Afterburning and Combustion in Explosions in Barometric Calorimeters (open access)

Afterburning and Combustion in Explosions in Barometric Calorimeters

None
Date: May 31, 2007
Creator: Reichenbach, H; Neuwald, P & Kuhl, A L
Object Type: Article
System: The UNT Digital Library
Argonne's Laboratory Computing Resource Center : 2006 Annual Report. (open access)

Argonne's Laboratory Computing Resource Center : 2006 Annual Report.

Argonne National Laboratory founded the Laboratory Computing Resource Center (LCRC) in the spring of 2002 to help meet pressing program needs for computational modeling, simulation, and analysis. The guiding mission is to provide critical computing resources that accelerate the development of high-performance computing expertise, applications, and computations to meet the Laboratory's challenging science and engineering missions. In September 2002 the LCRC deployed a 350-node computing cluster from Linux NetworX to address Laboratory needs for mid-range supercomputing. This cluster, named 'Jazz', achieved over a teraflop of computing power (10{sup 12} floating-point calculations per second) on standard tests, making it the Laboratory's first terascale computing system and one of the 50 fastest computers in the world at the time. Jazz was made available to early users in November 2002 while the system was undergoing development and configuration. In April 2003, Jazz was officially made available for production operation. Since then, the Jazz user community has grown steadily. By the end of fiscal year 2006, there were 76 active projects on Jazz involving over 380 scientists and engineers. These projects represent a wide cross-section of Laboratory expertise, including work in biosciences, chemistry, climate, computer science, engineering applications, environmental science, geoscience, information science, materials …
Date: May 31, 2007
Creator: Bair, R. B.; Kaushik, D. K.; Riley, K. R.; Valdes, J. V.; Drugan, C. D. & Pieper, G. P.
Object Type: Report
System: The UNT Digital Library
Biomimetic Membrane for CO2 Capture from Flue Gas (open access)

Biomimetic Membrane for CO2 Capture from Flue Gas

These Phase III experiments successfully addressed several issues needed to characterize a permeator system for application to a pulverized coal (PC) burning furnace/boiler assuming typical post-combustion cleanup devices in place. We completed key laboratory stage optimization and modeling efforts needed to move towards larger scale testing. The SOPO addressed six areas. Task 1--Post-Combustion Particle Cleanup--The first object was to determine if the Carbozyme permeator performance was likely to be reduced by particles (materials) in the flue gas stream that would either obstruct the mouth of the hollow fibers (HF) or stick to the HF bore wall surface. The second, based on the Acceptance Standards (see below), was to determine whether it would be preferable to clean the inlet gas stream (removing acid gases and particulates) or to develop methods to clean the Carbozyme permeator if performance declined due to HF block. We concluded that condensation of particle and particulate emissions, in the heat exchanger, could result in the formation of very sticky sulfate aerosols with a strong likelihood of obtruding the HF. These must be managed carefully and minimized to near-zero status before entering the permeator inlet stream. More extensive post-combustion cleanup is expected to be a necessary expense, independent …
Date: May 31, 2007
Creator: Trachtenberg, Michael C.
Object Type: Report
System: The UNT Digital Library
A Customizable Fuzzy Expert System for Regional and Local Play Analysis (open access)

A Customizable Fuzzy Expert System for Regional and Local Play Analysis

None
Date: May 31, 2007
Creator: Balch, Robert S. & Broadhead, Ronald F.
Object Type: Report
System: The UNT Digital Library
THE DEPENDENCE OF THE DIFFUSION PARAMETERS ON THE DISSOLVED H CONCENTRATION IN THE DILUTE PHASE OF PD H (open access)

THE DEPENDENCE OF THE DIFFUSION PARAMETERS ON THE DISSOLVED H CONCENTRATION IN THE DILUTE PHASE OF PD H

None
Date: May 31, 2007
Creator: Shanahan, K
Object Type: Article
System: The UNT Digital Library
Development and Application of Optimal Design Capability for Coal Gasification Systems (open access)

Development and Application of Optimal Design Capability for Coal Gasification Systems

The basic objective of this research is to develop a model to simulate the performance and cost of oxyfuel combustion systems to capture CO{sub 2} at fossil-fuel based power plants. The research also aims at identifying the key parameters that define the performance and costs of these systems, and to characterize the uncertainties and variability associated with key parameters. The final objective is to integrate the oxyfuel model into the existing IECM-CS modeling framework so as to have an analytical tool to compare various carbon management options on a consistent basis.
Date: May 31, 2007
Creator: Rubin, Edward S.; Rao, Anand B. & Berkenpas, Michael B.
Object Type: Report
System: The UNT Digital Library
Development of a Hydrogasification Process for Co-Production of Substitute Natural Gas (SNG) and Electric Power from Western Coals-Phase I (open access)

Development of a Hydrogasification Process for Co-Production of Substitute Natural Gas (SNG) and Electric Power from Western Coals-Phase I

The Advanced Hydrogasification Process (AHP)--conversion of coal to methane--is being developed through NETL with a DOE Grant and has successfully completed its first phase of development. The results so far are encouraging and have led to commitment by DOE/NETL to begin a second phase--bench scale reactor vessel testing, expanded engineering analysis and economic perspective review. During the next decade new means of generating electricity, and other forms of energy, will be introduced. The members of the AHP Team envision a need for expanded sources of natural gas or substitutes for natural gas, to fuel power generating plants. The initial work the team has completed on a process to use hydrogen to convert coal to methane (pipeline ready gas) shows promising potential. The Team has intentionally slanted its efforts toward the needs of US electric utilities, particularly on fuels that can be used near urban centers where the greatest need for new electric generation is found. The process, as it has evolved, would produce methane from coal by adding hydrogen. The process appears to be efficient using western coals for conversion to a highly sought after fuel with significantly reduced CO{sub 2} emissions. Utilities have a natural interest in the preservation …
Date: May 31, 2007
Creator: Hobbs, Raymond
Object Type: Report
System: The UNT Digital Library
Diffusion Coatings for Corrosion-Resistant Components in Coal Gasification Systems (open access)

Diffusion Coatings for Corrosion-Resistant Components in Coal Gasification Systems

Advanced electric power generation systems use a coal gasifier to convert coal to a gas rich in fuels such as H{sub 2} and CO. The gas stream contains impurities such as H{sub 2}S and HCl, which attack metal components of the coal gas train, causing plant downtime and increasing the cost of power generation. Corrosion-resistant coatings would improve plant availability and decrease maintenance costs, thus allowing the environmentally superior integrated-gasification-combined-cycle (IGCC) plants to be more competitive with standard power-generation technologies. Heat-exchangers, particle filters, turbines, and other components in the IGCC system must withstand the highly sulfiding conditions of the high-temperature coal gas over an extended period of time. The performance of components degrades significantly with time unless expensive high alloy materials are used. Deposition of a suitable coating on a low cost alloy will improve is resistance to such sulfidation attack and decrease capital and operating costs. The alloys used in the gasifier service include austenitic and ferritic stainless steels, nickel-chromium-iron alloys, and expensive nickel-cobalt alloys. The Fe- and Ni-based high-temperature alloys are susceptible to sulfidation attack unless they are fortified with high levels of Cr, Al, and Si. To impart corrosion resistance, these elements need not be in the …
Date: May 31, 2007
Creator: Krishnan, Gopala N.; Malhotra, Ripudaman; Perez, Jordi; Hornbostel, Marc; Lau, Kai-Hung & Sanjurjo, Angel
Object Type: Report
System: The UNT Digital Library
Ecological Data in Support of the Tank Closure and Waste Management Environmental Impact Statement. Part 2: Results of Spring 2007 Field Surveys (open access)

Ecological Data in Support of the Tank Closure and Waste Management Environmental Impact Statement. Part 2: Results of Spring 2007 Field Surveys

This review provides an evaluation of potential impacts of actions that have been proposed under various alternatives to support the closure of the high level waste tanks on the Hanford Site. This review provides a summary of data collected in the field during the spring of 2007 at all of the proposed project sites within 200 East and 200 West Areas, and at sites not previously surveyed. The primary purpose of this review is to provide biological data that can be incorporated into or used to support the Tank Closure and Waste Management Environmental Impact Statement.
Date: May 31, 2007
Creator: Sackschewsky, Michael R. & Downs, Janelle L.
Object Type: Report
System: The UNT Digital Library
Electrokinetic Hydrogen Generation from Liquid WaterMicrojets (open access)

Electrokinetic Hydrogen Generation from Liquid WaterMicrojets

We describe a method for generating molecular hydrogen directly from the charge separation effected via rapid flow of liquid water through a metal orifice, wherein the input energy is the hydrostatic pressure times the volume flow rate. Both electrokinetic currents and hydrogen production rates are shown to follow simple equations derived from the overlap of the fluid velocity gradient and the anisotropic charge distribution resulting from selective adsorption of hydroxide ions to the nozzle surface. Pressure-driven fluid flow shears away the charge balancing hydronium ions from the diffuse double layer and carries them out of the aperture. Downstream neutralization of the excess protons at a grounded target electrode produces gaseous hydrogen molecules. The hydrogen production efficiency is currently very low (ca. 10-6) for a single cylindrical jet, but can be improved with design changes.
Date: May 31, 2007
Creator: Duffin, Andrew M. & Saykally, Richard J.
Object Type: Article
System: The UNT Digital Library
Enhancement of Biogenic Coalbed Methane Production and Back Injection of Coalbed Methane Co-Produced Water (open access)

Enhancement of Biogenic Coalbed Methane Production and Back Injection of Coalbed Methane Co-Produced Water

Biogenic methane is a common constituent in deep subsurface environments such as coalbeds and oil shale beds. Coalbed methane (CBM) makes significant contributions to world natural gas industry and CBM production continues to increase. With increasing CBM production, the production of CBM co-produced water increases, which is an environmental concern. This study investigated the feasibility in re-using CBM co-produced water and other high sodic/saline water to enhance biogenic methane production from coal and other unconventional sources, such as oil shale. Microcosms were established with the selected carbon sources which included coal, oil shale, lignite, peat, and diesel-contaminated soil. Each microcosm contained either CBM coproduced water or groundwater with various enhancement and inhibitor combinations. Results indicated that the addition of nutrients and nutrients with additional carbon can enhance biogenic methane production from coal and oil shale. Methane production from oil shale was much greater than that from coal, which is possibly due to the greater amount of available Dissolved Organic Carbon (DOC) from oil shale. Inconclusive results were observed from the other sources since the incubation period was too low. WRI is continuing studies with biogenic methane production from oil shale.
Date: May 31, 2007
Creator: Jin, Song
Object Type: Text
System: The UNT Digital Library
Experimental and theoretical studies of particle generation afterlaser ablation of copper with background gas at atmosphericpressure (open access)

Experimental and theoretical studies of particle generation afterlaser ablation of copper with background gas at atmosphericpressure

Laser ablation has proven to be an effective method for generating nanoparticles; particles are produced in the laser induced vapor plume during the cooling stage. To understand the in-situ condensation process, a series of time resolved light scattering images were recorded and analyzed. Significant changes in the condensation rate and the shape of the condensed aerosol plume were observed in two background gases, helium and argon. The primary particle shape and size distribution were measured using a transmission electron microscope (TEM), a scanning electron microscope (SEM) and a differential mobility analyzer (DMA). The gas dynamics simulation included nucleation and coagulation within the vapor plume, heat and mass transfer from the vapor plume to the background gas, and heat transfer to the sample. The experimental data and the calculated evolution of the shape of the vapor plume showed the same trend for the spatial distribution of the condensed particles in both background gases. The simulated particle size distribution also qualitatively agreed with the experimental data. It was determined that the laser energy, the physical properties of the background gas (conductivity, diffusivity and viscosity), and the shape of the ablation system (ablation chamber and the layout of the sample) have strong effects …
Date: May 31, 2007
Creator: Wen, Sy-Bor; Mao, Xianglei; Greif, Ralph & Russo, Richard E.
Object Type: Article
System: The UNT Digital Library
Facilitating Oil Industry Access to Federal Lands through Interagency Data Sharing (open access)

Facilitating Oil Industry Access to Federal Lands through Interagency Data Sharing

Much of the environmental and technical data useful to the oil and gas industry and regulatory agencies is now contained in disparate state and federal databases. Delays in coordinating permit approvals between federal and state agencies translate into increased operational costs and stresses for the oil and gas industry. Making federal lease stipulation and area restriction data available on state agency Web sites will streamline a potential lessors review of available leases, encourage more active bidding on unleased federal lands, and give third-party operators independent access to data who otherwise may not have access to lease restrictions and other environmental data. As a requirement of the Energy Policy Conservation Act (EPCA), the Bureau of Land Management (BLM) is in the process of inventorying oil and natural gas resources beneath onshore federal lands and the extent and nature of any stipulation, restrictions, or impediments to the development of these resources. The EPCA Phase 1 Inventory resulted in a collection of GIS coverage files organized according to numerous lease stipulation reference codes. Meanwhile, state agencies also collect millions of data elements concerning oil and gas operations. Much of the oil and gas data nationwide is catalogued in the Ground Water Protection Council's …
Date: May 31, 2007
Creator: Jehn, Paul & Grunewald, Ben
Object Type: Report
System: The UNT Digital Library
A Generalized Eigensolver based on Smoothed Aggregation (GES-SA) for Initializing Smoothed Aggregation Multigrid (SA) (open access)

A Generalized Eigensolver based on Smoothed Aggregation (GES-SA) for Initializing Smoothed Aggregation Multigrid (SA)

Consider the linear system Ax = b, where A is a large, sparse, real, symmetric, and positive definite matrix and b is a known vector. Solving this system for unknown vector x using a smoothed aggregation multigrid (SA) algorithm requires a characterization of the algebraically smooth error, meaning error that is poorly attenuated by the algorithm's relaxation process. For relaxation processes that are typically used in practice, algebraically smooth error corresponds to the near-nullspace of A. Therefore, having a good approximation to a minimal eigenvector is useful to characterize the algebraically smooth error when forming a linear SA solver. This paper discusses the details of a generalized eigensolver based on smoothed aggregation (GES-SA) that is designed to produce an approximation to a minimal eigenvector of A. GES-SA might be very useful as a standalone eigensolver for applications that desire an approximate minimal eigenvector, but the primary aim here is for GES-SA to produce an initial algebraically smooth component that may be used to either create a black-box SA solver or initiate the adaptive SA ({alpha}SA) process.
Date: May 31, 2007
Creator: Brezina, M; Manteuffel, T; McCormick, S; Ruge, J; Sanders, G & Vassilevski, P S
Object Type: Article
System: The UNT Digital Library
Integrated High Temperature Coal-to-Hydrogen System with CO2 Separation (open access)

Integrated High Temperature Coal-to-Hydrogen System with CO2 Separation

A significant barrier to the commercialization of coal-to-hydrogen technologies is high capital cost. The purity requirements for H{sub 2} fuels are generally met by using a series of unit clean-up operations for residual CO removal, sulfur removal, CO{sub 2} removal and final gas polishing to achieve pure H{sub 2}. A substantial reduction in cost can be attained by reducing the number of process operations for H{sub 2} cleanup, and process efficiency can be increased by conducting syngas cleanup at higher temperatures. The objective of this program was to develop the scientific basis for a single high-temperature syngas-cleanup module to produce a pure stream of H{sub 2} from a coal-based system. The approach was to evaluate the feasibility of a 'one box' process that combines a shift reactor with a high-temperature CO{sub 2}-selective membrane to convert CO to CO{sub 2}, remove sulfur compounds, and remove CO{sub 2} in a simple, compact, fully integrated system. A system-level design was produced for a shift reactor that incorporates a high-temperature membrane. The membrane performance targets were determined. System level benefits were evaluated for a coal-to-hydrogen system that would incorporate membranes with properties that would meet the performance targets. The scientific basis for high temperature …
Date: May 31, 2007
Creator: Ruud, James A.; Ku, Anthony; Ramaswamy, Vidya; Wei, Wei & Willson, Patrick
Object Type: Report
System: The UNT Digital Library
ITER Shape Controller and Transport Simulations (open access)

ITER Shape Controller and Transport Simulations

We currently use the CORSICA integrated modeling code for scenario studies for both the DIII-D and ITER experiments. In these simulations, free- or fixed-boundary equilibria are simultaneously converged with thermal evolution determined from transport models providing temperature and current density profiles. Using a combination of fixed boundary evolution followed by free-boundary calculation to determine the separatrix and coil currents. In the free-boundary calculation, we use the state-space controller representation with transport simulations to provide feedback modeling of shape, vertical stability and profile control. In addition to a tightly coupled calculation with simulator and controller imbedded inside CORSICA, we also use a remote procedure call interface to couple the CORSICA non-linear plasma simulations to the controller environments developed within the Mathworks Matlab/Simulink environment. We present transport simulations using full shape and vertical stability control with evolution of the temperature profiles to provide simulations of the ITER controller and plasma response.
Date: May 31, 2007
Creator: Casper, T A; Meyer, W H; Pearlstein, L D & Portone, A
Object Type: Article
System: The UNT Digital Library
JV Task 99-Integrated Risk Analysis and Contaminant Reduction, Watford City, North Dakota (open access)

JV Task 99-Integrated Risk Analysis and Contaminant Reduction, Watford City, North Dakota

The Energy & Environmental Research Center (EERC) conducted a limited site investigation and risk analyses for hydrocarbon-contaminated soils and groundwater at a Construction Services, Inc., site in Watford City, North Dakota. Site investigation confirmed the presence of free product and high concentrations of residual gasoline-based contaminants in several wells, the presence of 1,2-dichloroethane, and extremely high levels of electrical conductivity indicative of brine residuals in the tank area south of the facility. The risk analysis was based on compilation of information from the site-specific geotechnical investigation, including multiphase extraction pilot test, laser induced fluorescence probing, evaluation of contaminant properties, receptor survey, capture zone analysis and evaluation of well head protection area for municipal well field. The project results indicate that the risks associated with contaminant occurrence at the Construction Services, Inc. site are low and, under current conditions, there is no direct or indirect exposure pathway between the contaminated groundwater and soils and potential receptors.
Date: May 31, 2007
Creator: Solc, Jaroslav & Botnen, Barry W.
Object Type: Report
System: The UNT Digital Library
Leakage of CO2 from geologic storage: Role of secondary accumulation at shallow depth (open access)

Leakage of CO2 from geologic storage: Role of secondary accumulation at shallow depth

Geologic storage of CO2 can be a viable technology forreducing atmospheric emissions of greenhouse gases only if it can bedemonstrated that leakage from proposed storage reservoirs and associatedhazards are small or can be mitigated. Risk assessment must evaluatepotential leakage scenarios and develop a rational, mechanisticunderstanding of CO2 behavior during leakage. Flow of CO2 may be subjectto positive feedbacks that could amplify leakage risks and hazards,placing a premium on identifying and avoiding adverse conditions andmechanisms. A scenario that is unfavorable in terms of leakage behavioris formation of a secondary CO2 accumulation at shallow depth. This paperdevelops a detailed numerical simulation model to investigate CO2discharge from a secondary accumulation, and evaluates the role ofdifferent thermodynamic and hydrogeologic conditions. Our simulationsdemonstrate self-enhancing as well as self-limiting feedbacks.Condensation of gaseous CO2, 3-phase flow of aqueous phase -- liquid CO2-- gaseous CO2, and cooling from Joule-Thomson expansion and boiling ofliquid CO2 are found to play important roles in the behavior of a CO2leakage system. We find no evidence that a subsurface accumulation of CO2at ambient temperatures could give rise to a high-energy discharge, aso-called "pneumatic eruption."
Date: May 31, 2007
Creator: Pruess, K.
Object Type: Article
System: The UNT Digital Library
LISSAT Analysis of a Generic Centrifuge Enrichment Plant (open access)

LISSAT Analysis of a Generic Centrifuge Enrichment Plant

The U.S. Department of Energy (DOE) is interested in developing tools and methods for use in designing and evaluating safeguards systems for current and future plants in the nuclear power fuel cycle. The DOE is engaging several DOE National Laboratories in efforts applied to safeguards for chemical conversion plants and gaseous centrifuge enrichment plants. As part of the development, Lawrence Livermore National Laboratory has developed an integrated safeguards system analysis tool (LISSAT). This tool provides modeling and analysis of facility and safeguards operations, generation of diversion paths, and evaluation of safeguards system effectiveness. The constituent elements of diversion scenarios, including material extraction and concealment measures, are structured using directed graphs (digraphs) and fault trees. Statistical analysis evaluates the effectiveness of measurement verification plans and randomly timed inspections. Time domain simulations analyze significant scenarios, especially those involving alternate time ordering of events or issues of timeliness. Such simulations can provide additional information to the fault tree analysis and can help identify the range of normal operations and, by extension, identify additional plant operational signatures of diversions. LISSAT analyses can be used to compare the diversion-detection probabilities for individual safeguards technologies and to inform overall strategy implementations for present and future plants. …
Date: May 31, 2007
Creator: Lambert, H; Elayat, H A; O?Connell, W J; Szytel, L & Dreicer, M
Object Type: Article
System: The UNT Digital Library
Material-based Stratification (open access)

Material-based Stratification

A simple probability model was applied to detection sampling in a room or space in which different surface materials are present. The model assesses the overall detection capability when the sampling and analytical methods have different performance properties for the different materials. The results suggest that some common sampling strategies may not be ideal. In particular: (1) In a single room or area that includes different surface types with different detection properties, do not use a single sampling grid with a common spacing throughout. (2) If it is known or strongly suspected that one material has better detection properties than the other, place all samples on that material. (3) When it is completely unknown which material has the better detection properties, allocate the samples equally between them.
Date: May 31, 2007
Creator: MacQueen, D H
Object Type: Report
System: The UNT Digital Library
Modeling Efforts to Aid in the Prediction of Process Enrichment Levels with the Intent of Identifying Potential Material Diversion (open access)

Modeling Efforts to Aid in the Prediction of Process Enrichment Levels with the Intent of Identifying Potential Material Diversion

As part of an ongoing effort at Lawrence Livermore National Laboratory (LLNL) to enhance analytical models that simulate enrichment and conversion facilities, efforts are underway to develop routines to estimate the total gamma-ray flux and that of specific lines around process piping containing UF{sub 6}. The intent of the simulation modeling effort is to aid in the identification of possible areas where material diversion could occur, as input to an overall safeguards strategy. The operation of an enrichment facility for the production of low enriched uranium (LEU) presents certain proliferation concerns, including both the possibility of diversion of LEU and the potential for producing material enriched to higher-than-declared, weapons-usable levels. Safeguards applied by the International Atomic Energy Agency (IAEA) are designed to provide assurance against diversion or misuse. Among the measures being considered for use is the measurement of radiation fields at various locations in the cascade hall. Our prior efforts in this area have focused on developing a model to predict neutron fields and how they would change during diversion of misuse. The neutron models indicated that while neutron detection useful in monitoring feed and product containers, it was not useful for monitoring process lines. Our current effort is …
Date: May 31, 2007
Creator: Guenther, C F; Elayat, H A; O?Connell, W J & Lambert, H E
Object Type: Article
System: The UNT Digital Library
Nanoscopic Study of the Polarization-Strain Coupling in Relaxor Ferroelectric and the Search for New Relaxor Materials for Transducer and Optical Applications (open access)

Nanoscopic Study of the Polarization-Strain Coupling in Relaxor Ferroelectric and the Search for New Relaxor Materials for Transducer and Optical Applications

SUMMARY Relaxor ferroelectrics exhibit a very unusual polarization behavior from which derive unique electrostrictive, piezoelectric and other properties. This behavior and these properties are due to the presence of nanoscale structural and polar order, the polar nanoregions (PNR), which can easily reorient under very modest external electric field, in stark contrast with conventional ferroelectrics. Moreover, when these nanoregions are aligned, their local distortions add up coherently to a macroscopic strain, hence their remarkable electrostrictive and piezoelectric properties. Initially, we demonstrated this effect in KTa1-xNbxO3 (KTN) and were able to identify the local internal symmetry of the PNR in KTN and explain their behavior under an applied electric field. We then extended the study to the more complicated lead relaxors, PbMg1/3Nb2/3O3 (PMN), PbZn1/3Nb2/3O3 (PZN) and (1-x)(PbZn1/3Nb2/3)O3-(x)PbTiO3 (PZN-PT). In particular, following the evolution of the diffuse intensity in neutron scattering and X-ray measurements, we were able to determine the evolution of the polar order from the pure PZN system to the mixed system, PZN-PT. This evolution with addition of PT, provides a physical basis for the remarkably easy polarization rotation that gives PZN-PT its unique properties for composition near the so-called morphotropic boundary (MPB). Through quasi-elastic and inelastic neutron and Raman scattering, …
Date: May 31, 2007
Creator: Toulouse, J.
Object Type: Report
System: The UNT Digital Library
On the production behavior of enhanced geothermal systems with CO2as working fluid (open access)

On the production behavior of enhanced geothermal systems with CO2as working fluid

Numerical simulation is used to evaluate mass flow and heatextraction rates from enhanced geothermal injection-production systemsthat are operated using either CO2 or water as heat transmission fluid.For a model system patterned after the European hot dry rock experimentat Soultz, we find significantly greater heat extraction rates for CO2 ascompared to water. The strong dependence of CO2 mobility (=density/viscosity) upon temperature and pressure may lead to unusualproduction behavior, where heat extraction rates can actually increasefor a time, even as the reservoir is subject to thermal depletion. Wepresent the first-ever three-dimensional simulations of CO2injection-production systems. These show strong effects of gravity onmass flow and heat extraction, due to the large contrast of CO2 densitybetween cold injection and hot production conditions. The tendency forpreferential flow of cold, dense CO2 along the reservoir bottom can leadto premature thermal breakthrough. The problem can be avoided byproducing from only a limited depth interval at the top of thereservoir.
Date: May 31, 2007
Creator: Pruess, K.
Object Type: Article
System: The UNT Digital Library
OPEN AIR DEMOLITION OF FACILITIES HIGHLY CONTAMINATED WITH PLUTONIUM (open access)

OPEN AIR DEMOLITION OF FACILITIES HIGHLY CONTAMINATED WITH PLUTONIUM

The demolition of highly contaminated plutonium buildings usually is a long and expensive process that involves decontaminating the building to near free- release standards and then using conventional methods to remove the structure. It doesn't, however, have to be that way. Fluor has torn down buildings highly contaminated with plutonium without excessive decontamination. By removing the select source term and fixing the remaining contamination on the walls, ceilings, floors, and equipment surfaces; open-air demolition is not only feasible, but it can be done cheaper, better (safer), and faster. Open-air demolition techniques were used to demolish two highly contaminated buildings to slab-on-grade. These facilities on the Department of Energy's Hanford Site were located in, or very near, compounds of operating nuclear facilities that housed hundreds of people working on a daily basis. To keep the facilities operating and the personnel safe, the projects had to be creative in demolishing the structures. Several key techniques were used to control contamination and keep it within the confines of the demolition area: spraying fixatives before demolition; applying fixative and misting with a fine spray of water as the buildings were being taken down; and demolishing the buildings in a controlled and methodical manner. In …
Date: May 31, 2007
Creator: LLOYD, E.R.
Object Type: Article
System: The UNT Digital Library