Computational Fluid Dynamics Simulation of a Tubular Aerosol Reactor for Solar Thermal ZnO Decomposition

2007 ◽  
Vol 129 (4) ◽  
pp. 391-404 ◽  
Author(s):  
Christopher Perkins ◽  
Alan Weimer
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Gas Flow ◽  
High Surface ◽  
Dynamics Simulation ◽  
Base Case ◽  
Reactor Wall ◽  
Conductive Heat ◽  
Sensitive Material ◽  
Aspect Ratios

Computational fluid dynamics simulations were performed to model solar ZnO dissociation in a tubular aerosol reactor at ultrahigh temperatures (1900–2300K). Reactor aspect ratios ranged between 0.15 and 0.45, with the smallest ratio base case corresponding to a reactor diameter of 0.02286m. Gas flow rates were set such that the Ar:ZnO ratio was greater than 3:1 and the system residence time was below 2s. The system was found to exhibit highly laminar flow in all cases (Re∼10), but gas velocity profiles did not seriously affect temperature profiles. Particle heating was nearly instantaneous, a result of the high radiation heat flux from the wall. There was essentially no difference between gas and particle temperatures due to the high surface area for conductive heat exchange between the phases. Calculation of ZnO conversion showed that significant conversions (>90%) could be attained for residence times typical of rapid aerosol processing. Particle sizes of >1μm negatively affected conversion, but sizes of 10μm still gave acceptable conversion levels. Simulation of reaction of product oxygen with the reactor wall showed that a reactor constructed of an oxidation-sensitive material would not be a viable choice for a high temperature solar reactor.

Computational Fluid Dynamics Simulation of a Tubular Aerosol Reactor for Solar Thermal ZnO Decomposition

2007 ◽  
Author(s):  
Christopher Perkins ◽  
Alan W. Weimer
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Surface ◽  
High Surface Area ◽  
Dynamics Simulation ◽  
Base Case ◽  
Reactor Wall ◽  
Conductive Heat ◽  
Sensitive Material ◽  
Aspect Ratios

Computational fluid dynamics simulations were performed to model solar ZnO dissociation in a tubular aerosol reactor at ultra-high temperatures (1900 K–2300 K). Reactor aspect ratios ranged between 0.15 and 0.45, with the smallest ratio base case corresponding to a reactor diameter of .02286 m. Gas flowrates were set such that the Ar:ZnO ratio was greater than 3:1 and the system residence time was below 2 s. The system was found to exhibit highly laminar flow in all cases (Re ∼ 10), but gas velocity profiles did not seriously affect temperature profiles. Particle heating was nearly instantaneous, a result of the high radiation heat flux from the wall. There was essentially no difference between gas and particle temperatures due to the high surface area for conductive heat exchange between the phases. Calculation of ZnO conversion showed that significant conversions (>90%) could be attained for residence times typical of rapid aerosol processing. Particle sizes larger than 1 μm negatively affected conversion, but sizes of 10 μm still gave acceptable conversion levels. Simulation of reaction of product oxygen with the reactor wall showed that a reactor constructed of an oxidation-sensitive material would not be a viable choice for a high temperature solar reactor.

Computational fluid dynamics simulation study of gas flow in dry scroll vacuum pump

Vacuum ◽  
2015 ◽  
Vol 116 ◽  
pp. 144-152 ◽  
Author(s):  
Xiang-Ji Yue ◽  
Yan-jun Lu ◽  
Ying-Li Zhang ◽  
De-chun Ba ◽  
Guang-Yu Wang ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Simulation Study ◽  
Gas Flow ◽  
Vacuum Pump ◽  
Dynamics Simulation ◽  
Computational Fluid Dynamics Simulation

scholarly journals Computational Fluid Dynamics Simulation and Experimental Study of Key Design Parameters of Solar Thermal Collectors

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
James Allan ◽  
Zahir Dehouche ◽  
Sinisa Stankovice ◽  
Alan Harries
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Thermal Efficiency ◽  
Thermal Contact ◽  
High Surface ◽  
Heat Removal ◽  
Solar Thermal ◽  
Dynamics Simulation ◽  
Low Flow ◽  
Design Parameters

Numerical simulation enables the optimization of a solar collector without the expense of building prototypes. This study details an approach using computational fluid dynamics (CFD) to simulate the performance of a solar thermal collector. Inputs to the simulation include; heat loss coefficient, irradiance, and ambient temperature. A simulated thermal efficiency was validated using experimental results by comparing the calculated heat removal factor. The validated methodology was then applied to five different inlet configurations of a header–riser collector. The most efficient designs had uniform flow through the risers. The worst performing configurations had low flow rates in the risers that led to high surface temperatures and poor thermal efficiency. The calculated heat removal factor differed by between 4.2% for the serpentine model and 12.1% for the header–riser. The discrepancies were attributed to differences in thermal contact between plate and tubes in the simulated and actual design.

scholarly journals Fire Propagation Study in Naturally Ventilated Buildings using Computer Simulation

2019 ◽  
Author(s):  
Raja Singh
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Natural Ventilation ◽  
The Other ◽  
Dynamics Simulation ◽  
Small Cells ◽  
Base Case ◽  
Fire Propagation ◽  
Naturally Ventilated Buildings ◽  
Made In

Fire safety is of imminent concern in buildings since the first building was made. In a fire, the major concerns are evacuation and safety from the smoke and the heat. Smoke and the heat of the fire spreads in the building from one space to the other if there is continuity in space. Naturally ventilated buildings are made with a premise of enhancing this vertical and horizontal continuity in order to create health ventilation and air movement. In case of a fire, these natural ventilation pathways can facilitate the flow of smoke and heat through the spaces. This study aims at verifying using computational fluid dynamics simulation the actual role played by natural ventilation elements in the propagation of fire in buildings. A CFD (Computational Fluid Dynamics) package called FDS(Fire Dynamics Simulator) has been used preceded by a 3D model made in a 3D modelling software. The CFD software uses laws of conservation of mass, momentum and energy to actually evaluate the change in the mass, momentum and energy in small cells. These cells are of which the test space is made up of and is divided into. A test case is made up of a building with conventional design. This is tested against enhanced naturally ventilated buildings with parametric iterations. The first model of the building has one feature and then the feature gets added and tested again in each case. Here, we can compare in real time the effect of each feature against a base case and against the other features provided for enhanced natural ventilation. What is compared in all the results is the slices made at the same location. This gives us an insight on the fire propagation in naturally ventilated buildings and designers can use this to prevent fires from endangering the lives of the inhabitants.

Computational fluid dynamics simulation of an Inert Particles Spouted Bed Reactor (IPSBR) system

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Ameera F. Mohammad ◽  
Aya A-H. I. Mourad ◽  
Jawad Mustafa ◽  
Ali H. Al-Marzouqi ◽  
Muftah H. El-Naas ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Gas Flow ◽  
Interfacial Area ◽  
Independent Study ◽  
Dynamics Simulation ◽  
Liquid Volume ◽  
Volume Distribution ◽  
Mesh Structure ◽  
Inert Particles

AbstractA novel system for contacting gases and liquids, suitable for many applications involving gas–liquid contact such as CO2 capture and brine desalination, has been simulated and experimentally validated. The system comprises a vertical vessel with gas and liquid ports and inert particles that enhance mixing and provide a high gas–liquid interfacial area. A low gas flow rate was statistically demonstrated and experimentally verified to be the optimum condition for CO2 capture and brine desalination; however, the gas velocity can have a considerable effect on the motion of inert particles inside the reactor. Uniform particles motion ensures good mixing within the reactor and hence efficient absorption and stripping process. A computational fluid dynamics (CFD) model, namely Eulerian model, presented in this paper, will help demonstrate the effect of mixing particles at specific conditions on the gas and liquid velocities inside the reactor, gas and liquid volume distribution through reactor, and eddy viscosities stresses of the mixing particles. A mesh-independent study was conducted to demonstrate the independency of mesh structure and size on the output responses. A quasi-steady state was attained to ensure the stability and feasibility of the selected model. The assembled model exhibits remarkable applicability in determining the optimum mixing particles densities, volume ratios, and sizes to ensure best velocity distribution and gas spreading inside the reactor and accordingly enhance the associated chemical reactions.

Optimization of 450mm Wafer Ashing Chamber by Computational Fluid Dynamics Simulation

2013 ◽  
Vol 834-836 ◽  
pp. 1544-1547
Author(s):  
Younghwan Cha ◽  
Myoungsoo Kim ◽  
Dahyeouk Lee ◽  
Kibo Kim ◽  
Seungkook Yang ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Gas Flow ◽  
Flux Distribution ◽  
Inductive Inference ◽  
Dynamics Simulation ◽  
Wafer Surface ◽  
Computational Fluid Dynamics Simulation ◽  
Process Step ◽  
Molecular Flux

Ashing is a photoresist-stripping process using oxygen or hydrogen radicals and is one of key process step in the semiconductor manufacturing processes. Uniform and fast stripping is the key factor in ashing. In this study, a computational fluid dynamics simulation was applied to find conditions for uniform molecular flux over the wafer surface and to optimize the ashing chamber geometry. In particular, the distance between the gas inlet baffle and wafer stage in the 450 mm wafer chamber was determined through inductive inference statistics. To improve the reliability of this simulation, the correlations between the calculated molecular flux distribution and the measured ashing rate distribution over 300 mm wafers were sought first. Effects of the distance between the baffle and wafer stage, wafer stage temperature, and gas flow rate on distributions of molecule flux and velocity, temperature and gas molecule density were calculated. The simulation showed that the density distribution over 450 mm wafer surface was more uniform when the distance between gas inlet baffle and wafer stage was between 35 mm and 60 mm, and that the reactant flux distribution was more uniform when the distance was between 60 mm and 80 mm. Therefore, the distance between the gas inlet baffle and wafer stage was chosen to be 60 mm.

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