Generation of standard gas mixtures of halogenated, aliphatic, and aromatic compounds and prediction of the individual output rates based on molecular formula and boiling point.

PubMed

Thorenz, Ute R; Kundel, Michael; Müller, Lars; Hoffmann, Thorsten

2012-11-01

In this work, we describe a simple diffusion capillary device for the generation of various organic test gases. Using a set of basic equations the output rate of the test gas devices can easily be predicted only based on the molecular formula and the boiling point of the compounds of interest. Since these parameters are easily accessible for a large number of potential analytes, even for those compounds which are typically not listed in physico-chemical handbooks or internet databases, the adjustment of the test gas source to the concentration range required for the individual analytical application is straightforward. The agreement of the predicted and measured values is shown to be valid for different groups of chemicals, such as halocarbons, alkanes, alkenes, and aromatic compounds and for different dimensions of the diffusion capillaries. The limits of the predictability of the output rates are explored and observed to result in an underprediction of the output rates when very thin capillaries are used. It is demonstrated that pressure variations are responsible for the observed deviation of the output rates. To overcome the influence of pressure variations and at the same time to establish a suitable test gas source for highly volatile compounds, also the usability of permeation sources is explored, for example for the generation of molecular bromine test gases.

Nanobubbles: An Effective Way to Study Gas-Generating Catalysis on a Single Nanoparticle.

PubMed

Li, Shuping; Du, Ying; He, Ting; Shen, Yangbin; Bai, Chuang; Ning, Fandi; Hu, Xin; Wang, Wenhui; Xi, Shaobo; Zhou, Xiaochun

2017-10-11

Gas-generating catalysis is important to many energy-related research fields, such as photocatalytic water splitting, water electrolysis, etc. The technique of single-nanoparticle catalysis is an effective way to search for highly active nanocatalysts and elucidate the reaction mechanism. However, gas-generating catalysis remains difficult to investigate at the single-nanoparticle level because product gases, such as H 2 and O 2 , are difficult to detect on an individual nanoparticle. Here, we successfully find that nanobubbles can be used to study the gas-generating catalysis, i.e., H 2 generation from formic acid dehydrogenation on a single Pd-Ag nanoplate, with a high time resolution (50 ms) via dark-field microscopy. The research reveals that the nanobubble evolution process includes nucleation time and lifetime. The nucleation rate of nanobubbles is proportional to the catalytic activity of a single nanocatalyst. The relationship between the catalytic activity and the nucleation rate is quantitatively described by a mathematical model, which shows that an onset reaction rate (r onset ) exists for the generation of nanobubbles on a single Pd-Ag nanoplate. The research also reveals that a Pd-Ag nanoplate with larger size usually has a higher activity. However, some large-sized ones still have low activities, indicating the size of the Pd-Ag nanoplate is not the only key factor for the activity. Notablely, further research shows that Pd content is the key factor for the activity of single Pd-Ag nanoplates with similar size. The methodology and knowledge acquired from this research are also applicable to other important gas-generating catalysis reactions at the single-nanoparticle level.

Generation rate of carbon monoxide from CO2 arc welding.

PubMed

Ojima, Jun

2013-01-01

CO poisoning has been a serious industrial hazard in Japanese workplaces. Although incomplete combustion is the major cause of CO generation, there is a risk of CO poisoning during some welding operations. The aim of the present study was to evaluate the generation rate of CO from CO2 arc welding under controlled laboratory conditions and estimate the ventilation requirements for the prevention of CO poisoning. Bead on plate welding was carried out with an automatic welding robot on a rolled steel base metal under several conditions. The concentration of emitted CO from the welding was measured by a real-time CO monitor in a well-ventilated laboratory that was free from ambient CO contamination. The generation rate of CO was obtained from the three measurements-the flow rate of the welding exhaust gas, CO concentration in the exhaust gas and the arcing time. Then the ventilation requirement to prevent CO poisoning was calculated. The generation rate of CO was found to be 386-883 ml/min with a solid wire and 331-1,293 ml/min with a flux cored wire respectively. It was found that the CO concentration in a room would be maintained theoretically below the OSHA PEL (50 ppm) providing the ventilation rate in the room was 6.6-25.9 m3/min. The actual ventilation requirement was then estimated to be 6.6-259 m3/min considering incomplete mixing. In order to prevent CO poisoning, some countermeasures against gaseous emission as well as welding fumes should be taken eagerly.

Optimization and phase matching of fiber-laser-driven high-order harmonic generation at high repetition rate.

PubMed

Cabasse, Amélie; Machinet, Guillaume; Dubrouil, Antoine; Cormier, Eric; Constant, Eric

2012-11-15

High-repetition-rate sources are very attractive for high-order harmonic generation (HHG). However, due to their pulse characteristics (low energy, long duration), those systems require a tight focusing geometry to achieve the necessary intensity to generate harmonics. In this Letter, we investigate theoretically and experimentally the optimization of HHG in this geometry, to maximize the extreme UV (XUV) photon flux and improve the conversion efficiency. We analyze the influence of atomic gas media (Ar, Kr, or Xe), gas pressure, and interaction geometries (a gas jet and a finite and a semi-infinite gas cell). Numerical simulations allow us to define optimal conditions for HHG in this tight focusing regime and to observe the signature of on-axis phase matching. These conditions are implemented experimentally using a high-repetition-rate Yb-doped fiber laser system. We achieve optimization of emission with a recorded XUV photon flux of 4.5×10(12) photons/s generated in Xe at 100 kHz repetition rate.

Programmable Pulse Generator for Aditya Gas Puffing System

NASA Astrophysics Data System (ADS)

Patel, Narendra; Chavda, Chhaya; Bhatt, S. B.; Chattopadhyay, Prabal; Saxena, Y. C.

2012-11-01

In the Aditya Tokamak, one of primary requirement for plasma generation is to feed the required quantity of the fuel gas prior to plasma shot. Gas feed system mainly consists of piezoelectric gas leak valve and gas reservoir. The Hydrogen gas is prior to 300ms loop voltage for the duration of 4 msec to 7 msec. Gas is puffed during the shot for required plasma parameters and to increase plasma density using the same system. The valve is controlled by either continuous voltage or pulses of different width, amplitude and delay with respect to loop voltage. These voltage pulses are normally applied through standard pulse generator. The standard pulse generator is replaced by micro controller based in housed developed programmable pulse generator system consists of in built power supply, BNC input for external trigger, BNC output and serial interface. This programmable pulse generator is successfully tested and is in operation for gas puffing during ADITYA Tokamak experiments. The paper discusses the design and development aspect of the system.

Performance of different PEEP valves and helmet outlets at increasing gas flow rates: a bench top study.

PubMed

Isgrò, S; Zanella, A; Giani, M; Abd El Aziz El Sayed Deab, S; Pesenti, A; Patroniti, N

2012-10-01

Aim of the paper was to assess the performance of different expiratory valves and the resistance of helmet outlet ports at increasing gas flow rates. A gas flow-meter was connected to 10 different expiratory peep valves: 1 water-seal valve, 4 precalibrated fixed PEEP valves and 5 adjustable PEEP valves. Three new valves of each brand, set at different pressure levels (5-7.5-10-12.5-15 cmH(2)O, if available), were tested at increasing gas flow rates (from 30 to 150 L/min). We measured the pressure generated just before the valves. Three different helmets sealed on a mock head were connected at the inlet port with a gas flow-meter while the outlet was left clear. We measured the pressure generated inside the helmet (due to the flow-resistance of the outlet port) at increasing gas flow rates. Adjustable valves showed a variable degree flow-dependency (increasing difference between the measured and the expected pressure at increasing flow rates), while pre-calibrated valves revealed a flow-independent behavior. Water seal valve showed low degree flow-dependency. The pressures generated by the outlet port of the tested helmets ranged from 0.02 to 2.29 cmH(2)O at the highest gas flow rate. Adjustable PEEP valves are not suggested for continuous-flow CPAP systems as their flow-dependency can lead to pressures higher than expected. Precalibrated and water seal valves exhibit the best performance. Different helmet outlet ports do not significantly affect the pressure generated during helmet CPAP. In order to avoid iatrogenic complications gas flow and pressure delivered during helmet CPAP must always be monitored.

Investigation of a catalytic gas generator for the Space Shuttle APU. [hydrazine Auxiliary Propulsion Unit

NASA Technical Reports Server (NTRS)

Emmons, D. L.; Huxtable, D. D.; Blevins, D. R.

1974-01-01

An investigation was conducted to establish the capability of a monopropellant hydrazine catalytic gas generator to meet the requirements specified for the Space Shuttle APU. Detailed analytical and experimental studies were conducted on potential problem areas including long-term nitriding effects on materials, design variables affecting catalyst life, vehicle vibration effects, and catalyst oxidation/contamination. A full-scale gas generator, designed to operate at a chamber pressure of 750 psia and a flow rate of 0.36 lbm/sec, was fabricated and subjected to three separate life test series. The objective of the first test series was to demonstrate the capability of the gas generator to successfully complete 20 simulated Space Shuttle missions in steady-state operation. The gas generator was then refurbished and subjected to a second series of tests to demonstrate the pulse-mode capability of the gas generator during 20 simulated missions. The third series of tests was conducted with a refurbished reactor to further demonstrate pulse-mode capability with a modified catalyst bed.

Estimate Of The Decay Rate Constant of Hydrogen Sulfide Generation From Landfilled Drywall

EPA Science Inventory

Research was conducted to investigate the impact of particle size on H2S gas emissions and estimate a decay rate constant for H2S gas generation from the anaerobic decomposition of drywall. Three different particle sizes of regular drywall and one particle size of paperless drywa...

Coal mine burns drainage gas to generate power for profit

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scholes, W.A.

A recently commissioned gas turbine power plant that uses methane gas recovered from a coal mine is described. The power plant uses the ASEA Stal GT35B series gas turbines with a base load rating on gas of 12.9 MW at 29.3% efficiency. The plant was installed at a cost of $4 million, as part of an extensive system for removing the methane from the coal mine, enabling higher ratio of coal production to be achieved in safety with modern longwall mining techniques. The plant will save the mine up to $250,000 per month on its electricity bill plus generate profitmore » from the sale of surplus power to the local activity.« less

Moisture effects on greenhouse gases generation in nitrifying gas-phase compost biofilters.

PubMed

Maia, Guilherme D N; Day, George B; Gates, Richard S; Taraba, Joseph L; Coyne, Mark S

2012-06-01

Gas-phase compost biofilters are extensively used in concentrated animal feeding operations to remove odors and, in some cases, ammonia from air sources. The expected biochemical pathway for these predominantly aerobic systems is nitrification. However, non-uniform media with low oxygen levels can shift biofilter microbial pathways to denitrification, a source of greenhouse gases. Several factors contribute to the formation of anoxic/anaerobic zones: media aging, media and particle structure, air velocity distribution, compaction, biofilm thickness, and moisture content (MC) distribution. The present work studies the effects of media moisture conditions on ammonia (NH(3)) removal and greenhouse gas generation (nitrous oxide, N(2)O and methane, CH(4)) for gas-phase compost biofilters subject to a 100-day controlled drying process. Continuous recordings were made for the three gases and water vapor (2.21-h sampling cycle, each cycle consisted of three gas species, and water vapor, for a total of 10,050 data points). Media moisture conditions were classified into three corresponding media drying rate (DR) stages: Constant DR (wetter media), falling DR, and stable-dry system. The first-half of the constant DR period (0-750 h; MC=65-52%, w.b.) facilitated high NH(3) removal rates, but higher N(2)O generation and no CH(4) generation. At the drier stages of the constant DR (750-950 h; MC=52-48%, w.b.) NH(3) removal remained high but N(2)O net generation decreased to near zero. In the falling DR stage (1200-1480 h; MC=44-13%) N(2)O generation decreased, CH(4) increased, and NH(3) was no longer removed. No ammonia removal or greenhouse gas generation was observed in the stable-dry system (1500-2500 h; MC=13%). These results indicate that media should remain toward the drier region of the constant DR (in close proximity to the falling DR stage; MC=50%, approx.), to maintain high levels of NH(3) removal, reduced levels of N(2)O generation, and nullify levels of CH(4

Middle East fuel supply & gas exports for power generation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mitchell, G.K.; Newendorp, T.

1995-12-31

The Middle East countries that border on, or are near, the Persian Gulf hold over 65% of the world`s estimated proven crude oil reserves and 32% of the world`s estimated proven natural gas reserves. In fact, approximately 5% of the world`s total proven gas reserves are located in Qatar`s offshore North Field. This large natural gas/condensate field is currently under development to supply three LNG export projects, as well as a sub-sea pipeline proposal to export gas to Pakistan. The Middle East will continue to be a major source of crude oil and oil products to world petroleum markets, includingmore » fuel for existing and future base load, intermediate cycling and peaking electric generation plants. In addition, as the Persian Gulf countries turn their attention to exploiting their natural gas resources, the fast-growing need for electricity in the Asia-Pacific and east Africa areas offers a potential market for both pipeline and LNG export opportunities to fuel high efficiency, gas-fired combustion turbine power plants. Mr. Mitchell`s portion of this paper will discuss the background, status and timing of several Middle Eastern gas export projects that have been proposed. These large gas export projects are difficult and costly to develop and finance. Consequently, any IPP developers that are considering gas-fired projects which require Mid-East LNG as a fuel source, should understand the numerous sources and timing to securing project debt, loan terms and conditions, and, restrictions/credit rating issues associated with securing financing for these gas export projects. Mr. Newendorp`s section of the paper will cover the financing aspects of these projects, providing IPP developers with additional considerations in selecting the primary fuel supply for an Asian-Pacific or east African electric generation project.« less

21 CFR 866.2580 - Gas-generating device.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Gas-generating device. 866.2580 Section 866.2580 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2580 Gas-generating device...

21 CFR 866.2580 - Gas-generating device.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Gas-generating device. 866.2580 Section 866.2580 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2580 Gas-generating device...

21 CFR 866.2580 - Gas-generating device.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Gas-generating device. 866.2580 Section 866.2580 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2580 Gas-generating device...

21 CFR 866.2580 - Gas-generating device.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Gas-generating device. 866.2580 Section 866.2580 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2580 Gas-generating device...

21 CFR 866.2580 - Gas-generating device.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Gas-generating device. 866.2580 Section 866.2580 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2580 Gas-generating device...

Singlet oxygen generation on porous superhydrophobic surfaces: effect of gas flow and sensitizer wetting on trapping efficiency.

PubMed

Zhao, Yuanyuan; Liu, Yang; Xu, Qianfeng; Barahman, Mark; Bartusik, Dorota; Greer, Alexander; Lyons, Alan M

2014-11-13

We describe physical-organic studies of singlet oxygen generation and transport into an aqueous solution supported on superhydrophobic surfaces on which silicon-phthalocyanine (Pc) particles are immobilized. Singlet oxygen ((1)O2) was trapped by a water-soluble anthracene compound and monitored in situ using a UV-vis spectrometer. When oxygen flows through the porous superhydrophobic surface, singlet oxygen generated in the plastron (i.e., the gas layer beneath the liquid) is transported into the solution within gas bubbles, thereby increasing the liquid-gas surface area over which singlet oxygen can be trapped. Higher photooxidation rates were achieved in flowing oxygen, as compared to when the gas in the plastron was static. Superhydrophobic surfaces were also synthesized so that the Pc particles were located in contact with, or isolated from, the aqueous solution to evaluate the relative effectiveness of singlet oxygen generated in solution and the gas phase, respectively; singlet oxygen generated on particles wetted by the solution was trapped more efficiently than singlet oxygen generated in the plastron, even in the presence of flowing oxygen gas. A mechanism is proposed that explains how Pc particle wetting, plastron gas composition and flow rate as well as gas saturation of the aqueous solution affect singlet oxygen trapping efficiency. These stable superhydrophobic surfaces, which can physically isolate the photosensitizer particles from the solution may be of practical importance for delivering singlet oxygen for water purification and medical devices.

Gas-geochemical condition and ecological functions of urban soils in areas with gas generating grounds

NASA Astrophysics Data System (ADS)

Mozharova, Nadezhda; Lebed-Sharlevich, Iana; Kulachkova, Svetlana

2014-05-01

Rapid urbanization and expansion of city borders lead to development of new areas, often following with relief changes, covering of gully-ravine systems and river beds with technogenic grounds containing construction and municipal waste. Decomposition of organic matter in these grounds is a source of methane and carbon dioxide. Intensive generation and accumulation of CO2 and CH4 into grounds may cause a fire and explosion risk for constructed objects. Gases emission to the atmosphere changes the global balance of GHGs and negatively influences on human health. The aim of this investigation is to study gas-geochemical condition and ecological functions of urban soils in areas with gas generating grounds. Studied areas are the gully-ravine systems or river beds, covered with technogenic grounds during land development. Stratigraphic columns of these grounds are 5-17 meters of man-made loamy material with inclusion of construction waste. Gas generating layer with increased content of organic matter, reductive conditions and high methanogenic activity (up to 1.0 ng*g-1*h-1) is situated at the certain depth. Maximum CH4 and CO2 concentrations in this layer reach dangerous values (2-10% and 11%, respectively) in the current standards. In case of disturbance of ground layer (e.g. well-drilling) methane is rapidly transferred by convective flux to atmosphere. The rate of CH4 emission reaches 100 mg*m-2*h-1 resulting in its atmospheric concentration growth by an order of magnitude compared with background. In normal occurrence of grounds methane gradually diffuses into the upper layers by pore space, consuming on different processes (e.g. formation of organic matter, nitrogen compounds or specific particles of magnetite), and emits to atmosphere. CH4 emission rate varies from 1 to 40 mg*m-2*h-1 increasing with depth of grounds. Carbon dioxide emission is about 100 mg*m-2*h-1. During soil formation on gas generating grounds bacterial oxidation of methane, one of the most

Variable gas leak rate valve

DOEpatents

Eernisse, Errol P.; Peterson, Gary D.

1976-01-01

A variable gas leak rate valve which utilizes a poled piezoelectric element to control opening and closing of the valve. The gas flow may be around a cylindrical rod with a tubular piezoelectric member encircling the rod for seating thereagainst to block passage of gas and for reopening thereof upon application of suitable electrical fields.

High harmonic generation in rare gas solids

NASA Astrophysics Data System (ADS)

Reis, David

2015-05-01

There has recently been renewed interest in the interaction of strong optical fields with large band-gap solids. The response is known to involve the attosecond dynamics of the electrons and includes the generation of non-perturbative high-order harmonics. However, the detailed mechanism remain a matter of intense debate. Here we report on high harmonic generation in rare gas solids as compared to a dilute gas. The measured spectrum in the solid exhibits a secondary plateau and a subsequent high-energy cut-off that extends well beyond the gas phase, while the ellipticity dependence is simlar to the gas phase and suggests importance of coherent single-site recombination.

Fuel cell generator containing a gas sealing means

DOEpatents

Makiel, J.M.

1987-02-03

A high temperature solid electrolyte electrochemical generator is made, operating with flowing fuel gas and oxidant gas, the generator having a thermal insulation layer, and a sealing means contacting or contained within the insulation, where the sealing means is effective to control the contact of the various gases utilized in the generator. 5 figs.

RADIOLYTIC GAS PRODUCTION RATES OF POLYMERS EXPOSED TO TRITIUM GAS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clark, E.

Data from previous reports on studies of polymers exposed to tritium gas is further analyzed to estimate rates of radiolytic gas production. Also, graphs of gas release during tritium exposure from ultrahigh molecular weight polyethylene (UHMW-PE), polytetrafluoroethylene (PTFE, a trade name is Teflon®), and Vespel® polyimide are re-plotted as moles of gas as a function of time, which is consistent with a later study of tritium effects on various formulations of the elastomer ethylene-propylene-diene monomer (EPDM). These gas production rate estimates may be useful while considering using these polymers in tritium processing systems. These rates are valid at least formore » the longest exposure times for each material, two years for UHMW-PE, PTFE, and Vespel®, and fourteen months for filled and unfilled EPDM. Note that the production “rate” for Vespel® is a quantity of H{sub 2} produced during a single exposure to tritium, independent of length of time. The larger production rate per unit mass for unfilled EPDM results from the lack of filler- the carbon black in filled EPDM does not produce H{sub 2} or HT. This is one aspect of how inert fillers reduce the effects of ionizing radiation on polymers.« less

Experimental study on trace chemical contaminant generation rates of human metabolism in spacecraft crew module

NASA Astrophysics Data System (ADS)

Lihua, Guo; Xinxing, He; Guoxin, Xu; Xin, Qi

2012-12-01

Trace chemical contaminants generated by human metabolism is a major source of contamination in spacecraft crew module. In this research, types and generation rates of pollutants from human metabolism were determined in the Chinese diets. Expired air, skin gas, and sweat of 20 subjects were analyzed at different exercise states in a simulated module. The exercise states were designed according to the basic activities in the orbit of astronauts. Qualitative and quantitative analyses of contaminants generated by human metabolic were performed with gas chromatography/mass spectrometry, gas chromatography and UV spectrophotometer. Sixteen chemical compounds from metabolic sources were found. With the increase in physical load, the concentrations of chemical compounds from human skin and expired air correspondingly increased. The species and the offgassing rates of pollutants from human metabolism are different among the Chinese, Americans and the Russians due to differences in ethnicity and dietary customs. This research provides data to aid in the design, development and operation of China's long duration space mission.

Fume generation rates for stainless steel, nickel and aluminum alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Castner, H.R.

1996-12-01

This paper describes a study of the effects of pulsed welding current on fume produced during gas metal arc welding (GMAW) of stainless steel, nickel, and aluminum alloys. This is an extension of earlier studies of mild steel electrode wire. Reduction of welding fume is important because steady current GMAW of stainless steels and nickel alloys may produce fume that exceeds recommended worker exposure limits for some of the fume constituents. Fume generation from aluminum alloy ER5356 was studied because steady current welding with this alloy produces much higher fume generation rates than ER4043 alloy electrode wire. This work showsmore » that pulsed current can reduce GMAW fume generation rates for Er308L, ER310, and ER312 stainless steel, ERNiCr-3 nickel alloy, and ER5356 aluminum-magnesium alloy electrode wires.« less

The Dependence of Heat and Gas Transfer Velocities on Wind-Generated and Mechanically Generated Aqueous-Phase Turbulence

NASA Astrophysics Data System (ADS)

Liang, H.; Mukto, M.; Loewen, M.; Zappa, C.; Litchendorf, T.; Asher, W.; Jessup, A.

2006-12-01

The air-sea flux, F, of a sparingly soluble nonreactive gas can be expressed as F = kG( CS-CW), where kG is the gas transfer velocity, CS is the concentration of gas that would be expected in the water if the system were in Henry`s Gas Law equilibrium, and CW is the actual concentration of the gas in the water. An analogous relationship for the net heat flux can also be written using the heat transfer velocity, kH, and the bulk-skin temperature difference in the aqueous phase. Hydrodynamical models of gas and heat exchange based on surface renewal theory predict that kG and kH will scale as the square root of the inverse of a timescale of the turbulence. Furthermore, if surface renewal provides an accurate conceptual model for both transfer processes, then both kG and kH should behave identically as turbulence conditions change. Here we report on recent laboratory experiments in which we measured turbulence, heat fluxes, kG, and kH in a 0.5 m by 0.5 m by 1 m deep tank in the presence of turbulence generated mechanically using a random synthetic jet array. The turbulence tank was embedded in a small wind tunnel so that kG and kH could be studied as a function of the mechanically generated turbulence but also turbulence generated by wind stress. Net heat transfer velocities were measured using Active Controlled Flux Technique and estimated from measurements of the latent and sensible heat fluxes combined with direct measurements of the bulk-skin temperature difference. Gas transfer velocities were determined by measuring the evasion rates of sulfur hexafluoride and helium. The length and velocity scales of the aqueous-phase turbulence were measured using a Digital Particle-Image Velocimetry system. These combined data sets are used to study how kG and kH depend on system turbulence, whether this dependence is consonant with that predicted using surface renewal, and whether there is a quantitative difference between mechanically generated turbulence and turbulence

46 CFR 154.908 - Inert gas generator: Location.

Code of Federal Regulations, 2011 CFR

2011-10-01

... STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Atmospheric Control in Cargo Containment Systems § 154.908 Inert gas generator: Location. (a) Except as..., service, or control space. (b) An inert gas generator that does not use flame burning equipment may be...

46 CFR 154.908 - Inert gas generator: Location.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Inert gas generator: Location. 154.908 Section 154.908 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY... Atmospheric Control in Cargo Containment Systems § 154.908 Inert gas generator: Location. (a) Except as...

Biomass & Natural Gas Based Hydrogen Fuel For Gas Turbine (Power Generation)

EPA Science Inventory

Significant progress has been made by major power generation equipment manufacturers in the development of market applications for hydrogen fuel use in gas turbines in recent years. Development of a new application using gas turbines for significant reduction of power plant CO2 e...

Generation of oxy-hydrogen gas and its effect on performance of spark ignition engine

NASA Astrophysics Data System (ADS)

Patil, N. N.; Chavan, C. B.; More, A. S.; Baskar, P.

2017-11-01

Considering the current scenario of petroleum fuels, it has been observed that, they will last for few years from now. On the other hand, the ever increasing cost of a gasoline fuels and their related adverse effects on environment caught the attention of researchers to find a supplementary source. For commercial fuels, supplementary source is not about replacing the entire fuel, instead enhancing efficiency by simply making use of it in lesser amount. From the recent research that has been carried out, focus on the use of Hydrogen rich gas as a supplementary source of fuel has increased. But the problem related to the storage of hydrogen gas confines the application of pure hydrogen in petrol engine. Using oxy-hydrogen gas (HHO) generator the difficulties of storing the hydrogen have overcome up to a certain limit. The present study highlights on performance evaluation of conventional petrol engine by using HHO gas as a supplementary fuel. HHO gas was generated from the electrolysis of water. KOH solution of 3 Molar concentration was used which act as a catalyst and accelerates the rate of generation of HHO gas. Quantity of gas to be supplied to the engine was controlled by varying amount of current. It was observed that, engine performance was improved on the introduction of HHO gas.

Gas-Generator Augmented Expander Cycle Rocket Engine

NASA Technical Reports Server (NTRS)

Greene, William D. (Inventor)

2011-01-01

An augmented expander cycle rocket engine includes first and second turbopumps for respectively pumping fuel and oxidizer. A gas-generator receives a first portion of fuel output from the first turbopump and a first portion of oxidizer output from the second turbopump to ignite and discharge heated gas. A heat exchanger close-coupled to the gas-generator receives in a first conduit the discharged heated gas, and transfers heat to an adjacent second conduit carrying fuel exiting the cooling passages of a primary combustion chamber. Heat is transferred to the fuel passing through the cooling passages. The heated fuel enters the second conduit of the heat exchanger to absorb more heat from the first conduit, and then flows to drive a turbine of one or both of the turbopumps. The arrangement prevents the turbopumps exposure to combusted gas that could freeze in the turbomachinery and cause catastrophic failure upon attempted engine restart.

Gas Generation Testing of Spherical Resorcinol-Formaldehyde (sRF) Resin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Colburn, Heather A.; Bryan, Samuel A.; Camaioni, Donald M.

This report describes gas generation testing of the spherical resorcinol-formaldehyde (sRF) resin that was conducted to support the technology maturation of the LAWPS facility. The current safety basis for the LAWPS facility is based primarily on two studies that had limited or inconclusive data sets. The two studies indicated a 40% increase in hydrogen generation rate of water (as predicted by the Hu model) with sRF resin over water alone. However, the previous studies did not test the range of conditions (process fluids and temperatures) that are expected in the LAWPS facility. Additionally, the previous studies did not obtain replicatemore » test results or comparable liquid-only control samples. All of the testing described in this report, conducted with water, 0.45M nitric acid, and waste simulants with and without sRF resin, returned hydrogen generation rates that are within the current safety basis for the facility of 1.4 times the Hu model output for water.« less

Modeled occupational exposures to gas-phase medical laser-generated air contaminants.

PubMed

Lippert, Julia F; Lacey, Steven E; Jones, Rachael M

2014-01-01

Exposure monitoring data indicate the potential for substantive exposure to laser-generated air contaminants (LGAC); however the diversity of medical lasers and their applications limit generalization from direct workplace monitoring. Emission rates of seven previously reported gas-phase constituents of medical laser-generated air contaminants (LGAC) were determined experimentally and used in a semi-empirical two-zone model to estimate a range of plausible occupational exposures to health care staff. Single-source emission rates were generated in an emission chamber as a one-compartment mass balance model at steady-state. Clinical facility parameters such as room size and ventilation rate were based on standard ventilation and environmental conditions required for a laser surgical facility in compliance with regulatory agencies. All input variables in the model including point source emission rates were varied over an appropriate distribution in a Monte Carlo simulation to generate a range of time-weighted average (TWA) concentrations in the near and far field zones of the room in a conservative approach inclusive of all contributing factors to inform future predictive models. The concentrations were assessed for risk and the highest values were shown to be at least three orders of magnitude lower than the relevant occupational exposure limits (OELs). Estimated values do not appear to present a significant exposure hazard within the conditions of our emission rate estimates.

Timing of oil and gas generation of petroleum systems in the Southwestern Wyoming Province

USGS Publications Warehouse

Roberts, L.N.R.; Lewan, M.D.; Finn, T.M.

2004-01-01

Burial history, thermal maturity, and timing of petroleum generation were modeled for eight key source-rock horizons at seven locations throughout the Southwestern Wyoming Province. The horizons are the bases of the Lower Permian Phosphoria Formation, the Upper Cretaceous Mowry Shale, Niobrara Formation, Baxter Shale (and equivalents), upper part of the Mesaverde Group, Lewis Shale, Lance Formation, and the Tertiary (Paleocene) Fort Union Formation. Burial history locations include three in the deepest parts of the province (Adobe Town in the Washakie Basin, Eagles Nest in the Great Divide Basin, and Wagon Wheel in the northern Green River Basin); two at intermediate basin depths (Federal 31-1 and Currant, Creek in the central and southern parts of the Green River Basin, respectively); and two relatively shallow locations (Bear 1 on the southeastern margin of the Sand Wash Basin and Bruff 2 on the Moxa arch). An overall ranking of the burial history locations in order of decreasing thermal maturity is Adobe Town > Eagles Nest > Wagon Wheel > Currant Creek > Federal 31-1 > Bear-1 > Bruff 2. The results of the models indicate that peak petroleum generation from Cretaceous oil- and gas-prone source rocks in the deepest parts of the province occurred from Late Cretaceous through middle Eocene. At the modeled locations, peak oil generation from source rocks of the Phosphoria Formation, which contain type-IIS kerogen, occurred in the Late Cretaceous (80 to 73 million years ago (Ma)). Gas generation from the cracking of Phosphoria oil reached a peak in the late Paleocene (57 Ma) only in the deepest parts of the province. The Mowry Shale, Niobrara Formation, and Baxter Shale (and equivalents) contain type-IIS or a mix of type-II and type-III kerogens. Oil generation from these units, in the deepest parts of the province, reached peak rates during the latest Cretaceous to early Paleocene (66 to 61 Ma). Only at these deepest locations did these units reach peak gas

Development and application of an analysis methodology for interpreting ambiguous historical pressure data in the WIPP gas-generation experiments.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Felicione, F. S.

2006-01-23

The potential for generation of gases in transuranic (TRU) waste by microbial activity, chemical interactions, corrosion, and radiolysis was addressed in the Argonne National Laboratory-West (ANL-West) Gas-Generation Experiments (GGE). Data was collected over several years by simulating the conditions in the Waste Isolation Pilot Plant (WIPP) after the eventual intrusion of brine into the repository. Fourteen test containers with various actual TRU waste immersed in representative brine were inoculated with WIPP-relevant microbes, pressurized with inert gases, and kept in an inert-atmosphere environment for several years to provide estimates of the gas-generation rates that will be used in computer models formore » future WIPP Performance Assessments. Modest temperature variations occurred during the long-term ANL-West experiments. Although the experiment temperatures always remained well within the experiment specifications, the small temperature variation was observed to affect the test container pressure far more than had been anticipated. In fact, the pressure variations were so large, and seemingly erratic, that it was impossible to discern whether the data was even valid and whether the long-term pressure trend was increasing, decreasing, or constant. The result was that no useful estimates of gas-generation rates could be deduced from the pressure data. Several initial attempts were made to quantify the pressure fluctuations by relating these to the measured temperature variation, but none was successful. The work reported here carefully analyzed the pressure measurements to determine if these were valid or erroneous data. It was found that a thorough consideration of the physical phenomena that were occurring can, in conjunction with suitable gas laws, account quite accurately for the pressure changes that were observed. Failure of the earlier attempts to validate the data was traced to the omission of several phenomena, the most important being the

Two generators to produce SI-traceable reference gas mixtures for reactive compounds at atmospheric levels

NASA Astrophysics Data System (ADS)

Pascale, C.; Guillevic, M.; Ackermann, A.; Leuenberger, D.; Niederhauser, B.

2017-12-01

To answer the needs of air quality and climate monitoring networks, two new gas generators were developed and manufactured at METAS in order to dynamically generate SI-traceable reference gas mixtures for reactive compounds at atmospheric concentrations. The technical features of the transportable generators allow for the realization of such gas standards for reactive compounds (e.g. NO2, volatile organic compounds) in the nmol · mol-1 range (ReGaS2), and fluorinated gases in the pmol ṡ mol-1 range (ReGaS3). The generation method is based on permeation and dynamic dilution. The transportable generators have multiple individual permeation chambers allowing for the generation of mixtures containing up to five different compounds. This mixture is then diluted using mass flow controllers, thus making the production process adaptable to generate the required amount of substance fraction. All parts of ReGaS2 in contact with the gas mixture are coated to reduce adsorption/desorption processes. Each input parameter required to calculate the generated amount of substance fraction is calibrated with SI-primary standards. The stability and reproducibility of the generated amount of substance fractions were tested with NO2 for ReGaS2 and HFC-125 for ReGaS3. They demonstrate stability over 1-4 d better than 0.4% and 0.8%, respectively, and reproducibility better than 0.7% and 1%, respectively. Finally, the relative expanded uncertainty of the generated amount of substance fraction is smaller than 3% with the major contributions coming from the uncertainty of the permeation rate and/or of the purity of the matrix gas. These relative expanded uncertainties meet then the needs of the data quality objectives fixed by the World Meteorological Organization.

Generation of ethylene tracer by noncatalytic pyrolysis of natural gas at elevated pressure

USGS Publications Warehouse

Lu, Y.; Chen, S.; Rostam-Abadi, M.; Ruch, R.; Coleman, D.; Benson, L.J.

2005-01-01

There is a critical need within the pipeline gas industry for an inexpensive and reliable technology to generate an identification tag or tracer that can be added to pipeline gas to identify gas that may escape and improve the deliverability and management of gas in underground storage fields. Ethylene is an ideal tracer, because it does not exist naturally in the pipeline gas, and because its physical properties are similar to the pipeline gas components. A pyrolysis process, known as the Tragen process, has been developed to continuously convert the ???2%-4% ethane component present in pipeline gas into ethylene at common pipeline pressures of 800 psi. In our studies of the Tragen process, pyrolysis without steam addition achieved a maximum ethylene yield of 28%-35% at a temperature range of 700-775 ??C, corresponding to an ethylene concentration of 4600-5800 ppm in the product gas. Coke deposition was determined to occur at a significant rate in the pyrolysis reactor without steam addition. The ?? 13C isotopic analysis of gas components showed a ?? 13C value of ethylene similar to ethane in the pipeline gas, indicating that most of the ethylene was generated from decomposition of the ethane in the raw gas. However, ?? 13C isotopic analysis of the deposited coke showed that coke was primarily produced from methane, rather than from ethane or other heavier hydrocarbons. No coke deposition was observed with the addition of steam at concentrations of > 20% by volume. The dilution with steam also improved the ethylene yield. ?? 2005 American Chemical Society.

Lifecycle greenhouse gas emissions of coal, conventional and unconventional natural gas for electricity generation

EPA Science Inventory

An analysis of the lifecycle greenhouse gas (GHG) emissions associated with natural gas use recently published by Howarth et al. (2011) stated that use of natural gas produced from shale formations via hydraulic fracturing would generate greater lifecycle GHG emissions than petro...

46 CFR 154.906 - Inert gas generators.

Code of Federal Regulations, 2012 CFR

2012-10-01

...: (a) Produce an inert gas containing less than 5% oxygen by volume; (b) Have a device to continuously sample the discharge of the generator for oxygen content; and (c) Have an audible and visual alarm in the cargo control station that alarms when the inert gas contains 5% or more oxygen by volume. ...

46 CFR 154.906 - Inert gas generators.

Code of Federal Regulations, 2014 CFR

2014-10-01

...: (a) Produce an inert gas containing less than 5% oxygen by volume; (b) Have a device to continuously sample the discharge of the generator for oxygen content; and (c) Have an audible and visual alarm in the cargo control station that alarms when the inert gas contains 5% or more oxygen by volume. ...

46 CFR 154.906 - Inert gas generators.

Code of Federal Regulations, 2013 CFR

2013-10-01

...: (a) Produce an inert gas containing less than 5% oxygen by volume; (b) Have a device to continuously sample the discharge of the generator for oxygen content; and (c) Have an audible and visual alarm in the cargo control station that alarms when the inert gas contains 5% or more oxygen by volume. ...

46 CFR 154.906 - Inert gas generators.

Code of Federal Regulations, 2011 CFR

2011-10-01

...: (a) Produce an inert gas containing less than 5% oxygen by volume; (b) Have a device to continuously sample the discharge of the generator for oxygen content; and (c) Have an audible and visual alarm in the cargo control station that alarms when the inert gas contains 5% or more oxygen by volume. ...

46 CFR 154.906 - Inert gas generators.

Code of Federal Regulations, 2010 CFR

2010-10-01

...: (a) Produce an inert gas containing less than 5% oxygen by volume; (b) Have a device to continuously sample the discharge of the generator for oxygen content; and (c) Have an audible and visual alarm in the cargo control station that alarms when the inert gas contains 5% or more oxygen by volume. ...

First-order kinetic gas generation model parameters for wet landfills.

PubMed

Faour, Ayman A; Reinhart, Debra R; You, Huaxin

2007-01-01

Landfill gas collection data from wet landfill cells were analyzed and first-order gas generation model parameters were estimated for the US EPA landfill gas emissions model (LandGEM). Parameters were determined through statistical comparison of predicted and actual gas collection. The US EPA LandGEM model appeared to fit the data well, provided it is preceded by a lag phase, which on average was 1.5 years. The first-order reaction rate constant, k, and the methane generation potential, L(o), were estimated for a set of landfills with short-term waste placement and long-term gas collection data. Mean and 95% confidence parameter estimates for these data sets were found using mixed-effects model regression followed by bootstrap analysis. The mean values for the specific methane volume produced during the lag phase (V(sto)), L(o), and k were 33 m(3)/Megagrams (Mg), 76 m(3)/Mg, and 0.28 year(-1), respectively. Parameters were also estimated for three full scale wet landfills where waste was placed over many years. The k and L(o) estimated for these landfills were 0.21 year(-1), 115 m(3)/Mg, 0.11 year(-1), 95 m(3)/Mg, and 0.12 year(-1) and 87 m(3)/Mg, respectively. A group of data points from wet landfills cells with short-term data were also analyzed. A conservative set of parameter estimates was suggested based on the upper 95% confidence interval parameters as a k of 0.3 year(-1) and a L(o) of 100 m(3)/Mg if design is optimized and the lag is minimized.

Generation and confinement of microwave gas-plasma in photonic dielectric microstructure.

PubMed

Debord, B; Jamier, R; Gérôme, F; Leroy, O; Boisse-Laporte, C; Leprince, P; Alves, L L; Benabid, F

2013-10-21

We report on a self-guided microwave surface-wave induced generation of ~60 μm diameter and 6 cm-long column of argon-plasma confined in the core of a hollow-core photonic crystal fiber. At gas pressure of 1 mbar, the micro-confined plasma exhibits a stable transverse profile with a maximum gas-temperature as high as 1300 ± 200 K, and a wall-temperature as low as 500 K, and an electron density level of 10¹⁴ cm⁻³. The fiber guided fluorescence emission presents strong Ar⁺ spectral lines in the visible and near UV. Theory shows that the observed combination of relatively low wall-temperature and high ionisation rate in this strongly confined configuration is due to an unprecedentedly wide electrostatic space-charge field and the subsequent ion acceleration dominance in the plasma-to-gas power transfer.

Characterization and calibration of gas sensor systems at ppb level—a versatile test gas generation system

NASA Astrophysics Data System (ADS)

Leidinger, Martin; Schultealbert, Caroline; Neu, Julian; Schütze, Andreas; Sauerwald, Tilman

2018-01-01

This article presents a test gas generation system designed to generate ppb level gas concentrations from gas cylinders. The focus is on permanent gases and volatile organic compounds (VOCs) for applications like indoor and outdoor air quality monitoring or breath analysis. In the design and the setup of the system, several issues regarding handling of trace gas concentrations have been considered, addressed and tested. This concerns not only the active fluidic components (flow controllers, valves), which have been chosen specifically for the task, but also the design of the fluidic tubing regarding dead volumes and delay times, which have been simulated for the chosen setup. Different tubing materials have been tested for their adsorption/desorption characteristics regarding naphthalene, a highly relevant gas for indoor air quality monitoring, which has generated high gas exchange times in a previous gas mixing system due to long time adsorption/desorption effects. Residual gas contaminations of the system and the selected carrier air supply have been detected and quantified using both an analytical method (GC-MS analysis according to ISO 16000-6) and a metal oxide semiconductor gas sensor, which detected a maximum contamination equivalent to 28 ppb of carbon monoxide. A measurement strategy for suppressing even this contamination has been devised, which allows the system to be used for gas sensor and gas sensor system characterization and calibration in the low ppb concentration range.

Leakage Currents and Gas Generation in Advanced Wet Tantalum Capacitors

NASA Technical Reports Server (NTRS)

Teverovsky, Alexander

2015-01-01

Currently, military grade, established reliability wet tantalum capacitors are among the most reliable parts used for space applications. This has been achieved over the years by extensive testing and improvements in design and materials. However, a rapid insertion of new types of advanced, high volumetric efficiency capacitors in space systems without proper testing and analysis of degradation mechanisms might increase risks of failures. The specifics of leakage currents in wet electrolytic capacitors is that the conduction process is associated with electrolysis of electrolyte and gas generation resulting in building up of internal gas pressure in the parts. The risk associated with excessive leakage currents and increased pressure is greater for high value advanced wet tantalum capacitors, but it has not been properly evaluated yet. In this work, in Part I, leakages currents in various types of tantalum capacitors have been analyzed in a wide range of voltages, temperatures, and time under bias. Gas generation and the level of internal pressure have been calculated in Part II for different case sizes and different hermeticity leak rates to assess maximal allowable leakage currents. Effects related to electrolyte penetration to the glass seal area have been studied and the possibility of failures analyzed in Part III. Recommendations for screening and qualification to reduce risks of failures have been suggested.

Accounting for fuel price risk: Using forward natural gas prices instead of gas price forecasts to compare renewable to natural gas-fired generation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bolinger, Mark; Wiser, Ryan; Golove, William

2003-08-13

Against the backdrop of increasingly volatile natural gas prices, renewable energy resources, which by their nature are immune to natural gas fuel price risk, provide a real economic benefit. Unlike many contracts for natural gas-fired generation, renewable generation is typically sold under fixed-price contracts. Assuming that electricity consumers value long-term price stability, a utility or other retail electricity supplier that is looking to expand its resource portfolio (or a policymaker interested in evaluating different resource options) should therefore compare the cost of fixed-price renewable generation to the hedged or guaranteed cost of new natural gas-fired generation, rather than to projectedmore » costs based on uncertain gas price forecasts. To do otherwise would be to compare apples to oranges: by their nature, renewable resources carry no natural gas fuel price risk, and if the market values that attribute, then the most appropriate comparison is to the hedged cost of natural gas-fired generation. Nonetheless, utilities and others often compare the costs of renewable to gas-fired generation using as their fuel price input long-term gas price forecasts that are inherently uncertain, rather than long-term natural gas forward prices that can actually be locked in. This practice raises the critical question of how these two price streams compare. If they are similar, then one might conclude that forecast-based modeling and planning exercises are in fact approximating an apples-to-apples comparison, and no further consideration is necessary. If, however, natural gas forward prices systematically differ from price forecasts, then the use of such forecasts in planning and modeling exercises will yield results that are biased in favor of either renewable (if forwards < forecasts) or natural gas-fired generation (if forwards > forecasts). In this report we compare the cost of hedging natural gas price risk through traditional gas-based hedging

Country-Level Life Cycle Assessment of Greenhouse Gas Emissions from Liquefied Natural Gas Trade for Electricity Generation.

PubMed

Kasumu, Adebola S; Li, Vivian; Coleman, James W; Liendo, Jeanne; Jordaan, Sarah M

2018-02-20

In the determination of the net impact of liquefied natural gas (LNG) on greenhouse gas emissions, life cycle assessments (LCA) of electricity generation have yet to combine the effects of transport distances between exporting and importing countries, country-level infrastructure in importing countries, and the fuel sources displaced in importing countries. To address this, we conduct a LCA of electricity generated from LNG export from British Columbia, Canada with a three-step approach: (1) a review of viable electricity generation markets for LNG, (2) the development of results for greenhouse gas emissions that account for transport to importing nations as well as the infrastructure required for power generation and delivery, and (3) emissions displacement scenarios to test assumptions about what electricity is being displaced in the importing nation. Results show that while the ultimate magnitude of the greenhouse gas emissions associated with natural gas production systems is still unknown, life cycle greenhouse gas emissions depend on country-level infrastructure (specifically, the efficiency of the generation fleet, transmission and distribution losses and LNG ocean transport distances) as well as the assumptions on what is displaced in the domestic electricity generation mix. Exogenous events such as the Fukushima nuclear disaster have unanticipated effects on the emissions displacement results. We highlight national regulations, environmental policies, and multilateral agreements that could play a role in mitigating emissions.

Generation and delivery device for ozone gas

NASA Technical Reports Server (NTRS)

Andrews, Craig C. (Inventor); Murphy, Oliver J. (Inventor)

2002-01-01

The present invention provides an ozone generation and delivery system that lends itself to small scale applications and requires very low maintenance. The system preferably includes an anode reservoir and a cathode phase separator each having a hydrophobic membrane to allow phase separation of produced gases from water. The hydrogen gas, ozone gas and water containing ozone may be delivered under pressure.

Fission-gas-release rates from irradiated uranium nitride specimens

NASA Technical Reports Server (NTRS)

Weinstein, M. B.; Kirchgessner, T. A.; Tambling, T. N.

1973-01-01

Fission-gas-release rates from two 93 percent dense UN specimens were measured using a sweep gas facility. Specimen burnup rates averaged .0045 and .0032 percent/hr, and the specimen temperatures ranged from 425 to 1323 K and from 552 to 1502 K, respectively. Burnups up to 7.8 percent were achieved. Fission-gas-release rates first decreased then increased with burnup. Extensive interconnected intergranular porosity formed in the specimen operated at over 1500 K. Release rate variation with both burnup and temperature agreed with previous irradiation test results.

Dependence of Ozone Generation on Gas Temperature Distribution in AC Atmospheric Pressure Dielectric Barrier Discharge in Oxygen

NASA Astrophysics Data System (ADS)

Takahashi, Go; Akashi, Haruaki

AC atmospheric pressure multi-filament dielectric barrier discharge in oxygen has been simulated using two dimensional fluid model. In the discharge, three kinds of streamers have been obtained. They are primary streamers, small scale streamers and secondary streamers. The primary streamers are main streamers in the discharge and the small scale streamers are formed after the ceasing of the primary streamers. And the secondary streamers are formed on the trace of the primary streamers. In these streamers, the primary and the small scale streamers are very effective to generate O(3P) oxygen atoms which are precursor of ozone. And the ozone is generated mainly in the vicinity of the dielectrics. In high gas temperature region, ozone generation decreases in general. However, increase of the O(3P) oxygen atom density in high gas temperature region compensates decrease of ozone generation rate coefficient. As a result, amount of ozone generation has not changed. But if the effect of gas temperature was neglected, amount of ozone generation increases 10%.

Effect of depletion rate on solution gas drive in shale

NASA Astrophysics Data System (ADS)

Zhang, Mingshan; Sang, Qian; Gong, Houjian; Li, Yajun; Dong, Mingzhe

2018-01-01

Solution gas drive process has been studied extensively in sand rocks and heavy oil reservoirs for a long time. Oil recovery is affected by several factors, such as depletion rate, initial GOR (gas oil ratio), oil viscosity, and temperature and so on. Before the solution gas drive tests, elastic drive without dissolved gas was carried out as a reference, which shows a limited oil recovery. Solution gas drive experiments were conducted in shale to study oil recovery with various depletion rates. Results show that oil recovery increases with the decrease of depletion rates because of the low permeability and desorption of methane.

PV output smoothing using a battery and natural gas engine-generator.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Jay Dean; Ellis, Abraham; Denda, Atsushi

2013-02-01

In some situations involving weak grids or high penetration scenarios, the variability of photovoltaic systems can affect the local electrical grid. In order to mitigate destabilizing effects of power fluctuations, an energy storage device or other controllable generation or load can be used. This paper describes the development of a controller for coordinated operation of a small gas engine-generator set (genset) and a battery for smoothing PV plant output. There are a number of benefits derived from using a traditional generation resource in combination with the battery; the variability of the photovoltaic system can be reduced to a specific levelmore » with a smaller battery and Power Conditioning System (PCS) and the lifetime of the battery can be extended. The controller was designed specifically for a PV/energy storage project (Prosperity) and a gas engine-generator (Mesa Del Sol) currently operating on the same feeder in Albuquerque, New Mexico. A number of smoothing simulations of the Prosperity PV were conducted using power data collected from the site. By adjusting the control parameters, tradeoffs between battery use and ramp rates could be tuned. A cost function was created to optimize the control in order to balance, in this example, the need to have low ramp rates with reducing battery size and operation. Simulations were performed for cases with only a genset or battery, and with and without coordinated control between the genset and battery, e.g., without the communication link between sites or during a communication failure. The degree of smoothing without coordinated control did not change significantly because the battery dominated the smoothing response. It is anticipated that this work will be followed by a field demonstration in the near future.« less

Automatable Measurement of Gas Exchange Rate in Streams: Oxygen-Carbon Method

NASA Astrophysics Data System (ADS)

Pennington, R.; Haggerty, R.; Argerich, A.; Wondzell, S. M.

2015-12-01

Gas exchange rates between streams and the atmosphere are critically important to measurement of in-stream ecologic processes, as well as fate and transport of hazardous pollutants such as mercury and PCBs. Methods to estimate gas exchange rates include empirical relations to hydraulics, and direct injection of a tracer gas such as propane or SF6. Empirical relations are inconsistent and inaccurate, particularly for lower order, high-roughness streams. Gas injections are labor-intensive, and measured gas exchange rates are difficult to extrapolate in time since they change with discharge and stream geometry. We propose a novel method for calculation of gas exchange rates utilizing O2, pCO2, pH, and temperature data. Measurements, which can be automated using data loggers and probes, are made on the upstream and downstream end of the study reach. Gas exchange rates are then calculated from a solution to the transport equations for oxygen and dissolved inorganic carbon. Field tests in steep, low order, high roughness streams of the HJ Andrews Experimental Forest indicate the method to be viable along stream reaches with high downstream gas concentration gradients and high rates of gas transfer velocity. Automated and continuous collection of oxygen and carbonate chemistry data is increasingly common, thus the method may be used to estimate gas exchange rates through time, and is well suited for interactivity with databases.

Device accurately measures and records low gas-flow rates

NASA Technical Reports Server (NTRS)

Branum, L. W.

1966-01-01

Free-floating piston in a vertical column accurately measures and records low gas-flow rates. The system may be calibrated, using an adjustable flow-rate gas supply, a low pressure gage, and a sequence recorder. From the calibration rates, a nomograph may be made for easy reduction. Temperature correction may be added for further accuracy.

Energy transfer model and its applications of ultrasonic gas flow-meter under static and dynamic flow rates

NASA Astrophysics Data System (ADS)

Fang, Min; Xu, Ke-Jun; Zhu, Wen-Jiao; Shen, Zi-Wen

2016-01-01

Most of the ultrasonic gas flow-meters measure the gas flow rate by calculating the ultrasonic transmission time difference between the downstream and upstream. Ultrasonic energy attenuation occurs in the processes of the ultrasonic generation, conversion, transmission, and reception. Additionally, at the same time, the gas flow will also affect the ultrasonic propagation during the measurement, which results in the ultrasonic energy attenuation and the offset of ultrasonic propagation path. Thus, the ultrasonic energy received by the transducer is weaker. When the gas flow rate increases, this effect becomes more apparent. It leads to the measurement accuracy reduced, and the measurement range narrowed. An energy transfer model, where the ultrasonic gas flow-meter under without/with the gas flow, is established by adopting the statistical analysis and curve fitting based on a large amount of experimental data. The static sub model without the gas flow expresses the energy conversion efficiency of ultrasonic gas transducers, and the dynamic sub model with the gas flow reflects the energy attenuation pattern following the flow rate variations. The mathematical model can be used to determine the minimum energy of the excitation signal for meeting the requirement of specific measurement range, and predict the maximum measurable flow rate in the case of fixed energy of excitation signal. Based on the above studies, a method to enhance the excitation signal energy is proposed under the output power of the transmitting circuit being a finite value so as to extend the measurement rage of ultrasonic gas flow-meter.

The effect of microbubbles on gas-liquid mass transfer coefficient and degradation rate of COD in wastewater treatment.

PubMed

Yao, Kangning; Chi, Yong; Wang, Fei; Yan, Jianhua; Ni, Mingjiang; Cen, Kefa

2016-01-01

A commonly used aeration device at present has the disadvantages of low mass transfer rate because the generated bubbles are several millimeters in diameter which are much bigger than microbubbles. Therefore, the effect of a microbubble on gas-liquid mass transfer and wastewater treatment process was investigated. To evaluate the effect of each bubble type, the volumetric mass transfer coefficients for microbubbles and conventional bubbles were determined. The volumetric mass transfer coefficient was 0.02905 s(-1) and 0.02191 s(-1) at a gas flow rate of 0.67 L min(-1) in tap water for microbubbles and conventional bubbles, respectively. The degradation rate of simulated municipal wastewater was also investigated, using aerobic activated sludge and ozone. Compared with the conventional bubble generator, the chemical oxygen demand (COD) removal rate was 2.04, 5.9, 3.26 times higher than those of the conventional bubble contactor at the same initial COD concentration of COD 200 mg L(-1), 400 mg L(-1), and 600 mg L(-1), while aerobic activated sludge was used. For the ozonation process, the rate of COD removal using microbubble generator was 2.38, 2.51, 2.89 times of those of the conventional bubble generator. Based on the results, the effect of initial COD concentration on the specific COD degradation rate were discussed in different systems. Thus, the results revealed that microbubbles could enhance mass transfer in wastewater treatment and be an effective method to improve the degradation of wastewater.

Effects of argon gas flow rate on laser-welding.

PubMed

Takayama, Yasuko; Nomoto, Rie; Nakajima, Hiroyuki; Ohkubo, Chikahiro

2012-01-01

The purpose of this study was to evaluate the effects of the rate of argon gas flow on joint strength in the laser-welding of cast metal plates and to measure the porosity. Two cast plates (Ti and Co-Cr alloy) of the same metal were abutted and welded together. The rates of argon gas flow were 0, 5 and 10 L/min for the Co-Cr alloy, and 5 and 10 L/min for the Ti. There was a significant difference in the ratio of porosity according to the rate of argon gas flow in the welded area. Argon shielding had no significant effect on the tensile strength of Co-Cr alloy. The 5 L/min specimens showed greater tensile strength than the 10 L/min specimens for Ti. Laser welding of the Co-Cr alloy was influenced very little by argon shielding. When the rate of argon gas flow was high, joint strength decreased for Ti.

Generation of coherent terahertz radiation in ultrafast laser-gas interactionsa)

NASA Astrophysics Data System (ADS)

Kim, Ki-Yong

2009-05-01

The generation of intense terahertz radiation in ultrafast laser-gas interactions is studied on a basis of transient electron current model. When an ultrashort pulse laser's fundamental and its second harmonic fields are mixed to ionize a gas, a nonvanishing, directional photoelectron current can be produced, which simultaneously emits terahertz radiation in the far field. Here, the generation mechanism is examined with an analytic derivation and numerical simulations, in which tunneling ionization and subsequent electron motion in the combined laser field play a key role. In the simulations, three types of laser-gas interactions are considered: (i) mixing the fundamental and its second harmonic fields, (ii) mixing nonharmonic, two-color fields, and (iii) focusing single-color, few-cycle pulses. In these interactions, terahertz generation and other nonlinear effects driven by the transient current are investigated. In particular, anticorrelation between terahertz and second (or third) harmonic generation is observed and analyzed.

Gas-pressure dependence of terahertz-pulse generation in a laser-generated nitrogen plasma

NASA Astrophysics Data System (ADS)

Löffler, T.; Roskos, H. G.

2002-03-01

Far-infrared (terahertz) pulses can be generated by photoionization of electrically biased gases with amplified laser pulses [T. Löffler, F. Jacob, and H. G. Roskos, Appl. Phys. Lett. 77, 453 (2000)]. The efficiency of the generation process can be significantly increased when the absolute gas pressure is raised because it is then possible to apply higher bias fields close to the dielectric breakdown field of the gas which increases with the pressure. The dependence of the THz output on the optical pump power does not show any indication of saturation, making the plasma emitter an interesting source for THz pulses especially in conjunction with terawatt laser systems.

Detonation duct gas generator demonstration program

NASA Technical Reports Server (NTRS)

Wortman, Andrew; Brinlee, Gayl A.; Othmer, Peter; Whelan, Michael A.

1991-01-01

The feasibility of the generation of detonation waves moving periodically across high speed channel flow is experimentally demonstrated. Such waves are essential to the concept of compressing requirements and increasing the engine pressure compressor with the objective of reducing conventional compressor requirements and increasing the engine thermodynamic efficiency through isochoric energy addition. By generating transient transverse waves, rather than standing waves, shock wave losses are reduced by an order of magnitude. The ultimate objective is to use such detonation ducts downstream of a low pressure gas turbine compressor to produce a high overall pressure ratio thermodynamic cycle. A 4 foot long, 1 inch x 12 inch cross-section, detonation duct was operated in a blow-down mode using compressed air reservoirs. Liquid or vapor propane was injected through injectors or solenoid valves located in the plenum or the duct itself. Detonation waves were generated when the mixture was ignited by a row of spark plugs in the duct wall. Problems with fuel injection and mixing limited the air speeds to about Mach 0.5, frequencies to below 10 Hz, and measured pressure ratios of about 5 to 6. The feasibility of the gas dynamic compression was demonstrated and the critical problem areas were identified.

Ultrafine particles and nitrogen oxides generated by gas and electric cooking.

PubMed

Dennekamp, M; Howarth, S; Dick, C A; Cherrie, J W; Donaldson, K; Seaton, A

2001-08-01

To measure the concentrations of particles less than 100 nm diameter and of oxides of nitrogen generated by cooking with gas and electricity, to comment on possible hazards to health in poorly ventilated kitchens. Experiments with gas and electric rings, grills, and ovens were used to compare different cooking procedures. Nitrogen oxides (NO(x)) were measured by a chemiluminescent ML9841A NO(x) analyser. A TSI 3934 scanning mobility particle sizer was used to measure average number concentration and size distribution of aerosols in the size range 10-500 nm. High concentrations of particles are generated by gas combustion, by frying, and by cooking of fatty foods. Electric rings and grills may also generate particles from their surfaces. In experiments where gas burning was the most important source of particles, most particles were in the size range 15-40 nm. When bacon was fried on the gas or electric rings the particles were of larger diameter, in the size range 50-100 nm. The smaller particles generated during experiments grew in size with time because of coagulation. Substantial concentrations of NO(X) were generated during cooking on gas; four rings for 15 minutes produced 5 minute peaks of about 1000 ppb nitrogen dioxide and about 2000 ppb nitric oxide. Cooking in a poorly ventilated kitchen may give rise to potentially toxic concentrations of numbers of particles. Very high concentrations of oxides of nitrogen may also be generated by gas cooking, and with no extraction and poor ventilation, may reach concentrations at which adverse health effects may be expected. Although respiratory effects of exposure to NO(x) might be anticipated, recent epidemiology suggests that cardiac effects cannot be excluded, and further investigation of this is desirable.

Ultrafine particles and nitrogen oxides generated by gas and electric cooking

PubMed Central

Dennekamp, M; Howarth, S; Dick, C; Cherrie, J; Donaldson, K; Seaton, A

2001-01-01

OBJECTIVES—To measure the concentrations of particles less than 100 nm diameter and of oxides of nitrogen generated by cooking with gas and electricity, to comment on possible hazards to health in poorly ventilated kitchens.
METHODS—Experiments with gas and electric rings, grills, and ovens were used to compare different cooking procedures. Nitrogen oxides (NOx) were measured by a chemiluminescent ML9841A NOx analyser. A TSI 3934 scanning mobility particle sizer was used to measure average number concentration and size distribution of aerosols in the size range 10-500 nm.
RESULTS—High concentrations of particles are generated by gas combustion, by frying, and by cooking of fatty foods. Electric rings and grills may also generate particles from their surfaces. In experiments where gas burning was the most important source of particles, most particles were in the size range 15-40 nm. When bacon was fried on the gas or electric rings the particles were of larger diameter, in the size range 50-100 nm. The smaller particles generated during experiments grew in size with time because of coagulation. Substantial concentrations of NOX were generated during cooking on gas; four rings for 15 minutes produced 5 minute peaks of about 1000 ppb nitrogen dioxide and about 2000 ppb nitric oxide.
CONCLUSIONS—Cooking in a poorly ventilated kitchen may give rise to potentially toxic concentrations of numbers of particles. Very high concentrations of oxides of nitrogen may also be generated by gas cooking, and with no extraction and poor ventilation, may reach concentrations at which adverse health effects may be expected. Although respiratory effects of exposure to NOx might be anticipated, recent epidemiology suggests that cardiac effects cannot be excluded, and further investigation of this is desirable.


Keywords: cooking fuels; nitrogen oxides; ultrafine particles PMID:11452045

Gas-turbine expander power generating systems for internal needs of compressor stations of gas-main pipelines

NASA Astrophysics Data System (ADS)

Shimanov, A. A.; Biryuk, V. V.; Sheludko, L. P.; Shabanov, K. Yu.

2017-08-01

In the framework of this paper, there have been analyzed power station building methods to construct a power station for utilities for gas-main pipelines compressor stations. The application efficiency of turbo expanders in them to expand the power gas of compressor stations' gas compressor units has been shown. New schemes for gas-turbine expander power generating systems have been proposed.

Gas metal arc welding fume generation using pulsed current

DOE Office of Scientific and Technical Information (OSTI.GOV)

Castner, H.R.

1994-12-31

This paper describes a study of the effects of pulsed welding current on the amount of welding fume and ozone produced during gas metal arc welding (GMAW) using a range of welding procedures and pulse parameters. The results reported in this paper show that pulsed current can reduce GMAW fumes compared to steady current. This research also shows that welding parameters need to be properly controlled if pulsed current is to be used to reduce welding fumes. Fume and ozone generation rates were measured during this study for GMAW of mild steel using copper-coated ER70S-3 electrode wire and 95%Ar-5%CO{sub 2}more » and 85%Ar-15%CO{sub 2} shielding gases. Welds were made with both steady current and pulsed current over a wide range of welding parameters. Fume generation rates for steady current were found to be typically between 0.2 g/min and 0.8 g/min which agrees with other researchers. No significant difference was found in the chemical composition of welding fumes from pulsed current compared to the composition of fumes generated by steady current. New technology that can reduce arc welding fumes is of significant interest to a wide range of companies that use arc welding processes and this research should assist these users in evaluating the potential for the application of this technology to their own operations.« less

F-1 Gas Generator test

NASA Image and Video Library

2015-09-03

THE GAS GENERATOR TO AN F-1 ENGINE, THE MOST POWERFUL ROCKET ENGINE EVER BUILT, IS TEST-FIRED AT NASA'S MARSHALL SPACE FLIGHT CENTER IN HUNTSVILLE, ALABAMA, ON SEPT. 3. ALTHOUGH THE ENGINE WAS ORIGINALLY BUILT TO POWER THE SATURN V ROCKETS DURING AMERICA'S MISSIONS TO THE MOON, THIS TEST ARTICLE HAD NEW PARTS CREATED USING ADDITIVE MANUFACTURING, OR 3-D PRINTING, TO TEST THE VIABILITY OF THE TECHNOLOGY FOR BUILDING NEW ENGINE DESIGNS.

A pilot study to determine medical laser generated air contaminant emission rates for a simulated surgical procedure.

PubMed

Lippert, Julia F; Lacey, Steven E; Lopez, Ramon; Franke, John; Conroy, Lorraine; Breskey, John; Esmen, Nurtan; Liu, Li

2014-01-01

The U.S. Occupational Safety and Health Administration (OSHA) estimates that half a million health-care workers are exposed to laser surgical smoke each year. The purpose of this study was to establish a methodology to (1) estimate emission rates of laser-generated air contaminants (LGACs) using an emission chamber, and to (2) perform a screening study to differentiate the effects of three laser operational parameters. An emission chamber was designed, fabricated, and assessed for performance to estimate the emission rates of gases and particles associated with LGACs during a simulated surgical procedure. Two medical lasers (Holmium Yttrium Aluminum Garnet [Ho:YAG] and carbon dioxide [CO2]) were set to a range of plausible medical laser operational parameters in a simulated surgery to pyrolyze porcine skin generating plume in the emission chamber. Power, pulse repetition frequency (PRF), and beam diameter were evaluated to determine the effect of each operational parameter on emission rate using a fractional factorial design. The plume was sampled for particulate matter and seven gas phase combustion byproduct contaminants (benzene, ethylbenzene, toluene, formaldehyde, hydrogen cyanide, carbon dioxide, and carbon monoxide): the gas phase emission results are presented here. Most of the measured concentrations of gas phase contaminants were below their limit of detection (LOD), but detectable measurements enabled us to determine laser operation parameter influence on CO2 emissions. Confined to the experimental conditions of this screening study, results indicated that beam diameter was statistically significantly influential and power was marginally statistically significant to emission rates of CO2 when using the Ho:YAG laser but not with the carbon dioxide laser; PRF was not influential vis-a-vis emission rates of these gas phase contaminants.

STEAM GENERATOR FOR GAS COOLED NUCLEAR REACTORS

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

1960-03-14

A steam generator for a gas-cooled nuclear reactor is disposed inside the same pressure vessel as the reactor and has a tube system heated by the gas circulating through the reactor; the pressure vessel is double-walled, and the interspace between these two walls is filled with concrete serving as radiation shielding. The steam generator has a cylindricaIly shaped vertical casing, through which the heating gas circulates, while the tubes are arranged in a plurality of parallel horizontal planes and each of them have the shape of an involute of a circle. The tubes are uniformly distributed over the available surfacemore » in the plane, all the tubes of the same plane being connected in parallel. The exterior extremities of these involute-shaped tubes are each connected with similar tubes disposed in the adjacent lower situated plane, while the interior extremities are connected with tubes in the adjacent higher situated plane. The alimentation of the tubes is performed over annular headers. The tube system is self-supporting, the tubes being joined together by welded spacers. The fluid flow in the tubes is performed by forced circulation. (NPO)« less

Method of generating hydrogen gas from sodium borohydride

DOEpatents

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

2007-12-11

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.

Tailored ramp wave generation in gas gun experiments

NASA Astrophysics Data System (ADS)

Cotton, Matthew; Chapman, David; Winter, Ron; Harris, Ernie; Eakins, Daniel

2015-09-01

Gas guns are traditionally used as platforms to introduce a planar shock wave to a material using plate impact methods, generating states on the Hugoniot. The ability to deliver a ramp wave to a target during a gas gun experiment enables access to different regions of the equation-of-state surface, making it a valuable technique for characterising material behaviour. Previous techniques have relied on the use of multi-material impactors to generate a density gradient, which can be complex to manufacture. In this paper we describe the use of an additively manufactured steel component consisting of an array of tapered spikes which can deliver a ramp wave over ˜ 2 μs. The ability to tailor the input wave by varying the component design is discussed, an approach which makes use of the design freedom offered by additive manufacturing techniques to rapidly iterate the spike profile. Results from gas gun experiments are presented to evaluate the technique, and compared with 3D hydrodynamic simulations.

Effects of Surfactant Contamination on the Next Generation Gas Trap for the ISS Internal Thermal Control System

NASA Technical Reports Server (NTRS)

Leimkuehler, Thomas O.; Lukens, Clark; Reeves, Daniel R.; Holt, James M.

2004-01-01

The current dual-membrane gas trap is designed to remove non-condensed gas bubbles from the Internal Thermal Control System (ITCS) coolant on board the International Space Station (ISS). To date it has successfully served its purpose of preventing gas bubbles from causing depriming, overspeed, and shutdown of the ITCS pump. However, contamination in the ITCS coolant has adversely affected the gas venting rate and lifetime of the gas trap, warranting a development effort for a next-generation gas trap. Previous testing has shown that a hydrophobic-only design is capable of performing even better than the current dual-membrane design for both steady-state gas removal and gas slug removal in clean deionized water. This paper presents results of testing to evaluate the effects of surfactant contamination on the steady-state performance of the hydrophobic-only design.

Gas Generator Feedline Orifice Sizing Methodology: Effects of Unsteadiness and Non-Axisymmetric Flow

NASA Technical Reports Server (NTRS)

Rothermel, Jeffry; West, Jeffrey S.

2011-01-01

Engine LH2 and LO2 gas generator feed assemblies were modeled with computational fluid dynamics (CFD) methods at 100% rated power level, using on-center square- and round-edge orifices. The purpose of the orifices is to regulate the flow of fuel and oxidizer to the gas generator, enabling optimal power supply to the turbine and pump assemblies. The unsteady Reynolds-Averaged Navier-Stokes equations were solved on unstructured grids at second-order spatial and temporal accuracy. The LO2 model was validated against published experimental data and semi-empirical relationships for thin-plate orifices over a range of Reynolds numbers. Predictions for the LO2 square- and round-edge orifices precisely match experiment and semi-empirical formulas, despite complex feedline geometry whereby a portion of the flow from the engine main feedlines travels at a right-angle through a smaller-diameter pipe containing the orifice. Predictions for LH2 square- and round-edge orifice designs match experiment and semi-empirical formulas to varying degrees depending on the semi-empirical formula being evaluated. LO2 mass flow rate through the square-edge orifice is predicted to be 25 percent less than the flow rate budgeted in the original engine balance, which was subsequently modified. LH2 mass flow rate through the square-edge orifice is predicted to be 5 percent greater than the flow rate budgeted in the engine balance. Since CFD predictions for LO2 and LH2 square-edge orifice pressure loss coefficients, K, both agree with published data, the equation for K has been used to define a procedure for orifice sizing.

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Centrifugal bubble O2 (1Δ) gas generator with a total pressure of 100 Torr

NASA Astrophysics Data System (ADS)

Zagidulin, M. V.; Nikolaev, V. D.; Svistun, M. I.; Khvatov, N. A.

2008-08-01

A centrifugal bubbling singlet-oxygen gas generator is developed in which chlorine with helium are injected into the rotating layer of the alkali solution of hydrogen peroxide through cylindrical nozzles directed at an angle of 30° to the bubbler surface. The concentrations of water vapour and O2 (1Δ) and the gas temperature were determined by using the multichannel recording of the emission bands of oxygen at 634, 703, 762 and 1268 nm. For the chlorine and helium flow rates of 60 and 90 mmol s-1, respectively, the specific chlorine load of 3.2 mmol cm-2, a total pressure of 100 Torr in the working region of the gas generator and the oxygen partial pressure of 36 Torr, the chlorine utilisation was 90% and the content of O2 (1Δ) was ≈60%. For the ratio of the flow rates of chlorine and the alkali solution of hydrogen peroxide equal to 1 mol L-1, the water vapour content was ≈25%. The chemical efficiency of the oxygen—iodine laser with this gas generator achieved 23% for the specific power of 12.7 W cm per 1 cm3 s-1 per pass of the solution through the gas generator.

Etching Rate of Silicon Dioxide Using Chlorine Trifluoride Gas

NASA Astrophysics Data System (ADS)

Miura, Yutaka; Kasahara, Yu; Habuka, Hitoshi; Takechi, Naoto; Fukae, Katsuya

2009-02-01

The etching rate behavior of silicon dioxide (SiO2, fused silica) using chlorine trifluoride (ClF3) gas is studied at substrate temperatures between 573 and 1273 K at atmospheric pressure in a horizontal cold-wall reactor. The etching rate increases with the ClF3 gas concentration, and the overall reaction is recognized to be of the first order. The change of the etching rate with increasing substrate temperature is nonlinear, and the etching rate tends to approach a constant value at temperatures exceeding 1173 K. The overall rate constant is estimated by numerical calculation, taking into account the transport phenomena in the reactor, including the chemical reaction at the substrate surface. The activation energy obtained in this study is 45.8 kJ mol-1, and the rate constant is consistent with the measured etching rate behavior. A reactor system in which there is minimum etching of the fused silica chamber by ClF3 gas can be achieved using an IR lamp heating unit and a chamber cooling unit to maintain a sufficiently low temperature of the chamber wall.

Pulsed x-ray generator for commercial gas lasers

NASA Astrophysics Data System (ADS)

Bollanti, S.; Bonfigli, F.; Di Lazzaro, P.; Flora, F.; Giordano, G.; Letardi, T.; Murra, D.; Schina, G.; Zheng, C. E.

2001-10-01

We have designed and tested a 1-m-long x-ray diode based on innovative plasma cathodes, which exploit commercial spark plugs as electron emitters. Based on the results of a numerical study, we optimized both diode geometry (e.g., the angle between anode and cathode surfaces, the thickness of the Al window) and electrical circuitry (e.g., the capacitance in series to each spark plug, the peak voltage of the anode) of our x-ray generator. The overall result is a simple and efficient circuitry, giving a total diode current in excess of 2.1 kA with a breakdown voltage of 70 kV, which generates a 50 ns rise-time x-ray pulse with a spatially averaged dosage of up to 6×10-4 Gy when using a Pb-wrapped anode. The double-diode x-ray generator was operated for 1.5×106 shots at a repetition rate of up to 30 Hz, and the lifetime test was interrupted without any fault. During the lifetime test, it was not necessary to adjust any working parameter. At the end of the lifetime test, the x-ray emission uniformity was better than 80% along the longitudinal axis. This x-ray generator has a lifetime, reliability, and cost fitting the requirements of industrial users. Among the broad range of potential applications, this x-ray generator is particularly suitable to ionize discharge pumped gas lasers, like TEA CO2 and excimer lasers, including those operated by x-ray triggered discharges.

Enhanced late gas generation potential of petroleum source rocks via recombination reactions: Evidence from the Norwegian North Sea

NASA Astrophysics Data System (ADS)

Erdmann, Michael; Horsfield, Brian

2006-08-01

determination of kinetic parameters of the different gas generation types, which were used for extrapolations to a linear geological heating rate of 10 -11 K min -1. Peak generation temperatures for the primary gas generation were found to be higher for Heather Formation ( Tmax = 190 °C, equivalent to Ro appr. 1.7%) compared to Draupne Formation ( Tmax = 175 °C, equivalent to appr. Ro 1.3%). Secondary gas peak generation temperatures were calculated to be 220 °C for the Heather Formation and 205 to 215 °C for the Draupne Formation, respectively, with equivalent vitrinite reflectance values ( Ro) between 2.4% and 2.0%. The high temperature secondary gas formation from cracking of the recombination residue as detected for the Heather Formation is quantitatively important and is suggested to occur at very high temperatures ( Tmax approx. 250 °C) for geological heating rates. The prediction of a significant charge of dry gas from the Heather Formation at very high maturity levels has important implications for petroleum exploration in the region, especially to the north of the Viking Graben where Upper Jurassic sediments are sufficiently deep buried to have experienced such a process.

Onboard Inert Gas Generation System/Onboard Oxygen Gas Generation System (OBIGGS/OBOGS) Study. Part 1; Aircraft System Requirements

NASA Technical Reports Server (NTRS)

Reynolds, Thomas L.; Bailey, Delbert B.; Lewinski, Daniel F.; Roseburg, Conrad M.; Palaszewski, Bryan (Technical Monitor)

2001-01-01

The purpose of this technology assessment is to define a multiphase research study program investigating Onboard Inert Gas Generation Systems (OBIGGS) and Onboard Oxygen Generation Systems (OBOGS) that would identify current airplane systems design and certification requirements (Subtask 1); explore state-of-the-art technology (Subtask 2); develop systems specifications (Subtask 3); and develop an initial system design (Subtask 4). If feasible, consideration may be given to the development of a prototype laboratory test system that could potentially be used in commercial transport aircraft (Subtask 5). These systems should be capable of providing inert nitrogen gas for improved fire cargo compartment fire suppression and fuel tank inerting and emergency oxygen for crew and passenger use. Subtask I of this research study, presented herein, defines current production aircraft certification requirements and design objectives necessary to meet mandatory FAA certification requirements and Boeing design and performance specifications. These requirements will be utilized for baseline comparisons for subsequent OBIGGS/OBOGS application evaluations and assessments.

Development of the Next Generation Gas Trap for the Space Station Internal Thermal Control System

NASA Technical Reports Server (NTRS)

Leimkuehler, Thomas O.; Spelbring, Chris; Reeves, Daniel R.; Holt, James M.

2003-01-01

The current dual-membrane gas trap is designed to remove non-condensed gases (NCG) from the Internal Thermal Control System (ITCS) coolant on board the International Space Station (ISS). To date it has successfully served its purpose of preventing depriming, overspeed, and shutdown of the ITCS pump. However, contamination in the ITCS coolant has adversely affected the gas venting rate and lifetime of the gas trap, warranting a development effort for a next-generation gas trap. Design goals are to meet or exceed the current requirements to (1) include greater operating ranges and conditions, (2) eliminate reliance on the current hydrophilic tube fabrication process, and (3) increase operational life and tolerance to particulate and microbial growth fouling. In addition, the next generation gas trap will essentially be a 'dropin" design such that no modifications to the ITCS pump package assembly (PPA) will be required, and the implementation of the new design will not affect changes to the ITCS operational conditions, interfaces, or software. This paper will present the initial membrane module design and development work which has included (1) a trade study among several conceptual designs, (2) performance modeling of a hydrophobic-only design, and (3) small-scale development test data for the hydrophobic-only design. Testing has shown that the hydrophobic-only design is capable of performing even better than the current dual-membrane design for both steady-state gas removal and gas slug removal.

Thermal Analysis and Testing of Fastrac Gas Generator Design

NASA Technical Reports Server (NTRS)

Nguyen, H.

1998-01-01

The Fastrac Engine is being developed by the Marshall Space Flight Center (MSFC) to help meet the goal of substantially reducing the cost of access to space. This engine relies on a simple gas-generator cycle, which burns a small amount of RP-1 and oxygen to provide gas to drive the turbine and then exhausts the spent fuel. The Fastrac program envisions a combination of analysis, design and hot-fire evaluation testing. This paper provides the supporting thermal analysis of the gas generator design. In order to ensure that the design objectives were met, the evaluation tests have started on a component level and a total of 15 tests of different durations were completed to date at MSFC. The correlated thermal model results will also be compared against hot-fire thermocouple data gathered.

Liquid-in-gas droplet microfluidics; experimental characterization of droplet morphology, generation frequency, and monodispersity in a flow-focusing microfluidic device

NASA Astrophysics Data System (ADS)

Tirandazi, Pooyan; Hidrovo, Carlos H.

2017-07-01

Microfluidic techniques for production of uniform droplets usually rely on the use of two immiscible liquids (e.g. water-in-oil emulsions). It has been shown recently that a continuous gas flow instead of a second liquid carrier can be used as an alternative approach in droplet microfluidics. In this work we experimentally investigate the generation of liquid water droplets within air in flow-focusing configurations. Over a wide range of flow conditions we identify six distinct flow regimes inside the microchannel: Co-flowing, Threading, Plugging, Dripping, Multi-Satellite Formation, and Jetting. Flow regimes and their transitions are plotted and characterized based on the Weber number (We) of the system. We further investigate the impact of liquid microchannel size on the flow maps. Generation frequency, morphology, and monodispersity of the droplets are characterized in more detail in the Dripping regime. Generation frequency can be related to the product of the liquid and gas flow rates. However, droplet morphology (length and width) is more dependent on the gas flow rate. We demonstrate the production of monodisperse droplets (d < 100 µm and σ/d < 5 %) up to kHz formation rates in liquid-gas microfluidic systems for the first time. The results of this work provide practical and useful guidelines for precise, oil-free delivery of ultra-small volumes of fluid which can be integrated in lab-on-a-chip systems for a variety of applications in biochemical research and material synthesis.

Effects of the electrical parameters and gas flow rate on the generation of reactive species in liquids exposed to atmospheric pressure plasma jets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baek, Eun Jeong; Joh, Hea Min; Kim, Sun Ja

2016-07-15

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, N{sub 2}, and N{sub 2}{sup +} 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,more » 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.« less

Interdependence of the Electricity Generation System and the Natural Gas System and Implications for Energy Security

DTIC Science & Technology

2013-05-15

rates, but conservatively, two weeks to several months), firm delivery contracts (which are based on the capacity of the transmission pipelines and...gas is not guaranteed as it is not part of the capacity planning process). 0 20 40 60 80 100 120 0 2 4 6 8 10 12 D ur at io n of st or ag e su pp...military installations. For example, Tinker AFB, Robins AFB, and MCAGCC Twentynine Palms all have natural gas-fired generation or cogeneration on site

The upper limit of maturity of natural gas generation and its implication for the Yacheng formation in the Qiongdongnan Basin, China

NASA Astrophysics Data System (ADS)

Su, Long; Zheng, Jianjing; Chen, Guojun; Zhang, Gongcheng; Guo, Jianming; Xu, Yongchang

2012-08-01

Vitrinite reflectance (VR, Ro%) measurements from residual kerogen of pyrolysis experiments were performed on immature Maoming Oil Shale substituted the samples for the gas-prone source rocks of Yacheng formation of the Qiongdongnan Basin in the South China Sea. The work was focused on determination an upper limit of maturity for gas generation (ULMGG) or "the deadline of natural gas generation". Ro values at given temperatures increase with increasing temperature and prolonged heating time, but ΔRo-value, given a definition of the difference of all values for VR related to higher temperature and adjacent lower temperature in open-system non-isothermal experiment at the heating rate of 20 °C/min, is better than VR. And representative examples are presented in this paper. It indicates that the range of natural gas generation for Ro in the main gas generation period is from 0.96% to 2.74%, in which ΔRo is in concordance with the stage for the onset and end of the main gas generation period corresponding to 0.02% up to 0.30% and from 0.30% up to 0.80%, respectively. After the main gas generation period of 0.96-2.74%, the evolution of VR approach to the ULMGG of the whole rock for type II kerogen. It is equal to 4.38% of VR, where the gas generation rates change little with the increase of maturation, ΔRo is the maximum of 0.83% corresponding to VR of 4.38%Ro, and the source rock does not nearly occur in the end process of hydrocarbon gas generation while Ro is over 4.38%. It shows that it is the same the ULMGG from the whole rock for type II kerogen as the method with both comparison and kinetics. By comparing to both the conclusions of pyrolysis experiments and the data of VR from the source rock of Yacheng formation on a series of selected eight wells in the shallow-water continental shelf area, it indicate that the most hydrocarbon source rock is still far from reaching ULMGG from the whole rock for type II kerogen. The source rock of Yacheng formation in the

Next Generation * Natural Gas (NG)2 Information Requirements--Executive Summary

EIA Publications

2000-01-01

The Energy Information Administration (EIA) has initiated the Next Generation * Natural Gas (NG)2 project to design and implement a new and comprehensive information program for natural gas to meet customer requirements in the post-2000 time frame.

Fluid dynamics analysis of a gas attenuator for X-ray FELs under high-repetition-rate operation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Bo; Wu, Juhao; Raubenheimer, Tor O.

Newtonian fluid dynamics simulations were performed using the Navier–Stokes–Fourier formulations to elucidate the short time-scale (µs and longer) evolution of the density and temperature distributions in an argon-gas-filled attenuator for an X-ray free-electron laser under high-repetition-rate operation. Both hydrodynamic motions of the gas molecules and thermal conductions were included in a finite-volume calculation. It was found that the hydrodynamic wave motions play the primary role in creating a density depression (also known as a filament) by advectively transporting gas particles away from the X-ray laser–gas interaction region, where large pressure and temperature gradients have been built upon the initial energymore » depositionviaX-ray photoelectric absorption and subsequent thermalization. Concurrent outward heat conduction tends to reduce the pressure in the filament core region, generating a counter gas flow to backfill the filament, but on an initially slower time scale. If the inter-pulse separation is sufficiently short so the filament cannot recover, the depth of the filament progressively increases as the trailing pulses remove additional gas particles. Since the rate of hydrodynamic removal decreases while the rate of heat conduction back flow increases as time elapses, the two competing mechanisms ultimately reach a dynamic balance, establishing a repeating pattern for each pulse cycle. Finally, by performing simulations at higher repetition rates but lower per pulse energies while maintaining a constant time-averaged power, the amplitude of the hydrodynamic motion per pulse becomes smaller, and the evolution of the temperature and density distributions approach asymptotically towards, as expected, those calculated for a continuous-wave input of the equivalent power.« less

Fluid dynamics analysis of a gas attenuator for X-ray FELs under high-repetition-rate operation

DOE PAGES

Yang, Bo; Wu, Juhao; Raubenheimer, Tor O.; ...

2017-05-01

Newtonian fluid dynamics simulations were performed using the Navier–Stokes–Fourier formulations to elucidate the short time-scale (µs and longer) evolution of the density and temperature distributions in an argon-gas-filled attenuator for an X-ray free-electron laser under high-repetition-rate operation. Both hydrodynamic motions of the gas molecules and thermal conductions were included in a finite-volume calculation. It was found that the hydrodynamic wave motions play the primary role in creating a density depression (also known as a filament) by advectively transporting gas particles away from the X-ray laser–gas interaction region, where large pressure and temperature gradients have been built upon the initial energymore » depositionviaX-ray photoelectric absorption and subsequent thermalization. Concurrent outward heat conduction tends to reduce the pressure in the filament core region, generating a counter gas flow to backfill the filament, but on an initially slower time scale. If the inter-pulse separation is sufficiently short so the filament cannot recover, the depth of the filament progressively increases as the trailing pulses remove additional gas particles. Since the rate of hydrodynamic removal decreases while the rate of heat conduction back flow increases as time elapses, the two competing mechanisms ultimately reach a dynamic balance, establishing a repeating pattern for each pulse cycle. Finally, by performing simulations at higher repetition rates but lower per pulse energies while maintaining a constant time-averaged power, the amplitude of the hydrodynamic motion per pulse becomes smaller, and the evolution of the temperature and density distributions approach asymptotically towards, as expected, those calculated for a continuous-wave input of the equivalent power.« less

Methane Leak Rates from Natural Gas Wells in Norther California

NASA Astrophysics Data System (ADS)

Cui, Y.; Yoon, S.; Chen, Y.; Falk, M.; Kuwayama, T.; Croes, B. E.; Herner, J.; Vijayan, A.

2017-12-01

Methane is a potent greenhouse gas (GHG) and is the second most prevalent GHG emitted in California from human activities. As part of a comprehensive effort to reduce GHG emissions and meet the statewide climate goals, California has proposed a Short Lived Climate Pollutant (SLCP) Strategy that includes a 40% reduction of methane emissions from 2013 levels by 2030, with goals to reduce oil and gas related emissions and capture methane emissions from dairy operations and organic waste. There is growing evidence in the recent scientific literature suggesting that methane emissions can come from every stage of the oil and gas supply chain. During oil and gas production operations, studies reported that a small number of oil and gas wells made up a large fraction of total methane emissions from the wells. In such a fat-tail distribution, the mean methane leak rate from wells is orders of magnitude larger than the median, which indicates the presence of super emitter sources. However, since the super emitters are often positioned as outliers in a fat-tail distribution and do not always behave consistently, measuring their leak rates is challenging, but critical to quantify their impacts and identify potential mitigation opportunities. This presentation will discuss of methane leak rates measured from natural gas wells in Northern California for different well operations: active, idle, and plugged. The leak rates demonstrated fat-tail distributions, and the mean leak rates for each well operation status were an order of magnitude higher than the median leak rates. It was also observed that roughly 20% of wells contributed more than 80% of methane emissions. Further data collection is needed with a larger number of samples to better understand the relationship between the leak rates and well operation status. Such measurements could help improve the estimate of methane emissions from natural gas wells and inform methane reduction policies and programs in California.

Harmonization of initial estimates of shale gas life cycle greenhouse gas emissions for electric power generation.

PubMed

Heath, Garvin A; O'Donoughue, Patrick; Arent, Douglas J; Bazilian, Morgan

2014-08-05

Recent technological advances in the recovery of unconventional natural gas, particularly shale gas, have served to dramatically increase domestic production and reserve estimates for the United States and internationally. This trend has led to lowered prices and increased scrutiny on production practices. Questions have been raised as to how greenhouse gas (GHG) emissions from the life cycle of shale gas production and use compares with that of conventionally produced natural gas or other fuel sources such as coal. Recent literature has come to different conclusions on this point, largely due to differing assumptions, comparison baselines, and system boundaries. Through a meta-analytical procedure we call harmonization, we develop robust, analytically consistent, and updated comparisons of estimates of life cycle GHG emissions for electricity produced from shale gas, conventionally produced natural gas, and coal. On a per-unit electrical output basis, harmonization reveals that median estimates of GHG emissions from shale gas-generated electricity are similar to those for conventional natural gas, with both approximately half that of the central tendency of coal. Sensitivity analysis on the harmonized estimates indicates that assumptions regarding liquids unloading and estimated ultimate recovery (EUR) of wells have the greatest influence on life cycle GHG emissions, whereby shale gas life cycle GHG emissions could approach the range of best-performing coal-fired generation under certain scenarios. Despite clarification of published estimates through harmonization, these initial assessments should be confirmed through methane emissions measurements at components and in the atmosphere and through better characterization of EUR and practices.

Harmonization of initial estimates of shale gas life cycle greenhouse gas emissions for electric power generation

PubMed Central

Heath, Garvin A.; O’Donoughue, Patrick; Arent, Douglas J.; Bazilian, Morgan

2014-01-01

Recent technological advances in the recovery of unconventional natural gas, particularly shale gas, have served to dramatically increase domestic production and reserve estimates for the United States and internationally. This trend has led to lowered prices and increased scrutiny on production practices. Questions have been raised as to how greenhouse gas (GHG) emissions from the life cycle of shale gas production and use compares with that of conventionally produced natural gas or other fuel sources such as coal. Recent literature has come to different conclusions on this point, largely due to differing assumptions, comparison baselines, and system boundaries. Through a meta-analytical procedure we call harmonization, we develop robust, analytically consistent, and updated comparisons of estimates of life cycle GHG emissions for electricity produced from shale gas, conventionally produced natural gas, and coal. On a per-unit electrical output basis, harmonization reveals that median estimates of GHG emissions from shale gas-generated electricity are similar to those for conventional natural gas, with both approximately half that of the central tendency of coal. Sensitivity analysis on the harmonized estimates indicates that assumptions regarding liquids unloading and estimated ultimate recovery (EUR) of wells have the greatest influence on life cycle GHG emissions, whereby shale gas life cycle GHG emissions could approach the range of best-performing coal-fired generation under certain scenarios. Despite clarification of published estimates through harmonization, these initial assessments should be confirmed through methane emissions measurements at components and in the atmosphere and through better characterization of EUR and practices. PMID:25049378

76 FR 28971 - Atlanta Gas Light Company; Notice of Petition for Rate Approval

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-19

...] Atlanta Gas Light Company; Notice of Petition for Rate Approval Take notice that on May 9, 2011, as supplemented on May 11, 2011, Atlanta Gas Light Company (Atlanta Gas Light) filed a petition pursuant to.... Atlanta Gas Light states the rate election consists of the maximum cost-based rates approved by the...

Modeling acid-gas generation from boiling chloride brines

PubMed Central

2009-01-01

Background This study investigates the generation of HCl and other acid gases from boiling calcium chloride dominated waters at atmospheric pressure, primarily using numerical modeling. The main focus of this investigation relates to the long-term geologic disposal of nuclear waste at Yucca Mountain, Nevada, where pore waters around waste-emplacement tunnels are expected to undergo boiling and evaporative concentration as a result of the heat released by spent nuclear fuel. Processes that are modeled include boiling of highly concentrated solutions, gas transport, and gas condensation accompanied by the dissociation of acid gases, causing low-pH condensate. Results Simple calculations are first carried out to evaluate condensate pH as a function of HCl gas fugacity and condensed water fraction for a vapor equilibrated with saturated calcium chloride brine at 50-150°C and 1 bar. The distillation of a calcium-chloride-dominated brine is then simulated with a reactive transport model using a brine composition representative of partially evaporated calcium-rich pore waters at Yucca Mountain. Results show a significant increase in boiling temperature from evaporative concentration, as well as low pH in condensates, particularly for dynamic systems where partial condensation takes place, which result in enrichment of HCl in condensates. These results are in qualitative agreement with experimental data from other studies. Conclusion The combination of reactive transport with multicomponent brine chemistry to study evaporation, boiling, and the potential for acid gas generation at the proposed Yucca Mountain repository is seen as an improvement relative to previously applied simpler batch evaporation models. This approach allows the evaluation of thermal, hydrological, and chemical (THC) processes in a coupled manner, and modeling of settings much more relevant to actual field conditions than the distillation experiment considered. The actual and modeled distillation

Transition metal catalysis in the generation of petroleum and natural gas. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mango, F.D.

1997-01-21

This project originated on the premise that natural gas could be formed catalytically in the earth rather than thermally as commonly believed. The intention was to test this hypothetical view and to explore generally the role of sedimentary metals in the generation of light hydrocarbons (C1 - C9). We showed the metalliferous source rocks are indeed catalytic in the generation of natural gas. Various metal compounds in the pure state show the same levels of catalytic activity as sedimentary rocks and the products are identical. Nickel is particularly active among the early transition metals and is projected to remain catalyticallymore » robust at all stages of catagenesis. Nickel oxide promotes the formation of n-alkanes in addition to natural gas (NG), demonstrating the full scope of the hypothetical catalytic process: The composition of catalytic gas duplicates the entire range of natural gas, from so-called wet gas to dry gas (60 to 95+ wt % methane), while gas generated thermally is consistently depleted in methane (10 to 60 wt % methane). These results support the view that metal catalysis is a major pathway through which natural gas is formed in the earth.« less

Investigation of thermolytic hydrogen generation rate of tank farm simulated and actual waste

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martino, C.; Newell, D.; Woodham, W.

To support resolution of Potential Inadequacies in the Safety Analysis for the Savannah River Site (SRS) Tank Farm, Savannah River National Laboratory conducted research to determine the thermolytic hydrogen generation rate (HGR) with simulated and actual waste. Gas chromatography methods were developed and used with air-purged flow systems to quantify hydrogen generation from heated simulated and actual waste at rates applicable to the Tank Farm Documented Safety Analysis (DSA). Initial simulant tests with a simple salt solution plus sodium glycolate demonstrated the behavior of the test apparatus by replicating known HGR kinetics. Additional simulant tests with the simple salt solutionmore » excluding organics apart from contaminants provided measurement of the detection and quantification limits for the apparatus with respect to hydrogen generation. Testing included a measurement of HGR on actual SRS tank waste from Tank 38. A final series of measurements examined HGR for a simulant with the most common SRS Tank Farm organics at temperatures up to 140 °C. The following conclusions result from this testing.« less

On-site SiH4 generator using hydrogen plasma generated in slit-type narrow gap

NASA Astrophysics Data System (ADS)

Takei, Norihisa; Shinoda, Fumiya; Kakiuchi, Hiroaki; Yasutake, Kiyoshi; Ohmi, Hiromasa

2018-06-01

We have been developing an on-site silane (SiH4) generator based on use of the chemical etching reaction between solid silicon (Si) and the high-density H atoms that are generated in high-pressure H2 plasma. In this study, we have developed a slit-type plasma source for high-efficiency SiH4 generation. High-density H2 plasma was generated in a narrow slit-type discharge gap using a 2.45 GHz microwave power supply. The plasma’s optical emission intensity distribution along the slit was measured and the resulting distribution was reflected by both the electric power distribution and the hydrogen gas flow. Because the Si etching rate strongly affects the SiH4 generation rate, the Si etching behavior was investigated with respect to variations in the experimental parameters. The weight etch rate increased monotonically with increasing input microwave power. However, the weight etch rate decreased with increasing H2 pressure and an increasing plasma gap. This reduction in the etch rate appears to be related to shrinkage of the plasma generation area because increased input power is required to maintain a constant plasma area with increasing H2 pressure and the increasing plasma gap. Additionally, the weight etch rate also increases with increasing H2 flow rate. The SiH4 generation rate of the slit-type plasma source was also evaluated using gas-phase Fourier transform infrared absorption spectroscopy and the material utilization efficiencies of both Si and the H2 gas for SiH4 gas formation were discussed. The main etch product was determined to be SiH4 and the developed plasma source achieved a SiH4 generation rate of 10 sccm (standard cubic centimeters per minute) at an input power of 900 W. In addition, the Si utilization efficiency exceeded 60%.

Gas generation at a municipal waste combustor ash monofill -- Franklin, New Hampshire

DOE Office of Scientific and Technical Information (OSTI.GOV)

Musselman, C.N.; Straub, W.A.; Bidwell, J.N.

1997-12-31

The characterization of landfill gas generated at municipal solid waste landfills has received significant attention in recent years. Generation of landfill gas at municipal waste combustor ash monofills is generally assumed to be negligible and there is little, if any, published information available concerning the characteristics of gas generated at ash monofills. The lined residue landfill in Franklin, New Hampshire, USA has been accepting combined ash (bottom ash, fly ash, scrubber product from direct dry lime injection) from a 500 ton per day mass burn waste to energy facility in Concord, NH from 1989 through the present. In March, 1996,more » landfill operators noticed gaseous emissions from cleanout lines connected to the landfill`s primary leachate collection system beneath the landfilled residue. The landfill staff tested these emissions with a hand-held LEL meter, which tripped alarms for low O{sub 2} and explosiveness. Subsequently, a comprehensive program was completed to sample and analyze the gaseous emissions. Temperatures within the landfill mass were unexpectedly found to be as high as 156 F, higher than typical in an MSW landfill, presumably due to exothermic chemical reactions within the residue. Methane concentrations were found to be very low, and oxygen was present, although at depressed concentrations. Methanogenic bacterial activity does not appear to play a major role in gas generation in a residue landfill. Hydrogen gas was measured at significant concentrations. The hydrogen gas is postulated to be generated by reactions of elemental aluminum within the landfilled residue. These hydrogen generating aluminum reactions may be accelerated at elevated pH levels resulting from the presence of dry lime scrubber product. Volatile organic compounds were present in concentrations at the low end of concentrations generally reported for MSW landfills.« less

Next Generation Natural Gas Vehicle (NGNGV) program brochure

DOT National Transportation Integrated Search

2000-10-26

The U.S. Department of Energys (DOE) Office of Transportation Technologies (OTT), is responding to these national concerns. OTT has identified the development of next-generation natural gas vehicles as a strategy to reduce oil imports, vehicle pol...

Thermal-maturity limit for primary thermogenic-gas generation from humic coals as determined by hydrous pyrolysis

USGS Publications Warehouse

Lewan, Michael; Kotarba, M.J.

2014-01-01

Hydrous-pyrolysis experiments at 360°C (680°F) for 72 h were conducted on 53 humic coals representing ranks from lignite through anthracite to determine the upper maturity limit for hydrocarbon-gas generation from their kerogen and associated bitumen (i.e., primary gas generation). These experimental conditions are below those needed for oil cracking to ensure that generated gas was not derived from the decomposition of expelled oil generated from some of the coals (i.e., secondary gas generation). Experimental results showed that generation of hydrocarbon gas ends before a vitrinite reflectance of 2.0%. This reflectance is equivalent to Rock-Eval maximum-yield temperature and hydrogen indices (HIs) of 555°C (1031°F) and 35 mg/g total organic carbon (TOC), respectively. At these maturity levels, essentially no soluble bitumen is present in the coals before or after hydrous pyrolysis. The equivalent kerogen atomic H/C ratio is 0.50 at the primary gas-generation limit and indicates that no alkyl moieties are remaining to source hydrocarbon gases. The convergence of atomic H/C ratios of type-II and -I kerogen to this same value at a reflectance of indicates that the primary gas-generation limits for humic coal and type-III kerogen also apply to oil-prone kerogen. Although gas generation from source rocks does not exceed vitrinite reflectance values greater than , trapped hydrocarbon gases can remain stable at higher reflectance values. Distinguishing trapped gas from generated gas in hydrous-pyrolysis experiments is readily determined by of the hydrocarbon gases when a -depleted water is used in the experiments. Water serves as a source of hydrogen in hydrous pyrolysis and, as a result, the use of -depleted water is reflected in the generated gases but not pre-existing trapped gases.

Entropy Generation/Availability Energy Loss Analysis Inside MIT Gas Spring and "Two Space" Test Rigs

NASA Technical Reports Server (NTRS)

Ebiana, Asuquo B.; Savadekar, Rupesh T.; Patel, Kaushal V.

2006-01-01

The results of the entropy generation and availability energy loss analysis under conditions of oscillating pressure and oscillating helium gas flow in two Massachusetts Institute of Technology (MIT) test rigs piston-cylinder and piston-cylinder-heat exchanger are presented. Two solution domains, the gas spring (single-space) in the piston-cylinder test rig and the gas spring + heat exchanger (two-space) in the piston-cylinder-heat exchanger test rig are of interest. Sage and CFD-ACE+ commercial numerical codes are used to obtain 1-D and 2-D computer models, respectively, of each of the two solution domains and to simulate the oscillating gas flow and heat transfer effects in these domains. Second law analysis is used to characterize the entropy generation and availability energy losses inside the two solution domains. Internal and external entropy generation and availability energy loss results predicted by Sage and CFD-ACE+ are compared. Thermodynamic loss analysis of simple systems such as the MIT test rigs are often useful to understand some important features of complex pattern forming processes in more complex systems like the Stirling engine. This study is aimed at improving numerical codes for the prediction of thermodynamic losses via the development of a loss post-processor. The incorporation of loss post-processors in Stirling engine numerical codes will facilitate Stirling engine performance optimization. Loss analysis using entropy-generation rates due to heat and fluid flow is a relatively new technique for assessing component performance. It offers a deep insight into the flow phenomena, allows a more exact calculation of losses than is possible with traditional means involving the application of loss correlations and provides an effective tool for improving component and overall system performance.

A range of newly developed mobile generators to dynamically produce SI-traceable reference gas mixtures for reactive compounds at atmospheric concentrations

NASA Astrophysics Data System (ADS)

Leuenberger, Daiana; Pascale, Céline; Guillevic, Myriam; Ackermann, Andreas; Niederhauser, Bernhard

2017-04-01

Three new mobile facilities have been developed at METAS to dynamically generate SI-traceable reference gas mixtures for a variety of reactive compounds at atmospheric amount of substance fractions and at very low levels of uncertainty (Ux < 3%). We present three new portable "Reactive Gas Standard ReGaS" reference gas generators for the realisation of the following substances: ReGaS1: Ammonia and nitrogen dioxide in the nmol/mol (ppb) range ReGaS2: Volatile organic compounds (VOCs), e.g. limonene, alpha-pinene, MVK, MEK in the nmol/mol (ppb) range ReGaS-3: Fluorinated gases (F-gases, i.e. containing fluorine atoms) in the pmol/mol (ppt) range These three mobile generators have been designed and manufactured at METAS in the framework of the three EMRP projects MetNH3, KEY-VOCs and HIGHGAS. The method is based on permeation and subsequent dynamic dilution: A permeation tube containing the pure substance (e.g. NH3) is stored in the permeation chamber at constant temperature, pressure and matrix gas flow (N2, purified air, synthetic air). Under such conditions the pure substance permeates at constant rate into the matrix gas and can be diluted thereafter to the desired amount fractions in one or two subsequent steps. The permeation rate (mass loss over time) of the permeation tube is precisely calibrated in a fully traceable magnetic suspension balance. The carrier gas is previously purified from the compounds of interest using commercially available purification cartridges. The permeation chambers of ReGaS2 and ReGaS3 have multiple individual cells allowing for the generation of mixtures containing up to 5 different components if required. ReGaS1 allows for the generation of one-component mixtures only. These primary mixtures are then diluted to the required amount of substance fractions using thermal mass flow controllers for full flexibility and adaptability of the generation process over the entire range of possible concentrations. In order to considerably reduce

Enhanced Photoacoustic Gas Analyser Response Time and Impact on Accuracy at Fast Ventilation Rates during Multiple Breath Washout

PubMed Central

Horsley, Alex; Macleod, Kenneth; Gupta, Ruchi; Goddard, Nick; Bell, Nicholas

2014-01-01

Background The Innocor device contains a highly sensitive photoacoustic gas analyser that has been used to perform multiple breath washout (MBW) measurements using very low concentrations of the tracer gas SF6. Use in smaller subjects has been restricted by the requirement for a gas analyser response time of <100 ms, in order to ensure accurate estimation of lung volumes at rapid ventilation rates. Methods A series of previously reported and novel enhancements were made to the gas analyser to produce a clinically practical system with a reduced response time. An enhanced lung model system, capable of delivering highly accurate ventilation rates and volumes, was used to assess in vitro accuracy of functional residual capacity (FRC) volume calculation and the effects of flow and gas signal alignment on this. Results 10–90% rise time was reduced from 154 to 88 ms. In an adult/child lung model, accuracy of volume calculation was −0.9 to 2.9% for all measurements, including those with ventilation rate of 30/min and FRC of 0.5 L; for the un-enhanced system, accuracy deteriorated at higher ventilation rates and smaller FRC. In a separate smaller lung model (ventilation rate 60/min, FRC 250 ml, tidal volume 100 ml), mean accuracy of FRC measurement for the enhanced system was minus 0.95% (range −3.8 to 2.0%). Error sensitivity to flow and gas signal alignment was increased by ventilation rate, smaller FRC and slower analyser response time. Conclusion The Innocor analyser can be enhanced to reliably generate highly accurate FRC measurements down at volumes as low as those simulating infant lung settings. Signal alignment is a critical factor. With these enhancements, the Innocor analyser exceeds key technical component recommendations for MBW apparatus. PMID:24892522

Performance of a Small Gas Generator Using Liquid Hydrogen and Liquid Oxygen

NASA Technical Reports Server (NTRS)

Acker, Loren W.; Fenn, David B.; Dietrich, Marshall W.

1961-01-01

The performance and operating problems of a small hot-gas generator burning liquid hydrogen with liquid oxygen are presented. Two methods of ignition are discussed. Injector and combustion chamber design details based on rocket design criteria are also given. A carefully fabricated showerhead injector of simple design provided a gas generator that yielded combustion efficiencies of 93 and 96 percent.

Solid aerosol generator

DOEpatents

Prescott, Donald S.; Schober, Robert K.; Beller, John

1992-01-01

An improved solid aerosol generator used to produce a gas borne stream of dry, solid particles of predetermined size and concentration. The improved solid aerosol generator nebulizes a feed solution of known concentration with a flow of preheated gas and dries the resultant wet heated aerosol in a grounded, conical heating chamber, achieving high recovery and flow rates.

Measurement of gas yields and flow rates using a custom flowmeter

USGS Publications Warehouse

Circone, S.; Kirby, S.H.; Pinkston, J.C.; Stern, L.A.

2001-01-01

A simple gas collection apparatus based on the principles of a Torricelli tube has been designed and built to measure gas volume yields and flow rates. This instrument is routinely used to monitor and collect methane gas released during methane hydrate dissociation experiments. It is easily and inexpensively built, operates at ambient pressures and temperatures, and measures gas volumes of up to 7 L to a precision of about 15 ml (about 0.0025 mol). It is capable of measuring gas flow rates varying from more than 103 to less than 10-1 ml/min during gas evolution events that span minutes to several days. We have obtained a highly reproducible hydrate number of n=5.891 with a propagated uncertainty of ??0.020 for synthetic methane hydrate. ?? 2001 American Institute of Physics.

Design criteria monograph for liquid propellant gas generators

NASA Technical Reports Server (NTRS)

1974-01-01

Monograph reviews and assesses current design practices, and from them establishes firm guidance for achieving greater consistency in design, increased reliability in end product, and greater efficiency in design effort. Main emphasis of monograph is on bipropellant gas generators using hydrogen peroxide and hydrazine monopropellants.

Estimation of uncertainty in tracer gas measurement of air change rates.

PubMed

Iizuka, Atsushi; Okuizumi, Yumiko; Yanagisawa, Yukio

2010-12-01

Simple and economical measurement of air change rates can be achieved with a passive-type tracer gas doser and sampler. However, this is made more complex by the fact many buildings are not a single fully mixed zone. This means many measurements are required to obtain information on ventilation conditions. In this study, we evaluated the uncertainty of tracer gas measurement of air change rate in n completely mixed zones. A single measurement with one tracer gas could be used to simply estimate the air change rate when n = 2. Accurate air change rates could not be obtained for n ≥ 2 due to a lack of information. However, the proposed method can be used to estimate an air change rate with an accuracy of <33%. Using this method, overestimation of air change rate can be avoided. The proposed estimation method will be useful in practical ventilation measurements.

Fuel prices, emission standards, and generation costs for coal vs natural gas power plants.

PubMed

Pratson, Lincoln F; Haerer, Drew; Patiño-Echeverri, Dalia

2013-05-07

Low natural gas prices and stricter, federal emission regulations are promoting a shift away from coal power plants and toward natural gas plants as the lowest-cost means of generating electricity in the United States. By estimating the cost of electricity generation (COE) for 304 coal and 358 natural gas plants, we show that the economic viability of 9% of current coal capacity is challenged by low natural gas prices, while another 56% would be challenged by the stricter emission regulations. Under the current regulations, coal plants would again become the dominant least-cost generation option should the ratio of average natural gas to coal prices (NG2CP) rise to 1.8 (it was 1.42 in February 2012). If the more stringent emission standards are enforced, however, natural gas plants would remain cost competitive with a majority of coal plants for NG2CPs up to 4.3.

Drought Resilience of Water Supplies for Shale Gas Extraction and Related Power Generation in Texas

NASA Astrophysics Data System (ADS)

Reedy, R. C.; Scanlon, B. R.; Nicot, J. P.; Uhlman, K.

2014-12-01

There is considerable concern about water availability to support energy production in Texas, particularly considering that many of the shale plays are in semiarid areas of Texas and the state experienced the most extreme drought on record in 2011. The Eagle Ford shale play provides an excellent case study. Hydraulic fracturing water use for shale gas extraction in the play totaled ~ 12 billion gallons (bgal) in 2012, representing ~7 - 10% of total water use in the 16 county play area. The dominant source of water is groundwater which is not highly vulnerable to drought from a recharge perspective because water is primarily stored in the confined portion of aquifers that were recharged thousands of years ago. Water supply drought vulnerability results primarily from increased water use for irrigation. Irrigation water use in the Eagle Ford play was 30 billion gallons higher in the 2011 drought year relative to 2010. Recent trends toward increased use of brackish groundwater for shale gas extraction in the Eagle Ford also reduce pressure on fresh water resources. Evaluating the impacts of natural gas development on water resources should consider the use of natural gas in power generation, which now represents 50% of power generation in Texas. Water consumed in extracting the natural gas required for power generation is equivalent to ~7% of the water consumed in cooling these power plants in the state. However, natural gas production from shale plays can be overall beneficial in terms of water resources in the state because natural gas combined cycle power generation decreases water consumption by ~60% relative to traditional coal, nuclear, and natural gas plants that use steam turbine generation. This reduced water consumption enhances drought resilience of power generation in the state. In addition, natural gas combined cycle plants provide peaking capacity that complements increasing renewable wind generation which has no cooling water requirement. However, water

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.

High-Oriented Polypyrrole Nanotubes for Next-Generation Gas Sensor.

PubMed

Xue, Mianqi; Li, Fengwang; Chen, Dong; Yang, Zhanhai; Wang, Xiaowei; Ji, Junhui

2016-10-01

Highly oriented PPy nanotubes are grown by in situ vapor phase polymerization within a nanoscale template under low temperature. As-fabricated PPy nanotubes are used for gas sensing, where an ultralow detection limit (0.05 ppb) and very fast response are achieved. Such an in situ mass-productive method for synthesizing highly oriented conducting polymers may pave a new step toward next-generation gas sensors. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solid aerosol generator

DOEpatents

Prescott, D.S.; Schober, R.K.; Beller, J.

1992-03-17

An improved solid aerosol generator used to produce a gas borne stream of dry, solid particles of predetermined size and concentration is disclosed. The improved solid aerosol generator nebulizes a feed solution of known concentration with a flow of preheated gas and dries the resultant wet heated aerosol in a grounded, conical heating chamber, achieving high recovery and flow rates. 2 figs.

Generation of ozone by pulsed corona discharge over water surface in hybrid gas liquid electrical discharge reactor

NASA Astrophysics Data System (ADS)

Lukes, Petr; Clupek, Martin; Babicky, Vaclav; Janda, Vaclav; Sunka, Pavel

2005-02-01

Ozone formation by a pulse positive corona discharge generated in the gas phase between a planar high voltage electrode made from reticulated vitreous carbon and a water surface with an immersed ground stainless steel plate electrode was investigated under various operating conditions. The effects of gas flow rate (0.5-3 litre min-1), discharge gap spacing (2.5-10 mm), applied input power (2-45 W) and gas composition (oxygen containing argon or nitrogen) on ozone production were determined. Ozone concentration increased with increasing power input and with increasing discharge gap. The production of ozone was significantly affected by the presence of water vapour formed through vaporization of water at the gas-liquid interface by the action of the gas phase discharge. The highest energy efficiency for ozone production was obtained using high voltage pulses of approximately 150 ns duration in Ar/O2 mixtures with the maximum efficiency (energy yield) of 23 g kW h-1 for 40% argon content.

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.

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.

Are dialysis adequacy indices independent of solute generation rate?

PubMed

Waniewski, Jacek; Debowska, Malgorzata; Lindholm, Bengt

2014-01-01

KT/V is by definition independent of solute generation rate. Alternative dialysis adequacy indices (DAIs) such as equivalent renal clearance (EKR), standard KT/V (stdKT/V), and solute removal index (SRI) are estimated as the ratio of solute mass removed to an average solute mass in the body or solute concentration in blood; both nominator and denominator in these formulas depend on the solute generation rate. Our objective was to investigate whether and under which conditions the alternative DAIs are independent of solute generation rate. By using general compartment modeling, we show that for the metabolically stable patient (in whom the solute generated during the dialysis cycle, typically, 1 week, is equal to the solute removed from the body), DAIs estimated for the dialysis cycle are in general independent of the average solute generation rate (although they may depend on the pattern of oscillations in the generation rate). However, the alternative adequacy parameters (such as EKR, stdKT/V, and SRI) may depend on solute generation rate for metabolically unstable patients.

Counter-Rotatable Fan Gas Turbine Engine with Axial Flow Positive Displacement Worm Gas Generator

NASA Technical Reports Server (NTRS)

Giffin, Rollin George (Inventor); Murrow, Kurt David (Inventor); Fakunle, Oladapo (Inventor)

2014-01-01

A counter-rotatable fan turbine engine includes a counter-rotatable fan section, a worm gas generator, and a low pressure turbine to power the counter-rotatable fan section. The low pressure turbine maybe counter-rotatable or have a single direction of rotation in which case it powers the counter-rotatable fan section through a gearbox. The gas generator has inner and outer bodies having offset inner and outer axes extending through first, second, and third sections of a core assembly. At least one of the bodies is rotatable about its axis. The inner and outer bodies have intermeshed inner and outer helical blades wound about the inner and outer axes and extending radially outwardly and inwardly respectively. The helical blades have first, second, and third twist slopes in the first, second, and third sections respectively. A combustor section extends through at least a portion of the second section.

Comparative analysis of gas and coal-fired power generation in ultra-low emission condition using life cycle assessment (LCA)

NASA Astrophysics Data System (ADS)

Yin, Libao; Liao, Yanfen; Liu, Guicai; Liu, Zhichao; Yu, Zhaosheng; Guo, Shaode; Ma, Xiaoqian

2017-05-01

Energy consumption and pollutant emission of natural gas combined cycle power-generation (NGCC), liquefied natural gas combined cycle power-generation (LNGCC), natural gas combined heat and power generation (CHP) and ultra-supercritical power generation with ultra-low gas emission (USC) were analyzed using life cycle assessment method, pointing out the development opportunity and superiority of gas power generation in the period of coal-fired unit ultra-low emission transformation. The results show that CO2 emission followed the order: USC>LNGCC>NGCC>CHP the resource depletion coefficient of coal-fired power generation was lower than that of gas power generation, and the coal-fired power generation should be the main part of power generation in China; based on sensitivity analysis, improving the generating efficiency or shortening the transportation distance could effectively improve energy saving and emission reduction, especially for the coal-fired units, and improving the generating efficiency had a great significance for achieving the ultra-low gas emission.

A comparison of the rates of hydrocarbon generation from Lodgepole, False Bakken, and Bakken formation petroleum source rocks, Williston Basin, USA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jarvie, D.M.; Elsinger, R.J.; Inden, R.F.

1996-06-01

Recent successes in the Lodgepole Waulsortian Mound play have resulted in the reevaluation of the Williston Basin petroleum systems. It has been postulated that hydrocarbons were generated from organic-rich Bakken Formation source rocks in the Williston Basin. However, Canadian geoscientists have indicated that the Lodgepole Formation is responsible for oil entrapped in Lodgepole Formation and other Madison traps in portions of the Canadian Williston Basin. Furthermore, geoscientists in the U.S. have recently shown oils from mid-Madison conventional reservoirs in the U.S. Williston Basin were not derived from Bakken Formation source rocks. Kinetic data showing the rate of hydrocarbon formation frommore » petroleum source rocks were measured on source rocks from the Lodgepole, False Bakken, and Bakken Formations. These results show a wide range of values in the rate of hydrocarbon generation. Oil prone facies within the Lodgepole Formation tend to generate hydrocarbons earlier than the oil prone facies in the Bakken Formation and mixed oil/gas prone and gas prone facies in the Lodgepole Formation. A comparison of these source rocks using a geological model of hydrocarbon generation reveals differences in the timing of generation and the required level of maturity to generate significant amounts of hydrocarbons.« less

Automation of steam generator services at public service electric & gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cruickshank, H.; Wray, J.; Scull, D.

1995-03-01

Public Service Electric & Gas takes an aggressive approach to pursuing new exposure reduction techniques. Evaluation of historic outage exposure shows that over the last eight refueling outages, primary steam generator work has averaged sixty-six (66) person-rem, or, approximately tewenty-five percent (25%) of the general outage exposure at Salem Station. This maintenance evolution represents the largest percentage of exposure for any single activity. Because of this, primary steam generator work represents an excellent opportunity for the development of significant exposure reduction techniques. A study of primary steam generator maintenance activities demonstrated that seventy-five percent (75%) of radiation exposure was duemore » to work activities of the primary steam generator platform, and that development of automated methods for performing these activities was worth pursuing. Existing robotics systems were examined and it was found that a new approach would have to be developed. This resulted in a joint research and development project between Westinghouse and Public Service Electric & Gas to develop an automated system of accomplishing the Health Physics functions on the primary steam generator platform. R.O.M.M.R.S. (Remotely Operated Managed Maintenance Robotics System) was the result of this venture.« less

Increased traffic accident rates associated with shale gas drilling in Pennsylvania.

PubMed

Graham, Jove; Irving, Jennifer; Tang, Xiaoqin; Sellers, Stephen; Crisp, Joshua; Horwitz, Daniel; Muehlenbachs, Lucija; Krupnick, Alan; Carey, David

2015-01-01

We examined the association between shale gas drilling and motor vehicle accident rates in Pennsylvania. Using publicly available data on all reported vehicle crashes in Pennsylvania, we compared accident rates in counties with and without shale gas drilling, in periods with and without intermittent drilling (using data from 2005 to 2012). Counties with drilling were matched to non-drilling counties with similar population and traffic in the pre-drilling period. Heavily drilled counties in the north experienced 15-23% higher vehicle crash rates in 2010-2012 and 61-65% higher heavy truck crash rates in 2011-2012 than control counties. We estimated 5-23% increases in crash rates when comparing months with drilling and months without, but did not find significant effects on fatalities and major injury crashes. Heavily drilled counties in the southwest showed 45-47% higher rates of fatal and major injury crashes in 2012 than control counties, but monthly comparisons of drilling activity showed no significant differences associated with drilling. Vehicle accidents have measurably increased in conjunction with shale gas drilling. Copyright © 2014. Published by Elsevier Ltd.

Exhaustive Conversion of Inorganic Nitrogen to Nitrogen Gas Based on a Photoelectro-Chlorine Cycle Reaction and a Highly Selective Nitrogen Gas Generation Cathode.

PubMed

Zhang, Yan; Li, Jinhua; Bai, Jing; Shen, Zhaoxi; Li, Linsen; Xia, Ligang; Chen, Shuai; Zhou, Baoxue

2018-02-06

A novel method for the exhaustive conversion of inorganic nitrogen to nitrogen gas is proposed in this paper. The key properties of the system design included an exhaustive photoelectrochemical cycle reaction in the presence of Cl - , in which Cl· generated from oxidation of Cl - by photoholes selectively converted NH 4 + to nitrogen gas and some NO 3 - or NO 2 - . The NO 3 - or NO 2 - was finally reduced to nitrogen gas on a highly selective Pd-Cu-modified Ni foam (Pd-Cu/NF) cathode to achieve exhaustive conversion of inorganic nitrogen to nitrogen gas. The results indicated total nitrogen removal efficiencies of 30 mg L -1 inorganic nitrogen (NO 3 - , NH 4 + , NO 3 - /NH 4 + = 1:1 and NO 2 - /NO 3 - /NH 4 + = 1:1:1) in 90 min were 98.2%, 97.4%, 93.1%, and 98.4%, respectively, and the remaining nitrogen was completely removed by prolonging the reaction time. The rapid reduction of nitrate was ascribed to the capacitor characteristics of Pd-Cu/NF that promoted nitrate adsorption in the presence of an electric double layer, eliminating repulsion between the cathode and the anion. Nitrate was effectively removed with a rate constant of 0.050 min -1 , which was 33 times larger than that of Pt cathode. This system shows great potential for inorganic nitrogen treatment due to the high rate, low cost, and clean energy source.

Recovery Act: Johnston Rhode Island Combined Cycle Electric Generating Plant Fueled by Waste Landfill Gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Galowitz, Stephen

The primary objective of the Project was to maximize the productive use of the substantial quantities of waste landfill gas generated and collected at the Central Landfill in Johnston, Rhode Island. An extensive analysis was conducted and it was determined that utilization of the waste gas for power generation in a combustion turbine combined cycle facility was the highest and best use. The resulting project reflected a cost effective balance of the following specific sub-objectives. 1) Meet environmental and regulatory requirements, particularly the compliance obligations imposed on the landfill to collect, process and destroy landfill gas. 2) Utilize proven andmore » reliable technology and equipment. 3) Maximize electrical efficiency. 4) Maximize electric generating capacity, consistent with the anticipated quantities of landfill gas generated and collected at the Central Landfill. 5) Maximize equipment uptime. 6) Minimize water consumption. 7) Minimize post-combustion emissions. To achieve the Project Objective the project consisted of several components. 1) The landfill gas collection system was modified and upgraded. 2) A State-of-the Art gas clean up and compression facility was constructed. 3) A high pressure pipeline was constructed to convey cleaned landfill gas from the clean-up and compression facility to the power plant. 4) A combined cycle electric generating facility was constructed consisting of combustion turbine generator sets, heat recovery steam generators and a steam turbine. 5) The voltage of the electricity produced was increased at a newly constructed transformer/substation and the electricity was delivered to the local transmission system. The Project produced a myriad of beneficial impacts. 1) The Project created 453 FTE construction and manufacturing jobs and 25 FTE permanent jobs associated with the operation and maintenance of the plant and equipment. 2) By combining state-of-the-art gas clean up systems with post combustion emissions

Ensuring Reliable Natural Gas-Fired Generation with Fuel Contracts and Storage - DOE/NETL-2017/1816

DOE Office of Scientific and Technical Information (OSTI.GOV)

Myles, Paul T.; Labarbara, Kirk A.; Logan, Cecilia Elise

This report finds that natural gas-fired power plants purchase fuel both on the spot market and through firm supply contracts; there do not appear to be clear drivers propelling power plants toward one or the other type. Most natural gas-fired power generators are located near major natural gas transmission pipelines, and most natural gas contracts are currently procured on the spot market. Although there is some regional variation in the type of contract used, a strong regional pattern does not emerge. Whether gas prices are higher with spot or firm contracts varies by both region and year. Natural gas pricesmore » that push the generators higher in the supply curve would make them less likely to dispatch. Most of the natural gas generators discussed in this report would be unlikely to enter firm contracts if the agreed price would decrease their dispatch frequency. The price points at which these generators would be unlikely to enter a firm contract depends upon the region that the generator is in, and how dependent that region is on natural gas. The Electric Reliability Council of Texas (ERCOT) is more dependent on natural gas than either Eastern Interconnection or Western Interconnection. This report shows that above-ground storage is prohibitively expensive with respect to providing storage for an extended operational fuel reserve comparable to the amount of on-site fuel storage used for coal-fired plants. Further, both pressurized and atmospheric tanks require a significant amount of land for storage, even to support one day’s operation at full output. Underground storage offers the only viable option for 30-day operational storage of natural gas, and that is limited by the location of suitable geologic formations and depleted fields.« less

A Hybrid Method of Moment Equations and Rate Equations to Modeling Gas-Grain Chemistry

NASA Astrophysics Data System (ADS)

Pei, Y.; Herbst, E.

2011-05-01

Grain surfaces play a crucial role in catalyzing many important chemical reactions in the interstellar medium (ISM). The deterministic rate equation (RE) method has often been used to simulate the surface chemistry. But this method becomes inaccurate when the number of reacting particles per grain is typically less than one, which can occur in the ISM. In this condition, stochastic approaches such as the master equations are adopted. However, these methods have mostly been constrained to small chemical networks due to the large amounts of processor time and computer power required. In this study, we present a hybrid method consisting of the moment equation approximation to the stochastic master equation approach and deterministic rate equations to treat a gas-grain model of homogeneous cold cloud cores with time-independent physical conditions. In this model, we use the standard OSU gas phase network (version OSU2006V3) which involves 458 gas phase species and more than 4000 reactions, and treat it by deterministic rate equations. A medium-sized surface reaction network which consists of 21 species and 19 reactions accounts for the productions of stable molecules such as H_2O, CO, CO_2, H_2CO, CH_3OH, NH_3 and CH_4. These surface reactions are treated by a hybrid method of moment equations (Barzel & Biham 2007) and rate equations: when the abundance of a surface species is lower than a specific threshold, say one per grain, we use the ``stochastic" moment equations to simulate the evolution; when its abundance goes above this threshold, we use the rate equations. A continuity technique is utilized to secure a smooth transition between these two methods. We have run chemical simulations for a time up to 10^8 yr at three temperatures: 10 K, 15 K, and 20 K. The results will be compared with those generated from (1) a completely deterministic model that uses rate equations for both gas phase and grain surface chemistry, (2) the method of modified rate equations (Garrod

Effect of gas heating on the generation of an ultrashort avalanche electron beam in the pulse-periodic regime

NASA Astrophysics Data System (ADS)

Baksht, E. Kh.; Burachenko, A. G.; Lomaev, M. I.; Sorokin, D. A.; Tarasenko, V. F.

2015-07-01

The generation of an ultrashort avalanche electron beam (UAEB) in nitrogen in the pulse-periodic regime is investigated. The gas temperature in the discharge gap of the atmospheric-pressure nitrogen is measured from the intensity distribution of unresolved rotational transitions ( C 3Π u , v' = 0) → ( B 3Π g , v″ = 0) in the nitrogen molecule for an excitation pulse repetition rate of 2 kHz. It is shown that an increase in the UAEB current amplitude in the pulse-periodic regime is due to gas heating by a series of previous pulses, which leads to an increase in the reduced electric field strength as a result of a decrease in the gas density in the zone of the discharge formation. It is found that in the pulse-periodic regime and the formation of the diffuse discharge, the number of electrons in the beam increases by several times for a nitrogen pressure of 9 × 103 Pa. The dependences of the number of electrons in the UAEB on the time of operation of the generator are considered.

Improved solid aerosol generator

DOEpatents

Prescott, D.S.; Schober, R.K.; Beller, J.

1988-07-19

An improved solid aerosol generator used to produce a gas borne stream of dry, solid particles of predetermined size and concentration. The improved solid aerosol generator nebulizes a feed solution of known concentration with a flow of preheated gas and dries the resultant wet heated aerosol in a grounded, conical heating chamber, achieving high recovery and flow rates. 2 figs.

Testing marine shales' ability to generate catalytic gas at low temperature

NASA Astrophysics Data System (ADS)

Wei, L.; Schimmelmann, A.; Drobniak, A.; Sauer, P. E.; Mastalerz, M.

2013-12-01

Hydrocarbon gases are generally thought to originatevia low-temperature microbial or high-temperature thermogenicpathways (Whiticar, 1996) that can be distinguished by compound-specific hydrogen and carbon stable isotope ratios. An alternative low-temperature catalytic pathway for hydrocarbon generation from sedimentary organic matter has been proposed to be active at temperatures as low as 50oC (e.g.,Mango and Jarvie,2009,2010; Mango et al., 2010; Bartholomew et al., 1999). This hypothesis, however, still requires rigoroustesting by independent laboratory experiments.The possibility of catalytic generation of hydrocarbons in some source rocks (most likely in relatively impermeable and organic-rich shales where reduced catalytic centers can be best preserved) would offer an explanation for the finding of gas of non-microbial origin in formations that lack the thermal maturity for generating thermogenic gas.It is unknown whether catalytically generated methane would be isotopically different from thermogenicmethane (δ13CCH4>-50‰, δ2HCH4from -275‰ to -100‰) ormicrobially generated methane (δ13CCH4from -40‰ to -110‰, δ2HCH4from -400‰to -150‰) (Whiticar, 1998). In order to test for catalytic gas generationin water-wet shales and coals, we are conductinglaboratory experiments at three temperatures (60°C, 100°C, 200°C)and three pressures (ambient pressure, 107 Pa, 3x107 Pa)over periods of six months to several years. So far, our longest running experiments have reached one year. We sealed different types of thermally immature, pre-evacuatedshales (Mowry, New Albany, and Mahoganyshales) and coals (SpringfieldCoal and Wilcoxlignite)with isotopically defined waters in gold cells in the absence of elemental oxygen.Preliminary results show that these samples, depending on conditions, can generate light hydrocarbon gases (methane, ethane and propane) and CO2. Methane, CO2, and traces of H2havebeen generated at 60°C, whereas experiments at 100°C and 200�

Role of plasma electrons in the generation of a gas discharge plasma

NASA Astrophysics Data System (ADS)

Gruzdev, V. A.; Zalesski, V. G.; Rusetski, I. S.

2012-12-01

The role of different ionization mechanisms in penning-type gas discharges used to generate an emitting plasma in plasma electron sources is considered. It is shown that, under certain conditions, a substantial contribution to the process of gas ionization is provided by plasma electrons.

Using Probability of Exceedance to Compare the Resource Risk of Renewable and Gas-Fired Generation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bolinger, Mark

Of the myriad risks surrounding long-term investments in power plants, resource risk is one of the most difficult to mitigate, and is also perhaps the risk that most-clearly distinguishes renewable generation from natural gas-fired generation. For renewable generators like wind and solar projects, resource risk manifests as a quantity risk—i.e., the risk that the quantity of wind and insolation will be less than expected.i For gas-fired generators (i.e., a combined-cycle gas turbine or “CCGT”), resource risk manifests primarily as a price risk—i.e., the risk that natural gas will cost more than expected. Most often, resource risk—and natural gas price riskmore » in particular—falls disproportionately on utility ratepayers, who are typically not well-equipped to manage this risk. As such, it is incumbent upon utilities, regulators, and policymakers to ensure that resource risk is taken into consideration when making or approving resource decisions, or enacting policies that influence the development of the electricity sector more broadly.« less

Microscopic modeling of gas-surface scattering. I. A combined molecular dynamics-rate equation approach

NASA Astrophysics Data System (ADS)

Filinov, A.; Bonitz, M.; Loffhagen, D.

2018-06-01

A combination of first principle molecular dynamics (MD) simulations with a rate equation model (MD-RE approach) is presented to study the trapping and the scattering of rare gas atoms from metal surfaces. The temporal evolution of the atom fractions that are either adsorbed or scattered into the continuum is investigated in detail. We demonstrate that for this description one has to consider trapped, quasi-trapped and scattering states, and present an energetic definition of these states. The rate equations contain the transition probabilities between the states. We demonstrate how these rate equations can be derived from kinetic theory. Moreover, we present a rigorous way to determine the transition probabilities from a microscopic analysis of the particle trajectories generated by MD simulations. Once the system reaches quasi-equilibrium, the rates converge to stationary values, and the subsequent thermal adsorption/desorption dynamics is completely described by the rate equations without the need to perform further time-consuming MD simulations. As a proof of concept of our approach, MD simulations for argon atoms interacting with a platinum (111) surface are presented. A detailed deterministic trajectory analysis is performed, and the transition rates are constructed. The dependence of the rates on the incidence conditions and the lattice temperature is analyzed. Based on this example, we analyze the time scale of the gas-surface system to approach the quasi-stationary state. The MD-RE model has great relevance for the plasma-surface modeling as it makes an extension of accurate simulations to long, experimentally relevant time scales possible. Its application to the computation of atomic sticking probabilities is given in the second part (paper II).

Combustion Stability of the Gas Generator Assembly from J-2X Engine E10001 and Powerpack Tests

NASA Technical Reports Server (NTRS)

Hulka, J. R.; Kenny, R. L.; Casiano, M. J.

2013-01-01

Testing of a powerpack configuration (turbomachinery and gas generator assembly) and the first complete engine system of the liquid oxygen/liquid hydrogen propellant J-2X rocket engine have been completed at the NASA Stennis Space Center. The combustion stability characteristics of the gas generator assemblies on these two systems are of interest for reporting since considerable effort was expended to eliminate combustion instability during early development of the gas generator assembly with workhorse hardware. Comparing the final workhorse gas generator assembly development test data to the powerpack and engine system test data provides an opportunity to investigate how the nearly identical configurations of gas generator assemblies operate with two very different propellant supply systems one the autonomous pressure-fed test configuration on the workhorse development test stand, the other the pump-fed configurations on the powerpack and engine systems. The development of the gas generator assembly and the elimination of the combustion instability on the pressure-fed workhorse test stand have been reported extensively in the two previous Liquid Propulsion Subcommittee meetings 1-7. The powerpack and engine system testing have been conducted from mid-2011 through 2012. All tests of the powerpack and engine system gas generator systems to date have been stable. However, measureable dynamic behavior, similar to that observed on the pressure-fed test stand and reported in Ref. [6] and attributed to an injection-coupled response, has appeared in both powerpack and engine system tests. As discussed in Ref. [6], these injection-coupled responses are influenced by the interaction of the combustion chamber with a branch pipe in the hot gas duct that supplies gaseous helium to pre-spin the turbine during the start transient. This paper presents the powerpack and engine system gas generator test data, compares these data to the development test data, and provides additional

Refrigeration generation using expander-generator units

NASA Astrophysics Data System (ADS)

Klimenko, A. V.; Agababov, V. S.; Koryagin, A. V.; Baidakova, Yu. O.

2016-05-01

The problems of using the expander-generator unit (EGU) to generate refrigeration, along with electricity were considered. It is shown that, on the level of the temperatures of refrigeration flows using the EGU, one can provide the refrigeration supply of the different consumers: ventilation and air conditioning plants and industrial refrigerators and freezers. The analysis of influence of process parameters on the cooling power of the EGU, which depends on the parameters of the gas expansion process in the expander and temperatures of cooled environment, was carried out. The schematic diagram of refrigeration generation plant based on EGU is presented. The features and advantages of EGU to generate refrigeration compared with thermotransformer of steam compressive and absorption types were shown, namely: there is no need to use the energy generated by burning fuel to operate the EGU; beneficial use of the heat delivered to gas from the flow being cooled in equipment operating on gas; energy production along with refrigeration generation, which makes it possible to create, using EGU, the trigeneration plants without using the energy power equipment. It is shown that the level of the temperatures of refrigeration flows, which can be obtained by using the EGU on existing technological decompression stations of the transported gas, allows providing the refrigeration supply of various consumers. The information that the refrigeration capacity of an expander-generator unit not only depends on the parameters of the process of expansion of gas flowing in the expander (flow rate, temperatures and pressures at the inlet and outlet) but it is also determined by the temperature needed for a consumer and the initial temperature of the flow of the refrigeration-carrier being cooled. The conclusion was made that the expander-generator units can be used to create trigeneration plants both at major power plants and at small energy.

Apples with apples: accounting for fuel price risk in comparisons of gas-fired and renewable generation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bolinger, Mark; Wiser, Ryan

2003-12-18

For better or worse, natural gas has become the fuel of choice for new power plants being built across the United States. According to the US Energy Information Administration (EIA), natural gas combined-cycle and combustion turbine power plants accounted for 96% of the total generating capacity added in the US between 1999 and 2002--138 GW out of a total of 144 GW. Looking ahead, the EIA expects that gas-fired technology will account for 61% of the 355 GW new generating capacity projected to come on-line in the US up to 2025, increasing the nationwide market share of gas-fired generation frommore » 18% in 2002 to 22% in 2025. While the data are specific to the US, natural gas-fired generation is making similar advances in other countries as well. Regardless of the explanation for (or interpretation of) the empirical findings, however, the basic implications remain the same: one should not blindly rely on gas price forecasts when comparing fixed-price renewable with variable-price gas-fired generation contracts. If there is a cost to hedging, gas price forecasts do not capture and account for it. Alternatively, if the forecasts are at risk of being biased or out of tune with the market, then one certainly would not want to use them as the basis for resource comparisons or investment decisions if a more certain source of data (forwards) existed. Accordingly, assuming that long-term price stability is valued, the most appropriate way to compare the levelized cost of these resources in both cases would be to use forward natural gas price data--i.e. prices that can be locked in to create price certainty--as opposed to uncertain natural gas price forecasts. This article suggests that had utilities and analysts in the US done so over the sample period from November 2000 to November 2003, they would have found gas-fired generation to be at least 0.3-0.6 cents/kWh more expensive (on a levelized cost basis) than otherwise thought. With some renewable resources, in

Determination of Etch Rate Behavior of 4H-SiC Using Chlorine Trifluoride Gas

NASA Astrophysics Data System (ADS)

Miura, Yutaka; Habuka, Hitoshi; Katsumi, Yusuke; Oda, Satoko; Fukai, Yasushi; Fukae, Katsuya; Kato, Tomohisa; Okumura, Hajime; Arai, Kazuo

2007-12-01

The etch rate of single-crystalline 4H-SiC is studied using chlorine trifluoride gas at 673-973 K and atmospheric pressure in a cold wall horizontal reactor. The 4H-SiC etch rate can be higher than 10 μm/min at substrate temperatures higher than 723 K. The etch rate increases with the chlorine trifluoride gas flow rate. The etch rate is calculated by taking into account the transport phenomena in the reactor including the chemical reaction at the substrate surface. The flat etch rate at the higher substrate temperatures is caused mainly by the relationship between the transport rate and the surface chemical reaction rate of chlorine trifluoride gas.

Recovery Act: Brea California Combined Cycle Electric Generating Plant Fueled by Waste Landfill Gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Galowitz, Stephen

The primary objective of the Project was to maximize the productive use of the substantial quantities of waste landfill gas generated and collected at the Olinda Landfill near Brea, California. An extensive analysis was conducted and it was determined that utilization of the waste gas for power generation in a combustion turbine combined cycle facility was the highest and best use. The resulting Project reflected a cost effective balance of the following specific sub-objectives: • Meeting the environmental and regulatory requirements, particularly the compliance obligations imposed on the landfill to collect, process and destroy landfill gas • Utilizing proven andmore » reliable technology and equipment • Maximizing electrical efficiency • Maximizing electric generating capacity, consistent with the anticipated quantities of landfill gas generated and collected at the Olinda Landfill • Maximizing equipment uptime • Minimizing water consumption • Minimizing post-combustion emissions • The Project produced and will produce a myriad of beneficial impacts. o The Project created 360 FTE construction and manufacturing jobs and 15 FTE permanent jobs associated with the operation and maintenance of the plant and equipment. o By combining state-of-the-art gas clean up systems with post combustion emissions control systems, the Project established new national standards for best available control technology (BACT). o The Project will annually produce 280,320 MWh’s of clean energy o By destroying the methane in the landfill gas, the Project will generate CO2 equivalent reductions of 164,938 tons annually. The completed facility produces 27.4 MWnet and operates 24 hours a day, seven days a week.« less

Selecting Processes to Minimize Hexavalent Chromium from Stainless Steel Welding: Eight welding processes/shielding gas combinations were assessed for generation of hexavalent chromium in stainless steel welding fumes.

PubMed

Keane, M; Siert, A; Stone, S; Chen, B; Slaven, J; Cumpston, A; Antonini, J

2012-09-01

Eight welding processes/shielding gas combinations were assessed for generation of hexavalent chromium (Cr 6+ ) in stainless steel welding fumes. The processes examined were gas metal arc welding (GMAW) (axial spray, short circuit, and pulsed spray modes), flux cored arc welding (FCAW), and shielded metal arc welding (SMAW). The Cr 6+ fractions were measured in the fumes; fume generation rates, Cr 6+ generation rates, and Cr 6+ generation rates per unit mass of welding wire were determined. A limited controlled comparison study was done in a welding shop including SMAW, FCAW, and three GMAW methods. The processes studied were compared for costs, including relative labor costs. Results indicate the Cr 6+ in the fume varied widely, from a low of 2800 to a high of 34,000 ppm. Generation rates of Cr 6+ ranged from 69 to 7800 μg/min, and Cr 6+ generation rates per unit of wire ranged from 1 to 270 μg/g. The results of field study were similar to the findings in the laboratory. The Cr 6+ (ppm) in the fume did not necessarily correlate with the Cr 6+ generation rate. Physical properties were similar for the processes, with mass median aerodynamic diameters ranging from 250 to 336 nm, while the FCAW and SMAW fumes were larger (360 and 670 nm, respectively). The pulsed axial spray method was the best choice of the processes studied based on minimal fume generation, minimal Cr 6+ generation, and cost per weld. This method is usable in any position, has a high metal deposition rate, and is relatively simple to learn and use.

Rate processes in gas phase

NASA Technical Reports Server (NTRS)

Hansen, C. F.

1983-01-01

Reaction-rate theory and experiment are given a critical review from the engineers' point of view. Rates of heavy-particle, collision-induced reaction in gas phase are formulated in terms of the cross sections and activation energies for reaction. The effect of cross section function shape and of excited state contributions to reaction both cause the slope of Arrhenius plots to differ from the true activation energy, except at low temperature. The master equations for chemically reacting gases are introduced, and dissociation and ionization reactions are shown to proceed primarily from excited states about kT from the dissociation or ionization limit. Collision-induced vibration, vibration-rotation, and pure rotation transitions are treated, including three-dimensional effects and conservation of energy, which have usually been ignored. The quantum theory of transitions at potential surface crossing is derived, and results are found to be in fair agreement with experiment in spite of some questionable approximations involved.

Monopropellant engine investigation for space shuttle reaction control. Volume 2: Design, fabrication, and demonstration test of a catalytic gas generator for the space shuttle APU

NASA Technical Reports Server (NTRS)

1975-01-01

The capability of a catalytic gas generator to meet the requirement specified for the space shuttle APU is established. A full-scale gas generator, designed to operate at a chamber pressure of 750 psia and a flow rate of 0.36 lbm/sec, was fabricated and subjected to three separate life test series. The nickel foam metal used for catalyst retention was investigated. Inspection of the foam metal following the first life test revealed significant degradation. Consequently an investigation was conducted to determine the mechanism of degradation and to provide an improved foam metal.

Shale gas activity and increased rates of sexually transmitted infections in Ohio, 2000-2016.

PubMed

Deziel, Nicole C; Humeau, Zoe; Elliott, Elise G; Warren, Joshua L; Niccolai, Linda M

2018-01-01

The growing shale gas ("fracking") industry depends on a mobile workforce, whose influx could have social impacts on host communities. Sexually transmitted infections (STIs) can increase through sexual mixing patterns associated with labor migration. No prior studies have quantified the relationship between shale gas activity and rates of three reportable STIs: chlamydia, gonorrhea, and syphilis. We conducted a longitudinal, ecologic study from 2000-2016 in Ohio, situated in a prolific shale gas region in the United States (US). Data on reported cases of chlamydia, gonorrhea, and syphilis by county and year were obtained from the Ohio Department of Health. All 88 counties were classified as none, low, and high shale gas activity in each year, using data from the Ohio Department of Natural Resources. Annual rate ratios (RR) and 95% confidence intervals (95% CIs) were calculated from mixed-effects Poisson regression models evaluating the relationship between shale gas activity and reported annual STI rates while adjusting for secular trends and potential confounders obtained from the US Census. Compared to counties with no shale gas activity, counties with high activity had 21% (RR = 1.21; 95%CI = 1.08-1.36) increased rates of chlamydia and 19% (RR = 1.27; 95%CI 0.98-1.44) increased rates of gonorrhea, respectively. No association was observed for syphilis. This first report of a link between shale gas activity and increased rates of both chlamydia and gonorrhea may inform local policies and community health efforts.

CdS QDs-chitosan microcapsules with stimuli-responsive property generated by gas-liquid microfluidic technique.

PubMed

Chen, Yanjun; Yao, Rongyi; Wang, Yifeng; Chen, Ming; Qiu, Tong; Zhang, Chaocan

2015-01-01

This article describes a straightforward gas-liquid microfluidic approach to generate uniform-sized chitosan microcapsules containing CdS quantum dots (QDs). CdS QDs are encapsulated into the liquid-core of the microcapsules. The sizes of the microcapsules can be conveniently controlled by gas flow rate. QDs-chitosan microcapsules show good fluorescent stability in water, and exhibit fluorescent responses to chemical environmental stimuli. α-Cyclodextrin (α-CD) causes the microcapsules to deform and even collapse. More interestingly, α-CD induces obvious changes on the fluorescent color of the microcapsules. However, β-cyclodextrin (β-CD) has little influence on the shape and fluorescent color of the microcapsules. Based on the results of scanning electron microscopy, the possible mechanism about the effects of α-CD on the chitosan microcapsules is analyzed. These stimuli-responsive microcapsules are low-cost and easy to be prepared by gas-liquid microfluidic technique, and can be applied as a potential micro-detector to chemicals, such as CDs. Copyright © 2014 Elsevier B.V. All rights reserved.

DOE/NREL Next Generation Natural Gas Vehicle Program : an overview

DOT National Transportation Integrated Search

2001-05-14

This paper summarizes the Next Generation Natural Gas Vehicle (NG-NGV) Program that is led by the U.S. Department Of Energys (DOEs) Office of Heavy Vehicle Technologies (OHVT) through the National Renewable Energy Laboratory (NREL). The goal of...

RAETRAD MODEL OF RADON GAS GENERATION, TRANSPORT, AND INDOOR ENTRY

EPA Science Inventory

The report describes the theoretical basis, implementation, and validation of the Radon Emanation and Transport into Dwellings (RAETRAD) model, a conceptual and mathematical approach for simulating radon (222Rn) gas generation and transport from soils and building foundations to ...

Using high resolution measurements of gas tracers to determine metabolic rates in streams

NASA Astrophysics Data System (ADS)

Knapp, J. L.; Osenbrück, K.; Brennwald, M. S.; Cirpka, O. A.

2017-12-01

Hyporheic exchange and other hyporheic processes are strongly linked to stream respiration, as the majority of a streams' microorganisms are located within the streambed. Directly estimating these respiration rates on the reach scale is usually not possible, but they can indirectly be inferred from measurements of dissolved oxygen. This, however, requires determining stream reaeration rates with high precision. Conducting gas-tracer tests has been found to be the most reliable method to estimate stream reaeration, but the majority of field-based sampling techniques for tracer gases are either costly in time and materials, or imprecise. By contrast, on-site gas analysis using gas-equilibrium membrane-inlet mass spectrometers (miniRUEDI, Gasometrix GmbH [1]) avoid the errors caused by sampling, storage, and analysis in the standard sampling techniques. Furthermore, the high analytical frequency of the on-site mass-spectrometer provides concentration data exhibiting a low uncertainty. We present results from gas-tracer tests with a continuous injection of propane and noble gases as tracers in a number of small streams. The concentrations of the tracer gases are recorded continuously over time at the first measurement station to account for fluctuations of the input signal, whereas shorter sample sets are collected at all further measurement stations. Reaeration rate constants are calculated from gas measurements for individual stream sections. These rates are then used to estimate metabolic rates of respiration and primary production based on time series of oxygen measurements. To demonstrate the advancement of the method provided by the on-site analysis, results from measurements performed by on-site mass spectroscopy are compared to those from traditional headspace sampling with gas chromatography analysis. Additionally, differences in magnitude and uncertainty of the obtained reaeration rates of oxygen and calculated metabolic rates from both methods highlight the

77 FR 63311 - Acacia Natural Gas Corporation; Notice of Petition for Rate Approval

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-16

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. PR13-1-000] Acacia Natural Gas Corporation; Notice of Petition for Rate Approval Take notice that on October 9, 2012, Acacia Natural Gas Corporation (Acacia) filed a Petition for Rate Approval pursuant to 284.123(b)(2) of the...

PBX 9502 Gas Generation Progress Report FY17

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holmes, Matthew David; Erickson, Michael Andrew Englert

The self-ignition (“cookoff”) behavior of PBX 9502 depends on the dynamic evolution of gas permeability and physical damage in the material. The time-resolved measurement of product gas generation yields insight regarding the crucial properties that dominate cookoff behavior. We report on small-scale laboratory testing performed in FY17, in which small unconfined samples of PBX 9502 were heated in a small custom-built sealed pressure vessel to self-ignition. We recorded time-lapse video of the evolving physical changes in the sample, quasi-static long-duration pressure rise, then high-speed video and dynamic pressure rise of the cookoff event. We report the full pressure attained duringmore » the cookoff of a 1.02g sample in a free volume of 62.5 cm 3.« less

77 FR 70432 - Washington Gas Light Company; Notice of Petition for Rate Approval

Federal Register 2010, 2011, 2012, 2013, 2014

2012-11-26

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket Nos. PR13-6-000; PR13-7-000] Washington Gas Light Company; Notice of Petition for Rate Approval Take notice that on November 9, 2012, Washington Gas Light Company (Washington Gas) filed its Lost and unaccounted-for Gas (LAUF) as provided for...

Genetic algorithm to optimize the design of main combustor and gas generator in liquid rocket engines

NASA Astrophysics Data System (ADS)

Son, Min; Ko, Sangho; Koo, Jaye

2014-06-01

A genetic algorithm was used to develop optimal design methods for the regenerative cooled combustor and fuel-rich gas generator of a liquid rocket engine. For the combustor design, a chemical equilibrium analysis was applied, and the profile was calculated using Rao's method. One-dimensional heat transfer was assumed along the profile, and cooling channels were designed. For the gas-generator design, non-equilibrium properties were derived from a counterflow analysis, and a vaporization model for the fuel droplet was adopted to calculate residence time. Finally, a genetic algorithm was adopted to optimize the designs. The combustor and gas generator were optimally designed for 30-tonf, 75-tonf, and 150-tonf engines. The optimized combustors demonstrated superior design characteristics when compared with previous non-optimized results. Wall temperatures at the nozzle throat were optimized to satisfy the requirement of 800 K, and specific impulses were maximized. In addition, the target turbine power and a burned-gas temperature of 1000 K were obtained from the optimized gas-generator design.

Design Optimization of Gas Generator Hybrid Propulsion Boosters

NASA Technical Reports Server (NTRS)

Weldon, Vincent; Phillips, Dwight; Fink, Larry

1990-01-01

A methodology used in support of a study for NASA/MSFC to optimize the design of gas generator hybrid propulsion booster for uprating the National Space Transportation System (NSTS) is presented. The objective was to compare alternative configurations for this booster approach, optimizing each candidate concept on different bases, in order to develop data for a trade table on which a final decision was based. The methodology is capable of processing a large number of independent and dependent variables, adjusting the overall subsystems characteristics to arrive at a best compromise integrated design to meet various specific optimization criteria subject to selected constraints. For each system considered, a detailed weight statement was generated along with preliminary cost and reliability estimates.

DC Linked Hybrid Generation System with an Energy Storage Device including a Photo-Voltaic Generation and a Gas Engine Cogeneration for Residential Houses

NASA Astrophysics Data System (ADS)

Lung, Chienru; Miyake, Shota; Kakigano, Hiroaki; Miura, Yushi; Ise, Toshifumi; Momose, Toshinari; Hayakawa, Hideki

For the past few years, a hybrid generation system including solar panel and gas cogeneration is being used for residential houses. Solar panels can generate electronic power at daytime; meanwhile, it cannot generate electronic power at night time. But the power consumption of residential houses usually peaks in the evening. The gas engine cogeneration system can generate electronic power without such a restriction, and it also can generate heat power to warm up house or to produce hot water. In this paper, we propose the solar panel and gas engine co-generation hybrid system with an energy storage device that is combined by dc bus. If a black out occurs, the system still can supply electronic power for special house loads. We propose the control scheme for the system which are related with the charging level of the energy storage device, the voltage of the utility grid which can be applied both grid connected and stand alone operation. Finally, we carried out some experiments to demonstrate the system operation and calculation for loss estimation.

Dilution and permeation standards for the generation of NO, NO2 and SO2 calibration gas mixtures

NASA Astrophysics Data System (ADS)

Haerri, H.-P.; Macé, T.; Waldén, J.; Pascale, C.; Niederhauser, B.; Wirtz, K.; Stovcik, V.; Sutour, C.; Couette, J.; Waldén, T.

2017-03-01

The evaluation results of the metrological performance of a dilution and a permeation standard for generating SI-traceable calibration gas mixtures of NO, SO2 and NO2 for ambient air measurements are presented. The composition of the in situ produced reference gas mixtures is calculated from the instantaneous values of the input quantities of the generating standards. In a measurement comparison, the calibration and measurement capabilities of five laboratories were evaluated for the three analytes at limiting amount of substance fractions in ambient air between 20 and 150 nmol mol-1. For the upper generated reference values the target relative uncertainties of  ⩽2% (for NO and SO2) and  ⩽3% (for NO2) for evaluating the laboratory results were fulfilled in 12 out of 13 cases. For the analytical results seven out of nine laboratories met the criteria for the upper values for NO and NO2, for SO2 it was one out of four. From the negative degrees of equivalence of all NO2 comparison results it was supposed that the permeation rate of NO2 through the FEP polymer membrane of the permeator was different in air and N2. Subsequent precision permeation measurements with various carrier gases revealed that the permeation rate of NO2 was  ≈0.8% lower in synthetic air compared to N2. With the corrected NO2 reference values for air the degrees of equivalence of the laboratory results were improved and closer to be symmetrically distributed.

Hydrogen rich gas generator

NASA Technical Reports Server (NTRS)

Houseman, J. (Inventor)

1976-01-01

A process and apparatus is described for producing a hydrogen rich gas by introducing a liquid hydrocarbon fuel in the form of a spray into a partial oxidation region and mixing with a mixture of steam and air that is preheated by indirect heat exchange with the formed hydrogen rich gas, igniting the hydrocarbon fuel spray mixed with the preheated mixture of steam and air within the partial oxidation region to form a hydrogen rich gas.

Potential role of gas hydrate decomposition in generating submarine slope failures: Chapter 12

USGS Publications Warehouse

Pauli, Charles K.; Ussler, William III; Dillon, William P.; Max, Michael D.

2003-01-01

Gas hydrate decomposition is hypothesized to be a factor in generating weakness in continental margin sediments that may help explain some of the observed patterns of continental margin sediment instability. The processes associated with formation and decomposition of gas hydrate can cause the strengthening of sediments in which gas hydrate grow and the weakening of sediments in which gas hydrate decomposes. The weakened sediments may form horizons along which the potential for sediment failure is increased. While a causal relationship between slope failures and gas hydrate decomposition has not been proven, a number of empirical observations support their potential connection.

CONCEPTUAL MODEL FOR ORIGIN OF ABNORMALLY PRESSURED GAS ACCUMULATIONS IN LOW-PERMEABILITY RESERVOIRS.

USGS Publications Warehouse

Law, B.E.; Dickinson, W.W.

1985-01-01

The paper suggests that overpressured and underpressured gas accumulations of this type have a common origin. In basins containing overpressured gas accumulations, rates of thermogenic gas accumulation exceed gas loss, causing fluid (gas) pressure to rise above the regional hydrostatic pressure. Free water in the larger pores is forced out of the gas generation zone into overlying and updip, normally pressured, water-bearing rocks. While other diagenetic processes continue, a pore network with very low permeability develops. As a result, gas accumulates in these low-permeability reservoirs at rates higher than it is lost. In basins containing underpressured gas accumulations, rates of gas generation and accumulation are less than gas loss. The basin-center gas accumulation persists, but because of changes in the basin dynamics, the overpressured accumulation evolves into an underpressured system.

A global gas flaring black carbon emission rate dataset from 1994 to 2012

PubMed Central

Huang, Kan; Fu, Joshua S.

2016-01-01

Global flaring of associated petroleum gas is a potential emission source of particulate matters (PM) and could be notable in some specific regions that are in urgent need of mitigation. PM emitted from gas flaring is mainly in the form of black carbon (BC), which is a strong short-lived climate forcer. However, BC from gas flaring has been neglected in most global/regional emission inventories and is rarely considered in climate modeling. Here we present a global gas flaring BC emission rate dataset for the period 1994–2012 in a machine-readable format. We develop a region-dependent gas flaring BC emission factor database based on the chemical compositions of associated petroleum gas at various oil fields. Gas flaring BC emission rates are estimated using this emission factor database and flaring volumes retrieved from satellite imagery. Evaluation using a chemical transport model suggests that consideration of gas flaring emissions can improve model performance. This dataset will benefit and inform a broad range of research topics, e.g., carbon budget, air quality/climate modeling, and environmental/human exposure. PMID:27874852

A global gas flaring black carbon emission rate dataset from 1994 to 2012

NASA Astrophysics Data System (ADS)

Huang, Kan; Fu, Joshua S.

2016-11-01

Global flaring of associated petroleum gas is a potential emission source of particulate matters (PM) and could be notable in some specific regions that are in urgent need of mitigation. PM emitted from gas flaring is mainly in the form of black carbon (BC), which is a strong short-lived climate forcer. However, BC from gas flaring has been neglected in most global/regional emission inventories and is rarely considered in climate modeling. Here we present a global gas flaring BC emission rate dataset for the period 1994-2012 in a machine-readable format. We develop a region-dependent gas flaring BC emission factor database based on the chemical compositions of associated petroleum gas at various oil fields. Gas flaring BC emission rates are estimated using this emission factor database and flaring volumes retrieved from satellite imagery. Evaluation using a chemical transport model suggests that consideration of gas flaring emissions can improve model performance. This dataset will benefit and inform a broad range of research topics, e.g., carbon budget, air quality/climate modeling, and environmental/human exposure.

Valuing natural gas power generation assets in the new competitive marketplace

NASA Astrophysics Data System (ADS)

Hsu, Michael Chun-Wei

1999-10-01

The profitability of natural gas fired power plants depends critically on the spread between electricity and natural gas prices. The price levels of these two energy commodities are the key uncertain variables in determining the operating margin and therefore the value of a power plant. The owner of a generation unit has the decision of dispatching the plant only when profit margins are positive. This operating flexibility is a real option with real value. In this dissertation I introduce the spark spread call options and illustrate how such paper contracts replicate the uncertain payoff space facing power asset owners and, therefore, how the financial options framework can be applied in estimating the value of natural gas generation plants. The intrinsic value of gas power plants is approximated as the sum of a series of spark spread call options with succeeding maturity dates. The Black-Scholes spread option pricing model, with volatility and correlation term structure adjustments, is utilized to price the spark spread options. Sensitivity analysis is also performed on the BS spread option formulation to compare different asset types. In addition I explore the potential of using compound and compound-exchange option concepts to evaluate, respectively, the benefits of delaying investment in new generation and in repowering existing antiquated units. The compound option designates an option on top of another option. In this case the series of spark spread call options is the 'underlying' option while the option to delay new investments is the 'overlying.' The compound-exchange option characterizes the opportunity to 'exchange' the old power plant, with its series of spark spread call options, for a set of new spark spread call options that comes with the new generation unit. The strike price of the compound-exchange option is the repowering capital investment and typically includes the purchase of new steam generators and combustion turbines, as well as other

Durability Challenges for Next Generation of Gas Turbine Engine Materials

NASA Technical Reports Server (NTRS)

Misra, Ajay K.

2012-01-01

Aggressive fuel burn and carbon dioxide emission reduction goals for future gas turbine engines will require higher overall pressure ratio, and a significant increase in turbine inlet temperature. These goals can be achieved by increasing temperature capability of turbine engine hot section materials and decreasing weight of fan section of the engine. NASA is currently developing several advanced hot section materials for increasing temperature capability of future gas turbine engines. The materials of interest include ceramic matrix composites with 1482 - 1648 C temperature capability, advanced disk alloys with 815 C capability, and low conductivity thermal barrier coatings with erosion resistance. The presentation will provide an overview of durability challenges with emphasis on the environmental factors affecting durability for the next generation of gas turbine engine materials. The environmental factors include gaseous atmosphere in gas turbine engines, molten salt and glass deposits from airborne contaminants, impact from foreign object damage, and erosion from ingestion of small particles.

25 CFR 213.23 - Royalty rates for minerals other than oil and gas.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 25 Indians 1 2012-04-01 2011-04-01 true Royalty rates for minerals other than oil and gas. 213.23 Section 213.23 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR ENERGY AND MINERALS LEASING OF... Royalty rates for minerals other than oil and gas. Unless otherwise authorized by the Commissioner of...

Generation and delivery device for ozone gas and ozone dissolved in water

NASA Technical Reports Server (NTRS)

Andrews, Craig C. (Inventor); Murphy, Oliver J. (Inventor)

2004-01-01

The present invention provides an ozone generation and delivery system that lends itself to small scale applications and requires very low maintenance. The system preferably includes an anode reservoir and a cathode phase separator each having a hydrophobic membrane to allow phase separation of produced gases from water. The hydrogen gas, ozone gas and water containing ozone may be delivered under pressure.

Generation and characterization of gas bubbles in liquid metals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eckert, S.; Gerbeth, G.; Witke, W.

1996-06-01

There is an ongoing research performed in the RCR on local transport phenomena in turbulent liquid metal (LM) duct flows exposed to external magnetic fields. In this context so-called MHD flow phenomena can be observed, which are unknown in usual hydraulic engineering. The field of interest covers also the influence of magnetic fields on the behaviour of liquid metal - gas mixtures. Profound knowledge on these LMMHD two-phase flow plays an important role in a variety of technological applications, in particular, in the design of Liquid-Metal MHD generators or for several metallurgical processes employing gas-stirred reactors. However, the highly empiricalmore » nature of two-phase flow analysis gives little hope for the prediction of MHD two-phase flows without extensive experimental data. A summary is given about the authors research activities focussing on two directions: (a) Momentum transfer between gas and liquid metal in a bubbly flow regime to investigate the influence of the external magnetic field on the velocity slip ration S (b) Peculiarities of the MHD turbulence to use small gas bubbles as local tracers in order to study the turbulent mass transfer.« less

Investigation of the rates of surface and bulk ROS-generating reactions using indigo dye as an indicator

NASA Astrophysics Data System (ADS)

Anderson, Carly; Clark, Douglas; Graves, David

2014-10-01

We present evidence for the existence of two distinct processes that contribute to the generation of reactive oxygen and nitrogen species (RONS) in liquids exposed to cold atmospheric plasma (CAP) in air. At the plasma-liquid interface, there exists a fast surface reaction zone where RONS from the gas phase interact with species in the liquid. RONS can also be produced by ``slow'' chemical reactions in the bulk liquid, even long after plasma exposure. To separate the effects of these processes, we used indigo dye as an indicator of ROS production; specifically generation of hydroxyl radical. The rate of indigo decolorization while in direct contact with CAP is compared with the expected rate of hydroxyl radical generation at the liquid surface. When added to aqueous solutions after CAP exposure, indigo dye reacts on a time scale consistent with the production of peroxynitrous acid, ONOOH, which is known to decompose to hydroxyl radical below a pH of 6.8. In this study, the CAP used was a air corona discharge plasma run in a positive streamer mode.

Effects of microbial processes on gas generation under expected WIPP repository conditions: Annual report through 1992

DOE Office of Scientific and Technical Information (OSTI.GOV)

Francis, A.J.; Gillow, J.B.

1993-09-01

Microbial processes involved in gas generation from degradation of the organic constituents of transuranic waste under conditions expected at the Waste Isolation Pilot Plant (WIPP) repository are being investigated at Brookhaven National Laboratory. These laboratory studies are part of the Sandia National Laboratories -- WIPP Gas Generation Program. Gas generation due to microbial degradation of representative cellulosic waste was investigated in short-term (< 6 months) and long-term (> 6 months) experiments by incubating representative paper (filter paper, paper towels, and tissue) in WIPP brine under initially aerobic (air) and anaerobic (nitrogen) conditions. Samples from the WIPP surficial environment and undergroundmore » workings harbor gas-producing halophilic microorganisms, the activities of which were studied in short-term experiments. The microorganisms metabolized a variety of organic compounds including cellulose under aerobic, anaerobic, and denitrifying conditions. In long-term experiments, the effects of added nutrients (trace amounts of ammonium nitrate, phosphate, and yeast extract), no nutrients, and nutrients plus excess nitrate on gas production from cellulose degradation.« less

Design optimization of gas generator hybrid propulsion boosters

NASA Technical Reports Server (NTRS)

Weldon, Vincent; Phillips, Dwight U.; Fink, Lawrence E.

1990-01-01

A methodology used in support of a contract study for NASA/MSFC to optimize the design of gas generator hybrid propulsion booster for uprating the National Space Transportation System (NSTS) is presented. The objective was to compare alternative configurations for this booster approach, optimizing each candidate concept on different bases, in order to develop data for a trade table on which a final decision was based. The methodology is capable of processing a large number of independent and dependent variables, adjusting the overall subsystems characteristics to arrive at a best compromise integrated design to meet various specified optimization criteria subject to selected constraints. For each system considered, a detailed weight statement was generated along with preliminary cost and reliability estimates.

Long arc stabilities with various arc gas flow rates

NASA Astrophysics Data System (ADS)

Maruyama, K.; Takeda, K.; Sugimoto, M.; Noguchi, Y.

2014-11-01

A new arc torch for use in magnetically driven arc device was developed with a commercially available TIG welding arc torch. The torch has a water-cooling system to the torch nozzle and has a nozzle nut to supply a swirling-free plasma gas flow. Its endurance against arc thermal load is examined. Features of its generated arc are investigated.

Integrally geared and integrated turbine generator energy recovery for high pressure natural gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Agahi, R.R.; Ershaghi, B.; Moser, H.

1995-12-31

Recovery of pressure let-down energy dates back to the early 1980`s. Several installations have proven the feasibility and attractive pay back of using turbine generator system in lieu of throttling valves. These installations, on average, are saving up to 200,000 barrels of fuel oil per year. Since the first installation, many improvements have been implemented in turboexpander packages and the associated control systems. Based on site requirements, two alternate designs may be introduced. One is a totally encapsulated integral turboexpander generator unit. The other is an integrally geared turboexpander. Both alternatives have the flexibility necessary to cope with a widemore » range of inlet gas conditions while maintaining required outlet gas conditions. These installations are environmentally friendly (no hazardous gas leakage) and operate within an acceptable noise level.« less

[Measurement of pancreatic microcirculation using hydrogen gas generated by electrolysis in dogs].

PubMed

Nishiwaki, H; Satake, K; Ko, I; Tanaka, H; Kanazawa, G; Nagai, Y; Umeyama, K

1986-11-01

Measurements of pancreatic microflow were investigated using hydrogen gas generated by electrolysis in dog. After laparatomy under general anesthesia, uncinate process of the pancreas was punctured by a needle electrode for electrolysis and determination of hydrogen gas. The consecutive measurements of pancreatic microflow revealed the good reproducibility at the same point of the pancreas. The simultaneous measurements of pancreatic microflow by electrolysis and pancreatic tissue blood flow by H2 inhalation method were carried out at the same point of the pancreas. Correlation analysis of both measurements revealed coefficient of 0.751 and a significant relationship was observed (p less than 0.05). However, the value was a little higher in pancreatic microflow as compared with pancreatic tissue blood flow. Pancreatic microflow and pancreatic exocrine secretion increased after intravenous administration of Dopamine and Secretin (10 micrograms/kg/min). It is concluded that the measurement of pancreatic microflow by hydrogen gas generated by electrolysis is a useful method on understanding the microcirculation of the pancreas.

Air quality impacts of projections of natural gas-fired distributed generation

NASA Astrophysics Data System (ADS)

Horne, Jeremy R.; Carreras-Sospedra, Marc; Dabdub, Donald; Lemar, Paul; Nopmongcol, Uarporn; Shah, Tejas; Yarwood, Greg; Young, David; Shaw, Stephanie L.; Knipping, Eladio M.

2017-11-01

This study assesses the potential impacts on emissions and air quality from the increased adoption of natural gas-fired distributed generation of electricity (DG), including displacement of power from central power generation, in the contiguous United States. The study includes four major tasks: (1) modeling of distributed generation market penetration; (2) modeling of central power generation systems; (3) modeling of spatially and temporally resolved emissions; and (4) photochemical grid modeling to evaluate the potential air quality impacts of increased DG penetration, which includes both power-only DG and combined heat and power (CHP) units, for 2030. Low and high DG penetration scenarios estimate the largest penetration of future DG units in three regions - New England, New York, and California. Projections of DG penetration in the contiguous United States estimate 6.3 GW and 24 GW of market adoption in 2030 for the low DG penetration and high DG penetration scenarios, respectively. High DG penetration (all of which is natural gas-fired) serves to offset 8 GW of new natural gas combined cycle (NGCC) units, and 19 GW of solar photovoltaic (PV) installations by 2030. In all scenarios, air quality in the central United States and the northwest remains unaffected as there is little to no DG penetration in those states. California and several states in the northeast are the most impacted by emissions from DG units. Peak increases in maximum daily 8-h average ozone concentrations exceed 5 ppb, which may impede attainment of ambient air quality standards. Overall, air quality impacts from DG vary greatly based on meteorological conditions, proximity to emissions sources, the number and type of DG installations, and the emissions factors used for DG units.

Flow-rate independent gas-mixing system for drift chambers, using solenoid valves

NASA Astrophysics Data System (ADS)

Sugano, K.

1991-03-01

We describe an inexpensive system for mixing argon and ethane gas for drift chambers which was used for an experiment at Fermilab. This system is based on the idea of intermittent mixing of gases with fixed mixing flow rates. A dual-action pressure switch senses the pressure in a mixed gas reservoir tank and operates solenoid valves to control mixing action and regulate reservoir pressure. This system has the advantages that simple controls accurately regulate the mixing ratio and that the mixing ratio is nearly flow-rate independent without readjustments. We also report the results of the gas analysis of various samplings, and the reliability of the system in long-term running.

Energy metabolism, body composition, and urea generation rate in hemodialysis patients.

PubMed

Sridharan, Sivakumar; Vilar, Enric; Berdeprado, Jocelyn; Farrington, Ken

2013-10-01

Hemodialysis (HD) adequacy is currently assessed using normalized urea clearance (Kt/V), although scaling based on Watson volume (V) may disadvantage women and men with low body weight. Alternative scaling factors such as resting energy expenditure and high metabolic rate organ mass have been suggested. The relationship between such factors and uremic toxin generation has not been established. We aimed to study the relationship between body size, energy metabolism, and urea generation rate. A cross-sectional cohort of 166 HD patients was studied. Anthropometric measurements were carried on all. Resting energy expenditure was measured by indirect calorimetry, fat-free mass by bio-impedance and total energy expenditure by combining resting energy expenditure with a questionnaire-derived physical activity data. High metabolic rate organ mass was calculated using a published equation and urea generation rate using formal urea kinetic modeling. Metabolic factors including resting energy expenditure, total energy expenditure and fat-free mass correlated better with urea generation rate than did Watson volume. Total energy expenditure and fat-free mass (but not Watson Volume) were independent predictors of urea generation rate, the model explaining 42% of its variation. Small women (generation rate per kg than women with higher V. Similarly urea generation rate normalized to fat-free mass was significantly greater in small women than in all others (significant only in comparison to larger men). Exercise-related energy expenditure correlated significantly with urea generation rate. Energy metabolism, body composition and physical activity play important roles in small solute uremic toxin generation in HD patients and hence may impact on minimum dialysis requirements. Small women generate relatively more small solute toxins than other groups and thus may have a higher relative need for dialysis. © 2013 The Authors. Hemodialysis

Hydrogen generation from natural gas for the fuel cell systems of tomorrow

NASA Astrophysics Data System (ADS)

Dicks, Andrew L.

In most cases hydrogen is the preferred fuel for use in the present generation of fuel cells being developed for commercial applications. Of all the potential sources of hydrogen, natural gas offers many advantages. It is widely available, clean, and can be converted to hydrogen relatively easily. When catalytic steam reforming is used to generate hydrogen from natural gas, it is essential that sulfur compounds in the natural gas are removed upstream of the reformer and various types of desulfurisation processes are available. In addition, the quality of fuel required for each type of fuel cell varies according to the anode material used, and the cell temperature. Low temperature cells will not tolerate high concentrations of carbon monoxide, whereas the molten fuel cell (MCFC) and solid oxide fuel cell (SOFC) anodes contain nickel on which it is possible to electrochemically oxidise carbon monoxide directly. The ability to internally reform fuel gas is a feature of the MCFC and SOFC. Internal reforming can give benefits in terms of increased electrical efficiency owing to the reduction in the required cell cooling and therefore parasitic system losses. Direct electrocatalysis of hydrocarbon oxidation has been the elusive goal of fuel cell developers over many years and recent laboratory results are encouraging. This paper reviews the principal methods of converting natural gas into hydrogen, namely catalytic steam reforming, autothermic reforming, pyrolysis and partial oxidation; it reviews currently available purification techniques and discusses some recent advances in internal reforming and the direct use of natural gas in fuel cells.

Shale gas activity and increased rates of sexually transmitted infections in Ohio, 2000–2016

PubMed Central

Humeau, Zoe; Elliott, Elise G.; Warren, Joshua L.; Niccolai, Linda M.

2018-01-01

Background The growing shale gas (“fracking”) industry depends on a mobile workforce, whose influx could have social impacts on host communities. Sexually transmitted infections (STIs) can increase through sexual mixing patterns associated with labor migration. No prior studies have quantified the relationship between shale gas activity and rates of three reportable STIs: chlamydia, gonorrhea, and syphilis. Methods We conducted a longitudinal, ecologic study from 2000–2016 in Ohio, situated in a prolific shale gas region in the United States (US). Data on reported cases of chlamydia, gonorrhea, and syphilis by county and year were obtained from the Ohio Department of Health. All 88 counties were classified as none, low, and high shale gas activity in each year, using data from the Ohio Department of Natural Resources. Annual rate ratios (RR) and 95% confidence intervals (95% CIs) were calculated from mixed-effects Poisson regression models evaluating the relationship between shale gas activity and reported annual STI rates while adjusting for secular trends and potential confounders obtained from the US Census. Results Compared to counties with no shale gas activity, counties with high activity had 21% (RR = 1.21; 95%CI = 1.08–1.36) increased rates of chlamydia and 19% (RR = 1.27; 95%CI 0.98–1.44) increased rates of gonorrhea, respectively. No association was observed for syphilis. Conclusion This first report of a link between shale gas activity and increased rates of both chlamydia and gonorrhea may inform local policies and community health efforts. PMID:29570712

A three-dimensional algebraic grid generation scheme for gas turbine combustors with inclined slots

NASA Technical Reports Server (NTRS)

Yang, S. L.; Cline, M. C.; Chen, R.; Chang, Y. L.

1993-01-01

A 3D algebraic grid generation scheme is presented for generating the grid points inside gas turbine combustors with inclined slots. The scheme is based on the 2D transfinite interpolation method. Since the scheme is a 2D approach, it is very efficient and can easily be extended to gas turbine combustors with either dilution hole or slot configurations. To demonstrate the feasibility and the usefulness of the technique, a numerical study of the quick-quench/lean-combustion (QQ/LC) zones of a staged turbine combustor is given. Preliminary results illustrate some of the major features of the flow and temperature fields in the QQ/LC zones. Formation of co- and counter-rotating bulk flow and shape temperature fields can be observed clearly, and the resulting patterns are consistent with experimental observations typical of the confined slanted jet-in-cross flow. Numerical solutions show the method to be an efficient and reliable tool for generating computational grids for analyzing gas turbine combustors with slanted slots.

Slurry growth, gas retention, and flammable gas generation by Hanford radioactive waste tanks: Synthetic waste studies, FY 1991

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bryan, S.A.; Pederson, L.R.; Ryan, J.L.

1992-08-01

Of 177 high-level waste storage tanks on the Hanford Site, 23 have been placed on a safety watch list because they are suspected of producing flammable gases in flammable or explosive concentrate. One tankin particular, Tank 241-SY-101 (Tank 101-SY), has exhibited slow increases in waste volume followed by a rapid decrease accompanied by venting of large quantities of gases. The purpose of this study is to help determine the processes by which flammable gases are produced, retained, and eventually released from Tank 101-SY. Waste composition data for single- and double-shell waste tanks on the flammable gas watch listare critically reviewed.more » The results of laboratory studies using synthetic double-shell wastes are summarized, including physical and chemical properties of crusts that are formed, the stoichiometry and rate ofgas generation, and mechanisms responsible for formation of a floating crust.« less

Hydrogen rich gas generator

NASA Technical Reports Server (NTRS)

Houseman, J.; Rupe, J. H.; Kushida, R. O. (Inventor)

1976-01-01

A process and apparatus is described for producing a hydrogen rich gas by injecting air and hydrocarbon fuel at one end of a cylindrically shaped chamber to form a mixture and igniting the mixture to provide hot combustion gases by partial oxidation of the hydrocarbon fuel. The combustion gases move away from the ignition region to another region where water is injected to be turned into steam by the hot combustion gases. The steam which is formed mixes with the hot gases to yield a uniform hot gas whereby a steam reforming reaction with the hydrocarbon fuel takes place to produce a hydrogen rich gas.

Feasibility of flare gas reformation to practical energy in Farashband gas refinery: no gas flaring.

PubMed

Rahimpour, Mohammad Reaza; Jokar, Seyyed Mohammad

2012-03-30

A suggested method for controlling the level of hazardous materials in the atmosphere is prevention of combustion in flare. In this work, three methods are proposed to recover flare gas instead of conventional gas-burning in flare at the Farashband gas refinery. These methods aim to minimize environmental and economical disadvantages of burning flare gas. The proposed methods are: (1) gas to liquid (GTL) production, (2) electricity generation with a gas turbine and, (3) compression and injection into the refinery pipelines. To find the most suitable method, the refinery units that send gas to the flare as well as the required equipment for the three aforementioned methods are simulated. These simulations determine the amount of flare gas, the number of GTL barrels, the power generated by the gas turbine and the required compression horsepower. The results of simulation show that 563 barrels/day of valuable GTL products is produced by the first method. The second method provides 25 MW electricity and the third method provides a compressed natural gas with 129 bar pressure for injection to the refinery pipelines. In addition, the economics of flare gas recovery methods are studied and compared. The results show that for the 4.176MMSCFD of gas flared from the Farashband gas refinery, the electricity production gives the highest rate of return (ROR), the lowest payback period, the highest annual profit and mild capital investment. Therefore, the electricity production is the superior method economically. Copyright © 2012 Elsevier B.V. All rights reserved.

A comparison between tracer gas and aerosol particles distribution indoors: The impact of ventilation rate, interaction of airflows, and presence of objects.

PubMed

Bivolarova, M; Ondráček, J; Melikov, A; Ždímal, V

2017-11-01

The study investigated the separate and combined effects of ventilation rate, free convection flow produced by a thermal manikin, and the presence of objects on the distribution of tracer gas and particles in indoor air. The concentration of aerosol particles and tracer gas was measured in a test room with mixing ventilation. Three layouts were arranged: an empty room, an office room with an occupant sitting in front of a table, and a single-bed hospital room. The room occupant was simulated by a thermal manikin. Monodisperse particles of three sizes (0.07, 0.7, and 3.5 μm) and nitrous oxide tracer gas were generated simultaneously at the same location in the room. The particles and gas concentrations were measured in the bulk room air, in the breathing zone of the manikin, and in the exhaust air. Within the breathing zone of the sitting occupant, the tracer gas emerged as reliable predictor for the exposure to all different-sized test particles. A change in the ventilation rate did not affect the difference in concentration distribution between tracer gas and larger particle sizes. Increasing the room surface area did not influence the similarity in the dispersion of the aerosol particles and the tracer gas. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Generation and delivery device for ozone gas and ozone dissolved in water

NASA Technical Reports Server (NTRS)

Andrews, Craig C. (Inventor); Murphy, Oliver J. (Inventor)

2006-01-01

The present invention provides an ozone generation and delivery system that lends itself to small scale applications and requires very low maintenance. The system includes an anode reservoir and a cathode phase separator each having a hydrophobic membrane to allow phase separation of produced gases from water. The system may be configured to operate passively with no moving parts or in a self-pressurizing manner with the inclusion of a pressure controlling device or valve in the gas outlet of the anode reservoir. The hydrogen gas, ozone gas and water containing ozone may be delivered under pressure.

Generation and delivery device for ozone gas and ozone dissolved in water

NASA Technical Reports Server (NTRS)

Andrews, Craig C. (Inventor); Rogers, Thomas D. (Inventor); Murphy, Oliver J. (Inventor)

1999-01-01

The present invention provides an ozone generation and delivery system that lends itself to small scale applications and requires very low maintenance. The system includes an anode reservoir and a cathode phase separator each having a hydrophobic membrane to allow phase separation of produced gases from water. The system may be configured to operate passively with no moving parts or in a self-pressurizing manner with the inclusion of a pressure controlling device or valve in the gas outlet of the anode reservoir. The hydrogen gas, ozone gas and water containing ozone may be delivered under pressure.

Angle-resolved photoemission spectroscopy with 9-eV photon-energy pulses generated in a gas-filled hollow-core photonic crystal fiber

NASA Astrophysics Data System (ADS)

Bromberger, H.; Ermolov, A.; Belli, F.; Liu, H.; Calegari, F.; Chávez-Cervantes, M.; Li, M. T.; Lin, C. T.; Abdolvand, A.; Russell, P. St. J.; Cavalleri, A.; Travers, J. C.; Gierz, I.

2015-08-01

A recently developed source of ultraviolet radiation, based on optical soliton propagation in a gas-filled hollow-core photonic crystal fiber, is applied here to angle-resolved photoemission spectroscopy (ARPES). Near-infrared femtosecond pulses of only few μJ energy generate vacuum ultraviolet radiation between 5.5 and 9 eV inside the gas-filled fiber. These pulses are used to measure the band structure of the topological insulator Bi2Se3 with a signal to noise ratio comparable to that obtained with high order harmonics from a gas jet. The two-order-of-magnitude gain in efficiency promises time-resolved ARPES measurements at repetition rates of hundreds of kHz or even MHz, with photon energies that cover the first Brillouin zone of most materials.

Hydroxyl radical generation in electro-Fenton process with a gas-diffusion electrode: Linkages with electro-chemical generation of hydrogen peroxide and iron redox cycle.

PubMed

Yatagai, Tomonori; Ohkawa, Yoshiko; Kubo, Daichi; Kawase, Yoshinori

2017-01-02

The hydroxyl radical generation in an electro-Fenton process with a gas-diffusion electrode which is strongly linked with electro-chemical generation of hydrogen peroxide and iron redox cycle was studied. The OH radical generation subsequent to electro-chemical generations of H 2 O 2 was examined under the constant potential in the range of Fe 2+ dosage from 0 to 1.0 mM. The amount of generated OH radical initially increased and gradually decreased after the maximum was reached. The initial rate of OH radical generation increased for the Fe 2+ dosage <0.25 mM and at higher Fe 2+ dosages remained constant. At higher Fe 2+ dosages the precipitation of Fe might inhibit the enhancement of OH radical generation. The experiments for decolorization and total organic carbon (TOC) removal of azo-dye Orange II by the electro-Fenton process were conducted and the quick decolorization and slow TOC removal of Orange II were found. To quantify the linkages of OH radical generation with dynamic behaviors of electro-chemically generated H 2 O 2 and iron redox cycle and to investigate effects of OH radical generation on the decolorization and TOC removal of Orange II, novel reaction kinetic models were developed. The proposed models could satisfactory clarify the linkages of OH radical generation with electro-chemically generated H 2 O 2 and iron redox cycle and simulate the decolorization and TOC removal of Orange II by the electro-Fenton process.

Design study of an advanced gas generator. [which can be ignited during start-up period of turbine engines

NASA Technical Reports Server (NTRS)

Kim, S.; Trinh, H. P.

1993-01-01

A gas generator which can be ignited reliably during the initial start-up period and offers fairly uniform gas temperature at the exit was studied numerically. Various sizes and shapes of the mixing enhancement devices and their positions were examined to evaluate the uniformity of the exit gas temperature and the change of internal pressure drop incurred by introducing the mixing enhancement devices. By introducing a turbulence ring and a splash plate with an appropriate size and position, it was possible to obtain fairly uniform gas temperature distributions and a maximum gas temperature that is within the design limit temperature of 1600 R at the generator exit. However, with the geometry studied, the pressure drop across the generator was great, approximately 1150 psi, to satisfy the assigned design limit temperature. If the design limit temperature is increased to 1650 R, the pressure drop across the generator could be lowered by as much as 350 psi.

Effects of flow rate and gas mixture on the welfare of weaned and neonate pigs during gas euthanasia.

PubMed

Sadler, L J; Hagen, C D; Wang, C; Widowski, T M; Johnson, A K; Millman, S T

2014-02-01

The objectives of this study were to assess efficacy and welfare implications of gas euthanasia when applied to weaned and neonate pigs. Parameters associated with welfare, which were measured before loss of consciousness, included open-mouth breathing, ataxia, righting response, and escape attempts. Two age groups (weaned and neonate) were assessed in 9 gas treatments arranged in a 2 × 4 factorial design, with 2 gas types (CO2 = 100% CO2 and 50:50 = 50:50 CO2:argon) and 4 flow rates (box volume exchange/min: slow = 20%; medium = 35%; fast = 50%; prefill = prefilled followed by 20%) and a control treatment in which ambient air was passed through the box. Pig pairs (10/treatment) were placed in a modified Euthanex AgPro system (Euthanex Corp., Palmer, PA). Behavioral and physiological responses were observed directly and from video recordings for latency, duration, prevalence (percent of pigs affected), and frequency (number of occurrences/pig). Data were analyzed as linear mixed models or with a Cox proportional hazard model as appropriate. Piglet pair was the experimental unit. For the weaned pig, welfare was superior with CO2 relative to 50:50 within 1 or more flow rates on the basis of reduced duration of open-mouth breathing, duration of ataxia, frequency of escape attempts, and duration and frequency of righting response (P < 0.05). No measured parameters indicated superior welfare with the use of 50:50, whereas latencies to loss of posture and last movement favored CO2 (P < 0.05). Faster flow rates were associated with reduced (P < 0.05) duration or frequency of open-mouth breathing, ataxia, and righting response, as well as superior (P < 0.05) indicators of efficacy, including latencies to loss of posture, gasping, and last movement, relative to slower flow rates. Weaned pigs were more likely to defecate (P < 0.01), display nasal discharge (P < 0.05), and display longer (P < 0.001) latencies to loss of posture and last movement than neonates. Duration of

Nondestructive Evaluation of the J-2X Direct Metal Laser Sintered Gas Generator Discharge Duct

NASA Technical Reports Server (NTRS)

Esther, Elizabeth A.; Beshears, Ronald D.; Lash, Rhonda K.

2012-01-01

The J-2X program at NASA's Marshall Space Flight Center (MSFC) procured a direct metal laser sintered (DMLS) gas generator discharge duct from Pratt & Whitney Rocketdyne and Morris Technologies for a test program that would evaluate the material properties and durability of the duct in an engine-like environment. DMLS technology was pursued as a manufacturing alternative to traditional techniques, which used off nominal practices to manufacture the gas generator duct's 180 degree turn geometry. MSFC's Nondestructive Evaluation (NDE) Team performed radiographic, ultrasonic, computed tomographic, and fluorescent penetrant examinations of the duct. Results from the NDE examinations reveal some shallow porosity but no major defects in the as-manufactured material. NDE examinations were also performed after hot-fire testing the gas generator duct and yielded similar results pre and post-test and showed no flaw growth or development.

Energy policy act transportation study: Interim report on natural gas flows and rates

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1995-11-17

This report, Energy Policy Act Transportation Study: Interim Report on Natural Gas Flows and Rates, is the second in a series mandated by Title XIII, Section 1340, ``Establishment of Data Base and Study of Transportation Rates,`` of the Energy Policy Act of 1992 (P.L. 102--486). The first report Energy Policy Act Transportation Study: Availability of Data and Studies, was submitted to Congress in October 1993; it summarized data and studies that could be used to address the impact of legislative and regulatory actions on natural gas transportation rates and flow patterns. The current report presents an interim analysis of naturalmore » gas transportation rates and distribution patterns for the period from 1988 through 1994. A third and final report addressing the transportation rates and flows through 1997 is due to Congress in October 2000. This analysis relies on currently available data; no new data collection effort was undertaken. The need for the collection of additional data on transportation rates will be further addressed after this report, in consultation with the Congress, industry representatives, and in other public forums.« less

Combustion Stability Analyses for J-2X Gas Generator Development

NASA Technical Reports Server (NTRS)

Hulka, J. R.; Protz, C. S.; Casiano, M. J.; Kenny, R. J.

2010-01-01

The National Aeronautics and Space Administration (NASA) is developing a liquid oxygen/liquid hydrogen rocket engine for upper stage and trans-lunar applications of the Ares vehicles for the Constellation program. This engine, designated the J-2X, is a higher pressure, higher thrust variant of the Apollo-era J-2 engine. Development was contracted to Pratt & Whitney Rocketdyne in 2006. Over the past several years, development of the gas generator for the J-2X engine has progressed through a variety of workhorse injector, chamber, and feed system configurations. Several of these configurations have resulted in injection-coupled combustion instability of the gas generator assembly at the first longitudinal mode of the combustion chamber. In this paper, the longitudinal mode combustion instabilities observed on the workhorse test stand are discussed in detail. Aspects of this combustion instability have been modeled at the NASA Marshall Space Flight Center with several codes, including the Rocket Combustor Interaction Design and Analysis (ROCCID) code and a new lumped-parameter MatLab model. To accurately predict the instability characteristics of all the chamber and injector geometries and test conditions, several features of the submodels in the ROCCID suite of calculations required modification. Finite-element analyses were conducted of several complicated combustion chamber geometries to determine how to model and anchor the chamber response in ROCCID. A large suite of sensitivity calculations were conducted to determine how to model and anchor the injector response in ROCCID. These modifications and their ramification for future stability analyses of this type are discussed in detail. The lumped-parameter MatLab model of the gas generator assembly was created as an alternative calculation to the ROCCID methodology. This paper also describes this model and the stability calculations.

Getting the gas out - developing gas networks in magmatic systems

NASA Astrophysics Data System (ADS)

Cashman, Katharine; Rust, Alison; Oppenheimer, Julie; Belien, Isolde

2015-04-01

Volcanic eruption style, and explosive potential, are strongly controlled by the pre-eruptive history of the magmatic volatiles: specifically, the more efficient the gas loss prior to eruption, the lower the likelihood of primary (magmatic) explosive activity. Commonly considered gas loss mechanisms include separated flow, where individual bubbles (or bubble clouds) travel at a rate that is faster than the host magma, and permeable flow, where gas escapes through permeable (connected) pathways developed within a (relatively) static matrix. Importantly, gas loss via separated flow is episodic, while gas loss via permeable flow is likely to be continuous. Analogue experiments and numerical models on three phase (solid-liquid-gas) systems also suggest a third mechanism of gas loss that involves the opening and closing of 'pseudo fractures'. Pseudo fractures form at a critical crystallinity that is close to the maximum particle packing. Fractures form by local rearrangement of solid particles and liquid to form a through-going gas fracture; gas escape is episodic, and modulated by the available gas volume and the rate of return flow of interstitial liquid back into the fracture. In all of the gas escape scenarios described above, a fundamental control on gas behaviour is the melt viscosity, which affects the rate of individual bubble rise, the rate of bubble expansion, the rate of film thinning (required for bubble coalescence), and the rate of melt flow into gas-generated fractures. From the perspective of magma degassing, rates of gas expansion and film thinning are key to the formation of an interconnected (permeable) gas pathway. Experiments with both analogue and natural materials show that bubble coalescence is relatively slow, and, in particle-poor melts, does not necessarily create permeable gas networks. As a result, degassing efficiency is modulated by the time scales required either (1) to produce large individual bubbles or bubble clouds (in low viscosity

Biocidal Defeat Agents Produced by Silver-Iodine Nanoenergetic Gas Generators

NASA Astrophysics Data System (ADS)

Davila, Ivan

Nanostructured aluminum (Al), iodine pentoxide (I2O5) nano-rods, and silver oxide (Ag2O) nanoparticles, (Al-I2O5-Ag 2O) were used to compose the ternary thermite composition that serves as a Nanoenergetic Gas Generator (NGG). This composition produces biocidal gases giving the mixture the ability to destroy highly pathogenic microorganisms or bacteria. The dissemination of the biocidal gas in combustion chamber was observed using a high-speed camera. The testing of NGG combustion process against the living Escherichia coli (E.coli) K-12 strain cells, that were cultivated/placed on the sample/chamber surfaces, demonstrated that iodine and silver atoms clouds were deposited to the bacteria surface. The 10/75/15 wt % of I2O5/Ag2O/Al composition demonstrated the best performance for destroying of E.coli with efficiency over 99 %. The results of the experiments showed that gaseous silver and iodine generated from NGG combustion produces a strong biocidal environment that has a great potential to neutralize highly pathogenic microorganisms and bacteria.

Numerical study of the generation of runaway electrons in a gas diode with a hot channel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lisenkov, V. V., E-mail: lisenkov@iep.uran.ru; Ural Federal University, 19 Mira St., Ekaterinburg 620002; Shklyaev, V. A., E-mail: shklyaev@to.hcei.tsc.ru

2015-11-15

A new method for increasing the efficiency of runaway electron beam generation in atmospheric pressure gas media has been suggested and theoretically proved. The method consists of creating a hot region (e.g., a spark channel or a laser plume) with a decreased numerical density of gas molecules (N) near the cathode. In this method, the ratio E/N (E—electric field strength) is increased by decreasing N instead of increasing E, as has been done in the past. The numerical model that is used allows the simultaneous calculation of the formation of a subnanosecond gas discharge and the generation of runaway electronsmore » in gas media. The calculations have demonstrated the possibility of obtaining current pulses of runaway electrons with amplitudes of hundred of amperes and durations of more than 100 ps. The influence of the hot channel geometry on the parameters of the generated beam has been investigated.« less

Committing to coal and gas: Long-term contracts, regulation, and fuel switching in power generation

NASA Astrophysics Data System (ADS)

Rice, Michael

Fuel switching in the electricity sector has important economic and environmental consequences. In the United States, the increased supply of gas during the last decade has led to substantial switching in the short term. Fuel switching is constrained, however, by the existing infrastructure. The power generation infrastructure, in turn, represents commitments to specific sources of energy over the long term. This dissertation explores fuel contracts as the link between short-term price response and long-term plant investments. Contracting choices enable power plant investments that are relationship-specific, often regulated, and face uncertainty. Many power plants are subject to both hold-up in investment and cost-of-service regulation. I find that capital bias is robust when considering either irreversibility or hold-up due to the uncertain arrival of an outside option. For sunk capital, the rental rate is inappropriate for determining capital bias. Instead, capital bias depends on the regulated rate of return, discount rate, and depreciation schedule. If policies such as emissions regulations increase fuel-switching flexibility, this can lead to capital bias. Cost-of-service regulation can shorten the duration of a long-term contract. From the firm's perspective, the existing literature provides limited guidance when bargaining and writing contracts for fuel procurement. I develop a stochastic programming framework to optimize long-term contracting decisions under both endogenous and exogenous sources of hold-up risk. These typically include policy changes, price shocks, availability of fuel, and volatility in derived demand. For price risks, the optimal contract duration is the moment when the expected benefits of the contract are just outweighed by the expected opportunity costs of remaining in the contract. I prove that imposing early renegotiation costs decreases contract duration. Finally, I provide an empirical approach to show how coal contracts can limit

Life cycle greenhouse gas emissions from U.S. liquefied natural gas exports: implications for end uses.

PubMed

Abrahams, Leslie S; Samaras, Constantine; Griffin, W Michael; Matthews, H Scott

2015-03-03

This study analyzes how incremental U.S. liquefied natural gas (LNG) exports affect global greenhouse gas (GHG) emissions. We find that exported U.S. LNG has mean precombustion emissions of 37 g CO2-equiv/MJ when regasified in Europe and Asia. Shipping emissions of LNG exported from U.S. ports to Asian and European markets account for only 3.5-5.5% of precombustion life cycle emissions, hence shipping distance is not a major driver of GHGs. A scenario-based analysis addressing how potential end uses (electricity and industrial heating) and displacement of existing fuels (coal and Russian natural gas) affect GHG emissions shows the mean emissions for electricity generation using U.S. exported LNG were 655 g CO2-equiv/kWh (with a 90% confidence interval of 562-770), an 11% increase over U.S. natural gas electricity generation. Mean emissions from industrial heating were 104 g CO2-equiv/MJ (90% CI: 87-123). By displacing coal, LNG saves 550 g CO2-equiv per kWh of electricity and 20 g per MJ of heat. LNG saves GHGs under upstream fugitive emissions rates up to 9% and 5% for electricity and heating, respectively. GHG reductions were found if Russian pipeline natural gas was displaced for electricity and heating use regardless of GWP, as long as U.S. fugitive emission rates remain below the estimated 5-7% rate of Russian gas. However, from a country specific carbon accounting perspective, there is an imbalance in accrued social costs and benefits. Assuming a mean social cost of carbon of $49/metric ton, mean global savings from U.S. LNG displacement of coal for electricity generation are $1.50 per thousand cubic feet (Mcf) of gaseous natural gas exported as LNG ($.028/kWh). Conversely, the U.S. carbon cost of exporting the LNG is $1.80/Mcf ($.013/kWh), or $0.50-$5.50/Mcf across the range of potential discount rates. This spatial shift in embodied carbon emissions is important to consider in national interest estimates for LNG exports.

Analytical investigation of thermal barrier coatings on advanced power generation gas turbines

NASA Technical Reports Server (NTRS)

Amos, D. J.

1977-01-01

An analytical investigation of present and advanced gas turbine power generation cycles incorporating thermal barrier turbine component coatings was performed. Approximately 50 parametric points considering simple, recuperated, and combined cycles (including gasification) with gas turbine inlet temperatures from current levels through 1644K (2500 F) were evaluated. The results indicated that thermal barriers would be an attractive means to improve performance and reduce cost of electricity for these cycles. A recommended thermal barrier development program has been defined.

Gas hydrate formation rates from dissolved-phase methane in porous laboratory specimens

USGS Publications Warehouse

Waite, William F.; Spangenberg, E.K.

2013-01-01

Marine sands highly saturated with gas hydrates are potential energy resources, likely forming from methane dissolved in pore water. Laboratory fabrication of gas hydrate-bearing sands formed from dissolved-phase methane usually requires 1–2 months to attain the high hydrate saturations characteristic of naturally occurring energy resource targets. A series of gas hydrate formation tests, in which methane-supersaturated water circulates through 100, 240, and 200,000 cm3 vessels containing glass beads or unconsolidated sand, show that the rate-limiting step is dissolving gaseous-phase methane into the circulating water to form methane-supersaturated fluid. This implies that laboratory and natural hydrate formation rates are primarily limited by methane availability. Developing effective techniques for dissolving gaseous methane into water will increase formation rates above our observed (1 ± 0.5) × 10−7 mol of methane consumed for hydrate formation per minute per cubic centimeter of pore space, which corresponds to a hydrate saturation increase of 2 ± 1% per day, regardless of specimen size.

Gas-fired power in the UK: Bridging supply gaps and implications of domestic shale gas exploitation for UK climate change targets.

PubMed

Turk, Jeremy K; Reay, David S; Haszeldine, R Stuart

2018-03-01

There is a projected shortcoming in the fourth carbon budget of 7.5%. This shortfall may be increased if the UK pursues a domestic shale gas industry to offset projected decreases in traditional gas supply. Here we estimate that, if the project domestic gas supply gap for power generation were to be met by UK shale gas with low fugitive emissions (0.08%), an additional 20.4MtCO 2 e 1 would need to be accommodated during carbon budget periods 3-6. We find that a modest fugitive emissions rate (1%) for UK shale gas would increase global emissions compared to importing an equal quantity of Qatari liquefied natural gas. Additionally, we estimate that natural gas electricity generation would emit 420-466MtCO 2 e (460 central estimate) during the same time period within the traded EU emissions cap. We conclude that domestic shale gas production with even a modest 1% fugitive emissions rate would risk exceedance of UK carbon budgets. We also highlight that, under the current production-based greenhouse gas accounting system, the UK is incentivized to import natural gas rather than produce it domestically. Copyright © 2017 Elsevier B.V. All rights reserved.

Air-water Gas Exchange Rates on a Large Impounded River Measured Using Floating Domes (Poster)

EPA Science Inventory

Mass balance models of dissolved gases in rivers typically serve as the basis for whole-system estimates of greenhouse gas emission rates. An important component of these models is the exchange of dissolved gases between air and water. Controls on gas exchange rates (K) have be...

Developing models for the prediction of hospital healthcare waste generation rate.

PubMed

Tesfahun, Esubalew; Kumie, Abera; Beyene, Abebe

2016-01-01

An increase in the number of health institutions, along with frequent use of disposable medical products, has contributed to the increase of healthcare waste generation rate. For proper handling of healthcare waste, it is crucial to predict the amount of waste generation beforehand. Predictive models can help to optimise healthcare waste management systems, set guidelines and evaluate the prevailing strategies for healthcare waste handling and disposal. However, there is no mathematical model developed for Ethiopian hospitals to predict healthcare waste generation rate. Therefore, the objective of this research was to develop models for the prediction of a healthcare waste generation rate. A longitudinal study design was used to generate long-term data on solid healthcare waste composition, generation rate and develop predictive models. The results revealed that the healthcare waste generation rate has a strong linear correlation with the number of inpatients (R(2) = 0.965), and a weak one with the number of outpatients (R(2) = 0.424). Statistical analysis was carried out to develop models for the prediction of the quantity of waste generated at each hospital (public, teaching and private). In these models, the number of inpatients and outpatients were revealed to be significant factors on the quantity of waste generated. The influence of the number of inpatients and outpatients treated varies at different hospitals. Therefore, different models were developed based on the types of hospitals. © The Author(s) 2015.

Cascading of Fluctuations in Interdependent Energy Infrastructures. Gas-Grid Coupling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chertkov, Michael; Lebedev, Vladimir; Backhaus, Scott N.

2014-09-05

The revolution of hydraulic fracturing has dramatically increased the supply and lowered the cost of natural gas in the United States driving an expansion of natural gas-fired generation capacity in many electrical grids. Unrelated to the natural gas expansion, lower capital costs and renewable portfolio standards are driving an expansion of intermittent renewable generation capacity such as wind and photovoltaic generation. These two changes may potentially combine to create new threats to the reliability of these interdependent energy infrastructures. Natural gas-fired generators are often used to balance the fluctuating output of wind generation. However, the time-varying output of these generatorsmore » results in time-varying natural gas burn rates that impact the pressure in interstate transmission pipelines. Fluctuating pressure impacts the reliability of natural gas deliveries to those same generators and the safety of pipeline operations. We adopt a partial differential equation model of natural gas pipelines and use this model to explore the effect of intermittent wind generation on the fluctuations of pressure in natural gas pipelines. The mean square pressure fluctuations are found to grow linearly in time with points of maximum deviation occurring at the locations of flow reversals.« less

Performance Prediction and Simulation of Gas Turbine Engine Operation for Aircraft, Marine, Vehicular, and Power Generation

DTIC Science & Technology

2007-02-01

gas turbine systems is the Brayton cycle that passes atmospheric air, the working fluid, through the turbine only once. The thermodynamic steps of the... Brayton cycle include compression of atmospheric air, introduction and ignition of fuel, and expansion of the heated combustion gases through the...the two heat recovery steam generators to generate steam. The gas turbine model is built by connecting the individual components of the Brayton

Megawatt low-temperature DC plasma generator with divergent channels of gas-discharge tract

NASA Astrophysics Data System (ADS)

Gadzhiev, M. Kh.; Isakaev, E. Kh.; Tyuftyaev, A. S.; Yusupov, D. I.; Sargsyan, M. A.

2017-04-01

We have developed and studied a new effective megawatt double-unit generator of low-temperature argon plasma, which belongs to the class of dc plasmatrons and comprises the cathode and anode units with divergent gas-discharge channels. The generator has an efficiency of about 80-85% and ensures a long working life at operating currents up to 4000 A.

Transition metal catalysis in the generation of petroleum and natural gas. Final report, September 1, 1992--October 31, 1995

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mango, F.D.

1997-01-21

This project originated on the premise that natural gas could be formed catalytically in the earth rather than thermally as commonly believed. The intention was to test this hypothetical view and to explore generally the role of sedimentary metals in the generation of light hydrocarbons (C1 - C9). We showed the metalliferous source rocks are indeed catalytic in the generation of natural gas. Various metal compounds in the pure state show the same levels of catalytic activity as sedimentary rocks and the products are identical. Nickel is particularly active among the early transition metals and is projected to remain catalyticallymore » robust at all stages of catagenesis. Nickel oxide promotes the formation of n-alkanes in addition to natural gas (NG), demonstrating the full scope of the hypothetical catalytic process. The composition of catalytic gas duplicates the entire range of natural gas, from so-called wet gas to dry gas (60 to 95+ wt % methane), while gas generated thermally is consistently depleted in methane (10 to 60 wt % methane). These results support the view that metal catalysis is a major pathway through which natural gas is formed in the earth.« less

ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT: BIOQUELL, INC. CLARIS C HYDROGEN PEROXIDE GAS GENERATOR

EPA Science Inventory

The Environmental Technology Verification report discusses the technology and performance of the Clarus C Hydrogen Peroxide Gas Generator, a biological decontamination device manufactured by BIOQUELL, Inc. The unit was tested by evaluating its ability to decontaminate seven types...

Measurement of generation-dependent proliferation rates and death rates during mouse erythroid progenitor cell differentiation.

PubMed

Akbarian, Vahe; Wang, Weijia; Audet, Julie

2012-05-01

Herein, we describe an experimental and computational approach to perform quantitative carboxyfluorescein diacetate succinimidyl ester (CFSE) cell-division tracking in cultures of primary colony-forming unit-erythroid (CFU-E) cells, a hematopoietic progenitor cell type, which is an important target for the treatment of blood disorders and for the manufacture of red blood cells. CFSE labeling of CFU-Es isolated from mouse fetal livers was performed to examine the effects of stem cell factor (SCF) and erythropoietin (EPO) in culture. We used a dynamic model of proliferation based on the Smith-Martin representation of the cell cycle to extract proliferation rates and death rates from CFSE time-series. However, we found that to accurately represent the cell population dynamics in differentiation cultures of CFU-Es, it was necessary to develop a model with generation-specific rate parameters. The generation-specific rates of proliferation and death were extracted for six generations (G(0) -G(5) ) and they revealed that, although SCF alone or EPO alone supported similar total cell outputs in culture, stimulation with EPO resulted in significantly higher proliferation rates from G(2) to G(5) and higher death rates in G(2) , G(3) , and G(5) compared with SCF. In addition, proliferation rates tended to increase from G(1) to G(5) in cultures supplemented with EPO and EPO + SCF, while they remained lower and more constant across generations with SCF. The results are consistent with the notion that SCF promotes CFU-E self-renewal while EPO promotes CFU-E differentiation in culture. Copyright © 2012 International Society for Advancement of Cytometry.

Advances in Thermal Spray Coatings for Gas Turbines and Energy Generation: A Review

NASA Astrophysics Data System (ADS)

Hardwicke, Canan U.; Lau, Yuk-Chiu

2013-06-01

Functional coatings are widely used in energy generation equipment in industries such as renewables, oil and gas, propulsion engines, and gas turbines. Intelligent thermal spray processing is vital in many of these areas for efficient manufacturing. Advanced thermal spray coating applications include thermal management, wear, oxidation, corrosion resistance, sealing systems, vibration and sound absorbance, and component repair. This paper reviews the current status of materials, equipment, processing, and properties' aspects for key coatings in the energy industry, especially the developments in large-scale gas turbines. In addition to the most recent industrial advances in thermal spray technologies, future technical needs are also highlighted.

Optimal generation of spatially coherent soft X-ray isolated attosecond pulses in a gas-filled waveguide using two-color synthesized laser pulses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin, Cheng; Hong, Kyung -Han; Lin, C. D.

2016-12-08

Here, we numerically demonstrate the generation of intense, low-divergence soft X-ray isolated attosecond pulses in a gas-filled hollow waveguide using synthesized few-cycle two-color laser waveforms. The waveform is a superposition of a fundamental and its second harmonic optimized such that highest harmonic yields are emitted from each atom. We then optimize the gas pressure and the length and radius of the waveguide such that bright coherent high-order harmonics with angular divergence smaller than 1 mrad are generated, for photon energy from the extreme ultraviolet to soft X-rays. By selecting a proper spectral range enhanced isolated attosecond pulses are generated. Wemore » study how dynamic phase matching caused by the interplay among waveguide mode, neutral atomic dispersion, and plasma effect is achieved at the optimal macroscopic conditions, by performing time-frequency analysis and by analyzing the evolution of the driving laser’s electric field during the propagation. Our results, when combined with the on-going push of high-repetition-rate lasers (sub- to few MHz’s) may eventually lead to the generation of high-flux, low-divergence soft X-ray tabletop isolated attosecond pulses for applications.« less

Analyses of Injection-Coupled Combustion Instability from J-2X Gas Generator Development

NASA Technical Reports Server (NTRS)

Hulka, James R.; Kenny, R. Jeremy; Protz, Chris; Casiano, Matthew

2011-01-01

During development of the gas generator for the liquid oxygen/liquid hydrogen propellant J-2X rocket engine, combustion instabilities were observed near the frequency of the first longitudinal acoustic mode of the hot gas combustion chamber duct. These instabilities were similar to intermediate-frequency or buzz-type instabilities as described in historical programs, except for several aspects: 1) the frequencies were low, in the realm of chug; 2) at times the instability oscillation amplitudes were quite large, with peak-to-peak amplitudes exceeding 50% of the mean chamber pressure along with the appearance of harmonics; 3) the chamber excitation was related to but not exactly at the first longitudinal combustion chamber acoustic mode; and 4) the injector provided mass flow rate oscillations induced by capacitance and inertance effects in the injector rather than by organ pipe resonances of the coaxial oxidizer posts. This type of combustion instability is referred to as "injection coupling" because one critical driving source of the instability is mass flow rate oscillations from the injector. However, the type of injection coupling observed here is different than observed in previous instances of buzz instability with coaxial injectors, because of the lower frequencies and lack of influence from the oxidizer post organ pipe resonances. Test data and preliminary analyses of the initial combustion instabilities were presented in several papers at the 5th Liquid Propulsion Subcommittee meeting. Since that time, additional hot-fire tests with several new hardware configurations have been conducted, and additional analyses have been completed. The analytical models described in previous papers have been updated to include the influences of new geometrical configurations, including a different oxidizer injector manifold configuration and a branch pipe in the hot gas duct that supplies gaseous helium during the start transient to pre-spin the turbine. In addition, the

Fission-gas release from uranium nitride at high fission rate density

NASA Technical Reports Server (NTRS)

Weinstein, M. B.; Kirchgessner, T. A.; Tambling, T. N.

1973-01-01

A sweep gas facility has been used to measure the release rates of radioactive fission gases from small UN specimens irradiated to 8-percent burnup at high fission-rate densities. The measured release rates have been correlated with an equation whose terms correspond to direct recoil release, fission-enhanced diffusion, and atomic diffusion (a function of temperature). Release rates were found to increase linearly with burnups between 1.5 and 8 percent. Pore migration was observed after operation at 1550 K to over 6 percent burnup.

Angle-resolved photoemission spectroscopy with 9-eV photon-energy pulses generated in a gas-filled hollow-core photonic crystal fiber

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bromberger, H., E-mail: Hubertus.Bromberger@mpsd.mpg.de; Liu, H.; Chávez-Cervantes, M.

2015-08-31

A recently developed source of ultraviolet radiation, based on optical soliton propagation in a gas-filled hollow-core photonic crystal fiber, is applied here to angle-resolved photoemission spectroscopy (ARPES). Near-infrared femtosecond pulses of only few μJ energy generate vacuum ultraviolet radiation between 5.5 and 9 eV inside the gas-filled fiber. These pulses are used to measure the band structure of the topological insulator Bi{sub 2}Se{sub 3} with a signal to noise ratio comparable to that obtained with high order harmonics from a gas jet. The two-order-of-magnitude gain in efficiency promises time-resolved ARPES measurements at repetition rates of hundreds of kHz or even MHz,more » with photon energies that cover the first Brillouin zone of most materials.« less

In Situ Analysis of Gas Generation in Lithium-Ion Batteries with Different Carbonate-Based Electrolytes.

PubMed

Teng, Xin; Zhan, Chun; Bai, Ying; Ma, Lu; Liu, Qi; Wu, Chuan; Wu, Feng; Yang, Yusheng; Lu, Jun; Amine, Khalil

2015-10-21

Gas generation in lithium-ion batteries is one of the critical issues limiting their safety performance and lifetime. In this work, a set of 900 mAh pouch cells were applied to systematically compare the composition of gases generated from a serial of carbonate-based composite electrolytes, using a self-designed gas analyzing system. Among electrolytes used in this work, the composite γ-butyrolactone/ethyl methyl carbonate (GBL/EMC) exhibited remarkably less gassing because of the electrochemical stability of the GBL, which makes it a promising electrolyte for battery with advanced safety and lifetime.

Gas Accretion and Star Formation Rates

NASA Astrophysics Data System (ADS)

Sánchez Almeida, Jorge

Cosmological numerical simulations of galaxy evolution show that accretion of metal-poor gas from the cosmic web drives the star formation in galaxy disks. Unfortunately, the observational support for this theoretical prediction is still indirect, and modeling and analysis are required to identify hints as actual signs of star formation feeding from metal-poor gas accretion. Thus, a meticulous interpretation of the observations is crucial, and this observational review begins with a simple theoretical description of the physical process and the key ingredients it involves, including the properties of the accreted gas and of the star formation that it induces. A number of observations pointing out the connection between metal-poor gas accretion and star formation are analyzed, specifically, the short gas-consumption time-scale compared to the age of the stellar populations, the fundamental metallicity relationship, the relationship between disk morphology and gas metallicity, the existence of metallicity drops in starbursts of star-forming galaxies, the so-called G dwarf problem, the existence of a minimum metallicity for the star-forming gas in the local universe, the origin of the α-enhanced gas forming stars in the local universe, the metallicity of the quiescent BCDs, and the direct measurements of gas accretion onto galaxies. A final section discusses intrinsic difficulties to obtain direct observational evidence, and points out alternative observational pathways to further consolidate the current ideas.

Experiments to Evaluate and Implement Passive Tracer Gas Methods to Measure Ventilation Rates in Homes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lunden, Melissa; Faulkner, David; Heredia, Elizabeth

2012-10-01

This report documents experiments performed in three homes to assess the methodology used to determine air exchange rates using passive tracer techniques. The experiments used four different tracer gases emitted simultaneously but implemented with different spatial coverage in the home. Two different tracer gas sampling methods were used. The results characterize the factors of the execution and analysis of the passive tracer technique that affect the uncertainty in the calculated air exchange rates. These factors include uncertainties in tracer gas emission rates, differences in measured concentrations for different tracer gases, temporal and spatial variability of the concentrations, the comparison betweenmore » different gas sampling methods, and the effect of different ventilation conditions.« less

Room temperature micro-hydrogen-generator

NASA Astrophysics Data System (ADS)

Gervasio, Don; Tasic, Sonja; Zenhausern, Frederic

A new compact and cost-effective hydrogen-gas generator has been made that is well suited for supplying hydrogen to a fuel-cell for providing base electrical power to hand-carried appliances. This hydrogen-generator operates at room temperature, ambient pressure and is orientation-independent. The hydrogen-gas is generated by the heterogeneous catalytic hydrolysis of aqueous alkaline borohydride solution as it flows into a micro-reactor. This reactor has a membrane as one wall. Using the membrane keeps the liquid in the reactor, but allows the hydrogen-gas to pass out of the reactor to a fuel-cell anode. Aqueous alkaline 30 wt% borohydride solution is safe and promotes long application life, because this solution is non-toxic, non-flammable, and is a high energy-density (≥2200 W-h per liter or per kilogram) hydrogen-storage solution. The hydrogen is released from this storage-solution only when it passes over the solid catalyst surface in the reactor, so controlling the flow of the solution over the catalyst controls the rate of hydrogen-gas generation. This allows hydrogen generation to be matched to hydrogen consumption in the fuel-cell, so there is virtually no free hydrogen-gas during power generation. A hydrogen-generator scaled for a system to provide about 10 W electrical power is described here. However, the technology is expected to be scalable for systems providing power spanning from 1 W to kW levels.

Natural gas in the energy industry of the 21st century

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cuttica, J.

1995-12-31

This paper provides a gas industry perspective on the impacts of restructuring the natural gas and electric industries. The four main implications discussed are: (1) market trends, (2) strategic positioning, (3) significant market implications, and (4) issues for the future. Market trends discussed include transitioning rate of return to market competition and regulatory impacts. Significant market implications for gas-fired generation identified include limited new generation investment, extension of existing plants, and an opportunity for distributed power generation. 12 tabs.

The impact of feedback and the hot halo on the rates of gas accretion onto galaxies

NASA Astrophysics Data System (ADS)

Correa, Camila A.; Schaye, Joop; van de Voort, Freeke; Duffy, Alan R.; Wyithe, J. Stuart B.

2018-04-01

We investigate the physics that drives the gas accretion rates onto galaxies at the centers of dark matter haloes using the EAGLE suite of hydrodynamical cosmological simulations. We find that at redshifts z ≤ 2 the accretion rate onto the galaxy increases with halo mass in the halo mass range 1010 - 1011.7 M⊙, flattens between the halo masses 1011.7 - 1012.7 M⊙, and increases again for higher-mass haloes. However, the galaxy gas accretion does not flatten at intermediate halo masses when AGN feedback is switched off. To better understand these trends, we develop a physically motivated semi-analytic model of galaxy gas accretion. We show that the flattening is produced by the rate of gas cooling from the hot halo. The ratio of the cooling radius and the virial radius does not decrease continuously with increasing halo mass as generally thought. While it decreases up to ˜1013 M⊙ haloes, it increases for higher halo masses, causing an upturn in the galaxy gas accretion rate. This may indicate that in high-mass haloes AGN feedback is not sufficiently efficient. When there is no AGN feedback, the density of the hot halo is higher, the ratio of the cooling and virial radii does not decrease as much and the cooling rate is higher. Changes in the efficiency of stellar feedback can also increase or decrease the accretion rates onto galaxies. The trends can plausibly be explained by the re-accretion of gas ejected by progenitor galaxies and by the suppression of black hole growth, and hence AGN feedback, by stellar feedback.

The effect of working gas pressure on the switching rate of a kivotron

NASA Astrophysics Data System (ADS)

Bokhan, P. A.; Gugin, P. P.; Zakrevsky, D. E.; Lavrukhin, M. A.

2016-05-01

The switching rate in gas-discharge devices (kivotrons) based on an "open" discharge with counterpropagating electron beams is studied experimentally. Structures with a total cathode area of 2 cm2 were used. A monotonic reduction in the switching time with an increase in the working gas pressure and in the voltage amplitude at the time of breakdown is demonstrated. The minimum switching time is ~240 ps at a voltage of 17 kV. The maximum current rise rate, which is limited by the discharge circuit inductance, is 3 × 1012 A/s.

Radionuclide Gas Transport through Nuclear Explosion-Generated Fracture Networks

PubMed Central

Jordan, Amy B.; Stauffer, Philip H.; Knight, Earl E.; Rougier, Esteban; Anderson, Dale N.

2015-01-01

Underground nuclear weapon testing produces radionuclide gases which may seep to the surface. Barometric pumping of gas through explosion-fractured rock is investigated using a new sequentially-coupled hydrodynamic rock damage/gas transport model. Fracture networks are produced for two rock types (granite and tuff) and three depths of burial. The fracture networks are integrated into a flow and transport numerical model driven by surface pressure signals of differing amplitude and variability. There are major differences between predictions using a realistic fracture network and prior results that used a simplified geometry. Matrix porosity and maximum fracture aperture have the greatest impact on gas breakthrough time and window of opportunity for detection, with different effects between granite and tuff simulations highlighting the importance of accurately simulating the fracture network. In particular, maximum fracture aperture has an opposite effect on tuff and granite, due to different damage patterns and their effect on the barometric pumping process. From stochastic simulations using randomly generated hydrogeologic parameters, normalized detection curves are presented to show differences in optimal sampling time for granite and tuff simulations. Seasonal and location-based effects on breakthrough, which occur due to differences in barometric forcing, are stronger where the barometric signal is highly variable. PMID:26676058

Radionuclide Gas Transport through Nuclear Explosion-Generated Fracture Networks.

PubMed

Jordan, Amy B; Stauffer, Philip H; Knight, Earl E; Rougier, Esteban; Anderson, Dale N

2015-12-17

Underground nuclear weapon testing produces radionuclide gases which may seep to the surface. Barometric pumping of gas through explosion-fractured rock is investigated using a new sequentially-coupled hydrodynamic rock damage/gas transport model. Fracture networks are produced for two rock types (granite and tuff) and three depths of burial. The fracture networks are integrated into a flow and transport numerical model driven by surface pressure signals of differing amplitude and variability. There are major differences between predictions using a realistic fracture network and prior results that used a simplified geometry. Matrix porosity and maximum fracture aperture have the greatest impact on gas breakthrough time and window of opportunity for detection, with different effects between granite and tuff simulations highlighting the importance of accurately simulating the fracture network. In particular, maximum fracture aperture has an opposite effect on tuff and granite, due to different damage patterns and their effect on the barometric pumping process. From stochastic simulations using randomly generated hydrogeologic parameters, normalized detection curves are presented to show differences in optimal sampling time for granite and tuff simulations. Seasonal and location-based effects on breakthrough, which occur due to differences in barometric forcing, are stronger where the barometric signal is highly variable.

Evaluation of an Integrated Gas-Cooled Reactor Simulator and Brayton Turbine-Generator

NASA Technical Reports Server (NTRS)

Hissam, David Andy; Stewart, Eric T.

2006-01-01

A closed-loop brayton cycle, powered by a fission reactor, offers an attractive option for generating both planetary and in-space electric power. Non-nuclear testing of this type of system provides the opportunity to safely work out integration and system control challenges for a modest investment. Recognizing this potential, a team at Marshall Space Flight Center has evaluated the viability of integrating and testing an existing gas-cooled reactor simulator and a modified commercially available, off-the-shelf, brayton turbine-generator. Since these two systems were developed independently of one another, this evaluation had to determine if they could operate together at acceptable power levels, temperatures, and pressures. Thermal, fluid, and structural analyses show that this combined system can operate at acceptable power levels and temperatures. In addition, pressure drops across the reactor simulator, although higher than desired, are also viewed as acceptable. Three potential working fluids for the system were evaluated: N2, He/Ar, and He/Xe. Other potential issues, such as electrical breakdown in the generator and the operation of the brayton foil bearings using various gas mixtures, were also investigated.

Low NO{sub x} turbine power generation utilizing low Btu GOB gas. Final report, June--August 1995

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ortiz, I.; Anthony, R.V.; Gabrielson, J.

1995-08-01

Methane, a potent greenhouse gas, is second only to carbon dioxide as a contributor to potential global warming. Methane liberated by coal mines represents one of the most promising under exploited areas for profitably reducing these methane emissions. Furthermore, there is a need for apparatus and processes that reduce the nitrogen oxide (NO{sub x}) emissions from gas turbines in power generation. Consequently, this project aims to demonstrate a technology which utilizes low grade fuel (CMM) in a combustion air stream to reduce NO{sub x} emissions in the operation of a gas turbine. This technology is superior to other existing technologiesmore » because it can directly use the varying methane content gases from various streams of the mining operation. The simplicity of the process makes it useful for both new gas turbines and retrofitting existing gas turbines. This report evaluates the feasibility of using gob gas from the 11,000 acre abandoned Gateway Mine near Waynesburg, Pennsylvania as a fuel source for power generation applying low NO{sub x} gas turbine technology at a site which is currently capable of producing low grade GOB gas ({approx_equal} 600 BTU) from abandoned GOB areas.« less

Analysis of municipal waste generation rate in Poland compared to selected European countries

NASA Astrophysics Data System (ADS)

Klojzy-Karczmarczyk, Beata; Makoudi, Said

2017-10-01

The generated municipal waste rates provided in the planning documents are a tool for forecasting the mass of waste generated in individual waste management regions. An important issue is the decisive separation of two concepts: waste generated and waste collected. The study includes analysis of the generation rate for Poland with division into urban and rural areas. The estimated and projected rate of municipal waste generation for Poland provided in subsequent editions of National Waste Management Plans (KPGO) changed since 2000 within wide range from about 300 to more than 500 kg per capita in an individual year (kg/pc/year). Currently, the National Waste Management Plan for the years 2017-2022 estimates municipal waste generation rate at approx. 270 kg/per capita/year with a projected increase to 330 kg/per capita/year in 2030. Most European countries adopt higher municipal waste generation rate, often exceeding 600 kg/per capita/year. The objective of the paper is therefore to analyze the causes of this difference in the declared values. The morphological composition of municipal waste stream in Poland and in selected European countries (e.g. France, Belgium, Switzerland) was analyzed. At present it is not possible to balance the value of the generation rate with the rate of waste collection in Poland. The conducted analyzes allow for determining a number of reasons for variation of the rate value in particular countries, mostly morphological composition of municipal waste, inclusion of household-like waste from infrastructure facilities or not and amount of waste collected in rural areas. The differences in the generation rates and provided possible reasons indicate the need to harmonize the methodology for estimating rates of municipal waste generation in various countries, including Poland.

The Relationship Between Temperature and Gas Concentration Fluctuation Rates at an Air-Water Interface

NASA Astrophysics Data System (ADS)

Asher, W. E.; Jessup, A. T.; Liang, H.; Zappa, C. J.

2008-12-01

The air-sea flux, F, of a sparingly soluble nonreactive gas can be expressed as F = kG(CS-CW), where kG is the gas transfer velocity, CS is the concentration of gas that would be expected in the water if the system were in Henry's Gas Law equilibrium, and CW is the gas concentration in the bulk water. An analogous relationship for the net heat flux can also be written using the heat transfer velocity, kH, and the bulk-skin temperature difference in the aqueous phase. Surface divergence theory for the air-water transfer of gas and heat predicts that kG and kH will scale as the square root of the surface divergence rate, r. However, because of the interaction between diffusivity and the scale depth of the surface divergences, the scale factor for heat is likely to be different from the scale factor for gases. Infrared imagery was used to measure the timescales of variations in temperature at a water surface and laser-induced fluorescence (LIF) was used to measure temporal fluctuations in aqueous-phase concentrations of carbon dioxide (CO2) at a water surface. The rate at which these temperature and concentration fluctuations occur is then assumed to be related to r. The divergence rates derived for temperature from the IR images can be compared to the rates for gas derived from the LIF measurements to understand how r estimated from the two measurements differ. The square root of r is compared to concurrently measured kG for helium and sulfur hexafluoride to test the assumption that r1/2 scales with kG. Additionally, we measured kH using the active controlled flux technique, and those heat transfer velocities can also be used to test for a r1/2 dependence. All measurements reported here were made in the APL-UW synthetic jet array facility.

NASA Fastrac Engine Gas Generator Component Test Program and Results

NASA Technical Reports Server (NTRS)

Dennis, Henry J., Jr.; Sanders, T.

2000-01-01

Low cost access to space has been a long-time goal of the National Aeronautics and Space Administration (NASA). The Fastrac engine program was begun at NASA's Marshall Space Flight Center to develop a 60,000-pound (60K) thrust, liquid oxygen/hydrocarbon (LOX/RP), gas generator-cycle booster engine for a fraction of the cost of similar engines in existence. To achieve this goal, off-the-shelf components and readily available materials and processes would have to be used. This paper will present the Fastrac gas generator (GG) design and the component level hot-fire test program and results. The Fastrac GG is a simple, 4-piece design that uses well-defined materials and processes for fabrication. Thirty-seven component level hot-fire tests were conducted at MSFC's component test stand #116 (TS116) during 1997 and 1998. The GG was operated at all expected operating ranges of the Fastrac engine. Some minor design changes were required to successfully complete the test program as development issues arose during the testing. The test program data results and conclusions determined that the Fastrac GG design was well on the way to meeting the requirements of NASA's X-34 Pathfinder Program that chose the Fastrac engine as its main propulsion system.

Transition metal catalysis in the generation of petroleum and natural gas. Progress report, [1992--1993

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mango, F.

1993-08-01

A new hypothesis is introduced for the generation of petroleum and natural gas. The transition metals, activated under the reducing conditions of diagenesis, are proposed as catalysts in the generation of light hydrocarbons. The objective of this proposal is to test that hypothesis. Transition metals (Ni, V, Ti, Co, Fe), in kerogen, porphyrins, and as pure compounds, will be tested under catagenic conditions for catalytic activity in the conversion of normal paraffins and hydrogen into light hydrocarbons. If the hypothesis is correct, kerogenous transition metals should become catalytically active under the reducing conditions of diagenesis and catalyze the conversion ofmore » paraffins into the light hydrocarbons seen in petroleum. Moreover, the C{sub 1}-C{sub 4} hydrocarbons generated catalytically should be similar in molecular and isotopic compositions to natural gas.« less

Gas Generators and Their Potential to Support Human-Scale HIADS (Hypersonic Inflatable Aerodynamic Decelerators)

NASA Technical Reports Server (NTRS)

Bodkin, Richard J.; Cheatwood, F. M.; Dillman, Robert A; Dinonno, John M.; Hughes, Stephen J.; Lucy, Melvin H.

2016-01-01

As HIAD technology progresses from 3-m diameter experimental scale to as large as 20-m diameter for human Mars entry, the mass penalties of carrying compressed gas has led the HIAD team to research current state-of-the-art gas generator approaches. Summarized below are several technologies identified in this survey, along with some of the pros and cons with respect to supporting large-scale HIAD applications.

Construction and demolition waste generation rates for high-rise buildings in Malaysia.

PubMed

Mah, Chooi Mei; Fujiwara, Takeshi; Ho, Chin Siong

2016-12-01

Construction and demolition waste continues to sharply increase in step with the economic growth of less developed countries. Though the construction industry is large, it is composed of small firms with individual waste management practices, often leading to the deleterious environmental outcomes. Quantifying construction and demolition waste generation allows policy makers and stakeholders to understand the true internal and external costs of construction, providing a necessary foundation for waste management planning that may overcome deleterious environmental outcomes and may be both economically and environmentally optimal. This study offers a theoretical method for estimating the construction and demolition project waste generation rate by utilising available data, including waste disposal truck size and number, and waste volume and composition. This method is proposed as a less burdensome and more broadly applicable alternative, in contrast to waste estimation by on-site hand sorting and weighing. The developed method is applied to 11 projects across Malaysia as the case study. This study quantifies waste generation rate and illustrates the construction method in influencing the waste generation rate, estimating that the conventional construction method has a waste generation rate of 9.88 t 100 m -2 , the mixed-construction method has a waste generation rate of 3.29 t 100 m -2 , and demolition projects have a waste generation rate of 104.28 t 100 m -2 . © The Author(s) 2016.

Low-temperature gas from marine shales: wet gas to dry gas over experimental time.

PubMed

Mango, Frank D; Jarvie, Daniel M

2009-11-09

Marine shales exhibit unusual behavior at low temperatures under anoxic gas flow. They generate catalytic gas 300 degrees below thermal cracking temperatures, discontinuously in aperiodic episodes, and lose these properties on exposure to trace amounts of oxygen. Here we report a surprising reversal in hydrocarbon generation. Heavy hydrocarbons are formed before light hydrocarbons resulting in wet gas at the onset of generation grading to dryer gas over time. The effect is moderate under gas flow and substantial in closed reactions. In sequential closed reactions at 100 degrees C, gas from a Cretaceous Mowry shale progresses from predominately heavy hydrocarbons (66% C5, 2% C1) to predominantly light hydrocarbons (56% C1, 8% C5), the opposite of that expected from desorption of preexisting hydrocarbons. Differences in catalyst substrate composition explain these dynamics. Gas flow should carry heavier hydrocarbons to catalytic sites, in contrast to static conditions where catalytic sites are limited to in-place hydrocarbons. In-place hydrocarbons and their products should become lighter with conversion thus generating lighter hydrocarbon over time, consistent with our experimental results. We recognize the similarities between low-temperature gas generation reported here and the natural progression of wet gas to dry gas over geologic time. There is now substantial evidence for natural catalytic activity in source rocks. Natural gas at thermodynamic equilibrium and the results reported here add to that evidence. Natural catalysis provides a plausible and unique explanation for the origin and evolution of gas in sedimentary basins.

Safe Management of Waste Generated during Shale Gas Operations

NASA Astrophysics Data System (ADS)

Kukulska-Zając, Ewa; Król, Anna; Holewa-Rataj, Jadwiga

2017-04-01

Exploration and exploitation of hydrocarbon deposits, regardless of their type, are connected with the generation of waste, which may have various environmental effects. Such wastes may pose a serious risk to the surrounding environment and public health because they usually contain numerous potentially toxic chemicals. Waste associated with exploration and exploitation of unconventional hydrocarbon deposits is composed of a mixture of organic and inorganic materials, the qualitative and quantitative composition of which changes widely over time, depending on numerous factors. As a result the proper characteristic of this type of waste is very important. Information gained from detailed chemical analyses of drilling chemicals, drilling wastes, and flowback water can be used to manage shale gas-related wastes more appropriately, to develop treatment methods, to store the waste, and assess the potential environmental and health risk. The following paper will focus mainly on the results of research carried out on waste samples coming from the unconventional hydrogen exploration sites. Additionally, regulatory frameworks applicable to the management of wastes produced during this type of works will be discussed. The scope of research concerning physicochemical parameters for this type of wastes will also be presented. The presented results were obtained during M4ShaleGas project realization. The M4ShaleGas project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement no. 640715.

Contribution to irradiation creep arising from gas-driven bubbles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woo, C.H.; Garner, F.A.

1998-03-01

In a previous paper the relationship was defined between void swelling and irradiation creep arising from the interaction of the SIPA and SIG creep-driven deformation and swelling-driven deformation was highly interactive in nature, and that the two contributions could not be independently calculated and then considered as directly additive. This model could be used to explain the recent experimental observation that the creep-swelling coupling coefficient was not a constant as previously assumed, but declined continuously as the swelling rate increased. Such a model thereby explained the creep-disappearance and creep-damping anomalies observed in conditions where significant void swelling occurred before substantialmore » creep deformation developed. At lower irradiation temperatures and high helium/hydrogen generation rates, such as found in light water cooled reactors and some fusion concepts, gas-filled cavities that have not yet exceeded the critical radius for bubble-void conversion should also exert an influence on irradiation creep. In this paper the original concept is adapted to include such conditions, and its predictions then compared with available data. It is shown that a measurable increase in the creep rate is expected compared to the rate found in low gas-generating environments. The creep rate is directly related to the gas generation rate and thereby to the neutron flux and spectrum.« less

Sequential Gaussian co-simulation of rate decline parameters of longwall gob gas ventholes.

PubMed

Karacan, C Özgen; Olea, Ricardo A

2013-04-01

Gob gas ventholes (GGVs) are used to control methane inflows into a longwall mining operation by capturing the gas within the overlying fractured strata before it enters the work environment. Using geostatistical co-simulation techniques, this paper maps the parameters of their rate decline behaviors across the study area, a longwall mine in the Northern Appalachian basin. Geostatistical gas-in-place (GIP) simulations were performed, using data from 64 exploration boreholes, and GIP data were mapped within the fractured zone of the study area. In addition, methane flowrates monitored from 10 GGVs were analyzed using decline curve analyses (DCA) techniques to determine parameters of decline rates. Surface elevation showed the most influence on methane production from GGVs and thus was used to investigate its relation with DCA parameters using correlation techniques on normal-scored data. Geostatistical analysis was pursued using sequential Gaussian co-simulation with surface elevation as the secondary variable and with DCA parameters as the primary variables. The primary DCA variables were effective percentage decline rate, rate at production start, rate at the beginning of forecast period, and production end duration. Co-simulation results were presented to visualize decline parameters at an area-wide scale. Wells located at lower elevations, i.e., at the bottom of valleys, tend to perform better in terms of their rate declines compared to those at higher elevations. These results were used to calculate drainage radii of GGVs using GIP realizations. The calculated drainage radii are close to ones predicted by pressure transient tests.

Sequential Gaussian co-simulation of rate decline parameters of longwall gob gas ventholes

USGS Publications Warehouse

Karacan, C. Özgen; Olea, Ricardo A.

2013-01-01

Gob gas ventholes (GGVs) are used to control methane inflows into a longwall mining operation by capturing the gas within the overlying fractured strata before it enters the work environment. Using geostatistical co-simulation techniques, this paper maps the parameters of their rate decline behaviors across the study area, a longwall mine in the Northern Appalachian basin. Geostatistical gas-in-place (GIP) simulations were performed, using data from 64 exploration boreholes, and GIP data were mapped within the fractured zone of the study area. In addition, methane flowrates monitored from 10 GGVs were analyzed using decline curve analyses (DCA) techniques to determine parameters of decline rates. Surface elevation showed the most influence on methane production from GGVs and thus was used to investigate its relation with DCA parameters using correlation techniques on normal-scored data. Geostatistical analysis was pursued using sequential Gaussian co-simulation with surface elevation as the secondary variable and with DCA parameters as the primary variables. The primary DCA variables were effective percentage decline rate, rate at production start, rate at the beginning of forecast period, and production end duration. Co-simulation results were presented to visualize decline parameters at an area-wide scale. Wells located at lower elevations, i.e., at the bottom of valleys, tend to perform better in terms of their rate declines compared to those at higher elevations. These results were used to calculate drainage radii of GGVs using GIP realizations. The calculated drainage radii are close to ones predicted by pressure transient tests.

Sequential Gaussian co-simulation of rate decline parameters of longwall gob gas ventholes

PubMed Central

Karacan, C.Özgen; Olea, Ricardo A.

2015-01-01

Gob gas ventholes (GGVs) are used to control methane inflows into a longwall mining operation by capturing the gas within the overlying fractured strata before it enters the work environment. Using geostatistical co-simulation techniques, this paper maps the parameters of their rate decline behaviors across the study area, a longwall mine in the Northern Appalachian basin. Geostatistical gas-in-place (GIP) simulations were performed, using data from 64 exploration boreholes, and GIP data were mapped within the fractured zone of the study area. In addition, methane flowrates monitored from 10 GGVs were analyzed using decline curve analyses (DCA) techniques to determine parameters of decline rates. Surface elevation showed the most influence on methane production from GGVs and thus was used to investigate its relation with DCA parameters using correlation techniques on normal-scored data. Geostatistical analysis was pursued using sequential Gaussian co-simulation with surface elevation as the secondary variable and with DCA parameters as the primary variables. The primary DCA variables were effective percentage decline rate, rate at production start, rate at the beginning of forecast period, and production end duration. Co-simulation results were presented to visualize decline parameters at an area-wide scale. Wells located at lower elevations, i.e., at the bottom of valleys, tend to perform better in terms of their rate declines compared to those at higher elevations. These results were used to calculate drainage radii of GGVs using GIP realizations. The calculated drainage radii are close to ones predicted by pressure transient tests. PMID:26190930

Effect of biogas generation on radon emissions from landfills receiving radium-bearing waste from shale gas development.

PubMed

Walter, Gary R; Benke, Roland R; Pickett, David A

2012-09-01

Dramatic increases in the development of oil and natural gas from shale formations will result in large quantities of drill cuttings, flowback water, and produced water. These organic-rich shale gas formations often contain elevated concentrations of naturally occurring radioactive materials (NORM), such as uranium, thorium, and radium. Production of oil and gas from these formations will also lead to the development of technologically enhanced NORM (TENORM) in production equipment. Disposal of these potentially radium-bearing materials in municipal solid waste (MSW) landfills could release radon to the atmosphere. Risk analyses of disposal of radium-bearing TENORM in MSW landfills sponsored by the Department of Energy did not consider the effect of landfill gas (LFG) generation or LFG control systems on radon emissions. Simulation of radon emissions from landfills with LFG generation indicates that LFG generation can significantly increase radon emissions relative to emissions without LFG generation, where the radon emissions are largely controlled by vapor-phase diffusion. Although the operation of LFG control systems at landfills with radon source materials can result in point-source atmospheric radon plumes, the LFG control systems tend to reduce overall radon emissions by reducing advective gas flow through the landfill surface, and increasing the radon residence time in the subsurface, thus allowing more time for radon to decay. In some of the disposal scenarios considered, the radon flux from the landfill and off-site atmospheric activities exceed levels that would be allowed for radon emissions from uranium mill tailings. Increased development of hydrocarbons from organic-rich shale formations has raised public concern that wastes from these activities containing naturally occurring radioactive materials, particularly radium, may be disposed in municipal solid waste landfills and endanger public health by releasing radon to the atmosphere. This paper

Comparative life-cycle air emissions of coal, domestic natural gas, LNG, and SNG for electricity generation.

PubMed

Jaramillo, Paulina; Griffin, W Michael; Matthews, H Scott

2007-09-01

The U.S. Department of Energy (DOE) estimates that in the coming decades the United States' natural gas (NG) demand for electricity generation will increase. Estimates also suggest that NG supply will increasingly come from imported liquefied natural gas (LNG). Additional supplies of NG could come domestically from the production of synthetic natural gas (SNG) via coal gasification-methanation. The objective of this study is to compare greenhouse gas (GHG), SOx, and NOx life-cycle emissions of electricity generated with NG/LNG/SNG and coal. This life-cycle comparison of air emissions from different fuels can help us better understand the advantages and disadvantages of using coal versus globally sourced NG for electricity generation. Our estimates suggest that with the current fleet of power plants, a mix of domestic NG, LNG, and SNG would have lower GHG emissions than coal. If advanced technologies with carbon capture and sequestration (CCS) are used, however, coal and a mix of domestic NG, LNG, and SNG would have very similar life-cycle GHG emissions. For SOx and NOx we find there are significant emissions in the upstream stages of the NG/ LNG life-cycles, which contribute to a larger range in SOx and NOx emissions for NG/LNG than for coal and SNG.

Optimizing gas transfer to improve growth rate of Haematococcus pluvialis in a raceway pond with chute and oscillating baffles.

PubMed

Yang, Zongbo; Cheng, Jun; Li, Ke; Zhou, Junhu; Cen, Kefa

2016-08-01

Up-down chute and oscillating (UCO) baffles were used to generate vortex and oscillating flow field to improve growth rate of Haematococcus pluvialis in a raceway pond. Effects of gas flow rate, solution velocity, and solution depth on solution mass transfer coefficient and mixing time were evaluated using online pH and dissolved oxygen probes. Mass transfer coefficient increased by 1.3 times and mixing time decreased by 33% when UCO baffles were used in the H. pluvialis solution, resulting in an 18% increase in biomass yield with 2% CO2. The H. pluvialis biomass yield further increased to 1.5g/L, and astaxanthin composition accumulated to 29.7mg/L under relatively higher light intensity and salinity. Copyright © 2016 Elsevier Ltd. All rights reserved.

Burial History, Thermal Maturity, and Oil and Gas Generation History of Source Rocks in the Bighorn Basin, Wyoming and Montana

USGS Publications Warehouse

Roberts, Laura N.R.; Finn, Thomas M.; Lewan, Michael D.; Kirschbaum, Mark A.

2008-01-01

Burial history, thermal maturity, and timing of oil and gas generation were modeled for seven key source-rock units at eight well locations throughout the Bighorn Basin in Wyoming and Montana. Also modeled was the timing of cracking to gas of Phosphoria Formation-sourced oil in the Permian Park City Formation reservoirs at two well locations. Within the basin boundary, the Phosphoria is thin and only locally rich in organic carbon; it is thought that the Phosphoria oil produced from Park City and other reservoirs migrated from the Idaho-Wyoming thrust belt. Other petroleum source rocks include the Cretaceous Thermopolis Shale, Mowry Shale, Frontier Formation, Cody Shale, Mesaverde and Meeteetse Formations, and the Tertiary (Paleocene) Fort Union Formation. Locations (wells) selected for burial history reconstructions include three in the deepest parts of the Bighorn Basin (Emblem Bench, Red Point/Husky, and Sellers Draw), three at intermediate depths (Amoco BN 1, Santa Fe Tatman, and McCulloch Peak), and two at relatively shallow locations (Dobie Creek and Doctor Ditch). The thermal maturity of source rocks is greatest in the deep central part of the basin and decreases to the south, east, and north toward the basin margins. The Thermopolis and Mowry Shales are predominantly gas-prone source rocks, containing a mix of Type-III and Type-II kerogens. The Frontier, Cody, Mesaverde, Meeteetse, and Fort Union Formations are gas-prone source rocks containing Type-III kerogen. Modeling results indicate that in the deepest areas, (1) the onset of petroleum generation from Cretaceous rocks occurred from early Paleocene through early Eocene time, (2) peak petroleum generation from Cretaceous rocks occurred during Eocene time, and (3) onset of gas generation from the Fort Union Formation occurred during early Eocene time and peak generation occurred from late Eocene to early Miocene time. Only in the deepest part of the basin did the oil generated from the Thermopolis and

77 FR 35669 - AltaGas Renewable Energy Colorado LLC; Supplemental Notice That Initial Market-Based Rate Filing...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-14

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. ER12-1875-000] AltaGas Renewable Energy Colorado LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request... of AltaGas Renewable Energy Colorado LLC application for market-based rate authority, with an...

A Gas Chromatographic System for the Detection of Ethylene Gas Using Ambient Air as a Carrier Gas

PubMed Central

Zaidi, Nayyer Abbas; Tahir, Muhammad Waseem; Vellekoop, Michael J.; Lang, Walter

2017-01-01

Ethylene gas is a naturally occurring gas that has an influence on the shelf life of fruit during their transportation in cargo ships. An unintentional exposure of ethylene gas during transportation results in a loss of fruit. A gas chromatographic system is presented here for the detection of ethylene gas. The gas chromatographic system was assembled using a preconcentrator, a printed 3D printed gas chromatographic column, a humidity sensor, solenoid valves, and an electrochemical ethylene gas sensor. Ambient air was used as a carrier gas in the gas chromatographic system. The flow rate was fixed to 10 sccm. It was generated through a mini-pump connected in series with a mass flow controller. The metal oxide gas sensor is discussed with its limitation in ambient air. The results show the chromatogram obtained from metal oxide gas sensor has low stability, drifts, and has uncertain peaks, while the chromatogram from the electrochemical sensor is stable and precise. Furthermore, ethylene gas measurements at higher ppb concentration and at lower ppb concentration were demonstrated with the electrochemical ethylene gas sensor. The system separates ethylene gas and humidity. The chromatograms obtained from the system are stable, and the results are 1.2% repeatable in five similar measurements. The statistical calculation of the gas chromatographic system shows that a concentration of 2.3 ppb of ethylene gas can be detected through this system. PMID:28991173

A Gas Chromatographic System for the Detection of Ethylene Gas Using Ambient Air as a Carrier Gas.

PubMed

Zaidi, Nayyer Abbas; Tahir, Muhammad Waseem; Vellekoop, Michael J; Lang, Walter

2017-10-07

Ethylene gas is a naturally occurring gas that has an influence on the shelf life of fruit during their transportation in cargo ships. An unintentional exposure of ethylene gas during transportation results in a loss of fruit. A gas chromatographic system is presented here for the detection of ethylene gas. The gas chromatographic system was assembled using a preconcentrator, a printed 3D printed gas chromatographic column, a humidity sensor, solenoid valves, and an electrochemical ethylene gas sensor. Ambient air was used as a carrier gas in the gas chromatographic system. The flow rate was fixed to 10 sccm. It was generated through a mini-pump connected in series with a mass flow controller. The metal oxide gas sensor is discussed with its limitation in ambient air. The results show the chromatogram obtained from metal oxide gas sensor has low stability, drifts, and has uncertain peaks, while the chromatogram from the electrochemical sensor is stable and precise. Furthermore, ethylene gas measurements at higher ppb concentration and at lower ppb concentration were demonstrated with the electrochemical ethylene gas sensor. The system separates ethylene gas and humidity. The chromatograms obtained from the system are stable, and the results are 1.2% repeatable in five similar measurements. The statistical calculation of the gas chromatographic system shows that a concentration of 2.3 ppb of ethylene gas can be detected through this system.

INNOVATIVE HYBRID GAS/ELECTRIC CHILLER COGENERATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Todd Kollross; Mike Connolly

2004-06-30

Engine-driven chillers are quickly gaining popularity in the market place (increased from 7,000 tons in 1994 to greater than 50,000 tons in 1998) due to their high efficiency, electric peak shaving capability, and overall low operating cost. The product offers attractive economics (5 year pay back or less) in many applications, based on areas cooling requirements and electric pricing structure. When heat is recovered and utilized from the engine, the energy resource efficiency of a natural gas engine-driven chiller is higher than all competing products. As deregulation proceeds, real time pricing rate structures promise high peak demand electric rates, butmore » low off-peak electric rates. An emerging trend with commercial building owners and managers who require air conditioning today is to reduce their operating costs by installing hybrid chiller systems that combine gas and electric units. Hybrid systems not only reduce peak electric demand charges, but also allow customers to level their energy load profiles and select the most economical energy source, gas or electricity, from hour to hour. Until recently, however, all hybrid systems incorporated one or more gas-powered chillers (engine driven and/or absorption) and one or more conventional electric units. Typically, the cooling capacity of hybrid chiller plants ranges from the hundreds to thousands of refrigeration tons, with multiple chillers affording the user a choice of cooling systems. But this flexibility is less of an option for building operators who have limited room for equipment. To address this technology gap, a hybrid chiller was developed by Alturdyne that combines a gas engine, an electric motor and a refrigeration compressor within a single package. However, this product had not been designed to realize the full features and benefits possible by combining an engine, motor/generator and compressor. The purpose of this project is to develop a new hybrid chiller that can (1) reduce end

Study of Plasma Flows Generated in Plasma Focus Discharge in Different Regimes of Working Gas Filling

NASA Astrophysics Data System (ADS)

Voitenko, D. A.; Ananyev, S. S.; Astapenko, G. I.; Basilaia, A. D.; Markolia, A. I.; Mitrofanov, K. N.; Myalton, V. V.; Timoshenko, A. P.; Kharrasov, A. M.; Krauz, V. I.

2017-12-01

Results are presented from experimental studies of the plasma flows generated in the KPF-4 Phoenix Mather-type plasma focus device (Sukhum Physical Technical Institute). In order to study how the formation and dynamics of the plasma flow depend on the initial distribution of the working gas, a system of pulsed gas puffing into the discharge volume was developed. The system allows one to create profiled gas distributions, including those with a reduced gas density in the region of plasma flow propagation. Results of measurements of the magnetic field, flow profile, and flow deceleration dynamics at different initial distributions of the gas pressure are presented.

Implications of Lower Natural Gas Prices for Electric Generators in the Southeast, The

EIA Publications

2009-01-01

This supplement to the Energy Information Administration's (EIA) May 2009 Short-Term Energy Outlook (STEO) focuses on changes in the utilization of coal- and natural-gas-fired generation capacity in the electric utility sector as the differential between delivered fuel prices narrows.

Determination of LEDs degradation with entropy generation rate

NASA Astrophysics Data System (ADS)

Cuadras, Angel; Yao, Jiaqiang; Quilez, Marcos

2017-10-01

We propose a method to assess the degradation and aging of light emitting diodes (LEDs) based on irreversible entropy generation rate. We degraded several LEDs and monitored their entropy generation rate ( S ˙ ) in accelerated tests. We compared the thermoelectrical results with the optical light emission evolution during degradation. We find a good relationship between aging and S ˙ (t), because S ˙ is both related to device parameters and optical performance. We propose a threshold of S ˙ (t) as a reliable damage indicator of LED end-of-life that can avoid the need to perform optical measurements to assess optical aging. The method lays beyond the typical statistical laws for lifetime prediction provided by manufacturers. We tested different LED colors and electrical stresses to validate the electrical LED model and we analyzed the degradation mechanisms of the devices.

Ammonia biofiltration and nitrous oxide generation during the start-up of gas-phase compost biofilters

NASA Astrophysics Data System (ADS)

Maia, Guilherme D. N.; Day V, George B.; Gates, Richard S.; Taraba, Joseph L.

2012-01-01

Gas-Phase Biofiltration technology is widely utilized for treating ammonia gas (NH 3) with one of its potential detrimental by-products being nitrous oxide (N 2O), a potent greenhouse gas (100-y radiative forcing 298 times greater than carbon dioxide). The present work was conducted to investigate the relation between NH 3 removal during biofiltration and N 2O generation as a product of incomplete denitrification during the start-up of gas-phase compost biofilters. Four laboratory scale tubular biofilters in up flow mode (20 s residence-time) were studied for 21 days: 3 replicates were subjected to 16 ppm v (0.78 g m -2 h -1) of NH 3 and a statistical control not subjected to NH 3. Ammonia concentration differences between biofilter inlet (Bottom = 16 ppm v) and outlet (Top) and N 2O concentration differences between biofilter outlet (Top) and biofilter inlet (background concentrations at the bottom) were used to determine the extent of the correlation between NH 3 removal and N 2O generation. Correlations with CH 4 and CO 2 were also reported. The high Spearman correlation coefficients for the three replicates ( ρ = -0.845, -0.820, and -0.841, with P ≤ 0.0001 for replications A, B and C, respectively) suggested that availability of nitrate/nitrite owing to NH 3 nitrification favored conditions for N 2O generation as a sub-product of denitrification. The statistical control received no NH 3 inputs and did not generate N 2O. Therefore, the results indicated that the process of NH 3 removal was a trigger for N 2O production. Carbon dioxide and N 2O were moderately correlated. Methane and N 2O were weakly correlated and only for replicate C. No significant correlation was found for the Statistical Control between N 2O and CH 4.

Thermoelectric Power Generation System for Future Hybrid Vehicles Using Hot Exhaust Gas

NASA Astrophysics Data System (ADS)

Kim, Sun-Kook; Won, Byeong-Cheol; Rhi, Seok-Ho; Kim, Shi-Ho; Yoo, Jeong-Ho; Jang, Ju-Chan

2011-05-01

The present experimental and computational study investigates a new exhaust gas waste heat recovery system for hybrid vehicles, using a thermoelectric module (TEM) and heat pipes to produce electric power. It proposes a new thermoelectric generation (TEG) system, working with heat pipes to produce electricity from a limited hot surface area. The current TEG system is directly connected to the exhaust pipe, and the amount of electricity generated by the TEMs is directly proportional to their heated area. Current exhaust pipes fail to offer a sufficiently large hot surface area for the high-efficiency waste heat recovery required. To overcome this, a new TEG system has been designed to have an enlarged hot surface area by the addition of ten heat pipes, which act as highly efficient heat transfer devices and can transmit the heat to many TEMs. As designed, this new waste heat recovery system produces a maximum 350 W when the hot exhaust gas heats the evaporator surface of the heat pipe to 170°C; this promises great possibilities for application of this technology in future energy-efficient hybrid vehicles.

Gas exchange patterns and water loss rates in the Table Mountain cockroach, Aptera fusca (Blattodea: Blaberidae).

PubMed

Groenewald, Berlizé; Bazelet, Corinna S; Potter, C Paige; Terblanche, John S

2013-10-15

The importance of metabolic rate and/or spiracle modulation for saving respiratory water is contentious. One major explanation for gas exchange pattern variation in terrestrial insects is to effect a respiratory water loss (RWL) saving. To test this, we measured the rates of CO2 and H2O release ( and , respectively) in a previously unstudied, mesic cockroach, Aptera fusca, and compared gas exchange and water loss parameters among the major gas exchange patterns (continuous, cyclic, discontinuous gas exchange) at a range of temperatures. Mean , and per unit did not differ among the gas exchange patterns at all temperatures (P>0.09). There was no significant association between temperature and gas exchange pattern type (P=0.63). Percentage of RWL (relative to total water loss) was typically low (9.79±1.84%) and did not differ significantly among gas exchange patterns at 15°C (P=0.26). The method of estimation had a large impact on the percentage of RWL, and of the three techniques investigated (traditional, regression and hyperoxic switch), the traditional method generally performed best. In many respects, A. fusca has typical gas exchange for what might be expected from other insects studied to date (e.g. , , RWL and cuticular water loss). However, we found for A. fusca that expressed as a function of metabolic rate was significantly higher than the expected consensus relationship for insects, suggesting it is under considerable pressure to save water. Despite this, we found no consistent evidence supporting the conclusion that transitions in pattern type yield reductions in RWL in this mesic cockroach.

The impact of feedback and the hot halo on the rates of gas accretion on to galaxies

NASA Astrophysics Data System (ADS)

Correa, Camila A.; Schaye, Joop; van de Voort, Freeke; Duffy, Alan R.; Wyithe, J. Stuart B.

2018-07-01

We investigate the physics that drives the gas accretion rates on to galaxies at the centres of dark matter haloes using the EAGLE suite of hydrodynamical cosmological simulations. We find that at redshifts z ≤ 2, the accretion rate on to the galaxy increases with halo mass in the halo mass range 1010-1011.7 M⊙, flattens between the halo masses 1011.7 and 1012.7 M⊙, and increases again for higher mass haloes. However, the galaxy gas accretion does not flatten at intermediate halo masses when active galactic nucleus (AGN) feedback is switched off. To better understand these trends, we develop a physically motivated semi-analytic model of galaxy gas accretion. We show that the flattening is produced by the rate of gas cooling from the hot halo. The ratio of the cooling radius and the virial radius does not decrease continuously with increasing halo mass as generally thought. While it decreases up to ˜1013 M⊙ haloes, it increases for higher halo masses, causing an upturn in the galaxy gas accretion rate. This may indicate that in high-mass haloes, AGN feedback is not sufficiently efficient. When there is no AGN feedback, the density of the hot halo is higher, the ratio of the cooling and virial radii does not decrease as much, and the cooling rate is higher. Changes in the efficiency of stellar feedback can also increase or decrease the accretion rates on to galaxies. The trends can plausibly be explained by the re-accretion of gas ejected by progenitor galaxies and by the suppression of black hole growth, and hence AGN feedback, by stellar feedback.

Transition regime analytical solution to gas mass flow rate in a rectangular micro channel

NASA Astrophysics Data System (ADS)

Dadzie, S. Kokou; Dongari, Nishanth

2012-11-01

We present an analytical model predicting the experimentally observed gas mass flow rate in rectangular micro channels over slip and transition regimes without the use of any fitting parameter. Previously, Sone reported a class of pure continuum regime flows that requires terms of Burnett order in constitutive equations of shear stress to be predicted appropriately. The corrective terms to the conventional Navier-Stokes equation were named the ghost effect. We demonstrate in this paper similarity between Sone ghost effect model and newly so-called 'volume diffusion hydrodynamic model'. A generic analytical solution to gas mass flow rate in a rectangular micro channel is then obtained. It is shown that the volume diffusion hydrodynamics allows to accurately predict the gas mass flow rate up to Knudsen number of 5. This can be achieved without necessitating the use of adjustable parameters in boundary conditions or parametric scaling laws for constitutive relations. The present model predicts the non-linear variation of pressure profile along the axial direction and also captures the change in curvature with increase in rarefaction.

Physical properties and surface/interface analysis of nanocrystalline WO3 films grown under variable oxygen gas flow rates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vemuri, R. S.; Carbjal-Franco, G.; Ferrer, D. A.

2012-10-15

Nanocrystalline WO3 films were grown by reactive magnetron sputter-deposition in a wide range of oxygen gas flow rates while keeping the deposition temperature fixed at 400 oC. The physical characteristics of WO3 films were evaluated using grazing incidence X-ray diffraction (GIXRD), X-ray reflectivity (XRR) and transmission electron microscopy (TEM) measurements. Physical characterization indicates that the thickness, grain size, and density of WO3 films are sensitive to the oxygen gas flow rate during deposition. XRD data indicates the formation of tetragonal WO3 films. The grain size increases from 21 to 25 nm with increasing oxygen gas flow rate to 65%, atmore » which point the grain size exhibits a decreasing trend to attain the lowest value of 15 nm at 100% oxygen. TEM analysis provides a model consisting of isotropic WO3 film (nanocrystalline)-SiO2 interface (amorphous)-Si(100) substrate. XRR simulations, which are based on this model, provide excellent agreement to the experimental data indicating that the normalized thickness of WO3 films decreases with the increasing oxygen gas flow rate. The density of WO3 films increases with increasing oxygen gas flow rate.« less

Effect of pulsed corona discharge voltage and feed gas flow rate on dissolved ozone concentration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prasetyaningrum, A., E-mail: ajiprasetyaningrum@gmail.com; Ratnawati,; Jos, B.

Ozonization is one of the methods extensively used for water purification and degradation of organic materials. Ozone (O{sub 3}) is recognized as a powerful oxidizing agent. Due to its strong oxidability and better environmental friendless, ozone increasing being used in domestic and industrial applications. Current technology in ozone production utilizes several techniques (corona discharge, ultra violet radiation and electrolysis). This experiment aimed to evaluating effect of voltage and gas flow rate on ozone production with corona discharge. The system consists of two net-type stainless steel electrode placed in a dielectric barrier. Three pulsed voltage (20, 30, 40 KV) and flowmore » rate (5, 10, 15 L/min) were prepare for operation variable at high frequency (3.7 kHz) with AC pulsed power supply. The dissolved ozone concentration depends on the applied high-voltage level, gas flow rate and the discharge exposure duration. The ozone concentration increases with decreasing gas flow rate. Dissolved ozone concentrations greater than 200 ppm can be obtained with a minimum voltage 40 kV.« less

Effect of pulsed corona discharge voltage and feed gas flow rate on dissolved ozone concentration

NASA Astrophysics Data System (ADS)

Prasetyaningrum, A.; Ratnawati, Jos, B.

2015-12-01

Ozonization is one of the methods extensively used for water purification and degradation of organic materials. Ozone (O3) is recognized as a powerful oxidizing agent. Due to its strong oxidability and better environmental friendless, ozone increasing being used in domestic and industrial applications. Current technology in ozone production utilizes several techniques (corona discharge, ultra violet radiation and electrolysis). This experiment aimed to evaluating effect of voltage and gas flow rate on ozone production with corona discharge. The system consists of two net-type stainless steel electrode placed in a dielectric barrier. Three pulsed voltage (20, 30, 40 KV) and flow rate (5, 10, 15 L/min) were prepare for operation variable at high frequency (3.7 kHz) with AC pulsed power supply. The dissolved ozone concentration depends on the applied high-voltage level, gas flow rate and the discharge exposure duration. The ozone concentration increases with decreasing gas flow rate. Dissolved ozone concentrations greater than 200 ppm can be obtained with a minimum voltage 40 kV.

Condensation and dissociation rates for gas phase metal clusters from molecular dynamics trajectory calculations

DOE PAGES

Yang, Huan; Goudeli, Eirini; Hogan, Christopher J.

2018-04-24

In gas phase synthesis systems, clusters form and grow via condensation, in which a monomer binds to an existing cluster. While a hard sphere equation is frequently used to predict the condensation rate coefficient, this equation neglects the influences of potential interactions and cluster internal energy on the condensation process. Here, we present a collision rate theory-Molecular Dynamics simulation approach to calculate condensation probabilities and condensation rate coefficients; we use this approach to examine atomic condensation onto 6-56 atom Au and Mg clusters. The probability of condensation depends upon the initial relative velocity ( v) between atom and cluster andmore » the initial impact parameter ( b). In all cases there is a well-defined region of b-v space where condensation is highly probable, and outside of which the condensation probability drops to zero. For Au clusters with more than 10 atoms, we find that at gas temperatures in the 300-1200 K range, the condensation rate coefficient exceeds the hard sphere rate coefficient by a factor of 1.5-2.0. Conversely, for Au clusters with 10 or fewer atoms, and for 14 atom and 28 atom Mg clusters, as cluster equilibration temperature increases the condensation rate coefficient drops to values below the hard sphere rate coefficient. Calculations also yield the self-dissociation rate coefficient, which is found to vary considerably with gas temperature. Finally, calculations results reveal that grazing (high b) atom-cluster collisions at elevated velocity (> 1000 m s -1) can result in the colliding atom rebounding (bounce) from the cluster surface or binding while another atom dissociates (replacement). In conclusion, the presented method can be applied in developing rate equations to predict material formation and growth rates in vapor phase systems.« less

Condensation and dissociation rates for gas phase metal clusters from molecular dynamics trajectory calculations.

PubMed

Yang, Huan; Goudeli, Eirini; Hogan, Christopher J

2018-04-28

In gas phase synthesis systems, clusters form and grow via condensation, in which a monomer binds to an existing cluster. While a hard-sphere equation is frequently used to predict the condensation rate coefficient, this equation neglects the influences of potential interactions and cluster internal energy on the condensation process. Here, we present a collision rate theory-molecular dynamics simulation approach to calculate condensation probabilities and condensation rate coefficients. We use this approach to examine atomic condensation onto 6-56-atom Au and Mg clusters. The probability of condensation depends upon the initial relative velocity (v) between atom and cluster and the initial impact parameter (b). In all cases, there is a well-defined region of b-v space where condensation is highly probable, and outside of which the condensation probability drops to zero. For Au clusters with more than 10 atoms, we find that at gas temperatures in the 300-1200 K range, the condensation rate coefficient exceeds the hard-sphere rate coefficient by a factor of 1.5-2.0. Conversely, for Au clusters with 10 or fewer atoms and for 14- and 28-atom Mg clusters, as cluster equilibration temperature increases, the condensation rate coefficient drops to values below the hard-sphere rate coefficient. Calculations also yield the self-dissociation rate coefficient, which is found to vary considerably with gas temperature. Finally, calculations results reveal that grazing (high b) atom-cluster collisions at elevated velocity (>1000 m s -1 ) can result in the colliding atom rebounding (bounce) from the cluster surface or binding while another atom dissociates (replacement). The presented method can be applied in developing rate equations to predict material formation and growth rates in vapor phase systems.

Condensation and dissociation rates for gas phase metal clusters from molecular dynamics trajectory calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Huan; Goudeli, Eirini; Hogan, Christopher J.

In gas phase synthesis systems, clusters form and grow via condensation, in which a monomer binds to an existing cluster. While a hard sphere equation is frequently used to predict the condensation rate coefficient, this equation neglects the influences of potential interactions and cluster internal energy on the condensation process. Here, we present a collision rate theory-Molecular Dynamics simulation approach to calculate condensation probabilities and condensation rate coefficients; we use this approach to examine atomic condensation onto 6-56 atom Au and Mg clusters. The probability of condensation depends upon the initial relative velocity ( v) between atom and cluster andmore » the initial impact parameter ( b). In all cases there is a well-defined region of b-v space where condensation is highly probable, and outside of which the condensation probability drops to zero. For Au clusters with more than 10 atoms, we find that at gas temperatures in the 300-1200 K range, the condensation rate coefficient exceeds the hard sphere rate coefficient by a factor of 1.5-2.0. Conversely, for Au clusters with 10 or fewer atoms, and for 14 atom and 28 atom Mg clusters, as cluster equilibration temperature increases the condensation rate coefficient drops to values below the hard sphere rate coefficient. Calculations also yield the self-dissociation rate coefficient, which is found to vary considerably with gas temperature. Finally, calculations results reveal that grazing (high b) atom-cluster collisions at elevated velocity (> 1000 m s -1) can result in the colliding atom rebounding (bounce) from the cluster surface or binding while another atom dissociates (replacement). In conclusion, the presented method can be applied in developing rate equations to predict material formation and growth rates in vapor phase systems.« less

Condensation and dissociation rates for gas phase metal clusters from molecular dynamics trajectory calculations

NASA Astrophysics Data System (ADS)

Yang, Huan; Goudeli, Eirini; Hogan, Christopher J.

2018-04-01

In gas phase synthesis systems, clusters form and grow via condensation, in which a monomer binds to an existing cluster. While a hard-sphere equation is frequently used to predict the condensation rate coefficient, this equation neglects the influences of potential interactions and cluster internal energy on the condensation process. Here, we present a collision rate theory-molecular dynamics simulation approach to calculate condensation probabilities and condensation rate coefficients. We use this approach to examine atomic condensation onto 6-56-atom Au and Mg clusters. The probability of condensation depends upon the initial relative velocity (v) between atom and cluster and the initial impact parameter (b). In all cases, there is a well-defined region of b-v space where condensation is highly probable, and outside of which the condensation probability drops to zero. For Au clusters with more than 10 atoms, we find that at gas temperatures in the 300-1200 K range, the condensation rate coefficient exceeds the hard-sphere rate coefficient by a factor of 1.5-2.0. Conversely, for Au clusters with 10 or fewer atoms and for 14- and 28-atom Mg clusters, as cluster equilibration temperature increases, the condensation rate coefficient drops to values below the hard-sphere rate coefficient. Calculations also yield the self-dissociation rate coefficient, which is found to vary considerably with gas temperature. Finally, calculations results reveal that grazing (high b) atom-cluster collisions at elevated velocity (>1000 m s-1) can result in the colliding atom rebounding (bounce) from the cluster surface or binding while another atom dissociates (replacement). The presented method can be applied in developing rate equations to predict material formation and growth rates in vapor phase systems.

Generator configuration for solid oxide fuel cells

DOEpatents

Reichner, Philip

1989-01-01

Disclosed are improvements in a solid oxide fuel cell generator 1 having a multiplicity of electrically connected solid oxide fuel cells 2, where a fuel gas is passed over one side of said cells and an oxygen-containing gas is passed over the other side of said cells resulting in the generation of heat and electricity. The improvements comprise arranging the cells in the configuration of a circle, a spiral, or folded rows within a cylindrical generator, and modifying the flow rate, oxygen concentration, and/or temperature of the oxygen-containing gases that flow to those cells that are at the periphery of the generator relative to those cells that are at the center of the generator. In these ways, a more uniform temperature is obtained throughout the generator.

Improving microalgal growth with small bubbles in a raceway pond with swing gas aerators.

PubMed

Yang, Zongbo; Cheng, Jun; Liu, Jianzhong; Zhou, Junhu; Cen, Kefa

2016-09-01

A novel swing gas aerator was developed to generate small bubbles for improving the mass transfer coefficient and microalgal growth rate in a raceway pond. A high-speed photography system (HSP) was used to measure the bubble diameter and generation time, and online precise dissolved oxygen probes and pH probes were used to measure the mass transfer coefficient and mixing time. Bubble generation time and diameter decreased by 21% and 9%, respectively, when rubber gas aerators were swung in the microalgae solution. When water pump power and gas aeration rate increased in a raceway pond with swing gas aerators and oscillating baffles (SGAOB), bubble generation time and diameter decreased but solution velocity and mass transfer coefficient increased. The mass transfer coefficient increased by 25% and the solution velocity increased by 11% when SGAOB was used, and the microalgal biomass yield increased by 18%. Copyright © 2016 Elsevier Ltd. All rights reserved.

Externally pressurized porous cylinder for multiple surface aerosol generation and method of generation

DOEpatents

Apel, Charles T.; Layman, Lawrence R.; Gallimore, David L.

1988-01-01

A nebulizer for generating aerosol having small droplet sizes and high efficiency at low sample introduction rates. The nebulizer has a cylindrical gas permeable active surface. A sleeve is disposed around the cylinder and gas is provided from the sleeve to the interior of the cylinder formed by the active surface. In operation, a liquid is provided to the inside of the gas permeable surface. The gas contacts the wetted surface and forms small bubbles which burst to form an aerosol. Those bubbles which are large are carried by momentum to another part of the cylinder where they are renebulized. This process continues until the entire sample is nebulized into aerosol sized droplets.

Externally pressurized porous cylinder for multiple surface aerosol generation and method of generation

DOEpatents

Apel, C.T.; Layman, L.R.; Gallimore, D.L.

1988-05-10

A nebulizer is described for generating aerosol having small droplet sizes and high efficiency at low sample introduction rates. The nebulizer has a cylindrical gas permeable active surface. A sleeve is disposed around the cylinder and gas is provided from the sleeve to the interior of the cylinder formed by the active surface. In operation, a liquid is provided to the inside of the gas permeable surface. The gas contacts the wetted surface and forms small bubbles which burst to form an aerosol. Those bubbles which are large are carried by momentum to another part of the cylinder where they are renebulized. This process continues until the entire sample is nebulized into aerosol sized droplets. 2 figs.

Comparison of electrical and optical characteristics in gas-phase and gas-liquid phase discharges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qazi, H. I. A.; Li, He-Ping, E-mail: liheping@tsinghua.edu.cn; Zhang, Xiao-Fei

This paper presents an AC-excited argon discharge generated using a gas-liquid (two-phase) hybrid plasma reactor, which mainly consists of a powered needle electrode enclosed in a conical quartz tube and grounded deionized water electrode. The discharges in the gas-phase, as well as in the two-phase, exhibit two discharge modes, i.e., the low current glow-like diffuse mode and the high current streamer-like constrict mode, with a mode transition, which exhibits a negative resistance of the discharges. The optical emission spectral analysis shows that the stronger diffusion of the water vapor into the discharge region in the two-phase discharges boosts up themore » generation of OH (A–X) radicals, and consequently, leads to a higher rotational temperature in the water-phase plasma plume than that of the gas-phase discharges. Both the increase of the power input and the decrease of the argon flow rate result in the increase of the rotational temperature in the plasma plume of the water-phase discharge. The stable two-phase discharges with a long plasma plume in the water-phase under a low power input and gas flow rate may show a promising prospect for the degradation of organic pollutants, e.g., printing and dyeing wastewater, in the field of environmental protection.« less

Compound-specific carbon isotope analysis of instantaneous gas generated from shaly coal during hydrous pyrolysis

NASA Astrophysics Data System (ADS)

Tsai, Wen-Yu; Sun, Chih-Hsien; Huang, Wuu-Liang

2010-05-01

Isotopes of natural gases have provided important information for indicating their maturation, origins and influencing factors during the generation processes. In order to distinguish compositions of gas generated at different intervals of maturities, the present study investigates the variation of compound-specific carbon isotope (CSI) ratios of hydrocarbon gases from a shaly coal by instantaneous hydrous pyrolysis, during which the earlier generated gas was evacuated before the start of next maturation stage. The experiments were conducted at ten different maturity stages (0.65 to 2.02 % Ro) from a terrestrial shaly coal with 0.48 % Ro. The gas products were analyzed by GC-IR-MS. The results show that, in general, the δ13C values of methane (C1), ethane (C2), propane (C3) slightly increase, then decrease and finally increase with increasing maturities. This reverse phenomenon indicates the heterogeneous and complex compositions of the kerogen. The isotope compositions of gases exhibit three distinct clusters in natural gas plot of δ13C values versus 1/n (where n is carbon number of the gaseous molecule), corresponding to three different groups of maturity stages. By linking the same maturity stage of δ13C values, all lines show nearly parallel in each group with consistently reverse trend of δ13C3 < δ13C2 > δ13C1. These three distinct clusters were also observed in the cross plotting of iC4/nC4 versus iC5/nC5 isomer ratios. This may imply that the kerogen is composed of three discrete structural domains which were progressively cracked at three major groups of maturity stages. The reverse trend was inconsistent with data for gas collected cumulatively in most prior pyrolysis experiments and the linear relationship predicted from kinetic isotope effect (KIE) model. Although the non-linear relationship or reverse trend, δ13C3 < δ13C2, was also reported for some natural gases, it was interpreted as a result of mixing from different source rocks or other

Fission gas release during power bumping at high burnup

NASA Astrophysics Data System (ADS)

Cunningham, M. E.; Freshley, M. D.; Lanning, D. D.

1993-03-01

Research to define the behavior of Zircaloy-clad light-water reactor fuel irradiated to high burnup levels was conducted by the High Burnup Effects Program (HBEP). One activity conducted by the HBEP was to "bump" the power level of irradiated, commercial light-water reactor fuel rods to design limit linear heat generation rates at end-of-life. These bumping irradiations simulated end-of-life design limit linear heat generation rates and provided data on the effects of short-term, high power irradiations at high burnup applicable to the design and operating constraints imposed by maximum allowable fuel rod internal gas pressure limits. Based on net fission gas release during the bumping irradiations, it was observed that higher burnup rods had greater rod-average fractional fission gas release than lower burnup rods at equal bumping powers. It was also observed that a hold period of 48 hours at the peak power was insufficient to achieve equilibrium fission gas release. Finally, differences in the prebump location of fission gas, i.e., within the UO 2 matrix or at grain boundaries, affected the fission gas release during the bumping irradiations.

25 CFR 211.43 - Royalty rates for minerals other than oil and gas.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 25 Indians 1 2012-04-01 2011-04-01 true Royalty rates for minerals other than oil and gas. 211.43 Section 211.43 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR ENERGY AND MINERALS LEASING OF TRIBAL LANDS FOR MINERAL DEVELOPMENT Rents, Royalties, Cancellations and Appeals § 211.43 Royalty rates...

25 CFR 212.43 - Royalty rates for minerals other than oil and gas.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 25 Indians 1 2012-04-01 2011-04-01 true Royalty rates for minerals other than oil and gas. 212.43 Section 212.43 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR ENERGY AND MINERALS LEASING OF ALLOTTED LANDS FOR MINERAL DEVELOPMENT Rents, Royalties, Cancellations, and Appeals § 212.43 Royalty rates...

25 CFR 212.43 - Royalty rates for minerals other than oil and gas.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 25 Indians 1 2010-04-01 2010-04-01 false Royalty rates for minerals other than oil and gas. 212.43 Section 212.43 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR ENERGY AND MINERALS LEASING OF ALLOTTED LANDS FOR MINERAL DEVELOPMENT Rents, Royalties, Cancellations, and Appeals § 212.43 Royalty rates...

Evaluation of Start Transient Oscillations with the J-2X Engine Gas Generator Assembly

NASA Technical Reports Server (NTRS)

Hulka, J. R.; Morgan, C. J.; Casiano, M. J.

2015-01-01

During development of the gas generator for the liquid oxygen/liquid hydrogen propellant J-2X rocket engine, distinctive and oftentimes high-amplitude pressure oscillations and hardware vibrations occurred during the start transient of nearly every workhorse gas generator assembly test, as well as during many tests of engine system hardware. These oscillations appeared whether the steady-state conditions exhibited stable behavior or not. They occurred similarly with three different injector types, and with every combustion chamber configuration tested, including chamber lengths ranging over a 5:1 range, several different nozzle types, and with or without a side branch line simulating a turbine spin start gas supply line. Generally, two sets of oscillations occurred, one earlier in the start transient and at higher frequencies, and the other almost immediately following and at lower frequencies. Multiple dynamic pressure measurements in the workhorse combustion chambers indicated that the oscillations were associated with longitudinal acoustic modes of the combustion chambers, with the earlier and higher frequency oscillation usually related to the second longitudinal acoustic mode and the later and lower frequency oscillation usually related to the first longitudinal acoustic mode. Given that several early development gas generator assemblies exhibited unstable behavior at frequencies near the first longitudinal acoustic modes of longer combustion chambers, the start transient oscillations are presumed to provide additional insight into the nature of the combustion instability mechanisms. Aspects of the steadystate oscillations and combustion instabilities from development and engine system test programs have been reported extensively in the three previous JANNAF Liquid Propulsion Subcommittee meetings (see references below). This paper describes the hardware configurations, start transient sequence operations, and transient and dynamic test data during the start

Mid-infrared trace gas detection using continuous-wave difference frequency generation in periodically poled RbTiOAsO4

NASA Technical Reports Server (NTRS)

Chen, W.; Mouret, G.; Boucher, D.; Tittel, F. K.

2001-01-01

A tunable mid-infrared continuous-wave (cw) spectroscopic source in the 3.4-4.5 micrometers region is reported, based on difference frequency generation (DFG) in a quasi-phase-matched periodically poled RbTiOAsO4 (PPRTA) crystal. DFG power levels of 10 microW were generated at approximately 4 micrometers in a 20-mm long PPRTA crystal by mixing two cw single-frequency Ti:Al2O3 lasers operating near 713 nm and 871 nm, respectively, using a laser pump power of 300 mW. A quasi-phase-matched infrared wavelength-tuning bandwidth (FWHM) of 12 cm-1 and a temperature tuning rate of 1.02 cm-1/degree C were achieved. Experimental details regarding the feasibility of trace gas detection based on absorption spectroscopy of CO2 in ambient air using this DFG radiation source are also described.

Respiratory rate detection using a wearable electromagnetic generator.

PubMed

Padasdao, Bryson; Boric-Lubecke, Olga

2011-01-01

Wearable health and fitness monitoring systems are a promising new way of collecting physiological data without inconveniencing patients. Human energy harvesting may be used to power wearable sensors. In this paper, we explore this zero-net energy biosensor concept through sensing and harvesting of respiratory effort. An off the shelf servo motor operation in reverse was used to successfully obtain respiratory rate, while also demonstrating significant harvested power. These are the first reported respiratory rate sensing results using electromagnetic generators.

The Spatial Footprint of Natural Gas-Fired Electricity

NASA Astrophysics Data System (ADS)

Jordaan, S. M.; Heath, G.; Macknick, J.; Mohammadi, E.; Ben-Horin, D.; Urrea, V.; Marceau, D.

2015-12-01

Consistent comparisons of the amount of land required for different electricity generation technologies are challenging because land use associated with fossil fuel acquisition and delivery has not been well characterized or empirically grounded. This research focuses on improving estimates of the life cycle land use of natural gas-fired electricity (m2/MWh generated) through the novel combination of inventories of natural gas-related infrastructure, satellite imagery analysis and gas production estimates. We focus on seven counties that represent 98% of the total gas production in the Barnett Shale (Texas), evaluating over 500 sites across five life cycle stages (gas production, gathering, processing, transmission, and power generation as well as produced water disposal). We find that a large fraction of total life cycle land use is related to gathering (midstream) infrastructure, particularly pipelines; access roads related to all stages also contribute a large life cycle share. Results were sensitive to several inputs, including well lifetime, pipeline right of way, number of wells per site, variability of heat rate for electricity generation, and facility lifetime. Through this work, we have demonstrated a novel, highly-resolved and empirical method for estimating life cycle land use from natural gas infrastructure in an important production region. When replicated for other gas production regions and other fuels, the results can enable more empirically-grounded and robust comparisons of the land footprint of alternative energy choices.

Microwave plasma assisted supersonic gas jet deposition of thin film materials

DOEpatents

Schmitt, III, Jerome J.; Halpern, Bret L.

1993-01-01

An apparatus for fabricating thin film materials utilizing high speed gas dynamics relies on supersonic free jets of carrier gas to transport depositing vapor species generated in a microwave discharge to the surface of a prepared substrate where the vapor deposits to form a thin film. The present invention generates high rates of deposition and thin films of unforeseen high quality at low temperatures.

Microwave plasma assisted supersonic gas jet deposition of thin film materials

DOEpatents

Schmitt, J.J. III; Halpern, B.L.

1993-10-26

An apparatus for fabricating thin film materials utilizing high speed gas dynamics relies on supersonic free jets of carrier gas to transport depositing vapor species generated in a microwave discharge to the surface of a prepared substrate where the vapor deposits to form a thin film. The present invention generates high rates of deposition and thin films of unforeseen high quality at low temperatures. 5 figures.

Assessing the Greenhouse Gas Emissions from Natural Gas Fired Power Plants

NASA Astrophysics Data System (ADS)

Hajny, K. D.; Shepson, P. B.; Rudek, J.; Stirm, B. H.; Kaeser, R.; Stuff, A. A.

2017-12-01

Natural gas is often discussed as a "bridge fuel" to transition to renewable energy as it only produces 51% the amount of CO2 per unit energy as coal. This, coupled with rapid increases in production fueled by technological advances, has led to a near tripling of natural gas used for electricity generation since 2005. One concern with this idea of a "bridge fuel" is that methane, the primary component of natural gas, is itself a potent greenhouse gas with 28 and 84 times the global warming potential of CO2 based on mass over a 100 and 20 year period, respectively. Studies have estimated that leaks from the point of extraction to end use of 3.2% would offset the climate benefits of natural gas. Previous work from our group saw that 3 combined cycle power plants emitted unburned CH4 from the stacks and leaked additional CH4 from equipment on site, but total loss rates were still less than 2.2%. Using Purdue's Airborne Laboratory for Atmospheric Research (ALAR) we completed additional aircraft based mass balance experiments combined with passes directly over power plant stacks to expand on the previous study. In this work, we have measured at 12 additional natural gas fired power plants including a mix of operation types (baseload, peaking, intermediate) and firing methods (combined cycle, simple thermal, combustion turbine). We have also returned to the 3 plants previously sampled to reinvestigate emissions for each of those, to assess reproducibility of the results. Here we report the comparison of reported continuous emissions monitoring systems (CEMS) data for CO2 to our emission rates calculated from mass balance experiments, as well as a comparison of calculated CH4 emission rates to estimated emission rates based on the EPA emission factor of 1 g CH4/mmbtu natural gas and CEMS reported heat input. We will also discuss emissions from a coal-fired plant which has been sampled by the group in the past and has since converted to natural gas. Lastly, we discuss the

Efficient generation of fast neutrons by magnetized deuterons in an optimized deuterium gas-puff z-pinch

NASA Astrophysics Data System (ADS)

Klir, D.; Shishlov, A. V.; Kokshenev, V. A.; Kubes, P.; Labetsky, A. Yu; Rezac, K.; Cherdizov, R. K.; Cikhardt, J.; Cikhardtova, B.; Dudkin, G. N.; Fursov, F. I.; Garapatsky, A. A.; Kovalchuk, B. M.; Kravarik, J.; Kurmaev, N. E.; Orcikova, H.; Padalko, V. N.; Ratakhin, N. A.; Sila, O.; Turek, K.; Varlachev, V. A.

2015-04-01

Z-pinch experiments with deuterium gas puffs have been carried out on the GIT-12 generator at 3 MA currents. Recently, a novel configuration of a deuterium gas-puff z-pinch was used to accelerate deuterons and to generate fast neutrons. In order to form a homogeneous, uniformly conducting layer at a large initial radius, an inner deuterium gas puff was surrounded by an outer hollow cylindrical plasma shell. The plasma shell consisting of hydrogen and carbon ions was formed at the diameter of 350 mm by 48 plasma guns. A linear mass of the plasma shell was about 5 µg cm-1 whereas a total linear mass of deuterium gas in single or double shell gas puffs was about 100 µg cm-1. The implosion lasted 700 ns and seemed to be stable up to a 5 mm radius. During stagnation, m = 0 instabilities became more pronounced. When a disruption of necks occurred, the plasma impedance reached 0.4 Ω and high energy (>2 MeV) bremsstrahlung radiation together with high energy deuterons were produced. Maximum neutron energies of 33 MeV were observed by axial time-of-flight detectors. The observed neutron spectra could be explained by a suprathermal distribution of deuterons with a high energy tail f≤ft({{E}\\text{d}}\\right)\\propto E\\text{d}-(1.8+/- 0.2) . Neutron yields reached 3.6 × 1012 at a 2.7 MA current. A high neutron production efficiency of 6 × 107 neutrons per one joule of plasma energy resulted from the generation of high energy deuterons and from their magnetization inside plasmas.

Landfill gas to electricity demonstration project

NASA Astrophysics Data System (ADS)

Giuliani, A. J.; Cagliostro, L. A.

1982-03-01

Medium Btu methane gas is a naturally occurring by product of anaerobic digestion of landfilled municipal solid waste. The energy potential of landfill gas in New York State is estimated to be 61 trillion Btu's per year or the equivalent of 10 percent of the natural gas used annually in the State. The 18-month Landfill Gas to Electricity Demonstration Project conducted at the Fresh Kills Landfill in Staten Island, New York conclusively demonstrated that landfill gas is an acceptable fuel for producing electricity using an internal combustion engine/generator set. Landfill gas proved to be a reliable and consistent fuel source during a six-month field test program. Engine exhaust emissions were determined to be comparable to that of natural gas and no unusually high corrosion rates on standard pipeline material were found.

Generation of µW level plateau harmonics at high repetition rate.

PubMed

Hädrich, S; Krebs, M; Rothhardt, J; Carstens, H; Demmler, S; Limpert, J; Tünnermann, A

2011-09-26

The process of high harmonic generation allows for coherent transfer of infrared laser light to the extreme ultraviolet spectral range opening a variety of applications. The low conversion efficiency of this process calls for optimization or higher repetition rate intense ultrashort pulse lasers. Here we present state-of-the-art fiber laser systems for the generation of high harmonics up to 1 MHz repetition rate. We perform measurements of the average power with a calibrated spectrometer and achieved µW harmonics between 45 nm and 61 nm (H23-H17) at a repetition rate of 50 kHz. Additionally, we show the potential for few-cycle pulses at high average power and repetition rate that may enable water-window harmonics at unprecedented repetition rate. © 2011 Optical Society of America

High-pressure LOX/hydrocarbon preburners and gas generators

NASA Technical Reports Server (NTRS)

Huebner, A. W.

1981-01-01

The objective of the program was to conduct a small scale hardware test program to establish the technology base required for LOX/hydrocarbon preburners and gas generators. The program consisted of six major tasks; Task I reviewed and assessed the performance prediction models and defined a subscale test program. Task II designed and fabricated this subscale hardware. Task III tested and analyzed the data from this hardware. Task IV analyzed the hot fire results and formulated a preliminary design for 40K preburner assemblies. Task V took the preliminary design and detailed and fabricated three 40K size preburner assemblies, one each fuel-rich LOX/CH, and LOX/RP-1 and one oxidizer rich LOX/CH4. Task VI delivered these preburner assemblies to MSFC for subsequent evaluation.

Methane gas generation from waste water extraction process of crude palm oil in experimental digesters

NASA Astrophysics Data System (ADS)

Dillon, A.; Penafiel, R.; Garzón, P. V.; Ochoa, V.

2015-12-01

Industrial processes to extract crude palm oil, generates large amounts of waste water. High concentrations of COD, ST, SV, NH4 + and low solubility of O2, make the treatment of these effluents starts with anaerobic processes. The anaerobic digestion process has several advantages over aerobic degradation: lower operating costs (not aeration), low sludge production, methane gas generation. The 4 stages of anaerobic digestion are: hydrolysis, acidogenic, acetogenesis and methanogenesis. Through the action of enzymes synthesized by microbial consortia are met. The products of each step to serve as reagents is conducted as follows. The organic load times and cell hydraulic retention, solids content, nutrient availability, pH and temperature are factors that influence directly in biodigesters. The objectives of this presentation is to; characterize the microbial inoculum and water (from palm oil wasted water) to be used in biodigestores, make specific methanogenic activity in bioassays, acclimatize the microorganisms to produce methane gas using basal mineral medium with acetate for the input power, and to determine the production of methane gas digesters high organic load.

Deformation and the timing of gas generation and migration in the eastern Brooks Range foothills, Arctic National Wildlife Refuge, Alaska

USGS Publications Warehouse

Parris, T.M.; Burruss, R.C.; O'Sullivan, P. B.

2003-01-01

Along the southeast border of the 1002 Assessment Area in the Arctic National Wildlife Refuge, Alaska, an explicit link between gas generation and deformation in the Brooks Range fold and thrust belt is provided through petrographic, fluid inclusion, and stable isotope analyses of fracture cements integrated with zircon fission-track data. Predominantly quartz-cemented fractures, collected from thrusted Triassic and Jurassic rocks, contain crack-seal textures, healed microcracks, and curved crystals and fluid inclusion populations, which suggest that cement growth occurred before, during, and after deformation. Fluid inclusion homogenization temperatures (175-250??C) and temperature trends in fracture samples suggest that cements grew at 7-10 km depth during the transition from burial to uplift and during early uplift. CH4-rich (dry gas) inclusions in the Shublik Formation and Kingak Shale are consistent with inclusion entrapment at high thermal maturity for these source rocks. Pressure modeling of these CH4-rich inclusions suggests that pore fluids were overpressured during fracture cementation. Zircon fission-track data in the area record postdeposition denudation associated with early Brooks Range deformation at 64 ?? 3 Ma. With a closure temperature of 225-240??C, the zircon fission-track data overlap homogenization temperatures of coeval aqueous inclusions and inclusions containing dry gas in Kingak and Shublik fracture cements. This critical time-temperature relationship suggests that fracture cementation occurred during early Brooks Range deformation. Dry gas inclusions suggest that Shublik and Kingak source rocks had exceeded peak oil and gas generation temperatures at the time structural traps formed during early Brooks Range deformation. The timing of hydrocarbon generation with respect to deformation therefore represents an important exploration risk for gas exploration in this part of the Brooks Range fold and thrust belt. The persistence of gas high at

76 FR 36913 - Washington Gas Light Company; Notice of Motion for Extension of Rate Case Filing Deadline

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-23

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. PR09-8-005] Washington Gas Light Company; Notice of Motion for Extension of Rate Case Filing Deadline Take notice that on June 15, 2011, Washington Gas Light Company (Washington Gas) filed a request for an extension consistent with...

A space-based combined thermophotovoltaic electric generator and gas laser solar energy conversion system

NASA Technical Reports Server (NTRS)

Yesil, Oktay

1989-01-01

This paper describes a spaceborne energy conversion system consisting of a thermophotovoltaic electric generator and a gas laser. As a power source for the converson, the system utilizes an intermediate blackbody cavity heated to a temperature of 2000-2400 K by concentrated solar radiation. A double-layer solar cell of GaAs and Si forms a cylindrical surface concentric to this blackbody cavity, receiving the blackbody radiation and converting it into electricity with cell conversion efficiency of 50 percent or more. If the blackbody cavity encloses a laser medium, the blackbody radiation can also be used to simultaneously pump a lasing gas. The feasibility of blackbody optical pumping at 4.3 microns in a CO2-He gas mixture was experimentally demonstrated.

Heat and mass transfer rates during flow of dissociated hydrogen gas over graphite surface

NASA Technical Reports Server (NTRS)

Nema, V. K.; Sharma, O. P.

1986-01-01

To improve upon the performance of chemical rockets, the nuclear reactor has been applied to a rocket propulsion system using hydrogen gas as working fluid and a graphite-composite forming a part of the structure. Under the boundary layer approximation, theoretical predictions of skin friction coefficient, surface heat transfer rate and surface regression rate have been made for laminar/turbulent dissociated hydrogen gas flowing over a flat graphite surface. The external stream is assumed to be frozen. The analysis is restricted to Mach numbers low enough to deal with the situation of only surface-reaction between hydrogen and graphite. Empirical correlations of displacement thickness, local skin friction coefficient, local Nusselt number and local non-dimensional heat transfer rate have been obtained. The magnitude of the surface regression rate is found low enough to ensure the use of graphite as a linear or a component of the system over an extended period without loss of performance.

Throat carriage rate and antimicrobial susceptibility pattern of group A Streptococci (GAS) in healthy Ethiopian school children.

PubMed

Abdissa, Alemseged; Asrat, Daniel; Kronvall, Göran; Shitu, Belay; Achiko, Dilachew; Zeidan, Mohammed; Yamuah, Lawrence K; Aseffa, Abraham

2011-04-01

Group A Streptococci (GAS) or Streptococcus pyogenes are the most frequent cause of pharyngitis and skin infection in children and lead to post infection complications including acute rheumatic fever and glomerulonephritis. Pharyngeal carriage rates of GAS among healthy school children vary with geographical location and seasons. There is not much information on the screening of children for carriage of GAS in Ethiopia. The study aimed at assessing the carriage rate of Group A Streptococci and antimicrobial susceptibility of the isolates in healthy Ethiopian school children. A total of 937 children residing in Addis Ababa (n=491), Gondar (n=265) and Dire-Dawa (n=181) were investigated during a period between November 2004 and January 2005. Throat specimens were collected and cultured using standard procedure. Beta haemolytic streptococci were serogrouped by agglutination tests using specific antisera. Antimicrobial susceptibility testing of the isolates was performed by diffusion method. The median and the mean ages of the study participants were 11 (range 6-14) years. Girls constituted 52% (486/937) of the study participants. A total of 167 (17.8%) beta haemolytic streptococci were recovered from 937 children investigated GAS accounted for 91/167 (54.5%) of beta hemolytic streptococcal isolates. The carrier rate for GAS was 9.7% (91/937) of the screened children followed by group G with 3.2% (30/937) and group C streptococci with 2.2% (21/937). All GAS isolates were sensitive to oxacillin, penicillin, erythromycin, clindamycin and trimethoprim-sulphamethoxazole. Lower frequency of resistance was observed against tetracycline and vanocmycin. The present study revealed that GAS was the most predominant beta-haemolytic streptococcus among healthy Ethiopian school children. Our results showed that pharyngeal carriage of GAS in school children should not be underestimated. Therefore it is recommended to conduct regular screening and GAS surveillance in schools, and

Design and assembly of a catalyst bed gas generator for the catalytic decomposition of high concentration hydrogen peroxide propellants and the catalytic combustion of hydrocarbon/air mixtures

NASA Technical Reports Server (NTRS)

Lohner, Kevin A. (Inventor); Mays, Jeffrey A. (Inventor); Sevener, Kathleen M. (Inventor)

2004-01-01

A method for designing and assembling a high performance catalyst bed gas generator for use in decomposing propellants, particularly hydrogen peroxide propellants, for use in target, space, and on-orbit propulsion systems and low-emission terrestrial power and gas generation. The gas generator utilizes a sectioned catalyst bed system, and incorporates a robust, high temperature mixed metal oxide catalyst. The gas generator requires no special preheat apparatus or special sequencing to meet start-up requirements, enabling a fast overall response time. The high performance catalyst bed gas generator system has consistently demonstrated high decomposition efficiency, extremely low decomposition roughness, and long operating life on multiple test articles.

Nanosecond pulsed power generator for a voltage amplitude up to 300 kV and a repetition rate up to 16 Hz for fine disintegration of quartz

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krastelev, E. G., E-mail: ekrastelev@yandex.ru; Sedin, A. A.; Tugushev, V. I.

2015-12-15

A generator of high-power high-voltage nanosecond pulses is intended for electrical discharge disintegration of mineral quartz and other nonconducting minerals. It includes a 320 kV Marx pulsed voltage generator, a high-voltage glycerin-insulated coaxial peaking capacitor, and an output gas spark switch followed by a load, an electric discharge disintegration chamber. The main parameters of the generator are as follows: a voltage pulse amplitude of up to 300 kV, an output impedance of ≈10 Ω, a discharge current amplitude of up to 25 kA for a half-period of 80–90 ns, and a pulse repetition rate of up to 16 Hz.

Estimation of rates of aerobic hydrocarbon biodegradation by simulation of gas transport in the unsaturated zone

USGS Publications Warehouse

Lahvis, Matthew A.; Baehr, Arthur L.

1996-01-01

The distribution of oxygen and carbon dioxide gases in the unsaturated zone provides a geochemical signature of aerobic hydrocarbon degradation at petroleum product spill sites. The fluxes of these gases are proportional to the rate of aerobic biodegradation and are quantified by calibrating a mathematical transport model to the oxygen and carbon dioxide gas concentration data. Reaction stoichiometry is assumed to convert the gas fluxes to a corresponding rate of hydrocarbon degradation. The method is applied at a gasoline spill site in Galloway Township, New Jersey, to determine the rate of aerobic degradation of hydrocarbons associated with passive and bioventing remediation field experiments. At the site, microbial degradation of hydrocarbons near the water table limits the migration of hydrocarbon solutes in groundwater and prevents hydrocarbon volatilization into the unsaturated zone. In the passive remediation experiment a site-wide degradation rate estimate of 34,400 g yr−1 (11.7 gal. yr−1) of hydrocarbon was obtained by model calibration to carbon dioxide gas concentration data collected in December 1989. In the bioventing experiment, degradation rate estimates of 46.0 and 47.9 g m−2 yr−1(1.45 × 10−3 and 1.51 × 10−3 gal. ft.−2yr−1) of hydrocarbon were obtained by model calibration to oxygen and carbon dioxide gas concentration data, respectively. Method application was successful in quantifying the significance of a naturally occurring process that can effectively contribute to plume stabilization.

Effect of N{sub 2} and Ar gas on DC arc plasma generation and film composition from Ti-Al compound cathodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhirkov, Igor, E-mail: igozh@ifm.liu.se; Rosen, Johanna; Oks, Efim

2015-06-07

DC arc plasma from Ti, Al, and Ti{sub 1−x}Al{sub x} (x = 0.16, 0.25, 0.50, and 0.70) compound cathodes has been characterized with respect to plasma chemistry (charged particles) and charge-state-resolved ion energy for Ar and N{sub 2} pressures in the range 10{sup −6} to 3 × 10{sup −2} Torr. Scanning electron microscopy was used for exploring the correlation between the cathode and film composition, which in turn was correlated with the plasma properties. In an Ar atmosphere, the plasma ion composition showed a reduction of Al of approximately 5 at. % compared to the cathode composition, while deposited films were in accordance with the cathodemore » stoichiometry. Introducing N{sub 2} above ∼5 × 10{sup −3} Torr, lead to a reduced Al content in the plasma as well as in the film, and hence a 1:1 correlation between the cathode and film composition cannot be expected in a reactive environment. This may be explained by an influence of the reactive gas on the arc mode and type of erosion of Ti and Al rich contaminations, as well as on the plasma transport. Throughout the investigated pressure range, a higher deposition rate was obtained from cathodes with higher Al content. The origin of generated gas ions was investigated through the velocity rule, stating that the most likely ion velocities of all cathode elements from a compound cathode are equal. The results suggest that the major part of the gas ions in Ar is generated from electron impact ionization, while gas ions in a N{sub 2} atmosphere primarily originate from a nitrogen contaminated layer on the cathode surface. The presented results provide a contribution to the understanding processes of plasma generation from compound cathodes. It also allows for a more reasonable approach to the selection of composite cathode and experimental conditions for thin film depositions.« less

Effect of Feed Gas Flow Rate on CO2 Absorption through Super Hydrophobic Hollow Fiber membrane Contactor

NASA Astrophysics Data System (ADS)

Kartohardjono, Sutrasno; Alexander, Kevin; Larasati, Annisa; Sihombing, Ivander Christian

2018-03-01

Carbon dioxide is pollutant in natural gas that could reduce the heating value of the natural gas and cause problem in transportation due to corrosive to the pipeline. This study aims to evaluate the effects of feed gas flow rate on CO2 absorption through super hydrophobic hollow fiber contactor. Polyethyleneglycol-300 (PEG-300) solution was used as absorbent in this study, whilst the feed gas used in the experiment was a mixture of 30% CO2 and 70% CH4. There are three super hydrophobic hollow fiber contactors sized 6 cm and 25 cm in diameter and length used in this study, which consists of 1000, 3000 and 5000 fibers, respectively. The super hydrophobic fiber membrane used is polypropylene-based with outer and inner diameter of about 525 and 235 μm, respectively. In the experiments, the feed gas was sent through the shell side of the membrane contactor, whilst the absorbent solution was pumped through the lumen fibers. The experimental results showed that the mass transfer coefficient, flux, absorption efficiency for CO2-N2 system and CO2 loading increased with the feed gas flow rate, but the absorption efficiency for CO2-N2 system decreased. The mass transfer coefficient and the flux, at the same feed gas flow rate, decreased with the number of fibers in the membrane contactor, but the CO2 absorption efficiency and the CO2 loading increased.

Optimization of a RF-generated CF4/O2 gas plasma sterilization process.

PubMed

Lassen, Klaus S; Nordby, Bolette; Grün, Reinar

2003-05-15

A sterilization process with the use of RF-generated (13.56 MHz) CF(4)/O(2) gas plasma was optimized in regards to power, flow rate, exposure time, and RF-system type. The dependency of the sporicidal effect on the spore inoculum positioning in the chamber of the RF systems was also investigated. Dried Bacillus stearothermophilus ATCC 7953 endospores were used as test organisms. The treatments were evaluated on the basis of survival curves and corresponding D values. The only parameter found to affect the sterilization process was the power of the RF system. Higher power resulted in higher kill. Finally, when the samples were placed more than 3-8 cm away from a centrally placed electrode in System 2, the sporicidal effect was reduced. The results are discussed and compared to results from the present literature. The RF excitation source is evaluated to be more appropriate for sterilization processes than the MW source. Copyright 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 65B: 239-244, 2003

Aluminum/ammonia heat pipe gas generation and long term system impact for the Space Telescope's Wide Field Planetary Camera

NASA Technical Reports Server (NTRS)

Jones, J. A.

1983-01-01

In the Space Telescope's Wide Field Planetary Camera (WFPC) project, eight heat pipes (HPs) are used to remove heat from the camera's inner electronic sensors to the spacecraft's outer, cold radiator surface. For proper device functioning and maximization of the signal-to-noise ratios, the Charge Coupled Devices (CCD's) must be maintained at -95 C or lower. Thermoelectric coolers (TEC's) cool the CCD's, and heat pipes deliver each TEC's nominal six to eight watts of heat to the space radiator, which reaches an equilibrium temperature between -15 C to -70 C. An initial problem was related to the difficulty to produce gas-free aluminum/ammonia heat pipes. An investigation was, therefore, conducted to determine the cause of the gas generation and the impact of this gas on CCD cooling. In order to study the effect of gas slugs in the WFPC system, a separate HP was made. Attention is given to fabrication, testing, and heat pipe gas generation chemistry studies.

High-sweeping-speed optically synchronized dual-channel terahertz-signal generator for driving a superconducting tunneling mixer and its application to active gas sensing.

PubMed

Oh, Kyoung-Hwan; Shimizu, Naofumi; Kohjiro, Satoshi; Kikuchi, Ken'ichi; Wakatsuki, Atsushi; Kukutsu, Naoya; Kado, Yuichi

2009-10-12

We propose a high-sweeping-speed optically synchronized dual-channel terahertz (THz) signal generator for an active gas-sensing system with a superconductor-insulator-superconductor (SIS) mixer. The generator can sweep a frequency range from 200 to 500 GHz at a speed of 375 GHz/s and a frequency resolution of 500 MHz. With the developed gas-sensing system, a gas-absorption-line measurement was successfully carried out with N(2)O gas in that frequency range.

Analyses of Longitudinal Mode Combustion Instability in J-2X Gas Generator Development

NASA Technical Reports Server (NTRS)

Hulka, J. R.; Protz, C. S.; Casiano, M. J.; Kenny, R. J.

2011-01-01

The National Aeronautics and Space Administration (NASA) and Pratt & Whitney Rocketdyne are developing a liquid oxygen/liquid hydrogen rocket engine for future upper stage and trans-lunar applications. This engine, designated the J-2X, is a higher pressure, higher thrust variant of the Apollo-era J-2 engine. The contract for development was let to Pratt & Whitney Rocketdyne in 2006. Over the past several years, development of the gas generator for the J-2X engine has progressed through a variety of workhorse injector, chamber, and feed system configurations on the component test stand at the NASA Marshall Space Flight Center (MSFC). Several of the initial configurations resulted in combustion instability of the workhorse gas generator assembly at a frequency near the first longitudinal mode of the combustion chamber. In this paper, several aspects of these combustion instabilities are discussed, including injector, combustion chamber, feed system, and nozzle influences. To ensure elimination of the instabilities at the engine level, and to understand the stability margin, the gas generator system has been modeled at the NASA MSFC with two techniques, the Rocket Combustor Interaction Design and Analysis (ROCCID) code and a lumped-parameter MATLAB(TradeMark) model created as an alternative calculation to the ROCCID methodology. To correctly predict the instability characteristics of all the chamber and injector geometries and test conditions as a whole, several inputs to the submodels in ROCCID and the MATLAB(TradeMark) model were modified. Extensive sensitivity calculations were conducted to determine how to model and anchor a lumped-parameter injector response, and finite-element and acoustic analyses were conducted on several complicated combustion chamber geometries to determine how to model and anchor the chamber response. These modifications and their ramification for future stability analyses of this type are discussed.

Well blowout rates in California Oil and Gas District 4--Update and Trends

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jordan, Preston D.; Benson, Sally M.

2009-10-01

Well blowouts are one type of event in hydrocarbon exploration and production that generates health, safety, environmental and financial risk. Well blowouts are variously defined as 'uncontrolled flow of well fluids and/or formation fluids from the wellbore' or 'uncontrolled flow of reservoir fluids into the wellbore'. Theoretically this is irrespective of flux rate and so would include low fluxes, often termed 'leakage'. In practice, such low-flux events are not considered well blowouts. Rather, the term well blowout applies to higher fluxes that rise to attention more acutely, typically in the order of seconds to days after the event commences. Itmore » is not unusual for insurance claims for well blowouts to exceed US$10 million. This does not imply that all blowouts are this costly, as it is likely claims are filed only for the most catastrophic events. Still, insuring against the risk of loss of well control is the costliest in the industry. The risk of well blowouts was recently quantified from an assembled database of 102 events occurring in California Oil and Gas District 4 during the period 1991 to 2005, inclusive. This article reviews those findings, updates them to a certain extent and compares them with other well blowout risk study results. It also provides an improved perspective on some of the findings. In short, this update finds that blowout rates have remained constant from 2005 to 2008 within the limits of resolution and that the decline in blowout rates from 1991 to 2005 was likely due to improved industry practice.« less

Impact of socioeconomic status on municipal solid waste generation rate.

PubMed

Khan, D; Kumar, A; Samadder, S R

2016-03-01

The solid waste generation rate was expected to vary in different socioeconomic groups due to many environmental and social factors. This paper reports the assessment of solid waste generation based on different socioeconomic parameters like education, occupation, income of the family, number of family members etc. A questionnaire survey was conducted in the study area to identify the different socioeconomic groups that may affect the solid waste generation rate and composition. The average waste generated in the municipality is 0.41 kg/capita/day in which the maximum waste was found to be generated by lower middle socioeconomic group (LMSEG) with average waste generation of 0.46 kg/capita/day. Waste characterization indicated that there was no much difference in the composition of wastes among different socioeconomic groups except ash residue and plastic. Ash residue is found to increase as we move lower down the socioeconomic groups with maximum (31%) in lower socioeconomic group (LSEG). The study area is a coal based city hence application of coal and wood as fuel for cooking in the lower socioeconomic group is the reason for high amount of ash content. Plastic waste is maximum (15%) in higher socioeconomic group (HSEG) and minimum (1%) in LSEG. Food waste is a major component of generated waste in almost every socioeconomic group with maximum (38%) in case of HSEG and minimum (28%) in LSEG. This study provides new insights on the role of various socioeconomic parameters on generation of household wastes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Method of controlling temperature of a thermoelectric generator in an exhaust system

DOEpatents

Prior, Gregory P; Reynolds, Michael G; Cowgill, Joshua D

2013-05-21

A method of controlling the temperature of a thermoelectric generator (TEG) in an exhaust system of an engine is provided. The method includes determining the temperature of the heated side of the TEG, determining exhaust gas flow rate through the TEG, and determining the exhaust gas temperature through the TEG. A rate of change in temperature of the heated side of the TEG is predicted based on the determined temperature, the determined exhaust gas flow rate, and the determined exhaust gas temperature through the TEG. Using the predicted rate of change of temperature of the heated side, exhaust gas flow rate through the TEG is calculated that will result in a maximum temperature of the heated side of the TEG less than a predetermined critical temperature given the predicted rate of change in temperature of the heated side of the TEG. A corresponding apparatus is provided.

Testing and Functions of the J2X Gas Generator

NASA Technical Reports Server (NTRS)

Miller, Nicholas

2009-01-01

The Ares I, NASA s new solid rocket based crew launch vehicle, is a two stage in line rocket that has made its waytothe forefront of NASA s endeavors. The Ares I s Upper Stage (US) will be propelled by a J-2X engine which is fueled by liquid hydrogen and liquid oxygen. The J-2X is a variation based on two of its predecessor s, the J-2 and J-2S engines. ET50 is providing the design support for hardware required to run tests on the J-2X Gas Generator (GG) that increases the delivery pressure of the supplied combustion fuels that the engine burns. The test area will be running a series of tests using different lengths and curved segments of pipe and different sized nozzles to determine the configuration that best satisfies the thrust, heat, and stability requirements for the engine. I have had to research the configurations that are being tested and gain an understanding of the purpose of the tests. I then had to research the parts that would be used in the test configurations. I was taken to see parts similar to the ones used in the test configurations and was allowed to review drawings and dimensions used for those parts. My job over this summer has been to use the knowledge I have gained to design, model, and create drawings for the un-fabricated parts that are necessary for the J-2X Workhorse Gas Generator Phase IIcTest.

Performance of PEM fuel cells stack as affected by number of cell and gas flow-rate

NASA Astrophysics Data System (ADS)

Syampurwadi, A.; Onggo, H.; Indriyati; Yudianti, R.

2017-03-01

The proton exchange membrane fuel cell (PEMFC) is a promising technology as an alternative green energy due to its high power density, low operating temperatures, low local emissions, quiet operation and fast start up-shutdown. In order to apply fuel cell as portable power supply, the performance investigation of small number of cells is needed. In this study, PEMFC stacks consisting of 1, 3, 5 and 7-cells with an active area of 25 cm2 per cell have been designed and developed. Their was evaluated in variation of gas flow rate. The membrane electrode assembly (MEA) was prepared by hot-pressing commercial gas diffusion electrodes (Pt loading 0.5 mg/cm2) on pre-treated Nafion 117 membrane. The stacks were constructed using bipolar plates in serpentine pattern and Z-type gas flow configuration. The experimental results were presented as polarization and power output curves which show the effects of varying number of cells and H2/O2 flow-rates on the PEMFC performance. The experimental results showed that not only number of cells and gas flow-rates affected the fuel cells performance, but also the operating temperature as a result of electrochemistry reaction inside the cell.

The Use of Generating Sets with ING Gas Engines in "Shore to Ship" Systems

NASA Astrophysics Data System (ADS)

Tarnapowicz, Dariusz; German-Galkin, Sergiej

2016-09-01

The main sources of air pollution in ports are ships, on which electrical energy is produced in the autonomous generating sets Diesel-Generator. The most effective way to reduce harmful exhaust emissions from ships is to exclude marine generating sets and provide the shore-side electricity in "Shore to Ship" system. The main problem in the implementation of power supply for ships from land is connected with matching parameters of voltage in onshore network with marine network. Currently, the recommended solution is to supply ships from the onshore electricity network with the use of power electronic converters. This article presents an analysis of the "Shore to Ship" system with the use of generating sets with LNG gas engines. It shows topologies with LNG - Generator sets, environmental benefits of such a solution, advantages and disadvantages.

Slowing of Femtosecond Laser-Generated Nanoparticles in a Background Gas

DOE PAGES

Rouleau, Christopher M.; Puretzky, Alexander A.; Geohegan, David B.

2014-11-25

The slowing of Pt nanoparticles in argon background gas was characterized by Rayleigh scattering imaging using a plume of nanoparticles generated by femtosecond laser through thin film ablation (fs-TTFA) of 20 nanometers-thick Pt films. The ablation was performed at threshold laser energy fluences for complete film removal to provide a well-defined plume consisting almost entirely of nanoparticles traveling with a narrow velocity distribution, providing a unique system to unambiguously characterize the slowing of nanoparticles during interaction with background gases. Nanoparticles of ~200 nm diameter were found to decelerate in background Ar gas with pressures less than 50 Torr in goodmore » agreement with a linear drag model in the Epstein regime. Based on this model, the stopping distance of small nanoparticles in the plume was predicted and tested by particle collection in an off-axis geometry, and size distribution analysis by transmission electron microscopy. These results permit a basis to interpret nanoparticle propagation through background gases in laser ablation plumes that contain mixed components.« less

Generator replacement is associated with an increased rate of ICD lead alerts.

PubMed

Lovelock, Joshua D; Cruz, Cesar; Hoskins, Michael H; Jones, Paul; El-Chami, Mikhael F; Lloyd, Michael S; Leon, Angel; DeLurgio, David B; Langberg, Jonathan J

2014-10-01

Lead malfunction is an important cause of morbidity and mortality in patients with an implantable cardioverter-defibrillator (ICD). We have shown that the failure of recalled high-voltage leads significantly increases after ICD generator replacement. However, generator replacement has not been recognized as a predictor of lead failure in general. The purpose of this study is to assess the effect of ICD generator exchange on the rate of ICD lead alerts. A time-dependent Cox proportional hazards model was used to analyze a database of remotely monitored ICDs. The model assessed the impact of generator exchange on the rate of lead alerts after ICD generator replacement. The analysis included 60,219 patients followed for 37 ± 19 months. The 5-year lead survival was 99.3% (95% confidence interval 99.2%-99.4%). Of 60,219 patients, 7458 patients (12.9%) underwent ICD generator exchange without lead replacement. After generator replacement, the rate of lead alerts was more than 5-fold higher than in controls with leads of the same age without generator replacement (hazard ratio 5.19; 95% confidence interval 3.45-7.84). A large number of lead alerted within 3 months of generator replacement. Lead alerts were more common in patients with single- vs dual-chamber ICDs and in younger patients. Sex was not associated with lead alerts. Routine generator replacement is associated with a 5-fold higher risk of lead alert compared to age-matched leads without generator replacement. This suggests the need for intense surveillance after generator replacement and the development of techniques to minimize the risk of lead damage during generator replacement. Copyright © 2014 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

A new portable generator to dynamically produce SI-traceable reference gas mixtures for VOCs and water vapour at atmospheric concentration

NASA Astrophysics Data System (ADS)

Guillevic, Myriam; Pascale, Céline; Ackermann, Andreas; Leuenberger, Daiana; Niederhauser, Bernhard

2016-04-01

In the framework of the KEY-VOCs and AtmoChem-ECV projects, we are currently developing new facilities to dynamically generate reference gas mixtures for a variety of reactive compounds, at concentrations measured in the atmosphere and in a SI-traceable way (i.e. the amount of substance fraction in mole per mole is traceable to SI-units). Here we present the realisation of such standards for water vapour in the range 1-10 μmol/mol and for volatile organic compounds (VOCs) such as limonene, alpha-pinene, MVK, MEK, in the nmol/mol range. The matrix gas can be nitrogen or synthetic air. Further development in gas purification techniques could make possible to use purified atmospheric air as carrier gas. The method is based on permeation and dynamic dilution: one permeator containing a pure substance (either water, limonene, MVK, MEK or α-pinene) is kept into a permeation chamber with a constant gas flow. The mass loss is precisely calibrated using a magnetic suspension balance. The carrier gas is purified beforehand from the compounds of interest to the required level, using commercially available purification cartridges. This primary mixture is then diluted to reach the required amount of substance fraction. All flows are piloted by mass flow controllers which makes the production process flexible and easily adaptable to generate the required concentration. All parts in contact with the gas mixture are passivated using coated surfaces, to reduce adsorption/desorption processes as much as possible. Two setups are currently developed: one already built and fixed in our laboratory in Bern as well as a portable generator that is still under construction and that could be used anywhere in the field. The permeation chamber of the portable generator has multiple individual cells allowing the generation of mixtures up to 5 different components if needed. Moreover the presented technique can be adapted and applied to a large variety of molecules (e.g., NO2, BTEX, CFCs

Risk Analysis using Corrosion Rate Parameter on Gas Transmission Pipeline

NASA Astrophysics Data System (ADS)

Sasikirono, B.; Kim, S. J.; Haryadi, G. D.; Huda, A.

2017-05-01

In the oil and gas industry, the pipeline is a major component in the transmission and distribution process of oil and gas. Oil and gas distribution process sometimes performed past the pipeline across the various types of environmental conditions. Therefore, in the transmission and distribution process of oil and gas, a pipeline should operate safely so that it does not harm the surrounding environment. Corrosion is still a major cause of failure in some components of the equipment in a production facility. In pipeline systems, corrosion can cause failures in the wall and damage to the pipeline. Therefore it takes care and periodic inspections or checks on the pipeline system. Every production facility in an industry has a level of risk for damage which is a result of the opportunities and consequences of damage caused. The purpose of this research is to analyze the level of risk of 20-inch Natural Gas Transmission Pipeline using Risk-based inspection semi-quantitative based on API 581 associated with the likelihood of failure and the consequences of the failure of a component of the equipment. Then the result is used to determine the next inspection plans. Nine pipeline components were observed, such as a straight pipes inlet, connection tee, and straight pipes outlet. The risk assessment level of the nine pipeline’s components is presented in a risk matrix. The risk level of components is examined at medium risk levels. The failure mechanism that is used in this research is the mechanism of thinning. Based on the results of corrosion rate calculation, remaining pipeline components age can be obtained, so the remaining lifetime of pipeline components are known. The calculation of remaining lifetime obtained and the results vary for each component. Next step is planning the inspection of pipeline components by NDT external methods.

Thermal history of sedimentary basins, maturation indices, and kinetics of oil and gas generation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tissot, B.P.; Pelet, R.; Ungerer, P.

1987-12-01

Temperature is the most sensitive parameter in hydrocarbon generation. Thus, reconstruction of temperature history is essential when evaluating petroleum prospects. No measurable parameter can be directly converted to paleotemperature. Maturation indices such as vitrinite reflectance, T/sub max/ from Rock-Eval pyrolysis, spore coloration, Thermal Alteration Index (TAI), or concentration of biological markers offer an indirect approach. All these indices are a function of the thermal history through rather complex kinetics, frequently influenced by the type of organic matter. Their significance and validity are reviewed. Besides the problems of identification (e.g. vitrinite) and interlaboratory calibration, it is important to simultaneously interpret kerogenmore » type and maturation and to avoid difficult conversions from one index to another. Geodynamic models, where structural and thermal histories are connected, are another approach to temperature reconstruction which could be calibrated against the present distribution of temperature and the present value of maturation indices. Kinetics of kerogen decomposition controls the amount and composition of hydrocarbons generated. An empirical time-temperature index (TTI), originally introduced by Lopatin, does not allow such a quantitative evaluation. Due to several limitations (no provision for different types of kerogen and different rates of reactions, poor calibration on vitrinite reflectance), it is of limited interest unless one has no access to a desk-top computer. Kinetic models, based on a specific calibration made on actual source rock samples, can simulate the evolution of all types of organic matter and can provide a quantitative evaluation of oil and gas generated. 29 figures.« less

Determination of the rate of crystal growth from the gas phase under conditions of turbulent free convection

NASA Astrophysics Data System (ADS)

Alad'Ev, S. I.

1987-04-01

Crystal growth in vertical and horizontal cylindrical vials, with the substrate and the source serving as the vial ends, is investigated analytically, assuming that the medium consists of a binary mixture of an active and an inert gas. The active gas is made up of the gaseous products of reactions taking place at the substrate and at the source. It is shown that turbulent free convection leads to an increase in crystal growth rate. All other conditions being equal, crystal growth in vertical vials is greater than that in horizontal ones; in both cases crystal growth rate increases with the vial radius, temperature gradient in the gas phase, and gas phase density. The results are compared with experimental data on the growth of Ge crystals in the Ge-GeI4 system.

Standby Rates for Combined Heat and Power Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sedano, Richard; Selecky, James; Iverson, Kathryn

2014-02-01

Improvements in technology, low natural gas prices, and more flexible and positive attitudes in government and utilities are making distributed generation more viable. With more distributed generation, notably combined heat and power, comes an increase in the importance of standby rates, the cost of services utilities provide when customer generation is not operating or is insufficient to meet full load. This work looks at existing utility standby tariffs in five states. It uses these existing rates and terms to showcase practices that demonstrate a sound application of regulatory principles and ones that do not. The paper also addresses areas formore » improvement in standby rates.« less

The interaction of intense, ultra-short microwave beams with the plasma generated by gas ionization

NASA Astrophysics Data System (ADS)

Shafir, G.; Cao, Y.; Bliokh, Y.; Leopold, J. G.; Levko, D.; Rostov, V.; Gad, R.; Fisher, A.; Bernshtam, V.; Krasik, Ya. E.

2018-03-01

Results of the non-linear interaction of an extremely short (0.6 ns) high power (˜500 MW) X-band focused microwave beam with the plasma generated by gas ionization are presented. Within certain gas pressure ranges, specific to the gas type, the plasma density is considerably lower around the microwave beam axis than at its periphery, thus forming guiding channel through which the beam self-focuses. Outside these pressure ranges, either diffuse or streamer-like plasma is observed. We also observe high energy electrons (˜15 keV), accelerated by the very high-power microwaves. A simplified analytical model of this complicated dynamical system and particle-in-cell numerical simulations confirm the experimental results.

Radionuclide gas transport through nuclear explosion-generated fracture networks

DOE PAGES

Jordan, Amy B.; Stauffer, Philip H.; Knight, Earl E.; ...

2015-12-17

Underground nuclear weapon testing produces radionuclide gases which may seep to the surface. Barometric pumping of gas through explosion-fractured rock is investigated using a new sequentially-coupled hydrodynamic rock damage/gas transport model. Fracture networks are produced for two rock types (granite and tuff) and three depths of burial. The fracture networks are integrated into a flow and transport numerical model driven by surface pressure signals of differing amplitude and variability. There are major differences between predictions using a realistic fracture network and prior results that used a simplified geometry. Matrix porosity and maximum fracture aperture have the greatest impact on gasmore » breakthrough time and window of opportunity for detection, with different effects between granite and tuff simulations highlighting the importance of accurately simulating the fracture network. In particular, maximum fracture aperture has an opposite effect on tuff and granite, due to different damage patterns and their effect on the barometric pumping process. From stochastic simulations using randomly generated hydrogeologic parameters, normalized detection curves are presented to show differences in optimal sampling time for granite and tuff simulations. In conclusion, seasonal and location-based effects on breakthrough, which occur due to differences in barometric forcing, are stronger where the barometric signal is highly variable.« less

Radionuclide gas transport through nuclear explosion-generated fracture networks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jordan, Amy B.; Stauffer, Philip H.; Knight, Earl E.

Underground nuclear weapon testing produces radionuclide gases which may seep to the surface. Barometric pumping of gas through explosion-fractured rock is investigated using a new sequentially-coupled hydrodynamic rock damage/gas transport model. Fracture networks are produced for two rock types (granite and tuff) and three depths of burial. The fracture networks are integrated into a flow and transport numerical model driven by surface pressure signals of differing amplitude and variability. There are major differences between predictions using a realistic fracture network and prior results that used a simplified geometry. Matrix porosity and maximum fracture aperture have the greatest impact on gasmore » breakthrough time and window of opportunity for detection, with different effects between granite and tuff simulations highlighting the importance of accurately simulating the fracture network. In particular, maximum fracture aperture has an opposite effect on tuff and granite, due to different damage patterns and their effect on the barometric pumping process. From stochastic simulations using randomly generated hydrogeologic parameters, normalized detection curves are presented to show differences in optimal sampling time for granite and tuff simulations. In conclusion, seasonal and location-based effects on breakthrough, which occur due to differences in barometric forcing, are stronger where the barometric signal is highly variable.« less

New insights on timing of oil and gas generation in the central Gulf Coast interior zone based on hydrous-pyrolysis kinetic parameters

USGS Publications Warehouse

Lewan, Michael D.; Dutton, Shirley P.; Ruppel, Stephen C.; Hentz, Tucker F.

2002-01-01

Timing of oil and gas generation from Turonian and Smackover source rocks in the central Gulf CoastInterior Zone was determined in one-dimensional burial-history curves (BHCs) using hydrous-pyrolysis kinetic parameters. The results predict that basal Smackover source-rock intervals with Type-IIS kerogen completed oil generation between 121 and 99 Ma, and Turonian source-rocks with Type-II kerogen remain immature over most of the same area. The only exception to the latter occurs in the northwestern part of the Mississippi salt basin, where initial stages of oil generation have started as a result of higher thermal gradients. This maturity difference between Turonian and Smackover source rocks is predicted with present-day thermal gradients. Predicted oil generation prior to the Sabine and Monroe uplifts suggests that a significant amount of the oil emplaced in Cretaceous reservoirs of these uplifts would have been lost during periods of erosion. Hydrous-pyrolysis kineticparameters predict that cracking of Smackover oil to gas started 52 Ma, which postdates major uplift and erosional events of the Sabine and Monroe uplifts. This generated gas would accumulate and persist in these uplift areas as currently observed. The predicted timing of oil and gas generation with hydrous-pyrolysis kinetic parameters is in accordance with the observed scarcity of oil from Turonian source rocks, predominance of gas accumulations on the Sabine and Monroe uplifts, and predominance of oil accumulations along the northern rim of the Interior Zone.

Rate of disappearance of gas bubble trauma signs in juvenile salmonids

USGS Publications Warehouse

Hans, K.M.; Mesa, M.G.; Maule, A.G.

1999-01-01

To assess the rate of disappearance of gas bubble trauma (GBT) signs in juvenile salmonids, we exposed spring chinook salmon Oncorhynchus tshawytscha and steelhead O. mykiss to water containing high levels of dissolved gas supersaturation (DGS) for a time period sufficient to induce signs of GBT, reduced the DGS to minimal levels, and then sampled fish through time to document changes in severity of GBT. Because of the tendency of GBT signs to dissipate at different rates, we conducted trials focusing on emboli (bubbles) in the gill filaments and lateral line and separate trials that focused on bubbles in the external surfaces (fins, eyes, and opercula). Bubbles in gill filaments dissipated almost completely within 2 h after transfer of fish to water of nearly normal DGS (104%), whereas bubbles in the lateral line dissipated to negligible levels within 5 h. Bubbles on external surfaces were more persistent through time than they were in gill filaments and the lateral line. Although typically dissipating to low levels within 48 h, external bubbles sometimes remained for 4 d. Assuming a direct relation exists between easily observable signs and direct mortality, our results suggest that fish can recover quickly from the potentially lethal effects of DGS once they move from water with high DGS to water of almost normal gas saturation. These results should be of fundamental importance to fishery managers interpreting the results of monitoring for the severity and prevalence of GBT in juvenile salmonids in the Columbia River system and perhaps elsewhere.

[Chronic CO poisoning. Use of generator gas during the second world war and recent research].

PubMed

Tvedt, B; Kjuus, H

1997-06-30

The consequences of long-lasting and low-grade exposure to carbon monoxide are a matter of debate. During the second world war, lack of petrol led to widespread use of wood as fuel (generator gas vehicles), especially in the Nordic countries. This caused many cases of "acute" or "chronic" carbon monoxide poisoning. Typical symptoms of "chronic poisoning" were headache, dizziness and tiredness. Usually the symptoms disappeared after some weeks or month, but in some patients probably became permanent. The experiences from the generator gas era are now almost forgotten, and chronic carbon monoxide poisoning is easily overlooked. The authors describe two cases of such poisoning. A crane driver at a smelting works developed permanent symptoms after twenty years of exposure. A faulty oil-fired central heating system caused long-lasting symptoms in four members of a family.

Huge increase in gas phase nanoparticle generation by pulsed direct current sputtering in a reactive gas admixture

NASA Astrophysics Data System (ADS)

Polonskyi, Oleksandr; Peter, Tilo; Mohammad Ahadi, Amir; Hinz, Alexander; Strunskus, Thomas; Zaporojtchenko, Vladimir; Biederman, Hynek; Faupel, Franz

2013-07-01

Using reactive DC sputtering in a gas aggregation cluster source, we show that pulsed discharge gives rise to a huge increase in deposition rate of nanoparticles by more than one order of magnitude compared to continuous operation. We suggest that this effect is caused by an equilibrium between slight target oxidation (during "time-off") and subsequent sputtering of Ti oxides (sub-oxides) at "time-on" with high power impulse.

[Efficiency of oxidant gas generator cells powered by electric or solar energy].

PubMed

Brust Carmona, H; Benitez, A; Zarco, J; Sánchez, E; Mascher, I

1998-02-01

Diseases caused by microbial contaminants in drinking water continue to be a serious problem in countries like Mexico. Chlorination, using chlorine gas or chlorine compounds, is one of the best ways to treat drinking water. However, difficulties in handling chlorine gas and the inefficiency of hypochlorite solution dosing systems--due to sociopolitical, economic, and cultural factors--have reduced the utility of these chlorination procedures, especially in far-flung and inaccessible rural communities. These problems led to the development of appropriate technologies for the disinfection of water by means of the on-site generation of mixed oxidant gases (chlorine and ozone). This system, called MOGGOD, operates through the electrolysis of a common salt solution. Simulated system evaluation using a hydraulic model allowed partial and total costs to be calculated. When powered by electrical energy from the community power grid, the system had an efficiency of 90%, and in 10 hours it was able to generate enough gases to disinfect about 200 m3 of water at a cost of approximately N$8 (US $1.30). When the electrolytic cell was run on energy supplied through a photoelectric cell, the investment costs were higher. A system fed by photovoltaic cells could be justified in isolated communities that lack electricity but have a gravity-fed water distribution system.

Theranostic gas-generating nanoparticles for targeted ultrasound imaging and treatment of neuroblastoma.

PubMed

Lee, Jangwook; Min, Hyun-Su; You, Dong Gil; Kim, Kwangmeyung; Kwon, Ick Chan; Rhim, Taiyoun; Lee, Kuen Yong

2016-02-10

The development of safe and efficient diagnostic/therapeutic agents for treating cancer in clinics remains challenging due to the potential toxicity of conventional agents. Although the annual incidence of neuroblastoma is not that high, the disease mainly occurs in children, a population vulnerable to toxic contrast agents and therapeutics. We demonstrate here that cancer-targeting, gas-generating polymeric nanoparticles are useful as a theranostic tool for ultrasound (US) imaging and treating neuroblastoma. We encapsulated calcium carbonate using poly(d,l-lactide-co-glycolide) and created gas-generating polymer nanoparticles (GNPs). These nanoparticles release carbon dioxide bubbles under acidic conditions and enhance US signals. When GNPs are modified using rabies virus glycoprotein (RVG) peptide, a targeting moiety to neuroblastoma, RVG-GNPs effectively accumulate at the tumor site and substantially enhance US signals in a tumor-bearing mouse model. Intravenous administration of RVG-GNPs also reduces tumor growth in the mouse model without the use of conventional therapeutic agents. This approach to developing theranostic agents with disease-targeting ability may provide useful strategy for the detection and treatment of cancers, allowing safe and efficient clinical applications with fewer side effects than may occur with conventional agents. Copyright © 2015 Elsevier B.V. All rights reserved.

Analysis of hydrocarbons generated in coalbeds

NASA Astrophysics Data System (ADS)

Butala, Steven John M.

This dissertation describes kinetic calculations using literature data to predict formation rates and product yields of oil and gas at typical low-temperature conditions in coalbeds. These data indicate that gas formation rates from hydrocarbon thermolysis are too low to have generated commercial quantities of natural gas, assuming bulk first-order kinetics. Acid-mineral-catalyzed cracking, transition-metal-catalyzed hydrogenolysis of liquid hydrocarbons, and catalyzed CO2 hydrogenation form gas at high rates. The gaseous product compositions for these reactions are nearly the same as those for typical natural coalbed gases, while those from thermal and catalytic cracking are more representative of atypical coalbed gases. Three Argonne Premium Coals (Upper-Freeport, Pittsburgh #8 and Lewiston-Stockton) were extracted with benzene in both Soxhlet and elevated pressure extraction (EPE) systems. The extracts were compared on the basis of dry mass yield and hydrocarbon profiles obtained by gas chromatography/mass spectrometry. The dry mass yields for the Upper-Freeport coal gave consistent results by both methods, while the yields from the Pittsburgh #8 and Lewiston-Stockton coals were greater by the EPE method. EPE required ˜90 vol. % less solvent compared to Soxhlet extraction. Single-ion-chromatograms of the Soxhlet extracts all exhibited bimodal distributions, while those of the EPE extracts did not. Hydrocarbons analyzed from Greater Green River Basin samples indicate that the natural oils in the basin originated from the coal seams. Analysis of artificially produced oil indicates that hydrous pyrolysis mimics generation of C15+ n-alkanes, but significant variations were found in the branched alkane, low-molecular-weight n-alkanes, and high-molecular-weight aromatic hydrocarbon distributions.

Comparison of pollutant emission rates from unvented kerosene and gas space heaters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Apte, M.G.; Traynor, G.W.

1986-05-01

In this paper the pollutant emission rates of all five types of unvented space heaters are compared. Pollutant emission rates for carbon dioxide, carbon monoxide (CO), nitric oxide, nitrogen dioxide (NO/sub 2/), formaldehyde, and submicron suspended particles were measured. Special emphasis is placed on CO and NO/sub 2/ emissions. Pollutant measurements were made in a 27-m/sup 3/ environmental chamber and emission rates were calculated using a mass-balance model. Emission rates for propane and natural gas space heaters were similar. Emissions from the various types of heaters fall into three distinct groups. The groups are better characterized by burner design thanmore » by the type of fuel used. Radiant kerosene heaters and infrared UVGSHs constitute one group; convective kerosene heaters and convective UVGSHs the second, and two-stage kerosene heaters the third group. When groups are compared, emission rates vary by an order of magnitude for carbon monoxide and for nitrogen dioxide. The two-stage kerosene heaters emitted the least CO and also the least NO/sub 2/ per unit of fuel energy consumed. The radiant/infrared heaters emitted the most CO, and the convective heaters emitted the most NO/sub 2/. The effects of various operation parameters such as the wick height for kerosene heaters and the air shutter adjustment for gas heaters are discussed. Convective UVGSHs operating at half input were found to have lower emission rates on average than when operating at full input. Some maltuned convective UVGSHs were capable of emitting very high amounts of CO. Kerosene heaters were found to emit more CO and NO/sub 2/ on average when they were operated with lowered wicks.« less

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.

Mitigation of Hydrogen Gas Generation from the Reaction of Uranium Metal with Water in K Basin Sludge and Sludge Waste Forms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sinkov, Sergey I.; Delegard, Calvin H.; Schmidt, Andrew J.

2011-06-08

Prior laboratory testing identified sodium nitrate and nitrite to be the most promising agents to minimize hydrogen generation from uranium metal aqueous corrosion in Hanford Site K Basin sludge. Of the two, nitrate was determined to be better because of higher chemical capacity, lower toxicity, more reliable efficacy, and fewer side reactions than nitrite. The present lab tests were run to determine if nitrate’s beneficial effects to lower H2 generation in simulated and genuine sludge continued for simulated sludge mixed with agents to immobilize water to help meet the Waste Isolation Pilot Plant (WIPP) waste acceptance drainable liquid criterion. Testsmore » were run at ~60°C, 80°C, and 95°C using near spherical high-purity uranium metal beads and simulated sludge to emulate uranium-rich KW containerized sludge currently residing in engineered containers KW-210 and KW-220. Immobilization agents tested were Portland cement (PC), a commercial blend of PC with sepiolite clay (Aquaset II H), granulated sepiolite clay (Aquaset II G), and sepiolite clay powder (Aquaset II). In all cases except tests with Aquaset II G, the simulated sludge was mixed intimately with the immobilization agent before testing commenced. For the granulated Aquaset II G clay was added to the top of the settled sludge/solution mixture according to manufacturer application directions. The gas volumes and compositions, uranium metal corrosion mass losses, and nitrite, ammonia, and hydroxide concentrations in the interstitial solutions were measured. Uranium metal corrosion rates were compared with rates forecast from the known uranium metal anoxic water corrosion rate law. The ratios of the forecast to the observed rates were calculated to find the corrosion rate attenuation factors. Hydrogen quantities also were measured and compared with quantities expected based on non-attenuated H2 generation at the full forecast anoxic corrosion rate to arrive at H2 attenuation factors. The uranium

Radiolytic and thermolytic bubble gas hydrogen composition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woodham, W.

This report describes the development of a mathematical model for the estimation of the hydrogen composition of gas bubbles trapped in radioactive waste. The model described herein uses a material balance approach to accurately incorporate the rates of hydrogen generation by a number of physical phenomena and scale the aforementioned rates in a manner that allows calculation of the final hydrogen composition.

Onboard Inert Gas Generation System/Onboard Oxygen Gas Generation System (OBIGGS/OBOGS) Study. Part 2; Gas Separation Technology--State of the Art

NASA Technical Reports Server (NTRS)

Reynolds, Thomas L.; Eklund, Thor I.; Haack, Gregory A.

2001-01-01

This purpose of this contract study task was to investigate the State of the Art in Gas Separation Technologies utilized for separating air into both nitrogen and oxygen gases for potential applications on commercial aircraft. The intended applications included: nitrogen gas for fuel tank inerting, cargo compartment fire protection, and emergency oxygen for passenger and crew use in the event of loss of cabin pressure. The approach was to investigate three principle methods of gas separation: Hollow Fiber Membrane (HFM), Ceramic Membrane (CM), and liquefaction: Total Atmospheric Liquefaction of Oxygen and Nitrogen (TALON). Additional data on the performance of molecular sieve pressure swing adsorption (PSA) systems was also collected and discussed. Performance comparisons of these technologies are contained in the body of the report.

Dispersion tuning in sub-micron tapers for third-harmonic and photon triplet generation.

PubMed

Hammer, Jonas; Cavanna, Andrea; Pennetta, Riccardo; Chekhova, Maria V; Russell, Philip St J; Joly, Nicolas Y

2018-05-15

Precise control of the dispersion landscape is of crucial importance if optical fibers are to be successfully used for the generation of three-photon states of light-the inverse of third-harmonic generation (THG). Here we report gas-tuning of intermodal phase-matched THG in sub-micron-diameter tapered optical fiber. By adjusting the pressure of the surrounding argon gas up to 50 bars, intermodally phase-matched third-harmonic light can be generated for pump wavelengths within a 15 nm range around 1.38 μm. We also measure the infrared fluorescence generated in the fiber when pumped in the visible and estimate that the accidental coincidence rate in this signal is lower than the predicted detection rate of photon triplets.

Strengthened MILP formulation for certain gas turbine unit commitment problems

DOE PAGES

Pan, Kai; Guan, Yongpei; Watson, Jean -Paul; ...

2015-05-22

In this study, we derive a strengthened MILP formulation for certain gas turbine unit commitment problems, in which the ramping rates are no smaller than the minimum generation amounts. This type of gas turbines can usually start-up faster and have a larger ramping rate, as compared to the traditional coal-fired power plants. Recently, the number of this type of gas turbines increases significantly due to affordable gas prices and their scheduling flexibilities to accommodate intermittent renewable energy generation. In this study, several new families of strong valid inequalities are developed to help reduce the computational time to solve these typesmore » of problems. Meanwhile, the validity and facet-defining proofs are provided for certain inequalities. Finally, numerical experiments on a modified IEEE 118-bus system and the power system data based on recent studies verify the effectiveness of applying our formulation to model and solve this type of gas turbine unit commitment problems, including reducing the computational time to obtain an optimal solution or obtaining a much smaller optimality gap, as compared to the default CPLEX, when the time limit is reached with no optimal solutions obtained.« less

Burial history, thermal maturity, and oil and gas generation history of petroleum systems in the Wind River Basin Province, central Wyoming: Chapter 6 in Petroleum systems and geologic assessment of oil and gas resources in the Wind River Basin Province, Wyoming

USGS Publications Warehouse

Roberts, Laura N.R.; Finn, Thomas M.; Lewan, Michael D.; Kirschbaum, Mark A.

2007-01-01

Burial history, thermal maturity, and timing of oil and gas generation were modeled for eight key source rock units at nine well locations throughout the Wind River Basin Province. Petroleum source rocks include the Permian Phosphoria Formation, the Cretaceous Mowry Shale, Cody Shale, and Mesaverde, Meeteetse, and Lance Formations, and the Tertiary (Paleocene) Fort Union Formation, including the Waltman Shale Member. Within the province boundary, the Phosphoria is thin and only locally rich in organic carbon. Phosphoria oil produced from reservoirs in the province is thought to have migrated from the Wyoming and Idaho thrust belt. Locations (wells) selected for burial history reconstructions include three in the deepest parts of the province (Adams OAB-17, Bighorn 1-5, and Coastal Owl Creek); three at intermediate depths (Hells Half Acre, Shell 33X-10, and West Poison Spider); and three at relatively shallow locations (Young Ranch, Amoco Unit 100, and Conoco-Coal Bank). The thermal maturity of source rocks is greatest in the deep northern and central parts of the province and decreases to the south and east toward the basin margins. The results of the modeling indicate that, in the deepest areas, (1) peak petroleum generation from Cretaceous rocks occurred from Late Cretaceous through middle Eocene time, and (2) onset of oil generation from the Waltman Shale Member occurred from late Eocene to early Miocene time. Based on modeling results, gas generation from the cracking of Phosphoria oil reservoired in the Park City Formation reached a peak in the late Paleocene/early Eocene (58 to 55 Ma) only in the deepest parts of the province. The Mowry Shale and Cody Shale (in the eastern half of the basin) contain a mix of Type-II and Type-III kerogens. Oil generation from predominantly Type-II source rocks of these units in the deepest parts of the province reached peak rates during the latest Cretaceous to early Eocene (65 to 55 Ma). Only in these areas of the basin did

MHD Generating system

DOEpatents

Petrick, Michael; Pierson, Edward S.; Schreiner, Felix

1980-01-01

According to the present invention, coal combustion gas is the primary working fluid and copper or a copper alloy is the electrodynamic fluid in the MHD generator, thereby eliminating the heat exchangers between the combustor and the liquid-metal MHD working fluids, allowing the use of a conventional coalfired steam bottoming plant, and making the plant simpler, more efficient and cheaper. In operation, the gas and liquid are combined in a mixer and the resulting two-phase mixture enters the MHD generator. The MHD generator acts as a turbine and electric generator in one unit wherein the gas expands, drives the liquid across the magnetic field and thus generates electrical power. The gas and liquid are separated, and the available energy in the gas is recovered before the gas is exhausted to the atmosphere. Where the combustion gas contains sulfur, oxygen is bubbled through a side loop to remove sulfur therefrom as a concentrated stream of sulfur dioxide. The combustor is operated substoichiometrically to control the oxide level in the copper.

Evolution of supersaturation of amorphous pharmaceuticals: the effect of rate of supersaturation generation.

PubMed

Sun, Dajun D; Lee, Ping I

2013-11-04

The combination of a rapidly dissolving and supersaturating "spring" with a precipitation retarding "parachute" has often been pursued as an effective formulation strategy for amorphous solid dispersions (ASDs) to enhance the rate and extent of oral absorption. However, the interplay between these two rate processes in achieving and maintaining supersaturation remains inadequately understood, and the effect of rate of supersaturation buildup on the overall time evolution of supersaturation during the dissolution of amorphous solids has not been explored. The objective of this study is to investigate the effect of supersaturation generation rate on the resulting kinetic solubility profiles of amorphous pharmaceuticals and to delineate the evolution of supersaturation from a mechanistic viewpoint. Experimental concentration-time curves under varying rates of supersaturation generation and recrystallization for model drugs, indomethacin (IND), naproxen (NAP) and piroxicam (PIR), were generated from infusing dissolved drug (e.g., in ethanol) into the dissolution medium and compared with that predicted from a comprehensive mechanistic model based on the classical nucleation theory taking into account both the particle growth and ripening processes. In the absence of any dissolved polymer to inhibit drug precipitation, both our experimental and predicted results show that the maximum achievable supersaturation (i.e., kinetic solubility) of the amorphous solids increases, the time to reach maximum decreases, and the rate of concentration decline in the de-supersaturation phase increases, with increasing rate of supersaturation generation (i.e., dissolution rate). Our mechanistic model also predicts the existence of an optimal supersaturation rate which maximizes the area under the curve (AUC) of the kinetic solubility concentration-time profile, which agrees well with experimental data. In the presence of a dissolved polymer from ASD dissolution, these observed trends

Bayesian Estimation of Fugitive Methane Point Source Emission Rates from a SingleDownwind High-Frequency Gas Sensor

EPA Science Inventory

Bayesian Estimation of Fugitive Methane Point Source Emission Rates from a Single Downwind High-Frequency Gas Sensor With the tremendous advances in onshore oil and gas exploration and production (E&P) capability comes the realization that new tools are needed to support env...

Demand charge reduction with digester gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1985-02-01

This paper examines a rather sophisticated treatment system in the city of Whitewater, Wisconsin. The power generated is used to trim utility peak power loads and demand charges. Power is derived from four Waukesha VHP 3600G engine generator sets with provisions for a fifth as growth requires. The engine is a Waukesha F3521GU spark ignited, six-cylinder gas engine with 9.375 in. x 8.50 bore and stroke driving a Kato 350 kW generator rated at 480/277 volts and 1200 rpm. Normal operation is to reduce the peak demand.

Gas breakthrough and emission through unsaturated compacted clay in landfill final cover

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ng, C.W.W.; Chen, Z.K.; Coo, J.L.

Highlights: • Explore feasibility of unsaturated clay as a gas barrier in landfill cover. • Gas breakthrough pressure increases with clay thickness and degree of saturation. • Gas emission rate decreases with clay thickness and degree of saturation. • A 0.6 m-thick clay layer may be sufficient to meet gas emission rate limit. - Abstract: Determination of gas transport parameters in compacted clay plays a vital role for evaluating the effectiveness of soil barriers. The gas breakthrough pressure has been widely studied for saturated swelling clay buffer commonly used in high-level radioactive waste disposal facility where the generated gas pressuremore » is very high (in the order of MPa). However, compacted clay in landfill cover is usually unsaturated and the generated landfill gas pressure is normally low (typically less than 10 kPa). Furthermore, effects of clay thickness and degree of saturation on gas breakthrough and emission rate in the context of unsaturated landfill cover has not been quantitatively investigated in previous studies. The feasibility of using unsaturated compacted clay as gas barrier in landfill covers is thus worthwhile to be explored over a wide range of landfill gas pressures under various degrees of saturation and clay thicknesses. In this study, to evaluate the effectiveness of unsaturated compacted clay to minimize gas emission, one-dimensional soil column tests were carried out on unsaturated compacted clay to determine gas breakthrough pressures at ultimate limit state (high pressure range) and gas emission rates at serviceability limit state (low pressure range). Various degrees of saturation and thicknesses of unsaturated clay sample were considered. Moreover, numerical simulations were carried out using a coupled gas–water flow finite element program (CODE-BRIGHT) to better understand the experimental results by extending the clay thickness and varying the degree of saturation to a broader range that is typical at

Gas exchange rates across the sediment-water and air-water interfaces in south San Francisco Bay

USGS Publications Warehouse

Hartman, Blayne; Hammond, Douglas E.

1984-01-01

Radon 222 concentrations in the water and sedimentary columns and radon exchange rates across the sediment-water and air-water interfaces have been measured in a section of south San Francisco Bay. Two independent methods have been used to determine sediment-water exchange rates, and the annual averages of these methods agree within the uncertainty of the determinations, about 20%. The annual average of benthic fluxes from shoal areas is nearly a factor of 2 greater than fluxes from the channel areas. Fluxes from the shoal and channel areas exceed those expected from simple molecular diffusion by factors of 4 and 2, respectively, apparently due to macrofaunal irrigation. Values of the gas transfer coefficient for radon exchange across the air-water interface were determined by constructing a radon mass balance for the water column and by direct measurement using floating chambers. The chamber method appears to yield results which are too high. Transfer coefficients computed using the mass balance method range from 0.4 m/day to 1.8 m/day, with a 6-year average of 1.0 m/day. Gas exchange is linearly dependent upon wind speed over a wind speed range of 3.2–6.4 m/s, but shows no dependence upon current velocity. Gas transfer coefficients predicted from an empirical relationship between gas exchange rates and wind speed observed in lakes and the oceans are within 30% of the coefficients determined from the radon mass balance and are considerably more accurate than coefficients predicted from theoretical gas exchange models.

Generator exchange is associated with an increased rate of Sprint Fidelis lead failure.

PubMed

Lovelock, Joshua D; Patel, Ayesha; Mengistu, Andenet; Hoskins, Michael; El-Chami, Mikhael; Lloyd, Michael S; Leon, Angel; DeLurgio, David; Langberg, Jonathan J

2012-10-01

The Medtronic Sprint Fidelis defibrillator lead is at an increased risk for failure and was recalled in October 2007. Approximately 268,000 leads were implanted, and more than 100,000 patients still have active Fidelis leads. A number of studies have examined the rate and clinical predictors of lead failure, but none has addressed the effect of an implantable cardioverter-defibrillator generator exchange on subsequent lead failure. Although the manufacturer asserts that "Sprint Fidelis performance after device change-out is similar to lead performance without device change-out," published data are lacking. To assess the effect of implantable cardioverter-defibrillator generator exchange on the rate of Fidelis lead failure. A chart review was conducted in patients who underwent implantation of a Fidelis lead. Patients with a functioning Fidelis lead at generator exchange were compared with controls with leads implanted for a comparable amount of time not undergoing ICD replacement. A total of 1366 patients received a Fidelis lead prior to the recall, of which 479 were still actively followed. Seventy-two patients with a functioning lead underwent generator exchange without lead replacement. Following generator replacement, 15 leads failed. Sixty percent of the Fidelis leads failed within 3 months. Generator exchange increased the rate of lead failure compared with matched controls (20.8% vs 2.54%; P < .001). Generator exchange is associated with a higher than expected rate of Fidelis lead failure, often within 3 months. The risk-benefit ratio of Fidelis lead replacement at the time of generator exchange may be greater than appreciated. Copyright © 2012 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Production efficiencies of U.S. electric generation plants: Effects of data aggregation and greenhouse gas and renewable energy policy

NASA Astrophysics Data System (ADS)

Lynes, Melissa Kate

Over the last few decades there has been a shift in electricity production in the U.S. Renewable energy sources are becoming more widely used. In addition, electric generation plants that use coal inputs are more heavily regulated than a couple decades ago. This shift in electricity production was brought on by changes in federal policy -- a desire for electricity produced in the U.S. which led to policies being adopted that encourage the use of renewable energy. The change in production practices due to policies may have led to changes in the productivity of electric generation plants. Multiple studies have examined the most efficient electric generation plants using the data envelopment analysis (DEA) approach. This study builds on past research to answer three questions: 1) Does the level of aggregation of fuel input variables affect the plant efficiency scores and how does the efficiency of renewable energy input compare to nonrenewable energy inputs; 2) Are policies geared toward directly or indirectly reducing greenhouse gas emissions affecting the production efficiencies of greenhouse gas emitting electric generation plants; and 3) Do renewable energy policies and the use of intermittent energy sources (i.e. wind and solar) affect the productivity growth of electric generation plants. All three analysis, presented in three essays, use U.S. plant level data obtained from the Energy Information Administration to answer these questions. The first two essays use DEA to determine the pure technical, overall technical, and scale efficiencies of electric generation plants. The third essay uses DEA within the Malmquist index to assess the change in productivity over time. Results indicate that the level of aggregation does matter particularly for scale efficiency. This implies that valuable information is likely lost when fuel inputs are aggregated together. Policies directly focused on reducing greenhouse gas emissions may improve the production efficiencies of

Motor unit firing rate patterns during voluntary muscle force generation: a simulation study

NASA Astrophysics Data System (ADS)

Hu, Xiaogang; Rymer, William Z.; Suresh, Nina L.

2014-04-01

Objective. Muscle force is generated by a combination of motor unit (MU) recruitment and changes in the discharge rate of active MUs. There have been two basic MU recruitment and firing rate paradigms reported in the literature, which describe the control of the MUs during force generation. The first (termed the reverse ‘onion skin’ profile), exhibits lower firing rates for lower threshold units, with higher firing rates occurring in higher threshold units. The second (termed the ‘onion skin’ profile), exhibits an inverse arrangement, with lower threshold units reaching higher firing rates. Approach. Using a simulation of the MU activity in a hand muscle, this study examined the force generation capacity and the variability of the muscle force magnitude at different excitation levels of the MU pool under these two different MU control paradigms. We sought to determine which rate/recruitment scheme was more efficient for force generation, and which scheme gave rise to the lowest force variability. Main results. We found that the force output of both firing patterns leads to graded force output at low excitation levels, and that the force generation capacity of the two different paradigms diverged around 50% excitation. In the reverse ‘onion skin’ pattern, at 100% excitation, the force output reached up to 88% of maximum force, whereas for the ‘onion skin’ pattern, the force output only reached up to 54% of maximum force at 100% excitation. The force variability was lower at the low to moderate force levels under the ‘onion skin’ paradigm than with the reverse ‘onion skin’ firing patterns, but this effect was reversed at high force levels. Significance. This study captures the influence of MU recruitment and firing rate organization on muscle force properties, and our results suggest that the different firing organizations can be beneficial at different levels of voluntary muscle force generation and perhaps for different tasks.

Flexible-rate optical packet generation/detection and label swapping for optical label switching networks

NASA Astrophysics Data System (ADS)

Wu, Zhongying; Li, Juhao; Tian, Yu; Ge, Dawei; Zhu, Paikun; Chen, Yuanxiang; Chen, Zhangyuan; He, Yongqi

2017-03-01

In recent years, optical label switching (OLS) gains lots of attentions due to its intrinsic advantages to implement protocol, bit-rate, granularity and data format transparency packet switching. In this paper, we propose a novel scheme to realize flexible-rate optical packet switching for OLS networks. At the transmitter node, flexible-rate packet is generated by parallel modulating different combinations of optical carriers generated from the optical multi-carrier generator (OMCG), among which the low-speed optical label occupies one carrier. At the switching node, label is extracted and re-generated in label processing unit (LPU). The payloads are switched based on routing information and new label is added after switching. At the receiver node, another OMCG serves as local oscillators (LOs) for optical payloads coherent detection. The proposed scheme offers good flexibility for dynamic optical packet switching by adjusting the payload bandwidth and could also effectively reduce the number of lasers, modulators and receivers for packet generation/detection. We present proof-of-concept demonstrations of flexible-rate packet generation/detection and label swapping in 12.5 GHz grid. The influence of crosstalk for cascaded label swapping is also investigated.

Viscous slip coefficients for binary gas mixtures measured from mass flow rates through a single microtube

NASA Astrophysics Data System (ADS)

Yamaguchi, H.; Takamori, K.; Perrier, P.; Graur, I.; Matsuda, Y.; Niimi, T.

2016-09-01

The viscous slip coefficient for helium-argon binary gas mixture is extracted from the experimental values of the mass flow rate through a microtube. The mass flow rate is measured by the constant-volume method. The viscous slip coefficient was obtained by identifying the measured mass flow rate through a microtube with the corresponding analytical expression, which is a function of the Knudsen number. The measurements were carried out in the slip flow regime where the first-order slip boundary condition can be applied. The measured viscous slip coefficients of binary gas mixtures exhibit a concave function of the molar ratio of the mixture, showing a similar profile with numerical results. However, from the detailed comparison between the measured and numerical values with the complete and incomplete accommodation at a surface, it is inappropriate to estimate the viscous slip coefficient for the mixture numerically by employing separately measured tangential momentum accommodation coefficient for each component. The time variation of the molar ratio in the downstream chamber was measured by sampling the gas from the chamber using the quadrupole mass spectrometer. In our measurements, it is indicated that the volume flow rate of argon is larger than that of helium because of the difference in the tangential momentum accommodation coefficient.

Pressure Dependence of Gas-Phase Reaction Rates

ERIC Educational Resources Information Center

De Persis, Stephanie; Dollet, Alain; Teyssandier, Francis

2004-01-01

It is presented that only simple concepts, mainly taken from activated-complex or transition-state theory, are required to explain and analytically describe the influence of pressure on gas-phase reaction kinetics. The simplest kind of elementary gas-phase reaction is a unimolecular decomposition reaction.

The Generation Rate of Respirable Dust from Cutting Fiber Cement Siding Using Different Tools

PubMed Central

Qi, Chaolong; Echt, Alan; Gressel, Michael G

2017-01-01

This article describes the evaluation of the generation rate of respirable dust (GAPS, defined as the mass of respirable dust generated per unit linear length cut) from cutting fiber cement siding using different tools in a laboratory testing system. We used an aerodynamic particle sizer spectrometer (APS) to continuously monitor the real-time size distributions of the dust throughout cutting tests when using a variety of tools, and calculated the generation rate of respirable dust for each testing condition using the size distribution data. The test result verifies that power shears provided an almost dust-free operation with a GAPS of 0.006 gram meter−1 (g m−1) at the testing condition. For the same power saws, the cuts using saw blades with more teeth generated more respirable dusts. Using the same blade for all four miter saws tested in this study, a positive linear correlation was found between the saws’ blade rotating speed and its dust generation rate. In addition, a circular saw running at the highest blade rotating speed of 9068 RPM generated the greatest amount of dust. All the miter saws generated less dust in the ‘chopping mode’ than in the ‘chopping and sliding’ mode. For the tested saws, GAPS consistently decreased with the increases of the saw cutting feed rate and the number of board in the stack. All the test results point out that fewer cutting interactions between the saw blade’s teeth and the siding board for a unit linear length of cut tend to result in a lower generation rate of respirable dust. These results may help guide optimal operation in practice and future tool development aimed at minimizing dust generation while producing a satisfactory cut. PMID:28395343

The Generation Rate of Respirable Dust from Cutting Fiber Cement Siding Using Different Tools.

PubMed

Qi, Chaolong; Echt, Alan; Gressel, Michael G

2017-03-01

This article describes the evaluation of the generation rate of respirable dust (GAPS, defined as the mass of respirable dust generated per unit linear length cut) from cutting fiber cement siding using different tools in a laboratory testing system. We used an aerodynamic particle sizer spectrometer (APS) to continuously monitor the real-time size distributions of the dust throughout cutting tests when using a variety of tools, and calculated the generation rate of respirable dust for each testing condition using the size distribution data. The test result verifies that power shears provided an almost dust-free operation with a GAPS of 0.006 g m-1 at the testing condition. For the same power saws, the cuts using saw blades with more teeth generated more respirable dusts. Using the same blade for all four miter saws tested in this study, a positive linear correlation was found between the saws' blade rotating speed and its dust generation rate. In addition, a circular saw running at the highest blade rotating speed of 9068 rpm generated the greatest amount of dust. All the miter saws generated less dust in the 'chopping mode' than in the 'chopping and sliding' mode. For the tested saws, GAPS consistently decreased with the increases of the saw cutting feed rate and the number of board in the stack. All the test results point out that fewer cutting interactions between the saw blade's teeth and the siding board for a unit linear length of cut tend to result in a lower generation rate of respirable dust. These results may help guide optimal operation in practice and future tool development aimed at minimizing dust generation while producing a satisfactory cut. Published by Oxford University Press on behalf of The British Occupational Hygiene Society 2017.

Life cycle greenhouse gas emissions and freshwater consumption of Marcellus shale gas.

PubMed

Laurenzi, Ian J; Jersey, Gilbert R

2013-05-07

We present results of a life cycle assessment (LCA) of Marcellus shale gas used for power generation. The analysis employs the most extensive data set of any LCA of shale gas to date, encompassing data from actual gas production and power generation operations. Results indicate that a typical Marcellus gas life cycle yields 466 kg CO2eq/MWh (80% confidence interval: 450-567 kg CO2eq/MWh) of greenhouse gas (GHG) emissions and 224 gal/MWh (80% CI: 185-305 gal/MWh) of freshwater consumption. Operations associated with hydraulic fracturing constitute only 1.2% of the life cycle GHG emissions, and 6.2% of the life cycle freshwater consumption. These results are influenced most strongly by the estimated ultimate recovery (EUR) of the well and the power plant efficiency: increase in either quantity will reduce both life cycle freshwater consumption and GHG emissions relative to power generated at the plant. We conclude by comparing the life cycle impacts of Marcellus gas and U.S. coal: The carbon footprint of Marcellus gas is 53% (80% CI: 44-61%) lower than coal, and its freshwater consumption is about 50% of coal. We conclude that substantial GHG reductions and freshwater savings may result from the replacement of coal-fired power generation with gas-fired power generation.

Local anticorrelation between star formation rate and gas-phase metallicity in disc galaxies

NASA Astrophysics Data System (ADS)

Sánchez Almeida, J.; Caon, N.; Muñoz-Tuñón, C.; Filho, M.; Cerviño, M.

2018-06-01

Using a representative sample of 14 star-forming dwarf galaxies in the local Universe, we show the existence of a spaxel-to-spaxel anticorrelation between the index N2 ≡ log ([N II]λ 6583/H α ) and the H α flux. These two quantities are commonly employed as proxies for gas-phase metallicity and star formation rate (SFR), respectively. Thus, the observed N2 to H α relation may reflect the existence of an anticorrelation between the metallicity of the gas forming stars and the SFR it induces. Such an anticorrelation is to be expected if variable external metal-poor gas fuels the star-formation process. Alternatively, it can result from the contamination of the star-forming gas by stellar winds and SNe, provided that intense outflows drive most of the metals out of the star-forming regions. We also explore the possibility that the observed anticorrelation is due to variations in the physical conditions of the emitting gas, other than metallicity. Using alternative methods to compute metallicity, as well as previous observations of H II regions and photoionization models, we conclude that this possibility is unlikely. The radial gradient of metallicity characterizing disc galaxies does not produce the correlation either.

Deconvolution of gas chromatographic data

NASA Technical Reports Server (NTRS)

Howard, S.; Rayborn, G. H.

1980-01-01

The use of deconvolution methods on gas chromatographic data to obtain an accurate determination of the relative amounts of each material present by mathematically separating the merged peaks is discussed. Data were obtained on a gas chromatograph with a flame ionization detector. Chromatograms of five xylenes with differing degrees of separation were generated by varying the column temperature at selected rates. The merged peaks were then successfully separated by deconvolution. The concept of function continuation in the frequency domain was introduced in striving to reach the theoretical limit of accuracy, but proved to be only partially successful.

Electricity generation from synthesis gas by microbial processes: CO fermentation and microbial fuel cell technology.

PubMed

Kim, Daehee; Chang, In Seop

2009-10-01

A microbiological process was established to harvest electricity from the carbon monoxide (CO). A CO fermenter was enriched with CO as the sole carbon source. The DGGE/DNA sequencing results showed that Acetobacterium spp. were enriched from the anaerobic digester fluid. After the fermenter was operated under continuous mode, the products were then continuously fed to the microbial fuel cell (MFC) to generate electricity. Even though the conversion yield was quite low, this study proved that synthesis gas (syn-gas) can be converted to electricity with the aid of microbes that do not possess the drawbacks of metal catalysts of conventional methods.

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

ablation. Two different ablation models are proposed to determine the heat loss from the solid surface due to the ablation of the solid material. Both of them are physics based. Various numerical simulations were carried out using both models to predict the temperature distribution in the solid and in the gas flow, and then predict the ablation rates at a typical NTR motor hydrogen gas temperature and pressure. Solid mass loss rate per foot of a pipe was also calculated from these predictions. The results are presented for fully developed turbulent flow conditions in a sample SS pipe with a 6 inch diameter.

Natural gas fugitive emissions rates constrained by global atmospheric methane and ethane.

PubMed

Schwietzke, Stefan; Griffin, W Michael; Matthews, H Scott; Bruhwiler, Lori M P

2014-07-15

The amount of methane emissions released by the natural gas (NG) industry is a critical and uncertain value for various industry and policy decisions, such as for determining the climate implications of using NG over coal. Previous studies have estimated fugitive emissions rates (FER)--the fraction of produced NG (mainly methane and ethane) escaped to the atmosphere--between 1 and 9%. Most of these studies rely on few and outdated measurements, and some may represent only temporal/regional NG industry snapshots. This study estimates NG industry representative FER using global atmospheric methane and ethane measurements over three decades, and literature ranges of (i) tracer gas atmospheric lifetimes, (ii) non-NG source estimates, and (iii) fossil fuel fugitive gas hydrocarbon compositions. The modeling suggests an upper bound global average FER of 5% during 2006-2011, and a most likely FER of 2-4% since 2000, trending downward. These results do not account for highly uncertain natural hydrocarbon seepage, which could lower the FER. Further emissions reductions by the NG industry may be needed to ensure climate benefits over coal during the next few decades.

Dust release rates and dust-to-gas mass ratios of eight comets

NASA Technical Reports Server (NTRS)

Singh, P. D.; De Almeida, A. A.; Huebner, W. F.

1992-01-01

Mass release rates of dust and mass ratios of dust-to-gas release rates of Comets Thiele (1985m), Wilson (1986l), P/Borrelly (1987p), Liller (1988a), Bradfield (1987s), Hartley-Good (1985l), P/Giacobini-Zinner (1984e), and P/Halley (1982i) are estimated from the analysis of continuum flux measurements at optical wavelengths. An attempt is made to estimate the size of each comet nucleus on the basis of water-ice sublimation (vaporization), assuming that the nucleus is spherical and only a fraction of its surface area is active. Where possible, the dust mass release rates are compared with those obtained by other investigators in the optical and IR wavelength regions. Good agreement with results based on IR observations is found.

Singlet oxygen generation in gas discharge for oxygen-iodine laser pumping

NASA Astrophysics Data System (ADS)

Lopaev, D. V.; Braginsky, O. V.; Klopovsky, K. S.; Kovalev, A. S.; Mankelevich, Yu. A.; Popov, N. A.; Rakhimov, A. T.; Rakhimova, T. V.; Vasilieva, A. N.

2004-09-01

The possibility of development of effective discharged singlet oxygen (SO) generator (DSOG) for oxygen-iodine laser (OIL) is studied in detail. Researches of kinetics of oxygen atoms and oxygen molecules in the lowest metastable singlet states have been carried out in the different discharges and its afterglow (DC discharges, E-beam controlled discharge and RF discharges) in both CW and pulsed mode in a wide range of conditions (pressures, gas mixtures, energy deposits etc.). The models developed for all the discharges have allowed us to analyze SO generation and loss mechanisms and to find out the key-parameters controlling the highest SO yield. It is shown that in addition to spatial plasma uniformity at low E/N and high specific energy deposit per oxygen molecule, DSOG must be oxygen atom free to avoid fast three-body quenching of SO by atomic oxygen with increasing pressure and thereby to provide pressure scaling (in tens Torrs) for applying to real OIL systems.

Working memory dynamics bias the generation of beliefs: the influence of data presentation rate on hypothesis generation.

PubMed

Lange, Nicholas D; Thomas, Rick P; Buttaccio, Daniel R; Illingworth, David A; Davelaar, Eddy J

2013-02-01

Although temporal dynamics are inherent aspects of diagnostic tasks, few studies have investigated how various aspects of time course influence hypothesis generation. An experiment is reported that demonstrates that working memory dynamics operating during serial data acquisition bias hypothesis generation. The presentation rate (and order) of a sequence of serially presented symptoms was manipulated to be either fast (180 ms per symptom) or slow (1,500 ms per symptom) in a simulated medical diagnosis task. When the presentation rate was slow, participants chose the disease hypothesis consistent with the symptoms appearing later in the sequence. When the presentation rate was fast, however, participants chose the disease hypothesis consistent with the symptoms appearing earlier in the sequence, therefore representing a novel primacy effect. We predicted and account for this effect through competitive working memory dynamics governing information acquisition and the contribution of maintained information to the retrieval of hypotheses from long-term memory.

Leak Rate Quantification Method for Gas Pressure Seals with Controlled Pressure Differential

NASA Technical Reports Server (NTRS)

Daniels, Christopher C.; Braun, Minel J.; Oravec, Heather A.; Mather, Janice L.; Taylor, Shawn C.

2015-01-01

An enhancement to the pressure decay leak rate method with mass point analysis solved deficiencies in the standard method. By adding a control system, a constant gas pressure differential across the test article was maintained. As a result, the desired pressure condition was met at the onset of the test, and the mass leak rate and measurement uncertainty were computed in real-time. The data acquisition and control system were programmed to automatically stop when specified criteria were met. Typically, the test was stopped when a specified level of measurement uncertainty was attained. Using silicone O-ring test articles, the new method was compared with the standard method that permitted the downstream pressure to be non-constant atmospheric pressure. The two methods recorded comparable leak rates, but the new method recorded leak rates with significantly lower measurement uncertainty, statistical variance, and test duration. Utilizing this new method in leak rate quantification, projects will reduce cost and schedule, improve test results, and ease interpretation between data sets.

Mobile natural gas leak surveys indicate that two utilities have high false negative rates

NASA Astrophysics Data System (ADS)

von Fischer, J. C.; Brewer, P. E.; Chamberlain, S.; Gaylord, A.; von Fischer, J.

2016-12-01

In the distribution systems that carry natural gas to consumers, leaks need to be discovered for safety reasons and to reduce greenhouse gas emissions. However, few utilities have adopted newer laser-based technologies that have greater sensitivity and precision, and instead rely on "industry standard" equipment that is far less sensitive. In partnership with the Environmental Defense Fund and Google, we mapped natural gas leaks in the domains of two anonymous utilities (Utility "A" and "B") using high sensitivity Picarro methane analyzers in Google Street View Cars. Surprisingly, when we shared these results with utilities, their survey crews were unable to find most of the leaks that our survey indicated (84% in A and 80% in B). To investigate this phenomenon, our team visited a subset of the leaks in each utility domain (n=32 in A and n=30 in B), and worked alongside utility surveyors to search the leak indication area, using a Los Gatos Research ultraportable methane analyzer to pinpoint leak locations. We found evidence of natural gas leaks at 69% and 68% of the locations in Utilities A and B respectively where survey crews had found nothing. We describe this as a "false negative" rate for the utility because the utility survey falsely indicated that there was no leak at these locations. Of these false negatives, 7% (n=2 of 32 in A, n=2 of 30 in B) were determined to be Grade 1 leaks requiring immediate repair due to high safety risk. Instrument sensitivity appears to explain some of the false negative rates. In particular, use of some industry standard equipment appears to have created a false sense of confidence among utility surveyors that leaks were not present. However, there was also evidence of communication failures and that surveyors did not use optimal approaches in their search. Based on these findings, we suggest that: 1) mobile deployment of high-precision methane analyzers can help find more natural gas leaks, and 2) use of some hand-held survey

Soap film gas flowmeter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lalin, H.S.; Bermudez, J.E.; Fleming, W.T.

1987-09-08

A soap film gas flowmeter is described comprising: a flow tube having a hollow body with opposite open ends through which a soap film is propelled and a first closed chamber housing a soap solution. It also includes means for supporting the flow tube in a substantially vertical position with the open bottom end of the flow tube disposed in the first chamber above the soap solution; a second closed chamber into which the open top end of the flow tube extends and gas inlet means for introducing gas into the first chamber at a flow rate to be measuredmore » using the flowmeters. A gas exit means is included for discharging the gas introduced into the first chamber through the second chamber. Plus there are means for generating a single soap bubble from the soap solution substantially at the bottom end of the flow tube and a relatively large opening in the flowtube for providing an open passageway for inlet gas to pass through the flowtube when the bottom open end of the flowtube is covered by the soap solution.« less

Latest generation, wide-angle, high-definition colonoscopes increase adenoma detection rate.

PubMed

Adler, Andreas; Aminalai, Alireza; Aschenbeck, Jens; Drossel, Rolf; Mayr, Michael; Scheel, Mathias; Schröder, Andreas; Yenerim, Timur; Wiedenmann, Bertram; Gauger, Ulrich; Roll, Stephanie; Rösch, Thomas

2012-02-01

Improvements to endoscopy imaging technologies might improve detection rates of colorectal cancer and patient outcomes. We compared the accuracy of the latest generation of endoscopes with older generation models in detection of colorectal adenomas. We compared data from 2 prospective screening colonoscopy studies (the Berlin Colonoscopy Project 6); each study lasted approximately 6 months and included the same 6 colonoscopists, who worked in private practice. Participants in group 1 (n = 1256) were all examined by using the latest generation of wide-angle, high-definition colonoscopes that were manufactured by the same company. Individuals in group 2 (n = 1400) were examined by endoscopists who used routine equipment (a mixture of endoscopes from different companies; none of those used to examine group 1). The adenoma detection rate was calculated on the basis of the number of all adenomas/number of all patients. There were no differences in patient parameters or withdrawal time between groups (8.0 vs 8.2 minutes). The adenoma detection rate was significantly higher in group 1 (0.33) than in group 2 (0.27; P = .01); a greater number of patients with least 1 adenoma were identified in group 1 (22.1%) than in group 2 (18.2%; P = .01). A higher percentage of high-grade dysplastic adenomas were detected in group 1 (1.19%) than in group 2 (0.57%), but this difference was not statistically significant (P = .06). The latest generation of wide-angle, high-definition colonoscopes improves rates of adenoma detection by 22%, compared with mixed, older technology endoscopes used in routine private practice. These findings might affect definitions of quality control parameters for colonoscopy screening for colorectal cancer. Copyright © 2012 AGA Institute. Published by Elsevier Inc. All rights reserved.

Field Measurements of Black Carbon Yields from Gas Flaring.

PubMed

Conrad, Bradley M; Johnson, Matthew R

2017-02-07

Black carbon (BC) emissions from gas flaring in the oil and gas industry are postulated to have critical impacts on climate and public health, but actual emission rates remain poorly characterized. This paper presents in situ field measurements of BC emission rates and flare gas volume-specific BC yields for a diverse range of flares. Measurements were performed during a series of field campaigns in Mexico and Ecuador using the sky-LOSA optical measurement technique, in concert with comprehensive Monte Carlo-based uncertainty analyses. Parallel on-site measurements of flare gas flow rate and composition were successfully performed at a subset of locations enabling direct measurements of fuel-specific BC yields from flares under field conditions. Quantified BC emission rates from individual flares spanned more than 4 orders of magnitude (up to 53.7 g/s). In addition, emissions during one notable ∼24-h flaring event (during which the plume transmissivity dropped to zero) would have been even larger than this maximum rate, which was measured as this event was ending. This highlights the likely importance of superemitters to global emission inventories. Flare gas volume-specific BC yields were shown to be strongly correlated with flare gas heating value. A newly derived correlation fitting current field data and previous lab data suggests that, in the context of recent studies investigating transport of flare-generated BC in the Arctic and globally, impacts of flaring in the energy industry may in fact be underestimated.

Impact of Gas Heating in Inductively Coupled Plasmas

NASA Technical Reports Server (NTRS)

Hash, D. B.; Bose, D.; Rao, M. V. V. S.; Cruden, B. A.; Meyyappan, M.; Sharma, S. P.; Biegel, Bryan (Technical Monitor)

2001-01-01

Recently it has been recognized that the neutral gas in inductively coupled plasma reactors heats up significantly during processing. The resulting gas density variations across the reactor affect reaction rates, radical densities, plasma characteristics, and uniformity within the reactor. A self-consistent model that couples the plasma generation and transport to the gas flow and heating has been developed and used to study CF4 discharges. A Langmuir probe has been used to measure radial profiles of electron density and temperature. The model predictions agree well with the experimental results. As a result of these comparisons along with the poorer performance of the model without the gas-plasma coupling, the importance of gas heating in plasma processing has been verified.

Flow rate and source reservoir identification from airborne chemical sampling of the uncontrolled Elgin platform gas release

NASA Astrophysics Data System (ADS)

Lee, James D.; Mobbs, Stephen D.; Wellpott, Axel; Allen, Grant; Bauguitte, Stephane J.-B.; Burton, Ralph R.; Camilli, Richard; Coe, Hugh; Fisher, Rebecca E.; France, James L.; Gallagher, Martin; Hopkins, James R.; Lanoiselle, Mathias; Lewis, Alastair C.; Lowry, David; Nisbet, Euan G.; Purvis, Ruth M.; O'Shea, Sebastian; Pyle, John A.; Ryerson, Thomas B.

2018-03-01

An uncontrolled gas leak from 25 March to 16 May 2012 led to evacuation of the Total Elgin wellhead and neighbouring drilling and production platforms in the UK North Sea. Initially the atmospheric flow rate of leaking gas and condensate was very poorly known, hampering environmental assessment and well control efforts. Six flights by the UK FAAM chemically instrumented BAe-146 research aircraft were used to quantify the flow rate. The flow rate was calculated by assuming the plume may be modelled by a Gaussian distribution with two different solution methods: Gaussian fitting in the vertical and fitting with a fully mixed layer. When both solution methods were used they compared within 6 % of each other, which was within combined errors. Data from the first flight on 30 March 2012 showed the flow rate to be 1.3 ± 0.2 kg CH4 s-1, decreasing to less than half that by the second flight on 17 April 2012. δ13CCH4 in the gas was found to be -43 ‰, implying that the gas source was unlikely to be from the main high pressure, high temperature Elgin gas field at 5.5 km depth, but more probably from the overlying Hod Formation at 4.2 km depth. This was deemed to be smaller and more manageable than the high pressure Elgin field and hence the response strategy was considerably simpler. The first flight was conducted within 5 days of the blowout and allowed a flow rate estimate within 48 h of sampling, with δ13CCH4 characterization soon thereafter, demonstrating the potential for a rapid-response capability that is widely applicable to future atmospheric emissions of environmental concern. Knowledge of the Elgin flow rate helped inform subsequent decision making. This study shows that leak assessment using appropriately designed airborne plume sampling strategies is well suited for circumstances where direct access is difficult or potentially dangerous. Measurements such as this also permit unbiased regulatory assessment of potential impact, independent of the emitting

Hydrogen-based power generation from bioethanol steam reforming

NASA Astrophysics Data System (ADS)

Tasnadi-Asztalos, Zs.; Cormos, C. C.; Agachi, P. S.

2015-12-01

This paper is evaluating two power generation concepts based on hydrogen produced from bioethanol steam reforming at industrial scale without and with carbon capture. The power generation from bioethanol conversion is based on two important steps: hydrogen production from bioethanol catalytic steam reforming and electricity generation using a hydrogen-fuelled gas turbine. As carbon capture method to be assessed in hydrogen-based power generation from bioethanol steam reforming, the gas-liquid absorption using methyl-di-ethanol-amine (MDEA) was used. Bioethanol is a renewable energy carrier mainly produced from biomass fermentation. Steam reforming of bioethanol (SRE) provides a promising method for hydrogen and power production from renewable resources. SRE is performed at high temperatures (e.g. 800-900°C) to reduce the reforming by-products (e.g. ethane, ethene). The power generation from hydrogen was done with M701G2 gas turbine (334 MW net power output). Hydrogen was obtained through catalytic steam reforming of bioethanol without and with carbon capture. For the evaluated plant concepts the following key performance indicators were assessed: fuel consumption, gross and net power outputs, net electrical efficiency, ancillary consumptions, carbon capture rate, specific CO2 emission etc. As the results show, the power generation based on bioethanol conversion has high energy efficiency and low carbon footprint.

Microfluidic study of fast gas-liquid reactions.

PubMed

Li, Wei; Liu, Kun; Simms, Ryan; Greener, Jesse; Jagadeesan, Dinesh; Pinto, Sascha; Günther, Axel; Kumacheva, Eugenia

2012-02-15

We present a new concept for studies of the kinetics of fast gas-liquid reactions. The strategy relies on the microfluidic generation of highly monodisperse gas bubbles in the liquid reaction medium and subsequent analysis of time-dependent changes in bubble dimensions. Using reactions of CO(2) with secondary amines as an exemplary system, we demonstrate that the method enables rapid determination of reaction rate constant and conversion, and comparison of various binding agents. The proposed approach addresses two challenges in studies of gas-liquid reactions: a mass-transfer limitation and a poorly defined gas-liquid interface. The proposed strategy offers new possibilities in studies of the fundamental aspects of rapid multiphase reactions, and can be combined with throughput optimization of reaction conditions.

Heat Transfer and Entropy Generation Analysis of an Intermediate Heat Exchanger in ADS

NASA Astrophysics Data System (ADS)

Wang, Yongwei; Huai, Xiulan

2018-04-01

The intermediate heat exchanger for enhancement heat transfer is the important equipment in the usage of nuclear energy. In the present work, heat transfer and entropy generation of an intermediate heat exchanger (IHX) in the accelerator driven subcritical system (ADS) are investigated experimentally. The variation of entropy generation number with performance parameters of the IHX is analyzed, and effects of inlet conditions of the IHX on entropy generation number and heat transfer are discussed. Compared with the results at two working conditions of the constant mass flow rates of liquid lead-bismuth eutectic (LBE) and helium gas, the total pumping power all tends to reduce with the decreasing entropy generation number, but the variations of the effectiveness, number of transfer units and thermal capacity rate ratio are inconsistent, and need to analyze respectively. With the increasing inlet mass flow rate or LBE inlet temperature, the entropy generation number increases and the heat transfer is enhanced, while the opposite trend occurs with the increasing helium gas inlet temperature. The further study is necessary for obtaining the optimized operation parameters of the IHX to minimize entropy generation and enhance heat transfer.

Life-cycle assessment of electricity generation systems and applications for climate change policy analysis

NASA Astrophysics Data System (ADS)

Meier, Paul Joseph

This research uses Life-Cycle Assessment (LCA) to better understand the energy and environmental performance for two electricity generation systems, a 620 MW combined-cycle natural gas plant, and an 8kW building-integrated photovoltaic system. The results of the LCA are used to provide an effective and accurate means for evaluating greenhouse gas emission reduction strategies for U.S. electricity generation. The modern combined-cycle plant considered in this thesis is nominally 48% thermally efficient, but it is only 43% energy efficient when evaluated across its entire life-cycle, due primarily to energy losses during the natural gas fuel cycle. The emission rate for the combined-cycle natural gas plant life-cycle (469 tonnes CO2-equivalent per GWeh), was 23% higher than the emission rate from plant operation alone (382 tonnes CO2-equivalent per GWeh). Uncertainty in the rate of fuel-cycle methane releases results in a potential range of emission rates between 457 to 534 tonnes CO 2-equivalent per GWeh for the studied plant. The photovoltaic system modules have a sunlight to DC electricity conversion efficiency of 5.7%. However, the system's sunlight to AC electricity conversion efficiency is 4.3%, when accounting for life-cycle energy inputs, as well as losses due to system wiring, AC inversion, and module degradation. The LCA illustrates that the PV system has a low, but not zero, life-cycle greenhouse gas emission rate of 39 Tonnes CO2-equivalent per GWeh. A ternary method of evaluation is used to evaluate three greenhouse gas mitigation alternatives: (1) fuel-switching from coal to natural gas for Kyoto-based compliance, (2) fuel-switching from coal to nuclear/renewable for Kyoto based compliance, and (3) fuel-switching to meet the White House House's Global Climate Change Initiative. In a moderate growth scenario, fuel-switching from coal to natural gas fails to meet a Kyoto-based emission target, while fuel-switching to nuclear/renewable meets the emission

Trip generation rates, peaking characteristics, and vehicle mix characteristics of special West Virginia generators : executive summary.

DOT National Transportation Integrated Search

2000-02-01

For a number of land uses, published trip rates were not appropriate for application in West Virginia. There are a number of so-called special generators, which are either unique to West Virginia (i.e., regional jails) or have assumed increased impor...

Comparing facility-level methane emission rate estimates at natural gas gathering and boosting stations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vaughn, Timothy L.; Bell, Clay S.; Yacovitch, Tara I.

Coordinated dual-tracer, aircraft-based, and direct component-level measurements were made at midstream natural gas gathering and boosting stations in the Fayetteville shale (Arkansas, USA). On-site component-level measurements were combined with engineering estimates to generate comprehensive facility-level methane emission rate estimates ('study on-site estimates (SOE)') comparable to tracer and aircraft measurements. Combustion slip (unburned fuel entrained in compressor engine exhaust), which was calculated based on 111 recent measurements of representative compressor engines, accounts for an estimated 75% of cumulative SOEs at gathering stations included in comparisons. Measured methane emissions from regenerator vents on glycol dehydrator units were substantially larger than predicted bymore » modelling software; the contribution of dehydrator regenerator vents to the cumulative SOE would increase from 1% to 10% if based on direct measurements. Concurrent measurements at 14 normally-operating facilities show relative agreement between tracer and SOE, but indicate that tracer measurements estimate lower emissions (regression of tracer to SOE = 0.91 (95% CI = 0.83-0.99), R2 = 0.89). Tracer and SOE 95% confidence intervals overlap at 11/14 facilities. Contemporaneous measurements at six facilities suggest that aircraft measurements estimate higher emissions than SOE. Aircraft and study on-site estimate 95% confidence intervals overlap at 3/6 facilities. The average facility level emission rate (FLER) estimated by tracer measurements in this study is 17-73% higher than a prior national study by Marchese et al.« less

Comparing facility-level methane emission rate estimates at natural gas gathering and boosting stations

DOE PAGES

Vaughn, Timothy L.; Bell, Clay S.; Yacovitch, Tara I.; ...

2017-02-09

Coordinated dual-tracer, aircraft-based, and direct component-level measurements were made at midstream natural gas gathering and boosting stations in the Fayetteville shale (Arkansas, USA). On-site component-level measurements were combined with engineering estimates to generate comprehensive facility-level methane emission rate estimates ('study on-site estimates (SOE)') comparable to tracer and aircraft measurements. Combustion slip (unburned fuel entrained in compressor engine exhaust), which was calculated based on 111 recent measurements of representative compressor engines, accounts for an estimated 75% of cumulative SOEs at gathering stations included in comparisons. Measured methane emissions from regenerator vents on glycol dehydrator units were substantially larger than predicted bymore » modelling software; the contribution of dehydrator regenerator vents to the cumulative SOE would increase from 1% to 10% if based on direct measurements. Concurrent measurements at 14 normally-operating facilities show relative agreement between tracer and SOE, but indicate that tracer measurements estimate lower emissions (regression of tracer to SOE = 0.91 (95% CI = 0.83-0.99), R2 = 0.89). Tracer and SOE 95% confidence intervals overlap at 11/14 facilities. Contemporaneous measurements at six facilities suggest that aircraft measurements estimate higher emissions than SOE. Aircraft and study on-site estimate 95% confidence intervals overlap at 3/6 facilities. The average facility level emission rate (FLER) estimated by tracer measurements in this study is 17-73% higher than a prior national study by Marchese et al.« less

Development of a primary diffusion source of organic vapors for gas analyzer calibration

NASA Astrophysics Data System (ADS)

Lecuna, M.; Demichelis, A.; Sassi, G.; Sassi, M. P.

2018-03-01

The generation of reference mixtures of volatile organic compounds (VOCs) at trace levels (10 ppt-10 ppb) is a challenge for both environmental and clinical measurements. The calibration of gas analyzers for trace VOC measurements requires a stable and accurate source of the compound of interest. The dynamic preparation of gas mixtures by diffusion is a suitable method for fulfilling these requirements. The estimation of the uncertainty of the molar fraction of the VOC in the mixture is a key step in the metrological characterization of a dynamic generator. The performance of a dynamic generator was monitored over a wide range of operating conditions. The generation system was simulated by a model developed with computational fluid dynamics and validated against experimental data. The vapor pressure of the VOC was found to be one of the main contributors to the uncertainty of the diffusion rate and its influence at 10-70 kPa was analyzed and discussed. The air buoyancy effect and perturbations due to the weighing duration were studied. The gas carrier flow rate and the amount of liquid in the vial were found to play a role in limiting the diffusion rate. The results of sensitivity analyses were reported through an uncertainty budget for the diffusion rate. The roles of each influence quantity were discussed. A set of criteria to minimize the uncertainty contribution to the primary diffusion source (25 µg min-1) were estimated: carrier gas flow rate higher than 37.7 sml min-1, a maximum VOC liquid mass decrease in the vial of 4.8 g, a minimum residual mass of 1 g and vial weighing times of 1-3 min. With this procedure a limit uncertainty of 0.5% in the diffusion rate can be obtained for VOC mixtures at trace levels (10 ppt-10 ppb), making the developed diffusion vials a primary diffusion source with potential to become a new reference material for trace VOC analysis.

Gas bubble formation in fused silica generated by ultra-short laser pulses.

PubMed

Cvecek, Kristian; Miyamoto, Isamu; Schmidt, Michael

2014-06-30

During processing of glass using ultra-fast lasers the formation of bubble-like structures can be observed in several glass types such as fused silica. Their formation can be exploited to generate periodic gratings in glasses but for other glass processing techniques such as waveguide-writing or glass welding by ultra-fast lasers the bubble formation proves often detrimental. In this work we present experiments and their results in order to gain understanding of the origins and on the underlying formation and transportation mechanisms of the gas bubbles.

Nitrogen Gas Plasma Generated by a Static Induction Thyristor as a Pulsed Power Supply Inactivates Adenovirus

PubMed Central

Sakudo, Akikazu; Toyokawa, Yoichi; Imanishi, Yuichiro

2016-01-01

Adenovirus is one of the most important causative agents of iatrogenic infections derived from contaminated medical devices or finger contact. In this study, we investigated whether nitrogen gas plasma, generated by applying a short high-voltage pulse to nitrogen using a static induction thyristor power supply (1.5 kilo pulse per second), exhibited a virucidal effect against adenoviruses. Viral titer was reduced by one log within 0.94 min. Results from detection of viral capsid proteins, hexon and penton, by Western blotting and immunochromatography were unaffected by the plasma treatment. In contrast, analysis using the polymerase chain reaction suggested that plasma treatment damages the viral genomic DNA. Reactive chemical products (hydrogen peroxide, nitrate, and nitrite), ultraviolet light (UV-A) and slight temperature elevations were observed during the operation of the gas plasma device. Viral titer versus intensity of each potential virucidal factor were used to identify the primary mechanism of disinfection of adenovirus. Although exposure to equivalent levels of UV-A or heat treatment did not inactivate adenovirus, treatment with a relatively low concentration of hydrogen peroxide efficiently inactivated the virus. Our results suggest the nitrogen gas plasma generates reactive chemical products that inactivate adenovirus by damaging the viral genomic DNA. PMID:27322066

Assessing the containment efficiency of a microbiological safety cabinet during the simultaneous generation of a nanoaerosol and a tracer gas.

PubMed

Cesard, V; Belut, E; Prevost, C; Taniere, A; Rimbert, N

2013-04-01

The intention of this article is to compare the containment performance of a Type II microbiological safety cabinet (MSC) confronted with the simultaneous generation of a saline nanoparticle aerosol and a tracer gas (SF(6)). The back dissemination coefficient, defined as the ratio of the pollutant concentration measured outside the enclosure to the pollutant flow rate emitted inside the enclosure, is calculated in order to quantify the level of protection of each airborne contaminant tested for three enclosure operating configurations: an initial configuration (without perturbations), a configuration exposing a dummy in front of the enclosure (simulation of an operator), and a configuration employing the movement of a plate in front of the enclosure (simulation of human movement). Based on the results of this study, we observed that nanoparticulate and gaseous behaviours are strongly correlated, thus showing the predominance of air-driven transport over particle-specific behaviour. The average level of protection afforded by the MSC was found systematically slightly higher for the nanoaerosol than for the gas in the studied configurations (emission properties of the source, operating conditions, and measurement protocols). This improved protection efficiency, however, cannot be considered as a warrant of protection for operators since operating condition and ventilation parameters are still more influential on the containment than the pollutant nature (i.e. nanoaerosol or gas).

The hyperoxic switch: assessing respiratory water loss rates in tracheate arthropods with continuous gas exchange.

PubMed

Lighton, John R B; Schilman, Pablo E; Holway, David A

2004-12-01

Partitioning the relative contributions of cuticular and respiratory water loss in a tracheate arthropod is relatively easy if it undergoes discontinuous gas exchange cycles or DGCs, leaving its rate of cuticular water loss in primary evidence while its spiracles are closed. Many arthropods are not so obliging and emit CO(2) continuously, making cuticular and respiratory water losses difficult or impossible to partition. We report here that by switching ambient air from 21 to 100% O(2), marked spiracular constriction takes place, causing a transient but substantial - up to 90% - reduction in CO(2) output. A reduction in water loss rate occurs at the same time. Using this approach, we investigated respiratory water loss in Drosophila melanogaster and in two ant species, Forelius mccooki and Pogonomyrmex californicus. Our results - respiratory water loss estimates of 23%, 7.6% and 5.6% of total water loss rates, respectively - are reasonable in light of literature estimates, and suggest that the 'hyperoxic switch' may allow straightforward estimation of respiratory water loss rates in arthropods lacking discontinuous gas exchange. In P. californicus, which we were able to measure with and without a DGC, presence or absence of a DGC did not affect respiratory vs total water loss rates.