Streamlined Approach for Environmental Restoration Plan for Corrective Action Unit 134: Aboveground Storage Tanks, Nevada Test Site, Nevada (open access)

Streamlined Approach for Environmental Restoration Plan for Corrective Action Unit 134: Aboveground Storage Tanks, Nevada Test Site, Nevada

This Streamlined Approach for Environmental Restoration (SAFER) Plan identifies the activities required for the closure of Corrective Action Unit (CAU) 134, Aboveground Storage Tanks. CAU 134 is currently listed in Appendix III of the Federal Facility Agreement and Consent Order (FFACO) (FFACO, 1996; as amended February 2008) and consists of four Corrective Action Sites (CASs) located in Areas 3, 15, and 29 of the Nevada Test Site (NTS) (Figure 1): (1) CAS 03-01-03, Aboveground Storage Tank; (2) CAS 03-01-04, Tank; (3) CAS 15-01-05, Aboveground Storage Tank; and (4) CAS 29-01-01, Hydrocarbon Stain. CAS 03-01-03 consists of a mud tank that is located at the intersection of the 3-07 and the 3-12 Roads in Area 3 of the NTS. The tank and its contents are uncontaminated and will be dispositioned in accordance with applicable federal, state, and local regulations. This CAS will be closed by taking no further action. CAS 03-01-04 consists of a potable water tank that is located at the Core Complex in Area 3 of the NTS. The tank will be closed by taking no further action. CAS 15-01-05 consists of an aboveground storage tank (AST) and associated impacted soil, if any. This CAS is located on a …
Date: May 31, 2008
Creator: National Security Technologies, LLC
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
Toxicology Studies of Lewisite and Sulfur Mustard Agents: Genetic Toxicity of Lewisite (L) In Chinese Hamster Ovary Cells (open access)

Toxicology Studies of Lewisite and Sulfur Mustard Agents: Genetic Toxicity of Lewisite (L) In Chinese Hamster Ovary Cells

The cytotoxic clastogenic and mutagenic effects of the arsenic containing vesicant, Lewisite (L) [dichloro(2-chlorovinyl) arsine], have been investigated using Chinese hamster ovary cells. One hour exposures to Lewisite were cytotoxic in uM amounts. The cell survival response yields a D37 of 0.6 uM and an extrapolation number of 2.5. The mutagenic response at the hypoxantnine-guanine phosporibosyl transferase (HGPRT) locus was sporadic and not significantly greater than control values when cells were exposed over a range of 0.125 to2.0 uM. Sister chromatid exchange (SCE) induction, a measure of chromosomal rearrangement, was weakly positive over a range of 0.25 to 1.0 uM but the values were not significantly greater than the control response. Chromosomal aberrations were induced at 0.75 and 1.0 UMin one experiment and 0.5 and 0.75 uM in another experiment. The Induced values were significantly greater than the control values. Lewisite appears to be cytotoxic and clastogenic in our investigations but SCE and mutation at the HGPRT locus are not significantly greater than control values. Lewisita toxicity was in some ways similar to radiomimetic chemicals such as bleomycin.
Date: May 31, 1989
Creator: Jostes Jr., R. F.; Sasser, L. B. & Rausch, R. J.
Object Type: Report
System: The UNT Digital Library
Analyzing the Effects of Temporal Wind Patterns on the Value ofWind-Generated Electricity at Different Sites in California and theNorthwest (open access)

Analyzing the Effects of Temporal Wind Patterns on the Value ofWind-Generated Electricity at Different Sites in California and theNorthwest

Wind power production varies on a diurnal and seasonal basis. In this report, we use wind speed data modeled by TrueWind Solutions, LLC (now AWS Truewind) to assess the effects of wind timing on the value of electric power from potential wind farm locations in California and the Northwest. (Data from this dataset are referred to as ''TrueWind data'' throughout this report.) The intra-annual wind speed variations reported in the TrueWind datasets have not previously been used in published work, however, so we also compare them to a collection of anemometer wind speed measurements and to a limited set of actual wind farm production data. The research reported in this paper seeks to answer three specific questions: (1) How large of an effect can the temporal variation of wind power have on the value of wind in different wind resource areas? (2) Which locations are affected most positively or negatively by the seasonal and diurnal timing of wind speeds? (3) How compatible are wind resources in the Northwest and California with wholesale power prices and loads in either region? The latter question is motivated by the fact that wind power projects in the Northwest could sell their output into California …
Date: May 31, 2006
Creator: Fripp, Matthias & Wiser, Ryan
Object Type: Report
System: The UNT Digital Library
Detection of Periodic Beacon Loads in Electrical Distribution Substation Data (open access)

Detection of Periodic Beacon Loads in Electrical Distribution Substation Data

This research explores methods for identifying a whether a load is sending a signal to the utility SCADA system. Such a system can identify whether various loads are signialing using existing SCADA infrastructure, that is, without added, high cost communications infrastructure.
Date: May 31, 2006
Creator: Hammerstrom, Donald J.; Guttromson, Ross T.; Lu, Ning; Boyd, Paul A.; Trudnowski, Daniel; Chassin, David P. et al.
Object Type: Report
System: The UNT Digital Library
Next Generation Engineered Materials for Ultra Supercritical Steam Turbines (open access)

Next Generation Engineered Materials for Ultra Supercritical Steam Turbines

To reduce the effect of global warming on our climate, the levels of CO{sub 2} emissions should be reduced. One way to do this is to increase the efficiency of electricity production from fossil fuels. This will in turn reduce the amount of CO{sub 2} emissions for a given power output. Using US practice for efficiency calculations, then a move from a typical US plant running at 37% efficiency to a 760 C /38.5 MPa (1400 F/5580 psi) plant running at 48% efficiency would reduce CO2 emissions by 170kg/MW.hr or 25%. This report presents a literature review and roadmap for the materials development required to produce a 760 C (1400 F) / 38.5MPa (5580 psi) steam turbine without use of cooling steam to reduce the material temperature. The report reviews the materials solutions available for operation in components exposed to temperatures in the range of 600 to 760 C, i.e. above the current range of operating conditions for today's turbines. A roadmap of the timescale and approximate cost for carrying out the required development is also included. The nano-structured austenitic alloy CF8C+ was investigated during the program, and the mechanical behavior of this alloy is presented and discussed as an …
Date: May 31, 2006
Creator: Arrell, Douglas
Object Type: Report
System: The UNT Digital Library
Final Report: Thermal Conductance of Solid-Liquid Interfaces (open access)

Final Report: Thermal Conductance of Solid-Liquid Interfaces

Research supported by this grant has significantly advanced fundamental understanding of the thermal conductance of solid-liquid interfaces, and the thermal conductivity of nanofluids and nanoscale composite materials. • The thermal conductance of interfaces between carbon nanotubes and a surrounding matrix of organic molecules is exceptionally small and this small value of the interface conductance limits the enhancement in thermal conductivity that can be achieved by loading a fluid or a polymer with nanotubes. • The thermal conductance of interfaces between metal nanoparticles coated with hydrophilic surfactants and water is relatively high and surprisingly independent of the details of the chemical structure of the surfactant. • We extended our experimental methods to enable studies of planar interfaces between surfactant-coated metals and water where the chemical functionalization can be varied between strongly hydrophobic and strongly hydrophilic. The thermal conductance of hydrophobic interfaces establishes an upper-limit of 0.25 nm on the thickness of the vapor-layer that is often proposed to exist at hydrophobic interfaces. • Our high-precision measurements of fluid suspensions show that the thermal conductivity of fluids is not significantly enhanced by loading with a small volume fraction of spherical nanoparticles. These experimental results directly contradict some of the anomalous results in …
Date: May 31, 2006
Creator: Cahil, David, G. & Braun, Paul, V.
Object Type: Report
System: The UNT Digital Library
Support of Activities of the NAS in Relation to the Radiation Effects Research Foundation (open access)

Support of Activities of the NAS in Relation to the Radiation Effects Research Foundation

The National Academies (NA) provides support for the activities related to the long-term follow up of the health of the survivors of the atomic bombings of Hiroshima and Nagasaki being conducted by the Radiation Effects Research Foundation (RERF) laboratories in Hiroshima and Nagasaki, Japan. The NA serves as scientific and administrative liaison between the U.S. Department of Energy (DOE) and RERF, and performs tasks in the areas of scientific oversight, information/public interface, fiscal oversight, and personnel management. The project includes recruitment and support of approximately 10 NA employees who work at RERF in Japan. Specific activities are performed consistent with the cooperative agreement’s Statement of Work between DOE and NA and consistent with an Annual Work Plan developed by DOE and NA.
Date: May 31, 2006
Creator: Douple, Evan B.
Object Type: Report
System: The UNT Digital Library
Electron emission and defect formation in the interaction of slow,highly charged ions with diamond surfaces (open access)

Electron emission and defect formation in the interaction of slow,highly charged ions with diamond surfaces

We report on electron emission and defect formation in theinteraction between slow (v~;0.3 vBohr) highly charged ions (SHCI) withinsulating (type IIa) and semiconducting (type IIb) diamonds. Electronemission induced by 31Pq+ (q=5 to 13), and 136Xeq+ (q=34 to 44) withkinetic energies of 9 kVxq increase linearly with the ion charge states,reaching over 100 electrons per ion for high xenon charge states withoutsurface passivation of the diamond with hydrogen. Yields from bothdiamond types are up to a factor of two higher then from reference metalsurfaces. Crater like defects with diameters of 25 to 40 nm are formed bythe impact of single Xe44+ ions. High secondary electron yields andsingle ion induced defects enable the formation of single dopant arrayson diamond surfaces.
Date: May 31, 2006
Creator: Sideras-Haddad, E.; Shrivastava, S.; Rebuli, D.B.; Persaud, A.; Schneider, D.H. & Schenkel, T.
Object Type: Article
System: The UNT Digital Library
TEMPEST Simulations of Collisionless Damping of Geodesic-Acoustic Mode in Edge Plasma Pedestal (open access)

TEMPEST Simulations of Collisionless Damping of Geodesic-Acoustic Mode in Edge Plasma Pedestal

The fully nonlinear 4D TEMPEST gyrokinetic continuum code produces frequency, collisionless damping of geodesic-acoustic mode (GAM) and zonal flow with fully nonlinear Boltzmann electrons for the inverse aspect ratio {epsilon}-scan and the tokamak safety factor q-scan in homogeneous plasmas. The TEMPEST simulation shows that GAM exists in edge plasma pedestal for steep density and temperature gradients, and an initial GAM relaxes to the standard neoclassical residual, rather than Rosenbluth-Hinton residual due to the presence of ion-ion collisions. The enhanced GAM damping explains experimental BES measurements on the edge q scaling of the GAM amplitude.
Date: May 31, 2007
Creator: Xu, X; Xiong, Z; Nevins, W & McKee, G
Object Type: Article
System: The UNT Digital Library
Summary of operations and performance of the Murdock site restoration project in June 2005-December 2006. (open access)

Summary of operations and performance of the Murdock site restoration project in June 2005-December 2006.

This document summarizes the performance of the groundwater and surface water restoration systems installed by the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) at the former CCC/USDA grain storage facility in Murdock, Nebraska, during the initial period of systems operation, from June 2005 through December 2006. In the Murdock project, several innovative technologies are being used to remove carbon tetrachloride contamination from a shallow aquifer underlying the town, as well as from water naturally discharged to the surface at the headwaters of a small creek (a tributary to Pawnee Creek) north of the town (Figure 1.1). The restoration activities at Murdock are being conducted by the CCC/USDA as a non-time-critical removal action under the regulatory authority and supervision of the U.S. Environmental Protection Agency (EPA), Region VII. Argonne National Laboratory assisted the CCC/USDA by providing technical oversight for the restoration effort and facilities during this review period. Included in this report are the results of all sampling and monitoring activities performed in accord with the EPA-approved Monitoring Plan for this site (Argonne 2006), as well as additional investigative activities conducted during the review period. This document presents overviews of the treatment facilities (Section 2) and site operations …
Date: May 31, 2007
Creator: LaFreniere, L. M.
Object Type: Report
System: The UNT Digital Library
Developing Innovative Wall Systems that Improve Hygrothermal Performance of Residential Buildings (open access)

Developing Innovative Wall Systems that Improve Hygrothermal Performance of Residential Buildings

This document serves as the Topical Report documenting work completed by Washington State University (WSU) under U.S. Department of Energy Grant, Developing Innovative Wall Systems that Improve Hygrothermal Performance of Residential Buildings. This project was conducted in collaboration with Oak Ridge National Laboratory (ORNL), and includes the participation of several industry partners including Weyerhaeuser, APA - The Engineered Wood Association, CertainTeed Corporation and Fortifiber. This document summarizes work completed by Washington State University August 2002 through June 2006. WSU's primary experimental role is the design and implementation of a field testing protocol that monitored long term changes in the hygrothermal response of wall systems. During the project period WSU constructed a test facility, developed a matrix of test wall designs, constructed and installed test walls in the test facility, installed instrumentation in the test walls and recorded data from the test wall specimens. Each year reports were published documenting the hygrothermal response of the test wall systems. Public presentation of the results was, and will continue to be, made available to the building industry at large by industry partners and the University.
Date: May 31, 2006
Creator: Tichy, Robert & Murray, Chuck
Object Type: Report
System: The UNT Digital Library
GridLAB-D Technical Support Document: Tape Modules Version 1.0 (open access)

GridLAB-D Technical Support Document: Tape Modules Version 1.0

GridLAB-D Technical Support Document describing tape modules, version 1.0.
Date: May 31, 2008
Creator: Chassin, David P.
Object Type: Report
System: The UNT Digital Library
Hydrogen Production via a Commercially Ready Inorganic Membrane Reactor, Semi-Annual Technical Progress Report: October 200[5] - March 2006 (open access)

Hydrogen Production via a Commercially Ready Inorganic Membrane Reactor, Semi-Annual Technical Progress Report: October 200[5] - March 2006

One of the technical barriers for ceramic membranes is its scale up potential. The conventional ceramic membranes/modules originally developed for liquid phase applications are costly and not suitable for high temperature applications. One of the objectives under this project is the development of a ceramic membrane/module, which is economical and suitable for high temperature applications proposed under this project (200-300 C). During this period, we initiated the fabrication of a prototype ceramic membrane module which can be (1) qualified for the proposed application temperature, and (2) cost acceptable for large scale applications. A prototype ceramic membrane bundle (3-inch diameter and 35-inch L) has been prepared, which passes the temperature stability requirement. It also meets the low end of the burst pressure requirement, i.e., 500-750 psi. In the next period, we will continue the improvement of this prototype module to upgrade its burst pressure to 1000 to 1500 psi range. In addition, bench-top experimental study has been conducted in this period to verify satisfactorily the simulated results for the process scheme developed in the last report, which took into the consideration of streamlining the pre- and post-treatment. The sensitivity analysis indicates that membrane surface area requirement is a key operating parameter …
Date: May 31, 2006
Creator: Liu, Paul K. T.
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
GridLAB-D Technical Support Document: Climate Module Version 1.0 (open access)

GridLAB-D Technical Support Document: Climate Module Version 1.0

GridLAB-D technical support document discussing climate module.
Date: May 31, 2008
Creator: Tenney, Nathan D.
Object Type: Report
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
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
Second Generation MOF's for Hydrogen Storage (open access)

Second Generation MOF's for Hydrogen Storage

This final technical report summarizes work exploring strategies to generate second generation metal organic frameworks (MOFs). These strategies were (a) the formation of interpenetrated frameworks and (b) the generation of coordinatively unsaturated metal centers (open metal sites). In the first phase of the project the effectiveness of these strategies was evaluated experimentally by measuring the saturation hydrogen uptake at high pressure and low temperature of 14 MOFs. The results of these studies demonstrated that surface area is the most useful parameter that correlates with ultimate hydrogen capacity. The strategy of interpenetration has so far failed to produce MOFs with high surface areas and therefore high saturation capacities for hydrogen have not been achieved. The incorporation of coordinatively unsaturated metal centers, however, is a promising strategy that allows higher heats of H2 adsorption to be realized without compromising surface area. Based on these initial findings, research efforts in phase two have concentrated on the discovery of new ultrahigh surface area materials with metal centers capable of supporting coordinative unsaturation without structural collapse. One approach has been the synthesis of new organic linkers that have more exposed edges, which is a factor that contributes to increasing surface area, at least when considering …
Date: May 31, 2008
Creator: Matzger, Adam
Object Type: Report
System: The UNT Digital Library
Conceptual Design of a Nuclear Ram Jet-Rocket Missile (open access)

Conceptual Design of a Nuclear Ram Jet-Rocket Missile

The conceptual design of a nuclear ram jet-rocket missile is preserved. This missile is a modified, scaled-up AC-210 nuclear ram jet carrying ammonia in the space enclosed by the spike and inlet diffuser. The payload may be a 10,000 pound thermonuclear weapon or equivalent weight of reconnaissance equipment plus local shielding as in the AC-210 missile. The payload for a missile of body size equivalent to the AC-210 will be reduced by the weight of ammonia.
Date: May 31, 1956
Creator: Szekely, T.
Object Type: Report
System: The UNT Digital Library
Breaking Barriers to Low-Cost Modular Inverter Production & Use (open access)

Breaking Barriers to Low-Cost Modular Inverter Production & Use

The goal of this cost share contract is to advance key technologies to reduce size, weight and cost while enhancing performance and reliability of Modular Inverter Product for Distributed Energy Resources (DER). Efforts address technology development to meet technical needs of DER market protection, isolation, reliability, and quality. Program activities build on SatCon Technology Corporation inverter experience (e.g., AIPM, Starsine, PowerGate) for Photovoltaic, Fuel Cell, Energy Storage applications. Efforts focused four technical areas, Capacitors, Cooling, Voltage Sensing and Control of Parallel Inverters. Capacitor efforts developed a hybrid capacitor approach for conditioning SatCon's AIPM unit supply voltages by incorporating several types and sizes to store energy and filter at high, medium and low frequencies while minimizing parasitics (ESR and ESL). Cooling efforts converted the liquid cooled AIPM module to an air-cooled unit using augmented fin, impingement flow cooling. Voltage sensing efforts successfully modified the existing AIPM sensor board to allow several, application dependent configurations and enabling voltage sensor galvanic isolation. Parallel inverter control efforts realized a reliable technique to control individual inverters, connected in a parallel configuration, without a communication link. Individual inverter currents, AC and DC, were balanced in the paralleled modules by introducing a delay to the individual PWM …
Date: May 31, 2005
Creator: Borowy, Bogdan; Casey, Leo; Foshage, Jerry; Nichols, Steve & Perkinson, Jim
Object Type: Report
System: The UNT Digital Library
Establishment of an Environmental Control Technology Laboratory with a Circulating Fluidized-Bed Combustion System (open access)

Establishment of an Environmental Control Technology Laboratory with a Circulating Fluidized-Bed Combustion System

On February 14, 2002, President Bush announced the Clear Skies Initiative, a legislative proposal to control the emissions of nitrogen oxides (NO{sub x}), sulfur dioxide (SO{sub 2}), and mercury from power plants. In response to this initiative, the National Energy Technology Laboratory organized a Combustion Technology University Alliance and hosted a Solid Fuel Combustion Technology Alliance Workshop. The workshop identified multi-pollutant control; improved sorbents and catalysts; mercury monitoring and capture; and improved understanding of the underlying reaction chemistry occurring during combustion as the most pressing research needs related to controlling environmental emissions from fossil-fueled power plants. The Environmental Control Technology Laboratory will help meet these challenges and offer solutions for problems associated with emissions from fossil-fueled power plants. The goal of this project was to develop the capability and technology database needed to support municipal, regional, and national electric power generating facilities to improve the efficiency of operation and solve operational and environmental problems. In order to effectively provide the scientific data and the methodologies required to address these issues, the project included the following aspects: (1) Establishing an Environmental Control Technology Laboratory using a laboratory-scale, simulated fluidized-bed combustion (FBC) system; (2) Designing, constructing, and operating a bench-scale (0.6 MW{sub …
Date: May 31, 2008
Creator: Pan, Wei-Ping; Cao, Yan & Smith, John
Object Type: Report
System: The UNT Digital Library
Detonation of Meta-stable Clusters (open access)

Detonation of Meta-stable Clusters

We consider the energy accumulation in meta-stable clusters. This energy can be much larger than the typical chemical bond energy (~;;1 ev/atom). For example, polymeric nitrogen can accumulate 4 ev/atom in the N8 (fcc) structure, while helium can accumulate 9 ev/atom in the excited triplet state He2* . They release their energy by cluster fission: N8 -> 4N2 and He2* -> 2He. We study the locus of states in thermodynamic state space for the detonation of such meta-stable clusters. In particular, the equilibrium isentrope, starting at the Chapman-Jouguet state, and expanding down to 1 atmosphere was calculated with the Cheetah code. Large detonation pressures (3 and 16 Mbar), temperatures (12 and 34 kilo-K) and velocities (20 and 43 km/s) are a consequence of the large heats of detonation (6.6 and 50 kilo-cal/g) for nitrogen and helium clusters respectively. If such meta-stable clusters could be synthesized, they offer the potential for large increases in the energy density of materials.
Date: May 31, 2008
Creator: Kuhl, Allen; Kuhl, Allen L.; Fried, Laurence E.; Howard, W. Michael; Seizew, Michael R.; Bell, John B. et al.
Object Type: Article
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