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Computer Modeling of Flow, Thermal Condition and Ash Deposition in a Hot-Gas Filtration Device
The objective of the present study is to develop a computational model for simulating the gas flow, thermal condition and ash transport and deposition pattern in the hot-gas filtration systems. The computational model is to provide a virtual tool for design and operation modifications. Particular attention is given to the Particle Control Device (PCD) at the Power Systems Development Facility (PSDF) in Wilsonville, Alabama. For evaluation of gas velocity and temperature field in the vessel, the FLUENT commercial CFD computer code is used. Ash particle transport and deposition pattern was analyzed with the Lagrangian particle tracking approach.
Date:
September 19, 2002
Creator:
Ahmadi, G.; Mazaheri, A.; Liu, C. & Gamwo, I. K.
Object Type:
Article
System:
The UNT Digital Library
Particle Transportation and Deposition in Hot Gas Filter Vessels - a Computational and Experimental Modeling Approach
In this project, a computational modeling approach for analyzing flow and ash transport and deposition in filter vessels was developed. An Eulerian-Lagrangian formulation for studying hot-gas filtration process was established. The approach uses an Eulerian analysis of gas flows in the filter vessel, and makes use of the Lagrangian trajectory analysis for the particle transport and deposition. Particular attention was given to the Siemens-Westinghouse filter vessel at Power System Development Facility in Wilsonville in Alabama. Details of hot-gas flow in this tangential flow filter vessel are evaluated. The simulation results show that the rapidly rotation flow in the spacing between the shroud and the vessel refractory acts as cyclone that leads to the removal of a large fraction of the larger particles from the gas stream. Several alternate designs for the filter vessel are considered. These include a vessel with a short shroud, a filter vessel with no shroud and a vessel with a deflector plate. The hot-gas flow and particle transport and deposition in various vessels are evaluated. The deposition patterns in various vessels are compared. It is shown that certain filter vessel designs allow for the large particles to remain suspended in the gas stream and to deposit …
Date:
July 1, 2002
Creator:
Ahmadi, Goodarz
Object Type:
Report
System:
The UNT Digital Library
EARLY ENTRANCE COPRODUCTION PLANT
The overall objective of this project is the three phase development of an Early Entrance Coproduction Plant (EECP) which produces at least one product from at least two of the following three categories: (1) electric power (or heat), (2) fuels, and (3) chemicals. The objective is to have these products produced by technologies capable of using synthesis gas derived from coal and/or other carbonaceous feedstocks. The objective of Phase I is to determine the feasibility and define the concept for the EECP located at a specific site; develop a Research, Development, and Testing (RD&T) Plan for implementation in Phase II; and prepare a Preliminary Project Financing Plan. The objective of Phase II is to implement the work as outlined in the Phase I RD&T Plan to enhance the development and commercial acceptance of coproduction technology that produces high-value products, particularly those that are critical to our domestic fuel and power requirements. The project will resolve critical knowledge and technology gaps on the integration of gasification and downstream processing to coproduce some combination of power, fuels, and chemicals from coal and/or other carbonaceous feedstocks. The objective of Phase III is to develop an engineering design package and a financing and testing …
Date:
November 22, 2002
Creator:
Ahmed, Mushtaq; Anderson, John H.; Berry, Earl R.; Brent, Fred; He, Ming; Ong, Jimmy O. et al.
Object Type:
Report
System:
The UNT Digital Library
Integrated fuel processor development challenges.
In the absence of a hydrogen-refueling infrastructure, the success of the fuel cell system in the market will depend on fuel processors to enable the use of available fuels, such as gasoline, natural gas, etc. The fuel processor includes several catalytic reactors, scrubbers to remove chemical species that can poison downstream catalysts or the fuel cell electrocatalyst, and heat exchangers. Most fuel cell power applications seek compact, lightweight hardware with rapid-start and load- following capabilities. Although packaging can partially address the size and volume, balancing the performance parameters while maintaining the fuel conversion (to hydrogen) efficiency requires careful integration of the unit operations and processes. Argonne National Laboratory has developed integrated fuel processors that are compact and light, and that operate efficiently. This paper discusses some of the difficulties encountered in the development process, focusing on the factors/components that constrain performance, and areas that need further research and development.
Date:
January 9, 2002
Creator:
Ahmed, S.; Pereira, Lee, S. H. D.; Kaun, T. & Krumpelt, M.
Object Type:
Article
System:
The UNT Digital Library
Scalable Analysis Techniques for Microprocessor Performance Counter Metrics
Contemporary microprocessors provide a rich set of integrated performance counters that allow application developers and system architects alike the opportunity to gather important information about workload behaviors. These counters can capture instruction, memory, and operating system behaviors. Current techniques for analyzing data produced from these counters use raw counts, ratios, and visualization techniques to help users make decisions about their application source code. While these techniques are appropriate for analyzing data from one process, they do not scale easily to new levels demanded by contemporary computing systems. Indeed, the amount of data generated by these experiments is on the order of tens of thousands of data points. Furthermore, if users execute multiple experiments, then we add yet another dimension to this already knotty picture. This flood of multidimensional data can swamp efforts to harvest important ideas from these valuable counters. Very simply, this paper addresses these concerns by evaluating several multivariate statistical techniques on these datasets. We find that several techniques, such as statistical clustering, can automatically extract important features from this data. These derived results can, in turn, be feed directly back to an application developer, or used as input to a more comprehensive performance analysis environment, such as …
Date:
July 24, 2002
Creator:
Ahn, D H & Vetter, J S
Object Type:
Article
System:
The UNT Digital Library
Industrial Complex for Solid Radwaste Management at Chernobyle Nuclear Power Plant
In the framework of the preparation for the decommissioning of the Chernobyl Nuclear Power Plant (ChNPP) an Industrial Complex for Solid Radwaste Management (ICSRM) will be built under the EC TACIS Program in the vicinity of ChNPP. The paper will present the proposed concepts and their integration into existing buildings and installations. Further, the paper will consider the safety cases, as well as the integration of Western and Ukrainian Organizations into a cohesive project team and the requirement to guarantee the fulfillment of both Western standards and Ukrainian regulations and licensing requirements. The paper will provide information on the status of the interim design and the effects of value engineering on the output of basic design phase. The paper therefor summarizes the design results of the involved design engineers of the Design and Process Providers BNFL (LOT 1), RWE NUKEM GmbH (LOT 2 and General) and INITEC (LOT 3).
Date:
February 26, 2002
Creator:
Ahner, S. & Fomin, V. V.
Object Type:
Article
System:
The UNT Digital Library
Contactless Technique for Measuring Minority-Carrier Parameters in Silicon
Characterization of minority-carrier parameters is a primary interest for a range of devices, including solar cells. For 'on-line' testing needs, contactless techniques are mandatory, as any diagnostic requiring contact formation is impractical. Here, we will describe the resonance-coupled photoconductive decay (RCPCD) technique that has proven to be a valuable diagnostic for a number of semiconductor technologies. This technique avoids some of the inherent limitations of microwave reflection. Our system is a pump-probe technique, using an optical pump and a microwave probe (400 to 900 MHz). These low frequency microwaves penetrate most silicon wafers with common doping levels. By varying the optical excitation wavelength, one can probe wafers of standard (300 to 400 {micro}m) wafer thickness. Also, the method is very linear in sample photoconductivity, and we have observed a linear response over more than three orders of magnitude of excess carrier concentration. This attribute allows us to measure the carrier recombination lifetime over many decades of injection level, allowing the use of a procedure that is called injection-level spectroscopy (ILS). The RCPCD technique was developed [1,2,3,4,5,6] at the National Renewable Energy Laboratory (NREL) and has been applied to more than 5000 samples, ranging from small-area thin films to 350-{micro}m-thick, 250-mm-diameter …
Date:
August 1, 2002
Creator:
Ahrenkiel, R. K. & Johnston, S. W.
Object Type:
Article
System:
The UNT Digital Library
Acoustic Separation Technology
Today's restrictive environmental regulations encourage paper mills to close their water systems. Closed water systems increase the level of contaminants significantly. Accumulations of solid suspensions are detrimental to both the papermaking process and the final products. To remove these solids, technologies such as flotation using dissolved air (DAF), centrifuging, and screening have been developed. Dissolved Air Flotation systems are commonly used to clarify whitewater. These passive systems use high pressure to dissolve air into whitewater. When the pressure is released, air micro-bubbles form and attach themselves to fibers and particles, which then float to the surface where they are mechanically skimmed off. There is an economic incentive to explore alternatives to the DAF technology to drive down the cost of whitewater processing and minimize the use of chemicals. The installed capital cost for a DAF system is significant and a typical DAF system takes up considerable space. An alternative approach, which is the subject of this project, involves a dual method combining the advantages of chemical flocculation and in-line ultrasonic clarification to efficiently remove flocculated contaminants from a water stream
Date:
February 22, 2002
Creator:
Ahrens, Fred & Patterson, Tim
Object Type:
Report
System:
The UNT Digital Library
Observation of high energy atmospheric neutrinos with antarctic muon and neutrino detector array
The Antarctic Muon and Neutrino Detector Array (AMANDA) began collecting data with ten strings in 1997. Results from the first year of operation are presented. Neutrinos coming through the Earth from the Northern Hemisphere are identified by secondary muons moving upward through the array. Cosmic rays in the atmosphere generate a background of downward moving muons, which are about 10{sup 6} times more abundant than the upward moving muons. Over 130 days of exposure, we observed a total of about 300 neutrino events. In the same period, a background of 1.05 x 10{sup 9} cosmic ray muon events was recorded. The observed neutrino flux is consistent with atmospheric neutrino predictions. Monte Carlo simulations indicate that 90 percent of these events lie in the energy range 66 GeV to 3.4 TeV. The observation of atmospheric neutrinos consistent with expectations establishes AMANDA-B10 as a working neutrino telescope.
Date:
May 7, 2002
Creator:
Ahrens, J.; Andres, E.; Bai, X.; Barouch, G.; Barwick, S. W.; Bay, R. C. et al.
Object Type:
Article
System:
The UNT Digital Library
Thoughts and ''Facts'' From the Ags Polarized Proton Runs During the 1980s.
This workshop's focus is on considering ways for improving the proton beam polarization that the AGS delivers to the RHIC. This talk attempts to review the first decade of AGS polarization--the 1980's; to briefly describe some aspects of the machine situation, the depolarization avoidance strategies employed and the success achieved in AGS from the perspective of one of those involved.
Date:
November 6, 2002
Creator:
Ahrens, L.
Object Type:
Article
System:
The UNT Digital Library
Calculation of the Mean Energy Loss in the BTA Stripping Foils and Comparison with Measurement
N/A
Date:
July 1, 2002
Creator:
Ahrens, L. & Gardner, C. J.
Object Type:
Report
System:
The UNT Digital Library
Determination of the AGS Injection Kicker Strength from Beam Measurements
N/A
Date:
December 1, 2002
Creator:
Ahrens, L. A. & Gardner, C. J.
Object Type:
Report
System:
The UNT Digital Library
THE RHIC BEAM ABORT SYSTEM - OPERATION DURING THE RHIC 2001 GOLD RUN.
None
Date:
June 2, 2002
Creator:
Ahrens, L.; Mi, J. L. & Zhang, W.
Object Type:
Article
System:
The UNT Digital Library
The Stochastic Engine Initiative: Improving Prediction of Behavior in Geologic Environments We Cannot Directly Observe
The stochastic engine uses modern computational capabilities to combine simulations with observations. We integrate the general knowledge represented by models with specific knowledge represented by data, using Bayesian inferencing and a highly efficient staged Metropolis-type search algorithm. From this, we obtain a probability distribution characterizing the likely configurations of the system consistent with existing data. The primary use will be optimizing knowledge about the configuration of a system for which sufficient direct observations cannot be made. Programmatic applications include underground systems ranging from environmental contamination to military bunkers, optimization of complex nonlinear systems, and timely decision-making for complex, hostile environments such as battlefields or the detection of secret facilities. We create a stochastic ''base representation'' of system configurations (states) from which the values of measurable parameters can be calculated using forward simulators. Comparison of these predictions to actual measurements drives embedded Bayesian inferencing, updating the distributions of states in the base representation using the Metropolis method. Unlike inversion methods that generate a single bestcase deterministic solution, this method produces all the likely solutions, weighted by their likelihoods. This flexible method is best applied to highly non-linear, multi-dimensional problems. Staging of the Metropolis searches permits us to run the simplest model …
Date:
May 9, 2002
Creator:
Aines, R; Nitao, J; Newmark, R; Carle, S; Ramirez, A; Harris, D et al.
Object Type:
Report
System:
The UNT Digital Library
Contaminant-Organic Complexes: Their Structure and Energetics in Surface Decontamination Processes
The current debate over possible decontamination processes for U.S. Department of Energy (DOE) facilities is centered on disparate decontamination problems, but the key contaminants (uranium [U], plutonium [Pu], and neptunium [Np]) are universally important. There is no single decontamination technique or agent for all metal surfaces and contaminants with which DOE is faced. However, more innovative agents used alone or in conjunction with traditional processes can increase the potential to reclaim for future use some of these valuable resources or, at the least, decontaminate the metal surfaces to allow disposal as nonradioactive, nonhazardous material. This debate underscores several important issues: (1) regardless of the decontamination scenario, metal (Fe, U, Pu, Np) oxide film removal from the surface is central to decontamination; and (2) simultaneous oxide dissolution and sequestration of actinide contaminants against re-adsorption to a clean metal surface will influence the efficacy of a process or agent and its cost.
Date:
June 2002
Creator:
Ainsworth, C. C.; Hay, B. P.; Traina, S. J. & Myneni, S. C. B.
Object Type:
Report
System:
The UNT Digital Library
The Effect of Heterogeneity on In-Situ Combustion: The Propagation of Combustion Fronts in Layered Porous Media
This report extend the approach to heterogeneous systems, by considering the simpler case of in-situ combustion in layered porous media (and particularly to a two-layer model). Analytical models were developed to delineate the combined elects of fluid flow, reaction and heat transfer on the dynamics of combustion fronts in layered porous media, using as parameters the thermal coupling between the layers, the heat transfer to the surroundings and the permeability contrast.
Date:
June 11, 2002
Creator:
Akkutlu, I. Yucel & Yortsos, Yanis C.
Object Type:
Report
System:
The UNT Digital Library
Non-Adiabatic Effects on Combustion Front Propagation in Porous Media: Multiplicity of Steady States
The sustained propagation of combustion fronts in porous media is a necessary condition for the success of an in situ combustion project for oil recovery. Compared to other recovery methods, in situ combustion involves the added complexity of exothermic reactions and temperature-dependent chemical kinetics. In the presence of heat losses, the possibility of ignition and extinction (quenching) exists. In this report, we address the properties of combustion fronts propagating at a constant velocity in the presence of heat losses.
Date:
March 11, 2002
Creator:
Akkutlu, I. Yucel & Yortsos, Yanis C.
Object Type:
Report
System:
The UNT Digital Library
MAGNETO-CHEMICAL CHARACTER STUDIES OF NOVEL Fe CATALYSTS FOR COAL LIQUEFACTION
The objectives of the present study are: (1) To synthesize iron catalysts: Fe/MoO{sub 3}, and Fe/Co/MoO{sub 3} employing two distinct techniques: Pyrolysis with organic precursors and Co-precipitation of metal nitrates; (2) To investigate the magnetic character of the catalysts before and after exposure to CO and CO+H{sub 2} by (a) Mossbauer study of Iron (b) Zerofield Nuclear Magnetic Resonance study of Cobalt, and (c) Magnetic character of the catalyst composite; (3) To study the IR active surface species of the catalyst while stimulating (CO--Metal, (CO+H{sub 2})--Metal) interactions, by FTIR Spectroscopy; and (4) To analyze the catalytic character (conversion efficiency and product distribution) in both direct and indirect liquefaction Process and (5) To examine the correlations between the magnetic and chemical characteristics. This report presents the results of our investigation on (a) the effect of metal loading (b) the effect of intermetallic ratio and (c) the effect of catalyst preparation procedure on (i) the magnetic character of the catalyst composite (ii) the IR active surface species of the catalyst and (iii) the catalytic yields for three different metal loadings: 5%, 15%, and 25% (nominal) for three distinct intermetallic ratios (Fe/Co = 0.3, 1.5, 3.0).
Date:
April 1, 2002
Creator:
Akundi, Murty A.; Zhang, Jian H.; Murty, A.N. & Naidu, S.V.
Object Type:
Report
System:
The UNT Digital Library
Laboratory Directed Research and Development FY2001 Annual Report
Established by Congress in 1991, the Laboratory Directed Research and Development (LDRD) Program provides the Department of Energy (DOE)/National Nuclear Security Administration (NNSA) laboratories, like Lawrence Livermore National Laboratory (LLNL or the Laboratory), with the flexibility to invest up to 6% of their budget in long-term, high-risk, and potentially high payoff research and development (R&D) activities to support the DOE/NNSA's national security missions. By funding innovative R&D, the LDRD Program at LLNL develops and extends the Laboratory's intellectual foundations and maintains its vitality as a premier research institution. As proof of the Program's success, many of the research thrusts that started many years ago under LDRD sponsorship are at the core of today's programs. The LDRD Program, which serves as a proving ground for innovative ideas, is the Laboratory's most important single resource for fostering excellent science and technology for today's needs and tomorrow's challenges. Basic and applied research activities funded by LDRD enhance the Laboratory's core strengths, driving its technical vitality to create new capabilities that enable LLNL to meet DOE/NNSA's national security missions. The Program also plays a key role in building a world-class multidisciplinary workforce by engaging the Laboratory's best researchers, recruiting its future scientists and engineers, …
Date:
June 20, 2002
Creator:
Al-Ayat, R
Object Type:
Report
System:
The UNT Digital Library
ADVANCED DIAGNOSTIC TECHNIQUES FOR THREE-PHASE SLURRY BUBBLE COLUMN REACTORS(SBCR)
This report summarizes the accomplishment made during the third year of this cooperative research effort between Washington University, Ohio State University and Air Products and Chemicals. Data processing of the performed Computer Automated Radioactive Particle Tracking (CARPT) experiments in 6 inch column using air-water-glass beads (150 {micro}m) system has been completed. Experimental investigation of time averaged three phases distribution in air-Therminol LT-glass beads (150 {micro}m) system in 6 inch column has been executed. Data processing and analysis of all the performed Computed Tomography (CT) experiments have been completed, using the newly proposed CT/Overall gas holdup methodology. The hydrodynamics of air-Norpar 15-glass beads (150 {micro}m) have been investigated in 2 inch slurry bubble column using Dynamic Gas Disengagement (DGD), Pressure Drop fluctuations, and Fiber Optic Probe. To improve the design and scale-up of bubble column reactors, a correlation for overall gas holdup has been proposed based on Artificial Neural Network and Dimensional Analysis.
Date:
July 25, 2002
Creator:
Al-Dahhan, M.H.; Fan, L.S. & Dudukovic, M.P.
Object Type:
Report
System:
The UNT Digital Library
Effect of Mo Back Contact on Na Out-Diffusion and Device Performance of Mo/Cu(In,Ga)Se2/CdS/ZnO Solar Cells: Preprint
This conference paper describes the molybdenum thin films that were deposited on soda lime glass (SLG) substrates using direct-current planar magnetron sputtering, with a sputtering power density of 1.2 W/cm2. The working gas (Ar) pressure was varied from 0.6 to 16 mtorr to induce changes in the Mo films' morphology and microstructure. Thin films of Cu(In,Ga)Se2 (CIGS) were deposited on the Mo-coated glass using the 3-stage co-evaporation process. The morphology of both the Mo-coated SLG and the CIGS thin films grown on it was examined using high-resolution scanning electron microscopy. Na was depth profiled in the Mo and CIGS films by secondary ion mass spectrometry. The device performance was evaluated under standard conditions of 1000 W/m2 and 25 C. Optimum device performance is found for an intermediate Mo sputtering pressure.
Date:
May 1, 2002
Creator:
Al-Thani, H. A.; Hasoon, F. S.; Young, M.; Asher, S.; Alleman, J. L.; Al-Jassim, M. M. et al.
Object Type:
Article
System:
The UNT Digital Library
Evaporative Evolution of Brines from Synthetic Topoah Spring Tuff Pore Water, Yucca Mountain, NV
We are investigating the evaporation of pore water representative of the designated high-level-nuclear-waste repository at Yucca Mountain, NV to predict the range of brine compositions that may contact waste containers. These brines could form potentially corrosive thin films on the containers and impact their long-term integrity. Here we report the geochemistry of a relatively complex synthetic Topopah Spring Tuff pore water that was progressively evaporated in a series of experiments. The experiments were conducted in a closed vessel, heated to 95 C, and purged with atmospheric CO{sub 2}. Aqueous samples of the evaporating solution were taken and analyzed to determine the evolving water chemistry, and the final solid precipitate was analyzed by X-ray diffraction. The synthetic Topopah Spring Tuff water evolved towards a complex brine that contains about 3 mol% SO{sub 4}, and 2 mol% Ca, 3 mol% K, 5 mol% NO{sub 3}, 40 mol% Cl, and 47 mol% Na. Trends in the solution data and identification of CaSO{sub 4} solids (anhydrite and bassanite) suggest that fluorite, carbonate, sulfate, and Mg-silicate precipitation minimize the corrosion potential of ''sulfate type pore water'' by removing F, Ca, and Mg during the early stages of evaporation.
Date:
November 26, 2002
Creator:
Alai, M & Carroll, S
Object Type:
Article
System:
The UNT Digital Library
Final report: U.S. competitive position in automotive technologies
Patent data are presented and analyzed to assess the U.S. competitive position in eleven advanced automotive technology categories, including automotive fuel cells, hydrogen storage, advanced batteries, hybrid electric vehicles and others. Inventive activity in most of the technologies is found to be growing at a rapid pace, particularly in advanced batteries, automotive fuel cells and ultracapacitors. The U.S. is the clear leader in automotive fuel cells, on-board hydrogen storage and light weight materials. Japan leads in advanced batteries, hybrid electric vehicles, ultracapacitors, and appears to be close to overtaking the U.S. in other areas of power electronics.
Date:
September 30, 2002
Creator:
Albert, Michael B.; Cheney, Margaret; Thomas, Patrick & Kroll, Peter
Object Type:
Report
System:
The UNT Digital Library
SO(10) GUT models and their present success in explaining mass and mixing data
Some features of SO(10) GUT models are reviewed, and a number of such models in the literature are compared. While some have been eliminated by recent neutrino data, others are presently successful in explaining the quark and lepton mass and mixing data. A short description of one very predictive model is given which illustrates some of the features discussed. Future tests of the models are pointed out including one which contrasts sharply with those models based on an L{sub e}-L{sub {mu}}-L{sub {tau}} type symmetry.
Date:
December 13, 2002
Creator:
Albright, Carl H.
Object Type:
Article
System:
The UNT Digital Library