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.

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 Combined numerical and experimental study of microstructure and permeability in porous granular media

2020 ◽  
Author(s):  
Philipp Eichheimer ◽  
Marcel Thielmann ◽  
Wakana Fujita ◽  
Gregor J. Golabek ◽  
Michihiko Nakamura ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Numerical Simulations ◽  
Granular Media ◽  
Large Scale ◽  
Earth Science ◽  
Numerical Models ◽  
Effective Porosity ◽  
Flow Properties ◽  
Wide Range ◽  
Flow Through

Abstract. Fluid flow on different scales is of interest for several Earth science disciplines like petrophysics, hydrogeology and volcanology. To parameterize fluid flow in large-scale numerical simulations (e.g. groundwater and volcanic systems), flow properties on the microscale need to be considered. For this purpose experimental and numerical investigations of flow through porous media over a wide range of porosities are necessary. In the present study we sinter glass bead media with various porosities. The microstructure, namely effective porosity and effective specific surface, is investigated using image processing. We determine flow properties like hydraulic tortuosity and permeability using both experimental measurements and numerical simulations. By fitting microstructural and flow properties to porosity, we obtain a modified Kozeny-Carman equation for isotropic low-porosity media, that can be used to simulate permeability in large-scale numerical models. To verify the modified Kozeny-Carman equation we compare it to the computed and measured permeability values.

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.

scholarly journals Combined numerical and experimental study of microstructure and permeability in porous granular media

Solid Earth ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 1079-1095 ◽  
Author(s):  
Philipp Eichheimer ◽  
Marcel Thielmann ◽  
Wakana Fujita ◽  
Gregor J. Golabek ◽  
Michihiko Nakamura ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Numerical Simulations ◽  
Granular Media ◽  
Large Scale ◽  
Earth Science ◽  
Effective Porosity ◽  
Flow Through Porous Media ◽  
Flow Properties ◽  
Wide Range ◽  
Flow Through

Abstract. Fluid flow on different scales is of interest for several Earth science disciplines like petrophysics, hydrogeology and volcanology. To parameterize fluid flow in large-scale numerical simulations (e.g. groundwater and volcanic systems), flow properties on the microscale need to be considered. For this purpose experimental and numerical investigations of flow through porous media over a wide range of porosities are necessary. In the present study we sinter glass bead media with various porosities and measure the permeability experimentally. The microstructure, namely effective porosity and effective specific surface, is investigated using image processing. We determine flow properties like tortuosity and permeability using numerical simulations. We test different parameterizations for isotropic low-porosity media on their potential to predict permeability by comparing their estimations to computed and experimentally measured values.

Numerical simulation of fluid flow and cell expansion in large scale inside a novel bioreactor

2016 ◽  
Vol 33 ◽  
pp. S111
Author(s):  
Kedong Song ◽  
Xinyu Yan ◽  
Xiangqin Li ◽  
Tianqing Liu
Keyword(s):  
Numerical Simulation ◽  
Fluid Flow ◽  
Cell Expansion ◽  
Large Scale

scholarly journals Combined numerical and experimental study of microstructure and permeability in porous granular media

2020 ◽  
Author(s):  
Philipp Eichheimer ◽  
Marcel Thielmann ◽  
Wakana Fujita ◽  
Gregor J. Golabek ◽  
Michihiko Nakamura ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Numerical Simulations ◽  
Granular Media ◽  
Large Scale ◽  
Earth Science ◽  
Numerical Models ◽  
Effective Porosity ◽  
Flow Properties ◽  
Wide Range ◽  
Flow Through

<div> <div> <div> <p>Fluid flow on different scales is of interest for several Earth science disciplines like petrophysics, hydrogeology and volcanology. To parameterize fluid flow in large-scale numerical simulations (e.g. groundwater and volcanic systems), flow properties on the microscale need to be considered. For this purpose experimental and numerical investigations of flow through porous media over a wide range of porosities are necessary. In the present study we sinter glass bead media with various porosities, representing shallow depth crustal sediments. The microstructure, namely effective porosity and effective specific surface, is investigated using image processing. We furthermore determine flow properties like hydraulic tortuosity and permeability using both experimental measurements and numerical simulations. By fitting microstructural and flow properties to porosity, we obtain a modified Kozeny-Carman equation for isotropic low-porosity media, that can be used to simulate permeability in large-scale numerical models. To verify the modified Kozeny-Carman equation we compare it to the numerically computed and experimentally measured permeability values.</p> </div> </div> </div>

Numerical Simulation for Heat Transfer and Fluid Flow Performances of Thin Film Evaporation in the Micro Rectangular Groove

2014 ◽  
Vol 672-674 ◽  
pp. 1459-1464
Author(s):  
Jing Ming Dong ◽  
Chun Lu Kang ◽  
Hai Chao Yuan ◽  
Xin Xiang Pan
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Numerical Simulation ◽  
Fluid Flow ◽  
Bulk Region ◽  
Thin Film Evaporation ◽  
Film Evaporation ◽  
Temperature And Pressure ◽  
The Galerkin Method ◽  
Rectangular Groove

The heat transfer and fluid flow performances of thin film evaporation were investigated numerically in this paper. Based on the coordinate transformation and the Galerkin Method, the analytical solutions of the temperature and pressure distribution within the meniscus bulk region, where the interface is dominated by surface tension were found. The effects of contact angle, superheat and aspect ratio on the temperature distribution of thin film evaporation in the rectangular groove were studied. Meanwhile, the pressure and velocity distribution of thin film evaporation were calculated and analyzed. The results had investigated in this paper can help understanding the mechanism of thin film evaporation for the further study.

scholarly journals A Unified Equation to Predict the Permeability of Rough Fractures via Lattice Boltzmann Simulation

Water ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 1081 ◽  
Author(s):  
Peijie Yin ◽  
Can Zhao ◽  
Jianjun Ma ◽  
Linchong Huang
Keyword(s):  
Numerical Simulation ◽  
Fluid Flow ◽  
Lattice Boltzmann ◽  
Mass Conservation ◽  
Extensive Study ◽  
Roughness Coefficient ◽  
Single Fracture ◽  
Lattice Boltzmann Simulation ◽  
Wide Range ◽  
Flow Through

In this paper, the fluid flow through rough fractures was investigated via numerical simulation based on the lattice Boltzmann method (LBM). The accuracy of LBM was validated through the numerical simulation of the parallel plate model and the verification of the mass conservation of fluid flow through rough fracture. After that, the effect of roughness on fluid flow was numerically conducted, in which, the geometry of fractures was characterized by the joint roughness coefficient (JRC), fractal dimension (D) and standard deviation (σ). It was found that the JRC cannot reflect the realistic influence of roughness on the permeability of single fracture, in which, an increase in permeability with increasing JRC has been observed at the range of 8~12 and 14~16. The reason behind this was revealed through the calculation of the root mean square of the first derivative of profile (Z2), and an equation has been proposed to estimate the permeability based on the aperture and Z2 of the fracture. The numerical simulations were further conducted on fluid flow though synthetic fractures with a wide range of D and σ. In order to unify the parameter that characterizes the roughness, Z2 was obtained for each synthetic fracture, and the corresponding relationship between permeability, aperture and Z2 was analyzed. Meanwhile, it was found that the fluid flow behaves differently with different ranges of Z2 and the critical point was found to be Z2 = 0.5. Based on extensive study, it was concluded that Z2 is a generic parameter characterizing the roughness, and the proposed equation could be used to predict the permeability for fluid flow in fracture.

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.

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