
Numerical Simulation ◽  
Fluid Flow ◽  
Large Scale ◽  
Solar Furnace ◽  
Variable Pressure ◽  
Cooling Zone ◽  
Solar Reactor ◽  
Wide Range ◽  
Vaporization Process ◽  
Temperature And Pressure

Abstract A 2 kW solar furnace was used to vaporize a graphite target for fullerene synthesis. Tests were performed in a wide range of vaporization rates (0.1–4 g/h), under variable pressure and argon flow rate. Experimental results are interpreted with numerical simulation to define key parameters for large-scale synthesis of fullerenes with solar energy. We demonstrate that the vaporization process is controlled by diffusion in the temperature and pressure ranges 3000–3700 K and 70–250 hPa respectively. Experimental data and numerical simulation suggest that in the solar reactor, fullerene yield is governed by the dilution of carbon vapor in argon and by the temperature gradient in the cooling zone. Criteria for both parameters are suggested. Consequently, these data, combined with the numerical model accounting for heat, mass and fluid flow inside the reactor, may be used for the design of large-scale solar process.

scholarly journals High-Resolution Numerical Simulation and Analysis of Mach Reflection Structures in Detonation Waves in Low-Pressure H2–O2–Ar Mixtures: A Summary of Results Obtained with the Adaptive Mesh Refinement Framework AMROC

2011 ◽  
Vol 2011 ◽  
pp. 1-18 ◽  
Author(s):  
Ralf Deiterding
Keyword(s):  
Numerical Simulation ◽  
Adaptive Mesh Refinement ◽  
Large Scale ◽  
Mach Reflection ◽  
Adaptive Mesh ◽  
Low Pressure ◽  
Detonation Waves ◽  
Parallel Simulations ◽  
Wide Range ◽  
Complex Boundaries

Numerical simulation can be key to the understanding of the multidimensional nature of transient detonation waves. However, the accurate approximation of realistic detonations is demanding as a wide range of scales needs to be resolved. This paper describes a successful solution strategy that utilizes logically rectangular dynamically adaptive meshes. The hydrodynamic transport scheme and the treatment of the nonequilibrium reaction terms are sketched. A ghost fluid approach is integrated into the method to allow for embedded geometrically complex boundaries. Large-scale parallel simulations of unstable detonation structures of Chapman-Jouguet detonations in low-pressure hydrogen-oxygen-argon mixtures demonstrate the efficiency of the described techniques in practice. In particular, computations of regular cellular structures in two and three space dimensions and their development under transient conditions, that is, under diffraction and for propagation through bends are presented. Some of the observed patterns are classified by shock polar analysis, and a diagram of the transition boundaries between possible Mach reflection structures is constructed.

Comparison of Temperature Field of French Windows Building with Different Types of Floor Radiant System

2013 ◽  
Vol 274 ◽  
pp. 527-530
Author(s):  
Zhi Long Liu ◽  
Fang Wang ◽  
Lian Jing Niu ◽  
Chen Xia Li ◽  
Guo Min Fu
Keyword(s):  
Numerical Simulation ◽  
Temperature Field ◽  
Indoor Air ◽  
Large Scale ◽  
Ground Surface ◽  
Ground Surface Temperature ◽  
Wide Range ◽  
Different Types ◽  
Surface Temperature Field ◽  
Parallel Type

In modern buildings, especially the large-scale ones, the use of French windows becomes more and more popular. In these buildings, compare with the traditional heat sink, the floor radiant system has a wide range of applications because the temperature field of it is more uniform and it is much easier to arrangement. In this paper, by the way of numerical simulation, the ground surface temperature field and indoor air temperature field of three different types of floor radiant system are compared using the CFD software FLUENT. At last, the parallel type can be the best choice in the French windows buildings for the temperature field of it is high but not too high to make people feel uncomfortable.

Experimental Investigation of Vortex Flow in a Two-Chamber Solar Thermochemical Reactor

2013 ◽  
Vol 135 (11) ◽  
Author(s):  
Erik E. Koepf ◽  
Matthew D. Lindemer ◽  
Suresh G. Advani ◽  
Ajay K. Prasad
Keyword(s):  
High Temperature ◽  
Flow Visualization ◽  
Large Scale ◽  
Gas Flow ◽  
Vortex Flow ◽  
Solar Reactor ◽  
Concentrated Solar Energy ◽  
Wide Range ◽  
Reactor Geometry ◽  
Solar Thermochemical

Recent advances in the field of large-scale solar thermochemical processing have given rise to substantial research efforts and demonstration projects. Many applications of high-temperature solar-thermal technology employ an enclosed cavity environment, thus requiring a transparent window through which concentrated solar energy can enter. One configuration employed is a two-cavity reactor connected by a narrow aperture, where solar flux entering through the window is focused at the aperture plane before diverging into the lower chamber, where the chemical reaction occurs. For the Zn/ZnO thermochemical cycle where Zn is solar-thermally reduced from ZnO in a high-temperature cavity environment, effective removal of the product gas stream containing zinc vapor is of paramount importance to prevent fouling by condensation on the reactor window. Two argon-jet configurations, tangential and radial, located around the circumference of the upper chamber are used to control the gas flow within the reactor cavity. First, the tangential jets drive a vortex flow, and second, the radial wall jet travels across the window before converging at the reactor center line and turning downward to create a downward jet. The tangential jet-induced flow creates a rotating vortex, contributing to overall flow stability, and the radial jet-induced downward flow counters the updraft created by the vortex while actively cooling and sweeping clear the inner surface of the window. Flow visualization in a full-scale transparent model of the reactor using smoke and laser illumination is employed to characterize the effectiveness of aerodynamic window clearing and to characterize the processes by which a vortex flow develops and breaks down in a two-chamber solar reactor geometry. Based on a large dataset of flow visualization images, a metric is developed to define vortex stability over a wide range of flow conditions and identify an ideal operating range for which a vortex formation path is established that maintains stable flow patterns and removes product gases while minimizing the use of argon gas. The predominant influence of vortex instability and breakdown is identified and examined for the case of a beam-down, two-chamber solar reactor geometry.

Electron microscopy study of reactively sputter-deposited Ti/N films on silicon

1992 ◽  
Vol 50 (2) ◽  
pp. 1362-1363
Author(s):  
V. C. Kannan ◽  
A. K. Singh ◽  
R. B. Irwin ◽  
S. Chittipeddi ◽  
F. D. Nkansah ◽  
...  
Keyword(s):  
Integrated Circuits ◽  
Large Scale ◽  
Hexagonal Phase ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Process Conditions ◽  
Tin Films ◽  
Wide Range ◽  
Fcc Phase ◽  
Circuits Vlsi

Titanium nitride (TiN) films have historically been used as diffusion barrier between silicon and aluminum, as an adhesion layer for tungsten deposition and as an interconnect material etc. Recently, the role of TiN films as contact barriers in very large scale silicon integrated circuits (VLSI) has been extensively studied. TiN films have resistivities on the order of 20μ Ω-cm which is much lower than that of titanium (nearly 66μ Ω-cm). Deposited TiN films show resistivities which vary from 20 to 100μ Ω-cm depending upon the type of deposition and process conditions. TiNx is known to have a NaCl type crystal structure for a wide range of compositions. Change in color from metallic luster to gold reflects the stabilization of the TiNx (FCC) phase over the close packed Ti(N) hexagonal phase. It was found that TiN (1:1) ideal composition with the FCC (NaCl-type) structure gives the best electrical property.

Software system for numerical simulation of broadband laser gas analysis of the atmosphere

2018 ◽  
pp. 66-73 ◽  
Author(s):  
S. A. Sadovnikov
Keyword(s):  
Numerical Simulation ◽  
Laser Radiation ◽  
Gas Analysis ◽  
Modular System ◽  
Software System ◽  
Transmission Spectra ◽  
Molecular Absorption ◽  
Molecular Scattering ◽  
Atmospheric Transmission ◽  
Wide Range

Introduction: Successful monitoring of environmental parameters requires the development of flexible software complexes with evolvable calculation functionality. Purpose: Developing a modular system for numerical simulation of atmospheric laser gas analysis. Results: Based on differential absorption method, a software system has been developed which provides the calculation of molecular absorption cross-sections, molecular absorption coefficients, atmospheric transmission spectra, and lidar signals. Absorption line contours are calculated using the Voigt profile. The prior information sources are HITRAN spectroscopic databases and statistical models of the distribution of temperature, pressure and gas components in the atmosphere. For modeling lidar signals, software blocks of calculating the molecular scattering coefficient and aerosol absorption/scattering coefficients were developed. For testing the applicability of various laser sources in the problems of environmental monitoring of the atmosphere, a concentration reconstruction error calculation block was developed for the atmospheric gas components, ignoring the interfering absorption of laser radiation by foreign gases. To verify the correct functioning of the software, a program block was developed for comparing the results of the modeling of atmospheric absorption and transmission spectra by using the standard SPECTRA information system. The discrepancy between the calculation of the atmospheric transmission spectra obtained using the developed system as compared to the SPECTRA results is less than 1%. Thus, a set of the presented program blocks allows you to carry out complex modeling of remote atmospheric gas analysis. Practical relevance: The software complex allows you to rapidly assess the possibilities of using a wide range of laser radiation sources for the problems of remote gas analysis.

THE SOME QUESTIONS OF AUTONOMOUS MOTION AND MANAGEMENT OF LAND-MOBILE ROBOTIC COMPLEXES FOR UKRAINIAN GROUND FORCESE

2019 ◽  
pp. 53-58
Author(s):  
О. Кravchuk ◽  
V. Symonenkov ◽  
I. Symonenkova ◽  
O. Hryhorev
Keyword(s):  
Large Scale ◽  
Armed Forces ◽  
Distributed Information ◽  
Wide Range ◽  
Highly Effective ◽  
Information Management Systems ◽  
Robotic Devices ◽  
Principles And Standards ◽  
And Control ◽  
The Eu

Today, more than forty countries of the world are engaged in the development of military-purpose robots. A number of unique mobile robots with a wide range of capabilities are already being used by combat and intelligence units of the Armed forces of the developed world countries to conduct battlefield intelligence and support tactical groups. At present, the issue of using the latest information technology in the field of military robotics is thoroughly investigated, and the creation of highly effective information management systems in the land-mobile robotic complexes has acquired a new phase associated with the use of distributed information and sensory systems and consists in the transition from application of separate sensors and devices to the construction of modular information subsystems, which provide the availability of various data sources and complex methods of information processing. The purpose of the article is to investigate the ways to increase the autonomy of the land-mobile robotic complexes using in a non-deterministic conditions of modern combat. Relevance of researches is connected with the necessity of creation of highly effective information and control systems in the perspective robotic means for the needs of Land Forces of Ukraine. The development of the Armed Forces of Ukraine management system based on the criteria adopted by the EU and NATO member states is one of the main directions of increasing the effectiveness of the use of forces (forces), which involves achieving the principles and standards necessary for Ukraine to become a member of the EU and NATO. The inherent features of achieving these criteria will be the transition to a reduction of tasks of the combined-arms units and the large-scale use of high-precision weapons and land remote-controlled robotic devices. According to the views of the leading specialists in the field of robotics, the automation of information subsystems and components of the land-mobile robotic complexes can increase safety, reliability, error-tolerance and the effectiveness of the use of robotic means by standardizing the necessary actions with minimal human intervention, that is, a significant increase in the autonomy of the land-mobile robotic complexes for the needs of Land Forces of Ukraine.

Stirring and aeration system for the upgrading of small waste water treatment plants

1994 ◽  
Vol 29 (12) ◽  
pp. 149-156 ◽  
Author(s):  
Marcus Höfken ◽  
Katharina Zähringer ◽  
Franz Bischof
Keyword(s):  
Waste Water ◽  
Water Treatment ◽  
Large Scale ◽  
Waste Water Treatment ◽  
Water Treatment Plants ◽  
Waste Water Treatment Plants ◽  
Basic Fluid ◽  
Aeration System ◽  
Technical Realization ◽  
Wide Range

A novel agitating system has been developed which allows for individual or combined operation of stirring and aeration processes. Basic fluid mechanical considerations led to the innovative hyperboloid design of the stirrer body, which ensures high efficiencies in the stirring and the aeration mode, gentle circulation with low shear forces, excellent controllability, and a wide range of applications. This paper presents the basic considerations which led to the operating principle, the technical realization of the system and experimental results in a large-scale plant. The characteristics of the system and the differences to other stirring and aeration systems are illustrated. Details of the technical realization are shown, which conform to the specific demands of applications in the biological treatment of waste water. Special regard is given to applications in the upgrading of small compact waste water treatment plants.

Thin structure of heterogeneous and multiphase fluid flows

2012 ◽  
Vol 9 (1) ◽  
pp. 175-180
Author(s):  
Yu.D. Chashechkin
Keyword(s):  
Large Scale ◽  
Fundamental System ◽  
Fluid Flows ◽  
Regular Solutions ◽  
Flow Models ◽  
Group Methods ◽  
Wide Range ◽  
Thin Structure ◽  
Multiphase Fluid ◽  
Complete Solutions

According to the results of visualization of streams, the existence of structures in a wide range of scales is noted: from galactic to micron. The use of a fundamental system of equations is substantiated based on the results of comparing symmetries of various flow models with the usage of theoretical group methods. Complete solutions of the system are found by the methods of the singular perturbations theory with a condition of compatibility, which determines the characteristic equation. A comparison of complete solutions with experimental data shows that regular solutions characterize large-scale components of the flow, a rich family of singular solutions describes formation of the thin media structure. Examples of calculations and observations of stratified, rotating and multiphase media are given. The requirements for the technique of an adequate experiment are discussed.

Integrative Data Analysis from a Unifying Research Synthesis Perspective

2018 ◽  
Author(s):  
Eun-Young Mun ◽  
Anne E. Ray
Keyword(s):  
Data Analysis ◽  
Large Scale ◽  
Research Synthesis ◽  
Alcohol Intervention ◽  
Data Set ◽  
Integrative Data Analysis ◽  
Level Data ◽  
Model Complex ◽  
Wide Range ◽  
Individual Participant

Integrative data analysis (IDA) is a promising new approach in psychological research and has been well received in the field of alcohol research. This chapter provides a larger unifying research synthesis framework for IDA. Major advantages of IDA of individual participant-level data include better and more flexible ways to examine subgroups, model complex relationships, deal with methodological and clinical heterogeneity, and examine infrequently occurring behaviors. However, between-study heterogeneity in measures, designs, and samples and systematic study-level missing data are significant barriers to IDA and, more broadly, to large-scale research synthesis. Based on the authors’ experience working on the Project INTEGRATE data set, which combined individual participant-level data from 24 independent college brief alcohol intervention studies, it is also recognized that IDA investigations require a wide range of expertise and considerable resources and that some minimum standards for reporting IDA studies may be needed to improve transparency and quality of evidence.

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