73 Matching Results

Results open in a new window/tab.

Shock Compression of Hydrogen and Other Small Molecules (open access)

Shock Compression of Hydrogen and Other Small Molecules

None
Date: July 6, 2001
Creator: Nellis, W J
System: The UNT Digital Library
Metastable metallic hydrogen glass (open access)

Metastable metallic hydrogen glass

The quest for metallic hydrogen has been going on for over one hundred years. Before hydrogen was first condensed into a liquid in 1898, it was commonly thought that condensed hydrogen would be a metal, like the monatomic alkali metals below hydrogen in the first column of the Periodic Table. Instead, condensed hydrogen turned out to be transparent, like the diatomic insulating halogens in the seventh column of the Periodic Table. Wigner and Huntington predicted in 1935 that solid hydrogen at 0 K would undergo a first-order phase transition from a diatomic to a monatomic crystallographically ordered solid at {approx}25 GPa. This first-order transition would be accompanied by an insulator-metal transition. Though searched for extensively, a first-order transition from an ordered diatomic insulator to a monatomic metal is yet to be observed at pressures up to 120 and 340 GPa using x-ray diffraction and visual inspection, respectively. On the other hand, hydrogen reaches the minimum electrical conductivity of a metal at 140 GPa, 0.6 g/cm{sup 3}, and 3000 K. These conditions were achieved using a shock wave reverberating between two stiff sapphire anvils. The shock wave was generated with a two-stage light-gas gun. This temperature exceeds the calculated melting temperature …
Date: February 6, 2001
Creator: Nellis, W J
System: The UNT Digital Library
Relative Advantages of Direct and Indirect Drive for an Inertial Fusion Energy Power Plant Driven by a Diode-Pumped Solid-State Laser (open access)

Relative Advantages of Direct and Indirect Drive for an Inertial Fusion Energy Power Plant Driven by a Diode-Pumped Solid-State Laser

This paper reviews our current understanding of the relative advantages of direct drive (DD) and indirect drive (ID) for a 1 GWe inertial fusion energy (IFE) power plant driven by a diode-pumped solid-state laser (DPSSL). This comparison is motivated by a recent study (1) that shows that the projected cost of electricity (COE) for DD is actually about the same as that for ID even though the target gain for DD can be much larger. We can therefore no longer assume that DD is the ultimate targeting scenario for IFE, and must begin a more rigorous comparison of these two drive options. The comparison begun here shows that ID may actually end up being preferred, but the uncertainties are still rather large.
Date: March 6, 2001
Creator: Orth, C D
System: The UNT Digital Library
Inertial Fusion and High-Energy-Density Science in the United States (open access)

Inertial Fusion and High-Energy-Density Science in the United States

Inertial fusion and high-energy density science worldwide is poised to take a great leap forward. In the US, programs at the University of Rochester, Sandia National Laboratories, Los Alamos National Laboratory, Lawrence Livermore National Laboratory (LLNL), the Naval Research Laboratory, and many smaller laboratories have laid the groundwork for building a facility in which fusion ignition can be studied in the laboratory for the first time. The National Ignition Facility (NIF) is being built by the Department of Energy's National Nuclear Security Agency to provide an experimental test bed for the US Stockpile Stewardship Program (SSP) to ensure the dependability of the country's nuclear deterrent without underground nuclear testing. NIF and other large laser systems being planned such as the Laser MegaJoule (LMJ) in France will also make important contributions to basic science, the development of inertial fusion energy, and other scientific and technological endeavors. NIF will be able to produce extreme temperatures and pressures in matter. This will allow simulating astrophysical phenomena (on a tiny scale) and measuring the equation of state of material under conditions that exist in planetary cores.
Date: September 6, 2001
Creator: Tarter, C B
System: The UNT Digital Library
Selective Catalytic Oxidation of Hydrogen Sulfide to Elemental Sulfur from Coal-Derived Fuel Gases (open access)

Selective Catalytic Oxidation of Hydrogen Sulfide to Elemental Sulfur from Coal-Derived Fuel Gases

The development of low cost, highly efficient, desulfurization technology with integrated sulfur recovery remains a principle barrier issue for Vision 21 integrated gasification combined cycle (IGCC) power generation plants. In this plan, the U. S. Department of Energy will construct ultra-clean, modular, co-production IGCC power plants each with chemical products tailored to meet the demands of specific regional markets. The catalysts employed in these co-production modules, for example water-gas-shift and Fischer-Tropsch catalysts, are readily poisoned by hydrogen sulfide (H{sub 2}S), a sulfur contaminant, present in the coal-derived fuel gases. To prevent poisoning of these catalysts, the removal of H{sub 2}S down to the parts-per-billion level is necessary. Historically, research into the purification of coal-derived fuel gases has focused on dry technologies that offer the prospect of higher combined cycle efficiencies as well as improved thermal integration with co-production modules. Primarily, these concepts rely on a highly selective process separation step to remove low concentrations of H{sub 2}S present in the fuel gases and produce a concentrated stream of sulfur bearing effluent. This effluent must then undergo further processing to be converted to its final form, usually elemental sulfur. Ultimately, desulfurization of coal-derived fuel gases may cost as much as 15% …
Date: November 6, 2001
Creator: Gardner, Todd H.; Berry, David A.; Lyons, K. David; Beer, Stephen K. & Monahan, Michael J.
System: The UNT Digital Library
Angular distributions of electrons photoemitted from core levels of oriented diatomic molecules: Multiple scattering theory in non-spherical potentials (open access)

Angular distributions of electrons photoemitted from core levels of oriented diatomic molecules: Multiple scattering theory in non-spherical potentials

We use multiple scattering in non-spherical potentials (MSNSP) to calculate the angular distributions of electrons photoemitted from the 1s-shells of CO and N2 gas-phase molecules with fixed-in-space orientations. For low photoelectron kinetic energies (E<50 eV), as appropriate to certain shape-resonances, the electron scattering must be represented by non-spherical scattering potentials, which are naturally included in our formalism. Our calculations accurately reproduce the experimental angular patterns recently measured by several groups, including those at the shape-resonance energies. The MSNSP theory thus enhances the sensitivity to spatial electronic distribution and dynamics, paving the way toward their determination from experiment.
Date: September 6, 2001
Creator: Diez Muino, R.; Rolles, D.; Garcia de Abajo, F. J.; Fadley, C. S. & Van Hove, M. A.
System: The UNT Digital Library
ADVANCED STEAM GENERATORS (open access)

ADVANCED STEAM GENERATORS

Concerns about climate change have encouraged significant interest in concepts for ultra-low or ''zero''-emissions power generation systems. In some proposed concepts, nitrogen is removed from the combustion air and replaced with another diluent such as carbon dioxide or steam. In this way, formation of nitrogen oxides is prevented, and the exhaust stream can be separated into concentrated CO{sub 2} and steam or water streams. The concentrated CO{sub 2} stream could then serve as input to a CO{sub 2} sequestration process or utilized in some other way. Some of these concepts are illustrated in Figure 1. This project is an investigation of one approach to ''zero'' emission power generation. Oxy-fuel combustion is used with steam as diluent in a power cycle proposed by Clean Energy Systems, Inc. (CES) [1,2]. In oxy-fuel combustion, air separation is used to produce nearly pure oxygen for combustion. In this particular concept, the combustion temperatures are moderated by steam as a diluent. An advantage of this technique is that water in the product stream can be condensed with relative ease, leaving a pure CO{sub 2} stream suitable for sequestration. Because most of the atmospheric nitrogen has been separated from the oxidant, the potential to form any …
Date: November 6, 2001
Creator: Richards, George A.; Casleton, Kent H.; Lewis, Robie E.; Rogers, William A.; Woike, Mark R. & Willis, Brian P.
System: The UNT Digital Library
Overview of NETL In-House Vision 21 Activities (open access)

Overview of NETL In-House Vision 21 Activities

The Office of Science and Technology at the National Energy Technology Laboratory, conducts research in support of Department of Energy's Fossil Energy Program. The research is funded through a variety of programs with each program focusing on a particular aspect of fossil energy. Since the Vision 21 Concept is based on the Advanced Power System Programs (Integrated Gasification Combined Cycle, Pressurized Fluid Bed, HIPPS, Advanced Turbine Systems, and Fuel Cells) it is not surprising that much of the research supports the Vision 21 Concept. The research is classified and presented according to ''enabling technologies'' and ''supporting technologies'' as defined by the Vision 21 Program. Enabling technology include fuel flexible gasification, fuel flexible combustion, hydrogen separation from fuel gas, advanced combustion systems, circulating fluid bed technology, and fuel cells. Supporting technologies include development of advanced materials, computer simulations, computation al fluid dynamics modeling, and advanced environmental control. An overview of Vision 21 related research is described, emphasizing recent accomplishments and capabilities.
Date: November 6, 2001
Creator: Wildman, David J.
System: The UNT Digital Library
Fuel Cell/Turbine Ultra High Efficiency Power System (open access)

Fuel Cell/Turbine Ultra High Efficiency Power System

FuelCell Energy, INC. (FCE) is currently involved in the design of ultra high efficiency power plants under a cooperative agreement (DE-FC26-00NT40) managed by the National Energy Technology Laboratory (NETL) as part of the DOE's Vision 21 program. Under this project, FCE is developing a fuel cell/turbine hybrid system that integrates the atmospheric pressure Direct FuelCell{reg_sign} (DFC{reg_sign}) with an unfired Brayton cycle utilizing indirect heat recovery from the power plant. Features of the DFC/T{trademark} system include: high efficiency, minimal emissions, simplicity in design, direct reforming internal to the fuel cell, no pressurization of the fuel cell, independent operating pressure of the fuel cell and turbine, and potential cost competitiveness with existing combined cycle power plants at much smaller sizes. Objectives of the Vision 21 Program include developing power plants that will generate electricity with net efficiencies approaching 75 percent (with natural gas), while producing sulfur and nitrogen oxide emissions of less than 0.01 lb/million BTU. These goals are significant improvements over conventional power plants, which are 35-60 percent efficient and produce emissions of 0.07 to 0.3 lb/million BTU of sulfur and nitrogen oxides. The nitrogen oxide and sulfur emissions from the DFC/T system are anticipated to be better than the Vision …
Date: November 6, 2001
Creator: Hossein, Ghezel-Ayagh
System: The UNT Digital Library
Improving Information Technology to Maximize Fenestration Energy Efficiency (open access)

Improving Information Technology to Maximize Fenestration Energy Efficiency

Improving software for the analysis of fenestration product energy efficiency and developing related information technology products that aid in optimizing the use of fenestration products for energy efficiency are essential steps toward ensuring that more efficient products are developed and that existing and emerging products are utilized in the applications where they will produce the greatest energy savings. Given the diversity of building types and designs and the climates in the U.S., no one fenestration product or set of properties is optimal for all applications. Future tools and procedures to analyze fenestration product energy efficiency will need to both accurately analyze fenestration product performance under a specific set of conditions and to look at whole fenestration product energy performance over the course of a yearly cycle and in the context of whole buildings. Several steps have already been taken toward creating fenestration product software that will provide the information necessary to determine which details of a fenestration product's design can be improved to have the greatest impact on energy efficiency, what effects changes in fenestration product design will have on the comfort parameters that are important to consumers, and how specific fenestration product designs will perform in specific applications. Much …
Date: June 6, 2001
Creator: Arasteh, Dariush; Mitchell, Robin; Kohler, Christian; Huizenga,Charlie & Curcija, Dragan
System: The UNT Digital Library
Virtual Simulation of Vision 21 Energy Plants (open access)

Virtual Simulation of Vision 21 Energy Plants

The Vision 21 Energy plants will be designed by combining several individual power, chemical, and fuel-conversion technologies. These independently developed technologies or technology modules can be interchanged and combined to form the complete Vision 21 plant that achieves the needed level of efficiency and environmental performance at affordable costs. The knowledge about each technology module must be captured in computer models so that the models can be linked together to simulate the entire Vision 21 power plant in a Virtual Simulation environment. Eventually the Virtual Simulation will find application in conceptual design, final design, plant operation and control, and operator training. In this project we take the first step towards developing such a Vision 21 Simulator. There are two main knowledge domains of a plant--the process domain (what is in the pipes), and the physical domain (the pipes and equipment that make up the plant). Over the past few decades, commercial software tools have been developed for each of these functions. However, there are three main problems that inhibit the design and operation of power plants: (1) Many of these tools, largely developed for chemicals and refining, have not been widely adopted in the power industry. (2) Tools are not …
Date: November 6, 2001
Creator: Syamlal, Madhava; Felix, Paul E.; Osawe, Maxwell O.; Fiveland, Woodrow A.; Sloan, David G.; Zitney, Stephen E. et al.
System: The UNT Digital Library
Durable Zinc Oxide-Based Regenerable Sorbents for Desulfurization of Syngas in a Fixed-Bed Reactor (open access)

Durable Zinc Oxide-Based Regenerable Sorbents for Desulfurization of Syngas in a Fixed-Bed Reactor

A fixed-bed regenerable desulfurization sorbent, identified as RVS-land developed by researchers at the U.S. Department of Energy's National Energy Technology Laboratory, was awarded the R&D 100 award in 2000 and is currently offered as a commercial product by Sued-Chemie Inc. An extensive testing program for this sorbent was undertaken which included tests at a wide range of temperatures, pressures and gas compositions both simulated and generated in an actual gasifier for sulfidation and regeneration. This testing has demonstrated that during these desulfurization tests, the RVS-1 sorbent maintained an effluent H2S concentration of <5 ppmv at temperatures from 260 to 600 C (500-1100 F) and pressures of 203-2026 kPa(2 to 20 atm) with a feed containing 1.2 vol% H{sub 2}S. The types of syngas tested ranged from an oxygen-blown Texaco gasifier to biomass-generated syngas. The RVS-1 sorbent has high crush strength and attrition resistance, which, unlike past sorbent formulations, does not decrease with extended testing at actual at operating conditions. The sulfur capacity of the sorbent is roughly 17 to 20 wt.% and also remains constant during extended testing (>25 cycles). In addition to H{sub 2}S, the RVS-1 sorbent has also demonstrated the ability to remove dimethyl sulfide and carbonyl sulfide …
Date: November 6, 2001
Creator: Siriwardane, Ranjani V.; Cicero, Daniel C. (U.S. Department of Energy, National Energy Technology Laboratory, Morgantown); Stiegel, Gary J.; Gupta, Raghubir P. (U.S. Department of Energy, National Energy Technology Laboratory, Pittsburgh) & Turk, Brian S. (Research Triangle Institute)
System: The UNT Digital Library
Development of Foster Wheeler's Vision 21 Partial Gasification Module (open access)

Development of Foster Wheeler's Vision 21 Partial Gasification Module

The US Department of Energy (DOE) has awarded Foster Wheeler Development Corporation a contract to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% while producing near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The unique aspect of the process is that it utilizes a pressurized circulating fluidized bed partial gasifier and does not attempt to consume the coal in a single step. To convert all the coal to syngas in a single step requires extremely high temperatures ({approx} 2500 to 2800F) that melt and vaporize the coal and essentially drive all coal ash contaminants into the syngas. …
Date: November 6, 2001
Creator: Robertson, A.
System: The UNT Digital Library
Circulating Fluid-Bed Technology for Advanced Power Systems (open access)

Circulating Fluid-Bed Technology for Advanced Power Systems

Circulating fluid bed technology offers the advantages of a plug flow, yet well-mixed, and high throughput reactor for power plant applications. The ability to effectively scale these systems in size, geometry, and operating conditions is limited because of the extensive deviation from ideal dilute gas-solids flow behavior (Monazam et al., 2001; Li, 1994). Two fluid computations show promise of accurately simulating the hydrodynamics in the riser circulating fluid bed; however, validation tests for large vessels with materials of interest to the power industry are lacking (Guenther et al., 2002). There is little available data in reactors large enough so that geometry (i.e. entrance, exit, and wall) effects do not dominate the hydrodynamics, yet with sufficiently large particle sizes to allow sufficiently large grid sizes to allow accurate and timely hydrodynamic simulations. To meet this need experimental tests were undertaken with relatively large particles of narrow size distribution in a large enough unit to reduce the contributions of wall effects and light enough to avoid geometry effects. While computational fluid dynamic calculations are capable of generating detailed velocity and density profiles, it is believed that the validation and model development begins with the ability to simulate the global flow regime transitions. …
Date: November 6, 2001
Creator: Shadle, Lawrence J.; Ludlow, J. Christopher; Mei, Joseph S. & Guenther, Christopher
System: The UNT Digital Library
Power increase in the STAR-LM generation IV HLMC reactor. (open access)

Power increase in the STAR-LM generation IV HLMC reactor.

None
Date: July 6, 2001
Creator: Sienicki, J. J. & Spencer, B. W.
System: The UNT Digital Library
Interplay of soft and hard processes and hadron pT spectra in pA and AA collisions (open access)

Interplay of soft and hard processes and hadron pT spectra in pA and AA collisions

None
Date: April 6, 2001
Creator: Wang, Enke & Wang, Xin-Nian
System: The UNT Digital Library
Extraction of highly charged ions from the electron beam ion trap at LBNL for applications in surface analysis and Materials Science (open access)

Extraction of highly charged ions from the electron beam ion trap at LBNL for applications in surface analysis and Materials Science

We describe results from highly ion extraction experiments at the Electron Beam Ion Trap (EBIT) facility which is now operated at Lawrence Berkeley National Laboratory after transfer from Lawrence Livermore National Laboratory. Requirements on ion source performance for the application of highly charged ions (e. g. Xe{sup 44+}) in surface analysis and materials science are discussed.
Date: September 6, 2001
Creator: Schenkel, T.; Persaud, A.; Kraemer, A.; McDonald, J. W.; Holder, J. P.; Hamza, A. V. et al.
System: The UNT Digital Library
Synchrotron radiation from electron beams in plasma focusing channels (open access)

Synchrotron radiation from electron beams in plasma focusing channels

Spontaneous radiation emitted from relativistic electrons undergoing betatron motion in a plasma focusing channel is analyzed and application to plasma wakefield accelerator experiments and to the ion channel laser (ICL) are discussed. Important similarities and differences between a free electron laser (FEL) and an ICL are delineated. It is shown that the frequency of spontaneous radiation is a strong function of the betatron strength parameter alpha-beta, which plays a similar role to that of the wiggler strength parameter in a conventional FEL. For alpha-beta > 1, radiation is emitted in numerous harmonics. Furthermore, alpha-beta is proportional to the amplitude of the betatron orbit, which varies for every electron in the beam. The radiation spectrum emitted from an electron beam is calculated by averaging the single electron spectrum over the electron distribution. This leads to a frequency broadening of the radiation spectrum, which places serious limits on the possibility of realizing an ICL.
Date: December 6, 2001
Creator: Esarey, E.; Shadwick, B. A.; Catravas, P. & Leemans, W. P.
System: The UNT Digital Library
Effect of thin-film coating on wear in EGR-contaminated oil. (open access)

Effect of thin-film coating on wear in EGR-contaminated oil.

Increased use of higher-efficiency compression ignition direct injection (CIDI) diesel engines instead of today's gasoline engines will result in reduced fuel consumption and greenhouse gases emissions. However, NO{sub x} and particulate exhaust emissions from diesel engines must be significantly reduced due to their possible adverse health effects. Exhaust gas recirculation (EGR) is an effective way to reduce NO{sub x} emissions from diesel engines, but the particulates and acidic exhaust products in the recirculated gas will contaminate engine lubricant oil by increasing the soot content and total acid number (TAN). These factors will increase the wear rate in many critical engine components and seriously compromise engine durability. We have investigated the use of commercially available thin and hard coatings (TiN, TiCN, TiAlN, and CrN) to mitigate the negative effects of EGR on wear. In tests with the four-ball machine according to ASTM D4172, we found that all the four coatings deposited on M-50 steel significantly reduced wear in EGR-contaminated oils when compared with uncoated M50 steel balls.
Date: December 6, 2001
Creator: Ajayi, O. O.; Aldajah, S. H.; Erdemir, A. & Fenske, G. R.
System: The UNT Digital Library
Structural basis of water specific transport through AQP1 water channel (open access)

Structural basis of water specific transport through AQP1 water channel

None
Date: December 6, 2001
Creator: Sui, Haixin; Han, Bong-Gyoon; Lee, John K.; Walian, Peter & Jap, Bing K.
System: The UNT Digital Library
Comparison of emerging diagnostic tools for large commercial HVAC systems (open access)

Comparison of emerging diagnostic tools for large commercial HVAC systems

Diagnostic software tools for large commercial buildings are being developed to help detect and diagnose energy and other performance problems with building operations. These software applications utilize energy management control system (EMCS) trend log data. Due to the recent development of diagnostic tools, there has been little detailed comparison among the tools and a limited awareness of tool capabilities by potential users. Today, these diagnostic tools focus mainly on air handlers, but the opportunity exists for broadening the scope of the tools to include all major parts of heating, cooling, and ventilation systems in more detail. This paper compares several tools in the following areas: (1) Scope, intent, and background; (2) Data acquisition, pre-processing, and management; (3) Problems detected; (4) Raw data visualization; (5) Manual and automated diagnostic methods and (6) Level of automation. This comparison is intended to provide practitioners and researchers with a picture of the current state of diagnostic tools. There is tremendous potential for these tools to help improve commercial building energy and non-energy performance.
Date: April 6, 2001
Creator: Friedman, Hannah & Piette, Mary Ann
System: The UNT Digital Library
2001 Gordon Research Conference on Laser Diagnostics in Combustion. Final Progress Report (open access)

2001 Gordon Research Conference on Laser Diagnostics in Combustion. Final Progress Report

None
Date: July 6, 2001
Creator: unknown
System: The UNT Digital Library
Chemical freeze-out parameters at RHIC from microscopic model calculations (open access)

Chemical freeze-out parameters at RHIC from microscopic model calculations

None
Date: April 6, 2001
Creator: Bravina, L. V.; Zabrodin, E. E.; Bass, S. A.; Faessler, A.; Fuchs, C.; Gorenstein, M. I. et al.
System: The UNT Digital Library
Advances in ANL reactor physics methods inspired by A. F. Henry. (open access)

Advances in ANL reactor physics methods inspired by A. F. Henry.

None
Date: July 6, 2001
Creator: Khalil, H. S.; Taiwo, T. A.; Yang, W. S. & Finck, P. J.
System: The UNT Digital Library