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Sample records for reactive gas solids

  1. Gas sampling system for reactive gas-solid mixtures

    DOEpatents

    Daum, Edward D.; Downs, William; Jankura, Bryan J.; McCoury, Jr., John M.

    1990-01-01

    An apparatus and method for sampling gas containing a reactive particulate solid phase flowing through a duct and for communicating a representative sample to a gas analyzer. A sample probe sheath 32 with an angular opening 34 extends vertically into a sample gas duct 30. The angular opening 34 is opposite the gas flow. A gas sampling probe 36 concentrically located within sheath 32 along with calibration probe 40 partly extends in the sheath 32. Calibration probe 40 extends further in the sheath 32 than gas sampling probe 36 for purging the probe sheath area with a calibration gas during calibration.

  2. Gas sampling system for reactive gas-solid mixtures

    DOEpatents

    Daum, Edward D.; Downs, William; Jankura, Bryan J.; McCoury, Jr., John M.

    1989-01-01

    An apparatus and method for sampling a gas containing a reactive particulate solid phase flowing through a duct and for communicating a representative sample to a gas analyzer. A sample probe sheath 32 with an angular opening 34 extends vertically into a sample gas duct 30. The angular opening 34 is opposite the gas flow. A gas sampling probe 36 concentrically located within sheath 32 along with calibration probe 40 partly extend in the sheath 32. Calibration probe 40 extends further in the sheath 32 than gas sampling probe 36 for purging the probe sheath area with a calibration gas during calibration.

  3. Quantum State-Resolved Reactive and Inelastic Scattering at Gas-Liquid and Gas-Solid Interfaces

    NASA Astrophysics Data System (ADS)

    Grütter, Monika; Nelson, Daniel J.; Nesbitt, David J.

    2012-06-01

    Quantum state-resolved reactive and inelastic scattering at gas-liquid and gas-solid interfaces has become a research field of considerable interest in recent years. The collision and reaction dynamics of internally cold gas beams from liquid or solid surfaces is governed by two main processes, impulsive scattering (IS), where the incident particles scatter in a few-collisions environment from the surface, and trapping-desorption (TD), where full equilibration to the surface temperature (T{TD}≈ T{s}) occurs prior to the particles' return to the gas phase. Impulsive scattering events, on the other hand, result in significant rotational, and to a lesser extent vibrational, excitation of the scattered molecules, which can be well-described by a Boltzmann-distribution at a temperature (T{IS}>>T{s}). The quantum-state resolved detection used here allows the disentanglement of the rotational, vibrational, and translational degrees of freedom of the scattered molecules. The two examples discussed are (i) reactive scattering of monoatomic fluorine from room-temperature ionic liquids (RTILs) and (ii) inelastic scattering of benzene from a heated (˜500 K) gold surface. In the former experiment, rovibrational states of the nascent HF beam are detected using direct infrared absorption spectroscopy, and in the latter, a resonace-enhanced multi-photon-ionization (REMPI) scheme is employed in combination with a velocity-map imaging (VMI) device, which allows the detection of different vibrational states of benzene excited during the scattering process. M. E. Saecker, S. T. Govoni, D. V. Kowalski, M. E. King and G. M. Nathanson Science 252, 1421, 1991. A. M. Zolot, W. W. Harper, B. G. Perkins, P. J. Dagdigian and D. J. Nesbitt J. Chem. Phys 125, 021101, 2006. J. R. Roscioli and D. J. Nesbitt Faraday Disc. 150, 471, 2011.

  4. Reactive flow in solids

    NASA Astrophysics Data System (ADS)

    Brassart, Laurence; Suo, Zhigang

    2013-01-01

    When guest atoms diffuse into a host solid and react, the host may flow inelastically. Often a reaction can stimulate flow in a host too brittle to flow under a mechanical load alone. We formulate a theory of reactive flow in solids by regarding both flow and reaction as nonequilibrium processes, and placing the driving forces for flow and reaction on equal footing. We construct chemomechanical rate-dependent kinetic models without yield strength. In a host under constant stress and chemical potential, flow will persist indefinitely, but reaction will arrest. We also construct chemomechanical yield surface and flow rule by extending the von Mises theory of plasticity. We show that the host under a constant deviatoric stress will flow gradually in response to ramp chemical potential, and will ratchet in response to cyclic chemical potential.

  5. The study of alternate, solid-phase fluorinating agents for use in reactive gas recycle of used nuclear fuel

    NASA Astrophysics Data System (ADS)

    Inabinett, Dillon

    Surrogate oxides of the Used Nuclear Fuel (UNF) matrix were fluorinated using alternate, solid-phase fluorinating agents XeF2 and NH4HF2 to form volatile and non-volatile compounds and demonstrate the possibility of a chemical and thermal separations. A matrix of experiments was conducted at the milligram quantity scale using a Shimadzu DTG-60 TG/DTA installed at SRNL (Savannah River National Laboratory) for testing of all non-radioactive samples and a Netzsch STA 409 TGA installed in the laboratory at USC (University of South Carolina) for testing of all radioactive samples. The fluorination and subsequent volatilization potentials were analyzed by mixing excess fluorinating agent with a surrogate oxide at roughly a 2:1 ratio and then heated to elevated temperatures for analysis. Thermogravimetric and differential thermal analysis allowed for reaction pathways to be analyzed and suggest windows both thermally and chemically for separations of these various components. The differences in thermophysical properties of these products can be utilized as a starting point to effectively separate, isolate, and collect product streams with different product composition for further processing. The study of these chemistries could be incorporated into advanced separations methods to provide another possible solution for the long-term sustainability of nuclear power as the issue of reuse and disposal of commercial fuel continues to grow.

  6. ENVIRONMENTAL REACTIVITY OF SOLID STATE HYDRIDE MATERIALS

    SciTech Connect

    Gray, J; Donald Anton, D

    2009-04-23

    In searching for high gravimetric and volumetric density hydrogen storage systems, it is inevitable that higher energy density materials will be used. In order to make safe and commercially acceptable condensed phase hydrogen storage systems, it is important to understand quantitatively the risks involved in using and handling these materials and to develop appropriate mitigation strategies to handle potential material exposure events. A crucial aspect of the development of risk identification and mitigation strategies is the development of rigorous environmental reactivity testing standards and procedures. This will allow for the identification of potential risks and implementation of risk mitigation strategies. Modified testing procedures for shipping air and/or water sensitive materials, as codified by the United Nations, have been used to evaluate two potential hydrogen storage materials, 2LiBH{sub 4} {center_dot} MgH{sub 2} and NH{sub 3}BH{sub 3}. The modified U.N. procedures include identification of self-reactive substances, pyrophoric substances, and gas-emitting substances with water contact. The results of these tests for air and water contact sensitivity will be compared to the pure material components where appropriate (e.g. LiBH{sub 4} and MgH{sub 2}). The water contact tests are divided into two scenarios dependent on the hydride to water mole ratio and heat transport characteristics. Air contact tests were run to determine whether a substance will spontaneously react with air in a packed or dispersed form. In the case of the 2LiBH{sub 4} {center_dot} MgH{sub 2} material, the results from the hydride mixture compared to the pure materials results showed the MgH{sub 2} to be the least reactive component and LiBH{sub 4} the more reactive. The combined 2LiBH{sub 4} {center_dot} MgH{sub 2} resulted in a material having environmental reactivity between these two materials. Relative to 2LiBH{sub 4} {center_dot} MgH{sub 2}, the chemical hydride NH{sub 3}BH

  7. Mechanistic Reactive Burn Modeling of Solid Explosives

    SciTech Connect

    Y.Horie; Y.Hamate; D.Greening

    2003-04-01

    This report describes a computational framework for reactive burn modeling of solid explosives and the development of a test case where physical mechanisms represent RDX or RDX-based materials. The report is a sequel to LA-13794-MS, ''A Unifying Framework for Hot Spots and the Ignition of Energetic Materials,'' where we proposed a new approach to the building of a general purpose model that captures the essential features of the three primary origins of hot-spot formation: void collapse, shear banding, friction. The purpose of the present report is to describe the continuing task of coupling the unifying hot-spot model to hydrodynamic calculations to develop a mechanistic reactive burn model. The key components of the coupling include energy localization, the growth of hot spots, overall hot-spot behavior, and a phase-averaged mixture equation of state (EOS) in a Mie-Grueneisen form. The nucleation and growth of locally heated regions is modeled by a phenomenological treatment as well as a statistical model based on an exponential size distribution. The Mie-Grueneisen form of the EOS is one of many possible choices and is not a critical selection for implementing the model. In this report, model calculations are limited to proof-of-concept illustrations for shock loading. Results include (1) shock ignition and growth-to-detonation, (2) double shock ignition, and (3) quenching and reignition. A comparative study of Pop-plots is discussed based on the statistical model.

  8. Method For Reactivating Solid Catalysts Used For Alklation Reactions

    DOEpatents

    Ginosar, Daniel M.; Thompson, David N.; Coates, Kyle; Zalewski, David J.; Fox, Robert V.

    2005-05-03

    A method for reactivating a solid alkylation catalyst is provided which can be performed within a reactor that contains the alkylation catalyst or outside the reactor. Effective catalyst reactivation is achieved whether the catalyst is completely deactivated or partially deactivated. A fluid reactivating agent is employed to dissolve catalyst fouling agents and also to react with such agents and carry away the reaction products. The deactivated catalyst is contacted with the fluid reactivating agent under pressure and temperature conditions such that the fluid reactivating agent is dense enough to effectively dissolve the fouling agents and any reaction products of the fouling agents and the reactivating agent. Useful pressures and temperatures for reactivation include near-critical, critical, and supercritical pressures and temperatures for the reactivating agent. The fluid reactivating agent can include, for example, a branched paraffin containing at least one tertiary carbon atom, or a compound that can be isomerized to a molecule containing at least one tertiary carbon atom.

  9. Method for reactivating solid catalysts used in alkylation reactions

    DOEpatents

    Ginosar, Daniel M.; Thompson, David N.; Coates, Kyle; Zalewski, David J.; Fox, Robert V.

    2003-06-17

    A method for reactivating a solid alkylation catalyst is provided which can be performed within a reactor that contains the alkylation catalyst or outside the reactor. Effective catalyst reactivation is achieved whether the catalyst is completely deactivated or partially deactivated. A fluid reactivating agent is employed to dissolve catalyst fouling agents and also to react with such agents and carry away the reaction products. The deactivated catalyst is contacted with the fluid reactivating agent under pressure and temperature conditions such that the fluid reactivating agent is dense enough to effectively dissolve the fouling agents and any reaction products of the fouling agents and the reactivating agent. Useful pressures and temperatures for reactivation include near-critical, critical, and supercritical pressures and temperatures for the reactivating agent. The fluid reactivating agent can include, for example, a branched paraffin containing at least one tertiary carbon atom, or a compound that can be isomerized to a molecule containing at least one tertiary carbon atom.

  10. Solids flow mapping in gas-solid risers

    NASA Astrophysics Data System (ADS)

    Bhusarapu, Satish Babu

    Gas-solid risers are extensively used in many industrial processes for gas-solid reactions (e.g. coal combustion and gasification) and for solid catalyzed gas phase reactions (e.g. fluid catalytic cracking, butane oxidation to maleic anhydride). Ab initio prediction of the complex multiphase fluid dynamics in risers is not yet possible, which makes reactor modeling difficult. In particular, quantification of solids flow and mixing is important. Almost all the experimental techniques used to characterize solids flow lead to appreciable errors in measured variables in large scale, high mass flux systems. In addition, none of the experimental techniques provide all the relevant data required to develop a satisfactory solids flow model. In this study, non-invasive Computer Automated Radioactive Particle Tracking (CARPT) is employed to visualize and quantify the solids dynamics and mixing in the gas-solid riser of a Circulating Fluidized Bed (CFB). A single radioactive tracer particle is monitored during its multiple visits to the riser and with an assumption of ergodicity, the following flow parameters are estimated: (a) Overall solids mass flux in the CFB loop. (b) Solids residence time distribution in the riser and down-comer. (c) Lagrangian and Eulerian solids velocity fields in a fully-developed section of the riser. This includes velocity fluctuations and components of the diffusivity tensor. The existing CARPT technique is extended to large scale systems. A new algorithm, based on a cross-correlation search, is developed for position rendition from CARPT data. Two dimensional solids holdup profiles are estimated using gamma-ray computed tomography. The image quality from the tomography data is improved by implementing an alternating minimization algorithm. This work establishes for the first time a reliable database for local solids dynamic quantities such as time-averaged velocities, Reynolds stresses, eddy diffusivities and turbulent kinetic energy. In addition

  11. Efficient and Safe Chemical Gas Generators with Nanocomposite Reactive Materials

    DTIC Science & Technology

    2015-11-30

    customized chemical gas generators based on novel energetic materials that will exhibit improved effectiveness, process stability, and fire safety...2015 Approved for Public Release; Distribution Unlimited Final Report: Efficient and Safe Chemical Gas Generators with Nanocomposite Reactive Materials...Building, Room 209 El Paso, TX 79968 -0587 12-Sep-2015 ABSTRACT Final Report: Efficient and Safe Chemical Gas Generators with Nanocomposite Reactive

  12. Time Dependent Studies of Reactive Shocks in the Gas Phase

    DTIC Science & Technology

    1978-11-16

    1 LEVEL NRL Memorandum Report 3W tO Time Dependent Studies of Reactive Shocks in the Gas Phase E.S. ORAN, ’T.R. YOUNG and J.P. BORIS Laboratory for...34-• TIME DEPENDENT STUDIES OF REACTIVE SHOCKS IN THE GAS PHASE I. Introduction This paper presents results obtained from a detailed numerical...chemical kinetics, reaction products, and intermediates produced in reactive gas mixtures ignited by the propagation of a shock front. The model is based

  13. Cerebrovascular reactivity mapping without gas challenges.

    PubMed

    Liu, Peiying; Li, Yang; Pinho, Marco; Park, Denise C; Welch, Babu G; Lu, Hanzhang

    2017-02-01

    Cerebrovascular reactivity (CVR), the ability of cerebral vessels to dilate or constrict, has been shown to provide valuable information in the diagnosis and treatment evaluation of patients with various cerebrovascular conditions. CVR mapping is typically performed using hypercapnic gas inhalation as a vasoactive challenge while collecting BOLD images, but the inherent need of gas inhalation and the associated apparatus setup present a practical obstacle in applying it in routine clinical use. Therefore, we aimed to develop a new method to map CVR using resting-state BOLD data without the need of gas inhalation. This approach exploits the natural variation in respiration and measures its influence on BOLD MRI signal. In this work, we first identified a surrogate of the arterial CO2 fluctuation during spontaneous breathing from the global BOLD signal. Second, we tested the feasibility and reproducibility of the proposed approach to use the above-mentioned surrogate as a regressor to estimate voxel-wise CVR. Third, we validated the "resting-state CVR map" with a conventional CVR map obtained with hypercapnic gas inhalation in healthy volunteers. Finally, we tested the utility of this new approach in detecting abnormal CVR in a group of patients with Moyamoya disease, and again validated the results using the conventional gas inhalation method. Our results showed that global BOLD signal fluctuation in the frequency range of 0.02-0.04Hz contains the most prominent contribution from natural variation in arterial CO2. The CVR map calculated using this signal as a regressor is reproducible across runs (ICC=0.91±0.06), and manifests a strong spatial correlation with results measured with a conventional hypercapnia-based method in healthy subjects (r=0.88, p<0.001). We also found that resting-state CVR was able to identify vasodilatory deficit in patients with steno-occlusive disease, the spatial pattern of which matches that obtained using the conventional gas method (r

  14. Xurography for microfluidics on a reactive solid.

    PubMed

    Neuville, Amélie; Renaud, Louis; Luu, Thi Thuy; Minde, Mona Wetrhus; Jettestuen, Espen; Vinningland, Jan Ludvig; Hiorth, Aksel; Dysthe, Dag Kristian

    2017-01-17

    In this paper, we propose a simple method to embed transparent reactive materials in a microfluidic cell, and to observe in situ the dissolution of the material. As an example, we show how to obtain the dissolution rate of a calcite window of optical quality, dissolved in water and hydrochloric acid (HCl). These fluids circulate at controlled flowrates in a channel which is obtained by xurography: double sided tape is cut out with a cutter plotter and placed between the calcite window and a non-reactive support. While the calcite window reacts in contact with the acid, its topography is measured in situ every 10 s using an interference microscope, with a pixel resolution of 4.9 μm and a vertical resolution of 50 nm. In order to avoid inlet influence on the reaction, a thin layer of photoresist is added on the calcite surface at the inlet and outlet. This layer is also used as a non reactive reference surface.

  15. End-Member Formulation of Solid Solutions and Reactive Transport

    SciTech Connect

    Lichtner, Peter C.

    2015-09-01

    A model for incorporating solid solutions into reactive transport equations is presented based on an end-member representation. Reactive transport equations are solved directly for the composition and bulk concentration of the solid solution. Reactions of a solid solution with an aqueous solution are formulated in terms of an overall stoichiometric reaction corresponding to a time-varying composition and exchange reactions, equivalent to reaction end-members. Reaction rates are treated kinetically using a transition state rate law for the overall reaction and a pseudo-kinetic rate law for exchange reactions. The composition of the solid solution at the onset of precipitation is assumed to correspond to the least soluble composition, equivalent to the composition at equilibrium. The stoichiometric saturation determines if the solid solution is super-saturated with respect to the aqueous solution. The method is implemented for a simple prototype batch reactor using Mathematica for a binary solid solution. Finally, the sensitivity of the results on the kinetic rate constant for a binary solid solution is investigated for reaction of an initially stoichiometric solid phase with an undersaturated aqueous solution.

  16. Enhanced electrodes for solid state gas sensors

    DOEpatents

    Garzon, Fernando H.; Brosha, Eric L.

    2001-01-01

    A solid state gas sensor generates an electrical potential between an equilibrium electrode and a second electrode indicative of a gas to be sensed. A solid electrolyte substrate has the second electrode mounted on a first portion of the electrolyte substrate and a composite equilibrium electrode including conterminous transition metal oxide and Pt components mounted on a second portion of the electrolyte substrate. The composite equilibrium electrode and the second electrode are electrically connected to generate an electrical potential indicative of the gas that is being sensed. In a particular embodiment of the present invention, the second electrode is a reference electrode that is exposed to a reference oxygen gas mixture so that the electrical potential is indicative of the oxygen in a gas stream.

  17. Solid fuel volatilization to produce synthesis gas

    DOEpatents

    Schmidt, Lanny D.; Dauenhauer, Paul J.; Degenstein, Nick J.; Dreyer, Brandon J.; Colby, Joshua L.

    2014-07-29

    A method comprising contacting a carbon and hydrogen-containing solid fuel and a metal-based catalyst in the presence of oxygen to produce hydrogen gas and carbon monoxide gas, wherein the contacting occurs at a temperature sufficiently high to prevent char formation in an amount capable of stopping production of the hydrogen gas and the carbon monoxide gas is provided. In one embodiment, the metal-based catalyst comprises a rhodium-cerium catalyst. Embodiments further include a system for producing syngas. The systems and methods described herein provide shorter residence time and high selectivity for hydrogen and carbon monoxide.

  18. APPARATUS FOR SHORT TIME MEASUREMENTS IN A FIXED-BED, GAS/SOLID REACTOR

    EPA Science Inventory

    An apparatus for exposure of a solid to reactive process gas is described which makes possible short time (≥ 0.3 to 15 s) exposures in a fixed-bed reactor. Operating conditions for differential reaction with respect to the gas concentration and rapid quench for arresting hi...

  19. Gas Phase Reactivity of Carboxylates with N-Hydroxysuccinimide Esters

    PubMed Central

    Peng, Zhou; McGee, William M.; Bu, Jiexun; Barefoot, Nathan Z.; McLuckey, Scott A.

    2015-01-01

    N-hydroxysuccinimide (NHS) esters have been used for gas phase conjugation reactions with peptides at nucleophilic sites, such as primary amines (N-terminus, ε-amine of lysine) or guanidines, by forming amide bonds through a nucleophilic attack on the carbonyl carbon. The carboxylate has recently been found to also be a reactive nucleophile capable of initiating a similar nucleophilic attack to form a labile anhydride bond. The fragile bond is easily cleaved, resulting in an oxygen transfer from the carboxylate-containing species to the reagent, nominally observed as a water transfer. This reactivity is shown for both peptides and non-peptidic species. Reagents isotopically labeled with O18 were used to confirm reactivity. This constitutes an example of distinct differences in reactivity of carboxylates between the gas-phase, where they are shown to be reactive, and the solution-phase, where they are not regarded as reactive with NHS esters. PMID:25338221

  20. Gas Phase Reactivity of Carboxylates with N-Hydroxysuccinimide Esters

    NASA Astrophysics Data System (ADS)

    Peng, Zhou; McGee, William M.; Bu, Jiexun; Barefoot, Nathan Z.; McLuckey, Scott A.

    2015-01-01

    N-hydroxysuccinimide (NHS) esters have been used for gas-phase conjugation reactions with peptides at nucleophilic sites, such as primary amines (N-terminus, ɛ-amine of lysine) or guanidines, by forming amide bonds through a nucleophilic attack on the carbonyl carbon. The carboxylate has recently been found to also be a reactive nucleophile capable of initiating a similar nucleophilic attack to form a labile anhydride bond. The fragile bond is easily cleaved, resulting in an oxygen transfer from the carboxylate-containing species to the reagent, nominally observed as a water transfer. This reactivity is shown for both peptides and non-peptidic species. Reagents isotopically labeled with O18 were used to confirm reactivity. This constitutes an example of distinct differences in reactivity of carboxylates between the gas phase, where they are shown to be reactive, and the solution phase, where they are not regarded as reactive with NHS esters.

  1. Amorphous Molecular Organic Solids for Gas Adsorption

    SciTech Connect

    Tian, Jian; Thallapally, Praveen K.; Dalgarno, Scott J.; McGrail, B. Peter; Atwood, Jerry L.

    2009-07-06

    We show that molecular organic compounds with large accessible internal cavities, as part of their rigid molecular structure, display exceptional ability for gas storage and separation in the amorphous solid state. This finding suggests for the first time that long-range molecular order is not a prerequisite for organic molecules to be engineered as porous materials

  2. Method for generating a highly reactive plasma for exhaust gas after treatment and enhanced catalyst reactivity

    SciTech Connect

    Whealton, John H.; Hanson, Gregory R.; Storey, John M.; Raridon, Richard J.; Armfield, Jeffrey S.; Bigelow, Timothy S.; Graves, Ronald L.

    2000-07-01

    This patent application describes a method and apparatus of exhaust gas remediation that enhance the reactivity of the material catalysts found within catalytic converters of cars, trucks, and power stations.

  3. Solid polymer battery electrolyte and reactive metal-water battery

    DOEpatents

    Harrup, Mason K.; Peterson, Eric S.; Stewart, Frederick F.

    2000-01-01

    In one implementation, a reactive metal-water battery includes an anode comprising a metal in atomic or alloy form selected from the group consisting of periodic table Group 1A metals, periodic table Group 2A metals and mixtures thereof. The battery includes a cathode comprising water. Such also includes a solid polymer electrolyte comprising a polyphosphazene comprising ligands bonded with a phosphazene polymer backbone. The ligands comprise an aromatic ring containing hydrophobic portion and a metal ion carrier portion. The metal ion carrier portion is bonded at one location with the polymer backbone and at another location with the aromatic ring containing hydrophobic portion. The invention also contemplates such solid polymer electrolytes use in reactive metal/water batteries, and in any other battery.

  4. Preliminary Results of Solid Gas Generator Micropropulsion

    NASA Technical Reports Server (NTRS)

    deGroot, Wilhelmus A.; Reed, Brian D.; Brenizer, Marshall

    1999-01-01

    A decomposing solid thruster concept, which creates a more benign thermal and chemical environment than solid propellant combustion, while maintaining, performance similar to solid combustion, is described. A Micro-Electro-Mechanical (MEMS) thruster concept with diode laser and fiber-optic initiation is proposed, and thruster components fabricated with MEMS technology are presented. A high nitrogen content solid gas generator compound is evaluated and tested in a conventional axisymmetric thrust chamber with nozzle throat area ratio of 100. Results show incomplete decomposition of this compound in both low pressure (1 kPa) and high pressure (1 MPa) environments, with decomposition of up to 80% of the original mass. Chamber pressures of 1.1 MPa were obtained, with maximum calculated thrust of approximately 2.7 N. Resistively heated wires and resistively heated walls were used to initiate decomposition. Initiation tests using available lasers were unsuccessful, but infrared spectra of the compound show that the laser initiation tests used inappropriate wavelengths for optimal propellant absorption. Optimal wavelengths for laser ignition were identified. Data presented are from tests currently in progress. Alternative solid gas generator compounds are being evaluated for future tests.

  5. Method for improved gas-solids separation

    DOEpatents

    Kusik, Charles L.; He, Bo X.

    1990-01-01

    Methods are disclosed for the removal of particulate solids from a gas stream at high separation efficiency, including the removal of submicron size particles. The apparatus includes a cyclone separator type of device which contains an axially mounted perforated cylindrical hollow rotor. The rotor is rotated at high velocity in the same direction as the flow of an input particle-laden gas stream to thereby cause enhanced separation of particulate matter from the gas stream in the cylindrical annular space between the rotor and the sidewall of the cyclone vessel. Substantially particle-free gas passes through the perforated surface of the spinning rotor and into the hollow rotor, from when it is discharged out of the top of the apparatus. Separated particulates are removed from the bottom of the vessel.

  6. Method for improved gas-solids separation

    DOEpatents

    Kusik, C.L.; He, B.X.

    1990-11-13

    Methods are disclosed for the removal of particulate solids from a gas stream at high separation efficiency, including the removal of submicron size particles. The apparatus includes a cyclone separator type of device which contains an axially mounted perforated cylindrical hollow rotor. The rotor is rotated at high velocity in the same direction as the flow of an input particle-laden gas stream to thereby cause enhanced separation of particulate matter from the gas stream in the cylindrical annular space between the rotor and the sidewall of the cyclone vessel. Substantially particle-free gas passes through the perforated surface of the spinning rotor and into the hollow rotor, from where it is discharged out of the top of the apparatus. Separated particulates are removed from the bottom of the vessel. 4 figs.

  7. Pyrolysis process for producing condensed stabilized hydrocarbons utilizing a beneficially reactive gas

    DOEpatents

    Durai-Swamy, Kandaswamy

    1982-01-01

    In a process for recovery of values contained in solid carbonaceous material, the solid carbonaceous material is comminuted and then subjected to pyrolysis, in the presence of a carbon containing solid particulate source of heat and a beneficially reactive transport gas in a transport flash pyrolysis reactor, to form a pyrolysis product stream. The pyrolysis product stream contains a gaseous mixture and particulate solids. The solids are separated from the gaseous mixture to form a substantially solids-free gaseous stream which comprises volatilized hydrocarbon free radicals newly formed by pyrolysis. Preferably the solid particulate source of heat is formed by oxidizing part of the separated particulate solids. The beneficially reactive transport gas inhibits the reactivity of the char product and the carbon-containing solid particulate source of heat. Condensed stabilized hydrocarbons are obtained by quenching the gaseous mixture stream with a quench fluid which contains a capping agent for stabilizing and terminating newly formed volatilized hydrocarbon free radicals. The capping agent is partially depleted of hydrogen by the stabilization and termination reaction. Hydrocarbons of four or more carbon atoms in the gaseous mixture stream are condensed. A liquid stream containing the stabilized liquid product is then treated or separated into various fractions. A liquid containing the hydrogen depleted capping agent is hydrogenated to form a regenerated capping agent. At least a portion of the regenerated capping agent is recycled to the quench zone as the quench fluid. In another embodiment capping agent is produced by the process, separated from the liquid product mixture, and recycled.

  8. Gas atomization synthesis of refractory or intermetallic compounds and supersaturated solid solutions

    DOEpatents

    Anderson, Iver E.; Lograsso, Barbara K.; Ellis, Timothy W.

    1994-01-01

    A metallic melt is atomized using a high pressure atomizing gas wherein the temperature of the melt and the composition of the atomizing gas are selected such that the gas and melt react in the atomization spray zone to form a refractory or intermetallic compound in the as-atomized powder particles. A metallic melt is also atomized using a high pressure atomizing gas mixture gas wherein the temperature of the melt and the ratio of a reactive gas to a carrier gas are selected to form powder particles comprising a supersaturated solid solution of the atomic species of the reactive gas in the particles. The powder particles are then heat treated to precipitate dispersoids in-situ therein to form a dispersion strengthened material.

  9. Gas atomization synthesis of refractory or intermetallic compounds and supersaturated solid solutions

    DOEpatents

    Anderson, I.E.; Lograsso, B.K.; Ellis, T.W.

    1994-11-29

    A metallic melt is atomized using a high pressure atomizing gas wherein the temperature of the melt and the composition of the atomizing gas are selected such that the gas and melt react in the atomization spray zone to form a refractory or intermetallic compound in the as-atomized powder particles. A metallic melt is also atomized using a high pressure atomizing gas mixture gas wherein the temperature of the melt and the ratio of a reactive gas to a carrier gas are selected to form powder particles comprising a supersaturated solid solution of the atomic species of the reactive gas in the particles. The powder particles are then heat treated to precipitate dispersoids in-situ therein to form a dispersion strengthened material. 9 figures.

  10. Solid-state power supply for gas lasers

    NASA Astrophysics Data System (ADS)

    Bertolini, A.; Beverini, N.; Carelli, G.; Francesconi, M.; Nannizzi, M.; Strumia, F.; Ioli, N.; Moretti, A.

    2004-08-01

    A novel pulsed power supply for gas lasers is presented. The device uses only solid state components and is based on a capacitor bank discharge. Fast switching of the discharge is triggered by an insulated gate bipolar transistor. The terminal section of the power supply is a transformer designed to match the reactive capacitance of a gas discharge. Strokes up to 30 kV and 30 mA are achieved across the secondary windings of this transformer. The power supply delivers high voltage pulses with a duration between 0.5 and 50 μs and a repetition rate up to some kHz. The power supply has been tested on a longitudinal discharge quasi-cw regime CO2 laser. Laser pulses were generated with a duration down to the microseconds region, a peak power exceeding some kilowatts, and a repetition rate ranging from 200 Hz to a few kHz.

  11. Microencapsulation of liquid and solid substances by reactive polymers.

    PubMed

    Shevchuk, O; Serdiuk, V; Bukartyk, N; Moncibovich, R; Tokarev, V

    2014-01-01

    This study is devoted to the development of techniques for the formation of polymeric microcapsules (MC) with either liquid or solid core and with the polymer shell containing diverse functional groups on the basis of new reactive functional copolymers (FC). Two approaches to the formation of MC containing FC shell that included the stages of "oil-in-water" or "water-in-oil" dispersion preparation followed by slow extraction of solvents from dispersed phase by dispersive media were examined. FC with the same structure was successfully applied for both "oil-in-water" and "water-in-oil" systems. Spherical MC with the liquid hydrocarbon core demonstrated essential increase in their volume after heating at the temperature exceeding a boiling point of hydrocarbon encapsulated. Presence of reactive groups in the MC shell opens up new opportunity for further tuning the MC properties via their interaction with proper compounds, particularly via graft-polymerisation of diverse vinyl monomers initiated from the MC surface.

  12. Nanocrystalline films for gas-reactive applications

    DOEpatents

    Eastman, Jeffrey A.; Thompson, Loren J.

    2004-02-17

    A gas sensor for detection of oxidizing and reducing gases, including O.sub.2, CO.sub.2, CO, and H.sub.2, monitors the partial pressure of a gas to be detected by measuring the temperature rise of an oxide-thin-film-coated metallic line in response to an applied electrical current. For a fixed input power, the temperature rise of the metallic line is inversely proportional to the thermal conductivity of the oxide coating. The oxide coating contains multi-valent cation species that change their valence, and hence the oxygen stoichiometry of the coating, in response to changes in the partial pressure of the detected gas. Since the thermal conductivity of the coating is dependent on its oxygen stoichiometry, the temperature rise of the metallic line depends on the partial pressure of the detected gas. Nanocrystalline (<100 nm grain size) oxide coatings yield faster sensor response times than conventional larger-grained coatings due to faster oxygen diffusion along grain boundaries rather than through grain interiors.

  13. Pore structure and reactivity changes in hot coal gas desulfurization sorbents

    SciTech Connect

    Sotirchos, S.V.

    1991-05-01

    The primary objective of the project was the investigation of the pore structure and reactivity changes occurring in metal/metal oxide sorbents used for desulfurization of hot coal gas during sulfidation and regeneration, with particular emphasis placed on the effects of these changes on the sorptive capacity and efficiency of the sorbents. Commercially available zinc oxide sorbents were used as model solids in our experimental investigation of the sulfidation and regeneration processes.

  14. Worldwide gas processing enjoys solid 1991

    SciTech Connect

    True, W.R. )

    1992-07-20

    This paper reports that worldwide gas-processing operations exhibited growth across the board last year as demand for NGLs, primarily as petrochemical feedstock and gasoline blendstock, pushed operators to increases in capacities, throughput, and production. Most evident were the gains in the U.S., Canada, and Latin America. As has been true for several years, the U.S. continued to lead the rest of the world in gas-processing capacity and NGL production. Outside the U.S., the rest of the world continued to grow, although not as markedly. Canada and the countries of Latin America led others with solid gains in capacities, gas processed, and NGLs produced. These developments are reflected in the exclusive, plant-by-plant, world-wide gas-processing survey along with an international survey of petroleum-derived sulfur recovery. Last year, one major plant in the Caribbean came on stream adding 650 MMcfd of capacity and producing almost 10,000 b/d of product. By the time the next year's report, a major Canadian sour-gas plant near Calgary will be running.

  15. Solid surface mapping by inverse gas chromatography.

    PubMed

    Gutiérrez, M C; Osuna, S; Baráibar, I

    2005-09-16

    Inverse gas chromatography (IGC) at infinite dilution, is a technique for characterising solid surfaces. Current practice is the injection of n-alkane homologous series to obtain the free energy of adsorption of the CH2 group, from which the London component of the solid surface free energy, gamma(d)s, is calculated. A value around 40 mJ/m2 is obtained for poly(ethylene), and 30 mJ/m2 for a clean glass fibre, while the potential surface interactivity of a glass fibre is far greater than that of poly(ethylene). A specific component of the surface, in mJ/m2, should be calculated in order to obtain significant parameters. As applied up to date, when calculating the specific component of the surface energy, the fact that W(sp)a energy values are in a totally different scale than AN or DN values is a major drawback. Consequently, Ka and Kb values obtained are in arbitrary energy units, different from those of the London component measured by injecting the n-alkane series. This paper proposes a method to obtain Ka and Kb values of the surface in the same energetic scale than the London component. The method enables us to correct the traditional London component of a solid, obtaining a new value, where the amount of WaCH2 accounting for Debye interactions with polar sites, is excluded. As a result, an approach to surface mapping is performed in several different substrate materials. We show results obtained on different solid surfaces: poly(ethylene), clean glass fibre, glass beads, chemically modified glass beads and carbon fibre.

  16. Compact solid source of hydrogen gas

    DOEpatents

    Kravitz, Stanley H.; Hecht, Andrew M.; Sylwester, Alan P.; Bell, Nelson S.

    2004-06-08

    A compact solid source of hydrogen gas, where the gas is generated by contacting water with micro-disperse particles of sodium borohydride in the presence of a catalyst, such as cobalt or ruthenium. The micro-disperse particles can have a substantially uniform diameter of 1-10 microns, and preferably about 3-5 microns. Ruthenium or cobalt catalytic nanoparticles can be incorporated in the micro-disperse particles of sodium borohydride, which allows a rapid and complete reaction to occur without the problems associated with caking and scaling of the surface by the reactant product sodium metaborate. A closed loop water management system can be used to recycle wastewater from a PEM fuel cell to supply water for reacting with the micro-disperse particles of sodium borohydride in a compact hydrogen gas generator. Capillary forces can wick water from a water reservoir into a packed bed of micro-disperse fuel particles, eliminating the need for using an active pump.

  17. [Reactivity of the limestone in wet flue gas desulfurization].

    PubMed

    Zhu, Tian-le; Li, Yao; Ling, Xuan; Liu, Hong-ju; Xu, Feng-gang; Liu, Han-qiang

    2005-11-01

    On the basis of the analysis of chemical components of the natural limestones from different deposits in China, the pore structures of the typical limestones, with the different CaCO3 content, were examined. The reactivity of the limestones was investigated by sulfuric acid titration and gas-liquid absorption methods. The research results showed that the specific surface area of the natural limestones studied in this work was about 1.8 m2/g. It was seen that the pH of the limestone slurry rapidly decreased and then back up when the sulfuric acid was added. The higher the CaCO3 content was, or the smaller the particle size was, the larger the pH back-up rate was, and similarly the faster the SO2 concentration of the reactor outlet increased. The Reactivity of the limestone obtained by the sulfuric acid titration had the same features as that obtained by the gas liquid absorption. Compared with the specific surface area, the CaCO3 content had more effect on the reactivity of the limestones. The particle size of the limestones had a significant effect on the reactivity when the particle size was relatively large, that is less than 300-360 mesh, vice versa.

  18. Visualizing Gas Adsorption on Porous Solids: Four Simple, Effective Demonstrations

    ERIC Educational Resources Information Center

    Cheung, Ocean

    2014-01-01

    Gas adsorption on porous solids is a topic that is often discussed in an undergraduate chemistry or chemical engineering course. The idea of porosity and gas adsorption on a porous solid is usually discussed with adsorption isotherms recorded using commercially available equipment. This discussion can be rather abstract and can be difficult for…

  19. Chaos suppression in gas-solid fluidization.

    PubMed

    Pence, Deborah V.; Beasley, Donald E.

    1998-06-01

    Fluidization in granular materials occurs primarily as a result of a dynamic balance between gravitational forces and forces resulting from the flow of a fluid through a bed of discrete particles. For systems where the fluidizing medium and the particles have significantly different densities, density wave instabilities create local pockets of very high void fraction termed bubbles. The fluidization regime is termed the bubbling regime. Such a system is appropriately termed a self-excited nonlinear system. The present study examines chaos suppression resulting from an opposing oscillatory flow in gas-solid fluidization. Time series data representing local, instantaneous pressure were acquired at the surface of a horizontal cylinder submerged in a bubbling fluidized bed. The particles had a weight mean diameter of 345 &mgr;m and a narrow size distribution. The state of fluidization corresponded to the bubbling regime and total air flow rates employed in the present study ranged from 10% to 40% greater than that required for minimum fluidization. The behavior of time-varying local pressure in fluidized beds in the absence of a secondary flow is consistent with deterministic chaos. Kolmogorov entropy estimates from local, instantaneous pressure suggest that the degree of chaotic behavior can be substantially suppressed by the presence of an opposing, oscillatory secondary flow. Pressure signals clearly show a "phase-locking" phenomenon coincident with the imposed frequency. In the present study, the greatest degree of suppression occurred for operating conditions with low primary and secondary flow rates, and a secondary flow oscillation frequency of 15 Hz. (c) 1998 American Institute of Physics.

  20. Method for generating a highly reactive plasma for exhaust gas aftertreatment and enhanced catalyst reactivity

    DOEpatents

    Whealton, John H.; Hanson, Gregory R.; Storey, John M.; Raridon, Richard J.; Armfield, Jeffrey S.; Bigelow, Timothy S.; Graves, Ronald L.

    2002-01-01

    A method for non-thermal plasma aftertreatment of exhaust gases the method comprising the steps of providing short risetime, high frequency, high power bursts of low-duty factor microwaves sufficient to generate a plasma discharge and passing a gas to be treated through the discharge so as to cause dissociative reduction of the exhaust gases and enhanced catalyst reactivity through application of the pulsed microwave fields directly to the catalyst material sufficient to cause a polarizability catastrophe and enhanced heating of the metal crystallite particles of the catalyst, and in the presence or absence of the plasma. The invention also includes a reactor for aftertreatment of exhaust gases.

  1. Etching radical controlled gas chopped deep reactive ion etching

    DOEpatents

    Olynick, Deidre; Rangelow, Ivo; Chao, Weilun

    2013-10-01

    A method for silicon micromachining techniques based on high aspect ratio reactive ion etching with gas chopping has been developed capable of producing essentially scallop-free, smooth, sidewall surfaces. The method uses precisely controlled, alternated (or chopped) gas flow of the etching and deposition gas precursors to produce a controllable sidewall passivation capable of high anisotropy. The dynamic control of sidewall passivation is achieved by carefully controlling fluorine radical presence with moderator gasses, such as CH.sub.4 and controlling the passivation rate and stoichiometry using a CF.sub.2 source. In this manner, sidewall polymer deposition thicknesses are very well controlled, reducing sidewall ripples to very small levels. By combining inductively coupled plasmas with controlled fluorocarbon chemistry, good control of vertical structures with very low sidewall roughness may be produced. Results show silicon features with an aspect ratio of 20:1 for 10 nm features with applicability to nano-applications in the sub-50 nm regime. By comparison, previous traditional gas chopping techniques have produced rippled or scalloped sidewalls in a range of 50 to 100 nm roughness.

  2. Testing and evaluation of solid lubricants for gas bearings

    NASA Technical Reports Server (NTRS)

    Albrecht, P. R.; Fischer, W. H.

    1974-01-01

    The testing and results of testing solid film lubricants for gas lubricated bearing applications are reported. The tests simulated operational hazards of tilting pad gas bearings. The presence of a low coefficient of friction and the endurance of the solid film lubricant were the criteria for judging superior performance. All solid lubricants tested were applied to a plasma sprayed chrome oxide surface. Molybdenum disulfide and graphite fluoride were the solid lubricants tested; other test parameters included the method of application of the solid lubricant and the surface finish of the plasma sprayed coating. In general, the application of a solid film lubricant was found to significantly improve the coefficient of friction of the rubbing surfaces.

  3. Heat transfer across the interface between nanoscale solids and gas.

    PubMed

    Cheng, Chun; Fan, Wen; Cao, Jinbo; Ryu, Sang-Gil; Ji, Jie; Grigoropoulos, Costas P; Wu, Junqiao

    2011-12-27

    When solid materials and devices scale down in size, heat transfer from the active region to the gas environment becomes increasingly significant. We show that the heat transfer coefficient across the solid-gas interface behaves very differently when the size of the solid is reduced to the nanoscale, such as that of a single nanowire. Unlike for macroscopic solids, the coefficient is strongly pressure dependent above ∼10 Torr, and at lower pressures it is much higher than predictions of the kinetic gas theory. The heat transfer coefficient was measured between a single, free-standing VO(2) nanowire and surrounding air using laser thermography, where the temperature distribution along the VO(2) nanowire was determined by imaging its domain structure of metal-insulator phase transition. The one-dimensional domain structure along the nanowire results from the balance between heat generation by the focused laser and heat dissipation to the substrate as well as to the surrounding gas, and thus serves as a nanoscale power-meter and thermometer. We quantified the heat loss rate across the nanowire-air interface, and found that it dominates over all other heat dissipation channels for small-diameter nanowires near ambient pressure. As the heat transfer across the solid-gas interface is nearly independent of the chemical identity of the solid, the results reveal a general scaling relationship for gaseous heat dissipation from nanostructures of all solid materials, which is applicable to nanoscale electronic and thermal devices exposed to gaseous environments.

  4. Dynamic solid phase microextraction sampling for reactive terpenes in the presence of ozone.

    PubMed

    Shu, Shi; Morrison, Glenn

    2010-10-15

    Dynamic gas sampling using solid phase microextraction (SPME) was evaluated for recovery of reactive terpenes and terpenoids in the presence of ozone. For limonene, α-terpineol and dihydromyrcenol in the 20-60 ppb range, this method achieves >80% recovery for ozone mixing ratios up to 100 ppb. Both the experimental results and a model analysis indicate that higher ozone concentrations and longer sampling times result in lower percent recovery. Typically greater than 90% recovery and ppb level method detection limits were achieved with a 5 min sample time. Increasing the flow rate from 100 to 400 sccm flow (5-20 cms(-1)) through the active sampler did not significantly affect sensitivity or recovery in most cases, probably due to negligible mass-transfer improvements. The recovery for each compound improves when sampling from a mixture of different species than that from a single compound sample. This may be due to competition for ozone amongst adsorbed species. Dynamic SPME sampling can improve detection and quantification of terpenes in reactive environments, especially for low vapor pressure (<5 mm Hg at 25°C) compounds that can be adsorbed to ozone scrubbers used in other methods.

  5. Pore structure and reactivity changes in hot coal gas desulfurization sorbents. Final report, September 1987--January 1991

    SciTech Connect

    Sotirchos, S.V.

    1991-05-01

    The primary objective of the project was the investigation of the pore structure and reactivity changes occurring in metal/metal oxide sorbents used for desulfurization of hot coal gas during sulfidation and regeneration, with particular emphasis placed on the effects of these changes on the sorptive capacity and efficiency of the sorbents. Commercially available zinc oxide sorbents were used as model solids in our experimental investigation of the sulfidation and regeneration processes.

  6. Disposal pathway for tritiated reactive metals and tritiated hydrogen gas

    SciTech Connect

    Antoniazzi, A. B.; Morton, C. S.

    2008-07-15

    Kinectrics and its predecessor company Ontario Hydro Research Div. (a division of Ontario Hydro) had a fully operational tritium laboratory on site since the early 1980's. During those years numerous projects and experiments were undertaken using hydrogen and tritium for the most part. Metals with an affinity for hydrogen are commonly employed as scavengers of hydrogenic gases from process streams or as hydrogen storage mediums. The two most common of these metals used were depleted uranium and a zirconium-iron alloy (SAES St198). The break-up of Ontario Hydro through deregulation activities resulted in the building of a new, smaller, tritium laboratory and the decommissioning of the original tritium laboratory. Decommissioning activities resulted in the need to safely dispose of these reactive metals. Disposal of these metals is not straight forward. For safe, long term, disposal it has been decided to oxidize the metals in a controlled fashion. The oxidized beds, containing the metals, will be sent to a radioactive waste site for long term storage. Options for disposal of tritiated hydrogen gas are presented and discussed. This paper provides a disposal pathway for tritiated reactive metals and hydrogen thereby closing the loop in tritium handling. (authors)

  7. Solid-State-Trapped Reactive Ammonium Carbamate Self-Derivative Salts of Prolinamide

    PubMed Central

    Tilborg, Anaëlle; Lanners, Steve; Norberg, Bernadette; Wouters, Johan

    2013-01-01

    Single crystals for two polymorphs of the ammonium carbamate self-derivative salt of prolinamide have been successfully obtained and characterized. Decarbonation of the carbamate salts was monitored by calorimetry, confirming stabilization of the reactive carbonated adducts in the solid state. Sublimation of the salts afforded crystals of prolinamide, leading to the first crystal structure of this otherwise common molecule. Reactivity of the ammonium carbamate self-derivative salt is further illustrated by the observation of a series of derived products, including dehydroprolinamide, a methylene-bridged prolinamide, and a bicyclic derivative. Crystal structures of these products display distinct amidic and/or non-amidic hydrogen bonding. This study emphasizes the reactivity of carbonated amines stabilized in the solid and opens perspectives for a systematic study of (solid-state) reactions involving these trapped reactive species. PMID:24551566

  8. Frustrated Organic Solids Display Unexpected Gas Sorption

    SciTech Connect

    Thallapally, Praveen K.; Dalgarno, Scott J.; Atwood, Jerry L.

    2006-11-27

    Calixarene based organic solid can hold guests such as toluene and other organic molecules we have discovered a new type of material which believe involves a frustration of the solvate lattice as it moves toward the thermodynamically stable desolvated state. The intermediated phase with partial solvent content unexpectedly sorbs gases such as carbon dioxide and highly explosive acetylene deep inside the crystal lattice.

  9. CO2 sequestration using waste concrete and anorthosite tailings by direct mineral carbonation in gas-solid-liquid and gas-solid routes.

    PubMed

    Ben Ghacham, Alia; Cecchi, Emmanuelle; Pasquier, Louis-César; Blais, Jean-François; Mercier, Guy

    2015-11-01

    Mineral carbonation (MC) represents a promising alternative for sequestering CO2. In this work, the CO2 sequestration capacity of the available calcium-bearing materials waste concrete and anorthosite tailings is assessed in gas-solid-liquid and gas-solid routes using 18.2% flue CO2 gas. The objective is to screen for a better potential residue and phase route and as the ultimate purpose to develop a cost-effective process. The results indicate the possibility of removing 66% from inlet CO2 using waste concrete for the aqueous route. However, the results that were obtained with the carbonation of anorthosite were less significant, with 34% as the maximal percentage of CO2 removal. The difference in terms of reactivity could be explained by the accessibility to calcium. In fact, anorthosite presents a framework structure wherein the calcium is trapped, which could slow the calcium dissolution into the aqueous phase compared to the concrete sample, where calcium can more easily leach. In the other part of the study concerning gas-solid carbonation, the results of CO2 removal did not exceed 15%, which is not economically interesting for scaling up the process. The results obtained with waste concrete samples in aqueous phase are interesting. In fact, 34.6% of the introduced CO2 is converted into carbonate after 15 min of contact with the gas without chemical additives and at a relatively low gas pressure. Research on the optimization of the aqueous process using waste concrete should be performed to enhance the reaction rate and to develop a cost-effective process.

  10. On the Superficial Gas Velocity in Deep Gas-Solid Fluidized Beds

    SciTech Connect

    Li, Tingwen; Grace, John; Shadle, Lawrence; Guenther, Chris

    2011-11-15

    The superficial gas velocity is one of the key parameters used to determine the flow hydrodynamics in gas–solids fluidized beds. However, the superficial velocity varies with height in practice, and there is no consistent basis for its specification. Different approaches to determine the superficial gas velocity in a deep gas–solids system are shown to cause difficulties in developing models and in comparing predictions with experimental results. In addition, the reference conditions for superficial gas velocity are important in modeling of deep gas–solids systems where there is a considerable pressure drop.

  11. A Generalized Kinetic Model for Heterogeneous Gas-Solid Reactions

    SciTech Connect

    Xu, Zhijie; Sun, Xin; Khaleel, Mohammad A.

    2012-08-15

    We present a generalized kinetic model for gas-solid heterogeneous reactions taking place at the interface between two phases. The model studies the reaction kinetics by taking into account the reactions at the interface, as well as the transport process within the product layer. The standard unreacted shrinking core model relies on the assumption of quasi-static diffusion that results in a steady-state concentration profile of gas reactant in the product layer. By relaxing this assumption and resolving the entire problem, general solutions can be obtained for reaction kinetics, including the reaction front velocity and the conversion (volume fraction of reacted solid). The unreacted shrinking core model is shown to be accurate and in agreement with the generalized model for slow reaction (or fast diffusion), low concentration of gas reactant, and small solid size. Otherwise, a generalized kinetic model should be used.

  12. Applications for Solid Propellant Cool Gas Generator Technology

    NASA Astrophysics Data System (ADS)

    van der List, M.; van Vliet, L. D.; Sanders, H. M.; Put, P. A. G.; Elst, J. W. E. C.

    2004-10-01

    In 2002 and 2003, Bradford Engineering B.V. conducted, in corporation with the Dutch research institute TNO Prins Maurits Laboratory (PML) a SME study for ESA-ESTEC for the identification of spaceflight applications and on-ground demonstration of Solid Propellant Cool Gas Generator (SPCGG) technology. This innovative technology has been developed by TNO-PML while Bradford Engineering also brought in its experience in spaceflight hardware development and manufacturing. The Solid Propellant Cool Gas Generator (SPCGG) technology allows for pure gas generation at ambient temperatures, as opposed to conventional solid propellant gas generators. This makes the SPCGG technology interesting for a wide range of terrestrial spaceflight applications. During the first part of the study, a variety of potential applications have been identified and three applications were selected for a more detailed quantitative study. In the third phase a ground demonstration was performed successfully for a cold gas propulsion system application. During the actual demonstration test, 10 cool gas generators were mounted and all operated successfully in sequence, demonstrating good repeatability of the produced amount of gas and pressure.

  13. SOLID GAS SUSPENSION NUCLEAR FUEL ASSEMBLY

    DOEpatents

    Schluderberg, D.C.; Ryon, J.W.

    1962-05-01

    A fuel assembly is designed for use in a gas-suspension cooled nuclear fuel reactor. The coolant fluid is an inert gas such as nitrogen or helium with particles such as carbon suspended therein. The fuel assembly is contained within an elongated pressure vessel extending down into the reactor. The fuel portion is at the lower end of the vessel and is constructed of cylindrical segments through which the coolant passes. Turbulence promotors within the passageways maintain the particles in agitation to increase its ability to transfer heat away from the outer walls. Shielding sections and alternating passageways above the fueled portion limit the escape of radiation out of the top of the vessel. (AEC)

  14. Solid fuel combustion system for gas turbine engine

    DOEpatents

    Wilkes, Colin; Mongia, Hukam C.

    1993-01-01

    A solid fuel, pressurized fluidized bed combustion system for a gas turbine engine includes a carbonizer outside of the engine for gasifying coal to a low Btu fuel gas in a first fraction of compressor discharge, a pressurized fluidized bed outside of the engine for combusting the char residue from the carbonizer in a second fraction of compressor discharge to produce low temperature vitiated air, and a fuel-rich, fuel-lean staged topping combustor inside the engine in a compressed air plenum thereof. Diversion of less than 100% of compressor discharge outside the engine minimizes the expense of fabricating and maintaining conduits for transferring high pressure and high temperature gas and incorporation of the topping combustor in the compressed air plenum of the engine minimizes the expense of modifying otherwise conventional gas turbine engines for solid fuel, pressurized fluidized bed combustion.

  15. Natural synthesis of bioactive greigite by solid-gas reactions

    NASA Astrophysics Data System (ADS)

    Igarashi, Kensuke; Yamamura, Yasuhisa; Kuwabara, Tomohiko

    2016-10-01

    Greigite, a ferrimagnetic iron sulfide Fe(II)Fe(III)2S4, is thought to have played an essential role in chemical evolution leading to the origin of life. Greigite contains a [4Fe-4S] cluster-like structure and has been synthesized in the laboratory by liquid-state reactions. However, it is unclear how greigite can be synthesized in nature. Herein, we show that greigite is synthesized by the solid-gas reaction of Fe(III)-oxide-hydroxides and H2S. We discovered that the hyperthermophilic hydrogenotrophic methanogen Methanocaldococcus jannaschii reduced elemental sulfur, and the resulting sulfide generated greigite from hematite. The time course and pH dependence of the reaction respectively indicated the involvement of amorphous FeS and H2S as reaction intermediates. An abiotic solid-gas reaction of hematite and H2S (g) under strictly anaerobic conditions was developed. The solid-gas reaction fully converted hematite to greigite/pyrite at 40-120 °C within 12 h and was unaffected by the bulk gas phase. Similar abiotic reactions occurred, but relatively slowly, with aqueous H2S in acidulous liquids using hematite, magnetite, or amorphous FeO(OH) as starting materials, suggesting that greigite was extensively produced in the Hadean Eon as these Fe(III)-oxide-hydroxides were shown to be present or routinely produced during that era. Surprisingly, the obtained greigite induced methanogenesis and growth of hydrogenotrophic methanogens, suggesting that the external greigite crystals enhanced reactions that would otherwise require enzymes, such as [4Fe-4S] cluster-harboring membrane-bound hydrogenases. These data suggested that the greigite produced by the solid-gas and solid-dissolved gas reactions was bioactive.

  16. Miniature solid-state gas compressor

    DOEpatents

    Lawless, W.N.; Cross, L.E.; Steyert, W.A.

    1985-05-07

    A miniature apparatus for compressing gases is disclosed in which an elastomer disposed between two opposing electrostrictive or piezoelectric ceramic blocks, or between a single electrostrictive or piezoelectric ceramic block and a rigid surface, is caused to extrude into or recede from a channel defined adjacent to the elastomer in response to application or removal of an electric field from the blocks. Individual cells of blocks and elastomer are connected to effect a gas compression by peristaltic activation of the individual cells. The apparatus is self-valving in that the first and last cells operate as inlet and outlet valves, respectively. Preferred electrostrictive and piezoelectric ceramic materials are disclosed, and an alternative, non-peristaltic embodiment of the apparatus is described. 9 figs.

  17. Miniature solid-state gas compressor

    DOEpatents

    Lawless, William N.; Cross, Leslie E.; Steyert, William A.

    1985-01-01

    A miniature apparatus for compressing gases is disclosed in which an elastomer disposed between two opposing electrostrictive or piezoelectric ceramic blocks, or between a single electrostrictive or piezoelectric ceramic block and a rigid surface, is caused to extrude into or recede from a channel defined adjacent to the elastomer in response to application or removal of an electric field from the blocks. Individual cells of blocks and elastomer are connected to effect a gas compression by peristaltic activation of the individual cells. The apparatus is self-valving in that the first and last cells operate as inlet and outlet valves, respectively. Preferred electrostrictive and piezoelectric ceramic materials are disclosed, and an alternative, non-peristaltic embodiment of the apparatus is described.

  18. Turbulence modeling of gas-solid suspension flows

    NASA Technical Reports Server (NTRS)

    Chen, C. P.

    1988-01-01

    The purpose here is to discuss and review advances in two-phase turbulent modeling techniques and their applications in various gas-solid suspension flow situations. In addition to the turbulence closures, heat transfer effect, particle dispersion and wall effects are partially covered.

  19. Reactivity and Characterization of Solid State Hydrodesulfurization Catalysts.

    NASA Astrophysics Data System (ADS)

    Lindner, James Henry

    1990-01-01

    The identification of the phase responsible for hydrodesulfurization (HDS) activity has been the subject of extensive research. In this study, model solid state catalysts prepared from elemental starting materials were synthesized, characterized, and then used to desulfurize thiophene at temperatures ranging from 200-400 ^circC and a pressure of one atmosphere. The results of this work indicate that an increased HDS activity can be correlated with the presence of a poorly crystalline molybdenum sulfide-like phase detected by XRD, HREM, or AEM. The formation of this sulfur-deficient, non-stoichiometric phase could be accomplished by either removing sulfur directly from the catalyst synthesis mixture to yield a non-stoichiometric MoS_{ rm 2-x} moiety, or by introducing a transition metal promoter such as Fe, Co, Ni, or Cu into the system. The promoter atoms induced structural changes in the molybdenum sulfide edge planes by effectively scavenging sulfur during catalyst synthesis to form promoter sulfide species, which enhanced the formation of a non-stoichiometric, highly active molybdenum sulfide. This morphological effect was the primary function of the promoter in this system. All model catalysts displayed similar structure in the (0002) basal plane of MoS_2; however, only the catalytically active samples showed a high concentration of defects and disorder in the (1010), (1011), and (1012) edge planes. The HREM images obtained from these edge planes and their correlation with HDS activity dramatically illustrated the importance of the often-discussed edge plane structure of MoS_2 and its significance on HDS catalysis. Normalization of the HDS activities for the solid state models and a commercial catalyst with O_2 or CO chemisorption uptakes suggested that a similarity may exist between the catalytically active sites of these materials. In-situ XPS revealed that increasing promoter atom concentrations resulted in a more complete reduction of the promoter atom; but

  20. Transport coefficients of solid particles immersed in a viscous gas.

    PubMed

    Garzó, Vicente; Fullmer, William D; Hrenya, Christine M; Yin, Xiaolong

    2016-01-01

    Transport properties of a suspension of solid particles in a viscous gas are studied. The dissipation in such systems arises from two sources: inelasticity in particle collisions and viscous dissipation due to the effect of the gas phase on the particles. Here we consider a simplified case in which the mean relative velocity between the gas and solid phases is taken to be zero, such that "thermal drag" is the only remaining gas-solid interaction. Unlike the previous, more general, treatment of the drag force [Garzó et al., J. Fluid Mech. 712, 129 (2012)]JFLSA70022-112010.1017/jfm.2012.404, here we take into account contributions to the (scaled) transport coefficients η^{*} (shear viscosity), κ^{*} (thermal conductivity), and μ^{*} (Dufour-like coefficient) coming from the temperature dependence of the (dimensionless) friction coefficient γ^{*} characterizing the amplitude of the drag force. At moderate densities, the thermal drag model (which is based on the Enskog kinetic equation) is solved by means of the Chapman-Enskog method and the Navier-Stokes transport coefficients are determined in terms of the coefficient of restitution, the solid volume fraction, and the friction coefficient. The results indicate that the effect of the gas phase on η^{*} and μ^{*} is non-negligible (especially in the case of relatively dilute systems) while the form of κ^{*} is the same as the one obtained in the dry granular limit. Finally, as an application of these results, a linear stability analysis of the hydrodynamic equations is carried out to analyze the conditions for stability of the homogeneous cooling state. A comparison with direct numerical simulations shows a good agreement for conditions of practical interest.

  1. Modeling of fault reactivation and induced seismicity during hydraulic fracturing of shale-gas reservoirs

    EPA Science Inventory

    We have conducted numerical simulation studies to assess the potential for injection-induced fault reactivation and notable seismic events associated with shale-gas hydraulic fracturing operations. The modeling is generally tuned toward conditions usually encountered in the Marce...

  2. Optical instrumentation and study of gas-solid suspension flows

    SciTech Connect

    Ling, S.C.; Pao, H.P.

    1990-09-01

    A new technique and particle detecting system for the quantification of local fluid flow velocities, particle concentrations and size distributions in gas-solid suspension flows has been successfully developed and constructed. A new 2-inch diameter pneumatic-pipe test-loop facility for study of solids transport flows has been built and in operation. In order to check scaling law developed from the experimental results in the 2-inch pipe, a 4-inch pipe test-loop facility was also designed and constructed. In the past, the mechanics of suspended-solid flow have not been solved in a closed form due to the lack of a model for the turbulent field to pick up solid particles from the flow boundary. In this research project, we have identified the existence of micro-hairpin vortices as a major mechanism for the lifting of solid particles from the flow boundary. This permits one to formulate a realistic model. That is, the introduction of a particle source term in the governing transport equation for the suspended particles. The resultant solution predicts the correct critical flow conditions for the initial pickup of different sizes of solid particles and their subsequent concentrations in the flow field. 21 figs.

  3. Space Shuttle Solid Rocket Nozzle Joint 2 Gas Path Study

    NASA Technical Reports Server (NTRS)

    Lui, R. C.; Hyer, R. L.

    1999-01-01

    Each Space Shuttle solid rocket nozzle contains five joints. By design, each nozzle joint utilizes room-temperature vulcanized (RTV) rubber as a thermal barrier to protect the nozzle metal parts and O-rings from heat degradation due to motor combustion gas. Typically, combustion gas does not penetrate through the RTV in nozzle Joints. However, Joint currently experiences gas penetration through the RTV over 90 percent of the time. The occurrence of Joint gas paths is a very complex phenomenon with several known contributors such as the unique geometry of the joint, motor pressure, nozzle vectoring, manufacturing induced RTV voids. RTV material capability, and joint skip (relative radial displacement of joint components). The occurrence of Joint gas paths appears to be a combination of these causes. To better understand the causes of gas paths in Joint, the circumferential locations of gas paths in the RTV were identified and correlated with nozzle vectoring, RTV closeour locations (where the RTV backfill is completed), and X-ray low-density. anomaly (LDA) indications. Results that no specific cause was determined.

  4. Design of Solid-Gas Interfaces for Enhanced Thermal Transfer

    DTIC Science & Technology

    2015-09-28

    solid surfaces in contact with monoatomic and diatomic gases. We demonstrated that the TAC and MAC can be significantly enhanced by proper surface...surfaces in contact with monoatomic and diatomic gases. Guided by the determined relationships and parametric dependencies we proposed and demonstrated...Au) slab in contact with Ar or N2 gas, as depicted in Fig. 1(a). The embedded-atom-method (EAM) potential [14] was used for realistic description

  5. Oscillatory burning of solid propellants including gas phase time lag.

    NASA Technical Reports Server (NTRS)

    T'Ien, J. S.

    1972-01-01

    An analysis has been performed for oscillatory burning of solid propellants including gas phase time lag. The gaseous flame is assumed to be premixed and laminar with a one-step overall chemical reaction. The propellant is assumed to decompose according to the Arrenhius Law, with no condensed phase reaction. With this model, strong gas phase resonance has been found in certain cases at the characteristic gas-phase frequencies, but the peaking of the acoustic admittance is in the direction favoring the damping of pressure waves. At still higher frequencies, moderate wave-amplifying ability was found. The limit of low frequency response obtained previously by Denison and Baum was recovered, and the limitations of the quasi-steady theory were investigated.

  6. Effects of various reactive gas atmospheres on the properties of bio-oil using microwave pyrolysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fast pyrolysis of lignocellulosic biomass produces organic liquids (bio-oil), bio-char, water, and non-condensable gases. The non-condensable gas component typically contains syngas (H2, CO and CO2) as well as small hydrocarbons (CH4, C2H6, and C3H8). Tail Gas Reactive Pyrolysis (TGRP), a patent p...

  7. Gas chromatograph-mass spectrometer (GC/MS) system for quantitative analysis of reactive chemical compounds

    DOEpatents

    Grindstaff, Quirinus G.

    1992-01-01

    Described is a new gas chromatograph-mass spectrometer (GC/MS) system and method for quantitative analysis of reactive chemical compounds. All components of such a GC/MS system external to the oven of the gas chromatograph are programmably temperature controlled to operate at a volatilization temperature specific to the compound(s) sought to be separated and measured.

  8. Slurried solid media for simultaneous water purification and carbon dioxide removal from gas mixtures

    DOEpatents

    Aines, Roger D.; Bourcier, William L.; Viani, Brian

    2013-01-29

    A slurried solid media for simultaneous water purification and carbon dioxide removal from gas mixtures includes the steps of dissolving the gas mixture and carbon dioxide in water providing a gas, carbon dioxide, water mixture; adding a porous solid media to the gas, carbon dioxide, water mixture forming a slurry of gas, carbon dioxide, water, and porous solid media; heating the slurry of gas, carbon dioxide, water, and porous solid media producing steam; and cooling the steam to produce purified water and carbon dioxide.

  9. Theory for Indirect Conduction in Dense, Gas-Solid Systems

    NASA Astrophysics Data System (ADS)

    Lattanzi, Aaron; Hrenya, Christine

    2016-11-01

    Heat transfer in dense gas-solid systems is dominated by conduction, and critical to the operation of rotary-kilns, catalytic cracking, and heat exchangers with solid particles as the heat transfer fluid. In particular, the indirect conduction occurring between two bodies separated by a thin layer of fluid can significantly impact the heat transfer within gas-solid systems. Current state-of-the-art models for indirect conduction assume that particles are surrounded by a static "fluid lens" and that one-dimensional conduction occurs through the fluid lens when the lens overlaps another body. However, attempts to evaluate the effect of surface roughness and fluid lens thickness (theoretical inputs) on indirect conduction have been restricted to static, single-particle cases. By contrast, here we quantify these effects for dynamic, multi-particle systems. This analysis is compared to outputs from computational fluid dynamics and discrete element method (CFD-DEM) simulations of heat transfer in a packed bed and flow down a heated ramp. Analytical predictions for model sensitivity are found to be in agreement with simulation results and differ greatly from the static, single-particle analysis. Namely, indirect conduction in static systems is found to be most sensitive to surface roughness, while dynamic systems are sensitive to the fluid lens thickness.

  10. Statistical thermodynamics of aerosols and the gas-solid Joule-Thomson effect

    NASA Astrophysics Data System (ADS)

    Pierotti, Robert A.; Rybolt, Thomas R.

    1984-04-01

    Due to the adsorption of a gas by a solid, it is expected that an aerosol created by dispersing a fine powder in a gas would have unique thermodynamic properties not found in pure or mixed gases. The virial equation of state associated with an aerosol dusty gas is obtained from statistical thermodynamic considerations. In the theoretical model presented here, the aerosol is considered to be a two component fluid made up of solid particles and gas molecules. The aerosol virial equation of state is used to derive an expression for the Joule-Thomson effect associated with a gas-solid dispersion. The magnitude of the gas-solid Joule-Thomson effect is expressed in terms of gas and gas-solid virial coefficients. Previous adsorption data for an argon-porous carbon system is used to obtain gas-solid virial coefficients and to predict the magnitude of the gas-solid Joule-Thomson effect. A significant enhancement of the Joule-Thomson effect is predicted for gas-solid systems which display a strong interaction. For example, at a temperature of 300 K an argon-Saran 746 porous carbon aerosol system at a concentration of (0.4 g of powder/l of gas) is predicted to have a gas-solid Joule-Thomson coefficient of 3.6 K/atm which is ten times greater than the effect for pure argon.

  11. The equivalent electrical permittivity of gas-solid mixtures at intermediate solid volume fractions.

    SciTech Connect

    Torczynski, John Robert; Ceccio, Steven Louis; Tortora, Paul Richard

    2005-07-01

    Several mixture models are evaluated for their suitability in predicting the equivalent permittivity of dielectric particles in a dielectric medium for intermediate solid volume fractions (0.4 to 0.6). Predictions of the Maxwell, Rayleigh, Bottcher and Bruggeman models are compared to computational simulations of several arrangements of solid particles in a gas and to the experimentally determined permittivity of a static particle bed. The experiment uses spherical glass beads in air, so air and glass permittivity values (1 and 7, respectively) are used with all of the models and simulations. The experimental system used to measure the permittivity of the static particle bed and its calibration are described. The Rayleigh model is found to be suitable for predicting permittivity over the entire range of solid volume fractions (0-0.6).

  12. Dynamics of inelastic and reactive gas-surface collisions

    SciTech Connect

    Smoliar, Laura Ann

    1995-04-01

    The dynamics of inelastic and reactive collisions in atomic beam-surface scattering are presented. The inelastic scattering of hyperthermal rare gaseous atoms from three alkali halide surfaces (LiF, NaCl, GI)was studied to understand mechanical energy transfer in unreactive systems. The dynamics of the chemical reaction in the scattering of H(D) atoms from the surfaces of LIF(001) and the basal plane of graphite were also studied.

  13. Cover and startup gas supply system for solid oxide fuel cell generator

    DOEpatents

    Singh, Prabhakar; George, Raymond A.

    1999-01-01

    A cover and startup gas supply system for a solid oxide fuel cell power generator is disclosed. Hydrocarbon fuel, such as natural gas or diesel fuel, and oxygen-containing gas are supplied to a burner. Combustion gas exiting the burner is cooled prior to delivery to the solid oxide fuel cell. The system mixes the combusted hydrocarbon fuel constituents with hydrogen which is preferably stored in solid form to obtain a non-explosive gas mixture. The system may be used to provide both non-explosive cover gas and hydrogen-rich startup gas to the fuel cell.

  14. Cover and startup gas supply system for solid oxide fuel cell generator

    DOEpatents

    Singh, P.; George, R.A.

    1999-07-27

    A cover and startup gas supply system for a solid oxide fuel cell power generator is disclosed. Hydrocarbon fuel, such as natural gas or diesel fuel, and oxygen-containing gas are supplied to a burner. Combustion gas exiting the burner is cooled prior to delivery to the solid oxide fuel cell. The system mixes the combusted hydrocarbon fuel constituents with hydrogen which is preferably stored in solid form to obtain a non-explosive gas mixture. The system may be used to provide both non-explosive cover gas and hydrogen-rich startup gas to the fuel cell. 4 figs.

  15. Acoustic Probe for Solid-Gas-Liquid Suspension

    SciTech Connect

    Tavlarides, L.L.; Sangani, Ashok

    2003-09-14

    The primary objective of the research project during the first funding period was to develop an acoustic probe to measure volume percent solids in solid-liquid slurries in the presence of small amounts of gas bubbles. This problem was addressed because of the great need for a non-invasive, accurate and reliable method for solids monitoring in liquid slurries in the presence of radiolytically generated gases throughout the DOE complex. These measurements are necessary during mobilization of salts and sediments in tanks, transport of these slurries in transfer lines to processing facilities across a site, and, in some instances, during high level waste processing. Although acoustic probes have been commonly used for monitoring flows in single-phase fluids (McLeod, 1967), their application to monitor two-phase mixtures has not yet fully realized its potential. A number of investigators in recent years have therefore been involved in developing probes for measuring the volume fractions in liquid solid suspensions (Atkinson and Kytomaa, 1993; Greenwood et al., 1993; Martin et al., 1995) and in liquid-liquid suspensions (Bonnet and Tavlarides, 1987; Tavlarides and Bonnet, 1988, Yi and Tavlarides, 1990; Tsouris and Tavlarides, 1993, Tsouris et al., 1995). In particular, Atkinson and Kytomaa (1993) showed that the acoustic technique can be used to determine both the velocity and the volume fraction of solids while Martin et al. (1995) and Spelt et al. (1999) showed that the acoustic probe can also be used to obtain information on the size distribution of the particles. In a recent testing of in-line slurry monitors with radioactive slurries suspended with Pulsair Mixers (Hylton & Bayne, 1999), an acoustic probe did not compare well with other instruments most probably due to presence of entrained gases and improper acoustic frequency range of interrogation. The work of the investigators cited has established the potential of the acoustic probe for characterizing

  16. Acoustic cross-correlation flowmeter for solid-gas flow

    DOEpatents

    Sheen, S.H.; Raptis, A.C.

    1984-05-14

    Apparatus for measuring particle velocity in a solid-gas flow within a pipe includes: first and second transmitting transducers for transmitting first and second ultrasonic signals into the pipe at first and second locations, respectively, along the pipe; an acoustic decoupler, positioned between said first and second transmitting transducers, for acoustically isolating said first and second signals from one another; first and second detecting transducers for detecting said first and second signals and for generating first and second detected signals; and means for cross-correlating said first and second output signals.

  17. Acoustic cross-correlation flowmeter for solid-gas flow

    DOEpatents

    Sheen, Shuh-Haw; Raptis, Apostolos C.

    1986-01-01

    Apparatus for measuring particle velocity in a solid-gas flow within a pipe includes: first and second transmitting transducers for transmitting first and second ultrasonic signals into the pipe at first and second locations, respectively, along the pipe; an acoustic decoupler, positioned between said first and second transmitting transducers, for acoustically isolating said first and second signals from one another; first and second detecting transducers for detecting said first and second signals and for generating first and second detected signals in response to said first and second detected signals; and means for cross-correlating said first and second output signals.

  18. PRESSURIZED SOLID OXIDE FUEL CELL/GAS TURBINE POWER SYSTEM

    SciTech Connect

    W.L. Lundberg; G.A. Israelson; R.R. Moritz; S.E. Veyo; R.A. Holmes; P.R. Zafred; J.E. King; R.E. Kothmann

    2000-02-01

    Power systems based on the simplest direct integration of a pressurized solid oxide fuel cell (SOFC) generator and a gas turbine (GT) are capable of converting natural gas fuel energy to electric power with efficiencies of approximately 60% (net AC/LHV), and more complex SOFC and gas turbine arrangements can be devised for achieving even higher efficiencies. The results of a project are discussed that focused on the development of a conceptual design for a pressurized SOFC/GT power system that was intended to generate 20 MWe with at least 70% efficiency. The power system operates baseloaded in a distributed-generation application. To achieve high efficiency, the system integrates an intercooled, recuperated, reheated gas turbine with two SOFC generator stages--one operating at high pressure, and generating power, as well as providing all heat needed by the high-pressure turbine, while the second SOFC generator operates at a lower pressure, generates power, and provides all heat for the low-pressure reheat turbine. The system cycle is described, major system components are sized, the system installed-cost is estimated, and the physical arrangement of system components is discussed. Estimates of system power output, efficiency, and emissions at the design point are also presented, and the system cost of electricity estimate is developed.

  19. Reactive Gas transport in soil: Kinetics versus Local Equilibrium Approach

    NASA Astrophysics Data System (ADS)

    Geistlinger, Helmut; Jia, Ruijan

    2010-05-01

    Gas transport through the unsaturated soil zone was studied using an analytical solution of the gas transport model that is mathematically equivalent to the Two-Region model. The gas transport model includes diffusive and convective gas fluxes, interphase mass transfer between the gas and water phase, and biodegradation. The influence of non-equilibrium phenomena, spatially variable initial conditions, and transient boundary conditions are studied. The objective of this paper is to compare the kinetic approach for interphase mass transfer with the standard local equilibrium approach and to find conditions and time-scales under which the local equilibrium approach is justified. The time-scale of investigation was limited to the day-scale, because this is the relevant scale for understanding gas emission from the soil zone with transient water saturation. For the first time a generalized mass transfer coefficient is proposed that justifies the often used steady-state Thin-Film mass transfer coefficient for small and medium water-saturated aggregates of about 10 mm. The main conclusion from this study is that non-equilibrium mass transfer depends strongly on the temporal and small-scale spatial distribution of water within the unsaturated soil zone. For regions with low water saturation and small water-saturated aggregates (radius about 1 mm) the local equilibrium approach can be used as a first approximation for diffusive gas transport. For higher water saturation and medium radii of water-saturated aggregates (radius about 10 mm) and for convective gas transport, the non-equilibrium effect becomes more and more important if the hydraulic residence time and the Damköhler number decrease. Relative errors can range up to 100% and more. While for medium radii the local equilibrium approach describes the main features both of the spatial concentration profile and the time-dependence of the emission rate, it fails completely for larger aggregates (radius about 100 mm

  20. 15N solid-state NMR provides a sensitive probe of oxidized flavin reactive sites.

    PubMed

    Koder, Ronald L; Walsh, Joseph D; Pometun, Maxim S; Dutton, P Leslie; Wittebort, Richard J; Miller, Anne-Frances

    2006-11-29

    Flavins are central to the reactivity of a wide variety of enzymes and electron transport proteins. There is great interest in understanding the basis for the different reactivities displayed by flavins in different protein contexts. We propose solid-state nuclear magnetic resonance (SS-NMR) as a tool for directly observing reactive positions of the flavin ring and thereby obtaining information on their frontier orbitals. We now report the SS-NMR signals of the redox-active nitrogens N1 and N5, as well as that of N3. The chemical shift tensor of N5 is over 720 ppm wide, in accordance with the predictions of theory and our calculations. The signal of N3 can be distinguished on the basis of coupling to 1H absent for N1 and N5, as well as the shift tensor span of only 170 ppm, consistent with N3's lower aromaticity and lack of a nonbonding lone pair. The isotropic shifts and spans of N5 and N1 reflect two opposite extremes of the chemical shift range for "pyridine-type" N's, consistent with their electrophilic and nucleophilic chemical reactivities, respectively. Upon flavin reduction, N5's chemical shift tensor contracts dramatically to a span of less than 110 ppm, and the isotropic chemical shift changes by approximately 300 ppm. Both are consistent with loss of N5's nonbonding lone pair and decreased aromaticity, and illustrate the responsiveness of the 15N chemical shift principal values to electronic structure. Thus. 15N chemical shift principal values promise to be valuable tools for understanding electronic differences that underlie variations in flavin reactivity, as well as the reactivities of other heterocyclic cofactors.

  1. A two-fluid model for reactive dilute solid-liquid mixtures with phase changes

    NASA Astrophysics Data System (ADS)

    Reis, Martina Costa; Wang, Yongqi

    2016-12-01

    Based on the Eulerian spatial averaging theory and the Müller-Liu entropy principle, a two-fluid model for reactive dilute solid-liquid mixtures is presented. Initially, some averaging theorems and properties of average quantities are discussed and, then, averaged balance equations including interfacial source terms are postulated. Moreover, constitutive equations are proposed for a reactive dilute solid-liquid mixture, where the formation of the solid phase is due to a precipitation chemical reaction that involves ions dissolved in the liquid phase. To this end, principles of constitutive theory are used to propose linearized constitutive equations that account for diffusion, heat conduction, viscous and drag effects, and interfacial deformations. A particularity of the model is that the mass interfacial source term is regarded as an independent constitutive variable. The obtained results show that the inclusion of the mass interfacial source term into the set of independent constitutive variables permits to easily describe the phase changes associated with precipitation chemical reactions.

  2. A two-fluid model for reactive dilute solid-liquid mixtures with phase changes

    NASA Astrophysics Data System (ADS)

    Reis, Martina Costa; Wang, Yongqi

    2017-03-01

    Based on the Eulerian spatial averaging theory and the Müller-Liu entropy principle, a two-fluid model for reactive dilute solid-liquid mixtures is presented. Initially, some averaging theorems and properties of average quantities are discussed and, then, averaged balance equations including interfacial source terms are postulated. Moreover, constitutive equations are proposed for a reactive dilute solid-liquid mixture, where the formation of the solid phase is due to a precipitation chemical reaction that involves ions dissolved in the liquid phase. To this end, principles of constitutive theory are used to propose linearized constitutive equations that account for diffusion, heat conduction, viscous and drag effects, and interfacial deformations. A particularity of the model is that the mass interfacial source term is regarded as an independent constitutive variable. The obtained results show that the inclusion of the mass interfacial source term into the set of independent constitutive variables permits to easily describe the phase changes associated with precipitation chemical reactions.

  3. Method for generating a highly reactive plasma for exhaust gas aftertreatment and enhanced catalyst reactivity

    DOEpatents

    Whealton, John H.; Hanson, Gregory R.; Storey, John M.; Raridon, Richard J.; Armfield, Jeffrey S.; Bigelow, Timothy S.; Graves, Ronald L.

    2001-01-01

    A method for non-thermal plasma aftertreatment of exhaust gases the method comprising the steps of providing short risetime (about 40 ps), high frequency (about 5G hz), high power bursts of low-duty factor microwaves sufficient to generate a dielectric barrier discharge and passing a gas to treated through the discharge so as to cause dissociative reduction of the exhaust gases. The invention also includes a reactor for generating the non-thermal plasma.

  4. Interpretations of the OSCAR data for reactive-gas scavenging

    SciTech Connect

    Easter, R.C.; Hales, J.M.

    1982-11-01

    A description is given of the application of a reactive scavenging model for the interpretation of data from the Oxidation and Scavenging Characteristics of April Rains (OSCAR) field study to evaluate scavenging mechanisms. The OSCAR experiment, conducted during April 1982, was a cooperative field investigation of wet removal by cyclonic storms. A part of the experiment involved intensive measurements at a site in NE Indiana and was designed to provide needed inputs for diagnostic scavenging models. Sequential precipitation chemistry, surface and airborne air chemistry, cloud physics, and meteorological measurements were performed. The model application reported here involves a single storm event at the Indiana site. Although the work presented involves the analysis of only a single precipitation event over a limited geographical area (10/sup 4/ km/sup 2/), the data utilized have considerable uncertainties, and the model contains numerous approximations, it is nevertheless concluded that the ability of the model to reproduce much of the observed precipitation chemistry behavior for the event is quite encouraging.

  5. Time Resolved X-Ray Diffraction of Reactive Solids Under Dynamic Loadings

    NASA Astrophysics Data System (ADS)

    Yoo, Choong-Shik

    2015-06-01

    We present novel time-resolved (TR) x-ray diffraction and TR Raman spectroscopy capable of probing structural and chemical evolutions of solids undergoing chemical and phase transformations. These methods are applicable to a wide range of dynamic experiments to study both single event phenomena of solids under thermal, electric or mechanical impact conditions and non-single event phenomena under dynamic-diamond anvil cell (d-DAC) and high frequency pulse (or ramp) laser-heated DAC. In this talk, relevant technology developments are described with several examples of our recent studies on reactive metals and dense molecular systems, which are synergistic to many proposed activities to develop dynamic synchrotron x-ray diffraction capabilities centered at advanced third and fourth generation light sources.

  6. Chemical reactivity of graphene oxide towards amines elucidated by solid-state NMR

    NASA Astrophysics Data System (ADS)

    Vacchi, Isabella A.; Spinato, Cinzia; Raya, Jésus; Bianco, Alberto; Ménard-Moyon, Cécilia

    2016-07-01

    Graphene oxide (GO) is an attractive nanomaterial for many applications. Controlling the functionalization of GO is essential for the design of graphene-based conjugates with novel properties. But, the chemical composition of GO has not been fully elucidated yet. Due to the high reactivity of the oxygenated moieties, mainly epoxy, hydroxyl and carboxyl groups, several derivatization reactions may occur concomitantly. The reactivity of GO with amine derivatives has been exploited in the literature to design graphene-based conjugates, mainly through amidation. However, in this study we undoubtedly demonstrate using magic angle spinning (MAS) solid-state NMR that the reaction between GO and amine functions occurs via ring opening of the epoxides, and not by amidation. We also prove that there is a negligible amount of carboxylic acid groups in two GO samples obtained by a different synthesis process, hence eliminating the possibility of amidation reactions with amine derivatives. This work brings additional insights into the chemical reactivity of GO, which is fundamental to control its functionalization, and highlights the major role of MAS NMR spectroscopy for a comprehensive characterization of derivatized GO.Graphene oxide (GO) is an attractive nanomaterial for many applications. Controlling the functionalization of GO is essential for the design of graphene-based conjugates with novel properties. But, the chemical composition of GO has not been fully elucidated yet. Due to the high reactivity of the oxygenated moieties, mainly epoxy, hydroxyl and carboxyl groups, several derivatization reactions may occur concomitantly. The reactivity of GO with amine derivatives has been exploited in the literature to design graphene-based conjugates, mainly through amidation. However, in this study we undoubtedly demonstrate using magic angle spinning (MAS) solid-state NMR that the reaction between GO and amine functions occurs via ring opening of the epoxides, and not by

  7. Non-reactive and reactive trace gas fluxes: Simultaneous measurements with ground based and vertically integrating methods

    NASA Astrophysics Data System (ADS)

    Mayer, J.-C.; Rummel, U.; Andreae, M. O.; Foken, T.; Meixner, F. X.

    2009-04-01

    The footprint area, i.e. the source region of a flux measured at a certain location, increases with increasing height above ground of the flux measurements. For non-reactive trace gases and horizontally homogeneous terrain (particularly with respect to deposition and emission processes), an increase in height should not alter the actual measured flux (constant flux layer assumption). For reactive trace gases, with chemical life times of about 30 s - 300 s, chemical production and loss processes within the measuring layer lead to vertical flux divergence. The magnitude of the flux divergence can be determined directly by comparing fluxes of reactive trace gases being affected by chemistry with fluxes of the same species being not altered by chemistry. In August 2006, the field experiment LIBRETTO (LIndenBerg REacTive Trace gas prOfiles) was carried out in cooperation with the German Meteorological Service (DWD) at the field site of the Richard Aßmann Observatory in Lindenberg. At a 99 m mast, profiles of air temperature, relative humidity, wind speed and direction were measured. The mast is equipped with an elevator, where sensors for trace gases (CO2, H2O, O3), air temperature and relative humidity have been installed. During the experiment, the elevator system was run continuously, providing scanned profiles of trace gas concentrations from 2 m to 99 m a.g.l. of the atmospheric boundary layer (ABL) approx. every 10 minutes. Between 0.15 m and 2.0 m, concentration differences of the trace gases CO2, H2O, O3, NO and NO2 were measured. Applying the modified Bowen ration (MBR) method to the measured concentration differences and directly measured sensible heat flux (eddy covariance data from DWD) yields surface fluxes of the trace gases. Integral fluxes of CO2, O3 and sensible heat were computed simultaneously by applying the nocturnal boundary layer budget method to the scanned elevator profiles. A direct comparison showed little deviations between the two methods

  8. Low-frequency sound transmission through a gas-solid interface.

    PubMed

    Godin, Oleg A

    2011-02-01

    Sound transmission through gas-solid interfaces is usually very weak because of the large contrast in wave impedances at the interface. Here, it is shown that diffraction effects can lead to a dramatic increase in the transparency of gas-solid interfaces at low frequencies, resulting in the bulk of energy emitted by compact sources within a solid being radiated into a gas. The anomalous transparency is made possible by power fluxes in evanescent body waves and by excitation of interface waves. Sound transmission into gas is found to be highly sensitive to absorption of elastic waves within a solid.

  9. Water-Gas Shift and Methane Reactivity on Reducible Perovskite-Type Oxides.

    PubMed

    Thalinger, Ramona; Opitz, Alexander K; Kogler, Sandra; Heggen, Marc; Stroppa, Daniel; Schmidmair, Daniela; Tappert, Ralf; Fleig, Jürgen; Klötzer, Bernhard; Penner, Simon

    2015-05-28

    Comparative (electro)catalytic, structural, and spectroscopic studies in hydrogen electro-oxidation, the (inverse) water-gas shift reaction, and methane conversion on two representative mixed ionic-electronic conducting perovskite-type materials La0.6Sr0.4FeO3-δ (LSF) and SrTi0.7Fe0.3O3-δ (STF) were performed with the aim of eventually correlating (electro)catalytic activity and associated structural changes and to highlight intrinsic reactivity characteristics as a function of the reduction state. Starting from a strongly prereduced (vacancy-rich) initial state, only (inverse) water-gas shift activity has been observed on both materials beyond ca. 450 °C but no catalytic methane reforming or methane decomposition reactivity up to 600 °C. In contrast, when starting from the fully oxidized state, total methane oxidation to CO2 was observed on both materials. The catalytic performance of both perovskite-type oxides is thus strongly dependent on the degree/depth of reduction, on the associated reactivity of the remaining lattice oxygen, and on the reduction-induced oxygen vacancies. The latter are clearly more reactive toward water on LSF, and this higher reactivity is linked to the superior electrocatalytic performance of LSF in hydrogen oxidation. Combined electron microscopy, X-ray diffraction, and Raman measurements in turn also revealed altered surface and bulk structures and reactivities.

  10. Water-Gas Shift and Methane Reactivity on Reducible Perovskite-Type Oxides

    PubMed Central

    2015-01-01

    Comparative (electro)catalytic, structural, and spectroscopic studies in hydrogen electro-oxidation, the (inverse) water-gas shift reaction, and methane conversion on two representative mixed ionic–electronic conducting perovskite-type materials La0.6Sr0.4FeO3−δ (LSF) and SrTi0.7Fe0.3O3−δ (STF) were performed with the aim of eventually correlating (electro)catalytic activity and associated structural changes and to highlight intrinsic reactivity characteristics as a function of the reduction state. Starting from a strongly prereduced (vacancy-rich) initial state, only (inverse) water-gas shift activity has been observed on both materials beyond ca. 450 °C but no catalytic methane reforming or methane decomposition reactivity up to 600 °C. In contrast, when starting from the fully oxidized state, total methane oxidation to CO2 was observed on both materials. The catalytic performance of both perovskite-type oxides is thus strongly dependent on the degree/depth of reduction, on the associated reactivity of the remaining lattice oxygen, and on the reduction-induced oxygen vacancies. The latter are clearly more reactive toward water on LSF, and this higher reactivity is linked to the superior electrocatalytic performance of LSF in hydrogen oxidation. Combined electron microscopy, X-ray diffraction, and Raman measurements in turn also revealed altered surface and bulk structures and reactivities. PMID:26045733

  11. A (reactive) lattice-gas approach to economic cycles

    NASA Astrophysics Data System (ADS)

    Ausloos, Marcel; Clippe, Paulette; Miśkiewicz, Janusz; Peķalski, Andrzej

    2004-12-01

    A microscopic approach to macroeconomic features is intended. A model for macroeconomic behavior under heterogeneous spatial economic conditions is reviewed. A birth-death lattice gas model taking into account the influence of an economic environment on the fitness and concentration evolution of economic entities is numerically and analytically examined. The reaction-diffusion model can also be mapped onto a high-order logistic map. The role of the selection pressure along various dynamics with entity diffusion on a square symmetry lattice has been studied by Monte-Carlo simulation. The model leads to a sort of phase transition for the fitness gap as a function of the selection pressure and to cycles. The control parameter is a (scalar) “business plan”. The business plan(s) allows for spin-offs or merging and enterprise survival evolution law(s), whence bifurcations, cycles and chaotic behavior.

  12. Co-processing of agricultural plastic waste and switchgrass via tail gas reactive pyrolysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mixtures of agricultural plastic waste in the form of polyethylene hay bale covers (PE) (4-37%) and switchgrass were investigated using the US Department of Agriculture’s tail gas reactive pyrolysis (TGRP) at different temperatures (400-570 deg C). TGRP of switchgrass and plastic mixtures significan...

  13. High sensitivity gas spectroscopy of porous, highly scattering solids.

    PubMed

    Svensson, Tomas; Andersson, Mats; Rippe, Lars; Johansson, Jonas; Folestad, Staffan; Andersson-Engels, Stefan

    2008-01-01

    We present minimalistic and cost-efficient instrumentation employing tunable diode laser gas spectroscopy for the characterization of porous and highly scattering solids. The sensitivity reaches 3 x 10(-6) (absorption fraction), and the improvement with respect to previous work in this field is a factor of 10. We also provide the first characterization of the interference phenomenon encountered in high-resolution spectroscopy of turbid samples. Revealing that severe optical interference originates from the samples, we discuss important implications for system design. In addition, we introduce tracking coils and sample rotation as new and efficient tools for interference suppression. The great value of the approach is illustrated in an application addressing structural properties of pharmaceutical materials.

  14. Normal stress differences in a sheared gas-solid suspension

    NASA Astrophysics Data System (ADS)

    Saha, Saikat; Alam, Meheboob

    2016-11-01

    The stress tensor and normal stress differences are analyzed for a homogeneously sheared gas-solid suspension using Enskog-Boltzmann equation. Inelastic particles are suspended in a viscous fluid of viscosity μf and experience a Stokes drag force. Viscous heating due to shear is compensated by (i) the inelastic collisions between particles and (ii) the drag force experienced by the particles due to the interstitial fluid. Rheology of the particle phase is analyzed with anisotropic-Gaussian as the single particle distribution function. The first (N1) and second (N2) normal stress differences are computed as functions of the density (ν), Stokes number (St) and restitution coefficient (e). A comparison with the existing simulation data shows an excellent agreement for both N1 and N2 over the predictions from other Grad-level theories. Finally, in the limit of St -> ∞ (μf -> 0), the related results from the conventional theory of dry granular flows are recovered.

  15. Ferroelectric Dispersed Composite Solid Electrolyte for CO2 Gas Sensor

    NASA Astrophysics Data System (ADS)

    Singh, K.; Ambekar, P.; Bhoga, S. S.

    2002-12-01

    The Li2CO3:LiNbO3 composite system was investigated for the application in electrochemical gas sensor. The conductivity maximum is observed for 50Li2CO3+50LiNbO3. An enhancement in conductivity is understood to be due to the percolation threshold. The composite is also seen less sensitive to moisture. Potentiometric sensors are obtained using optimized composition. At the reference electrode, the activity of Li+ is fixed by using open reference electrode material. Good reversibility of cell emf was observed for PCO2 ranging from 200 ppm to 20% at 400°C. The cell response was Nernstian, following nearly two-electron reaction. The sensor showed negligible cross-sensitivity to moisture. Developed solid electrolyte not only exhibit shorter response time but also improves over all performance relative to the sensor based on pure carbonate.

  16. Study of Solid Particle Behavior in High Temperature Gas Flows

    NASA Astrophysics Data System (ADS)

    Majid, A.; Bauder, U.; Stindl, T.; Fertig, M.; Herdrich, G.; Röser, H.-P.

    2009-01-01

    The Euler-Lagrangian approach is used for the simulation of solid particles in hypersonic entry flows. For flow field simulation, the program SINA (Sequential Iterative Non-equilibrium Algorithm) developed at the Institut für Raumfahrtsysteme is used. The model for the effect of the carrier gas on a particle includes drag force and particle heating only. Other parameters like lift Magnus force or damping torque are not taken into account so far. The reverse effect of the particle phase on the gaseous phase is currently neglected. Parametric analysis is done regarding the impact of variation in the physical input conditions like position, velocity, size and material of the particle. Convective heat fluxes onto the surface of the particle and its radiative cooling are discussed. The variation of particle temperature under different conditions is presented. The influence of various input conditions on the trajectory is explained. A semi empirical model for the particle wall interaction is also discussed and the influence of the wall on the particle trajectory with different particle conditions is presented. The heat fluxes onto the wall due to impingement of particles are also computed and compared with the heat fluxes from the gas.

  17. Generalized gas-solid adsorption modeling: Single-component equilibria

    SciTech Connect

    Ladshaw, Austin; Yiacoumi, Sotira; Tsouris, Costas; DePaoli, David W.

    2015-01-07

    Over the last several decades, modeling of gas–solid adsorption at equilibrium has generally been accomplished through the use of isotherms such as the Freundlich, Langmuir, Tóth, and other similar models. While these models are relatively easy to adapt for describing experimental data, their simplicity limits their generality to be used with many different sets of data. This limitation forces engineers and scientists to test each different model in order to evaluate which one can best describe their data. Additionally, the parameters of these models all have a different physical interpretation, which may have an effect on how they can be further extended into kinetic, thermodynamic, and/or mass transfer models for engineering applications. Therefore, it is paramount to adopt not only a more general isotherm model, but also a concise methodology to reliably optimize for and obtain the parameters of that model. A model of particular interest is the Generalized Statistical Thermodynamic Adsorption (GSTA) isotherm. The GSTA isotherm has enormous flexibility, which could potentially be used to describe a variety of different adsorption systems, but utilizing this model can be fairly difficult due to that flexibility. To circumvent this complication, a comprehensive methodology and computer code has been developed that can perform a full equilibrium analysis of adsorption data for any gas-solid system using the GSTA model. The code has been developed in C/C++ and utilizes a Levenberg–Marquardt’s algorithm to handle the non-linear optimization of the model parameters. Since the GSTA model has an adjustable number of parameters, the code iteratively goes through all number of plausible parameters for each data set and then returns the best solution based on a set of scrutiny criteria. Data sets at different temperatures are analyzed serially and then linear correlations with temperature are made for the parameters of the model. The end result is a full set of

  18. Generalized gas-solid adsorption modeling: Single-component equilibria

    DOE PAGES

    Ladshaw, Austin; Yiacoumi, Sotira; Tsouris, Costas; ...

    2015-01-07

    Over the last several decades, modeling of gas–solid adsorption at equilibrium has generally been accomplished through the use of isotherms such as the Freundlich, Langmuir, Tóth, and other similar models. While these models are relatively easy to adapt for describing experimental data, their simplicity limits their generality to be used with many different sets of data. This limitation forces engineers and scientists to test each different model in order to evaluate which one can best describe their data. Additionally, the parameters of these models all have a different physical interpretation, which may have an effect on how they can bemore » further extended into kinetic, thermodynamic, and/or mass transfer models for engineering applications. Therefore, it is paramount to adopt not only a more general isotherm model, but also a concise methodology to reliably optimize for and obtain the parameters of that model. A model of particular interest is the Generalized Statistical Thermodynamic Adsorption (GSTA) isotherm. The GSTA isotherm has enormous flexibility, which could potentially be used to describe a variety of different adsorption systems, but utilizing this model can be fairly difficult due to that flexibility. To circumvent this complication, a comprehensive methodology and computer code has been developed that can perform a full equilibrium analysis of adsorption data for any gas-solid system using the GSTA model. The code has been developed in C/C++ and utilizes a Levenberg–Marquardt’s algorithm to handle the non-linear optimization of the model parameters. Since the GSTA model has an adjustable number of parameters, the code iteratively goes through all number of plausible parameters for each data set and then returns the best solution based on a set of scrutiny criteria. Data sets at different temperatures are analyzed serially and then linear correlations with temperature are made for the parameters of the model. The end result is a full set

  19. Chemical reactivity of graphene oxide towards amines elucidated by solid-state NMR.

    PubMed

    Vacchi, Isabella A; Spinato, Cinzia; Raya, Jésus; Bianco, Alberto; Ménard-Moyon, Cécilia

    2016-07-14

    Graphene oxide (GO) is an attractive nanomaterial for many applications. Controlling the functionalization of GO is essential for the design of graphene-based conjugates with novel properties. But, the chemical composition of GO has not been fully elucidated yet. Due to the high reactivity of the oxygenated moieties, mainly epoxy, hydroxyl and carboxyl groups, several derivatization reactions may occur concomitantly. The reactivity of GO with amine derivatives has been exploited in the literature to design graphene-based conjugates, mainly through amidation. However, in this study we undoubtedly demonstrate using magic angle spinning (MAS) solid-state NMR that the reaction between GO and amine functions occurs via ring opening of the epoxides, and not by amidation. We also prove that there is a negligible amount of carboxylic acid groups in two GO samples obtained by a different synthesis process, hence eliminating the possibility of amidation reactions with amine derivatives. This work brings additional insights into the chemical reactivity of GO, which is fundamental to control its functionalization, and highlights the major role of MAS NMR spectroscopy for a comprehensive characterization of derivatized GO.

  20. A CFD study of gas-solid jet in a CFB riser flow

    SciTech Connect

    Li, Tingwen; Guenther, Chris

    2012-03-01

    Three-dimensional high-resolution numerical simulations of a gas–solid jet in a high-density riser flow were conducted. The impact of gas–solid injection on the riser flow hydrodynamics was investigated with respect to voidage, tracer mass fractions, and solids velocity distribution. The behaviors of a gas–solid jet in the riser crossflow were studied through the unsteady numerical simulations. Substantial separation of the jetting gas and solids in the riser crossflow was observed. Mixing of the injected gas and solids with the riser flow was investigated and backmixing of gas and solids was evaluated. In the current numerical study, both the overall hydrodynamics of riser flow and the characteristics of gas–solid jet were reasonably predicted compared with the experimental measurements made at NETL.

  1. Reactive sputtering of titanium in Ar/CH4 gas mixture: Target poisoning and film characteristics

    SciTech Connect

    Fouad, O.A.; Rumaiz, A.; Shah, S.

    2009-03-01

    Reactive sputtering of titanium target in the presence of Ar/CH{sub 4} gas mixture has been investigated. With the addition of methane gas to above 1.5% of the process gas a transition from the metallic sputtering mode to the poison mode was observed as indicated by the change in cathode current. As the methane gas flow concentration increased up to 10%, the target was gradually poisoned. The hysteresis in the cathode current could be plotted by first increasing and then subsequently decreasing the methane concentration. X-ray diffraction and X-ray photoelectron spectroscopy analyses of the deposited films confirmed the formation of carbide phases and the transition of the process from the metallic to compound sputtering mode as the methane concentration in the sputtering gas is increased. The paper discusses a sputtering model that gives a rational explanation of the target poisoning phenomenon and shows an agreement between the experimental observations and calculated results.

  2. Anode materials for sour natural gas solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Danilovic, Nemanja

    Novel anode catalysts have been developed for sour natural gas solid oxide fuel cell (SOFC) applications. Sour natural gas comprises light hydrocarbons, and typically also contains H2S. An alternative fuel SOFC that operates directly on sour natural gas would reduce the overall cost of plant construction and operation for fuel cell power generation. The anode for such a fuel cell must have good catalytic and electrocatalytic activity for hydrocarbon conversion, sulfur-tolerance, resistance to coking, and good electronic and ionic conductivity. The catalytic activity and stability of ABO3 (A= La, Ce and/or Sr, B=Cr and one or more of Ti, V, Cr, Fe, Mn, or Co) perovskites as SOFC anode materials depends on both A and B, and are modified by substituents. The materials have been prepared by both solid state and wet-chemical methods. The physical and chemical characteristics of the materials have been fully characterized using electron microscopy, XRD, calorimetry, dilatometry, particle size and area, using XPS and TGA-DSC-MS. Electrochemical performance was determined using potentiodynamic and potentiostatic cell testing, electrochemical impedance analysis, and conductivity measurements. Neither Ce0.9Sr0.1VO3 nor Ce0.9 Sr0.1Cr0.5V0.5O3 was an active anode for oxidation of H2 and CH4 fuels. However, active catalysts comprising Ce0:9Sr0:1V(O,S)3 and Ce0.9Sr 0.1Cr0.5V0.5(O,S)3 were formed when small concentrations of H2S were present in the fuels. The oxysulfides formed in-situ were very active for conversion of H2S. The maximum performance improved from 50 mW cm-2 to 85 mW cm -2 in 0.5% H2S/CH4 at 850°C with partial substitution of V by Cr in Ce0.9Sr0.1V(O,S)3. Selective conversion of H2S offers potential for sweetening of sour gas without affecting the hydrocarbons. Perovskites La0.75Sr0.25Cr0.5X 0.5O3--delta, (henceforth referred to as LSCX, X=Ti, Mn, Fe, Co) are active for conversion of H2, CH4 and 0.5% H2S/CH4. The order of activity in the different fuels depends on

  3. Abundance and Utility: For Military Operations, Liquid Fuels Remain a Solid Choice over Natural Gas

    DTIC Science & Technology

    2014-08-01

    and combat support vehicles, ships, and aircraft, the adoption of natural gas —whether as compressed natural gas (CNG) or liquefied natural gas (LNG...tacticaldefensemedia.com16 | DoD Power & Energy Fall 2014 For Military Operations, Liquid Fuels Remain a Solid Choice over Natural Gas By Bret...Strogen and Patrick Lobner Abundance and Utility Fueling the Force Natural Gas M ilitary energy strategists often recount the British Royal Navy’s decision

  4. Impact of exhaust gas recirculation (EGR) on the oxidative reactivity of diesel engine soot

    SciTech Connect

    Al-Qurashi, Khalid; Boehman, Andre L.

    2008-12-15

    This paper expands the consideration of the factors affecting the nanostructure and oxidative reactivity of diesel soot to include the impact of exhaust gas recirculation (EGR). Past work showed that soot derived from oxygenated fuels such as biodiesel carries some surface oxygen functionality and thereby possesses higher reactivity than soot from conventional diesel fuel. In this work, results show that EGR exerts a strong influence on the physical properties of the soot which leads to enhanced oxidation rate. HRTEM images showed a dramatic difference between the burning modes of the soot generated under 0 and 20% EGR. The soot produced under 0% EGR strictly followed an external burning mode with no evidence of internal burning. In contrast, soot generated under 20% EGR exhibited dual burning modes: slow external burning and rapid internal burning. The results demonstrate clearly that highly reactive soot can be achieved by manipulating the physical properties of the soot via EGR. (author)

  5. Numerical Modeling of Reactive Multiphase Flow for FCC and Hot Gas Desulfurization Circulating Fluidized Beds

    SciTech Connect

    Miller, Aubrey L.

    2005-07-01

    This work was carried out to understand the behavior of the solid and gas phases in a CFB riser. Only the riser is modeled as a straight pipe. A model with linear algebraic approximation to solids viscosity of the form, {musubs} = 5.34{epsisubs}, ({espisubs} is the solids volume fraction) with an appropriate boundary condition at the wall obtained by approximate momentum balance solution at the wall to acount for the solids recirculation is tested against experimental results. The work done was to predict the flow patterns in the CFB risers from available experimental data, including data from a 7.5-cm-ID CFB riser at the Illinois Institute of Technology and data from a 20.0-cm-ID CFB riser at the Particulate Solid Research, Inc., facility. This research aims at modeling the removal of hydrogen sulfide from hot coal gas using zinc oxide as the sorbent in a circulating fluidized bed and in the process indentifying the parameters that affect the performance of the sulfidation reactor. Two different gas-solid reaction models, the unreacted shrinking core (USC) and the grain model were applied to take into account chemical reaction resistances. Also two different approaches were used to affect the hydrodynamics of the process streams. The first model takes into account the effect of micro-scale particle clustering by adjusting the gas-particle drag law and the second one assumes a turbulent core with pseudo-steady state boundary condition at the wall. A comparison is made with experimental results.

  6. Reactive solid-state dewetting of Cu-Ni films on silicon

    NASA Astrophysics Data System (ADS)

    Clearfield, Raphael; Railsback, Justin G.; Pearce, Ryan C.; Hensley, Dale K.; Fowlkes, Jason D.; Fuentes-Cabrera, Miguel; Simpson, Michael L.; Rack, Philip D.; Melechko, Anatoli V.

    2010-12-01

    The behavior of a 50 nm Cu-Ni alloy film on Si in a process of reactive solid-state dewetting is presented. The films were annealed at a range of temperatures (300-700 °C) in 1% H2 99% N2 reducing atmosphere. The resulting alloy and silicide particles formed by film dewetting and film reaction with the substrate were distinguished by selective wet etching and examined by scanning electron microscopy and spectroscopy. After potassium hydroxide etch, regions that etch slower than silicon substrate have distribution statistics similar to the alloy and silicide particles prior to their removal, indicating strong coupling between mass transport across the interface and along the surface.

  7. Surface emission of landfill gas from solid waste landfill

    NASA Astrophysics Data System (ADS)

    Park, Jin-Won; Shin, Ho-Chul

    The surface emission of landfill gas (LFG) was studied to estimate the amount of LFG efflux from solid waste landfills using an air flux chamber. LFG efflux increased as atmospheric temperature increased during the day, and the same pattern for the surface emission was observed for the change of seasons. LFG efflux rate decreased from summer through winter. The average LFG efflux rates of winter, spring and summer were 0.1584, 0.3013 and 0.8597 m 3 m -2 h -1 respectively. The total amount of surface emission was calculated based on the seasonal LFG efflux rate and the landfill surface area. From the estimates of LFG generation, it is expected that about 30% of the generated LFG may be released through the surface without extraction process. As forced extraction with a blower proceeded, the extraction well pressure decreased from 1100 to -100 mm H 2O, and the LFG surface efflux decreased markedly above 80%. Thus, the utilization of LFG by forced extraction would be the good solution for global warming and air pollution by LFG.

  8. Gas-solid alkali destruction of volatile chlorocarbons

    SciTech Connect

    Foropoulos, J. Jr.

    1995-12-01

    Many chlorocarbons are environmental dangers and health hazards. The simplest perchlorinated hydrocarbon, carbon tetrachloride, is near the top of the list of hazardous compounds. Carbon tetrachloride was used as a cleaning fluid, solvent, and fire-extinguishing agent. The nuclear and defense complexes also employed great quantities of carbon tetrachloride and other chlorocarbons as cleaning and degreasing agents. Many sites nationwide have underground chlorocarbon contamination plumes. Bulk chlorocarbon inventories at many locations await treatment and disposal. Often the problem is compounded by the chlorocarbon being radioactively contaminated. Waste inventory and groundwater contamination problems exist for many other chlorocarbons, especially methylene chloride, chloroform, and tri- and tetrachloroethylene. In this work solid soda lime (a fused mixture of approximately 95% CaO and 5% NaOH in a coarse, granulated form) at 350 C to 400 C acts as the hydrolyzing degradation, and off-gas scrubbing medium. Within soda lime CO{sub 2} and HCl from hydrolysis and degradation convert immediately to calcium and sodium chlorides and carbonates, with water vapor as a volatile byproduct.

  9. Infrared spectroscopy study of electrochromic nanocrystalline tungsten oxide films made by reactive advanced gas deposition

    NASA Astrophysics Data System (ADS)

    Solis, J. L.; Hoel, A.; Lantto, V.; Granqvist, C. G.

    2001-03-01

    Nanocrystalline W oxide films were produced by advanced reactive gas deposition. The material consisted of ˜6 nm diameter tetragonal crystallites, as found from x-ray diffraction and electron microscopy. Optoelectrochemical measurements demonstrated electrochromism upon Li+ intercalation/deintercalation, and infrared absorption spectroscopy gave clear evidence for longitudinal and transversal optical modes being modified following the lithiation. Our data were consistent with ionic transport predominantly in disordered grain boundaries and intercrystalline regions and with electrochromism being associated with small polaron formation.

  10. Thermocapillary Interaction between a Solid Particle and a Liquid-Gas Interface

    NASA Astrophysics Data System (ADS)

    Golovin, A. A.; Leshansky, A. M.; Nir, A.

    1996-11-01

    Interaction between solid particles and a free liquid-gas interface is very important for flotation processes and for various processes involving multiphase flows. In the present contribution, interaction between a hot solid particle submerged into an ambient fluid, and a free liquid-gas interface is considered. A non-uniform temperature field around the solid particle produces surface tension gradients at the liquid-gas interface which generate a thermocapillary flow in the surrounding fluid. This flow yields the motion of the solid particle itself. Three cases are considered: (i) interaction between a solid particle and a spherical gas bubble at a finite separation distance; (ii) thermocapillary motion of a solid particle and an attached gas bubble; (iii) interaction between a solid particle and a plane undeformable liquid-gas interface. In all cases the velocity of the thermocapillarity induced motion of the solid particle is calculated in the approximation of the Stokes flow and a low Peclet number as a function of the separation distance and the bubble-to-particle radii ratio. Some preliminary results of the present work have been published in (A.A.Golovin, Int. J. Multiphase Flow 21), 715 (1995)..

  11. Investigating ebullition in a sand column using dissolved gas analysis and reactive transport modeling

    USGS Publications Warehouse

    Amos, Richard T.; Mayer, K. Ulrich

    2006-01-01

    Ebullition of gas bubbles through saturated sediments can enhance the migration of gases through the subsurface, affect the rate of biogeochemical processes, and potentially enhance the emission of important greenhouse gases to the atmosphere. To better understand the parameters controlling ebullition, methanogenic conditions were produced in a column experiment and ebullition through the column was monitored and quantified through dissolved gas analysis and reactive transport modeling. Dissolved gas analysis showed rapid transport of CH4 vertically through the column at rates several times faster than the bromide tracer and the more soluble gas CO2, indicating that ebullition was the main transport mechanism for CH4. An empirically derived formulation describing ebullition was integrated into the reactive transport code MIN3P allowing this process to be investigated on the REV scale in a complex geochemical framework. The simulations provided insights into the parameters controlling ebullition and show that, over the duration of the experiment, 36% of the CH4 and 19% of the CO2 produced were transported to the top of the column through ebullition.

  12. Experimental design for reflection measurements of highly reactive liquid or solid substances with application to liquid sodium

    SciTech Connect

    Chan, S.H.; Gossler, A.A.

    1980-06-30

    A versatile goniometer system with associated electronic components and mechanical instruments has been assembled. It is designed to measure spectral, specular reflectances of highly reactive liquid or solid substances over a spectral range of 0.3 to 9 ..mu.. and incidence angles of 12 to 30/sup 0/ off the normal direction. The capability of measuring reflectances of liquid substances clearly distinguishes this experimental design from conventional systems which are applicable only to solid substances. This design has been used to measure the spectral, specular reflectance of liquid sodium and preliminary results obtained are compared with those of solid sodium measured by other investigators.

  13. Organometallic synthesis, reactivity and catalysis in the solid state using well-defined single-site species

    PubMed Central

    Pike, Sebastian D.; Weller, Andrew S.

    2015-01-01

    Acting as a bridge between the heterogeneous and homogeneous realms, the use of discrete, well-defined, solid-state organometallic complexes for synthesis and catalysis is a remarkably undeveloped field. Here, we present a review of this topic, focusing on describing the key transformations that can be observed at a transition-metal centre, as well as the use of well-defined organometallic complexes in the solid state as catalysts. There is a particular focus upon gas–solid reactivity/catalysis and single-crystal-to-single-crystal transformations. PMID:25666064

  14. ORIGIN OF THERMAL FLUIDS AT LASSEN VOLCANIC NATIONAL PARK: EVIDENCE FROM NOBLE AND REACTIVE GAS ABUNDANCES.

    USGS Publications Warehouse

    Truesdell, Alfred H.; Mazor, Emanuel; Nehring, Nancy L.

    1983-01-01

    Thermal fluid discharges at Lassen are dominated by high-altitude fumaroles and acid-sulfate hot springs in the Park, and lower altitude, neutral, high-chloride hot springs in Mill Valley 7-10 km to the south. The interrelations of these fluids have been studied by noble and reactive gas analyses. Atmospheric noble gas (ANG) contents of superheated fumaroles are similar to those of air-saturated recharge water (ASW) at 5 degree C and 2500-m elevation. Low-elevation, high-chloride, hot-spring waters are highly depleted in ANG, relative to the ASW. The surface temperatures and gas chemistry of the fumaroles and hot springs suggest that steam originating from partial to near-complete vaporization of liquid from a boiling, high-chloride, hot water aquifer is decompressed adiabatically, and more or less mixed with shallow groundwater to form superheated and drowned fumaroles within the Park. Refs.

  15. Laboratory tests in support of the MSRE reactive gas removal system

    SciTech Connect

    Rudolph, J.C.; Del Cul, G.D.; Caja, J.; Toth, L.M.; Williams, D.F.; Thomas, K.S.; Clark, D.E.

    1997-07-01

    The Molten Salt Reactor Experiment (MSRE) at Oak Ridge National Laboratory has been shut down since December 1969, at which time the molten salt mixture of LiF-BeF{sub 2}-ZrF{sub 4}-{sup 233}UF{sub 4} (64.5-30.3-5.0-0.13 mol%) was transferred to fuel salt drain tanks for storage. In the late 1980s, increased radiation in one of the gas lines from the drain tank was attributed to {sup 233}UF{sub 6}. In 1994 two gas samples were withdraw (from a gas line in the Vent House connecting to the drain tanks) and analyzed. Surprisingly, 350 mm Hg of F{sub 2}, 70 mm Hg of UF{sub 6}, and smaller amounts of other gases were found in both of the samples. To remote this gas from above the drain tanks and all of the associated piping, the reactive gas removal system (RGRS) was designed. This report details the laboratory testing of the RGRS, using natural uranium, prior to its implementation at the MSRE facility. The testing was performed to ensure that the equipment functioned properly and was sufficient to perform the task while minimizing exposure to personnel. In addition, the laboratory work provided the research and development effort necessary to maximize the performance of the system. Throughout this work technicians and staff who were to be involved in RGRS operation at the MSRE site worked directly with the research staff in completing the laboratory testing phase. Consequently, at the end of the laboratory work, the personnel who were to be involved in the actual operations had acquired all of the training and experience necessary to continue with the process of reactive gas removal.

  16. Crucial roles of reactive chemical species in modification of respiratory syncytial virus by nitrogen gas plasma.

    PubMed

    Sakudo, Akikazu; Toyokawa, Yoichi; Imanishi, Yuichiro; Murakami, Tomoyuki

    2017-05-01

    The exact mechanisms by which nanoparticles, especially those composed of soft materials, are modified by gas plasma remain unclear. Here, we used respiratory syncytial virus (RSV), which has a diameter of 80-350nm, as a model system to identify important factors for gas plasma modification of nanoparticles composed of soft materials. Nitrogen gas plasma, generated by applying a short high-voltage pulse using a static induction (SI) thyristor power supply produced reactive chemical species (RCS) and caused virus inactivation. The plasma treatment altered the viral genomic RNA, while treatment with a relatively low concentration of hydrogen peroxide, which is a neutral chemical species among RCS, effectively inactivated the virus. Furthermore, a zero dimensional kinetic global model of the reaction scheme during gas plasma generation identified the production of various RCS, including neutral chemical species. Our findings suggest the nitrogen gas plasma generates RCS, including neutral species that damage the viral genomic RNA, leading to virus inactivation. Thus, RCS generated by gas plasma appears to be crucial for virus inactivation, suggesting this may constitute an important factor in terms of the efficient modification of nanoparticles composed of soft materials.

  17. Gas-Phase Reactivity of Protonated 2-, 3- and 4-Dehydropyridine Radicals Toward Organic Reagents

    PubMed Central

    Adeuya, Anthony; Price, Jason M.; Jankiewicz, Bartłomiej J.; Nash, John J.; Kenttämaa, Hilkka I.

    2009-01-01

    In order to explore the effects of the electronic nature of charged phenyl radicals on their reactivity, reactions of the three distonic isomers of ndehydropyridinium cation (n = 2, 3 or 4) have been investigated in the gas phase by using Fourier-transform ion cyclotron resonance mass spectrometry. All three isomers react with cyclohexane, methanol, ethanol and 1-pentanol exclusively via hydrogen atom abstraction, and with allyl iodide mainly via iodine atom abstraction, with a reaction efficiency ordering: 2 > 3 > 4. The observed reactivity ordering correlates well with the calculated vertical electron affinities of the charged radicals (i.e., the higher the vertical electron affinity, the faster the reaction). Charged radicals 2 and 3 also react with tetrahydrofuran exclusively via hydrogen atom abstraction, but the reaction of 4 with tetrahydrofuran yields products arising from nonradical reactivity. The unusual reactivity of 4 is likely to result from the contribution of an ionized carbene-type resonance structure that facilitates nucleophilic addition to the most electrophilic carbon atom (C-4) in this charged radical. The influence of such a resonance structure on the reactivity of 2 is not obvious, and this may be due to stabilizing hydrogen-bonding interactions in the transition states for this molecule. Charged radicals 2 and 3 abstract a hydrogen atom from the substituent in both phenol and toluene, but 4 abstracts a hydrogen atom from the phenyl ring – a reaction that is unprecedented for phenyl radicals. Charged radical 4 reacts with tert-butyl isocyanide mainly by hydrogen cyanide (HCN) abstraction while CN abstraction is the principal reaction for 2 and 3. The different reactivity observed for 4 (compared to 2 and 3) is likely to result from different charge and spin distributions of the reaction intermediates for these charged radicals. PMID:19902945

  18. Application of a gas-solid fluidized bed separator for shredded municipal bulky solid waste separation.

    PubMed

    Sekito, T; Matsuto, T; Tanaka, N

    2006-01-01

    A laboratory-scale gas-solid fluidized bed separator able to separate fractions of 5.6-50mm was used for separation of shredded municipal bulky waste (SBW) into combustibles and incombustibles. In batch-scale tests, it was found that accumulation of SBW in the bottom of the bed significantly reduced the separation efficiency. In this study, stirring was shown to be effective in preventing this accumulation. Flexible sheet materials such as paper and film plastics also significantly decreased the separation efficiency. In batch-scale tests, an overall efficiency of 90% was obtained when flexible materials such as film plastics and paper were excluded from the feed SBW. In continuous feeding tests, purities of the float and sink fractions attained 95% and 86% efficiencies, respectively, with an overall efficiency of 79%. The effect of feedstock shape on separation efficiency was also investigated. This study revealed that large particles can be properly separated on the basis of density, while the shape of the material significantly influenced behavior in the fluidizing bed.

  19. The Scattering of Gas Atoms from Solid Surfaces

    ERIC Educational Resources Information Center

    Walton, Alan J.

    1977-01-01

    Traditional undergraduate courses in gas kinetic theory encourage the view that in all collisions between a gas atom and a surface, the angle of incidence of the gas atom equals its angle of reflection. This article illustrates and explains the incorrectness in assuming specular reflection and zero dwell time. (Author/MA)

  20. THE IMPACT OF MUNICIPAL SOLID WASTE MANAGEMENT ON GREENHOUSE GAS EMISSIONS IN THE UNITED STATES

    EPA Science Inventory

    Technological advancements in United States (U.S.) municipal solid waste (MSW) disposal and a focus on the environmental advantages of integrated MSW management have greatly reduced the environmental impacts of MSW management, including greenhouse gas (GHG) emissions. This study ...

  1. DETERMINATION OF CHLOROETHENES IN ENVIRONMENTAL BIOLOGICAL SAMPLES USING GAS CHROMATOGRAPHY COUPLED WITH SOLID PHASE MICRO EXTRACTION

    EPA Science Inventory

    An analytical method has been developed to determine the chloroethene series, tetrachloroethene (PCE), trichloroethene (TCE),cisdichloroethene (cis-DCE) andtransdichloroethene (trans-DCE) in environmental biotreatment studies using gas chromatography coupled with a solid phase mi...

  2. Gas-liquid interfacial plasmas producing reactive species for cell membrane permeabilization

    PubMed Central

    Kaneko, Toshiro; Sasaki, Shota; Takashima, Keisuke; Kanzaki, Makoto

    2017-01-01

    Gas-liquid interfacial atmospheric-pressure plasma jets (GLI-APPJ) are used medically for plasma-induced cell-membrane permeabilization. In an attempt to identify the dominant factors induced by GLI-APPJ responsible for enhancing cell-membrane permeability, the concentration and distribution of plasma-produced reactive species in the gas and liquid phase regions are measured. These reactive species are classified in terms of their life-span: long-lived (e.g., H2O2), short-lived (e.g., O2•−), and extremely-short-lived (e.g., •OH). The concentration of plasma-produced •OHaq in the liquid phase region decreases with an increase in solution thickness (<1 mm), and plasma-induced cell-membrane permeabilization is found to decay markedly as the thickness of the solution increases. Furthermore, the horizontally center-localized distribution of •OHaq, resulting from the center-peaked distribution of •OH in the gas phase region, corresponds with the distribution of the permeabilized cells upon APPJ irradiation, whereas the overall plasma-produced oxidizing species such as H2O2aq in solution exhibit a doughnut-shaped horizontal distribution. These results suggest that •OHaq is likely one of the dominant factors responsible for plasma-induced cell-membrane permeabilization. PMID:28163376

  3. Acoustic probe for solid-gas-liquid suspensions. 1998 annual progress report

    SciTech Connect

    Tavlarides, L.L.; Sangani, A.S.; Greenwood, M.S.

    1998-06-01

    'The proposed research will develop an acoustic probe for monitoring particle size and volume fraction in slurries in the absence and presence of gas. The goals are to commission and verify the probe components and system operation, develop theory for the forward and inverse problems for acoustic wave propagation through a three phase medium, and experimentally verify the theoretical analysis. The acoustic probe will permit measurement of solid content in gas-liquid-solid waste slurries in tanks across the DOE complex.'

  4. Predicting second gas-solid virial coefficients using calculated molecular properties on various carbon surfaces.

    PubMed

    Rybolt, Thomas R; Janeksela, Vanessa E; Hooper, Dana N; Thomas, Howard E; Carrington, Nathan A; Williamson, Eric J

    2004-04-01

    Gas-solid chromatography was used to obtain values of the second gas-solid virial coefficient, B2s, in the temperature range from 343 to 493 K for seven adsorbate gases: methane, ethane, propane, chloromethane, chlorodifluoromethane, dimethyl ether, and sulfur hexafluoride. Carboxen-1000, a 1200 m2/g carbon molecular sieve (Supelco Inc.), was used as the adsorbent. These data were combined with earlier work to make a combined data set of 36 different adsorbate gases variously interacting with from one to four different carbon surfaces. All B2s values were extrapolated to 403 K to create a set of 65 different gas-solid B2s values at a fixed temperature. The B2s value for a given gas-solid system can be converted to a chromatographic retention time at any desired flow rate and can be converted to the amount of gas adsorbed at any pressure in the low-coverage, Henry's law region. Beginning with a theoretical equation for the second gas-solid virial coefficient, various quantitative structure retention relations (QSRR) were developed and used to correlate the B2s values for different gas adsorbates with different carbon surfaces. Two calculated adsorbate molecular parameters (molar refractivity and connectivity index), when combined with two adsorbent parameters (surface area and a surface energy contribution to the gas-solid interaction), provided an effective correlation (r2 = 0.952) of the 65 different B2s values. The two surface parameters provided a simple yet useful representation of the structure and energy of the carbon surfaces and thus our correlations considered variation in both the adsorbate gas and the adsorbent solid.

  5. DEVELOPMENT OF LOW-DIFFUSION FLUX-SPLITTING METHODS FOR DENSE GAS-SOLID FLOWS

    EPA Science Inventory

    The development of a class of low-diffusion upwinding methods for computing dense gas-solid flows is presented in this work. An artificial compressibility/low-Mach preconditioning strategy is developed for a hyperbolic two-phase flow equation system consisting of separate solids ...

  6. Fundamental equations of a mixture of gas and small spherical solid particles from simple kinetic theory.

    NASA Technical Reports Server (NTRS)

    Pai, S. I.

    1973-01-01

    The fundamental equations of a mixture of a gas and pseudofluid of small spherical solid particles are derived from the Boltzmann equation of two-fluid theory. The distribution function of the gas molecules is defined in the same manner as in the ordinary kinetic theory of gases, but the distribution function for the solid particles is different from that of the gas molecules, because it is necessary to take into account the different size and physical properties of solid particles. In the proposed simple kinetic theory, two additional parameters are introduced: one is the radius of the spheres and the other is the instantaneous temperature of the solid particles in the distribution of the solid particles. The Boltzmann equation for each species of the mixture is formally written, and the transfer equations of these Boltzmann equations are derived and compared to the well-known fundamental equations of the mixture of a gas and small solid particles from continuum theory. The equations obtained reveal some insight into various terms in the fundamental equations. For instance, the partial pressure of the pseudofluid of solid particles is not negligible if the volume fraction of solid particles is not negligible as in the case of lunar ash flow.

  7. Bio-inspired solid phase extraction sorbent material for cocaine: a cross reactivity study.

    PubMed

    Montesano, Camilla; Sergi, Manuel; Perez, German; Curini, Roberta; Compagnone, Dario; Mascini, Marcello

    2014-12-01

    The binding specificity of a bio-inspired hexapeptide (QHWWDW) versus cocaine and four other drugs such as 3,4-methylenedioxy-N-methylamphetamine (MDMA), 3,4-methylenedioxy-N-ethylamphetamine (MDEA), phencyclidine and morphine was computationally studied and then experimentally confirmed in solid phase extraction (SPE) followed by liquid chromatography-mass spectrometry (LC/MS) detection. In simulation, the hexapeptide-drug complexes were docked with different scoring functions and considering pH chemical environment. In experimental, the cross reactivity of the selected hexapeptide was tested as SPE sorbent versus cocaine and other four drugs using buffer solutions at pH 4 and 7. Significant differences in specific retention were found between cocaine (97% of recovery) and both morphine (45% of recovery) and phencyclidine (60% of recovery), but less for ecstasies (average recovery 69%). In agreement with docking simulation, the hexapeptide showed the highest recovery with best specificity versus cocaine at pH 7 with an experimentally binding constant of 2.9 × 10(6)M(-1). The bio-inspired sorbent material analytical performances were compared with a commercial reversed phase cartridge confirming the hexapeptide specificity to cocaine and validating simulated data.

  8. Open-source MFIX-DEM software for gas-solids flows: Part I verification studies

    SciTech Connect

    Garg, Rahul; Galvin, Janine; Li, Tingwen; Pannala, Sreekanth

    2012-01-01

    With rapid advancements in computer hardware, it is now possible to perform large simulations of granular flows using the Discrete Element Method (DEM). As a result, solids are increasingly treated in a discrete Lagrangian fashion in the gas solids flow community. In this paper, the open-source MFIX-DEM software is described that can be used for simulating the gas solids flow using an Eulerian reference frame for the continuum fluid and a Lagrangian discrete framework (Discrete Element Method) for the particles. This method is referred to as the continuum discrete method (CDM) to clearly make a distinction between the ambiguity of using a Lagrangian or Eulerian reference for either continuum or discrete formulations. This freely available CDM code for gas solids flows can accelerate the research in computational gas solids flows and establish a baseline that can lead to better closures for the continuum modeling (or traditionally referred to as two fluid model) of gas solids flows. In this paper, a series of verification cases is employed which tests the different aspects of the code in a systematic fashion by exploring specific physics in gas solids flows before exercising the fully coupled solution on simple canonical problems. It is critical to have an extensively verified code as the physics is complex with highly-nonlinear coupling, and it is difficult to ascertain the accuracy of the results without rigorous verification. These series of verification tests set the stage not only for rigorous validation studies (performed in part II of this paper) but also serve as a procedure for testing any new developments that couple continuum and discrete formulations for gas solids flows.

  9. Gas-phase reactivity of [Ca(formamide)](2+) complex: an example of different dynamical behaviours.

    PubMed

    Martin-Somer, Ana; Spezia, Riccardo; Yáñez, Manuel

    2017-04-28

    In the present contribution, we have summarized our recent work on the comprehension of [Ca(formamide)](2+) complex gas-phase unimolecular dissociation. By using different theoretical approaches, we were able to revise the original (and typical for such kind of problems) understanding given in terms of stationary points on the potential energy surface, which did not provide a satisfactory explanation of the experimentally observed reactivity. In particular, we point out how non-statistical and non-intrinsic reaction coordinate mechanisms are of fundamental importance.This article is part of the themed issue 'Theoretical and computational studies of non-equilibrium and non-statistical dynamics in the gas phase, in the condensed phase and at interfaces'.

  10. Greenhouse gas emission from soil amended with biochar made from hydrothermally carbonizing swine solids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biochar made from hydrothermally carbonizing swine solids was mixed with a 50/50 mixture of Norfolk Ap and E horizon at a rate of 20 g/kg. During the incubation period of 54 days, greenhouse gas (CO2 and N2O) emission fluxes were calculated by nonlinearly regressing time-series headspace gas concent...

  11. Reactivity and analytical performance of oxygen as cell gas in inductively coupled plasma tandem mass spectrometry

    NASA Astrophysics Data System (ADS)

    Virgilio, Alex; Amais, Renata S.; Amaral, Clarice D. B.; Fialho, Lucimar L.; Schiavo, Daniela; Nóbrega, Joaquim A.

    2016-12-01

    The reactivity and analytical performance of O2 as cell gas in inductively coupled plasma tandem mass spectrometry was investigated. Selected analytes in a wide mass range were divided in three groups according to their reactivity: G1 represents elements with high oxygen affinity (Ce, La, P, Sc, Ti, and Y), G2 contains elements that may partially react with oxygen (As, Ba, Mo, Si, Sr, and V), and G3 comprises elements expected to be less reactive towards oxygen (Al, Bi, Cu, Mg, Pb, and Pd). On-mass and mass-shift modes were evaluated by monitoring atomic and metal oxide ions, respectively. Analytical signal profiles, oxide percentages, sensitivities and limits of detection for oxygen flow rates varying from 0.1 to 1.0 mL min- 1 were also studied. Group 1 elements plus As and V presented better sensitivities and LODs when measuring oxides, which were the major species for all flow rates evaluated. Molybdenum and Si oxides presented intermediate behavior and MoO fraction was up to 47% and limit of detection was the same as that obtained in on-mass mode. For others G2 and G3 elements, on-mass mode presented higher sensitivity and better LODs, with estimated oxide contents lower than 10%. In most cases, increasing oxygen flow rates led to lower sensitivities and worse LODs.

  12. Rapid hydrogen gas generation using reactive thermal decomposition of uranium hydride.

    SciTech Connect

    Kanouff, Michael P.; Van Blarigan, Peter; Robinson, David B.; Shugard, Andrew D.; Gharagozloo, Patricia E.; Buffleben, George M.; James, Scott Carlton; Mills, Bernice E.

    2011-09-01

    Oxygen gas injection has been studied as one method for rapidly generating hydrogen gas from a uranium hydride storage system. Small scale reactors, 2.9 g UH{sub 3}, were used to study the process experimentally. Complimentary numerical simulations were used to better characterize and understand the strongly coupled chemical and thermal transport processes controlling hydrogen gas liberation. The results indicate that UH{sub 3} and O{sub 2} are sufficiently reactive to enable a well designed system to release gram quantities of hydrogen in {approx} 2 seconds over a broad temperature range. The major system-design challenge appears to be heat management. In addition to the oxidation tests, H/D isotope exchange experiments were performed. The rate limiting step in the overall gas-to-particle exchange process was found to be hydrogen diffusion in the {approx}0.5 {mu}m hydride particles. The experiments generated a set of high quality experimental data; from which effective intra-particle diffusion coefficients can be inferred.

  13. Evolution of gas-filled nanocracks in crystalline solids.

    PubMed

    Hartmann, M; Trinkaus, H

    2002-02-04

    In this work, the evolution of gas-filled cracks under gas implantation and subsequent annealing is studied on the basis of an elastic continuum approach. The observed growth limitation of He-filled nanocracks in SiC is attributed to their stabilization by the formation of circular dislocation dipoles. The formation and Ostwald ripening of bubble-loop complexes at elevated temperatures is modeled in terms of gas atom exchange between such complexes coupled with local matrix atom exchange between bubbles and loops of the same complex. The scaling laws derived for the time dependence of bubble and loop sizes are found to be in good agreement with experimental data.

  14. Method and apparatus for the separation of a gas-solids mixture in a circulating fluidized bed reactor

    DOEpatents

    Vimalchand, Pannalal; Liu, Guohai; Peng, WanWang

    2010-08-10

    The system of the present invention includes a centripetal cyclone for separating particulate material from a particulate laden gas solids stream. The cyclone includes a housing defining a conduit extending between an upstream inlet and a downstream outlet. In operation, when a particulate laden gas-solids stream passes through the upstream housing inlet, the particulate laden gas-solids stream is directed through the conduit and at least a portion of the solids in the particulate laden gas-solids stream are subjected to a centripetal force within the conduit.

  15. Diesel-related hydrocarbons can dominate gas phase reactive carbon in megacities

    NASA Astrophysics Data System (ADS)

    Dunmore, R. E.; Hopkins, J. R.; Lidster, R. T.; Lee, J. D.; Evans, M. J.; Rickard, A. R.; Lewis, A. C.; Hamilton, J. F.

    2015-03-01

    Hydrocarbons are key precursors to two priority air pollutants, ozone and particulate matter. Those with two to seven carbons have historically been straightforward to observe and have been successfully reduced in many developed cities through air quality policy interventions. Longer chain hydrocarbons released from diesel vehicles are not considered explicitly as part of air quality strategies and there are few direct measurements of their gaseous abundance in the atmosphere. This study describes the chemically comprehensive and continuous measurements of organic compounds in a developed megacity (London), which demonstrate that on a seasonal median basis, diesel-related hydrocarbons represent only 20-30% of the total hydrocarbon mixing ratio but comprise more than 50% of the atmospheric hydrocarbon mass and are a dominant local source of secondary organic aerosols. This study shows for the first time that, 60% of the winter primary hydrocarbon hydroxyl radical reactivity is from diesel-related hydrocarbons and using the maximum incremental reactivity scale, we predict that they contribute up to 50% of the ozone production potential in London. Comparing real-world urban composition with regulatory emissions inventories in the UK and US highlights a previously unaccounted for but, very significant under-reporting of diesel related hydrocarbons; an underestimation of a factor ~ 4 for C9 species rising to a factor of over 70 for C12 during winter. These observations show that hydrocarbons from diesel vehicles can dominate gas phase reactive carbon in cities with high diesel fleet fractions. Future control of urban particulate matter and ozone in such locations requires a shift in policy focus onto gas phase hydrocarbons released from diesels as this vehicle type continues to displace gasoline world-wide.

  16. Diesel-related hydrocarbons can dominate gas phase reactive carbon in megacities

    NASA Astrophysics Data System (ADS)

    Dunmore, R. E.; Hopkins, J. R.; Lidster, R. T.; Lee, J. D.; Evans, M. J.; Rickard, A. R.; Lewis, A. C.; Hamilton, J. F.

    2015-09-01

    Hydrocarbons are key precursors to two priority air pollutants, ozone and particulate matter. Those with two to seven carbons have historically been straightforward to observe and have been successfully reduced in many developed cities through air quality policy interventions. Longer chain hydrocarbons released from diesel vehicles are not considered explicitly as part of air quality strategies and there are few direct measurements of their gaseous abundance in the atmosphere. This study describes the chemically comprehensive and continuous measurements of organic compounds in a developed megacity (London), which demonstrate that on a seasonal median basis, diesel-related hydrocarbons represent only 20-30 % of the total hydrocarbon mixing ratio but comprise more than 50 % of the atmospheric hydrocarbon mass and are a dominant local source of secondary organic aerosols. This study shows for the first time that 60 % of the winter primary hydrocarbon hydroxyl radical reactivity is from diesel-related hydrocarbons and using the maximum incremental reactivity scale, we predict that they contribute up to 50 % of the ozone production potential in London. Comparing real-world urban composition with regulatory emissions inventories in the UK and US highlights a previously unaccounted for, but very significant, under-reporting of diesel-related hydrocarbons; an underestimation of a factor ~4 for C9 species rising to a factor of over 70 for C12 during winter. These observations show that hydrocarbons from diesel vehicles can dominate gas phase reactive carbon in cities with high diesel fleet fractions. Future control of urban particulate matter and ozone in such locations requires a shift in policy focus onto gas phase hydrocarbons released from diesels as this vehicle type continues to displace gasoline world-wide.

  17. CFD methods for the reduction of reactive gas emission from a paper laminating machine.

    PubMed

    Horvath, Andras; Jordan, Christian; Forstner, Gerhard; Altacher, Peter; Harasek, Michael

    2007-06-18

    In cooperation with the world's second largest manufacturer of beverage cartons (SIG Combibloc) for liquid foodstuffs an innovative off-take for neutralisation of reactive gas in a paper laminating machine was constructed. A great challenge during engineering work was ensuring a high concentration of the reactive gas where needed and at the same time minimising work place impact in a machine basically without housing. Preliminary 2D-models of the machine geometry proved to be insufficient in describing all the governing flow phenomena. A simplified 3D-geometry containing all important parts of the complex machinery was necessary for accurate predictions. It was found that the driving force of air movement and transport of reactive gas (which acts as an adhesive agent) from the reaction zone in the interior of the laminating machine to the outside is a boundary flow caused by the rapid movement of carton material and rotating cylinders. A physically correct simulation result of the boundary flow is a premise for correct prediction of air flow in and around the machinery. Lacking experimental data (due to an inaccessible geometry) a worst case scenario was constructed by generating a grid and using turbulence models that maximised mass transport in the boundary layer region and thus emission of (tracer)gas from the machine. CFD simulations were done using the geometry preprocessor Gambit, and the finite volume solver Fluent. The results of the analysis of the emission paths from the machine were surprising and led to the construction of an effective off-take relatively far away from the emission source. The chosen position ensures low disturbance of highly sensitive flow patterns inside the machine and diffusive mixing, dilution and contamination of the surroundings. The effect of the new off-take is an immediate and significant rise in air quality in the vicinity of the laminating machine and ensures maximum allowed concentration in the plant area. The product

  18. Ion-induced chemistry in condensed gas solids

    NASA Astrophysics Data System (ADS)

    Boring, J. W.; Johnson, R. E.; Reimann, C. T.; Garret, J. W.; Brown, W. L.; Marcantonio, K. J.

    1983-12-01

    Solids of H 2O, D 2O, CO 2, and SO 2 have been bombarded by MeV and keV ions, and the sputtering of these materials investigated by measuring the total yield and the mass and energy spectra of ejected particles. One observes the results of considerable chemical activity in these low temperature solids. With MeV ions incident on D 2O and CO 2, the production of D 2, O 2 and CO, O 2 respectively are found, while keV ions on SO 2 produce SO, SO 3 and O 2.

  19. ENVIRONMENTAL REACTIVITY OF SOLID-STATE HYDROGEN SYSTEMS: FUNDAMENTAL TESTING AND EVALUATION

    SciTech Connect

    James, C.; Cortes-Concepcion., J; Anton, D.; Tamburello, D.

    2010-12-13

    In order to enable the commercial acceptance of solid state hydrogen storage materials and systems it is important to understand the risks associated with the environmental exposure of various materials. In some instances, these materials are sensitive to the environment surrounding the material and the behavior is unique and independent to each material. The development of testing procedures to evaluate a material's behavior with different environmental exposures is a critical need. In some cases material modifications may be needed in order to reduce the risk of environmental exposure. We have redesigned two standardized UN tests for clarity and exactness; the burn rate and self-heating tests. The results of these and other UN tests are shown for ammonia borane, NH{sub 3}BH{sub 3}, and alane, AlH{sub 3}. The burn rate test showed a strong dependence on the preparation method of aluminum hydride as the particle size and trace amounts of solvent greatly influence the test results. The self-heating test for ammonia borane showed a failed test as low as 70 C in a modified cylindrical form. Finally, gas phase calorimetry was performed and resulted in an exothermic behavior within an air and 30%RH environment.

  20. Assessment of alternative disposal methods to reduce greenhouse gas emissions from municipal solid waste in India.

    PubMed

    Yedla, Sudhakar; Sindhu, N T

    2016-06-01

    Open dumping, the most commonly practiced method of solid waste disposal in Indian cities, creates serious environment and economic challenges, and also contributes significantly to greenhouse gas emissions. The present article attempts to analyse and identify economically effective ways to reduce greenhouse gas emissions from municipal solid waste. The article looks at the selection of appropriate methods for the control of methane emissions. Multivariate functional models are presented, based on theoretical considerations as well as the field measurements to forecast the greenhouse gas mitigation potential for all the methodologies under consideration. Economic feasibility is tested by calculating the unit cost of waste disposal for the respective disposal process. The purpose-built landfill system proposed by Yedla and Parikh has shown promise in controlling greenhouse gas and saving land. However, these studies show that aerobic composting offers the optimal method, both in terms of controlling greenhouse gas emissions and reducing costs, mainly by requiring less land than other methods.

  1. Numerical solution of moving boundary problem for deposition process in solid fuel gas generator

    NASA Astrophysics Data System (ADS)

    Volokhov, V. M.; Dorofeenko, S. O.; Sharov, M. S.; Toktaliev, P. D.

    2016-11-01

    Moving boundary problem in application to process of depositions formation in gas generator are considered. Gas generator, as a part of fuel preparation system of high-speed vehicle, convert solid fuel into multicomponent multiphase mixture, which further burned down in combustion chamber. Mathematical model of two-phase “gas-solid particles” flow, including Navier-Stokes equations for turbulent flow in gas generator and mass, impulse conservations laws for elementary depositions layer are proposed. Verification of proposed mathematical model for depositions mass in gas generator conditions is done. Further possible improvements of proposed model, based on more detail accounting of particle-wall interaction and wall's surface adhesion properties are analyzed.

  2. An effusive molecular beam technique for studies of polyatomic gas-surface reactivity and energy transfer.

    PubMed

    Cushing, G W; Navin, J K; Valadez, L; Johánek, V; Harrison, I

    2011-04-01

    An effusive molecular beam technique is described to measure alkane dissociative sticking coefficients, S(T(g), T(s); ϑ), on metal surfaces for which the impinging gas temperature, T(g), and surface temperature, T(s), can be independently varied, along with the angle of incidence, ϑ, of the impinging gas. Effusive beam experiments with T(g) = T(s) = T allow for determination of angle-resolved dissociative sticking coefficients, S(T; ϑ), which when averaged over the cos (ϑ)/π angular distribution appropriate to the impinging flux from a thermal ambient gas yield the thermal dissociative sticking coefficient, S(T). Nonequilibrium S(T(g), T(s); ϑ) measurements for which T(g) ≠ T(s) provide additional opportunities to characterize the transition state and gas-surface energy transfer at reactive energies. A resistively heated effusive molecular beam doser controls the T(g) of the impinging gas striking the surface. The flux of molecules striking the surface from the effusive beam is determined from knowledge of the dosing geometry, chamber pressure, and pumping speed. Separate experiments with a calibrated leak serve to fix the chamber pumping speed. Postdosing Auger electron spectroscopy is used to measure the carbon of the alkyl radical reaction product that is deposited on the surface as a result of alkane dissociative sticking. As implemented in a typical ultrahigh vacuum chamber for surface analysis, the technique has provided access to a dynamic range of roughly 6 orders of magnitude in the initial dissociative sticking coefficient for small alkanes on Pt(111).

  3. Evaluation of the validity of the UN SADT H.4 test for solid organic peroxides and self-reactive substances.

    PubMed

    Steensma, M; Schuurman, P; Malow, M; Krause, U; Wehrstedt, K-D

    2005-01-31

    Many self-accelerating decomposition temperatures (SADTs) of solid organic peroxides and self-reactive substances have been determined with the UN test method H.4, which is a scaled down test in a small Dewar vessel. For solid organic peroxides and solid self-reactive substances Fierz has questioned this procedure in a recent paper. Fierz concluded that the Dewar test results should not be extrapolated to beyond 8l packages, owing to the thermal insulation value of solids. On the other hand, long term experience with the test, with a great variety of solid organic peroxides and self-reactive substances show about equal critical temperatures in the small Dewar vessel and on 50 kg scale. In the present work, we first checked, by numerical simulations, the Dewar scale versus the larger scale, in a way comparable with Fierz' method: both scales are simulated by spheres, consisting of a number of annular layers, for the large scale the usual external heat loss term is used but for the small scale the outside heat transfer is strongly limited. The outcome of these simulations, covering a variety of physical parameters, supports the concerns expressed by Fierz. After this, we performed accurate cooling and heating experiments with solid organic peroxide in the usual Dewar vessel, provided with a large set of thermocouples. The results of these experiments showed that the simulation model for the Dewar vessel has to be changed from a spherical analogue to a short cylinder of solid material with heat exchange mainly via its top (U(top) approximately 3.5 W/(m(2)K), overall heat transfer coefficient) and some heat exchange (U(side) approximately 0.29 W/(m(2)K)) through its cylindrical and bottom part. With this "modified cylinder" model (being neither an infinitely long cylinder nor a slab) of the Dewar vessel, we found that the UN method H.4 enables an accurate prediction of the SADT, with small deviations of 0+/-2.5 degrees C. Further, by performing a truly three

  4. Molecular engineering of Schiff-base linked covalent polymers with diverse topologies by gas-solid interface reaction.

    PubMed

    Liu, Xuan-He; Guan, Cui-Zhong; Zheng, Qing-Na; Wang, Dong; Wan, Li-Jun

    2015-03-14

    The design and construction of molecular nanostructures with tunable topological structures are great challenges in molecular nanotechnology. Herein, we demonstrate the molecular engineering of Schiff-base bond connected molecular nanostructures. Building module construction has been adopted to modulate the symmetry of resulted one dimensional (1D) and two dimensional (2D) polymers. Specifically, we have designed and constructed 1D linear and zigzag polymers, 2D hexagonal and chessboard molecular nanostructures by varying the number of reactive sites and geometry and symmetry of precursors. It is demonstrated that high-quality conjugated polymers can be fabricated by using gas-solid interface reaction. The on-demanding synthesis of polymeric architectures with diverse topologies paves the way to fabricate molecular miniature devices with various desired functionalities.

  5. Rapid Carbonation for Calcite from a Solid-Liquid-Gas System with an Imidazolium-Based Ionic Liquid

    PubMed Central

    Ibrahim, Abdul-Rauf; Vuningoma, Jean Bosco; Huang, Yan; Wang, Hongtao; Li, Jun

    2014-01-01

    Aqueous carbonation of Ca(OH)2 is a complex process that produces calcite with scalenohedral calcite phases and characterized by inadequate carbonate species for effective carbonation due to the poor dissolution of CO2 in water. Consequently, we report a solid-liquid-gas carbonation system with an ionic liquid (IL), 1-butyl-3-methylimidazolium bromide, in view of enhancing the reaction of CO2 with Ca(OH)2. The use of the IL increased the solubility of CO2 in the aqueous environment and enhanced the transport of the reactive species (Ca2+ and CO32−) and products. The presence of the IL also avoided the formation of the CaCO3 protective and passivation layer and ensured high carbonation yields, as well as the production of stoichiometric rhombohedral calcite phases in a short time. PMID:24968273

  6. Pore-Scale Geochemical Reactivity Associated with CO2 Storage: New Frontiers at the Fluid-Solid Interface.

    PubMed

    Noiriel, Catherine; Daval, Damien

    2017-03-31

    The reactivity of carbonate and silicate minerals is at the heart of porosity and pore geometry changes in rocks injected with CO2, which ultimately control the evolution of flow and transport properties of fluids in porous and/or fractured geological reservoirs. Modeling the dynamics of CO2-water-rock interactions is challenging because of the resulting large geochemical disequilibrium, the reservoir heterogeneities, and the large space and time scales involved in the processes. In particular, there is a lack of information about how the macroscopic properties of a reservoir, e.g., the permeability, will evolve as a result of geochemical reactions at the molecular scale. Addressing this point requires a fundamental understanding of how the microstructures influence the macroscopic properties of rocks. The pore scale, which ranges from a few nanometers to centimeters, has stood out as an essential scale of observation of geochemical processes in rocks. Transport or surface reactivity limitations due to the pore space architecture, for instance, are best described at the pore scale itself. It can be also considered as a mesoscale for aggregating and increasing the gain of fundamental understanding of microscopic interfacial processes. Here we focus on the potential application of a combination of physicochemical measurements coupled with nanoscale and microscale imaging techniques during laboratory experiments to improve our understanding of the physicochemical mechanisms that occur at the fluid-solid interface and the dynamics of the coupling between the geochemical reactions and flow and transport modifications at the pore scale. Imaging techniques such as atomic force microscopy, vertical scanning interferometry, focused ion beam transmission electron microscopy, and X-ray microtomography, are ideal for investigating the reactivity dynamics of these complex materials. Minerals and mineral assemblages, i.e., rocks, exhibit heterogeneous and anisotropic reactivity

  7. Accommodative Behavior of Non-porous Molecular crystal at Solid-Gas and Solid-Liquid Interface

    PubMed Central

    Mande, Hemant M.; Ghalsasi, Prasanna S.

    2015-01-01

    Molecular crystals demonstrate drastically different behavior in solid and liquid state, mainly due to their difference in structural frameworks. Therefore, designing of unique structured molecular compound which can work at both these interfaces has been a challenge. Here, we present remarkable ‘molecular’ property by non-porous molecular solid crystal, dinuclear copper complex (C6H5CH(X)NH2)2CuCl2, to reversibly ‘adsorb’ HCl gas at solid-gas interface as well as ‘accommodate’ azide anion at solid-liquid interface with crystal to crystal transformation. The latter process is driven by molecular recognition, self-assembly, and anchimeric assistance. The observed transformations are feasible due to breathing of inner and outer coordination sphere around metal center resulting in change in metal polyhedra for ‘accommodating’ guest molecule. These transformations cause changes in optical, magnetic, and/or ferroelectric property offering diversity in ‘sensing’ application. With the proposed underlying principles in these exceptional reversible and cyclic transformations, we prepared a series of compounds, can facilitate designing of novel multifunctional molecular materials. PMID:26411980

  8. Communication: H-atom reactivity as a function of temperature in solid parahydrogen: The H + N2O reaction.

    PubMed

    Mutunga, Fredrick M; Follett, Shelby E; Anderson, David T

    2013-10-21

    We present low temperature kinetic measurements for the H + N2O association reaction in solid parahydrogen (pH2) at liquid helium temperatures (1-5 K). We synthesize (15)N2(18)O doped pH2 solids via rapid vapor deposition onto an optical substrate attached to the cold tip of a liquid helium bath cryostat. We then subject the solids to short duration 193 nm irradiations to generate H-atoms produced as byproducts of the in situ N2O photodissociation, and monitor the subsequent reaction kinetics using rapid scan FTIR. For reactions initiated in solid pH2 at 4.3 K we observe little to no reaction; however, if we then slowly reduce the temperature of the solid we observe an abrupt onset to the H + N2O → cis-HNNO reaction at temperatures below 2.4 K. This abrupt change in the reaction kinetics is fully reversible as the temperature of the solid pH2 is repeatedly cycled. We speculate that the observed non-Arrhenius behavior (negative activation energy) is related to the stability of the pre-reactive complex between the H-atom and (15)N2(18)O reagents.

  9. Investigating the role of gas bubble formation and entrapment in contaminated aquifers: Reactive transport modelling

    NASA Astrophysics Data System (ADS)

    Amos, Richard T.; Ulrich Mayer, K.

    2006-09-01

    In many natural and contaminated aquifers, geochemical processes result in the production or consumption of dissolved gases. In cases where methanogenesis or denitrification occurs, the production of gases may result in the formation and growth of gas bubbles below the water table. Near the water table, entrapment of atmospheric gases during water table rise may provide a significant source of O 2 to waters otherwise depleted in O 2. Furthermore, the presence of bubbles will affect the hydraulic conductivity of an aquifer, resulting in changes to the groundwater flow regime. The interactions between physical transport, biogeochemical processes, and gas bubble formation, entrapment and release is complex and requires suitable analysis tools. The objective of the present work is the development of a numerical model capable of quantitatively assessing these processes. The multicomponent reactive transport code MIN3P has been enhanced to simulate bubble growth and contraction due to in-situ gas production or consumption, bubble entrapment due to water table rise and subsequent re-equilibration of the bubble with ambient groundwater, and permeability changes due to trapped gas phase saturation. The resulting formulation allows for the investigation of complex geochemical systems where microbially mediated redox reactions both produce and consume gases as well as affect solution chemistry, alkalinity, and pH. The enhanced model has been used to simulate processes in a petroleum hydrocarbon contaminated aquifer where methanogenesis is an important redox process. The simulations are constrained by data from a crude oil spill site near Bemidji, MN. Our results suggest that permeability reduction in the methanogenic zone due to in-situ formation of gas bubbles, and dissolution of entrapped atmospheric bubbles near the water table, both work to attenuate the dissolved gas plume emanating from the source zone. Furthermore, the simulations demonstrate that under the given

  10. Investigating the role of gas bubble formation and entrapment in contaminated aquifers: Reactive transport modelling

    USGS Publications Warehouse

    Amos, Richard T.; Mayer, K. Ulrich

    2006-01-01

    In many natural and contaminated aquifers, geochemical processes result in the production or consumption of dissolved gases. In cases where methanogenesis or denitrification occurs, the production of gases may result in the formation and growth of gas bubbles below the water table. Near the water table, entrapment of atmospheric gases during water table rise may provide a significant source of O2 to waters otherwise depleted in O2. Furthermore, the presence of bubbles will affect the hydraulic conductivity of an aquifer, resulting in changes to the groundwater flow regime. The interactions between physical transport, biogeochemical processes, and gas bubble formation, entrapment and release is complex and requires suitable analysis tools. The objective of the present work is the development of a numerical model capable of quantitatively assessing these processes. The multicomponent reactive transport code MIN3P has been enhanced to simulate bubble growth and contraction due to in-situ gas production or consumption, bubble entrapment due to water table rise and subsequent re-equilibration of the bubble with ambient groundwater, and permeability changes due to trapped gas phase saturation. The resulting formulation allows for the investigation of complex geochemical systems where microbially mediated redox reactions both produce and consume gases as well as affect solution chemistry, alkalinity, and pH. The enhanced model has been used to simulate processes in a petroleum hydrocarbon contaminated aquifer where methanogenesis is an important redox process. The simulations are constrained by data from a crude oil spill site near Bemidji, MN. Our results suggest that permeability reduction in the methanogenic zone due to in-situ formation of gas bubbles, and dissolution of entrapped atmospheric bubbles near the water table, both work to attenuate the dissolved gas plume emanating from the source zone. Furthermore, the simulations demonstrate that under the given

  11. Evaluation of wall boundary condition parameters for gas-solids fluidized bed simulations

    SciTech Connect

    Li, Tingwen; Benyahia, Sofiane

    2013-10-01

    Wall boundary conditions for the solids phase have significant effects on numerical predictions of various gas-solids fluidized beds. Several models for the granular flow wall boundary condition are available in the open literature for numerical modeling of gas-solids flow. In this study, a model for specularity coefficient used in Johnson and Jackson boundary conditions by Li and Benyahia (AIChE Journal, 2012, 58, 2058-2068) is implemented in the open-source CFD code-MFIX. The variable specularity coefficient model provides a physical way to calculate the specularity coefficient needed by the partial-slip boundary conditions for the solids phase. Through a series of 2-D numerical simulations of bubbling fluidized bed and circulating fluidized bed riser, the model predicts qualitatively consistent trends to the previous studies. Furthermore, a quantitative comparison is conducted between numerical results of variable and constant specularity coefficients to investigate the effect of spatial and temporal variations in specularity coefficient.

  12. Effects of gas periodic stimulation on key enzyme activity in gas double-dynamic solid state fermentation (GDD-SSF).

    PubMed

    Chen, Hongzhang; Shao, Meixue; Li, Hongqiang

    2014-03-05

    The heat and mass transfer have been proved to be the important factors in air pressure pulsation for cellulase production. However, as process of enzyme secretion, the cellulase formation has not been studied in the view of microorganism metabolism and metabolic key enzyme activity under air pressure pulsation condition. Two fermentation methods in ATPase activity, cellulase productivity, weight lose rate and membrane permeability were systematically compared. Results indicated that gas double-dynamic solid state fermentation had no obviously effect on cell membrane permeability. However, the relation between ATPase activity and weight loss rate was linearly dependent with r=0.9784. Meanwhile, the results also implied that gas periodic stimulation had apparently strengthened microbial metabolism through increasing ATPase activity during gas double-dynamic solid state fermentation, resulting in motivating the production of cellulase by Trichoderma reesei YG3. Therefore, the increase of ATPase activity would be another crucial factor to strengthen fermentation process for cellulase production under gas double-dynamic solid state fermentation.

  13. Reactive gas pulsing sputtering process, a promising technique to elaborate silicon oxynitride multilayer nanometric antireflective coatings

    NASA Astrophysics Data System (ADS)

    Farhaoui, A.; Bousquet, A.; Smaali, R.; Moreau, A.; Centeno, E.; Cellier, J.; Bernard, C.; Rapegno, R.; Réveret, F.; Tomasella, E.

    2017-01-01

    The oxynitride materials present a high versatility, which enables their properties to be controlled by tuning their elemental composition. This is the case for silicon oxynitrides used for multilayer antireflective coatings (ARCs), where several thin films with various refractive indexes are needed. Different techniques allow for the modification of the thin film composition. In this paper, we investigate the reactive gas pulsing sputtering process to easily tune the thin film composition, from an oxide to a nitride, by controlling the averaged oxygen flow rate, without reducing the deposition rate, compared to a conventional reactive process (CP). We then demonstrated that the refractive indexes of films deposited by this pulsing process (PP) can be varied in the same range compared to films obtained by CP (from 1.83 to 1.45 at 1.95 eV), whereas their extinction coefficients remain low. Finally, the multilayer ARC has been simulated and optimized by a genetic algorithm for wavelength at 600 nm and for the silicon substrate. Various optimized multilayer (mono-, bi- and tri-layers) structures have been deposited by the PP technique and characterized. They are presented in good agreement with the simulated reflectivity. Hence, the PP allows for an easy depositing tri-layer system with a reasonable deposition rate and low reflectivity (8.1% averaged on 400-750 nm visible light range).

  14. Different reactivities of amphetamines with N-methyl-bis(trifluoroacetamide) in heated gas chromatographic injectors.

    PubMed

    Hidvégi, E; Hideg, Zs; Somogyi, G P

    2008-03-01

    A fast gas chromatographic mass spectrometric method has been developed earlier for the determination of amphetamine derivatives in human serum and urine. For derivatization, N-methyl-bis(trifluoroacetamide) (MBTFA) was used. Derivatization was performed using an on-line mode, since 1 microl of MBTFA and 1 microl sample extract, dissolved in toluene were injected simultaneously. In this study, the reactivity of the several amphetamine type analytes with MBTFA was investigated. MBTFA used for flash derivatization was applied undiluted on the one hand and diluted 4--4096-fold with acetonitrile on the other hand. Studying several amphetamines in the test sample spiked at the same concentrations we found that they could be divided into 3 groups based on relative target ion peak areas as a function of MBTFA dilution. Group 1, containing only primary amines showed an early increase of the relative peak areas if we increased MBTFA concentration, where group 2 (mainly N-methyl secondary amines) showed that relative peak areas started to increase intensively at higher MBTFA concentrations. Finally, MDEA as an N-ethyl secondary amine, representing group 3, showed significant increase if only slightly diluted MBTFA was used as a flash reagent. This phenomenon can be explained mainly with the less and less reactivity of amine groups in the case of groups 2 and 3, compared to group 1. These findings could help to optimise analytical methods involving flash derivatization processes.

  15. Pulsed flashover of solid dielectric materials in compressed gas environment

    SciTech Connect

    Tewari, Somesh Vinayak E-mail: svtewari@barc.gov.in; Sharma, Archana; Mittal, K. C.

    2015-06-24

    An experimental investigation of surface flashover characteristics of PMMA and POM is studied in compressed nitrogen gas environment with nitrogen as the background gas. The operating pressure range is from 1kg/cm{sup 2} to 4kg/cm{sup 2}. It is observed that the breakdown voltage of PMMA is higher than POM owing to a higher permittivity mismatch between POM- nitrogen interface as compared to the PMMA- nitrogen interface. The reduction in spacer efficiency with pressure for PMMA is 11% as compared to POM which shows a higher reduction of 18%. This paper further emphasizes on the role of energy level and density of charge carrier trapping centers for a reduced breakdown voltage in POM as compared to PMMA.

  16. Rapid estimate of solid volume in large tuff cores using a gas pycnometer

    SciTech Connect

    Thies, C.; Geddis, A.M.; Guzman, A.G.

    1996-09-01

    A thermally insulated, rigid-volume gas pycnometer system has been developed. The pycnometer chambers have been machined from solid PVC cylinders. Two chambers confine dry high-purity helium at different pressures. A thick-walled design ensures minimal heat exchange with the surrounding environment and a constant volume system, while expansion takes place between the chambers. The internal energy of the gas is assumed constant over the expansion. The ideal gas law is used to estimate the volume of solid material sealed in one of the chambers. Temperature is monitored continuously and incorporated into the calculation of solid volume. Temperature variation between measurements is less than 0.1{degrees}C. The data are used to compute grain density for oven-dried Apache Leap tuff core samples. The measured volume of solid and the sample bulk volume are used to estimate porosity and bulk density. Intrinsic permeability was estimated from the porosity and measured pore surface area and is compared to in-situ measurements by the air permeability method. The gas pycnometer accommodates large core samples (0.25 m length x 0.11 m diameter) and can measure solid volume greater than 2.20 cm{sup 3} with less than 1% error.

  17. Prediction of Ablation Rates from Solid Surfaces Exposed to High Temperature Gas Flow

    NASA Technical Reports Server (NTRS)

    Akyuzlu, Kazim M.; Coote, David

    2013-01-01

    A mathematical model and a solution algorithm is developed to study the physics of high temperature heat transfer and material ablation and identify the problems associated with the flow of hydrogen gas at very high temperatures and velocities through pipes and various components of Nuclear Thermal Rocket (NTR) motors. Ablation and melting can be experienced when the inner solid surface of the cooling channels and the diverging-converging nozzle of a Nuclear Thermal Rocket (NTR) motor is exposed to hydrogen gas flow at temperatures around 2500 degrees Kelvin and pressures around 3.4 MPa. In the experiments conducted on typical NTR motors developed in 1960s, degradation of the cooling channel material (cracking in the nuclear fuel element cladding) and in some instances melting of the core was observed. This paper presents the results of a preliminary study based on two types of physics based mathematical models that were developed to simulate the thermal-hydrodynamic conditions that lead to ablation of the solid surface of a stainless steel pipe exposed to high temperature hydrogen gas near sonic velocities. One of the proposed models is one-dimensional and assumes the gas flow to be unsteady, compressible and viscous. An in-house computer code was developed to solve the conservations equations of this model using a second-order accurate finite-difference technique. The second model assumes the flow to be three-dimensional, unsteady, compressible and viscous. A commercial CFD code (Fluent) was used to solve the later model equations. Both models assume the thermodynamic and transport properties of the hydrogen gas to be temperature dependent. In the solution algorithm developed for this study, the unsteady temperature of the pipe is determined from the heat equation for the solid. The solid-gas interface temperature is determined from an energy balance at the interface which includes heat transfer from or to the interface by conduction, convection, radiation, and

  18. A second-order Godunov method for wave problems in coupled solid-water-gas systems

    SciTech Connect

    Tang, H.S.; Sotiropoulos, F.

    1999-05-20

    Wave problems in solid-water-gas systems with distinct phase interfaces are commonly encountered in practice, such as in water entry of a recovered body, reservoir-dam interaction during earthquakes, and spallation of steel plates caused by blast waves. Here, the authors present a second-order Godunov method for computing unsteady, one-dimensional wave problems with a fracture and cavitation in coupled solid-water-gas systems. The method employs a hydro-elasto-plastic body, the Tait equation, and the ideal gas law for solid, water, and gaseous phases, respectively, and models both fractures and cavities as vacuum zones with distinct borders. The numerical approach utilizes a Lagrangian formulation in conjunction with local solid-water-gas-vacuum Riemann problems, which have unique solutions and can be solved efficiently. The various phases are treated in a unified manner and no supplementary interface conditions are necessary for tracking material boundaries. Calculations are carried out for Riemann problems, wave propagation and reflection in a water-rock-air system, and spallation and cavitation in an explosion-steel-water-gas system. It is shown that the Godunov method has high resolution for shocks and phase interfaces, clearly resolves elastic and plastic waves, and successfully describes onset and propagation of fracture and cavitation zones.

  19. Formation of the Giant Planets by Concurrent Accretion of Solids and Gas

    NASA Technical Reports Server (NTRS)

    Hubickyj, Olenka

    1997-01-01

    Models were developed to simulate planet formation. Three major phases are characterized in the simulations: (1) planetesimal accretion rate, which dominates that of gas, rapidly increases owing to runaway accretion, then decreases as the planet's feeding zone is depleted; (2) occurs when both solid and gas accretion rates are small and nearly independent of time; and (3) starts when the solid and gas masses are about equal and is marked by runaway gas accretion. The models applicability to planets in our Solar System are judged using two basic "yardsticks". The results suggest that the solar nebula dissipated while Uranus and Neptune were in the second phase, during which, for a relatively long time, the masses of their gaseous envelopes were small but not negligible compared to the total masses. Background information, results and a published article are included in the report.

  20. IGR solid-state electrochemical NO sub x control for natural gas combustion exhaust gases

    SciTech Connect

    Hossain, M.S.; Neyman, M.; Cook, W.J. ); Gordon, A.Z. )

    1989-07-01

    Solid-state electrochemical technology, embodied in the IGR process, is used to reduce nitrogen oxides (NO{sub x}) to nitrogen and oxygen, and thereby control NO{sub x} emissions from natural gas powered engines. The IGR deNO{sub x} process is based on solid-state, flow-through, high surface area, porous oxygen ion conductive ceramic electrolytes. Recent bench-scale experiments have demonstrated NO{sub x} reduction in multicomponent gas streams, the inert portion of which simulate natural gas combustion products. The reduction products were analyzed by in situ gas chromatography to verify NO{sub x} reduction rates inferred from electrochemical measurements. IGR process advantages compared with existing NO{sub x} control technologies are reviewed.

  1. Solid-state gas sensors for breath analysis: a review.

    PubMed

    Di Natale, Corrado; Paolesse, Roberto; Martinelli, Eugenio; Capuano, Rosamaria

    2014-05-08

    The analysis of volatile compounds is an efficient method to appraise information about the chemical composition of liquids and solids. This principle is applied to several practical applications, such as food analysis where many important features (e.g. freshness) can be directly inferred from the analysis of volatile compounds. The same approach can also be applied to a human body where the volatile compounds, collected from the skin, the breath or in the headspace of fluids, might contain information that could be used to diagnose several kinds of diseases. In particular, breath is widely studied and many diseases can be potentially detected from breath analysis. The most fascinating property of breath analysis is the non-invasiveness of the sample collection. Solid-state sensors are considered the natural complement to breath analysis, matching the non-invasiveness with typical sensor features such as low-cost, easiness of use, portability, and the integration with the information networks. Sensors based breath analysis is then expected to dramatically extend the diagnostic capabilities enabling the screening of large populations for the early diagnosis of pathologies. In the last years there has been an increased attention to the development of sensors specifically aimed to this purpose. These investigations involve both specific sensors designed to detect individual compounds and non-specific sensors, operated in array configurations, aimed at clustering subjects according to their health conditions. In this paper, the recent significant applications of these sensors to breath analysis are reviewed and discussed.

  2. Flow Mapping in a Gas-Solid Riser via Computer Automated Radioactive Particle Tracking (CARPT)

    SciTech Connect

    Muthanna Al-Dahhan; Milorad P. Dudukovic; Satish Bhusarapu; Timothy J. O'hern; Steven Trujillo; Michael R. Prairie

    2005-06-04

    Statement of the Problem: Developing and disseminating a general and experimentally validated model for turbulent multiphase fluid dynamics suitable for engineering design purposes in industrial scale applications of riser reactors and pneumatic conveying, require collecting reliable data on solids trajectories, velocities ? averaged and instantaneous, solids holdup distribution and solids fluxes in the riser as a function of operating conditions. Such data are currently not available on the same system. Multiphase Fluid Dynamics Research Consortium (MFDRC) was established to address these issues on a chosen example of circulating fluidized bed (CFB) reactor, which is widely used in petroleum and chemical industry including coal combustion. This project addresses the problem of lacking reliable data to advance CFB technology. Project Objectives: The objective of this project is to advance the understanding of the solids flow pattern and mixing in a well-developed flow region of a gas-solid riser, operated at different gas flow rates and solids loading using the state-of-the-art non-intrusive measurements. This work creates an insight and reliable database for local solids fluid-dynamic quantities in a pilot-plant scale CFB, which can then be used to validate/develop phenomenological models for the riser. This study also attempts to provide benchmark data for validation of Computational Fluid Dynamic (CFD) codes and their current closures. Technical Approach: Non-Invasive Computer Automated Radioactive Particle Tracking (CARPT) technique provides complete Eulerian solids flow field (time average velocity map and various turbulence parameters such as the Reynolds stresses, turbulent kinetic energy, and eddy diffusivities). It also gives directly the Lagrangian information of solids flow and yields the true solids residence time distribution (RTD). Another radiation based technique, Computed Tomography (CT) yields detailed time averaged local holdup profiles at

  3. Cannock landfill gas powering a small tubular solid oxide fuel cell — a case study

    NASA Astrophysics Data System (ADS)

    Staniforth, J.; Kendall, K.

    Cannock landfill gas — mainly a mixture of methane and carbon dioxide — can successfully power a small tubular solid oxide fuel cell. Initial experiments showed a relatively rapid falling off in power due to poisoning with hydrogen sulphide. A simple de-sulphurisation system alleviated this problem. Even greater performance was achieved by the pre-addition of air to help in the reforming of the gas, giving little loss of power over the lifetime of the experiment.

  4. Heat transfer coefficients of dilute flowing gas-solids suspensions

    NASA Technical Reports Server (NTRS)

    Kane, R. S.; Pfeffer, R.

    1973-01-01

    Heat transfer coefficients of air-glass, argon-glass, and argon-aluminum suspensions were measured in horizontal and vertical tubes. The glass, 21.6 and 36.0 micron diameter particles, was suspended at gas Reynolds numbers between 11,000 and 21,000 and loading ratios between 0 and 2.5. The presence of particles generally reduced the heat transfer coefficient. The circulation of aluminum powder in the 0.870 inch diameter closed loop system produced tenacious deposits on protuberances into the stream. In the vertical test section, the Nusselt number reduction was attributed to viscous sublayer thickening; in the horizontal test section to particle deposition.

  5. Co-CoO nanoparticles prepared by reactive gas-phase aggregation

    NASA Astrophysics Data System (ADS)

    González, J. A.; Andrés, J. P.; De Toro, J. A.; Muñiz, P.; Muñoz, T.; Crisan, O.; Binns, C.; Riveiro, J. M.

    2009-11-01

    The technique of gas-phase aggregation has been used to prepare partially oxidized Co nanoparticles films by allowing a controlled flow of oxygen gas into the aggregation zone. This method differs from those previously reported, that is, the passivation of a beam of preformed particles in a secondary chamber and the conventional (low Ar pressure) reactive sputtering of Co to produce Co-CoO composite films. Transmission electron microscopy shows that the mean size of the particles is about 6 nm. For sufficiently high oxygen pressures, the nanoparticles films become super-paramagnetic at room temperature. X-ray diffraction patterns display reflections corresponding to fcc Co and fcc CoO phases, with an increasing dominance of the latter upon increasing the oxygen pressure in the aggregation zone, which is consistent with the observed reduction in saturation magnetization. The cluster films assembled with particles grown under oxygen in the condensation zone exhibit exchange-bias fields (about 8 kOe at 20 K) systematically higher than those measured for Co-CoO core-shell nanoparticles prepared by oxidizing preformed particles in the deposition chamber, which we attribute, in the light of results from annealing experiments, to a higher ferromagnetic-antiferromagnetic (Co-CoO) interface density.

  6. Si substrates texturing and vapor-solid-solid Si nanowhiskers growth using pure hydrogen as source gas

    SciTech Connect

    Nordmark, H.; Holmestad, R.; Nagayoshi, H.; Matsumoto, N.; Nishimura, S.; Terashima, K.; Marioara, C. D.; Walmsley, J. C.; Ulyashin, A.

    2009-02-15

    Scanning and transmission electron microscopies have been used to study silicon substrate texturing and whisker growth on Si substrates using pure hydrogen source gas in a tungsten hot filament reactor. Substrate texturing, in the nanometer to micrometer range of mono- and as-cut multicrystalline silicon, was observed after deposition of WSi{sub 2} particles that acted as a mask for subsequent hydrogen radical etching. Simultaneous Si whisker growth was observed for long residence time of the source gas and low H{sub 2} flow rate with high pressure. The whiskers formed via vapor-solid-solid growth, in which the deposited WSi{sub 2} particles acted as catalysts for a subsequent metal-induced layer exchange process well below the eutectic temperature. In this process, SiH{sub x} species, formed by substrate etching by the H radicals, diffuse through the metal particles. This leads to growth of crystalline Si whiskers via metal-induced solid-phase crystallization. Transmission electron microscopy, electron diffraction, and x-ray energy dispersive spectroscopy were used to study the WSi{sub 2} particles and the structure of the Si substrates in detail. It has been established that the whiskers are partly crystalline and partly amorphous, consisting of pure Si with WSi{sub 2} particles on their tips as well as sometimes being incorporated into their structure.

  7. Acoustic probe for solid-gas-liquid suspensions. 1997 annual progress report

    SciTech Connect

    Tavlarides, L.L.; Sangani, A.S.

    1997-01-01

    'Acoustic probes have shown promise to be quite effective in determining the solid content in solid-liquid suspensions. However, the presence of small amounts of gas in the waste slurries stored in tanks across the DOE complex prevents straightforward application for characterization of these slurries. The proposed research will develop an acoustic probe for monitoring particle size and volume fraction in slurries in the absence and the presence of gas bubbles. Theoretical Analysis Accomplished: Attenuation of sound waves depends on the size distribution of the solids and the volume fraction of solids. These can in principle be calculated from attenuation measured over a range of frequencies. However, small amounts of bubbles distort the measured attenuation. A typical result from theoretical analysis for the attenuation of solid- gas-liquid systems is given in Figure 1. The total attenuation of a sound wave v(o) equals the sum of contributions by a large number of ''bins'' of particle sizes. This notion yields the following equation for the (hitherto) unknown number density of solid particles as a function of particle radius N(a): j k(o,a)N(a)da = v(o), where the kernel k(o,a) is obtained from analysis. If N(a) is given, the above equation is used to calculate the attenuation v(o). This is referred to as solving the ''forward problem''. Solving for N(a) with v(o) given is the ''inverse problem''. A complication that one faces when trying to solve the inverse problem is that the stated problem is mathematically ill-posed, i.e., small fluctuations in v(o) cause large fluctuations in the result for the number density. Therefore the problem needs to be ''regularized'', i.e., the stated problem needs to be changed slightly such as to make it well-posed. This has been done by others for gas-liquid systems in the past. This approach is currently being applied in the present project to solid-liquid systems. As is shown in Figure 2, it successfully recovers the number

  8. Fault reactivation and seismicity risk from CO2 sequestration in the Chinshui gas field, NW Taiwan

    NASA Astrophysics Data System (ADS)

    Sung, Chia-Yu; Hung, Jih-Hao

    2015-04-01

    The Chinshui gas field located in the fold-thrust belt of western Taiwan was a depleted reservoir. Recently, CO2 sequestration has been planned at shallower depths of this structure. CO2 injection into reservoir will generate high fluid pressure and trigger slip on reservoir-bounding faults. We present detailed in-situ stresses from deep wells in the Chinshui gas field and evaluated the risk of fault reactivation for underground CO2 injection. The magnitudes of vertical stress (Sv), formation pore pressure (Pf) and minimum horizontal stress (Shmin) were obtained from formation density logs, repeat formation tests, sonic logs, mud weight, and hydraulic fracturing including leak-off tests and hydraulic fracturing. The magnitude of maximum horizontal stress (SHmax) was constrained by frictional limit of critically stressed faults. Results show that vertical stress gradient is about 23.02 MPa/km (1.02 psi/ft), and minimum horizontal stress gradient is 18.05 MPa/km (0.80 psi/ft). Formation pore pressures were hydrostatic at depths 2 km, and increase with a gradient of 16.62 MPa/km (0.73 psi/ft). The ratio of fluid pressure and overburden pressure (λp) is 0.65. The upper bound of maximum horizontal stress constrained by strike-slip fault stress regime (SHmax>Sv>Shmin) and coefficient of friction (μ=0.6) is about 18.55 MPa/km (0.82 psi/ft). The orientation of maximum horizontal stresses was calculated from four-arm caliper tools through the methodology suggested by World Stress Map (WMS). The mean azimuth of preferred orientation of borehole breakouts are in ~65。N. Consequently, the maximum horizontal stress axis trends in 155。N and sub-parallel to the far-field plate-convergence direction. Geomechanical analyses of the reactivation of pre-existing faults was assessed using 3DStress and Traptester software. Under current in-situ stress, the middle block fault has higher slip tendency, but still less than frictional coefficient of 0.6 a common threshold value for

  9. Solid waste generation from oil and gas industries in United Arab Emirates.

    PubMed

    Elshorbagy, Walid; Alkamali, Abdulqader

    2005-04-11

    Solid wastes generated from oil and gas industrial activities are very diverse in their characteristics, large in their amounts and many of which are hazardous in nature. Thus, quantifying and characterizing the generated amounts in association with their types, classes, sources, industrial activities, and their chemical and biological characteristics is an obvious mandate when evaluating the possible management practices. This paper discusses the types, amounts, generation units, and the factors related to solid waste generation from a major oil and gas field in the United Arab Emirates (Asab Field). The generated amounts are calculated based on a 1-year data collection survey and using a database software specially developed and customized for the current study. The average annual amount of total solid waste generated in the studied field is estimated at 4061 t. Such amount is found equivalent to 650 kg/capita, 0.37 kg/barrel oil, and 1.6 kg/m3 of extracted gas. The average annual amount of hazardous solid waste is estimated at 55 t and most of which (73%) is found to be generated from gas extraction-related activities. The majority of other industrial non-hazardous solid waste is generated from oil production-related activities (41%), The present analysis does also provide the estimated generation amounts per waste type and class, amounts of combustible, recyclable, and compostable wastes, and the amounts dumped in uncontrolled way as well as disposed into special hazardous landfill facilities. The results should help the decision makers in evaluating the best alternatives available to manage the solid wastes generated from the oil and gas industries.

  10. Application of the carbon dioxide-barium hydroxide hydrate gas-solid reaction for the treatment of dilute carbon dioxide-bearing gas streams

    SciTech Connect

    Haag, G.L.

    1983-09-01

    The removal of trace components from gas streams via irreversible gas-solid reactions in an area of interest to the chemical engineering profession. This research effort addresses the use of fixed beds of Ba(OH)/sub 2/ hydrate flakes for the removal of an acid gas, CO/sub 2/, from air that contains approx. 330 ppM/sub v/ CO/sub 2/. Areas of investigation encompassed: (1) an extensive literature review of Ba(OH)/sub 2/ hydrate chemistry, (2) microscale studies on 0.150-g samples to develop a better understanding of the reaction, (3) process studies at the macroscale level with 10.2-cm-ID fixed-bed reactors, and (4) the development of a model for predicting fixed-bed performance. Experimental studies indicated fixed beds of commercial Ba(OH)/sub 2/.8H/sub 2/O flakes at ambient temperatures to be capable of high CO/sub 2/-removal efficiencies (effluent concentrations <100 ppB), high reactant utilization (>99%), and an acceptable pressure drop (1.8 kPa/m at a superficial gas velocity of 13 cm/s). Ba(OH)/sub 2/.8H/sub 2/O was determined to be more reactive toward CO/sub 2/ than either Ba(OH)/sub 2/.3H/sub 2/O or Ba(OH)/sub 2/.1H/sub 2/O. A key variable in the development of this fixed-bed process was relative humidity. Operation at conditions with effluent relative humidities >60% resulted in significant recrystallization and restructuring of the flake and subsequent pressure-drop problems.

  11. Estimating production and consumption of solid reactive Fe phases in marine sediments from concentration profiles

    EPA Science Inventory

    1D diffusion models may be used to estimate rates of production and consumption of dissolved metabolites in marine sediments, but are applied less often to the solid phase. Here we used a numerical inverse method to estimate solid phase Fe(III) and Fe(II) consumption and product...

  12. Distillation and isolation of commodity chemicals from Bio-oil made by tail-gas reactive prolysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Owing to instabilities, very little has been accomplished with regards to simple cost-effective separations of fast-pyrolysis bio-oil. However, recent developments in the use of tail-gas reactive pyrolysis (TGRP) (Mullen and Boateng 2013) provide higher quality bio-oils that are thermally stable. We...

  13. Aqueous extractive upgrading of bio-oils created by tail-gas reactive pyrolysis to produce pure hydrocarbons and phenols

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tail-gas reactive pyrolysis (TGRP) of biomass produces bio-oil that is lower in oxygen (~15 wt% total) and significantly more hydrocarbon-rich than traditional bio-oils or even catalytic fast pyrolysis. TGRP bio-oils lend themselves toward mild and inexpensive upgrading procedures. We isolated oxyge...

  14. Electrophilic acid gas-reactive fluid, proppant, and process for enhanced fracturing and recovery of energy producing materials

    DOEpatents

    Fernandez, Carlos A.; Heldebrant, David J.; Bonneville, Alain H. R.; Jung, Hun Bok; Carroll, Kenneth

    2016-09-20

    An electrophilic acid gas-reactive fracturing and recovery fluid, proppant, and process are detailed. The fluid expands in volume to provide rapid and controlled increases in pressure that enhances fracturing in subterranean bedrock for recovery of energy-producing materials. Proppants stabilize openings in fractures and fissures following fracturing.

  15. Medium-temperature solid oxide fuel cells prepared using reactive magnetron sputtering. Ph.D. Thesis

    SciTech Connect

    Wang, L.

    1993-12-31

    The purpose of this research is to investigate the deposition, structure, interfacial impedances, and characteristics of medium temperature solid-oxide fuel cells (SOFC`s) with thin-film electrolytes. Three main areas have been investigated. First, the structure, chemistry, and properties of materials designed specifically for medium temperature SOFC`s have been studied. The authors have developed techniques for sputter deposition of cubic 10 mol percent Y2O3-stabilized zirconia (YSZ) and 30 mol percent Y2O3-doped bismuth oxide (YSB) thin film oxygen ion conductors. The electrical properties of the films were characterized using the complex impedance spectroscopy method. Studies of AgYSZ cermet and Ag-perovskite (perovskite = La(1-x)Sr(x)Co(Mn)O3), used as high conductivity, low overpotential air electrodes, have also been carried out. Second, interfacial impedances for various electrode-electrolyte combinations and for multilayer electrolytes have been studied. In particular, the authors have found that a layer of Y-stabilized Bi2O3 (YSB) as thin as 60 nm between the YSZ electrolyte and the electrode significantly reduces the interfacial resistance. For example, inserting YSB between YSZ and a Ag-YSZ electrode reduces the resistance from 1.5 to 0.45 Omega cm(exp 2) at 750 deg C in air. Ag-(La,Sr)CoO3 on YSB electrolytes had interfacial resistances as low as 0.3 Omega cm2, compared with 0.4 and 1.5 Omega cm(exp 2) for (La,Sr)CoO3 and Ag on YSB at 750 deg C, respectively. The Ag cermet materials thus exhibited lower interfacial resistances than their component materials. Third, thin film medium temperature SOFC`s have been fabricated and characterized. SOFC`s were deposited onto porous alumina supports. The resulting cell open-circuit voltages (OCV) were approximately equal to 0.8 V, 0.3 V less than expected, due to gas cross-over.

  16. Forebody and base region real gas flow in severe planetary entry by a factored implicit numerical method. II - Equilibrium reactive gas

    NASA Technical Reports Server (NTRS)

    Davy, W. C.; Green, M. J.; Lombard, C. K.

    1981-01-01

    The factored-implicit, gas-dynamic algorithm has been adapted to the numerical simulation of equilibrium reactive flows. Changes required in the perfect gas version of the algorithm are developed, and the method of coupling gas-dynamic and chemistry variables is discussed. A flow-field solution that approximates a Jovian entry case was obtained by this method and compared with the same solution obtained by HYVIS, a computer program much used for the study of planetary entry. Comparison of surface pressure distribution and stagnation line shock-layer profiles indicates that the two solutions agree well.

  17. ASEF solid-waste-to-methane gas, Pompano Beach, Florida, refCOM

    NASA Astrophysics Data System (ADS)

    Mooij, H. P.

    1983-01-01

    Five graphs are presented to document solid waste to methane experiments. The first simply shows the number of hours spent running in relation to the number of tons of material fed into the digester. The second shows the relationship between tonnage fed and subsequent gas production. Tonnage is further broken down into moisture, dry, and volatile fractions. The third graph shows the relationship between methane and carbon dioxide in the off gas. The fourth graph shows the pH, alkalinity, and volatile acids in the digester slurry environment, Nutrient levels of the effluent are shown in the fifth graph. Finally, materials analysis and gas production data are tabulated.

  18. Tailoring surface conditions for enhanced reactivity of aluminum powders with solid oxidizing agents

    NASA Astrophysics Data System (ADS)

    Padhye, Richa; Smith, Dylan K.; Korzeniewski, Carol; Pantoya, Michelle L.

    2017-04-01

    The effect of processing liquids on particle surface hydration and subsequent reactivity of mixtures containing aluminum (Al) with different oxidizing agents was investigated. Recently, polar processing liquids were shown to significantly increase the surface hydration layer on Al particles and effect the reactivity of Al combined with polytetrafluoroethylene (PTFE). Processing mixtures of Al and PTFE using hexane (e.g., a non-polar liquid) limited surface hydration and produced significantly lower flame speeds than the same mixture processed in isopropanol (e.g., a polar liquid). Increased surface hydroxyl concentration was linked to higher exothermic behavior within a pre-ignition reaction (PIR) which may contribute to higher overall flame speed. This study extends the previous analysis toward assessing the influence of processing liquid on reactivity of aluminum with other oxidizing agents, specifically CuO, MoO3 and I2O5. Results from DSC analysis show no PIR kinetics associated with Al and CuO or MoO3, and Al+ CuO showed no difference in reactivity as a function of processing liquid. But, MoO3 FTIR shows modified surface structures after treatment in a polar solvent. Correspondingly, Al + MoO3 processed in polar solvent exhibited increased flame speed by 19% when compared to Al + MoO3 processed in a non-polar liquid. For Al + I2O5, water in polar processing liquids produces various hydrated states of iodic acid (i.e., HIO3 and HI3O8). Changing the hydration state of I2O5 significantly impacts reactivity. Results from this study confirm that carrier fluid used to process Al with metal oxides can also alter the surface structure of the metal oxide, thereby promoting greater reactivity with Al. A polar carrier fluid not only modifies the surface of Al but also hydration sensitive metal oxides such as MoO3 and correspondingly promotes greater reactivity.

  19. The effect of gas double-dynamic on mass distribution in solid-state fermentation.

    PubMed

    Chen, Hong-Zhang; Zhao, Zhi-Min; Li, Hong-Qiang

    2014-05-10

    The mass distribution regularity in substrate of solid-state fermentation (SSF) has rarely been reported due to the heterogeneity of solid medium and the lack of suitable instrument and method, which limited the comprehensive analysis and enhancement of the SSF performance. In this work, the distributions of water, biomass, and fermentation product in different medium depths of SSF were determined using near-infrared spectroscopy (NIRS) and the developed models. Based on the mass distribution regularity, the effects of gas double-dynamic on heat transfer, microbial growth and metabolism, and product distribution gradient were systematically investigated. Results indicated that the maximum temperature of substrate and the maximum carbon dioxide evolution rate (CER) were 39.5°C and 2.48mg/(hg) under static aeration solid-state fermentation (SASSF) and 33.9°C and 5.38mg/(hg) under gas double-dynamic solid-state fermentation (GDSSF), respectively, with the environmental temperature for fermentation of 30±1°C. The fermentation production (cellulase activity) ratios of the upper, middle, and lower levels were 1:0.90:0.78 at seventh day under SASSF and 1:0.95:0.89 at fifth day under GDSSF. Therefore, combined with NIRS analysis, gas double-dynamic could effectively strengthen the solid-state fermentation performance due to the enhancement of heat transfer, the stimulation of microbial metabolism and the increase of the homogeneity of fermentation products.

  20. Improve your solids control. [Management of solids during oil and gas well drilling

    SciTech Connect

    Montgomery, M.S. ); Love, W.W. )

    1993-10-01

    With today's emphasis on the environmental impact of drilling operations, minimization of drilling fluid and drill cuttings waste is critical. This can be achieved using proper solids removal equipment -- such as high performance shale shakers, hydrocyclones, and centrifuges -- and proper pre-well planning. The method described here is founded in decision matrix theory and focuses on several key variables. These include well parameters, the drilling program, logistics, environmental issues, rig selection, expert advice and cost.

  1. Continuum Approaches for Describing Solid-Gas and Solid-Liquid Flow

    DTIC Science & Technology

    1992-02-01

    architecture, cellular automata , etc.) as they become available. These computer simulations can be used to evaluate the rheological properties and, hence, be...avalanches and sand- dune formation, in addition to its relevance for solid transport e.g., circulating fluidized beds. Simple kinetic theories of particle...Real flowing sand forms sandpiles (or sand dunes ) stabilized by sliding friction as the velocity becomes small, yet a continuum fluid model of the

  2. Analysis of Indirect Emissions Benefits of Wind, Landfill Gas, and Municipal Solid Waste Generation

    EPA Science Inventory

    Techniques are introduced to calculate the hourly indirect emissions benefits of three types of green power resources: wind energy, municipal solid waste (MSW) combustion, and landfill gas (LFG) combustion. These techniques are applied to each of the U.S. EPA's eGRID subregions i...

  3. Highly sensitive solids mass spectrometer uses inert-gas ion source

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Mass spectrometer provides a recorded analysis of solid material surfaces and bulk. A beam of high-energy inert-gas ions bombards the surface atoms of a sample and converts a percentage into an ionized vapor. The mass spectrum analyzer separates the vapor ionic constituents by mass-to-charge ratio.

  4. Greenhouse gas emission and groundwater pollution potentials of soils amended with raw and carbonized swine solids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this research is to study the greenhouse gas emission and groundwater pollution potentials of the soils amended with raw swine solids and swine biochars made from different thermochemical conditions. Triplicate sets of small pots were designed: 1) control soil with a 50/50 mixture o...

  5. Utilization of the Recycle Reactor in Determining Kinetics of Gas-Solid Catalytic Reactions.

    ERIC Educational Resources Information Center

    Paspek, Stephen C.; And Others

    1980-01-01

    Describes a laboratory scale reactor that determines the kinetics of a gas-solid catalytic reaction. The external recycle reactor construction is detailed with accompanying diagrams. Experimental details, application of the reactor to CO oxidation kinetics, interphase gradients, and intraphase gradients are discussed. (CS)

  6. Solid oxide fuel cell having compound cross flow gas patterns

    DOEpatents

    Fraioli, A.V.

    1983-10-12

    A core construction for a fuel cell is disclosed having both parallel and cross flow passageways for the fuel and the oxidant gases. Each core passageway is defined by electrolyte and interconnect walls. Each electrolyte wall consists of cathode and anode materials sandwiching an electrolyte material. Each interconnect wall is formed as a sheet of inert support material having therein spaced small plugs of interconnect material, where cathode and anode materials are formed as layers on opposite sides of each sheet and are electrically connected together by the interconnect material plugs. Each interconnect wall in a wavy shape is connected along spaced generally parallel line-like contact areas between corresponding spaced pairs of generally parallel electrolyte walls, operable to define one tier of generally parallel flow passageways for the fuel and oxidant gases. Alternate tiers are arranged to have the passageways disposed normal to one another. Solid mechanical connection of the interconnect walls of adjacent tiers to the opposite sides of the common electrolyte wall therebetween is only at spaced point-like contact areas, 90 where the previously mentioned line-like contact areas cross one another.

  7. On the Electron Gas Heat Capacity in Undergraduate Solid State

    NASA Astrophysics Data System (ADS)

    Hasbun, Javier

    2013-03-01

    In undergraduate solid state physics the electronic energy, Uel, is calculated through the Fermi distribution function while the energy is weighted with the density of states. The electronic heat capacity is the derivative of the electronic energy with respect to temperature. Through this process, it is possible to obtain a low temperature approximation for the heat capacity, Cel that's proportional to the temperature. It is of interest to do a numerical calculation of Uel from which the numerical Cel is extracted. However, the result obtained, while agreeing with the low temperature approximation, has a slope that's substantially different. The disagreement appears large as the temperature is increased from zero K. Here we show that the reason has to do with the constancy of the Fermi level. By including the self consistent behavior of the chemical potential, the deviation from zero Kelvin is much improved and the result seems to make better sense. The lesson learned is significant enough to be of great pedagogical importance as regards the heat capacity calculation and the behavior of the chemical potential with temperature.

  8. Solid oxide fuel cell having compound cross flow gas patterns

    DOEpatents

    Fraioli, Anthony V.

    1985-01-01

    A core construction for a fuel cell is disclosed having both parallel and cross flow passageways for the fuel and the oxidant gases. Each core passageway is defined by electrolyte and interconnect walls. Each electrolyte wall consists of cathode and anode materials sandwiching an electrolyte material. Each interconnect wall is formed as a sheet of inert support material having therein spaced small plugs of interconnect material, where cathode and anode materials are formed as layers on opposite sides of each sheet and are electrically connected together by the interconnect material plugs. Each interconnect wall in a wavy shape is connected along spaced generally parallel line-like contact areas between corresponding spaced pairs of generally parallel electrolyte walls, operable to define one tier of generally parallel flow passageways for the fuel and oxidant gases. Alternate tiers are arranged to have the passageways disposed normal to one another. Solid mechanical connection of the interconnect walls of adjacent tiers to the opposite sides of the common electrolyte wall therebetween is only at spaced point-like contact areas, 90 where the previously mentioned line-like contact areas cross one another.

  9. Ninhydrin reaction on thiol-reactive solid and its potential for the quantitation of D-penicillamine.

    PubMed

    Rojanarata, Theerasak; Opanasopit, Praneet; Ngawhirunpat, Tanasait; Saehuan, Choedchai

    2010-07-15

    While aminothiols produce weak purple-colored reactions with ninhydrin, we demonstrate for the first time that this color could be intensely developed. Using a D-penicillamine paradigm, adsorption of this compound via a disulfide bond onto thiol-reactive solid prior to ninhydrin reaction allowed spectrophotometrical monitoring of the supernatant at 570 nm. Compared with off-solid method, this approach expanded the linear concentration range to 50-600 microg mL(-1) and enhanced the sensitivity so that D-penicillamine with the concentrations of less than 100 microg mL(-1) could be accurately quantitated by using a second-order polynomial calibration curve. Additionally, this assay was unaffected by disulfide adduct interference, highlighting its potential for the analysis of D-penicillamine as well as other aminothiols.

  10. Optimum design of the constant-volume gas pycnometer for determining the volume of solid particles

    NASA Astrophysics Data System (ADS)

    Tamari, S.

    2004-03-01

    Gas pycnometry is based on Boyle-Mariotte's law of volume-pressure relationships. This method has been widely used to determine the volume (and thus the density) of rock fragments, soluble powders, light objects and even living beings. Surprisingly, little is known about the optimum design of gas pycnometers. The purpose of this study was to investigate the optimum design of a gas pycnometer, so that it can determine the volume of solid particles with the greatest accuracy. The 'constant-volume' gas pycnometer was considered because of its widespread use. The law of propagation of uncertainty was used to derive a theoretical formula that relates the pycnometer's accuracy to the main sources of random error (gas-pressure measurements, pycnometer temperature and sample-chamber volume). The consequences of this formula in terms of optimizing the geometry and working conditions of the pycnometer are discussed. It was found that some gas pycnometers described in the literature may have not been used under the best conditions. Guidelines are given to design a gas pycnometer that can theoretically determine the volume of solid particles with a relative standard uncertainty smaller than 0.2%.

  11. Vapor-liquid-solid epitaxial growth of Si1-xGex alloy nanowires. Composition dependence on precursor reactivity and morphology control for vertical forests

    DOE PAGES

    Choi, S. G.; Manandhar, P.; Picraux, S. T.

    2015-07-07

    The growth of high-density group IV alloy nanowire forests is critical for exploiting their unique functionalities in many applications. Here, the compositional dependence on precursor reactivity and optimized conditions for vertical growth are studied for Si1- x Ge x alloy nanowires grown by the vapor-liquid-solid method. The nanowire composition versus gas partial-pressure ratio for germane-silane and germane-disilane precursor combinations is obtained at 350°C over a wide composition range (0.05 ≤ x ≤ 0.98) and a generalized model to predict composition for alloy nanowires is developed based on the relative precursor partial pressures and reactivity ratio. In combination with germane, silanemore » provides more precise compositional control at high Ge concentrations (x > 0.7), whereas disilane greatly increases the Si concentration for a given gas ratio and enables more precise alloy compositional control at small Ge concentrations (x < 0.3). Vertically oriented, non-kinking nanowire forest growth on Si (111) substrates is then discussed for silane/germane over a wide range of compositions, with temperature and precursor partial pressure optimized by monitoring the nanowire growth front using in-situ optical reflectance. For high Ge compositions (x ≈ 0.9), a “two-step” growth approach with nucleation at higher temperatures results in nanowires with high-density and uniform vertical orientation. Furthermore, increasing Si content (x ≈ 0.8), the optimal growth window is shifted to higher temperatures, which minimizes nanowire kinking morphologies. For Si-rich Si1- x Ge x alloys (x ≈ 0.25), vertical nanowire growth is enhanced by single-step, higher-temperature growth at reduced pressures.« less

  12. Online gas composition estimation in solid oxide fuel cell systems with anode off-gas recycle configuration

    NASA Astrophysics Data System (ADS)

    Dolenc, B.; Vrečko, D.; Juričić, Ð.; Pohjoranta, A.; Pianese, C.

    2017-03-01

    Degradation and poisoning of solid oxide fuel cell (SOFC) stacks are continuously shortening the lifespan of SOFC systems. Poisoning mechanisms, such as carbon deposition, form a coating layer, hence rapidly decreasing the efficiency of the fuel cells. Gas composition of inlet gases is known to have great impact on the rate of coke formation. Therefore, monitoring of these variables can be of great benefit for overall management of SOFCs. Although measuring the gas composition of the gas stream is feasible, it is too costly for commercial applications. This paper proposes three distinct approaches for the design of gas composition estimators of an SOFC system in anode off-gas recycle configuration which are (i.) accurate, and (ii.) easy to implement on a programmable logic controller. Firstly, a classical approach is briefly revisited and problems related to implementation complexity are discussed. Secondly, the model is simplified and adapted for easy implementation. Further, an alternative data-driven approach for gas composition estimation is developed. Finally, a hybrid estimator employing experimental data and 1st-principles is proposed. Despite the structural simplicity of the estimators, the experimental validation shows a high precision for all of the approaches. Experimental validation is performed on a 10 kW SOFC system.

  13. A study of tritium in municipal solid waste leachate and gas

    SciTech Connect

    Mutch Jr, R. D.; Mahony, J. D.

    2008-07-15

    It has become increasingly clear in the last few years that the vast majority of municipal solid waste landfills produce leachate that contains elevated levels of tritium. The authors recently conducted a study of landfills in New York and New Jersey and found that the mean concentration of tritium in the leachate from ten municipal solid waste (MSW) landfills was 33,800 pCi/L with a peak value of 192,000 pCi/L. A 2003 study in California reported a mean tritium concentration of 99,000 pCi/L with a peak value of 304,000 pCi/L. Studies in Pennsylvania and the UK produced similar results. The USEPA MCL for tritium is 20,000 pCi/L. Tritium is also manifesting itself as landfill gas and landfill gas condensate. Landfill gas condensate samples from landfills in the UK and California were found to have tritium concentrations as high as 54,400 and 513,000 pCi/L, respectively. The tritium found in MSW leachate is believed to derive principally from gaseous tritium lighting devices used in some emergency exit signs, compasses, watches, and even novelty items, such as 'glow stick' key chains. This study reports the findings of recent surveys of leachate from a number of municipal solid waste landfills, both open and closed, from throughout the United States and Europe. The study evaluates the human health and ecological risks posed by elevated tritium levels in municipal solid waste leachate and landfill gas and the implications to their safe management. We also assess the potential risks posed to solid waste management facility workers exposed to tritium-containing waste materials in transfer stations and other solid waste management facilities. (authors)

  14. A nanostructured surface increases friction exponentially at the solid-gas interface

    PubMed Central

    Phani, Arindam; Putkaradze, Vakhtang; Hawk, John E.; Prashanthi, Kovur; Thundat, Thomas

    2016-01-01

    According to Stokes’ law, a moving solid surface experiences viscous drag that is linearly related to its velocity and the viscosity of the medium. The viscous interactions result in dissipation that is known to scale as the square root of the kinematic viscosity times the density of the gas. We observed that when an oscillating surface is modified with nanostructures, the experimentally measured dissipation shows an exponential dependence on kinematic viscosity. The surface nanostructures alter solid-gas interplay greatly, amplifying the dissipation response exponentially for even minute variations in viscosity. Nanostructured resonator thus allows discrimination of otherwise narrow range of gaseous viscosity making dissipation an ideal parameter for analysis of a gaseous media. We attribute the observed exponential enhancement to the stochastic nature of interactions of many coupled nanostructures with the gas media. PMID:27596851

  15. A nanostructured surface increases friction exponentially at the solid-gas interface

    NASA Astrophysics Data System (ADS)

    Phani, Arindam; Putkaradze, Vakhtang; Hawk, John E.; Prashanthi, Kovur; Thundat, Thomas

    2016-09-01

    According to Stokes’ law, a moving solid surface experiences viscous drag that is linearly related to its velocity and the viscosity of the medium. The viscous interactions result in dissipation that is known to scale as the square root of the kinematic viscosity times the density of the gas. We observed that when an oscillating surface is modified with nanostructures, the experimentally measured dissipation shows an exponential dependence on kinematic viscosity. The surface nanostructures alter solid-gas interplay greatly, amplifying the dissipation response exponentially for even minute variations in viscosity. Nanostructured resonator thus allows discrimination of otherwise narrow range of gaseous viscosity making dissipation an ideal parameter for analysis of a gaseous media. We attribute the observed exponential enhancement to the stochastic nature of interactions of many coupled nanostructures with the gas media.

  16. Coal/biomass fuels and the gas turbine: Utilization of solid fuels and their derivatives

    SciTech Connect

    DeCorso, M.; Newby, R.; Anson, D.; Wenglarz, R.; Wright, I.

    1996-06-01

    This paper discusses key design and development issues in utilizing coal and other solid fuels in gas turbines. These fuels may be burned in raw form or processed to produce liquids or gases in more or less refined forms. The use of such fuels in gas turbines requires resolution of technology issues which are of little or no consequence for conventional natural gas and refined oil fuels. For coal, these issues are primarily related to the solid form in which coal is naturally found and its high ash and contaminant levels. Biomass presents another set of issues similar to those of coal. Among the key areas discussed are effects of ash and contaminant level on deposition, corrosion, and erosion of turbine hot parts, with particular emphasis on deposition effects.

  17. Modeling of ultrasound transmission through a solid-liquid interface comprising a network of gas pockets

    NASA Astrophysics Data System (ADS)

    Paumel, K.; Moysan, J.; Chatain, D.; Corneloup, G.; Baqué, F.

    2011-08-01

    Ultrasonic inspection of sodium-cooled fast reactor requires a good acoustic coupling between the transducer and the liquid sodium. Ultrasonic transmission through a solid surface in contact with liquid sodium can be complex due to the presence of microscopic gas pockets entrapped by the surface roughness. Experiments are run using substrates with controlled roughness consisting of a network of holes and a modeling approach is then developed. In this model, a gas pocket stiffness at a partially solid-liquid interface is defined. This stiffness is then used to calculate the transmission coefficient of ultrasound at the entire interface. The gas pocket stiffness has a static, as well as an inertial component, which depends on the ultrasonic frequency and the radiative mass.

  18. Solid Sorbents for CO2 Capture from Post-Combustion and Pre-Combustion Gas Streams

    SciTech Connect

    Siriwardane, R.V.; Robinson, C.; Stevens, R.W.

    2007-08-01

    A novel liquid impregnated solid sorbent was developed for CO2 removal in the temperature range of ambient to 60 °C for both fixed bed and fluidized bed reactor applications. The sorbent is regenerable at 60-80 °C. Multi-cycle tests conducted in an atmospheric bench scale reactor with simulated flue gas demonstrated that the sorbent retains its CO2 sorption capacity with CO2 removal efficiency of about 99%. A second, novel solid sorbent containing mixture of alkali earth and alkali compounds was developed for CO2 removal at 200-315 °C from high pressure gas streams (i.e., suitable for IGCC systems). The sorbent showed very high capacity for CO2 removal from gas streams containing 28% CO2 at 200 °C and 11.2 atm during lab-scale flow reactor tests as well as regenerability at 375 °C.

  19. 2D fluid simulations of discharges at atmospheric pressure in reactive gas mixtures

    NASA Astrophysics Data System (ADS)

    Bourdon, Anne

    2015-09-01

    Since a few years, low-temperature atmospheric pressure discharges have received a considerable interest as they efficiently produce many reactive chemical species at a low energy cost. This potential is of great interest for a wide range of applications as plasma assisted combustion or biomedical applications. Then, in current simulations of atmospheric pressure discharges, there is the need to take into account detailed kinetic schemes. It is interesting to note that in some conditions, the kinetics of the discharge may play a role on the discharge dynamics itself. To illustrate this, we consider the case of the propagation of He-N2 discharges in long capillary tubes, studied for the development of medical devices for endoscopic applications. Simulation results put forward that the discharge dynamics and structure depend on the amount of N2 in the He-N2 mixture. In particular, as the amount of N2 admixture increases, the discharge propagation velocity in the tube increases, reaches a maximum for about 0 . 1 % of N2 and then decreases, in agreement with experiments. For applications as plasma assisted combustion with nanosecond repetitively pulsed discharges, there is the need to handle the very different timescales of the nanosecond discharge with the much longer (micro to millisecond) timescales of combustion processes. This is challenging from a computational point of view. It is also important to better understand the coupling of the plasma induced chemistry and the gas heating. To illustrate this, we present the simulation of the flame ignition in lean mixtures by a nanosecond pulsed discharge between two point electrodes. In particular, among the different discharge regimes of nanosecond repetitively pulsed discharges, a ``spark'' regime has been put forward in the experiments, with an ultra-fast local heating of the gas. For other discharge regimes, the gas heating is much weaker. We have simulated the nanosecond spark regime and have observed shock waves

  20. Effect of reactive gas (oxygen/chlorine/fluorine) etching on the magnetic flux of a high moment write pole material

    SciTech Connect

    Zhang Jinqiu; Liu Feng; Chen Lifan; Miloslavsky, Lena

    2010-05-15

    Effect of reactive gas (oxygen/chlorine/fluorine) etching on NiFe magnetic properties was investigated. Experimental data showed 40% magnetic property degradation for F-containing gas etching, 10% degradation for O-containing gas etching, and 5% degradation for Cl-containing gas etching processes. X-ray diffraction analysis indicated that the crystallographic orientation remained the same upon the reactive gas etching, which is due to the low ion energy in plasma etching process as opposed to ion milling process with high input energy. It is proposed that the reported magnetic property degradation was mainly caused by the nonmagnetic dead layer formation, rather than the changes in the crystallographic orientation. The dead layer was determined by the NiFe thickness dependence of remnant magnetic flux variations between pre-etched and postetched samples. The dead layer remained nearly constant for O-containing gas etching process with increasing plasma processing time. The nonmagnetic dead layer of {approx}40-50 A formed in O-containing etching gas was observed in transmission electron microscopy cross-sectional image and was in very good agreement with the calculated value based on magnetic flux measurements. Combined magnetic and physical characterizations suggest that the dead layer thickness saturates at the initial stage of the plasma etching and magnetic property remained unchanged with increasing etching duration upon formation of the dead layer.

  1. Decorative black TiCxOy film fabricated by DC magnetron sputtering without importing oxygen reactive gas

    NASA Astrophysics Data System (ADS)

    Ono, Katsushi; Wakabayashi, Masao; Tsukakoshi, Yukio; Abe, Yoshiyuki

    2016-02-01

    Decorative black TiCxOy films were fabricated by dc (direct current) magnetron sputtering without importing the oxygen reactive gas into the sputtering chamber. Using a ceramic target of titanium oxycarbide (TiC1.59O0.31), the oxygen content in the films could be easily controlled by adjustment of total sputtering gas pressure without remarkable change of the carbon content. The films deposited at 2.0 and 4.0 Pa, those are higher pressure when compared with that in conventional magnetron sputtering, showed an attractive black color. In particular, the film at 4.0 Pa had the composition of TiC1.03O1.10, exhibited the L* of 41.5, a* of 0.2 and b* of 0.6 in CIELAB color space. These values were smaller than those in the TiC0.29O1.38 films (L* of 45.8, a* of 1.2 and b* of 1.2) fabricated by conventional reactive sputtering method from the same target under the conditions of gas pressure of 0.3 Pa and optimized oxygen reactive gas concentration of 2.5 vol.% in sputtering gas. Analysis of XRD and XPS revealed that the black film deposited at 4.0 Pa was the amorphous film composed of TiC, TiO and C. The adhesion property and the heat resisting property were enough for decorative uses. This sputtering process has an industrial advantage that the decorative black coating with color uniformity in large area can be easily obtained by plain operation because of unnecessary of the oxygen reactive gas importing which is difficult to be controlled uniformly in the sputtering chamber.

  2. A fully coupled model for water-gas-heat reactive transport with methane oxidation in landfill covers.

    PubMed

    Ng, C W W; Feng, S; Liu, H W

    2015-03-01

    Methane oxidation in landfill covers is a complex process involving water, gas and heat transfer as well as microbial oxidation. The coupled phenomena of microbial oxidation, water, gas, and heat transfer are not fully understood. In this study, a new model is developed that incorporates water-gas-heat coupled reactive transport in unsaturated soil with methane oxidation. Effects of microbial oxidation-generated water and heat are included. The model is calibrated using published data from a laboratory soil column test. Moreover, a series of parametric studies are carried out to investigate the influence of microbial oxidation-generated water and heat, initial water content on methane oxidation efficiency. Computed and measured results of gas concentration and methane oxidation rate are consistent. It is found that the coupling effects between water-gas-heat transfer and methane oxidation are significant. Ignoring microbial oxidation-generated water and heat can result in a significant difference in methane oxidation efficiency by 100%.

  3. Enhanced tunability of the composition in silicon oxynitride thin films by the reactive gas pulsing process

    NASA Astrophysics Data System (ADS)

    Aubry, Eric; Weber, Sylvain; Billard, Alain; Martin, Nicolas

    2014-01-01

    Silicon oxynitride thin films were sputter deposited by the reactive gas pulsing process. Pure silicon target was sputtered in Ar, N2 and O2 mixture atmosphere. Oxygen gas was periodically and solely introduced using exponential signals. In order to vary the injected O2 quantity in the deposition chamber during one pulse at constant injection time (TON), the tau mounting time τmou of the exponential signals was systematically changed for each deposition. Taking into account the real-time measurements of the discharge voltage and the I(O*)/I(Ar*) emission lines ratio, it is shown that the oscillations of the discharge voltage during the TON and TOFF times (injection of O2 stopped) are attributed to the preferential adsorption of the oxygen compared to that of the nitrogen. The sputtering mode alternates from a fully nitrided mode (TOFF time) to a mixed mode (nitrided and oxidized mode) during the TON time. For the highest injected O2 quantities, the mixed mode tends toward a fully oxidized mode due to an increase of the trapped oxygen on the target. The oxygen (nitrogen) concentration in the SiOxNy films similarly (inversely) varies as the oxygen is trapped. Moreover, measurements of the contamination speed of the Si target surface are connected to different behaviors of the process. At low injected O2 quantities, the nitrided mode predominates over the oxidized one during the TON time. It leads to the formation of Si3N4-yOy-like films. Inversely, the mixed mode takes place for high injected O2 quantities and the oxidized mode prevails against the nitrided one producing SiO2-xNx-like films.

  4. Solution or solid - it doesn't matter: visible light-induced CO release reactivity of zinc flavonolato complexes.

    PubMed

    Anderson, Stacey N; Larson, Michael T; Berreau, Lisa M

    2016-09-20

    Two types of zinc flavonolato complexes ([(6-Ph2TPA)Zn(flavonolato)]ClO4 and Zn(flavonolato)2) of four extended flavonols have been prepared, characterized, and evaluated for visible light-induced CO release reactivity. Zinc coordination of each flavonolato anion results in a red-shift of the lowest energy absorption feature and in some cases enhanced molar absorptivity relative to the free flavonol. The zinc-coordinated flavonolato ligands undergo visible light-induced CO release with enhanced reaction quantum yields relative to the neutral flavonols. Most notable is the discovery that both types of zinc flavonolato derivatives undergo similar visible light-induced CO release reactivity in solution and in the solid state. A solid film of a Zn(flavonolato)2 derivative was evaluated as an in situ CO release agent for aerobic oxidative palladium-catalyzed alkoxycarbonylation to produce esters in ethanol. The CO release product was found to undergo ester alcolysis under the conditions of the carbonylation reaction.

  5. Atmospheric reactivity of hydroxyl radicals with guaiacol (2-methoxyphenol), a biomass burning emitted compound: Secondary organic aerosol formation and gas-phase oxidation products

    NASA Astrophysics Data System (ADS)

    Lauraguais, Amélie; Coeur-Tourneur, Cécile; Cassez, Andy; Deboudt, Karine; Fourmentin, Marc; Choël, Marie

    2014-04-01

    Methoxyphenols are low molecular weight semi-volatile polar aromatic compounds produced from the pyrolysis of wood lignin. The reaction of guaiacol (2-methoxyphenol) with hydroxyl radicals has been studied in the LPCA simulation chamber at (294 ± 2) K, atmospheric pressure, low relative humidity (RH < 1%) and under high-NOx conditions using CH3ONO as OH source. The aerosol production was monitored using a SMPS (Scanning Mobility Particle Sizer); the SOA yields were in the range from 0.003 to 0.87 and the organic aerosol formation can be expressed by a one-product gas/particle partitioning absorption model. Transmission (TEM) and Scanning (SEM) Electron Microscopy observations were performed to characterize the physical state of SOA produced from the OH reaction with guaiacol; they display both liquid and solid particles (in an amorphous state). GC-FID (Gas Chromatography - Flame Ionization Detection) and GC-MS (Gas Chromatography - Mass Spectrometry) analysis show the formation of nitroguaiacol isomers as main oxidation products in the gas- and aerosol-phases. In the gas-phase, the formation yields were (10 ± 2) % for 4-nitroguaiacol (1-hydroxy-2-methoxy-4-nitrobenzene; 4-NG) and (6 ± 2) % for 3- or 6-nitroguaiacol (1-hydroxy-2-methoxy-3-nitrobenzene or 1-hydroxy-2-methoxy-6-nitrobenzene; 3/6-NG; the standards are not commercially available so both isomers cannot be distinguished) whereas in SOA their yield were much lower (≤0.1%). To our knowledge, this work represents the first identification of nitroguaiacols as gaseous oxidation products of the OH reaction with guaiacol. As the reactivity of nitroguaiacols with atmospheric oxidants is probably low, we suggest using them as biomass burning emission gas tracers. The atmospheric implications of the guaiacol + OH reaction are also discussed.

  6. Reactive greenhouse gas scenarios: Systematic exploration of uncertainties and the role of atmospheric chemistry

    NASA Astrophysics Data System (ADS)

    Prather, Michael J.; Holmes, Christopher D.; Hsu, Juno

    2012-05-01

    Knowledge of the atmospheric chemistry of reactive greenhouse gases is needed to accurately quantify the relationship between human activities and climate, and to incorporate uncertainty in our projections of greenhouse gas abundances. We present a method for estimating the fraction of greenhouse gases attributable to human activities, both currently and for future scenarios. Key variables used to calculate the atmospheric chemistry and budgets of major non-CO2 greenhouse gases are codified along with their uncertainties, and then used to project budgets and abundances under the new climate-change scenarios. This new approach uses our knowledge of changing abundances and lifetimes to estimate current total anthropogenic emissions, independently and possibly more accurately than inventory-based scenarios. We derive a present-day atmospheric lifetime for methane (CH4) of 9.1 ± 0.9 y and anthropogenic emissions of 352 ± 45 Tg/y (64% of total emissions). For N2O, corresponding values are 131 ± 10 y and 6.5 ± 1.3 TgN/y (41% of total); and for HFC-134a, the lifetime is 14.2 ± 1.5 y.

  7. Gas-Phase Reactivity of Cesium-Containing Species by Quantum Chemistry.

    PubMed

    Šulková, Katarína; Cantrel, Laurent; Louis, Florent

    2015-09-03

    Thermodynamics and kinetics of cesium species reactions have been studied by using high-level quantum chemical tools. A systematic theoretical study has been done to find suitable methodology for calculation of reliable thermodynamic properties, allowing us to determine bimolecular rate constants with appropriate kinetic theories of gas-phase reactions. Four different reactions have been studied in this work: CsO + H2 = CsOH + H (R1), Cs + HI = CsI + H (R2), CsI + H2O = CsOH + HI (R3), and CsI + OH = CsOH + I (R4). All reactions involve steam, hydrogen, and iodine in addition of cesium. Most of the reactions are fast and (R3) and (R4) proceed even without energetic barrier. In terms of chemical reactivity in the reactor coolant system (RCS) in the case of severe accident, it can be expected that there will be no kinetic limitations for main cesium species (CsOH and CsI) transported along the RCS. Cs chemical speciation inside the RCS should be governed by the thermodynamics.

  8. Feasibility of gas/solid carboligation: conversion of benzaldehyde to benzoin using thiamine diphosphate-dependent enzymes.

    PubMed

    Mikolajek, R; Spiess, A C; Büchs, J

    2007-05-10

    A carboligation was investigated for the first time as an enzymatic gas phase reaction, where benzaldehyde was converted to benzoin using thiamine diphosphate (ThDP)-dependent enzymes, namely benzaldehyde lyase (BAL) and benzoylformate decarboxylase (BFD). The biocatalyst was immobilized per deposition on non-porous support. Some limitations of the gas/solid biocatalysis are discussed based on this carboligation and it is also demonstrated that the solid/gas system is an interesting tool for more volatile products.

  9. Greenhouse gas emissions from solid waste in Beijing: The rising trend and the mitigation effects by management improvements.

    PubMed

    Yu, Yongqiang; Zhang, Wen

    2016-04-01

    Disposal of solid waste poses great challenges to city managements. Changes in solid waste composition and disposal methods, along with urbanisation, can certainly affect greenhouse gas emissions from municipal solid waste. In this study, we analysed the changes in the generation, composition and management of municipal solid waste in Beijing. The changes of greenhouse gas emissions from municipal solid waste management were thereafter calculated. The impacts of municipal solid waste management improvements on greenhouse gas emissions and the mitigation effects of treatment techniques of greenhouse gas were also analysed. Municipal solid waste generation in Beijing has increased, and food waste has constituted the most substantial component of municipal solid waste over the past decade. Since the first half of 1950s, greenhouse gas emission has increased from 6 CO2-eq Gg y(-1)to approximately 200 CO2-eq Gg y(-1)in the early 1990s and 2145 CO2-eq Gg y(-1)in 2013. Landfill gas flaring, landfill gas utilisation and energy recovery in incineration are three techniques of the after-emission treatments in municipal solid waste management. The scenario analysis showed that three techniques might reduce greenhouse gas emissions by 22.7%, 4.5% and 9.8%, respectively. In the future, if waste disposal can achieve a ratio of 4:3:3 by landfill, composting and incineration with the proposed after-emission treatments, as stipulated by the Beijing Municipal Waste Management Act, greenhouse gas emissions from municipal solid waste will decrease by 41%.

  10. Dispersed bubble reactor for enhanced gas-liquid-solids contact and mass transfer

    DOEpatents

    Vimalchand, Pannalal; Liu, Guohai; Peng, WanWang; Bonsu, Alexander

    2016-01-26

    An apparatus to promote gas-liquid contact and facilitate enhanced mass transfer. The dispersed bubble reactor (DBR) operates in the dispersed bubble flow regime to selectively absorb gas phase constituents into the liquid phase. The dispersion is achieved by shearing the large inlet gas bubbles into fine bubbles with circulating liquid and additional pumped liquid solvent when necessary. The DBR is capable of handling precipitates that may form during absorption or fine catalysts that may be necessary to promote liquid phase reactions. The DBR can be configured with multistage counter current flow sections by inserting concentric cylindrical sections into the riser to facilitate annular flow. While the DBR can absorb CO.sub.2 in liquid solvents that may lead to precipitates at high loadings, it is equally capable of handling many different types of chemical processes involving solids (precipitates/catalysts) along with gas and liquid phases.

  11. Alpha-tricalcium phosphate (α-TCP): solid state synthesis from different calcium precursors and the hydraulic reactivity.

    PubMed

    Cicek, Gulcin; Aksoy, Eda Ayse; Durucan, Caner; Hasirci, Nesrin

    2011-04-01

    The effects of solid state synthesis process parameters and primary calcium precursor on the cement-type hydration efficiency (at 37 °C) of α-tricalcium phosphate (Ca(3)(PO(4))(2) or α-TCP) into hydroxyapatite (Ca(10-x)HPO(4)(PO(4))(6-x)(OH)(2-x) x = 0-1, or HAp) have been investigated. α-TCP was synthesized by firing of stoichiometric amount of calcium carbonate (CaCO(3)) and monetite (CaHPO(4)) at 1150-1350 °C for 2 h. Three commercial grade CaCO(3) powders of different purity were used as the starting material and the resultant α-TCP products for all synthesis routes were compared in terms of the material properties and the reactivity. The reactant CaHPO(4) was also custom synthesized from the respective CaCO(3) source. A low firing temperature in the range of 1150-1350°C promoted formation of β-polymorph as a second phase in the resultant TCP. Meanwhile, higher firing temperatures resulted in phase pure α-TCP with poor hydraulic reactivity. The extension of firing operation also led to a decrease in the reactivity. It was found that identical synthesis history, morphology, particle size and crystallinity match between the α-TCPs produced from different CaCO(3) sources do not essentially culminate in products exhibiting similar hydraulic reactivity. The changes in reactivity are arising from differences in the trace amount of impurities found in the CaCO(3) precursors. In this regard, a correlation between the observed hydraulic reactivities and the impurity content of the CaCO(3) powders--as determined by inductively coupled plasma mass spectrometry--has been established. A high level of magnesium impurity in the CaCO(3) almost completely hampers the hydration of α-TCP. This impurity also favors formation of β- instead of α-polymorph in the product of TCP upon firing.

  12. FIELD TEST MEASUREMENTS AT FIVE MUNICIPAL SOLID WASTE LANDFILLS WITH LANDFILL GAS CONTROL TECHNOLOGY--FINAL REPORT

    EPA Science Inventory

    Research was conducted to evaluate landfill gas emissions at five municipal solid waste landfills which have modern control technology for landfill gas emissions. Comprehensive testing was conducted on the raw landfill gas and the combustion outlet exhaust. The project had two ...

  13. Effect of particle inertia on fluid turbulence in gas-solid disperse flow

    NASA Astrophysics Data System (ADS)

    Mito, Yoichi

    2016-11-01

    The effect of particle inertia on the fluid turbulence in gas-solid disperse flow through a vertical channel has been examined by using a direct numerical simulation, to calculate the gas velocities seen by the particles, and a simplified non-stationary flow model, in which a uniform distribution of solid spheres of density ratio of 1000 are added into the fully-developed turbulent gas flow in an infinitely wide channel. The gas flow is driven downward with a constant pressure gradient. The frictional Reynolds number defined with the frictional velocity before the addition of particles, v0*, is 150. The feedback forces are calculated using a point force method. Particle diameters of 0.95, 1.3 and 1.9, which are made dimensionless with v0* and the kinematic viscosity, and volume fractions, ranging from 1 ×10-4 to 2 ×10-3 , in addition to the one-way coupling cases, are considered. Gravitational effect is not clearly seen where the fluid turbulence is damped by feedback effect. Gas flow rate increases with the decrease in particle inertia, that causes the increase in feedback force. Fluid turbulence decreases with the increase in particle inertia, that causes the increase in diffusivity of feedback force and of fluid turbulence. This work was supported by JSPS KAKENHI Grant Number 26420097.

  14. Semi-wet flue gas desulfurization with a multi-solid fluidized bed

    SciTech Connect

    Lei, Z.; Wu, C.; Xu, B.; Chen, Y.; Liu, B.

    1997-12-31

    In this study, the authors put forward a new flue gas desulfurization process with a Multi-Solid Fluidized Bed. The principle of the method is as follows. The flue gas is supplied to the bottom of the fluidized bed and lime/limestone slurry is dropped from the top to a bed of the coarse particles. The slurry is uniformly dispersed in the bed by the fluidizing coarse particles, so that the slurry can make contact with the flue gas sufficiently. Dried fine particles of desulfurization product are entrained to the gas-solid separator. In this system, the drying process of the slurry is a key point. During the primary work, they investigated the drying mechanism of the limestone slurry containing fine particles in the coarse particle bed. The desulfurization performance of a simulated flue gas has been carried out. It is concluded that: (1) the drying process of the slurry is mainly one of the water involved; (2) the slurry drying process can be separated into two steps with constant and decreasing velocity, respectively; and (3) using this apparatus, more than 95% SO{sub 2} removal can be obtained when Ca/S equals 2.

  15. Solar-wind krypton and solid/gas fractionation in the early solar nebula

    NASA Technical Reports Server (NTRS)

    Wiens, Roger C.; Burnett, D. S.; Neugebauer, M.; Pepin, R. O.

    1991-01-01

    The solar-system Kr abundance is calculated from solar-wind noble-gas ratios, determined previously by low-temperature oxidations of lunar ilmenite grains, normalized to Si by spacecraft solar-wind measurements. The estimated Kr-83 abundance of 4.1 + or - 1.5 per million Si atoms is within uncertainty of estimates assuming no fractionation, determined from CI-chondrite abundances of surrounding elements. This is significant because it is the first such constraint on solid/gas fractionation, though the large uncertainty only confines it to somewhat less than a factor of two.

  16. Gas-Induced Transformation and Expansion of a Non-Porous Organic Solid

    SciTech Connect

    Thallapally, Praveen K.; McGrail, B. Peter; Dalgarno, Scott J.; Schaef, Herbert T.; Tian, Jian; Atwood, Jerry L.

    2008-02-01

    At high pressure and temperature, it is possible to transform the high density thermodynamic form of a well known organic host (p-tert-butylcalix[4]arene) to the low density kinetic form and vice versa. This transformation involves converting a material that is effectively inactive with respect to gas sorption, into the form that has large lattice voids and that is sorptive under normal experimental conditions, despite the high density form being devoid of channels or porosity. Remarkably, particular gas molecules appear to diffuse through the solid into small lattice voids, and effect the transformation to the low density kinetic form, which involves significant expansion of the crystalline organic lattice.

  17. Preparation and analysis of high reactive Zn-Ti-O hot gas sulfur sorbents

    SciTech Connect

    Xu Deping

    1997-12-31

    Three hot gas desulfurization sorbents (HGSS) was prepared by plain mixing of powder ZnCO{sub 3} and TiO{sub 2} in a conical agitator, by vibrating, grinding and mixing of the same material, and by co-precipitating of ZnCO{sub 3} and Ti(SO{sub 4}){sub 2} using NH{sub 3}H{sub 2}O or (NH{sub 4}){sub 2}CO{sub 3} as precipitating agent. Calcining temperature was 1,030 K, and Zn/Ti atom ratio was 2/1. Sulfidation performance was tested in a quartz tube at 923 K, space speed being 10,000 h{sup {minus}1} , H{sub 2}S being 0.5% (v/v). The author found that the desulfurization activity of co-precipitating HGSS was two times that of plain mixing HGSS; the grinding mixing HGSS was similar to co-precipitating HGSS. The three sorbents were characterized by XRD and SEM analysis. The breakthrough curve and solid conversion are discussed in terms of grain size, crystalline state, inactive nucleus of crystallization, and the generating course of zinc titanate of each sorbent.

  18. Hyperfine dipole-dipole broadening of selective reflection spectroscopy at the gas-solid interface

    NASA Astrophysics Data System (ADS)

    Meng, Tengfei; Ji, Zhonghua; Zhao, Yanting; Xiao, Liantuan; Jia, Suotang

    2016-09-01

    We theoretically and experimentally investigate hyperfine dipole-dipole broadening in the selective reflection (SR) spectroscopy at the gas-solid interface with the atomic density of 1014-1015 cm-3. The two-level SR theory considering pump beam and dipole-dipole interaction between excited-state atom and ground-state atom is presented. The numerical simulation of the SR spectrum is in agreement with experimental results. The reduction of spectral width is observed by introducing a pump beam which is an effective technique to improve the resolution of spectroscopy. We analyze the dependence of dipole-dipole broadening on atomic density and pump beam power. This study is helpful for the description of the SR spectroscopy at the gas-solid interface where the Doppler broadening is comparable with dipole-dipole broadening.

  19. Characteristics of dilute gas-solids suspensions in drag reducing flow

    NASA Technical Reports Server (NTRS)

    Kane, R. S.; Pfeffer, R.

    1973-01-01

    Measurements were performed on dilute flowing gas-solids suspensions and included data, with particles present, on gas friction factors, velocity profiles, turbulence intensity profiles, turbulent spectra, and particle velocity profiles. Glass beads of 10 to 60 micron diameter were suspended in air at Reynolds numbers of 10,000 to 25,000 and solids loading ratios from 0 to 4. Drag reduction was achieved for all particle sizes in vertical flow and for the smaller particle sizes in horizontal flow. The profile measurements in the vertical tube indicated that the presence of particles thickened the viscous sublayer. A quantitative theory based on particle-eddy interaction and viscous sublayer thickening has been proposed.

  20. Solid-gas reactions driven by mechanical alloying of niobium and tantalum in nitrogen

    SciTech Connect

    Liu, L.; Lu, L.; Chen, L.; Qin, Y.; Zhang, L.D.

    1999-04-01

    Solid-gas reactions of niobium and tantalum with molecular nitrogen driven by mechanical alloying (MA) have been investigated by X-ray diffraction, transmission electron microscopy, and differential thermal analysis. It was found that the phase transition followed a sequence of Nb{sub 2}N {r_arrow} Nb{sub 3}N{sub 4} {r_arrow} NbN when Nb was milled with N{sub 2}. The chemosorption of nitrogen onto the clean metal surfaces created by ball milling is believed to be the fundamental process governing solid-gas reactions, and the defects generated during MA can promote the diffusion of adsorbed nitrogen, and consequently the formation of metal nitrides. The difference in phase transition between the two systems is discussed.

  1. TiN films fabricated by reactive gas pulse sputtering: A hybrid design of multilayered and compositionally graded structures

    NASA Astrophysics Data System (ADS)

    Yang, Jijun; Zhang, Feifei; Wan, Qiang; Lu, Chenyang; Peng, Mingjing; Liao, Jiali; Yang, Yuanyou; Wang, Lumin; Liu, Ning

    2016-12-01

    Reactive gas pulse (RGP) sputtering approach was used to prepare TiN thin films through periodically changing the N2/Ar gas flow ratio. The obtained RGPsbnd TiN film possessed a hybrid architecture containing compositionally graded and multilayered structures, composed of hcp Ti-phase and fcc TiN-phase sublayers. Meanwhile, the RGP-TiN film exhibited a composition-oscillation along the film thickness direction, where the Ti-phase sublayer had a compositional gradient and the TiN-phase retained a constant stoichiometric ratio of Ti:N ≈ 1. The film modulation ratio λ (the thicknesses ratio of the Ti and TiN-phase sublayer) can be effectively tuned by controlling the undulation behavior of the N2 partial flow rate. Detailed analysis showed that this hybrid structure originated from a periodic transition of the film growth mode during the reactive sputtering process.

  2. Characterization of landfill gas composition at the Fresh Kills municipal solid-waste landfill

    SciTech Connect

    Eklund, B.; Anderson, E.P.; Walker, B.L.; Burrows, D.B.

    1998-08-01

    The most common disposal method in the US for municipal solid waste (MSW) is burial in landfills. Until recently, air emissions from these landfills were not regulated. Under the New Source Performance Standards and Emission Guidelines for MSW landfills, MSW operators are required to determine the nonmethane organic gas generation rate of their landfill through modeling and/or measurements. This paper summarizes speciated nonmethane organic compound (NMOC) measurement data collected during an intensive, short-term field program. Over 250 separate landfill gas samples were collected from emission sources at the Fresh Kills landfill in New York City and analyzed for approximately 150 different analytes. The average total NMOC value for the landfill was 438 ppmv (as hexane) versus the regulatory default value of 4,000 ppmv (as hexane). Over 70 individual volatile organic compounds (VOCs) were detected and quantified in the landfill gas samples. The typical gas composition for this landfill was determined as well as estimates of the spatial, temporal, and measurement variability in the gas composition. The data for NMOC show that the gas composition within the landfill is equivalent to the composition of the gas exiting the landfill through passive vents and through the soil cover.

  3. Compatibility of Space Nuclear Power Plant Materials in an Inert He/Xe Working Gas Containing Reactive Impurities

    SciTech Connect

    MM Hall

    2006-01-31

    A major materials selection and qualification issue identified in the Space Materials Plan is the potential for creating materials compatibility problems by combining dissimilar reactor core, Brayton Unit and other power conversion plant materials in a recirculating, inert He/Xe gas loop containing reactive impurity gases. Reported here are results of equilibrium thermochemical analyses that address the compatibility of space nuclear power plant (SNPP) materials in high temperature impure He gas environments. These studies provide early information regarding the constraints that exist for SNPP materials selection and provide guidance for establishing test objectives and environments for SNPP materials qualification testing.

  4. Measurement of Gas Velocities in the Presence of Solids in the Riser of a Cold Flow Circulating Fluidized Bed

    SciTech Connect

    Spenik, J.; Ludlow, J.C.; Compston, R.; Breault, R.W.

    2007-01-01

    The local gas velocity and the intensity of the gas turbulence in a gas/solid flow are a required measurement in validating the gas and solids flow structure predicted by computational fluid dynamic (CFD) models in fluid bed and transport reactors. The high concentration and velocities of solids, however, make the use of traditional gas velocity measurement devices such as pitot tubes, hot wire anemometers and other such devices difficult. A method of determining these velocities has been devised at the National Energy Technology Laboratory employing tracer gas. The technique developed measures the time average local axial velocity gas component of a gas/solid flow using an injected tracer gas which induces changes in the heat transfer characteristics of the gas mixture. A small amount of helium is injected upstream a known distance from a self-heated thermistor. The thermistor, protected from the solids by means of a filter, is exposed to gases that are continuously extracted from the flow. Changes in the convective heat transfer characteristics of the gas are indicated by voltage variations across a Wheatstone bridge. When pulsed injections of helium are introduced to the riser flow the change in convective heat transfer coefficient of the gas can be rapidly and accurately determined with this instrument. By knowing the separation distance between the helium injection point and the thermistor extraction location as well as the time delay between injection and detection, the gas velocity can easily be calculated. Variations in the measured gas velocities also allow the turbulence intensity of the gas to be estimated.

  5. Compilation and evaluation of gas phase diffusion coefficients of reactive trace gases in the atmosphere: volume 1. Inorganic compounds

    NASA Astrophysics Data System (ADS)

    Tang, M. J.; Cox, R. A.; Kalberer, M.

    2014-09-01

    Diffusion of gas molecules to the surface is the first step for all gas-surface reactions. Gas phase diffusion can influence and sometimes even limit the overall rates of these reactions; however, there is no database of the gas phase diffusion coefficients of atmospheric reactive trace gases. Here we compile and evaluate, for the first time, the diffusivities (pressure-independent diffusion coefficients) of atmospheric inorganic reactive trace gases reported in the literature. The measured diffusivities are then compared with estimated values using a semi-empirical method developed by Fuller et al. (1966). The diffusivities estimated using Fuller's method are typically found to be in good agreement with the measured values within ±30%, and therefore Fuller's method can be used to estimate the diffusivities of trace gases for which experimental data are not available. The two experimental methods used in the atmospheric chemistry community to measure the gas phase diffusion coefficients are also discussed. A different version of this compilation/evaluation, which will be updated when new data become available, is uploaded online (https://sites.google.com/site/mingjintang/home/diffusion).

  6. Preparation of highly selective solid-phase extractants for Cibacron reactive dyes using molecularly imprinted polymers.

    PubMed

    Al-Degs, Yahya S; Abu-Surrah, Adnan S; Ibrahim, Khalid A

    2009-02-01

    Selective polymeric extractants were prepared for preconcentration of Cibacron reactive red dye, a dye that is often applied with Cibacron reactive blue and Cibacron reactive yellow for dyeing of fabrics. The best extractant was fabricated (in chloroform) using methacrylic acid (as monomer), ethylene glycol dimethacrylate (as crosslinker), AIBN (as initiator for polymerization), and red dye as template molecule, with a molar stoichiometric ratio of 8.0:40.0:2.5:0.63, respectively. The structure of the molecularly imprinted polymer (MIP) was robust, and resisted dissolution up to 260 degrees C. Compared with the un-imprinted polymer, the imprinted product has a large specific surface area which improved its adsorption capacity. The effect of imprinting was obvious from the adsorption capacity measured at pH 4 for red dye (the imprinted molecule), which was increased from 24.0 to 79.3 mg g(-1) after imprinting. Equilibrium adsorption studies revealed that the dye-imprinted-polymer enables efficient extraction of red dye even in the presence of blue and yellow dyes which have similar chemical natures to the red dye. The selectivity coefficients S (red dye/dye), were 13.9 and 17.1 relative to the yellow and blue dyes, respectively. The MIP was found to be effective for red dye preconcentration, with a preconcentration factor of 100, from tap water and treated textile wastewater. The factors affecting extraction of red dye by the MIP were studied and optimized. Under the optimized extraction conditions, red dye was selectively quantified in the presence of other competing dyes at a concentration of 20 microg L(-1) from different water systems with satisfactory recoveries (91-95%) and RSD values (approximately 5.0%).

  7. An innovative gas-solid torbed reactor for the recycling industries

    NASA Astrophysics Data System (ADS)

    Dodson, C. E.; Lakshmanan, V. I.

    1998-07-01

    Gas-solid Torbed reactors have been developed for processing a wide range of materials. The reactors have facilitated several novel recycling projects in countries where they are used. One of the major advantages of these reactors when applied to the recycling industries is the compactness of the plant and its inherent ability to be scaled down and fully automated to better match the volume requirements of this sector.

  8. Prototype demonstration of dual sorbent injection for acid gas control on municipal solid waste combustion units

    SciTech Connect

    1994-05-01

    This report gathered and evaluated emissions and operations data associated with furnace injection of dry hydrated lime and duct injection of dry sodium bicarbonate at a commercial, 1500 ton per day, waste-to-energy facility. The information compiled during the project sheds light on these sorbents to affect acid gas emissions from municipal solid waste combustors. The information assesses the capability of these systems to meet the 1990 Clean Air Act and 1991 EPA Emission Guidelines.

  9. Solid sorbents for removal of carbon dioxide from gas streams at low temperatures

    DOEpatents

    Sirwardane, Ranjani V.

    2005-06-21

    New low-cost CO.sub.2 sorbents are provided that can be used in large-scale gas-solid processes. A new method is provided for making these sorbents that involves treating substrates with an amine and/or an ether so that the amine and/or ether comprise at least 50 wt. percent of the sorbent. The sorbent acts by capturing compounds contained in gaseous fluids via chemisorption and/or physisorption between the unit layers of the substrate's lattice where the polar amine liquids and solids and/or polar ether liquids and solids are located. The method eliminates the need for high surface area supports and polymeric materials for the preparation of CO.sub.2 capture systems, and provides sorbents with absorption capabilities that are independent of the sorbents' surface areas. The sorbents can be regenerated by heating at temperatures in excess of 35.degree. C.

  10. Solid Sorbents for Removal of Carbon Dioxide from Gas Streams at Low Temperatures

    SciTech Connect

    Sirwardane, Ranjani V.

    2005-06-21

    New low-cost CO2 sorbents are provided that can be used in large-scale gas-solid processes. A new method is provided for making these sorbents that involves treating substrates with an amine and/or an ether so that the amine and/or ether comprise at least 50 wt. percent of the sorbent. The sorbent acts by capturing compounds contained in gaseous fluids via chemisorption and/or physisorption between the unit layers of the substrate's lattice where the polar amine liquids and solids and/or polar ether liquids and solids are located. The method eliminates the need for high surface area supports and polymeric materials for the preparation of CO2 capture systems, and provides sorbents with absorption capabilities that are independent of the sorbents' surface areas. The sorbents can be regenerated by heating at temperatures in excess of 35 degrees C.

  11. Acoustic probe for the characterization of solid-gas- liquid slurries

    NASA Astrophysics Data System (ADS)

    Norato, Michael Anthony

    1999-10-01

    The development of nuclear weapons technology during the Cold War Era has left a legacy of large quantities of radioactive waste which are stored throughout the US Department of Energy (US DOE) Nuclear Weapons Complex. During the proposed remediation stages of processing, it will be necessary to characterize and monitor these waste slurries by remote methods. Acoustic probes have shown promise because of their non- intrusive nature and ability to penetrate optically opaque slurries. A forward theory for the acoustic response in both dilute and concentrated solid liquid slurries is developed. It is based on ensemble averaging of the equations of motion in the solid and liquid phases to obtain expressions for the ``effective properties'' of the slurry mixture in terms of coefficients which appear in the equations of motion for the solid particle. The attenuations predicted from the theory are in generally good agreement with the experimental data obtained by Toneburst and Pulse/FFT data acquisition methods for solid-liquid slurries of soda-lime glass particles of 14.9 μm and 65 μm mean radius and polystyrene particles of 79 gm radius at concentrations ranging from 5% to 50% solids by volume. The forward theory is readily extended to systems containing more than one dispersed phase, such as particles and gas bubbles, and the theory predictions are observed to be in good agreement with preliminary attenuation data obtained in solid-gas-liquid slurries of soda-lime glass particles of 14.9 gm mean radius at 5% and 10% by volume and gas bubbles ranging from approximately 25 μm to 150 μm radius at volume fractions on the order of 10-5. An inverse theory is also developed to determine the concentration and solids volume fraction distribution in a solid-liquid slurry given its experimentally obtained acoustic response. A Tikhonov scheme is employed to regularize the ill-posed integro-differential equations and solve them as a linear programming problem. Solution of the

  12. Non-intrusive measurement and hydrodynamics characterization of gas-solid fluidized beds: a review

    NASA Astrophysics Data System (ADS)

    Sun, Jingyuan; Yan, Yong

    2016-11-01

    Gas-solid fluidization is a well-established technique to suspend or transport particles and has been applied in a variety of industrial processes. Nevertheless, our knowledge of fluidization hydrodynamics is still limited for the design, scale-up and operation optimization of fluidized bed reactors. It is, therefore, essential to characterize the two-phase flow behaviours in gas-solid fluidized beds and monitor the fluidization processes for control and optimization. A range of non-intrusive techniques have been developed or proposed for measuring the fluidization dynamic parameters and monitoring the flow status without disturbing or distorting the flow fields. This paper presents a comprehensive review of the non-intrusive measurement techniques and the current state of knowledge and experience in the characterization and monitoring of gas-solid fluidized beds. These techniques are classified into six main categories as per sensing principles, electrostatic, acoustic emission and vibration, visualization, particle tracking, laser Doppler anemometry and phase Doppler anemometry as well as pressure-fluctuation methods. Trends and future developments in this field are also discussed.

  13. Possibilities of mercury removal in the dry flue gas cleaning lines of solid waste incineration units.

    PubMed

    Svoboda, Karel; Hartman, Miloslav; Šyc, Michal; Pohořelý, Michael; Kameníková, Petra; Jeremiáš, Michal; Durda, Tomáš

    2016-01-15

    Dry methods of the flue gas cleaning (for HCl and SO2 removal) are useful particularly in smaller solid waste incineration units. The amount and forms of mercury emissions depend on waste (fuel) composition, content of mercury and chlorine and on the entire process of the flue gas cleaning. In the case of high HCl/total Hg molar ratio in the flue gas, the majority (usually 70-90%) of mercury is present in the form of HgCl2 and a smaller amount in the form of mercury vapors at higher temperatures. Removal of both main forms of mercury from the flue gas is dependent on chemical reactions and sorption processes at the temperatures below approx. 340 °C. Significant part of HgCl2 and a small part of elemental Hg vapors can be adsorbed on fly ash and solid particle in the air pollution control (APC) processes, which are removed in dust filters. Injection of non-impregnated active carbon (AC) or activated lignite coke particles is able to remove mainly the oxidized Hg(2+) compounds. Vapors of metallic Hg(o) are adsorbed relatively weakly. Much better chemisorption of Hg(o) together with higher sorbent capacity is achieved by AC-based sorbents impregnated with sulfur, alkali poly-sulfides, ferric chloride, etc. Inorganic sorbents with the same or similar chemical impregnation are also applicable for deeper Hg(o) removal (over 85%). SCR catalysts convert part of Hg(o) into oxidized compounds (HgO, HgCl2, etc.) contributing to more efficient Hg removal, but excess of NH3 has a negative effect. Both forms, elemental Hg(o) and HgCl2, can be converted into HgS particles by reacting with droplets/aerosol of poly-sulfides solutions/solids in flue gas. Mercury captured in the form of water insoluble HgS is more advantageous in the disposal of solid waste from APC processes. Four selected options of the dry flue gas cleaning with mercury removal are analyzed, assessed and compared (in terms of efficiency of Hg-emission reduction and costs) with wet methods and retrofits for more

  14. Solid State Structure-Reactivity Studies on Bixbyites, Fluorites and Perovskites Belonging to the Vanadate, Titanate and Cerate Families

    NASA Astrophysics Data System (ADS)

    Shafi, Shahid P.

    This thesis primarily focuses on the systematic understanding of structure-reactivity relationships in two representative systems: bixbyite and related structures as well as indium doped CeO2. Topotactic reaction routes have gained significant attention over the past two decades due to their potential to access kinetically controlled metastable materials. This has contributed substantially to the understanding of solid state reaction pathways and provided first insights into mechanisms. Contrary to the widely used ex-situ methods, in-situ techniques including powder x-ray diffraction and thermogravimetric-differential thermal analysis have been employed extensively throughout this work in order to follow the reaction pathways in real time. Detailed analysis of the AVO3 (A = In, Sc) bixbyite reactivity under oxidative conditions has been carried out and a variety of novel metastable oxygen defect phases have been identified and characterized. The novel metastable materials have oxygen deficient fluorite structures and consequently are potential ion conductors. Structural aspects of the topotactic vs. reconstructive transformations are illustrated with this model system. The structure-reactivity study of AVO3 phases was extended to AVO3 perovskite family. Based on the research methodologies and results from AVO3 bixbyite reactivity studies a generalized mechanistic oxidation pathway has been established with a non-vanadium phase, ScTiO3 bixbyite. However, there is stark contrast in terms of structural stability and features beyond this stability limit during AVO3 and ScTiO3 bixbyite reaction pathways. A series of complex reaction sequences including phase separation and phase transitions were identified during the investigation of ScTiO3 reactivity. The two-step formation pathway for the fluorite-type oxide ion conductor Ce1-xInxO2-delta (0 ≤ x ≤ 0.3) is being reported. The formation of the BaCe1-xInxO 3-delta perovskites and the subsequent CO2-capture reaction

  15. Greenhouse gas emissions from two-stage landfilling of municipal solid waste

    NASA Astrophysics Data System (ADS)

    Zhang, Yuanyuan; Yue, Dongbei; Nie, Yongfeng

    2012-08-01

    Simulations were conducted to investigate greenhouse gas emissions from aerobic pretreatment and subsequent landfilling. The flows in carbon balance, such as gas, leachate, and solid phases, were considered in the simulations. The total amount of CO2 eq. decreased as organic removal efficiency (ORE) increased. At ORE values of 0, 0.30, 0.41, and 0.54, the total amounts of CO2 eq. were 2614, 2326, 2075, and 1572 kg CO2 eq. per one ton dry matter, respectively; gas accounted for the main contribution to the total amount. The reduction in CO2 eq. from leachate was the primary positive contribution, accounting for 356%, 174%, and 100% of total reduction at ORE values of 0.30, 0.41, and 0.54, respectively. The CO2 eq. from energy consumption was the negative contribution to total reduction, but this contribution is considerably lower than that from gas. Aerobic pretreatment shortened the lag time of biogas production by 74.1-97.0%, and facilitated the transfer of organic carbon in solid waste from uncontrolled biogas and highly polluting leachate to aerobically generated CO2.

  16. Multiple Multidentate Halogen Bonding in Solution, in the Solid State, and in the (Calculated) Gas Phase.

    PubMed

    Jungbauer, Stefan H; Schindler, Severin; Herdtweck, Eberhardt; Keller, Sandro; Huber, Stefan M

    2015-09-21

    The binding properties of neutral halogen-bond donors (XB donors) bearing two multidentate Lewis acidic motifs toward halides were investigated. Employing polyfluorinated and polyiodinated terphenyl and quaterphenyl derivatives as anion receptors, we obtained X-ray crystallographic data of the adducts of three structurally related XB donors with tetraalkylammonium chloride, bromide, and iodide. The stability of these XB complexes in solution was determined by isothermal titration calorimetry (ITC), and the results were compared to X-ray analyses as well as to calculated binding patterns in the gas phase. Density functional theory (DFT) calculations on the gas-phase complexes indicated that the experimentally observed distortion of the XB donors during multiple multidentate binding can be reproduced in 1:1 complexes with halides, whereas adducts with two halides show a symmetric binding pattern in the gas phase that is markedly different from the solid state structures. Overall, this study demonstrates the limitations in the transferability of binding data between solid state, solution, and gas phase in the study of complex multidentate XB donors.

  17. In situ measurement of gas-solid interactions in astrophysical dust & planetary analogues

    NASA Astrophysics Data System (ADS)

    Thompson, S. P.; Parker, J. E.; Day, S. J.; Evans, A.; Tang, C. C.

    2012-02-01

    Facilities for studying gas-solid interactions on beamline I11 at the Diamond Light Source are described. Sample evolution in low and high gas pressure capillary cells (1 × 10-7 to 100 bar) with non-contact cooling and heating (80 to 1273 K) can be monitored structurally (X-rays) and spectroscopically (Raman). First results on the dehydration of MgSO4.7H2O, the formation of CO2 clathrate hydrate and the reaction of amorphous CaSiO3 grains with CO2 gas to form CaCO3 are presented to demonstrate the application of these cells to laboratory investigations involving the processing of cosmic dust simulants and planetary materials analogues.

  18. Oscillations of a gas pocket on a liquid-covered solid surface

    NASA Astrophysics Data System (ADS)

    Gelderblom, Hanneke; Zijlstra, Aaldert G.; van Wijngaarden, Leen; Prosperetti, Andrea

    2012-12-01

    The dynamic response of a gas bubble entrapped in a cavity on the surface of a submerged solid subject to an acoustic field is investigated in the linear approximation. We derive semi-analytical expressions for the resonance frequency, damping, and interface shape of the bubble. For the liquid phase, we consider two limit cases: potential flow and unsteady Stokes flow. The oscillation frequency and interface shape are found to depend on two dimensionless parameters: the ratio of the gas stiffness to the surface tension stiffness, and the Ohnesorge number, representing the relative importance of viscous forces. We perform a parametric study and show, among others, that an increase in the gas pressure or a decrease in the surface tension leads to an increase in the resonance frequency until an asymptotic value is reached.

  19. Numerical Computation of Flame Spread over a Thin Solid in Forced Concurrent Flow with Gas-phase Radiation

    NASA Technical Reports Server (NTRS)

    Jiang, Ching-Biau; T'ien, James S.

    1994-01-01

    Excerpts from a paper describing the numerical examination of concurrent-flow flame spread over a thin solid in purely forced flow with gas-phase radiation are presented. The computational model solves the two-dimensional, elliptic, steady, and laminar conservation equations for mass, momentum, energy, and chemical species. Gas-phase combustion is modeled via a one-step, second order finite rate Arrhenius reaction. Gas-phase radiation considering gray non-scattering medium is solved by a S-N discrete ordinates method. A simplified solid phase treatment assumes a zeroth order pyrolysis relation and includes radiative interaction between the surface and the gas phase.

  20. Coupling between geochemical reactions and multicomponent gas and solute transport in unsaturated media: A reactive transport modeling study

    NASA Astrophysics Data System (ADS)

    Molins, S.; Mayer, K. U.

    2007-05-01

    The two-way coupling that exists between biogeochemical reactions and vadose zone transport processes, in particular gas phase transport, determines the composition of soil gas. To explore these feedback processes quantitatively, multicomponent gas diffusion and advection are implemented into an existing reactive transport model that includes a full suite of geochemical reactions. Multicomponent gas diffusion is described on the basis of the dusty gas model, which accounts for all relevant gas diffusion mechanisms. The simulation of gas attenuation in partially saturated landfill soil covers, methane production, and oxidation in aquifers contaminated by organic compounds (e.g., an oil spill site) and pyrite oxidation in mine tailings demonstrate that both diffusive and advective gas transport can be affected by geochemical reactions. Methane oxidation in landfill covers reduces the existing upward pressure gradient, thereby decreasing the contribution of advective methane emissions to the atmosphere and enhancing the net flux of atmospheric oxygen into the soil column. At an oil spill site, methane oxidation causes a reversal in the direction of gas advection, which results in advective transport toward the zone of oxidation both from the ground surface and the deeper zone of methane production. Both diffusion and advection contribute to supply atmospheric oxygen into the subsurface, and methane emissions to the atmosphere are averted. During pyrite oxidation in mine tailings, pressure reduction in the reaction zone drives advective gas flow into the sediment column, enhancing the oxidation process. In carbonate-rich mine tailings, calcite dissolution releases carbon dioxide, which partly offsets the pressure reduction caused by O2 consumption.

  1. Coupling between geochemical reactions and multicomponent gas and solute transport in unsaturated media: A reactive transport modeling study

    USGS Publications Warehouse

    Molins, S.; Mayer, K.U.

    2007-01-01

    The two-way coupling that exists between biogeochemical reactions and vadose zone transport processes, in particular gas phase transport, determines the composition of soil gas. To explore these feedback processes quantitatively, multicomponent gas diffusion and advection are implemented into an existing reactive transport model that includes a full suite of geochemical reactions. Multicomponent gas diffusion is described on the basis of the dusty gas model, which accounts for all relevant gas diffusion mechanisms. The simulation of gas attenuation in partially saturated landfill soil covers, methane production, and oxidation in aquifers contaminated by organic compounds (e.g., an oil spill site) and pyrite oxidation in mine tailings demonstrate that both diffusive and advective gas transport can be affected by geochemical reactions. Methane oxidation in landfill covers reduces the existing upward pressure gradient, thereby decreasing the contribution of advective methane emissions to the atmosphere and enhancing the net flux of atmospheric oxygen into the soil column. At an oil spill site, methane oxidation causes a reversal in the direction of gas advection, which results in advective transport toward the zone of oxidation both from the ground surface and the deeper zone of methane production. Both diffusion and advection contribute to supply atmospheric oxygen into the subsurface, and methane emissions to the atmosphere are averted. During pyrite oxidation in mine tailings, pressure reduction in the reaction zone drives advective gas flow into the sediment column, enhancing the oxidation process. In carbonate-rich mine tailings, calcite dissolution releases carbon dioxide, which partly offsets the pressure reduction caused by O2 consumption.

  2. Prognostic Role of the Pretreatment C-Reactive Protein/Albumin Ratio in Solid Cancers: A Meta-Analysis

    PubMed Central

    Li, Nan; Tian, Guang-Wei; Wang, Ying; Zhang, Hui; Wang, Zi-hui; Li, Guang

    2017-01-01

    The C-reactive protein/albumin ratio (CAR) has been shown to play a significant prognostic role in several cancers. We aimed to comprehensively explore the potential role of the CAR as a prognostic indicator in solid cancers. In this meta-analysis, we collected data from 10 studies that examined the association between serum CAR and overall survival in patients with cancer. This meta-analysis included 4592 tumor patients. The eligible studies were found through the PubMed and Web of Science databases updated on 6 Oct 2016. The pooled hazard ratio (2.01, 95% CI: 1.58–2.56, p < 0.001) indicated that high CAR yielded worse survival in different cancers. Subgroup analyses showed a significant association between CAR and prognosis, regardless of the cutoff value, cutoff value selection, treatment method, country, sample size, stage and cancer type. This meta-analysis suggests that CAR may be a potential prognostic marker in solid cancers. However, further large prospective studies should be conducted to explore the critical role of CAR in survival of cancer patients. PMID:28128229

  3. Greenhouse Gas Emissions from Solid and Liquid Organic Fertilizers Applied to Lettuce.

    PubMed

    Toonsiri, Phasita; Del Grosso, Stephen J; Sukor, Arina; Davis, Jessica G

    2016-11-01

    Improper application of nitrogen (N) fertilizer and environmental factors can cause the loss of nitrous oxide (NO) to the environment. Different types of fertilizers with different C/N ratios may have different effects on the environment. The focus of this study was to evaluate the effects of environmental factors and four organic fertilizers (feather meal, blood meal, fish emulsion, and cyano-fertilizer) applied at different rates (0, 28, 56, and 112 kg N ha) on NO emissions and to track CO emissions from a lettuce field ( L.). The study was conducted in 2013 and 2014 and compared preplant-applied solid fertilizers (feather meal and blood meal) and multiple applications of liquid fertilizers (fish emulsion and cyano-fertilizer). Three days a week, NO and CO emissions were measured twice per day in 2013 and once per day in 2014 using a closed-static chamber, and gas samples were analyzed by gas chromatography. Preplant-applied solid fertilizers significantly increased cumulative NO emissions as compared with control, but multiple applications of liquid fertilizers did not. Emission factors for NO ranged from 0 to 0.1% for multiple applications of liquid fertilizers and 0.6 to 11% for preplant-applied solid fertilizers, which could be overestimated due to chamber placement over fertilizer bands. In 2014, solid fertilizers with higher C/N ratios (3.3-3.5) resulted in higher CO emissions than liquid fertilizers (C/N ratio, 0.9-1.5). Therefore, organic farmers should consider the use of multiple applications of liquid fertilizers as a means to reduce soil greenhouse gas emissions while maintaining high yields.

  4. Development of acoustic flow instruments for solid/gas pipe flows

    SciTech Connect

    Sheen, S.H.; Raptis, A.C.

    1986-05-01

    Two nonintrusive acoustic flow sensing techniques are reported. One technique, passive in nature, simply measures the bandpassed acoustic noise level produced by particle/particle and particle/wall collisions. The noise levels, given in true RMS voltages or in autocorrelations, show a linear relationship to particle velocity but increase with solid concentration. Therefore, the passive technique requires calibration and a separate measure of solid concentration before it can be used to monitor the particle velocity. The second technique is based on the active cross-correlation principle. It measures particle velocity directly by correlating flow-related signatures at two sensing stations. The velocity data obtained by this technique are compared with measurements by a radioactive-particle time-of-flight (TOF) method. A multiplier of 1.53 is required to bring the acoustic data into agreement with the radioactive TOF result. The difference may originate from the difference in flow fields where particles are detected. The radioactive method senses particles mainly in the turbulent region and essentially measures average particle velocity across the pipe, while the acoustic technique detects particles near the pipe wall, and so measures the particle velocity in the viscous sublayer. Both techniques were tested in flows of limestone and air and 1-mm glass beads and air at the Argonne National Laboratory Solid/Gas Test Facility (SGFTF). The test matrix covered solid velocities of 20 to 30 m/s in a 2-in. pipe and solid-to-gas loading ratios of 6 to 22. 37 refs., 19 figs., 4 tabs.

  5. Modeling of fault reactivation and induced seismicity during hydraulic fracturing of shale-gas reservoirs

    SciTech Connect

    Rutqvist, Jonny; Rinaldi, Antonio P.; Cappa, Frédéric; Moridis, George J.

    2013-07-01

    We have conducted numerical simulation studies to assess the potential for injection-induced fault reactivation and notable seismic events associated with shale-gas hydraulic fracturing operations. The modeling is generally tuned towards conditions usually encountered in the Marcellus shale play in the Northeastern US at an approximate depth of 1500 m (~;;4,500 feet). Our modeling simulations indicate that when faults are present, micro-seismic events are possible, the magnitude of which is somewhat larger than the one associated with micro-seismic events originating from regular hydraulic fracturing because of the larger surface area that is available for rupture. The results of our simulations indicated fault rupture lengths of about 10 to 20 m, which, in rare cases can extend to over 100 m, depending on the fault permeability, the in situ stress field, and the fault strength properties. In addition to a single event rupture length of 10 to 20 m, repeated events and aseismic slip amounted to a total rupture length of 50 m, along with a shear offset displacement of less than 0.01 m. This indicates that the possibility of hydraulically induced fractures at great depth (thousands of meters) causing activation of faults and creation of a new flow path that can reach shallow groundwater resources (or even the surface) is remote. The expected low permeability of faults in producible shale is clearly a limiting factor for the possible rupture length and seismic magnitude. In fact, for a fault that is initially nearly-impermeable, the only possibility of larger fault slip event would be opening by hydraulic fracturing; this would allow pressure to penetrate the matrix along the fault and to reduce the frictional strength over a sufficiently large fault surface patch. However, our simulation results show that if the fault is initially impermeable, hydraulic fracturing along the fault results in numerous small micro-seismic events along with the propagation, effectively

  6. Reactive organic gas emissions from livestock feed contribute significantly to ozone production in central California.

    PubMed

    Howard, Cody J; Kumar, Anuj; Malkina, Irina; Mitloehner, Frank; Green, Peter G; Flocchini, Robert G; Kleeman, Michael J

    2010-04-01

    The San Joaquin Valley (SJV) in California currently experiences some of the highest surface ozone (O(3)) concentrations in the United States even though it has a population density that is an order of magnitude lower than many urban areas with similar ozone problems. Previously unrecognized agricultural emissions may explain why O(3) concentrations in the SJV have not responded to traditional emissions control programs. In the present study, the ozone formation potentials (OFP) of livestock feed emissions were measured on representative field samples using a transportable smog chamber. Seven feeds were considered: cereal silage (wheat grain and oat grain), alfalfa silage, corn silage, high moisture ground corn (HMGC), almond shells, almond hulls, and total mixed ration (TMR = 55% corn silage, 16% corn grain, 8% almond hulls, 7% hay, 7% bran + seeds, and 5% protein + vitamins + minerals). The measured short-term OFP for each gram of reactive organic gas (ROG) emissions from all livestock feed was 0.17-0.41 g-O(3) per g-ROG. For reference, OFP of exhaust from light duty gasoline powered cars under the same conditions is 0.69 +/- 0.15 g-O(3) per g-ROG. Model calculations were able to reproduce the ozone formation from animal feeds indicating that the measured ROG compounds account for the observed ozone formation (i.e., ozone closure was achieved). Ethanol and other alcohol species accounted for more than 50% of the ozone formation for most types of feed. Aldehydes were also significant contributors for cereal silage, high moisture ground corn, and total mixed ration. Ozone production calculations based on feed consumption rates, ROG emissions rates, and OFP predict that animal feed emissions dominate the ROG contributions to ozone formation in the SJV with total production of 25 +/- 10 t O(3) day(-1). The next most significant ROG source of ozone production in the SJV is estimated to be light duty vehicles with total production of 14.3 +/- 1.4 t O(3) day(-1). The

  7. Reactivity of Ozone with Solid Potassium Iodide Investigated by Atomic Force Microscopy

    SciTech Connect

    Mulleregan, Alice; Brown, Matthew A.; Ashby, Paul D.; Ogletree, D. Frank; Salmeron, Miquel; Hemminger, John C.

    2008-04-14

    The reaction of ozone with the (100) plane of solid potassium iodide (KI) was investigated using atomic force microscopy (AFM). The reaction forming potassium iodate (KIO{sub 3}) initiates at step edges prior to reacting on the flat terraces. Small domains of KIO{sub 3}, initially 3.8 {angstrom} in height are formed on the top of step edges. Following reaction at the step edge, domains of KIO{sub 3} are formed across the terraces. With prolonged exposure to ozone, KIO{sub 3} domains nucleate further growth until the surface is evenly covered with KIO{sub 3} particles that are 4-6 nm in height, at which point the surface is passivated and the reaction terminates.

  8. Analysis of ammonium nitrate headspace by on-fiber solid phase microextraction derivatization with gas chromatography mass spectrometry.

    PubMed

    Lubrano, Adam L; Andrews, Benjamin; Hammond, Mark; Collins, Greg E; Rose-Pehrsson, Susan

    2016-01-15

    A novel analytical method has been developed for the quantitation of trace levels of ammonia in the headspace of ammonium nitrate (AN) using derivatized solid phase microextraction (SPME) fibers with gas chromatography mass spectrometry (GC-MS). Ammonia is difficult to detect via direct injection into a GC-MS because of its low molecular weight and extreme polarity. To circumvent this issue, ammonia was derivatized directly onto a SPME fiber by the reaction of butyl chloroformate coated fibers with the ammonia to form butyl carbamate. A derivatized externally sampled internal standard (dESIS) method based upon the reactivity of diethylamine with unreacted butyl chloroformate on the SPME fiber to form butyl diethylcarbamate was established for the reproducible quantification of ammonia concentration. Both of these compounds are easily detectable and separable via GC-MS. The optimized method was then used to quantitate the vapor concentration of ammonia in the headspace of two commonly used improvised explosive device (IED) materials, ammonium nitrate fuel oil (ANFO) and ammonium nitrate aluminum powder (Ammonal), as well as identify the presence of additional fuel components within the headspace.

  9. Performance of a Zerovalent Iron Reactive Barrier for the Treatment of Arsenic in Groundwater: Part 2. Geochemical Modeling and Solid Phase Studies

    EPA Science Inventory

    Arsenic uptake processes were evaluated in a zerovalent iron reactive barrier installed at a lead smelting facility using geochemical modeling, solid-phase analysis, and X-ray absorption spectroscopy techniques. Aqueous speciation of arsenic plays a key role in directing arsenic...

  10. Chemistry at the square nanometer: reactivity at liquid/solid interfaces revealed with an STM.

    PubMed

    Münninghoff, Joris A W; Elemans, Johannes A A W

    2017-02-02

    For more than three decades the scanning tunnelling microscope (STM) has proven to be an indispensable tool to image molecules adsorbed at a surface at the highest detail possible. In addition to simply imaging molecules, STM can also be applied to monitor dynamic surface phenomena, including chemical reactions. By studying reactions at a surface at the single molecule level, unique information about reaction mechanisms can be obtained which remains hidden when conventional ensemble techniques are used. Many STM studies of chemical reactions have been performed in extreme environments like ultrahigh vacuum or high pressure chambers, but these are far removed from conditions in which most chemical and biological processes take place, i.e., in a liquid at ambient atmospheres. This feature paper highlights the developments in the relatively unexplored research area of investigating chemical reactions with an STM at a liquid/solid interface under ambient conditions. Covalent couplings between molecules, light-induced isomerisations, reactions under electrochemical control, and complex multistep processes and catalysis are discussed.

  11. Advanced instrumentation for local measurement of gas-solid suspension flows

    NASA Astrophysics Data System (ADS)

    Ling, S. C.; Pao, H. P.

    The study of gas-solid suspension flow is being conducted in two parts: the lifting of heavy particles from the flow boundary by micro-hairpin vortices and the design of an optical instrument to investigate the characteristics of turbulent flows has particle-size concentrations. The study of micro-hairpin vortices is based on the observation of these vortices in a cavitation water-tunnel. The micro-vortices exist within the laminar and intermediate sublayer of the turbulent flow field where the velocity gradient is most intense. These vortices are believed to be the major production source of turbulence which are also responsible for the picking up of heavy solid particles from the flow boundary at the bottom of the pipe. However, this important transport mechanism near the bottom boundary was not taken into account in all previous theories of solid transport. It is hoped that this work will provide a more basic understanding on the mechanics of solid transport. Our major research effort in this quarter has been concentrated on the construction of the experimental test-setup and the development of an optical particle-size and concentration detector. The optical detector also provides the information on flow characteristics.

  12. Experimental Research on Gas-Solid Flow in a Square Cyclone Separator with Double Inlets

    NASA Astrophysics Data System (ADS)

    Xiong, B.; Lu, X. F.; Amano, R. S.; Shu, C.

    A square cyclone separator with double inlets was developed for a new type Circulating Fluidized Bed (CFB) boiler arrangement scheme including two furnaces. Experiments on the performance and gas-solid flow recorded by a high-speed photography have been conducted in a cold test rig with a separator cross section 400mm×400mm. Experimental results indicated that with the inlet velocity of 22.4m/s and the inlet solids concentration of 4.9g/m3, the cut size is 15 μm, the critical size is 75μm, and the pressure drop coefficient is 1.7. The performance is also affected by the inlet velocity and solids concentration. The trajectory of particles shows that the particles swirl in the region near the wall and are easily separated. Especially, the instantaneous separation occurred at the corner is very significant for the improvement of the collection efficiency with the high inlet solids concentration for CFB boiler.

  13. Conversion of tomato, peach and honeydew solid waste into methane gas

    SciTech Connect

    Hills, D.J.; Roberts, D.W.

    1982-01-01

    Results from a laboratory investigation on the title conversion and seasonal operation of a pilot-plant size digester are presented. For 4-L laboratory digesters operating at 35 degrees, the respective optimal loading rates and retention times for tomato, honeydew, and peach residues, were 5, 3, and 1 kg volatile solids (VS)/cubic meter-day and 25, 20, and 15 days. Under these operating conditions 33, 83, and 86% of VS were destroyed for tomato, honeydew and peach residues, respectively, and the corresponding gas productions at 0 degrees and 1 atm. were 0.43, 2.45, and 1.15 vol./digester vol-day. Operation of the 22-cubic meter pilot plant generally confirmed the laboratory data for tomato solid waste.

  14. Basic research needs and opportunities at the solid-gas interface

    NASA Astrophysics Data System (ADS)

    Brodsky, M. B.; Cathcart, J. V.; Hansen, R. S.; Kliewer, K. L.; Landman, U.; Park, R. L.; Shatynski, S. R.

    1982-04-01

    Solar energy conversion technologies which involve a solid-gas (S-G) interface in formation or operation and the means to study the related phenomena are reviewed, including thermoelectric and thermionic conversion. The analyses are considered as necessary for characterizing glasses, mirrors, heat mirrors, and transmitters using thermo- and photochromic modeling. Research is indicated on the glass-air interface, the air-solid interface encountered by antireflective coatings, the kinetics, and mechanisms of polymer degradation, and the development of new reflective materials. Absorber materials are explored, along with alternatives such as textured surfaces. Processes of formation, protection, and degradation of solar cells, particularly low cost thin-film devices, are explored, along with junction reaction and decomposition studies of thermoelectric devices and reactions of alkali metal vapors with thermionic devices.

  15. Magnitude and reactivity consequences of moisture ingress into the modular High-Temperature Gas-Cooled Reactor core

    SciTech Connect

    Smith, O.L. )

    1992-12-01

    Inadvertent admission of moisture into the primary system of a modular high-temperature gas-cooled reactor has been identified in US Department of Energy-sponsored studies as an important safety concern. The work described here develops an analytical methodology to quantify the pressure and reactivity consequences of steam-generator tube rupture and other moisture-ingress-related incidents. Important neutronic and thermohydraulic processes are coupled with reactivity feedback and safety and control system responses. The rate and magnitude of steam buildup are found to be dominated by major system features such as break size compared with safety valve capacity and reliability and less sensitive to factors such as heat transfer coefficients. The results indicate that ingress transients progress at a slower pace than previously predicted by bounding analyses, with milder power overshoots and more time for operator or automatic corrective actions.

  16. Revisiting low-fidelity two-fluid models for gas-solids transport

    NASA Astrophysics Data System (ADS)

    Adeleke, Najeem; Adewumi, Michael; Ityokumbul, Thaddeus

    2016-08-01

    Two-phase gas-solids transport models are widely utilized for process design and automation in a broad range of industrial applications. Some of these applications include proppant transport in gaseous fracking fluids, air/gas drilling hydraulics, coal-gasification reactors and food processing units. Systems automation and real time process optimization stand to benefit a great deal from availability of efficient and accurate theoretical models for operations data processing. However, modeling two-phase pneumatic transport systems accurately requires a comprehensive understanding of gas-solids flow behavior. In this study we discuss the prevailing flow conditions and present a low-fidelity two-fluid model equation for particulate transport. The model equations are formulated in a manner that ensures the physical flux term remains conservative despite the inclusion of solids normal stress through the empirical formula for modulus of elasticity. A new set of Roe-Pike averages are presented for the resulting strictly hyperbolic flux term in the system of equations, which was used to develop a Roe-type approximate Riemann solver. The resulting scheme is stable regardless of the choice of flux-limiter. The model is evaluated by the prediction of experimental results from both pneumatic riser and air-drilling hydraulics systems. We demonstrate the effect and impact of numerical formulation and choice of numerical scheme on model predictions. We illustrate the capability of a low-fidelity one-dimensional two-fluid model in predicting relevant flow parameters in two-phase particulate systems accurately even under flow regimes involving counter-current flow.

  17. Ditechnetium heptoxide revisited: Solid-state, gas-phase, and theoretical studies

    DOE PAGES

    Childs, Bradley C.; Braband, Henrik; Lawler, Keith; ...

    2016-10-04

    Here, ditechnetium heptoxide was synthesized from the oxidation of TcO2 with O2 at 450 °C and characterized by single crystal X-ray diffraction (SCXRD), electron impact mass spectrometry (EI-MS) and theoretical methods. Refinement of the structure at 100 K indicates that Tc2O7 crystallizes as a molecular solid in the orthorhombic space group Pbca (a = 7.312(3) Å, b = 5.562(2) Å, c = 13.707(5) Å, V = 557.5(3) Å3). The Tc2O7 molecule can be described as corner-sharing TcO4 tetrahedra (Tc---Tc = 3.698(1) Å and Tc-OBri-Tc = 180.0°). The EI-MS spectrum of Tc2O7 consists of both mononuclear and dinuclear species. The mainmore » dinuclear species in the gas-phase are Tc2O7 (100%) and Tc2O5 (56%), while the main mononuclear species are TcO3 (33.9%) and TcO2 (42.8%). The difference in the relative intensities of the M2O5 (M = Tc, Re) fragments (1.7% for Re) indicate that these Group 7 elements exhibit different gas phase chemistry. The solid-state structure of Tc2O7 was investigated by density functional theory (DFT) methods. The optimized structure of the Tc2O7 molecule is in good agreement with the experimental one. Simulations indicate that the more favorable geometry for the Tc2O7 molecule in the gas-phase is bent (Tc-OBri-Tc = 156.5°), while linear (Tc-OBri-Tc = 180.0°) is favored in the solid state.« less

  18. Reactive Melt Extrusion To Improve the Dissolution Performance and Physical Stability of Naproxen Amorphous Solid Dispersions.

    PubMed

    Liu, Xu; Zhou, Lin; Zhang, Feng

    2017-03-06

    The purpose of this study was to investigate the reaction between naproxen (NPX) and meglumine (MEG) at elevated temperature and to study the effect of this reaction on the physical stabilities and in vitro drug-release properties of melt-extruded naproxen amorphous solid dispersions (ASDs). Differential scanning calorimetry, hot-stage polarized light microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy analyses demonstrated that in situ salt formation with proton transfer between NPX and MEG occurred at elevated temperature during the melt extrusion process. The amorphous NPX-MEG salt was physically most stable when two components were present at a 1:1 molar ratio. Polymeric carriers, including povidone, copovidone, and SOLUPLUS, did not interfere with the reaction between NPX and MEG during melt extrusion. Compared to the traditional NPX ASDs consisting of NPX and polymer only, NPX-MEG ASDs were physically more stable and remained amorphous following four months storage at 40 °C and 75% RH (relative humidity). Based on nonsink dissolution testing and polarized light microscopy analyses, we concluded that the conventional NPX ASDs composed of NPX and polymers failed to improve the NPX dissolution rate due to the rapid recrystallization of NPX in contact with aqueous medium. The dissolution rate of NPX-MEG ASDs was two times greater than the corresponding physical mixtures and conventional NPX ASDs. This study demonstrated that the acid-base reaction between NPX and MEG during melt extrusion significantly improved the physical stability and the dissolution rate of NPX ASDs.

  19. Groundwater impacts associated with landfill gas migration at municipal solid waste landfill sites

    SciTech Connect

    Clister, W.; Janechek, A.; Hibbs, S.

    1998-07-01

    Many older municipal solid waste (MSW) landfills are unlined and subsequently have become a source of local groundwater contamination. However, the adverse impact on the groundwater quality at such sites is not necessarily limited to that caused by leachate contamination of the underlying aquifer but also may include the effects of landfill gas (LFG) migration. Absorption of certain LFG components, particularly volatile organic compounds (VOCs), may occur at offsite locations when a LFG excursion front migrates into adjacent soils. When LFG management systems are installed at such sites, this problem is often eliminated.

  20. Soil-gas survey at the solid waste landfill - Final Report

    SciTech Connect

    Evans, J.C.; Fruland, R.M.; Glover, D.W.; Veverka, C.

    1989-12-01

    A soil-gas survey to determine the lateral distribution of chlorinated hydrocarbon solvents in the vadose zone, and possibly ground water, was conducted at the Hanford Site Solid Waste Landfill. For a 2-year period, three trenches just inside the western perimeter of the landfill had received liquid discharges of both sewage and washwater, which contained solvents. Ground-water monitoring wells, installed a few months after liquid discharge had been discontinued, indicated very low levels (less than 10 ppb) of solvents exist in the ground water downgradient from the disposal trenches. 13 refs., 7 figs., 1 tab.

  1. Microscopic Processes at the Gas-Solid Interface of Compound Semiconductors.

    DTIC Science & Technology

    1981-03-01

    AGO35 PI ETN MV NJD TOFEETIA ENIERN AD-T FG20 2 MICROSCOPIC PROCESSES AT THE GAS-SOLID INTERFACE OF COMPOUND SE-ETC(U) UUCMAR 81 P MARK . A KAHN...1. A. Kahn, G. Cisneros, M. Bonn and P. Mark , Surf. Sct., 71 (1978) 387. 2. A. Kahn, E. So and P. Mark , J. Vac. Sci. Technol., 15, No. 2, (1978) 580...4 3. A. Kahn, E. So and P. Mark , J. Vac. Sc. Technol., 15, (1978) 1223. 4. R.J. Meyer, C.B. Duke, A. Paton, J.L. Yeh, J.C. Tsang, A. Kahn and P. Mark

  2. Numerical simulation study on gas solid two-phase flow in pre-calciner

    NASA Astrophysics Data System (ADS)

    Hu, Zhijuan; Lu, Jidong; Huang, Lai; Wang, Shijie

    2006-06-01

    A three-dimensional numerical simulation of DD (dual combustion and denitratior process) pre-calciner for cement production was conducted in this paper. In Euler coordinate system, the fluid phase is expressed with RNG k- ɛ two-equation model and the solid phase is expressed with particle stochastic trajectory model in Lagrange coordinate system. Four mixture fractions are deduced in this article to simulate the gas compositions. The results of numerical simulation predicted the burn-out ratio of coal and the decomposition ratio of limestone particles along with particle trajectories. It also supplied theoretical foundation for industrial analysis of the coupling relation between coal combustion and calcium carbonate decomposition.

  3. Screening of Brazilian fruit aromas using solid-phase microextraction-gas chromatography-mass spectrometry.

    PubMed

    Augusto, F; Valente, A L; dos Santos Tada, E; Rivellino, S R

    2000-03-17

    Manual headspace solid-phase microextraction (SPME) coupled to gas chromatography-mass spectrometry (GC-MS) was used for the qualitative analysis of the aromas of four native Brazilian fruits: cupuassu (Theobroma grandiflorum, Spreng.), cajá (Spondias lutea. L.), siriguela (Spondias purpurea, L.) and graviola (Anona reticulata, L). Industrialized pulps of these fruits were used as samples, and extractions with SPME fibers coated with polydimethylsiloxane, polyacrylate, Carbowax and Carboxen were carried out. The analytes identified included several alcohols, esters, carbonyl compounds and terpernoids. The highest amounts extracted, evaluated from the sum of peak areas, were achieved using the Carboxen fiber.

  4. Control of reactive oxygen and nitrogen species production in liquid by nonthermal plasma jet with controlled surrounding gas

    NASA Astrophysics Data System (ADS)

    Ito, Taiki; Uchida, Giichiro; Nakajima, Atsushi; Takenaka, Kosuke; Setsuhara, Yuichi

    2017-01-01

    We present the development of a low-frequency nonthermal plasma-jet system, where the surrounding-gas condition of the plasma jet is precisely controlled in open air. By restricting the mixing of the ambient air into the plasma jet, the plasma jet can be selectively changed from a N2 main discharge to an O2 main discharge even in open air. In the plasma-jet system with the controlled surrounding gas, the production of reactive oxygen and nitrogen species is successfully controlled in deionized water: the concentration ratio of NO2 - to H2O2 is tuned from 0 to 0.18, and a high NO2 - concentration ratio is obtained at a N2 gas ratio of 0.80 relative to the total N2/O2 gas mixture in the main discharge gas. We also find that the NO2 - concentration is much higher in the plasma-activated medium than in the plasma-activated deionized water, which is mainly explained by the contribution of amino acids to NO2 - generation in the medium.

  5. Combinations of solid oxide fuel cell and several enhanced gas turbine cycles

    NASA Astrophysics Data System (ADS)

    Kuchonthara, Prapan; Bhattacharya, Sankar; Tsutsumi, Atsushi

    Combined power generation systems with combinations of solid oxide fuel cell (SOFC) and various enhanced gas turbine (GT) cycles were evaluated. In the GT part, steam injected gas turbine (STIG) cycle, GT/steam turbine (ST) combined cycle, and humid air turbine (HAT) cycle were considered. Moreover, additional recuperation was considered by means of air preheating (APH) in the STIG cycle. Effects of operating turbine inlet temperature (TIT) and pressure ratio (PR) on overall system performance were assessed. Although the SOFC-HAT system shows the lowest specific work output compared to other systems, its highest thermal efficiency presents a significant advantage. Furthermore, at high TITs and PRs the SOFC-HAT system gives the best performance in terms of both thermal efficiency and specific work. Results indicate that energy recuperative features in the HAT promote the positive effect of increasing TIT by means of enhancing GT efficiency, leading to the improvement in thermal efficiency of the overall system.

  6. An extended soft-cube model for the thermal accommodation of gas atoms on solid surfaces

    NASA Astrophysics Data System (ADS)

    Burke, J. R.; Hollenbach, D. J.

    1980-01-01

    A numerical soft cube model was developed for calculating thermal accommodation coefficients alpha and trapping fractions f sub t for the interaction of gases incident upon solid surfaces. A semiempirical correction factor c which allows the calculation of alpha and f sub t when the collision times are long compared to the surface oscillator period were introduced. The processes of trapping, evaporation, and detailed balancing were discussed. The numerical method was designed to treat economically and with moderate (+ or - 20 percent) accuracy the dependence of alpha and f sub t on finite and different surface and gas temperatures for a large number of gas/surface combinations. Comparison was made with experiments of rare gases on tungsten and on alkalis, as well as one astrophysical case of H2 on graphite. The dependence of alpha on the soft cube dimensionless parameters is presented graphically.

  7. THEORY OF A QUODON GAS WITH APPLICATION TO PRECIPITATION KINETICS IN SOLIDS UNDER IRRADIATION

    SciTech Connect

    Dubinko, Volodymyr; Shapovalov, Roman V.

    2014-06-17

    Rate theory of the radiation-induced precipitation in solids is modified with account of non-equilibrium fluctuations driven by the “gas” of lattice solitons (a.k.a. “quodons”) produced by irradiation. According to quantitative estimations, a steady-state density of the quodon gas under sufficiently intense irradiation can be comparable to the density of classical phonon gas. The modified rate theory is applied to modelling of copper precipitation in FeCu binary alloys under electron irradiation. In contrast to the classical rate theory, which disagrees strongly with experimental data on all precipitation parameters, the modified rate theory describes quite well both the evolution of precipitates and the matrix concentration of copper measured by different methods.

  8. Feed gas contaminant removal in ion transport membrane systems

    DOEpatents

    Underwood, Richard Paul [Allentown, PA; Makitka, III, Alexander; Carolan, Michael Francis [Allentown, PA

    2012-04-03

    An oxygen ion transport membrane process wherein a heated oxygen-containing gas having one or more contaminants is contacted with a reactive solid material to remove the one or more contaminants. The reactive solid material is provided as a deposit on a support. The one or more contaminant compounds in the heated oxygen-containing gas react with the reactive solid material. The contaminant-depleted oxygen-containing gas is contacted with a membrane, and oxygen is transported through the membrane to provide transported oxygen.

  9. The Penetration Behavior of an Annular Gas-Solid Jet Impinging on a Liquid Bath: The Effects of the Density and Size of Solid Particles

    NASA Astrophysics Data System (ADS)

    Chang, J. S.; Sohn, H. Y.

    2012-08-01

    Top-blow injection of a gas-solid jet through a circular lance is used in the Mitsubishi Continuous Smelting Process. One problem associated with this injection is the severe erosion of the hearth refractory below the lances. A new configuration of the lance to form an annular gas-solid jet rather than the circular jet was designed in this laboratory. With this new configuration, the solid particles fed through the center tube leave the lance at a much lower velocity than the gas, and the penetration behavior of the jet is significantly different from that with a circular lance where the solid particles leave the lance at the same high velocity as the gas. In previous cold-model investigations in this laboratory, the effects of the gas velocity, particle feed rate, lance height of the annular lance, and the cross-sectional area of the gas jet were studied and compared with the circular lance. This study examined the effect of the density and size of the solid particles on the penetration behavior of the annular gas-solid jet, which yielded some unexpected results. The variation in the penetration depth with the density of the solid particles at the same mass feed rate was opposite for the circular lance and the annular lance. In the case of the circular lance, the penetration depth became shallower as the density of the solid particles increased; on the contrary, for the annular lance, the penetration depth became deeper with the increasing density of particles. However, at the same volumetric feed rate of the particles, the density effect was small for the circular lance, but for the annular lance, the jets with higher density particles penetrated more deeply. The variation in the penetration depth with the particle diameter was also different for the circular and the annular lances. With the circular lance, the penetration depth became deeper as the particle size decreased for all the feed rates, but with the annular lance, the effect of the particle size was

  10. Investigation of Gas Solid Fluidized Bed Dynamics with Non-Spherical Particles

    SciTech Connect

    Choudhuri, Ahsan

    2013-06-30

    One of the largest challenges for 21st century is to fulfill global energy demand while also reducing detrimental impacts of energy generation and use on the environment. Gasification is a promising technology to meet the requirement of reduced emissions without compromising performance. Coal gasification is not an incinerating process; rather than burning coal completely a partial combustion takes place in the presence of steam and limited amounts of oxygen. In this controlled environment, a chemical reaction takes place to produce a mixture of clean synthetic gas. Gas-solid fluidized bed is one such type of gasification technology. During gasification, the mixing behavior of solid (coal) and gas and their flow patterns can be very complicated to understand. Many attempts have taken place in laboratory scale to understand bed hydrodynamics with spherical particles though in actual applications with coal, the particles are non-spherical. This issue drove the documented attempt presented here to investigate fluidized bed behavior using different ranges of non-spherical particles, as well as spherical. For this investigation, various parameters are controlled that included particle size, bed height, bed diameter and particle shape. Particles ranged from 355 µm to 1180 µm, bed diameter varied from 2 cm to 7 cm, two fluidized beds with diameters of 3.4 cm and 12.4 cm, for the spherical and non-spherical shaped particles that were taken into consideration. Pressure drop was measured with increasing superficial gas velocity. The velocity required in order to start to fluidize the particle is called the minimum fluidization velocity, which is one of the most important parameters to design and optimize within a gas-solid fluidized bed. This minimum fluidization velocity was monitored during investigation while observing variables factors and their effect on this velocity. From our investigation, it has been found that minimum fluidization velocity is independent of bed

  11. Remarks on global existence and exponential stability of solutions for the viscous radiative and reactive gas with large initial data

    NASA Astrophysics Data System (ADS)

    Zhang, Jianlin

    2017-04-01

    In this paper, we study a large time behavior of the global spherically or cylindrically symmetric solutions in H 1 for the compressible viscous radiative and reactive gas in multi-dimension with large initial data. Precisely, if the initial data are spherically symmetric or cylindrically symmetric, the smallness of initial data is not needed. The main concern of the present paper is to investigate the exponential stability of a solution toward the stationary solution as time goes to infinity. We obtain the uniform positive lower and upper bounds of the density by using different methods.

  12. Structure, reactivity and tailoring of porous organic solids based on phenylacetylene silver coordination networks

    NASA Astrophysics Data System (ADS)

    Kiang, Yuan-Hon

    This thesis studies the preparation of covalently crosslinked porous organic solids via phenylacetylene nitrile ligands and silver(I) ions coordination networks. A prototype of three-fold symmetric phenylacetylene nitrile ligand, 1,3,5-tris(4-ethynyl benzonitrile) (1) has been found to crystallize with silver(I) trifluoromethansulfonate to form a three dimensional channel structure. The extended channels found in this coordination network are of honeycomb type 15 A in diameter. Properties such as guest removal and exchange within this host crystal have been investigated. The honeycomb channels in the crystal structure are retained through both guest exchange and complete guest removal. The apohost (defined as a host without occluded guests) exhibits selectivity for new guests by absorbing aromatic molecules and not aliphatic molecules from the vapor phase. Repeated removal and reintroduction of benzyl alcohol guests is demonstrated to occur with the retention of crystallinity and without the macroscopic reformation of the crystallites. Investigations on molecular variants of the prototypic ligand 1 crystallized with silver(I) trifluoromethansulfonate have revealed a nearly invariant honeycomb porous structure type. Modifications involved both the attachment of pendant groups on the central aromatic ring of the parent molecule and the addition of elongated spacer unit between the central benzene ring and the peripheral nitrile groups. Single crystal refinements for five silver(I) salts of modified organic ligands as well as powder studies of 15 crystalline phases showed the consistent formation of the honeycomb channels, demonstrating that the parent porous architecture is stable both to functional modification as well as to size change. It was found in the case of a host with alcohol functionality that trifluoroacetic anhydride and silyl triflate both reacted with the host to form respectively an ester and a siloxane with retention of the porous structure type. In

  13. Anode-pore tortuosity in solid oxide fuel cells found from gas and current flow rates

    NASA Astrophysics Data System (ADS)

    Schmidt, V. Hugo; Tsai, Chih-Long

    The effect of solid oxide fuel cell (SOFC) anode thickness, porosity, pore size, and pore tortuosity on fuel and exhaust gas flow is calculated. Also determined is the concentration of these gases and of diluent gases as a function of position across the anode. The calculation is based on the dusty-gas model which includes a Knudsen (molecule-wall) collision term in the Stefan-Maxwell equation which is based on unlike-molecule collisions. Commonly made approximations are avoided in order to obtain more exact results. One such approximation is the assumption of uniform total gas pressure across the anode. Another such approximation is the assumption of zero fuel gas concentration at the anode-electrolyte interface under the anode saturation condition for which the SOFC output voltage goes to zero. Elimination of this approximation requires use of a model we developed (published elsewhere) for terminal voltage V as a function of electrolyte current density i. Key formulae from this model are presented. The formulae developed herein for gas flow and tortuosity are applied to the results of a series of careful experiments performed by another group, who used binary and ternary gas mixtures on the anode side of an SOFC. Our values for tortuosity are in a physically reasonable low range, from 1.7 to 3.3. They are in fair agreement with those obtained by the other group, once a difference in nomenclature is taken into account. This difference consists in their definition of tortuosity being what some call tortuosity factor, which is the square of what we and some others call tortuosity. The results emphasize the need for careful design of anode pore structures, especially in anode-supported SOFCs which require thicker anodes.

  14. The Influence of Lattice Imperfections on the Chemical Reactivity of Solids. The Growth, Perfection and Defect Properties of PETN (Pentaerythritol Tetranitrate) and RDX (Cyclotrimethylene Trinitramine) Single Crystals. Part 2.

    DTIC Science & Technology

    1984-02-01

    RD-A1i~ 272 THE INFLUENCE OF LATTICE IMPERFECTIONS ON THE CHEMICAL i REACTIVITY OF SOI (U) UNIVERSITY OF STRATHCLYDE GLASGOW (SCOTLAND) DEPT OF PURE...M251 11111 MICROCOPY RESOLUTION TEST CHART NATIONAL BUREAU OF STANDARDS 1963-A THE INFLUENCE O ATC MEFCIN ON THE CHEMICAL REACTIVITY OF SOLIDS o. THE...on the Chemical Reactivity of Solids. FINAL TECHNICAL ". PERFORMING ORG. REPORT NUMBER 7. AUTHOR(.) S. CONTRACT OR GRANT NUMUER(i,) J. N. Sherwood

  15. Particle velocity and solid volume fraction measurements with a new capacitive flowmeter at the Solid/Gas Flow Test Facility. [Glass beads

    SciTech Connect

    Bobis, J.P.; Porges, K.G.A.; Raptis, A.C.; Brewer, W.E.; Bernovich, L.T.

    1986-08-01

    The performance of a new capacitive flowmeter has been assessed experimentally in a gas-entrained solid flow stream at the Argonne National Laboratory (ANL) Solid/Gas Flow Test Facility (S/GFTF) for solid feedrates in the range of 0.5 to 2 kg/s and solid-gas loadings up to 22, corresponding to a range of solid volume fractions extending from 0.004 to 0.016. Two types of nonintrusive instruments using the capacitive principle were fabricated at ANL and installed in the horizontal leg of a 12.3 m test section to sense the solids. An improved electrode geometry designed to maximize the coverage of the duct interior while minimizing the readout error due to a nonuniform electric field, was incorporated for one spoolpiece with the sensing electrodes on the outside surface of a ceramic liner and for another spoolpiece with the sensing electrodes mounted flush with the duct inside surface. The capacitive instruments measured the solid volume fraction and the average particle velocity. The results are compared with time-of-flight measurements of short-lived radioactive particles that duplicate closely the size and density of the 1000..mu.. glass beads used in these flow tests. Results show that the solid volume fraction measurements agree with the theoretical models presented and that the particle velocity deduced from the cross-correlation scheme agreed to within 5% of the irradiated particle velocity technique for the 21 to 31 m/s range generated with the S/GFTF. 43 refs., 36 figs., 19 tabs.

  16. Characterization of Human Skin Emanations by Solid Phase Microextraction (SPME) Extraction of Volatiles and Subsequent Analysis by Gas Chromatography-Mass Spectrometry (GC-MS)

    DTIC Science & Technology

    2007-11-02

    1 Characterization of Human Skin Emanations by Solid Phase Microextraction (SPME) Extraction of Volatiles and Subsequent Analysis by Gas...DATES COVERED - 4. TITLE AND SUBTITLE Characterization of Human Skin Emanations by Solid Phase Microextraction (SPME) Extraction of Volatiles...3 Characterization of Human Skin Emanations by Solid Phase Microextraction (SPME) Extraction of Volatiles and Subsequent Analysis by Gas

  17. Formation Of the Giant Planets By Concurrent Accretion Of Solids And Gas

    NASA Technical Reports Server (NTRS)

    Pollack, James B.; Hubickyj, Olenka; Bodenheimer, Peter; Lissauer, Jack J.; Podolak, Morris; Greenzweig, Yuval; Cuzzi, Jeffery N. (Technical Monitor)

    1995-01-01

    New numerical simulations of the formation of the giant planets are presented, in which for the first time both the gas and planetesimal accretion rates are calculated in a self-consistent, interactive fashion. The simulations combine three elements: 1) three-body accretion cross-sections of solids onto an isolated planetary embryo, 2) a stellar evolution code for the planet's gaseous envelope, and 3) a planetesimal dissolution code within the envelope, used to evaluate the planet's effective capture radius and the energy deposition profile of accreted material. Major assumptions include: The planet is embedded in a disk of gas and small planetesimals with locally uniform initial surface mass density, and planetesimals are not allowed to migrate into or out of the planet's feeding zone. All simulations are characterized by three major phases. During the first phase, the planet's mass consists primarily of solid material. The planetesimal accretion rate, which dominates that of gas, rapidly increases owing to runaway accretion, then decreases as the planet's feeding zone is depleted. During the second phase, both solid and gas accretion rates are small and nearly independent of time. The third phase, marked by runaway gas accretion, starts when the solid and gas masses are about equal. It is engendered by a strong positive feedback on the gas accretion rates, driven by the rapid contraction of the gaseous envelope and the rapid expansion of the outer boundary, which depends on the planet's total mass. The overall evolutionary time scale is generally determined by the length of the second phase. The actual rates at which the giant planets accreted small planetesimals is probably intermediate between the constant rates assumed in most previous studies and the highly variable rates that we have used. Within the context, of the adopted model of planetesimal accretion, the joint constraints of the time scale for dissipation of the solar nebula and the current high

  18. Comparative modeling of fault reactivation and seismicity in geologic carbon storage and shale-gas reservoir stimulation

    NASA Astrophysics Data System (ADS)

    Rutqvist, Jonny; Rinaldi, Antonio; Cappa, Frederic

    2016-04-01

    The potential for fault reactivation and induced seismicity are issues of concern related to both geologic CO2 sequestration and stimulation of shale-gas reservoirs. It is well known that underground injection may cause induced seismicity depending on site-specific conditions, such a stress and rock properties and injection parameters. To date no sizeable seismic event that could be felt by the local population has been documented associated with CO2 sequestration activities. In the case of shale-gas fracturing, only a few cases of felt seismicity have been documented out of hundreds of thousands of hydraulic fracturing stimulation stages. In this paper we summarize and review numerical simulations of injection-induced fault reactivation and induced seismicity associated with both underground CO2 injection and hydraulic fracturing of shale-gas reservoirs. The simulations were conducted with TOUGH-FLAC, a simulator for coupled multiphase flow and geomechanical modeling. In this case we employed both 2D and 3D models with an explicit representation of a fault. A strain softening Mohr-Coulomb model was used to model a slip-weakening fault slip behavior, enabling modeling of sudden slip that was interpreted as a seismic event, with a moment magnitude evaluated using formulas from seismology. In the case of CO2 sequestration, injection rates corresponding to expected industrial scale CO2 storage operations were used, raising the reservoir pressure until the fault was reactivated. For the assumed model settings, it took a few months of continuous injection to increase the reservoir pressure sufficiently to cause the fault to reactivate. In the case of shale-gas fracturing we considered that the injection fluid during one typical 3-hour fracturing stage was channelized into a fault along with the hydraulic fracturing process. Overall, the analysis shows that while the CO2 geologic sequestration in deep sedimentary formations are capable of producing notable events (e

  19. Pore Scale Modeling of the Reactive Transport of Chromium in the Cathode of a Solid Oxide Fuel Cell

    SciTech Connect

    Ryan, Emily M.; Tartakovsky, Alexandre M.; Recknagle, Kurtis P.; Khaleel, Mohammad A.; Amon, Cristina

    2011-01-01

    We present a pore scale model of a solid oxide fuel cell (SOFC) cathode. Volatile chromium species are known to migrate from the current collector of the SOFC into the cathode where over time they decrease the voltage output of the fuel cell. A pore scale model is used to investigate the reactive transport of chromium species in the cathode and to study the driving forces of chromium poisoning. A multi-scale modeling approach is proposed which uses a cell level model of the cathode, air channel and current collector to determine the boundary conditions for a pore scale model of a section of the cathode. The pore scale model uses a discrete representation of the cathode to explicitly model the surface reactions of oxygen and chromium with a cathode material. The pore scale model is used to study the reaction mechanisms of chromium by considering the effects of reaction rates, diffusion coefficients, chromium vaporization, and oxygen consumption on chromium’s deposition in the cathode. The study shows that chromium poisoning is most significantly affected by the chromium reaction rates in the cathode and that the reaction rates are a function of the local current density in the cathode.

  20. Solid-phase microextraction-gas chromatographic determination of volatile monoaromatic hydrocarbons in soil.

    PubMed

    Zygmunt, B; Namiesnik, J

    2001-08-01

    Benzene, toluene, ethylbenzene, three isomers of xylene, and cumene have been isolated and enriched from soil samples by a combination of water extraction at room and elevated temperature and headspace-solid-phase microextraction before their gas chromatographic-mass spectrometric (GC-MS) determination. The conditions used for all stages of sample preparation and chromatographic analysis were optimized. Analytes sampled on a polydimethylsiloxane-coated solid-phase microextraction fiber were thermally desorbed in the split/splitless injector of a gas chromatograph (GC) coupled with a mass spectrometer (MS). The desorption temperature was optimized. The GC separation was performed in a capillary column. Detection limits were found to be of the order of ca. 1 ng g(-1). Relative recoveries of the analytes from soils were found to be highly dependent on soil organic-matter content and on compound identity; they ranged from ca 92 to 96% for sandy soil (extraction at room temperature) and from ca 27 to 55% for peaty soil (extraction at elevated temperature). A few real-world soil samples were analyzed; the individual monoaromatic hydrocarbon content ranged from below detection limits to 6.4 ng g(-1) for benzene and 8.1 for the total of p- + m-xylene.

  1. Carbon dioxide capture by functionalized solid amine sorbents with simulated flue gas conditions.

    PubMed

    Liu, Yamin; Ye, Qing; Shen, Mei; Shi, Jingjin; Chen, Jie; Pan, Hua; Shi, Yao

    2011-07-01

    A novel solid amine sorbent was prepared using KIT-6-type mesoporous silica modified with tetraethylenepentamine (TEPA). Its adsorption behavior toward CO(2) from simulated flue gases is investigated using an adsorption column. The adsorption capacities at temperatures of 303, 313, 333, 343, and 353 K are 2.10, 2.29, 2.58, 2.85, and 2.71 mmol g(-1), respectively. Experimental adsorption isotherms were obtained, and the average isosteric heat of adsorption was 43.8 kJ/mol. The adsorption capacity increases to 3.2 mmol g(-1) when the relative humidity (RH) of the simulated flue gas reaches 37%. The adsorption capacity is inhibited slightly by the presence of SO(2) at concentrations lower than 300 ppm but is not significantly influenced by NO at concentrations up to 400 ppm. The adsorbent is completely regenerated in 10 min at 393 K and a pressure of 5 KPa, with expected consumption energy of about 1.41 MJ kg(-1) CO(2). The adsorption capacity remains almost the same after 10 cycles of adsorption/regeneration with adsorption conditions of 10 vol % CO(2), 100 ppm SO(2), 200 ppm NO, 100% relative humidity, and a temperature of 393 K. The solid amine sorbent, KIT-6(TEPA), performs excellently for CO(2) capture and its separation from flue gas.

  2. Open-source MFIX-DEM software for gas-solids flows: Part II Validation studies

    SciTech Connect

    Li, Tingwen; Garg, Rahul; Galvin, Janine; Pannala, Sreekanth

    2012-01-01

    With rapid advancements in computer hardware and numerical algorithms, computational fluid dynamics (CFD) has been increasingly employed as a useful tool for investigating the complex hydrodynamics inherent in multiphase flows. An important step during the development of a CFD model and prior to its application is conducting careful and comprehensive verification and validation studies. Accordingly, efforts to verify and validate the open-source MFIX-DEM software, which can be used for simulating the gas solids flow using an Eulerian reference frame for the continuum fluid and a Lagrangian discrete framework (Discrete Element Method) for the particles, have been made at the National Energy Technology Laboratory (NETL). In part I of this paper, extensive verification studies were presented and in this part, detailed validation studies of MFIX-DEM are presented. A series of test cases covering a range of gas solids flow applications were conducted. In particular the numerical results for the random packing of a binary particle mixture, the repose angle of a sandpile formed during a side charge process, velocity, granular temperature, and voidage profiles from a bounded granular shear flow, lateral voidage and velocity profiles from a monodisperse bubbling fluidized bed, lateral velocity profiles from a spouted bed, and the dynamics of segregation of a binary mixture in a bubbling bed were compared with available experimental data, and in some instances with empirical correlations. In addition, sensitivity studies were conducted for various parameters to quantify the error in the numerical simulation.

  3. Unified phonon-based approach to the thermodynamics of solid, liquid and gas states

    NASA Astrophysics Data System (ADS)

    Bolmatov, Dima; Zav'yalov, Dmitry; Zhernenkov, Mikhail; Musaev, Edvard T.; Cai, Yong Q.

    2015-12-01

    We introduce a unified approach to states of matter (solid, liquid and gas) and describe the thermodynamics of the pressure-temperature phase diagram in terms of phonon excitations. We derive the effective Hamiltonian with low-energy cutoff in two transverse phonon polarizations (phononic band gaps) by breaking the symmetry in phonon interactions. Further, we construct the statistical mechanics of states of aggregation employing the Debye approximation. The introduced formalism covers the Debye theory of solids, the phonon theory of liquids, and thermodynamic limits such as the Dulong-Petit thermodynamic limit (cV = 3kB), the ideal gas limit (cV =3/2 kB) and the new thermodynamic limit (cV = 2kB), dubbed here the Frenkel line thermodynamic limit. We discuss the phonon propagation and localization effects in liquids above and below the Frenkel line, and explain the "fast sound" phenomenon. As a test for our theory we calculate velocity-velocity autocorrelation and pair distribution functions within the Green-Kubo formalism. We show the consistency between dynamics of phonons and pair correlations in the framework of the unified approach. New directions towards advancements in phononic band gaps engineering, hypersound manipulation technologies and exploration of exotic behaviour of fluids relevant to geo- and planetary sciences are discussed. The presented results are equally important both for practical implications and for fundamental research.

  4. High pressure operation of tubular solid oxide fuel cells and their intergration with gas turbines

    SciTech Connect

    Haynes, C.; Wepfer, W.J.

    1996-12-31

    Fossil fuels continue to be used at a rate greater than that of their natural formation, and the current byproducts from their use are believed to have a detrimental effect on the environment (e.g. global warming). There is thus a significant impetus to have cleaner, more efficient fuel consumption alternatives. Recent progress has led to renewed vigor in the development of fuel cell technology, which has been shown to be capable of producing high efficiencies with relatively benign exhaust products. The tubular solid oxide fuel cell developed by Westinghouse Electric Corporation has shown significant promise. Modeling efforts have been and are underway to optimize and better understand this fuel cell technology. Thus far, the bulk of modeling efforts has been for operation at atmospheric pressure. There is now interest in developing high-efficiency integrated gas turbine/solid oxide fuel cell systems. Such operation of fuel cells would obviously occur at higher pressures. The fuel cells have been successfully modeled under high pressure operation and further investigated as integrated components of an open loop gas turbine cycle.

  5. 1,8-Bis(phenylethynyl)anthracene - gas and solid phase structures.

    PubMed

    Lamm, Jan-Hendrik; Horstmann, Jan; Stammler, Hans-Georg; Mitzel, Norbert W; Zhabanov, Yuriy A; Tverdova, Natalya V; Otlyotov, Arseniy A; Giricheva, Nina I; Girichev, Georgiy V

    2015-09-07

    1,8-Bis(phenylethynyl)anthracene (1,8-BPEA) was synthesized by a twofold Kumada cross-coupling reaction. The molecular structure of 1,8-BPEA was determined using a combination of gas-phase electron diffraction (GED), mass spectrometry (MS), quantum chemical calculations (QC) and single-crystal X-ray diffraction (XRD). Five rotamers of the molecule with different orientations of phenylethynyl groups were investigated by DFT calculations. According to these, molecules of C2 symmetry with co-directional rotation of the phenylethynyl groups are predicted to exist in the gas phase at 498 K. This was confirmed by a GED/MS experiment at this temperature. The bonding of this conformer was studied and described in terms of an NBO-analysis. Dispersion interactions in the solid state structure and in the free molecule are discussed. In the solid this symmetry is broken; the asymmetric unit of the single crystal contains 3.5 molecules and a herringbone packing motif of π-stacked dimers and trimers. The π-stacking in the dimers is between the anthracene units, and the trimers are linked by π-stacking between phenyl and anthracene units. The interaction between these stacks can be described in terms of σ(C-H)π interactions.

  6. FORCE2: A multidimensional flow program for gas solids flow theory guide

    SciTech Connect

    Burge, S.W.

    1991-05-01

    This report describes the theory and structure of the FORCE2 flow program. The manual describes the governing model equations, solution procedure and their implementation in the computer program. FORCE2 is an extension of an existing B&V multidimensional, two-phase flow program. FORCE2 was developed for application to fluid beds by flow implementing a gas-solids modeling technology derived, in part, during a joint government -- industry research program, ``Erosion of FBC Heat Transfer Tubes,`` coordinated by Argonne National Laboratory. The development of FORCE2 was sponsored by ASEA-Babcock, an industry participant in this program. This manual is the principal documentation for the program theory and organization. Program usage and post-processing of code predictions with the FORCE2 post-processor are described in a companion report, FORCE2 -- A Multidimensional Flow Program for Fluid Beds, User`s Guide. This manual is segmented into sections to facilitate its usage. In section 2.0, the mass and momentum conservation principles, the basis for the code, are presented. In section 3.0, the constitutive relations used in modeling gas-solids hydrodynamics are given. The finite-difference model equations are derived in section 4.0 and the solution procedures described in sections 5.0 and 6.0. Finally, the implementation of the model equations and solution procedure in FORCE2 is described in section 7.0.

  7. Co-grinding significance for calcium carbonate-calcium phosphate mixed cement. Part I: effect of particle size and mixing on solid phase reactivity.

    PubMed

    Tadier, S; Le Bolay, N; Rey, C; Combes, C

    2011-04-01

    In part I of this study we aim to evaluate and control the characteristics of the powders constituting the solid phase of a vaterite CaCO(3)-dicalcium phosphate dihydrate cement using a co-grinding process and to determine their impact on cement setting ability. An original methodology involving complementary analytical techniques was implemented to thoroughly investigate the grinding mechanism of separated or mixed reactive powders and the effects on solid phase reactivity. We showed that the association of both reactive powders during co-grinding improves the efficiency of this process in terms of the particle size decrease, thus making co-grinding adaptable to industrial development of the cement. For the first time the usefulness of horizontal attenuated total reflection Fourier transform infrared spectroscopy to follow the chemical setting reaction at 37°C in real time has been demonstrated. We point out the antagonist effects that co-grinding can have on cement setting: the setting time is halved; however, progress of the chemical reaction involving dissolution-reprecipitation is delayed by 30 min, probably due to the increased contact area between the reactive powders, limiting their hydration. More generally, we can take advantage of the co-grinding process to control powder mixing, size and reactivity and this original analytical methodology to better understand its effect on the phenomena involved during powder processing and cement setting, which is decisive for the development of multi-component cements.

  8. Application of Headspace Solid Phase Microextraction and Gas Chromatography/Mass Spectrometry for Rapid Detection of the Chemical Warfare Agent Sulfur Mustard

    DTIC Science & Technology

    2002-05-16

    Title of Thesis: “Application of Headspace Solid Phase Microextraction and Gas Chromatography/Mass Spectrometry for Rapid...TITLE AND SUBTITLE Application of Headspace Solid Phase Microextraction and Gas Chromatography/Mass Spectrometry for Rapid Detection of the Chemical...phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS). Five commercially available SPME fibers were investigated to determine the

  9. Gas-solid carbonation as a possible source of carbonates in cold planetary environments

    NASA Astrophysics Data System (ADS)

    Garenne, A.; Montes-Hernandez, G.; Beck, P.; Schmitt, B.; Brissaud, O.; Pommerol, A.

    2013-02-01

    Carbonates are abundant sedimentary minerals at the surface and sub-surface of the Earth and they have been proposed as tracers of liquid water in extraterrestrial environments. Their formation mechanism is since generally associated with aqueous alteration processes. Recently, carbonate minerals have been discovered on Mars' surface by different orbitals or rover missions. In particular, the phoenix mission has measured from 1% to 5% of calcium carbonate (calcite type) within the soil (Smith et al., 2009). These occurrences have been reported in area where the relative humidity is significantly high (Boynton et al., 2009). The small concentration of carbonates suggests an alternative process on mineral grain surfaces (as suggested by Shaheen et al., 2010) than carbonation in aqueous conditions. Such an observation could rather point toward a possible formation mechanism by dust-gas reaction under current Martian conditions. To understand the mechanism of carbonate formation under conditions relevant to current Martian atmosphere and surface, we designed an experimental setup consisting of an infrared microscope coupled to a cryogenic reaction cell (IR-CryoCell setup). Three different mineral precursors of carbonates (Ca and Mg hydroxides, and a hydrated Ca silicate formed from Ca2SiO4), low temperature (from -10 to +30 °C), and reduced CO2 pressure (from 100 to 2000 mbar) were utilized to investigate the mechanism of gas-solid carbonation at mineral surfaces. These mineral materials are crucial precursors to form Ca and Mg carbonates in humid environments (0%gas-solid carbonation process or carbonate formation at the dust-water ice-CO2 interfaces could be a currently active Mars' surface

  10. Advanced system experimental facility: solid waste to methane gas. Background and process description

    SciTech Connect

    Isaacson, R.; Pfeffer, J.

    1981-03-01

    The Refuse Conversion to Methane Facility in Pompano Beach, Florida, a 100-ton/day experimental plant to convert municipal solid waste (MSW) to methane for fuel, has been built and is being tested. The facility has been designed to assess the technical merit of anaerobic digestion of the MSW process. Approximately 40 ton/day of volatile solids are fed to the digesters; of this, about 25 ton/day will be converted to gases. For each pound of volatile solids destroyed, 6.6 std. ft/sup 3/ of methane gas and 6.6 std. ft/sup 3/ of CO/sub 2/ will be produced. Thus, the plant will yield approximately 330,000 std. ft/sup 3//day each of methane and CO/sub 2/. This project provides a critical test of the most important process variables, thus allowing judgments to be made on scale-up considerations. The successful operation of this facility will yield information with a significant impact on potential commercial-scale plant developments. The background and theory involved in applying this technology to MSW, as well as details of the specific process line, are presented.

  11. Solids precipitation in crude oils, gas-to-liquids and their blends

    NASA Astrophysics Data System (ADS)

    Ramanathan, Karthik

    Gas-to-liquids (GTL) liquids are obtained from syngas by the Fischer-Tropsch synthesis. The blending of GTL liquids produced from natural gas/coal reserves and crude oils is a possibility in the near future for multiple reasons. Solids precipitation is a major problem in pipelines and refineries leading to significant additional operating costs. The effect of the addition of a paraffinic GTL liquid to crude oils on solids precipitation was investigated in this study. A Fourier transform infrared (FT-IR) spectroscopic technique was used to obtain solid-liquid equilibria (SLE) data for the various samples. The SLE of multiple systems of model oils composed of n-alkanes was investigated preliminarily. Blends of a model oil simulating a GTL liquid composition and a crude oil showed that the wax precipitation temperature (WPT) decreased upon blending. Three crude oils from different geographic regions (Alaskan North Slope, Colorado and Venezuela) and a laboratory-produced GTL liquid were used in the preparation of blends with five different concentrations of the GTL liquid. The wax precipitation temperatures of the blends were found to decrease with the increasing addition of the GTL liquid for all the oils. This effect was attributed to the solvent effect of the low molecular weight-paraffinic GTL liquid on the crude oils. The weight percent solid precipitated that was estimated as a function of temperature did not show a uniform trend for the set of crude oils. The asphaltene onset studies done on the blends with near-infrared spectroscopy indicated that the addition of GTL liquid could have a stabilizing effect on the asphaltenes in some oils. Analytical techniques such as distillation, solvent separation, HPLC, GC, and GPC were used to obtain detailed composition data on the samples. Two sets of compositional data with 49 and 86 pseudo-components were used to describe the three crude oils used in the blending work. The wax precipitation was calculated using a

  12. Thermal-Flow Code for Modeling Gas Dynamics and Heat Transfer in Space Shuttle Solid Rocket Motor Joints

    NASA Technical Reports Server (NTRS)

    Wang, Qunzhen; Mathias, Edward C.; Heman, Joe R.; Smith, Cory W.

    2000-01-01

    A new, thermal-flow simulation code, called SFLOW. has been developed to model the gas dynamics, heat transfer, as well as O-ring and flow path erosion inside the space shuttle solid rocket motor joints by combining SINDA/Glo, a commercial thermal analyzer. and SHARPO, a general-purpose CFD code developed at Thiokol Propulsion. SHARP was modified so that friction, heat transfer, mass addition, as well as minor losses in one-dimensional flow can be taken into account. The pressure, temperature and velocity of the combustion gas in the leak paths are calculated in SHARP by solving the time-dependent Navier-Stokes equations while the heat conduction in the solid is modeled by SINDA/G. The two codes are coupled by the heat flux at the solid-gas interface. A few test cases are presented and the results from SFLOW agree very well with the exact solutions or experimental data. These cases include Fanno flow where friction is important, Rayleigh flow where heat transfer between gas and solid is important, flow with mass addition due to the erosion of the solid wall, a transient volume venting process, as well as some transient one-dimensional flows with analytical solutions. In addition, SFLOW is applied to model the RSRM nozzle joint 4 subscale hot-flow tests and the predicted pressures, temperatures (both gas and solid), and O-ring erosions agree well with the experimental data. It was also found that the heat transfer between gas and solid has a major effect on the pressures and temperatures of the fill bottles in the RSRM nozzle joint 4 configuration No. 8 test.

  13. A pressurized thermogravimetric analyzer for use in studies of gas/solid systems. First technical report

    SciTech Connect

    Mitchell, R.E.

    1993-09-22

    A TG-151 Thermogravimetric Experimental Station, which measures and records weight changes of a solid material over a wide dynamic temperature range at a wide range of pressures in controlled environments, was purchased from Cahn Instruments, Inc. The TG-151 permits temperature to be programmed to follow a precise temperature profile of ramp and/or isothermal segments while monitoring the changes in weight of solid samples exposed to a gaseous environment of specified composition at a preset pressure. Weight and temperature measurements are made at user-specified time intervals and total time (up to 48 hours). Data are stored on the disk of a dedicated computer. The data can be processed by a data analysis program or exported to spreadsheet programs. The pressure vessel is designed to operate in vacuum to 10{sup {minus}5} torr and over a wide range of pressures. At normal room temperature, the TG-151 can operate up to 100 atm and at 1273 K, it can operate up to 70 atm. The null balance has a sensitivity of 10 micrograms, capacity up to 100 grams, and a dynamic range of 10{sup 6}:1. Both reducing and oxidizing environments can be established in the reaction chamber. For our specific needs the instrument had to be slightly modified to allow for two reactant gas streams to enter the pressure vessel at prescribed times. This required the purchase and installation of a gas blending system. The gas blending system permits coal and char samples to be heated at a specified rate to a desired temperature in an inert environment before the sample is exposed to an oxidizing environment.

  14. Constructing Solid-Gas-Interfacial Fenton Reaction over Alkalinized-C3N4 Photocatalyst To Achieve Apparent Quantum Yield of 49% at 420 nm.

    PubMed

    Li, Yunxiang; Ouyang, Shuxin; Xu, Hua; Wang, Xin; Bi, Yingpu; Zhang, Yuanfang; Ye, Jinhua

    2016-10-03

    Efficient generation of active oxygen-related radicals plays an essential role in boosting advanced oxidation process. To promote photocatalytic oxidation for gaseous pollutant over g-C3N4, a solid-gas interfacial Fenton reaction is coupled into alkalinized g-C3N4-based photocatalyst to effectively convert photocatalytic generation of H2O2 into oxygen-related radicals. This system includes light energy as power, alkalinized g-C3N4-based photocatalyst as an in situ and robust H2O2 generator, and surface-decorated Fe(3+) as a trigger of H2O2 conversion, which attains highly efficient and universal activity for photodegradation of volatile organic compounds (VOCs). Taking the photooxidation of isopropanol as model reaction, this system achieves a photoactivity of 2-3 orders of magnitude higher than that of pristine g-C3N4, which corresponds to a high apparent quantum yield of 49% at around 420 nm. In-situ electron spin resonance (ESR) spectroscopy and sacrificial-reagent incorporated photocatalytic characterizations indicate that the notable photoactivity promotion could be ascribed to the collaboration between photocarriers (electrons and holes) and Fenton process to produce abundant and reactive oxygen-related radicals. The strategy of coupling solid-gas interfacial Fenton process into semiconductor-based photocatalysis provides a facile and promising solution to the remediation of air pollution via solar energy.

  15. Pneumatic nebulization gas-solid extraction of triazine herbicides in vegetable.

    PubMed

    Li, Na; Jin, Haiyan; Nian, Li; Wang, Yeqiang; Lei, Lei; Zhang, Rui; Zhang, Hanqi; Yu, Yong

    2013-08-23

    The pneumatic nebulization gas-solid extraction (PN-GSE) high-performance liquid chromatography (HPLC) was developed and applied to the extraction, separation and determination of triazine herbicides in vegetables. The herbicides were ultrasonically extracted from vegetables with 70% methanol in water. Then the extract was introduced to PN-GSE system to further clean-up. The experimental parameters, including type and concentration of extraction solvent, ratio of solvent to sample, pH value of sample solution and PN-GSE solution, extraction time, temperature, type of sorbent, flow rate of carrier gas, pumping rate of gas, and kind and volume of elution solvent, were investigated and optimized. The limits of detection for seven herbicides range from 0.59 to 1.05μg/kg. The recoveries of the herbicides are in the range of 86.2-110.6% and relative standard deviations are equal or less than 7.51%, when the present method was applied to the analysis of spiked samples. The present method was applied to the analysis of real samples and the results were satisfactory.

  16. Characterization of gas produced by the anaerobic digestion of municipal solid waste

    SciTech Connect

    Gerrish, H.P.; Daly, E.L.; Lascarro, J.F.; Nemerow, N.; Sengupta, S.; Wong, K.F.

    1980-12-01

    A large-scale proof-of-concept facility has been constructed in Pompano, Florida, to evaluate the feasibility of producing methane-rich gas from the anaerobic digestion of municipal solid waste. The University of Miami together with the AMES Research Laboratory are participating in the environmental source assessment of that technology. The ultimate goal is to determine if the products are environmentally acceptable or are of less environmental consequence (with or without controls) than if generated in an unprocessed landfill. This paper describes the gas analysis procedure and the gas composition as determined to date for unstable, lower mesophilic (30/sup 0/-40/sup 0/C) digester conditions and with the plant operating at only 15% of its design capacity. It is observed that the composition of the biogas from the large-scale facility is quite similar, with the possible exception of H/sub 2/S and NH/sub 3/, to that produced by small-scale digesters and in landfills. The CH/sub 4/ and CO/sub 2/ levels varied significantly about mean values of 55% and 45% respectively. At this stage of the evaluation, it appears that the potential environmental concern might be from the odorous components of the biogas.

  17. Planetesimal Growth through the Accretion of Small Solids: Hydrodynamics Simulations with Gas-Particle Coupling

    NASA Astrophysics Data System (ADS)

    Hughes, Anna; Boley, Aaron C.

    2016-10-01

    The growth and migration of planetesimals in young protoplanetary disks are fundamental to the planet formation process. A number of mechanisms seemingly inhibit small grains from growing to sizes much larger than a centimeter, limiting planetesimal growth. In spite of this, the meteoritic record, abundance of exoplanets, and the lifetimes of disks considered altogether indicate that growth must be rapid and common. If a small number of 100-km sized planetesimals do form by some method such as the streaming instability, then gas drag effects could enable those objects to accrete small solids efficiently. In particular, accretion rates for such planetesimals could be higher or lower than rates based on the geometric cross-section and gravitational focusing alone. The local gas conditions and properties of accreting bodies select a locally optimal accretion size for the pebbles. As planetesimals accrete pebbles, they feel an additional angular momentum exchange - causing the planetesimal to slowly drift inward, which becomes significant at short orbital periods. We present self-consistent hydrodynamic simulations with direct particle integration and gas-drag coupling to evaluate the rate of planetesimal growth due to pebble accretion. We explore a range of particle sizes, planetesimal properties, and disk conditions using wind tunnel simulations. These results are followed by numerical analysis of planetesimal drift rates at a variety of stellar distances.

  18. Combined solid oxide fuel cell and gas turbine systems for efficient power and heat generation

    NASA Astrophysics Data System (ADS)

    Palsson, Jens; Selimovic, Azra; Sjunnesson, Lars

    The Department of Heat and Power Engineering at Lund University in Sweden has been conducting theoretical studies of combined SOFC and gas turbine (SOFC/GT) cycles. The overall goal is an unbiased evaluation of performance prospects and operational behaviour of such systems. The project is part of a Swedish national program on high-temperature fuel cells. Results of continuous studies started earlier by authors are presented. Recent developments in modelling techniques has resulted in a more accurate fuel cell model giving an advantage over previous system studies based on simplified SOFC models. The fuel cell model has been improved by detailed representation of resistive cell losses, reaction kinetics for the reforming reaction and heat conduction through the solid part of the cell. This SOFC model has further been confirmed against the literature and integrated into simulation software, Aspen Plus™. Recent calculations have focused on a system with external pre-reforming and anode gas recirculation for the internal supply of steam. A reference system, sized at 500 kW, has also been analyzed in variants with gas turbine reheat and air compression intercooling. In addition, knowledge of stack and system behaviour has been gained from sensitivity studies. It is shown that the pressure ratio has a large impact on performance and that electrical efficiencies of more than 65% are possible at low pressure ratios.

  19. Solid-gas reactions of complex oxides inside an environmental high-resolution transmission electron microscope.

    PubMed

    Sayagués, M J; Krumeich, F; Hutchison, J L

    2001-07-01

    In a gas reaction cell (GRC), installed in a high-resolution transmission electron microscope (HRTEM) (JEOL 4000EX), samples can be manipulated in an ambient atmosphere (p<50mbar). This experimental setup permits not only the observation of solid-gas reactions in situ at close to the atomic level but also the induction of structural modifications under the influence of a plasma, generated by the ionization of gas particles by an intense electron beam. Solid state reactions of non-stoichiometric niobium oxides and niobium tungsten oxides with different gases (O2, H2 and He) have been carried out inside this controlled environment transmission electron microscope (CETEM), and this has led to reaction products with novel structures which are not accessible by conventional solid state synthesis methods. Monoclinic and orthorhombic Nb(12)O(29) crystallize in block structures comprising [3x4] blocks. The oxidation of the monoclinic phase occurs via a three step mechanism: firstly, a lamellar defect of composition Nb(11)O(27) is formed. Empty rectangular channels in this defect provide the diffusion paths in the subsequent oxidation. In the second step, microdomains of the Nb(22)O(54) phase are generated as an intermediate state of the oxidation process. The structure of the final product Nb(10)O(25), which consists of [3x3] blocks and tetrahedral coordinated sites, is isostructural to PNb(9)O(25). Microdomains of this apparently metastable phase appear as a product of the Nb(22)O(54) oxidation. The oxidation reaction of Nb(12)O(29) was found to be a reversible process: the reduction of the oxidation product with H(2) results in the formation of the starting Nb(12)O(29) structure. On the other hand, the block structure of Nb(12)O(29) has been destroyed by a direct treatment of the sample with H(2) while NbO in a cubic rock salt structure is produced. This in situ technique has also been applied to niobium tungsten oxides which constitute the solid solution series Nb(8-n

  20. Ditechnetium heptoxide revisited: Solid-state, gas-phase, and theoretical studies

    SciTech Connect

    Childs, Bradley C.; Braband, Henrik; Lawler, Keith; Mast, Daniel S.; Bigler, Laurent; Stalder, Urs; Forster, Paul M.; Czerwinski, Kenneth R.; Alberto, Roger; Sattelberger, Alfred P.; Poineau, Frederic

    2016-10-04

    Here, ditechnetium heptoxide was synthesized from the oxidation of TcO2 with O2 at 450 °C and characterized by single crystal X-ray diffraction (SCXRD), electron impact mass spectrometry (EI-MS) and theoretical methods. Refinement of the structure at 100 K indicates that Tc2O7 crystallizes as a molecular solid in the orthorhombic space group Pbca (a = 7.312(3) Å, b = 5.562(2) Å, c = 13.707(5) Å, V = 557.5(3) Å3). The Tc2O7 molecule can be described as corner-sharing TcO4 tetrahedra (Tc---Tc = 3.698(1) Å and Tc-OBri-Tc = 180.0°). The EI-MS spectrum of Tc2O7 consists of both mononuclear and dinuclear species. The main dinuclear species in the gas-phase are Tc2O7 (100%) and Tc2O5 (56%), while the main mononuclear species are TcO3 (33.9%) and TcO2 (42.8%). The difference in the relative intensities of the M2O5 (M = Tc, Re) fragments (1.7% for Re) indicate that these Group 7 elements exhibit different gas phase chemistry. The solid-state structure of Tc2O7 was investigated by density functional theory (DFT) methods. The optimized structure of the Tc2O7 molecule is in good agreement with the experimental one. Simulations indicate that the more favorable geometry for the Tc2O7 molecule in the gas-phase is bent (Tc-OBri-Tc = 156.5°), while linear (Tc-OBri-Tc = 180.0°) is favored in the solid state.

  1. Direct gas-solid carbonation kinetics of steel slag and the contribution to in situ sequestration of flue gas CO(2) in steel-making plants.

    PubMed

    Tian, Sicong; Jiang, Jianguo; Chen, Xuejing; Yan, Feng; Li, Kaimin

    2013-12-01

    Direct gas-solid carbonation of steel slag under various operational conditions was investigated to determine the sequestration of the flue gas CO2 . X-ray diffraction analysis of steel slag revealed the existence of portlandite, which provided a maximum theoretical CO2 sequestration potential of 159.4 kg CO 2 tslag (-1) as calculated by the reference intensity ratio method. The carbonation reaction occurred through a fast kinetically controlled stage with an activation energy of 21.29 kJ mol(-1) , followed by 10(3) orders of magnitude slower diffusion-controlled stage with an activation energy of 49.54 kJ mol(-1) , which could be represented by a first-order reaction kinetic equation and the Ginstling equation, respectively. Temperature, CO2 concentration, and the presence of SO2 impacted on the carbonation conversion of steel slag through their direct and definite influence on the rate constants. Temperature was the most important factor influencing the direct gas-solid carbonation of steel slag in terms of both the carbonation conversion and reaction rate. CO2 concentration had a definite influence on the carbonation rate during the kinetically controlled stage, and the presence of SO2 at typical flue gas concentrations enhanced the direct gas-solid carbonation of steel slag. Carbonation conversions between 49.5 % and 55.5 % were achieved in a typical flue gas at 600 °C, with the maximum CO2 sequestration amount generating 88.5 kg CO 2 tslag (-1) . Direct gas-solid carbonation of steel slag showed a rapid CO2 sequestration rate, high CO2 sequestration amounts, low raw-material costs, and a large potential for waste heat utilization, which is promising for in situ carbon capture and sequestration in the steel industry.

  2. Modeling the Gas Dynamics Environment in a Subscale Solid Rocket Test Motor

    NASA Technical Reports Server (NTRS)

    Eaton, Andrew M.; Ewing, Mark E.; Bailey, Kirk M.; McCool, Alex (Technical Monitor)

    2001-01-01

    Subscale test motors are often used for the evaluation of solid rocket motor component materials such as internal insulation. These motors are useful for characterizing insulation performance behavior, screening insulation material candidates and obtaining material thermal and ablative property design data. One of the primary challenges associated with using subscale motors however, is the uncertainty involved when extrapolating the results to full-scale motor conditions. These uncertainties are related to differences in such phenomena as turbulent flow behavior and boundary layer development, propellant particle interactions with the wall, insulation off-gas mixing and thermochemical reactions with the bulk flow, radiation levels, material response to the local environment, and other anomalous flow conditions. In addition to the need for better understanding of physical mechanisms, there is also a need to better understand how to best simulate these phenomena using numerical modeling approaches such as computational fluid dynamics (CFD). To better understand and model interactions between major phenomena in a subscale test motor, a numerical study of the internal flow environment of a representative motor was performed. Simulation of the environment included not only gas dynamics, but two-phase flow modeling of entrained alumina particles like those found in an aluminized propellant, and offgassing from wall surfaces similar to an ablating insulation material. This work represents a starting point for establishing the internal environment of a subscale test motor using comprehensive modeling techniques, and lays the groundwork for improving the understanding of the applicability of subscale test data to full-scale motors. It was found that grid resolution, and inclusion of phenomena in addition to gas dynamics, such as two-phase and multi-component gas composition are all important factors that can effect the overall flow field predictions.

  3. Effects of Ti addiction in WO 3 thin film ammonia gas sensor prepared by dc reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Hu, Ming; Yong, Cholyun; Feng, Youcai; Lv, Yuqiang; Han, Lei; Liang, Jiran; Wang, Haopeng

    2006-11-01

    WO 3 sensing films (1500 Å) were deposited using dc reactive magnetron sputtering method on alumina substrate on which patterned interdigital Pt electrodes were previously formed. The additive Ti was sputtered with different thickness (100-500 Å) onto WO 3 thin films and then the films as-deposited were annealed at 400°C in air for 3h. The crystal structure and chemical composition of the films were characterized by XRD and XPS analysis. The effect of Ti addition on sensitive properties of WO 3 thin film to the NH 3 gas was then discussed. WO 3 thin films added Ti revealed excellent sensitivity and response characteristics in the presence of low concentration of NH 3 (5-400 ppm) gas in air at 200°C operating temperature. Especially,in case 300 Å thickness of additive Ti, WO 3 thin films have a promotional effect on the response speed to NH 3 and selectivity enhanced with respect to other gases (CO, C IIH 5OH, CH 4). The influence of different substrates, including alumina, silicon and glass, on sensitivity to NH 3 gas has also been investigated.

  4. Effect of Organic Coatings on the Reactivity of Gas-Phase Ozone with Particle-Borne PAHs

    NASA Astrophysics Data System (ADS)

    Zhou, S.; McWhinney, R. D.; Lee, A.; Shiraiwa, M.; Poeschl, U.; Abbatt, J.

    2012-12-01

    Organic aerosols can undergo various physical and chemical transformations and hence change their properties e.g. hygroscopicity, density, toxicity and composition via atmospheric oxidative 'aging'. Both field and laboratory studies show evidence that heterogeneous surface reactions contribute to aerosol aging, however, the aerosol oxidation rate and mechanism remain poorly understood. One question that remains unclear is whether or not bulk reactions in the particle following heterogeneous uptake of reactive species (such as OH, NO3 and O3) contribute to the aerosol aging process. It is now well recognized that surface-bound PAHs react rapidly under typical atmospheric oxidant conditions. However, it is not known the degree to which this reactivity is suppressed by organic coatings that (initially) bury the PAH. In the present study, we are expanding upon recent studies of the reactions between O3 and particle-borne PAHs conducted by both our group and others. In particular, flow tube kinetics studies will be presented of ozone reacting with thin layers of PAH adsorbed to ammonium sulfate particles with a range of different overlying organic coatings (e.g. organic liquids, solids, and secondary organic aerosol (SOA) from ozonolysis of α-pinene). The effects of the coating materials, especially the phases of the organic coatings and the relative humidity, on the heterogeneous kinetics will be presented. Moreover, with the application of a kinetic multi-layer model the reaction mechanisms will be presented with estimates for the rates of diffusion of reactants through the organic layers.

  5. Experimental Study on Gas-Solid Flow Charcteristics in a CFB Riser Of 54M in Height

    NASA Astrophysics Data System (ADS)

    Hu, N.; Yang, H. R.; Zhang, H.; Zhang, R. Q.; Cao, J. N.; Liu, Q.; Lu, J. F.; Yue, G. X.

    Understanding the height effect on the gas-solid flow characteristics in a CFB riser is important as more and more large capacity CFB boilers are used and to be developed. In this study, a cold CFB test rig with a riser of 240mm in LD. and 38m and 54m in height was built. The influences of operating conditions, such as solid inventory and fluidizing gas velocity, on the axial voidage profile along the riser were assessed. When the gas velocity exceeds the transport velocity, the S-shaped profile of voidage in the riser was established. At the same time, the voidage in top-dilute section reached the saturation carrying capacity, and the solids circulation rate did not vary with the height of the riser nor the solids inventory. It was also found the critical solids inventory for the saturation carrying capacity increases as the riser height increases. When the height was changed from 38m to 54m, the critical solids inventory increased about 25% from about 40kg to about 50kg, and pressure drop in the furnace also increased about 25%.

  6. Electrostatic sensors applied to the measurement of electric charge transfer in gas solids pipelines

    NASA Astrophysics Data System (ADS)

    Woodhead, S. R.; Denham, J. C.; Armour-Chelu, D. I.

    2005-01-01

    This paper describes the development of a number of electric charge sensors. The sensors have been developed specifically to investigate triboelectric charge transfer which takes place between particles and the pipeline wall, when powdered materials are conveyed through a pipeline using air. A number of industrial applications exist for such gas solids pipelines, including pneumatic conveyors, vacuum cleaners and dust extraction systems. The build-up of electric charge on pipelines and powdered materials can lead to electrostatic discharge and so is of interest from a safety viewpoint. The charging of powders can also adversely affect their mechanical handling characteristics and so is of interest to handling equipment engineers. The paper presents the design of the sensors, the design of the electric charge test rig and electric charge measurement test results.

  7. New technique for determining the parameters of gas permeation through solids

    SciTech Connect

    Kohls, J.F.

    1980-01-01

    The solution of Fick's equation for gas permeation through solid flat membranes yields a throughput rate equation with two unknown parameters, diffusivity and solubility. The common methods used to evaluate these parameters rely on knowing the equilibrium throughout rate. This equilibrium rate is in some cases rapidly established (on the order of seconds), in other cases slowly established (order of months). Thus, permeation measurements may require equipment usage over a long time period, precluding its use for other experience. A mathematical technique for predicting the permeation parameters using the unequilibrated portion of the permeation throughout curve has been developed which overcomes this difficulty. The method developed (termed stabilized search) was tested with data simulated using a known amount of error. The predicted parameters were as accurate as the data, but the values were generated in only 20 to 40% of the time required for other methods.

  8. New mathematical technique for determining the parameters of gas permeation through solids

    SciTech Connect

    Kohls, J.F.

    1980-01-01

    The solution of Fick's equation for gas permeation through solid flat membranes yields a throughput rate equation with two unknown parameters, diffusivity and solubility. The common methods used to evaluate these parameters rely on knowing the equilibrium throughput rate. This equilibrium rate is in some cases rapidly established (on the order of seconds), in other cases slowly established (order of months). Thus, permeation measurements may require equipment usage over a long time period, precluding its use for other experiments. A mathematical technique for predicting the permeation parameters using the unequilibrated portion of the permeation throughput curve has been developed which overcomes this difficulty. The method developed (termed stabilized search) was tested with data simulated using a known amount of error. The predicted parameters were as accurate as the data, but the values were generated in only 20 to 40% of the time required for other methods.

  9. Harsh-Environment Solid-State Gamma Detector for Down-hole Gas and Oil Exploration

    SciTech Connect

    Peter Sandvik; Stanislav Soloviev; Emad Andarawis; Ho-Young Cha; Jim Rose; Kevin Durocher; Robert Lyons; Bob Pieciuk; Jim Williams; David O'Connor

    2007-08-10

    The goal of this program was to develop a revolutionary solid-state gamma-ray detector suitable for use in down-hole gas and oil exploration. This advanced detector would employ wide-bandgap semiconductor technology to extend the gamma sensor's temperature capability up to 200 C as well as extended reliability, which significantly exceeds current designs based on photomultiplier tubes. In Phase II, project tasks were focused on optimization of the final APD design, growing and characterizing the full scintillator crystals of the selected composition, arranging the APD device packaging, developing the needed optical coupling between scintillator and APD, and characterizing the combined elements as a full detector system preparing for commercialization. What follows is a summary report from the second 18-month phase of this program.

  10. Non-invasive medical diagnostics by nanoparticle-based solid-state gas sensors

    NASA Astrophysics Data System (ADS)

    Tricoli, Antonio

    2013-08-01

    Chemical sensors made of tailored nanoparticles offer excellent miniaturization capability and are able to rapidly and continuously detect trace amounts of important analytes down to trace concentrations. Application of these sensing materials to non-invasive medical diagnostics by breath analysis has the potential to drastically reduce diagnostics costs while offering better service quality to the patients and enabling very early-stage detection of severe illnesses such as lung cancer. Here, we present a flexible approach to synthesize advanced solid-state gas sensor materials that have demonstrated reliable detection of important breath markers. In particular, the feasibility of capturing highly performing, meta-stable sensing nanoparticles by flame-synthesis of multi component metal-oxides is critically discussed.

  11. Emergence of a Metallic Quantum Solid Phase in a Rydberg-Dressed Fermi Gas.

    PubMed

    Li, Wei-Han; Hsieh, Tzu-Chi; Mou, Chung-Yu; Wang, Daw-Wei

    2016-07-15

    We examine possible low-temperature phases of a repulsively Rydberg-dressed Fermi gas in a three-dimensional free space. It is shown that the collective density excitations develop a roton minimum, which is softened at a wave vector smaller than the Fermi wave vector when the particle density is above a critical value. The mean field calculation shows that, unlike the insulating density wave states often observed in conventional condensed matters, a self-assembled metallic density wave state emerges at low temperatures. In particular, the density wave state supports a Fermi surface and a body-centered-cubic crystal order at the same time with the estimated critical temperature being about one tenth of the noninteracting Fermi energy. Our results suggest the emergence of a fermionic quantum solid that should be observable in the current experimental setup.

  12. Toluene vapor capture by activated carbon particles in a dual gas-solid cyclone system.

    PubMed

    Lim, Yun Hui; Ngo, Khanh Quoc; Park, Young Koo; Jo, Young Min

    2012-08-01

    Capturing of odorous compounds such as toluene vapor by a particulate-activated carbon adsorbent was investigated in a gas-solid cyclone, which is one type of mobile beds. The test cyclone was early modified with the post cyclone (PoC) and a spiral flow guide to the vortex finder. The proposed process may contribute to the reduction of gases and dust from industrial exhausts, especially when dealing with a low concentration of odorous elements and a large volume ofdust flow. In this device, the toluene capturing efficiency at a 400 ppm concentration rose up to 77.4% when using activated carbon (AC) particles with a median size of 27.03 microm. A maximum 96% of AC particles could be collected for reuse depending on the size and flow rate. The AC regenerated via thermal treatment showed an adsorption potential up to 66.7% throughout repeated tests.

  13. Energy recuperation in solid oxide fuel cell (SOFC) and gas turbine (GT) combined system

    NASA Astrophysics Data System (ADS)

    Kuchonthara, Prapan; Bhattacharya, Sankar; Tsutsumi, Atsushi

    A combined power generation system consisting of a solid oxide fuel cell (SOFC) and a gas turbine (GT) with steam and heat recuperation (HR) was evaluated using a commercial process simulation tool, ASPEN Plus. The effect of steam recuperation (SR) on the overall efficiency of the combined system was investigated by comparing the SOFC-GT during heat and steam recuperation (HSR) against the system during only heat recuperation. At low turbine inlet temperatures (TITs), the overall efficiency of the SOFC-GT combined system with heat and steam recuperation improved by showing an increase in TIT and a reduction in pressure ratio (PR). On the other hand, at high TITs, the opposite trend was observed. The integration of steam recuperation was found to improve the overall efficiency and specific power of SOFC-GT combined systems with a relatively compact SOFC component.

  14. [Determination of organophosphorous pesticide residues in red wine by solid phase microextraction-gas chromatography].

    PubMed

    Hu, Yuan; Liu, Wenmin; Zhou, Yanming; Guan, Yafeng

    2006-05-01

    A method for the determination of 12 organophosphorus pesticide residues (OPs) in red wine by fiber solid phase microextraction (SPME) coupled with gas chromatography (GC) was developed and validated. The SPME phase was prepared by sol-gel technology of physical incorporation. The extraction conditions were optimized with the results of stirring rate of 1,250 r/min, NaCl mass concentration of 150 g/L, and extraction time of 30 min. With the sample volume of 25 mL, the relative standard deviations (RSD) of peak areas for most of OPs were below 5%, and the detection limits of OPs were in the range of 5 ng/L-0.38 microg/L. It can be seen from the results that this method has the potential to analyze OPs in other beverages and soft drinking materials.

  15. Particle acceleration model for gas--solid suspensions at moderate Reynolds numbers

    NASA Astrophysics Data System (ADS)

    Tenneti, Sudheer; Garg, Rahul; Hrenya, Christine; Fox, Rodney; Subramaniam, Shankar

    2009-11-01

    Particle granular temperature plays an important role in the prediction of core annular structure in riser flows. The covariance of fluctuating particle acceleration and fluctuating particle velocity governs the evolution of the granular temperature in homogeneous suspensions undergoing elastic collisions. Koch and co--workers (Phys. Fluid. 1990, JFM 1999) showed that the granular temperature has a source term due to hydrodynamic interactions in gas--solid suspensions in the Stokes flow regime. We performed direct numerical simulations (DNS) of freely evolving suspensions at moderate Reynolds numbers using the immersed boundary method (IBM). We found that simple extension of a class of mean particle acceleration models to their instantaneous counterparts does not predict the correct fluctuating particle acceleration--fluctuating velocity covariance that is obtained from DNS. The fluctuating particle velocity autocorrelation function decay and the Lagrangian structure function obtained from DNS motivate the use of a Langevin model for the instantaneous particle acceleration.

  16. Study of Gas Solid Flow Characteristics in Cyclone Inlet Ducts of A300Mwe CFB Boiler

    NASA Astrophysics Data System (ADS)

    Tang, J. Y.; Lu, X. F.; Lai, J.; Liu, H. Z.

    Gas solid flow characteristics in cyclone's inlet duct of a 300MW CFB boiler were studied in a cold circulating fluidized bed (CFB) experimental setup according to a 410t/h CFB boiler with a scale of 10∶1. Tracer particles were adopted in the experiment and their motion trajectories in the two kinds of cyclone's inlet ducts were photographed by a high-speed camera. By analyzing the motion trajectories of tracer particles, acceleration performance of particle phases in the two inlet ducts was obtained. Results indicate that the acceleration performance of particles in the long inlet duct is better than that in the short inlet duct, but the pressure drop of the long inlet duct is higher. Meanwhile, under the same operating conditions, both the separation efficiency and the pressure drop of the cyclone are higher when the cyclone is connected with the long inlet duct. Figs 11, Tabs 4 and refs 10.

  17. Analytical flow/thermal modeling of combustion gas flows in Redesigned Solid Rocket Motor test joints

    NASA Technical Reports Server (NTRS)

    Woods, G. H.; Knox, E. C.; Pond, J. E.; Bacchus, D. L.; Hengel, J. E.

    1992-01-01

    A one-dimensional analytical tool, TOPAZ (Transient One-dimensional Pipe flow AnalyZer), was used to model the flow characteristics of hot combustion gases through Redesigned Solid Rocket Motor (RSRM) joints and to compute the resultant material surface temperatures and o-ring seal erosion of the joints. The capabilities of the analytical tool were validated with test data during the Seventy Pound Charge (SPC) motor test program. The predicted RSRM joint thermal response to ignition transients was compared with test data for full-scale motor tests. The one-dimensional analyzer is found to be an effective tool for simulating combustion gas flows in RSRM joints and for predicting flow and thermal properties.

  18. The effects of gas-fluid-rock interactions on CO2 injection and storage: Insights from reactive transport modeling

    SciTech Connect

    Xiao, Y.; Xu, T.; Pruess, K.

    2008-10-15

    Possible means of reducing atmospheric CO{sub 2} emissions include injecting CO{sub 2} in petroleum reservoirs for Enhanced Oil Recovery or storing CO{sub 2} in deep saline aquifers. Large-scale injection of CO{sub 2} into subsurface reservoirs would induce a complex interplay of multiphase flow, capillary trapping, dissolution, diffusion, convection, and chemical reactions that may have significant impacts on both short-term injection performance and long-term fate of CO{sub 2} storage. Reactive Transport Modeling is a promising approach that can be used to predict the spatial and temporal evolution of injected CO{sub 2} and associated gas-fluid-rock interactions. This presentation will summarize recent advances in reactive transport modeling of CO{sub 2} storage and review key technical issues on (1) the short- and long-term behavior of injected CO{sub 2} in geological formations; (2) the role of reservoir mineral heterogeneity on injection performance and storage security; (3) the effect of gas mixtures (e.g., H{sub 2}S and SO{sub 2}) on CO{sub 2} storage; and (4) the physical and chemical processes during potential leakage of CO{sub 2} from the primary storage reservoir. Simulation results suggest that CO{sub 2} trapping capacity, rate, and impact on reservoir rocks depend on primary mineral composition and injecting gas mixtures. For example, models predict that the injection of CO{sub 2} alone or co-injection with H{sub 2}S in both sandstone and carbonate reservoirs lead to acidified zones and mineral dissolution adjacent to the injection well, and carbonate precipitation and mineral trapping away from the well. Co-injection of CO{sub 2} with H{sub 2}S and in particular with SO{sub 2} causes greater formation alteration and complex sulfur mineral (alunite, anhydrite, and pyrite) trapping, sometimes at a much faster rate than previously thought. The results from Reactive Transport Modeling provide valuable insights for analyzing and assessing the dynamic

  19. Dry Scrubbing of Aluminum Cell Gases: Design and Operating Characteristics of a Novel Gas/Solids Reactor

    NASA Astrophysics Data System (ADS)

    Lamb, W. D.; Reeve, Martin R.; Dethloff, F. H.; Leinum, Magne

    1982-11-01

    Engineering details of a pilot plant reactor are described. It comprises a vertical cylindrical vessel with a tangential bottom gas entry. Countercurrent spiraling gas-solids flow is achieved. Reacted solids can be withdrawn from the bottom or the top using a rising axial gas jet. The reactor was evaluated by testing in a dry scrubber system treating 14,000 m3/h of gas from prebake cells. At inlet concentrations of 30-60 mg/m3 it achieved 99.5% scrubbing efficiency with aluminas of a surface area of 45-80 m2/g at feed rates considerably less than cell requirements. Potential benefits are: 1) control of metal purity by segregation of scrubber catch to selected cells, 2) scrubbing high HF inlet concentrations at full feed rate, and 3) meeting more stringent working environment and stack emission requirements.

  20. Origin of melting point depression for rare gas solids confined in carbon pores.

    PubMed

    Morishige, Kunimitsu; Kataoka, Takaaki

    2015-07-21

    To obtain insights into the mechanism of the melting-point depression of rare gas solids confined in crystalline carbon pores, we examined the freezing and melting behavior of Xe and Ar confined to the crystalline pores of ordered mesoporous carbons as well as compressed exfoliated graphite compared to the amorphous pores of ordered mesoporous silicas, by means of X-ray diffraction. For the Xe and Ar confined to the crystalline carbon pores, there was no appreciable thermal hysteresis between freezing and melting. Furthermore, the position of the main diffraction peak did not change appreciably on freezing and melting. This strongly suggests that the liquids confined in the carbon pores form a multilayered structure parallel to the smooth walls. For the Xe and Ar confined to the amorphous silica pores, on the other hand, the position of the main diffraction peak shifted into higher scattering angle on freezing suggested that the density of the confined solid is distinctly larger than for the confined liquid. Using compressed exfoliated graphite with carbon walls of higher crystallinity, we observed that three-dimensional (3D) microcrystals of Xe confined in the slit-shaped pores melted to leave the unmelted bilayers on the pore walls below the bulk triple point. The lattice spacing of the 3D microcrystals confined is larger by ∼0.7% than that of the bilayer next to the pore walls in the vicinity of the melting point.

  1. Origin of melting point depression for rare gas solids confined in carbon pores

    SciTech Connect

    Morishige, Kunimitsu Kataoka, Takaaki

    2015-07-21

    To obtain insights into the mechanism of the melting-point depression of rare gas solids confined in crystalline carbon pores, we examined the freezing and melting behavior of Xe and Ar confined to the crystalline pores of ordered mesoporous carbons as well as compressed exfoliated graphite compared to the amorphous pores of ordered mesoporous silicas, by means of X-ray diffraction. For the Xe and Ar confined to the crystalline carbon pores, there was no appreciable thermal hysteresis between freezing and melting. Furthermore, the position of the main diffraction peak did not change appreciably on freezing and melting. This strongly suggests that the liquids confined in the carbon pores form a multilayered structure parallel to the smooth walls. For the Xe and Ar confined to the amorphous silica pores, on the other hand, the position of the main diffraction peak shifted into higher scattering angle on freezing suggested that the density of the confined solid is distinctly larger than for the confined liquid. Using compressed exfoliated graphite with carbon walls of higher crystallinity, we observed that three-dimensional (3D) microcrystals of Xe confined in the slit-shaped pores melted to leave the unmelted bilayers on the pore walls below the bulk triple point. The lattice spacing of the 3D microcrystals confined is larger by ∼0.7% than that of the bilayer next to the pore walls in the vicinity of the melting point.

  2. The effects of flue gas desulfurization (FGD) system additives on solid by-products. Final report

    SciTech Connect

    Huyck, K.A.; Tatum, G.S.; DeKraker, D.P.

    1995-12-01

    This study was designed to examine characteristics of by-products from flue gas desulfurization (FGD) systems that use performance-enhancing additives. The by-products were evaluated for handling, disposal, properties, and utilization potential. This study was designed to identify potential operation-limiting consequences (fatal flaws) caused by using FGD system additives. It was not intended to be an all-encompassing study of the possible process, environmental, and utilization circumstances at each plant. Seven utilities conducting additive testing agreed to provide samples for this study both before and during their testing. Solid samples were collected from FGD systems using the following additives: di-basic acid (DBA), which is a mixture of succinic, glutaric, and adipic acids; formate; sulfur; ethylene diamine tetraacetic acid (EDTA); and chloride. Changes in handling properties that may alter process operations were observed at sites where DBS was used. Changes in leaching behavior, permeability and unconfined compressive strength (properties that affect by-product disposal properties) showed no clear trend for additive or system type. The intent of this study is to provide an overall assessment of potential system-limiting effects of FGD additive use. There were no overriding problems relating to disposal with the use of additives. However, properties of solids produced with and without additives should be tested at each site prior to use of an FGD system additive. This is necessary because of the variability in state disposal and permitting requirements and the influence of specific operating conditions on by-product properties.

  3. Lattice Boltzmann simulation of the gas-solid adsorption process in reconstructed random porous media.

    PubMed

    Zhou, L; Qu, Z G; Ding, T; Miao, J Y

    2016-04-01

    The gas-solid adsorption process in reconstructed random porous media is numerically studied with the lattice Boltzmann (LB) method at the pore scale with consideration of interparticle, interfacial, and intraparticle mass transfer performances. Adsorbent structures are reconstructed in two dimensions by employing the quartet structure generation set approach. To implement boundary conditions accurately, all the porous interfacial nodes are recognized and classified into 14 types using a proposed universal program called the boundary recognition and classification program. The multiple-relaxation-time LB model and single-relaxation-time LB model are adopted to simulate flow and mass transport, respectively. The interparticle, interfacial, and intraparticle mass transfer capacities are evaluated with the permeability factor and interparticle transfer coefficient, Langmuir adsorption kinetics, and the solid diffusion model, respectively. Adsorption processes are performed in two groups of adsorbent media with different porosities and particle sizes. External and internal mass transfer resistances govern the adsorption system. A large porosity leads to an early time for adsorption equilibrium because of the controlling factor of external resistance. External and internal resistances are dominant at small and large particle sizes, respectively. Particle size, under which the total resistance is minimum, ranges from 3 to 7 μm with the preset parameters. Pore-scale simulation clearly explains the effect of both external and internal mass transfer resistances. The present paper provides both theoretical and practical guidance for the design and optimization of adsorption systems.

  4. Reversible solid oxide fuel cell for natural gas/renewable hybrid power generation systems

    NASA Astrophysics Data System (ADS)

    Luo, Yu; Shi, Yixiang; Zheng, Yi; Cai, Ningsheng

    2017-02-01

    Renewable energy (RE) is expected to be the major part of the future energy. Presently, the intermittence and fluctuation of RE lead to the limitation of its penetration. Reversible solid oxide fuel cell (RSOFC) as the energy storage device can effectively store the renewable energy and build a bidirectional connection with natural gas (NG). In this paper, the energy storage strategy was designed to improve the RE penetration and dynamic operation stability in a distributed system coupling wind generators, internal combustion engine, RSOFC and lithium-ion batteries. By compromising the relative deviation of power supply and demand, RE penetration, system efficiency and capacity requirement, the strategy that no more than 36% of the maximum wind power output is directly supplied to users and the other is stored by the combination of battery and reversible solid oxide fuel cell is optimal for the distributed system. In the case, the RE penetration reached 56.9% and the system efficiency reached 55.2%. The maximum relative deviation of power supply and demand is also lower than 4%, which is significantly superior to that in the wind curtailment case.

  5. Lattice Boltzmann simulation of gas-solid adsorption processes at pore scale level

    NASA Astrophysics Data System (ADS)

    Zhou, L.; Qu, Z. G.; Chen, L.; Tao, W. Q.

    2015-11-01

    A two-dimensional lattice Boltzmann (LB) approach was established to implement kinetic concentration boundary conditions in interfacial mass-transfer processes and to simulate the adsorption process in porous media at pore scale and mesoscopic levels. A general treatment was applied to conduct three types of concentration boundary conditions effectively and accurately. Applicability for adsorption was verified by two benchmark examples, which were representative of the interparticle mass transport and intraparticle mass transport in the adsorption system, respectively. The gas-solid adsorption process in reconstructed porous media at the pore scale level was numerically investigated. Mass-transfer processes of the adsorption reaction were simulated by executing Langmuir adsorption kinetics on surfaces of adsorbent particles. Meanwhile, the homogeneous solid diffusion model (HSDM) was used for mass transport in interior particles. The transient adsorbed amount was obtained in detail, and the impact of flow condition, porosity, and adsorbent particle size on the entire dynamic adsorption performance was investigated. The time needed to approach steady state decreased with increased fluid velocity. Transient adsorption capability and time consumption to equilibrium were nearly independent of porosity, whereas increasing pore size led to a moderating adsorption rate and more time was consumed to approach the saturation adsorption. Benefiting from the advantages of the LB method, both bulk and intraparticle mass transfer performances during adsorption can be obtained using the present pore scale approach. Thus, interparticle mass transfer and intraparticle mass transfer are the two primary segments, and intraparticle diffusion has the dominant role.

  6. The effective surface energy of heterogeneous solids measured by inverse gas chromatography at infinite dilution.

    PubMed

    Sun, Chenhang; Berg, John C

    2003-04-15

    Inverse gas chromatography (IGC) at infinite dilution has been widely used to access the nonspecific surface free energy of solid materials. Since most practical surfaces are heterogeneous, the effective surface energy given by IGC at infinite dilution is somehow averaged over the whole sample surface, but the rule of averaging has thus far not been established. To address this problem, infinite dilution IGC analysis was carried out on mixtures of known heterogeneity. These materials are obtained by mixing two types of solid particles with significantly different surface energies as characterized individually with IGC, and results are obtained for binary combinations in varying proportions. It is found that when all surface components have the same accessibility by probe molecules, the effective surface energy of such a heterogeneous surface is related to the surface energy distribution by a square root linear relationship, square root sigma(eff)(LW)= summation operator (i)phi(i) square root sigma(i)(LW), where sigma(i)(LW) refers to the nonspecific (Lifshitz-van der Waals) surface energy of patches i, and phi(i) to their area fraction.

  7. Origin of melting point depression for rare gas solids confined in carbon pores

    NASA Astrophysics Data System (ADS)

    Morishige, Kunimitsu; Kataoka, Takaaki

    2015-07-01

    To obtain insights into the mechanism of the melting-point depression of rare gas solids confined in crystalline carbon pores, we examined the freezing and melting behavior of Xe and Ar confined to the crystalline pores of ordered mesoporous carbons as well as compressed exfoliated graphite compared to the amorphous pores of ordered mesoporous silicas, by means of X-ray diffraction. For the Xe and Ar confined to the crystalline carbon pores, there was no appreciable thermal hysteresis between freezing and melting. Furthermore, the position of the main diffraction peak did not change appreciably on freezing and melting. This strongly suggests that the liquids confined in the carbon pores form a multilayered structure parallel to the smooth walls. For the Xe and Ar confined to the amorphous silica pores, on the other hand, the position of the main diffraction peak shifted into higher scattering angle on freezing suggested that the density of the confined solid is distinctly larger than for the confined liquid. Using compressed exfoliated graphite with carbon walls of higher crystallinity, we observed that three-dimensional (3D) microcrystals of Xe confined in the slit-shaped pores melted to leave the unmelted bilayers on the pore walls below the bulk triple point. The lattice spacing of the 3D microcrystals confined is larger by ˜0.7% than that of the bilayer next to the pore walls in the vicinity of the melting point.

  8. Determination of amphetamines in human urine by headspace solid-phase microextraction and gas chromatography.

    PubMed

    Raikos, Nikolaos; Christopoulou, Klio; Theodoridis, Georgios; Tsoukali, Heleni; Psaroulis, Dimitrios

    2003-06-05

    Solid-phase microextraction (SPME) is under investigation for its usefulness in the determination of a widening variety of volatile and semivolatile analytes in biological fluids and materials. Semivolatiles are increasingly under study as analytical targets, and difficulties with small partition coefficients and long equilibration times have been identified. Amphetamines were selected as semivolatiles exhibiting these limitations and methods to optimize their determination were investigated. A 100- micro m polydimethylsiloxane (PDMS)-coated SPME fiber was used for the extraction of the amphetamines from human urine. Amphetamine determination was made using gas chromatography (GC) with flame-ionization detection (FID). Temperature, time and salt saturation were optimized to obtain consistent extraction. A simple procedure for the analysis of amphetamine (AMP) and methamphetamine (MA) in urine was developed and another for 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxy-N-methamphetamine (MDMA) and 3,4-methylenedioxy-N-ethylamphetamine (MDEA) using headspace solid-phase microextraction (HS-SPME) and GC-FID. Higher recoveries were obtained for amphetamine (19.5-47%) and methamphetamine (20-38.1%) than MDA (5.1-6.6%), MDMA (7-9.6%) and MDEA (5.4-9.6%).

  9. Ozone uptake and formation of reactive oxygen intermediates on glassy, semi-solid and liquid organic matter

    NASA Astrophysics Data System (ADS)

    Berkemeier, Thomas; Steimer, Sarah S.; Krieger, Ulrich K.; Peter, Thomas; Pöschl, Ulrich; Ammann, Markus; Shiraiwa, Manabu

    2016-04-01

    Heterogeneous and multiphase reactions of ozone are important pathways for chemical ageing of atmospheric organic aerosols (Abbatt, Lee and Thornton, 2012). The effects of particle phase state on the reaction kinetics are still not fully elucidated and cannot be described by classical models assuming a homogeneous condensed phase (Berkemeier et al., 2013). We apply a kinetic multi-layer model, explicitly resolving gas adsorption, condensed phase diffusion and condensed phase chemistry (Shiraiwa et al., 2010), to systematic measurements of ozone uptake onto proxies for secondary organic aerosols (SOA). Our findings show how moisture-induced phase changes affect the gas uptake and chemical transformation of organic matter through change in the physicochemical properties of the substrate: the diffusion coefficients are found to be low under dry conditions, but increase by several orders of magnitude toward higher relative humidity (RH). The solubility of ozone in the dry organic matrix is found to be one order of magnitude higher than in the dilute aqueous solution. The model simulations reveal that at high RH, ozone uptake is mainly controlled by reaction throughout the particle bulk, whereas at low RH, bulk diffusion is retarded severely and reaction at the surface becomes the dominant pathway, with ozone uptake being limited by replenishment of unreacted organic molecules from the bulk phase. The experimental results can only be reconciled including a pathway for ozone self-reaction, which becomes especially important under dry and polluted conditions. Ozone self-reaction can be interpreted as formation and recombination of long-lived reactive oxygen intermediates at the aerosol surface, which could also explain several kinetic parameters and has implications for the health effects of organic aerosol particles. This study hence outlines how kinetic modelling can be used to gain mechanistic insight into the coupling of mass transport, phase changes, and chemical

  10. Experimental investigation of 1 kW solid oxide fuel cell system with a natural gas reformer and an exhaust gas burner

    NASA Astrophysics Data System (ADS)

    Yen, Tzu-Hsiang; Hong, Wen-Tang; Huang, Wei-Ping; Tsai, Yu-Ching; Wang, Hung-Yu; Huang, Cheng-Nan; Lee, Chien-Hsiung

    An experimental investigation is performed to establish the optimal operating conditions of a porous media after-burner integrated with a 1 kW solid oxide fuel cell (SOFC) system fed by a natural gas reformer. The compositions of the anode off-gas and cathode off-gas emitted by the SOFC when operating with fuel utilizations in the range 0-0.6 are predicted using commercial GCTool software. The numerical results are then used to set the compositions of the anode off-gas and cathode off-gas in a series of experiments designed to clarify the effects of the fuel utilization, cathode off-gas temperature and excess air ratio on the temperature distribution within the after-burner. The experimental results show that the optimal after-burner operation is obtained when using an anode off-gas temperature of 650 °C, a cathode off-gas temperature of 390 °C, a flame barrier temperature of 700 °C, an excess air ratio of 2 and a fuel utilization of U f = 0.6. It is shown that under these conditions, the after-burner can operate in a long-term, continuous fashion without the need for either cooling air or any additional fuel other than that provided by the anode off-gas.

  11. Evidence of the self-heating effect on surface reactivity and gas sensing of metal oxide nanowire chemiresistors.

    PubMed

    Strelcov, Evgheni; Dmitriev, Serghei; Button, Bradley; Cothren, Joshua; Sysoev, Victor; Kolmakov, Andrei

    2008-09-03

    The effect of Joule self-heating of the semiconducting metal oxide nanowire (here (and below unless specified), due to the generality of the effect, we use the term 'nanowire' without specification as to whether the nanobelt or other class of quasi-1D nanostructure is considered) conductometric gas sensor on its surface reactivity and kinetics is demonstrated. Due to small thermal capacitance and hampered thermal losses from the nanowire to its surroundings, the sensor was able to operate without a heater, consuming only a few microwatts of power. These results demonstrate the importance of the self-heating effect in nanowire electronics and its potential use in chemical and bio-sensing, where the ultra-small size of the active element and minimal power consumption are crucial.

  12. Reactive-template fabrication of porous SnO2 nanotubes and their remarkable gas-sensing performance.

    PubMed

    Zhang, Jun; Guo, Jing; Xu, Hongyan; Cao, Bingqiang

    2013-08-28

    A facile reactive-template strategy has been developed to fabricate porous SnO2 nanotubes using MnO2 nanorods as the sacrificial template. The formation of nanotubes is based on the redox reaction mechanism, which requires no post-treatment of the MnO2 templates. The morphological and structural characteristics of the samples have been systematically characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal-gravimetric (TG), and N2 adsorption-desorption techniques. A gas-sensor device was constructed using as-prepared SnO2 nanotubes and was tested for its ability to detect ethanol and some other compounds. Because of the porous structure and relative large specific surface area, the SnO2 nanotube sensor manifests remarkably improved sensing performance, including fast response recovery, high sensitivity, and excellent repeatability, suggesting the promising application of the SnO2 nanotube materials.

  13. Synthesis, structural and conformational properties, and gas phase reactivity of 1,4-dihydropyridine ester and ketone derivatives.

    PubMed

    Giorgi, Gianluca; Adamo, Mauro F A; Ponticelli, Fabio; Ventura, Antonio

    2010-12-07

    A new series of 4-aryl-2,6-dimethyl-1,4-dihydropyridines, characterized by ester or ketone functions at positions 3 and 5, has been synthesized. Structural and conformational properties, concerning the dihydropyridine ring and the orientation (synplanar/antiperiplanar) of the substituents have been investigated in their crystal structure and in solution by nuclear magnetic resonance. Evaluation of intermolecular and hydrogen bonding interactions as well as packing features, have been also carried out, evidencing interesting packing motifs. Their gas phase reactivity, as protonated and deprotonated molecules, has been investigated by electrospray ionization, high resolution and collision-induced dissociation multiple stage mass spectrometry. Deydrogenation reactions have been observed as a function of the capillary voltage.

  14. Well-to-Wheels Analysis of Compressed Natural Gas and Ethanol from Municipal Solid Waste

    SciTech Connect

    Lee, Uisung; Han, Jeongwoo; Wang, Michael

    2016-10-01

    The amount of municipal solid waste (MSW) generated in the United States was estimated at 254 million wet tons in 2013, and around half of that generated waste was landfilled. There is a huge potential in recovering energy from that waste, since around 60% of landfilled material is biomass-derived waste that has high energy content. In addition, diverting waste for fuel production avoids huge fugitive emissions from landfills, especially uncontrolled CH4 emissions, which are the third largest anthropogenic CH4 source in the United States. Lifecycle analysis (LCA) is typically used to evaluate the environmental impact of alternative fuel production pathways. LCA of transportation fuels is called well-to-wheels (WTW) and covers all stages of the fuel production pathways, from feedstock recovery (well) to vehicle operation (wheels). In this study, the Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation (GREET®) model developed by Argonne National Laboratory is used to evaluate WTW greenhouse gas (GHG) emissions and fossil fuel consumption of waste-derived fuels. Two waste-to-energy (WTE) pathways have been evaluated – one for compressed natural gas (CNG) production using food waste via anaerobic digestion, and the other for ethanol production from yard trimmings via fermentation processes. Because the fuel production pathways displace current waste management practices (i.e., landfilling waste), we use a marginal approach that considers only the differences in emissions between the counterfactual case and the alternative fuel production case.

  15. Nickel oxide nanowires: vapor liquid solid synthesis and integration into a gas sensing device

    NASA Astrophysics Data System (ADS)

    Kaur, N.; Comini, E.; Zappa, D.; Poli, N.; Sberveglieri, G.

    2016-05-01

    In the field of advanced sensor technology, metal oxide nanostructures are promising materials due to their high charge carrier mobility, easy fabrication and excellent stability. Among all the metal oxide semiconductors, nickel oxide (NiO) is a p-type semiconductor with a wide band gap and excellent optical, electrical and magnetic properties, which has not been much investigated. Herein, we report the growth of NiO nanowires by using the vapor liquid solid (VLS) technique for gas sensing applications. Platinum, palladium and gold have been used as a catalyst for the growth of NiO nanowires. The surface morphology of the nanowires was investigated through scanning electron microscopy to find out which catalyst and growth conditions are best for the growth of nanowires. GI-XRD and Raman spectroscopies were used to confirm the crystalline structure of the material. Different batches of sensors have been prepared, and their sensing performances towards different gas species such as carbon monoxide, ethanol, acetone and hydrogen have been explored. NiO nanowire sensors show interesting and promising performances towards hydrogen.

  16. Lattice model theory of the equation of state covering the gas, liquid, and solid phases

    NASA Technical Reports Server (NTRS)

    Bonavito, N. L.; Tanaka, T.; Chan, E. M.; Horiguchi, T.; Foreman, J. C.

    1975-01-01

    The three stable states of matter and the corresponding phase transitions were obtained with a single model. Patterned after Lennard-Jones and Devonshires's theory, a simple cubic lattice model containing two fcc sublattices (alpha and beta) is adopted. The interatomic potential is taken to be the Lennard-Jones (6-12) potential. Employing the cluster variation method, the Weiss and the pair approximations on the lattice gas failed to give the correct phase diagrams. Hybrid approximations were devised to describe the lattice term in the free energy. A lattice vibration term corresponding to a free volume correction is included semi-phenomenologically. The combinations of the lattice part and the free volume part yield the three states and the proper phase diagrams. To determine the coexistence regions, the equalities of the pressure and Gibbs free energy per molecule of the coexisting phases were utilized. The ordered branch of the free energy gives rise to the solid phase while the disordered branch yields the gas and liquid phases. It is observed that the triple point and the critical point quantities, the phase diagrams and the coexistence regions plotted are in good agreement with the experimental values and graphs for argon.

  17. Kinetics of thermochemical gas-solid reactions important in the Venus sulfur cycle

    NASA Technical Reports Server (NTRS)

    Fegley, Bruce, Jr.

    1988-01-01

    The thermochemical net reaction CaCO3 + SO2 yields CaSO4 + CO is predicted to be an important sink for incorporation of SO2 into the Venus crust. The reaction rate law was established to understand the dependence of rate on experimental variables such as temperature and partial pressure of SO2, CO2, and O2. The experimental approach was a variant of the thermogravimetric method often employed to study the kinetics of thermochemical gas-solid reactions. Clear calcite crystals were heated at constant temperature in SO2-bearing gas streams for varying time periods. Reaction rate was determined by three independent methods. A weighted linear least squares fit to all rate data yielded a rate equation. Based on the Venera 13, 14 and Vega 2 observations of CaO content of the Venus atmosphere, SO2 at the calculated rate would be removed from the Venus atmosphere in about 1,900,00 years. The most plausible endogenic source of the sulfur needed to replenish atmospheric SO2 is volcanism. The annual amount of erupted material needed for the replenishment depends on sulfur content; three ratios are used to calculate rates ranging from 0.4 to 11 cu km/year. This geochemically derived volcanism rate can be used to test if geophysically derived rates are correct. The work also suggests that Venus is less volcanically active than the Earth.

  18. Solid Oxide Fuel Cell/Gas Turbine Hybrid Cycle Technology for Auxiliary Aerospace Power

    NASA Technical Reports Server (NTRS)

    Steffen, Christopher J., Jr.; Freeh, Joshua E.; Larosiliere, Louis M.

    2005-01-01

    A notional 440 kW auxiliary power unit has been developed for 300 passenger commercial transport aircraft in 2015AD. A hybrid engine using solid-oxide fuel cell stacks and a gas turbine bottoming cycle has been considered. Steady-state performance analysis during cruise operation has been presented. Trades between performance efficiency and system mass were conducted with system specific energy as the discriminator. Fuel cell performance was examined with an area specific resistance. The ratio of fuel cell versus turbine power was explored through variable fuel utilization. Area specific resistance, fuel utilization, and mission length had interacting effects upon system specific energy. During cruise operation, the simple cycle fuel cell/gas turbine hybrid was not able to outperform current turbine-driven generators for system specific energy, despite a significant improvement in system efficiency. This was due in part to the increased mass of the hybrid engine, and the increased water flow required for on-board fuel reformation. Two planar, anode-supported cell design concepts were considered. Designs that seek to minimize the metallic interconnect layer mass were seen to have a large effect upon the system mass estimates.

  19. Oxysterols in cosmetics-Determination by planar solid phase extraction and gas chromatography-mass spectrometry.

    PubMed

    Schrack, S; Hohl, C; Schwack, W

    2016-11-18

    Sterol oxidation products (SOPs) are linked to several toxicological effects. Therefore, investigation of potential dietary uptake sources particularly food of animal origin has been a key issue for these compounds. For the simultaneous determination of oxysterols from cholesterol, phytosterols, dihydrolanosterol and lanosterol in complex cosmetic matrices, planar solid phase extraction (pSPE) was applied as clean-up tool. SOPs were first separated from more non-polar and polar matrix constituents by normal phase thin-layer chromatography and then focussed into one target zone. Zone extraction was performed with the TLC-MS interface, followed by gas chromatography-mass spectrometry analysis. pSPE showed to be effective for cleaning up cosmetic samples as sample extracts were free of interferences, and gas chromatographic columns did not show any signs of overloading. Recoveries were between 86 and 113% with relative standard deviations of below 10% (n=6). Results of our market survey in 2016 showed that some cosmetics with ingredients of plant origin contained phytosterol oxidation products (POPs) in the low ppm range and therefore in line with levels reported for food. In lanolin containing products, total SOPs levels (cholesterol oxidation products (COPs), lanosterol oxidation products (LOPs), dihydrolanosterol oxidation products (DOPs)) being in the low percent range exceeded reported levels for food by several orders of magnitudes.

  20. Venus volcanism: Rate estimates from laboratory studies of sulfur gas-solid reactions

    NASA Technical Reports Server (NTRS)

    Ehlers, K.; Fegley, B., Jr.; Prinn, R. G.

    1989-01-01

    Thermochemical reactions between sulfur-bearing gases in the atmosphere of Venus and calcium-, iron-, magnesium-, and sulfur-bearing minerals on the surface of Venus are an integral part of a hypothesized cycle of thermochemical and photochemical reactions responsible for the maintenance of the global sulfuric acid cloud cover on Venus. SO2 is continually removed from the Venus atmosphere by reaction with calcium bearing minerals on the planet's surface. The rate of volcanism required to balance SO2 depletion by reactions with calcium bearing minerals on the Venus surface can therefore be deduced from a knowledge of the relevant gas-solid reaction rates combined with reasonable assumptions about the sulfur content of the erupted material (gas + magma). A laboratory program was carried out to measure the rates of reaction between SO2 and possible crustal minerals on Venus. The reaction of CaCO3(calcite) + SO2 yields CaSO4 (anhydrite) + CO was studied. Brief results are given.

  1. The impact of municipal solid waste management on greenhouse gas emissions in the United States.

    PubMed

    Weitz, Keith A; Thorneloe, Susan A; Nishtala, Subba R; Yarkosky, Sherry; Zannes, Maria

    2002-09-01

    Technological advancements, environmental regulations, and emphasis on resource conservation and recovery have greatly reduced the environmental impacts of municipal solid waste (MSW) management, including emissions of greenhouse gases (GHGs). This study was conducted using a life-cycle methodology to track changes in GHG emissions during the past 25 years from the management of MSW in the United States. For the baseline year of 1974, MSW management consisted of limited recycling, combustion without energy recovery, and landfilling without gas collection or control. This was compared with data for 1980, 1990, and 1997, accounting for changes in MSW quantity, composition, management practices, and technology. Over time, the United States has moved toward increased recycling, composting, combustion (with energy recovery) and landfilling with gas recovery, control, and utilization. These changes were accounted for with historical data on MSW composition, quantities, management practices, and technological changes. Included in the analysis were the benefits of materials recycling and energy recovery to the extent that these displace virgin raw materials and fossil fuel electricity production, respectively. Carbon sinks associated with MSW management also were addressed. The results indicate that the MSW management actions taken by U.S. communities have significantly reduced potential GHG emissions despite an almost 2-fold increase in waste generation. GHG emissions from MSW management were estimated to be 36 million metric tons carbon equivalents (MMTCE) in 1974 and 8 MMTCE in 1997. If MSW were being managed today as it was in 1974, GHG emissions would be approximately 60 MMTCE.

  2. Structural Analysis of Perfluoropropanoyl Fluoride in the Gas, Liquid, and Solid Phases.

    PubMed

    Berrueta Martínez, Yanina; Reuter, Christian G; Vishnevskiy, Yury V; Bava, Yanina B; Picone, A Lorena; Romano, Rosana M; Stammler, Hans-Georg; Neumann, Beate; Mitzel, Norbert W; Della Védova, Carlos O

    2016-04-21

    The coexistence of two conformers in perfluoropropanoyl fluoride, CF3CF2C(O)F, differing in the CC-CF dihedral angle (gauche 85(10)% and anti 15(10)%), has been determined by means of gas-phase electron diffraction (GED). Quantum-chemical calculations performed at the MP2 and B3LYP approximations and cc-pVTZ basis sets reproduce the experimental values with confidence. By contrast, FTIR spectra give no clear evidence for the anti-conformer in the gas phase. Information on this less abundant but stable rotamer is obtained from matrix-isolation/FTIR spectroscopy and liquid Raman spectroscopy. In situ crystallization and single-crystal X-ray diffraction (XRD) data reveal the presence of solely the gauche-conformation in the solid state. A set of intermolecular interactions including C═O···C═O, C-F···F-C, and F···C═O is detected. The nature of bonding and the relative stabilities of gauche- and anti-conformers are explored using natural bond orbitals.

  3. Estimates of solid waste disposal rates and reduction targets for landfill gas emissions

    NASA Astrophysics Data System (ADS)

    Powell, Jon T.; Townsend, Timothy G.; Zimmerman, Julie B.

    2016-02-01

    Landfill disposal of municipal solid waste represents one of the largest anthropogenic global methane emission sources, and recent policy approaches have targeted significant reductions of these emissions to combat climate change in the US (ref. ). The efficacy of active gas collection systems in the US was examined by analysing performance data, including fire occurrence, from more than 850 landfills. A generalized linear model showed that the operating status of a landfill--open and actively receiving waste or closed--was the most significant predictor of collection system performance. Gas collection systems at closed landfills were statistically significantly more efficient (p < 0.001) and on average 17 percentage points more efficient than those at open landfills, but open landfills were found to represent 91% of all landfill methane emissions. These results demonstrate the clear need to target open landfills to achieve significant near-term methane emission reductions. This observation is underscored by landfill disposal rates in the US significantly exceeding previously reported national estimates, with this study reporting 262 million tonnes in the year 2012 compared with 122 million tonnes in 2012 as estimated by the US Environmental Protection Agency.

  4. Benefits of improved municipal solid waste management on greenhouse gas reduction in Luangprabang, Laos.

    PubMed

    Vilaysouk, Xaysackda; Babel, Sandhya

    2017-03-16

    Climate change is a consequence of greenhouse gas emissions. Greenhouse gas (GHG) emissions from the waste sector contribute to 3% of total anthropogenic emissions. In this study, applicable solutions for municipal solid waste (MSW) management in Luangprabang (LPB) and Laos were examined. Material flow analysis of MSW was performed to estimate the amount of MSW generated in 2015. Approximately 29,419 tonnes of MSW is estimated for 2015. Unmanaged landfilling was the main disposal method, while MSW open burning was also practiced to some extent. The International Panel on Climate Change 2006 model and the Atmospheric Brown Clouds Emission Inventory Manual were used to estimate GHG emissions from existing MSW management, and total emissions are 33,889 tonnes/year carbon dioxide-equivalents (CO2-eq). Three scenarios were developed in order to reduce GHG emissions and environmental problems. Improvement of the MSW management by expanding MSW collection services, introducing composting and recycling, and avoiding open burning, can be considered as solutions to overcome the problems for LPB. The lowest GHG emissions are achieved in the scenario where composting and recycling are proposed, with the total GHG emissions reduction by 18,264 tonnes/year CO2-eq.

  5. The Case for Natural Gas Fueled Solid Oxide Fuel Cell Power Systems for Distributed Generation

    SciTech Connect

    Chick, Lawrence A.; Weimar, Mark R.; Whyatt, Greg A.; Powell, Michael R.

    2015-02-01

    Natural-gas-fueled solid oxide fuel cell (NGSOFC) power systems yield electrical conversion efficiencies exceeding 60% and may become a viable alternative for distributed generation (DG) if stack life and manufacturing economies of scale can be realized. Currently, stacks last approximately 2 years and few systems are produced each year because of the relatively high cost of electricity from the systems. If mass manufacturing (10,000 units per year) and a stack life of 15 years can be reached, the cost of electricity from an NGSOFC system is estimated to be about 7.7 ¢/kWh, well within the price of commercial and residential retail prices at the national level (9.9-10¢/kWh and 11-12 ¢/kWh, respectively). With an additional 5 ¢/kWh in estimated additional benefits from DG, NGSOFC could be well positioned to replace the forecasted 59-77 gigawatts of capacity loss resulting from coal plant closures due to stricter emissions regulations and low natural gas prices.

  6. A one-dimensional model for gas-solid heat transfer in pneumatic conveying

    NASA Astrophysics Data System (ADS)

    Smajstrla, Kody Wayne

    A one-dimensional ODE model reduced from a two-fluid model of a higher dimensional order is developed to study dilute, two-phase (air and solid particles) flows with heat transfer in a horizontal pneumatic conveying pipe. Instead of using constant air properties (e.g., density, viscosity, thermal conductivity) evaluated at the initial flow temperature and pressure, this model uses an iteration approach to couple the air properties with flow pressure and temperature. Multiple studies comparing the use of constant or variable air density, viscosity, and thermal conductivity are conducted to study the impact of the changing properties to system performance. The results show that the fully constant property calculation will overestimate the results of the fully variable calculation by 11.4%, while the constant density with variable viscosity and thermal conductivity calculation resulted in an 8.7% overestimation, the constant viscosity with variable density and thermal conductivity overestimated by 2.7%, and the constant thermal conductivity with variable density and viscosity calculation resulted in a 1.2% underestimation. These results demonstrate that gas properties varying with gas temperature can have a significant impact on a conveying system and that the varying density accounts for the majority of that impact. The accuracy of the model is also validated by comparing the simulation results to the experimental values found in the literature.

  7. Simultaneous removal of SO{sub 2} and NO from flue gas using 'oxygen-enriched' highly reactive absorbent

    SciTech Connect

    Zhao, Y.; Sun, X.J.; Fang, H.; Liu, F.

    2007-04-15

    Fly ash, industry-grade lime, and an additive, MnO{sub 2} (M), were used to prepare an 'oxygen-enriched' highly reactive absorbent. Experiments of simultaneous desulfurization and denitrification were carried in a flue gas circulating fluidized bed (CFB). The effects of influencing factors were also investigated on the removal efficiencies of desulfurization and denitrification. Removal efficiencies of 95.5% for SO{sub 2} and 64.8% for NO were obtained respectively under the optimal experimental conditions. The component of the spent absorbent was analyzed with chemical analysis methods. The results indicated that more nitrogen species appeared in the spent absorbent except sulfur species. A scanning electron microscope (SEM) and an accessory X-ray energy spectrometer (EDS) were used to observe microproperties of the samples, including fly ash, oxidizing highly reactive absorbent, and spent absorbent. The simultaneous removal mechanism of SO{sub 2} and NO based on this absorbent was proposed according to the experimental results.

  8. Gas-Phase Reactions of Doubly Charged Lanthanide Cations with Alkanes and Alkenes. Trends in Metal(2+) Reactivity

    SciTech Connect

    Gibson, John K.; Marcalo, Joaquim; Santos, Marta; Pires de Matos, Antonio; Haire, Richard G.

    2008-12-08

    The gas-phase reactivity of doubly-charged lanthanide cations, Ln2+ (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu), with alkanes (methane, ethane, propane, n-butane) and alkenes (ethene, propene, 1-butene) was studied by Fourier transform ion cyclotron resonance mass spectrometry. The reaction products consisted of different combinations of doubly-charged organometallic ions?adducts or species formed via metal-ion-induced hydrogen, dihydrogen, alkyl, or alkane eliminations from the hydrocarbons?and singly-charged ions that resulted from electron, hydride, or methide transfers from the hydrocarbons to the metal ions. The only lanthanide cations capable of activating the hydrocarbons to form doubly-charged organometallic ions were La2+, Ce2+, Gd2+, and Tb2+, which have ground-state or low-lying d1 electronic configurations. Lu2+, with an accessible d1 electronic configuration but a rather high electron affinity, reacted only through transfer channels. The remaining Ln2+ reacted via transfer channels or adduct formation. The different accessibilities of d1 electronic configurations and the range of electron affinities of the Ln2+ cations allowed for a detailed analysis of the trends for metal(2+) reactivity and the conditions for occurrence of bond activation, adduct formation, and electron, hydride, and methide transfers.

  9. Partition and size distribution of heavy metals in the flue gas from municipal solid waste incinerators in Taiwan.

    PubMed

    Yuan, Chung-Shin; Lin, Hsun-Yu; Wu, Chun-Hsin; Liu, Ming-Han

    2005-03-01

    This study investigates the partition of heavy metals in both solid and gas phases in the flue gas from municipal solid waste (MSW) incinerators. Six MSW incinerators in Taiwan were examined and heavy metals in the flue gas at the inlets and outlets of air pollution control devices (APCDs) were analyzed. Heavy metals including Hg, Pb, Cd, Zn, Cu and Cr were sampled by USEPA Method 29 and further analyzed using inductively coupled plasma-mass spectroscopy (ICP-MS) and cold vapor atomic absorption spectrometry (CVAAS). Experimental results revealed that the removal efficiencies of the APCDs for the heavy metals Pb, Cd, Zn, Cu and Cr greatly exceeded 90%, but that of Hg did not. Two groups of heavy metals upstream of APCDs were observed. Pb, Cd, Zn, Cu and Cr were present mainly in the solid phase with a solid to gas ratio (S/G) of over 12.3. However, in most cases, mercury appeared mainly in the gas phase with an S/G ratio from 0.15 to 1.04, because it has a low boiling point. Additionally, treatment with the APCDs increased the S/G ratio of mercury because gaseous mercury could be removed by injecting powdered activated carbon (PAC) into the flue gas. Moreover, the distribution of particle sizes in the solid phase was bimodal. Finer particles (d(p)2.5 microm) contained more Cr and Hg.

  10. Gas-phase reactivity of carboxylic acid functional groups with carbodiimides.

    PubMed

    Prentice, Boone M; Gilbert, Joshua D; Stutzman, John R; Forrest, William P; McLuckey, Scott A

    2013-01-01

    Gas-phase modification of carboxylic acid functionalities is performed via ion/ion reactions with carbodiimide reagents [N-cyclohexyl-N'-(2-morpholinoethyl)carbodiimide (CMC) and [3-(3-Ethylcarbodiimide-1-yl)propyl]trimethylaminium (ECPT)]. Gas-phase ion/ion covalent chemistry requires the formation of a long-lived complex. In this instance, the complex is stabilized by an electrostatic interaction between the fixed charge quaternary ammonium group of the carbodiimide reagent cation and the analyte dianion. Subsequent activation results in characteristic loss of an isocyanate derivative from one side of the carbodiimide functionality, a signature for this covalent chemistry. The resulting amide bond is formed on the analyte at the site of the original carboxylic acid. Reactions involving analytes that do not contain available carboxylic acid groups (e.g., they have been converted to sodium salts) or reagents that do not have the carbodiimide functionality do not undergo a covalent reaction. This chemistry is demonstrated using PAMAM generation 0.5 dendrimer, ethylenediaminetetraacetic acid (EDTA), and the model peptide DGAILDGAILD. This work demonstrates the selective gas-phase covalent modification of carboxylic acid functionalities.

  11. A conservative multi-group approach to the Boltzmann equations for reactive gas mixtures

    NASA Astrophysics Data System (ADS)

    Bisi, M.; Rossani, A.; Spiga, G.

    2015-11-01

    Starting from a simple kinetic model for a quaternary mixture of gases undergoing a bimolecular chemical reaction, multi-group integro-differential equations are derived for the particle distribution functions of all species. The procedure takes advantage of a suitable probabilistic formulation, based on the underlying collision frequencies and transition probabilities, of the relevant reactive kinetic equations of Boltzmann type. Owing to an appropriate choice of a sufficiently large number of weight functions, it is shown that the proposed multi-group equations are able to fulfil exactly, at any order of approximation, the correct conservation laws that must be inherited from the original kinetic equations, where speed was a continuous variable. Future developments are also discussed.

  12. Gas-solid carbonation as a current alternative origin for carbonates in Martian regolith

    NASA Astrophysics Data System (ADS)

    Garenne, A.; Montes-Hernandez, G.; Beck, P.; Schmitt, B.; Brissaud, O.

    2011-12-01

    Carbonates are abundant sedimentary minerals at the surface and sub-surface of Earth and they have been proposed as tracers of liquid water in extraterrestrial environments (e.g. at Mars surface). Its formation mechanism is since generally associated with aqueous alteration processes. Recently, carbonates minerals have been discovered on Mars surface by different orbital or rovers missions. In particular, the phoenix mission has measured from 1 to 5% of calcium carbonate (calcite type). These occurrences have been reported in area were the relative humidity is significantly high (Boynton et al., 2009). The small concentration of carbonates suggests an alternative process than carbonation in aqueous conditions. Such an observation might rather point toward a possible formation mechanism by dust-gas reaction under current Martian conditions. For this reason, in the present study, we designed an experimental setup consisting of an infrared microscope coupled to a cryogenic reaction cell (IR-CryoCell setup) in order to investigate the gas-solid carbonation of three different mineral precursors for carbonates (Ca and Mg hydroxides, and a hydrated Ca silicate formed from Ca2SiO4) at low temperature (from -10 to 25°C) and at reduced CO2 pressure (from 100 to 1000 mbar). These mineral materials are crucial precursors to form respective Ca and Mg carbonates in humid environments (0 < relative humidity < 100%) at dust-CO2 or dust-water ice-CO2 interfaces. The results have revealed a significant and fast carbonation process for Ca hydroxide and hydrated Ca silicate. Conversely, slight carbonation process was observed for Mg hydroxide. These results suggest that gas-solid carbonation process or carbonate formation at the dust-water ice-CO2 interfaces could be a currently active Mars surface process. We note that the carbonation process at low temperature (<0°C) described in the present study could also have important implications on the dust-water ice-CO2 interactions in

  13. A new model for two-dimensional numerical simulation of pseudo-2D gas-solids fluidized beds

    SciTech Connect

    Li, Tingwen; Zhang, Yongmin

    2013-10-11

    Pseudo-two dimensional (pseudo-2D) fluidized beds, for which the thickness of the system is much smaller than the other two dimensions, is widely used to perform fundamental studies on bubble behavior, solids mixing, or clustering phenomenon in different gas-solids fluidization systems. The abundant data from such experimental systems are very useful for numerical model development and validation. However, it has been reported that two-dimensional (2D) computational fluid dynamic (CFD) simulations of pseudo-2D gas-solids fluidized beds usually predict poor quantitative agreement with the experimental data, especially for the solids velocity field. In this paper, a new model is proposed to improve the 2D numerical simulations of pseudo-2D gas-solids fluidized beds by properly accounting for the frictional effect of the front and back walls. Two previously reported pseudo-2D experimental systems were simulated with this model. Compared to the traditional 2D simulations, significant improvements in the numerical predictions have been observed and the predicted results are in better agreement with the available experimental data.

  14. Metal etching with reactive gas cluster ion beams using pickup cell

    SciTech Connect

    Toyoda, Noriaki; Yamada, Isao

    2012-11-06

    Mixed gas cluster ion beams were formed using pickup cell for metal etching. O{sub 2} neutral clusters pick up acetic acid and formed mixed cluster beam. By using O{sub 2}-GCIB with acetic acid, enhancement of Cu etching was observed. Because of dense energy deposition by GCIB, etching of Cu proceeds by CuO formation, enhancement of chemical reaction with acetic acid and desorption of etching products. Surface roughening was not observed on poly crystalline Cu because of the small dependence of etching rate on crystal orientation. Halogen free and low-temperature metal etching with GCIB using pickup cell is possible.

  15. Reactive Carbon from Life Support Wastes for Incinerator Flue Gas Cleanup

    NASA Technical Reports Server (NTRS)

    Fisher, J. W.; Pisharody, S.; Moran, M. J.; Wignarajah, K.; Shi, Y.

    2002-01-01

    This paper presents the results from a joint research initiative between NASA Ames Research Center and Lawrence Berkeley National lab. The objective of the research is to produce activated carbon from life support wastes and to use the activated carbon to adsorb and chemically reduce the NO(sub x) and SO(sub 2) contained in incinerator flue gas. Inedible biomass waste from food production is the primary waste considered for conversion to activated carbon. Results to date show adsorption of both NO(sub x) and SO(sub 2) in activated carbon made from biomass. Conversion of adsorbed NO(sub x) to nitrogen has also been observed.

  16. Reactive carbon from life support wastes for incinerator flue gas cleanup-System Testing

    SciTech Connect

    Fisher, John W.; Pisharody, Suresh; Moran, Mark J.; Wignarajah, Kanapathipillai; Xu, X.H.; Shi, Yao; Chang, Shih-Ger

    2002-05-14

    This paper presents the results from a joint research initiative between NASA Ames Research Center and Lawrence Berkeley National lab. The objective of the research is to produce activated carbon from life support wastes and to use the activated carbon to adsorb and chemically reduce the NO{sub x} and SO{sub 2} contained in incinerator flue gas. Inedible biomass waste from food production is the primary waste considered for conversion to activated carbon. Results to date show adsorption of both NO{sub x} and SO{sub 2} in activated carbon made from biomass. Conversion of adsorbed NO{sub x} to nitrogen has also been observed.

  17. Inhaled hydrogen gas therapy for prevention of noise-induced hearing loss through reducing reactive oxygen species.

    PubMed

    Kurioka, Takaomi; Matsunobu, Takeshi; Satoh, Yasushi; Niwa, Katsuki; Shiotani, Akihiro

    2014-12-01

    Reactive oxygen species (ROS) that form in the inner ear play an important role in noise-induced hearing loss (NIHL). Recent studies have revealed that molecular hydrogen (H2) has great potential for reducing ROS. In this study, we examined the potential of hydrogen gas to protect against NIHL. We tested this hypothesis in guinea pigs with 0.5%, 1.0% and 1.5% H2 inhalation in air for 5h a day after noise exposure, for five consecutive days. All animals underwent measurements for auditory brainstem response after the noise exposure; the results revealed that there was a better improvement in the threshold shift for the 1.0% and 1.5% H2-treated groups than the non-treated group. Furthermore, outer hair cell (OHC) loss was examined 7 days after noise exposure. A significantly higher survival rate of OHCs was observed in the 1.0% and 1.5% H2-treated group as compared to that of the non-treated group in the basal turn. Immunohistochemical analyses for 8-hydroxy-2'-deoxyguanosine (8-OHdG) were performed to examine the amount of oxidative DNA damage. While strong immunoreactivities against 8-OHdG were observed of the non-treated group, the H2-treated group showed decreased immunoreactivity for 8-OHdG. These findings strongly suggest that inhaled hydrogen gas protects against NIHL.

  18. A reactive transport modelling approach to assess the leaching potential of hydraulic fracturing fluids associated with coal seam gas extraction

    NASA Astrophysics Data System (ADS)

    Mallants, Dirk; Simunek, Jirka; Gerke, Kirill

    2015-04-01

    Coal Seam Gas production generates large volumes of "produced" water that may contain compounds originating from the use of hydraulic fracturing fluids. Such produced water also contains elevated concentrations of naturally occurring inorganic and organic compounds, and usually has a high salinity. Leaching of produced water from storage ponds may occur as a result of flooding or containment failure. Some produced water is used for irrigation of specific crops tolerant to elevated salt levels. These chemicals may potentially contaminate soil, shallow groundwater, and groundwater, as well as receiving surface waters. This paper presents an application of scenario modelling using the reactive transport model for variably-saturated media HP1 (coupled HYDRUS-1D and PHREEQC). We evaluate the fate of hydraulic fracturing chemicals and naturally occurring chemicals in soil as a result of unintentional release from storage ponds or when produced water from Coal Seam Gas operations is used in irrigation practices. We present a review of exposure pathways and relevant hydro-bio-geo-chemical processes, a collation of physico-chemical properties of organic/inorganic contaminants as input to a set of generic simulations of transport and attenuation in variably saturated soil profiles. We demonstrate the ability to model the coupled processes of flow and transport in soil of contaminants associated with hydraulic fracturing fluids and naturally occurring contaminants.

  19. Formation of hydrogenated amorphous carbon films by reactive high power impulse magnetron sputtering containing C2H2 gas

    NASA Astrophysics Data System (ADS)

    Kimura, Takashi; Kamata, Hikaru

    2015-09-01

    Diamond-like carbon (DLC) films have attracted interest for material industries, because they have unique properties. Hydrogenated amorphous carbon films are prepared by reactive high power impulse magnetron sputtering (HiPIMS) containing C2H2 gas and the properties of the films produced in Ar/C2H2 and Ne/C2H2 HiPIMS are compared. Production of hydrocarbon radicals and their ions strongly depends on both electron temperature and electron density in HiPIMS. Therefore, the influence of the difference in buffer gas (Ar and Ne) on the film properties is also valuable to investigate. The film preparation is performed at an average power of 60 W and a repetition frequency of 110 Hz. Total pressure ranges between 0.3 and 2 Pa. The maximum of instantaneous power is about 20-25 kW, and the magnitude of the current is 35 A. A negative pulse voltage is applied to the substrates for about 15 μs after the target voltage changed from about -500 V to 0 V. Hardness of the films prepared by Ar/C2H2 HiPIMS monotonically decreases with increasing the total pressure, whereas that of the films prepared by Ne/C2H2 HiPIMS does not strongly depend on the total pressure. This work is partially supported by JSPS KAKENHI Grant Number 26420230.

  20. Gas-Microjet Reactive Scattering: Collisions of HCl and DCl with Cool Salty Water.

    PubMed

    Faust, Jennifer A; Sobyra, Thomas B; Nathanson, Gilbert M

    2016-02-18

    Liquid microjets provide a powerful means to investigate reactions of gases with salty water in vacuum while minimizing gas-vapor collisions. We use this technique to explore the fate of gaseous HCl and DCl molecules impinging on 8 molal LiCl and LiBr solutions at 238 K. The experiments reveal that HCl or DCl evaporate infrequently if they become thermally accommodated at the surface of either solution. In particular, we observe minimal thermal desorption of HCl following HCl collisions and no distinct evidence for rapid, interfacial DCl→HCl exchange following DCl collisions. These results imply that surface thermal motions are not generally strong enough to propel momentarily trapped HCl or DCl back into the gas phase before they ionize and disappear into solution. Instead, only HCl and DCl molecules that scatter directly from the surface escape entry. These recoiling molecules transfer less energy upon collision to LiBr/H2O than to LiCl/H2O, reflecting the heavier mass of Br(-) than of Cl(-) in the interfacial region.

  1. Identification and Quantification of Pesticides in Environmental Waters With Solid Phase Microextraction and Analysis Using Field-Portable Gas Chromatography-Mass Spectrometry

    DTIC Science & Technology

    2004-06-10

    Microextraction and Analysis using Field-Portable Gas Chromatography-Mass Spectrometry Name of Candidate: CPT Michael J. Nack...in the thesis manuscript entitled: Identification and Quantification of Pesticides in Environmental Waters with Solid Phase Microextraction ...Pesticides in Environmental Waters with Solid Phase Microextraction and Analysis using Field-Portable Gas Chromatography-Mass Spectrometry

  2. Theoretical investigation on reactivity of Ag and Au atoms toward CS2 in gas phase

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Yang, Ling; Tian, An-Min; Wong, Ning-Bew

    2008-02-01

    The reaction mechanisms of Ag and Au atoms with CS2 on both doublet and quartet potential energy surfaces (PESs) have been investigated using UBPW91 and UCCSD(T) methods. The two studied reactions proceed via a similar insertion-elimination mechanism instead of a direct abstract mechanism. The reaction Ag + CS2 --> SAgCS is endothermic by about 21E0 kcal/mol. But another reaction Au + CS2 --> SAuCS is slightly exothermic by about 8.8 kcal/mol, which is different from the previous theoretical prediction. In the overall reactions, the rate-determining step is found to be the C-S bond cleavage step with a high-activation barrier of about 40 kcal/mol. The calculated vibration frequencies are in good agreement with the experiment values and show that the BPW91 method is very good for the calculation of small molecules containing Ag and Au. The reactivity of the two atoms toward CS2 is compared with those of the first-row transition-metal atoms. The present study provides a detailed picture of the C-S bond activation and cleavage in carbon disulfide mediated by second and the third row transition-metal atoms Ag and Au.

  3. Phase separation in NiCrN coatings induced by N2 addition in the gas phase: A way to generate magnetic thin films by reactive sputtering of a non-magnetic NiCr target

    NASA Astrophysics Data System (ADS)

    Luciu, I.; Duday, D.; Choquet, P.; Perigo, E. A.; Michels, A.; Wirtz, T.

    2016-12-01

    Magnetic coatings are used for a lot of applications from data storage in hard discs, spintronics and sensors. Meanwhile, magnetron sputtering is a process largely used in industry for the deposition of thin films. Unfortunately, deposition of magnetic coatings by magnetron sputtering is a difficult task due to the screening effect of the magnetic target lowering the magnetic field strength of the magnet positioned below the target, which is used to generate and trap ions in the vicinity of the target surface to be sputtered. In this work we present an efficient method to obtain soft magnetic thin films by reactive sputtering of a non-magnetic target. The aim is to recover the magnetic properties of Ni after dealloying of Ni and Cr due to the selective reactivity of Cr with the reactive nitrogen species generated during the deposition process. The effects of nitrogen content on the dealloying and DC magnetron sputtering (DCMS) deposition processes are studied here. The different chemical compositions, microstructures and magnetic properties of DCMS thin films obtained by sputtering in reactive gas mixtures with different ratios of Ar/N2 from a non-magnetic Ni-20Cr target have been determined. XPS data indicate that the increase of nitrogen content in the films has a strong influence on the NiCr phase decomposition into Ni and CrN, leading to ferromagnetic coatings due to the Ni phase. XRD results show that the obtained Ni-CrN films consist of a metallic fcc cubic Ni phase mixed with fcc cubic CrN. The lattice parameter decreases with the N2 content and reaches the theoretical value of the pure fcc-Ni, when Cr is mostly removed from the Ni-Cr phase. Dealloying of Cr from a Ni80-Cr20 solid solution is achieved in our experimental conditions and the deposition of Ni ferromagnetic coatings embedding CrN from a non-magnetic target is possible with reactive DC magnetron sputtering.

  4. Henry`s law gas-solid chromatography and correlations of virial coefficients for hydrocarbons, chlorofluorocarbons, ethers, and sulfur hexafluoride adsorbed onto carbon

    SciTech Connect

    Rybolt, T.R.; Epperson, M.T.; Weaver, H.W.; Thomas, H.E.; Clare, S.E.; Manning, B.M.; McClung, J.T.

    1995-07-01

    Gas-solid chromatography was used to determine the Henry`s law second gas-solid virial coefficients within the temperature range of 314--615 K for ethane, propane, butane, isobutane, pentane, hexane, heptane, chloromethane, dichloromethane, trichloromethane, tetrachloromethane, trichlorofluoromethane (Freon 11), chlorodifluoromethane (Freon 22), dichlorodifluoromethane (Freon 12), methyl ether, ethyl ether, and sulfur hexafluoride with Carbopack B, a microporous carbon adsorbent. The temperature dependence of the second gas-solid virial coefficients of these adsorbates was used in conjunction with analyses based on a graphical method, a single-surface numeric integration method, a single-surface analytic expression method, and a two-surface analytic expression method to determine the gas-solid interaction energies and other parameters. The interaction energies were correlated with a ratio of the critical temperature divided by the square root of the critical pressure. The four methods were compared in their abilities to successfully calculate second gas-solid virial coefficient values.

  5. Chemical reactivity on gas-phase metal clusters driven by blackbody infrared radiation.

    PubMed

    Parry, Imogen S; Kartouzian, Aras; Hamilton, Suzanne M; Balaj, O Petru; Beyer, Martin K; Mackenzie, Stuart R

    2015-01-19

    We report the observation of chemical reactions in gas-phase Rh(n)(N2O)m(+) complexes driven by absorption of blackbody radiation. The experiments are performed under collision-free conditions in a Fourier transform ion cyclotron resonance mass spectrometer. Mid-infrared absorption by the molecularly adsorbed N2O moieties promotes a small fraction of the cluster distribution sufficiently to drive the N2O decomposition reaction, leading to the production of cluster oxides and the release of molecular nitrogen. N2O decomposition competes with molecular desorption and the branching ratios for the two processes show marked size effects, reflecting variations in the relative barriers. The rate of decay is shown to scale approximately linearly with the number of infrared chromophores. The experimental findings are interpreted in terms of calculated infrared absorption rates assuming a sudden-death limit.

  6. Propagation of a cylindrical shock wave in a mixture of a non-ideal gas and small solid particles under the action of monochromatic radiation

    NASA Astrophysics Data System (ADS)

    Sahu, Praveen Kumar; Nath, Gorakh

    2016-07-01

    Cylindrical shock wave in a dusty gas is discussed under the action of monochromatic radiation into stellar atmosphere with a constant intensity on unit area. The gas is assumed to be grey and opaque and shock to be transparent. The dusty gas is assumed to be a mixture of non-ideal gas and small solid particles. To obtain some essential features of the shock propagation, small solid particles are taken as pseudo-fluid and it is assumed that the equilibrium flow condition is maintained in the flow-field. The effects of variation of the parameters of the non-idealness of the gas, the mass concentration of solid particles in the mixture, the ratio of the density of solid particles to the initial density of the gas and the radiation parameter are investigated. It is shown that an increase in the parameters of the non-idealness of the gas and the radiation parameter have decaying effect on the shock waves; whereas with an increase in the ratio of the density of solid particles to the initial density of the gas the shock strength increases. It is found that an increase in the parameter non-idealness of the gas and the ratio of the density of solid particles to the initial density of the gas have opposite behaviour on fluid velocity, pressure and shock strength. Also, it is shown that an increase in the radiation parameter has effect to decrease the flow variables and the shock strength.

  7. Gas dynamic and force effects of a solid particle in a shock wave in air

    NASA Astrophysics Data System (ADS)

    Obruchkova, L. R.; Baldina, E. G.; Efremov, V. P.

    2017-03-01

    Shock wave interaction with an adiabatic solid microparticle is numerically simulated. In the simulation, the shock wave is initiated by the Riemann problem with instantaneous removal of a diaphragm between the high- and low-pressure chambers. The calculation is performed in the two-dimensional formulation using the ideal gas equation of state. The left end of the tube is impermeable, while outflow from the right end is permitted. The particle is assumed to be motionless, impermeable, and adiabatic, and the simulation is performed for time intervals shorted than the time of velocity and temperature relaxation of the particle. The numerical grid is chosen for each particle size to ensure convergence. For each particle size, the calculated hydraulic resistance coefficient describing the particle force impact on the flow is compared with that obtained from the analytical Stokes formula. It is discovered that the Stokes formula can be used for calculation of hydraulic resistance of a motionless particle in a shock wave flow. The influence of the particle diameter on the flow perturbation behind the shock front is studied. Specific heating of the flow in front of the particle is calculated and a simple estimate is proposed. The whole heated region is divided by the acoustic line into the subsonic and supersonic regions. It is demonstrated that the main heat generated by the particle in the flow is concentrated in the subsonic region. The calculations are performed using two different 2D hydro codes. The energy release in the flow induced by the particle is compared with the maximum possible heating at complete termination of the flow. The results can be used for estimating the possibility of gas ignition in front of the particle by a shock wave whose amplitude is insufficient for initiating detonation in the absence of a particle.

  8. Greenhouse gas emissions from municipal solid waste management in Vientiane, Lao PDR.

    PubMed

    Babel, Sandhya; Vilaysouk, Xaysackda

    2016-01-01

    Municipal solid waste (MSW) is one of the major environmental problems throughout the world including in Lao PDR. In Vientiane, due to the lack of a collection service, open burning and illegal dumping are commonly practised. This study aims to estimate the greenhouse gas (GHG) emission from the current situation of MSW management (MSWM) in Vientiane and proposes an alternative solution to reduce the GHG emission and environmental impacts. The 2006 Intergovernmental Panel on Climate Change (IPCC) Guidelines for National Greenhouse Gas Inventories (IPCC 2006 model) are used for the estimation of GHG emission from landfill and composting. For the estimation of GHG emission from open burning, the Atmospheric Brown Clouds Emission Inventory Manual (ABC EIM) is used. In Vientiane, a total of 232, 505 tonnes year(-1) of MSW was generated in 2011. Waste generation in Vientiane is 0.69 kg per capita per day, and about 31% of the total MSW generated was directly sent to landfill (71,162 tonnes year(-1)). The total potential GHG emission from the baseline scenario in 2011 was 110,182 tonnes year(-1) CO2-eq, which is 0.15 tonne year(-1) CO2-eq per capita. From the three MSWM scenarios proposed, scenario S3, which includes recycling, composting and landfilling, seems to be an effective solution for dealing with MSW in Vientiane with less air pollution, and is environmentally friendly. The total GHG emission in scenario S3 is reduced to 91,920 tonnes year(-1) CO2-eq (47% reduction), compared with the S1 scenario where all uncollected waste is diverted to landfill.

  9. Using dissolved gas analysis to investigate the performance of an organic carbon permeable reactive barrier for the treatment of mine drainage

    USGS Publications Warehouse

    Williams, R.L.; Mayer, K.U.; Amos, R.T.; Blowes, D.W.; Ptacek, C.J.; Bain, J.G.

    2007-01-01

    The strongly reducing nature of permeable reactive barrier (PRB) treatment materials can lead to gas production, potentially resulting in the formation of gas bubbles and ebullition. Degassing in organic C based PRB systems due to the production of gases (primarily CO2 and CH4) is investigated using the depletion of naturally occurring non-reactive gases Ar and N2, to identify, confirm, and quantify chemical and physical processes. Sampling and analysis of dissolved gases were performed at the Nickel Rim Mine Organic Carbon PRB, which was designed for the treatment of groundwater contaminated by low quality mine drainage characterized by slightly acidic pH, and elevated Fe(II) and SO4 concentrations. A simple 4-gas degassing model was used to analyze the dissolved gas data, and the results indicate that SO4 reduction is by far the dominant process of organic C consumption within the barrier. The data provided additional information to delineate rates of microbially mediated SO4 reduction and confirm the presence of slow and fast flow zones within the barrier. Degassing was incorporated into multicomponent reactive transport simulations for the barrier and the simulations were successful in reproducing observed dissolved gas trends.

  10. Solid-phase microextraction gas chromatography-mass spectrometry determination of fragrance allergens in baby bathwater.

    PubMed

    Lamas, J Pablo; Sanchez-Prado, Lucia; Garcia-Jares, Carmen; Llompart, Maria

    2009-07-01

    A method based on solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) has been optimized for the determination of fragrance allergens in water samples. This is the first study devoted to this family of cosmetic ingredients performed by SPME. The influence of parameters such as fibre coating, extraction and desorption temperatures, salting-out effect and sampling mode on the extraction efficiency has been studied by means of a mixed-level factorial design, which allowed the study of the main effects as well as two-factor interactions. Excluding desorption temperature, the other parameters were, in general, very important for the achievement of high response. The final procedure was based on headspace sampling at 100 degrees C, using polydimethylsiloxane/divinylbenzene fibres. The method showed good linearity and precision for all compounds, with detection limits ranging from 0.001 to 0.3 ng mL(-1). Reliability was demonstrated through the evaluation of the recoveries in different real water samples, including baby bathwater and swimming pool water. The absence of matrix effects allowed the use of external standard calibration to quantify the target compounds in the samples. The proposed procedure was applied to the determination of allergens in several real samples. All the target compounds were found in the samples, and, in some cases, at quite high concentrations. The presence and the levels of these chemicals in baby bathwater should be a matter of concern.

  11. Heat removal from high temperature tubular solid oxide fuel cells utilizing product gas from coal gasifiers.

    SciTech Connect

    Parkinson, W. J. ,

    2003-01-01

    In this work we describe the results of a computer study used to investigate the practicality of several heat exchanger configurations that could be used to extract heat from tubular solid oxide fuel cells (SOFCs) . Two SOFC feed gas compositions were used in this study. They represent product gases from two different coal gasifier designs from the Zero Emission Coal study at Los Alamos National Laboratory . Both plant designs rely on the efficient use of the heat produced by the SOFCs . Both feed streams are relatively rich in hydrogen with a very small hydrocarbon content . One feed stream has a significant carbon monoxide content with a bit less hydrogen . Since neither stream has a significant hydrocarbon content, the common use of the endothermic reforming reaction to reduce the process heat is not possible for these feed streams . The process, the method, the computer code, and the results are presented as well as a discussion of the pros and cons of each configuration for each process .

  12. Greenhouse gas emission mitigation relevant to changes in municipal solid waste management system.

    PubMed

    Pikoń, Krzysztof; Gaska, Krzysztof

    2010-07-01

    Standard methods for assessing the environmental impact of waste management systems are needed to underpin the development and implementation of sustainable waste management practice. Life cycle assessment (LCA) is a tool for comprehensively ensuring such assessment and covers all impacts associated with waste management. LCA is often called "from cradle to grave" analysis. This paper integrates information on the greenhouse gas (GHG) implications of various management options for some of the most common materials in municipal solid waste (MSW). Different waste treatment options for MSW were studied in a system analysis. Different combinations of recycling (cardboard, plastics, glass, metals), biological treatment (composting), and incineration as well as land-filling were studied. The index of environmental burden in the global warming impact category was calculated. The calculations are based on LCA methodology. All emissions taking place in the whole life cycle system were taken into account. The analysis included "own emissions," or emissions from the system at all stages of the life cycle, and "linked emissions," or emissions from other sources linked with the system in an indirect way. Avoided emissions caused by recycling and energy recovery were included in the analysis. Displaced emissions of GHGs originate from the substitution of energy or materials derived from waste for alternative sources. The complex analysis of the environmental impact of municipal waste management systems before and after application of changes in MSW systems according to European Union regulations is presented in this paper. The evaluation is made for MSW systems in Poland.

  13. Estimation of the main dill seeds odorant carvone by solid-phase microextraction and gas chromatography.

    PubMed

    Zawirska-Wojtasiak, Renata; Wasowicz, Erwin

    2002-10-01

    Solid-phase microextraction (SPME) was examined for its suitability for isolation of volatiles from seeds of dill in comparison with the traditional steam distillation procedure. Two main dill seeds volatiles, carvone and limonene, were taken into consideration. Two Supelco SPME fibers were used for the extraction: polyacrylic (PAc) and polydimethylsiloxane (PDMS). The time required to saturate the fibers was 3 min, while distillation took 3 h. Gas chromatography (GC) separation was reduced to 5 min by use of microcapillary column HP-5 cross-linked 5% Ph Me Siloxane. The standards of limonene and carvone were used to prepare calibration curves. PAc fiber responses were described by quadratic curves while PDMS responded linearly. Six varieties of dill were examined by distillation and SPME with both fibers. The good results were achieved for carvone by SPME-PDMS with significant regression between distillation and SPME. This compound can be measured in dill seeds samples within 10 min. The SPME-PDMS were also tested for its application to chiral resolution of carvone and limonene enantiomers in dill seeds oil. The enantiomeric separation was done with two chiral columns. The enantiomeric ratios measured by SPME were just the same as with distillation.

  14. Real time mass flux measurements of gas-solid suspensions at low velocities

    SciTech Connect

    Saunders, J H; Chao, B T; Soo, S L

    1981-01-01

    In previous work, measurement of the particulate mass flux was made based upon a novel electrostatic technique. A small conducting wire sensor was inserted in the flow and as each particle hit the sensor an individual pulse of current was identified. Through suitable electronic circuitry, the number of pulses in a given time were counted. This was a direct measure of the number of particle-probe collisions which was related to local particle mass flow. The technique is currently limited to monodisperse suspensions. A primary advantage of the impact counter system is that the output does not depend upon the magnitude of the actual charge transfer. As long as the pulses are sufficiently above the noise level, variations in charge transfer will not affect the measurement. For the current work, the technique was applied to vertical gas-solid flow where the fluid velocity was slightly above the particle terminal velocity. Under these conditions a sufficient signal to noise ratio was not found. The Cheng-Soo charge transfer theory indicated that the low particle-sensor impact velocity was responsible. The probe system was then modified by extracting a particulate sample isokinetically and accelerating the particles to a sufficient velocity by an area reduction in the sampling tube. With this technique the signal to noise ratio was about 12 to 1. Mass flux results are shown to compare favorably with filter collection and weighing.

  15. Gas-phase synthesis of Mg-Ti nanoparticles for solid-state hydrogen storage.

    PubMed

    Calizzi, M; Venturi, F; Ponthieu, M; Cuevas, F; Morandi, V; Perkisas, T; Bals, S; Pasquini, L

    2016-01-07

    Mg-Ti nanostructured samples with different Ti contents were prepared via compaction of nanoparticles grown by inert gas condensation with independent Mg and Ti vapour sources. The growth set-up offered the option to perform in situ hydrogen absorption before compaction. Structural and morphological characterisation was carried out by X-ray diffraction, energy dispersive spectroscopy and electron microscopy. The formation of an extended metastable solid solution of Ti in hcp Mg was detected up to 15 at% Ti in the as-grown nanoparticles, while after in situ hydrogen absorption, phase separation between MgH2 and TiH2 was observed. At a Ti content of 22 at%, a metastable Mg-Ti-H fcc phase was observed after in situ hydrogen absorption. The co-evaporation of Mg and Ti inhibited nanoparticle coalescence and crystallite growth in comparison with the evaporation of Mg only. In situ hydrogen absorption was beneficial to subsequent hydrogen behaviour, studied by high pressure differential scanning calorimetry and isothermal kinetics. A transformed fraction of 90% was reached within 100 s at 300 °C during both hydrogen absorption and desorption. The enthalpy of hydride formation was not observed to differ from bulk MgH2.

  16. Nonlocal van der Waals functionals: The case of rare-gas dimers and solids

    NASA Astrophysics Data System (ADS)

    Tran, Fabien; Hutter, Jürg

    2013-05-01

    Recently, the nonlocal van der Waals (vdW) density functionals [M. Dion, H. Rydberg, E. Schröder, D. C. Langreth, and B. I. Lundqvist, Phys. Rev. Lett. 92, 246401 (2004), 10.1103/PhysRevLett.92.246401] have attracted considerable attention due to their good performance for systems where weak interactions are important. Since the physics of dispersion is included in these functionals, they are usually more accurate and show less erratic behavior than the semilocal and hybrid methods. In this work, several variants of the vdW functionals have been tested on rare-gas dimers (from He2 to Kr2) and solids (Ne, Ar, and Kr) and their accuracy compared to standard semilocal approximations, supplemented or not by an atom-pairwise dispersion correction [S. Grimme, J. Antony, S. Ehrlich, and H. Krieg, J. Chem. Phys. 132, 154104 (2010), 10.1063/1.3382344]. An analysis of the results in terms of energy decomposition is also provided.

  17. Determination of terpenes in tequila by solid phase microextraction-gas chromatography-mass spectrometry.

    PubMed

    Peña-Alvarez, Araceli; Capella, Santiago; Juárez, Rocío; Labastida, Carmen

    2006-11-17

    Solid phase microextraction and capillary gas chromatography-mass spectrometry were used for the determination of seven terpenes in tequila. The method was selected based on the following parameters: coating selection (PA, PDMS, CW/DVB, and PDMS/DVB), extraction temperature, addition of salt, and extraction time profile. The extraction conditions were: PDMS/DVB fiber, Headspace, 100% NaCl, 25 degrees C extraction temperature, 30 min extraction time and stirring at 1200 rpm. The calibration curves (50-1000 ng/ml) for the terpenes followed linear relationships with correlation coefficients (r) greater than 0.99, except for trans,trans-farnesol (r = 0.98). RSD values were smaller than 10% confirmed that the technique was precise. Samples from 18 different trade brands of "Aged" tequila analyzed with the developed method showed the same terpenes in different concentrations. The analytical procedure used is selective, robust (more than 100 analyses with the same fiber), fast and of low-cost.

  18. Power decoupling control of a solid oxide fuel cell and micro gas turbine hybrid power system

    NASA Astrophysics Data System (ADS)

    Wu, Xiao-Juan; Huang, Qi; Zhu, Xin-Jian

    Solid Oxide Fuel Cell (SOFC) integrated into Micro Gas Turbine (MGT) is a multivariable nonlinear and strong coupling system. To enable the SOFC and MGT hybrid power system to follow the load profile accurately, this paper proposes a self-tuning PID decoupling controller based on a modified output-input feedback (OIF) Elman neural network model to track the MGT output power and SOFC output power. During the modeling, in order to avoid getting into a local minimum, an improved particle swarm optimization (PSO) algorithm is employed to optimize the weights of the OIF Elman neural network. Using the modified OIF Elman neural network identifier, the SOFC/MGT hybrid system is identified on-line, and the parameters of the PID controller are tuned automatically. Furthermore, the corresponding decoupling control law is achieved by the conventional PID control algorithm. The validity and accuracy of the decoupling controller are tested by simulations in MATLAB environment. The simulation results verify that the proposed control strategy can achieve favorable control performance with regard to various load disturbances.

  19. Quantification of Greenhouse Gas Emissions from the Predisposal Stage of Municipal Solid Waste Management.

    PubMed

    Zhou, Chuanbin; Jiang, Daqian; Zhao, Zhilan

    2017-01-03

    Municipal solid waste (MSW) disposal represents one of the largest sources of anthropogenic greenhouse gas (GHG) emissions. However, the biogenic GHG emissions in the predisposal stage of MSW management (i.e., the time from waste being dropped off in community or household garbage bins to being transported to disposal sites) are excluded from the IPCC inventory methodology and rarely discussed in academic literature. Herein, we quantify the effluxes of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) from garbage bins in five communities along the urban-rural gradient in Beijing in four seasons. We find that the annual average CO2, CH4, and N2O effluxes in the predisposal stage were (1.6 ± 0.9)10(3), 0.049 ± 0.016, and 0.94 ± 0.54 mg kg(-1)h(-1) (dry matter basis) and had significant seasonal differences (24- to 159-fold) that were strongly correlated with temperature. According to our estimate, the N2O emission in the MSW predisposal stage amounts to 20% of that in the disposal stage in Beijing, making the predisposal stage a nontrivial source of waste-induced N2O emissions. Furthermore, the CO2 and CH4 emissions in the MSW predisposal account for 5% (maximum 10% in summer) of the total carbon contents in a Beijing's household food waste stream, which has significance in the assessment of MSW-related renewable energy potential and urban carbon cycles.

  20. Electromotive Force for Solid Oxide Fuel Cells Using Biomass Produced Gas as Fuel

    NASA Astrophysics Data System (ADS)

    Zhu, Wei; Yin, Yan-hong; Gao, Cen; Xia, Chang-rong; Meng, Guang-yao

    2006-08-01

    The electromotive force (e.m.f.) of solid oxide fuel cells using biomass produced gas (BPG) as the fuels is calculated at 700-1,200 K using an in-house computer program, based on thermodynamic equilibrium analysis. Tour program also predicts the concentration of oxygen in the fuel chamber as well as the concentration of equilibrium species such as H2, CO, CO2 and CH4. Compared with using hydrogen as a fuel, the e.m.f. for cells using BPG as the fuels is relative low and strongly influenced by carbon deposition. To remove carbon deposition, the optimum amount of H2O to add is determined at various operating temperatures. Further the e.m.f. for cells based on yttria stabilized zirconia and doped ceria as electrolytes are compared. The study reveals that when using BPG as fuel, the depression of e.m.f. for a SOFC using doped ceria as electrolyte is relatively small when compared with that using Yttria stabilized zirconia.

  1. Magnetic solid phase extraction and gas chromatography-mass spectrometrical analysis of sixteen polycyclic aromatic hydrocarbons.

    PubMed

    Cai, Ying; Yan, Zhihong; NguyenVan, Manh; Wang, Lijia; Cai, Qingyun

    2015-08-07

    Fluorenyl functionalized superparamagnetic core/shell magnetic nanoparticles (MNPs, Fe3O4@SiO2@Flu) were prepared and characterized by transmission electron microscope, X-ray diffraction and infrared spectroscopy. The MNPs having an average diameter of 200nm were then used as solid-phase extraction sorbent for the determination of 16 priority pollutants polycyclic aromatic hydrocarbons (PAHs) in water samples designated by United States Environmental Protection Agency (U.S. EPA). The main influencing parameters, including sorbent amount, desorption solvent, sample volume and extraction time were optimized. Analyses were performed on gas chromatography-mass spectrometry (GC-MS) using selected ion monitoring (SIM) mode. Method validation proved the feasibility of the developed sorbents for the quantitation of the investigated analytes at trace levels. Limit of detection ranging from 0.5 to 4.0ng/L were obtained. The repeatability was investigated by evaluating the intra- and inter-day precisions with relative standard deviations (RSDs) lower than 13.1%. Finally, the proposed method was successfully applied for the determination of PAHs in water samples with the recoveries in the range of 96.0-106.7%.

  2. Durable solid lubricant coatings for foil gas bearings to 315 deg C

    NASA Technical Reports Server (NTRS)

    Wagner, R. C.; Sliney, H. E.

    1984-01-01

    The durability and friction characteristics of bonded solid lubricant films on compliant gas bearings were measured. Coating compositions, which were judged to be suitable for use to at least 315 C, were selected for this study. Most of the data were obtained with polyimide-bonded graphite fluoride coatings and with silicate-bonded graphite coatings. These coatings were applied to the bore of Inconel 750 foil bearings. The journals were A286 stainless steel, with a rms surface finish of 0.2 microns. The foils were subjected to repeated start/stop cycles under a 14 kPa (2 psi) bearing unit load. Sliding contact occurred during lift-off and coast down at surface velocities less than 6 m/s (3000 rpm). Testing continued until 9000 cycles were accumulated or until a rise in starting torque indicated that the coating had failed. The coatings were evaluated in the temperature range from 25 C to 315 C. Comparisons in coating performance as well as discussions of their properties and methods of application are given.

  3. Reactive transport modeling of the long-term effects of CO2 storage in the P18 depleted gas field

    NASA Astrophysics Data System (ADS)

    Tambach, T. J.; Koenen, M.; Wasch, L. J.; Loeve, D.; Maas, J. G.

    2012-04-01

    Depleted gas fields are an import CO2 storage sink for The Netherlands, with a total storage capacity of more than 3 Gtonne. The CO2 sources are located at relatively short distances from potential storage reservoirs and an infrastructure for (cross-border) gas transport over large distances already exists. Several depleted gas fields in the subsurface of the Netherlands have yet been evaluated as potential locations for CO2 storage (for example the K12-B field). The P18 gas field is located in the offshore of The Netherlands and is currently evaluated as potential CO2 storage reservoir. The aim of this study is to predict the long-term effects of CO2 injection into the P18 field using reactive transport modeling (TOUGHREACT). The storage reservoir is described using the mineralogy and petrophysical characteristics of three geological layers in a radial (R,Z) reservoir model with top depth of 3456 m, a thickness of 98 m, and 3300 grid cells. The initial reservoir temperature was defined as 90 degrees C with an initial (depletion) pressure of 20.0 bars. Capillary pressure curves are based on empirical relations. The CO2 is injected uniformly distributed over the model height, at a constant rate of 35 kg/s (1.1 Mton/year), and a temperature of 40 degrees C for 30 years. The well is then shut-in with a reservoir pressure of approximately 375 bar. The simulations are continued up to 10,000 years for computing the long-term effects in the reservoir. The results show that the near-well area is dried out during injection, leading to salt precipitation and reduced permeability during injection. Condensation of the evaporated water occurs outside the near-well area. Water imbibition is modelled after shut in of the well, leading to rewetting of the near-well area and redissolution of the salt. Most geochemical reactions need water to occur, including well-cement minerals, and therefore predictions of water flow after well shut-ins are important to take into account

  4. Reactions of atomic cations with methane: gas phase room-temperature kinetics and periodicities in reactivity.

    PubMed

    Shayesteh, Alireza; Lavrov, Vitali V; Koyanagi, Gregory K; Bohme, Diethard K

    2009-05-14

    Reactions of methane have been measured with 59 atomic metal cations at room temperature in helium bath gas at 0.35 Torr using an inductively-coupled plasma/selected-ion flow tube (ICP/SIFT) tandem mass spectrometer. The atomic cations were produced at approximately 5500 K in an ICP source and allowed to decay radiatively and to thermalize by collisions with argon and helium atoms prior to reaction. Rate coefficients and product distributions are reported for the reactions of fourth-row atomic cations from K(+) to Se(+), of fifth-row atomic cations from Rb(+) to Te(+) (excluding Tc(+)), of sixth-row atomic cations from Cs(+) to Bi(+), and of the lanthanide cations from La(+) to Lu(+) (excluding Pm(+)). Two primary reaction channels were observed: C-H bond insertion with elimination of H(2), and CH(4) addition. The bimolecular H(2) elimination was observed in the reactions of CH(4) with As(+), Nb(+), and some sixth-row metal cations, i.e., Ta(+), W(+), Os(+), Ir(+), Pt(+); secondary and higher-order H(2) elimination was observed exclusively for Ta(+), W(+), and Ir(+) ions. All other transition-metal cations except Mn(+) and Re(+) were observed to react with CH(4) exclusively by addition, and up to two methane molecules were observed to add sequentially to most transition-metal ions. CH(4) addition was also observed for Ge(+), Se(+), La(+), Ce(+), and Gd(+) ions, while the other main-group and lanthanide cations did not react measurably with methane.

  5. Characteristics and reactivity of rapidly hydrated sorbent for semidry flue gas desulfurization

    SciTech Connect

    Jie Zhang; Changfu You; Suwei Zhao; Changhe Chen; Haiying Qi

    2008-03-01

    The semidry flue gas desulfurization (FGD) process has many advantages over the wet FGD process for moving sulfur dioxide emissions from pulverized coal-fired power plants. Semidry FGD with a rapidly hydrated sorbent was studied in a pilot-scale circulating fluidized bed (CFB) experimental facility. The sorbent was made from lumps of lime and coal fly ash. The desulfurization efficiency was measured for various operating parameters, including the sorbent recirculation rate and the water spray method. The experimental results show that the desulfurization efficiencies of the rapidly hydrated sorbent were 1.5-3.0 times higher than a commonly used industrial sorbent for calcium to sulfur molar ratios from 1.2 to 3.0, mainly due to the higher specific surface area and pore volume. The Ca(OH){sub 2} content in the cyclone separator ash was about 2.9% for the rapidly hydrated sorbent and was about 0.1% for the commonly used industrial sorbent, due to the different adhesion between the fine Ca(OH){sub 2} particles and the fly ash particles, and the low cyclone separation efficiency for the fine Ca(OH){sub 2} particles that fell off the sorbent particles. Therefore the actual recirculation rates of the active sorbent with Ca(OH){sub 2} particles were higher for the rapidly hydrated sorbent, which also contributed to the higher desulfurization efficiency. The high fly ash content in the rapidly hydrated sorbent resulted in good operating stability. The desulfurization efficiency with upstream water spray was 10-15% higher than that with downstream water spray. 20 refs., 7 figs., 1 tab.

  6. Setup for in situ investigation of gases and gas/solid interfaces by soft x-ray emission and absorption spectroscopy

    SciTech Connect

    Benkert, A. E-mail: l.weinhardt@kit.edu; Blum, M.; Meyer, F.; Wilks, R. G.; Yang, W.; Bär, M.; and others

    2014-01-15

    We present a novel gas cell designed to study the electronic structure of gases and gas/solid interfaces using soft x-ray emission and absorption spectroscopies. In this cell, the sample gas is separated from the vacuum of the analysis chamber by a thin window membrane, allowing in situ measurements under atmospheric pressure. The temperature of the gas can be regulated from room temperature up to approximately 600 °C. To avoid beam damage, a constant mass flow can be maintained to continuously refresh the gaseous sample. Furthermore, the gas cell provides space for solid-state samples, allowing to study the gas/solid interface for surface catalytic reactions at elevated temperatures. To demonstrate the capabilities of the cell, we have investigated a TiO{sub 2} sample behind a mixture of N{sub 2} and He gas at atmospheric pressure.

  7. Gas-phase detection of solid-state fission product complexes for post-detonation nuclear forensic analysis.

    PubMed

    Stratz, S Adam; Jones, Steven A; Oldham, Colton J; Mullen, Austin D; Jones, Ashlyn V; Auxier, John D; Hall, Howard L

    2016-01-01

    This study presents the first known detection of fission products commonly found in post-detonation nuclear debris samples using solid sample introduction and a uniquely coupled gas chromatography inductively-coupled plasma time-of-flight mass spectrometer. Rare earth oxides were chemically altered to incorporate a ligand that enhances the volatility of the samples. These samples were injected (as solids) into the aforementioned instrument and detected for the first time. Repeatable results indicate the validity of the methodology, and this capability, when refined, will prove to be a valuable asset for rapid post-detonation nuclear forensic analysis.

  8. Surfactant assisted solid-state synthesis and gas sensor application of a SWCNT/SnO2 nanocomposite material.

    PubMed

    Lu, Jun; Ma, Anson; Yang, Shihe; Ng, Ka Ming

    2007-01-01

    Although tin oxide has been the most widely investigated metal oxide material for gas detection, it suffers from the large resistance and high operating temperature. This could be overcome by hybridization with nanostructured carbon. In this work, tin oxide nanoparticles with ultrasmall sizes of 1-3 nm have been uniformly coated onto bundles of single-walled carbon nanotubes by a surfactant assisted solid state synthesis approach for the first time. Gas sensor properties of the as-synthesized nanocomposite material toward NO2 (from 5 to 60 ppm) are measured at 150 degrees C. Compared to the pure carbon tubes gas sensors, the nanocomposite gas sensor responds to NO2 in low concentrations with good linearity, high sensitivity, and fast recovery, while working at a relatively low temperature.

  9. Gas phase studies of the Pesci decarboxylation reaction: synthesis, structure, and unimolecular and bimolecular reactivity of organometallic ions.

    PubMed

    O'Hair, Richard A J; Rijs, Nicole J

    2015-02-17

    promoting the formation of the organometallic ion. Where isomeric organometallic ions are generated and normal MS approaches cannot distinguish them, we describe approaches to elucidate the decarboxylation mechanism via determination of their structure. These "unmasked" organometallic ions, [RM(L)n](x), can also be structurally interrogated spectroscopically or via CID. We have thus compared the gas-phase structures and decomposition of several highly reactive and synthetically important organometallic ions for the first time. Perhaps the most significant aspect of this work is the study of bimolecular reactions, which provides experimental information on mechanistically obscure bond-formation and cross-coupling steps and the intrinsic reactivity of ions. We have sought to understand transformations of substrates including acid-base and hydrolysis reactions, along with reactions resulting in C-C bond formation. Our studies also allow a direct comparison of the performance of different metal catalysts in the individual elementary steps associated with protodecarboxylation and decarboxylative alkylation cycles. Electronic structure (DFT and ab initio) and dynamics (RRKM) calculations provide further mechanistic insights into these reactions. The broad implications of this research are that new reactions can be discovered and that the performance of metal catalysts can be evaluated in terms of each of their elementary steps. This has been particularly useful for the study of metal-mediated decarboxylation reactions.

  10. Uncertainty quantification tools for multiphase gas-solid flow simulations using MFIX

    SciTech Connect

    Fox, Rodney O.; Passalacqua, Alberto

    2016-02-01

    MFIX. The effect of uncertainty on the disperse-phase volume fraction, on the phase velocities and on the pressure drop inside the fluidized bed are examined, and the reconstructed PDFs are provided for the three quantities studied. Then the approach is applied to a bubbling fluidized bed with two uncertain parameters, particle-particle and particle-wall restitution coefficients. Contour plots of the mean and standard deviation of solid volume fraction, solid phase velocities and gas pressure are provided. The PDFs of the response are reconstructed using EQMOM with appropriate kernel density functions. The simulation results are compared to experimental data provided by the 2013 NETL small-scale challenge problem. Lastly, the proposed procedure is demonstrated by considering a riser of a circulating fluidized bed as an example application. The mean particle size is considered to be the uncertain input parameter. Contour plots of the mean and standard deviation of solid volume fraction, solid phase velocities, and granular temperature are provided. Mean values and confidence intervals of the quantities of interest are compared to the experiment results. The univariate and bivariate PDF reconstructions of the system response are performed using EQMOM and ECQMOM.

  11. Mechanism of kinetic energy transfer in homogeneous bidisperse gas-solid flow and its implications for segregation

    NASA Astrophysics Data System (ADS)

    Mehrabadi, Mohammad; Subramaniam, Shankar

    2017-02-01

    Most gas-solid flows encountered in nature and industrial applications are polydisperse, and the segregation or mixing of particle classes in polydisperse gas-solid flows is a phenomenon of great practical importance. A statistically homogeneous gas-solid flow with a bidisperse distribution (in size or density) of particles is a canonical representation of polydisperse flows. A key feature that distinguishes the bidisperse flow from its monodisperse counterpart is the exchange of momentum and kinetic energy between the particle classes due to collisions, which are important for applications outside the very dilute regime. The average exchange of linear momentum between particle classes due to collisions occurs through the particle-particle drag term. The conservation equations for average momentum corresponding to each particle class can be used to deduce the average slip velocity between the particle size and density classes, which is the signature of particle segregation. In this canonical problem, the steady value of particle mean slip velocity results from a balance between three terms, each in turn involving the body force or the mean fluid pressure gradient, the gas-particle drag, and the particle-particle drag. The particle-particle drag depends on the particle velocity fluctuations in each class [Louge, M. Y. et al., "The role of particle collisions in pneumatic transport," J. Fluid Mech. 231, 345-359 (1991)], thereby coupling the mean and second-moment equations. For monodisperse gas-solid flows the transfer of kinetic energy from the mean to second-moment equations was explained by Subramaniam and co-workers who proposed the conservation of interphase turbulent kinetic energy transfer principle [Xu, Y. and Subramaniam, S., "Consistent modeling of interphase turbulent kinetic energy transfer in particle-laden turbulent flows," Phys. Fluids 19(8), 085101 (2007)], and this was subsequently verified by particle-resolved direct numerical simulation [Mehrabadi

  12. Vapor-liquid-solid epitaxial growth of Si1-xGex alloy nanowires. Composition dependence on precursor reactivity and morphology control for vertical forests

    SciTech Connect

    Choi, S. G.; Manandhar, P.; Picraux, S. T.

    2015-07-07

    The growth of high-density group IV alloy nanowire forests is critical for exploiting their unique functionalities in many applications. Here, the compositional dependence on precursor reactivity and optimized conditions for vertical growth are studied for Si1- x Ge x alloy nanowires grown by the vapor-liquid-solid method. The nanowire composition versus gas partial-pressure ratio for germane-silane and germane-disilane precursor combinations is obtained at 350°C over a wide composition range (0.05 ≤ x ≤ 0.98) and a generalized model to predict composition for alloy nanowires is developed based on the relative precursor partial pressures and reactivity ratio. In combination with germane, silane provides more precise compositional control at high Ge concentrations (x > 0.7), whereas disilane greatly increases the Si concentration for a given gas ratio and enables more precise alloy compositional control at small Ge concentrations (x < 0.3). Vertically oriented, non-kinking nanowire forest growth on Si (111) substrates is then discussed for silane/germane over a wide range of compositions, with temperature and precursor partial pressure optimized by monitoring the nanowire growth front using in-situ optical reflectance. For high Ge compositions (x ≈ 0.9), a “two-step” growth approach with nucleation at higher temperatures results in nanowires with high-density and uniform vertical orientation. Furthermore, increasing Si content (x ≈ 0.8), the optimal growth window is shifted to higher temperatures, which minimizes nanowire kinking morphologies. For Si-rich Si1- x Ge x alloys (x ≈ 0.25), vertical nanowire growth is enhanced by single-step, higher-temperature growth at reduced pressures.

  13. The Organic Matter of Comet P/Halley as Inferred by Joint Gas and Solid Phase Analysis

    NASA Astrophysics Data System (ADS)

    Krueger, F. R.; Korth, A.; Kissel, J.

    1997-12-01

    During the encounters with comet Halley, PICCA on GIOTTO measured the gas phase organic ion composition of the coma, and PUMA on VEGA 1 measured the dust composition. Joining those results a consistent picture of the parent organic matter from which dust and gas is produced can be obtained. One recognizes a complex unsaturated polycondensate, which splits during coma-formation into the more refractory C=C,C-N-containing dust part, and the more volatile C=C,C-O-containing gas part. The responsible exothermal chemical reactions, triggered by the sun light may play a major role in the dynamics of coma formation. The latent heat and reactivity may cause problems regarding a sample return mission.

  14. A system using solid ceramic oxygen electrolyte cells to measure oxygen fugacities in gas-mixing systems

    NASA Technical Reports Server (NTRS)

    Williams, R. J.; Mullins, O.

    1976-01-01

    Details are given for the construction and operation of a 101.3 kN/sq m (1 atmosphere) redox control system. A solid ceramic oxygen electrolyte cell is used to monitor the oxygen fugacity in the furnace. The system consists of a vertical quench, gas mixing furnace with heads designed for mounting the electrolyte cell and with facilities for inserting and removing the samples. The system also contains the high input impedance electronics necessary for measurements, a simplified version of a gas mixing apparatus, and devices for experiments under controlled rates of change relative to temperature and redox state. The calibration and maintenance of the system are discussed.

  15. Chemical characterization of diesel and hydrotreated vegetable oil (HVO) soot after reactive gas probing using diffuse reflectance FTIR spectroscopy (DRIFTS).

    PubMed

    Tapia, A; Salgado, M S; Martín, M P; Rodríguez-Fernández, J; Rossi, M J; Cabañas, B

    2017-01-23

    A chemical characterization of diesel and hydrotreated vegetable oil (HVO) soot has been developed using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) before and after the reaction with different probe gases. Samples were generated under combustion conditions corresponding to an urban operation mode of a diesel engine and were reacted with probe gas-phase molecules in a Knudsen flow reactor. Specifically, NH2OH, O3 and NO2 were used as reactants (probes) and selected according to their reactivities towards specific functional groups on the sample surface. Samples of previously ground soot were diluted with KBr and were introduced in a DRIFTS accessory. A comparison between unreacted and reacted soot samples was made in order to establish chemical changes on the soot surface upon reaction. It was concluded that the interface of diesel and HVO soot before reaction mainly consists polycyclic aromatic hydrocarbons, nitro and carbonyl compounds, as well as ether functionalities. The main difference between both soot samples was observed in the band of the C=O groups that in diesel soot was observed at 1719 cm(-1) but not in HVO soot. After reaction with probe gases, it was found that nitro compounds remain on the soot surface, that the degree of unsaturation decreases for reacted samples, and that new spectral bands such as hydroxyl groups are observed.

  16. Development of a Solid-Oxide Fuel Cell/Gas Turbine Hybrid System Model for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Freeh, Joshua E.; Pratt, Joseph W.; Brouwer, Jacob

    2004-01-01

    Recent interest in fuel cell-gas turbine hybrid applications for the aerospace industry has led to the need for accurate computer simulation models to aid in system design and performance evaluation. To meet this requirement, solid oxide fuel cell (SOFC) and fuel processor models have been developed and incorporated into the Numerical Propulsion Systems Simulation (NPSS) software package. The SOFC and reformer models solve systems of equations governing steady-state performance using common theoretical and semi-empirical terms. An example hybrid configuration is presented that demonstrates the new capability as well as the interaction with pre-existing gas turbine and heat exchanger models. Finally, a comparison of calculated SOFC performance with experimental data is presented to demonstrate model validity. Keywords: Solid Oxide Fuel Cell, Reformer, System Model, Aerospace, Hybrid System, NPSS

  17. Modeling of gas turbine - solid oxide fuel cell systems for combined propulsion and power on aircraft

    NASA Astrophysics Data System (ADS)

    Waters, Daniel Francis

    This dissertation investigates the use of gas turbine (GT) engine integrated solid oxide fuel cells (SOFCs) to reduce fuel burn in aircraft with large electrical loads like sensor-laden unmanned air vehicles (UAVs). The concept offers a number of advantages: the GT absorbs many SOFC balance of plant functions (supplying fuel, air, and heat to the fuel cell) thereby reducing the number of components in the system; the GT supplies fuel and pressurized air that significantly increases SOFC performance; heat and unreacted fuel from the SOFC are recaptured by the GT cycle offsetting system-level losses; good transient response of the GT cycle compensates for poor transient response of the SOFC. The net result is a system that can supply more electrical power more efficiently than comparable engine-generator systems with only modest (<10%) decrease in power density. Thermodynamic models of SOFCs, catalytic partial oxidation (CPOx) reactors, and three GT engine types (turbojet, combined exhaust turbofan, separate exhaust turbofan) are developed that account for equilibrium gas phase and electrochemical reaction, pressure losses, and heat losses in ways that capture `down-the-channel' effects (a level of fidelity necessary for making meaningful performance, mass, and volume estimates). Models are created in a NASA-developed environment called Numerical Propulsion System Simulation (NPSS). A sensitivity analysis identifies important design parameters and translates uncertainties in model parameters into uncertainties in overall performance. GT-SOFC integrations reduce fuel burn 3-4% in 50 kW systems on 35 kN rated engines (all types) with overall uncertainty <1%. Reductions of 15-20% are possible at the 200 kW power level. GT-SOFCs are also able to provide more electric power (factors >3 in some cases) than generator-based systems before encountering turbine inlet temperature limits. Aerodynamic drag effects of engine-airframe integration are by far the most important

  18. Simultaneous particulates, NO sub x , SO sub x removal from flue gas by all solid-state electrochemical technology

    SciTech Connect

    Cook, W.J.; Cornell, L.P.; Keyvani, M.; Neyman, M.

    1989-11-09

    The objective is to develop an all solid-state electrochemical technology to control SOx, NOx, and particulate emissions from coal combustion flue gases. It is based on a solid-state, electrochemical reactor which reduces NOx and SO{sub 2} to nitrogen, sulfur, and oxygen. Work was performed in the area of electrocatalyst preparation and testing. Transition metal oxides (Ru, Cr, V, W, Co, Mo), mixtures of transition metal oxides and transition metal oxide perovskites were tested as electrocatalysts. The electrocatalyst along with gold electrodes were coated and fired on a yittria stabilized ceria solid electrolyte disk. The reduction of NO and SO{sub 2} in gas mixtures containing 0 to 4% oxygen was measured while a voltage was applied to the disk. 3 refs., 5 figs., 4 tabs.

  19. [Determination of phthalic acid esters in textiles by solid phase extraction-gas chromatography].

    PubMed

    Niu, Zengyuan; Ye, Xiwen; Fang, Liping; Xue, Qiuhong; Sun, Zhongsong

    2006-09-01

    A method was established for the simultaneous determination of some phthalic acid esters, namely, dimethyl phthalate (DMP), diethyl phthalate (DEP), dipropyl phthalate (DPrP), dibutyl phthalate (DBP), diamyl phthalate (DAP), dihexyl phthalate (DHP), benzyln-butyl phthalate (BBP), di-(2-ethylhexyl) phthalate (DEHP), dicyclohexyl phthalate (DCHP), di-n-octyl phthalate (DNOP), diisononyl phthalate (DINP) and diisodecyl phthalate (DIDP) in textiles by solid phase extraction (SPE) coupled with gas chromatography (GC). The phthalic acid esters in textiles were extracted by Soxhlet extraction with hexane, the extracts were then cleaned up and enriched by a strong anion exchange (SAX) SPE cartridge. The parameters affecting the purification efficiency of SPE cartridge, such as solvent conditioning, rinsing, and elution, were studied. Conditioning with 5 mL hexane and rinsing with 3 mL isooctane were proved to be the optimal conditions. Of the several solvent ratios (ethylacetate in hexane) used for selective elution of phthalic acid esters from the SAX SPE cartridge, the 15% (v/v) content for ethylacetate in hexane gave the best result. Under the optimized conditions, the recoveries of phthalic acid esters for spiked standards (n=7) were 86.3%-102.7%, and the relative standard deviations (RSDs) were less than 5%. In this method the detection limits for DMP, DEP, DPrP, DBP, DAP, BBP, DCHP, DEHP, DNOP were all below 1 mg/kg, and the detection limits for DINP and DIDP were 1.74 mg/kg and 1.55 mg/kg respectively. This SPE-GC method is sensitive, accurate and suitable for the analysis of phthalate environmental hormones in textiles.

  20. CO{sub 2} Capture from Flue Gas Using Solid Molecular Basket Sorbents

    SciTech Connect

    Fillerup, Eric; Zhang, Zhonghua; Peduzzi, Emanuela; Wang, Dongxiang; Guo, Jiahua; Ma, Xiaoliang; Wang, Xiaoxing; Song, Chunshan

    2012-08-31

    The objective of this project is to develop a new generation of solid, regenerable polymeric molecular basket sorbent (MBS) for more cost-efficient capture and separation of CO{sub 2} from flue gas of coal-fired power plants. The primary goal is to develop a cost-effective MBS sorbent with better thermal stability. To improve the cost-effectiveness of MBS, we have explored commercially available and inexpensive support to replace the more expensive mesoporous molecular sieves like MCM-41 and SBA- 15. In addition, we have developed some advanced sorbent materials with 3D pore structure such as hexagonal mesoporous silica (HMS) to improve the CO{sub 2} working capacity of MBS, which can also reduce the cost for the whole CO{sub 2} capture process. During the project duration, the concern regarding the desorption rate of MBS sorbents has been raised, because lower desorption rate increases the desorption time for complete regeneration of the sorbent which in turn leads to a lower working capacity if the regeneration time is limited. Thus, the improvement in the thermal stability of MBS became a vital task for later part of this project. The improvement in the thermal stability was performed via increasing the polymer density either using higher molecular weight PEI or PEI cross-linking with an organic compound. Moreover, we have used the computational approach to estimate the interaction of CO{sub 2} with different MBSs for the fundamental understanding of CO{sub 2} sorption, which may benefit the development, design and modification of the sorbents and the process.

  1. Thermostability of Sm2(FeGa)17Cy prepared by gas-solid reaction (GSR)

    NASA Astrophysics Data System (ADS)

    Cao, L.; Handstein, A.; Gebel, B.; Schäfer, R.; Müller, K.-H.

    1997-04-01

    The gas-solid-reaction (GSR) was used to introduce interstitial carbon atoms into Sm2Fe17-xGax compounds with x=0, 0.5, 1, and 2. For this process, powders made from homogenized ingots were annealed at 500 °C under methane for different times. The thermostability increases for small amounts of Ga and the investigation shows that Sm2Fe16.5Ga0.5Cy is stable up to 750 °C. In the case of Sm2Fe15Ga2Cy carburized for 6 h (y=2.0) and 18 h (y=2.2), the x-ray diffraction patterns show the Th2Zn17-type structure only. After annealing at 800 °C for 20 min the 6 h carburized sample shows a small amount of α-Fe and other phases and there is a large Fe content after annealing at 850 °C. For an 18 h carburized sample, less Fe and no other phases have be seen after annealing at 800 °C, i.e., the material is nearly single phase. The result that longer carburization times stabilize the Th2Zn17-type structure could also be manifested by Kerr microscopy. A comparison with mechanically alloyed Sm2Fe15Ga2C2 powders prepared with Sm excess shows that those are very stable up to 900 °C. The density of fine-grained Sm2Fe17-xGaxCy could be increased by hot pressing, but the degree of compaction and the phase purity very sensitively depend on the Ga content.

  2. Laser-induced carbon plasma emission spectroscopic measurements on solid targets and in gas-phase optical breakdown

    SciTech Connect

    Nemes, Laszlo; Keszler, Anna M.; Hornkohl, James O.; Parigger, Christian

    2005-06-20

    We report measurements of time- and spatially averaged spontaneous-emission spectra following laser-induced breakdown on a solid graphite/ambient gas interface and on solid graphite in vacuum, and also emission spectra from gas-phase optical breakdown in allene C3H4 and helium, and in CO2 and helium mixtures. These emission spectra were dominated by CII (singly ionized carbon), CIII (doubly ionized carbon), hydrogen Balmer beta (H{sub b}eta), and Swan C2 band features. Using the local thermodynamic equilibrium and thin plasma assumptions, we derived electron number density and electron temperature estimates. The former was in the 1016 cm{sup -3} range, while the latter was found to be near 20000 K. In addition, the vibration-rotation temperature of the Swan bands of the C2 radical was determined to be between 4500 and 7000 K, using an exact theoretical model for simulating diatomic emission spectra. This temperature range is probably caused by the spatial inhomogeneity of the laser-induced plasma plume. Differences are pointed out in the role of ambient CO2 in a solid graphite target and in gas-phase breakdown plasma.

  3. Gas-solid flows - 1986; Proceedings of the Fourth Fluid Mechanics, Plasma Dynamics, and Lasers Conference, Atlanta, GA, May 11-14, 1986

    NASA Astrophysics Data System (ADS)

    Jurewicz, J. T.

    Papers are presented on deposition and resuspension of gas-borne particles in recirculating turbulent flows, particle dispersion in decaying isotropic homogeneous turbulence, turbulent dispersion of droplets for air flow in a pipe, a comparison between Lagrangian and Eulerian model approaches to turbulent particle dispersion, and the effect of turbulent electrohydrodynamics on electrostatic precipitator efficiency. Also considered are errors due to turbidity in particle sizing using laser Doppler velocimetry, particle motion in a fluidically oscillating jet, high pressure steam/water jet measurements using a portable particle sizing laser Doppler system, the effect of particle shape on pressure drop in a turbulent gas/solid suspension, and the experimental study of gas solid flows in pneumatic conveying. Other topics include entropy production and pressure loss in gas-solid flows, a computational study of turbulent gas-particle flow in a Venturi, a numerical analysis of confined recirculating gas-solid turbulent flows, nozzle and free jet flows of gas particle mixtures, and particle separation in pulsed airflow. Papers are also presented on sampling of solid particles in clouds, particle motion near the inlet of a sampling probe, the effects of slot injection on blade erosion in direct coal-fueled gas turbines, bed diameter effects and incipient slugging in gas fluidized beds, and sedimentation of air fluidized fine graphite particles by methanol vapor.

  4. Performance of a zerovalent iron reactive barrier for the treatment of arsenic in groundwater: Part 2. Geochemical modeling and solid phase studies

    SciTech Connect

    Beak, Douglas G.; Wilkin, Richard T.

    2009-06-12

    Arsenic uptake processes were evaluated in a zerovalent iron reactive barrier installed at a lead smelting facility using geochemical modeling, solid-phase analysis, and X-ray absorption spectroscopy techniques. Aqueous speciation of arsenic is expected to play a key role in directing arsenic uptake processes. Geochemical modeling reveals contrasting pH-dependencies for As(III) and As(V) precipitation. At the moderately alkaline pH conditions typically encountered in zerovalent iron reactive barriers, As(III) is unlikely to precipitate as an oxide or a sulfide phase. Conversely, increasing pH is expected to drive precipitation of metal arsenates including ferrous arsenate. Bacterially mediated sulfate reduction plays an important role in field installations of granular iron. Neoformed iron sulfides provide surfaces for adsorption of oxyanion and thioarsenic species of As(III) and As(V) and are expected to provide enhanced arsenic removal capacity. X-ray absorption near edge structure (XANES) spectra indicate that arsenic is sequestered in the solid phase as both As(III) and As(V) in coordination environments with O and S. Arsenic removal in the PRB probably results from several pathways, including adsorption to iron oxide and iron sulfide surfaces, and possible precipitation of ferrous arsenate. Corrosion of granular iron appears to result in some As(III) oxidation to As(V) as the proportion of As(V) to As(III) in the solid phase is greater compared to influent groundwater. As(0) was not detected in the PRB materials. These results are broadly comparable to laboratory based studies of arsenic removal by zerovalent iron, but additional complexity is revealed in the field environment, which is largely due to the influence of subsurface microbiota.

  5. A Reversible Planar Solid Oxide Fuel-Fed Electrolysis Cell and Solid Oxide Fuel Cell for Hydrogen and Electricity Production Operating on Natural Gas/Biomass Fuels

    SciTech Connect

    Tao, Greg, G.

    2007-03-31

    A solid oxide fuel-assisted electrolysis technique was developed to co-generate hydrogen and electricity directly from a fuel at a reduced cost of electricity. Solid oxide fuel-assisted electrolysis cells (SOFECs), which were comprised of 8YSZ electrolytes sandwiched between thick anode supports and thin cathodes, were constructed and experimentally evaluated at various operation conditions on lab-level button cells with 2 cm2 per-cell active areas as well as on bench-scale stacks with 30 cm2 and 100 cm2 per-cell active areas. To reduce the concentration overpotentials, pore former systems were developed and engineered to optimize the microstructure and morphology of the Ni+8YSZ-based anodes. Chemically stable cathode materials, which possess good electronic and ionic conductivity and exhibit good electrocatalytic properties in both oxidizing and reducing gas atmospheres, were developed and materials properties were investigated. In order to increase the specific hydrogen production rate and thereby reduce the system volume and capital cost for commercial applications, a hybrid system that integrates the technologies of the SOFEC and the solid-oxide fuel cell (SOFC), was developed and successfully demonstrated at a 1kW scale, co-generating hydrogen and electricity directly from chemical fuels.

  6. Evaluation Of Landfill Gas Decay Constant For Municipal Solid Waste Landfills Operated As Bioreactors

    EPA Science Inventory

    Prediction of the rate of gas production from bioreactor landfills is important to optimize energy recovery and to estimate greenhouse gas emissions. Landfill gas (LFG) composition and flow rate were monitored for four years for a conventional and two bioreactor landfill landfil...

  7. Gas-phase chemical reactivity of CFC-114 and potential replacements. Part 4, Reactivity of c-C{sub 4}F{sub 8} with F{sub 2} and UF{sub 6}

    SciTech Connect

    Trowbridge, L.D.; Angel, E.C.

    1992-07-01

    The DOE gaseous diffusion plant complex makes extensive use of CFC-114 as a primary coolant. As this material is on the Montreal Protocol list of materials scheduled for production curtailment, a substitute must be found. In addition to physical cooling properties, the gaseous diffusion application imposes the unique requirement of chemical inertness to fluorinating agents. A series of studies has therefore been undertaken to evaluate the gas-phase chemical reactivity of potential alternate coolants. This report examines the reactivity of perfluorocyclobutane (C-C{sub 4}F{sub 8}) with UF{sub 6} and F{sub 2} at selected reference conditions (approximately 10 Torr partial pressure of each reactant at 150{degrees}C). At the reference conditions, a very slight degree of reactivity was observed with F{sub 2}, but much less than the observed reactivity of the reference coolant, CFC-114. No reaction was observed with UF{sub 6}. A limited number of experiments was conducted at higher temperature, providing a first estimate of the rate of increase of reaction rate with increased temperature.

  8. 40 CFR Appendix A to Subpart Pppp... - Determination of Weight Volatile Matter Content and Weight Solids Content of Reactive Adhesives

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... react during the adhesive curing reaction, and, as a result, do not volatilize. The monomers become integral parts of the cured adhesive through chemical reaction. At least 70 weight percent of the system... solids. If left uncovered, as in a Method 24 (ASTM D2369) test, the reaction is inhibited by the...

  9. 40 CFR Appendix A to Subpart Pppp... - Determination of Weight Volatile Matter Content and Weight Solids Content of Reactive Adhesives

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... react during the adhesive curing reaction, and, as a result, do not volatilize. The monomers become integral parts of the cured adhesive through chemical reaction. At least 70 weight percent of the system... solids. If left uncovered, as in a Method 24 (ASTM D2369) test, the reaction is inhibited by the...

  10. Land, irrigation water, greenhouse gas, and reactive nitrogen burdens of meat, eggs, and dairy production in the United States

    PubMed Central

    Eshel, Gidon; Shepon, Alon; Makov, Tamar; Milo, Ron

    2014-01-01

    Livestock production impacts air and water quality, ocean health, and greenhouse gas (GHG) emissions on regional to global scales and it is the largest use of land globally. Quantifying the environmental impacts of the various livestock categories, mostly arising from feed production, is thus a grand challenge of sustainability science. Here, we quantify land, irrigation water, and reactive nitrogen (Nr) impacts due to feed production, and recast published full life cycle GHG emission estimates, for each of the major animal-based categories in the US diet. Our calculations reveal that the environmental costs per consumed calorie of dairy, poultry, pork, and eggs are mutually comparable (to within a factor of 2), but strikingly lower than the impacts of beef. Beef production requires 28, 11, 5, and 6 times more land, irrigation water, GHG, and Nr, respectively, than the average of the other livestock categories. Preliminary analysis of three staple plant foods shows two- to sixfold lower land, GHG, and Nr requirements than those of the nonbeef animal-derived calories, whereas irrigation requirements are comparable. Our analysis is based on the best data currently available, but follow-up studies are necessary to improve parameter estimates and fill remaining knowledge gaps. Data imperfections notwithstanding, the key conclusion—that beef production demands about 1 order of magnitude more resources than alternative livestock categories—is robust under existing uncertainties. The study thus elucidates the multiple environmental benefits of potential, easy-to-implement dietary changes, and highlights the uniquely high resource demands of beef. PMID:25049416

  11. Development of modified flyash as a permeable reactive barrier medium for a former manufactured gas plant site, Northern Ireland

    NASA Astrophysics Data System (ADS)

    Doherty, R.; Phillips, D. H.; McGeough, K. L.; Walsh, K. P.; Kalin, R. M.

    2006-05-01

    A sequential biological permeable reactive barrier (PRB) was determined to be the best option for remediating groundwater that has become contaminated with a wide range of organic contaminants (i.e., benzene, toluene, ethylbenzene, xylene and polyaromatic hydrocarbons), heavy metals (i.e., lead and arsenic), and cyanide at a former manufactured gas plant after 150 years of operation in Portadown, Northern Ireland. The objective of this study was to develop a modified flyash that could be used in the initial cell within a sequential biological PRB to filter complex contaminated groundwater containing ammonium. Flyash modified with lime (CaOH) and alum was subjected to a series of batch tests which investigated the modified cation exchange capacity (CEC) and rate of removal of anions and cations from the solution. These tests showed that a high flyash composition medium (80%) could remove 8.65 mol of ammonium contaminant for every kilogram of medium. The modified CEC procedure ruled out the possibility of cation exchange as the major removal mechanism. The medium could also adsorb anions as well as cations (i.e., Pb and Cr), but not with the same capacity. The initial mechanism for Pb and Cr removal is probably precipitation. This is followed by sorption, which is possibly the only mechanism for the removal of dichromate anions. Scanning electron microscopic analysis revealed very small (<1 μm) cubic highly crystalline precipitates on the flyash, although this new crystalline zeolite growth did not occur rapidly enough to enable productive zeolite formation. Surface area measurements showed that biofilm growth on the medium could be a major factor in the comparative reduction of surface area between real and synthetic contaminant groundwaters. The modified flyash was found to be a highly sorptive granular material that did not inhibit microbiological activity, however, leaching tests revealed that the medium would fail as a long-term barrier material.

  12. Method and apparatus for measuring the gas permeability of a solid sample

    DOEpatents

    Carstens, D.H.W.

    1984-01-27

    The disclosure is directed to an apparatus and method for measuring the permeability of a gas in a sample. The gas is allowed to reach a steady flow rate through the sample. A measurable amount of the gas is collected during a given time period and then delivered to a sensitive quadrupole. The quadrupole signal, adjusted for background, is proportional to the amount of gas collected during the time period. The quadrupole can be calibrated with a standard helium leak. The gas can be deuterium and the sample can be polyvinyl alcohol.

  13. Effects of Gas-Phase Radiation and Detailed Kinetics on the Burning and Extinction of a Solid Fuel

    NASA Technical Reports Server (NTRS)

    Rhatigan, Jennifer L.

    2001-01-01

    This is the first attempt to analyze both radiation and detailed kinetics on the burning and extinction of a solid fuel in a stagnation-point diffusion flame. We present a detailed and comparatively accurate computational model of a solid fuel flame along with a quantitative study of the kinetics mechanism, radiation interactions, and the extinction limits of the flame. A detailed kinetics model for the burning of solid trioxane (a trimer of formaldehyde) is coupled with a narrowband radiation model, with carbon dioxide, carbon monoxide, and water vapor as the gas-phase participating media. The solution of the solid trioxane diffusion flame over the flammable regime is presented in some detail, as this is the first solution of a heterogeneous trioxane flame. We identify high-temperature and low-temperature reaction paths for the heterogeneous trioxane flame. We then compare the adiabatic solution to solutions that include Surface radiation only and gas-phase and surface radiation using a black surface model. The analysis includes discussion of detailed flame chemistry over the flammable regime and, in particular, at the low stretch extinction limit. We emphasize the low stretch regime of the radiatively participating flame, since this is the region representative of microgravity flames. When only surface radiation is included, two extinction limits exist (the blow-off limit, and the low stretch radiative limit), and the burning rate and maximum flame temperatures are lower, as expected. With the inclusion of surface and gas-phase radiation, results show that, while flame temperatures are lower, the burning rate of the trioxane diffusion flame may actually increase at low stretch rate due to radiative feedback from the flame to the surface.

  14. The COSmIC/THS experiment: gas and solid phase studies of Titan aerosol simulants produced at cold temperature

    NASA Astrophysics Data System (ADS)

    Sciamma-OBrien, E. M.; Upton, K.; Beauchamp, J. L.; Salama, F.

    2013-12-01

    In Titan's atmosphere, a complex chemistry between N2 and CH4 occurs at temperatures lower than 200K and leads to the production of heavy molecules and subsequently solid aerosols that form the haze surrounding Titan. The Titan Haze Simulation (THS) experiment has been developed at the NASA Ames COSmIC facility to study Titan's atmospheric chemistry at low temperature, and in particular to study the chemical pathways that link the simple molecules resulting from the first steps of the N2-CH4 chemistry to benzene, and to PAHs and nitrogen-containing PAHs (PANHs), potential precursors to Titan's solid aerosols. In the COSmIC/THS, the chemistry is simulated by plasma in the stream of a supersonic expansion. With this unique design, the gas is jet-cooled to Titan-like temperature (~150K) before inducing the chemistry by plasma, and remains at low temperature in the plasma discharge (~200K measured by optical emission spectroscopy). Different N2-CH4-based gas mixtures can be injected in the plasma, with or without the addition of trace elements present on Titan. Both the gas phase and solid phase products resulting from the plasma-induced chemistry can be monitored and analyzed using a combination of complementary in situ and ex situ diagnostics: Cavity Ring Down Spectroscopy and Time-Of-Flight Mass Spectrometry (TOF-MS) for the gas phase; Direct Analysis in Real Time Mass Spectrometry (DART-MS), Gas Chromatography-Mass Spectrometry (GC-MS), Scanning Electron Microscopy (SEM), Raman spectroscopy, Nuclear Magnetic Resonance (NMR) and Infrared (IR) spectroscopy for the solid phase. Previous TOF-MS mass spectrometry analyses of the gas phase have demonstrated that the COSmIC/THS experiment can be used to study the first and intermediate steps as well as specific chemical pathways of Titan's atmospheric chemistry. The more complex chemistry, observed in the gas phase when adding trace elements to the initial N2-CH4 mixture, has been confirmed by an extensive study of the

  15. EPA Method 525.3 - Determination of Semivolatile Organic Chemicals in Drinking Water by Solid Phase Extraction and Capillary Column Gas Chromatography/Mass Spectrometry (GC/MS)

    EPA Science Inventory

    Method 525.3 is an analytical method that uses solid phase extraction (SPE) and gas chromatography/mass spectrometry (GC/MS) for the identification and quantitation of 125 selected semi-volatile organic chemicals in drinking water.

  16. Development of harsh environment nitrogen oxides solid-state gas sensors

    NASA Astrophysics Data System (ADS)

    Szabo, Nicholas Frank

    The goal of this dissertation was to study and develop high temperature solid-state sensors for combustion based gases. Specific attention was focused on NOx gases (NO and NO2) as they are of significant importance with respect to the environment and the health of living beings. This work is divided into four sections with the first chapter being an introduction into the effects of NOx gases and current regulations, followed by an introduction to the field of high temperature NOx sensors and finally where and why they will be needed in the future. Chapter 2 focuses on the development of a gas sensor for NOx capable of operation in harsh environments. The basis of the sensor is a mixed potential response at 500/600°C generated by exposure of gases to a platinum-yttria stabilized zirconia (Pt-YSZ) interface. Asymmetry between the two Pt electrodes on YSZ is generated by covering one of the electrodes with a zeolite, which helps to bring NO/NO2 towards equilibrium prior to the gases reaching the electrochemically active interface. Three sensor designs have been examined, including a planar design that is amenable to packaging for surviving automotive exhaust streams. Automotive tests indicated that the sensor is capable of detecting NO in engine exhausts. Chapter 2 concluded that it is difficult to measure NO or NO2 selectively especially when both gases are present at the same time thus we have developed a strategy in chapter 3 to measure the total NOx level (NO + NO2) in a background of O2 and N2 at high temperatures with minimal CO interference by combining a catalytic filter bed with the existing YSZ sensor device. The filter bed was composed of a Pt catalyst dispersed onto a zeolite Y support placed before a YSZ sensor having an air reference with a Cr2O3 or Pt sensing electrode. Chapter 4 explores the reasons for the difference in sensitivity of metal oxide electrodes, Cr2O3 and a mixed conducting perovskite La0.6Sr0.4Fe0.8Co0.2Ox, with the goal of ultimately

  17. The design of stationary and mobile solid oxide fuel cell-gas turbine systems

    NASA Astrophysics Data System (ADS)

    Winkler, Wolfgang; Lorenz, Hagen

    A general thermodynamic model has shown that combined fuel cell cycles may reach an electric-efficiency of more than 80%. This value is one of the targets of the Department of Energy (DOE) solid oxide fuel cell-gas turbine (SOFC-GT) program. The combination of a SOFC and GT connects the air flow of the heat engine and the cell cooling. The principle strategy in order to reach high electrical-efficiencies is to avoid a high excess air for the cell cooling and heat losses. Simple combined SOFC-GT cycles show an efficiency between 60 and 72%. The combination of the SOFC and the GT can be done by using an external cooling or by dividing the stack into multiple sub-stacks with a GT behind each sub-stack as the necessary heat sink. The heat exchangers (HEXs) of a system with an external cooling have the benefit of a pressurization on both sides and therefore, have a high heat exchange coefficient. The pressurization on both sides delivers a low stress to the HEX material. The combination of both principles leads to a reheat (RH)-SOFC-GT cycle that can be improved by a steam turbine (ST) cycle. The first results of a study of such a RH-SOFC-GT-ST cycle indicate that a cycle design with an efficiency of more than 80% is possible and confirm the predictions by the theoretical thermodynamic model mentioned above. The extremely short heat-up time of a thin tubular SOFC and the market entrance of the micro-turbines give the option of using these SOFC-GT designs for mobile applications. The possible use of hydrocarbons such as diesel oil is an important benefit of the SOFC. The micro-turbine and the SOFC stack will be matched depending on the start-up requirements of the mobile system. The minimization of the volume needed is a key issue. The efficiency of small GTs is lower than the efficiency of large GTs due to the influence of the leakage within the stages of GTs increasing with a decreasing size of the GT. Thus, the SOFC module pressure must be lower than in larger

  18. Headspace solid-phase microextraction-gas chromatography-mass spectrometry characterization of propolis volatile compounds.

    PubMed

    Pellati, Federica; Prencipe, Francesco Pio; Benvenuti, Stefania

    2013-10-01

    In this study, a novel and efficient method based on headspace solid-phase microextraction (HS-SPME), followed by gas chromatography-mass spectrometry (GC-MS), was developed for the analysis of propolis volatile compounds. The HS-SPME procedure, whose experimental parameters were properly optimized, was carried out using a 100 μm polydimethylsiloxane (PDMS) fiber. The GC-MS analyses were performed on a HP-5 MS cross-linked 5% diphenyl-95% dimethyl polysiloxane capillary column (30 m × 0.25 mm I.D., 1.00 μm film thickness), under programmed-temperature elution. Ninety-nine constituents were identified using this technique in the samples of raw propolis collected from different Italian regions. The main compounds detected include benzoic acid (0.87-30.13%) and its esters, such as benzyl benzoate (0.16-13.05%), benzyl salicylate (0.34-1.90%) and benzyl cinnamate (0.34-3.20%). Vanillin was detected in most of the samples analyzed in this study (0.07-5.44%). Another relevant class of volatile constituents is represented by sesquiterpene hydrocarbons, such as δ-cadinene (1.29-13.31%), γ-cadinene (1.36-8.85%) and α-muurolene (0.78-6.59%), and oxygenated sesquiterpenes, such as β-eudesmol (2.33-12.83%), T-cadinol (2.73-9.95%) and α-cadinol (4.84-9.74%). Regarding monoterpene hydrocarbons, they were found to be present at low level in the samples analyzed in this study, with the exception of one sample from Southern Italy, where α-pinene was the most abundant constituent (13.19%). The results obtained by HS-SPME-GC-MS were also compared with those of hydrodistillation (HD) coupled with GC-MS. The HS-SPME-GC-MS method developed in this study allowed us to determine the chemical fingerprint of propolis volatile constituents, thus providing a new and reliable tool for the complete characterization of this biologically active apiary product.

  19. Photophysics of Solid State Structures as Related To: a. Conformation and Morphology of Polyimide. B. Conductivity and Reactivity of Solid Oxide Electrolytes

    NASA Astrophysics Data System (ADS)

    Wachsman, Eric David

    1990-01-01

    The scope of this investigation is broad, from polymeric to ceramic materials, and for the latter includes both solid state kinetics and heterogeneous electrocatalysis. Macroscopic or bulk properties of these materials are investigated by application of physical chemistry on an atomic--molecular scale. Optical (uv-visible and fluorescence) and AC impedance spectroscopy are applied to the investigation of ordering and defect chemistry in these materials. In the study of polyimides we find that upon annealing at elevated temperature the fluorescence emission intensity increases with both temperature and time. This increase in emission intensity is ascribed to the formation of an ordered morphology and an increase in population of a coplanar conformation. These changes in morphology and conformation result in the formation of an intermolecular and an intramolecular charge transfer complex, respectively, which we propose are the fluorescing species in polyimides. Solid oxide electrolytes (SOE) conduct oxygen ions by a vacancy mechanism at elevated temperature. The fluorite structure of Bi_2O _3 has the highest ionic conductivity due to its high concentration of vacant oxygen sites and the resulting high degree of structural disorder. The conductivity of Bi_2O_3 phase stabilized with 20 mol% Er_2O _3 (ESB), was investigated using AC impedance spectroscopy. The conductivity of this material exhibits two activation energies due to an order-disorder transition of the oxygen sublattice at about 600 ^circC. Ordering of the oxygen sublattice upon annealing below the transition temperature results in a decrease in conductivity with time. This reversible conductivity aging phenomenon was found to follow first order kinetics at short times and diffusion limited growth at long times. An endotherm was observed, using differential thermal analysis, whose magnitude increased with the degree of ordering and the ordered structure was found to involve alignment of oxygen vacancies

  20. A gas-tight Cu K alpha x-ray transparent reaction chamber for high-temperature x-ray diffraction analyses of halide gas/solid reactions.

    PubMed

    Shian, Samuel; Sandhage, Kenneth H

    2009-11-01

    An externally heated, x-ray transparent reaction chamber has been developed to enable the dynamic high temperature x-ray diffraction (HTXRD) analysis of a gas/solid [TiF(4)(g)/SiO(2)(s)] reaction involving a halide gas reactant formed at elevated temperatures (up to 350 degrees C) from a condensed source (TiF(4) powder) sealed within the chamber. The reaction chamber possessed x-ray transparent windows comprised of a thin (13 microm) internal layer of Al foil and a thicker (125 microm) external Kapton film. After sealing the SiO(2) specimens (diatom frustules or Stober spheres) above TiF(4) powder within the reaction chamber, the chamber was heated to a temperature in the range of 160-350 degrees C to allow for internal generation of TiF(4)(g). The TiF(4)(g) underwent a metathetic reaction with the SiO(2) specimen to yield a TiOF(2)(s) product. HTXRD analysis, using Cu K alpha x rays passed through the Kapton/Al windows of the chamber, was used to track the extent of SiO(2) consumption and/or TiOF(2) formation with time. The Al foil inner layer of the windows protected the Kapton film from chemical attack by TiF(4)(g), whereas the thicker, more transparent Kapton film provided the mechanical strength needed to contain this gas. By selecting an appropriate combination of x-ray transparent materials to endow such composite windows with the required thermal, chemical, and mechanical performance, this inexpensive reaction chamber design may be applied to the HTXRD analyses of a variety of gas/solid reactions.

  1. [Determination of alkyl-phenols in textiles by in-tube capillary solid-phase extraction-gas chromatography].

    PubMed

    Zhang, Luohong; Du, Ting; Zhong, Jiayu

    2015-10-01

    An in-tube capillary solid-phase extraction (SPE) -gas chromatography (GC) method was developed for confirmation and quantitative determination of octylphenol (OP) and nonylphenol (NP) in textiles. To make the in-tube capillary SPE column, the best SPE cartridge was chosen from four kinds of SPE cartridges. The adsorbent in the cartridge was used as the filling material to make the in-tube capillary SPE column. The nature, volume used, flow rate and adsorption capacity of the eluent were compared. Finally, the in-tube capillary solid-phase extraction was combined with gas chromatography to detect the alkyl phenols (APs). Abselut NEXUS extraction cartridge was chosen as the best solid phase extractant. The optimal in-tube capillary SPE extraction conditions were as follows: 1.2 μL methanol and 1.2 μL ultra-pure water for activating the extraction column, 1.2 μL methanol for eluting, 0.4 μL/min for solution loading. The method showed a good linear relationship in the low concentration range, and the enrichment ratios for the APs were about 100 times. The detection limits of octylphenol and nonylphenol were 3.7 μg/L and 4.5 μg/L, respectively. The recoveries of octylphenol were 85.6%-98.2%, and those of nonylphenol were 83.8%-95.7%. The experimental results demonstrated that the method is simple, rapid, and useful for detecting APs in textiles.

  2. Gas/solid carbon branching ratios in surface-mediated reactions and the incorporation of carbonaceous material into planetesimals

    NASA Astrophysics Data System (ADS)

    Nuth, Joseph A.; Johnson, Natasha M.; Ferguson, Frank T.; Carayon, Alicia

    2016-07-01

    We report the ratio of the initial carbon available as CO that forms gas-phase compounds compared to the fraction that deposits as a carbonaceous solid (the gas/solid branching ratio) as a function of time and temperature for iron, magnetite, and amorphous iron silicate smoke catalysts during surface-mediated reactions in an excess of hydrogen and in the presence of N2. This fraction varies from more than 99% for an amorphous iron silicate smoke at 673 K to less than 40% for a magnetite catalyst at 873 K. The CO not converted into solids primarily forms methane, ethane, water, and CO2, as well as a very wide range of organic molecules at very low concentration. Carbon deposits do not form continuous coatings on the catalytic surfaces, but instead form extremely high surface area per unit volume "filamentous" structures. While these structures will likely form more slowly but over much longer times in protostellar nebulae than in our experiments due to the much lower partial pressure of CO, such fluffy coatings on the surfaces of chondrules or calcium aluminum inclusions could promote grain-grain sticking during low-velocity collisions.

  3. C-Reactive Protein Is an Important Biomarker for Prognosis Tumor Recurrence and Treatment Response in Adult Solid Tumors: A Systematic Review

    PubMed Central

    Shrotriya, Shiva; Walsh, Declan; Bennani-Baiti, Nabila; Thomas, Shirley; Lorton, Cliona

    2015-01-01

    Purpose A systematic literature review was done to determine the relationship between elevated CRP and prognosis in people with solid tumors. C-reactive protein (CRP) is a serum acute phase reactant and a well-established inflammatory marker. We also examined the role of CRP to predict treatment response and tumor recurrence. Methods MeSH (Medical Subject Heading) terms were used to search multiple electronic databases (PubMed, EMBASE, Web of Science, SCOPUS, EBM-Cochrane). Two independent reviewers selected research papers. We also included a quality Assessment (QA) score. Reports with QA scores <50% were excluded. PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) methodology was utilized for this review (S1 PRISMA Checklist). Results 271 articles were identified for final review. There were 45% prospective studies and 52% retrospective. 264 had intermediate QA score (≥50% but <80%); Seven were adequate (80% -100%); A high CRP was predictive of prognosis in 90% (245/271) of studies—80% of the 245 studies by multivariate analysis, 20% by univariate analysis. Many (52%) of the articles were about gastrointestinal malignancies (GI) or kidney malignancies. A high CRP was prognostic in 90% (127 of 141) of the reports in those groups of tumors. CRP was also prognostic in most reports in other solid tumors primary sites. Conclusions A high CRP was associated with higher mortality in 90% of reports in people with solid tumors primary sites. This was particularly notable in GI malignancies and kidney malignancies. In other solid tumors (lung, pancreas, hepatocellular cancer, and bladder) an elevated CRP also predicted prognosis. In addition there is also evidence to support the use of CRP to help decide treatment response and identify tumor recurrence. Better designed large scale studies should be conducted to examine these issues more comprehensively. PMID:26717416

  4. Thermodynamic analysis of a combined gas turbine power plant with a solid oxide fuel cell for marine applications

    NASA Astrophysics Data System (ADS)

    Welaya, Yousri M. A.; Mosleh, M.; Ammar, Nader R.

    2013-12-01

    Strong restrictions on emissions from marine power plants (particularly SOx, NOx) will probably be adopted in the near future. In this paper, a combined solid oxide fuel cell (SOFC) and gas turbine fuelled by natural gas is proposed as an attractive option to limit the environmental impact of the marine sector. It includes a study of a heatrecovery system for 18 MW SOFC fuelled by natural gas, to provide the electric power demand onboard commercial vessels. Feasible heat-recovery systems are investigated, taking into account different operating conditions of the combined system. Two types of SOFC are considered, tubular and planar SOFCs, operated with either natural gas or hydrogen fuels. This paper includes a detailed thermodynamic analysis for the combined system. Mass and energy balances are performed, not only for the whole plant but also for each individual component, in order to evaluate the thermal efficiency of the combined cycle. In addition, the effect of using natural gas as a fuel on the fuel cell voltage and performance is investigated. It is found that a high overall efficiency approaching 70% may be achieved with an optimum configuration using SOFC system under pressure. The hybrid system would also reduce emissions, fuel consumption, and improve the total system efficiency.

  5. Efficiency analysis of a hydrogen-fueled solid oxide fuel cell system with anode off-gas recirculation

    NASA Astrophysics Data System (ADS)

    Peters, Roland; Deja, Robert; Engelbracht, Maximilian; Frank, Matthias; Nguyen, Van Nhu; Blum, Ludger; Stolten, Detlef

    2016-10-01

    This study analyzes different hydrogen-fueled solid oxide fuel cell (SOFC) system layouts. It begins with a simple system layout without any anode off-gas recirculation, continues with a configuration equipped with off-gas recirculation, including steam condensation and then considers a layout with a dead-end anode off-gas loop. Operational parameters such as stack fuel utilization, as well as the recirculation rate, are modified, with the aim of achieving the highest efficiency values. Drawing on experiments and the accumulated experience of the SOFC group at the Forschungszentrum Jülich, a set of operational parameters were defined and applied to the simulations. It was found that anode off-gas recirculation, including steam condensation, improves electrical efficiency by up to 11.9 percentage-points compared to a layout without recirculation of the same stack fuel utilization. A system layout with a dead-end anode off-gas loop was also found to be capable of reaching electrical efficiencies of more than 61%.

  6. Solid Phase Peat and Dissolved Organic Matter Composition and Reactivity as a Function of Surface Vegetation in Northern Minnesota Peatlands

    NASA Astrophysics Data System (ADS)

    Tfaily, M. M.; Hamdan, R.; Jaffe, R.; Cawley, K.; Cooper, W. T.; Chanton, J.

    2012-12-01

    Peatlands are unusual in greenhouse scenarios because on the one hand they sequester carbon from the atmosphere as peat, while on the other hand they re-emit it in large quantities as methane. Little is known, however, about the chemical processes that link solid phase peat and dissolved organic matter (DOM) within its porewaters. In this work we have applied FT-IR and 13C NMR spectroscopy to characterize the solid phase peat at varying depths from different sites at the Marcell Experimental Forest (MEF) where the Oak Ridge National Laboratory (ORNL) has begun the Spruce and Peatland Response Under Climatic and Environmental Change (SPRUCE) project. Parallel Factor analyzed Excitation/Emission Matrix fluorescence spectroscopy (PARAFAC-EEMS) and ultrahigh resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS) were used to characterize the molecular composition of peat porewaters. Analyses of the solid phase and the porewater suggested the presence of different zones of varying degrees of humification in the peat core. FT-IR and NMR data indicated that the relative abundances of alipahtics and aromatics increased with depth to about 100 cm, then remained relatively constant. This increase was accompanied with a concomitant decrease in the relative abundance of carbohydrates. FT-ICR MS data showed a large abundance of compounds with high O/C ratios at the surface (acrotelm) that tend to disappear with depth (catotelm), with accumulation of refractory aliphatic compounds characterized by low O/C and high H/C ratios.

  7. Air Pollution Monitoring and Use of Nanotechnology Based Solid State Gas Sensors in Greater Cairo Area, Egypt

    NASA Astrophysics Data System (ADS)

    Ramadan, A. B. A.

    Air pollution is a serious problem in thickly populated and industrialized areas in Egypt, especially in greater Cairo area. Economic growth and industrialization are proceeding at a rapid pace, accompanied by increasing emissions of air polluting sources. Furthermore, though the variety and quantities of polluting sources have increased dramatically, the development of a suitable method for monitoring the pollution causing sources has not followed at the same pace. Environmental impacts of air pollutants have impact on public health, vegetation, material deterioration etc. To prevent or minimize the damage caused by atmospheric pollution, suitable monitoring systems are urgently needed that can rapidly and reliably detect and quantify polluting sources for monitoring by regulating authorities in order to prevent further deterioration of the current pollution levels. Consequently, it is important that the current real-time air quality monitoring system, controlled by the Egyptian Environmental Affairs Agency (EEAA), should be adapted or extended to aid in alleviating this problem. Nanotechnology has been applied to several industrial and domestic fields, for example, applications for gas monitoring systems, gas leak detectors in factories, fire and toxic gas detectors, ventilation control, breath alcohol detectors, and the like. Here we report an application example of studying air quality monitoring based on nanotechnology `solid state gas sensors'. So as to carry out air pollution monitoring over an extensive area, a combination of ground measurements through inexpensive sensors and wireless GIS will be used for this purpose. This portable device, comprising solid state gas sensors integrated to a Personal Digital Assistant (PDA) linked through Bluetooth communication tools and Global Positioning System (GPS), will allow rapid dissemination of information on pollution levels at multiple sites simultaneously.

  8. Characterization of three agave species by gas chromatography and solid-phase microextraction-gas chromatography-mass spectrometry.

    PubMed

    Peña-Alvarez, Araceli; Díaz, Laura; Medina, Alejandra; Labastida, Carmen; Capella, Santiago; Vera, Luz Elena

    2004-02-20

    Steam distillation (SD) extraction-solid-phase microextraction coupled to GC-MS was developed for the determination of terpenes and Bligh-Dyer extraction-derivatization coupled with GC for the determination of fatty acids such as ethyl esters were used. It was found that the three different Agave species have the same profile of fatty acids; the quantity of these compounds is different in each Agave variety. On the other hand, different terpenes were identified in the three Agave plants studied: nine in A. salmiana, eight in A. angustifolia and 32 in A. tequilana Weber var. azul.

  9. A DMPA Langmuir monolayer study: from gas to solid phase. An atomistic description by molecular dynamics Simulation.

    PubMed

    Giner-Casares, J J; Camacho, L; Martín-Romero, M T; Cascales, J J López

    2008-03-04

    In this work, a DMPA Langmuir monolayer at the air/water interface was studied by molecular dynamics simulations. Thus, an atomistic picture of a Langmuir monolayer was drawn from its expanded gas phase to its final solid condensed one. In this sense, some properties of monolayers that were traditionally poorly or even not reproduced in computer simulations, such as lipid domain formation or pressure-area per lipid isotherm, were properly reproduced in this work. Thus, the physical laws that control the lipid domain formation in the gas phase and the structure of lipid monolayers from the gas to solid condensed phase were studied. Thanks to the atomistic information provided by the molecular dynamics simulations, we were able to add valuable information to the experimental description of these processes and to access experimental data related to the lipid monolayers in their expanded phase, which is difficult or inaccessible to study by experimental techniques. In this sense, properties such as lipids head hydration and lipid structure were studied.

  10. Interpretation of tracer surface diffusion experiments on UO2 — roles of gas and solid transport processes

    SciTech Connect

    Olander, D. R.

    1981-02-01

    In this paper, the spreading of a tracer from an enriched needle source which contacts the surface of a depleted pellet sink is analyzed rigorously. It is shown that volume diffusion in both the needle and the pellet need to be considered because only by this process is sufficient radioactivity accumulated for measurement after the anneal. Parasitic gas phase processes are of two types: evaporative loss of solid if a flowing gas is used, or molecular diffusion from enriched portions of the surface to depleted zones if the couple is in a closed vessel with a stagnant gas. A complete numerical solution including surface diffusion, solid diffusion, evaporative loss and contact resistance is applied to the UO2 tracer study of Marlowe and Kazanoff at 1915°C. Based upon UO2 evaporation experiments, the analysis shows that the evaporative loss effect is not important in these experiments. Finally, the UO2 surface diffusion coefficient deduced from analysis of these data is 0.2 ± 0.1 cm2/s at 1915°C, which is 104 times larger than that predicted by extrapolation of values obtained by mass transfer techniques.

  11. Correlation between chemical reactivity and the Hammett acidity function in amorphous solids using inversion of sucrose as a model reaction.

    PubMed

    Chatterjee, Koustuv; Shalaev, Evgenyi Y; Suryanarayanan, Raj; Govindarajan, Ramprakash

    2008-01-01

    The goal was to evaluate the effects of acidity, expressed as the Hammett acidity function, on chemical reactivity in freeze-dried materials (lyophiles). Dextran-sucrose-citrate and polyvinyl pyrrolidone (PVP)-sucrose-citrate aqueous solutions, adjusted to pH values of 2.6, 2.8, and 3.0 were freeze dried, and characterized by X-ray powder diffractometry, DSC, isothermal microcalorimetry, and Karl Fischer titrimetry. Lyophiles were also prepared from identical solutions but containing bromophenol blue (BB). Diffuse reflectance-visible spectroscopy was used to measure the extent of BB protonation from which the Hammett acidity functions were determined. The stability studies were performed at 60 degrees C. All the freeze-dried samples were observed to be X-ray amorphous with <0.15% w/w water content. The T(g) of dextran lyophiles were approximately 20 degrees C higher than that of PVP lyophiles whereas enthalpy relaxation rates at 60 degrees C were similar. The Hammett acidity functions were significantly lower (i.e., higher acidity) for dextran systems (<2.2-2.6) when compared with PVP systems (3.3-3.9). The rate of sucrose inversion was significantly (an order of magnitude) higher in dextran lyophiles. This study showed that in amorphous matrices with comparable water content and structural relaxation times, chemical reactivity could be significantly different depending on the matrix "acidity".

  12. ReaxFF Reactive Force-Field Modeling of the Triple-Phase Boundary in a Solid Oxide Fuel Cell.

    PubMed

    Merinov, Boris V; Mueller, Jonathan E; van Duin, Adri C T; An, Qi; Goddard, William A

    2014-11-20

    In our study, the Ni/YSZ ReaxFF reactive force field was developed by combining the YSZ and Ni/C/H descriptions. ReaxFF reactive molecular dynamics (RMD) were applied to model chemical reactions, diffusion, and other physicochemical processes at the fuel/Ni/YSZ interface. The ReaxFF RMD simulations were performed on the H2/Ni/YSZ and C4H10/Ni/YSZ triple-phase boundary (TPB) systems at 1250 and 2000 K, respectively. The simulations indicate amorphization of the Ni surface, partial decohesion (delamination) at the interface, and coking, which have indeed all been observed experimentally. They also allowed us to derive the mechanism of the butane conversion at the Ni/YSZ interface. Many steps of this mechanism are similar to the pyrolysis of butane. The products obtained in our simulations are the same as those in experiment, which indicates that the developed ReaxFF potential properly describes complex physicochemical processes, such as the oxide-ion diffusion, fuel conversion, water formation reaction, coking, and delamination, occurring at the TPB and can be recommended for further computational studies of the fuel/electrode/electrolyte interfaces in a SOFC.

  13. Comparison of enzymatic reactivity of corn stover solids prepared by dilute acid, AFEX™, and ionic liquid pretreatments

    PubMed Central

    2014-01-01

    Background Pretreatment is essential to realize high product yields from biological conversion of naturally recalcitrant cellulosic biomass, with thermochemical pretreatments often favored for cost and performance. In this study, enzymatic digestion of solids from dilute sulfuric acid (DA), ammonia fiber expansion (AFEX™), and ionic liquid (IL) thermochemical pretreatments of corn stover were followed over time for the same range of total enzyme protein loadings to provide comparative data on glucose and xylose yields of monomers and oligomers from the pretreated solids. The composition of pretreated solids and enzyme adsorption on each substrate were also measured to determine. The extent glucose release could be related to these features. Results Corn stover solids from pretreatment by DA, AFEX, and IL were enzymatically digested over a range of low to moderate loadings of commercial cellulase, xylanase, and pectinase enzyme mixtures, the proportions of which had been previously optimized for each pretreatment. Avicel® cellulose, regenerated amorphous cellulose (RAC), and beechwood xylan were also subjected to enzymatic hydrolysis as controls. Yields of glucose and xylose and their oligomers were followed for times up to 120 hours, and enzyme adsorption was measured. IL pretreated corn stover displayed the highest initial glucose yields at all enzyme loadings and the highest final yield for a low enzyme loading of 3 mg protein/g glucan in the raw material. However, increasing the enzyme loading to 12 mg/g glucan or more resulted in DA pretreated corn stover attaining the highest longer-term glucose yields. Hydrolyzate from AFEX pretreated corn stover had the highest proportion of xylooligomers, while IL produced the most glucooligomers. However, the amounts of both oligomers dropped with increasing enzyme loadings and hydrolysis times. IL pretreated corn stover had the highest enzyme adsorption capacity. Conclusions Initial hydrolysis yields were highest

  14. Chemical reactivity of polycyclic organic compounds adsorbed on coal fly ash and related solid surfaces. Progress report, May 1985-April 1986

    SciTech Connect

    Mamantov, G.; Wehry, E.L.

    1986-04-01

    The fundamental objectives of this research are to characterize and understand the photochemical and nonphotochemical reactivity of polycyclic aromatic hydrocarbons (PAHs) and their derivatives as adsorbates on the surface of coal fly ash and related particulate solids. Specific efforts undertaken and results obtained during this period are summarized with detailed discussions presented in the form of Appendices. Results are tabulated from a thorough examination of the photochemistry of pyrene, benzo(a)pyrene (BaP), anthracene, phenanthrene, and benz(a)anthracene (BaA) as adsorbates on eight coal stack ashes. A procedure was developed to separate coal ashes into carbon and iron contents. Attempts to measure heats of absorption of PAHs on various coal ashes were made. Pyrene nitration occurred only when NO/sub 2/ was contaminated with nitric acid.

  15. Solid-, solution-, and gas-state NMR monitoring of ¹³C-cellulose degradation in an anaerobic microbial ecosystem.

    PubMed

    Yamazawa, Akira; Iikura, Tomohiro; Shino, Amiu; Date, Yasuhiro; Kikuchi, Jun

    2013-07-29

    Anaerobic digestion of biomacromolecules in various microbial ecosystems is influenced by the variations in types, qualities, and quantities of chemical components. Nuclear magnetic resonance (NMR) spectroscopy is a powerful tool for characterizing the degradation of solids to gases in anaerobic digestion processes. Here we describe a characterization strategy using NMR spectroscopy for targeting the input solid insoluble biomass, catabolized soluble metabolites, and produced gases. ¹³C-labeled cellulose produced by Gluconacetobacter xylinus was added as a substrate to stirred tank reactors and gradually degraded for 120 h. The time-course variations in structural heterogeneity of cellulose catabolism were determined using solid-state NMR, and soluble metabolites produced by cellulose degradation were monitored using solution-state NMR. In particular, cooperative changes between the solid NMR signal and ¹³C-¹³C/¹³C-¹²C isotopomers in the microbial degradation of ¹³C-cellulose were revealed by a correlation heat map. The triple phase NMR measurements demonstrated that cellulose was anaerobically degraded, fermented, and converted to methane gas from organic acids such as acetic acid and butyric acid.

  16. Simultaneous particulates, NO sub x , SO sub x removal from flue gas by all solid-state electrochemical technology

    SciTech Connect

    Cook, W.J.; Cornell, L.P.; Keyvani, M.; Neyman, M.

    1989-07-21

    The objective is to develop an all solid-state electrochemical technology to control SO{sub x}, NO{sub x}, and particulate emissions from coal combustion flue gases. It is based on a solid-state, electrochemical reactor which reduces NOx and SO{sub 2} to nitrogen, sulfur, and oxygen. The solid electrolyte is a high surface area ceramic oxide-ion conductor such as a stabilized zirconia or ceria. The cell electrodes may be of various electronically conductive materials such as porous, high surface area nickel, silver, or gold. Work was performed in two areas, electrocatalyst preparation and testing and particulate control tests. Transition metal oxide electrocatalysts were tested by applying the electrocatalyst along with gold electrodes to a stabilized ceria solid electrolyte disk and measuring the reduction of NO and SO{sub 2} in gas mixtures containing 0 to 4% oxygen while a voltage was applied to the disk. The high temperature particulate control test apparatus was installed and flyash tests were done. The efficiency of high temperature particulate filters was also tested. 2 refs., 10 figs.

  17. Application of electrical capacitance tomography for measurement of gas-solids flow characteristics in a pneumatic conveying system

    NASA Astrophysics Data System (ADS)

    Jaworski, Artur J.; Dyakowski, Tomasz

    2001-08-01

    Transient three-dimensional multiphase flows are a characteristic feature of many industrial processes. The experimental observations and measurements of such flows are extremely difficult, and industrial process tomography has been developed over the last decade into a reliable method for investigating these complex phenomena. Gas-solids flows, such as those in pneumatic conveying systems, exhibit many interesting features and these can be successfully investigated by using electrical capacitance tomography. This paper discusses the current state of the art in this field, advantages and limitations of the technique and required future developments. Various levels of visualization and processing of tomographic data obtained in a pilot-plant-scale pneumatic conveying system are presented. A case study outlining the principles of measuring the mass flow rate of solids in a vertical channel is shown.

  18. Pyrolysis-capillary gas chromatography-mass spectrometry for the determination of polyvinyl chloride traces in solid environmental samples.

    PubMed

    Tienpont, B; David, F; Vanwalleghem, F; Sandra, P

    2001-03-16

    A novel method based on pyrolysis-capillary gas chromatography-mass spectrometry (CGC-MS) was developed for the quantitative analysis of polyvinylchloride (PVC) in solid environmental samples like sludge and dust. The samples are extracted and the extract is fractionated by solid-phase extraction (SPE). Possibly interfering biological and frequently occuring synthetic polymers are removed by this clean-up. The final extract is analyzed by pyrolysis-CGC-MS. Selective detection of PVC is performed by using specific markers in the pyrogram. Quantitation is done on naphthalene. Good linearity was obtained in a range from 0.5 to 100 microg applied to the pyrolyser. The limit of quantitation (LOQ) in sludge and dust samples is 10 mg/kg dry mass. A correlation between PVC and phthalates was made for sewage sludge samples.

  19. Simultaneous particulates, NO sub x , SO sub x removal from flue gas by all solid-state electrochemical technology

    SciTech Connect

    Cook, W.J.; Hossain, M.S.; Neyman, M. ); Gordon, A.Z. )

    1988-04-20

    The IGR emission control technology controls SOx, NOx, and particulate emissions from coal combustion flue gases. It is based on a solid-state, flow-through, electrochemical reactor which reduces NOx and SO{sub 2} to nitrogen, sulfur, and oxygen. The cell electrolyte is a solid electrolyte, normally a high surface area ceramic oxide-ion conductor. Three tasks were active during this quarter, Task (1) Development of 10 Cubic Feet/Min High Surface Area Electrochemical Reactors, Task (2) Procurement, Construction and Debugging of the Electrochemical Reactors and Particulate Removal System and Task (3) Electrocatalyst Preparation and Screening Studies. Task (3) is the screening of electrocatalysts for high oxygen overpotential and low SO{sub 2} and NO{sub x} overpotential. Electrochemical measurements were made with oxide ion conducting ceramic disks in nitric oxide and sulfur dioxide gas mixtures. 2 refs., 10 figs.

  20. Simultaneous particulates NO sub x , SO sub x removal from flue gas by all solid-state electrochemical technology

    SciTech Connect

    Cook, W.J.; Hossain, M.S.; Neyman, M. ); Gordon, A.Z. )

    1988-03-17

    The IGR emission control technology controls SOx, NOx, and particulate emissions from coal combustion flue gases. It is based on a solid-state, flow-through, electrochemical reactor which reduces NOx and SO{sub 2} to nitrogen, sulfur, and oxygen. The cell electrolyte is a solid electrolyte, normally a high surface area ceramic oxide-ion conductor. Two tasks were active during this quarter, Task (1) Development of 10 Cubic Feet/Min High Surface Area Electrochemical Reactors and Task (2) Electrocatalyst Preparation and Screening Studies. Task (2) is the screening of electrocatalysts for high oxygen overpotential and low SO{sub 2} and NO{sub x} overpotential. Electrochemical measurements were made with oxide ion conducting ceramic disks in nitric oxide and sulfur dioxide gas mixtures. 1 ref., 9 figs.

  1. Open-source MFIX-DEM software for gas-solids flows: Part 1 - Verification studies

    SciTech Connect

    Garg, Rahul; Galvin, Janine; Li, Tingwen; Pannala, Sreekanth

    2012-04-01

    With rapid advancements in computer hardware, it is now possible to perform large simulations of granular flows using the Discrete Element Method (DEM). As a result, solids are increasingly treated in a discrete Lagrangian fashion in the gas–solids flow community. In this paper, the open-source MFIX-DEM software is described that can be used for simulating the gas–solids flow using an Eulerian reference frame for the continuum fluid and a Lagrangian discrete framework (Discrete Element Method) for the particles. This method is referred to as the continuum discrete method (CDM) to clearly make a distinction between the ambiguity of using a Lagrangian or Eulerian reference for either continuum or discrete formulations. This freely available CDM code for gas–solids flows can accelerate the research in computational gas–solids flows and establish a baseline that can lead to better closures for the continuum modeling (or traditionally referred to as two fluid model) of gas–solids flows. In this paper, a series of verification cases is employed which tests the different aspects of the code in a systematic fashion by exploring specific physics in gas–solids flows before exercising the fully coupled solution on simple canonical problems. It is critical to have an extensively verified code as the physics is complex with highly-nonlinear coupling, and it is difficult to ascertain the accuracy of the results without rigorous verification. These series of verification tests set the stage not only for rigorous validation studies (performed in part II of this paper) but also serve as a procedure for testing any new developments that couple continuum and discrete formulations for gas–solids flows.

  2. Open Source MFIX-DEM Software for Gas-Solids Flows: Part 1 - Verification Studies

    SciTech Connect

    Garg, Rahul; Galvin, Janine; Li, Tingwen; Pannala, Sreekanth

    2012-04-01

    With rapid advancements in computer hardware, it is now possible to perform large simulations of granular flows using the Discrete Element Method (DEM). As a result, solids are increasingly treated in a discrete Lagrangian fashion in the gas–solids flow community. In this paper, the open-source MFIX-DEM software is described that can be used for simulating the gas–solids flow using an Eulerian reference frame for the continuum fluid and a Lagrangian discrete framework (Discrete Element Method) for the particles. This method is referred to as the continuum discrete method (CDM) to clearly make a distinction between the ambiguity of using a Lagrangian or Eulerian reference for either continuum or discrete formulations. This freely available CDM code for gas–solids flows can accelerate the research in computational gas–solids flows and establish a baseline that can lead to better closures for the continuum modeling (or traditionally referred to as two fluid model) of gas–solids flows. In this paper, a series of verification cases is employed which tests the different aspects of the code in a systematic fashion by exploring specific physics in gas–solids flows before exercising the fully coupled solution on simple canonical problems. It is critical to have an extensively verified code as the physics is complex with highly-nonlinear coupling, and it is difficult to ascertain the accuracy of the results without rigorous verification. These series of verification tests set the stage not only for rigorous validation studies (performed in part II of this paper) but also serve as a procedure for testing any new developments that couple continuum and discrete formulations for gas–solids flows.

  3. A Test Study of 50% Lightning Impulse Breakdown Voltage on Rod-Plane Gap with Two-Phase Mixture of Gas and Solid Particles

    NASA Astrophysics Data System (ADS)

    He, Zhenghao; Xu, Huaili; Bai, Jing; Yu, Fusheng; Hu, Feng; Li, Jin

    2007-12-01

    A test study on 50% lightning impulse breakdown voltage in two-phase mixture of gas and solid particles has been carried out in a specially designed discharge cabinet. A mechanical sieve is set up for sifting different solid particles into the discharge space uniformly. The lightning impulse voltage according with international electro-technical commission (IEC) standard is applied to the electrodes inside the discharge cabinet by the rule of up-down method in a total of 40 times. The results showed that the 50% lightning impulse breakdown voltage in two-phase mixture of gas and solid particles has its own features and is much different from that in air.

  4. Greenhouse gas emissions and reactive nitrogen releases from rice production with simultaneous incorporation of wheat straw and nitrogen fertilizer

    NASA Astrophysics Data System (ADS)

    Xia, Longlong; Xia, Yongqiu; Ma, Shutan; Wang, Jinyang; Wang, Shuwei; Zhou, Wei; Yan, Xiaoyuan

    2016-08-01

    Impacts of simultaneous inputs of crop straw and nitrogen (N) fertilizer on greenhouse gas (GHG) emissions and N losses from rice production are not well understood. A 2-year field experiment was established in a rice-wheat cropping system in the Taihu Lake region (TLR) of China to evaluate the GHG intensity (GHGI) as well as reactive N intensity (NrI) of rice production with inputs of wheat straw and N fertilizer. The field experiment included five treatments of different N fertilization rates for rice production: 0 (RN0), 120 (RN120), 180 (RN180), 240 (RN240), and 300 kg N ha-1 (RN300, traditional N application rate in the TLR). Wheat straws were fully incorporated into soil before rice transplantation. The meta-analytic technique was employed to evaluate various Nr losses. Results showed that the response of rice yield to N rate successfully fitted a quadratic model, while N fertilization promoted Nr discharges exponentially (nitrous oxide emission, N leaching, and runoff) or linearly (ammonia volatilization). The GHGI of rice production ranged from 1.20 (RN240) to 1.61 kg CO2 equivalent (CO2 eq) kg-1 (RN0), while NrI varied from 2.14 (RN0) to 10.92 g N kg-1 (RN300). Methane (CH4) emission dominated the GHGI with a proportion of 70.2-88.6 % due to direct straw incorporation, while ammonia (NH3) volatilization dominated the NrI with proportion of 53.5-57.4 %. Damage costs to environment incurred by GHG and Nr releases from current rice production (RN300) accounted for 8.8 and 4.9 % of farmers' incomes, respectively. Cutting N application rate from 300 (traditional N rate) to 240 kg N ha-1 could improve rice yield and nitrogen use efficiency by 2.14 and 10.30 %, respectively, while simultaneously reducing GHGI by 13 %, NrI by 23 %, and total environmental costs by 16 %. Moreover, the reduction of 60 kg N ha-1 improved farmers' income by CNY 639 ha-1, which would provide them with an incentive to change the current N application rate. Our study suggests that GHG

  5. Hybrid field-assisted solid-liquid-solid dispersive extraction for the determination of organochlorine pesticides in tobacco with gas chromatography.

    PubMed

    Zhou, Ting; Xiao, Xiaohua; Li, Gongke

    2012-01-03

    A novel one-step sample preparation technique termed hybrid field-assisted solid-liquid-solid dispersive extraction (HF-SLSDE) was developed in this study. A simple glass system equipped with a condenser was designed as an extraction vessel. The HF-SLSDE technique was a three-phase dispersive extraction approach. Target analytes were extracted from the sample into the extraction solvent enhanced by the hybrid field. Meanwhile, the interfering components were adsorbed by dispersing sorbent. No cleanup step preceded chromatographic analysis. The efficiency of the HF-SLSDE approach was demonstrated in the determination of organochlorine pesticide (OCP) residues in tobacco with a gas chromatography-electron capture detector (GC-ECD). Various operation conditions were studied systematically. Low detection limits (0.3-1.6 μg/kg) and low quantification limits (1.0-4.5 μg/kg) were achieved under the optimized conditions. The recoveries of OCPs ranged from 70.2% to 118.2%, with relative standard deviations of <9.6%, except for the lowest fortification level. Because of the effect of the hybrid field, HF-SLSDE showed significant predominance compared with other extraction techniques. The dispersing sorbent with good cleanup ability used in this study was also found to be a microwave absorption medium, which could heat the nonpolar extraction solvent under microwave irradiation. Different microstructures of tobacco samples before and after extractions demonstrated the mechanism of HF-SLSDE was based on an explosion at the cell level. According to the results, HF-SLSDE was proved to be a simple and effective sample preparation method for the analysis of pesticide residues in solid samples and could potentially be extended to other nonpolar target analytes in a complex matrix.

  6. Optimisation of specialty malt volatile analysis by headspace solid-phase microextraction in combination with gas chromatography and mass spectrometry.

    PubMed

    Vandecan, Sem M G; Saison, Daan; Schouppe, Nina; Delvaux, Filip; Delvaux, Freddy R

    2010-06-25

    The objective of this study was to develop a technique for analysing 14 flavour components, relevant for specialty malts. Therefore, a method was developed for the analysis of these components in dry ground malt using headspace solid-phase microextraction coupled with gas chromatography and mass spectrometry. A procedure was optimised for the optimal amount of sample, fibre selection, extraction temperature and extraction time. Afterwards, the method was calibrated and validated by the quantification of the specialty malt flavour components in a colour, a caramel and a roasted malt.

  7. Determination of cocaine and cocaethylene in plasma by solid-phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Alvarez, Iván; Bermejo, Ana María; Tabernero, María Jesús; Fernández, Purificación; López, Patricia

    2007-01-01

    The present paper describes a method for the simultaneous determination of cocaine and cocaethylene in plasma. It was based in the extraction of the analytes by solid-phase microextraction (SPME), and gas chromatography-mass spectrometry (GC-MS) was used to identify and quantify the analytes in selected ion monitoring (SIM) mode. The method showed to be very simple, rapid and sensitive. The method was validated for the two compounds, including linearity (range 25-1000 ng/mL) and the main precision parameters. It was applied to ten plasma samples from cocaine and alcohol users, obtaining positive results in all cases.

  8. Multiresidue method for the gas chromatographic determination of pesticides in honey after solid-phase extraction cleanup.

    PubMed

    Jansson, C

    2000-01-01

    A new multiresidue method is described for the determination of pesticides in honey. The method involves dissolution of the honey in a methanol-water mixture, followed by solid-phase extraction cleanup and gas chromatographic determination. Twenty-six pesticides used on flowering field crops, on flowering fruit and vegetables, or as acaricides to control Varroa jacobsoni in beehives are determined by the method. Recoveries from honey, spiked at 0.02-1.6 mg/kg, ranged from 85 to 127% with a relative standard deviation (RSD) of 2-16%, except for the RSD of 27% for captan at 0.05 mg/kg.

  9. Detection of perfluorocarbons in blood by headspace solid-phase microextraction combined with gas chromatography/mass spectrometry.

    PubMed

    Mathurin, J C; de Ceaurriz, J; Audran, M; Krafft, M P

    2001-11-01

    A new method of detection of perfluorocarbon molecules (PFCs) in blood sample has been established. After an extraction and pre-concentration step performed by headspace solid-phase microextraction (HS-SPME), the PFCs are detected by gas chromatography-mass spectrometry (GC/MS) with an ion trap mass spectrometer in MS and MS/MS modes. The influence of different parameters on the SPME process is discussed. The limit of detection and the linearity of the procedure have been determined for two PFCs.

  10. Room temperature gas-solid reaction of titanium on glass surfaces forming a very low resistivity layer

    NASA Astrophysics Data System (ADS)

    Solís, Hugo; Clark, Neville; Azofeifa, Daniel; Avendano, E.

    2016-09-01

    Titanium films were deposited on quartz, glass, polyamide and PET substrates in a high vacuum system at room temperature and their electrical resistance monitored in vacuo as a function of thickness. These measurements indicate that a low electrical resistance layer is formed in a gas-solid reaction during the condensation of the initial layers of Ti on glass and quartz substrates. Layers begin to show relative low electrical resistance at around 21 nm for glass and 9nm for quartz. Samples deposited on polyamide and PET do not show this low resistance feature.

  11. Opaque Mineral Assemblages at Chondrule Boundaries in the Vigarano CV Chondrite: Evidence for Gas-Solid Reactions Following Chondrule Formation

    NASA Technical Reports Server (NTRS)

    Lauretta, Dante S.

    2004-01-01

    Recent studies of opaque minerals in primitive ordinary chondrites suggest that metal grains exposed at chondrule boundaries were corroded when volatile elements recondensed after the transient heating event responsible for chondrule formation. Metal grains at chondrule boundaries in the Bishunpur (LL3.1) chondrite are rimmed by troilite and fayalite. If these layers formed by gas solid reaction, then the composition of the corrosion products can provide information on the chondrule formation environment. Given the broad similarities among chondrules from different chondrite groups, similar scale layers should occur on chondrules in other primitive meteorite groups. Here I report on metal grains at chondrule boundaries in Vigarano (CV3).

  12. CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES: Gas-Fluid and Fluid-Solid Phase Instability for Restricted Primitive Model

    NASA Astrophysics Data System (ADS)

    Guo, Yuan-Yuan; Chen, Xiao-Song

    2009-08-01

    By considering the fluctuation of grand potential Ω around equilibrium with respect to small one-particle density fluctuations δρα(vec r), the phase instability of restricted primitive model (RPM) of ionic systems is investigated. We use the integral equation theory to calculate the direct correlation functions in the reference hypernetted chain approximation and obtain the spinodal line of RPM. Our analysis explicitly indicates that the gas-fluid phase instability is induced by k = 0 fluctuation mode, while the fluid-solid phase instability is related to k ≠ 0 fluctuation modes. The spinodal line is qualitatively consistent with the result of computer simulations by others.

  13. Quantitative analysis of solids in motion by transient infrared emission spectroscopy using hot-gas jet excitation

    SciTech Connect

    Jones, R.W.; McClelland, J.F. )

    1990-10-01

    Quantitative compositional analysis of optically thick solids in motion is demonstrated by using transient infrared emission spectroscopy (TIRES). TIRES greatly reduces the self-absorption that normally degrades conventional emission spectra so that they closely resemble blackbody spectra. Quantitative compositional analyses of poly((methyl methacrylate)-co-(butyl methacrylate)) and poly(ethylene-co-(vinyl acetate)) with standard errors of prediction under 1% were achieved with only a few seconds of data acquisition using principal component regression. Use of a hot-gas jet in place of a laser in the TIRES technique allows study of materials that do not absorb strongly at common laser wavelengths while reducing cost and complexity.

  14. Comparison of the Reactivity of the Three Distonic Isomers of the Pyridine Radical Cation Toward Tetrahydrofuran in Solution and in the Gas Phase

    PubMed Central

    Widjaja, Fanny; Jin, Zhicheng; Nash, John J.; Kenttämaa, Hilkka I.

    2013-01-01

    The reactivity of the three distonic isomers of the pyridine radical cation toward tetrahydrofuran is compared in solution and in the gas phase. In solution, the distonic ions were generated by UV photolysis at 300 nm from iodo-precursors in acidic 50:50 tetrahydrofuran/water solutions. In the gas phase, the ions were generated by collisionally activated dissociation (CAD) of protonated iodo-precursors in an FT-ICR mass spectrometer, as described in the literature. The same major reaction, hydrogen atom abstraction, was observed in solution and in the gas phase. Attempts to cleave the iodine atom from the 2-iodopyridinium cation in the gas phase and in solution yielded the 2-pyridyl cation in addition to the desired 2-dehydropyridinium cation. In the gas phase, this ion was ejected prior to the examination of the desired ion’s chemical properties. This was not possible in solution. This study suggests that solvation effects are not significant for radical reactions of charged radicals. On the other hand, the even-electron ion studied, the 2-pyridyl cation, shows substantial solvation effects. For example, in solution, the 2-pyridyl cation forms a stable adduct with tetrahydrofuran, whereas in the gas phase, only addition/elimination reactions were observed. PMID:23345033

  15. A Gas-Surface Interaction Model based on Accelerated Reactive Molecular Dynamics for Hypersonic Conditions including Thermal Conduction

    DTIC Science & Technology

    2012-02-28

    of the arc-jet flow field and predicted convective heat flux. When compared with the measured heat flux, the discrepancy is attributed to...published an AIAA conference paper in 2007 entitled, “Molecular mechanisms of gas surface interactions in hypersonic flow ” [24]. In this paper...Hypersonic Gas -Phase and Gas -Surface Reactions”, proceedings of the 27th International Symposium on Rarefied Gas Dynamics, July 2010, Monterey, CA

  16. Solid phase micro extraction - A new technique coupled with gas chromatograph for chloroethene analysis from aqueous samples

    SciTech Connect

    Xu, N.; Sewell, G.W.

    1996-10-01

    Once the chloroethenes (tetrachloroethene and trichloroethene) contamination occurs in the subsurface environment, they tend to retain and form a Pollution plum in the aquifer because of their recalcitrance to aerobic oxidation. Currently, the most promising bioremediation method for chlorinated compounds is through anaerobic reductive biotransformation, in which each chlorine is replaced by a hydrogen. To study the biodegradation process, it is essential to monitor tetrachloroethene and its degradation daughter products frequently. An analytical method has been modified for chloroethene analysis by gas chromatography. Solid Phase Micro Extraction technique has been used to extract aqueous sample onto a fiber and then to desorb the sample directly into a gas chromatograph injection port. The total run time is less than 17 minutes.

  17. Anode gas recirculation for improving the performance and cost of a 5-kW solid oxide fuel cell system

    NASA Astrophysics Data System (ADS)

    Torii, Ryohei; Tachikawa, Yuya; Sasaki, Kazunari; Ito, Kohei

    2016-09-01

    Solid oxide fuel cells (SOFCs) have the potential to efficiently convert chemical energy into electricity and heat and are expected to be implemented in stationary combined heat and power (CHP) systems. This paper presents the heat balance analysis for a 5-kW medium-sized integrated SOFC system and the evaluation of the effect of anode gas recirculation on the system performance. The risk of carbon deposition on an SOFC anode due to anode gas recirculation is also assessed using the C-H-O diagram obtained from thermodynamic equilibrium calculations. These results suggest that a higher recirculation ratio increases net fuel utilization and improves the electrical efficiency of the SOFC system. Furthermore, cost simulation of the SOFC system and comparison with the cost of electricity supply by a power grid indicates that the capital cost is sufficiently low to popularize the SOFC system in terms of the total cost over one decade.

  18. Analysis of a landfill gas to energy system at the municipal solid waste landfill in Gaziantep, Turkey.

    PubMed

    Tercan, Safak Hengirmen; Cabalar, Ali Firat; Yaman, Gokhan

    2015-08-01

    This paper presents an analysis of the electricity generation from municipal solid waste (MSW), via landfill gas valorization technology, at the landfill of Gaziantep City, Turkey. Rapid increase in population, and industrial developments, throughout the world including Turkey results in larger amount of waste materials generated, increased need for energy, and adverse affects on the environment and human health. Turkey plans to produce 1/3 of its electricity demand using renewable energy sources by the year of 2023. It is recommended to use each year around 25 million tonnes of the MSW generated nationwide for a renewable energy supply. In this study, a concise summary of current status of electricity generation from a MSW landfill gas plant (via biogas harnessing) located in Gaziantep City was analyzed as a case study.

  19. Durability Prediction of Solid Oxide Fuel Cell Anode Material under Thermo-Mechanical and Fuel Gas Contaminants Effects

    SciTech Connect

    Iqbal, Gulfam; Guo, Hua; Kang , Bruce S.; Marina, Olga A.

    2011-01-10

    Solid Oxide Fuel Cells (SOFCs) operate under harsh environments, which cause deterioration of anode material properties and service life. In addition to electrochemical performance, structural integrity of the SOFC anode is essential for successful long-term operation. The SOFC anode is subjected to stresses at high temperature, thermal/redox cycles, and fuel gas contaminants effects during long-term operation. These mechanisms can alter the anode microstructure and affect its electrochemical and structural properties. In this research, anode material degradation mechanisms are briefly reviewed and an anode material durability model is developed and implemented in finite element analysis. The model takes into account thermo-mechanical and fuel gas contaminants degradation mechanisms for prediction of long-term structural integrity of the SOFC anode. The proposed model is validated experimentally using a NexTech ProbostatTM SOFC button cell test apparatus integrated with a Sagnac optical setup for simultaneously measuring electrochemical performance and in-situ anode surface deformation.

  20. Fabrication of Nd:Lu2.7Gd0.3Al5O12 transparent ceramics by solid-state reactive sintering

    NASA Astrophysics Data System (ADS)

    Ma, Peng; Xie, Tengfei; Wu, Lexiang; Chen, Haohong; Kou, Huamin; Shi, Yun; Pan, Yubai; Li, Jiang

    2017-04-01

    Transparent 1.0 at% Nd:Lu2.7Gd0.3Al5O12 (Nd:LuGdAG) ceramics were fabricated by the solid-state reactive sintering method using commercial powders as starting materials. The powders were mixed in ethanol with tetraethoxysilane (TEOS) and MgO, dried and pressed. The compacts were vacuum-sintered from 1725 °C to 1800 °C for observing the microstructure and the optical transmittance of Nd:Lu2.7Gd0.3Al5O12 ceramics. The sample sintered at 1800 °C for 10 h has an almost dense and homogenous structure with the average grain size of 12.8 μm, whose in-line transmittance is about 70% at 1064 nm. The absorption and emission cross sections were calculated to be 1.0 × 10-20 cm2 and 1.23 × 10-18 cm2, respectively. It is proved that Nd:LuGdAG ceramics have the potential to be a new solid-state laser material.

  1. Effects of the electrical parameters and gas flow rate on the generation of reactive species in liquids exposed to atmospheric pressure plasma jets

    NASA Astrophysics Data System (ADS)

    Baek, Eun Jeong; Joh, Hea Min; Kim, Sun Ja; Chung, T. H.

    2016-07-01

    In this work, an atmospheric pressure plasma jet was fabricated and studied for plasma-liquid interactions. The plasma jet consists of a quartz-covered pin electrode and outer quartz tube with a tapered nozzle. Using the current-voltage (I-V) and optical emission characteristics of the plasma jet, the plasma density and the speed of the plume were investigated. The optical emission spectra clearly indicated the excited NO, O, OH, N2, and N2+ in the plasma plumes. Then the plasma jets were applied to the deionized water. We investigated the effects of the operating parameters such as applied voltage, pulse frequency, and gas flow rate on the generation of reactive species in the gas and liquid phases. The densities of reactive species including OH radicals were obtained at the plasma-liquid surface and inside the plasma-treated liquids using ultraviolet absorption spectroscopy and chemical probe method. The nitrite concentration was detected by Griess assay. The data are very suggestive that there is a strong correlation among the production of reactive oxygen and nitrogen species (RONS) in the plasmas and liquids.

  2. NOx abatement in natural-gas-combustion exhaust gases by solid-state electrochemical technology. Topical report, September 1986-May 1987

    SciTech Connect

    Neyman, M.; Siwajek, L.; Cook, W.J.; Gordon, A.Z.

    1987-11-01

    Solid-state electrochemical technology, embodied in the IGR deNOx process is used to reduce nitrogen oxides (NOx) to nitrogen and oxygen, and thereby control NOx emissions from natural gas powered engines. The IGR deNOx process is based on solid-state, flow-through, high-surface area, oxygen-ion-conductive ceramic electrolytes. Ceramic reactor elements made of fully stabilized zirconia (FSZ) (yttria-stabilized) were coated with porous silver electrodes, and tested with NO gas mixtures including a mixture containing CO/sub 2/, H/sub 2/O and N/sub 2/ using both electrical and gas-chromatographic analysis.

  3. MODULAR APPLICATION OF COMPUTATIONAL MODELS OF INHALED REACTIVE GAS DOSIMETRY FOR RISK ASSESSMENT OF RESPIRATORY TRACT TOXICITY: CHLORINE

    EPA Science Inventory

    Inhaled reactive gases typically cause respiratory tract toxicity with a prominent proximal to distal lesion pattern. This pattern is largely driven by airflow and interspecies differences between rodents and humans result from factors such as airway architecture, ventilation ra...

  4. A novel solid state fermentation coupled with gas stripping enhancing the sweet sorghum stalk conversion performance for bioethanol

    PubMed Central

    2014-01-01

    Background Bioethanol production from biomass is becoming a hot topic internationally. Traditional static solid state fermentation (TS-SSF) for bioethanol production is similar to the traditional method of intermittent operation. The main problems of its large-scale intensive production are the low efficiency of mass and heat transfer and the high ethanol inhibition effect. In order to achieve continuous production and high conversion efficiency, gas stripping solid state fermentation (GS-SSF) for bioethanol production from sweet sorghum stalk (SSS) was systematically investigated in the present study. Results TS-SSF and GS-SSF were conducted and evaluated based on different SSS particle thicknesses under identical conditions. The ethanol yield reached 22.7 g/100 g dry SSS during GS-SSF, which was obviously higher than that during TS-SSF. The optimal initial gas stripping time, gas stripping temperature, fermentation time, and particle thickness of GS-SSF were 10 h, 35°C, 28 h, and 0.15 cm, respectively, and the corresponding ethanol stripping efficiency was 77.5%. The ethanol yield apparently increased by 30% with the particle thickness decreasing from 0.4 cm to 0.05 cm during GS-SSF. Meanwhile, the ethanol yield increased by 6% to 10% during GS-SSF compared with that during TS-SSF under the same particle thickness. The results revealed that gas stripping removed the ethanol inhibition effect and improved the mass and heat transfer efficiency, and hence strongly enhanced the solid state fermentation (SSF) performance of SSS. GS-SSF also eliminated the need for separate reactors and further simplified the bioethanol production process from SSS. As a result, a continuous conversion process of SSS and online separation of bioethanol were achieved by GS-SSF. Conclusions SSF coupled with gas stripping meet the requirements of high yield and efficient industrial bioethanol production. It should be a novel bioconversion process for bioethanol production from SSS

  5. Reactivity of oxygen radical anions bound to scandia nanoparticles in the gas phase: C-H bond activation.

    PubMed

    Tian, Li-Hua; Meng, Jing-Heng; Wu, Xiao-Nan; Zhao, Yan-Xia; Ding, Xun-Lei; He, Sheng-Gui; Ma, Tong-Mei

    2014-01-20

    The activation of C-H bonds in alkanes is currently a hot research topic in chemistry. The atomic oxygen radical anion (O(-·)) is an important species in C-H activation. The mechanistic details of C-H activation by O(-·) radicals can be well understood by studying the reactions between O(-·) containing transition metal oxide clusters and alkanes. Here the reactivity of scandium oxide cluster anions toward n-butane was studied by using a high-resolution time-of-flight mass spectrometer coupled with a fast flow reactor. Hydrogen atom abstraction (HAA) from n-butane by (Sc2O3)(N)O(-) (N=1-18) clusters was observed. The reactivity of (Sc2O3)(N)O(-) (N=1-18) clusters is significantly sizedependent and the highest reactivity was observed for N=4 (Sc8O13(-)) and 12 (Sc24O37(-)). Larger (Sc2O3)(N)O(-) clusters generally have higher reactivity than the smaller ones. Density functional theory calculations were performed to interpret the reactivity of (Sc2O3)(N)O(-) (N=1-5) clusters, which were found to contain the O(-·) radicals as the active sites. The local charge environment around the O(-·) radicals was demonstrated to control the experimentally observed size-dependent reactivity. This work is among the first to report HAA reactivity of cluster anions with dimensions up to nanosize toward alkane molecules. The anionic O(-·) containing scandium oxide clusters are found to be more reactive than the corresponding cationic ones in the C-H bond activation.

  6. An improved external recycle reactor for determining gas-solid reaction kinetics

    NASA Technical Reports Server (NTRS)

    Miller, Irvin M.; Hoyt, Ronald F.

    1987-01-01

    These improvements in the recycle system effectively eliminate initial concentration variation by two modifications: (1) a vacuum line connection to the recycle loop which permits this loop to be evacuated and then filled with the test gas mixture to slightly above atmospheric pressure; and (2) a bypass line across the reactor which permits the reactor to be held under vacuum while the rest of the recycle loop is filled with test gas. A three-step procedure for bringing the feed gas mixture into contact with the catalyst at time zero is described.

  7. The organic matter of Comet Halley as inferred by joint gas phase and solid phase analyses

    NASA Astrophysics Data System (ADS)

    Krueger, F. R.; Korth, A.; Kissel, J.

    1991-04-01

    During encounters with Comet Halley, the experiment PICCA onboard Giotto measured the gas-phase organic ion composition of the coma, and the experiment PUMA onboard Vega-1 measured the dust composition. Joining both results gives a consistent picture of the parent organic matter from which dust and gas is produced: a complex unsaturated polycondensate, which splits during coma formation into the more refractory C=C,C-N-containing dust part and the more volatile C=C,C-O-containing gas part. The responsible exothermal chemical reactions, which are triggered by sunlight, may play a major role in the dynamics of coma formation.

  8. Asymptotic theory of two-phase gas-solid flow through a vertical tube at moderate pressure gradient

    NASA Astrophysics Data System (ADS)

    Sergeev, Y. A.; Zhurov, A. I.

    1997-02-01

    Based on the equations, constitutive relations and boundary conditions of the kinetic theory of colliding particles in a gas-solid suspension, the approximate theory of the steady, developed vertical flow of a gas-particulate mixture is developed for the case of moderate gas pressure gradient in a vertical tube. The basic equations and boundary conditions show a singular behaviour of the solution of the problem at the wall. The method of matched asymptotic expansions is applied to develop a boundary layer-type theory for the flow parameters of the particulate phase. The basic equations in the bulk flow are reduced to a system of two ordinary integrodifferential equations for the particle-phase concentration and mean kinetic energy of particle velocity fluctuations (particle-phase pseudotemperature). The distributions of the particle concentration and velocity are found in both the bulk and the boundary layer. The solutions shows the bifurcation of flow parameters, and an explicit criterion is derived to identify a range of the given macroscopic parameters corresponding to upward or downward particulate flow. The integrated parameters (total fluxes of the gas and particle phase) are calculated.

  9. Demonstration of a Highly Efficient Solid Oxide Fuel Cell Power System Using Adiabatic Steam Reforming and Anode Gas Recirculation

    SciTech Connect

    Powell, Michael R.; Meinhardt, Kerry D.; Sprenkle, Vincent L.; Chick, Lawrence A.; Mcvay, Gary L.

    2012-05-01

    Solid oxide fuel cells (SOFC) are currently being developed for a wide variety of applications because of their high efficiency at multiple power levels. Applications for SOFCs encompass a large range of power levels including 1-2 kW residential combined heat and power applications, 100-250 kW sized systems for distributed generation and grid extension, and MW-scale power plants utilizing coal. This paper reports on the development of a highly efficient, small-scale SOFC power system operating on methane. The system uses adiabatic steam reforming of methane and anode gas recirculation to achieve high net electrical efficiency. The anode exit gas is recirculated and all of the heat and water required for the endothermic reforming reaction are provided by the anode gas emerging from the SOFC stack. Although the single-pass fuel utilization is only about 55%, because of the anode gas recirculation the overall fuel utilization is up to 93%. The demonstrated system achieved gross power output of 1650 to 2150 watts with a maximum net LHV efficiency of 56.7% at 1720 watts. Overall system efficiency could be further improved to over 60% with use of properly sized blowers.

  10. Evaluation and Application of a Solid Adsorbent Method for Monitoring Exposure to Volatile Organic Compounds from Oil and Gas Operations.

    NASA Astrophysics Data System (ADS)

    Smith, K. R.; Helmig, D.; Thompson, C. R.; Wang, W.; Terrell, R. M.; Lewis, A. C.

    2014-12-01

    Residential communities are being increasingly impacted by emissions from oil and gas development and this has driven the need for simple, effective, and low-cost methods for air quality monitoring. Primary emissions from oil and gas production consist of volatile organic compounds (VOCs) ranging from the short chain alkanes and alkenes to aromatic and semi-volatile species; many of these are a concern from both an air quality and public health viewpoint, as they can lead to local ozone pollution and increased risk of cancer or respiratory illness. The fate of hydrocarbons once in the atmosphere is ultimately oxidation through to CO2 and water, adding to the greenhouse gas burden. Measurement techniques that are capable of identifying and quantifying the full range of primary emissions of concern are required to assess community exposure to air toxics and to better inform residents, as well as local and state legislators. Here, we present evaluation of a low-cost air monitoring technique using stainless steel diffusion cartridges containing multiple solid adsorbents. Over the course of a three-month period in summer of 2014, cartridges were deployed at five monitoring sites located around Boulder County in the Northern Colorado Front Range, and exposed to ambient air for periods of up to four days along with concurrent sampling using stainless steel SUMMA canisters. Samples collected with both methods were subsequently analyzed for VOCs by GC-FID and the results were compared to determine the accuracy and precision of the diffusion cartridge method. Results of this evaluation show that the diffusion cartridge method has the potential to be a simple and low-cost solution for widespread exposure monitoring in communities near oil and gas development regions. Such measurements may also provide supporting evidence on wider effects on greenhouse gas emissions from oil and gas development operations.

  11. Analysis of trace contaminants in hot gas streams using time-weighted average solid-phase microextraction: proof of concept.

    PubMed

    Woolcock, Patrick J; Koziel, Jacek A; Cai, Lingshuang; Johnston, Patrick A; Brown, Robert C

    2013-03-15

    Time-weighted average (TWA) passive sampling using solid-phase microextraction (SPME) and gas chromatography was investigated as a new method of collecting, identifying and quantifying contaminants in process gas streams. Unlike previous TWA-SPME techniques using the retracted fiber configuration (fiber within needle) to monitor ambient conditions or relatively stagnant gases, this method was developed for fast-moving process gas streams at temperatures approaching 300 °C. The goal was to develop a consistent and reliable method of analyzing low concentrations of contaminants in hot gas streams without performing time-consuming exhaustive extraction with a slipstream. This work in particular aims to quantify trace tar compounds found in a syngas stream generated from biomass gasification. This paper evaluates the concept of retracted SPME at high temperatures by testing the three essential requirements for TWA passive sampling: (1) zero-sink assumption, (2) consistent and reliable response by the sampling device to changing concentrations, and (3) equal concentrations in the bulk gas stream relative to the face of the fiber syringe opening. Results indicated the method can accurately predict gas stream concentrations at elevated temperatures. Evidence was also discovered to validate the existence of a second boundary layer within the fiber during the adsorption/absorption process. This limits the technique to operating within reasonable mass loadings and loading rates, established by appropriate sampling depths and times for concentrations of interest. A limit of quantification for the benzene model tar system was estimated at 0.02 g m(-3) (8 ppm) with a limit of detection of 0.5 mg m(-3) (200 ppb). Using the appropriate conditions, the technique was applied to a pilot-scale fluidized-bed gasifier to verify its feasibility. Results from this test were in good agreement with literature and prior pilot plant operation, indicating the new method can measure low

  12. Combining Solid-state and Solution-based Techniques: Synthesis and Reactivity of Chalcogenidoplumbates(II or IV).

    PubMed

    Thiele, Günther; Donsbach, Carsten; Nußbruch, Isabell; Dehnen, Stefanie

    2016-12-29

    The phases of "PbCh2" (Ch = Se, Te) are obtained from solid-state syntheses (i.e., by the fusion of the elements under inert conditions in silica glass ampules). Reduction of such phases by elemental alkaline metals in amines affords crystalline chalcogenidoplumbate(II) salts comprised of [PbTe3](2)(-) or [Pb2Ch3](2)(-) anions, depending upon which sequestering agent for the cations is present: crown ethers, like 18-crown-6, or cryptands, like [2.2.2]crypt. Reactions of solutions of such anions with transition-metal compounds yield (poly-)chalcogenide anions or transition-metal chalcogenide clusters, including one with a µ-PbSe ligand (i.e., the heaviest-known CO homolog). In contrast, the solid-state synthesis of a phase of the nominal composition "K2PbSe2" by successive reactions of the elements and by the subsequent solvothermal treatment in amines yields the first non-oxide/halide inorganic lead(IV) compound: a salt of the ortho-selenidoplumbate(IV) anion [PbSe4](4)(-). This was unexpected due to the redox potentials of Pb(IV) and Se(-II). Such methods can further be applied to other elemental combinations, leading to the formation of solutions with binary [HgTe2](2)(-) or [BiSe3](3)(-) anions, or to large-scale syntheses of K2Hg2Se3 or K3BiSe3 via the solid-state route. All compounds are characterized by single-crystal X-ray diffraction and elemental analysis; solutions of plumbate salts can be investigated by (205)Pb and (77)Se or (127)Te NMR techniques. Quantum chemical calculations using density functional theory methods enable energy comparisons. They further allow for insights into the electronic configuration and thus, the bonding situation. Molecular Rh-containing Chevrel-type compounds were found to exhibit delocalized mixed valence, whereas similar telluridopalladate anions are electron-precise; the cluster with the µ-PbSe ligand is energetically favored over a hypothetical CO analog, in line with the unsuccessful attempt at its synthesis. The

  13. A new method for direct total OH reactivity measurements using a fast Gas Chromatographic Photo-Ionization Detector (GC-PID)

    NASA Astrophysics Data System (ADS)

    Nölscher, A. C.; Sinha, V.; Bockisch, S.; Klüpfel, T.; Williams, J.

    2012-04-01

    *160*400 mm), light (8 kg) and provides a good time resolution (50-60 sec). The method is able to operate in ambient conditions, requires no external carrier gas, and an internal battery provides power for ca. 12 hours which makes the instrument suitable for outdoor field campaigns. The GC-PID detection limit for pyrrole is 3 ppb, which is adequate for this application and total OH reactivity can be measured under optimum conditions down to 4 sec-1. The new set-up has been tested in parallel to previously validated PTR-MS measurements for CRM in laboratory experiments, a plant chamber, and boreal forest field studies. Advantages and drawbacks of the new technique are discussed. Although the polymerization of pyrrole on the detector window remains a weakness in the present version of the system, in general the GC-PID produces acceptable results. [1] Calpini et al, 1999, Analusis, 27, 328 [2] Kovacs and Brune. 2001, Journal of Atmospheric Chemistry, 39, 105-122 [3] V. Sinha et al, 2008, Atmos. Chem. Phys., 8, 2213-2227 [4] http://www.environics-iut.de/

  14. Solid State Gas Sensor Research in Germany – a Status Report

    PubMed Central

    Moos, Ralf; Sahner, Kathy; Fleischer, Maximilian; Guth, Ulrich; Barsan, Nicolae; Weimar, Udo

    2009-01-01

    This status report overviews activities of the German gas sensor research community. It highlights recent progress in the field of potentiometric, amperometric, conductometric, impedimetric, and field effect-based gas sensors. It is shown that besides step-by-step improvements of conventional principles, e.g. by the application of novel materials, novel principles turned out to enable new markets. In the field of mixed potential gas sensors, novel materials allow for selective detection of combustion exhaust components. The same goal can be reached by using zeolites for impedimetric gas sensors. Operando spectroscopy is a powerful tool to learn about the mechanisms in n-type and in p-type conductometric sensors and to design knowledge-based improved sensor devices. Novel deposition methods are applied to gain direct access to the material morphology as well as to obtain dense thick metal oxide films without high temperature steps. Since conductometric and impedimetric sensors have the disadvantage that a current has to pass the gas sensitive film, film morphology, electrode materials, and geometrical issues affect the sensor signal. Therefore, one tries to measure directly the Fermi level position either by measuring the gas-dependent Seebeck coefficient at high temperatures or at room temperature by applying a modified miniaturized Kelvin probe method, where surface adsorption-based work function changes drive the drain-source current of a field effect transistor. PMID:22408529

  15. Gas-Phase Reactions of Cationic Vanadium-Phosphorus Oxide Clusters with C2Hx (x=4, 6): A DFT-Based Analysis of Reactivity Patterns

    PubMed Central

    Dietl, Nicolas; Zhang, Xinhao; van der Linde, Christian; Beyer, Martin K; Schlangen, Maria; Schwarz, Helmut

    2013-01-01

    The reactivities of the adamantane-like heteronuclear vanadium-phosphorus oxygen cluster ions [VxP4−xO10].+ (x=0, 2–4) towards hydrocarbons strongly depend on the V/P ratio of the clusters. Possible mechanisms for the gas-phase reactions of these heteronuclear cations with ethene and ethane have been elucidated by means of DFT-based calculations; homolytic C–H bond activation constitutes the initial step, and for all systems the P–O. unit of the clusters serves as the reactive site. More complex oxidation processes, such as oxygen-atom transfer to, or oxidative dehydrogenation of the hydrocarbons require the presence of a vanadium atom to provide the electronic prerequisites which are necessary to bring about the 2e− reduction of the cationic clusters. PMID:23322620

  16. Technical bases for the use of CIF{sub 3} in the MSRE reactive gas removal project at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    Trowbridge, L.D.

    1997-06-01

    Nearly impermeable, non-volatile deposits in the Molten Salt Reactor Experiment (MSRE) off-gas piping are impeding the removal of reactive gases from that system. The deposits almost certainly consist of reduced uranium fluorides or of uranium oxyfluorides. Treatment with ClF{sub 3} is a non-intrusive method capable of chemically converting these compounds back to UF{sub 6}, which can then be removed as a gas. This report discusses the technical bases for the use of ClF{sub 3} treatments in this system. A variety of issues are examined, and where the necessary information exists or has been developed, the resolution discussed. The more important of these issues include the efficacy of ClF{sub 3} at deposit removal under the conditions imposed by the MSRE system, materials compatibility of ClF{sub 3} and its reaction products, and operational differences in the Reactive Gas Removal System imposed by the presence of ClF{sub 3} and its products.

  17. Direct gas-solid carbonation of serpentinite residues in the absence and presence of water vapor: a feasibility study for carbon dioxide sequestration.

    PubMed

    Veetil, Sanoopkumar Puthiya; Pasquier, Louis-César; Blais, Jean-François; Cecchi, Emmanuelle; Kentish, Sandra; Mercier, Guy

    2015-09-01

    Mineral carbonation of serpentinite mining residue offers an environmentally secure and permanent storage of carbon dioxide. The strategy of using readily available mining residue for the direct treatment of flue gas could improve the energy demand and economics of CO2 sequestration by avoiding the mineral extraction and separate CO2 capture steps. The present is a laboratory scale study to assess the possibility of CO2 fixation in serpentinite mining residues via direct gas-solid reaction. The degree of carbonation is measured both in the absence and presence of water vapor in a batch reactor. The gas used is a simulated gas mixture reproducing an average cement flue gas CO2 composition of 18 vol.% CO2. The reaction parameters considered are temperature, total gas pressure, time, and concentration of water vapor. In the absence of water vapor, the gas-solid carbonation of serpentinite mining residues is negligible, but the residues removed CO2 from the feed gas possibly due to reversible adsorption. The presence of small amount of water vapor enhances the gas-solid carbonation, but the measured rates are too low for practical application. The maximum CO2 fixation obtained is 0.07 g CO2 when reacting 1 g of residue at 200 °C and 25 barg (pCO2 ≈ 4.7) in a gas mixture containing 18 vol.% CO2 and 10 vol.% water vapor in 1 h. The fixation is likely surface limited and restricted due to poor gas-solid interaction. It was identified that both the relative humidity and carbon dioxide-water vapor ratio have a role in CO2 fixation regardless of the percentage of water vapor.

  18. Headspace Gas Chromatography Method for Studies of Reaction and Permeation of Volatile Agents with Solid Materials

    DTIC Science & Technology

    2015-01-01

    detected to produce a signal that is proportional to the amount of analyte. Flame Photometric Detector (FPD): GC detector that detects analytes by...burning the vapor stream in a hydrogen/air flame to produce fluorescent emission from characteristic species in the flame . The light emission is... Pretreatment of material: Some fabrics or materials must be treated to specifications before reaction. For example, tests for reactivity may be

  19. Simultaneous SO[sub 2]/NO/particulate removal from coal combustion gas by solid-state electrochemical technology

    SciTech Connect

    Cornell, L.P.; Cook, W.J.; Keyvani, M.; Neyman, M. ); Helfritch, D.J. . Environmental Services and Technologies Div.)

    1991-01-21

    A solid-state electrochemical process now in an early stage of development converts NO[sub x]and SO[sub x] to nitrogen, oxygen, and sulfur. Process objectives are to remove 90+% of SO[sub x] and NO[sub x] and 99% of particulates from Ohio coal combustion flue gases. The electrochemical reactor cell uses ionically conductive ceramics as electrolyte, and electronically conductive materials (including some ceramics) as electrodes; there are no moving parts, no consumable reagents, no by-product sludges, and no process fluids except the flue gas. Downstream of the electro-chemical cell, particulates are removed with a filter or electrostatic precipitator and elemental sulfur is condensed. This work developed and tested electrocatalysts for their ability to selectively reduce SO[sub 2] and NO[sub x] in the presence of oxygen gas in concentrations typical of coal combustion flue gases. Several solid electrolytes and various electrode materials were also tested for use in the electrochemical cell. Gold was chosen as the electrode in the tests because it is porous, resistant to chemical attack, and conductive. Electrocatalyst coatings containing a single transition metal were applied to one inch diameter yttria stabilized ceria disks and tested for NO and SO[sub 2] reduction.

  20. High performance solid-phase analytical derivatization of phenols for gas chromatography-mass spectrometry.

    PubMed

    Kojima, Miki; Tsunoi, Shinji; Tanaka, Minoru

    2004-07-09

    The solid-phase analytical derivatization of phenols with pentafluoropyridine is performed. Fourteen phenols including chlorophenols and alkylphenols, could be efficiently adsorbed on a strong anion-exchange solid phase, Oasis MAX. The phenols adsorbed on Oasis MAX as phenolate ions were desorbed after derivatization with pentafluoropyridine. After optimization of the adsorption and derivatization, we established a procedure for the determination of the phenols in water samples by means of GC-MS. Under the optimized conditions, calibration curves were linear in the range of 10-1000 ng/l for the alkylphenols (100-10000 ng/l for nonylphenol) and 50-1000 ng/l for the others. By processing 100 ml samples, the method detection limits (MDLs) were in the range of 0.45-2.3 ng/l for the alkylphenols (8.5 ng/l for nonylphenol) and 2.4-16 ng/l for the others. Compared with the biphasic reaction system, the signal-to-noise ratios obtained by the solid-phase analytical derivatization were significantly higher. This is ascribed to the fact that coexisting neutral and acidic compounds are efficiently removed from the sample solution by this solid-phase analytical derivatization system.

  1. The Physics Teacher: The Four States of Matter--Solid, Squishy, Liquid and Gas

    ERIC Educational Resources Information Center

    Clark, Roy W.

    2007-01-01

    The Physics Teacher provides introductory physics education at the high school and university levels and some of its articles are of interest to chemists. One such article points out that several substances used in the kitchen and bathrooms are not simple liquids or solids but are squishy substances, which include mayonnaise, shaving cream,…

  2. Hybrid Solid Oxide Fuel Cell/Gas Turbine System Design for High Altitude Long Endurance Aerospace Missions

    NASA Technical Reports Server (NTRS)

    Himansu, Ananda; Freeh, Joshua E.; Steffen, Christopher J., Jr.; Tornabene, Robert T.; Wang, Xiao-Yen J.

    2006-01-01

    A system level analysis, inclusive of mass, is carried out for a cryogenic hydrogen fueled hybrid solid oxide fuel cell and bottoming gas turbine (SOFC/GT) power system. The system is designed to provide primary or secondary electrical power for an unmanned aerial vehicle (UAV) over a high altitude, long endurance mission. The net power level and altitude are parametrically varied to examine their effect on total system mass. Some of the more important technology parameters, including turbomachinery efficiencies and the SOFC area specific resistance, are also studied for their effect on total system mass. Finally, two different solid oxide cell designs are compared to show the importance of the individual solid oxide cell design on the overall system. We show that for long mission durations of 10 days or more, the fuel mass savings resulting from the high efficiency of a SOFC/GT system more than offset the larger powerplant mass resulting from the low specific power of the SOFC/GT system. These missions therefore favor high efficiency, low power density systems, characteristics typical of fuel cell systems in general.

  3. Simultaneous particulates, NO sub x , SO sub x removal from flue gas by all solid-state electrochemcial technology

    SciTech Connect

    Cook, W.J.; Keyvani, M.; Neyman, M. ); Gordon, A.Z. )

    1989-05-22

    The IGR Process emission control technology controls SO{sub 2}/NO{sub x}, and particulate emissions from coal combustion flue gases. The technology uses an electrochemical solid-state reactor which converts SO{sub 2} and NO{sub x} to S, N{sub 2}, and O{sub 2}. The cell electrolyte is a solid electrolyte, namely a high surface area ceramic oxide-ion conductor. Tasks this quarter include: (1) Procurement, Construction and Debugging of the Electrochemical Reactors and Particulate Removal System; (2) Reactor Operation on SO{sub 2}/NO{sub x} Spiked Gas Streams; and (3) Electrocatalysts Preparation and Screening Studies. In Task (1) the particulate control test apparatus has been completely installed and flyash tests have begun. During the tests a voltage is applied across the solid electrolyte and the current is monitored while flyash passes through the cell. In Task (1) electrochemical measurements were made with oxide ion conducting ceramic disks in gases containing NO and SO{sub 2}. In Task (3) the electrochemical measurements are being made using four electrocatalysts in gases containing NO, SO{sub 2}, and oxygen. 3 refs., 4 figs., 2 tabs.

  4. Simultaneous particulates, NO sub x , SO sub x removal from flue gas by all solid-state electrochemical technology

    SciTech Connect

    Cook, W.J.; Hossain, M.S.; Keyvani, M.; Neyman, M. ); Gordon, A.Z. )

    1989-04-14

    The IGR emission control technology controls SO{sub 2}/NO{sub x}, and particulate emissions from coal combustion flue gases. The technology uses an electrochemical solid-state reactor which converts SO{sub 2} and NO{sub X} to S, N{sub 2}, and O{sub 2}. The cell electrolyte is a solid electrolyte, namely a high surface area ceramic oxide-ion conductor. Three tasks were active during this quarter: Task (1), Procurement, Construction and Debugging of the Electrochemical Reactors and Particulate Removal System, Tasks, (2) Reactor Operation on SO{sub 2}/NO{sub X} Spiked Gas Streams, and Task (3) Electrocatalysts Preparation and Screening Studies. In Task (1) the particulate control apparatus has been completely installed and its operation is being examined with respect to filtration materials and solid electrolyte. In Task (2) electrochemical measurements were made with oxide ion conducting ceramic disks in gases containing NO and SO{sub 2}. In Task (3) the electrochemical measurements are being made using a series of electrocatalysts in gases containing NO, SO{sub 2}, and oxygen. 9 figs., 1 tab.

  5. A novel method for rapid determination of total solid content in viscous liquids by multiple headspace extraction gas chromatography.

    PubMed

    Xin, Li-Ping; Chai, Xin-Sheng; Hu, Hui-Chao; Barnes, Donald G

    2014-09-05

    This work demonstrates a novel method for rapid determination of total solid content in viscous liquid (polymer-enriched) samples. The method is based multiple headspace extraction gas chromatography (MHE-GC) on a headspace vial at a temperature above boiling point of water. Thus, the trend of water loss from the tested liquid due to evaporation can be followed. With the limited MHE-GC testing (e.g., 5 extractions) and a one-point calibration procedure (i.e., recording the weight difference before and after analysis), the total amount of water in the sample can be determined, from which the total solid contents in the liquid can be calculated. A number of black liquors were analyzed by the new method which yielded results that closely matched those of the reference method; i.e., the results of these two methods differed by no more than 2.3%. Compared with the reference method, the MHE-GC method is much simpler and more practical. Therefore, it is suitable for the rapid determination of the solid content in many polymer-containing liquid samples.

  6. Evaluation of landfill gas decay constant for municipal solid waste landfills operated as bioreactors.

    PubMed

    Tolaymat, Thabet M; Green, Roger B; Hater, Gary R; Barlaz, Morton A; Black, Paul; Bronson, Doug; Powell, Jon

    2010-01-01

    Prediction of the rate of gas production from bioreactor landfills is important for the optimization of energy recovery and for estimating greenhouse gas emissions. To improve the predictability of gas production, landfill gas (LFG) composition and flow rates were monitored for 4 yr from one conventional and two bioreactor landfill cells at the Outer Loop Landfill in Louisville, KY. The ultimate methane yield (L(o)) was estimated from the biochemical methane (CH4) potential of freshly buried refuse and the decay rate constant (k) was estimated from measured CH4 collection. The site-specific L(o) was estimated to be 48.4 m3-CH4 wet Mg(-1). The estimated decay rate in the conventional cell (0.06 yr(-1)) was comparable to the AP-42 default value of 0.04 yr(-1), whereas estimates for the two bioreactor cells were substantially higher (approximately 0.11 yr(-1)). The data document the ability of the bioreactor operation to enhance landfill CH4 generation, although the estimated decay rate is sensitive to the selected L(o). The more rapid decomposition in the bioreactor cells reduces the length of time over which gas will be produced and emphasizes the importance of having a LFG collection system operational once the waste receives added moisture.

  7. Deposition and characterization of zirconium nitride (ZrN) thin films by reactive magnetron sputtering with linear gas ion source and bias voltage

    SciTech Connect

    Kavitha, A.; Kannan, R.; Subramanian, N. Sankara; Loganathan, S.

    2014-04-24

    Zirconium nitride thin films have been prepared on stainless steel substrate (304L grade) by reactive cylindrical magnetron sputtering method with Gas Ion Source (GIS) and bias voltage using optimized coating parameters. The structure and surface morphologies of the ZrN films were characterized using X-ray diffraction, atomic microscopy and scanning electron microscopy. The adhesion property of ZrN thin film has been increased due to the GIS. The coating exhibits better adhesion strength up to 10 N whereas the ZrN thin film with bias voltage exhibits adhesion up to 500 mN.

  8. Cellulosic ethanol from municipal solid waste: a case study of the economic, energy, and greenhouse gas impacts in California.

    PubMed

    Chester, Mikhail; Martin, Elliot

    2009-07-15

    As cellulosic ethanol technologies advance, states could use the organic content of municipal solid waste as a transportation fuel feedstock and simultaneously reduce externalities associated with waste disposal. We examine the major processes required to support a lignocellulosic (employing enzymatic hydrolysis) municipal solid waste-to-ethanol infrastructure computing cost, energy, and greenhouse gas effects for California. The infrastructure is compared against the Business As Usual case where the state continues to import most of its ethanol needs from the Midwest. Assuming between 60% and 90% practical yields for ethanol production, California could produce between 1.0 and 1.5 billion gallons per year of ethanol from 55% of the 40 million metric tonnes of waste currently sent to landfills annually. The classification of organic wastes and ethanol plant operation represent almost the entire system cost (between $3.5 and $4.5 billion annually) while distribution has negligible cost effects and savings from avoided landfilling is small. Fossil energy consumption from Business As Usual decreases between 82 and 130 PJ largely due to foregone gasoline consumption. The net greenhouse gas impacts are ultimately dependent on how well landfills control their emissions of decomposing organics. Based on the current landfill mix in the state, the cellulosic infrastructure would experience a slight gain in greenhouse gas emissions. However, net emissions can rise if organics diversion releases carbon that would otherwise be flared and sequestered. Emissions would be avoided if landfills are not capable of effectively controlling emissions during periods of active waste decay. There is currently considerable uncertainty surrounding the recovery efficiency of landfill emissions controls. In either case, burying lignin appears to be better than burning lignin because of its decay properties, energy and carbon content We estimate the breakeven price for lignocellulosic ethanol

  9. New paradigm for simplified combustion modeling of energetic solids: Branched chain gas reaction

    SciTech Connect

    Brewster, M.Q.; Ward, M.J.; Son, S.F.

    1997-09-01

    Two combustion models with simple but rational chemistry are compared: the classical high gas activation energy (E{sub g}/RT {much_gt} 1) Denison-Baum-Williams (DBW) model, and a new low gas activation energy (E{sub g}/RT {much_lt} 1) model recently proposed by Ward, Son, and Brewster (WSB). Both models make the same simplifying assumptions of constant properties, Lewis number unity, single-step, second order gas phase reaction, and single-step, zero order, high activation energy condensed phase decomposition. The only difference is in the gas reaction activation energy E{sub g} which is asymptotically large for DBW and vanishingly small for WSB. For realistic parameters the DBW model predicts a nearly constant temperature sensitivity {sigma}{sub p} and a pressure exponent n approaching 1. The WSB model predicts generally observed values of n = 0.7 to 0.9 and {sigma}{sub p}(T{sub o},P) with the generally observed variations with temperature (increasing) and pressure (decreasing). The WSB temperature profile also matches measured profiles better. Comparisons with experimental data are made using HMX as an illustrative example (for which WSB predictions for {sigma}{sub p}(T{sub o},P) are currently more accurate than even complex chemistry models). WSB has also shown good agreement with NC/NG double base propellant and HNF, suggesting that at the simplest level of combustion modeling, a vanishingly small gas activation energy is more realistic than an asymptotically large one. The authors conclude from this that the important (regression rate determining) gas reaction zone near the surface has more the character of chain branching than thermal decomposition.

  10. System for reactivating catalysts

    SciTech Connect

    Ginosar, Daniel M.; Thompson, David N.; Anderson, Raymond P.

    2010-03-02

    A method of reactivating a catalyst, such as a solid catalyst or a liquid catalyst is provided. The method comprises providing a catalyst that is at least partially deactivated by fouling agents. The catalyst is contacted with a fluid reactivating agent that is at or above a critical point of the fluid reactivating agent and is of sufficient density to dissolve impurities. The fluid reactivating agent reacts with at least one fouling agent, releasing the at least one fouling agent from the catalyst. The at least one fouling agent becomes dissolved in the fluid reactivating agent and is subsequently separated or removed from the fluid reactivating agent so that the fluid reactivating agent may be reused. A system for reactivating a catalyst is also disclosed.

  11. Probabilistic Analysis of Solid Oxide Fuel Cell Based Hybrid Gas Turbine System

    NASA Technical Reports Server (NTRS)

    Gorla, Rama S. R.; Pai, Shantaram S.; Rusick, Jeffrey J.

    2003-01-01

    The emergence of fuel cell systems and hybrid fuel cell systems requires the evolution of analysis strategies for evaluating thermodynamic performance. A gas turbine thermodynamic cycle integrated with a fuel cell was computationally simulated and probabilistically evaluated in view of the several uncertainties in the thermodynamic performance parameters. Cumulative distribution functions and sensitivity factors were computed for the overall thermal efficiency and net specific power output due to the uncertainties in the thermodynamic random variables. These results can be used to quickly identify the most critical design variables in order to optimize the design and make it cost effective. The analysis leads to the selection of criteria for gas turbine performance.

  12. Optimum Operation Condition on Distributed Power Supply System with Micro Gas Turbine/Solid Oxide Fuel Cell

    NASA Astrophysics Data System (ADS)

    Suzuki, Hiroshi; Yamada, Miki; Usui, Hiromoto; Komoda, Yoshiyuki

    In order to find the optimum operation condition of a distributed power supply system of 30kW class micro gas turbine (MGT) and solid oxide fuel cell (SOFC) hybrid system with the combination of line electric power and supplied gas, a system analysis has been performed. In this study, an absorption chiller and a boiler were mounted to utilize the exhausted heat from the MGT/SOFC system. The time variation of energy consumption in 24 hours for house and market models was taken into consideration for the calculation of the energy saving ratio of the present system. The operation ratio defined with the ratio of power supply of MGT/SOFC system to the power required at the peak load was changed as a parameter. From the comparison with the system using line power and gas, it is found that the present system shows high energy saving ratio around 0.4 of the operation ratio, but the energy saving ratio severely decreases in the range of high operation ratio. In this study, it is revealed that the thermal storage system effectively improves the energy saving ratio especially for the house model in winter season.

  13. Importance of network density of nanotube: Effect on nitrogen dioxide gas sensing by solid state resistive sensor

    NASA Astrophysics Data System (ADS)

    Mishra, Prabhash; Grachyova, D. V.; Moskalenko, A. S.; Shcherbak, M. A.; Pavelyev, V. S.

    2016-04-01

    Dispersion of single-walled carbon nanotubes (SWCNTs) is an established fact, however, its effect on toxic gas sensing for the development of solid state resistive sensor was not well reported. In this report, the dispersion quality of SWCNTs has been investigated and improved, and this well-dispersed SWCNTs network was used for sensor fabrication to monitor nitrogen dioxide gas. Ultraviolet (UV)-visible spectroscopic studies shows the strength of SWNTs dispersion and scanning electron microscopy (SEM) imaging provides the morphological properties of the sensor device. In this gas sensor device, two sets of resistive type sensors were fabricated that consisting of a pair of interdigitated electrodes (IDEs) using dielectrophoresis technique with different SWCNTs network density. With low-density SWCNTs networks, this fabricated sensor exhibits a high response for nitrogen dioxide sensing. The sensing of nitrogen dioxide is mainly due to charge transfer from absorbed molecules to sidewalls of nanotube and tube-tube screening acting a major role for the transport properties of charge carriers.

  14. Efficiency of energy recovery from municipal solid waste and the resultant effect on the greenhouse gas balance.

    PubMed

    Gohlke, Oliver

    2009-11-01

    Global warming is a focus of political interest and life-cycle assessment of waste management systems reveals that energy recovery from municipal solid waste is a key issue. This paper demonstrates how the greenhouse gas effects of waste treatment processes can be described in a simplified manner by considering energy efficiency indicators. For evaluation to be consistent, it is necessary to use reasonable system boundaries and to take the generation of electricity and the use of heat into account. The new European R1 efficiency criterion will lead to the development and implementation of optimized processes/systems with increased energy efficiency which, in turn, will exert an influence on the greenhouse gas effects of waste management in Europe. Promising technologies are: the increase of steam parameters, reduction of in-plant energy consumption, and the combined use of heat and power. Plants in Brescia and Amsterdam are current examples of good performance with highly efficient electricity generation. Other examples of particularly high heat recovery rates are the energy-from-waste (EfW) plants in Malmö and Gothenburg. To achieve the full potential of greenhouse gas reduction in waste management, it is necessary to avoid landfilling combustible wastes, for example, by means of landfill taxes and by putting incentives in place for increasing the efficiency of EfW systems.

  15. Remote-Raman and Micro-Raman Studies of Solid CO2, CH4, Gas Hydrates and Ice

    NASA Technical Reports Server (NTRS)

    Sharma, S. K.; Misra, A. K.; Lucey, P. G.; Exarhos, G. J.; Windisch, C. F., Jr.

    2004-01-01

    It is well known that on Mars CO2 is the principal constituent of the thin atmosphere and on a seasonal basis CO2 snow and frost coats the polar caps. Also over 25% of the Martian atmosphere freezes out and sublimes again each year. The Mars Odyssey Emission Imaging system (THEMIS) has discovered water ice exposed near the edge of Mars southern perennials cap. In recent years, it has been suggested that in Martian subsurface CO2 may exist as gas hydrate (8CO2 + 44 H2O) with melting temperature of 10C. Since the crust of Mars has been stable for enough time there is also a possibility that methane formed by magmatic processes and/or as a byproduct of anaerobic deep biosphere activity to have raised toward the planet s surface. This methane would have been captured and stored as methane hydrate, which concentrates methane and water. Determination of abundance and distribution of these ices on the surface and in the near surface are of fundamental importance for understanding Martian atmosphere, and for future exploration of Mars. In this work, we have evaluated feasibility of using remote Raman and micro-Raman spectroscopy as potential nondestructive and non-contact techniques for detecting solid CO2, CH4 gas, and gas hydrates as well as water-ice on planetary surfaces.

  16. Reactive Poly(Amic Acid)/ Poly(Glycidyl Methacrylate-r-Poly(ethylene Glycol) Methyl Ether Methacrylate) Blends as Gas Permeation Membranes

    NASA Astrophysics Data System (ADS)

    Beaulieu, Michael; Watkins, James

    2012-02-01

    Polymers containing polar moieties, such as ether groups show an affinity for acidic gases, such as CO2 due to dipole-quadrapole interactions. Polymer blends in which one of the components is poly(ethylene glycol) (PEG) have been studied extensively in literature as a CO2/light gas permeation membrane, but due to the crystallization and poor mechanical properties have been difficult to incorporate PEG above 60wt%. In this study, a series of random copolymers containing both glycidyl methacrylate and poly(ethylene glycol) methyl ether methacrylate in different ratios are blended with a poly(amic acid) prepolymer made from 4, 4'-oxydianiline and pyromellitic dianhydride to create gas permeation membranes. By using a reactive blend PEG loadings above 70% have been realized with sufficient mechanical properties, and since the side chain on the PEGMA is short these blends do not suffer from crystallization.

  17. Modeling of reflection of detonation and shock waves from a rigid wall in mixtures of a reactive gas and chemically inert particles

    NASA Astrophysics Data System (ADS)

    Fedorov, A. V.; Fomin, P. A.; Tropin, D. A.; Chen, J.-R.

    2012-05-01

    An algorithm of approximate calculation of the reflection of detonation waves in mixtures of a reactive gas and chemically inert microparticles has been proposed. Consideration has been given to the case where the gas behind the wave front is in chemical equilibrium (D → D reflection). It has been shown that the presence of the condensed phase can substantially decrease the parameters of the reflected wave (its velocity, pressure, and temperature). Within the framework of a one-dimensional nonstationary approach and with allowance for the detailed kinetics of chemical reactions, the evolution of the shock wave in a stoichiometric hydrogen-oxygen mixture with sand particles in its reflection from a rigid wall has been calculated. The limiting particle concentration below which the reflected wave is of the detonation type and above which it is of the shock type has been found.

  18. Gas-induced solid state transformation of an organic lattice: from nonporous to nanoporous

    SciTech Connect

    Tian, Jian; Thallapally, Praveen K.; Liu, Jun; Exarhos, Gregory J.; Atwood, Jerry L.

    2011-01-14

    A well-known organic host, tris-o-phenylenedioxycyclotriphosphazene, exists in two polymorphic guest-free forms: the thermodynamic nonporous high-density phase and the kinetic porous low-density phase. Simple pressurization of the high density phase with CO2 brings a solid-state transformation to the low density phase. As a consequence, the crystal volume expands significantly by 23% with conformational change of the host molecules from Cs symmetry to D3h symmetry.

  19. Immobilization conditions of ketoreductase on enantioselective reduction in a gas-solid bioreactor.

    PubMed

    Nagayama, Kazuhito; Spiess, Antje C; Büchs, Jochen

    2010-05-01

    The immobilization conditions of commercial ketoreductase for continuous enantioselective reduction in the gas-phase reaction were investigated with respect to the immobilization efficiency (residual activity and protein loading) and the gas-phase reaction efficiency (initial reaction rate, half-life, and enantioselectivity). For the analyses, ketoreductase was first immobilized by physical deposition on glass supports and the reduction of 2-butanone to (S)-2-butanol with the concomitant regeneration of NADH by 2-propanol was used as a model reaction. The optimal conditions of enzyme immobilization were obtained using an absolute pressure of 100 hPa for drying, a pH between 6.5 and 7.0, and a buffer concentration of 50 mM. The buffer concentration in particular had a strong effect on both the enzyme activity and enantioselectivity. Under optimal immobilization conditions, the thermostability of ketoreductase in the gas-phase system was enhanced compared to the aqueous-phase system, while the enantioselectivity was successfully maintained at a level identical to that of the native enzyme. These results indicate that the gas-phase reaction has a great potential for industrial production of chiral compounds, but requires careful optimization of immobilization conditions for the reaction to progress effectively.

  20. Gas-phase synthesis of solid state DNA nanoparticles stabilized by l-leucine.

    PubMed

    Raula, Janne; Hanzlíková, Martina; Rahikkala, Antti; Hautala, Juho; Kauppinen, Esko I; Urtti, Arto; Yliperttula, Marjo

    2013-02-28

    Aerosol flow reactor is used to generate solid-state nanoparticles in a one-step process that is based on drying of aerosol droplets in continuous flow. We investigated the applicability of aerosol flow reactor method to prepare solid state DNA nanoparticles. Precursor solutions of plasmid DNA with or without complexing agent (polyethylenimine), coating material (l-leucine) and mannitol (bulking material) were dispersed to nanosized droplets and instantly dried in laminar heat flow. Particle morphology, integrity and stability were studied by scanning electron microscopy. The stability of DNA was studied by gel electrophoresis. Plasmid DNA as such degraded in the aerosol flow process. Complexing agent protected DNA from degradation and coating material enabled production of dispersed, non-aggregated, nanoparticles. The resulting nanoparticles were spherical and their mean diameter ranged from 65 to 125nm. The nanoparticles were structurally stable at room temperature and their DNA content was about 10%. We present herein the proof of principle for the production of dispersed solid state nanoparticles with relevant size and intact plasmid DNA.