Quantification of Reduction of Nitrogen Oxides by Nitrate Accumulation on Titanium Dioxide Photocatalytic Concrete Pavement

2012 ◽  
Vol 2290 (1) ◽  
pp. 147-153 ◽  
Author(s):  
David Osborn ◽  
Marwa M. Hassan ◽  
Heather Dylla
Keyword(s):  
Nitrogen Oxides ◽  
Photocatalytic Degradation ◽  
Test Site ◽  
Operating Conditions ◽  
Experimental Program ◽  
Rain Event ◽  
Nitrate Accumulation ◽  
Pavement Surface ◽  
Laboratory Test Results ◽  
Activity Measurements

Field trials of photocatalytic pavements were recently initiated and are being considered by many states (e.g., Virginia, Texas, New York, and Missouri). Results from this study are from the country's first air-purifying asphalt and concrete photocatalytic pavements on December 20, 2010. The test area was a pavement site located on the Louisiana State University campus in Baton Rouge. The objective of this study was validation of photocatalytic degradation of nitrogen oxides (NOx) at the test site by measuring nitrate salts (NO3) deposited on the pavement surface. With quantification of the nitrate levels produced in the field attributable to photocatalytic activity, measurements were correlated to laboratory test results of NOx reduction efficiency. A field sampling procedure of NO3 deposited on the pavement surface is presented. On the basis of the results of the experimental program, the proposed method to quantify photocatalytic efficiency through nitrate measurements was successful. There was definite evidence that photocatalytic degradation of NOx was taking place in the treated section. In addition, the photocatalytic process was active during the first 4 days followed by a slight decrease in degradation of NOx. Full regeneration of photo catalytic activity took place through a self-cleaning process during a rain event. Six months of traffic and in-service operating conditions had negligible effects on the efficiency of the photocatalytic coating. In addition, there was good agreement between nitric oxide removal efficiency measured in the field after one day of nitrate accumulation and in the laboratory at the same relative humidity.

scholarly journals Hardware-in-the-loop simulation of wave energy converters based on dielectric elastomer generators

Meccanica ◽  
2021 ◽  
Vol 56 (5) ◽  
pp. 1223-1237
Author(s):  
Giacomo Moretti ◽  
Andrea Scialò ◽  
Giovanni Malara ◽  
Giovanni Gerardo Muscolo ◽  
Felice Arena ◽  
...  
Keyword(s):  
Wave Energy ◽  
Large Scale ◽  
Low Cost ◽  
Test Site ◽  
Dielectric Elastomer ◽  
Operating Conditions ◽  
Polymer Materials ◽  
Hardware In The Loop ◽  
Wave Energy Converters ◽  
Energy Converters

AbstractDielectric elastomer generators (DEGs) are soft electrostatic generators based on low-cost electroactive polymer materials. These devices have attracted the attention of the marine energy community as a promising solution to implement economically viable wave energy converters (WECs). This paper introduces a hardware-in-the-loop (HIL) simulation framework for a class of WECs that combines the concept of the oscillating water columns (OWCs) with the DEGs. The proposed HIL system replicates in a laboratory environment the realistic operating conditions of an OWC/DEG plant, while drastically reducing the experimental burden compared to wave tank or sea tests. The HIL simulator is driven by a closed-loop real-time hydrodynamic model that is based on a novel coupling criterion which allows rendering a realistic dynamic response for a diversity of scenarios, including large scale DEG plants, whose dimensions and topologies are largely different from those available in the HIL setup. A case study is also introduced, which simulates the application of DEGs on an OWC plant installed in a mild real sea laboratory test-site. Comparisons with available real sea-test data demonstrated the ability of the HIL setup to effectively replicate a realistic operating scenario. The insights gathered on the promising performance of the analysed OWC/DEG systems pave the way to pursue further sea trials in the future.

Influence of Operational Parameters on Photocatalytic Degradation of Linuron in Aqueous TiO2 Pillared Montmorillonite Suspension

2021 ◽  
Vol 16 (3) ◽  
pp. 673-685
Author(s):  
D. Hadj Bachir ◽  
Hocine Boutoumi ◽  
H. Khalaf ◽  
Pierre Eloy ◽  
J. Schnee ◽  
...  
Keyword(s):  
Photocatalytic Degradation ◽  
Physicochemical Characterization ◽  
Operating Conditions ◽  
Cod Removal ◽  
Pollutant Concentration ◽  
Catalyst Loading ◽  
Operational Parameters ◽  
X Ray ◽  
Pillared Montmorillonite ◽  
Initial Ph

TiO2 pillared clay was prepared by intercalation of titan polyoxocation into interlamelar space of an Algerian montmorillonite and used for the photocatalytic degradation of the linuron herbicide as a target pollutant in aqueous solution. The TiO2 pillared montmorillonite (Mont-TiO2) was characterized by X-ray photoelectron spectroscopy (XPS), X-Ray diffraction (XRD), X-Ray fluorescence (XRF), scanning electronic microscopy (SEM), thermogravimetry and differential thermal analysis (TG-DTA), Fourier transformed infra-red (FT-IR), specific area and porosity determinations. This physicochemical characterization pointed to successful TiO2 pillaring of the clay. The prepared material has porous structure and exhibit a good thermal stability as indicated by its surface area after calcination by microwave. The effects of operating parameters such as catalyst loading, initial pH of the solution and the pollutant concentration on the photocatalytic efficiency and COD removal  were evaluated. Under initial pH of the solution around seven, pollutant concentration of 10 mg/L and 2.5 g/L of catalyst at room temperature, the degradation efficiency and COD removal of linuron was best then the other operating conditions. It was observed that operational parameters play a major role in the photocatalytic degradation process. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

A Nitrogen Oxides Emission Prediction Model for Gas Turbines Based on Interpretable Multilayer Perceptron Neural Networks

2020 ◽  
Author(s):  
Dawen Huang ◽  
Shanhua Tang ◽  
Dengji Zhou
Keyword(s):  
Neural Networks ◽  
Nitrogen Oxides ◽  
Prediction Model ◽  
Working Conditions ◽  
Gas Turbines ◽  
Middle Layer ◽  
Operating Conditions ◽  
Nox Emission ◽  
Outlet Temperature ◽  
Output Layer

Abstract Gas turbines, an important energy conversion equipment, produce Nitrogen Oxides (NOx) emissions, endangering human health and forming air pollution. With the increasingly stringent NOx emission standards, it is more significant to ascertain NOx emission characteristics to reduce pollutant emissions. Establishing an emission prediction model is an effective way for real-time and accurate monitoring of the NOx discharge amount. Based on the multi-layer perceptron neural networks, an interpretable emission prediction model with a monitorable middle layer is designed to monitor NOx emission by taking the ambient parameters and boundary parameters as the network inputs. The outlet temperature of the compressor is selected as the monitorable measuring parameters of the middle layer. The emission prediction model is trained by historical operation data under different working conditions. According to the errors between the predicted values and measured values of the middle layer and output layer, the weights of the emission prediction model are optimized by the back-propagation algorithm, and the optimal NOx emission prediction model is established for gas turbines under the various working conditions. Furthermore, the mechanism of predicting NOx emission value is explained based on known parameter influence laws between the input layer, middle layer and output layer, which helps to reveal the main measurement parameters affecting NOx emission value, adjust the model parameters and obtain more accurate prediction results. Compared with the traditional emission monitoring methods, the emission prediction model has higher accuracy and faster calculation efficiency and can obtain believable NOx emission prediction results for various operating conditions of gas turbines.

scholarly journals Photocatalytic Degradation of Monolinuron and Linuron in an Aqueous Suspension of Titanium Dioxide Under Simulated Solar Irradiation

2007 ◽  
Vol 20 (2) ◽  
pp. 163-172 ◽  
Author(s):  
Razika Zouaghi ◽  
Abdennour Zertal ◽  
Bernard David ◽  
Sylvie Guittonneau
Keyword(s):  
Photocatalytic Degradation ◽  
Degradation Rate ◽  
Ph Value ◽  
Degradation Kinetics ◽  
Aqueous Suspension ◽  
Operating Conditions ◽  
Solar Irradiation ◽  
Point Of Zero Charge ◽  
Degradation Rates ◽  
Simulated Solar Irradiation

Abstract The photocatalytic degradation of two phenylurea herbicides, monolinuron (MLN) and linuron (LN), was investigated in an aqueous suspension of TiO2 using simulated solar irradiation. The objective of the study was to compare their photocatalytic reactivity and to assess the influence of various parameters such as initial pesticide concentration, catalyst concentration and photonic flux on the photocatalytic degradation rate of MLN and LN. A comparative study of the photocatalytic degradation kinetics of both herbicides showed that these two compounds have a comparable reactivity with TiO2/simulated sun light. Under the operating conditions of this study, the photocatalytic degradation of MLN and LN followed pseudo first-order decay kinetics. The kobs values indicated an inverse dependence on the initial herbicide concentration and were fitted to the Langmuir-Hinshelwood equation. Photocatalytic degradation rates increased with TiO2 dosage, but overdoses did not necessarily increase the photocatalytic efficiency. The degradation rate of MLN increased with radiant flux until an optimum at 580 W m‑2 was reached and then decreased. Under these conditions, an electron-hole recombination was favored. Finally, the photocatalytic degradation rate depended on pH, where an optimum was found at a pH value close to the pH of the point of zero charge (pH = 6).

Effect of Creep Relaxation on the Delayed Hydride Cracking Behavior of Irradiated Zirconium 2.5%Wt Niobium Pressure Tube Material

2006 ◽  
Author(s):  
Heather Chaput ◽  
Brian W. Leitch ◽  
Don R. Metzger
Keyword(s):  
High Stress ◽  
Local Stress ◽  
Operating Conditions ◽  
Experimental Results ◽  
Pressure Tube ◽  
Experimental Program ◽  
Tube Material ◽  
Cracking Behavior ◽  
Delayed Hydride Cracking ◽  
Hydride Cracking

Surface scratches and flaws encountered in CANDU nuclear pressure tubes must be evaluated to ensure that a cracking mechanism, called delayed hydride cracking (DHC), is not initiated. The stress concentration due to a flaw can cause diffusion of hydrogen and precipitation of zirconium hydride at the flaw tip. The presence of a hydride results in reduced fracture resistance in a local region where high stress prevails. In many cases, flaws exist for an extended period of time before the hydrogen content in the base material is sufficient to form a hydride. In this situation high stress creep can significantly relax the local stress at the flaw tip. The assessment of flaws on the basis of local stress distribution not considering creep is expected to be overly conservative, and may result in unnecessary remedial action in reactor operation and maintenance procedures. An experimental program has been developed to isolate and quantify the effect of creep on DHC in irradiated Zr-2.5%Nb pressure tube material. As part of this program, the thermal and load histories relevant to reactor operating conditions have been considered, and initial experimental results indicate that the action of creep increases the threshold load for crack initiation. Finite element analysis of creep relaxation around a hydride also supports the experimental results, and a fracture initiation model is applied to the experimental conditions in order to establish an analytical trend for the effect of creep. The quantitative effect predicted by the model is in reasonable agreement with the experimental results, and an improved, less conservative assessment procedure that accounts for creep is deemed to be practical.

Laboratory test results on self-hardening grouts for flexible cutoffs

1984 ◽  
Vol 21 (1) ◽  
pp. 185-191 ◽  
Author(s):  
Robert P. Chapuis ◽  
J.-Jacques Paré ◽  
André A. Loiselle
Keyword(s):  
Experimental Program ◽  
Test Results ◽  
James Bay ◽  
Cement Slurry ◽  
Cutoff Wall ◽  
Hydroelectric Project ◽  
Solid States ◽  
Bentonite Slurry ◽  
Laboratory Test Results ◽  
Cutoff Walls

The addition of cement to a bentonite slurry gives a complex material called self-hardening grout which slowly sets to become a clay-like solid. The properties of these mixes are highly dependent on the bentonite and the cement used. Most information available up to now comes from European countries where the technique has been developed. As very little information was available about such mixes in North America, an experimental program was initiated to study their applicability for cutoff walls of certain dams of the James Bay hydroelectric project. The present paper describes the characteristics of different mixes tested in their fluid and solid states. Keywords: bentonite, cement, slurry, cutoff wall.

scholarly journals Full-Scale Fracture Propagation Experiments: A Recent Application and Future Use for the Pipeline Industry

2000 ◽  
Author(s):  
D. Michael Johnson ◽  
Peter S. Cumber ◽  
Norval Horner ◽  
Lorne Carlson ◽  
Robert Eiber
Keyword(s):  
Fracture Propagation ◽  
High Strength Steels ◽  
High Strength ◽  
Test Site ◽  
Full Scale ◽  
Operating Conditions ◽  
Test Facility ◽  
Operating Pressure ◽  
Experimental Facility ◽  
The Usa

A full scale fracture propagation test facility has been developed to validate the design, in terms of the ability of the material to avert a propagating fracture, of a major new pipeline to transport gas 1800 miles from British Columbia in Canada to Chicago in the USA. The pipeline, being built by Alliance Pipeline Ltd, will transport rich natural gas, i.e. gas with a higher than normal proportion of heavier hydrocarbons, at a maximum operating pressure of 12,000 kPa. This gas mixture and pressure combination imposes a more severe requirement on the pipe steel toughness than the traditional operating conditions of North American pipelines. As these conditions were outside the validated range of models, two full-scale experiments were conducted to prove the design. This paper will provide details of the construction of the 367m long experimental facility at the BG Technology Spadeadam test site along with the key data obtained from the experiments. Evaluation of this data showed that the test program had validated Alliance’s fracture control design. The decompression data obtained in the experiments will be compared against predictions from a new decompression model developed by BG Technology. The use of the experimental facility and the model to support future developments in the pipeline industry, particularly in relation to the use of high strength steels, will also be discussed.

Wave Rotor Combustor Test Rig Preliminary Design

2004 ◽  
Author(s):  
Berrak Alparslan ◽  
M. Razi Nalim ◽  
Philip H. Snyder
Keyword(s):  
Computational Models ◽  
Combustion Process ◽  
Constant Volume ◽  
Operating Conditions ◽  
Experimental Program ◽  
Preliminary Design ◽  
Wave Rotor ◽  
Test Rig ◽  
Operating Cycle ◽  
And Performance

Pressure gain combustion in a wave rotor approaching the thermodynamic ideal of constant volume combustion has been proposed to significantly enhance the performance of gas turbine engines. A computational and experimental program is currently being conducted to investigate the combustion process and performance of a wave rotor with detonative and near-detonative internal combustion. An innovative and flexible preliminary design of the test rig is presented to demonstrate the operation and performance of the system. A preliminary design method based on a sequence of computational models is used to design wave processes for testing in the rig and to define rig geometry and operating conditions. The operating cycle allows for propagation of the combustion front from the exit end of the combustion channel to the inlet end. This is similar to and motivated by the Constant Volume Combustor (CVC) concept that seeks to produce a relatively uniform set of outflow conditions in both spatial and time coordinates.

Pre Test Calculations on TOPFLOW PTS Experiment With NEPTUNE_CFD Code

2011 ◽  
Author(s):  
A. Martin ◽  
C. Raynaud ◽  
P. Pe´turaud ◽  
C. Heib ◽  
F. Dubois ◽  
...  
Keyword(s):  
Two Phase Flow ◽  
Test Procedure ◽  
Operating Conditions ◽  
Experimental Program ◽  
Phase Flow ◽  
Two Phase ◽  
Loss Of Coolant Accident ◽  
Flow Configurations ◽  
Definition Of ◽  
Physical Phenomena

Hypothetical Small Break Loss Of Coolant Accident is identified as one of the most severe transients leading to a potential huge Pressurized Thermal Shock on the Reactor Pressure Vessel (RPV). This may result in two-phase flow configurations in the cold legs, according to the operating conditions, and to reliably assess the RPV wall integrity, advanced two-phase flow simulations are required. Related needs in development and/or validation of these advanced models are important, and the ongoing TOPFLOW-PTS experimental program was designed to provide a well documented data base to meet these needs. This paper focuses on pre-test NEPTUNE_CFD simulations of TOPFLOW-PTS experiments; these simulations were performed to (i) help in the definition of the test matrix and test procedure, and (ii) check the presence of the different key physical phenomena at the mock-up scale.

scholarly journals An Analytical Study of Nitrogen Oxides and Carbon Monoxide Emissions in Hydrocarbon Combustion With Added Nitrogen: Preliminary Results

1980 ◽  
Author(s):  
D. A. Bittker
Keyword(s):  
Carbon Monoxide ◽  
Nitrogen Oxides ◽  
Analytical Study ◽  
Primary Objective ◽  
Operating Conditions ◽  
Department Of Energy ◽  
Critical Research ◽  
Preliminary Results ◽  
Hydrocarbon Combustion

This work is one part of a four-part Critical Research and Technology Fuels Combustion Program funded by the Department of Energy. The primary objective of this part of the program is to analytically determine the effect of combustor operating conditions on the conversion of fuel-bound nitrogen (FBN) to nitrogen oxides (NOx). The effect of FBN and of operating conditions on carbon monoxide (CO) formation was also studied.

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