scholarly journals Identification of Model Parameters of Vaporized Hydrogen Peroxide Decomposi-tion Flux on Building Materials for Compu-tational Fluid Dynamics

2016 ◽  
Vol 07 (02) ◽  
pp. 212-229 ◽  
Author(s):  
Kazuhide Ito ◽  
Sung-Jun Yoo ◽  
Hirofumi Horata
Keyword(s):  
Fluid Dynamics ◽  
Hydrogen Peroxide ◽  
Building Materials ◽  
Model Parameters

Computational fluid dynamics modelling of the visible light photocatalytic oxidation process of toluene for indoor building materials with locally doped titanium dioxide

2019 ◽  
Vol 29 (2) ◽  
pp. 163-179 ◽  
Author(s):  
Koki Nakahara ◽  
Mahbubul Muttakin ◽  
Kiyoshi Yamamoto ◽  
Kazuhide Ito
Keyword(s):  
Fluid Dynamics ◽  
Mathematical Model ◽  
Computational Fluid Dynamics ◽  
Titanium Dioxide ◽  
Gas Phase ◽  
Photocatalytic Oxidation ◽  
Building Materials ◽  
Model Parameters ◽  
Surface Boundary ◽  
Cfd Analysis

Computational fluid dynamics (CFD) is one of the promising methods that can precisely predict non-uniform air flow and contaminant distribution in indoor environments. The overarching objective of this study was to develop a mathematical model for describing the photocatalytic oxidation (PCO) reaction mechanism of gas phase toluene with titanium dioxide (TiO2)-bound indoor building materials. This mathematical model was developed based on Langmuir-Hinshelwood type kinetics and for the integration with CFD simulations as a wall surface boundary condition. The effects of gas phase toluene concentration, illuminance and humidity on the toluene oxidation reaction were considered with locally TiO2-doped building materials. Especially, humidity dependence was explicitly integrated as a competitive adsorption model between toluene and water vapour. Moreover, surface compositions of TiO2 and the substrate (ceramic tile in this study), and the physical adsorption properties of those materials, were modelled and integrated into the mathematical model. A 0.02 m3 chamber experiment and adsorption isotherm measurements were conducted to identify the model parameters. CFD analysis was carried out according to experimental scenarios, and an optimization procedure for the model parameters was proposed for their application as the boundary conditions in the CFD analysis.

Rheological modelling of fresh human faeces

2014 ◽  
Vol 4 (3) ◽  
pp. 484-489 ◽  
Author(s):  
S. M. Woolley ◽  
C. A. Buckley ◽  
J. Pocock ◽  
G. L. Foutch
Keyword(s):  
Fluid Dynamics ◽  
Reasonable Agreement ◽  
Model Parameters ◽  
Viscosity Data ◽  
Initial Screening ◽  
Human Faeces ◽  
Shear Thinning Fluids ◽  
Treatment Processes ◽  
Rheological Modelling ◽  
Generate Model

An analysis of viscosity data from sets of raw data on the shear rheological properties of fresh human faeces was performed to generate model constants that can be used for the design of faecal treatment processes. The models selected are standard choices in computational fluid dynamics software for shear-thinning fluids. Initial screening for model selection was based on a literature review of similarly viscous materials. Results showed reasonable agreement with Power Law (PL). PL model parameters were proposed for fresh human faeces and correlated against sample properties. A PL model for shear stress as a function of moisture content was proposed.

An Improved Computational Fluid Dynamics (CFD) Model for Erosion Prediction in Oil and Gas Industry Applications

2014 ◽  
Author(s):  
Deval Pandya ◽  
Brian Dennis ◽  
Ronnie Russell
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Surface Velocity ◽  
Particle Model ◽  
Model Parameters ◽  
Cfd Model ◽  
Erosion Model ◽  
Erosion Prediction ◽  
Erosion Models ◽  
Computational Fluid Dynamics Cfd

In recent years, the study of flow-induced erosion phenomena has gained interest as erosion has a direct influence on the life, reliability and safety of equipment. Particularly significant erosion can occur inside the drilling tool components caused by the low particle loading (<10%) in the drilling fluid. Due to the difficulty and cost of conducting experiments, significant efforts have been invested in numerical predictive tools to understand and mitigate erosion within drilling tools. Computational fluid dynamics (CFD) is becoming a powerful tool to predict complex flow-erosion and a cost-effective method to re-design drilling equipment for mitigating erosion. Existing CFD-based erosion models predict erosion regions fairly accurately, but these models have poor reliability when it comes to quantitative predictions. In many cases, the error can be greater than an order of magnitude. The present study focuses on development of an improved CFD-erosion model for predicting the qualitative as well as the quantitative aspects of erosion. A finite-volume based CFD-erosion model was developed using a commercially available CFD code. The CFD model involves fluid flow and turbulence modeling, particle tracking, and application of existing empirical erosion models. All parameters like surface velocity, particle concentration, particle volume fraction, etc., used in empirical erosion equations are obtained through CFD analysis. CFD modeling parameters like numerical schemes, turbulence models, near-wall treatments, grid strategy and discrete particle model parameters were investigated in detail to develop guidelines for erosion prediction. As part of this effort, the effect of computed results showed good qualitative and quantitative agreement for the benchmark case of flow through an elbow at different flow rates and particle sizes. This paper proposes a new/modified erosion model. The combination of an improved CFD methodology and a new erosion model provides a novel computational approach that accurately predicts the location and magnitude of erosion. Reliable predictive methodology can help improve designs of downhole equipment to mitigate erosion risk as well as provide guidance on repair and maintenance intervals. This will eventually lead to improvement in the reliability and safety of downhole tool operation.

scholarly journals Deep search for hydrogen peroxide toward pre- and protostellar objects

2020 ◽  
Vol 636 ◽  
pp. A114
Author(s):  
G. W. Fuchs ◽  
D. Witsch ◽  
D. Herberth ◽  
M. Kempkes ◽  
B. Stanclik ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Solid State ◽  
Water Reservoir ◽  
Reaction Network ◽  
Reaction Scheme ◽  
Young Stellar Objects ◽  
Model Parameters ◽  
Stellar Objects ◽  
Additional Information ◽  
Water Formation

Context. In the laboratory, hydrogen peroxide (HOOH) was proven to be an intermediate product in the solid-state reaction scheme that leads to the formation of water on icy dust grains. When HOOH desorbs from the icy grains, it can be detected in the gas phase. In combination with water detections, it may provide additional information on the water reaction network. Hydrogen peroxide has previously been found toward ρ Oph A. However, further searches for this molecule in other sources failed. Hydrogen peroxide plays a fundamental role in the understanding of solid-state water formation and the overall water reservoir in young stellar objects (YSOs). Without further HOOH detections, it is difficult to assess and develop suitable chemical models that properly take into account the formation of water on icy surfaces. Aims. The objective of this work is to identify HOOH in YSOs and thereby constrain the grain surface water formation hypothesis. Methods. Using an astrochemical model based on previous work in combination with a physical model of YSOs, the sources R CrA-IRS 5A, NGC C1333-IRAS 2A, L1551-IRS 5, and L1544 were identified as suitable candidates for an HOOH detection. Long integration times on the APEX 12 m and IRAM 30 m telescopes were applied to search for HOOH signatures in these sources. Results. None of the four sources under investigation showed convincing spectral signatures of HOOH. The upper limit for HOOH abundance based on the noise level at the frequency positions of this molecule for the source R CrA-IRS 5A was close to the predicted value. For NGC 1333-IRAS 2A, L1544, and L1551-IRS 5, the model overestimated the hydrogen peroxide abundances. Conclusions. HOOH remains an elusive molecule. With only one secure cosmic HOOH source detected so far, namely ρ Oph A, the chemical model parameters for this molecule cannot be sufficiently well determined or confirmed in existing models. Possible reasons for the nondetections of HOOH are discussed.

scholarly journals Removal of Banana Tree Fungi Using Green Tuff Rock Powder Waste Containing Zeolite

Catalysts ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1049
Author(s):  
Toyohisa Fujita ◽  
Josiane Ponou ◽  
Gjergj Dodbiba ◽  
Ji-Whahn Anh ◽  
Siminig Lu ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Building Materials ◽  
The Philippines ◽  
Rock Powder ◽  
Panama Disease ◽  
Banana Tree ◽  
Cavendish Banana ◽  
Peroxide Decomposition ◽  
Powder Suspension ◽  
Akita Prefecture

Hinai green tuff, which is found in Akita Prefecture, Japan, is used for the production of building materials, etc. About 60% of all stone is emitted as waste powder and therefore it is important to find ways for recycling it. In this work, the characteristics of green tuff powder have been investigated. The results of scanning electron microscope (SEM) and elemental map observations indicate that the green tuff contains TiO2 on zeolite. The green tuff can therefore be used as a natural catalyst for producing hydrogen peroxide with moisture and oxygen with light. The optimum calcined temperature of the green tuff powder is about 800 °C, producing the hydroxyl radical from hydrogen peroxide decomposition without ultraviolet light (UV) and decomposition of the superoxide anion. As the application of green tuff powder, Cavendish banana trees found in the Philippines infected by a new Panama disease were treated with powder suspension in order to remove the fungus (a type of Fusarium wilt) due to the photocatalyst characteristics of powder. The suspension, prepared by using the powder was sprayed on the infected banana trees for about one month. Photograph observation indicated that the so-called 800 °C suspension spray was more effective in growing the infected banana trees.

scholarly journals Experimental and Computational Analysis of NOx Photocatalytic Abatement Using Carbon-Modified TiO2 Materials

Catalysts ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1366
Author(s):  
Tatiana Zhiltsova. ◽  
Nelson Martins ◽  
Mariana R. F. Silva ◽  
Carla F. Da Silva ◽  
Mirtha A. O. Lourenço ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Kinetic Model ◽  
Photocatalytic Oxidation ◽  
Cfd Simulation ◽  
Emission Spectra ◽  
Chemical Kinetic ◽  
Solar Light ◽  
Model Parameters ◽  
Chemical Kinetic Model ◽  
Simulated Solar Light

In the present study, two photocatalytic graphene oxide (GO) and carbon nanotubes (CNT) modified TiO2 materials thermally treated at 300 °C (T300_GO and T300_CNT, respectively) were tested and revealed their conversion efficiency of nitrogen oxides (NOx) under simulated solar light, showing slightly better results when compared with the commercial Degussa P25 material at the initial concentration of NOx of 200 ppb. A chemical kinetic model based on the Langmuir–Hinshelwood (L-H) mechanism was employed to simulate micropollutant abatement. Modeling of the fluid dynamics and photocatalytic oxidation (PCO) kinetics was accomplished with computational fluid dynamics (CFD) approach for modeling single-phase liquid fluid flow (air/NOx mixture) with an isothermal heterogeneous surface reaction. A tuning methodology based on an extensive CFD simulation procedure was applied to adjust the kinetic model parameters toward a better correspondence between simulated and experimentally obtained data. The kinetic simulations of heterogeneous photo-oxidation of NOx carried out with the optimized parameters demonstrated a high degree of matching with the experimentally obtained NOx conversion. T300_CNT is the most active photolytic material with a degradation rate of 62.1%, followed by P25-61.4% and T300_GO-60.4%, when irradiated, for 30 min, with emission spectra similar to solar light.

Development of a simulator for ozone/UV reactor based on CFD analysis

2002 ◽  
Vol 46 (11-12) ◽  
pp. 13-19 ◽  
Author(s):  
M. Kamimura ◽  
S. Furukawa ◽  
J. Hirotsuji
Keyword(s):  
Fluid Dynamics ◽  
Hydrogen Peroxide ◽  
Radical Reaction ◽  
Reaction Model ◽  
Cfd Analysis ◽  
Dynamics Model ◽  
Uv Reactor ◽  
Completely Stirred Tank Reactor ◽  
Cstr System ◽  
Good Agreement

A new CFD (Computational Fluid Dynamics) simulator for an O3/UV reactor where ozone dissolved water flows under the irradiation of UV, has been developed by combining a fluid dynamics model with a complex radical reaction model. The radical reaction model used in this simulator was found to be reasonable, because the results obtained from the simulation of a completely stirred tank reactor (CSTR) system were in good agreement with the experimental results, e.g., the concentrations of total organic carbon (TOC), hydrogen peroxide and dissolved ozone obtained from a lab-scale CSTR. Furthermore, by using this CFD simulator, the distributions of substances such as hydroxyl radical (OHá) and hydrogen peroxide in the O3/UV reactor have been investigated. These distributions showed that this CFD simulator was considered to be reasonable. In addition, the simulation results suggested that conventional reactors were not optimized.

Effects of Hydrogen Peroxide on Foam Concrete Performances

2014 ◽  
Vol 584-586 ◽  
pp. 1746-1749 ◽  
Author(s):  
Yu Li Cui ◽  
Fu Guo Qian ◽  
Shu Xiu Liu ◽  
Hai Tao Yin
Keyword(s):  
Thermal Conductivity ◽  
Hydrogen Peroxide ◽  
Surface Morphology ◽  
Building Materials ◽  
Mass Density ◽  
High Strength ◽  
Utilization Efficiency ◽  
Foam Concrete ◽  
Low Mass ◽  
Addition Amount

This paper reports the effects of hydrogen peroxide in surface morphology, strength, density, thermal conductivity of foam concrete and hydrogen peroxide utilization efficiency. The results show that these foam concretes are new and innovative building materials with interesting properties: low mass density and high strength when the addition amount of hydrogen peroxide is in 5%~6% range. Responsible for these properties are the macro-and microporosity. Macropores are created by adding hydrogen peroxide in different addition amount. It is also found that the utilization efficiency of hydrogen peroxide is higher when the addition amount of hydrogen peroxide is in the range of 5%~6%.

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