A new method for calculation of water saturation in shale gas reservoirs using V P -to-V S ratio and porosity

NASA Astrophysics Data System (ADS)

Liu, Kun; Sun, Jianmeng; Zhang, Hongpan; Liu, Haitao; Chen, Xiangyang

2018-02-01

Total water saturation is an important parameter for calculating the free gas content of shale gas reservoirs. Owing to the limitations of the Archie formula and its extended solutions in zones rich in organic or conductive minerals, a new method was proposed to estimate total water saturation according to the relationship between total water saturation, V P -to-V S ratio and total porosity. Firstly, the ranges of the relevant parameters in the viscoelastic BISQ model in shale gas reservoirs were estimated. Then, the effects of relevant parameters on the V P -to-V S ratio were simulated based on the partially saturated viscoelastic BISQ model. These parameters were total water saturation, total porosity, permeability, characteristic squirt-flow length, fluid viscosity and sonic frequency. The simulation results showed that the main factors influencing V P -to-V S ratio were total porosity and total water saturation. When the permeability and the characteristic squirt-flow length changed slightly for a particular shale gas reservoir, their influences could be neglected. Then an empirical equation for total water saturation with respect to total porosity and V P -to-V S ratio was obtained according to the experimental data. Finally, the new method was successfully applied to estimate total water saturation in a sequence formation of shale gas reservoirs. Practical applications have shown good agreement with the results calculated by the Archie model.

Experimental constraints on the outgassing dynamics of basaltic magmas

NASA Astrophysics Data System (ADS)

Pioli, L.; Bonadonna, C.; Azzopardi, B. J.; Phillips, J. C.; Ripepe, M.

2012-03-01

The dynamics of separated two-phase flow of basaltic magmas in cylindrical conduits has been explored combining large-scale experiments and theoretical studies. Experiments consisted of the continuous injection of air into water or glucose syrup in a 0.24 m diameter, 6.5 m long bubble column. The model calculates vesicularity and pressure gradient for a range of gas superficial velocities (volume flow rates/pipe area, 10-2-102 m/s), conduit diameters (100-2 m), and magma viscosities (3-300 Pa s). The model is calibrated with the experimental results to extrapolate key flow parameters such as Co (distribution parameter) and Froude number, which control the maximum vesicularity of the magma in the column, and the gas rise speed of gas slugs. It predicts that magma vesicularity increases with increasing gas volume flow rate and decreases with increasing conduit diameter, until a threshold value (45 vol.%), which characterizes churn and annular flow regimes. Transition to annular flow regimes is expected to occur at minimum gas volume flow rates of 103-104 m3/s. The vertical pressure gradient decreases with increasing gas flow rates and is controlled by magma vesicularity (in bubbly flows) or the length and spacing of gas slugs. This study also shows that until conditions for separated flow are met, increases in magma viscosity favor stability of slug flow over bubbly flow but suggests coexistence between gas slugs and small bubbles, which contribute to a small fraction of the total gas outflux. Gas flow promotes effective convection of the liquid, favoring magma homogeneity and stable conditions.

Computer Programs for Calculating the Isentropic Flow Properties for Mixtures of R-134a and Air

NASA Technical Reports Server (NTRS)

Kvaternik, Raymond G.

2000-01-01

Three computer programs for calculating the isentropic flow properties of R-134a/air mixtures which were developed in support of the heavy gas conversion of the Langley Transonic Dynamics Tunnel (TDT) from dichlorodifluoromethane (R-12) to 1,1,1,2 tetrafluoroethane (R-134a) are described. The first program calculates the Mach number and the corresponding flow properties when the total temperature, total pressure, static pressure, and mole fraction of R-134a in the mixture are given. The second program calculates tables of isentropic flow properties for a specified set of free-stream Mach numbers given the total pressure, total temperature, and mole fraction of R-134a. Real-gas effects are accounted for in these programs by treating the gases comprising the mixture as both thermally and calorically imperfect. The third program is a specialized version of the first program in which the gases are thermally perfect. It was written to provide a simpler computational alternative to the first program in those cases where real-gas effects are not important. The theory and computational procedures underlying the programs are summarized, the equations used to compute the flow quantities of interest are given, and sample calculated results that encompass the operating conditions of the TDT are shown.

An experimental trace gas investigation of fluid transport and mixing in a circular-to-rectangular transition duct

NASA Technical Reports Server (NTRS)

Reichert, B. A.; Hingst, W. R.; Okiishi, T. H.

1991-01-01

An ethylene trace gas technique was used to map out fluid transport and mixing within a circular to rectangular transition duct. Ethylene gas was injected at several points in a cross stream plane upstream of the transition duct. Ethylene concentration contours were determined at several cross stream measurement planes spaced axially within the duct. The flow involved a uniform inlet flow at a Mach number level of 0.5. Statistical analyses were used to quantitatively interpret the trace gas results. Also, trace gas data were considered along with aerodynamic and surface flow visualization results to ascertain transition duct flow phenomena. Convection of wall boundary layer fluid by vortices produced regions of high total pressure loss in the duct. The physical extent of these high loss regions is governed by turbulent diffusion.

Pulsatile Flow Across a Cylinder--An Investigation of Flow in a Total Artificial Lung

NASA Astrophysics Data System (ADS)

Lin, Yu-Chun

2005-11-01

The effect of pulsatility on flow across a single cylinder has been examined experimentally using particle image velocimetry. This work is motivated by the ongoing development of a total artificial lung (TAL), a device which would serve as a bridge to lung transplant. The prototype TAL consists of hollow microfibers through which oxygen-rich gas flows and blood flows around. Flow through the device is provided entirely by right heart and, therefore, is puslatile. The Peclet number of the flow is large and consequently the development of secondary flow affects the resulting gas exchange. The effects of frequency and average flow rate of pulsatile flow around a cylinder were investigated experimentally in a water tunnel and some of the results were compared with preliminary numerical results. Vortices developed behind the cylinder at lower Reynolds numbers in pulsatile flow than steady flow. The results indicate that there are critical values of the Reynolds number between 3 to 5 and Stokes numbers of 0.22, below which vortices were not observed. The findings suggest that higher Stokes and Reynolds numbers within the device could enhance vortex formation. However, this enhanced gas exchange could be at the expense of higher device resistance and increased likelihood of blood trauma. Intelligent TAL design will require consideration of these effects. This work is supported by NIH grant HL69420.

On factors influencing air-water gas exchange in emergent wetlands

USGS Publications Warehouse

Ho, David T.; Engel, Victor C.; Ferron, Sara; Hickman, Benjamin; Choi, Jay; Harvey, Judson W.

2018-01-01

Knowledge of gas exchange in wetlands is important in order to determine fluxes of climatically and biogeochemically important trace gases and to conduct mass balances for metabolism studies. Very few studies have been conducted to quantify gas transfer velocities in wetlands, and many wind speed/gas exchange parameterizations used in oceanographic or limnological settings are inappropriate under conditions found in wetlands. Here six measurements of gas transfer velocities are made with SF6 tracer release experiments in three different years in the Everglades, a subtropical peatland with surface water flowing through emergent vegetation. The experiments were conducted under different flow conditions and with different amounts of emergent vegetation to determine the influence of wind, rain, water flow, waterside thermal convection, and vegetation on air-water gas exchange in wetlands. Measured gas transfer velocities under the different conditions ranged from 1.1 cm h−1 during baseline conditions to 3.2 cm h−1 when rain and water flow rates were high. Commonly used wind speed/gas exchange relationships would overestimate the gas transfer velocity by a factor of 1.2 to 6.8. Gas exchange due to thermal convection was relatively constant and accounted for 14 to 51% of the total measured gas exchange. Differences in rain and water flow among the different years were responsible for the variability in gas exchange, with flow accounting for 37 to 77% of the gas exchange, and rain responsible for up to 40%.

40 CFR 98.364 - Monitoring and QA/QC requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... or operator shall document the procedures used to ensure the accuracy of gas flow rate, gas... (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Manure Management § 98.364 Monitoring and QA/QC requirements... fraction of total manure managed in each system component. (c) The CH4 concentration of gas from digesters...

40 CFR 98.364 - Monitoring and QA/QC requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... or operator shall document the procedures used to ensure the accuracy of gas flow rate, gas... (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Manure Management § 98.364 Monitoring and QA/QC requirements... fraction of total manure managed in each system component. (c) The CH4 concentration of gas from digesters...

40 CFR 98.364 - Monitoring and QA/QC requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... or operator shall document the procedures used to ensure the accuracy of gas flow rate, gas... (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Manure Management § 98.364 Monitoring and QA/QC requirements... fraction of total manure managed in each system component. (c) The CH4 concentration of gas from digesters...

40 CFR 63.4168 - What are the requirements for continuous parameter monitoring system installation, operation, and...

Code of Federal Regulations, 2014 CFR

2014-07-01

... add-on control device, you must monitor the total regeneration desorbing gas (e.g., steam or nitrogen) mass flow for each regeneration cycle, the carbon bed temperature after each regeneration and cooling... regeneration desorbing gas mass flow monitor must be an integrating device having a measurement sensitivity of...

40 CFR 63.3557 - What are the requirements for continuous parameter monitoring system installation, operation, and...

Code of Federal Regulations, 2013 CFR

2013-07-01

... monitor the total regeneration desorbing gas (e.g., steam or nitrogen) mass flow for each regeneration cycle, the carbon bed temperature after each regeneration and cooling cycle, and comply with paragraphs (a)(3) through (5) and (d)(1) and (2) of this section. (1) The regeneration desorbing gas mass flow...

40 CFR 63.3557 - What are the requirements for continuous parameter monitoring system installation, operation, and...

Code of Federal Regulations, 2014 CFR

2014-07-01

... monitor the total regeneration desorbing gas (e.g., steam or nitrogen) mass flow for each regeneration cycle, the carbon bed temperature after each regeneration and cooling cycle, and comply with paragraphs (a)(3) through (5) and (d)(1) and (2) of this section. (1) The regeneration desorbing gas mass flow...

40 CFR 63.3557 - What are the requirements for continuous parameter monitoring system installation, operation, and...

Code of Federal Regulations, 2012 CFR

2012-07-01

... monitor the total regeneration desorbing gas (e.g., steam or nitrogen) mass flow for each regeneration cycle, the carbon bed temperature after each regeneration and cooling cycle, and comply with paragraphs (a)(3) through (5) and (d)(1) and (2) of this section. (1) The regeneration desorbing gas mass flow...

Oscillating side-branch enhancements of thermoacoustic heat exchangers

DOEpatents

Swift, Gregory W.

2003-05-13

A regenerator-based engine or refrigerator has a regenerator with two ends at two different temperatures, through which a gas oscillates at a first oscillating volumetric flow rate in the direction between the two ends and in which the pressure of the gas oscillates, and first and second heat exchangers, each of which is at one of the two different temperatures. A dead-end side branch into which the gas oscillates has compliance and is connected adjacent to one of the ends of the regenerator to form a second oscillating gas flow rate additive with the first oscillating volumetric flow rate, the compliance having a volume effective to provide a selected total oscillating gas volumetric flow rate through the first heat exchanger. This configuration enables the first heat exchanger to be configured and located to better enhance the performance of the heat exchanger rather than being confined to the location and configuration of the regenerator.

Design of Compressed Sensing Algorithm for Coal Mine IoT Moving Measurement Data Based on a Multi-Hop Network and Total Variation.

PubMed

Wang, Gang; Zhao, Zhikai; Ning, Yongjie

2018-05-28

As the application of a coal mine Internet of Things (IoT), mobile measurement devices, such as intelligent mine lamps, cause moving measurement data to be increased. How to transmit these large amounts of mobile measurement data effectively has become an urgent problem. This paper presents a compressed sensing algorithm for the large amount of coal mine IoT moving measurement data based on a multi-hop network and total variation. By taking gas data in mobile measurement data as an example, two network models for the transmission of gas data flow, namely single-hop and multi-hop transmission modes, are investigated in depth, and a gas data compressed sensing collection model is built based on a multi-hop network. To utilize the sparse characteristics of gas data, the concept of total variation is introduced and a high-efficiency gas data compression and reconstruction method based on Total Variation Sparsity based on Multi-Hop (TVS-MH) is proposed. According to the simulation results, by using the proposed method, the moving measurement data flow from an underground distributed mobile network can be acquired and transmitted efficiently.

Stripped interstellar gas in cluster cooling flows

NASA Technical Reports Server (NTRS)

Soker, Noam; Bregman, Joel N.; Sarazin, Craig L.

1991-01-01

It is suggested that nonlinear perturbations which lead to thermal instabilities in cooling flows might start as blobs of interstellar gas which are stipped out of cluster galaxies. Assuming that most of the gas produced by stellar mass loss in cluster galaxies is stripped from the galaxies, the total rate of such stripping is roughly 100 solar masses/yr, which is similar to the rates of cooling in cluster cooling flows. It is possible that a substantial portion of the cooling gas originates as blobs of interstellar gas stripped from galaxies. The magnetic fields within and outside of the low-entropy perturbations may help to maintain their identities by suppressing both thermal conduction and Kelvin-Helmholtz instabilities. These density fluctuations may disrupt the propagation of radio jets through the intracluster gas, which may be one mechanism for producing wideangle-tail radio galaxies.

Achieving high time-resolution with a new flow-through type analyzer for total inorganic carbon in seawater.

PubMed

Kimoto, Hideshi; Nozaki, Ken; Kudo, Setsuko; Kato, Ken; Negishi, Akira; Kayanne, Hajime

2002-03-01

A fully automated, continuous-flow-through type analyzer was developed to observe rapid changes in the concentration of total inorganic carbon (CT) in coastal zones. Seawater and an H3PO4 solution were fed into the analyzer's mixing coil by two high-precision valveless piston pumps. The CO2 was stripped from the seawater and moved into a carrier gas, using a newly developed continuous-flow-through CO2 extractor. A mass flow controller was used to assure a precise flow rate of the carrier gas. The CO2 concentration was then determined with a nondispersive infrared gas analyzer. This analyzer achieved a time-resolution of as good as 1 min. In field experiments on a shallow reef flat of Shiraho (Ishigaki Island, Southwest Japan), the analyzer detected short-term, yet extreme, variations in CT which manual sampling missed. Analytical values obtained by the analyzer on the boat were compared with those determined by potentiometric titration with a closed cell in a laboratory: CT(flow-through) = 0.980 x CT(titration) + 38.8 with r2 = 0.995 (n = 34; September 1998).

A "Greenhouse Gas" Experiment for the Undergraduate Laboratory

ERIC Educational Resources Information Center

Gomez, Elaine; Paul, Melissa; Como, Charles; Barat, Robert

2014-01-01

This experiment and analysis offer an effective experience in greenhouse gas reduction. Ammoniated water is flowed counter-current to a simulated flue gas of air and CO2 in a packed column. The gaseous CO2 concentrations are measured with an on-line, non- dispersive, infrared analyzer. Column operating parameters include total gas flux, dissolved…

40 CFR 63.3547 - What are the requirements for continuous parameter monitoring system installation, operation, and...

Code of Federal Regulations, 2012 CFR

2012-07-01

... adsorber as an add-on control device, you must monitor the total regeneration desorbing gas (e.g., steam or nitrogen) mass flow for each regeneration cycle, the carbon bed temperature after each regeneration and... regeneration desorbing gas mass flow monitor must be an integrating device having an accuracy of ±10 percent...

40 CFR 63.3547 - What are the requirements for continuous parameter monitoring system installation, operation, and...

Code of Federal Regulations, 2013 CFR

2013-07-01

... adsorber as an add-on control device, you must monitor the total regeneration desorbing gas (e.g., steam or nitrogen) mass flow for each regeneration cycle, the carbon bed temperature after each regeneration and... regeneration desorbing gas mass flow monitor must be an integrating device having an accuracy of ±10 percent...

40 CFR 63.3547 - What are the requirements for continuous parameter monitoring system installation, operation, and...

Code of Federal Regulations, 2014 CFR

2014-07-01

... adsorber as an add-on control device, you must monitor the total regeneration desorbing gas (e.g., steam or nitrogen) mass flow for each regeneration cycle, the carbon bed temperature after each regeneration and... regeneration desorbing gas mass flow monitor must be an integrating device having an accuracy of ±10 percent...

The ejector flowmeter as air/oxygen mixing device. An apparatus providing gas mixtures with adjustable oxygen content for high-flow humidification systems.

PubMed

Christensen, K N; Waaben, J; Jørgensen, S

1980-04-01

The ejector flowmeter is constructed for continuous removal of excess gas from anaesthetic circuits. This instrument can be used as an air/oxygen mixing device for high-flow humidification systems in wards where compressed air is not available. Pure oxygen is used as driving gas through the ejector. A nomogram has been constructed to show the relationship between oxygen driving pressure, inlet of air to the flowmeter, FIO2 and total outflow.

Numerical Simulations of Inclusion Behavior in Gas-Stirred Ladles

NASA Astrophysics Data System (ADS)

Lou, Wentao; Zhu, Miaoyong

2013-06-01

A computation fluid dynamics-population balance model (CFD-PBM) coupled model has been proposed to investigate the bubbly plume flow and inclusion behavior including growth, size distribution, and removal in gas-stirred ladles, and some new and important phenomena and mechanisms were presented. For the bubbly plume flow, a modified k- ɛ model with extra source terms to account for the bubble-induced turbulence was adopted to model the turbulence, and the bubble turbulent dispersion force was taken into account to predict gas volume fraction distribution in the turbulent gas-stirred system. For inclusion behavior, the phenomena of inclusions turbulent random motion, bubbles wake, and slag eye forming on the molten steel surface were considered. In addition, the multiple mechanisms both that promote inclusion growth due to inclusion-inclusion collision caused by turbulent random motion, shear rate in turbulent eddy, and difference inclusion Stokes velocities, and the mechanisms that promote inclusion removal due to bubble-inclusion turbulence random collision, bubble-inclusion turbulent shear collision, bubble-inclusion buoyancy collision, inclusion own floatation near slag-metal interface, bubble wake capture, and wall adhesion were investigated. The importance of different mechanisms and total inclusion removal ratio under different conditions, and the distribution of inclusion number densities in ladle, were discussed and clarified. The results show that at a low gas flow rate, the inclusion growth is mainly attributed to both turbulent shear collision and Stokes collision, which is notably affected by the Stokes collision efficiency, and the inclusion removal is mainly attributed to the bubble-inclusion buoyancy collision and inclusion own floatation near slag-metal interface. At a higher gas flow rate, the inclusions appear as turbulence random motion in bubbly plume zone, and both the inclusion-inclusion and inclusion-bubble turbulent random collisions become important for inclusion growth and removal. With the increase of the gas flow rate, the total removal ratio increases, but when the gas flow rate exceeds 200 NL/min in 150-ton ladle, the total removal ration almost does not change. For the larger size inclusions, the number density in bubbly plume zone is less than that in the sidewall recirculation zones, but for the small size inclusions, the distribution of number density shows the opposite trend.

A Systematic Procedure to Describe Shale Gas Permeability Evolution during the Production Process

NASA Astrophysics Data System (ADS)

Jia, B.; Tsau, J. S.; Barati, R.

2017-12-01

Gas flow behavior in shales is complex due to the multi-physics nature of the process. Pore size reduces as the in-situ stress increases during the production process, which will reduce intrinsic permeability of the porous media. Slip flow/pore diffusion enhances gas apparent permeability, especially under low reservoir pressures. Adsorption not only increases original gas in place but also influences gas flow behavior because of the adsorption layer. Surface diffusion between free gas and adsorption phase enhances gas permeability. Pore size reduction and the adsorption layer both have complex impacts on gas apparent permeability and non-Darcy flow might be a major component in nanopores. Previously published literature is generally incomplete in terms of coupling of all these four physics with fluid flow during gas production. This work proposes a methodology to simultaneously take them into account to describe a permeability evolution process. Our results show that to fully describe shale gas permeability evolution during gas production, three sets of experimental data are needed initially: 1) intrinsic permeability under different in-situ stress, 2) adsorption isotherm under reservoir conditions and 3) surface diffusivity measurement by the pulse-decay method. Geomechanical effects, slip flow/pore diffusion, adsorption layer and surface diffusion all play roles affecting gas permeability. Neglecting any of them might lead to misleading results. The increasing in-situ stress during shale gas production is unfavorable to shale gas flow process. Slip flow/pore diffusion is important for gas permeability under low pressures in the tight porous media. They might overwhelm the geomechanical effect and enhance gas permeability at low pressures. Adsorption layer reduces the gas permeability by reducing the effective pore size, but the effect is limited. Surface diffusion increases gas permeability more under lower pressures. The total gas apparent permeability might keep increasing during the gas production process when the surface diffusivity is larger than a critical value. We believe that our workflow proposed in this study will help describe shale gas permeability evolution considering all the underlying physics altogether.

Gas-Recovery System

DOEpatents

Heckman, R. A.

1971-12-14

Nuclear explosions have been proposed as a means for recovering gas from underground gas-bearing rock formations. In present practice, the nuclear device is positioned at the end of a long pipe which is subsequently filled with grout or concrete. After the device is exploded, the grout is drilled through to provide a flow path for the released gas to the ground surface. As settled grout is brittle, often the compressive shock of the explosion fractures the grout and deforms the pipe so that it may not be removed nor reused. In addition, the pipe is sometimes pinched off completely and the gas flow is totally obstructed. (2 claims)

Gas-recovery system

DOEpatents

Heckman, R.A.

1971-12-14

Nuclear explosions have been proposed as a means for recovering gas from underground gas-bearing rock formations. In present practice, the nuclear device is positioned at the end of a long pipe which is subsequently filled with grout or concrete. After the device is exploded, the grout is drilled through to provide a flow path for the released gas to the ground surface. As settled grout is brittle, often the compressive shock of the explosion fractures the grout and deforms the pipe so that it may not be removed nor reused. In addition, the pipe is sometimes pinched off completely and the gas flow is totally obstructed. (2 claims)

Assessment of porous material anisotropy and its effect on gas permeability

NASA Astrophysics Data System (ADS)

Wałowski, Grzegorz

2017-10-01

The results of experimental research upon the assessment of porous material anisotropy and its effect on gas permeability of porous materials with respect to the gas flow. The conducted research applied to natural materials with an anisotropic gap-porous structure and - for comparative purposes - to model materials such as coke, pumice and polyamide agglomerates. The research was conducted with the use of a special test stand that enables measuring the gas permeability with respect to three flow orientations compared with symmetric cubic-shaped samples. The research results show an explicit impact of the flow direction on the permeability of materials porous, which results from their anisotropic internal structures. The anisotropy coefficient and permeability effective coefficient of such materials was determined and an experimental evaluation of the value of this coefficient was conducted with respect to the gas stream and the total pressure drop across the porous deposit. The process of gas permeability was considered in the category of hydrodynamics of gas flow through porous deposits. It is important to broaden the knowledge of gas hydrodynamics assessment in porous media so far unrecognised for the development of a new generation of clean energy sources, especially in the context of biogas or raw gas production.

CFD simulation of gas and non-Newtonian fluid two-phase flow in anaerobic digesters.

PubMed

Wu, Binxin

2010-07-01

This paper presents an Eulerian multiphase flow model that characterizes gas mixing in anaerobic digesters. In the model development, liquid manure is assumed to be water or a non-Newtonian fluid that is dependent on total solids (TS) concentration. To establish the appropriate models for different TS levels, twelve turbulence models are evaluated by comparing the frictional pressure drops of gas and non-Newtonian fluid two-phase flow in a horizontal pipe obtained from computational fluid dynamics (CFD) with those from a correlation analysis. The commercial CFD software, Fluent12.0, is employed to simulate the multiphase flow in the digesters. The simulation results in a small-sized digester are validated against the experimental data from literature. Comparison of two gas mixing designs in a medium-sized digester demonstrates that mixing intensity is insensitive to the TS in confined gas mixing, whereas there are significant decreases with increases of TS in unconfined gas mixing. Moreover, comparison of three mixing methods indicates that gas mixing is more efficient than mixing by pumped circulation while it is less efficient than mechanical mixing.

Characterization of Nanoscale Gas Transport in Shale Formations

NASA Astrophysics Data System (ADS)

Chai, D.; Li, X.

2017-12-01

Non-Darcy flow behavior can be commonly observed in nano-sized pores of matrix. Most existing gas flow models characterize non-Darcy flow by empirical or semi-empirical methods without considering the real gas effect. In this paper, a novel layered model with physical meanings is proposed for both ideal and real gas transports in nanopores. It can be further coupled with hydraulic fracturing models and consequently benefit the storage evaluation and production prediction for shale gas recovery. It is hypothesized that a nanotube can be divided into a central circular zone where the viscous flow behavior mainly exists due to dominant intermolecular collisions and an outer annular zone where the Knudsen diffusion mainly exists because of dominant collisions between molecules and the wall. The flux is derived based on integration of two zones by applying the virtual boundary. Subsequently, the model is modified by incorporating slip effect, real gas effect, porosity distribution, and tortuosity. Meanwhile, a multi-objective optimization method (MOP) is applied to assist the validation of analytical model to search fitting parameters which are highly localized and contain significant uncertainties. The apparent permeability is finally derived and analyzed with various impact factors. The developed nanoscale gas transport model is well validated by the flux data collected from both laboratory experiments and molecular simulations over the entire spectrum of flow regimes. It has a decrease of as much as 43.8% in total molar flux when the real gas effect is considered in the model. Such an effect is found to be more significant as pore size shrinks. Knudsen diffusion accounts for more than 60% of the total gas flux when pressure is lower than 0.2 MPa and pore size is smaller than 50 nm. Overall, the apparent permeability is found to decrease with pressure, though it rarely changes when pressure is higher than 5.0 MPa and pore size is larger than 50 nm.

40 CFR 86.210-08 - Exhaust gas sampling system; Diesel-cycle vehicles not requiring particulate emissions measurements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... detector (HFID) (375 °±20 °F (191 °±11 °C)) sample for total hydrocarbon (THC) analysis. The HFID sample... integrated measurement of diluted THC is required. Unless compensation for varying mass flow is made, a constant mass flow system must be used to ensure a proportional THC measurement. (2) For natural gas-fueled...

40 CFR 86.210-08 - Exhaust gas sampling system; Diesel-cycle vehicles not requiring particulate emissions measurements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... detector (HFID) (375 °±20 °F (191 °±11 °C)) sample for total hydrocarbon (THC) analysis. The HFID sample... integrated measurement of diluted THC is required. Unless compensation for varying mass flow is made, a constant mass flow system must be used to ensure a proportional THC measurement. (2) For natural gas-fueled...

Analysis and comparison of wall cooling schemes for advanced gas turbine applications

NASA Technical Reports Server (NTRS)

Colladay, R. S.

1972-01-01

The relative performance of (1) counterflow film cooling, (2) parallel-flow film cooling, (3) convection cooling, (4) adiabatic film cooling, (5) transpiration cooling, and (6) full-coverage film cooling was investigated for heat loading conditions expected in future gas turbine engines. Assumed in the analysis were hot-gas conditions of 2200 K (3500 F) recovery temperature, 5 to 40 atmospheres total pressure, and 0.6 gas Mach number and a cooling air supply temperature of 811 K (1000 F). The first three cooling methods involve film cooling from slots. Counterflow and parallel flow describe the direction of convection cooling air along the inside surface of the wall relative to the main gas flow direction. The importance of utilizing the heat sink available in the coolant for convection cooling prior to film injection is illustrated.

Multi-phase-fluid discrimination with local fibre-optical probes: III. Three-phase flows

NASA Astrophysics Data System (ADS)

Fordham, E. J.; Ramos, R. T.; Holmes, A.; Simonian, S.; Huang, S.-M.; Lenn, C. P.

1999-12-01

Local fibre-optical sensors (or `local probes') for immiscible-fluid discrimination are demonstrated in three-phase (oil/water/gas) flows. The probes are made from standard silica fibres with plane oblique facets polished at the fibre tip, with surface treatment for wettability control. They use total internal reflection to distinguish among drops, bubbles and other regions of fluid in multi-phase flows, on the basis of refractive-index contrast. Dual probes, using two sensors each with a quasi-binary output, are used to determine profiles of three-phase volume fraction in a flow of kerosene, water and air in a pipe. The individual sensors used discriminate oil from `not-oil' and gas from liquid; their logical combination discriminates among the three phases. Companion papers deal with the sensor designs used and quantitative results achieved in the simpler two-phase cases of liquid/liquid flows and gas/liquid flows.

Microtube strip heat exchanger

NASA Astrophysics Data System (ADS)

Doty, F. D.

1991-10-01

This progress report is for the September-October 1991 quarter. We have demonstrated feasibility of higher specific conductance by a factor of five than any other work in high-temperature gas-to-gas exchangers. These laminar-flow, microtube exchangers exhibit extremely low pressure drop compared to alternative compact designs under similar conditions because of their much shorter flow length and larger total flow area for lower flow velocities. The design appears to be amenable to mass production techniques, but considerable process development remains. The reduction in materials usage and the improved heat exchanger performance promise to be of enormous significance in advanced engine designs and in cryogenics.

Inert gas clearance from tissue by co-currently and counter-currently arranged microvessels

PubMed Central

Lu, Y.; Michel, C. C.

2012-01-01

To elucidate the clearance of dissolved inert gas from tissues, we have developed numerical models of gas transport in a cylindrical block of tissue supplied by one or two capillaries. With two capillaries, attention is given to the effects of co-current and counter-current flow on tissue gas clearance. Clearance by counter-current flow is compared with clearance by a single capillary or by two co-currently arranged capillaries. Effects of the blood velocity, solubility, and diffusivity of the gas in the tissue are investigated using parameters with physiological values. It is found that under the conditions investigated, almost identical clearances are achieved by a single capillary as by a co-current pair when the total flow per tissue volume in each unit is the same (i.e., flow velocity in the single capillary is twice that in each co-current vessel). For both co-current and counter-current arrangements, approximate linear relations exist between the tissue gas clearance rate and tissue blood perfusion rate. However, the counter-current arrangement of capillaries results in less-efficient clearance of the inert gas from tissues. Furthermore, this difference in efficiency increases at higher blood flow rates. At a given blood flow, the simple conduction-capacitance model, which has been used to estimate tissue blood perfusion rate from inert gas clearance, underestimates gas clearance rates predicted by the numerical models for single vessel or for two vessels with co-current flow. This difference is accounted for in discussion, which also considers the choice of parameters and possible effects of microvascular architecture on the interpretation of tissue inert gas clearance. PMID:22604885

Numerical Simulation of Desulfurization Behavior in Gas-Stirred Systems Based on Computation Fluid Dynamics-Simultaneous Reaction Model (CFD-SRM) Coupled Model

NASA Astrophysics Data System (ADS)

Lou, Wentao; Zhu, Miaoyong

2014-10-01

A computation fluid dynamics-simultaneous reaction model (CFD-SRM) coupled model has been proposed to describe the desulfurization behavior in a gas-stirred ladle. For the desulfurization thermodynamics, different models were investigated to determine sulfide capacity and oxygen activity. For the desulfurization kinetic, the effect of bubbly plume flow, as well as oxygen absorption and oxidation reactions in slag eyes are considered. The thermodynamic and kinetic modification coefficients are proposed to fit the measured data, respectively. Finally, the effects of slag basicity and gas flow rate on the desulfurization efficiency are investigated. The results show that as the interfacial reactions (Al2O3)-(FeO)-(SiO2)-(MnO)-[S]-[O] simultaneous kinetic equilibrium is adopted to determine the oxygen activity, and the Young's model with the modification coefficient R th of 1.5 is adopted to determine slag sulfide capacity, the predicted sulfur distribution ratio LS agrees well with the measured data. With an increase of the gas blowing time, the predicted desulfurization rate gradually decreased, and when the modification parameter R k is 0.8, the predicted sulfur content changing with time in ladle agrees well with the measured data. If the oxygen absorption and oxidation reactions in slag eyes are not considered in this model, then the sulfur removal rate in the ladle would be overestimated, and this trend would become more obvious with an increase of the gas flow rate and decrease of the slag layer height. With the slag basicity increasing, the total desulfurization ratio increases; however, the total desulfurization ratio changes weakly as the slag basicity exceeds 7. With the increase of the gas flow rate, the desulfurization ratio first increases and then decreases. When the gas flow rate is 200 NL/min, the desulfurization ratio reaches a maximum value in an 80-ton gas-stirred ladle.

Foam flow in a model porous medium: II. The effect of trapped gas.

PubMed

Jones, S A; Getrouw, N; Vincent-Bonnieu, S

2018-05-09

Gas trapping is an important mechanism in both Water or Surfactant Alternating Gas (WAG/SAG) and foam injection processes in porous media. Foams for enhanced oil recovery (EOR) can increase sweep efficiency as they decrease the gas relative permeability, and this is mainly due to gas trapping. However, gas trapping mechanisms are poorly understood. Some studies have been performed during corefloods, but little work has been carried out to describe the bubble trapping behaviour at the pore scale. We have carried out foam flow tests in a micromodel etched with an irregular hexagonal pattern. Image analysis of the foam flow allowed the bubble centres to be tracked and local velocities to be obtained. It was found that the flow in the micromodel is dominated by intermittency and localized zones of trapped gas. The quantity of trapped gas was measured both by considering the fraction of bubbles that were trapped (via velocity thresholding) and by measuring the area fraction containing immobile gas (via image analysis). A decrease in the quantity of trapped gas was observed for both increasing total velocity and increasing foam quality. Calculations of the gas relative permeability were made with the Brooks Corey equation, using the measured trapped gas saturations. The results showed a decrease in gas relative permeabilities, and gas mobility, for increasing fractions of trapped gas. It is suggested that the shear thinning behaviour of foam could be coupled to the saturation of trapped gas.

Applying Alkyl-Chain Surface Functionalizations in Mesoporous Inorganic Structures: Their Impact on Gas Flow and Selectivity Depending on Temperature.

PubMed

Besser, Benjamin; Ahmed, Atiq; Baune, Michael; Kroll, Stephen; Thöming, Jorg; Rezwan, Kurosch

2016-10-12

Porous inorganic capillary membranes are prepared to serve as model structures for the experimental investigation of the gas transport in functionalized mesopores. The porous structures possess a mean pore diameter of 23 nm which is slightly reduced to 20 nm after immobilizing C 16 -alkyl chains on the surface. Gas permeation measurements are performed at temperatures ranging from 0 to 80 °C using Ar, N 2 , and CO 2 . Nonfunctionalized structures feature a gas transport according to Knudsen diffusion with regard to gas flow and selectivity. After C 16 -functionalization, the gas flow is reduced by a factor of 10, and the ideal selectivities deviate from the Knudsen theory. CO 2 adsorption measurements show a decrease in total amount of adsorbed gas and isosteric heat of adsorption. It is hypothesized that the immobilized C 16 -chains sterically influence the gas transport behavior without a contribution from adsorption effects. The reduced gas flow derives from an additional surface resistance caused by the C 16 -chains spacially limiting the adsorption and desorption directions for gas molecules propagating through the structure, resulting in longer diffusion paths. In agreement, the gas flow is found to correlate with the molecular diameter of the gas species (CO 2 < Ar < N 2 ) increasing the resistance for larger molecules. This affects the ideal selectivities with the relation [Formula: see text]. The influence on selectivity increases with increasing temperature which leads to the conclusion that the temperature induced movement of the C 16 -chains is responsible for the stronger interaction between gas molecules and surface functional groups.

The carrier gas pressure effect in a laminar flow diffusion chamber, homogeneous nucleation of n-butanol in helium.

PubMed

Hyvärinen, Antti-Pekka; Brus, David; Zdímal, Vladimír; Smolík, Jiri; Kulmala, Markku; Viisanen, Yrjö; Lihavainen, Heikki

2006-06-14

Homogeneous nucleation rate isotherms of n-butanol+helium were measured in a laminar flow diffusion chamber at total pressures ranging from 50 to 210 kPa to investigate the effect of carrier gas pressure on nucleation. Nucleation temperatures ranged from 265 to 280 K and the measured nucleation rates were between 10(2) and 10(6) cm(-3) s(-1). The measured nucleation rates decreased as a function of increasing pressure. The pressure effect was strongest at pressures below 100 kPa. This negative carrier gas effect was also temperature dependent. At nucleation temperature of 280 K and at the same saturation ratio, the maximum deviation between nucleation rates measured at 50 and 210 kPa was about three orders of magnitude. At nucleation temperature of 265 K, the effect was negligible. Qualitatively the results resemble those measured in a thermal diffusion cloud chamber. Also the slopes of the isothermal nucleation rates as a function of saturation ratio were different as a function of total pressure, 50 kPa isotherms yielded the steepest slopes, and 210 kPa isotherms the shallowest slopes. Several sources of inaccuracies were considered in the interpretation of the results: uncertainties in the transport properties, nonideal behavior of the vapor-carrier gas mixture, and shortcomings of the used mathematical model. Operation characteristics of the laminar flow diffusion chamber at both under-and over-pressure were determined to verify a correct and stable operation of the device. We conclude that a negative carrier gas pressure effect is seen in the laminar flow diffusion chamber and it cannot be totally explained with the aforementioned reasons.

The Breakup Mechanism and the Spray Pulsation Behavior of a Three-Stream Atomizer

NASA Astrophysics Data System (ADS)

Ng, Chin; Dord, Anne; Aliseda, Alberto

2011-11-01

In many processes of industrial importance, such as gasification, the liquid to gas mass ratio injected at the atomizer exceeds the limit of conventional two-fluid coaxial atomizers. To maximize the shear rate between the atomization gas and the liquid while maintaining a large contact area, a secondary gas stream is added at the centerline of the spray, interior to the liquid flow, which is annular in this configuration. This cylindrical gas jet has low momentum and does not contribute to the breakup process, which is still dominated by the high shear between the concentric annular liquid flow and the high momentum gas stream. The presence of two independently controlled gas streams leads to the appearance of a hydrodynamic instability that manifests itself in pulsating liquid flow rates and droplet sizes. We study the dependency of the atomization process on the relative flow rates of the three streams. We measure the size distribution, droplet number density and total liquid volumetric flow rate as a function of time, for realistic Weber and Ohnesorge numbers. Analysis of the temporal evolution of these physical variables reveals the dominant frequency of the instability and its effect on the breakup and dispersion of droplets in the spray. We present flow visualization and Phase Doppler Particle Analyzer results that provide insight into the behavior of this complex coaxial shear flow.

Hot gas ingestion test results of a two-poster vectored thrust concept with flow visualization in the NASA Lewis 9- by 15-foot low speed wind tunnel

NASA Technical Reports Server (NTRS)

Johns, Albert L.; Neiner, George; Bencic, Timothy J.; Flood, Joseph D.; Amuedo, Kurt C.

1990-01-01

A 9.2 percent scale STOVL hot gas ingestion model was tested in the NASA Lewis 9 x 15-foot Low-Speed Wind Tunnel. Flow visualization from the Phase 1 test program, which evaluated the hot ingestion phenomena and control techniques, is covered. The Phase 2 test program evaluated the hot gas ingestion phenomena at higher temperatures and used a laser sheet to investigate the flow field. Hot gas ingestion levels were measured for the several forward nozzle splay configurations and with flow control/life improvement devices (LIDs) which reduced the hot gas ingestion. The test was conducted at full scale nozzle pressure ratios and inlet Mach numbers. Results are presented over a range of nozzle pressure ratios at a 10 kn headwind velocity. The Phase 2 program was conducted at exhaust nozzle temperatures up to 1460 R and utilized a sheet laser system for flow visualization of the model flow field in and out of ground effects. The results reported are for nozzle exhaust temperatures up to 1160 R and contain the compressor face pressure and temperature distortions, the total pressure recovery, the inlet temperature rise, and the environmental effects of the hot gas. The environmental effects include the ground plane contours, the model airframe heating, and the location of the ground flow separation.

78 FR 43186 - Commission Information Collection Activities; Comment Request; Extension

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-19

...) Natural Gas Companies 11 1 11 75 825 The total estimated annual cost burden to respondents is $57,750... authorize the Commission to order a refund (with interest) for any portion of a natural gas company's... gas companies to ensure that the flow-through of refunds owed by these companies are made as...

40 CFR 60.266 - Test methods and procedures.

Code of Federal Regulations, 2010 CFR

2010-07-01

... effluent gas from exhaust stream “i”, dscm/hr (dscf/hr). P=average furnace power input, MW. K=conversion....8, the owner or operator shall not allow gaseous diluents to be added to the effluent gas stream after the fabric in an open pressurized fabric filter collector unless the total gas volume flow from...

Direct measurements of methane emissions from abandoned oil and gas wells in Pennsylvania

PubMed Central

Kang, Mary; Kanno, Cynthia M.; Reid, Matthew C.; Zhang, Xin; Mauzerall, Denise L.; Celia, Michael A.; Chen, Yuheng; Onstott, Tullis C.

2014-01-01

Abandoned oil and gas wells provide a potential pathway for subsurface migration and emissions of methane and other fluids to the atmosphere. Little is known about methane fluxes from the millions of abandoned wells that exist in the United States. Here, we report direct measurements of methane fluxes from abandoned oil and gas wells in Pennsylvania, using static flux chambers. A total of 42 and 52 direct measurements were made at wells and at locations near the wells (“controls”) in forested, wetland, grassland, and river areas in July, August, October 2013 and January 2014, respectively. The mean methane flow rates at these well locations were 0.27 kg/d/well, and the mean methane flow rate at the control locations was 4.5 × 10−6 kg/d/location. Three out of the 19 measured wells were high emitters that had methane flow rates that were three orders of magnitude larger than the median flow rate of 1.3 × 10−3 kg/d/well. Assuming the mean flow rate found here is representative of all abandoned wells in Pennsylvania, we scaled the methane emissions to be 4–7% of estimated total anthropogenic methane emissions in Pennsylvania. The presence of ethane, propane, and n-butane, along with the methane isotopic composition, indicate that the emitted methane is predominantly of thermogenic origin. These measurements show that methane emissions from abandoned oil and gas wells can be significant. The research required to quantify these emissions nationally should be undertaken so they can be accurately described and included in greenhouse gas emissions inventories. PMID:25489074

Direct measurements of methane emissions from abandoned oil and gas wells in Pennsylvania.

PubMed

Kang, Mary; Kanno, Cynthia M; Reid, Matthew C; Zhang, Xin; Mauzerall, Denise L; Celia, Michael A; Chen, Yuheng; Onstott, Tullis C

2014-12-23

Abandoned oil and gas wells provide a potential pathway for subsurface migration and emissions of methane and other fluids to the atmosphere. Little is known about methane fluxes from the millions of abandoned wells that exist in the United States. Here, we report direct measurements of methane fluxes from abandoned oil and gas wells in Pennsylvania, using static flux chambers. A total of 42 and 52 direct measurements were made at wells and at locations near the wells ("controls") in forested, wetland, grassland, and river areas in July, August, October 2013 and January 2014, respectively. The mean methane flow rates at these well locations were 0.27 kg/d/well, and the mean methane flow rate at the control locations was 4.5 × 10(-6) kg/d/location. Three out of the 19 measured wells were high emitters that had methane flow rates that were three orders of magnitude larger than the median flow rate of 1.3 × 10(-3) kg/d/well. Assuming the mean flow rate found here is representative of all abandoned wells in Pennsylvania, we scaled the methane emissions to be 4-7% of estimated total anthropogenic methane emissions in Pennsylvania. The presence of ethane, propane, and n-butane, along with the methane isotopic composition, indicate that the emitted methane is predominantly of thermogenic origin. These measurements show that methane emissions from abandoned oil and gas wells can be significant. The research required to quantify these emissions nationally should be undertaken so they can be accurately described and included in greenhouse gas emissions inventories.

Supersonic Coaxial Jet Experiment for CFD Code Validation

NASA Technical Reports Server (NTRS)

Cutler, A. D.; Carty, A. A.; Doerner, S. E.; Diskin, G. S.; Drummond, J. P.

1999-01-01

A supersonic coaxial jet facility has been designed to provide experimental data suitable for the validation of CFD codes used to analyze high-speed propulsion flows. The center jet is of a light gas and the coflow jet is of air, and the mixing layer between them is compressible. Various methods have been employed in characterizing the jet flow field, including schlieren visualization, pitot, total temperature and gas sampling probe surveying, and RELIEF velocimetry. A Navier-Stokes code has been used to calculate the nozzle flow field and the results compared to the experiment.

Flow injection gas chromatography with sulfur chemiluminescence detection for the analysis of total sulfur in complex hydrocarbon matrixes.

PubMed

Hua, Yujuan; Hawryluk, Myron; Gras, Ronda; Shearer, Randall; Luong, Jim

2018-01-01

A fast and reliable analytical technique for the determination of total sulfur levels in complex hydrocarbon matrices is introduced. The method employed flow injection technique using a gas chromatograph as a sample introduction device and a gas phase dual-plasma sulfur chemiluminescence detector for sulfur quantification. Using the technique described, total sulfur measurement in challenging hydrocarbon matrices can be achieved in less than 10 s with sample-to-sample time <2 min. The high degree of selectivity and sensitivity toward sulfur compounds of the detector offers the ability to measure low sulfur levels with a detection limit in the range of 20 ppb w/w S. The equimolar response characteristic of the detector allows the quantitation of unknown sulfur compounds and simplifies the calibration process. Response is linear over a concentration range of five orders of magnitude, with a high degree of repeatability. The detector's lack of response to hydrocarbons enables direct analysis without the need for time-consuming sample preparation and chromatographic separation processes. This flow injection-based sulfur chemiluminescence detection technique is ideal for fast analysis or trace sulfur analysis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Prandtl-Meyer flow tables for parahydrogen at total temperatures from 30K to 290K and for nitrogen at total temperatures from 100K to 300K at total pressures from 1 ATM to 10 ATM

NASA Technical Reports Server (NTRS)

Haut, R. C.; Adcock, J. B.

1976-01-01

The dependency of Mach number on the Prandtl-Meyer function was numerically determined by iterating the Prandtl-Meyer function and applying the Muller method to converge on the Mach number for flows in cryogenic parahydrogen and nitrogen at various total pressures and total temperatures. The results are compared with the ideal diatomic gas values and are presented in tabular form.

The Superorbital Expansion Tube concept, experiment and analysis

NASA Technical Reports Server (NTRS)

Neely, A. J.; Morgan, R. G.

1995-01-01

In response to the need for ground testing facilities for super orbital re-entry research, a small scale facility has been set up at the University of Queensland to demonstrate the superorbital expansion tube concept. This unique device is a free piston driven, triple diaphragm, impulse shock facility which uses the enthalpy multiplication mechanism of the unsteady expansion process and the addition of a secondary shock driver to further heat the driver gas. The pilot facility has been operated to produce quasi-steady test flows in air with shock velocities in excess of 13 km/s and with a usable test flow duration of the order of 15 micro sec. an experimental condition produced in the facility with total enthalpy of 108 MJ/kg and a total pressure of 335 MPa is reported. A simple analytical flow model which accounts for non-ideal rupture of the light tertiary diaphragm and the resulting entropy increase in the test gas is discussed. It is shown that equilibrium calculations more accurately model the unsteady expansion process than calculations assuming frozen chemistry. This is because the high enthalpy flows produced in the facility can only be achieved if the chemical energy stored in the test flow during shock heating of the test gas is partially returned to the flow during the process of unsteady expansion. Measurements of heat transfer rates to a flat plate demonstrate the usability of test flow for aerothermodynamic testing and comparison of these rates with empirical calculations confirms the usable accuracy of the flow model.

Numerical simulations of the flow in the HYPULSE expansion tube

NASA Technical Reports Server (NTRS)

Wilson, Gregory J.; Sussman, Myles A.; Bakos, Robert J.

1995-01-01

Axisymmetric numerical simulations with finite-rate chemistry are presented for two operating conditions in the HYPULSE expansion tube. The operating gas for these two cases is nitrogen and the computations are compared to experimental data. One test condition is at a total enthalpy of 15.2 MJ/Kg and a relatively low static pressure of 2 kPa. This case is characterized by a laminar boundary layer and significant chemical nonequilibrium in the acceleration gas. The second test condition is at a total enthalpy of 10.2 MJ/Kg and a static pressure of 38 kPa and is characterized by a turbulent boundary layer. For both cases, the time-varying test gas pressure predicted by the simulations is in good agreement with experimental data. The computations are also found to be in good agreement with Mirels' correlations for shock tube flow. It is shown that the nonuniformity of the test gas observed in the HYPULSE expansion tube is strongly linked to the boundary layer thickness. The turbulent flow investigated has a larger boundary layer and greater test gas nonuniformity. In order to investigate possibilities of improving expansion tube flow quality by reducing the boundary layer thickness, parametric studies showing the effect of density and turbulent transition point on the test conditions are also presented. Although an increase in the expansion tube operating pressure level would reduce the boundary layer thickness, the simulations indicate that the reduction would be less than what is predicted by flat plate boundary layer correlations.

Mapping the dark matter in the NGC 5044 group with ROSAT: Evidence for a nearly homogeneous cooling flow with a cooling wake

NASA Technical Reports Server (NTRS)

David, Laurence P.; Jones, Christine; Forman, William; Daines, Stuart

1994-01-01

The NGC 5044 group of galaxies was observed by the ROSAT Position Sensitive Proportional Counter (PSPC) for 30 ks during its reduced pointed phase (1991 July). Due to the relatively cool gas temperature in the group (kT = 0.98 +/- 0.02 keV) and the excellent photon statistics (65,000 net counts), we are able to determine precisely a number of fundamental properties of the group within 250 kpc of the central galaxy. In particular, we present model-independent measurements of the total gravitating mass, the temperature and abundance profiles of the gas, and the mass accretion rate. Between 60 and 250 kpc, the gas is nearly isothermal with T varies as r(exp (-0.13 +/- 0.03)). The total gravitating mass of the group can be unambiguously determined from the observed density and temperature profiles of the gas using the equation of hydrostatic equilibrium. Within 250 kpc, the gravitating mass is 1.6 x 10(exp 13) solar mass, yielding a mass-to-light ratio of 130 solar mass/solar luminosity. The baryons (gas and stars) comprise 12% of the total mass within this radius. At small radii, the temperature clearly increases outward and attains a maximum value at 60 kpc. The positive temperature gradient in the center of the group confirms the existence of a cooling flow. The cooling flow region extends well beyond the temperature maximum with a cooling radius between 100 and 150 kpc. There are two distinct regions in the cooling flow separated by the temperature maximum. In the outer region, the gas is nearly isothermal with a unifor m Fe abundance of approximately 80% solar, the flow is nearly homogeneous with dot-M= 20 to 25 solar mass/year, the X-ray contours are spherically symmetric, and rho(sub gas) varies as r(exp -1.6). In the inner region, the temperature profile has a positive gradient, the mass accretion rate decreases rapidly inward, the gas density profile is steeper, and the X-ray image shows some substrucutre. NGC 5044 is offset from the centroid of the outer X-ray contours indicating that the central galaxy may have a residual velocity with respect to the center of the group potential. There is also a linear X-ray feature with an extent of approximately 30 kpc with one end coincident with NGC 5044. The X-ray emission from this feature is softer than the ambient gas. We interpret this feature as a 'cooling wake' formed by the accreting gas as it is gravitationally focused into the wake of NGC 5044. One of the most surprising results of our PSPC observation is the discovery of a nearly homogeneous cooling flow. Prior results concerning the mass accretion profile in cooling flows indicate that dot-M varies as r. This relation implies that significant mass deposition occurs at large radii which generates an inhomogeneous flow. The mass accretion rate in the NGC 5044 group is essentially a constant beyond 40 kpc (well within the cooling radius). Significant mass deposition (a declining dot-M) does not commence until the gas accretes to within 40 kpc of the group center where the radiative cooling time is approximately equals 10(exp 9) year. Th is radius also corresponds to the temperature maximum, the break in gas density profile, and the onset of structure in the X-ray image. A Hubble constant of H(sub 0) = 50 km/sec/Mpc is used throughout the paper.

Effect of indirect non-thermal plasma on particle size distribution and composition of diesel engine particles

NASA Astrophysics Data System (ADS)

Linbo, GU; Yixi, CAI; Yunxi, SHI; Jing, WANG; Xiaoyu, PU; Jing, TIAN; Runlin, FAN

2017-11-01

To explore the effect of the gas source flow rate on the actual diesel exhaust particulate matter (PM), a test bench for diesel engine exhaust purification was constructed, using indirect non-thermal plasma technology. The effects of different gas source flow rates on the quantity concentration, composition, and apparent activation energy of PM were investigated, using an engine exhaust particle sizer and a thermo-gravimetric analyzer. The results show that when the gas source flow rate was large, not only the maximum peak quantity concentrations of particles had a large drop, but also the peak quantity concentrations shifted to smaller particle sizes from 100 nm to 80 nm. When the gas source flow rate was 10 L min-1, the total quantity concentration greatly decreased where the removal rate of particles was 79.2%, and the variation of the different mode particle proportion was obvious. Non-thermal plasma (NTP) improved the oxidation ability of volatile matter as well as that of solid carbon. However, the NTP gas source rate had little effects on oxidation activity of volatile matter, while it strongly influenced the oxidation activity of solid carbon. Considering the quantity concentration and oxidation activity of particles, a gas source flow rate of 10 L min-1 was more appropriate for the purification of particles.

Life and Times of the X-Ray Gas in Elliptical Galaxies

NASA Astrophysics Data System (ADS)

Renzini, Alvio

2000-09-01

The global gas flows in elliptical galaxies are initiated by stellar mass loss and their diagnostics rely on X-ray observations. The flows are controlled by a number of factors, including supernova heating, the depth and shape of the potential well as determined by the amount and distribution of bright and dark matter, AGN fueling and its feedback effects, interaction with the intracluster medium, and star formation. As a result no steady-state solution can satisfactorily describe the complex, evolutionary behavior of the gas flows, which can experience supersonic wind, subsonic outflow, and inflow phases, and transitions between one such flow regime to another. Having identified heating by Type Ia SN's as one of the key factors controlling the flows, constraints on its evolution with cosmological time are derived by considering the total amount of iron contained in whole clusters of galaxies, while the iron abundance in individual galaxy flows can set constraints on the present rate of SNIa's in ellipticals. The central issue of the problem remains the fate of the gas. It is argued that in one way or another, via SN-driven winds, ram pressure stripping, or AGN violent ejection, most of the gas is ultimately expelled from galaxies thus joining the intracluster medium.

Highly sensitive silicon microreactor for catalyst testing

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

Henriksen, Toke R.; Hansen, Ole; Department of Physics, Danish National Research Foundation's Center for Individual Nanoparticle Functionality

2009-12-15

A novel microfabricated chemical reactor for highly sensitive measurements of catalytic activity and surface kinetics is presented. The reactor is fabricated in a silicon chip and is intended for gas-phase reactions at pressures ranging from 0.1 to 5.0 bar. A high sensitivity is obtained by directing the entire gas flow through the catalyst bed to a mass spectrometer, thus ensuring that nearly all reaction products are present in the analyzed gas flow. Although the device can be employed for testing a wide range of catalysts, the primary aim of the design is to allow characterization of model catalysts which canmore » only be obtained in small quantities. Such measurements are of significant fundamental interest but are challenging because of the low surface areas involved. The relationship between the reaction zone gas flow and the pressure in the reaction zone is investigated experimentally. A corresponding theoretical model is presented, and the gas flow through an on-chip flow-limiting capillary is predicted to be in the intermediate regime. The experimental data for the gas flow are found to be in good agreement with the theoretical model. At typical experimental conditions, the total gas flow through the reaction zone is around 3x10{sup 14} molecules s{sup -1}, corresponding to a gas residence time in the reaction zone of about 11 s. To demonstrate the operation of the microreactor, CO oxidation on low-area platinum thin film circles is employed as a test reaction. Using temperature ramping, it is found that platinum catalysts with areas as small as 15 {mu}m{sup 2} are conveniently characterized with the device.« less

The influence of the cluster environment on the star formation efficiency of 12 Virgo spiral galaxies

NASA Astrophysics Data System (ADS)

Vollmer, B.; Wong, O. I.; Braine, J.; Chung, A.; Kenney, J. D. P.

2012-07-01

The influence of the environment on gas surface density and star formation efficiency of cluster spiral galaxies is investigated. We extend previous work on radial profiles by a pixel-to pixel analysis looking for asymmetries due to environmental interactions. The star formation rate is derived from GALEX UV and Spitzer total infrared data based on the 8, 24, 70, and 160 μm data. As in field galaxies, the star formation rate for most Virgo galaxies is approximately proportional to the molecular gas mass. Except for NGC 4438, the cluster environment does not affect the star formation efficiency with respect to the molecular gas. Gas truncation is not associated with major changes in the total gas surface density distribution of the inner disk of Virgo spiral galaxies. In three galaxies (NGC 4430, NGC 4501, and NGC 4522), possible increases in the molecular fraction and the star formation efficiency with respect to the total gas, of factors of 1.5 to 2, are observed on the windward side of the galactic disk. A significant increase of the star formation efficiency with respect to the molecular gas content on the windward side of ram pressure-stripped galaxies is not observed. The ram-pressure stripped extraplanar gas of 3 highly inclined spiral galaxies (NGC 4330, NGC 4438, and NGC 4522) shows a depressed star formation efficiency with respect to the total gas, and one of them (NGC 4438) shows a depressed rate even with respect to the molecular gas. The interpretation is that stripped gas loses the gravitational confinement and associated pressure of the galactic disk, and the gas flow is diverging, so the gas density decreases and the star formation rate drops. We found two such regions of low star formation efficiency in the more face-on galaxies NGC 4501 and NGC 4654 which are both undergoing ram pressure stripping. These regions show low radio continuum emission or unusually steep radio spectral index. However, the stripped extraplanar gas in one highly inclined galaxy (NGC 4569) shows a normal star formation efficiency with respect to the total gas. We propose this galaxy is different because it is observed long after peak pressure, and its extraplanar gas is now in a converging flow as it resettles back into the disk. Appendices are available in electronic form http://www.aanda.org

Variational energy principle for compressible, baroclinic flow. 1: First and second variations of total kinetic action

NASA Technical Reports Server (NTRS)

Schmid, L. A.

1977-01-01

The case of a cold gas in the absence of external force fields is considered. Since the only energy involved is kinetic energy, the total kinetic action (i.e., the space-time integral of the kinetic energy density) should serve as the total free-energy functional in this case, and as such should be a local minimum for all possible fluctuations about stable flow. This conjecture is tested by calculating explicit, manifestly covariant expressions for the first and second variations of the total kinetic action in the context of Lagrangian kinematics. The general question of the correlation between physical stability and the convexity of any action integral that can be interpreted as the total free-energy functional of the flow is discussed and illustrated for the cases of rectillinear and rotating shearing flows.

A study of high speed flows in an aircraft transition duct. Ph.D. Thesis - Iowa State Univ.

NASA Technical Reports Server (NTRS)

Reichert, Bruce A.

1991-01-01

The study of circular-to-rectangular transition duct flows with and without inlet swirl is presented. A method was devised to create a swirling, solid body rotational flow with minimal associated disturbances. Details of the swirl generator design and construction are discussed. Coefficients based on velocities and total and static pressures measured in cross stream planes at four axial locations within the transition duct along with surface static pressures and surface oil film visualization are presented for both nonswirling and swirling incoming flows. A method was developed to acquire trace gas measurements within the transition duct at high flow velocities. Statistical methods are used to help interpret the trace gas results.

Respiratory analysis system and method

NASA Technical Reports Server (NTRS)

Liu, F. F. (Inventor)

1973-01-01

A system is described for monitoring the respiratory process in which the gas flow rate and the frequency of respiration and expiration cycles can be determined on a real time basis. A face mask is provided with one-way inlet and outlet valves where the gas flow is through independent flowmeters and through a mass spectrometer. The opening and closing of a valve operates an electrical switch, and the combination of the two switches produces a low frequency electrical signal of the respiratory inhalation and exhalation cycles. During the time a switch is operated, the corresponsing flowmeter produces electric pulses representative of the flow rate; the electrical pulses being at a higher frequency than that of the breathing cycle and combined with the low frequency signal. The high frequency pulses are supplied to conventional analyzer computer which also receives temperature and pressure inputs and computes mass flow rate and totalized mass flow of gas. From the mass spectrometer, components of the gas are separately computed as to flow rate. The electrical switches cause operation of up-down inputs of a reversible counter. The respective up and down cycles can be individually monitored and combined for various respiratory measurements.

Program and charts for determining shock tube, and expansion tunnel flow quantities for real air

NASA Technical Reports Server (NTRS)

Miller, C. G., III; Wilder, S. E.

1975-01-01

A computer program in FORTRAN 4 language was written to determine shock tube, expansion tube, and expansion tunnel flow quantities for real-air test gas. This program permits, as input data, a number of possible combinations of flow quantities generally measured during a test. The versatility of the program is enhanced by the inclusion of such effects as a standing or totally reflected shock at the secondary diaphragm, thermochemical-equilibrium flow expansion and frozen flow expansion for the expansion tube and expansion tunnel, attenuation of the flow in traversing the acceleration section of the expansion tube, real air as the acceleration gas, and the effect of wall boundary layer on the acceleration section air flow. Charts which provide a rapid estimation of expansion tube performance prior to a test are included.

Control system adds to precipitator efficiency

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

Gurrole, G.

1978-02-01

An electrostatic precipitator in use at Lion Oil Co., Martinez, Calif., in a fluid catalytic cracking and CO boiler application, was upgraded by mechanical sectionalization of the gas passage and a new electronic control system. The electrostatic precipitator is installed upstream of the CO boiler to handle gas flow up to 4.77 ft/sec, and pressure to 4.5 psi. The independent gas chambers in the electrostatic precipitator were divided by installing gas-tight partition walls to form a total of four electrostatic fields. The precipitator was also equipped with adjustable inlet gas flow-control baffles for even gas distribution. Rows of grounded collectingmore » electrodes are parallel with the flow of gas. The emitting electrode system, powered by separate high-energy transformers for each collecting field, uses silicon-controlled rectifiers and analog electronic networks for rapid response to changing gas and dust conditions. Regulatory requirements call for efficient collection of catalyst fines with no more than 40 lb/hr escaping through the boiler stack. Currently, stack losses average about 38 lb/hr. The installation of two additional control systems with transformers and rectifiers should reduce stack losses to 34 lb/hr.« less

Novel Prospects for Plasma Spray-Physical Vapor Deposition of Columnar Thermal Barrier Coatings

NASA Astrophysics Data System (ADS)

Anwaar, Aleem; Wei, Lianglinag; Guo, Qian; Zhang, Baopeng; Guo, Hongbo

2017-12-01

Plasma spray-physical vapor deposition (PS-PVD) is an emerging coating technique that can produce columnar thermal barrier coatings from vapor phase. Feedstock treatment at the start of its trajectory in the plasma torch nozzle is important for such vapor-phase deposition. This study describes the effects of the plasma composition (Ar/He) on the plasma characteristics, plasma-particle interaction, and particle dynamics at different points spatially distributed inside the plasma torch nozzle. The results of calculations show that increasing the fraction of argon in the plasma gas mixture enhances the momentum and heat flow between the plasma and injected feedstock. For the plasma gas combination of 45Ar/45He, the total enthalpy transferred to a representative powder particle inside the plasma torch nozzle is highest ( 9828 kJ/kg). Moreover, due to the properties of the plasma, the contribution of the cylindrical throat, i.e., from the feed injection point (FIP) to the start of divergence (SOD), to the total transferred energy is 69%. The carrier gas flow for different plasma gas mixtures was also investigated by optical emission spectroscopy (OES) measurements of zirconium emissions. Yttria-stabilized zirconia (YSZ) coating microstructures were produced when using selected plasma gas compositions and corresponding carrier gas flows; structural morphologies were found to be in good agreement with OES and theoretical predictions. Quasicolumnar microstructure was obtained with porosity of 15% when applying the plasma composition of 45Ar/45He.

Distribution of E/N and N/e/ in a cross-flow electric discharge laser. [electric field to neutral gas density and electron number density

NASA Technical Reports Server (NTRS)

Dunning, J. W., Jr.; Lancashire, R. B.; Manista, E. J.

1976-01-01

Measurements have been conducted of the effect of the convection of ions and electrons on the discharge characteristics in a large scale laser. The results are presented for one particular distribution of ballast resistance. Values of electric field, current density, input power density, ratio of electric field to neutral gas density (E/N), and electron number density were calculated on the basis of measurements of the discharge properties. In a number of graphs, the E/N ratio, current density, power density, and electron density are plotted as a function of row number (downstream position) with total discharge current and gas velocity as parameters. From the dependence of the current distribution on the total current, it appears that the electron production in the first two rows significantly affects the current flowing in the succeeding rows.

Lateral Reaction Jet Flow Interaction Effects on a Generic Fin-Stabilized Munition in Supersonic Crossflows

DTIC Science & Technology

2013-11-01

freestream conditions ( 0 =300 K). .........22  Table 7. Results from nozzle parameter study, variation with jet gas total temperature (AR=1, M=2.5...end. Two additional supersonic nozzles of AR=2 and AR=8 (figures 3e and 3f) were also investigated, also with a throat diameter of 2.54 mm. The...walls, due to the different flow properties from the gas expansion there. Therefore, the plenum and nozzle exit walls were modeled with an advanced

Internal energy fluctuations of a granular gas under steady uniform shear flow.

PubMed

Brey, J Javier; García de Soria, M I; Maynar, P

2012-09-01

The stochastic properties of the total internal energy of a dilute granular gas in the steady uniform shear flow state are investigated. A recent theory formulated for fluctuations about the homogeneous cooling state is extended by analogy with molecular systems. The theoretical predictions are compared with molecular dynamics simulation results. Good agreement is found in the limit of weak inelasticity, while systematic and relevant discrepancies are observed when the inelasticity increases. The origin of this behavior is discussed.

Self-activation of biochar from furfural residues by recycled pyrolysis gas.

PubMed

Yin, Yulei; Gao, Yuan; Li, Aimin

2018-04-17

Biochar samples with controllable specific surface area and mesopore ratio were self-activated from furfural residues by recycled pyrolysis gas. The objective of this study was to develop a new cyclic utilization method for the gas produced by pyrolysis. The influences of preparation parameters on the resulting biochar were studied by varying the pyrolysis-gas flow rate, activation time and temperature. Structural characterization of the produced biochar was performed by analysis of nitrogen adsorption isotherms at 77 K and scanning electron microscope (SEM). The pyrolysis gas compositions before and after activation were determined by a gas chromatograph. The results indicated that the surface area of the biochar was increased from 167 m 2 /g to 567 m 2 /g, the total pore volume increased from 0.121 cm 3 /g to 0.380 cm 3 /g, and the ratio of the mesopore pore volume to the total pore volume increased 17-39.7%. The CO volume fraction of the pyrolysis gas changed from 34.66 to 62.29% and the CO 2 volume fraction decreased from 48.26% to 12.17% under different conditions of pyrolysis-gas flow rate, activation time and temperature. The calorific values of pyrolysis gas changed from 8.82 J/cm 3 to 14.00 J/cm 3 , which were higher than those of conventional pyrolysis gases. The slower pyrolysis-gas flow rate and higher activation time increased the efficiency of the reaction between carbon and pyrolysis gas. These results demonstrated the feasibility of treatment of the furfural residues to produce microporous and mesoporous biochar. The pyrolysis gas that results from the activation process could be used as fuel. Overall, this new self-activation method meets the development requirements of cyclic economy and cleaner production. Copyright © 2018. Published by Elsevier Ltd.

A shock capturing technique for hypersonic, chemically relaxing flows

NASA Technical Reports Server (NTRS)

Eberhardt, S.; Brown, K.

1986-01-01

A fully coupled, shock capturing technique is presented for chemically reacting flows at high Mach numbers. The technique makes use of a total variation diminishing (TVD) dissipation operator which results in sharp, crisp shocks. The eigenvalues and eigenvectors of the fully coupled system, which includes species conversion equations in addition to the gas dynamics equations, are analytically derived for a general reacting gas. Species production terms for a model dissociating gas are introduced and are included in the algorithm. The convective terms are solved using a first-order TVD scheme while the source terms are solved using a fourth-order Runge-Kutta scheme to enhance stability. Results from one-dimensional numerical experiments are shown for a two species and a three species gas.

Mixed Convective Condensation in Enclosures with Noncondensable Gases

NASA Astrophysics Data System (ADS)

Fox, Richard John

1994-01-01

A transient, two-dimensional, numerical model was developed in order to study the laminar flow, heat, and mass transfer in a vertical reflux condenser loaded with vapor and noncondensable gas. The simplified model treats the two-component (gas/vapor), two-phase (vapor/liquid) mixture as a continuum by making use of conservation equations for mass continuity, momentum, species, and energy. The liquid mist phase is formed in such a way as to obey one of three conditions: thermodynamic equilibrium, complete nonequilibrium (no mist formation), or partial equilibrium (partial supersaturation). In developing the model, special attention was paid to the formulation of the boundary conditions, global continuity, and numerical efficiency. Two different mixture combinations were used in order to create stable and unstable systems. Steam-helium mixtures (Mv, = 18, Mg = 4) were found to exhibit stable flows with the lighter helium trapped in the upper portion of the condenser, shutting off condensation in that region. Steam-air mixtures (M_ {v}, = 18, Mg = 28) were found to exhibit varying degrees of instability, depending on the noncondensable gas and heat load, owing to the accumulation of the heavy gas near the condensing surface. Under low gas loading cases (Pg = 0.031 kg/m^3) the natural convective fluctuations were found to be weak and the flow was more easily dominated by the forced convective inlet flow and wall suction. At such low gas loadings, stable, asymmetric flow patterns persisted up to high powers. Large gas loadings (Pg = 0.196 kg/m^3) showed much stronger natural convective effects. Regions of counterflowing vapor and gas were found to promote stronger mixing as the power was increased. Regions of noncondensing gas were found to blanket the condenser walls as the suction velocity increased, resulting in a strong resistance to heat and mass transfer and consequent increase in system pressure. Moderate gas loadings (Pg = 0.065 kg/m ^3) were found to exhibit intermediate behavior between the low and high gas loading cases. For the moderate gas loading cases, a bifurcation was found to occur when Re was increased beyond a critical value, forcing the system into one of two stable, distinct flow patterns. Each branch of the bifurcation was found to correspond to the flows that occur in either the low or high gas loading cases, and radically different heat transfer performance was encountered for the same system parameters. The model was also used to simulate experiments conducted in a vertical reflux thermosyphon using steam -air mixtures. The qualitative aspects of the flow were in reasonable agreement between the model and experiment and trends in the local heat transfer were similar. By converting latent heat energy into sensible heat energy, mist formation was found to increase the system temperature and, as a consequence, the overall heat transfer coefficient was lowered. However, the total heat transfer rate was not sensitive to mist formation since the reduction in the latent heat transfer was accompanied by a corresponding increase in the sensible heat transfer, altering the mode but not the magnitude of the total heat transfer.

Switch Box For Controlling Flows Of Four Gases

NASA Technical Reports Server (NTRS)

Wishard, James R.; Lamb, James L.

1995-01-01

Switch box designed for use in simultaneously controlling flows of as many as four out of total of six available gases into semiconductor-processing chamber. Contains switches, relays, logic circuitry, display devices, and other circuitry for connecting each of as many as four gas controllers to any one of as many as six available mass-flow controllers. Front panel of switch box apprises technician of statuses of flows of various gases.

A comparison of upwind schemes for computation of three-dimensional hypersonic real-gas flows

NASA Technical Reports Server (NTRS)

Gerbsch, R. A.; Agarwal, R. K.

1992-01-01

The method of Suresh and Liou (1992) is extended, and the resulting explicit noniterative upwind finite-volume algorithm is applied to the integration of 3D parabolized Navier-Stokes equations to model 3D hypersonic real-gas flowfields. The solver is second-order accurate in the marching direction and employs flux-limiters to make the algorithm second-order accurate, with total variation diminishing in the cross-flow direction. The algorithm is used to compute hypersonic flow over a yawed cone and over the Ames All-Body Hypersonic Vehicle. The solutions obtained agree well with other computational results and with experimental data.

Mercury mass flow in iron and steel production process and its implications for mercury emission control.

PubMed

Wang, Fengyang; Wang, Shuxiao; Zhang, Lei; Yang, Hai; Gao, Wei; Wu, Qingru; Hao, Jiming

2016-05-01

The iron and steel production process is one of the predominant anthropogenic sources of atmospheric mercury emissions worldwide. In this study, field tests were conducted to study mercury emission characteristics and mass flows at two iron and steel plants in China. It was found that low-sulfur flue gas from sintering machines could contribute up to 41% of the total atmospheric mercury emissions, and desulfurization devices could remarkably help reduce the emissions. Coal gas burning accounted for 17%-49% of the total mercury emissions, and therefore the mercury control of coal gas burning, specifically for the power plant burning coal gas to generate electricity, was significantly important. The emissions from limestone and dolomite production and electric furnaces can contribute 29.3% and 4.2% of the total mercury emissions from iron and steel production. More attention should be paid to mercury emissions from these two processes. Blast furnace dust accounted for 27%-36% of the total mercury output for the whole iron and steel production process. The recycling of blast furnace dust could greatly increase the atmospheric mercury emissions and should not be conducted. The mercury emission factors for the coke oven, sintering machine and blast furnace were 0.039-0.047gHg/ton steel, and for the electric furnace it was 0.021gHg/ton steel. The predominant emission species was oxidized mercury, accounting for 59%-73% of total mercury emissions to air. Copyright © 2016. Published by Elsevier B.V.

TI-59 helps predict IPRs for gravel-packed gas wells

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

Capdevielle, W.C.

The inflow performance relationship (IPR) is an important tool for reservoir and production engineers. It helps optimize completion, tubing, gas lift, and storm choke design. It facilitates accurate rate predictions that can be used to evaluate field development decisions. The IPR is the first step of the systems analysis that translates reservoir rock and fluid parameters into predictable flow rates. Use of gravel packing for sand control complicates the calculation that predicts a well's IPR curve, particularly in gas wells where high velocities in the formation and through gravel-filled perforation tunnels can cause turbulent flow. The program presented in thismore » article calculates the pressure drop and the flowing bottomhole pressures at varying flow rates for gravel-packed gas wells. The program was written for a Texas Instruments TI-59 programmable calculator with a PC-100 printer. Program features include: Calculations for in-casing gravel packs, open-hole gravel packs, or ungravel packed wells. Program prompts for the required data variables. Easy change of data values to run new cases. Calculates pressures for an unlimited number of flow rates. Results show the total pressure drop and the relative magnitude of its components.« less

Zero-G experiments in two-phase fluids flow regimes

NASA Technical Reports Server (NTRS)

Heppner, D. B.; King, C. D.; Littles, J. W.

1975-01-01

The two-phase flows studied were liquid and gas mixtures in a straight flow channel of circular cross-section. Boundaries between flow regimes have been defined for normogravity on coordinates of gas quality and total mass velocity; and, when combined with boundary expressions having a Froude number term, an analytical model was derived predicting boundary shifts with changes in gravity level. Experiments with air and water were performed, first in the normogravity environment of a ground laboratory and then in 'zero gravity' aboard a KC-135 aircraft flying parabolic trajectories. Data reduction confirmed regime boundary shifts in the direction predicted, although the magnitude was a little less than predicted. Pressure drop measurements showed significant increases for the low gravity condition.

3-D Numerical Simulation for Gas-Liquid Two-Phase Flow in Aeration Tank

NASA Astrophysics Data System (ADS)

Xue, R.; Tian, R.; Yan, S. Y.; Li, S.

In the crafts of activated sludge treatment, oxygen supply and the suspending state of activated sludge are primary factors to keep biochemistry process carrying on normally. However, they are all controlled by aeration. So aeration is crucial. The paper focus on aeration, use CFD software to simulate the field of aeration tank which is designed by sludge load method. The main designed size of aeration tank is: total volume: 20 000 m3; corridor width: 8m; total length of corridors: 139m; number of corridors: 3; length of one single corridor: 48m; effective depth: 4.5m; additional depth: 0.5m. According to the similarity theory, a geometrical model is set up in proportion of 10:1. The way of liquid flow is submerge to avoid liquid flow out directly. The grid is plotted by dividing the whole computational area into two parts. The bottom part which contains gas pipe and gas exit hole and the above part which is the main area are plotted by tetrahedron and hexahedron respectively. In boundary conditions, gas is defined as the primary-phase, and liquid is defined as the secondary-phase. Choosing mixture model, two-phase flow field of aeration tank is simulated by solved the Continuity equation for the mixture, Momentum equation for the mixture, Volume fraction equation for the secondary phases and Relative velocity formula when gas velocity is 10m/s, 20m/s, 30m/s. what figure shows is the contour of velocity magnitude for the mixture phase when gas velocity is 20m/s. Through analysis, the simulation tendency is agreed with actual running of aeration tank. It is feasible to use mixture model to simulate flow field of aeration tank by fluent software. According to the simulation result, the better velocity of liquid or gas (the quantity of inlet air) can be chosen by lower cost, and also the performance of aeration tank can be forecast. It will be helpful for designing and operation.

Gas dispersion and immobile gas volume in solid and porous particle biofilter materials at low air flow velocities.

PubMed

Sharma, Prabhakar; Poulsen, Tjalfe G

2010-07-01

Gas-phase dispersion in granular biofilter materials with a wide range of particle sizes was investigated using atmospheric air and nitrogen as tracer gases. Two types of materials were used: (1) light extended clay aggregates (LECA), consisting of highly porous particles, and (2) gravel, consisting of solid particles. LECA is a commercial material that is used for insulation, as a soil conditioner, and as a carrier material in biofilters for air cleaning. These two materials were selected to have approximately the same particle shape. Column gas transport experiments were conducted for both materials using different mean particle diameters, different particle size ranges, and different gas flow velocities. Measured breakthrough curves were modeled using the advection-dispersion equation modified for mass transfer between mobile and immobile gas phases. The results showed that gas dispersivity increased with increasing mean particle diameter for LECA but was independent of mean particle diameter for gravel. Gas dispersivity also increased with increasing particle size range for both media. Dispersivities in LECA were generally higher than for gravel. The mobile gas content in both materials increased with increasing gas flow velocity but it did not show any strong dependency on mean particle diameter or particle size range. The relative fraction of mobile gas compared with total porosity was highest for gravel and lowest for LECA likely because of its high internal porosity.

Hot gas ingestion test results of a two-poster vectored thrust concept with flow visualization in the NASA Lewis 9- x 15-foot low speed wind tunnel

NASA Technical Reports Server (NTRS)

Johns, Albert L.; Neiner, George; Bencic, Timothy J.; Flood, Joseph D.; Amuedo, Kurt C.; Strock, Thomas W.

1990-01-01

A 9.2 percent scale Short Takeoff and Vertical Landing (STOVL) hot gas ingestion model was designed and built by McDonnell Douglas Corporation (MCAIR) and tested in the Lewis Research Center 9 x 15 foot Low Speed Wind Tunnel (LSWT). Hot gas ingestion, the entrainment of heated engine exhaust into the inlet flow field, is a key development issure for advanced short takeoff and vertical landing aircraft. Flow visualization from the Phase 1 test program, which evaluated the hot ingestion phenomena and control techniques, is covered. The Phase 2 test program evaluated the hot gas ingestion phenomena at higher temperatures and used a laser sheet to investigate the flow field. Hot gas ingestion levels were measured for the several forward nozzle splay configurations and with flow control/life improvement devices (LIDs) which reduced the hot gas ingestion. The model support system had four degrees of freedom - pitch, roll, yaw, and vertical height variation. The model support system also provided heated high-pressure air for nozzle flow and a suction system exhaust for inlet flow. The test was conducted at full scale nozzle pressure ratios and inlet Mach numbers. Test and data analysis results from Phase 2 and flow visualization from both Phase 1 and 2 are documented. A description of the model and facility modifications is also provided. Headwind velocity was varied from 10 to 23 kn. Results are presented over a range of nozzle pressure ratios at a 10 kn headwind velocity. The Phase 2 program was conducted at exhaust nozzle temperatures up to 1460 R and utilized a sheet laser system for flow visualization of the model flow field in and out of ground effects. The results reported are for nozzle exhaust temperatures up to 1160 R. These results will contain the compressor face pressure and temperature distortions, the total pressure recovery, the inlet temperature rise, and the environmental effects of the hot gas. The environmental effects include the ground plane contours, the model airframe heating, and the location of the ground flow separation.

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.

Studies of Two-Phase Gas-Liquid Flow in Microgravity. Ph.D. Thesis, Dec. 1994

NASA Technical Reports Server (NTRS)

Bousman, William Scott

1995-01-01

Two-phase gas-liquid flows are expected to occur in many future space operations. Due to a lack of buoyancy in the microgravity environment, two-phase flows are known to behave differently than those in earth gravity. Despite these concerns, little research has been conducted on microgravity two-phase flow and the current understanding is poor. This dissertation describes an experimental and modeling study of the characteristics of two-phase flows in microgravity. An experiment was operated onboard NASA aircraft capable of producing short periods of microgravity. In addition to high speed photographs of the flows, electronic measurements of void fraction, liquid film thickness, bubble and wave velocity, pressure drop and wall shear stress were made for a wide range of liquid and gas flow rates. The effects of liquid viscosity, surface tension and tube diameter on the behavior of these flows were also assessed. From the data collected, maps showing the occurrence of various flow patterns as a function of gas and liquid flow rates were constructed. Earth gravity two-phase flow models were compared to the results of the microgravity experiments and in some cases modified. Models were developed to predict the transitions on the flow pattern maps. Three flow patterns, bubble, slug and annular flow, were observed in microgravity. These patterns were found to occur in distinct regions of the gas-liquid flow rate parameter space. The effect of liquid viscosity, surface tension and tube diameter on the location of the boundaries of these regions was small. Void fraction and Weber number transition criteria both produced reasonable transition models. Void fraction and bubble velocity for bubble and slug flows were found to be well described by the Drift-Flux model used to describe such flows in earth gravity. Pressure drop modeling by the homogeneous flow model was inconclusive for bubble and slug flows. Annular flows were found to be complex systems of ring-like waves and a substrate film. Pressure drop was best fitted with the Lockhart- Martinelli model. Force balances suggest that droplet entrainment may be a large component of the total pressure drop.

Gas transport and vesicularity in low-viscosity liquids

NASA Astrophysics Data System (ADS)

Pioli, Laura; Bonadonna, Costanza; Abdulkareem, Lokman; Azzopardi, Barry; Phillips, Jeremy

2010-05-01

Vesicle textures of basaltic scoria preserve information on magma bubble content at fragmentation and are commonly used to constrain degassing, vesiculation and magma permeability. These studies are based on the assumption that microscale textures are representative of the conduit-scale structures and processes. However, the conditions for which this assumption is valid have not been investigated in detail. We have investigated conduit-scale structures by performing a series of experiments of separate two-phase flows in a 6.5-m high cylindrical bubble column using a combination of air with pure glucose syrup, water-syrup mixtures and pure water to reproduce open-system degassing and strombolian activity conditions in the upper volcanic conduit (i.e. at very low or zero liquid fluxes). We have varied gas fluxes, initial liquid height, gas inlet configuration and liquid viscosity and analyzed flow regimes and properties. Temperature and pressure were measured at several heights along the pipe and vesicularity was calculated using pressure data, liquid level measurements and an Electrical Capacitance tomography (ECT) system, which measures instantaneous vesicularity and phase distribution from capacitance measurements between pairs of electrodes placed uniformly around the pipe circumference. The aim of the experiments was to identify the effect of gas-flow rates on the flow regimes (i.e. bubbly, slug, churn and annular), the main degassing structures and the total gas content of the column. The effect of increasing and decreasing gas flow rates was also studied to check hysteresis effects. Results indicate that the vesicularity of the liquid column depends primarily on gas flux, whereas flow regimes exert a minor control. In fact, vesicularity increases with gas flux following a power-law trend whose exponent depends on the viscosity of the liquid. In addition, distributions of instantaneous gas fraction in the column cross section during syrup experiments have shown that gas is mainly transported by large, conduit-size bubbles rising in a microvesicular liquid. Coalescence processes occur throughout the whole column, and are strongly affected by bubble size, shearing and flow dynamics. Increasing gas fluxes increases frequency and length of the large bubbles but does not affect the concentration of small bubbles in the liquid matrix. Scaling of these experiments suggest that these conditions could be met in low viscosity, crystal-poor magmas and we therefore suggest that this dynamics could also characterize two-phase flow in open conduit mafic systems.

ISM stripping from cluster galaxies and inhomogeneities in cooling flows

NASA Technical Reports Server (NTRS)

Soker, Noam; Bregman, Joel N.; Sarazin, Craig L.

1990-01-01

Analyses of the x ray surface brightness profiles of cluster cooling flows suggest that the mass flow rate decreases towards the center of the cluster. It is often suggested that this decrease results from thermal instabilities, in which denser blobs of gas cool rapidly and drop below x ray emitting temperatures. If the seeds for the thermal instabilities are entropy perturbations, these perturbations must enter the flow already in the nonlinear regime. Otherwise, the blobs would take too long to cool. Here, researchers suggest that such nonlinear perturbations might start as blobs of interstellar gas which are stripped out of cluster galaxies. Assuming that most of the gas produced by stellar mass loss in cluster galaxies is stripped from the galaxies, the total rate of such stripping is roughly M sub Interstellar Matter (ISM) approx. 100 solar mass yr(-1). It is interesting that the typical rates of cooling in cluster cooling flows are M sub cool approx. 100 solar mass yr(-1). Thus, it is possible that a substantial portion of the cooling gas originates as blobs of interstellar gas stripped from galaxies. The magnetic fields within and outside of the low entropy perturbations can help to maintain their identities, both by suppressing thermal conduction and through the dynamical effects of magnetic tension. One significant question concerning this scenario is: Why are cooling flows seen only in a fraction of clusters, although one would expect gas stripping to be very common. It may be that the density perturbations only survive and cool efficiently in clusters with a very high intracluster gas density and with the focusing effect of a central dominant galaxy. Inhomogeneities in the intracluster medium caused by the stripping of interstellar gas from galaxies can have a number of other effects on clusters. For example, these density fluctuations may disrupt the propagation of radio jets through the intracluster gas, and this may be one mechanism for producing Wide-Angle-Tail radio galaxies.

Shock-wave flow regimes at entry into the diffuser of a hypersonic ramjet engine: Influence of physical properties of the gas medium

NASA Astrophysics Data System (ADS)

Tarnavskii, G. A.

2006-07-01

The physical aspects of the effective-adiabatic-exponent model making it possible to decompose the total problem on modeling of high-velocity gas flows into individual subproblems (“physicochemical processes” and “ aeromechanics”), which ensures the creation of a universal and efficient computer complex divided into a number of independent units, have been analyzed. Shock-wave structures appearing at entry into the duct of a hypersonic aircraft have been investigated based on this methodology, and the influence of the physical properties of the gas medium in a wide range of variations of the effective adiabatic exponent has been studied.

Closed-cycle 1-kHz-pulse-repetition-frequency HF(DF) laser

NASA Astrophysics Data System (ADS)

Harris, Michael R.; Morris, A. V.; Gorton, Eric K.

1998-05-01

We describe the design and performance of a closed cycle, high pulse repetition frequency HF(DF) laser. A short duration, glow discharge is formed in a 10 SF6:1 H2(D2) gas mixture at a total pressure of approximately 110 torr. A pair of profiled electrodes define a 15 X 0.5 X 0.5 cm3 discharge volume through which gas flow is forced in the direction transverse to the optical axis. A centrifugal fan provides adequate gas flow to enable operation up to 3 kHz repetition frequency. The fan also passes the gas through a scrubber cell in which ground state HF(DF) is eliminated from the gas stream. An automated gas make-up system replenishes the spent fuel gases removed by the scrubber. Total gas admission is regulated by monitoring the system pressure, whilst the correct fuel balance is maintained through measurement of the discharge voltage. The HF(DF) generation rate is determined to be close to 5 X 1019 molecules per second per watt of laser output. Typical mean laser output powers of up to 3 watts can be delivered for extended periods of time. The primary limitation to life is found to be the discharge pre- ionization system. A distributed resistance corona pre- ionizer is shown to be advantageous when compared with an alternative arc array scheme.

Multibreath alveolar oxygen tension imaging.

PubMed

Clapp, Justin; Hamedani, Hooman; Kadlecek, Stephen; Xin, Yi; Shaghaghi, Hoora; Siddiqui, Sarmad; Rossman, Milton D; Rizi, Rahim R

2016-10-01

This study tested the ability of a multibreath hyperpolarized HP (3) He MRI protocol to increase the accuracy of regional alveolar oxygen tension (PA O2 ) measurements by lessening the influence of gas-flow artifacts. Conventional single-breath PA O2 measurement has been susceptible to error induced by intervoxel gas flow, particularly when used to study subjects with moderate-to-severe chronic obstructive pulmonary disease (COPD). Both single-breath and multibreath PA O2 imaging schemes were implemented in seven human subjects (one healthy, three asymptomatic smokers, and three COPD). The number and location of voxels with nonphysiologic PA O2 values generated by intervoxel gas flow were compared between the two protocols. The multibreath scheme resulted in a significantly lower total percentage of nonphysiologic PA O2 values (6.0%) than the single-breath scheme (13.7%) (P = 0.006). PA O2 maps showed several patterns of gas-flow artifacts that were present in the single-breath protocol but mitigated by the multibreath approach. Multibreath imaging also allowed for the analysis of slow-filling areas that presented no signal after a single breath. A multibreath approach enhances the accuracy and completeness of noninvasive PA O2 measurement by significantly lessening the proportion of nonphysiologic values generated by intervoxel gas flow. Magn Reson Med 76:1092-1101, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

Effects of Nonequilibrium Chemistry and Darcy-Forchheimer Pyrolysis Flow for Charring Ablator

NASA Technical Reports Server (NTRS)

Chen, Yih-Kanq; Milos, Frank S.

2013-01-01

The fully implicit ablation and thermal response code simulates pyrolysis and ablation of thermal protection materials and systems. The governing equations, which include energy conservation, a three-component decomposition model, and a surface energy balance, are solved with a moving grid.This work describes new modeling capabilities that are added to a special version of code. These capabilities include a time-dependent pyrolysis gas flow momentum equation with Darcy-Forchheimer terms and pyrolysis gas species conservation equations with finite rate homogeneous chemical reactions. The total energy conservation equation is also enhanced for consistency with these new additions. Two groups of parametric studies of the phenolic impregnated carbon ablator are performed. In the first group, an Orion flight environment for a proposed lunar-return trajectory is considered. In the second group, various test conditions for arcjet models are examined. The central focus of these parametric studies is to understand the effect of pyrolysis gas momentum transfer on material in-depth thermal responses with finite-rate, equilibrium, or frozen homogeneous gas chemistry. Results indicate that the presence of chemical nonequilibrium pyrolysis gas flow does not significantly alter the in-depth thermal response performance predicted using the chemical equilibrium gas model.

Are high flow nasal cannulae noisier than bubble CPAP for preterm infants?

PubMed

Roberts, C T; Dawson, J A; Alquoka, E; Carew, P J; Donath, S M; Davis, P G; Manley, B J

2014-07-01

Noise exposure in the neonatal intensive care unit is believed to be a risk factor for hearing loss in preterm neonates. Continuous positive airway pressure (CPAP) devices exceed recommended noise levels. High flow nasal cannulae (HFNC) are an increasingly popular alternative to CPAP for treating preterm infants, but there are no in vivo studies assessing noise production by HFNC. To study whether HFNC are noisier than bubble CPAP (BCPAP) for preterm infants. An observational study of preterm infants receiving HFNC or BCPAP. Noise levels within the external auditory meatus (EAM) were measured using a microphone probe tube connected to a calibrated digital dosimeter. Noise was measured across a range of frequencies and reported as decibels A-weighted (dBA). A total of 21 HFNC and 13 BCPAP noise measurements were performed in 21 infants. HFNC gas flows were 2-5 L/min, and BCPAP gas flows were 6-10 L/min with set pressures of 5-7 cm of water. There was no evidence of a difference in average noise levels measured at the EAM: mean difference (95% CI) of -1.6 (-4.0 to 0.9) dBA for HFNC compared to BCPAP. At low frequency (500 Hz), HFNC was mean (95% CI) 3.0 (0.3 to 5.7) dBA quieter than BCPAP. Noise increased with increasing BCPAP gas flow (p=0.007), but not with increasing set pressure. There was a trend to noise increasing with increasing HFNC gas flows. At the gas flows studied, HFNC are not noisier than BCPAP for preterm infants.

Analytical performance of a low-gas-flow torch optimized for inductively coupled plasma atomic emission spectrometry

USGS Publications Warehouse

Montaser, A.; Huse, G.R.; Wax, R.A.; Chan, S.-K.; Golightly, D.W.; Kane, J.S.; Dorrzapf, A.F.

1984-01-01

An inductively coupled Ar plasma (ICP), generated in a lowflow torch, was investigated by the simplex optimization technique for simultaneous, multielement, atomic emission spectrometry (AES). The variables studied included forward power, observation height, gas flow (outer, intermediate, and nebulizer carrier) and sample uptake rate. When the ICP was operated at 720-W forward power with a total gas flow of 5 L/min, the signal-to-background ratios (S/B) of spectral lines from 20 elements were either comparable or inferior, by a factor ranging from 1.5 to 2, to the results obtained from a conventional Ar ICP. Matrix effect studies on the Ca-PO4 system revealed that the plasma generated in the low-flow torch was as free of vaporizatton-atomizatton interferences as the conventional ICP, but easily ionizable elements produced a greater level of suppression or enhancement effects which could be reduced at higher forward powers. Electron number densities, as determined via the series until line merging technique, were tower ht the plasma sustained in the low-flow torch as compared with the conventional ICP. ?? 1984 American Chemical Society.

Generalization of turbojet and turbine-propeller engine performance in windmilling condition

NASA Technical Reports Server (NTRS)

Wallner, Ewis E; Welna, Henry J

1951-01-01

Windmilling characteristics of several turbojet and turbine-propeller engines were investigated individually over a wide range of flight conditions in the NACA Lewis altitude wind tunnel. A study was made of all these data and windmilling performance of gas turbine engines was generalized. Although internal-drag, air-flow, and total-pressure-drop parameters were generalized to a single curve for both the axial-flow type engines and another for the centrifugal-flow engine. The engine speed, component pressure changes, and windmilling-propeller drag were generalized to single curves for the two turbine-propeller-type engines investigated. By the use of these curves the windmilling performance can be estimated for axial-flow type gas turbine engines similar to the types investigated over a wide range of flight conditions.

40 CFR Figure 1 to Subpart G of... - Definitions of Terms Used in Wastewater Equations

Code of Federal Regulations, 2010 CFR

2010-07-01

... wastewater, ppmw. CG=Concentration of TOC (minus methane and ethane) or total organic hazardous air pollutants, in vented gas stream, dry basis, ppmv. CGc=Concentration of TOC or organic hazardous air... flow rate of vented gas stream, dry standard, m3/min. QMG=Mass flowrate of TOC (minus methane and...

A computational study of the flowfield surrounding the Aeroassist Flight Experiment vehicle

NASA Technical Reports Server (NTRS)

Gnoffo, Peter A.; Greene, Francis A.

1987-01-01

A symmetric total variation diminishing (STVD) algorithm has been applied to the solution of the three-dimensional hypersonic flowfield surrounding the Aeroassist Flight Experiment (AFE) vehicle. Both perfect-gas and chemical nonequilibrium models have been used. The perfect-gas flows were computed at two different Reynolds numbers, including a flight trajectory point at maximum dynamic pressure, and on two different grids. Procedures for coupling the solution of the species continuity equations with the Navier-Stokes equations in the presence of chemical nonequilibrium are reviewed and tested on the forebody of the AFE and on the complete flowfield assuming noncatalytic wall and no species diffusion. Problems with the STVD algorithm unique to flows with variable thermodynamic properties (real gas) are identified and algorithm modifications are suggested. A potential heating problem caused by strong flow impingement on the nozzle lip in the near wake at 0-deg angle of attack has been identified.

Total dissolved gas, barometric pressure, and water temperature data, lower Columbia River, Oregon and Washington, 1996

USGS Publications Warehouse

Tanner, Dwight Q.; Harrison, Howard E.; McKenzie, Stuart W.

1996-01-01

Increased levels of total dissolved gas pressure can cause gas-bubble trauma in fish downstream from dams on the Columbia River. In cooperation with the U.S. Army Corps of Engineers, the U.S. Geological Survey collected data on total dissolved gas pressure, barometric pressure, water temperature, and dissolved oxygen pressure at 11 stations on the lower Columbia River from the John Day forebay (river mile 215.6) to Wauna Mill (river mile 41.9) from March to September 1996. Methods of data collection, review, and processing are described in this report. Summaries of daily minimum, maximum, and mean hourly values are presented for total dissolved gas pressure, barometric pressure, and water temperature. Hourly values for these parameters are presented graphically. Dissolved oxygen data are not presented in this report because the quality-control data show that the data have poor precision and high bias. Suggested changes to monitoring procedures for future studies include (1) improved calibration procedures for total dissolved gas and dissolved oxygen to better define accuracy at elevated levels of supersaturation and (2) equipping dissolved oxygen sensors with stirrers because river velocities at the shoreline monitoring stations probably cannot maintain an adequate flow of water across the membrane surface of the dissolved oxygen sensor.

Quantifying the flow rate of the Deepwater Horizon Macondo Well oil spill

NASA Astrophysics Data System (ADS)

Camilli, R.; Bowen, A.; Yoerger, D. R.; Whitcomb, L. L.; Techet, A. H.; Reddy, C. M.; Sylva, S.; Seewald, J.; di Iorio, D.; Whoi Flow Rate Measurement Group

2010-12-01

The Deepwater Horizon blowout in the Mississippi Canyon block 252 of the Gulf of Mexico created the largest recorded offshore oil spill. The well outflow’s multiple leak sources, turbulent multiphase flow, tendency for hydrate formation, and extreme source depth of 1500 m below the sea surface complicated the quantitative estimation of oil and gas leakage rates. We present methods and results from a U.S. Coast Guard sponsored flow assessment study of the Deepwater Horizon’s damaged blow out preventer and riser. This study utilized a remotely operated vehicle equipped with in-situ acoustic sensors (a Doppler sonar and an imaging multibeam sonar) and isobaric gas-tight fluid samplers to measure directly outflow from the damaged well. Findings from this study indicate oil release rates and total release volume estimates that corroborate estimates made by the federal government’s Flow Rate Technical Group using non-acoustic techniques. The acoustic survey methods reported here provides a means for estimating fluid flow rates in subsurface environments, and are potentially useful for a diverse range of oceanographic applications. Photograph of the Discoverer Enterprise burning natural gas collected from the Macondo well blowout preventer during flow measurement operations. Copyright Wood Hole Oceanographic Institution.

Gas-kinetic unified algorithm for hypersonic flows covering various flow regimes solving Boltzmann model equation in nonequilibrium effect

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

Li, Zhihui; Ma, Qiang; Wu, Junlin

2014-12-09

Based on the Gas-Kinetic Unified Algorithm (GKUA) directly solving the Boltzmann model equation, the effect of rotational non-equilibrium is investigated recurring to the kinetic Rykov model with relaxation property of rotational degrees of freedom. The spin movement of diatomic molecule is described by moment of inertia, and the conservation of total angle momentum is taken as a new Boltzmann collision invariant. The molecular velocity distribution function is integrated by the weight factor on the internal energy, and the closed system of two kinetic controlling equations is obtained with inelastic and elastic collisions. The optimization selection technique of discrete velocity ordinatemore » points and numerical quadrature rules for macroscopic flow variables with dynamic updating evolvement are developed to simulate hypersonic flows, and the gas-kinetic numerical scheme is constructed to capture the time evolution of the discretized velocity distribution functions. The gas-kinetic boundary conditions in thermodynamic non-equilibrium and numerical procedures are studied and implemented by directly acting on the velocity distribution function, and then the unified algorithm of Boltzmann model equation involving non-equilibrium effect is presented for the whole range of flow regimes. The hypersonic flows involving non-equilibrium effect are numerically simulated including the inner flows of shock wave structures in nitrogen with different Mach numbers of 1.5-Ma-25, the planar ramp flow with the whole range of Knudsen numbers of 0.0009-Kn-10 and the three-dimensional re-entering flows around tine double-cone body.« less

Malignant human cell transformation of Marcellus shale gas drilling flow back water

PubMed Central

Yao, Yixin; Chen, Tingting; Shen, Steven S.; Niu, Yingmei; DesMarais, Thomas L; Linn, Reka; Saunders, Eric; Fan, Zhihua; Lioy, Paul; Kluz, Thomas; Chen, Lung-Chi; Wu, Zhuangchun; Costa, Max

2015-01-01

The rapid development of high-volume horizontal hydraulic fracturing for mining natural gas from shale has posed potential impacts on human health and biodiversity. The produced flow back waters after hydraulic stimulation is known to carry high levels of saline and total dissolved solids. To understand the toxicity and potential carcinogenic effects of these waste waters, flow back water from five Marcellus hydraulic fracturing oil and gas wells were analyzed. The physicochemical nature of these samples was analyzed by inductively coupled plasma mass spectrometry and scanning electron microscopy / energy dispersive X-ray spectroscopy. A cytotoxicity study using colony formation as the endpoint was carried out to define the LC50 values of test samples using human bronchial epithelial cells (BEAS-2B). The BEAS-2B cell transformation assay was employed to assess the carcinogenic potential of the samples. Barium and strontium were among the most abundant metals in these samples and the same metals were found elevated in BEAS-2B cells after long-term treatment. BEAS-2B cells treated for 6 weeks with flow back waters produced colony formation in soft agar that was concentration dependant. In addition, flow back water-transformed BEAS-2B cells show a better migration capability when compared to control cells. This study provides information needed to assess the potential health impact of post-hydraulic fracturing flow back waters from Marcellus Shale natural gas mining. PMID:26210350

Measurement of trace impurities in ultra pure hydrogen and deuterium at the parts-per-billion level using gas chromatography

NASA Astrophysics Data System (ADS)

Ganzha, V.; Ivshin, K.; Kammel, P.; Kravchenko, P.; Kravtsov, P.; Petitjean, C.; Trofimov, V.; Vasilyev, A.; Vorobyov, A.; Vznuzdaev, M.; Wauters, F.

2018-02-01

A series of muon experiments at the Paul Scherrer Institute in Switzerland deploy ultra-pure hydrogen active targets. A new gas impurity analysis technique was developed, based on conventional gas chromatography, with the capability to measure part-per-billion (ppb) traces of nitrogen and oxygen in hydrogen and deuterium. Key ingredients are a cryogenic admixture accumulation, a directly connected sampling system and a dedicated calibration setup. The dependence of the measured concentration on the sample volume was investigated, confirming that all impurities from the sample gas are collected in the accumulation column and measured with the gas chromatograph. The system was calibrated utilizing dynamic dilution of admixtures into the gas flow down to sub-ppb level concentrations. The total amount of impurities accumulated in the purification system during a three month long experimental run was measured and agreed well with the calculated amount based on the measured concentrations in the flow.

Controlling autonomous underwater floating platforms using bacterial fermentation.

PubMed

Biffinger, Justin C; Fitzgerald, Lisa A; Howard, Erinn C; Petersen, Emily R; Fulmer, Preston A; Wu, Peter K; Ringeisen, Bradley R

2013-01-01

Biogenic gas has a wide range of energy applications from being used as a source for crude bio-oil components to direct ignition for heating. The current study describes the use of biogenic gases from Clostridium acetobutylicum for a new application-renewable ballast regeneration for autonomous underwater devices. Uninterrupted (continuous) and blocked flow (pressurization) experiments were performed to determine the overall biogas composition and total volume generated from a semirigid gelatinous matrix. For stopped flow experiments, C. acetobutylicum generated a maximum pressure of 55 psi over 48 h composed of 60 % hydrogen gas when inoculated in a 5 % agar (w/v) support with 5 % glucose (w/v) in the matrix. Typical pressures over 24 h at 318 K ranged from 10 to 33 psi. These blocked flow experiments show for the first time the use of microbial gas production as a way to repressurize gas cylinders. Continuous flow experiments successfully demonstrated how to deliver biogas to an open ballast control configuration for deployable underwater platforms. This study is a starting point for engineering and microbiology investigations of biogas which will advance the integration of biology within autonomous systems.

Mass spectrometric measurements of driver gas arrival in the T4 free-piston shock-tunnel

NASA Astrophysics Data System (ADS)

Boyce, R. R.; Takahashi, M.; Stalker, R. J.

2005-12-01

Available test time is an important issue for ground-based flow research, particularly for impulse facilities such as shock tunnels, where test times of the order of several ms are typical. The early contamination of the test flow by the driver gas in such tunnels restricts the test time. This paper reports measurements of the driver gas arrival time in the test section of the T4 free-piston shock-tunnel over the total enthalpy range 3 17 MJ/kg, using a time-of-flight mass spectrometer. The results confirm measurements made by previous investigators using a choked duct driver gas detector at these conditions, and extend the range of previous mass spectrometer measurements to that of 3 20 MJ/kg. Comparisons of the contamination behaviour of various piston-driven reflected shock tunnels are also made.

Parametric analyses of planned flowing uranium hexafluoride critical experiments

NASA Technical Reports Server (NTRS)

Rodgers, R. J.; Latham, T. S.

1976-01-01

Analytical investigations were conducted to determine preliminary design and operating characteristics of flowing uranium hexafluoride (UF6) gaseous nuclear reactor experiments in which a hybrid core configuration comprised of UF6 gas and a region of solid fuel will be employed. The investigations are part of a planned program to perform a series of experiments of increasing performance, culminating in an approximately 5 MW fissioning uranium plasma experiment. A preliminary design is described for an argon buffer gas confined, UF6 flow loop system for future use in flowing critical experiments. Initial calculations to estimate the operating characteristics of the gaseous fissioning UF6 in a confined flow test at a pressure of 4 atm, indicate temperature increases of approximately 100 and 1000 K in the UF6 may be obtained for total test power levels of 100 kW and 1 MW for test times of 320 and 32 sec, respectively.

Amplification, attenuation, and dispersion of sound in inhomogeneous flows

NASA Technical Reports Server (NTRS)

Kentzer, C. P.

1975-01-01

First order effects of gradients in nonuniform potential flows of a compressible gas are included in a dispersion relation for sound waves. Three nondimensional numbers, the ratio of the change in the kinetic energy in one wavelength to the thermal energy of the gas, the ratio of the change in the total energy in one wavelength to the thermal energy, and the ratio of the dillatation frequency (the rate of expansion per unit volume) to the acoustic frequency, play a role in the separation of the effects of flow gradients into isotropic and anisotropic effects. Dispersion and attenuation (or amplification) of sound are found to be proportional to the wavelength for small wavelength, and depend on the direction of wave propagation relative to flow gradients. Modification of ray acoustics for the effects of flow gradients is suggested, and conditions for amplification and attenuation of sound are discussed.

AEROSOL NUCLEATION AND GROWTH DURING LAMINAR TUBE FLOW: MAXIMUM SATURATIONS AND NUCLEATION RATES. (R827354C008)

EPA Science Inventory

An approximate method of estimating the maximum saturation, the nucleation rate, and the total number nucleated per second during the laminar flow of a hot vapour–gas mixture along a tube with cold walls is described. The basis of the approach is that the temperature an...

Molecular Rayleigh Scattering Diagnostic for Measurement of High Frequency Temperature Fluctuations

NASA Technical Reports Server (NTRS)

Mielke, Amy F.; Elam, Kristie A.

2005-01-01

A novel technique for measurement of high frequency temperature fluctuations in unseeded gas flows using molecular Rayleigh scattering is investigated. The spectrum of laser light scattered from molecules in a gas flow is resolved using a Fabry-Perot interferometer. The width of the spectral peak is broadened by thermal motion of the molecules and hence is related to gas temperature. The interference fringe pattern containing spectral information is divided into four concentric regions using a series of mirrors angled with respect to one another. Light from each of these regions is directed towards photomultiplier tubes and sampled at 10 kHz using photon counting electronics. Monitoring the relative change in intensity within each region allows measurement of gas temperature. Independently monitoring the total scattered intensity provides a measure of gas density. This technique also has the potential to simultaneously measure a single component of flow velocity by monitoring the spectral peak location. Measurements of gas temperature and density are demonstrated using a low speed heated air jet surrounded by an unheated air co-flow. Mean values of temperature and density are shown for radial scans across the jet flow at a fixed axial distance from the jet exit plane. Power spectra of temperature and density fluctuations at several locations in the jet are also shown. The instantaneous measurements have fairly high uncertainty; however, long data records provide highly accurate statistically quantities, which include power spectra. Mean temperatures are compared with thermocouple measurements as well as the temperatures derived from independent density measurements. The accuracy for mean temperature measurements was +/- 7 K.

Malignant human cell transformation of Marcellus Shale gas drilling flow back water

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

Yao, Yixin; Department of Environmental Medicine, New York University School of Medicine, Tuxedo, NY 10987; Chen, Tingting

The rapid development of high-volume horizontal hydraulic fracturing for mining natural gas from shale has posed potential impacts on human health and biodiversity. The produced flow back waters after hydraulic stimulation are known to carry high levels of saline and total dissolved solids. To understand the toxicity and potential carcinogenic effects of these wastewaters, flow back waters from five Marcellus hydraulic fracturing oil and gas wells were analyzed. The physicochemical nature of these samples was analyzed by inductively coupled plasma mass spectrometry and scanning electron microscopy/energy dispersive X-ray spectroscopy. A cytotoxicity study using colony formation as the endpoint was carriedmore » out to define the LC{sub 50} values of test samples using human bronchial epithelial cells (BEAS-2B). The BEAS-2B cell transformation assay was employed to assess the carcinogenic potential of the samples. Barium and strontium were among the most abundant metals in these samples and the same metals were found to be elevated in BEAS-2B cells after long-term treatment. BEAS-2B cells treated for 6 weeks with flow back waters produced colony formation in soft agar that was concentration dependent. In addition, flow back water-transformed BEAS-2B cells show better migration capability when compared to control cells. This study provides information needed to assess the potential health impact of post-hydraulic fracturing flow back waters from Marcellus Shale natural gas mining. - Highlights: • This is the first report of potential cytotoxicity and transforming activity of Marcellus shale gas mining flow back to mammalian cells. • Barium and Strontium were elevated in flow back water exposed cells. • Flow back water malignantly transformed cells and formed tumor in athymic nude mice. • Flow back transformed cells exhibited altered transcriptome with dysregulated cell migration pathway and adherent junction pathway.« less

Multicomponent Gas Diffusion and an Appropriate Momentum Boundary Condition

NASA Technical Reports Server (NTRS)

Noever, David A.

1994-01-01

Multicomponent gas diffusion is reviewed with particular emphasis on gas flows near solid boundaries-the so-called Kramers-Kistemaker effect. The aim is to derive an appropriate momentum boundary condition which governs many gaseous species diffusing together. The many species' generalization of the traditional single gas condition, either as slip or stick (no-slip), is not obvious, particularly for technologically important cases of lower gas pressures and very dissimilar molecular weight gases. No convincing theoretical case exists for why two gases should interact with solid boundaries equally but in opposite flow directions, such that the total gas flow exactly vanishes. ln this way, the multicomponent no-slip boundary requires careful treatment The approaches discussed here generally adopt a microscopic model for gas-solid contact. The method has the advantage that the mathematics remain tractable and hence experimentally testable. Two new proposals are put forward, the first building in some molecular collision physics, the second drawing on a detailed view of surface diffusion which does not unphysically extrapolate bulk gas properties to govern the adsorbed molecules. The outcome is a better accounting of previously anomalous experiments. Models predict novel slip conditions appearing even for the case of equal molecular weight components. These approaches become particularly significant in view of a conceptual contradiction found to arise in previous derivations of the appropriate boundary conditions. The analogous case of three gases, one of which is uniformly distributed and hence non-diffusing, presents a further refinement which gives unexpected flow reversals near solid boundaries. This case is investigated alone and for aggregating gas species near their condensation point. In addition to predicting new physics, this investigation carries practical implications for controlling vapor diffusion in the growth of crystals used in medical diagnosis (e.g. mercuric iodide) and semiconductors.

Control of Cr6+ emissions from gas metal arc welding using a silica precursor as a shielding gas additive.

PubMed

Topham, Nathan; Wang, Jun; Kalivoda, Mark; Huang, Joyce; Yu, Kuei-Min; Hsu, Yu-Mei; Wu, Chang-Yu; Oh, Sewon; Cho, Kuk; Paulson, Kathleen

2012-03-01

Hexavalent chromium (Cr(6+)) emitted from welding poses serious health risks to workers exposed to welding fumes. In this study, tetramethylsilane (TMS) was added to shielding gas to control hazardous air pollutants produced during stainless steel welding. The silica precursor acted as an oxidation inhibitor when it decomposed in the high-temperature welding arc, limiting Cr(6+) formation. Additionally, a film of amorphous SiO(2) was deposited on fume particles to insulate them from oxidation. Experiments were conducted following the American Welding Society (AWS) method for fume generation and sampling in an AWS fume hood. The results showed that total shielding gas flow rate impacted the effectiveness of the TMS process. Increasing shielding gas flow rate led to increased reductions in Cr(6+) concentration when TMS was used. When 4.2% of a 30-lpm shielding gas flow was used as TMS carrier gas, Cr(6+) concentration in gas metal arc welding (GMAW) fumes was reduced to below the 2006 Occupational Safety and Health Administration standard (5 μg m(-3)) and the efficiency was >90%. The process also increased fume particle size from a mode size of 20 nm under baseline conditions to 180-300 nm when TMS was added in all shielding gas flow rates tested. SiO(2) particles formed in the process scavenged nanosized fume particles through intercoagulation. Transmission electron microscopy imagery provided visual evidence of an amorphous film of SiO(2) on some fume particles along with the presence of amorphous SiO(2) agglomerates. These results demonstrate the ability of vapor phase silica precursors to increase welding fume particle size and minimize chromium oxidation, thereby preventing the formation of hexavalent chromium.

Design and performance of the Ames electric-arc shock tunnel

NASA Technical Reports Server (NTRS)

Reller, J. O., Jr.

1973-01-01

A high enthalpy shock tunnel using arc-heated helium as the driver gas was designed for gas dynamic research at total stream energies from 7,000 to 35,000 j/g. The arc driver was found to be a relatively efficient energy converter. Tailored shock Mach numbers from 11.5 to 14.6 in air were demonstrated. A nozzle calibration with a total stream enthalpy of 18,600 j/g of air gave test times of 1.5 to 2.0 m sec at flow Mach numbers from 16 to 24.

Cold-air performance of compressor-drive turbine of Department of Energy upgraded automobile gas turbine engine. 1: Volute-manifold and stator performance

NASA Technical Reports Server (NTRS)

Roelke, R. J.; Haas, J. E.

1981-01-01

The aerodynamic performance of the inlet manifold and stator assembly of the compressor drive turbine was experimentally determined with cold air as the working fluid. The investigation included measurements of mass flow and stator-exit fluid torque as well as radial surveys of total pressure and flow angle at the stator inlet and annulus surveys of total pressure and flow angle at the stator exit. The stator-exit aftermixed flow conditions and overall stator efficiency were obtained and compared with their design values and the experimental results from three other stators. In addition, an analysis was made to determine the constituent aerodynamic losses that made up the stator kinetic energy loss.

Comparing the efficiency of supersonic oxygen-iodine laser with different mixing designs

NASA Astrophysics Data System (ADS)

Vyskubenko, Boris A.; Adamenkov, A. A.; Bakshin, V. V.; Efremov, V. I.; Ilyin, S. P.; Kolobyanin, Yu. V.; Krukovsky, I. M.; Kudryashov, E. A.; Moiseyev, V. B.

2003-11-01

The paper presents experimental studies of supersonic oxygen-iodine laser (OIL) using twisted-flow singlet oxygen generator (SOG) over a wide range of the singlet oxygen pressures and the buffer gas flow rates. The experiments used different designs of the nozzle unit and mixing system for singlet oxygen and iodine gas with the carrier gas (such as nitrogen or helium). For a wide range of the key parameters, the study looked at the efficiency of supersonic OIL with variation of the singlet oxygen pressure. The measurements were made for different positions of the iodine injection plane with respect to the critical cross-section (both in the subsonic part of the nozzle and in the supersonic flow). The gas pressure at the nozzle unit entry was varied from 50 to 250 Torr. The total pressure loss have been found for different mixing designs. Experimental curves are given for energy performance and chemical efficiency of the supersonic OIL as a function of the key parameters. Comparison is made between the calculated and experimental data. For the optimum conditions of OIL operation, chemical efficiency of 25-30% has been achieved.

Reproducible direct exposure environmental testing of metal-based magnetic media

NASA Technical Reports Server (NTRS)

Sides, Paul J.

1994-01-01

A flow geometry and flow rate for mixed flowing gas testing is proposed. Use of an impinging jet of humid polluted air can provide a uniform and reproducible exposure of coupons of metal-based magnetic media. Numerical analysis of the fluid flow and mass transfer in such as system has shown that samples confined within a distance equal to the nozzle radius on the surface of impingement are uniformly accessible to pollutants in the impinging gas phase. The critical factor is the nozzle height above the surface of impingement. In particular, the uniformity of exposure is less than plus/minus 2% for a volumetric flow rate of 1600 cm(exp 3)/minute total flow with the following specifications: For a one inch nozzle, the height of the nozzle opening above the stage should be 0.177 inches; for a 2 inch nozzle - 0.390 inches. Not only is the distribution uniform, but one can calculate the maximum delivery rate of pollutants to the samples for comparison with the observed deterioration.

24th International Symposium on Ballistics

DTIC Science & Technology

2008-09-26

production Samples dimensions were 0.3x0.05 m. Test set up Gas gun 5.5 mm diameter steel spheres and sabot Velocity measuring  systems High speed rate...Oilwell perforators – small caliber shaped charges – create the pathway for oil or gas to flow from the reservoir rock into the wellbore  Deep, clean ...overburden, tectonic) – Pore fluid pressure – Pore fluid type ( liquid vs. gas ) Background  Geomechanics considerations: – In-situ stresses (“total

Risks incurred by hydrogen escaping from containers and conduits

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

Swain, M.R.; Grilliot, E.S.

1998-08-01

This paper is a discussion of a method for hydrogen leak classification. Leaks are classified as; gas escapes into enclosed spaces, gas escapes into partially enclosed spaces (vented), and gas escapes into unenclosed spaces. Each of the three enclosure classifications is further divided into two subclasses; total volume of hydrogen escaped and flow rate of escaping hydrogen. A method to aid in risk assessment determination in partially enclosed spaces is proposed and verified for several enclosure geometries. Examples are discussed for additional enclosure geometries.

Noble gas and hydrocarbon tracers in multiphase unconventional hydrocarbon systems: Toward integrated advanced reservoir simulators

NASA Astrophysics Data System (ADS)

Darrah, T.; Moortgat, J.; Poreda, R. J.; Muehlenbachs, K.; Whyte, C. J.

2015-12-01

Although hydrocarbon production from unconventional energy resources has increased dramatically in the last decade, total unconventional oil and gas recovery from black shales is still less than 25% and 9% of the totals in place, respectively. Further, the majority of increased hydrocarbon production results from increasing the lengths of laterals, the number of hydraulic fracturing stages, and the volume of consumptive water usage. These strategies all reduce the economic efficiency of hydrocarbon extraction. The poor recovery statistics result from an insufficient understanding of some of the key physical processes in complex, organic-rich, low porosity formations (e.g., phase behavior, fluid-rock interactions, and flow mechanisms at nano-scale confinement and the role of natural fractures and faults as conduits for flow). Noble gases and other hydrocarbon tracers are capably of recording subsurface fluid-rock interactions on a variety of geological scales (micro-, meso-, to macro-scale) and provide analogs for the movement of hydrocarbons in the subsurface. As such geochemical data enrich the input for the numerical modeling of multi-phase (e.g., oil, gas, and brine) fluid flow in highly heterogeneous, low permeability formations Herein we will present a combination of noble gas (He, Ne, Ar, Kr, and Xe abundances and isotope ratios) and molecular and isotopic hydrocarbon data from a geographically and geologically diverse set of unconventional hydrocarbon reservoirs in North America. Specifically, we will include data from the Marcellus, Utica, Barnett, Eagle Ford, formations and the Illinois basin. Our presentation will include geochemical and geological interpretation and our perspective on the first steps toward building an advanced reservoir simulator for tracer transport in multicomponent multiphase compositional flow (presented separately, in Moortgat et al., 2015).

Impact of Adsorption on Gas Transport in Nanopores.

PubMed

Wu, Tianhao; Zhang, Dongxiao

2016-03-29

Given the complex nature of the interaction between gas and solid atoms, the development of nanoscale science and technology has engendered a need for further understanding of gas transport behavior through nanopores and more tractable models for large-scale simulations. In the present paper, we utilize molecular dynamic simulations to demonstrate the behavior of gas flow under the influence of adsorption in nano-channels consisting of illite and graphene, respectively. The results indicate that velocity oscillation exists along the cross-section of the nano-channel, and the total mass flow could be either enhanced or reduced depending on variations in adsorption under different conditions. The mechanisms can be explained by the extra average perturbation stress arising from density oscillation via the novel perturbation model for micro-scale simulation, and approximated via the novel dual-region model for macro-scale simulation, which leads to a more accurate permeability correction model for industrial applications than is currently available.

Estimating the gas hydrate recovery prospects in the western Black Sea basin based on the 3D multiphase flow of fluid and gas components within highly permeable paleo-channel-levee systems

NASA Astrophysics Data System (ADS)

Burwicz, Ewa; Zander, Timo; Rottke, Wolf; Bialas, Joerg; Hensen, Christian; Atgin, Orhan; Haeckel, Matthias

2017-04-01

Gas hydrate deposits are abundant in the Black Sea region and confirmed by direct observations as well as geophysical evidence, such as continuous bottom simulating reflectors (BSRs). Although those gas hydrate accumulations have been well-studied for almost two decades, the migration pathways of methane that charge the gas hydrate stability zone (GHSZ) in the region are unknown. The aim of this study is to explore the most probable gas migration scenarios within a three-dimensional finite element grid based on seismic surveys and available basin cross-sections. We have used the commercial software PetroMod(TM) (Schlumberger) to perform a set of sensitivity studies that narrow the gap between the wide range of sediment properties affecting the multi-phase flow in porous media. The high-resolution model domain focuses on the Danube deep-sea fan and associated buried sandy channel-levee systems whereas the total extension of the model domain covers a larger area of the western Black Sea basin. Such a large model domain allows for investigating biogenic as well as thermogenic methane generation and a permeability driven migration of the free phase of methane on a basin scale to confirm the hypothesis of efficient methane migration into the gas hydrate reservoir layers by horizontal flow along the carrier beds.

Real-Gas Effects on Binary Mixing Layers

NASA Technical Reports Server (NTRS)

Okong'o, Nora; Bellan, Josette

2003-01-01

This paper presents a computational study of real-gas effects on the mean flow and temporal stability of heptane/nitrogen and oxygen/hydrogen mixing layers at supercritical pressures. These layers consist of two counterflowing free streams of different composition, temperature, and density. As in related prior studies reported in NASA Tech Briefs, the governing conservation equations were the Navier-Stokes equations of compressible flow plus equations for the conservation of total energy and of chemical- species masses. In these equations, the expressions for heat fluxes and chemical-species mass fluxes were derived from fluctuation-dissipation theory and incorporate Soret and Dufour effects. Similarity equations for the streamwise velocity, temperature, and mass fractions were derived as approximations to the governing equations. Similarity profiles showed important real-gas, non-ideal-mixture effects, particularly for temperature, in departing from the error-function profile, which is the similarity solution for incompressible flow. The temperature behavior was attributed to real-gas thermodynamics and variations in Schmidt and Prandtl numbers. Temporal linear inviscid stability analyses were performed using the similarity and error-function profiles as the mean flow. For the similarity profiles, the growth rates were found to be larger and the wavelengths of highest instability shorter, relative to those of the errorfunction profiles and to those obtained from incompressible-flow stability analysis. The range of unstable wavelengths was found to be larger for the similarity profiles than for the error-function profiles

Thermal Analysis of a Carbon Fiber Rope Barrier for Use in the Reusable Solid Rocket Motor Nozzle Joint-2

NASA Technical Reports Server (NTRS)

Clayton, J. Louie

2002-01-01

This study provides development and verification of analysis methods used to assess performance of a carbon fiber rope (CFR) thermal barrier system that is currently being qualified for use in Reusable Solid Rocket Motor (RSRM) nozzle joint-2. Modeled geometry for flow calculations considers the joint to be vented with the porous CFR barriers placed in the 'open' assembly gap. Model development is based on a 1-D volume filling approach where flow resistances (assembly gap and CFRs) are defined by serially connected internal flow and the porous media 'Darcy' relationships. Combustion gas flow rates are computed using the volume filling code by assuming a lumped distribution total joint fill volume on a per linear circumferential inch basis. Gas compressibility, friction and heat transfer are included in the modeling. Gas-to-wall heat transfer is simulated by concurrent solution of the compressible flow equations and a large thermal 2-D finite element (FE) conduction grid. The derived numerical technique loosely couples the FE conduction matrix with the compressible gas flow equations. Free constants that appear in the governing equations are calibrated by parametric model comparison to hot fire subscale test results. The calibrated model is then used to make full-scale motor predictions using RSRM aft dome environments. Model results indicate that CFR thermal barrier systems will provide a thermally benign and controlled pressurization environment for the RSRM nozzle joint-2 primary seal activation.

Thermal Analysis of a Carbon Fiber Rope Barrier for Use in the Reusable Solid Rocket Motor Nozzle Joint-2

NASA Technical Reports Server (NTRS)

Clayton, J. Louie; Phelps, Lisa (Technical Monitor)

2001-01-01

This study provides for development and verification of analysis methods used to assess performance of a carbon fiber rope (CFR) thermal barrier system that is currently being qualified for use in Reusable Solid Rocket Motor (RSRM) nozzle joint-2. Modeled geometry for flow calculations considers the joint to be vented with the porous CFR barriers placed in the "open' assembly gap. Model development is based on a 1-D volume filling approach where flow resistances (assembly gap and CFRs) are defined by serially connected internal flow and the porous media "Darcy" relationships. Combustion gas flow rates are computed using the volume filling code by assuming a lumped distribution total joint fill volume on a per linear circumferential inch basis. Gas compressibility, friction and heat transfer are included in the modeling. Gas-to-wall heat transfer is simulated by concurrent solution of the compressible flow equations and a large thermal 2-D finite element (FE) conduction grid. The derived numerical technique loosely couples the FE conduction matrix with the compressible gas flow equations, Free constants that appear in the governing equations are calibrated by parametric model comparison to hot fire subscale test results. The calibrated model is then used to make full-scale motor predictions using RSRM aft dome environments. Model results indicate that CFR thermal barrier systems will provide a thermally benign and controlled pressurization environment for the RSRM nozzle joint-2 primary seal activation.

Malignant human cell transformation of Marcellus Shale gas drilling flow back water.

PubMed

Yao, Yixin; Chen, Tingting; Shen, Steven S; Niu, Yingmei; DesMarais, Thomas L; Linn, Reka; Saunders, Eric; Fan, Zhihua; Lioy, Paul; Kluz, Thomas; Chen, Lung-Chi; Wu, Zhuangchun; Costa, Max; Zelikoff, Judith

2015-10-01

The rapid development of high-volume horizontal hydraulic fracturing for mining natural gas from shale has posed potential impacts on human health and biodiversity. The produced flow back waters after hydraulic stimulation are known to carry high levels of saline and total dissolved solids. To understand the toxicity and potential carcinogenic effects of these wastewaters, flow back waters from five Marcellus hydraulic fracturing oil and gas wells were analyzed. The physicochemical nature of these samples was analyzed by inductively coupled plasma mass spectrometry and scanning electron microscopy/energy dispersive X-ray spectroscopy. A cytotoxicity study using colony formation as the endpoint was carried out to define the LC50 values of test samples using human bronchial epithelial cells (BEAS-2B). The BEAS-2B cell transformation assay was employed to assess the carcinogenic potential of the samples. Barium and strontium were among the most abundant metals in these samples and the same metals were found to be elevated in BEAS-2B cells after long-term treatment. BEAS-2B cells treated for 6weeks with flow back waters produced colony formation in soft agar that was concentration dependent. In addition, flow back water-transformed BEAS-2B cells show better migration capability when compared to control cells. This study provides information needed to assess the potential health impact of post-hydraulic fracturing flow back waters from Marcellus Shale natural gas mining. Copyright © 2015 Elsevier Inc. All rights reserved.

Hot gas ingestion characteristics and flow visualization of a vectored thrust STOVL concept

NASA Technical Reports Server (NTRS)

Johns, Albert L.; Neiner, George H.; Bencic, Timothy J.; Flood, Joseph D.; Amuedo, Kurt C.; Strock, Thomas W.; Williams, Ben R.

1990-01-01

A 9.2 percent scale short takeoff and vertical landing (STOVL) hot gas ingestion model was designed and built by McDonnell Douglas Corporation (MCAIR) and tested in the NASA Lewis Research Center 9- by 15-Foot Low Speed Wind Tunnel (LSWT). Hot gas ingestion, the entrainment of heated engine exhaust into the inlet flow field, is a key development issue for advanced short takeoff and vertical landing aircraft. The Phase 1 test program, conducted by NASA Lewis and McDonnell Douglas Corporation, evaluated the hot ingestion phenomena and control techniques and Phase 2 test program which was conducted by NASA Lewis are both reported. The Phase 2 program was conducted at exhaust nozzles temperatures up to 1460 R and utilized a sheet laser system for flow visualization of the model flow field in and out of ground effects. Hot gas ingestion levels were measured for the several forward nozzle splay configurations and with flow control/lift improvement devices which reduced the hot gas ingestion. The model support system had four degrees of freedom, heated high pressure air for nozzle flow, and a suction system exhaust for inlet flow. The headwind (freestream) velocity for Phase 1 was varied from 8 to 90 kn, with primary data taken in the 8 to 23 kn headwind velocity range. Phase 2 headwind velocity varied from 10 to 23 kn. Results of both Phase 1 and 2 are presented. A description of the model, facility, a new model support system, and a sheet laser illumination system are also provided. Results are presented over a range of main landing gear height (model height) above the ground plane at a 10 kn headwind velocity. The results contain the compressor face pressure and temperature distortions, total pressure recovery, compressor face temperature rise, and the environmental effects of the hot gas. The environmental effects include the ground plane temperature and pressure distributions, model airframe heating, and the location of the ground flow separation. Results from the sheet laser flow visualization test are also shown.

Design of Single Stage Axial Turbine with Constant Nozzle Angle Blading for Small Turbojet

NASA Astrophysics Data System (ADS)

Putra Adnan, F.; Hartono, Firman

2018-04-01

In this paper, an aerodynamic design of a single stage gas generator axial turbine for small turbojet engine is explained. As per design requirement, the turbine should be able to deliver power output of 155 kW at 0.8139 kg/s gas mass flow, inlet total temperature of 1200 K and inlet total pressure of 335330 Pa. The design phase consist of several steps, i.e.: determination of velocity triangles in 2D plane, 2D blading design and 3D flow analysis at design point using Computational Fluid Dynamics method. In the determination of velocity triangles, two conditions are applied: zero inlet swirl (i.e. the gas flow enter the turbine at axial direction) and constant nozzle angle design (i.e. the inlet and outlet angle of the nozzle blade are constant from root to tip). The 2D approach in cascade plane is used to specify airfoil type at root, mean and tip of the blade based on inlet and outlet flow conditions. The 3D approach is done by simulating the turbine in full configuration to evaluate the overall performance of the turbine. The observed parameters including axial gap, stagger angle, and tip clearance affect its output power. Based on analysis results, axial gap and stagger angle are positively correlated with output power up to a certain point at which the power decreases. Tip clearance, however, gives inversely correlation with output power.

Effect of additive oxygen gas on cellular response of lung cancer cells induced by atmospheric pressure helium plasma jet

PubMed Central

Joh, Hea Min; Choi, Ji Ye; Kim, Sun Ja; Chung, T. H.; Kang, Tae-Hong

2014-01-01

The atmospheric pressure helium plasma jet driven by pulsed dc voltage was utilized to treat human lung cancer cells in vitro. The properties of plasma plume were adjusted by the injection type and flow rate of additive oxygen gas in atmospheric pressure helium plasma jet. The plasma characteristics such as plume length, electric current and optical emission spectra (OES) were measured at different flow rates of additive oxygen to helium. The plasma plume length and total current decreased with an increase in the additive oxygen flow rate. The electron excitation temperature estimated by the Boltzmann plot from several excited helium emission lines increased slightly with the additive oxygen flow. The oxygen atom density in the gas phase estimated by actinometry utilizing argon was observed to increase with the additive oxygen flow. The concentration of intracellular reactive oxygen species (ROS) measured by fluorescence assay was found to be not exactly proportional to that of extracellular ROS (measured by OES), but both correlated considerably. It was also observed that the expression levels of p53 and the phospho-p53 were enhanced in the presence of additive oxygen flow compared with those from the pure helium plasma treatment. PMID:25319447

Lean stability augmentation study. [on gas turbine combustion chambers

NASA Technical Reports Server (NTRS)

Mcvey, J. B.; Kennedy, J. B.

1979-01-01

An analytical conceptual design study and an experimental test program were conducted to investigate techniques and develop technology for improving the lean combustion limits of premixing, prevaporizing combustors applicable to gas turbine engine main burners. The use of hot gas pilots, catalyzed flameholder elements, and heat recirculation to augment lean stability limits was considered in the conceptual design study. Tests of flameholders embodying selected concepts were conducted at a pressure of 10 arm and over a range of entrance temperatures simulating conditions to be encountered during stratospheric cruise. The tests were performed using an axisymmetric flametube test rig having a nominal diameter of 10.2 cm. A total of sixteen test configurations were examined in which lean blowout limits, pollutant emission characteristics, and combustor performance were evaluated. The use of a piloted perforated plate flameholder employing a pilot fuel flow rate equivalent to 4 percent of the total fuel flow at a simulated cruise condition resulted in a lean blowout equivalence ratio of less than 0.25 with a design point (T sub zero = 600k, Phi = 0.6) NOx emission index of less than 1.0 g/kg.

Decomposition of dimethylamine gas with dielectric barrier discharge.

PubMed

Ye, Zhaolian; Zhao, Jie; Huang, Hong ying; Ma, Fei; Zhang, Renxi

2013-09-15

The decomposition of dimethylamine (DMA) with gas under high flow rate was investigated with dielectric barrier discharge (DBD) technology. Different parameters including removal efficiency, energy yield, carbon balance and CO2 selectivity, secondary products, as well as pathways and mechanisms of DMA degradation were studied. The experimental results showed that removal efficiency of DMA depended on applied voltage and gas flow rate, but had no obvious correlation with initial concentration. Excellent energy performance was obtained using present DBD technology for DMA abatement. When experiment conditions were controlled at: gas flow rate of 14.9 m(3)/h, initial concentration of 2104 mg/m(3), applied voltage of 4.8 kV, removal efficiency of DMA and energy yield can reach 85.2% and 953.9 g/kWh, respectively. However, carbon balance (around 40%) was not ideal due to shorter residence time (about 0.1s), implying that some additional conditions should be considered to improve the total oxidation of DMA. Moreover, secondary products in outlet gas stream were detected via gas chromatogram-mass spectrum and the amounts of NO3(-) and NO2(-) were analyzed by ion chromatogram. The obtained data demonstrated that NOx might be suppressed due to reductive NH radical form DMA dissociation. The likely reaction pathways and mechanisms for the removal of DMA were suggested based on products analysis. Experimental results demonstrated the application potential of DBD as a clean technology for organic nitrogen-containing gas elimination from gas streams. Copyright © 2013 Elsevier B.V. All rights reserved.

Computational Aerothermodynamic Simulation Issues on Unstructured Grids

NASA Technical Reports Server (NTRS)

Gnoffo, Peter A.; White, Jeffery A.

2004-01-01

The synthesis of physical models for gas chemistry and turbulence from the structured grid codes LAURA and VULCAN into the unstructured grid code FUN3D is described. A directionally Symmetric, Total Variation Diminishing (STVD) algorithm and an entropy fix (eigenvalue limiter) keyed to local cell Reynolds number are introduced to improve solution quality for hypersonic aeroheating applications. A simple grid-adaptation procedure is incorporated within the flow solver. Simulations of flow over an ellipsoid (perfect gas, inviscid), Shuttle Orbiter (viscous, chemical nonequilibrium) and comparisons to the structured grid solvers LAURA (cylinder, Shuttle Orbiter) and VULCAN (flat plate) are presented to show current capabilities. The quality of heating in 3D stagnation regions is very sensitive to algorithm options in general, high aspect ratio tetrahedral elements complicate the simulation of high Reynolds number, viscous flow as compared to locally structured meshes aligned with the flow.

An Experimental and CFD Study of a Supersonic Coaxial Jet

NASA Technical Reports Server (NTRS)

Cutler, A. D.; White, J. A.

2001-01-01

A supersonic coaxial jet facility is designed and experimental data are acquired suitable for the validation of CFD codes employed in the analysis of high-speed air-breathing engines. The center jet is of a light gas, the coflow jet is of air, and the mixing layer between them is compressible. The jet flow field is characterized using schlieren imaging, surveys with pitot, total temperature and gas sampling probes, and RELIEF velocimetry. VULCAN, a structured grid CFD code, is used to solve for the nozzle and jet flow, and the results are compared to the experiment for several variations of the kappa - omega turbulence model

Applicability of empirical data currently used in predicting solid propellant exhaust plumes

NASA Technical Reports Server (NTRS)

Tevepaugh, J. A.; Smith, S. D.; Penny, M. M.; Greenwood, T.; Roberts, B. B.

1977-01-01

Theoretical and experimental approaches to exhaust plume analysis are compared. A two-phase model is extended to include treatment of reacting gas chemistry, and thermodynamical modeling of the gaseous phase of the flow field is considered. The applicability of empirical data currently available to define particle drag coefficients, heat transfer coefficients, mean particle size, and particle size distributions is investigated. Experimental and analytical comparisons are presented for subscale solid rocket motors operating at three altitudes with attention to pitot total pressure and stagnation point heating rate measurements. The mathematical treatment input requirements are explained. The two-phase flow field solution adequately predicts gasdynamic properties in the inviscid portion of two-phase exhaust plumes. It is found that prediction of exhaust plume gas pressures requires an adequate model of flow field dynamics.

Measurements of Skin Friction of the Compressible Turbulent Boundary Layer on a Cone with Foreign Gas Injection

NASA Technical Reports Server (NTRS)

Pappas, Constantine C.; Ukuno, Arthur F.

1960-01-01

Measurements of average skin friction of the turbulent boundary layer have been made on a 15deg total included angle cone with foreign gas injection. Measurements of total skin-friction drag were obtained at free-stream Mach numbers of 0.3, 0.7, 3.5, and 4.7 and within a Reynolds number range from 0.9 x 10(exp 6) to 5.9 x 10(exp 6) with injection of helium, air, and Freon-12 (CCl2F2) through the porous wall. Substantial reductions in skin friction are realized with gas injection within the range of Mach numbers of this test. The relative reduction in skin friction is in accordance with theory-that is, the light gases are most effective when compared on a mass flow basis. There is a marked effect of Mach number on the reduction of average skin friction; this effect is not shown by the available theories. Limited transition location measurements indicate that the boundary layer does not fully trip with gas injection but that the transition point approaches a forward limit with increasing injection. The variation of the skin-friction coefficient, for the lower injection rates with natural transition, is dependent on the flow Reynolds number and type of injected gas; and at the high injection rates the skin friction is in fair agreement with the turbulent boundary layer results.

The effect of dry spots on heat transfer in a locally heated liquid film moving under the action of gas flow in a channel

NASA Astrophysics Data System (ADS)

Zaitsev, D. V.; Tkachenko, E. M.; Bykovskaya, E. F.

2017-11-01

Intensive evaporation of a thin liquid film, moving in a flat micro-/minichannel under the action of gas flow is very promising for the use in cooling systems of modern semiconductor devices with localized heat sources of high intensity. In this work, using the high-speed visualization, the effect of the formation of dry spots on heat transfer in a locally heated liquid film shear-driven in a channel was investigated. It was found that the maximum intensity of heat removal from the heater is achieved in the mode, when the film flow continuity is broken. During the experiment the total area of dry spots increases with increasing heat flux and heater temperature, but when the heater reaches a certain temperature (≈100°C), the total area begins to decrease. However, the length of contact line increases with increasing heat flux and reaches a maximum in the pre-crisis regime. Intensive evaporation in the region of the contact line may explain the achievement of high heat fluxes in the shear-driven liquid film.

Two-stage preconcentrator for vapor/particle detection

DOEpatents

Linker, Kevin L.; Brusseau, Charles A.

2002-01-01

A device for concentrating particles from a high volume gas stream and delivering the particles for detection in a low volume gas stream includes first and second preconcentrators. The first preconcentrator has a first structure for retaining particles in a first gas flow path through which a first gas flows at a relatively high volume, valves for selectively stopping the first gas flow; and a second gas flow path through which gas flows at an intermediate flow volume for moving particles from the first structure. The second preconcentrator includes a second structure for retaining particles in the second gas flow path; a valve for selectively stopping the second gas flow; and a third gas flow path through which gas flows at a low volume for moving particles from the second structure to a detector. Each of the particle retaining structures is preferably a metal screen that may be resistively heated by application of an electric potential to release the particles.

Gas flow through rough microchannels in the transition flow regime.

PubMed

Deng, Zilong; Chen, Yongping; Shao, Chenxi

2016-01-01

A multiple-relaxation-time lattice Boltzmann model of Couette flow is developed to investigate the rarified gas flow through microchannels with roughness characterized by fractal geometry, especially to elucidate the coupled effects of roughness and rarefaction on microscale gas flow in the transition flow regime. The results indicate that the surface roughness effect on gas flow behavior becomes more significant in rarefied gas flow with the increase of Knudsen number. We find the gas flow behavior in the transition flow regime is more sensitive to roughness height than that in the slip flow regime. In particular, the influence of fractal dimension on rarefied gas flow behavior is less significant than roughness height.

Drops of energy: conserving urban water to reduce greenhouse gas emissions.

PubMed

Zhou, Yuanchun; Zhang, Bing; Wang, Haikun; Bi, Jun

2013-10-01

Water and energy are two essential resources of modern civilization and are inherently linked. Indeed, the optimization of the water supply system would reduce energy demands and greenhouse gas emissions in the municipal water sector. This research measured the climatic cobenefit of water conservation based on a water flow analysis. The results showed that the estimated energy consumption of the total water system in Changzhou, China, reached approximately 10% of the city's total energy consumption, whereas the industrial sector was found to be more energy intensive than other sectors within the entire water system, accounting for nearly 70% of the total energy use of the water system. In addition, four sustainable water management scenarios would bring the cobenefit of reducing the total energy use of the water system by 13.9%, and 77% of the energy savings through water conservation was indirect. To promote sustainable water management and reduce greenhouse gas emissions, China would require its water price system, both for freshwater and recycled water, to be reformed.

Pore-scale lattice Boltzmann simulation of micro-gaseous flow considering surface diffusion effect

DOE PAGES

Wang, Junjian; Kang, Qinjun; Chen, Li; ...

2016-11-21

Some recent studies have shown that adsorbed gas and its surface diffusion have profound influence on micro-gaseous flow through organic pores in shale gas reservoirs. Here, a multiple-relaxation-time (MRT) LB model is adopted to estimate the apparent permeability of organic shale and a new boundary condition, which combines Langmuir adsorption theory with Maxwellian diffusive reflection boundary condition, is proposed to capture gas slip and surface diffusion of adsorbed gas. The simulation results match well with previous studies carried out using Molecular Dynamics (MD) and show that Maxwell slip boundary condition fails to characterize gas transport in the near wall regionmore » under the influence of the adsorbed gas. The total molar flux can be either enhanced or reduced depending on variations in adsorbed gas coverage and surface diffusion velocity. The effects of pore width, pressure as well as Langmuir properties on apparent permeability of methane transport in organic pores are further studied. It is found that the surface transport plays a significant role in determining the apparent permeability, and the variation of apparent permeability with pore size and pressure is affected by the adsorption and surface diffusion.« less

Influence of vascular network design on gas transfer in lung assist device technology.

PubMed

Bassett, Erik K; Hoganson, David M; Lo, Justin H; Penson, Elliot J N; Vacanti, Joseph P

2011-01-01

Blood oxygenators are vital for the critically ill, but their use is limited to the hospital setting. A portable blood oxygenator or a lung assist device for ambulatory or long-term use would greatly benefit patients with chronic lung disease. In this work, a biomimetic blood oxygenator system was developed which consisted of a microfluidic vascular network covered by a gas permeable silicone membrane. This system was used to determine the influence of key microfluidic parameters-channel size, oxygen exposure length, and blood shear rate-on blood oxygenation and carbon dioxide removal. Total gas transfer increased linearly with flow rate, independent of channel size and oxygen exposure length. On average, CO(2) transfer was 4.3 times higher than oxygen transfer. Blood oxygen saturation was also found to depend on the flow rate per channel but in an inverse manner; oxygenation decreased and approached an asymptote as the flow rate per channel increased. These relationships can be used to optimize future biomimetic vascular networks for specific lung applications: gas transfer for carbon dioxide removal in patients with chronic obstructive pulmonary disease or oxygenation for premature infants requiring complete lung replacement therapy.

Small-volume, ultrahigh-vacuum-compatible high-pressure reaction cell for combined kinetic and in situ IR spectroscopic measurements on planar model catalysts

NASA Astrophysics Data System (ADS)

Zhao, Z.; Diemant, T.; Häring, T.; Rauscher, H.; Behm, R. J.

2005-12-01

We describe the design and performance of a high-pressure reaction cell for simultaneous kinetic and in situ infrared reflection (IR) spectroscopic measurements on model catalysts at elevated pressures, between 10-3 and 103mbars, which can be operated both as batch reactor and as flow reactor with defined gas flow. The cell is attached to an ultrahigh-vacuum (UHV) system, which is used for sample preparation and also contains facilities for sample characterization. Specific for this design is the combination of a small cell volume, which allows kinetic measurements with high sensitivity under batch or continuous flow conditions, the complete isolation of the cell from the UHV part during UHV measurements, continuous temperature control during both UHV and high-pressure operation, and rapid transfer between UHV and high-pressure stage. Gas dosing is performed by a designed gas-handling system, which allows operation as flow reactor with calibrated gas flows at adjustable pressures. To study the kinetics of reactions on the model catalysts, a quadrupole mass spectrometer is connected to the high-pressure cell. IR measurements are possible in situ by polarization-modulation infrared reflection-absorption spectroscopy, which also allows measurements at elevated pressures. The performance of the setup is demonstrated by test measurements on the kinetics for CO oxidation and the CO adsorption on a Au /TiO2/Ru(0001) model catalyst film at 1-50 mbar total pressure.

Experimental studies and model analysis of noble gas fractionation in low-permeability porous media

NASA Astrophysics Data System (ADS)

Ding, Xin; Mack Kennedy, B.; Molins, Sergi; Kneafsey, Timothy; Evans, William C.

2017-05-01

Gas flow through the vadose zone from sources at depth involves fractionation effects that can obscure the nature of transport and even the identity of the source. Transport processes are particularly complex in low permeability media but as shown in this study, can be elucidated by measuring the atmospheric noble gases. A series of laboratory column experiments was conducted to evaluate the movement of noble gas from the atmosphere into soil in the presence of a net efflux of CO2, a process that leads to fractionation of the noble gases from their atmospheric abundance ratios. The column packings were designed to simulate natural sedimentary deposition by interlayering low permeability ceramic plates and high permeability beach sand. Gas samples were collected at different depths at CO2 fluxes high enough to cause extreme fractionation of the noble gases (4He/36Ar > 20 times the air ratio). The experimental noble gas fractionation-depth profiles were in good agreement with those predicted by the dusty gas (DG) model, demonstrating the applicability of the DG model across a broad spectrum of environmental conditions. A governing equation based on the dusty gas model was developed to specifically describe noble gas fractionation at each depth that is controlled by the binary diffusion coefficient, Knudsen diffusion coefficient and the ratio of total advection flux to total flux. Finally, the governing equation was used to derive the noble gas fractionation pattern and illustrate how it is influenced by soil CO2 flux, sedimentary sequence, thickness of each sedimentary layer and each layer's physical parameters. Three potential applications of noble gas fractionation are provided: evaluating soil attributes in the path of gas flow from a source at depth to the atmosphere, testing leakage through low permeability barriers used to isolate buried waste, and tracking biological methanogenesis and methane oxidation associated with hydrocarbon degradation.

Closed cycle high-repetition-rate pulsed HF laser

NASA Astrophysics Data System (ADS)

Harris, Michael R.; Morris, A. V.; Gorton, Eric K.

1997-04-01

The design and performance of a closed cycle high repetition rate HF laser is described. A short pulse, glow discharge is formed in a 10 SF6:1 H2 gas mixture at a total pressure of approximately 110 torr within a 15 by 0.5 by 0.5 cm3 volume. Transverse, recirculated gas flow adequate to enable repetitive operation up to 3 kHz is imposed by a centrifugal fan. The fan also forces the gas through a scrubber cell to eliminate ground state HF from the gas stream. An automated gas make-up system replenishes spent gas removed by the scrubber. Typical mean laser output powers up to 3 W can be maintained for extended periods of operation.

Analysis of effect of the solubility on gas exchange in nonhomogeneous lungs

NASA Technical Reports Server (NTRS)

Colburn, W. E., Jr.; Evans, J. W.; West, J. B.

1974-01-01

A comparison is made of the gas exchange in nonhomogeneous lung models and in homogeneous lung models with the same total blood flow and ventilation. It is shown that the ratio of the rate of gas transfer of the inhomogeneous lung model over the rate of gas transfer of the homogeneous lung model as a function of gas solubility always has the qualitative features for gases with linear dissociation curves. This ratio is 1 for a gas with zero solubility and decreases to a single minimum. It subsequently rises to approach 1 as the solubility tends to infinity. The early portion of the graph of this function is convex, then after a single inflection point it is concave.

Method of design for vertical oil shale retorting vessels and retorting therewith

DOEpatents

Reeves, Adam A.

1978-01-03

A method of designing the gas flow parameters of a vertical shaft oil shale retorting vessel involves determining the proportion of gas introduced in the bottom of the vessel and into intermediate levels in the vessel to provide for lateral distribution of gas across the vessel cross section, providing mixing with the uprising gas, and determining the limiting velocity of the gas through each nozzle. The total quantity of gas necessary for oil shale treatment in the vessel may be determined and the proportion to be injected into each level is then determined based on the velocity relation of the orifice velocity and its feeder manifold gas velocity. A limitation is placed on the velocity of gas issuing from an orifice by the nature of the solid being treated, usually physical tests of gas velocity impinging the solid.

Tar Production from Biomass Pyrolysis in a Fluidized Bed Reactor: A Novel Turbulent Multiphase Flow Formulation

NASA Technical Reports Server (NTRS)

Bellan, J.; Lathouwers, D.

2000-01-01

A novel multiphase flow model is presented for describing the pyrolysis of biomass in a 'bubbling' fluidized bed reactor. The mixture of biomass and sand in a gaseous flow is conceptualized as a particulate phase composed of two classes interacting with the carrier gaseous flow. The solid biomass is composed of three initial species: cellulose, hemicellulose and lignin. From each of these initial species, two new solid species originate during pyrolysis: an 'active' species and a char, thus totaling seven solid-biomass species. The gas phase is composed of the original carrier gas (steam), tar and gas; the last two species originate from the volumetric pyrolysis reaction. The conservation equations are derived from the Boltzmann equations through ensemble averaging. Stresses in the gaseous phase are the sum of the Newtonian and Reynolds (turbulent) contributions. The particulate phase stresses are the sum of collisional and Reynolds contributions. Heat transfer between phases, and heat transfer between classes in the particulate phase is modeled, the last resulting from collisions between sand and biomass. Closure of the equations must be performed by modeling the Reynolds stresses for both phases. The results of a simplified version (first step) of the model are presented.

Effect of placements (horizontal with vertical) on gas-solid flow and particle impact erosion in gate valve

NASA Astrophysics Data System (ADS)

Lin, Zhe; Zhu, Linhang; Cui, Baoling; Li, Yi; Ruan, Xiaodong

2014-12-01

Gate valve has various placements in the practical usages. Due to the effect of gravity, particle trajectories and erosions are distinct between placements. Thus in this study, gas-solid flow properties and erosion in gate valve for horizontal placement and vertical placement are discussed and compared by using Euler-Lagrange simulation method. The structure of a gate valve and a simplified structure are investigated. The simulation procedure is validated in our published paper by comparing with the experiment data of a pipe and an elbow. The results show that for all investigated open degrees and Stokes numbers (St), there are little difference of gas flow properties and flow coefficients between two placements. It is also found that the trajectories of particles for two placements are mostly identical when St « 1, making the erosion independent of placement. With the increase of St, the distinction of trajectories between placements becomes more obvious, leading to an increasing difference of the erosion distributions. Besides, the total erosion ratio of surface T for horizontal placement is two orders of magnitudes larger than that for vertical placement when the particle diameter is 250μm.

Effect of low-flow anesthesia education on knowledge, attitude and behavior of the anesthesia team.

PubMed

Hanci, Volkan; Yurtlu, Serhan; Ayoğlu, Hilal; Okyay, Rahşan Dilek; Erdoğan, Gülay; Abduşoğlu, Mustafa; Sayin, Esin; Turan, Işil Ozkoçak

2010-08-01

The aim of this study was to evaluate the effect of education on the knowledge, attitude and behavior of anesthesiology staff and residents towards low-flow anesthesia. The staff and residents in the Department of Anesthesia and Reanimation, Zonguldak Karaelmas University were given theoretical and practical training in delivering low-flow anesthesia. To evaluate their attitudes and behaviors toward low-flow anesthesia, we collected data during the 6 months before training, during the first 3 months after training, and at 4-6 months after training. Anesthesia follow-up records, operation time, volatile anesthetic agent used, and the amount (in liters) of fresh gas low mid-anesthesia were recorded in all three stages. A total of 3,158 patients received general anesthesia and inhalation anesthesia was used in 3,115 of these patients. Our study group consisted of 2,752 patients who had no absolute or relative contraindications to low-flow anesthesia. While the mean fresh gas flow was 4.00 +/- 0.00 L/min before training, this level dropped to 2.98 L/min in the first 3 months after training, and to 3.26 L/min in the following 3 months. The mean fresh gas flow was significantly lower at the two post-training assessments than before training (p < 0.05). In conclusion, low-flow anesthesia may be used more frequently if educational seminars are provided to anesthetists. The use of low-flow anesthesia may increase further by allocating more time to this technique in anesthesia training programs provided at regular intervals. Copyright 2010 Elsevier. Published by Elsevier B.V. All rights reserved.

System using electric furnace exhaust gas to preheat scrap for steelmaking

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

Takai, K.; Iwasaki, K.

1987-09-08

A method is described for clean preheating of scrap contaminated with oil and organic matter, for steelmaking, using heat from exhaust gas flow from an electric furnace. It consists of: burning any combustibles present in the exhaust gas flow and simultanously separating out dust particles from the exhaust gas flow; heating a predetermined amount of the scrap by heat exchange with a predetermined portion of the exhaust gas flow; removing and collecting dust from the exhaust gas flow after preheating of scrap thereby; sensing the temperature of the exhaust flow; scrubbing the exhaust gas flow with an aqueous solution ofmore » a deodorant solvent flowing at a rate regulated to be in a predetermined relationship related to the exhaust gas temperature sensed prior to scrubbing, thereby generating saturated vapor and reducing the temperature of the exhaust gas flow by a predetermined amount; and electrostatically precipitating out oil mist attached to saturated water vapor and liquid droplets in the exhaust gas flow.« less

The ideal oxygen/nitrous oxide fresh gas flow sequence with the Anesthesia Delivery Unit machine.

PubMed

Hendrickx, Jan F A; Cardinael, Sara; Carette, Rik; Lemmens, Hendrikus J M; De Wolf, Andre M

2007-06-01

To determine whether early reduction of oxygen and nitrous oxide fresh gas flow from 6 L/min to 0.7 L/min could be accomplished while maintaining end-expired nitrous oxide concentration > or =50% with an Anesthesia Delivery Unit anesthesia machine. Prospective, randomized clinical study. Large teaching hospital in Belgium. 53 ASA physical status I and II patients requiring general endotracheal anesthesia and controlled mechanical ventilation. Patients were randomly assigned to one of 4 groups depending on the duration of high oxygen/nitrous oxide fresh gas flow (two and 4 L/min, respectively) before lowering total fresh gas flow to 0.7 L/min (0.3 and 0.4 L/min oxygen and nitrous oxide, respectively): one, two, three, or 5 minutes (1-minute group, 2-minute group, 3-minute group, and 5-minute group), with n = 10, 12, 13, and 8, respectively. The course of the end-expired nitrous oxide concentration and bellows volume deficit at end-expiration was compared among the 4 groups during the first 30 minutes. At the end of the high-flow period the end-expired nitrous oxide concentration was 35.6 +/- 6.2%, 48.4 +/- 4.8%, 53.7 +/- 8.7%, and 57.3 +/- 1.6% in the 4 groups, respectively. Thereafter, the end-expired nitrous oxide concentration decreased to a nadir of 36.1 +/- 4.5%, 45.4 +/- 3.8%, 50.9 +/- 6.1%, and 55.4 +/- 2.8% after three, 4, 6, and 8 minutes after flows were lowered in the 1- to 5-minute groups, respectively. A decrease in bellows volume was observed in most patients, but was most pronounced in the 2-minute group. The bellows volume deficit gradually faded within 15 to 20 minutes in all 4 groups. A 3-minute high-flow period (oxygen and nitrous oxide fresh gas flow of 2 and 4 L/min, respectively) suffices to attain and maintain end-expired nitrous oxide concentration > or =50% and ensures an adequate bellows volume during the ensuing low-flow period.

A combined volume-of-fluid method and low-Mach-number approach for DNS of evaporating droplets in turbulence

NASA Astrophysics Data System (ADS)

Dodd, Michael; Ferrante, Antonino

2017-11-01

Our objective is to perform DNS of finite-size droplets that are evaporating in isotropic turbulence. This requires fully resolving the process of momentum, heat, and mass transfer between the droplets and surrounding gas. We developed a combined volume-of-fluid (VOF) method and low-Mach-number approach to simulate this flow. The two main novelties of the method are: (i) the VOF algorithm captures the motion of the liquid gas interface in the presence of mass transfer due to evaporation and condensation without requiring a projection step for the liquid velocity, and (ii) the low-Mach-number approach allows for local volume changes caused by phase change while the total volume of the liquid-gas system is constant. The method is verified against an analytical solution for a Stefan flow problem, and the D2 law is verified for a single droplet in quiescent gas. We also demonstrate the schemes robustness when performing DNS of an evaporating droplet in forced isotropic turbulence.

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 party, on timescales that can inform industry decision makers and assist rapid-response planning by government.

Enhanced ozone production in a pulsed dielectric barrier discharge plasma jet with addition of argon to a He-O2 flow gas

NASA Astrophysics Data System (ADS)

Sands, Brian; Ganguly, Biswa; Scofield, James

2013-09-01

Ozone production in a plasma jet DBD driven with a 20-ns risetime unipolar pulsed voltage can be significantly enhanced using helium as the primary flow gas with an O2 coflow. The overvolted discharge can be sustained with up to a 5% O2 coflow at <20 kHz pulse repetition frequency at 13 kV applied voltage. Ozone production scales with the pulse repetition frequency up to a ``turnover frequency'' that depends on the O2 concentration, total gas flow rate, and applied voltage. For example, peak ozone densities >1016 cm-3 were measured with 3% O2 admixture and <3 W input power at a 12 kHz turnover frequency. A further increase in the repetition frequency results in increased discharge current and 777 nm O(5 P) emission, but decreased ozone production and is followed by a transition to a filamentary discharge mode. The addition of argon at concentrations >=5% reduces the channel conductivity and shifts the turnover frequency to higher frequencies. This results in increased ozone production for a given applied voltage and gas flow rate. Time-resolved Ar(1s5) and He(23S1) metastable densities were acquired along with discharge current and ozone density measurements to gain insight into the mechanisms of optimum ozone production.

Gas flow meter and method for measuring gas flow rate

DOEpatents

Robertson, Eric P.

2006-08-01

A gas flow rate meter includes an upstream line and two chambers having substantially equal, fixed volumes. An adjustable valve may direct the gas flow through the upstream line to either of the two chambers. A pressure monitoring device may be configured to prompt valve adjustments, directing the gas flow to an alternate chamber each time a pre-set pressure in the upstream line is reached. A method of measuring the gas flow rate measures the time required for the pressure in the upstream line to reach the pre-set pressure. The volume of the chamber and upstream line are known and fixed, thus the time required for the increase in pressure may be used to determine the flow rate of the gas. Another method of measuring the gas flow rate uses two pressure measurements of a fixed volume, taken at different times, to determine the flow rate of the gas.

CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Influence of the total gas flow rate on high rate growth microcrystalline silicon films and solar cells

NASA Astrophysics Data System (ADS)

Han, Xiao-Yan; Hou, Guo-Fu; Zhang, Xiao-Dan; Wei, Chang-Chun; Li, Gui-Jun; Zhang, De-Kun; Chen, Xin-Liang; Sun, Jian; Zhang, Jian-Jun; Zhao, Ying; Geng, Xin-Hua

2009-08-01

This paper reports that high-rate-deposition of microcrystalline silicon solar cells was performed by very-high-frequency plasma-enhanced chemical vapor deposition. These solar cells, whose intrinsic μc-Si:H layers were prepared by using a different total gas flow rate (Ftotal), behave much differently in performance, although their intrinsic layers have similar crystalline volume fraction, opto-electronic properties and a deposition rate of ~ 1.0 nm/s. The influence of Ftotal on the micro-structural properties was analyzed by Raman and Fourier transformed infrared measurements. The results showed that the vertical uniformity and the compact degree of μc-Si:H thin films were improved with increasing Ftotal. The variation of the microstructure was regarded as the main reason for the difference of the J-V parameters. Combined with optical emission spectroscopy, we found that the gas temperature plays an important role in determining the microstructure of thin films. With Ftotal of 300 sccm, a conversion efficiency of 8.11% has been obtained for the intrinsic layer deposited at 8.5 Å/s (1 Å = 0.1 nm).

Dependence of N-polar GaN rod morphology on growth parameters during selective area growth by MOVPE

NASA Astrophysics Data System (ADS)

Li, Shunfeng; Wang, Xue; Mohajerani, Matin Sadat; Fündling, Sönke; Erenburg, Milena; Wei, Jiandong; Wehmann, Hergo-Heinrich; Waag, Andreas; Mandl, Martin; Bergbauer, Werner; Strassburg, Martin

2013-02-01

Selective area growth of GaN rods by metalorganic vapor phase epitaxy has attracted great interest due to its novel applications in optoelectronic and photonics. In this work, we will present the dependence of GaN rod morphology on various growth parameters i.e. growth temperature, H2/N2 carrier gas concentration, V/III ratio, total carrier gas flow and reactor pressure. It is found that higher growth temperature helps to increase the aspect ratio of the rods, but reduces the height homogeneity. Furthermore, H2/N2 carrier gas concentration is found to be a critical factor to obtain vertical rod growth. Pure nitrogen carrier gas leads to irregular growth of GaN structure, while an increase of hydrogen carrier gas results in vertical GaN rod growth. Higher hydrogen carrier gas concentration also reduces the diameter and enhances the aspect of the GaN rods. Besides, increase of V/III ratio causes reduction of the aspect ratio of N-polar GaN rods, which could be explained by the relatively lower growth rate on (000-1) N-polar top surface when supplying more ammonia. In addition, an increase of the total carrier gas flow leads to a decrease in the diameter and the average volume of GaN rods. These phenomena are tentatively explained by the change of partial pressure of the source materials and boundary layer thickness in the reactor. Finally, it is shown that the average volume of the N-polar GaN rods keeps a similar value for a reactor pressure PR of 66 and 125 mbar, while an incomplete filling of the pattern opening is observed with PR of 250 mbar. Room temperature photoluminescence spectrum of the rods is also briefly discussed.

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

Wang, X.; Xiao, Y.; Xu, S.

A co-production system based on Fischer-Tropsch (FT) synthesis reactor and gas turbine was simulated and analyzed. Syngas from entrained bed coal gasification was used as feedstock of the low-temperature slurry phase Fischer-Tropsch reactor. Raw synthetic liquid produced was fractioned and upgraded to diesel, gasoline, and liquid petrol gas (LPG). Tail gas composed of unconverted syngas and FT light components was fed to the gas turbine. Supplemental fuel (NG, or refinery mine gas) might be necessary, which was dependent on gas turbine capacity expander through flow capacity, etc. FT yield information was important to the simulation of this co-production system. Amore » correlation model based on Mobil's two step pilot plant was applied. User models that can predict product yields and cooperate with other units were embedded into Aspen plus simulation. Performance prediction of syngas fired gas turbine was the other key of this system. The increase in mass flow through the turbine affects the match between compressor and turbine operating conditions. The calculation was carried out by GS software developed by Politecnico Di Milano and Princeton University. Various cases were investigated to match the FT synthesis island, power island, and gasification island in co-production systems. Effects of CO{sub 2} removal/LPG recovery, co-firing, and CH{sub 4} content variation were studied. Simulation results indicated that more than 50% of input energy was converted to electricity and FT products. Total yield of gasoline, diesel, and LPG was 136-155 g/N m{sup 3} (CO+H{sub 2}). At coal feed of 21.9 kg/s, net electricity exported to the grid was higher than 100 MW. Total production of diesel and gasoline (and LPG) was 118,000 t (134,000 t)/year. Under the economic analysis conditions assumed in this paper the co-production system was economically feasible.« less

Method and system for gas flow mitigation of molecular contamination of optics

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

Delgado, Gildardo; Johnson, Terry; Arienti, Marco

A computer-implemented method for determining an optimized purge gas flow in a semi-conductor inspection metrology or lithography apparatus, comprising receiving a permissible contaminant mole fraction, a contaminant outgassing flow rate associated with a contaminant, a contaminant mass diffusivity, an outgassing surface length, a pressure, a temperature, a channel height, and a molecular weight of a purge gas, calculating a flow factor based on the permissible contaminant mole fraction, the contaminant outgassing flow rate, the channel height, and the outgassing surface length, comparing the flow factor to a predefined maximum flow factor value, calculating a minimum purge gas velocity and amore » purge gas mass flow rate from the flow factor, the contaminant mass diffusivity, the pressure, the temperature, and the molecular weight of the purge gas, and introducing the purge gas into the semi-conductor inspection metrology or lithography apparatus with the minimum purge gas velocity and the purge gas flow rate.« less

Measurements of energy distribution and thrust for microwave plasma coupling of electrical energy to hydrogen for propulsion

NASA Technical Reports Server (NTRS)

Morin, T.; Chapman, R.; Filpus, J.; Hawley, M.; Kerber, R.; Asmussen, J.; Nakanishi, S.

1982-01-01

A microwave plasma system for transfer of electrical energy to hydrogen flowing through the system has potential application for coupling energy to a flowing gas in the electrothermal propulsion concept. Experimental systems have been designed and built for determination of the energy inputs and outputs and thrust for the microwave coupling of energy to hydrogen. Results for experiments with pressure in the range 100 microns-6 torr, hydrogen flow rate up to 1000 micronmoles/s, and total absorbed power to 700 w are presented.

Measuring Uptake Coefficients and Henry's Law Constants of Gas-Phase Species with Models for Secondary Organic Aerosol

NASA Astrophysics Data System (ADS)

Fairhurst, M. C.; Waring-Kidd, C.; Ezell, M. J.; Finlayson-Pitts, B. J.

2014-12-01

Volatile organic compounds (VOC) are oxidized in the atmosphere and their products contribute to secondary organic aerosol (SOA) formation. These particles have been shown to have effects on visibility, climate, and human health. Current models typically under-predict SOA concentrations from field measurements. Underestimation of these concentrations could be a result of how models treat particle growth. It is often assumed that particles grow via instantaneous thermal equilibrium partitioning between liquid particles and gas-phase species. Recent work has shown that growth may be better represented by irreversible, kinetically limited uptake of gas-phase species onto more viscous, tar-like SOA. However, uptake coefficients for these processes are not known. The goal of this project is to measure uptake coefficients and solubilities for different gases onto models serving as proxies for SOA and determine how they vary based on the chemical composition of the gas and the condensed phase. Experiments were conducted using two approaches: attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy and a flow system coupled to a mass spectrometer. The ATR crystal was coated with the SOA proxy and the gas-phase species introduced via a custom flow system. Uptake of the gas-phase species was characterized by measuring the intensity of characteristic IR bands as a function of time, from which a Henry's law constant and initial estimate of uptake coefficients could be obtained. Uptake coefficients were also measured in a flow system where the walls of the flow tube were coated with the SOA proxy and gas-phase species introduced via a moveable inlet. Uptake coefficients were derived from the decay in gas-phase species measured by mass spectrometry. The results of this work will establish a structure-interaction relationship for uptake of gases into SOA that can be implemented into regional and global models.

Electric force on plasma ions and the momentum of the ion-neutrals flow

NASA Astrophysics Data System (ADS)

Makrinich, G.; Fruchtman, A.; Zoler, D.; Boxman, R. L.

2018-05-01

The electric force on ions in plasma and the momentum flux carried by the mixed ion-neutral flow were measured and found to be equal. The experiment was performed in a direct-current gas discharge of cylindrical geometry with applied radial electric field and axial magnetic field. The unmagnetized plasma ions, neutralized by magnetized electrons, were accelerated radially outward transferring part of the gained momentum to neutrals. Measurements were taken for various argon gas flow rates between 13 and 100 Standard Cubic Centimeter per Minute, for a discharge current of 1.9 A and a magnetic field intensity of 136 G. The plasma density, electron temperature, and plasma potential were measured at various locations along the flow. These measurements were used to determine the local electric force on the ions. The total electric force on the plasma ions was then determined by integrating radially the local electric force. In parallel, the momentum flux of the mixed ion-neutral flow was determined by measuring the force exerted by the flow on a balance force meter (BFM). The maximal plasma density was between 6 × 1010 cm-3 and 5 × 1011 cm-3, the maximal electron temperature was between 8 eV and 25 eV, and the deduced maximal electric field was between 2200 V/m and 5800 V/m. The force exerted by the mixed ion-neutral flow on the BFM agreed with the total electric force on the plasma ions. This agreement showed that it is the electric force on the plasma ions that is the source of the momentum acquired by the mixed ion-neutral flow.

Calculation of gas turbine characteristic

NASA Astrophysics Data System (ADS)

Mamaev, B. I.; Murashko, V. L.

2016-04-01

The reasons and regularities of vapor flow and turbine parameter variation depending on the total pressure drop rate π* and rotor rotation frequency n are studied, as exemplified by a two-stage compressor turbine of a power-generating gas turbine installation. The turbine characteristic is calculated in a wide range of mode parameters using the method in which analytical dependences provide high accuracy for the calculated flow output angle and different types of gas dynamic losses are determined with account of the influence of blade row geometry, blade surface roughness, angles, compressibility, Reynolds number, and flow turbulence. The method provides satisfactory agreement of results of calculation and turbine testing. In the design mode, the operation conditions for the blade rows are favorable, the flow output velocities are close to the optimal ones, the angles of incidence are small, and the flow "choking" modes (with respect to consumption) in the rows are absent. High performance and a nearly axial flow behind the turbine are obtained. Reduction of the rotor rotation frequency and variation of the pressure drop change the flow parameters, the parameters of the stages and the turbine, as well as the form of the characteristic. In particular, for decreased n, nonmonotonic variation of the second stage reactivity with increasing π* is observed. It is demonstrated that the turbine characteristic is mainly determined by the influence of the angles of incidence and the velocity at the output of the rows on the losses and the flow output angle. The account of the growing flow output angle due to the positive angle of incidence for decreased rotation frequencies results in a considerable change of the characteristic: poorer performance, redistribution of the pressure drop at the stages, and change of reactivities, growth of the turbine capacity, and change of the angle and flow velocity behind the turbine.

Numerical Analysis of Mixed-Phase Icing Cloud Simulations in the NASA Propulsion Systems Laboratory

NASA Technical Reports Server (NTRS)

Bartkus, Tadas; Tsao, Jen-Ching; Struk, Peter; Van Zante, Judith

2017-01-01

This presentation describes the development of a numerical model that couples the thermal interaction between ice particles, water droplets, and the flowing gas of an icing wind tunnel for simulation of NASA Glenn Research Centers Propulsion Systems Laboratory (PSL). The ultimate goal of the model is to better understand the complex interactions between the test parameters and have greater confidence in the conditions at the test section of the PSL tunnel. The model attempts to explain the observed changes in test conditions by coupling the conservation of mass and energy equations for both the cloud particles and flowing gas mass. Model predictions were compared to measurements taken during May 2015 testing at PSL, where test conditions varied gas temperature, pressure, velocity and humidity levels, as well as the cloud total water content, particle initial temperature, and particle size distribution.

Numerical Analysis of Mixed-Phase Icing Cloud Simulations in the NASA Propulsion Systems Laboratory

NASA Technical Reports Server (NTRS)

Bartkus, Tadas P.; Tsao, Jen-Ching; Struk, Peter M.; Van Zante, Judith F.

2017-01-01

This paper describes the development of a numerical model that couples the thermal interaction between ice particles, water droplets, and the flowing gas of an icing wind tunnel for simulation of NASA Glenn Research Centers Propulsion Systems Laboratory (PSL). The ultimate goal of the model is to better understand the complex interactions between the test parameters and have greater confidence in the conditions at the test section of the PSL tunnel. The model attempts to explain the observed changes in test conditions by coupling the conservation of mass and energy equations for both the cloud particles and flowing gas mass. Model predictions were compared to measurements taken during May 2015 testing at PSL, where test conditions varied gas temperature, pressure, velocity and humidity levels, as well as the cloud total water content, particle initial temperature, and particle size distribution.

Rayleigh Scattering Diagnostic for Measurement of Temperature, Velocity, and Density Fluctuation Spectra

NASA Technical Reports Server (NTRS)

Mielke, Amy F.; Elam, Kristie A.; Sung, Chih-Jen; Panda, Jayanta

2006-01-01

A molecular Rayleigh scattering technique is developed to measure dynamic gas temperature, velocity, and density in unseeded turbulent flows at sampling rates up to 10 kHz. A high power CW laser beam is focused at a point in a heated air jet plume and Rayleigh scattered light is collected and spectrally resolved. The spectrum of the light, which contains information about the temperature, velocity, and density of the flow, is analyzed using a Fabry-Perot interferometer. The circular interference fringe pattern is divided into four concentric regions and sampled at 1 and 10 kHz using photon counting electronics. Monitoring the relative change in intensity within each region allows for measurement of gas temperature and velocity. Independently monitoring the total scattered light intensity provides a measure of gas density. Power spectral density calculations of temperature, velocity, and density fluctuations, as well as mean and fluctuating quantities are demonstrated for various radial locations in the jet flow at a fixed axial distance from the jet exit plane. Results are compared with constant current anemometry and pitot probe measurements at the same locations.

The conversion of biomass to light olefins on Fe-modified ZSM-5 catalyst: Effect of pyrolysis parameters.

PubMed

Zhang, Shihong; Yang, Mingfa; Shao, Jingai; Yang, Haiping; Zeng, Kuo; Chen, Yingquan; Luo, Jun; Agblevor, Foster A; Chen, Hanping

2018-07-01

Light olefins are the key building blocks for the petrochemical industry. In this study, the effects of in-situ and ex-situ process, temperature, Fe loading, catalyst to feed ratio and gas flow rate on the olefins carbon yield and selectivity were explored. The results showed that Fe-modified ZSM-5 catalyst increased the olefins yield significantly, and the ex-situ process was much better than in-situ. With the increasing of temperature, Fe-loading amount, catalyst to feed ratio, and gas flow rate, the carbon yields of light olefins were firstly increased and further decreased. The maximum carbon yield of light olefins (6.98% C-mol) was obtained at the pyrolysis temperature of 600°C, catalyst to feed ratio of 2, gas flow rate of 100ml/min, and 3wt% Fe/ZSM-5 for cellulose. The selectivity of C 2 H 4 was more than 60% for all feedstock, and the total light olefins followed the decreasing order of cellulose, corn stalk, hemicelluloses and lignin. Copyright © 2018 Elsevier B.V. All rights reserved.

Accretion in Close Pre-Main-Sequence Binaries

NASA Astrophysics Data System (ADS)

Ardila, David

2010-09-01

We propose to use COS to observe the circumbinary accretion flow in pre-main sequence binaries as a function of orbital phase. These observations will help us understand how the magnetosphere captures circumbinary gas, test model predictions regarding the importance of the mass ratio in directing the accretion flows, and study the kinematics of the gas filling the circumbinary gap. We will observe UZ Tau E {mass ratio q=0.3, e=0.33} and DQ Tau {q=1, e=0.58} in four phases, over three orbital periods, using G160M and G230L. The targets are Classical T Tauri stars for which the circumstellar disks are severely truncated. Our primary observables will be the CIV {1550 A} lines, formed at the footpoints of the accretion flow onto the star. We expect to observe the ebb and flow of the line shape, centroid, and flux as a function of orbital phase. The low-resolution NUV continuum observations will provide an independent measurement of the total accretion rate.

The drag force on a subsonic projectile in a fluid complex plasma

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

Ivlev, A. V.; Zhukhovitskii, D. I.

2012-09-15

The incompressible Navier-Stokes equation is employed to describe a subsonic particle flow induced in complex plasmas by a moving projectile. Drag forces acting on the projectile in different flow regimes are calculated. It is shown that, along with the regular neutral gas drag, there is an additional force exerted on the projectile due to dissipation in the surrounding particle fluid. This additional force provides significant contribution to the total drag.

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

Bosio, J.; Wilcox, P.; Sembsmoen, O.

A joint-venture, high-pressure, large-flow-rate facility to test, qualify, and research new natural-gas metering systems has been built by Den Norske Stats Oljeselskap A.S. (Statoil) and Total Marine Norsk A.S. Located near Haugesund in the Stavanger area, the lab, designated the Karsto Metering and Technology Laboratory, or K-Lab, is adjacent to Norway's first natural-gas-processing plant. It receives natural gas from across the Norwegian Trench from the Statfjord complex and after processing it sends it on to Emden, West Germany. The gas, which is produced in the North Sea, is transported to United Kingdom and the European continent through a high-pressure pipelinemore » network. The importance of gas-metering technology has been emphasized by oil and gas companies as well as by national regulatory authorities.« less

Flow Visualization of a Rotating Detonation Engine

DTIC Science & Technology

2016-10-05

2[b]), and a 3-dimensional (3-D) view around the injectors (2[c]). In this study, ethylene and oxygen were used as propellants. These gases were fed...1.0-mm radius; the ethylene injectors had a 0.8-mm radius. A total of 100 sets of injectors were installed at even intervals. The gases were injected...detonation wave, was filled with high-pressure, high-temperature burned gas. This high-pressure burned gas stopped the injection of ethylene and

Schlieren optical visualization for transient EHD induced flow in a stratified dielectric liquid under gas-phase ac corona discharges

NASA Astrophysics Data System (ADS)

Ohyama, R.; Inoue, K.; Chang, J. S.

2007-01-01

A flow pattern characterization of electrohydrodynamically (EHD) induced flow phenomena of a stratified dielectric fluid situated in an ac corona discharge field is conducted by a Schlieren optical system. A high voltage application to a needle-plate electrode arrangement in gas-phase normally initiates a conductive type EHD gas flow. Although the EHD gas flow motion initiated from the corona discharge electrode has been well known as corona wind, no comprehensive study has been conducted for an EHD fluid flow motion of the stratified dielectric liquid that is exposed to the gas-phase ac corona discharge. The experimentally observed result clearly presents the liquid-phase EHD flow phenomenon induced from the gas-phase EHD flow via an interfacial momentum transfer. The flow phenomenon is also discussed in terms of the gas-phase EHD number under the reduced gas pressure (reduced interfacial momentum transfer) conditions.

Gas-Dynamic Methods to Reduce Gas Flow Nonuniformity from the Annular Frames of Gas Turbine Engines

NASA Astrophysics Data System (ADS)

Kolmakova, D.; Popov, G.

2018-01-01

Gas flow nonuniformity is one of the main sources of rotor blade vibrations in the gas turbine engines. Usually, the flow circumferential nonuniformity occurs near the annular frames, located in the flow channel of the engine. This leads to the increased dynamic stresses in blades and consequently to the blade damage. The goal of the research was to find an acceptable method of reducing the level of gas flow nonuniformity. Two different methods were investigated during this research. Thus, this study gives the ideas about methods of improving the flow structure in gas turbine engine. Based on existing conditions (under development or existing engine) it allows the selection of the most suitable method for reducing gas flow nonuniformity.

Extracorporeal gas exchange and spontaneous breathing for the treatment of acute respiratory distress syndrome: an alternative to mechanical ventilation?*.

PubMed

Langer, Thomas; Vecchi, Vittoria; Belenkiy, Slava M; Cannon, Jeremy W; Chung, Kevin K; Cancio, Leopoldo C; Gattinoni, Luciano; Batchinsky, Andriy I

2014-03-01

Venovenous extracorporeal gas exchange is increasingly used in awake, spontaneously breathing patients as a bridge to lung transplantation. Limited data are available on a similar use of extracorporeal gas exchange in patients with acute respiratory distress syndrome. The aim of this study was to investigate the use of extracorporeal gas exchange in awake, spontaneously breathing sheep with healthy lungs and with acute respiratory distress syndrome and describe the interactions between the native lung (healthy and diseased) and the artificial lung (extracorporeal gas exchange) in this setting. Laboratory investigation. Animal ICU of a governmental laboratory. Eleven awake, spontaneously breathing sheep on extracorporeal gas exchange. Sheep were studied before (healthy lungs) and after the induction of acute respiratory distress syndrome via IV injection of oleic acid. Six gas flow settings (1-10 L/min), resulting in different amounts of extracorporeal CO2 removal (20-100% of total CO2 production), were tested in each animal before and after the injury. Respiratory variables and gas exchange were measured for every gas flow setting. Both healthy and injured sheep reduced minute ventilation according to the amount of extracorporeal CO2 removal, up to complete apnea. However, compared with healthy sheep, sheep with acute respiratory distress syndrome presented significantly increased esophageal pressure variations (25 ± 9 vs 6 ± 3 cm H2O; p < 0.001), which could be reduced only with very high amounts of CO2 removal (> 80% of total CO2 production). Spontaneous ventilation of both healthy sheep and sheep with acute respiratory distress syndrome can be controlled via extracorporeal gas exchange. If this holds true in humans, extracorporeal gas exchange could be used in awake, spontaneously breathing patients with acute respiratory distress syndrome to support gas exchange. A deeper understanding of the pathophysiology of spontaneous breathing during acute respiratory distress syndrome is however warranted in order to be able to propose extracorporeal gas exchange as a safe and valuable alternative to mechanical ventilation for the treatment of patients with acute respiratory distress syndrome.

Investigation of CNTD Silicon Nitride on Complex Shapes.

DTIC Science & Technology

1980-02-06

tubing) ! NH 3 + H 2 + N 2 SiCl4 + N2 Chamber Pressure, 4 2 To Manometer (copper tubing) t8 2 A: 2" DIA or 0 0 " To Pumping System _____________Pt/Pt-l3Rh...Total Gas Flow Rate: 47,350 cm3/min Gas Composition: N2 = 25,000 ml/min H2 = 20,600 ml/min Ar = 700 ml/min NH3 = 650 ml/min SiCl4 = 400 ml/min The...Values for SiCl4 were not available. In addition, the fractions of these two gases are extremely small in the overall gas composition. Individual

Xenon excimer emission from pulsed high-pressure capillary microdischarges

NASA Astrophysics Data System (ADS)

Lee, Byung-Joon; Rahaman, Hasibur; Petzenhauser, Isfried; Frank, Klaus; Giapis, Konstantinos P.

2007-06-01

Intense xenon vacuum ultraviolet (VUV) emission is observed from a high-pressure capillary cathode microdischarge in direct current operation, by superimposing a high-voltage pulse of 50ns duration. Under stagnant gas conditions, the total VUV light intensity increases linearly with pressure from 400 to 1013mbar for a fixed voltage pulse. At fixed pressure, however, the VUV light intensity increases superlinearly with voltage pulse height ranging from 08to2.8kV. Gains in emission intensity are obtained by inducing gas flow through the capillary cathode, presumably because of excimer dimer survival due to gas cooling.

Preparation of dielectric coating of variable dielectric constant by plasma polymerization

NASA Technical Reports Server (NTRS)

Hudis, M.; Wydeven, T. (Inventor)

1979-01-01

A plasma polymerization process for the deposition of a dielectric polymer coating on a substrate comprising disposing of the substrate in a closed reactor between two temperature controlled electrodes connected to a power supply is presented. A vacuum is maintained within the closed reactor, causing a monomer gas or gas mixture of a monomer and diluent to flow into the reactor, generating a plasma between the electrodes. The vacuum varies and controls the dielectric constant of the polymer coating being deposited by regulating the gas total and partial pressure, the electric field strength and frequency, and the current density.

Nonintrusive performance measurement of a gas turbine engine in real time

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

DeSilva, Upul P.; Claussen, Heiko

Performance of a gas turbine engine is monitored by computing a mass flow rate through the engine. Acoustic time-of-flight measurements are taken between acoustic transmitters and receivers in the flow path of the engine. The measurements are processed to determine average speeds of sound and gas flow velocities along those lines-of-sound. A volumetric flow rate in the flow path is computed using the gas flow velocities together with a representation of the flow path geometry. A gas density in the flow path is computed using the speeds of sound and a measured static pressure. The mass flow rate is calculatedmore » from the gas density and the volumetric flow rate.« less

Cold-air performance of a 15.41-cm-tip-diameter axial-flow power turbine with variable-area stator designed for a 75-kW automotive gas turbine engine

NASA Technical Reports Server (NTRS)

Mclallin, K. L.; Kofskey, M. G.; Wong, R. Y.

1982-01-01

An experimental evaluation of the aerodynamic performance of the axial flow, variable area stator power turbine stage for the Department of Energy upgraded automotive gas turbine engine was conducted in cold air. The interstage transition duct, the variable area stator, the rotor, and the exit diffuser were included in the evaluation of the turbine stage. The measured total blading efficiency was 0.096 less than the design value of 0.85. Large radial gradients in flow conditions were found at the exit of the interstage duct that adversely affected power turbine performance. Although power turbine efficiency was less than design, the turbine operating line corresponding to the steady state road load power curve was within 0.02 of the maximum available stage efficiency at any given speed.

Role of rough surface topography on gas slip flow in microchannels.

PubMed

Zhang, Chengbin; Chen, Yongping; Deng, Zilong; Shi, Mingheng

2012-07-01

We conduct a lattice Boltzmann simulation of gas slip flow in microchannels incorporating rough surface effects as characterized by fractal geometry with a focus on gas-solid interaction. The gas slip flow in rough microchannels, which is characterized by Poiseuille number and mass flow rate, is evaluated and compared with smooth microchannels. The effects of roughness height, surface fractal dimension, and Knudsen number on slip behavior of gas flow in microchannels are all investigated and discussed. The results indicate that the presence of surface roughness reduces boundary slip for gas flow in microchannels with respect to a smooth surface. The gas flows at the valleys of rough walls are no-slip while velocity slips are observed over the top of rough walls. We find that the gas flow behavior in rough microchannels is insensitive to the surface topography irregularity (unlike the liquid flow in rough microchannels) but is influenced by the statistical height of rough surface and rarefaction effects. In particular, decrease in roughness height or increase in Knudsen number can lead to large wall slip for gas flow in microchannels.

Drag reduction induced by superhydrophobic surfaces in turbulent pipe flow

NASA Astrophysics Data System (ADS)

Costantini, Roberta; Mollicone, Jean-Paul; Battista, Francesco

2018-02-01

The drag reduction induced by superhydrophobic surfaces is investigated in a turbulent pipe flow. Wetted superhydrophobic surfaces are shown to trap gas bubbles in their asperities. This stops the liquid from coming in direct contact with the wall in that location, allowing the flow to slip over the air bubbles. We consider a well-defined texture with streamwise grooves at the walls in which the gas is expected to be entrapped. This configuration is modeled with alternating no-slip and shear-free boundary conditions at the wall. With respect to the classical turbulent pipe flow, a substantial drag reduction is observed which strongly depends on the grooves' dimension and on the solid fraction, i.e., the ratio between the solid wall surface and the total surface of the pipe's circumference. The drag reduction is due to the mean slip velocity at the wall which increases the flow rate at a fixed pressure drop. The enforced boundary conditions also produce peculiar turbulent structures which on the contrary decrease the flow rate. The two concurrent effects provide an overall flow rate increase as demonstrated by means of the mean axial momentum balance. This equation provides the balance between the mean pressure gradient, the Reynolds stress, the mean flow rate, and the mean slip velocity contributions.

DISTRIBUTION OF THE TEMPERATURE IN THE ASH-GAS FLOW DURING KORYAKSKY VOLCANO ERUPTION IN 2009

NASA Astrophysics Data System (ADS)

Gordeev, E.; Droznin, V.

2009-12-01

The observations of the ash-gas plumes during the Koryaksky eruption in March 2009 by the high resolution thermovision camera allowed obtaining thermal distributions inside the ash-gas flows. The plume structure is formed by single emissions. They rise at the rate of 5.5-7 m/s. The plume structure in general is represented as 3 zones: 1. a zone of high heat exchange; 2. a zone of floating up; 3. a zone of lateral movement. The plume temperature within the zone of lateral movement exceeds the atmospheric temperature by 3-5 oC, within the zone of floating up it exceeds by 20 oC. Its rate within the zone of floating up comprises 5-7 m/s. At the boundary between the zones of high heat exchange and floating up where we know the plume section, from heat balance equation we can estimate steam rate and heat power of the fluid thermal flow. Power of the overheated steam was estimated as Q=35 kg/s. It forms the ash-gas plume from the eruption and has temperature equal to 450 oC. The total volume of water steam produced during 100 days of eruption was estimated 3*105 t, its energy - 109 MJ.

Groundwater remediation engineering sparging using acetylene--study on the flow distribution of air.

PubMed

Zheng, Yan-Mei; Zhang, Ying; Huang, Guo-Qiang; Jiang, Bin; Li, Xin-Gang

2005-01-01

Air sparging (AS) is an emerging method to remove VOCs from saturated soils and groundwater. Air sparging performance highly depends on the air distribution resulting in the aquifer. In order to study gas flow characterization, a two-dimensional experimental chamber was designed and installed. In addition, the method by using acetylene as the tracer to directly image the gas distribution results of AS process has been put forward. Experiments were performed with different injected gas flow rates. The gas flow patterns were found to depend significantly on the injected gas flow rate, and the characterization of gas flow distributions in porous media was very different from the acetylene tracing study. Lower and higher gas flow rates generally yield more irregular in shape and less effective gas distributions.

Micro/Nano-pore Network Analysis of Gas Flow in Shale Matrix

PubMed Central

Zhang, Pengwei; Hu, Liming; Meegoda, Jay N.; Gao, Shengyan

2015-01-01

The gas flow in shale matrix is of great research interests for optimized shale gas extraction. The gas flow in the nano-scale pore may fall in flow regimes such as viscous flow, slip flow and Knudsen diffusion. A 3-dimensional nano-scale pore network model was developed to simulate dynamic gas flow, and to describe the transient properties of flow regimes. The proposed pore network model accounts for the various size distributions and low connectivity of shale pores. The pore size, pore throat size and coordination number obey normal distribution, and the average values can be obtained from shale reservoir data. The gas flow regimes were simulated using an extracted pore network backbone. The numerical results show that apparent permeability is strongly dependent on pore pressure in the reservoir and pore throat size, which is overestimated by low-pressure laboratory tests. With the decrease of reservoir pressure, viscous flow is weakening, then slip flow and Knudsen diffusion are gradually becoming dominant flow regimes. The fingering phenomenon can be predicted by micro/nano-pore network for gas flow, which provides an effective way to capture heterogeneity of shale gas reservoir. PMID:26310236

Micro/Nano-pore Network Analysis of Gas Flow in Shale Matrix.

PubMed

Zhang, Pengwei; Hu, Liming; Meegoda, Jay N; Gao, Shengyan

2015-08-27

The gas flow in shale matrix is of great research interests for optimized shale gas extraction. The gas flow in the nano-scale pore may fall in flow regimes such as viscous flow, slip flow and Knudsen diffusion. A 3-dimensional nano-scale pore network model was developed to simulate dynamic gas flow, and to describe the transient properties of flow regimes. The proposed pore network model accounts for the various size distributions and low connectivity of shale pores. The pore size, pore throat size and coordination number obey normal distribution, and the average values can be obtained from shale reservoir data. The gas flow regimes were simulated using an extracted pore network backbone. The numerical results show that apparent permeability is strongly dependent on pore pressure in the reservoir and pore throat size, which is overestimated by low-pressure laboratory tests. With the decrease of reservoir pressure, viscous flow is weakening, then slip flow and Knudsen diffusion are gradually becoming dominant flow regimes. The fingering phenomenon can be predicted by micro/nano-pore network for gas flow, which provides an effective way to capture heterogeneity of shale gas reservoir.

Discharge characteristics and hydrodynamics behaviors of atmospheric plasma jets produced in various gas flow patterns

NASA Astrophysics Data System (ADS)

Setsuhara, Yuichi; Uchida, Giichiro; Nakajima, Atsushi; Takenaka, Kosuke; Koga, Kazunori; Shiratani, Masaharu

2015-09-01

Atmospheric nonequilibrium plasma jets have been widely employed in biomedical applications. For biomedical applications, it is an important issue to understand the complicated mechanism of interaction of the plasma jet with liquid. In this study, we present analysis of the discharge characteristics of a plasma jet impinging onto the liquid surface under various gas flow patterns such as laminar and turbulence flows. For this purpose, we analyzed gas flow patters by using a Schlieren gas-flow imaging system in detail The plasma jet impinging into the liquid surface expands along the liquid surface. The diameter of the expanded plasma increases with gas flow rate, which is well explained by an increase in the diameter of the laminar gas-flow channel. When the gas flow rate is further increased, the gas flow mode transits from laminar to turbulence in the gas flow channel, which leads to the shortening of the plasm-jet length. Our experiment demonstrated that the gas flow patterns strongly affect the discharge characteristics in the plasma-jet system. This study was partly supported by a Grant-in-Aid for Scientific Research on Innovative Areas ``Plasma Medical Innovation'' (24108003) from the Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT).

Assessment of total efficiency in adiabatic engines

NASA Astrophysics Data System (ADS)

Mitianiec, W.

2016-09-01

The paper presents influence of ceramic coating in all surfaces of the combustion chamber of SI four-stroke engine on working parameters mainly on heat balance and total efficiency. Three cases of engine were considered: standard without ceramic coating, fully adiabatic combustion chamber and engine with different thickness of ceramic coating. Consideration of adiabatic or semi-adiabatic engine was connected with mathematical modelling of heat transfer from the cylinder gas to the cooling medium. This model takes into account changeable convection coefficient based on the experimental formulas of Woschni, heat conductivity of multi-layer walls and also small effect of radiation in SI engines. The simulation model was elaborated with full heat transfer to the cooling medium and unsteady gas flow in the engine intake and exhaust systems. The computer program taking into account 0D model of engine processes in the cylinder and 1D model of gas flow was elaborated for determination of many basic engine thermodynamic parameters for Suzuki DR-Z400S 400 cc SI engine. The paper presents calculation results of influence of the ceramic coating thickness on indicated pressure, specific fuel consumption, cooling and exhaust heat losses. Next it were presented comparisons of effective power, heat losses in the cooling and exhaust systems, total efficiency in function of engine rotational speed and also comparison of temperature inside the cylinder for standard, semi-adiabatic and full adiabatic engine. On the basis of the achieved results it was found higher total efficiency of adiabatic engines at 2500 rpm from 27% for standard engine to 37% for full adiabatic engine.

AMBIENT CARBON MONOXIDE MONITOR

EPA Science Inventory

A portable instrument has been designed and two units have been built to monitor the concentration of CO in ambient air. The air flows through a sampling section that is approximately 43 cm long with a 28-pass optical system that produces a total path of 12 meters. Gas-filter cor...

Quantifying Hydrate Formation in Gas-rich Environments Using the Method of Characteristics

NASA Astrophysics Data System (ADS)

You, K.; Flemings, P. B.; DiCarlo, D. A.

2015-12-01

Methane hydrates hold a vast amount of methane globally, and have huge energy potential. Methane hydrates in gas-rich environments are the most promising production targets. We develop a one-dimensional analytical solution based on the method of characteristics to explore hydrate formation in such environments (Figure 1). Our solution shows that hydrate saturation is constant with time and space in a homogeneous system. Hydrate saturation is controlled by the initial thermodynamic condition of the system, and changed by the gas fractional flow. Hydrate saturation increases with the initial distance from the hydrate phase boundary. Different gas fractional flows behind the hydrate solidification front lead to different gas saturations at the hydrate solidification front. The higher the gas saturation at the front, the less the volume available to be filled by hydrate, and hence the lower the hydrate saturation. The gas fractional flow depends on the relative permeability curves, and the forces that drive the flow. Viscous forces (the drive for flow induced from liquid pressure gradient) dominate the flow, and hydrate saturation is independent on the gas supply rates and the flow directions at high gas supply rates. Hydrate saturation can be estimated as one minus the ratio of the initial to equilibrium salinity. Gravity forces (the drive for flow induced from the gravity) dominate the flow, and hydrate saturation depends on the flow rates and the flow directions at low gas supply rates. Hydrate saturation is highest for upward flow, and lowest for downward flow. Hydrate saturation decreases with the flow rate for upward flow, and increases with the flow rate for downward flow. This analytical solution illuminates how hydrate is formed by gas (methane, CO2, ethane, propane) flowing into brine-saturated sediments at both the laboratory and geological scales (Figure 1). It provides an approach to generalize the understanding of hydrate solidification in gas-rich environments, although complicated numerical models have been developed previously. Examples of gas expulsion into hydrate stability zones and the associated hydrate formation in both laboratory and geological scales, and CO2 sequestration into CO2-hydrates near the seafloor and under the permafrost will be presented.

Flowfield and heat transfer past an unshrouded gas turbine blade tip with different shapes

NASA Astrophysics Data System (ADS)

Liu, Jian-Jun; Li, Peng; Zhang, Chao; An, Bai-Tao

2013-04-01

This paper describes the numerical investigations of flow and heat transfer in an unshrouded turbine rotor blade of a heavy duty gas turbine with four tip configurations. By comparing the calculated contours of heat transfer coefficients on the flat tip of the HP turbine rotor blade in the GE-E3 aircraft engine with the corresponding experimental data, the κ-ω turbulence model was chosen for the present numerical simulations. The inlet and outlet boundary conditions for the turbine rotor blade are specified as the real gas turbine, which were obtained from the 3D full stage simulations. The rotor blade and the hub endwall are rotary and the casing is stationary. The influences of tip configurations on the tip leakage flow and blade tip heat transfer were discussed. It's showed that the different tip configurations changed the leakage flow patterns and the pressure distributions on the suction surface near the blade tip. Compared with the flat tip, the total pressure loss caused by the leakage flow was decreased for the full squealer tip and pressure side squealer tip, while increased for the suction side squealer tip. The suction side squealer tip results in the lowest averaged heat transfer coefficient on the blade tip compared to the other tip configurations.

Flow conditioner for fuel injector for combustor and method for low-NO.sub.x combustor

DOEpatents

Dutta, Partha; Smith, Kenneth O.; Ritz, Frank J.

2013-09-10

An injector for a gas turbine combustor including a catalyst coated surface forming a passage for feed gas flow and a channel for oxidant gas flow establishing an axial gas flow through a flow conditioner disposed at least partially within an inner wall of the injector. The flow conditioner includes a length with an interior passage opening into upstream and downstream ends for passage of the axial gas flow. An interior diameter of the interior passage smoothly reduces and then increases from upstream to downstream ends.

Measurement of Turbulent Pressure and Temperature Fluctuations in a Gas Turbine Combustor

NASA Technical Reports Server (NTRS)

Povinelli, Louis (Technical Monitor); LaGraff, John E.; Bramanti, Cristina; Pldfield, Martin; Passaro, Andrea; Biagioni, Leonardo

2004-01-01

The report summarizes the results of the redesign efforts directed towards the gas-turbine combustor rapid-injector flow diagnostic probe developed under sponsorship of NASA-GRC and earlier reported in NASA-CR-2003-212540. Lessons learned during the theoretical development, developmental testing and field-testing in the previous phase of this research were applied to redesign of both the probe sensing elements and of the rapid injection device. This redesigned probe (referred to herein as Turboprobe) has been fabricated and is ready, along with the new rapid injector, for field-testing. The probe is now designed to capture both time-resolved and mean total temperatures, total pressures and, indirectly, one component of turbulent fluctuations.

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.

Reduction of gas flow nonuniformity in gas turbine engines by means of gas-dynamic methods

NASA Astrophysics Data System (ADS)

Matveev, V.; Baturin, O.; Kolmakova, D.; Popov, G.

2017-08-01

Gas flow nonuniformity is one of the main sources of rotor blade vibrations in the gas turbine engines. Usually, the flow circumferential nonuniformity occurs near the annular frames, located in the flow channel of the engine. This leads to the increased dynamic stresses in blades and as a consequence to the blade damage. The goal of the research was to find an acceptable method of reducing the level of gas flow nonuniformity as the source of dynamic stresses in the rotor blades. Two different methods were investigated during this research. Thus, this study gives the ideas about methods of improving the flow structure in gas turbine engine. On the basis of existing conditions (under development or existing engine) it allows the selection of the most suitable method for reducing gas flow nonuniformity.

Propagation and Interactions of Ultrahigh Power Light: Relativistic Nonlinear Optics

DTIC Science & Technology

2014-09-30

energy electron beams [16,17]. In the simplest implementation, a 2-mm supersonic nozzle is used to produce a high density gas flow (ne=10 19 cm-3...was a high-density jet of neutral helium produced by a 3 or 4 mm-diameter supersonic Laval nozzle . The neutral density profile (characterized...250 MeV and total charge of 0.1 nC (>50 MeV) Figure 7: (a) Gas target profiles, measured using tomography, at a height of 2 mm above the nozzle

Eruption mass estimation using infrasound waveform inversion and ash and gas measurements: Evaluation at Sakurajima Volcano, Japan

NASA Astrophysics Data System (ADS)

Fee, David; Izbekov, Pavel; Kim, Keehoon; Yokoo, Akihiko; Lopez, Taryn; Prata, Fred; Kazahaya, Ryunosuke; Nakamichi, Haruhisa; Iguchi, Masato

2017-12-01

Eruption mass and mass flow rate are critical parameters for determining the aerial extent and hazard of volcanic emissions. Infrasound waveform inversion is a promising technique to quantify volcanic emissions. Although topography may substantially alter the infrasound waveform as it propagates, advances in wave propagation modeling and station coverage permit robust inversion of infrasound data from volcanic explosions. The inversion can estimate eruption mass flow rate and total eruption mass if the flow density is known. However, infrasound-based eruption flow rates and mass estimates have yet to be validated against independent measurements, and numerical modeling has only recently been applied to the inversion technique. Here we present a robust full-waveform acoustic inversion method, and use it to calculate eruption flow rates and masses from 49 explosions from Sakurajima Volcano, Japan. Six infrasound stations deployed from 12-20 February 2015 recorded the explosions. We compute numerical Green's functions using 3-D Finite Difference Time Domain modeling and a high-resolution digital elevation model. The inversion, assuming a simple acoustic monopole source, provides realistic eruption masses and excellent fit to the data for the majority of the explosions. The inversion results are compared to independent eruption masses derived from ground-based ash collection and volcanic gas measurements. Assuming realistic flow densities, our infrasound-derived eruption masses for ash-rich eruptions compare favorably to the ground-based estimates, with agreement ranging from within a factor of two to one order of magnitude. Uncertainties in the time-dependent flow density and acoustic propagation likely contribute to the mismatch between the methods. Our results suggest that realistic and accurate infrasound-based eruption mass and mass flow rate estimates can be computed using the method employed here. If accurate volcanic flow parameters are known, application of this technique could be broadly applied to enable near real-time calculation of eruption mass flow rates and total masses. These critical input parameters for volcanic eruption modeling and monitoring are not currently available.

Modeling Total Dissolved Gas for Optimal Operation of Multireservoir Systems

DOE PAGES

Politano, Marcela; Castro, Alejandro; Hadjerioua, Boualem

2017-02-09

One important environmental issue of hydropower in the Columbia and Snake River Basins (Pacific Northwest region of United States) is elevated total dissolved gas (TDG) downstream of a dam, which has the potential to cause gas bubble disease in affected fish. Gas supersaturation in the Columbia River Basin primarily occurs due to dissolution of bubbles entrained during spill events. This paper presents a physically based TDG model that can be used to optimize spill operations in multireservoir hydropower systems. Independent variables of the model are forebay TDG, tailwater elevation, spillway and powerhouse discharges, project head, and environmental parameters such asmore » temperature and atmospheric pressure. The model contains seven physically meaningful experimental parameters, which were calibrated and validated against TDG data collected downstream of Rock Island Dam (Washington) from 2008 to 2012. In conclusion, a sensitivity analysis was performed to increase the understanding of the relationships between TDG downstream of the dam and processes such as air entrainment, lateral powerhouse flow, and dissolution.« less

Electrochemical cell operation and system

DOEpatents

Maru, Hansraj C.

1980-03-11

Thermal control in fuel cell operation is affected through sensible heat of process gas by providing common input manifolding of the cell gas flow passage in communication with the cell electrolyte and an additional gas flow passage which is isolated from the cell electrolyte and in thermal communication with a heat-generating surface of the cell. Flow level in the cell gas flow passage is selected based on desired output electrical energy and flow level in the additional gas flow passage is selected in accordance with desired cell operating temperature.

Feasibility of Rayleigh Scattering Flow Diagnostics in the National Transonic Facility

NASA Technical Reports Server (NTRS)

Herring, Gregory C.; Lee, Joseph W.; Goad, William K.

2015-01-01

Laser-based Rayleigh light scattering (RLS) was performed in the National Transonic Facility (NTF) at NASA Langley Research Center. The goal was to determine if the free-stream flow undergoes clustering (early stage of condensation from gas to liquid) or remains in a pure diatomic molecular phase. Data indicate that clusters are not observable down to levels of 10% of the total light scatter for a variety of total pressures at one N2 cryogenic-mode total temperature (Tt = -50 F = 227 K) and one air-mode temperature (Tt = +130 F = 327 K). Thus RLS appears viable as a qualitative or quantitative diagnostic for flow density in NTF in the future. Particles are distinguished from optically unresolvable clusters because they are much larger and individually resolvable in the laser beam image with Mie scattering. The same RLS apparatus was also used, without modification, to visualize naturally occurring particles entrained in the flow for both cryogenic and air-modes. Estimates of the free-stream particle flux are presented, which may be important for interpretation of laminar-to-turbulent boundary-layer transition studies. 1

In situ biogas stripping of ammonia from a digester using a gas mixing system.

PubMed

Serna-Maza, Alba; Heaven, Sonia; Banks, Charles J

2017-12-01

Previous studies have suggested the use of digester biogas mixing systems for in situ ammonia removal from anaerobic digestates. The feasibility of this was tested at moderate and complete gas mixing rates at mesophilic and thermophilic temperatures in a 75-L digester. Experimental results showed that at gas mixing rates typical of full-scale commercial digesters the reduction in total ammonia nitrogen concentrations would be insufficient to allow stable acetoclastic methanogenesis in mesophilic conditions, or to prevent total inhibition of methanogenic activity in thermophilic food waste digestion. Simulation based on batch column stripping experiments at 55°C at gas violent flow rates of 0.032 m 3  m -2  min -1 indicated that ammonia concentrations could be reduced below inhibitory values in thermophilic food waste digestion for organic loading rates of up to 6 kg VS m -3  day -1 . These mixing rates are far in excess of those used in full-scale gas-mixed digesters and may not be operationally or commercially feasible.

Numerical Analysis of the Trailblazer Inlet Flowfield for Hypersonic Mach Numbers

NASA Technical Reports Server (NTRS)

Steffen, C. J., Jr.; DeBonis, J. R.

1999-01-01

A study of the Trailblazer vehicle inlet was conducted using the Global Air Sampling Program (GASP) code for flight Mach numbers ranging from 4-12. Both perfect gas and finite rate chemical analysis were performed with the intention of making detailed comparisons between the two results. Inlet performance was assessed using total pressure recovery and kinetic energy efficiency. These assessments were based upon a one-dimensional stream-thrust-average of the axisymmetric flowfield. Flow visualization utilized to examine the detailed shock structures internal to this mixed-compression inlet. Kinetic energy efficiency appeared to be the least sensitive to differences between the perfect gas and finite rate chemistry results. Total pressure recovery appeared to be the most sensitive discriminator between the perfect gas and finite rate chemistry results for flight Mach numbers above Mach 6. Adiabatic wall temperature was consistently overpredicted by the perfect gas model for flight Mach numbers above Mach 4. The predicted shock structures were noticeably different for Mach numbers from 6-12. At Mach 4, the perfect gas and finite rate chemistry models collapse to the same result.

Feasibility Study for a Practical High Rotor Tip Clearance Turbine.

DTIC Science & Technology

GAS TURBINE BLADES ), (* TURBINE BLADES , TOLERANCES(MECHANICS)), (* TURBOFAN ENGINES , GAS TURBINES , AXIAL FLOW TURBINES , AXIAL FLOW TURBINE ROTORS...AERODYNAMIC CONFIGURATIONS, LEAKAGE(FLUID), MEASUREMENT, TEST METHODS, PERFORMANCE( ENGINEERING ), MATHEMATICAL PREDICTION, REDUCTION, PRESSURE, PREDICTIONS, NOZZLE GAS FLOW, COMBUSTION CHAMBER GASES, GAS FLOW.

DEVELOPMENT OF A PROPORTIONAL SAMPLER FOR AUTOMOBILE EXHAUST EMISSIONS TESTING

EPA Science Inventory

The report describes the development of a device that is capable of sampling gaseous emissions from automobiles. The device samples exhaust gases at a mass rate that is proportional to the total exhaust gas mass flow rate, which is measured using an ultrasonic vortex flowmeter. T...

Algorithm For Hypersonic Flow In Chemical Equilibrium

NASA Technical Reports Server (NTRS)

Palmer, Grant

1989-01-01

Implicit, finite-difference, shock-capturing algorithm calculates inviscid, hypersonic flows in chemical equilibrium. Implicit formulation chosen because overcomes limitation on mathematical stability encountered in explicit formulations. For dynamical portion of problem, Euler equations written in conservation-law form in Cartesian coordinate system for two-dimensional or axisymmetric flow. For chemical portion of problem, equilibrium state of gas at each point in computational grid determined by minimizing local Gibbs free energy, subject to local conservation of molecules, atoms, ions, and total enthalpy. Major advantage: resulting algorithm naturally stable and captures strong shocks without help of artificial-dissipation terms to damp out spurious numerical oscillations.

[CFD numerical simulation onto the gas-liquid two-phase flow behavior during vehicle refueling process].

PubMed

Chen, Jia-Qing; Zhang, Nan; Wang, Jin-Hui; Zhu, Ling; Shang, Chao

2011-12-01

With the gradual improvement of environmental regulations, more and more attentions are attracted to the vapor emissions during the process of vehicle refueling. Research onto the vehicle refueling process by means of numerical simulation has been executed abroad since 1990s, while as it has never been involved so far domestically. Through reasonable simplification about the physical system of "Nozzle + filler pipe + gasoline storage tank + vent pipe" for vehicle refueling, and by means of volume of fluid (VOF) model for gas-liquid two-phase flow and Re-Normalization Group kappa-epsilon turbulence flow model provided in commercial computational fluid dynamics (CFD) software Fluent, this paper determined the proper mesh discretization scheme and applied the proper boundary conditions based on the Gambit software, then established the reasonable numerical simulation model for the gas-liquid two-phase flow during the refueling process. Through discussing the influence of refueling velocity on the static pressure of vent space in gasoline tank, the back-flowing phenomenon has been revealed in this paper. It has been demonstrated that, the more the flow rate and the refueling velocity of refueling nozzle is, the higher the gross static pressure in the vent space of gasoline tank. In the meanwhile, the variation of static pressure in the vent space of gasoline tank can be categorized into three obvious stages. When the refueling flow rate becomes higher, the back-flowing phenomenon of liquid gasoline can sometimes be induced in the head section of filler pipe, thus making the gasoline nozzle pre-shut-off. Totally speaking, the theoretical work accomplished in this paper laid some solid foundation for self-researching and self-developing the technology and apparatus for the vehicle refueling and refueling emissions control domestically.

Film Cooling Flow Effects on Post-Combustor Trace Chemistry

NASA Technical Reports Server (NTRS)

Wey, Thomas; Liu, Nan-Suey

2003-01-01

Film cooling injection is widely applied in the thermal design of turbomachinery, as it contributes to achieve higher operating temperature conditions of modern gas turbines, and to meet the requirements for reliability and life cycles. It is a significant part of the high-pressure turbine system. The film cooling injection, however, interacts with the main flow and is susceptible to have an influence on the aerodynamic performance of the cooled components, and through that may cause a penalty on the overall efficiency of the gas turbine. The main reasons are the loss of total pressure resulting from mixing the cooling air with mainstream and the reduction of the gas stagnation temperature at the exit of the combustion chamber to a lower value at the exit of nozzle guide vane. In addition, the impact of the injected air on the evolution of the trace species of the hot gas is not yet quite clear. This work computationally investigates the film cooling influence on post-combustor trace chemistry, as trace species in aircraft exhaust affect climate and ozone.

Simulating the gas hydrate production test at Mallik using the pilot scale pressure reservoir LARS

NASA Astrophysics Data System (ADS)

Heeschen, Katja; Spangenberg, Erik; Schicks, Judith M.; Priegnitz, Mike; Giese, Ronny; Luzi-Helbing, Manja

2014-05-01

LARS, the LArge Reservoir Simulator, allows for one of the few pilot scale simulations of gas hydrate formation and dissociation under controlled conditions with a high resolution sensor network to enable the detection of spatial variations. It was designed and built within the German project SUGAR (submarine gas hydrate reservoirs) for sediment samples with a diameter of 0.45 m and a length of 1.3 m. During the project, LARS already served for a number of experiments simulating the production of gas from hydrate-bearing sediments using thermal stimulation and/or depressurization. The latest test simulated the methane production test from gas hydrate-bearing sediments at the Mallik test site, Canada, in 2008 (Uddin et al., 2011). Thus, the starting conditions of 11.5 MPa and 11°C and environmental parameters were set to fit the Mallik test site. The experimental gas hydrate saturation of 90% of the total pore volume (70 l) was slightly higher than volumes found in gas hydrate-bearing formations in the field (70 - 80%). However, the resulting permeability of a few millidarcy was comparable. The depressurization driven gas production at Mallik was conducted in three steps at 7.0 MPa - 5.0 MPa - 4.2 MPa all of which were used in the laboratory experiments. In the lab the pressure was controlled using a back pressure regulator while the confining pressure was stable. All but one of the 12 temperature sensors showed a rapid decrease in temperature throughout the sediment sample, which accompanied the pressure changes as a result of gas hydrate dissociation. During step 1 and 2 they continued up to the point where gas hydrate stability was regained. The pressure decreases and gas hydrate dissociation led to highly variable two phase fluid flow throughout the duration of the simulated production test. The flow rates were measured continuously (gas) and discontinuously (liquid), respectively. Next to being discussed here, both rates were used to verify a model of gas hydrate dissociation applying the foamy oil approach, a method earlier adopted to model the Mallik production test (see abstract Abendroth et al., this volume). Combined with a dense set of data from a cylindrical electrical resistance tomography (ERT) array (see abstract Priegnitz et al., this volume), very valuable information were gained on the spatial as well as temporal formation and dissociation of gas hydrates as well as changes in permeability and resulting pathways for the fluid flow. Here we present the set-up and execution of the experiment and discuss the results from temperature and flow measurements with respect to the gas hydrate dissociation and characteristics of resulting fluid flow. Uddin, M., Wright, F., and Coombe, D. 2011. Numerical Study of Gas Evolution and Transport Behaviours in Natural Gas-Hydrate Reservoirs. Journal of Canadian Petroleum Technology 50, 70-89.

Reduced gas accretion on super-Earths and ice giants

NASA Astrophysics Data System (ADS)

Lambrechts, M.; Lega, E.

2017-10-01

A large fraction of giant planets have gaseous envelopes that are limited to about 10% of their total mass budget. Such planets are present in the solar system (Uranus, Neptune) and are frequently observed in short periods around other stars (the so-called super-Earths). In contrast to these observations, theoretical calculations based on the evolution of hydrostatic envelopes argue that such low-mass envelopes cannot be maintained around cores exceeding five Earth masses. Instead, under nominal disk conditions, these planets would acquire massive envelopes through runaway gas accretion within the lifetime of the protoplanetary disk. In this work we show that planetary envelopes are not in hydrostatic balance, which slows down envelope growth. A series of 3D global, radiative hydrodynamical simulations reveal a steady-state gas flow, which enters through the poles and exits in the disk midplane. Gas is pushed through the outer envelope in about ten orbital timescales. In regions of the disk that are not significantly dust-depleted, envelope accretion onto cores of about five Earth masses can get stalled as the gas flow enters the deep interior. Accreted solids sublimate deep in the convective interior, but small opacity-providing grains are trapped in the flow and do not settle, which further prevents rapid envelope accretion. The transition to runaway gas accretion can however be reached when cores grow larger than typical super-Earths, beyond 15 Earth masses, and preferably when disk opacities are below κ = 1 cm2/g. These findings offer an explanation for the typical low-mass envelopes around the cores of super-Earths.

Effects of neutral distribution and external magnetic field on plasma momentum in electrodeless plasma thrusters

NASA Astrophysics Data System (ADS)

Takase, Kazuki; Takahashi, Kazunori; Takao, Yoshinori

2018-02-01

The effects of neutral distribution and an external magnetic field on plasma distribution and thruster performance are numerically investigated using a particle-in-cell simulation with Monte Carlo collisions (PIC-MCC) and the direct simulation Monte Carlo (DSMC) method. The modeled thruster consists of a quartz tube 1 cm in diameter and 3 cm in length, where a double-turn rf loop antenna is wound at the center of the tube and a solenoid is placed between the loop antenna and the downstream tube exit. A xenon propellant is introduced from both the upstream and downstream sides of the thruster, and the flow rates are varied while maintaining the total gas flow rate of 30 μg/s. The PIC-MCC calculations have been conducted using the neutral distribution obtained from the DSMC calculations, which were applied with different strengths of the magnetic field. The numerical results show that both the downstream gas injection and the external magnetic field with a maximum strength near the thruster exit lead to a shift of the plasma density peak from the upstream to the downstream side. Consequently, a larger total thrust is obtained when increasing the downstream gas injection and the magnetic field strength, which qualitatively agrees with a previous experiment using a helicon plasma source.

A High-Speed Continuous Recording High Flow Gas Sampler for Measuring Methane Emissions from Pneumatic Devices at Oil and Natural Gas Production Facilities

NASA Astrophysics Data System (ADS)

Ferrara, T.; Howard, T. M.

2016-12-01

Studies attempting to reconcile facility level emission estimates of sources at oil and gas facilities with basin wide methane flux measurements have had limited success. Pneumatic devices are commonly used at oil and gas production facilities for process control or liquid pumping. These devices are powered by pressurized natural gas from the well, so they are known methane sources at these sites. Pneumatic devices are estimated to contribute 14% to 25% of the total greenhouse gas emissions (GHG) from production facilities. Measurements of pneumatic devices have shown that malfunctioning or poorly maintained control systems may be emitting significantly more methane than currently estimated. Emission inventories for these facilities use emission factors from EPA that are based on pneumatic device measurements made in the early 1990's. Recent studies of methane emissions from production facilities have attempted to measure emissions from pneumatic devices by several different methods. These methods have had limitations including alteration of the system being measured, the inability to distinguish between leaks and venting during normal operation, or insufficient response time to account of the time based emission events. We have developed a high speed recording high flow sampler that is capable of measuring the transient emissions from pneumatic devices. This sampler is based on the well-established high flow measurement technique used in oil and gas for quantifying component leak rates. In this paper we present the results of extensive laboratory controlled release testing. Additionally, test data from several field studies where this sampler has been used to measure pneumatic device emissions will be presented.

Performance of a hydrogen burner to simulate air entering scramjet combustors. [simulation of total temperature, total pressure, and volume fraction of oxygen of air at flight conditions

NASA Technical Reports Server (NTRS)

Russin, W. R.

1974-01-01

Tests were conducted to determine the performance of a hydrogen burner used to produce a test gas that simulates air entering a scramjet combustor at various flight conditions. The test gas simulates air in that it duplicates the total temperature, total pressure, and the volume fraction of oxygen of air at flight conditions. The main objective of the tests was to determine the performance of the burner as a function of the effective exhaust port area. The conclusions were: (1) pressure oscillations of the chugging type were reduced in amplitude to plus or minus 2 percent of the mean pressure level by proper sizing of hydrogen, oxygen, and air injector flow areas; (2) combustion efficiency remained essentially constant as the exhaust port area was increased by a factor of 3.4; (3) the mean total temperature determined from integrating the exit radial gas property profiles was within plus or minus 5 percent of the theoretical bulk total temperature; (4) the measured exit total temperature profile had a local peak temperature more than 30 percent greater than the theoretical bulk total temperature; and (5) measured heat transfer to the burner liner was 75 percent of that predicted by theory based on a flat radial temperature profile.

Process and apparatus for separation of components of a gas stream

DOEpatents

Bryan, Charles R.; Torczynski, John R.; Brady, Patrick V.; Gallis, Michail; Brooks, Carlton F.

2014-06-17

A process and apparatus for separating a gas mixture comprising providing a slot in a gas separation channel (conceptualized as a laterally elongated Clusius-Dickel column), having a length through which a net cross-flow of the gas mixture may be established; applying a higher temperature to one side of the channel and a lower temperature on an opposite side of the channel thereby causing thermal-diffusion and buoyant-convection flow to occur in the slot; and establishing a net cross-flow of a gas mixture comprising at least one higher density gas component and at least one lower density gas component along the length of the slot, wherein the cross-flow causes, in combination with the convection flow, a spiraling flow in the slot; and wherein the spiral flow causes an increasing amount of separation of the higher density gas from the lower density gas along the length of the channel. The process may use one or more slots and/or channels.

Process and apparatus for separation of components of a gas stream

DOEpatents

Bryan, Charles R; Torczynski, John R; Brady, Patrick V; Gallis, Michail; Brooks, Carlton F

2013-09-17

A process and apparatus for separating a gas mixture comprising providing a slot in a gas separation channel (conceptualized as a laterally elongated Clusius-Dickel column), having a length through which a net cross-flow of the gas mixture may be established; applying a higher temperature to one side of the channel and a lower temperature on an opposite side of the channel thereby causing thermal-diffusion and buoyant-convection flow to occur in the slot; and establishing a net cross-flow of a gas mixture comprising at least one higher density gas component and at least one lower density gas component along the length of the slot, wherein the cross-flow causes, in combination with the convection flow, a spiraling flow in the slot; and wherein the spiral flow causes an increasing amount of separation of the higher density gas from the lower density gas along the length of the channel. The process may use one or more slots and/or channels.

Process and apparatus for separation of components of a gas stream

DOEpatents

Bryan, Charles R; Torczynski, John R; Brady, Patrick V; Gallis, Michail; Brooks, Carlton F

2013-11-19

A process and apparatus for separating a gas mixture comprising providing a slot in a gas separation channel (conceptualized as a laterally elongated Clusius-Dickel column), having a length through which a net cross-flow of the gas mixture may be established; applying a higher temperature to one side of the channel and a lower temperature on an opposite side of the channel thereby causing thermal-diffusion and buoyant-convection flow to occur in the slot; and establishing a net cross-flow of a gas mixture comprising at least one higher density gas component and at least one lower density gas component along the length of the slot, wherein the cross-flow causes, in combination with the convection flow, a spiraling flow in the slot; and wherein the spiral flow causes an increasing amount of separation of the higher density gas from the lower density gas along the length of the channel. The process may use one or more slots and/or channels.

Heat transfer and pressure measurements for the SSME fuel turbine

NASA Technical Reports Server (NTRS)

Dunn, Michael G.; Kim, Jungho

1991-01-01

A measurement program is underway using the Rocketdyne two-stage Space Shuttle Main Engine (SSME) fuel turbine. The measurements use a very large shock tunnel to produce a short-duration source of heated and pressurized gas which is subsequently passed through the turbine. Within this environment, the turbine is operated at the design values of flow function, stage pressure ratio, stage temperature ratio, and corrected speed. The first stage vane row and the first stage blade row are instrumented in both the spanwise and chordwise directions with pressure transducers and heat flux gages. The specific measurements to be taken include time averaged surface pressure and heat flux distributions on the vane and blade, flow passage static pressure, flow passage total pressure and total temperature distributions, and phase resolved surface pressure and heat flux on the blade.

Estimation of Flow Channel Parameters for Flowing Gas Mixed with Air in Atmospheric-pressure Plasma Jets

NASA Astrophysics Data System (ADS)

Yambe, Kiyoyuki; Saito, Hidetoshi

2017-12-01

When the working gas of an atmospheric-pressure non-equilibrium (cold) plasma flows into free space, the diameter of the resulting flow channel changes continuously. The shape of the channel is observed through the light emitted by the working gas of the atmospheric-pressure plasma. When the plasma jet forms a conical shape, the diameter of the cylindrical shape, which approximates the conical shape, defines the diameter of the flow channel. When the working gas flows into the atmosphere from the inside of a quartz tube, the gas mixes with air. The molar ratio of the working gas and air is estimated from the corresponding volume ratio through the relationship between the diameter of the cylindrical plasma channel and the inner diameter of the quartz tube. The Reynolds number is calculated from the kinematic viscosity of the mixed gas and the molar ratio. The gas flow rates for the upper limit of laminar flow and the lower limit of turbulent flow are determined by the corresponding Reynolds numbers estimated from the molar ratio. It is confirmed that the plasma jet length and the internal plasma length associated with strong light emission increase with the increasing gas flow rate until the rate for the upper limit of laminar flow and the lower limit of turbulent flow, respectively. Thus, we are able to explain the increasing trend in the plasma lengths with the diameter of the flow channel and the molar ratio by using the cylindrical approximation.

Effect of Surface Nonequilibrium Thermochemistry in Simulation of Carbon Based Ablators

NASA Technical Reports Server (NTRS)

Chen, Yih-Kang; Gokcen, Tahir

2012-01-01

This study demonstrates that coupling of a material thermal response code and a flow solver using finite-rate gas/surface interaction model provides time-accurate solutions for multidimensional ablation of carbon based charring ablators. The material thermal response code used in this study is the Two-dimensional Implicit Thermal Response and Ablation Program (TITAN), which predicts charring material thermal response and shape change on hypersonic space vehicles. Its governing equations include total energy balance, pyrolysis gas momentum conservation, and a three-component decomposition model. The flow code solves the reacting Navier-Stokes equations using Data Parallel Line Relaxation (DPLR) method. Loose coupling between material response and flow codes is performed by solving the surface mass balance in DPLR and the surface energy balance in TITAN. Thus, the material surface recession is predicted by finite-rate gas/surface interaction boundary conditions implemented in DPLR, and the surface temperature and pyrolysis gas injection rate are computed in TITAN. Two sets of gas/surface interaction chemistry between air and carbon surface developed by Park and Zhluktov, respectively, are studied. Coupled fluid-material response analyses of stagnation tests conducted in NASA Ames Research Center arc-jet facilities are considered. The ablating material used in these arc-jet tests was a Phenolic Impregnated Carbon Ablator (PICA). Computational predictions of in-depth material thermal response and surface recession are compared with the experimental measurements for stagnation cold wall heat flux ranging from 107 to 1100 Watts per square centimeter.

Effect of Non-Equilibrium Surface Thermochemistry in Simulation of Carbon Based Ablators

NASA Technical Reports Server (NTRS)

Chen, Yih-Kanq; Gokcen, Tahir

2012-01-01

This study demonstrates that coupling of a material thermal response code and a flow solver using non-equilibrium gas/surface interaction model provides time-accurate solutions for the multidimensional ablation of carbon based charring ablators. The material thermal response code used in this study is the Two-dimensional Implicit Thermal-response and AblatioN Program (TITAN), which predicts charring material thermal response and shape change on hypersonic space vehicles. Its governing equations include total energy balance, pyrolysis gas mass conservation, and a three-component decomposition model. The flow code solves the reacting Navier-Stokes equations using Data Parallel Line Relaxation (DPLR) method. Loose coupling between the material response and flow codes is performed by solving the surface mass balance in DPLR and the surface energy balance in TITAN. Thus, the material surface recession is predicted by finite-rate gas/surface interaction boundary conditions implemented in DPLR, and the surface temperature and pyrolysis gas injection rate are computed in TITAN. Two sets of nonequilibrium gas/surface interaction chemistry between air and the carbon surface developed by Park and Zhluktov, respectively, are studied. Coupled fluid-material response analyses of stagnation tests conducted in NASA Ames Research Center arc-jet facilities are considered. The ablating material used in these arc-jet tests was Phenolic Impregnated Carbon Ablator (PICA). Computational predictions of in-depth material thermal response and surface recession are compared with the experimental measurements for stagnation cold wall heat flux ranging from 107 to 1100 Watts per square centimeter.

Numerical Simulation of Multiphase Flow in Nanoporous Organic Matter With Application to Coal and Gas Shale Systems

NASA Astrophysics Data System (ADS)

Song, Wenhui; Yao, Jun; Ma, Jingsheng; Sun, Hai; Li, Yang; Yang, Yongfei; Zhang, Lei

2018-02-01

Fluid flow in nanoscale organic pores is known to be affected by fluid transport mechanisms and properties within confined pore space. The flow of gas and water shows notably different characteristics compared with conventional continuum modeling approach. A pore network flow model is developed and implemented in this work. A 3-D organic pore network model is constructed from 3-D image that is reconstructed from 2-D shale SEM image of organic-rich sample. The 3-D pore network model is assumed to be gas-wet and to contain initially gas-filled pores only, and the flow model is concerned with drainage process. Gas flow considers a full range of gas transport mechanisms, including viscous flow, Knudsen diffusion, surface diffusion, ad/desorption, and gas PVT and viscosity using a modified van der Waals' EoS and a correlation for natural gas, respectively. The influences of slip length, contact angle, and gas adsorption layer on water flow are considered. Surface tension considers the pore size and temperature effects. Invasion percolation is applied to calculate gas-water relative permeability. The results indicate that the influences of pore pressure and temperature on water phase relative permeabilities are negligible while gas phase relative permeabilities are relatively larger in higher temperatures and lower pore pressures. Gas phase relative permeability increases while water phase relative permeability decreases with the shrinkage of pore size. This can be attributed to the fact that gas adsorption layer decreases the effective flow area of the water phase and surface diffusion capacity for adsorbed gas is enhanced in small pore size.

Experimental investigation on the flow around a simplified geometry of automotive engine compartment

NASA Astrophysics Data System (ADS)

D'Hondt, Marion; Gilliéron, Patrick; Devinant, Philippe

2011-05-01

In the current sustainable development context, car manufacturers have to keep doing efforts to reduce the aerodynamic drag of automotive vehicle in order to decrease their CO2 and greenhouse gas emissions. The cooling airflow, through the engine compartment of vehicles, contributes from 5 to 10% to the total aerodynamic drag. By means of simplified car geometry, equipped with an engine compartment, the configurations that favor a low contribution to total drag are identified. PIV (particle image velocimetry) velocity measurements in the wake of the geometry allow explaining these drag reductions. Besides, the cooling flow rate is also assessed and gives indications on the configurations that favor the engine cooling.

Preliminary assessment of the velocity pump reaction turbine as a geothermal total-flow expander

NASA Astrophysics Data System (ADS)

Demuth, O. J.

1984-06-01

The velocity pump reaction turbine (VPRT) was evaluated as a total flow expander in a geothermal-electric conversion cycle. Values of geofluid effectiveness of VPRT systems were estimated for conditions consisting of: a 360(F) geothermal resource, 60 F wet-bulb ambient temperature, zero and 0.003 mass concentrations of dissolved noncondensible gas in the geofluid, 100 and 120 F condensing temperatures, and engine efficiencies ranging from 0.4 to 1.0. Achievable engine efficiencies were estimated to range from 0.77, with plant geofluid effectiveness values ranging as high as 9.5 watt hr-lbm geofluid for the 360 F resource temperature. This value is competitive with magnitudes of geofluid effectiveness projected for advanced binary plants, and is on the order of 40% higher than estimates for dual-flash steam and other total flow systems reviewed. Because of its potentially high performance and relative simplicity, the VPRT system appears to warrant further investigation toward its use in a well-head geothermal plant.

Propagation characteristics of pulverized coal and gas two-phase flow during an outburst.

PubMed

Zhou, Aitao; Wang, Kai; Fan, Lingpeng; Tao, Bo

2017-01-01

Coal and gas outbursts are dynamic failures that can involve the ejection of thousands tons of pulverized coal, as well as considerable volumes of gas, into a limited working space within a short period. The two-phase flow of gas and pulverized coal that occurs during an outburst can lead to fatalities and destroy underground equipment. This article examines the interaction mechanism between pulverized coal and gas flow. Based on the role of gas expansion energy in the development stage of outbursts, a numerical simulation method is proposed for investigating the propagation characteristics of the two-phase flow. This simulation method was verified by a shock tube experiment involving pulverized coal and gas flow. The experimental and simulated results both demonstrate that the instantaneous ejection of pulverized coal and gas flow can form outburst shock waves. These are attenuated along the propagation direction, and the volume fraction of pulverized coal in the two-phase flow has significant influence on attenuation of the outburst shock wave. As a whole, pulverized coal flow has a negative impact on gas flow, which makes a great loss of large amounts of initial energy, blocking the propagation of gas flow. According to comparison of numerical results for different roadway types, the attenuation effect of T-type roadways is best. In the propagation of shock wave, reflection and diffraction of shock wave interact through the complex roadway types.

Propagation characteristics of pulverized coal and gas two-phase flow during an outburst

PubMed Central

Zhou, Aitao; Wang, Kai; Fan, Lingpeng; Tao, Bo

2017-01-01

Coal and gas outbursts are dynamic failures that can involve the ejection of thousands tons of pulverized coal, as well as considerable volumes of gas, into a limited working space within a short period. The two-phase flow of gas and pulverized coal that occurs during an outburst can lead to fatalities and destroy underground equipment. This article examines the interaction mechanism between pulverized coal and gas flow. Based on the role of gas expansion energy in the development stage of outbursts, a numerical simulation method is proposed for investigating the propagation characteristics of the two-phase flow. This simulation method was verified by a shock tube experiment involving pulverized coal and gas flow. The experimental and simulated results both demonstrate that the instantaneous ejection of pulverized coal and gas flow can form outburst shock waves. These are attenuated along the propagation direction, and the volume fraction of pulverized coal in the two-phase flow has significant influence on attenuation of the outburst shock wave. As a whole, pulverized coal flow has a negative impact on gas flow, which makes a great loss of large amounts of initial energy, blocking the propagation of gas flow. According to comparison of numerical results for different roadway types, the attenuation effect of T-type roadways is best. In the propagation of shock wave, reflection and diffraction of shock wave interact through the complex roadway types. PMID:28727738

Precision control of high temperature furnaces using an auxiliary power supply and charged practice current flow

DOEpatents

Pollock, George G.

1997-01-01

Two power supplies are combined to control a furnace. A main power supply heats the furnace in the traditional manner, while the power from the auxiliary supply is introduced as a current flow through charged particles existing due to ionized gas or thermionic emission. The main power supply provides the bulk heating power and the auxiliary supply provides a precise and fast power source such that the precision of the total power delivered to the furnace is improved.

Structure and shale gas production patterns from eastern Kentucky field

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

Shumaker, R.C.

Computer-derived subsurface structure, isopach, and gas-flow maps, based on 4000 drillers logs, have been generated for eastern Kentucky under a project sponsored by the Gas Research Institute. Structure maps show low-relief flextures related to basement structure. Some structures have been mapped at the surface, others have not. Highest final open-flow (fof) of shale gas from wells in Martin County follow a structural low between (basement) anticlines. From there, elevated gas flows (fof) extend westward along the Warfield monocline to Floyd County where the high flow (fof) trend extends southward along the Floyd County channel. In Knott County, the number ofmore » wells with high gas flow (fof) decreases abruptly. The center of highest gas flow (fof) in Floyd County spreads eastward to Pike County, forming a triangular shaped area of high production (fof). The center of highest gas flow (fof) is in an area where possible (basement) structure trends intersect and where low-relief surface folds (probably detached structure) were mapped and shown on the 1922 version of the Floyd County structure map. Modern regional maps, based on geophysical logs from widely spaced wells, do not define the low-relief structures that have been useful in predicting gas flow trends. Detailed maps based on drillers logs can be misleading unless carefully edited. Comparative analysis of high gas flows (fof) and 10-year cumulative production figures in a small area confirms that there is a relationship between gas flow (fof) values and long-term cumulative production.« less

The Seepage Simulation of Single Hole and Composite Gas Drainage Based on LB Method

NASA Astrophysics Data System (ADS)

Chen, Yanhao; Zhong, Qiu; Gong, Zhenzhao

2018-01-01

Gas drainage is the most effective method to prevent and solve coal mine gas power disasters. It is very important to study the seepage flow law of gas in fissure coal gas. The LB method is a simplified computational model based on micro-scale, especially for the study of seepage problem. Based on fracture seepage mathematical model on the basis of single coal gas drainage, using the LB method during coal gas drainage of gas flow numerical simulation, this paper maps the single-hole drainage gas, symmetric slot and asymmetric slot, the different width of the slot combined drainage area gas flow under working condition of gas cloud of gas pressure, flow path diagram and flow velocity vector diagram, and analyses the influence on gas seepage field under various working conditions, and also discusses effective drainage method of the center hole slot on both sides, and preliminary exploration that is related to the combination of gas drainage has been carried on as well.

Determination of gas & liquid two-phase flow regime transitions in wellbore annulus by virtual mass force coefficient when gas cut

NASA Astrophysics Data System (ADS)

Qu, Junbo; Yan, Tie; Sun, Xiaofeng; Chen, Ye; Pan, Yi

2017-10-01

With the development of drilling technology to deeper stratum, overflowing especially gas cut occurs frequently, and then flow regime in wellbore annulus is from the original drilling fluid single-phase flow into gas & liquid two-phase flow. By using averaged two-fluid model equations and the basic principle of fluid mechanics to establish the continuity equations and momentum conservation equations of gas phase & liquid phase respectively. Relationship between pressure and density of gas & liquid was introduced to obtain hyperbolic equation, and get the expression of the dimensionless eigenvalue of the equation by using the characteristic line method, and analyze wellbore flow regime to get the critical gas content under different virtual mass force coefficients. Results show that the range of equation eigenvalues is getting smaller and smaller with the increase of gas content. When gas content reaches the critical point, the dimensionless eigenvalue of equation has no real solution, and the wellbore flow regime changed from bubble flow to bomb flow. When virtual mass force coefficients are 0.50, 0.60, 0.70 and 0.80 respectively, the critical gas contents are 0.32, 0.34, 0.37 and 0.39 respectively. The higher the coefficient of virtual mass force, the higher gas content in wellbore corresponding to the critical point of transition flow regime, which is in good agreement with previous experimental results. Therefore, it is possible to determine whether there is a real solution of the dimensionless eigenvalue of equation by virtual mass force coefficient and wellbore gas content, from which we can obtain the critical condition of wellbore flow regime transformation. It can provide theoretical support for the accurate judgment of the annular flow regime.

Molecular Rayleigh Scattering Diagnostic for Dynamic Temperature, Velocity, and Density Measurements

NASA Technical Reports Server (NTRS)

Mielke, Amy R.; Elam, Kristie A.; Sung, Chi-Jen

2006-01-01

A molecular Rayleigh scattering technique is developed to measure dynamic gas temperature, velocity, and density in unseeded turbulent flows at sampling rates up to 16 kHz. A high power CW laser beam is focused at a point in an air jet plume and Rayleigh scattered light is collected and spectrally resolved. The spectrum of the light, which contains information about the temperature and velocity of the flow, is analyzed using a Fabry-Perot interferometer. The circular interference fringe pattern is divided into four concentric regions and sampled at 1 and 16 kHz using photon counting electronics. Monitoring the relative change in intensity within each region allows for measurement of gas temperature and velocity. Independently monitoring the total scattered light intensity provides a measure of gas density. A low speed heated jet is used to validate the measurement of temperature fluctuations and an acoustically excited nozzle flow is studied to validate velocity fluctuation measurements. Power spectral density calculations of the property fluctuations, as well as mean and fluctuating quantities are presented. Temperature fluctuation results are compared with constant current anemometry measurements and velocity fluctuation results are compared with constant temperature anemometry measurements at the same locations.

40 CFR 92.117 - Gas meter or flow instrumentation calibration, particulate measurement.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Gas meter or flow instrumentation... ENGINES Test Procedures § 92.117 Gas meter or flow instrumentation calibration, particulate measurement. (a) Sampling for particulate emissions requires the use of gas meters or flow instrumentation to...

40 CFR 92.117 - Gas meter or flow instrumentation calibration, particulate measurement.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 20 2014-07-01 2013-07-01 true Gas meter or flow instrumentation... ENGINES Test Procedures § 92.117 Gas meter or flow instrumentation calibration, particulate measurement. (a) Sampling for particulate emissions requires the use of gas meters or flow instrumentation to...

40 CFR 92.117 - Gas meter or flow instrumentation calibration, particulate measurement.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 21 2012-07-01 2012-07-01 false Gas meter or flow instrumentation... ENGINES Test Procedures § 92.117 Gas meter or flow instrumentation calibration, particulate measurement. (a) Sampling for particulate emissions requires the use of gas meters or flow instrumentation to...

40 CFR 92.117 - Gas meter or flow instrumentation calibration, particulate measurement.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 21 2013-07-01 2013-07-01 false Gas meter or flow instrumentation... ENGINES Test Procedures § 92.117 Gas meter or flow instrumentation calibration, particulate measurement. (a) Sampling for particulate emissions requires the use of gas meters or flow instrumentation to...

40 CFR 92.117 - Gas meter or flow instrumentation calibration, particulate measurement.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 20 2011-07-01 2011-07-01 false Gas meter or flow instrumentation... ENGINES Test Procedures § 92.117 Gas meter or flow instrumentation calibration, particulate measurement. (a) Sampling for particulate emissions requires the use of gas meters or flow instrumentation to...

40 CFR 89.416 - Raw exhaust gas flow.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 20 2011-07-01 2011-07-01 false Raw exhaust gas flow. 89.416 Section 89.416 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED... Procedures § 89.416 Raw exhaust gas flow. The exhaust gas flow shall be determined by one of the methods...

40 CFR 89.416 - Raw exhaust gas flow.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Raw exhaust gas flow. 89.416 Section 89.416 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED... Procedures § 89.416 Raw exhaust gas flow. The exhaust gas flow shall be determined by one of the methods...

Ethylene Trace-gas Techniques for High-speed Flows

NASA Technical Reports Server (NTRS)

Davis, David O.; Reichert, Bruce A.

1994-01-01

Three applications of the ethylene trace-gas technique to high-speed flows are described: flow-field tracking, air-to-air mixing, and bleed mass-flow measurement. The technique involves injecting a non-reacting gas (ethylene) into the flow field and measuring the concentration distribution in a downstream plane. From the distributions, information about flow development, mixing, and mass-flow rates can be dtermined. The trace-gas apparatus and special considerations for use in high-speed flow are discussed. A description of each application, including uncertainty estimates is followed by a demonstrative example.

A comparative study of several compressibility corrections to turbulence models applied to high-speed shear layers

NASA Technical Reports Server (NTRS)

Viegas, John R.; Rubesin, Morris W.

1991-01-01

Several recently published compressibility corrections to the standard k-epsilon turbulence model are used with the Navier-Stokes equations to compute the mixing region of a large variety of high speed flows. These corrections, specifically developed to address the weakness of higher order turbulence models to accurately predict the spread rate of compressible free shear flows, are applied to two stream flows of the same gas mixing under a large variety of free stream conditions. Results are presented for two types of flows: unconfined streams with either (1) matched total temperatures and static pressures, or (2) matched static temperatures and pressures, and a confined stream.

Use of a turbine in a breath-by-breath computer-based respiratory measurement system.

PubMed

Venkateswaran, R S; Gallagher, R R

1997-01-01

The Computer-Based Respiratory Measurement System (CBRMS) is capable of analyzing individual breaths to monitor the kinetics of oxygen uptake, carbon dioxide production, tidal volumes, pulmonary ventilation, and other respiratory parameters during rest, exercise, and recovery. Respiratory gas volumes are measured by a calibrated turbine transducer while the respiratory gas concentrations are measured by a calibrated, fast-responding medical gas analyzer. To improve accuracy of the results, the inspiratory volumes and gas concentrations are measured and not assumed to be equal to expiratory volumes or ambient concentrations respectively. The respiratory gas volumes and concentration signals are digitized and stored in arrays. The gas volumes are converted to flow signals by software differentiation. These digitized data arrays are stored as files in a personal computer. Time alignment of the flow and gas concentration signals is performed at each breath for maximum accuracy in analysis. For system verification, data were obtained under resting conditions and under constant load exercises at 50 W, 100 W, and 150 W. These workloads were performed by a healthy, male subject on a bicycle ergometer. A strong correlation existed between the CBRMS steady-state results and the standard end-expirate bag collection technique. Thus, there is reason to believe that the CBRMS is capable of calculating respiratory transient responses accurately, a significant contribution to an understanding of total respiratory system function.

Prediction of slug-to-annular flow pattern transition (STA) for reducing the risk of gas-lift instabilities and effective gas/liquid transport from low-pressure reservoirs

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

Toma, P.R.; Vargas, E.; Kuru, E.

Flow-pattern instabilities have frequently been observed in both conventional gas-lifting and unloading operations of water and oil in low-pressure gas and coalbed reservoirs. This paper identifies the slug-to-annular flow-pattern transition (STA) during upward gas/liquid transportation as a potential cause of flow instability in these operations. It is recommended that the slug-flow pattern be used mainly to minimize the pressure drop and gas compression work associated with gas-lifting large volumes of oil and water. Conversely, the annular flow pattern should be used during the unloading operation to produce gas with relatively small amounts of water and condensate. New and efficient artificialmore » lifting strategies are required to transport the liquid out of the depleted gas or coalbed reservoir level to the surface. This paper presents held data and laboratory measurements supporting the hypothesis that STA significantly contributes to flow instabilities and should therefore be avoided in upward gas/liquid transportation operations. Laboratory high-speed measurements of flow-pressure components under a broad range of gas-injection rates including STA have also been included to illustrate the onset of large STA-related flow-pressure oscillations. The latter body of data provides important insights into gas deliquification mechanisms and identifies potential solutions for improved gas-lifting and unloading procedures. A comparison of laboratory data with existing STA models was performed first. Selected models were then numerically tested in field situations. Effective field strategies for avoiding STA occurrence in marginal and new (offshore) field applications (i.e.. through the use of a slug or annular flow pattern regimen from the bottomhole to wellhead levels) are discussed.« less

Modeling of heavy-gas effects on airfoil flows

NASA Technical Reports Server (NTRS)

Drela, Mark

1992-01-01

Thermodynamic models were constructed for a calorically imperfect gas and for a non-ideal gas. These were incorporated into a quasi one dimensional flow solver to develop an understanding of the differences in flow behavior between the new models and the perfect gas model. The models were also incorporated into a two dimensional flow solver to investigate their effects on transonic airfoil flows. Specifically, the calculations simulated airfoil testing in a proposed high Reynolds number heavy gas test facility. The results indicate that the non-idealities caused significant differences in the flow field, but that matching of an appropriate non-dimensional parameter led to flows similar to those in air.

Simulation of gas flow in micro-porous media with the regularized lattice Boltzmann method

DOE PAGES

Wang, Junjian; Kang, Qinjun; Wang, Yuzhu; ...

2017-06-01

One primary challenge for prediction of gas flow in the unconventional gas reservoir at the pore-scale such as shale and tight gas reservoirs is the geometric complexity of the micro-porous media. In this paper, a regularized multiple-relaxation-time (MRT) lattice Boltzmann (LB) model is applied to analyze gas flow in 2-dimensional micro-porous medium reconstructed by quartet structure generation set (QSGS) on pore-scale. In this paper, the velocity distribution inside the porous structure is presented and analyzed, and the effects of the porosity and specific surface area on the rarefied gas flow and apparent permeability are examined and investigated. The simulation resultsmore » indicate that the gas exhibits different flow behaviours at various pressure conditions and the gas permeability is strongly related to the pressure. Finally, the increased porosity or the decreased specific surface area leads to the increase of the gas apparent permeability, and the gas flow is more sensitive to the pore morphological properties at low-pressure conditions.« less

Simulation of gas flow in micro-porous media with the regularized lattice Boltzmann method

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

Wang, Junjian; Kang, Qinjun; Wang, Yuzhu

One primary challenge for prediction of gas flow in the unconventional gas reservoir at the pore-scale such as shale and tight gas reservoirs is the geometric complexity of the micro-porous media. In this paper, a regularized multiple-relaxation-time (MRT) lattice Boltzmann (LB) model is applied to analyze gas flow in 2-dimensional micro-porous medium reconstructed by quartet structure generation set (QSGS) on pore-scale. In this paper, the velocity distribution inside the porous structure is presented and analyzed, and the effects of the porosity and specific surface area on the rarefied gas flow and apparent permeability are examined and investigated. The simulation resultsmore » indicate that the gas exhibits different flow behaviours at various pressure conditions and the gas permeability is strongly related to the pressure. Finally, the increased porosity or the decreased specific surface area leads to the increase of the gas apparent permeability, and the gas flow is more sensitive to the pore morphological properties at low-pressure conditions.« less

Exhaust plume impingement of chemically reacting gas-particle flows

NASA Technical Reports Server (NTRS)

Smith, S. D.; Penny, M. M.; Greenwood, T. F.; Roberts, B. B.

1975-01-01

A series of computer codes has been developed to predict gas-particle flows and resulting impingement forces, moments and heating rates to surfaces immersed in the flow. The gas-particle flow solution is coupled via heat transfer and drag between the phases with chemical effects included in the gas phase. The flow solution and impingement calculations are discussed. Analytical results are compared with test data obtained to evaluate gas-particle effects on the Space Shuttle thermal protection system during the staging maneuver.

A Model To Estimate Carbon Dioxide Injectivity and Storage Capacity for Geological Sequestration in Shale Gas Wells.

PubMed

Edwards, Ryan W J; Celia, Michael A; Bandilla, Karl W; Doster, Florian; Kanno, Cynthia M

2015-08-04

Recent studies suggest the possibility of CO2 sequestration in depleted shale gas formations, motivated by large storage capacity estimates in these formations. Questions remain regarding the dynamic response and practicality of injection of large amounts of CO2 into shale gas wells. A two-component (CO2 and CH4) model of gas flow in a shale gas formation including adsorption effects provides the basis to investigate the dynamics of CO2 injection. History-matching of gas production data allows for formation parameter estimation. Application to three shale gas-producing regions shows that CO2 can only be injected at low rates into individual wells and that individual well capacity is relatively small, despite significant capacity variation between shale plays. The estimated total capacity of an average Marcellus Shale well in Pennsylvania is 0.5 million metric tonnes (Mt) of CO2, compared with 0.15 Mt in an average Barnett Shale well. Applying the individual well estimates to the total number of existing and permitted planned wells (as of March, 2015) in each play yields a current estimated capacity of 7200-9600 Mt in the Marcellus Shale in Pennsylvania and 2100-3100 Mt in the Barnett Shale.

Transport of temperature-velocity covariance in gas-solid flow and its relation to the axial dispersion coefficient

NASA Astrophysics Data System (ADS)

Subramaniam, Shankar; Sun, Bo

2015-11-01

The presence of solid particles in a steady laminar flow generates velocity fluctuations with respect to the mean fluid velocity that are termed pseudo-turbulence. The level of these pseudo-turbulent velocity fluctuations has been characterized in statistically homogeneous fixed particle assemblies and freely evolving suspensions using particle-resolved direct numerical simulation (PR-DNS) by Mehrabadi et al. (JFM, 2015), and it is found to be a significant contribution to the total kinetic energy associated with the flow. The correlation of these velocity fluctuations with temperature (or a passive scalar) generates a flux term that appears in the transport equation for the average fluid temperature (or average scalar concentration). The magnitude of this transport of temperature-velocity covariance is quantified using PR-DNS of thermally fully developed flow past a statistically homogeneous fixed assembly of particles, and the budget of the average fluid temperature equation is presented. The relation of this transport term to the axial dispersion coefficient (Brenner, Phil. Trans. Roy. Soc. A, 1980) is established. The simulation results are then interpreted in the context of our understanding of axial dispersion in gas-solid flow. NSF CBET 1336941.

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.

Flow-pattern identification and nonlinear dynamics of gas-liquid two-phase flow in complex networks.

PubMed

Gao, Zhongke; Jin, Ningde

2009-06-01

The identification of flow pattern is a basic and important issue in multiphase systems. Because of the complexity of phase interaction in gas-liquid two-phase flow, it is difficult to discern its flow pattern objectively. In this paper, we make a systematic study on the vertical upward gas-liquid two-phase flow using complex network. Three unique network construction methods are proposed to build three types of networks, i.e., flow pattern complex network (FPCN), fluid dynamic complex network (FDCN), and fluid structure complex network (FSCN). Through detecting the community structure of FPCN by the community-detection algorithm based on K -mean clustering, useful and interesting results are found which can be used for identifying five vertical upward gas-liquid two-phase flow patterns. To investigate the dynamic characteristics of gas-liquid two-phase flow, we construct 50 FDCNs under different flow conditions, and find that the power-law exponent and the network information entropy, which are sensitive to the flow pattern transition, can both characterize the nonlinear dynamics of gas-liquid two-phase flow. Furthermore, we construct FSCN and demonstrate how network statistic can be used to reveal the fluid structure of gas-liquid two-phase flow. In this paper, from a different perspective, we not only introduce complex network theory to the study of gas-liquid two-phase flow but also indicate that complex network may be a powerful tool for exploring nonlinear time series in practice.

Laser photochemical lead isotopes separation for harmless nuclear power engineering

NASA Astrophysics Data System (ADS)

Bokhan, P. A.; Fateev, N. V.; Kim, V. A.; Zakrevsky, D. E.

2016-09-01

The collisional quenching of the metastable 3 P 1,2 and 1 D 2 lead atoms is studied experimentally in the gas flow of the lead atoms, reagent-molecules and a carrier gas Ar. The experimental parameters were similar to the conditions that are required in the operation of the experimental setup for photochemical isotope separation. Excited atoms are generated under electron impact conditions created by a gas glow discharge through the mixture of gases and monitored photoelectrically by attenuation of atomic resonance radiation from hollow cathode 208Pb lamp. The decay of the excited atoms has been studied in the presence various molecules and total cross section data are reported. The flow tube measurements has allowed to separate the physical and chemical quenching channels and measure the rates of the chemical reaction excited lead with N2O, CH2Cl2, SF6 and CuBr molecules. These results are discussed in the prospects of the obtaining isotopically modified lead as a promising coolant in the reactors on the fast-neutron.

Gas permeability of ice-templated, unidirectional porous ceramics

NASA Astrophysics Data System (ADS)

Seuba, Jordi; Deville, Sylvain; Guizard, Christian; Stevenson, Adam J.

2016-01-01

We investigate the gas flow behavior of unidirectional porous ceramics processed by ice-templating. The pore volume ranged between 54% and 72% and pore size between 2.9 ?m and 19.1 ?m. The maximum permeability (?? m?) was measured in samples with the highest total pore volume (72%) and pore size (19.1 ?m). However, we demonstrate that it is possible to achieve a similar permeability (?? m?) at 54% pore volume by modification of the pore shape. These results were compared with those reported and measured for isotropic porous materials processed by conventional techniques. In unidirectional porous materials tortuosity (?) is mainly controlled by pore size, unlike in isotropic porous structures where ? is linked to pore volume. Furthermore, we assessed the applicability of Ergun and capillary model in the prediction of permeability and we found that the capillary model accurately describes the gas flow behavior of unidirectional porous materials. Finally, we combined the permeability data obtained here with strength data for these materials to establish links between strength and permeability of ice-templated materials.

Laser cross-flow gas system

DOEpatents

Duncan, David B.

1992-01-01

A method and laser apparatus are disclosed which provide for a cross-flow of gas near one end of a laser discharge tube. The cross-flow of gas causes a concentration gradient which affects diffusion of contaminants in the discharge tube towards the cross-flow of the gas, which contaminants are then withdrawn from the discharge tube.

Study on dynamics of the influence exerted by plasma on gas flow field in non-thermal atmospheric pressure plasma jet

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

Qaisrani, M. Hasnain; Xian, Yubin, E-mail: yubin.xian@hotmail.com; Li, Congyun

2016-06-15

In this paper, first, steady state of the plasma jet at different operating conditions is investigated through Schlieren photography with and without applying shielding gas. Second, the dynamic process for the plasma impacting on the gas flow field is studied. When the discharge is ignited, reduction in laminar flow occurs. However, when the gas flow rate is too low or too high, this phenomenon is not obvious. What is more, both frequency and voltage have significant impact on the effect of plasma on the gas flow, but the former is more significant. Shielding gas provides a curtain for plasma tomore » propagate further. High speed camera along with Schlieren photography is utilized to study the impact of plasma on the gas flow when plasma is switched on and off. The transition of the gas flow from laminar to turbulent or vice versa happens right after the turbulent front. It is concluded that appearance and propagation of turbulence front is responsible for the transition of the flow state.« less

Multiparameter Analysis of Gas Transport Phenomena in Shale Gas Reservoirs: Apparent Permeability Characterization.

PubMed

Shen, Yinghao; Pang, Yu; Shen, Ziqi; Tian, Yuanyuan; Ge, Hongkui

2018-02-08

The large amount of nanoscale pores in shale results in the inability to apply Darcy's law. Moreover, the gas adsorption of shale increases the complexity of pore size characterization and thus decreases the accuracy of flow regime estimation. In this study, an apparent permeability model, which describes the adsorptive gas flow behavior in shale by considering the effects of gas adsorption, stress dependence, and non-Darcy flow, is proposed. The pore size distribution, methane adsorption capacity, pore compressibility, and matrix permeability of the Barnett and Eagle Ford shales are measured in the laboratory to determine the critical parameters of gas transport phenomena. The slip coefficients, tortuosity, and surface diffusivity are predicted via the regression analysis of the permeability data. The results indicate that the apparent permeability model, which considers second-order gas slippage, Knudsen diffusion, and surface diffusion, could describe the gas flow behavior in the transition flow regime for nanoporous shale. Second-order gas slippage and surface diffusion play key roles in the gas flow in nanopores for Knudsen numbers ranging from 0.18 to 0.5. Therefore, the gas adsorption and non-Darcy flow effects, which involve gas slippage, Knudsen diffusion, and surface diffusion, are indispensable parameters of the permeability model for shale.

Computational fluid dynamics modeling of gas dispersion in multi impeller bioreactor.

PubMed

Ahmed, Syed Ubaid; Ranganathan, Panneerselvam; Pandey, Ashok; Sivaraman, Savithri

2010-06-01

In the present study, experiments have been carried out to identify various flow regimes in a dual Rushton turbines stirred bioreactor for different gas flow rates and impeller speeds. The hydrodynamic parameters like fractional gas hold-up, power consumption and mixing time have been measured. A two fluid model along with MUSIG model to handle polydispersed gas flow has been implemented to predict the various flow regimes and hydrodynamic parameters in the dual turbines stirred bioreactor. The computational model has been mapped on commercial solver ANSYS CFX. The flow regimes predicted by numerical simulations are validated with the experimental results. The present model has successfully captured the flow regimes as observed during experiments. The measured gross flow characteristics like fractional gas hold-up, and mixing time have been compared with numerical simulations. Also the effect of gas flow rate and impeller speed on gas hold-up and power consumption have been investigated. (c) 2009 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Supersonic Flow of Chemically Reacting Gas-Particle Mixtures. Volume 2: RAMP - A Computer Code for Analysis of Chemically Reacting Gas-Particle Flows

NASA Technical Reports Server (NTRS)

Penny, M. M.; Smith, S. D.; Anderson, P. G.; Sulyma, P. R.; Pearson, M. L.

1976-01-01

A computer program written in conjunction with the numerical solution of the flow of chemically reacting gas-particle mixtures was documented. The solution to the set of governing equations was obtained by utilizing the method of characteristics. The equations cast in characteristic form were shown to be formally the same for ideal, frozen, chemical equilibrium and chemical non-equilibrium reacting gas mixtures. The characteristic directions for the gas-particle system are found to be the conventional gas Mach lines, the gas streamlines and the particle streamlines. The basic mesh construction for the flow solution is along streamlines and normals to the streamlines for axisymmetric or two-dimensional flow. The analysis gives detailed information of the supersonic flow and provides for a continuous solution of the nozzle and exhaust plume flow fields. Boundary conditions for the flow solution are either the nozzle wall or the exhaust plume boundary.

Low gas flow inductively coupled plasma optical emission spectrometry for the analysis of food samples after microwave digestion.

PubMed

Nowak, Sascha; Gesell, Monika; Holtkamp, Michael; Scheffer, Andy; Sperling, Michael; Karst, Uwe; Buscher, Wolfgang

2014-11-01

In this work, the recently introduced low flow inductively coupled plasma optical emission spectrometry (ICP-OES) with a total argon consumption below 0.7 L/min is applied for the first time to the field of food analysis. One goal is the investigation of the performance of this low flow plasma compared to a conventional ICP-OES system when non-aqueous samples with a certain matrix are introduced into the system. For this purpose, arsenic is determined in three different kinds of fish samples. In addition several nutrients (K, Na, Mg, Ca) and trace metals (Co, Cu, Mn, Cd, Pb, Zn, Fe, and Ni) are determined in honey samples (acacia) after microwave digestion. The precision of the measurements is characterized by relative standard deviations (RSD) and compared to the corresponding precision values achieved using the conventional Fassel-type torch of the ICP. To prove the accuracy of the low flow ICP-OES method, the obtained data from honey samples are validated by a conventional ICP-OES. For the measurements concerning arsenic in fish, the low flow ICP-OES values are validated by conventional Fassel-type ICP-OES. Furthermore, a certified reference material was investigated with the low gas flow setup. Limits of detection (LOD), according to the 3σ criterion, were determined to be in the low microgram per liter range for all analytes. Recovery rates in the range of 96-106% were observed for the determined trace metal elements. It was proven that the low gas flow ICP-OES leads to results that are comparable with those obtained with the Fassel-type torch for the analysis of food samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Gas-liquid mass transfer and flow phenomena in the Peirce-Smith converter: a water model study

NASA Astrophysics Data System (ADS)

Zhao, Xing; Zhao, Hong-liang; Zhang, Li-feng; Yang, Li-qiang

2018-01-01

A water model with a geometric similarity ratio of 1:5 was developed to investigate the gas-liquid mass transfer and flow characteristics in a Peirce-Smith converter. A gas mixture of CO2 and Ar was injected into a NaOH solution bath. The flow field, volumetric mass transfer coefficient per unit volume ( Ak/V; where A is the contact area between phases, V is the volume, and k is the mass transfer coefficient), and gas utilization ratio ( η) were then measured at different gas flow rates and blow angles. The results showed that the flow field could be divided into five regions, i.e., injection, strong loop, weak loop, splashing, and dead zone. Whereas the Ak/V of the bath increased and then decreased with increasing gas flow rate, and η steadily increased. When the converter was rotated clockwise, both Ak/V and η increased. However, the flow condition deteriorated when the gas flow rate and blow angle were drastically increased. Therefore, these parameters must be controlled to optimal conditions. In the proposed model, the optimal gas flow rate and blow angle were 7.5 m3·h-1 and 10°, respectively.

The Variation of Catalyst and Carrier Gas on Anisole Deoxygenation Reaction

NASA Astrophysics Data System (ADS)

Ariyani, D.; Dwi Nugrahaningtyas, Khoirina; Heraldy, E.

2018-03-01

This research aims to determine the best catalyst and carrier gas in anisole deoxygenation reaction. The reaction was carried out over a flow system with a variation of catalyst CoMo A (CoMo/USY reduction), CoMo B (CoMo/USY oxidation-reduction), and CoMo C (CoMo/ZAA oxidation-reduction). In addition, variation of carrier gas nitrogen and hydrogen was investigated. The result was analyzed using Gas Chromatography-Mass Spectroscopy (GC-MS). The deoxygenation anisole result showed that CoMo A catalyst with hydrogen as the carrier gas has the highest total product yield (50.72 %), intermediate product yield (38.49 % in phenol and 6.99 % in benzaldehyde), and deoxygenation yield (5.24 %). The CoMo C catalyst exhibited the most selective deoxygenation product. The nitrogen carrier gas with the CoMo C catalyst has the best selectivity of benzene product (93.92 %).

Multiphase flowmeter successfully measures three-phase flow at extremely high gas-volume fractions -- Gulf of Suez, Egypt

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

Leggett, R.B.; Borling, D.C.; Powers, B.S.

1998-02-01

A multiphase flowmeter (MPFM) installed in offshore Egypt has accurately measured three-phase flow in extremely gassy flow conditions. The meter is completely nonintrusive, with no moving parts, requires no flow mixing before measurement, and has no bypass loop to remove gas before multiphase measurement. Flow regimes observed during the field test of this meter ranged from severe slugging to annular flow caused by the dynamics of gas-lift gas in the production stream. Average gas-volume fraction ranged from 93 to 98% during tests conducted on seven wells. The meter was installed in the Gulf of Suez on a well protector platformmore » in the Gulf of Suez Petroleum Co. (Gupco) October field, and was placed in series with a test separator located on a nearby production platform. Wells were individually tested with flow conditions ranging from 1,300 to 4,700 B/D fluid, 2.4 to 3.9 MMscf/D of gas, and water cuts from 1 to 52%. The meter is capable of measuring water cuts up to 100%. Production was routed through both the MPFM and the test separator simultaneously as wells flowed with the assistance of gas-lift gas. The MPFM measured gas and liquid rates to within {+-} 10% of test-separator reference measurement flow rates, and accomplished this at gas-volume fractions from 93 to 96%. At higher gas-volume fractions up to 98%, accuracy deteriorated but the meter continued to provide repeatable results.« less

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

Smith, R.V.

This book reports on remedial measures for gas wells and new methods for calculating the position of the stabilized performance curves for gas wells as well as the heating value for natural gases from compositional analyses. In addition, the author includes problem solutions in an appendix and a section showing the relation between the conventional empirical equation and the theoretical performance equation of A.S. Odeh. The author successfully bridges the gap between the results of empirical testing and the theory of unsteady-state flow in porous media. It strengthens the bond between conventional reservoir engineering practices and understanding gas well behavior.more » Problems listed at the end of each chapter are excellent exercises for practitioners. This book provides information on: Natural Gas Engineering; Properties of natural gas; Application of gas laws to reservoir engineering; Gas measurement; Flow of natural gas in circular pipe and annular conductors; Flow of gas in porous media (a review); Gas well testing; Unsteady-state flow behavior of gas wells; Production forecasting for gas wells; Production decline curves for gas wells; Sizing flow strings for gas wells; Remedial measures for gas wells; Gas sales contracts; and appendices on Compressibility for natural gas, Gas measurement factors, SI metric conversion factors, and Solutions to problems.« less

40 CFR 60.64 - Test methods and procedures

Code of Federal Regulations, 2011 CFR

2011-07-01

... flow rate of effluent gas, where Cs and Qs are on the same basis (either wet or dry), dscf/hr; P = total kiln feed (dry basis) rate, ton/hr. For kilns constructed, modified or reconstructed on or after... associated alkali bypass and cooler) subject to the 10 percent opacity limit must follow the appropriate...

40 CFR 63.1349 - Performance testing requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

...-line kiln/raw mill is not operating. The owner or operator of a clinker cooler subject to limitations..., kg/dscm. Qsd = volumetric flow rate of effluent gas, dscm/hr. P = total kiln feed (dry basis), Mg/hr... kiln feed (dry basis), Mg/hr. (v) Except as provided in paragraph (b)(1)(vi) of this section the...

40 CFR 60.64 - Test methods and procedures

Code of Federal Regulations, 2012 CFR

2012-07-01

... flow rate of effluent gas, where Cs and Qs are on the same basis (either wet or dry), dscf/hr; P = total kiln feed (dry basis) rate, ton/hr. For kilns constructed, modified or reconstructed on or after... associated alkali bypass and cooler) subject to the 10 percent opacity limit must follow the appropriate...

Down scaled Kjeldahl digestion and flow injection conductometric system for determination of protein content in some traditional northern Thai foods.

PubMed

Yanu, Pattama; Jakmunee, Jaroon

2017-09-01

A flow injection conductometric (FIC) system for determination of total Kjeldahl nitrogen (TKN) was developed for estimating total protein content in food. A small scale Kjeldahl digestion was performed with a short digestion time of only 20min. The digested solution was injected into the FIC system, and TKN was converted to ammonia gas in an alkaline donor stream of the system. The gas diffused through a membrane and dissolved into an acceptor stream causing an increase in conductivity as detected by a detector and recorded as a peak. Under the optimum condition, a linear calibration graph in the range of 4.00-100.00mgL -1 was obtained with LOD of 0.05mgL -1 . A good precision (0.04% RSD, n=11, 30.00mgNL -1 ) and high sample throughput of 72h -1 was achieved. The method was applied for determination of protein in some traditional northern Thai foods, revealing that they are good sources of proteins. Copyright © 2017 Elsevier Ltd. All rights reserved.

Oxygen consumption of a pneumatically controlled ventilator in a field anesthesia machine.

PubMed

Szpisjak, Dale F; Javernick, Elizabeth N; Kyle, Richard R; Austin, Paul N

2008-12-01

Field anesthesia machines (FAM) have been developed for remote locations where reliable supplies of compressed medical gases or electricity may be absent. In place of electricity, pneumatically controlled ventilators use compressed gas to power timing circuitry and actuate valves. We sought to determine the total O(2) consumption and ventilator gas consumption (drive gas [DG] plus pneumatic control [PC] gas) of a FAM's pneumatically controlled ventilator in mechanical models of high (HC) and low (LC) total thoracic compliance. The amount of total O(2) consumed by the Magellan-2200 (Oceanic Medical Products, Atchison, KS) FAM with pneumatically controlled ventilator was calculated using the ideal gas law and the measured mass of O(2) consumed from E cylinders. DG to the bellows canister assembly was measured with the Wright Respirometer Mk 8 (Ferraris Respiratory Europe, Hertford, UK). PC gas consumption was calculated by subtracting DG and fresh gas flow (FGF) from the total O(2) consumed from the E cylinder. The delivered tidal volume (V(T)) was measured with a pneumotach (Hans Rudolph, KS City, MO). Three different V(T) were tested (500, 750, and 1000 mL) with two lung models (HC and LC) using the Vent Aid Training Test Lung (MI Instruments, Grand Rapids, MI). Respiratory variables included an I:E of 1:2, FGF of 1 L/min, and respiratory rate of 10 breaths/min. Total O(2) consumption was directly proportional to V(T) and inversely proportional to compliance. The smallest total O(2) consumption rate (including FGF) was 9.3 +/- 0.4 L/min in the HC-500 model and the largest was 15.9 +/- 0.5 L/min in the LC-1000 model (P < 0.001). The mean PC circuitry consumption was 3.9 +/- 0.24 L/min or 390 mL +/- 24 mL/breath. To prepare for loss of central DG supply, patient safety will be improved by estimating cylinder duration for low total thoracic compliance. Using data from the smaller compliance and greatest V(T) model (LC-1000), a full O(2) E cylinder would be depleted in <42 min, whereas a full H cylinder would last approximately 433 min.

Exhaust bypass flow control for exhaust heat recovery

DOEpatents

Reynolds, Michael G.

2015-09-22

An exhaust system for an engine comprises an exhaust heat recovery apparatus configured to receive exhaust gas from the engine and comprises a first flow passage in fluid communication with the exhaust gas and a second flow passage in fluid communication with the exhaust gas. A heat exchanger/energy recovery unit is disposed in the second flow passage and has a working fluid circulating therethrough for exchange of heat from the exhaust gas to the working fluid. A control valve is disposed downstream of the first and the second flow passages in a low temperature region of the exhaust heat recovery apparatus to direct exhaust gas through the first flow passage or the second flow passage.

State-to-state modeling of non-equilibrium air nozzle flows

NASA Astrophysics Data System (ADS)

Nagnibeda, E.; Papina, K.; Kunova, O.

2018-05-01

One-dimensional non-equilibrium air flows in nozzles are studied on the basis of the state-to-state description of vibrational-chemical kinetics. Five-component mixture N2/O2/NO/N/O is considered taking into account Zeldovich exchange reactions of NO formation, dissociation, recombination and vibrational energy transitions. The equations for vibrational and chem-ical kinetics in a flow are coupled to the conservation equations of momentum and total energy and solved numerically for different conditions in a nozzle throat. The vibrational distributions of nitrogen and oxygen molecules, number densities of species as well as the gas temperature and flow velocity along a nozzle axis are analysed using the detailed state-to-state flow description and in the frame of the simplified one-temperature thermal equilibrium kinetic model. The comparison of the results showed the influence of non-equilibrium kinetics on macroscopic nozzle flow parameters. In the state-to-state approach, non-Boltzmann vibrational dis-tributions of N2 and O2 molecules with a plateau part at intermediate levels are found. The results are found with the use of the complete and simplified schemes of reactions and the impact of exchange reactions, dissociation and recombination on variation of vibrational level populations, mixture composition, gas velocity and temperature along a nozzle axis is shown.

Estimating Engine Airflow in Gas-Turbine Powered Aircraft with Clean and Distorted Inlet Flows

NASA Technical Reports Server (NTRS)

Williams, J. G.; Steenken, W. G.; Yuhas, A. J.

1996-01-01

The P404-GF-400 Powered F/A-18A High Alpha Research Vehicle (HARV) was used to examine the impact of inlet-generated total-pressure distortion on estimating levels of engine airflow. Five airflow estimation methods were studied. The Reference Method was a fan corrected airflow to fan corrected speed calibration from an uninstalled engine test. In-flight airflow estimation methods utilized the average, or individual, inlet duct static- to total-pressure ratios, and the average fan-discharge static-pressure to average inlet total-pressure ratio. Correlations were established at low distortion conditions for each method relative to the Reference Method. A range of distorted inlet flow conditions were obtained from -10 deg. to +60 deg. angle of attack and -7 deg. to +11 deg. angle of sideslip. The individual inlet duct pressure ratio correlation resulted in a 2.3 percent airflow spread for all distorted flow levels with a bias error of -0.7 percent. The fan discharge pressure ratio correlation gave results with a 0.6 percent airflow spread with essentially no systematic error. Inlet-generated total-pressure distortion and turbulence had no significant impact on the P404-GE400 engine airflow pumping. Therefore, a speed-flow relationship may provide the best airflow estimate for a specific engine under all flight conditions.

Propellant Feed Subsystem for a 26 kW flight arcjet propulsion system

NASA Astrophysics Data System (ADS)

Vaughan, C. E.; Morris, J. P.

1993-06-01

The USAF arcjet ATTD program demanded the development of a low-cost ammonia Propellant Feed Subsystem (PFS). A flow rate of 240 +/- 5 mg/sec during a total of ten 15-min ammonia outflows was required for the flight mission. The precision of the flow tolerance required a departure from the design of previous ammonia propellant feed systems. Since a propellant management device was not used, thermocapillary forces were explored as a means to limit outflow of liquid phase ammonia. A high energy density feedline heater with an internal wick was developed to guarantee that only gas phase propellant would reach the arcjet. A digital control algorithm was developed to implement bang-bang control of mass flow rate metered by a sonic venturi. Development tests of this system have been completed. The system is capable of continuous gas phase outflows regardless of orientation. Integrated tests with the arcjet and power conditioning unit have also been successfully completed.

Conceptual Mean-Line Design of Single and Twin-Shaft Oxy-Fuel Gas Turbine in a Semiclosed Oxy-Fuel Combustion Combined Cycle.

PubMed

Sammak, Majed; Thorbergsson, Egill; Grönstedt, Tomas; Genrup, Magnus

2013-08-01

The aim of this study was to compare single- and twin-shaft oxy-fuel gas turbines in a semiclosed oxy-fuel combustion combined cycle (SCOC-CC). This paper discussed the turbomachinery preliminary mean-line design of oxy-fuel compressor and turbine. The conceptual turbine design was performed using the axial through-flow code luax-t, developed at Lund University. A tool for conceptual design of axial compressors developed at Chalmers University was used for the design of the compressor. The modeled SCOC-CC gave a net electrical efficiency of 46% and a net power of 106 MW. The production of 95% pure oxygen and the compression of CO 2 reduced the gross efficiency of the SCOC-CC by 10 and 2 percentage points, respectively. The designed oxy-fuel gas turbine had a power of 86 MW. The rotational speed of the single-shaft gas turbine was set to 5200 rpm. The designed turbine had four stages, while the compressor had 18 stages. The turbine exit Mach number was calculated to be 0.6 and the calculated value of AN 2 was 40 · 10 6 rpm 2 m 2 . The total calculated cooling mass flow was 25% of the compressor mass flow, or 47 kg/s. The relative tip Mach number of the compressor at the first rotor stage was 1.15. The rotational speed of the twin-shaft gas generator was set to 7200 rpm, while that of the power turbine was set to 4800 rpm. A twin-shaft turbine was designed with five turbine stages to maintain the exit Mach number around 0.5. The twin-shaft turbine required a lower exit Mach number to maintain reasonable diffuser performance. The compressor turbine was designed with two stages while the power turbine had three stages. The study showed that a four-stage twin-shaft turbine produced a high exit Mach number. The calculated value of AN 2 was 38 · 10 6 rpm 2 m 2 . The total calculated cooling mass flow was 23% of the compressor mass flow, or 44 kg/s. The compressor was designed with 14 stages. The preliminary design parameters of the turbine and compressor were within established industrial ranges. From the results of this study, it was concluded that both single- and twin-shaft oxy-fuel gas turbines have advantages. The choice of a twin-shaft gas turbine can be motivated by the smaller compressor size and the advantage of greater flexibility in operation, mainly in the off-design mode. However, the advantages of a twin-shaft design must be weighed against the inherent simplicity and low cost of the simple single-shaft design.

Design of a safe facility for the metalorganic chemical vapor deposition of high-purity GaAs and AlGaAs

NASA Astrophysics Data System (ADS)

Messham, R. L.; Tucker, W. K.

1986-09-01

A metalorganic chemical vapor deposition (MOCVD) facility designed to safely handle highly toxic and pyrophoric growth materials is described. The system concept is based on remote operation, passive flow restriction, and forced air dilution to maintain safe gas concentrations under normal running and catastrophic system failure conditions. MOCVD is a key materials technology for advanced high-frequency optical and microwave devices. At this time, the use of highly toxic arsine as an arsenic source is dictated by critical device purity, reproducibility, and doping control requirements. The handling and use of this gas is a primary feature in the design of any safe facility for MOCVD growth of high-quality GaAs/AlGaAs. After a critical review of presently available effluent treatment techniques, it was concluded that a combination of flow restriction and dilution presented the most reliable treatment. Measured flow rates through orifices from 0.002 to 0.005 inch in diameter were compared to calculated values. A 0.002 inch orifice located in the cylinder valve or CGA fitting, combined with a cylinder of pure liquid arsine (205 psi), limits the maximum gas flow to ≪1 lpm. Such a flow can then be vented through a dedicated exhaust system where an additional forced injection of diluting air reduces the gas concentration to acceptable levels. In the final Westinghouse R&D Center design, the use of low-pressure pure arsine, flow restriction, and stack air injection has reduced the maximum stack exist gas concentration to below 25% of the IDLH level for arsine under total and catastrophic MOCVD facility equipment failure conditions. The elimination of potential problems with purging behind such orifices using carefully designed purging procedures and a microprocessor-controlled purging system are described. The IDLH level is defined by the OSHA and NIOSH standards completion program and represents the maximum level from which one could escape within 30 min without any escape-impairing symptoms or irreversible health effects.

Laser cross-flow gas system

DOEpatents

Duncan, D.B.

1992-11-24

A method and laser apparatus are disclosed which provide for a cross-flow of gas near one end of a laser discharge tube. The cross-flow of gas causes a concentration gradient which affects diffusion of contaminants in the discharge tube towards the cross-flow of the gas, which contaminants are then withdrawn from the discharge tube. 1 figure.

A Gas-Kinetic Scheme for Reactive Flows

NASA Technical Reports Server (NTRS)

Lian,Youg-Sheng; Xu, Kun

1998-01-01

In this paper, the gas-kinetic BGK scheme for the compressible flow equations is extended to chemical reactive flow. The mass fraction of the unburnt gas is implemented into the gas kinetic equation by assigning a new internal degree of freedom to the particle distribution function. The new variable can be also used to describe fluid trajectory for the nonreactive flows. Due to the gas-kinetic BGK model, the current scheme basically solves the Navier-Stokes chemical reactive flow equations. Numerical tests validate the accuracy and robustness of the current kinetic method.

Using Multi-Disciplinary Data to Compile a Hydrocarbon Budget for GC600, a Natural Seep in the Gulf of Mexico

NASA Astrophysics Data System (ADS)

MacDonald, I. R.; Johansen, C.; Marty, E.; Natter, M.; Silva, M.; Hill, J. C.; Viso, R. F.; Lobodin, V.; Diercks, A. R.; Woolsey, M.; Macelloni, L.; Shedd, W. W.; Joye, S. B.; Abrams, M.

2016-12-01

Fluid exchange between the deep subsurface and the overlying ocean and atmosphere occurs at hydrocarbon seeps along continental margins. Seeps are key features that alter the seafloor morphology and geochemically affect the sediments that support chemosynthetic communities. However, the dynamics and discharge rates of hydrocarbons at cold seeps remain largely unconstrained. Here we merge complementary geochemical (oil fingerprinting), geophysical (seismic, subbottom, backscatter, multibeam) and video/imaging (Video Time Lapse Camera, DSV ALVIN video) data sets to constrain pathways and magnitudes of hydrocarbon fluxes from the source rock to the seafloor at a well-studied, prolific seep site in the Northern Gulf of Mexico (GC600). Oil fingerprinting showed compositional similarities for samples from the following collections: the reservoir, an active vent, and the sea-surface. This was consistent with reservoir structures and pathways identified in seismic data. Video data, which showed the spatial distribution of seep indicators such as bacteria mats, or hydrate outcrops at the sediment interface, were combined with known hydrocarbon fluxes from the literature and used to quantify the total hydrocarbon fluxes in the seep domain. Using a systems approach, we combined data sets and published values at various scales and resolutions to compile a preliminary hydrocarbon budget for the GC600 seep site. Total estimated in-flow of hydrocarbons was 2.07 x 109 mol/yr. The combined total of out-flow and sequestration amounted to 7.56 x 106 mol/yr leaving a potential excess (in-flow - out-flow) of 2.06 x 109 mol/yr. Thus quantification of the potential out-flow from the seep domains based on observable processes does not equilibrate with the theoretical inputs from the reservoir. Processes that might balance this budget include accumulation of gas hydrate and sediment free-gas, as well as greater efficiency of biological sinks.

Cold dust in the giant barred galaxy NGC 1365

NASA Astrophysics Data System (ADS)

Tabatabaei, F. S.; Weiß, A.; Combes, F.; Henkel, C.; Menten, K. M.; Beck, R.; Kovács, A.; Güsten, R.

2013-07-01

Constraining the physcial properties of dust requires observations at submm wavelengths. This will provide important insight into the gas content of galaxies. We mapped NGC 1365 at 870 μm with LABOCA, the Large APEX Bolometer Camera, allowing us to probe the central mass concentration as well as the rate at which the gas flows to the center. We obtained the dust physical properties both globally and locally for different locations in the galaxy. A 20 K modified black body represents about 98% of the total dust content of the galaxy, the rest can be represented by a warmer dust component of 40 K. The bar exhibits an east-west asymmetry in the dust distribution: The eastern bar is heavier than the western bar by more than a factor of 4. Integrating the dust spectral energy distribution, we derived a total infrared luminosity, LTIR, of 9.8 × 1010 L⊙, leading to a dust-enshrouded star formation rate of SFRTIR ≃ 16.7 M⊙ yr-1 in NGC 1365. We derived the gas mass from the measurements of the dust emission, resulting in a CO-to-H2 conversion factor of XCO ≃ 1.2 × 1020 mol cm-2 (K km s-1)-1 in the central disk, including the bar. Taking into account the metallicity variation, the central gas mass concentration is only ≃20% at R < 40″ (3.6 kpc). On the other hand, the timescale on which the gas flows into the center, ≃300 Myr, is relatively short. This indicates that the current central mass in NGC 1365 is evolving fast because of the strong bar.

Polyport atmospheric gas sampler

DOEpatents

Guggenheim, S. Frederic

1995-01-01

An atmospheric gas sampler with a multi-port valve which allows for multi, sequential sampling of air through a plurality of gas sampling tubes mounted in corresponding gas inlet ports. The gas sampler comprises a flow-through housing which defines a sampling chamber and includes a gas outlet port to accommodate a flow of gases through the housing. An apertured sample support plate defining the inlet ports extends across and encloses the sampling chamber and supports gas sampling tubes which depend into the sampling chamber and are secured across each of the inlet ports of the sample support plate in a flow-through relation to the flow of gases through the housing during sampling operations. A normally closed stopper means mounted on the sample support plate and operatively associated with each of the inlet ports blocks the flow of gases through the respective gas sampling tubes. A camming mechanism mounted on the sample support plate is adapted to rotate under and selectively lift open the stopper spring to accommodate a predetermined flow of gas through the respective gas sampling tubes when air is drawn from the housing through the outlet port.

Part 1 of a Computational Study of a Drop-Laden Mixing Layer

NASA Technical Reports Server (NTRS)

Okong'o, Nora A.; Bellan, Josette

2004-01-01

This first of three reports on a computational study of a drop-laden temporal mixing layer presents the results of direct numerical simulations (DNS) of well-resolved flow fields and the derivation of the large-eddy simulation (LES) equations that would govern the larger scales of a turbulent flow field. The mixing layer consisted of two counterflowing gas streams, one of which was initially laden with evaporating liquid drops. The gas phase was composed of two perfect gas species, the carrier gas and the vapor emanating from the drops, and was computed in an Eulerian reference frame, whereas each drop was tracked individually in a Lagrangian manner. The flow perturbations that were initially imposed on the layer caused mixing and eventual transition to turbulence. The DNS database obtained included transitional states for layers with various liquid mass loadings. For the DNS, the gas-phase equations were the compressible Navier-Stokes equations for conservation of momentum and additional conservation equations for total energy and species mass. These equations included source terms representing the effect of the drops on the mass, momentum, and energy of the gas phase. From the DNS equations, the expression for the irreversible entropy production (dissipation) was derived and used to determine the dissipation due to the source terms. The LES equations were derived by spatially filtering the DNS set and the magnitudes of the terms were computed at transitional states, leading to a hierarchy of terms to guide simplification of the LES equations. It was concluded that effort should be devoted to the accurate modeling of both the subgridscale fluxes and the filtered source terms, which were the dominant unclosed terms appearing in the LES equations.

Custom ultrasonic instrumentation for flow measurement and real-time binary gas analysis in the CERN ATLAS experiment

NASA Astrophysics Data System (ADS)

Alhroob, M.; Battistin, M.; Berry, S.; Bitadze, A.; Bonneau, P.; Boyd, G.; Crespo-Lopez, O.; Degeorge, C.; Deterre, C.; Di Girolamo, B.; Doubek, M.; Favre, G.; Hallewell, G.; Katunin, S.; Lombard, D.; Madsen, A.; McMahon, S.; Nagai, K.; O'Rourke, A.; Pearson, B.; Robinson, D.; Rossi, C.; Rozanov, A.; Stanecka, E.; Strauss, M.; Vacek, V.; Vaglio, R.; Young, J.; Zwalinski, L.

2017-01-01

The development of custom ultrasonic instrumentation was motivated by the need for continuous real-time monitoring of possible leaks and mass flow measurement in the evaporative cooling systems of the ATLAS silicon trackers. The instruments use pairs of ultrasonic transducers transmitting sound bursts and measuring transit times in opposite directions. The gas flow rate is calculated from the difference in transit times, while the sound velocity is deduced from their average. The gas composition is then evaluated by comparison with a molar composition vs. sound velocity database, based on the direct dependence between sound velocity and component molar concentration in a gas mixture at a known temperature and pressure. The instrumentation has been developed in several geometries, with five instruments now integrated and in continuous operation within the ATLAS Detector Control System (DCS) and its finite state machine. One instrument monitors C3F8 coolant leaks into the Pixel detector N2 envelope with a molar resolution better than 2ṡ 10-5, and has indicated a level of 0.14 % when all the cooling loops of the recently re-installed Pixel detector are operational. Another instrument monitors air ingress into the C3F8 condenser of the new C3F8 thermosiphon coolant recirculator, with sub-percent precision. The recent effect of the introduction of a small quantity of N2 volume into the 9.5 m3 total volume of the thermosiphon system was clearly seen with this instrument. Custom microcontroller-based readout has been developed for the instruments, allowing readout into the ATLAS DCS via Modbus TCP/IP on Ethernet. The instrumentation has many potential applications where continuous binary gas composition is required, including in hydrocarbon and anaesthetic gas mixtures.

Volatile organic compound (VOC) emissions characterization during the flow-back phase of a hydraulically refractured well in the Uintah Basin, Utah using mobile PTR-MS measurements

NASA Astrophysics Data System (ADS)

Geiger, F.; Warneke, C.; Brown, S. S.; De Gouw, J. A.; Dube, W. P.; Edwards, P.; Gilman, J.; Graus, M.; Helleis, F.; Kofler, J.; Lerner, B. M.; Orphal, J.; Petron, G.; Roberts, J. M.; Zahn, A.

2014-12-01

Ongoing improvements in advanced technologies for crude oil and natural gas extraction from unconventional reserves, such as directional drilling and hydraulic fracturing, have greatly increased the production of fossil fuels within recent years. The latest forecasts even estimate an enhancement of 56% in total natural gas production due to increased development of shale gas, tight gas and offshore natural gas resources from 2012 to 2040 with the largest contribution from shale formations [US EIA: Annual Energy Outlook 2014]. During the field intensive 'Energy and Environment - Uintah Basin Winter Ozone Study (UBWOS)', measurements of volatile organic compounds (VOCs) were made using proton-transfer-reactions mass spectrometry (PTR-MS) at the ground site Horse Pool and using a mobile laboratory in the Uintah Basin, Utah, which is a region well known for intense fossil fuel production. A reworked gas well in the Red Wash fields was sampled regularly within two weeks performing mobile laboratory measurements downwind of the well site. The well had been recently hydraulically refractured at that time and waste water was collected into an open flow-back pond. Very high mixing ratios of aromatic hydrocarbons (C6-C13) up to the ppm range were observed coming from condensate and flow-back reservoirs. The measurements are used to determine sources of specific VOC emissions originating from the different parts of the well site and mass spectra are used to classify the air composition in contrast to samples taken at the Horse Pool field site and crude oil samples from South Louisiana. Enhancement ratios and time series of measured peak values for aromatics showed no clear trend, which indicates changes in emissions with operations at the site.

Stability of Gas Hydrates on Continental Margins: Implications of Subsurface Fluid Flow

NASA Astrophysics Data System (ADS)

Nunn, J. A.

2008-12-01

Gas hydrates are found at or just below the sediment-ocean interface in continental margins settings throughout the world. They are also found on land in high latitude regions such as the north slope of Alaska. While gas hydrate occurrence is common, gas hydrates are stable under a fairly restricted range of temperatures and pressures. In a purely conductive thermal regime, near surface temperatures depend on basal heat flow, thermal conductivity of sediments, and temperature at the sediment-water or sediment-air interface. Thermal conductivity depends on porosity and sediment composition. Gas hydrates are most stable in areas of low heat flow and high thermal conductivity which produce low temperature gradients. Older margins with thin continental crust and coarse grained sediments would tend to be colder. Another potentially important control on subsurface temperatures is advective heat transport by recharge/discharge of groundwater. Upward fluid flow depresses temperature gradients over a purely conductive regime with the same heat flow which would make gas hydrates more stable. Downward fluid flow would have the opposite effect. However, regional scale fluid flow may substantially increase heat flow in discharge areas which would destabilize gas hydrates. For example, discharge of topographically driven groundwater along the coast in the Central North Slope of Alaska has increased surface heat flow in some areas by more than 50% over a purely conductive thermal regime. Fluid flow also alters the pressure regime which can affect gas hydrate stability. Modeling results suggest a positive feedback between gas hydrate formation/disassociation and fluid flow. Disassociation of gas hydrates or permafrost due to global warming could increase permeability. This could enhance fluid flow and associated heat transport causing a more rapid and/or more spatially extensive gas hydrate disassociation than predicted solely from conductive propagation of temporal changes in surface or water bottom temperature. Model results from both the North Slope of Alaska and the Gulf of Mexico are compared.

Optimizing Natural Gas Networks through Dynamic Manifold Theory and a Decentralized Algorithm: Belgium Case Study

NASA Astrophysics Data System (ADS)

Koch, Caleb; Winfrey, Leigh

2014-10-01

Natural Gas is a major energy source in Europe, yet political instabilities have the potential to disrupt access and supply. Energy resilience is an increasingly essential construct and begins with transmission network design. This study proposes a new way of thinking about modelling natural gas flow. Rather than relying on classical economic models, this problem is cast into a time-dependent Hamiltonian dynamics discussion. Traditional Natural Gas constraints, including inelastic demand and maximum/minimum pipe flows, are portrayed as energy functions and built into the dynamics of each pipe flow. Doing so allows the constraints to be built into the dynamics of each pipeline. As time progresses in the model, natural gas flow rates find the minimum energy, thus the optimal gas flow rates. The most important result of this study is using dynamical principles to ensure the output of natural gas at demand nodes remains constant, which is important for country to country natural gas transmission. Another important step in this study is building the dynamics of each flow in a decentralized algorithm format. Decentralized regulation has solved congestion problems for internet data flow, traffic flow, epidemiology, and as demonstrated in this study can solve the problem of Natural Gas congestion. A mathematical description is provided for how decentralized regulation leads to globally optimized network flow. Furthermore, the dynamical principles and decentralized algorithm are applied to a case study of the Fluxys Belgium Natural Gas Network.

Compact permanent magnet H⁺ ECR ion source with pulse gas valve.

PubMed

Iwashita, Y; Tongu, H; Fuwa, Y; Ichikawa, M

2016-02-01

Compact H(+) ECR ion source using permanent magnets is under development. Switching the hydrogen gas flow in pulse operations can reduce the gas loads to vacuum evacuation systems. A specially designed piezo gas valve chops the gas flow quickly. A 6 GHz ECR ion source equipped with the piezo gas valve is tested. The gas flow was measured by a fast ion gauge and a few ms response time is obtained.

Probe measures gas and liquid mass flux in high mass flow ratio two-phase flows

NASA Technical Reports Server (NTRS)

Burick, R. J.

1972-01-01

Deceleration probe constructed of two concentric tubes with separator inlet operates successfully in flow fields where ratio of droplet flow rate to gas flow rate ranges from 1.0 to 20, and eliminates problems of local flow field disturbances and flooding. Probe is effective tool for characterization of liquid droplet/gas spray fields.

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.

The effect of heat and moisture exchanger and gas flow on humidity and temperature in a circle anaesthetic system.

PubMed

Poopalalingam, R; Goh, M H; Chan, Y W

2002-11-01

The aim of the study was to measure the humidity and temperature of the inspired gas in a circle absorber system at fresh gas flows of 11/min and 31/min and assess the need of a heat and moisture exchanger (HME). This prospective randomised controlled study received the Hospital Ethics Committee approval and informed consent. Forty adult ASA 1 and 11 patients were randomised into four groups to receive with or without HME fresh gas flow of 1L/min or 3L/min. Temperature and the relative humidity readings were taken at the start and every 10 minutes for the first hour of anaesthesia. There was a significantly higher relative humidity, absolute humidity and temperatures of the inspired gases at fresh gas flow of 1L/min and 3L/min with a HME compared to 3L/min without HME. Patients receiving fresh gas flows of lL/min had higher relative and absolute humidity than patients with fresh gas flows of 3L/min. However, the addition of the HME improved the absolute and relative humidity of the inspired gas in patients receiving fresh gas flow of 3l/min to a comparable level. However, the addition of a HME to a fresh gas flow of 1L/min did not significantly improve the humidity of the inspired gas. This suggests that the inherent humidifying property of the circle system at low fresh gas flow of 1L/min was sufficient in short surgeries lasting less than one hour and that the addition of a HME may not be necessary.

Effects of Non-Equilibrium Chemistry and Darcy-Forchheimer Flow of Pyrolysis Gas for a Charring Ablator

NASA Technical Reports Server (NTRS)

Chen, Yih-Kanq; Milos, Frank S.

2011-01-01

The Fully Implicit Ablation and Thermal Response code, FIAT, simulates pyrolysis and ablation of thermal protection materials and systems. The governing equations, which include energy conservation, a three-component decomposition model, and a surface energy balance, are solved with a moving grid. This work describes new modeling capabilities that are added to a special version of FIAT. These capabilities include a time-dependent pyrolysis gas flow momentum equation with Darcy-Forchheimer terms and pyrolysis gas species conservation equations with finite-rate homogeneous chemical reactions. The total energy conservation equation is also enhanced for consistency with these new additions. Parametric studies are performed using this enhanced version of FIAT. Two groups of analyses of Phenolic Impregnated Carbon Ablator (PICA) are presented. In the first group, an Orion flight environment for a proposed Lunar-return trajectory is considered. In the second group, various test conditions for arcjet models are examined. The central focus of these parametric studies is to understand the effect of pyrolysis gas momentum transfer on PICA material in-depth thermal responses with finite-rate, equilibrium, or frozen homogeneous gas chemistry. Results are presented, discussed, and compared with those predicted by the baseline PICA/FIAT ablation and thermal response model developed by the Orion Thermal Protection System Advanced Development Project.

40 CFR 86.120-94 - Gas meter or flow instrumentation calibration; particulate, methanol and formaldehyde measurement.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 19 2012-07-01 2012-07-01 false Gas meter or flow instrumentation... Procedures § 86.120-94 Gas meter or flow instrumentation calibration; particulate, methanol and formaldehyde... or flow instrumentation to determine flow through the particulate filters, methanol impingers and...

40 CFR 86.120-94 - Gas meter or flow instrumentation calibration; particulate, methanol and formaldehyde measurement.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 18 2011-07-01 2011-07-01 false Gas meter or flow instrumentation... Procedures § 86.120-94 Gas meter or flow instrumentation calibration; particulate, methanol and formaldehyde... or flow instrumentation to determine flow through the particulate filters, methanol impingers and...

40 CFR 86.120-94 - Gas meter or flow instrumentation calibration; particulate, methanol and formaldehyde measurement.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 19 2014-07-01 2014-07-01 false Gas meter or flow instrumentation... Procedures § 86.120-94 Gas meter or flow instrumentation calibration; particulate, methanol and formaldehyde... or flow instrumentation to determine flow through the particulate filters, methanol impingers and...

40 CFR 86.120-94 - Gas meter or flow instrumentation calibration; particulate, methanol and formaldehyde measurement.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 19 2013-07-01 2013-07-01 false Gas meter or flow instrumentation... Procedures § 86.120-94 Gas meter or flow instrumentation calibration; particulate, methanol and formaldehyde... or flow instrumentation to determine flow through the particulate filters, methanol impingers and...

40 CFR 86.120-94 - Gas meter or flow instrumentation calibration; particulate, methanol and formaldehyde measurement.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 18 2010-07-01 2010-07-01 false Gas meter or flow instrumentation... Procedures § 86.120-94 Gas meter or flow instrumentation calibration; particulate, methanol and formaldehyde... or flow instrumentation to determine flow through the particulate filters, methanol impingers and...

42 CFR 84.94 - Gas flow test; closed-circuit apparatus.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 1 2011-10-01 2011-10-01 false Gas flow test; closed-circuit apparatus. 84.94...-Contained Breathing Apparatus § 84.94 Gas flow test; closed-circuit apparatus. (a) Where oxygen is supplied... rated service time of the apparatus. (b) Where constant flow is used in conjunction with demand flow...

42 CFR 84.94 - Gas flow test; closed-circuit apparatus.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 1 2010-10-01 2010-10-01 false Gas flow test; closed-circuit apparatus. 84.94...-Contained Breathing Apparatus § 84.94 Gas flow test; closed-circuit apparatus. (a) Where oxygen is supplied... rated service time of the apparatus. (b) Where constant flow is used in conjunction with demand flow...

Extending green technology innovations to enable greener fabs

NASA Astrophysics Data System (ADS)

Takahisa, Kenji; Yoo, Young Sun; Fukuda, Hitomi; Minegishi, Yuji; Enami, Tatsuo

2015-03-01

Semiconductor manufacturing industry has growing concerns over future environmental impacts as fabs expand and new generations of equipment become more powerful. Especially rare gases supply and price are one of prime concerns for operation of high volume manufacturing (HVM) fabs. Over the past year it has come to our attention that Helium and Neon gas supplies could be unstable and become a threat to HVM fabs. To address these concerns, Gigaphoton has implemented various green technologies under its EcoPhoton program. One of the initiatives is GigaTwin deep ultraviolet (DUV) lithography laser design which enables highly efficient and stable operation. Under this design laser systems run with 50% less electric energy and gas consumption compared to conventional laser designs. In 2014 we have developed two technologies to further reduce electric energy and gas efficiency. The electric energy reduction technology is called eGRYCOS (enhanced Gigaphoton Recycled Chamber Operation System), and it reduces electric energy by 15% without compromising any of laser performances. eGRYCOS system has a sophisticated gas flow design so that we can reduce cross-flow-fan rotation speed. The gas reduction technology is called eTGM (enhanced Total gas Manager) and it improves gas management system optimizing the gas injection and exhaust amount based on laser performances, resulting in 50% gas savings. The next steps in our roadmap technologies are indicated and we call for potential partners to work with us based on OPEN INNOVATION concept to successfully develop faster and better solutions in all possible areas where green innovation may exist.

Gas-liquid two-phase flow pattern identification by ultrasonic echoes reflected from the inner wall of a pipe

NASA Astrophysics Data System (ADS)

Liang, Fachun; Zheng, Hongfeng; Yu, Hao; Sun, Yuan

2016-03-01

A novel ultrasonic pulse echo method is proposed for flow pattern identification in a horizontal pipe with gas-liquid two-phase flow. A trace of echoes reflected from the pipe’s internal wall rather than the gas-liquid interface is used for flow pattern identification. Experiments were conducted in a horizontal air-water two-phase flow loop. Two ultrasonic transducers with central frequency of 5 MHz were mounted at the top and bottom of the pipe respectively. The experimental results show that the ultrasonic reflection coefficient of the wall-gas interface is much larger than that of the wall-liquid interface due to the large difference in the acoustic impedance of gas and liquid. The stratified flow, annular flow and slug flow can be successfully recognized using the attenuation ratio of the echoes. Compared with the conventional ultrasonic echo measurement method, echoes reflected from the inner surface of a pipe wall are independent of gas-liquid interface fluctuation, sound speed, and gas and liquid superficial velocities, which makes the method presented a promising technique in field practice.

Studies in Three Phase Gas-Liquid Fluidised Systems

NASA Astrophysics Data System (ADS)

Awofisayo, Joyce Ololade

1992-01-01

Available from UMI in association with The British Library. The work is a logical continuation of research started at Aston some years ago when studies were conducted on fermentations in bubble columns. The present work highlights typical design and operating problems that could arise in such systems as waste water, chemical, biochemical and petroleum operations involving three-phase, gas-liquid -solid fluidisation; such systems are in increasing use. It is believed that this is one of few studies concerned with "true" three-phase, gas-liquid-solid fluidised systems, and that this work will contribute significantly to closing some of the gaps in knowledge in this area. The research work was experimentally based and involved studies of the hydrodynamic parameters, phase holdups (gas and solid), particle mixing and segregation, and phase flow dynamics (flow regime and circulation patterns). The studies have focused particularly on the solid behaviour and the influence of properties of solids present on the above parameters in three-phase, gas-liquid-solid fluidised systems containing single particle components and those containing binary and ternary mixtures of particles. All particles were near spherical in shape and two particle sizes and total concentration levels were used. Experiments were carried out in two- and three-dimensional bubble columns. Quantitative results are presented in graphical form and are supported by qualitative results from visual studies which are also shown as schematic diagrams and in photographic form. Gas and solid holdup results are compared for air-water containing single, binary and ternary component particle mixtures. It should be noted that the criteria for selection of the materials used are very important if true three-phase fluidisation is to be achieved: this is very evident when comparing the results with those in the literature. The fluid flow and circulation patterns observed were assessed for validation of the generally accepted patterns, and the author believes that the present work provides more accurate insight into the modelling of liquid circulation in bubble columns. The characteristic bubbly flow at low gas velocity in a two-phase system is suppressed in the three-phase system. The degree of mixing within the system is found to be dependent on flow regime, liquid circulation and the ratio of solid phase physical properties.

Coupling compositional liquid gas Darcy and free gas flows at porous and free-flow domains interface

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

Masson, R., E-mail: roland.masson@unice.fr; Team COFFEE INRIA Sophia Antipolis Méditerranée; Trenty, L., E-mail: laurent.trenty@andra.fr

This paper proposes an efficient splitting algorithm to solve coupled liquid gas Darcy and free gas flows at the interface between a porous medium and a free-flow domain. This model is compared to the reduced model introduced in [6] using a 1D approximation of the gas free flow. For that purpose, the gas molar fraction diffusive flux at the interface in the free-flow domain is approximated by a two point flux approximation based on a low-frequency diagonal approximation of a Steklov–Poincaré type operator. The splitting algorithm and the reduced model are applied in particular to the modelling of the massmore » exchanges at the interface between the storage and the ventilation galleries in radioactive waste deposits.« less

Aerodynamic improvement of the assembly through which gas conduits are taken into a smoke stack by simulating gas flow on a computer

NASA Astrophysics Data System (ADS)

Prokhorov, V. B.; Fomenko, M. V.; Grigor'ev, I. V.

2012-06-01

Results from computer simulation of gas flow motion for gas conduits taken on one and two sides into the gas-removal shaft of a smoke stack with a constant cross section carried out using the SolidWorks and FlowVision application software packages are presented.

Flowing gas, non-nuclear experiments on the gas core reactor

NASA Technical Reports Server (NTRS)

Kunze, J. F.; Suckling, D. H.; Copper, C. G.

1972-01-01

Flow tests were conducted on models of the gas core (cavity) reactor. Variations in cavity wall and injection configurations were aimed at establishing flow patterns that give a maximum of the nuclear criticality eigenvalue. Correlation with the nuclear effect was made using multigroup diffusion theory normalized by previous benchmark critical experiments. Air was used to simulate the hydrogen propellant in the flow tests, and smoked air, argon, or freon to simulate the central nuclear fuel gas. All tests were run in the down-firing direction so that gravitational effects simulated the acceleration effect of a rocket. Results show that acceptable flow patterns with high volume fraction for the simulated nuclear fuel gas and high flow rate ratios of propellant to fuel can be obtained. Using a point injector for the fuel, good flow patterns are obtained by directing the outer gas at high velocity along the cavity wall, using louvered or oblique-angle-honeycomb injection schemes.

Propagation of atmospheric pressure helium plasma jet into ambient air at laminar gas flow

NASA Astrophysics Data System (ADS)

Pinchuk, M.; Stepanova, O.; Kurakina, N.; Spodobin, V.

2017-05-01

The formation of an atmospheric pressure plasma jet (APPJ) in a gas flow passing through the discharge gap depends on both gas-dynamic properties and electrophysical parameters of the plasma jet generator. The paper presents the results of experimental and numerical study of the propagation of the APPJ in a laminar flow of helium. A dielectric-barrier discharge (DBD) generated inside a quartz tube equipped with a coaxial electrode system, which provided gas passing through it, served as a plasma source. The transition of the laminar regime of gas flow into turbulent one was controlled by the photography of a formed plasma jet. The corresponding gas outlet velocity and Reynolds numbers were revealed experimentally and were used to simulate gas dynamics with OpenFOAM software. The data of the numerical simulation suggest that the length of plasma jet at the unvarying electrophysical parameters of DBD strongly depends on the mole fraction of ambient air in a helium flow, which is established along the direction of gas flow.

Process for removal of sulfur compounds from fuel gases

DOEpatents

Moore, Raymond H.; Stegen, Gary E.

1978-01-01

Fuel gases such as those produced in the gasification of coal are stripped of sulfur compounds and particulate matter by contact with molten metal salt. The fuel gas and salt are intimately mixed by passage through a venturi or other constriction in which the fuel gas entrains the molten salt as dispersed droplets to a gas-liquid separator. The separated molten salt is divided into a major and a minor flow portion with the minor flow portion passing on to a regenerator in which it is contacted with steam and carbon dioxide as strip gas to remove sulfur compounds. The strip gas is further processed to recover sulfur. The depleted, minor flow portion of salt is passed again into contact with the fuel gas for further sulfur removal from the gas. The sulfur depleted, fuel gas then flows through a solid absorbent for removal of salt droplets. The minor flow portion of the molten salt is then recombined with the major flow portion for feed to the venturi.

Pulsatile flow and mass transport over an array of cylinders: gas transfer in a cardiac-driven artificial lung.

PubMed

Chan, Kit Yan; Fujioka, Hideki; Bartlett, Robert H; Hirschl, Ronald B; Grotberg, James B

2006-02-01

The pulsatile flow and gas transport of a Newtonian passive fluid across an array of cylindrical microfibers are numerically investigated. It is related to an implantable, artificial lung where the blood flow is driven by the right heart. The fibers are modeled as either squared or staggered arrays. The pulsatile flow inputs considered in this study are a steady flow with a sinusoidal perturbation and a cardiac flow. The aims of this study are twofold: identifying favorable array geometry/spacing and system conditions that enhance gas transport; and providing pressure drop data that indicate the degree of flow resistance or the demand on the right heart in driving the flow through the fiber bundle. The results show that pulsatile flow improves the gas transfer to the fluid compared to steady flow. The degree of enhancement is found to be significant when the oscillation frequency is large, when the void fraction of the fiber bundle is decreased, and when the Reynolds number is increased; the use of a cardiac flow input can also improve gas transfer. In terms of array geometry, the staggered array gives both a better gas transfer per fiber (for relatively large void fraction) and a smaller pressure drop (for all cases). For most cases shown, an increase in gas transfer is accompanied by a higher pressure drop required to power the flow through the device.

Using artificial intelligence to improve identification of nanofluid gas-liquid two-phase flow pattern in mini-channel

NASA Astrophysics Data System (ADS)

Xiao, Jian; Luo, Xiaoping; Feng, Zhenfei; Zhang, Jinxin

2018-01-01

This work combines fuzzy logic and a support vector machine (SVM) with a principal component analysis (PCA) to create an artificial-intelligence system that identifies nanofluid gas-liquid two-phase flow states in a vertical mini-channel. Flow-pattern recognition requires finding the operational details of the process and doing computer simulations and image processing can be used to automate the description of flow patterns in nanofluid gas-liquid two-phase flow. This work uses fuzzy logic and a SVM with PCA to improve the accuracy with which the flow pattern of a nanofluid gas-liquid two-phase flow is identified. To acquire images of nanofluid gas-liquid two-phase flow patterns of flow boiling, a high-speed digital camera was used to record four different types of flow-pattern images, namely annular flow, bubbly flow, churn flow, and slug flow. The textural features extracted by processing the images of nanofluid gas-liquid two-phase flow patterns are used as inputs to various identification schemes such as fuzzy logic, SVM, and SVM with PCA to identify the type of flow pattern. The results indicate that the SVM with reduced characteristics of PCA provides the best identification accuracy and requires less calculation time than the other two schemes. The data reported herein should be very useful for the design and operation of industrial applications.

Heating and cooling system for an on-board gas adsorbent storage vessel

DOEpatents

Tamburello, David A.; Anton, Donald L.; Hardy, Bruce J.; Corgnale, Claudio

2017-06-20

In one aspect, a system for controlling the temperature within a gas adsorbent storage vessel of a vehicle may include an air conditioning system forming a continuous flow loop of heat exchange fluid that is cycled between a heated flow and a cooled flow. The system may also include at least one fluid by-pass line extending at least partially within the gas adsorbent storage vessel. The fluid by-pass line(s) may be configured to receive a by-pass flow including at least a portion of the heated flow or the cooled flow of the heat exchange fluid at one or more input locations and expel the by-pass flow back into the continuous flow loop at one or more output locations, wherein the by-pass flow is directed through the gas adsorbent storage vessel via the by-pass line(s) so as to adjust an internal temperature within the gas adsorbent storage vessel.

The contribution of waste management to the reduction of greenhouse gas emissions with applications in the city of Bucharest.

PubMed

Sandulescu, Elena

2004-12-01

Waste management is a key process to protect the environment and conserve resources. The contribution of appropriate waste management measures to the reduction of greenhouse gas (GHG) emissions from the city of Bucharest was studied. An analysis of the distribution of waste flows into various treatment options was conducted using the material flows and stocks analysis (MFSA). An optimum scenario (i.e. municipal solid waste stream managed as: recycling of recoverable materials, 8%; incineration of combustibles, 60%; landfilling of non-combustibles, 32%) was modelled to represent the future waste management in Bucharest with regard to its relevance towards the potential for GHG reduction. The results indicate that it can contribute by 5.5% to the reduction of the total amount of GHGs emitted from Bucharest.

Magnetic roller gas gate employing transonic sweep gas flow to isolate regions of differing gaseous composition or pressure

DOEpatents

Doehler, Joachim

1994-12-20

Disclosed herein is an improved gas gate for interconnecting regions of differing gaseous composition and/or pressure. The gas gate includes a narrow, elongated passageway through which substrate material is adapted to move between said regions and inlet means for introducing a flow of non-contaminating sweep gas into a central portion of said passageway. The gas gate is characterized in that the height of the passageway and the flow rate of the sweep gas therethrough provides for transonic flow of the sweep gas between the inlet means and at least one of the two interconnected regions, thereby effectively isolating one region, characterized by one composition and pressure, from another region, having a differing composition and/or pressure, by decreasing the mean-free-path length between collisions of diffusing species within the transonic flow region. The gas gate preferably includes a manifold at the juncture point where the gas inlet means and the passageway interconnect.

Hemocompatibility and oxygenation performance of polysulfone membranes grafted with polyethylene glycol and heparin by plasma-induced surface modification.

PubMed

Wang, Weiping; Zheng, Zhi; Huang, Xin; Fan, Wenling; Yu, Wenkui; Zhang, Zhibing; Li, Lei; Mao, Chun

2017-10-01

Polyethylene glycol (PEG) and heparin (Hep) were grafted onto polysulfone (PSF) membrane by plasma-induced surface modification to prepare PSF-PEG-Hep membranes used for artificial lung. The effects of plasma treatment parameters, including power, gas type, gas flow rate, and treatment time, were investigated, and different PEG chains were bonded covalently onto the surface in the postplasma grafting process. Membrane surfaces were characterized by water contact angle, PEG grafting degree, attenuated total reflectance-Fourier transform infrared spectroscopy, ultraviolet-visible spectrophotometry, X-ray photoelectron spectroscopy, critical water permeability pressure, and scanning electron microscopy. Protein adsorption, platelet adhesion, and coagulation tests showed significant improvement in the hemocompatibility of PSF-PEG-Hep membranes compared to pristine PSF membrane. Gas exchange tests through PSF-PEG6000-Hep membrane showed that when the flow rate of porcine blood reached 5.0 L/min, the permeation fluxes of O 2 and CO 2 reached 192.6 and 166.9 mL/min, respectively, which were close to the gas exchange capacity of a commercial membrane oxygenator. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1737-1746, 2017. © 2016 Wiley Periodicals, Inc.

A miniature electrothermal thruster using microwave-excited microplasmas: Thrust measurement and its comparison with numerical analysis

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

Takao, Yoshinori; Eriguchi, Koji; Ono, Kouichi

2007-06-15

A microplasma thruster has been developed, consisting of a cylindrical microplasma source 10 mm long and 1.5 mm in inner diameter and a conical micronozzle 1.0-1.4 mm long with a throat of 0.12-0.2 mm in diameter. The feed or propellant gas employed is Ar at pressures of 10-100 kPa, and the surface-wave-excited plasma is established by 4.0 GHz microwaves at powers of <10 W. The thrust has been measured by a combination of target and pendulum methods, exhibiting the performance improved by discharging the plasma. The thrust obtained is 1.4 mN at an Ar gas flow rate of 60 SCCMmore » (1.8 mg/s) and a microwave power of 6 W, giving a specific impulse of 79 s and a thrust efficiency of 8.7%. The thrust and specific impulse are 0.9 mN and 51 s, respectively, in cold-gas operation. A comparison with numerical analysis indicates that the pressure thrust contributes significantly to the total thrust at low gas flow rates, and that the micronozzle tends to have an isothermal wall rather than an adiabatic.« less

Gas block mechanism for water removal in fuel cells

DOEpatents

Issacci, Farrokh; Rehg, Timothy J.

2004-02-03

The present invention is directed to apparatus and method for cathode-side disposal of water in an electrochemical fuel cell. There is a cathode plate. Within a surface of the plate is a flow field comprised of interdigitated channels. During operation of the fuel cell, cathode gas flows by convection through a gas diffusion layer above the flow field. Positioned at points adjacent to the flow field are one or more porous gas block mediums that have pores sized such that water is sipped off to the outside of the flow field by capillary flow and cathode gas is blocked from flowing through the medium. On the other surface of the plate is a channel in fluid communication with each porous gas block mediums. The method for water disposal in a fuel cell comprises installing the cathode plate assemblies at the cathode sides of the stack of fuel cells and manifolding the single water channel of each of the cathode plate assemblies to the coolant flow that feeds coolant plates in the stack.

40 CFR 1065.248 - Gas divider.

Code of Federal Regulations, 2010 CFR

2010-07-01

... testing. You may use critical-flow gas dividers, capillary-tube gas dividers, or thermal-mass-meter gas... PROCEDURES Measurement Instruments Flow-Related Measurements § 1065.248 Gas divider. (a) Application. You may...

Gas flow rate dependence of the discharge characteristics of a helium atmospheric pressure plasma jet interacting with a substrate

NASA Astrophysics Data System (ADS)

Yan, Wen; Economou, Demetre J.

2017-10-01

A 2D (axisymmetric) computational study of the discharge characteristics of an atmospheric pressure plasma jet as a function of gas flow rate was performed. The helium jet emerged from a dielectric tube, with an average gas flow velocity in the range 2.5-20 m s-1 (1 atm, 300 K) in a nitrogen ambient, and impinged on a substrate a short distance dowstream. The effect of the substrate conductivity (conductror versus insulator) was also studied. Whenever possible, simulation predictions were compared with published experimental observations. Discharge ignition and propagation in the dielectric tube were hardly affected by the He gas flow velocity. Most properties of the plasma jet, however, depended sensitively on the He gas flow velocity, which determined the concentration distributions of helium and nitrogen in the mixing layer forming in the gap between the tube exit and the substrate. At low gas flow velocity, the plasma jet evolved from a hollow (donut-shaped) feature to one where the maximum of electron density was on axis. When the gas flow velocity was high, the plasma jet maintained its hollow structure until it struck the substrate. For a conductive substrate, the radial ion fluxes to the surface were relatively uniform over a radius of ~0.4-0.8 mm, and the dominant ion flux was that of He+. For a dielectric substrate, the radial ion fluxes to the surface peaked on the symmetry axis at low He gas flow velocity, but a hollow ion flux distribution was observed at high gas flow velocity. At the same time, the main ion flux switched from N2+ to He2+ as the He gas flow velocity increased from a low to a high value. The diameter of the plasma ‘footprint’ on the substrate first increased with increasing He gas flow velocity, and eventually saturated with further increases in velocity.

Precision control of high temperature furnaces using an auxiliary power supply and charged particle current flow

DOEpatents

Pollock, G.G.

1997-01-28

Two power supplies are combined to control a furnace. A main power supply heats the furnace in the traditional manner, while the power from the auxiliary supply is introduced as a current flow through charged particles existing due to ionized gas or thermionic emission. The main power supply provides the bulk heating power and the auxiliary supply provides a precise and fast power source such that the precision of the total power delivered to the furnace is improved. 5 figs.

42 CFR 84.93 - Gas flow test; open-circuit apparatus.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 1 2011-10-01 2011-10-01 false Gas flow test; open-circuit apparatus. 84.93...-Contained Breathing Apparatus § 84.93 Gas flow test; open-circuit apparatus. (a) A static-flow test will be performed on all open-circuit apparatus. (b) The flow from the apparatus shall be greater than 200 liters...

42 CFR 84.93 - Gas flow test; open-circuit apparatus.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 1 2010-10-01 2010-10-01 false Gas flow test; open-circuit apparatus. 84.93...-Contained Breathing Apparatus § 84.93 Gas flow test; open-circuit apparatus. (a) A static-flow test will be performed on all open-circuit apparatus. (b) The flow from the apparatus shall be greater than 200 liters...

A Physical Model Study of Two-Phase Gas-Liquid Flows in a Ladle Shroud

NASA Astrophysics Data System (ADS)

Singh, Prince K.; Mazumdar, Dipak

2018-06-01

Argon-steel flows inside a ladle shroud during teeming from a ladle to a tundish have been modelled physically. To this end, full-scale Perspex models of bloom as well as slab casting shrouds (BCS and SCS), operating with air and water, have been applied. Both open to air as well as immersed conditions were investigated with and without gas injection. Flows inside a ladle shroud under open to air and immersed conditions were found to be substantially different with a strong function of gas and liquid flow rates, collector nozzle and shroud diameters. Depending on the volumetric gas injection rate relative to liquid flow rate, different flow regimes have been observed in an immersed shroud [ i.e., 0 < ( ds/L_{s} ) ≤ 0.24 ]. At extremely low gas flow rates, [ i.e., ( Qg/Q_{L} ) ≤ 0.02 ], injected gas is completely entrained as bubbles by the down-flowing liquid resulting in a bubbly two-phase flow over the entire length of a shroud. However, with an increasing gas flow rate, two distinctly different regions start to develop within the shroud body: a free liquid jet in the upper part and a gas-liquid mixing zone below. The length of the free jet increases with an increasing gas flow rate and at significantly higher gas to liquid flow rates [ viz., ( Qg/Q_{L} )_{BCS} ≥ 0.42 ] and [ viz., ( Qg/Q_{L} )_{SCS} ≥ 0.30 ] , and the free jet is found to prevail over the entire length of the shroud. Within the range of conditions studied, it is observed that the free jet length or the line of demarcation between the jetting and two-phase mixing zone depends on gas and liquid flow rates and is specific to a particular shroud-collector nozzle system. Physical model results further indicate that a sufficiently large free jet length ( shroud length) tends to create a high pressure region inside a shroud and prevent ingression of air. Possible implications of the present findings with reference to industrial teeming practices are also discussed in the text.

40 CFR 63.3168 - What are the requirements for continuous parameter monitoring system installation, operation, and...

Code of Federal Regulations, 2012 CFR

2012-07-01

... regenerative carbon adsorber as an add-on control device, you must monitor the total regeneration desorbing gas (e.g., steam or nitrogen) mass flow for each regeneration cycle, the carbon bed temperature after each regeneration and cooling cycle, and comply with paragraphs (a)(3) through (5) and (d)(1) and (2...

Study of argon-oxygen flowing afterglow

NASA Astrophysics Data System (ADS)

Mazánková, V.; Trunec, D.; Navrátil, Z.; Raud, J.; Krčma, F.

2016-06-01

The reaction kinetics in argon-oxygen flowing afterglow (post-discharge) was studied using NO titration and optical emission spectroscopy. The flowing DC post-discharge in argon-oxygen mixture was created in a quartz tube at the total gas pressure of 1000 Pa and discharge power of 90 W. The O(3P) atom concentration was determined by NO titration at different places along the flow tube. The optical emission spectra were also measured along the flow tube. Argon spectral lines, oxygen lines at 777 nm and 844.6 nm and atmospheric A-band of {{\\text{O}}2} were identified in the spectra. Rotational temperature of {{\\text{O}}2} was determined from the oxygen atmospheric A-band and also the outer wall temperature of the flow tube was measured by a thermocouple and by an IR thermometer. A zero-dimensional kinetic model for the reactions in the afterglow was developed. This model allows the time dependencies of particle concentrations and of gas temperature to be calculated. The wall recombination probability for O(3P) atoms {γ\\text{O≤ft(\\text{P}\\right)}}=≤ft(1.63+/- 0.06\\right)× {{10}-3} and wall deactivation probability for {{\\text{O}}2} (b {{}1}Σ\\text{g}+ ) molecules {γ{{\\text{O}2}≤ft(\\text{b}\\right)}}=≤ft(1.7+/- 0.1\\right)× {{10}-3} were determined from the fit of model results to experimental data. Sensitivity analysis was applied for the analysis of kinetic model in order to reveal the most important reactions in the model. The calculated gas temperature increases in the afterglow and then decreases at later afterglow times after reaching the maximum. This behavior is in good agreement with the spatial rotational temperature dependence. A similar trend was also observed at outer wall temperature measurement.

Recirculating rotary gas compressor

DOEpatents

Weinbrecht, John F.

1992-01-01

A positive displacement, recirculating Roots-type rotary gas compressor which operates on the basis of flow work compression. The compressor includes a pair of large diameter recirculation conduits (24 and 26) which return compressed discharge gas to the compressor housing (14), where it is mixed with low pressure inlet gas, thereby minimizing adiabatic heating of the gas. The compressor includes a pair of involutely lobed impellers (10 and 12) and an associated port configuration which together result in uninterrupted flow of recirculation gas. The large diameter recirculation conduits equalize gas flow velocities within the compressor and minimize gas flow losses. The compressor is particularly suited to applications requiring sustained operation at higher gas compression ratios than have previously been feasible with rotary pumps, and is particularly applicable to refrigeration or other applications requiring condensation of a vapor.

Recirculating rotary gas compressor

DOEpatents

Weinbrecht, J.F.

1992-02-25

A positive displacement, recirculating Roots-type rotary gas compressor is described which operates on the basis of flow work compression. The compressor includes a pair of large diameter recirculation conduits which return compressed discharge gas to the compressor housing, where it is mixed with low pressure inlet gas, thereby minimizing adiabatic heating of the gas. The compressor includes a pair of involutely lobed impellers and an associated port configuration which together result in uninterrupted flow of recirculation gas. The large diameter recirculation conduits equalize gas flow velocities within the compressor and minimize gas flow losses. The compressor is particularly suited to applications requiring sustained operation at higher gas compression ratios than have previously been feasible with rotary pumps, and is particularly applicable to refrigeration or other applications requiring condensation of a vapor. 12 figs.

Staged membrane oxidation reactor system

DOEpatents

Repasky, John Michael; Carolan, Michael Francis; Stein, VanEric Edward; Chen, Christopher Ming-Poh

2014-05-20

Ion transport membrane oxidation system comprising (a) two or more membrane oxidation stages, each stage comprising a reactant zone, an oxidant zone, one or more ion transport membranes separating the reactant zone from the oxidant zone, a reactant gas inlet region, a reactant gas outlet region, an oxidant gas inlet region, and an oxidant gas outlet region; (b) an interstage reactant gas flow path disposed between each pair of membrane oxidation stages and adapted to place the reactant gas outlet region of a first stage of the pair in flow communication with the reactant gas inlet region of a second stage of the pair; and (c) one or more reactant interstage feed gas lines, each line being in flow communication with any interstage reactant gas flow path or with the reactant zone of any membrane oxidation stage receiving interstage reactant gas.

Integrated control system and method

DOEpatents

Wang, Paul Sai Keat; Baldwin, Darryl; Kim, Myoungjin

2013-10-29

An integrated control system for use with an engine connected to a generator providing electrical power to a switchgear is disclosed. The engine receives gas produced by a gasifier. The control system includes an electronic controller associated with the gasifier, engine, generator, and switchgear. A gas flow sensor monitors a gas flow from the gasifier to the engine through an engine gas control valve and provides a gas flow signal to the electronic controller. A gas oversupply sensor monitors a gas oversupply from the gasifier and provides an oversupply signal indicative of gas not provided to the engine. A power output sensor monitors a power output of the switchgear and provide a power output signal. The electronic controller changes gas production of the gasifier and the power output rating of the switchgear based on the gas flow signal, the oversupply signal, and the power output signal.

Staged membrane oxidation reactor system

DOEpatents

Repasky, John Michael; Carolan, Michael Francis; Stein, VanEric Edward; Chen, Christopher Ming-Poh

2013-04-16

Ion transport membrane oxidation system comprising (a) two or more membrane oxidation stages, each stage comprising a reactant zone, an oxidant zone, one or more ion transport membranes separating the reactant zone from the oxidant zone, a reactant gas inlet region, a reactant gas outlet region, an oxidant gas inlet region, and an oxidant gas outlet region; (b) an interstage reactant gas flow path disposed between each pair of membrane oxidation stages and adapted to place the reactant gas outlet region of a first stage of the pair in flow communication with the reactant gas inlet region of a second stage of the pair; and (c) one or more reactant interstage feed gas lines, each line being in flow communication with any interstage reactant gas flow path or with the reactant zone of any membrane oxidation stage receiving interstage reactant gas.

Staged membrane oxidation reactor system

DOEpatents

Repasky, John Michael; Carolan, Michael Francis; Stein, VanEric Edward; Chen, Christopher Ming-Poh

2012-09-11

Ion transport membrane oxidation system comprising (a) two or more membrane oxidation stages, each stage comprising a reactant zone, an oxidant zone, one or more ion transport membranes separating the reactant zone from the oxidant zone, a reactant gas inlet region, a reactant gas outlet region, an oxidant gas inlet region, and an oxidant gas outlet region; (b) an interstage reactant gas flow path disposed between each pair of membrane oxidation stages and adapted to place the reactant gas outlet region of a first stage of the pair in flow communication with the reactant gas inlet region of a second stage of the pair; and (c) one or more reactant interstage feed gas lines, each line being in flow communication with any interstage reactant gas flow path or with the reactant zone of any membrane oxidation stage receiving interstage reactant gas.

Ejector Enhanced Pulsejet Based Pressure Gain Combustors: An Old Idea With a New Twist

NASA Technical Reports Server (NTRS)

Paxson, Daniel E.; Dougherty, Kevin T.

2005-01-01

An experimental investigation of pressure-gain combustion for gas turbine application is described. The test article consists of an off-the-shelf valved pulsejet, and an optimized ejector, both housed within a shroud. The combination forms an effective can combustor across which there is a modest total pressure rise rather than the usual loss found in conventional combustors. Although the concept of using a pulsejet to affect semi-constant volume (i.e., pressure-gain) combustion is not new, that of combining it with a well designed ejector to efficiently mix the bypass flow is. The result is a device which to date has demonstrated an overall pressure rise of approximately 3.5 percent at an overall temperature ratio commensurate with modern gas turbines. This pressure ratio is substantially higher than what has been previously reported in pulsejet-based combustion experiments. Flow non-uniformities in the downstream portion of the device are also shown to be substantially reduced compared to those within the pulsejet itself. The standard deviation of total pressure fluctuations, measured just downstream of the ejector was only 5.0 percent of the mean. This smoothing aspect of the device is critical to turbomachinery applications since turbine performance is, in general, negatively affected by flow non-uniformities and unsteadiness. The experimental rig will be described and details of the performance measurements will be presented. Analyses showing the thermodynamic benefits from this level of pressure-gain performance in a gas turbine will also be assessed for several engine types. Issues regarding practical development of such a device are discussed, as are potential emissions reductions resulting from the rich burning nature of the pulsejet and the rapid mixing (quenching) associated with unsteady ejectors.

Economic analysis of condensers for water recovery in steam injected gas turbines

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

De Paepe, M.; Huvenne, P.; Dick, E.

1998-07-01

Steam injection cycles are interesting for small power ranges because of the high efficiency and the relatively low investment costs. A big disadvantage is the consumption of water by the cycle. Water recovery is seldom realized in industrial practice. In this paper an analysis of the technical and economical possibilities of water recovery by condensation of water out of the exhaust gases is made. Three gas turbines are considered : the Kawasaki M1A-13CC (2.3 MWe), the Allison 501KH (6.8 MWe) and the General Electric LM1600 (17 MWe). For every gas turbine two types of condensers are designed. In the watermore » cooled condenser finned tubes are used to cool the exhaust gases, flowing at the outside of the tubes. The water itself flows at the inside of the tubes and is cooled by a water to air cooler. In the air cooled condenser the exhaust gases flow at the inside of the tubes and the cooling air at the outside. The investment costs of the condensers is compared to the costs of the total installation. The investment costs are relatively smaller if the produced power goes up. The water cooled condenser with water to air cooler is cheaper than the air cooled condenser. Using a condenser results in higher exploitation costs due to the fans and pumps. It is shown that the air cooled condenser has lower exploitation costs than the water cooled one. Pay back time of the total installation does not significantly vary compared to the installation without recovery. Water prices are determined for which water recovery is profitable. For the water cooled condenser the turning point lies at 2.2 Euro/m; for the air cooled condenser this is 0.6 Euro/m.« less

CHANDRA Observations OF The Shock Heated Gas Around 3c 288 And 3c 449

NASA Astrophysics Data System (ADS)

Lal, Dharam V.; Kraft, R. P.; Evans, D. A.; Hardcastle, M. J.; Nulsen, P. E. J.; Croston, J. H.; Forman, W. R.; Jones, C.; Lee, J. C.

2010-03-01

The inflation of radio bubbles in the hot gas atmospheres of clusters of galaxies plays an important role in the overall energy budget of the ICM. Regular gentle (i.e. subsonic) nuclear outbursts may be able to provide sufficient energy to the gas in the cool cores of clusters to offset radiative losses and regulate large cooling flows; and one method to supplement the total energy input into the gas is for the lobes to initially drive strong shocks into the gas. We present results from Chandra/ACIS-S observations of the hot gas atmospheres of two powerful, nearby radio galaxies in poor clusters: 3C 288 and 3C 449. We measure the total energy of the current outburst to be a few times 10^{59} ergs for 3C 288 (T = 2.8 keV, L_X = 1.4 × 10^{44} ergs) and ˜10^{58} ergs for 3C 449 (T = 1.5 keV, L_X = 2.0 × 10^{42} ergs). We find multiple surface brightness discontinuities in the gas, which are probably shocks and are indicative of supersonic heating by the inflation of the radio lobe. We do not find X-ray cavity in 3C 288, whereas cavities are associated with both the radio lobes in 3C 449.

A study of gas flow pattern, undercutting and torch modification in variable polarity plasma arc welding

NASA Technical Reports Server (NTRS)

Mcclure, John C.; Hou, Haihui Ron

1994-01-01

A study on the plasma and shield gas flow patterns in variable polarity plasma arc (VPPA) welding was undertaken by shadowgraph techniques. Visualization of gas flow under different welding conditions was obtained. Undercutting is often present with aluminum welds. The effects of torch alignment, shield gas flow rate and gas contamination on undercutting were investigated and suggestions made to minimize the defect. A modified shield cup for the welding torch was fabricated which consumes much less shield gas while maintaining the weld quality. The current torch was modified with a trailer flow for Al-Li welding, in which hot cracking is a critical problem. The modification shows improved weldablility on these alloys.

Study on Gas-liquid Falling Film Flow in Internal Heat Integrated Distillation Column

NASA Astrophysics Data System (ADS)

Liu, Chong

2017-10-01

Gas-liquid internally heat integrated distillation column falling film flow with nonlinear characteristics, study on gas liquid falling film flow regulation control law, can reduce emissions of the distillation column, and it can improve the quality of products. According to the distribution of gas-liquid mass balance internally heat integrated distillation column independent region, distribution model of heat transfer coefficient of building internal heat integrated distillation tower is obtained liquid distillation falling film flow in the saturated vapour pressure of liquid water balance, using heat transfer equation and energy equation to balance the relationship between the circulating iterative gas-liquid falling film flow area, flow parameter information, at a given temperature, pressure conditions, gas-liquid flow falling film theory makes the optimal parameters to achieve the best fitting value with the measured values. The results show that the geometric gas-liquid internally heat integrated distillation column falling film flow heat exchange area and import column thermostat, the average temperature has significant. The positive correlation between the heat exchanger tube entrance due to temperature difference between inside and outside, the heat flux is larger, with the increase of internal heat integrated distillation column temperature, the slope decreases its temperature rise, which accurately describes the internal gas-liquid heat integrated distillation tower falling film flow regularity, take appropriate measures to promote the enhancement of heat transfer. It can enhance the overall efficiency of the heat exchanger.

Galileo observations of volcanic plumes on Io

USGS Publications Warehouse

Geissler, P.E.; McMillan, M.T.

2008-01-01

Io's volcanic plumes erupt in a dazzling variety of sizes, shapes, colors and opacities. In general, the plumes fall into two classes, representing distinct source gas temperatures. Most of the Galileo imaging observations were of the smaller, more numerous Prometheus-type plumes that are produced when hot flows of silicate lava impinge on volatile surface ices of SO2. Few detections were made of the giant, Pele-type plumes that vent high temperature, sulfur-rich gases from the interior of Io; this was partly because of the insensitivity of Galileo's camera to ultraviolet wavelengths. Both gas and dust spout from plumes of each class. Favorably located gas plumes were detected during eclipse, when Io was in Jupiter's shadow. Dense dust columns were imaged in daylight above several Prometheus-type eruptions, reaching heights typically less than 100 km. Comparisons between eclipse observations, sunlit images, and the record of surface changes show that these optically thick dust columns are much smaller in stature than the corresponding gas plumes but are adequate to produce the observed surface deposits. Mie scattering calculations suggest that these conspicuous dust plumes are made up of coarse grained “ash” particles with radii on the order of 100 nm, and total masses on the order of 106 kg per plume. Long exposure images of Thor in sunlight show a faint outer envelope apparently populated by particles small enough to be carried along with the gas flow, perhaps formed by condensation of sulfurous “snowflakes” as suggested by the plasma instrumentation aboard Galileo as it flew through Thor's plume [Frank, L.A., Paterson, W.R., 2002. J. Geophys. Res. (Space Phys.) 107, doi:10.1029/2002JA009240. 31-1]. If so, the total mass of these fine, nearly invisible particles may be comparable to the mass of the gas, and could account for much of Io's rapid resurfacing.

Swirling flow of a dissociated gas

NASA Technical Reports Server (NTRS)

Wolfram, W. R., Jr.; Walker, W. F.

1975-01-01

Most physical applications of the swirling flow, defined as a vortex superimposed on an axial flow in the nozzle, involve high temperatures and the possibility of real gas effects. The generalized one-dimensional swirling flow in a converging-diverging nozzle is analyzed for equilibrium and frozen dissociation using the ideal dissociating gas model. Numerical results are provided to illustrate the major effects and to compare with results obtained for a perfect gas with constant ratio of specific heats. It is found that, even in the case of real gases, perfect gas calculations can give a good estimate of the reduction in mass flow due to swirl.

Apparatus for dispensing compressed natural gas and liquified natural gas to natural gas powered vehicles

DOEpatents

Bingham, Dennis A.; Clark, Michael L.; Wilding, Bruce M.; Palmer, Gary L.

2007-05-29

A fueling facility and method for dispensing liquid natural gas (LNG), compressed natural gas (CNG) or both on-demand. The fueling facility may include a source of LNG, such as cryogenic storage vessel. A low volume high pressure pump is coupled to the source of LNG to produce a stream of pressurized LNG. The stream of pressurized LNG may be selectively directed through an LNG flow path or to a CNG flow path which includes a vaporizer configured to produce CNG from the pressurized LNG. A portion of the CNG may be drawn from the CNG flow path and introduced into the CNG flow path to control the temperature of LNG flowing therethrough. Similarly, a portion of the LNG may be drawn from the LNG flow path and introduced into the CNG flow path to control the temperature of CNG flowing therethrough.

Method and apparatus for dispensing compressed natural gas and liquified natural gas to natural gas powered vehicles

DOEpatents

Bingham, Dennis A.; Clark, Michael L.; Wilding, Bruce M.; Palmer, Gary L.

2005-05-31

A fueling facility and method for dispensing liquid natural gas (LNG), compressed natural gas (CNG) or both on-demand. The fueling facility may include a source of LNG, such as cryogenic storage vessel. A low volume high pressure pump is coupled to the source of LNG to produce a stream of pressurized LNG. The stream of pressurized LNG may be selectively directed through an LNG flow path or to a CNG flow path which includes a vaporizer configured to produce CNG from the pressurized LNG. A portion of the CNG may be drawn from the CNG flow path and introduced into the CNG flow path to control the temperature of LNG flowing therethrough. Similarly, a portion of the LNG may be drawn from the LNG flow path and introduced into the CNG flow path to control the temperature of CNG flowing therethrough.

Use of Inert Gases to Study the Interaction of Blood Flow and Diffusion during Passive Absorption from the Gastrointestinal Tract of the Rat

PubMed Central

Levitt, Michael D.; Levitt, David G.

1973-01-01

Measurement of the relative absorption rates of inert gases (H2, He, CH4, SF6, and 133Xe) was used to investigate the interaction between diffusion and blood flow during passive absorption from the stomach, small bowel, and colon of the rat. If uptake is blood flow limited, the gases should be absorbed in proportion to their solubilities in blood, but if diffusion limited, uptake should be proportional to the diffusion rate of the gases in mucosal tissues. The observed absorption data were fitted to a series of models of interaction between perfusion and diffusion. A simple model accurately predicted the absorption rates of the gases from all segments of bowel. In this model, gas is absorbed into two distinct blood flows: one which flows in proximity to the lumen and completely equilibrates with the lumen, and a second which is sufficiently rapid and distant from the lumen that its gas uptake is entirely diffusion limited. The fraction of the total absorption attributable to the equilibrating flow can be readily calculated and equalled 93%, 77%, and 33% for the small bowel, colon, and stomach, respectively. Thus the rate of passive absorption of gases from the small bowel is limited almost entirely by the blood flow to the mucosa, and absorption from the stomach is largely limited by the diffusion rate of the gases. The flow which equilibrates with the lumen can be quantitated, and this flow may provide a useful measure of “effective” mucosal blood flow. Images PMID:4719667

QATAR offshore oil

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

Not Available

The Qatar Petroleum Producing Authority is presently operating three offshore fields - Idd al-Shargi, Maydan Mahzam and Bul Hanine. The Idd al-Shargi field consists of 14 naturally flowing wells and three suspended wells. Individual flow rates of the producing wells range from 250 to 3000 barrels per day (b/d). The Maydan Mahzam field produces from 11 naturally flowing wells. Reservoir energy in the field is maintained by water injection. Each of the wells produce oil at rates ranging from 2500 to 20,000 b/d. The Bul Hanine field comprises 10 producing wells supported by 9 dumpflooders. Production rates of the individualmore » wells reach 29,000 b/d, making them among the world's highest. In 1978 the completion of a major acceleration project for the Bul Hanine Arab IV reservoir added more than 40,000 b/d to the production potential of the field. Total Qatari oil exports in 1978 were 91,708,000 barrels, equivalent to an average export rate of 25,000 b/d. Total production in Qatar in 1979 was 100,641,394 barrels (offshore) and 84,130,917 (onshore), an increase of 11% and a decrease of 3%, respectively, over 1978. Halal Island provides offshore storage for oil and gas berthing and loading operations. A natural gas liquids offshore complex, including a fractionation plant, is nearing completion at Umm Said. (SAC)« less

Breakdown characteristics of atmospheric dielectric barrier discharge in gas flow condition

NASA Astrophysics Data System (ADS)

Fan, Zhihui; Yan, Huijie; Wang, Yuying; Liu, Yidi; Guo, Hongfei; Ren, Chunsheng

2018-05-01

Experimental investigations of the breakdown characteristics of plate-to-plate dielectric barrier discharge excited by an AC source at different gas flow conditions are carried out. The ignition voltage for the appearance of the very first discharge filament and the breakdown voltage in each discharge half cycle in continuous operation are examined. As revealed by the results of the indoor air experiment, the ignition voltage manifests a monotonous increase with the increase in the gas flow rate, while the breakdown voltage has a marked decline at the low gas flow rate and increases slightly as the gas flow rate is higher than 10 m/s. As regards the obvious decreases in the ignition voltage and breakdown voltage, the decrease in the humidity with the increase in the gas flow rate plays a dominant role. As regards the increase in breakdown voltage, the memory effect from the preceding discharge is considered. The losses of metastable particles, together with particles having high translational energy in the gas flow, are considered to be the most critical factors.

Asymptotic research of transonic gas flows

NASA Astrophysics Data System (ADS)

Velmisov, Petr A.; Tamarova, Yuliya A.

2017-12-01

The article is dedicated to the development asymptotic theory of gas flowing at speed next to sound velocity, particularly of gas transonic flows, i.e. the flows, containing both, subsonic and supersonic areas. The main issue, when styding such flows, are nonlinearity and combined type of equations, describing the transonic flow. Based on asymptotic nonlinear equation obtained in the article, the gas transonic flows is studied, considering transverse disturbance with respect to the main flow. The asymptotic conditions at shock-wave front and conditions on the streamlined surface are found. Moreover, the equation of sound surface and asymptotic formula defining the pressure are recorded. Several exact particular solutions of such equation are given, and their application to solve several tasks of transonic aerodynamics is indicated. Specifically, the polynomial form solution describing gas axisymmetric flows in Laval nozzles with constant acceleration in direction of the nozzle's axis and flow swirling is obtained. The solutions describing the unsteady flow along the channels between spinning surfaces are presented. The asymptotic equation is obtained, describing the flow, appearing during non-separated and separated flow past, closely approximated to cylindrical one. Specific solutions are given, based on which the examples of steady flow are formed.

Thermodynamic evaluation of transonic compressor rotors using the finite volume approach

NASA Technical Reports Server (NTRS)

Moore, J.; Nicholson, S.; Moore, J. G.

1985-01-01

Research at NASA Lewis Research Center gave the opportunity to incorporate new control volumes in the Denton 3-D finite-volume time marching code. For duct flows, the new control volumes require no transverse smoothing and this allows calculations with large transverse gradients in properties without significant numerical total pressure losses. Possibilities for improving the Denton code to obtain better distributions of properties through shocks were demonstrated. Much better total pressure distributions through shocks are obtained when the interpolated effective pressure, needed to stabilize the solution procedure, is used to calculate the total pressure. This simple change largely eliminates the undershoot in total pressure down-stream of a shock. Overshoots and undershoots in total pressure can then be further reduced by a factor of 10 by adopting the effective density method, rather than the effective pressure method. Use of a Mach number dependent interpolation scheme for pressure then removes the overshoot in static pressure downstream of a shock. The stability of interpolation schemes used for the calculation of effective density is analyzed and a Mach number dependent scheme is developed, combining the advantages of the correct perfect gas equation for subsonic flow with the stability of 2-point and 3-point interpolation schemes for supersonic flow.

Rapid growth of black holes accompanied with hot or warm outflows exposed to anisotropic super-Eddington radiation

NASA Astrophysics Data System (ADS)

Takeo, Eishun; Inayoshi, Kohei; Ohsuga, Ken; Takahashi, Hiroyuki R.; Mineshige, Shin

2018-05-01

We perform two-dimensional radiation hydrodynamical simulations of accretion flows on to a black hole (BH) with a mass of 103 ≤ MBH/ M⊙ ≲ 106 in order to study rapid growth of BHs in the early Universe. For spherically symmetric flows, hyper-Eddington accretion from outside the Bondi radius can occur unimpeded by radiation feedback when MBH ≳ 104 M⊙(n∞/105 cm - 3) - 1(T∞/104 K)3/2, where the density and temperature of ambient gas are initially set to n∞ = 105 cm-3 and T∞ = 104 K. Here, we study accretion flows exposed to anisotropic radiation from a nuclear accretion disc with a luminosity higher than the Eddington value (LEdd) due to collimation towards the bipolar directions. We find that, unlike the spherically symmetric case, even less massive BHs with MBH < 104 M⊙ can be fed at high accretion rates of ≳ LEdd/c2 through the equatorial region, while ionized regions expand towards the poles producing hot outflows with T ˜ 105 K. For more massive BHs with MBH ≳ 5 × 105 M⊙, intense inflows of neutral gas through the equator totally cover the central radiating region due to the non-radial gas motions. Because of efficient recombination by hydrogen, the entire flow settles in neutral and warm gas with T ≃ 8000 K. The BH is fed at a rate of ˜5 × 104LEdd/c2 (a half of the inflow rate from the Bondi radius). Moreover, radiation momentum absorbed by neutral hydrogen produces warm outflows towards the bipolar directions at ˜ 10 per cent of the BH feeding rate and with a velocity several times higher than the escaping value.

Effects of high source flow and high pumping speed on gas source molecular beam epitaxy / chemical beam epitaxy

NASA Astrophysics Data System (ADS)

McCollum, M. J.; Jackson, S. L.; Szafranek, I.; Stillman, G. E.

1990-10-01

We report the growth of GaAs by molecular beam epitaxy (MBE), gas source molecular beam epitaxy (GSMBE), and chemical beam epitaxy (CBE) in an epitaxial III-V reactor which features high pumping speed. The system is comprised of a modified Perkin-Elmer 430P molecular beam epitaxy system and a custom gas source panel from Emcore. The growth chamber is pumped with a 7000 1/s (He) diffusion pump (Varian VHS-10 with Monsanto Santovac 5 oil). The gas source panel includes pressure based flow controllers (MKS 1150) allowing triethylaluminum (TEA), triethylgallium (TEG), and trimethylindium (TMI) to be supplied without the use of hydrogen. All source lines, including arsine and phosphine, are maintained below atmospheric pressure. The high pumping speed allows total system flow rates as high as 100 SCCM and V/III ratios as high as 100. The purity of GaAs grown by MBE in this system increases with pumping speed. GaAs layers grown by GSMBE with arsine flows of 10 and 20 SCCM have electron concentrations of 1 × 10 15 cm -3 (μ 77=48,000 cm 2/V·) and 2 × 10 14 cm -3 (μ 77=78,000 cm 2/V·s) respectively. El ectron concentration varies with hydride injector temperature such that the minimum in electron concentration occurs for less than complete cracking. The effect of V/III ratio and the use of a metal eutectic bubbler on residual carrier concentration in GaAs grown by CBE is presented. Intentional Si and Be doping of CBE grown GaAs is demonstrated at a high growth rate of 5.4 μm/h.

Radiolytic Gas-Driven Cryovolcanism in the Outer Solar System

NASA Technical Reports Server (NTRS)

Cooper, John F.; Cooper, Paul D.; Sittler, Edward C.; Sturner, Steven J.; Rymer, Abigail M.; Hill, Matthew E.

2007-01-01

Water ices in surface crusts of Europa, Enceladus, Saturn's main rings, and Kuiper Belt Objects can become heavily oxidized from radiolytic chemical alteration of near-surface water ice by space environment irradiation. Oxidant accumulations and gas production are manifested in part through observed H2O2 on Europa. tentatively also on Enceladus, and found elsewhere in gaseous or condensed phases at moons and rings of Jupiter and Saturn. On subsequent chemical contact in sub-surface environments with significant concentrations of primordially abundant reductants such as NH3 and CH4, oxidants of radiolytic origin can react exothermically to power gas-driven cryovolcanism. The gas-piston effect enormously amplifies the mass flow output in the case of gas formation at basal thermal margins of incompressible fluid reservoirs. Surface irradiation, H2O2 production, NH3 oxidation, and resultant heat, gas, and gas-driven mass flow rates are computed in the fluid reservoir case for selected bodies. At Enceladus the oxidant power inputs are comparable to limits on nonthermal kinetic power for the south polar plumes. Total heat output and plume gas abundance may be accounted for at Enceladus if plume activity is cyclic in high and low "Old Faithful" phases, so that oxidants can accumulate during low activity phases. Interior upwelling of primordially abundant NH3 and CH4 hydrates is assumed to resupply the reductant fuels. Much lower irradiation fluxes on Kuiper Belt Objects require correspondingly larger times for accumulation of oxidants to produce comparable resurfacing, but brightness and surface composition of some objects suggest that such activity may be ongoing.

Physical vapor transport of mercurous chloride under a nonlinear thermal profile

NASA Technical Reports Server (NTRS)

Mennetrier, Christophe; Duval, Walter M. B.; Singh, Narsingh B.

1992-01-01

Our study investigates numerically the flow field characteristics during the growth of mercurous chloride (Hg2Cl2) crystals in a rectangular ampoule under terrestrial and microgravity conditions for a nonlinear thermal gradient. With a residual gas lighter than the nutrient, the solutal Grashof number is dominant. We observe that in tilted configurations, when solutal convection is dominant, the maximum transport rate occurs at approximately 40 percent. For the vertical configurations, we were able to obtain solutions only for the cases either below the critical Rayleigh numbers or the stabilized configurations. The total mass flux decreases exponentially with an increase of pressure of residual gas, but it increases following a power law with the temperature difference driving the transport. The nonlinear thermal gradient appears to destabilize the flow field when thermal convection is dominant for both vertical top-heated and bottom-heated configurations. However, when the solutal Grashof number is dominant, the density gradient resulting from the solutal gradient appears to stabilize the flow for the bottom-heated configuration. The flow field for the top-heated configuration is destabilized for high Grashof numbers. The microgravity environment provides a means for lowering convection. For gravity levels of 10(exp -3) g(0) or less, the Stefan wind drives the flow, and no recirculating cell is predicted.

UF6 Density and Mass Flow Measurements for Enrichment Plants using Acoustic Techniques

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

Good, Morris S.; Smith, Leon E.; Warren, Glen A.

A key enabling capability for enrichment plant safeguards being considered by the International Atomic Energy Agency (IAEA) is high-accuracy, noninvasive, unattended measurement of UF6 gas density and mass flow rate. Acoustic techniques are currently used to noninvasively monitor gas flow in industrial applications; however, the operating pressures at gaseous centrifuge enrichment plants (GCEPs) are roughly two orders magnitude below the capabilities of commercial instrumentation. Pacific Northwest National Laboratory is refining acoustic techniques for estimating density and mass flow rate of UF6 gas in scenarios typical of GCEPs, with the goal of achieving 1% measurement accuracy. Proof-of-concept laboratory measurements using amore » surrogate gas for UF6 have demonstrated signatures sensitive to gas density at low operating pressures such as 10–50 Torr, which were observed over the background acoustic interference. Current efforts involve developing a test bed for conducting acoustic measurements on flowing SF6 gas at representative flow rates and pressures to ascertain the viability of conducting gas flow measurements under these conditions. Density and flow measurements will be conducted to support the evaluation. If successful, the approach could enable an unattended, noninvasive approach to measure mass flow in unit header pipes of GCEPs.« less

Multi-fluid CFD analysis in Process Engineering

NASA Astrophysics Data System (ADS)

Hjertager, B. H.

2017-12-01

An overview of modelling and simulation of flow processes in gas/particle and gas/liquid systems are presented. Particular emphasis is given to computational fluid dynamics (CFD) models that use the multi-dimensional multi-fluid techniques. Turbulence modelling strategies for gas/particle flows based on the kinetic theory for granular flows are given. Sub models for the interfacial transfer processes and chemical kinetics modelling are presented. Examples are shown for some gas/particle systems including flow and chemical reaction in risers as well as gas/liquid systems including bubble columns and stirred tanks.

Low noise lead screw positioner

NASA Technical Reports Server (NTRS)

Perkins, Gerald S. (Inventor)

1986-01-01

A very precise and low noise lead screw positioner, for positioning a retroreflector in an interferometer is described. A gas source supplies inert pressurized gas, that flows through narrow holes into the clearance space between a nut and the lead screw. The pressurized gas keeps the nut out of contact with the screw. The gas flows axially along the clearance space, into the environment. The small amount of inert gas flowing into the environment minimizes pollution. By allowing such flow into the environment, no seals are required between the end of the nut and the screw.

Evaluation of hydrogen as a cryogenic wind tunnel test gas

NASA Technical Reports Server (NTRS)

Haut, R. C.

1977-01-01

The nondimensional ratios used to describe various flow situations in hydrogen were determined and compared with the corresponding ideal diatomic gas ratios. The results were used to examine different inviscid flow configurations. The relatively high value of the characteristic rotational temperature causes the behavior of hydrogen, under cryogenic conditions, to deviate substantially from the behavior of an ideal diatomic gas in the compressible flow regime. Therefore, if an idea diatomic gas is to be modeled, cryogenic hydrogen is unacceptable as a wind tunnel test gas in a compressible flow situation.

Modeling of flowing gas diode pumped alkali lasers: dependence of the operation on the gas velocity and on the nature of the buffer gas.

PubMed

Barmashenko, B D; Rosenwaks, S

2012-09-01

A simple, semi-analytical model of flowing gas diode pumped alkali lasers (DPALs) is presented. The model takes into account the rise of temperature in the lasing medium with increasing pump power, resulting in decreasing pump absorption and slope efficiency. The model predicts the dependence of power on the flow velocity in flowing gas DPALs and checks the effect of using a buffer gas with high molar heat capacity and large relaxation rate constant between the 2P3/2 and 2P1/2 fine-structure levels of the alkali atom. It is found that the power strongly increases with flow velocity and that by replacing, e.g., ethane by propane as a buffer gas the power may be further increased by up to 30%. Eight kilowatt is achievable for 20 kW pump at flow velocity of 20  m/s.

Gas Flow and Ion Transfer in Heated ESI Capillary Interfaces

NASA Astrophysics Data System (ADS)

Bernier, Laurent; Pinfold, Harry; Pauly, Matthias; Rauschenbach, Stephan; Reiss, Julius

2018-02-01

Transfer capillaries are the preferred means to transport ions, generated by electrospray ionization, from ambient conditions to vacuum. During the transfer of ions through the narrow, long tubes into vacuum, substantial losses are typical. However, recently it was demonstrated that these losses can be avoided altogether. To understand the experimental observation and provide a general model for the ion transport, here, we investigate the ion transport through capillaries by numerical simulation of interacting ions. The simulation encompasses all relevant factors, such as space charge, diffusion, gas flow, and heating. Special attention is paid to the influence of the gas flow on the transmission and especially the change imposed by heating. The gas flow is modeled by a one-dimensional gas dynamics description. A large number of ions are treated as point particles in this gas flow. This allows to investigate the influence of the capillary heating on the gas flow and by this on the ion transport. The results are compared with experimental findings. [Figure not available: see fulltext.

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

Khinkis, Mark J.; Kozlov, Aleksandr P.

A radiant, non-catalytic recuperative reformer has a flue gas flow path for conducting hot exhaust gas from a thermal process and a reforming mixture flow path for conducting a reforming mixture. At least a portion of the reforming mixture flow path is positioned adjacent to the flue gas flow path to permit heat transfer from the hot exhaust gas to the reforming mixture. The reforming mixture flow path contains substantially no material commonly used as a catalyst for reforming hydrocarbon fuel (e.g., nickel oxide, platinum group elements or rhenium), but instead the reforming mixture is reformed into a higher calorificmore » fuel via reactions due to the heat transfer and residence time. In a preferred embodiment, a portion of the reforming mixture flow path is positioned outside of flue gas flow path for a relatively large residence time.« less

Dynamic Measurement of Temperature, Velocity, and Density in Hot Jets Using Rayleigh Scattering

NASA Technical Reports Server (NTRS)

Mielke, Amy F.; Elam, Kristie A.

2008-01-01

A molecular Rayleigh scattering technique was utilized to measure time-resolved gas temperature, velocity, and density in unseeded gas flows at sampling rates up to 10 kHz. A high power continuous-wave (cw) laser beam was focused at a point in an air flow field and Rayleigh scattered light was collected and fiber-optically transmitted to a Fabry-Perot interferometer for spectral analysis. Photomultipler tubes operated in the photon counting mode allowed high frequency sampling of the total signal level and the circular interference pattern to provide time-resolved density, temperature, and velocity measurements. Mean and rms velocity and temperature, as well as power spectral density calculations, are presented for measurements in a hydrogen-combustor heated jet facility with a 50.8-mm diameter nozzle at the NASA Glenn Research Center (GRC). The Rayleigh measurements are compared with particle image velocimetry data and CFD predictions. This technique is aimed at aeronautics research related to identifying noise sources in free jets, as well as applications in supersonic and hypersonic flows where measurement of flow properties, including mass flux, is required in the presence of shocks and ionization occurrence.

Computational analysis of a multistage axial compressor

NASA Astrophysics Data System (ADS)

Mamidoju, Chaithanya

Turbomachines are used extensively in Aerospace, Power Generation, and Oil & Gas Industries. Efficiency of these machines is often an important factor and has led to the continuous effort to improve the design to achieve better efficiency. The axial flow compressor is a major component in a gas turbine with the turbine's overall performance depending strongly on compressor performance. Traditional analysis of axial compressors involves throughflow calculations, isolated blade passage analysis, Quasi-3D blade-to-blade analysis, single-stage (rotor-stator) analysis, and multi-stage analysis involving larger design cycles. In the current study, the detailed flow through a 15 stage axial compressor is analyzed using a 3-D Navier Stokes CFD solver in a parallel computing environment. Methodology is described for steady state (frozen rotor stator) analysis of one blade passage per component. Various effects such as mesh type and density, boundary conditions, tip clearance and numerical issues such as turbulence model choice, advection model choice, and parallel processing performance are analyzed. A high sensitivity of the predictions to the above was found. Physical explanation to the flow features observed in the computational study are given. The total pressure rise verses mass flow rate was computed.

Comparative study on aerodynamic heating under perfect and nonequilibrium hypersonic flows

NASA Astrophysics Data System (ADS)

Wang, Qiu; Li, JinPing; Zhao, Wei; Jiang, ZongLin

2016-02-01

In this study, comparative heat flux measurements for a sharp cone model were conducted by utilizing a high enthalpy shock tunnel JF-10 and a large-scale shock tunnel JF-12, responsible for providing nonequilibrium and perfect gas flows, respectively. Experiments were performed at the Key Laboratory of High Temperature Gas Dynamics (LHD), Institute of Mechanics, Chinese Academy of Sciences. Corresponding numerical simulations were also conducted in effort to better understand the phenomena accompanying in these experiments. By assessing the consistency and accuracy of all the data gathered during this study, a detailed comparison of sharp cone heat transfer under a totally different kind of freestream conditions was build and analyzed. One specific parameter, defined as the product of the Stanton number and the square root of the Reynold number, was found to be more characteristic for the aerodynamic heating phenomena encountered in hypersonic flight. Adequate use of said parameter practically eliminates the variability caused by the deferent flow conditions, regardless of whether the flow is in dissociation or the boundary condition is catalytic. Essentially, the parameter identified in this study reduces the amount of ground experimental data necessary and eases data extrapolation to flight.

40 CFR Appendix E to Part 52 - Performance Specifications and, Specification Test Procedures for Monitoring Systems for Effluent...

Code of Federal Regulations, 2011 CFR

2011-07-01

..., Specification Test Procedures for Monitoring Systems for Effluent Stream Gas Volumetric Flow Rate E Appendix E... Stream Gas Volumetric Flow Rate 1. Principle and applicability. 1.1Principle. Effluent stream gas... method is applicable to subparts which require continuous gas volumetric flow rate measurement...

40 CFR Appendix E to Part 52 - Performance Specifications and, Specification Test Procedures for Monitoring Systems for Effluent...

Code of Federal Regulations, 2010 CFR

2010-07-01

..., Specification Test Procedures for Monitoring Systems for Effluent Stream Gas Volumetric Flow Rate E Appendix E... Stream Gas Volumetric Flow Rate 1. Principle and applicability. 1.1Principle. Effluent stream gas... method is applicable to subparts which require continuous gas volumetric flow rate measurement...

An Experimental and Numerical Investigation of Endwall Aerodynamics and Heat Transfer in a Gas Turbine Nozzle Guide Vane with Slot Film Cooling

NASA Astrophysics Data System (ADS)

Alqefl, Mahmood Hasan

In many regions of the high-pressure gas turbine, film cooling flows are used to protect the turbine components from the combustor exit hot gases. Endwalls are challenging to cool because of the complex system of secondary flows that disturb surface film coolant coverage. The secondary flow vortices wash the film coolant from the surface into the mainstream significantly decreasing cooling effectiveness. In addition to being effected by secondary flow structures, film cooling flow can also affect these structures by virtue of their momentum exchange. In addition, many studies in the literature have shown that endwall contouring affects the strength of passage secondary flows. Therefore, to develop better endwall cooling schemes, a good understanding of passage aerodynamics and heat transfer as affected by interactions of film cooling flows with secondary flows is required. This experimental and computational study presents results from a linear, stationary, two-passage cascade representing the first stage nozzle guide vane of a high-pressure gas turbine with an axisymmetrically contoured endwall. The sources of film cooling flows are upstream combustor liner coolant and endwall slot film coolant injected immediately upstream of the cascade passage inlet. The operating conditions simulate combustor exit flow features, with a high Reynolds number of 390,000 and approach flow turbulence intensity of 11% with an integral length scale of 21% of the chord length. Measurements are performed with varying slot film cooling mass flow to mainstream flow rate ratios (MFR). Aerodynamic effects are documented with five-hole probe measurements at the exit plane. Heat transfer is documented through recovery temperature measurements with a thermocouple. General secondary flow features are observed. Total pressure loss measurements show that varying the slot film cooling MFR has some effects on passage loss. Velocity vectors and vorticity distributions show a very thin, yet intense, cross-pitch flow on the contoured endwall side. Endwall adiabatic effectiveness values and coolant distribution thermal fields show minimal effects of varying slot film coolant MFR. This suggests the dominant effects of combustor liner coolant. show dominant effects of combustor liner coolant on cooling the endwall. A coolant vorticity correlation presenting the advective mixing of the coolant due to secondary flow vorticity at the exit plane is also discussed.

Investigation of air stream from combustor-liner air entry holes, 3

NASA Technical Reports Server (NTRS)

Aiba, T.; Nakano, T.

1979-01-01

Jets flowing from air entry holes of the combustor liner of a gas turbine were investigated. Cold air was supplied through the air entry holes into the primary hot gas flows. The mass flow of the primary hot gas and issuing jets was measured, and the behavior of the air jets was studied by the measurement of the temperature distribution of the gas mixture. The air jets flowing from three circular air entry holes, single streamwise long holes, and two opposing circular holes, parallel to the primary flow were studied along with the effects of jet and gas stream velocities, and of gas temperature. The discharge coefficient, the maximum penetration of the jets, the jet flow path, the mixing of the jets, and temperature distribution across the jets were investigated. Empirical expressions which describe the characteristics of the jets under the conditions of the experiments were formulated.

Fuel cell plates with improved arrangement of process channels for enhanced pressure drop across the plates

DOEpatents

Spurrier, Francis R.; Pierce, Bill L.; Wright, Maynard K.

1986-01-01

A plate for a fuel cell has an arrangement of ribs defining an improved configuration of process gas channels and slots on a surface of the plate which provide a modified serpentine gas flow pattern across the plate surface. The channels are generally linear and arranged parallel to one another while the spaced slots allow cross channel flow of process gas in a staggered fashion which creates a plurality of generally mini-serpentine flow paths extending transverse to the longitudinal gas flow along the channels. Adjacent pairs of the channels are interconnected to one another in flow communication. Also, a bipolar plate has the aforementioned process gas channel configuration on one surface and another configuration on the opposite surface. In the other configuration, there are not slots and the gas flow channels have a generally serpentine configuration.

Arc Jet Flow Properties Determined from Laser-Induced Fluorescence of Atomic Nitrogen

NASA Technical Reports Server (NTRS)

Fletcher, Douglas; Wercinski, Paul F. (Technical Monitor)

1998-01-01

An laser-spectroscopic investigation of the thermocheMical state of arcjet flows is currently being conducted in the Aerodynamic Heating Facility (AHF) Circlet at NASA Ames Research Center. Downstream of the nozzle exit, but upstream of the test article, Laser-Induced Fluorescence (LIF) of atomic nitrogen is used to assess the nonequilibriuM distribution of flow enthalpy in the free stream. The two-photon LIF technique provides simultaneous measurements of free stream velocity, translational temperature, and nitrogen number density on the flow centerline. Along with information from facility instrumentation, these measurements allow a determination of the free stream total enthalpy, and its apportionment in to thermal, kinetic, and chemical mode contributions. Experimental results are presented and discussed for two different niti-ogen/argon test gas flow runs during which the current is varied while the pressure remains constant .

Compressible Flow Phenomena at Inception of Lateral Density Currents Fed by Collapsing Gas-Particle Mixtures

NASA Astrophysics Data System (ADS)

Valentine, Greg A.; Sweeney, Matthew R.

2018-02-01

Many geological flows are sourced by falling gas-particle mixtures, such as during collapse of lava domes, and impulsive eruptive jets, and sustained columns, and rock falls. The transition from vertical to lateral flow is complex due to the range of coupling between particles of different sizes and densities and the carrier gas, and due to the potential for compressible flow phenomena. We use multiphase modeling to explore these dynamics. In mixtures with small particles, and with subsonic speeds, particles follow the gas such that outgoing lateral flows have similar particle concentration and speed as the vertical flows. Large particles concentrate immediately upon impact and move laterally away as granular flows overridden by a high-speed jet of expelled gas. When a falling flow is supersonic, a bow shock develops above the impact zone, and this produces a zone of high pressure from which lateral flows emerge as overpressured wall jets. The jets form complex structures as the mixtures expand and accelerate and then recompress through a recompression zone that mimics a Mach disk shock in ideal gas jets. In mixtures with moderate to high ratios of fine to coarse particles, the latter tend to follow fine particles through the expansion-recompression flow fields because of particle-particle drag. Expansion within the flow fields can lead to locally reduced gas pressure that could enhance substrate erosion in natural flows. The recompression zones form at distances, and have peak pressures, that are roughly proportional to the Mach numbers of impacting flows.

PIV Measurements of Gas Flow Fields from Burning End

NASA Astrophysics Data System (ADS)

Huang, Yifei; Wu, Junzhang; Zeng, Jingsong; Tang, Darong; Du, Liang

2017-12-01

To study the influence of cigarette gas on the environment, it is necessary to know the cigarette gas flow fields from burning end. By using PIV technique, in order to reveal velocity characteristics of gas flow fields, the velocities of cigarette gas flow fields was analyzed with different stepping motor frequencies corresponding to suction pressures, and the trend of velocity has been given with image fitting. The results shows that the velocities of the burning end increased with suction pressures; Between velocities of the burning end and suction pressures, the relations present polynomial rule; The cigarette gas diffusion in combustion process is faster than in the smoldering process.

Gas flow means for improving efficiency of exhaust hoods

DOEpatents

Gadgil, Ashok J.

1994-01-01

Apparatus for inhibiting the flow of contaminants in an exhaust enclosure toward an individual located adjacent an opening into the exhaust enclosure by providing a gas flow toward a source of contaminants from a position in front of an individual to urge said contaminants away from the individual toward a gas exit port. The apparatus comprises a gas mani-fold which may be worn by a person as a vest. The manifold has a series of gas outlets on a front face thereof facing away from the individual and toward the contaminants to thereby provide a flow of gas from the front of the individual toward the contaminants.

Heat Transfer to Anode of Arc as Function of Transverse Magnetic Field and Lateral Gas Flow Velocity

NASA Astrophysics Data System (ADS)

Zama, Yoshiyuki; Shiino, Toru; Ishii, Yoko; Maeda, Yoshifumi; Yamamoto, Shinji; Iwao, Toru

2016-10-01

Gas tungsten arc welding has useful joining technology because of high-energy and high-current characteristics. It can be flexible from the transverse magnetic field and lateral gas flow velocity. In this case, the weld defect occurs. In this research, the heat transfer to the anode of the arc as a function of the transverse magnetic field and lateral gas flow velocity is elucidated. That magnetic flux density and lateral gas velocity were varied from 0 to 3 mT and 0 to 50?m?s -1, respectively. The axial plasma gas argon flow rates were 3?slm. A transverse magnetic field is applied to the arc using Helmholtz coil. The anode is used by a water-cooled copper plate, and the heat transfer is measured by temperature of cooled water. As a result, the arc is deflected by the Lorentz force and lateral gas convection. Thus, the heat transfer to the anode of the arc decreases with increasing the transverse magnetic field and lateral gas flow velocity. In addition, the heat transfer to the anode changes with different attachments modes. The lateral gas flow causes a convective heat loss from the arc to the chamber walls.

Contribution of Methane Accumulation and Pore Water Flow to Forming High Concentration of Gas Hydrate in Sandy Sediments

NASA Astrophysics Data System (ADS)

Uchida, T.; Waseda, A.; Fujii, T.

2006-12-01

The geological and geophysical evaluations have suggested worldwide methane contents in gas hydrate beneath deep sea floors as well as permafrost-related zones to about twice the total reserves of conventional and unconventional hydrocarbon. In 1998 and 2002 Mallik wells were drilled in the Canadian Arctic that clarified the characteristics of gas hydrate-concentrated sandy layers at depths from 890 to 1110 m beneath the permafrost zone. Continuous downhole well log data, anomalies of chloride contents in pore waters, core temperature depression as well as visible gas hydrates have confirmed the highly saturated pore-space hydrate as intergranular pore filling, whose saturations are evaluated higher than 80 percent in pore volume. In the Nankai Trough forearc basins and accretionary prisms developed and BSRs (bottom simulating reflectors) have been recognized widely, where the multiple wells were drilled in 2000 and 2004, and revealed the presence of pore-space hydrate in sandy layers. It is remarked that there are many similar features in appearance and characteristics between the Mallik and Nankai Trough areas with observations of well- interconnected and highly saturated pore-space hydrate. High concentration of gas hydrate may need original pore space large enough to occur within a host sandy sediment, and this appears to be a similar mode for conventional petroleum accumulations. The distribution of a porous and coarser-grained sandy sediments should be one of the most important factors controlling occurrences and distributions of gas hydrate, as well as physicochemical conditions. Supplying methane for forming deep marine gas hydrate is commonly attributed to microbial conversion of organic material within the zone of stability or to migration of methane-containing fluids from a deeper source area. Pore water flows are considered to a macroscopic migration through faults/fractures and a microscopic flow in intergranular pore systems of sediment. We should assess the influence of methane supply on observable features of hydrate occurrences.

Bubble composition of natural gas seeps discovered along the Cascadia Continental Margin

NASA Astrophysics Data System (ADS)

Baumberger, T.; Merle, S. G.; Embley, R. W.; Seabrook, S.; Raineault, N.; Lilley, M. D.; Evans, L. J.; Walker, S. L.; Lupton, J. E.

2016-12-01

Gas hydrates and gas-filled pockets present in sedimentary deposits have been recognized as large reservoirs for reduced carbon in the Earth's crust. This is particularly relevant in geological settings with high carbon input, such as continental margins. During expedition NA072 on the E/V Nautilus (operated by the Ocean Exploration Trust Inc.) in June 2016, the U.S. Cascadia Continental Margin (Washington, Oregon and northern California) was explored for gas seepage from sediments. During this expedition, over 400 bubble plumes at water depths ranging from 125 and 1640 m were newly discovered, and five of them were sampled for gas bubble composition using specially designed gas tight fluid samplers mounted on the Hercules remotely operated vehicle (ROV). These gas bubble samples were collected at four different depths, 494 m (rim of Astoria Canyon), 615 and 620 m (SW Coquille Bank), 849 m (floor of Astoria Canyon) and 1227 m (Heceta SW). At the two deeper sites, exposed hydrate was present in the same area where bubbles were seeping out from the seafloor. Other than the escaping gas bubbles, no other fluid flow was visible. However, the presence of bacterial mats point to diffuse fluid flow present in the affected area. In this study we present the results of the currently ongoing geochemical analysis of the gas bubbles released at the different sites and depths. Noble gas analysis, namely helium and neon, will give information about the source of the helium as well as about potential fractionation between helium and neon associated with gas hydrates. The characterization of these gas samples will also include total gas (CO2, H2, N2, O2, Ar, CH4 and other hydrocarbons) and stable isotope analysis (C and H). This dataset will reveal the chemical composition of the seeping bubbles as well as give information about the possible sources of the carbon contained in the seeping gas.

40 CFR 98.443 - Calculating CO2 geologic sequestration.

Code of Federal Regulations, 2011 CFR

2011-07-01

... each gas-liquid separator for which flow is measured using a mass flow meter, you must calculate...) For each gas-liquid separator for which flow is measured using a volumetric flow meter, you must...) To aggregate production data, you must sum the mass of all of the CO2 separated at each gas-liquid...

Percolation connectivity, pore size, and gas apparent permeability: Network simulations and comparison to experimental data

NASA Astrophysics Data System (ADS)

Li, M.; Tang, Y. B.; Bernabé, Y.; Zhao, J. Z.; Li, X. F.; Li, T.

2017-07-01

We modeled single-phase gas flow through porous media using percolation networks. Gas permeability is different from liquid permeability. The latter is only related to the geometry and topology of the pore space, while the former depends on the specific gas considered and varies with gas pressure. As gas pressure decreases, four flow regimes can be distinguished as viscous flow, slip flow, transition flow, and free molecular diffusion. Here we use a published conductance model presumably capable of predicting the flow rate of an arbitrary gas through a cylindrical pipe in the four regimes. We incorporated this model into pipe network simulations. We considered 3-D simple cubic, body-centered cubic, and face-centered cubic lattices, in which we varied the pipe radius distribution and the bond coordination number. Gas flow was simulated at different gas pressures. The simulation results showed that the gas apparent permeability kapp obeys an identical scaling law in all three lattices, kapp (z-zc)β, where the exponent β depends on the width of the pipe radius distribution, z is the mean coordination number, and zc its critical value at the percolation threshold. Surprisingly, (z-zc) had a very weak effect on the ratio of the apparent gas permeability to the absolute liquid permeability, kapp/kabs, suggesting that the Klinkenberg gas slippage correction factor is nearly independent of connectivity. We constructed models of kapp and kapp/kabs based on the observed power law and tested them by comparison with published experimental data on glass beads and other materials.

Apparatus for focusing flowing gas streams

DOEpatents

Nogar, N.S.; Keller, R.A.

1985-05-20

Apparatus for focusing gas streams. The principle of hydrodynamic focusing is applied to flowing gas streams in order to provide sample concentration for improved photon and sample utilization in resonance ionization mass spectrometric analysis. In a concentric nozzle system, gas samples introduced from the inner nozzle into the converging section of the outer nozzle are focused to streams 50-250-..mu..m in diameter. In some cases diameters of approximately 100-..mu..m are maintained over distances of several centimeters downstream from the exit orifice of the outer nozzle. The sheath gas employed has been observed to further provide a protective covering around the flowing gas sample, thereby isolating the flowing gas sample from possible unwanted reactions with nearby surfaces. A single nozzle variation of the apparatus for achieving hydrodynamic focusing of gas samples is also described.

TURBINE COOLING FLOW AND THE RESULTING DECREASE IN TURBINE EFFICIENCY

NASA Technical Reports Server (NTRS)

Gauntner, J. W.

1994-01-01

This algorithm has been developed for calculating both the quantity of compressor bleed flow required to cool a turbine and the resulting decrease in efficiency due to cooling air injected into the gas stream. Because of the trend toward higher turbine inlet temperatures, it is important to accurately predict the required cooling flow. This program is intended for use with axial flow, air-breathing jet propulsion engines with a variety of airfoil cooling configurations. The algorithm results have compared extremely well with figures given by major engine manufacturers for given bulk metal temperatures and cooling configurations. The program calculates the required cooling flow and corresponding decrease in stage efficiency for each row of airfoils throughout the turbine. These values are combined with the thermodynamic efficiency of the uncooled turbine to predict the total bleed airflow required and the altered turbine efficiency. There are ten airfoil cooling configurations and the algorithm allows a different option for each row of cooled airfoils. Materials technology is incorporated and requires the date of the first year of service for the turbine stator vane and rotor blade. The user must specify pressure, temperatures, and gas flows into the turbine. This program is written in FORTRAN IV for batch execution and has been implemented on an IBM 3080 series computer with a central memory requirement of approximately 61K of 8 bit bytes. This program was developed in 1980.

Simultaneous film and convection cooling of a plate inserted in the exhaust stream of a gas turbine combustor

NASA Technical Reports Server (NTRS)

Marek, C. J.; Juhasz, A. J.

1973-01-01

Data were obtained on a parallel-flow film- and convection-cooled test section placed in the exhaust stream of a rectangular-sector combustor. The combustor was operated at atmospheric pressure and at exhaust temperatures of 589 and 1033 K (600 and 1400 F). The cooling air was at ambient pressure and temperature. Test results indicate that it is better to use combined film and convection cooling rather than either film or convection cooling alone for a fixed total coolant flow. An optimum ratio of film to convection cooling flow rates was determined for the particular geometry tested. The experimental results compared well with calculated results.

Analysis of Developing Gas/liquid Two-Phase Flows

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

Elena A. Tselishcheva; Michael Z. Podowski; Steven P. Antal

The goal of this work is to develop a mechanistically based CFD model that can be used to simulate process equipment operating in the churn-turbulent regime. The simulations were performed using a state-of-the-art computational multiphase fluid dynamics code, NPHASE–CMFD [Antal et al,2000]. A complete four-field model, including the continuous liquid field and three dispersed gas fields representing bubbles of different sizes, was first carefully tested for numerical convergence and accuracy, and then used to reproduce the experimental results from the TOPFLOW test facility at Forschungszentrum Dresden-Rossendorf e.V. Institute of Safety Research [Prasser et al,2007]. Good progress has been made inmore » simulating the churn-turbulent flows and comparison the NPHASE-CMFD simulations with TOPFLOW experimental data. The main objective of the paper is to demonstrate capability to predict the evolution of adiabatic churn-turbulent gas/liquid flows. The proposed modelling concept uses transport equations for the continuous liquid field and for dispersed bubble fields [Tselishcheva et al, 2009]. Along with closure laws based on interaction between bubbles and continuous liquid, the effect of height on air density has been included in the model. The figure below presents the developing flow results of the study, namely total void fraction at different axial locations along the TOPFLOW facility test section. The complete model description, as well as results of simulations and validation will be presented in the full paper.« less

Use of schlieren methods to study gas flow in laser technology

NASA Astrophysics Data System (ADS)

Mrňa, Libor; Pavelka, Jan; Horník, Petr; Hrabovský, Jozef

2016-11-01

Laser technologies such as welding and cutting rely on process gases. We suggest to use schlieren imaging to visualize the gas flow during these processes. During the process of laser welding, the shielding gas flows to the welded area to prevent oxidation of the weld pool by surrounding air. The gas also interacts with hot plasma spurting from the key hole induced by the laser beam incident on the molten material. This interaction is quite complicated because hot plasma mixes with the cold shielding gas while the system is moving along the weld. Three shielding gases were used in the presented experiment: Ar, He and N2. Differences in dynamics of the flow are clearly visible on schlieren images. Moreover, high speed recording reveals a structure consisting of hot gas bubbles. We were also able to determine the velocity of the bubbles from the recording. During laser cutting, the process gas flows coaxially with the laser beam from the nozzle to remove the molten material out of the kerf. The gas flow is critical for the quality of the resulting edge of the cut. Schlieren method was used to study gas flow under the nozzle and then under the material being cut. This actually creates another slot nozzle. Due to the very low speed of flow below the material the schleiren method is already at the limit of its sensitivity. Therefore, it is necessary to apply a differential technique to increase the contrast. Distinctive widening of the flow shaped by the kerf was observed.

X-ray fluorescence measurements of dissolved gas and cavitation

DOE PAGES

Duke, Daniel J.; Kastengren, Alan L.; Swantek, Andrew B.; ...

2016-09-28

The dynamics of dissolved gas and cavitation are strongly coupled, yet these phenomena are difficult to measure in-situ. Both create voids in the fluid that can be difficult to distinguish. In this paper, we present an application of X-ray fluorescence in which liquid density and total noncondensible gas concentration (both dissolved and nucleated) are simultaneously measured. The liquid phase is doped with 400 ppm of a bromine tracer, and dissolved air is removed and substituted with krypton. Fluorescent emission at X-ray wavelengths is simultaneously excited from the Br and Kr with a focused monochromatic X-ray beam from a synchrotron source.more » We measure the flow in a cavitating nozzle 0.5 mm in diameter. From Br fluorescence, total displacement of the liquid is measured. From Kr fluorescence, the mass fraction of both dissolved and nucleated gas is measured. Volumetric displacement of liquid due to both cavitation and gas precipitation can be separated through estimation of the local equilibrium dissolved mass fraction. The uncertainty in the line of sight projected densities of the liquid and gas phases is 4–6 %. The high fluorescence yields and energies of Br and Kr allow small mass fractions of gas to be measured, down to 10 -5, with an uncertainty of 8 %. Finally, these quantitative measurements complement existing optical diagnostic techniques and provide new insight into the diffusion of gas into cavitation bubbles, which can increase their internal density, pressure and lifetimes by orders of magnitude.« less

Klinkenberg effect in hydrodynamics of gas flow through anisotropic porous materials

NASA Astrophysics Data System (ADS)

Wałowski, Grzegorz; Filipczak, Gabriel

2017-10-01

This study discusses results of experiments on hydrodynamic assessment of gas flow through backbone (skeletal) porous materials with an anisotropic structure. The research was conducted upon materials of diversified petrographic characteristics, both natural origin (rocky, pumice) and process materials (char and coke). The study was conducted for a variety of hydrodynamic conditions, using air, as well as for nitrogen and carbon dioxide. The basis for assessing hydrodynamics of gas flow through porous material was a gas stream that results from the pressure forcing such flow. The results of measurements indicate a clear impact of the type of material on the gas permeability, and additionally - as a result of their anisotropic internal structure - to a significant effect of the flow direction on the value of gas stream.

Quantitative comparison between crowd models for evacuation planning and evaluation

NASA Astrophysics Data System (ADS)

Viswanathan, Vaisagh; Lee, Chong Eu; Lees, Michael Harold; Cheong, Siew Ann; Sloot, Peter M. A.

2014-02-01

Crowd simulation is rapidly becoming a standard tool for evacuation planning and evaluation. However, the many crowd models in the literature are structurally different, and few have been rigorously calibrated against real-world egress data, especially in emergency situations. In this paper we describe a procedure to quantitatively compare different crowd models or between models and real-world data. We simulated three models: (1) the lattice gas model, (2) the social force model, and (3) the RVO2 model, and obtained the distributions of six observables: (1) evacuation time, (2) zoned evacuation time, (3) passage density, (4) total distance traveled, (5) inconvenience, and (6) flow rate. We then used the DISTATIS procedure to compute the compromise matrix of statistical distances between the three models. Projecting the three models onto the first two principal components of the compromise matrix, we find the lattice gas and RVO2 models are similar in terms of the evacuation time, passage density, and flow rates, whereas the social force and RVO2 models are similar in terms of the total distance traveled. Most importantly, we find that the zoned evacuation times of the three models to be very different from each other. Thus we propose to use this variable, if it can be measured, as the key test between different models, and also between models and the real world. Finally, we compared the model flow rates against the flow rate of an emergency evacuation during the May 2008 Sichuan earthquake, and found the social force model agrees best with this real data.

Spark gap switch with spiral gas flow

DOEpatents

Brucker, John P.

1989-01-01

A spark gap switch having a contaminate removal system using an injected gas. An annular plate concentric with an electrode of the switch defines flow paths for the injected gas which form a strong spiral flow of the gas in the housing which is effective to remove contaminates from the switch surfaces. The gas along with the contaminates is exhausted from the housing through one of the ends of the switch.

Treating landfill gas hydrogen sulphide with mineral wool waste (MWW) and rod mill waste (RMW).

PubMed

Bergersen, Ove; Haarstad, Ketil

2014-01-01

Hydrogen sulphide (H2S) gas is a major odorant at municipal landfills. The gas can be generated from different waste fractions, for example demolition waste containing gypsum based plaster board. The removal of H2S from landfill gas was investigated by filtering it through mineral wool waste products. The flow of gas varied from 0.3 l/min to 3.0 l/min. The gas was typical for landfill gas with a mean H2S concentration of ca. 4500 ppm. The results show that the sulphide gas can effectively be removed by mineral wool waste products. The ratios of the estimated potential for sulphide precipitation were 19:1 for rod mill waste (RMW) and mineral wool waste (MWW). A filter consisting of a mixture of MWW and RMW, with a vertical perforated gas tube through the center of filter material and with a downward gas flow, removed 98% of the sulfide gas over a period of 80 days. A downward gas flow was more efficient in contacting the filter materials. Mineral wool waste products are effective in removing hydrogen sulphide from landfill gas given an adequate contact time and water content in the filter material. Based on the estimated sulphide removal potential of mineral wool and rod mill waste of 14 g/kg and 261 g/kg, and assuming an average sulphide gas concentration of 4500 ppm, the removal capacity in the filter materials has been estimated to last between 11 and 308 days. At the studied location the experimental gas flow was 100 times less than the actual gas flow. We believe that the system described here can be upscaled in order to treat this gas flow. Copyright © 2013 Elsevier Ltd. All rights reserved.

Optimization of contoured hypersonic scramjet inlets with a least-squares parabolized Navier-Stokes procedure

NASA Technical Reports Server (NTRS)

Korte, J. J.; Auslender, A. H.

1993-01-01

A new optimization procedure, in which a parabolized Navier-Stokes solver is coupled with a non-linear least-squares optimization algorithm, is applied to the design of a Mach 14, laminar two-dimensional hypersonic subscale flight inlet with an internal contraction ratio of 15:1 and a length-to-throat half-height ratio of 150:1. An automated numerical search of multiple geometric wall contours, which are defined by polynomical splines, results in an optimal geometry that yields the maximum total-pressure recovery for the compression process. Optimal inlet geometry is obtained for both inviscid and viscous flows, with the assumption that the gas is either calorically or thermally perfect. The analysis with a calorically perfect gas results in an optimized inviscid inlet design that is defined by two cubic splines and yields a mass-weighted total-pressure recovery of 0.787, which is a 23% improvement compared with the optimized shock-canceled two-ramp inlet design. Similarly, the design procedure obtains the optimized contour for a viscous calorically perfect gas to yield a mass-weighted total-pressure recovery value of 0.749. Additionally, an optimized contour for a viscous thermally perfect gas is obtained to yield a mass-weighted total-pressure recovery value of 0.768. The design methodology incorporates both complex fluid dynamic physics and optimal search techniques without an excessive compromise of computational speed; hence, this methodology is a practical technique that is applicable to optimal inlet design procedures.

Mathematical Modeling of Dual Layer Shell Type Recuperation System for Biogas Dehumidification

NASA Astrophysics Data System (ADS)

Gendelis, S.; Timuhins, A.; Laizans, A.; Bandeniece, L.

2015-12-01

The main aim of the current paper is to create a mathematical model for dual layer shell type recuperation system, which allows reducing the heat losses from the biomass digester and water amount in the biogas without any additional mechanical or chemical components. The idea of this system is to reduce the temperature of the outflowing gas by creating two-layered counter-flow heat exchanger around the walls of biogas digester, thus increasing a thermal resistance and the gas temperature, resulting in a condensation on a colder surface. Complex mathematical model, including surface condensation, is developed for this type of biogas dehumidifier and the parameter study is carried out for a wide range of parameters. The model is reduced to 1D case to make numerical calculations faster. It is shown that latent heat of condensation is very important for the total heat balance and the condensation rate is highly dependent on insulation between layers and outside temperature. Modelling results allow finding optimal geometrical parameters for the known gas flow and predicting the condensation rate for different system setups and seasons.

An advanced kinetic theory for morphing continuum with inner structures

NASA Astrophysics Data System (ADS)

Chen, James

2017-12-01

Advanced kinetic theory with the Boltzmann-Curtiss equation provides a promising tool for polyatomic gas flows, especially for fluid flows containing inner structures, such as turbulence, polyatomic gas flows and others. Although a Hamiltonian-based distribution function was proposed for diatomic gas flow, a general distribution function for the generalized Boltzmann-Curtiss equations and polyatomic gas flow is still out of reach. With assistance from Boltzmann's entropy principle, a generalized Boltzmann-Curtiss distribution for polyatomic gas flow is introduced. The corresponding governing equations at equilibrium state are derived and compared with Eringen's morphing (micropolar) continuum theory derived under the framework of rational continuum thermomechanics. Although rational continuum thermomechanics has the advantages of mathematical rigor and simplicity, the presented statistical kinetic theory approach provides a clear physical picture for what the governing equations represent.

Comparison of Gas Displacement based on Thermometry in the Pulse Tube with Rayleigh Scattering

NASA Astrophysics Data System (ADS)

Hagiwara, Yasumasa; Nara, Kenichi; Ito, Seitoku; Saito, Takamoto

A pulse tube refrigerator has high reliability because of its simple structure. Recently the level of development activity of the pulse tube refrigerator has increased, but the quantitative understanding of the refrigeration mechanism has not fully been obtained. Therefore various explanations were proposed. The concept of virtual gas piston in particular helps us to understand the function of a phase shifter such as a buffer tank and an orifice because the virtual gas piston corresponds to a piston of a Stirling refrigerator. However it is difficult to directly measure the averaged gas displacement which corresponds to the virtual gas piston because uniform gas flow such as a gas piston does not always exist. For example, there are a jet flow from orifice and circulated flows in a pulse tube, which are predicted theoretically. In spite of these phenomena, the averaged gas displacement is very important in practical use because it can simply predict the performance from the displacement. In this report, we calculate the averaged gas displacement and mass flow through an orifice. The mass flow is calculated from the pressure change in a buffer tank. The averaged gas displacement is calculated from temperature profiles in the pulse tube and the mass flow. It is necessary to measure temperature in the pulse tube as widely as possible in order to calculate the averaged gas displacement. We apply a method using the Rayleigh Scattering the thermometry in the pulse tube. With this method, it is possible to perform 2-dimensional measurement without disturbing the gas flow. By this method, the averaged gas displacements and the temperature profiles of basic and orifice types of refrigeration were compared.

Non-invasive classification of gas-liquid two-phase horizontal flow regimes using an ultrasonic Doppler sensor and a neural network

NASA Astrophysics Data System (ADS)

Musa Abbagoni, Baba; Yeung, Hoi

2016-08-01

The identification of flow pattern is a key issue in multiphase flow which is encountered in the petrochemical industry. It is difficult to identify the gas-liquid flow regimes objectively with the gas-liquid two-phase flow. This paper presents the feasibility of a clamp-on instrument for an objective flow regime classification of two-phase flow using an ultrasonic Doppler sensor and an artificial neural network, which records and processes the ultrasonic signals reflected from the two-phase flow. Experimental data is obtained on a horizontal test rig with a total pipe length of 21 m and 5.08 cm internal diameter carrying air-water two-phase flow under slug, elongated bubble, stratified-wavy and, stratified flow regimes. Multilayer perceptron neural networks (MLPNNs) are used to develop the classification model. The classifier requires features as an input which is representative of the signals. Ultrasound signal features are extracted by applying both power spectral density (PSD) and discrete wavelet transform (DWT) methods to the flow signals. A classification scheme of ‘1-of-C coding method for classification’ was adopted to classify features extracted into one of four flow regime categories. To improve the performance of the flow regime classifier network, a second level neural network was incorporated by using the output of a first level networks feature as an input feature. The addition of the two network models provided a combined neural network model which has achieved a higher accuracy than single neural network models. Classification accuracies are evaluated in the form of both the PSD and DWT features. The success rates of the two models are: (1) using PSD features, the classifier missed 3 datasets out of 24 test datasets of the classification and scored 87.5% accuracy; (2) with the DWT features, the network misclassified only one data point and it was able to classify the flow patterns up to 95.8% accuracy. This approach has demonstrated the success of a clamp-on ultrasound sensor for flow regime classification that would be possible in industry practice. It is considerably more promising than other techniques as it uses a non-invasive and non-radioactive sensor.

Monitoring the evolution and migration of a methane gas plume in an unconfined sandy aquifer using time-lapse GPR and ERT.

PubMed

Steelman, Colby M; Klazinga, Dylan R; Cahill, Aaron G; Endres, Anthony L; Parker, Beth L

2017-10-01

Fugitive methane (CH 4 ) leakage associated with conventional and unconventional petroleum development (e.g., shale gas) may pose significant risks to shallow groundwater. While the potential threat of stray (CH 4 ) gas in aquifers has been acknowledged, few studies have examined the nature of its migration and fate in a shallow groundwater flow system. This study examines the geophysical responses observed from surface during a 72day field-scale simulated CH 4 leak in an unconfined sandy aquifer at Canadian Forces Base Borden, Canada, to better understand the transient behaviour of fugitive CH 4 gas in the subsurface. Time-lapse ground-penetrating radar (GPR) and electrical resistivity tomography (ERT) were used to monitor the distribution and migration of the gas-phase and assess any impacts to groundwater hydrochemistry. Geophysical measurements captured the transient formation of a CH 4 gas plume emanating from the injector, which was accompanied by an increase in total dissolved gas pressure (P TDG ). Subsequent reductions in P TDG were accompanied by reduced bulk resistivity around the injector along with an increase in the GPR reflectivity along horizontal bedding reflectors farther downgradient. Repeat temporal GPR reflection profiling identified three events with major peaks in reflectivity, interpreted to represent episodic lateral CH 4 gas release events into the aquifer. Here, a gradual increase in P TDG near the injector caused a sudden lateral breakthrough of gas in the direction of groundwater flow, causing free-phase CH 4 to migrate much farther than anticipated based on groundwater advection. CH 4 accumulated along subtle permeability boundaries demarcated by grain-scale bedding within the aquifer characteristic of numerous Borden-aquifer multi-phase flow experiments. Diminishing reflectivity over a period of days to weeks suggests buoyancy-driven migration to the vadose zone and/or CH 4 dissolution into groundwater. Lateral and vertical CH 4 migration was primarily governed by subtle, yet measurable heterogeneity and anisotropy in the aquifer. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Determination of respiratory gas flow by electrical impedance tomography in an animal model of mechanical ventilation

PubMed Central

2014-01-01

Background A recent method determines regional gas flow of the lung by electrical impedance tomography (EIT). The aim of this study is to show the applicability of this method in a porcine model of mechanical ventilation in healthy and diseased lungs. Our primary hypothesis is that global gas flow measured by EIT can be correlated with spirometry. Our secondary hypothesis is that regional analysis of respiratory gas flow delivers physiologically meaningful results. Methods In two sets of experiments n = 7 healthy pigs and n = 6 pigs before and after induction of lavage lung injury were investigated. EIT of the lung and spirometry were registered synchronously during ongoing mechanical ventilation. In-vivo aeration of the lung was analysed in four regions-of-interest (ROI) by EIT: 1) global, 2) ventral (non-dependent), 3) middle and 4) dorsal (dependent) ROI. Respiratory gas flow was calculated by the first derivative of the regional aeration curve. Four phases of the respiratory cycle were discriminated. They delivered peak and late inspiratory and expiratory gas flow (PIF, LIF, PEF, LEF) characterizing early or late inspiration or expiration. Results Linear regression analysis of EIT and spirometry in healthy pigs revealed a very good correlation measuring peak flow and a good correlation detecting late flow. PIFEIT = 0.702 · PIFspiro + 117.4, r2 = 0.809; PEFEIT = 0.690 · PEFspiro-124.2, r2 = 0.760; LIFEIT = 0.909 · LIFspiro + 27.32, r2 = 0.572 and LEFEIT = 0.858 · LEFspiro-10.94, r2 = 0.647. EIT derived absolute gas flow was generally smaller than data from spirometry. Regional gas flow was distributed heterogeneously during different phases of the respiratory cycle. But, the regional distribution of gas flow stayed stable during different ventilator settings. Moderate lung injury changed the regional pattern of gas flow. Conclusions We conclude that the presented method is able to determine global respiratory gas flow of the lung in different phases of the respiratory cycle. Additionally, it delivers meaningful insight into regional pulmonary characteristics, i.e. the regional ability of the lung to take up and to release air. PMID:24779960

Poiseuille, thermal transpiration and Couette flows of a rarefied gas between plane parallel walls with nonuniform surface properties in the transverse direction and their reciprocity relations

NASA Astrophysics Data System (ADS)

Doi, Toshiyuki

2018-04-01

Slow flows of a rarefied gas between two plane parallel walls with nonuniform surface properties are studied based on kinetic theory. It is assumed that one wall is a diffuse reflection boundary and the other wall is a Maxwell-type boundary whose accommodation coefficient varies periodically in the direction perpendicular to the flow. The time-independent Poiseuille, thermal transpiration and Couette flows are considered. The flow behavior is numerically studied based on the linearized Bhatnagar-Gross-Krook-Welander model of the Boltzmann equation. The flow field, the mass and heat flow rates in the gas, and the tangential force acting on the wall surface are studied over a wide range of the gas rarefaction degree and the parameters characterizing the distribution of the accommodation coefficient. The locally convex velocity distribution is observed in Couette flow of a highly rarefied gas, similarly to Poiseuille flow and thermal transpiration. The reciprocity relations are numerically confirmed over a wide range of the flow parameters.

Resistance Heater Helps Stirling-Engine Research

NASA Technical Reports Server (NTRS)

Hoehn, F. W.

1982-01-01

Stirling engine heater head consists of 18 double-turn coils of tubing, each of which is tightly wrapped with resistance-heating element, through which working gas flows. Coils form a toroid about periphery of heater-head body. With new resistance heater, total circuit resistance can be selected independently of tube geometry by changing size of wires and/or number of wire wraps around each tube.

40 CFR 63.4768 - What are the requirements for continuous parameter monitoring system installation, operation, and...

Code of Federal Regulations, 2014 CFR

2014-07-01

... using a carbon adsorber as an add-on control device, you must monitor the total regeneration desorbing gas (e.g., steam or nitrogen) mass flow for each regeneration cycle, the carbon bed temperature after each regeneration and cooling cycle, and comply with paragraphs (a)(3) through (5) and (d)(1) and (2...

40 CFR 86.109-94 - Exhaust gas sampling system; Otto-cycle vehicles not requiring particulate emission measurements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... concentration and total flow over the test period. (2) Vehicle tailpipe to CVS Duct. For methanol-fueled... proportional samples for the bag sample, and for methanol-fueled vehicles, the methanol sample (Figure B94-2... methanol-fueled vehicles, the sample lines for the methanol and formaldehyde samples are heated to prevent...

Measuring Heterogeneous Reaction Rates with ATR-FTIR Spectroscopy to Evaluate Chemical Fates in an Atmospheric Environment: A Physical Chemistry and Environmental Chemistry Laboratory Experiment

ERIC Educational Resources Information Center

Roberts, Jason E.; Zeng, Guang; Maron, Marta K.; Mach, Mindy; Dwebi, Iman; Liu, Yong

2016-01-01

This paper reports an undergraduate laboratory experiment to measure heterogeneous liquid/gas reaction kinetics (ozone-oleic acid and ozone-phenothrin) using a flow reactor coupled to an attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectrometer. The experiment is specially designed for an upper-level undergraduate Physical…

Preliminary Results of an Altitude-Wind-Tunnel Investigation of an Axial-Flow Gas Turbine-Propeller Engine. 5; Combustion-Chamber Characterisitcs

NASA Technical Reports Server (NTRS)

Geisenheyner, Robert M.; Berdysz, Joseph J.

1948-01-01

An investigation to determine the performance and operational characteristics of an axial-flow gas turbine-propeller engine was conducted in the Cleveland altitude wind tunnel. As part of this investigation, the combustion-chamber performance was determined at pressure altitudes from 5000 to 35,000 feet, compressor-inlet ram-pressure ratios of 1.00 and 1.09, and engine speeds from 8000 to 13,000 rpm. Combustion-chamber performance is presented as a function of corrected engine speed and corrected horsepower. For the range of corrected engine speeds investigated, overall total-pressure-loss ratio, cycle efficiency, and the fractional loss in cycle efficiency resulting from pressure losses in the combustion chambers were unaffected by a change in altitude or compressor-inlet ram-pressure ratio. For the range of corrected horsepowers investigated, the total-pressure-loss ratio and the fractional loss in cycle efficiency resulting from pressure losses in the combustion chambers decreased with an increase in corrected horsepower at a constant corrected engine speed. The combustion efficiency remained constant for the range of corrected horsepowers investigated at all corrected engine speeds.

Benefits of improved municipal solid waste management on greenhouse gas reduction in Luangprabang, Laos.

PubMed

Vilaysouk, Xaysackda; Babel, Sandhya

2017-07-01

Climate change is a consequence of greenhouse gas emissions. Greenhouse gas (GHG) emissions from the waste sector contribute to 3% of total anthropogenic emissions. In this study, applicable solutions for municipal solid waste (MSW) management in Luangprabang (LPB) and Laos were examined. Material flow analysis of MSW was performed to estimate the amount of MSW generated in 2015. Approximately 29,419 tonnes of MSW is estimated for 2015. Unmanaged landfilling was the main disposal method, while MSW open burning was also practiced to some extent. The International Panel on Climate Change 2006 model and the Atmospheric Brown Clouds Emission Inventory Manual were used to estimate GHG emissions from existing MSW management, and total emissions are 33,889 tonnes/year carbon dioxide-equivalents (CO 2 -eq). Three scenarios were developed in order to reduce GHG emissions and environmental problems. Improvement of the MSW management by expanding MSW collection services, introducing composting and recycling, and avoiding open burning, can be considered as solutions to overcome the problems for LPB. The lowest GHG emissions are achieved in the scenario where composting and recycling are proposed, with the total GHG emissions reduction by 18,264 tonnes/year CO 2 -eq.

Process for heating coal-oil slurries

DOEpatents

Braunlin, W.A.; Gorski, A.; Jaehnig, L.J.; Moskal, C.J.; Naylor, J.D.; Parimi, K.; Ward, J.V.

1984-01-03

Controlling gas to slurry volume ratio to achieve a gas holdup of about 0.4 when heating a flowing coal-oil slurry and a hydrogen containing gas stream allows operation with virtually any coal to solvent ratio and permits operation with efficient heat transfer and satisfactory pressure drops. The critical minimum gas flow rate for any given coal-oil slurry will depend on numerous factors such as coal concentration, coal particle size distribution, composition of the solvent (including recycle slurries), and type of coal. Further system efficiency can be achieved by operating with multiple heating zones to provide a high heat flux when the apparent viscosity of the gas saturated slurry is highest. Operation with gas flow rates below the critical minimum results in system instability indicated by temperature excursions in the fluid and at the tube wall, by a rapid increase and then decrease in overall pressure drop with decreasing gas flow rate, and by increased temperature differences between the temperature of the bulk fluid and the tube wall. At the temperatures and pressures used in coal liquefaction preheaters the coal-oil slurry and hydrogen containing gas stream behaves essentially as a Newtonian fluid at shear rates in excess of 150 sec[sup [minus]1]. The gas to slurry volume ratio should also be controlled to assure that the flow regime does not shift from homogeneous flow to non-homogeneous flow. Stable operations have been observed with a maximum gas holdup as high as 0.72. 29 figs.

Process for heating coal-oil slurries

DOEpatents

Braunlin, Walter A.; Gorski, Alan; Jaehnig, Leo J.; Moskal, Clifford J.; Naylor, Joseph D.; Parimi, Krishnia; Ward, John V.

1984-01-03

Controlling gas to slurry volume ratio to achieve a gas holdup of about 0.4 when heating a flowing coal-oil slurry and a hydrogen containing gas stream allows operation with virtually any coal to solvent ratio and permits operation with efficient heat transfer and satisfactory pressure drops. The critical minimum gas flow rate for any given coal-oil slurry will depend on numerous factors such as coal concentration, coal particle size distribution, composition of the solvent (including recycle slurries), and type of coal. Further system efficiency can be achieved by operating with multiple heating zones to provide a high heat flux when the apparent viscosity of the gas saturated slurry is highest. Operation with gas flow rates below the critical minimum results in system instability indicated by temperature excursions in the fluid and at the tube wall, by a rapid increase and then decrease in overall pressure drop with decreasing gas flow rate, and by increased temperature differences between the temperature of the bulk fluid and the tube wall. At the temperatures and pressures used in coal liquefaction preheaters the coal-oil slurry and hydrogen containing gas stream behaves essentially as a Newtonian fluid at shear rates in excess of 150 sec.sup. -1. The gas to slurry volume ratio should also be controlled to assure that the flow regime does not shift from homogeneous flow to non-homogeneous flow. Stable operations have been observed with a maximum gas holdup as high as 0.72.

75 FR 42330 - Elemental Mercury Used in Flow Meters, Natural Gas Manometers, and Pyrometers; Significant New...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-21

..., the sale of mercury-containing flow meters is banned in six states: California, Maine, Massachusetts... Elemental Mercury Used in Flow Meters, Natural Gas Manometers, and Pyrometers; Significant New Use Rule... mercury (CAS No. 7439-97-6) for use in flow meters, natural gas manometers, and pyrometers, except for use...

A combined CFD-experimental method for developing an erosion equation for both gas-sand and liquid-sand flows

NASA Astrophysics Data System (ADS)

Mansouri, Amir

The surface degradation of equipment due to consecutive impacts of abrasive particles carried by fluid flow is called solid particle erosion. Solid particle erosion occurs in many industries including oil and gas. In order to prevent abrupt failures and costly repairs, it is essential to predict the erosion rate and identify the locations of the equipment that are mostly at risk. Computational Fluid Dynamics (CFD) is a powerful tool for predicting the erosion rate. Erosion prediction using CFD analysis includes three steps: (1) obtaining flow solution, (2) particle tracking and calculating the particle impact speed and angle, and (3) relating the particle impact information to mass loss of material through an erosion equation. Erosion equations are commonly generated using dry impingement jet tests (sand-air), since the particle impact speed and angle are assumed not to deviate from conditions in the jet. However, in slurry flows, a wide range of particle impact speeds and angles are produced in a single slurry jet test with liquid and sand particles. In this study, a novel and combined CFD/experimental method for developing an erosion equation in slurry flows is presented. In this method, a CFD analysis is used to characterize the particle impact speed, angle, and impact rate at specific locations on the test sample. Then, the particle impact data are related to the measured erosion depth to achieve an erosion equation from submerged testing. Traditionally, it was assumed that the erosion equation developed based on gas testing can be used for both gas-sand and liquid-sand flows. The erosion equations developed in this work were implemented in a CFD code, and CFD predictions were validated for various test conditions. It was shown that the erosion equation developed based on slurry tests can significantly improve the local thickness loss prediction in slurry flows. Finally, a generalized erosion equation is proposed which can be used to predict the erosion rate in gas-sand, water-sand and viscous liquid-sand flows with high accuracy. Furthermore, in order to gain a better understanding of the erosion mechanism, a comprehensive experimental study was conducted to investigate the important factors influencing the erosion rate in gas-sand and slurry flows. The wear pattern and total erosion ratio were measured in a direct impingement jet geometry (for both dry impact and submerged impingement jets). The effects of fluid viscosity, abrasive particle size, particle impact speed, jet inclination angle, standoff distance, sand concentration, and exposure time were investigated. Also, the eroded samples were studied with Scanning Electron Microscopy (SEM) to understand the erosion micro-structure. Also, the sand particle impact speed and angle were measured using a Particle Image Velocimetry (PIV) system. The measurements were conducted in two types of erosion testers (gas-solid and liquid-solid impinging jets). The Particle Tracking Velocimetry (PTV) technique was utilized which is capable of tracking individual small particles. Moreover, CFD modeling was performed to predict the particle impact data. Very good agreement between the CFD results and PTV measurements was observed.

Cross-flow electrochemical reactor cells, cross-flow reactors, and use of cross-flow reactors for oxidation reactions

DOEpatents

Balachandran, Uthamalingam; Poeppel, Roger B.; Kleefisch, Mark S.; Kobylinski, Thaddeus P.; Udovich, Carl A.

1994-01-01

This invention discloses cross-flow electrochemical reactor cells containing oxygen permeable materials which have both electron conductivity and oxygen ion conductivity, cross-flow reactors, and electrochemical processes using cross-flow reactor cells having oxygen permeable monolithic cores to control and facilitate transport of oxygen from an oxygen-containing gas stream to oxidation reactions of organic compounds in another gas stream. These cross-flow electrochemical reactors comprise a hollow ceramic blade positioned across a gas stream flow or a stack of crossed hollow ceramic blades containing a channel or channels for flow of gas streams. Each channel has at least one channel wall disposed between a channel and a portion of an outer surface of the ceramic blade, or a common wall with adjacent blades in a stack comprising a gas-impervious mixed metal oxide material of a perovskite structure having electron conductivity and oxygen ion conductivity. The invention includes reactors comprising first and second zones seprated by gas-impervious mixed metal oxide material material having electron conductivity and oxygen ion conductivity. Prefered gas-impervious materials comprise at least one mixed metal oxide having a perovskite structure or perovskite-like structure. The invention includes, also, oxidation processes controlled by using these electrochemical reactors, and these reactions do not require an external source of electrical potential or any external electric circuit for oxidation to proceed.

Mathematical Investigation of Fluid Flow, Mass Transfer, and Slag-steel Interfacial Behavior in Gas-stirred Ladles

NASA Astrophysics Data System (ADS)

Cao, Qing; Nastac, Laurentiu

2018-06-01

In this study, the Euler-Euler and Euler-Lagrange modeling approaches were applied to simulate the multiphase flow in the water model and gas-stirred ladle systems. Detailed comparisons of the computational and experimental results were performed to establish which approach is more accurate for predicting the gas-liquid multiphase flow phenomena. It was demonstrated that the Euler-Lagrange approach is more accurate than the Euler-Euler approach. The Euler-Lagrange approach was applied to study the effects of the free surface setup, injected bubble size, gas flow rate, and slag layer thickness on the slag-steel interaction and mass transfer behavior. Detailed discussions on the flat/non-flat free surface assumption were provided. Significant inaccuracies in the prediction of the surface fluid flow characteristics were found when the flat free surface was assumed. The variations in the main controlling parameters (bubble size, gas flow rate, and slag layer thickness) and their potential impact on the multiphase fluid flow and mass transfer characteristics (turbulent intensity, mass transfer rate, slag-steel interfacial area, flow patterns, etc.,) in gas-stirred ladles were quantitatively determined to ensure the proper increase in the ladle refining efficiency. It was revealed that by injecting finer bubbles as well as by properly increasing the gas flow rate and the slag layer thickness, the ladle refining efficiency can be enhanced significantly.

Gas flow means for improving efficiency of exhaust hoods

DOEpatents

Gadgil, A.J.

1994-01-11

Apparatus is described for inhibiting the flow of contaminants in an exhaust enclosure toward an individual located adjacent an opening into the exhaust enclosure by providing a gas flow toward a source of contaminants from a position in front of an individual to urge said contaminants away from the individual toward a gas exit port. The apparatus comprises a gas manifold which may be worn by a person as a vest. The manifold has a series of gas outlets on a front face thereof facing away from the individual and toward the contaminants to thereby provide a flow of gas from the front of the individual toward the contaminants. 15 figures.

Cascading Tesla Oscillating Flow Diode for Stirling Engine Gas Bearings

NASA Technical Reports Server (NTRS)

Dyson, Rodger

2012-01-01

Replacing the mechanical check-valve in a Stirling engine with a micromachined, non-moving-part flow diode eliminates moving parts and reduces the risk of microparticle clogging. At very small scales, helium gas has sufficient mass momentum that it can act as a flow controller in a similar way as a transistor can redirect electrical signals with a smaller bias signal. The innovation here forces helium gas to flow in predominantly one direction by offering a clear, straight-path microchannel in one direction of flow, but then through a sophisticated geometry, the reversed flow is forced through a tortuous path. This redirection is achieved by using microfluid channel flow to force the much larger main flow into this tortuous path. While microdiodes have been developed in the past, this innovation cascades Tesla diodes to create a much higher pressure in the gas bearing supply plenum. In addition, the special shape of the leaves captures loose particles that would otherwise clog the microchannel of the gas bearing pads.

An inverse gas chromatographic methodology for studying gas-liquid mass transfer.

PubMed

Paloglou, A; Martakidis, K; Gavril, D

2017-01-13

A novel methodology of reversed flow inverse gas chromatography (RF-IGC) is presented. It permits the simultaneous determination of mass transfer coefficients across the gas liquid interface as well as the respective solubility parameters and thermodynamic functions of dissolution of gases into liquids. The standard deviation of the experimentally determined parameters is estimated for first time, which combined with the successful comparison of the values of the present parameters with other literature ones ascertain the reliability of the methodology. Another novelty of the present work is that the chromatographic sampling of the physicochemical phenomena is done without performing the usual flow reversals procedure. Vinyl chloride monomer's (VCM) interaction with various composition liquid foods: orange juice, milk and olive oil was used as model system. The present transfer rates are controlled by the gas film at lower temperatures, but at higher temperatures the resistances in both films tend to become equal. The found liquid diffusivity values express the total mass transfer from the gas phase into the liquid's bulk and they decrease with rising temperature, as the solubilities of gases in liquids do. Solubility, expressed by Henry's law constant and the mean values of interfacial thickness are of the same order of magnitude to literature ones. From the thermodynamic point of view, VCM dissolution in all liquids is accompanied by significant heat release and it is a slightly non-spontaneous process, near equilibrium, while the entropy change values are negative. Copyright © 2016 Elsevier B.V. All rights reserved.

Fundamental Mixing and Combustion Experiments for Propelled Hypersonic Flight

NASA Technical Reports Server (NTRS)

Cutler, A. D.; Diskin, G. S.; Danehy, P. M.; Drummond, J. P.

2002-01-01

Two experiments have been conducted to acquire data for the validation of computational fluid dynamics (CFD) codes used in the design of supersonic combustors. The first experiment is a study of a supersonic coaxial jet into stagnant air in which the center jet is of a light gas, the coflow jet is of air, and the mixing layer between them is compressible. The jet flow field is characterized using schlieren imaging, surveys with Pitot, total temperature and gas sampling probes, and RELIEF velocimetry. VULCAN, a structured grid CFD code, is used to solve for the nozzle and jet flow. The second experiment is a study of a supersonic combustor consisting of a diverging duct with single downstream-angled wall injector. Entrance Mach number is 2 and enthalpy is nominally that of Mach 7 flight. Coherent anti-Stokes Raman spectroscopy (CARS) has been used to obtain nitrogen temperature in planes of the flow, and surface pressures and temperatures have also been acquired. Modern-design-of-experiment techniques have been used to maximize the quality of the data set.

Modeling of Gas Production from Shale Reservoirs Considering Multiple Transport Mechanisms.

PubMed

Guo, Chaohua; Wei, Mingzhen; Liu, Hong

2015-01-01

Gas transport in unconventional shale strata is a multi-mechanism-coupling process that is different from the process observed in conventional reservoirs. In micro fractures which are inborn or induced by hydraulic stimulation, viscous flow dominates. And gas surface diffusion and gas desorption should be further considered in organic nano pores. Also, the Klinkenberg effect should be considered when dealing with the gas transport problem. In addition, following two factors can play significant roles under certain circumstances but have not received enough attention in previous models. During pressure depletion, gas viscosity will change with Knudsen number; and pore radius will increase when the adsorption gas desorbs from the pore wall. In this paper, a comprehensive mathematical model that incorporates all known mechanisms for simulating gas flow in shale strata is presented. The objective of this study was to provide a more accurate reservoir model for simulation based on the flow mechanisms in the pore scale and formation geometry. Complex mechanisms, including viscous flow, Knudsen diffusion, slip flow, and desorption, are optionally integrated into different continua in the model. Sensitivity analysis was conducted to evaluate the effect of different mechanisms on the gas production. The results showed that adsorption and gas viscosity change will have a great impact on gas production. Ignoring one of following scenarios, such as adsorption, gas permeability change, gas viscosity change, or pore radius change, will underestimate gas production.

Modeling of Gas Production from Shale Reservoirs Considering Multiple Transport Mechanisms

PubMed Central

Guo, Chaohua; Wei, Mingzhen; Liu, Hong

2015-01-01

Gas transport in unconventional shale strata is a multi-mechanism-coupling process that is different from the process observed in conventional reservoirs. In micro fractures which are inborn or induced by hydraulic stimulation, viscous flow dominates. And gas surface diffusion and gas desorption should be further considered in organic nano pores. Also, the Klinkenberg effect should be considered when dealing with the gas transport problem. In addition, following two factors can play significant roles under certain circumstances but have not received enough attention in previous models. During pressure depletion, gas viscosity will change with Knudsen number; and pore radius will increase when the adsorption gas desorbs from the pore wall. In this paper, a comprehensive mathematical model that incorporates all known mechanisms for simulating gas flow in shale strata is presented. The objective of this study was to provide a more accurate reservoir model for simulation based on the flow mechanisms in the pore scale and formation geometry. Complex mechanisms, including viscous flow, Knudsen diffusion, slip flow, and desorption, are optionally integrated into different continua in the model. Sensitivity analysis was conducted to evaluate the effect of different mechanisms on the gas production. The results showed that adsorption and gas viscosity change will have a great impact on gas production. Ignoring one of following scenarios, such as adsorption, gas permeability change, gas viscosity change, or pore radius change, will underestimate gas production. PMID:26657698

Study of Liquid Breakup Process in Solid Rocket Motor Nozzle

DTIC Science & Technology

2016-02-16

liquid film flow with the gas flow. The rate of the wave breakup was characterized by introducing Breakup-length, Ohnesorge Number (Oh) and Weber Number... liquid film that flows along the wall of a strraight test channel while a relatively higher-speed gas moves over it. We have used an unsteady-flow...Reynolds- Averaged Navier-Stokes code (URANS) to investigate the interaction of the liquid film flow with the gas flow. The rate of the wave breakup was

Compressible flow at high pressure with linear equation of state

NASA Astrophysics Data System (ADS)

Sirignano, William A.

2018-05-01

Compressible flow varies from ideal-gas behavior at high pressures where molecular interactions become important. Density is described through a cubic equation of state while enthalpy and sound speed are functions of both temperature and pressure, based on two parameters, A and B, related to intermolecular attraction and repulsion, respectively. Assuming small variations from ideal-gas behavior, a closed-form solution is obtained that is valid over a wide range of conditions. An expansion in these molecular-interaction parameters simplifies relations for flow variables, elucidating the role of molecular repulsion and attraction in variations from ideal-gas behavior. Real-gas modifications in density, enthalpy, and sound speed for a given pressure and temperature lead to variations in many basic compressible flow configurations. Sometimes, the variations can be substantial in quantitative or qualitative terms. The new approach is applied to choked-nozzle flow, isentropic flow, nonlinear-wave propagation, and flow across a shock wave, all for the real gas. Modifications are obtained for allowable mass-flow through a choked nozzle, nozzle thrust, sonic wave speed, Riemann invariants, Prandtl's shock relation, and the Rankine-Hugoniot relations. Forced acoustic oscillations can show substantial augmentation of pressure amplitudes when real-gas effects are taken into account. Shocks at higher temperatures and pressures can have larger pressure jumps with real-gas effects. Weak shocks decay to zero strength at sonic speed. The proposed framework can rely on any cubic equation of state and be applied to multicomponent flows or to more-complex flow configurations.

DSMC simulation of two-phase plume flow with UV radiation

NASA Astrophysics Data System (ADS)

Li, Jie; Liu, Ying; Wang, Ning; Jin, Ling

2014-12-01

Rarefied gas-particle two-phase plume in which the phase of particles is liquid or solid flows from a solid propellant rocket of hypersonic vehicle flying at high altitudes, the aluminum oxide particulates not only impact the rarefied gas flow properties, but also make a great difference to plume radiation signature, so the radiation prediction of the rarefied gas-particle two-phase plume flow is very important for space target detection of hypersonic vehicles. Accordingly, this project aims to study the rarefied gas-particle two-phase flow and ultraviolet radiation (UV) characteristics. Considering a two-way interphase coupling of momentum and energy, the direct simulation Monte Carlo (DSMC) method is developed for particle phase change and the particle flow, including particulate collision, coalescence as well as separation, and a Monte Carlo ray trace model is implemented for the particulate UV radiation. A program for the numerical simulation of the gas-particle two-phase flow and radiation in which the gas flow nonequilibrium is strong is implemented as well. Ultraviolet radiation characteristics of the particle phase is studied based on the calculation of the flow field coupled with the radiation calculation, the radiation model for different size particles is analyzed, focusing on the effects of particle emission, absorption, scattering as well as the searchlight emission of the nozzle. A new approach may be proposed to describe the rarefied gas-particle two-phase plume flow and radiation transfer characteristics in this project.

Effects of gas reservoir configuration and pore radius on shale gas nanoflow: A molecular dynamics study.

PubMed

Tian, Huiquan; Guo, Guang-Jun; Geng, Ming; Zhang, Zhengcai; Zhang, Mingmin; Gao, Kai

2018-05-28

We calculated methane transport through cylindrical graphite nanopores in cyclical steady-state flows using non-equilibrium molecular dynamics simulations. First, two typical gas reservoir configurations were evaluated: open (OS) and closed (CS) systems in which pores connect to the gas reservoir without/with a graphite wall parallel to the gas flow. We found that the OS configuration, which is commonly used to study nanoflows, exhibited obvious size effects. Smaller gas reservoir cross-sectional areas were associated with faster gas flows. Because Knudsen diffusion and slip flow in pores are interrupted in a gas reservoir that does not have walls as constraints, OSs cannot be relied upon in cyclical nanoflow simulations. Although CSs eliminated size effects, they introduced surface roughness effects that stem from the junction surface between the gas reservoir and the pore. To obtain a convergent nanoflow, the length of a side of the gas reservoir cross-section should be at least 2 nm larger than the pore diameter. Second, we obtained methane flux data for various pore radii (0.5-2.5 nm) in CSs and found that they could be described accurately using the Javadpour formula. This is the first direct molecular simulation evidence to validate this formula. Finally, the radial density and flow-velocity distributions of methane in CS pores were analyzed in detail. We tested pores with a radius between 0.5 nm and 2.5 nm and determined that the maximum ratio (∼34%) of slip flow to overall flow occurred in the pore with a radius of 1.25 nm. This study will aid in the design of gas reservoir configurations for nanoflow simulations and is helpful in understanding shale gas nanoflows.

Effects of gas reservoir configuration and pore radius on shale gas nanoflow: A molecular dynamics study

NASA Astrophysics Data System (ADS)

Tian, Huiquan; Guo, Guang-Jun; Geng, Ming; Zhang, Zhengcai; Zhang, Mingmin; Gao, Kai

2018-05-01

We calculated methane transport through cylindrical graphite nanopores in cyclical steady-state flows using non-equilibrium molecular dynamics simulations. First, two typical gas reservoir configurations were evaluated: open (OS) and closed (CS) systems in which pores connect to the gas reservoir without/with a graphite wall parallel to the gas flow. We found that the OS configuration, which is commonly used to study nanoflows, exhibited obvious size effects. Smaller gas reservoir cross-sectional areas were associated with faster gas flows. Because Knudsen diffusion and slip flow in pores are interrupted in a gas reservoir that does not have walls as constraints, OSs cannot be relied upon in cyclical nanoflow simulations. Although CSs eliminated size effects, they introduced surface roughness effects that stem from the junction surface between the gas reservoir and the pore. To obtain a convergent nanoflow, the length of a side of the gas reservoir cross-section should be at least 2 nm larger than the pore diameter. Second, we obtained methane flux data for various pore radii (0.5-2.5 nm) in CSs and found that they could be described accurately using the Javadpour formula. This is the first direct molecular simulation evidence to validate this formula. Finally, the radial density and flow-velocity distributions of methane in CS pores were analyzed in detail. We tested pores with a radius between 0.5 nm and 2.5 nm and determined that the maximum ratio (˜34%) of slip flow to overall flow occurred in the pore with a radius of 1.25 nm. This study will aid in the design of gas reservoir configurations for nanoflow simulations and is helpful in understanding shale gas nanoflows.

Better Gas-Gap Thermal Switches For Sorption Compressors

NASA Technical Reports Server (NTRS)

Bhandari, Pradeep; Rodriguez, Jose

1995-01-01

Gas-gap thermal switches associated with sorption compressors of some heat pumps and cryogenic systems designed for higher performance, according to proposal, by introducing controlled turbulent flows into gas gaps. Utilizes convection in turbulent flow to transfer heat at greater rate. Design takes advantage of flow of working fluid. Working fluid also serve as heat transfer medium in gas gap.

Use of exhaust gas as sweep flow to enhance air separation membrane performance

DOEpatents

Dutart, Charles H.; Choi, Cathy Y.

2003-01-01

An intake air separation system for an internal combustion engine is provided with purge gas or sweep flow on the permeate side of separation membranes in the air separation device. Exhaust gas from the engine is used as a purge gas flow, to increase oxygen flux in the separation device without increasing the nitrogen flux.

Growth of a Massive Young Stellar Object Fed by a Gas Flow from a Companion Gas Clump

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

Chen, Xi; Shen, Zhiqiang; Ren, Zhiyuan

We present a Submillimeter Array (SMA) observation toward the young massive double-core system G350.69-0.49. This system consists of a northeast (NE) diffuse gas bubble and a southwest (SW) massive young stellar object (MYSO), both clearly seen in the Spitzer images. The SMA observations reveal a gas flow between the NE bubble and the SW MYSO in a broad velocity range from 5 to 30 km s{sup −1} with respect to the system velocity. The gas flow is well confined within the interval between the two objects and traces a significant mass transfer from the NE gas bubble to the SWmore » massive core. The transfer flow can supply the material accreted onto the SW MYSO at a rate of 4.2×10{sup −4} M{sub ⊙} yr{sup −1}. The whole system therefore suggests a mode for the mass growth in the MYSO from a gas transfer flow launched from its companion gas clump, despite the driving mechanism of the transfer flow not being fully determined from the current data.« less

Analysis of temperature and pressure changes in liquefied natural gas (LNG) cryogenic tanks

NASA Astrophysics Data System (ADS)

Chen, Q.-S.; Wegrzyn, J.; Prasad, V.

2004-10-01

Liquefied natural gas (LNG) is being developed as a transportation fuel for heavy vehicles such as trucks and transit buses, to lessen the dependency on oil and to reduce greenhouse gas emissions. The LNG stations are properly designed to prevent the venting of natural gas (NG) from LNG tanks, which can cause evaporative greenhouse gas emissions and result in fluctuations of fuel flow and changes of fuel composition. Boil-off is caused by the heat added into the LNG fuel during the storage and fueling. Heat can leak into the LNG fuel through the shell of tank during the storage and through hoses and dispensers during the fueling. Gas from tanks onboard vehicles, when returned to LNG tanks, can add additional heat into the LNG fuel. A thermodynamic and heat transfer model has been developed to analyze different mechanisms of heat leak into the LNG fuel. The evolving of properties and compositions of LNG fuel inside LNG tanks is simulated. The effect of a number of buses fueled each day on the possible total fuel loss rate has been analyzed. It is found that by increasing the number of buses, fueled each day, the total fuel loss rate can be reduced significantly. It is proposed that an electric generator be used to consume the boil-off gas or a liquefier be used to re-liquefy the boil-off gas to reduce the tank pressure and eliminate fuel losses. These approaches can prevent boil-off of natural gas emissions, and reduce the costs of LNG as transportation fuel.

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

A novel pump-driven veno-venous gas exchange system during extracorporeal CO2-removal.

PubMed

Hermann, Alexander; Riss, Katharina; Schellongowski, Peter; Bojic, Andja; Wohlfarth, Philipp; Robak, Oliver; Sperr, Wolfgang R; Staudinger, Thomas

2015-10-01

Pump-driven veno-venous extracorporeal CO2-removal (ECCO2-R) increasingly takes root in hypercapnic lung failure to minimize ventilation invasiveness or to avoid intubation. A recently developed device (iLA activve(®), Novalung, Germany) allows effective decarboxylation via a 22 French double lumen cannula. To assess determinants of gas exchange, we prospectively evaluated the performance of ECCO2-R in ten patients receiving iLA activve(®) due to hypercapnic respiratory failure. Sweep gas flow was increased in steps from 1 to 14 L/min at constant blood flow (phase 1). Similarly, blood flow was gradually increased at constant sweep gas flow (phase 2). At each step gas transfer via the membrane as well as arterial blood gas samples were analyzed. During phase 1, we observed a significant increase in CO2 transfer together with a decrease in PaCO2 levels from a median of 66 mmHg (range 46-85) to 49 (31-65) mmHg from 1 to 14 L/min sweep gas flow (p < 0.0001), while arterial oxygenation deteriorated with high sweep gas flow rates. During phase 2, oxygen transfer significantly increased leading to an increase in PaO2 from 67 (49-87) at 0.5 L/min to 117 (66-305) mmHg at 2.0 L/min (p < 0.0001). Higher blood flows also significantly enhanced decarboxylation (p < 0.0001). Increasing sweep gas flow results in effective CO2-removal, which can be further reinforced by raising blood flow. The clinically relevant oxygenation effect in this setting could broaden the range of indications of the system and help to set up an individually tailored configuration.

System for controlling the flow of gas into and out of a gas laser

DOEpatents

Alger, Terry; Uhlich, Dennis M.; Benett, William J.; Ault, Earl R.

1994-01-01

A modularized system for controlling the gas pressure within a copper vapor or like laser is described herein. This system includes a gas input assembly which serves to direct gas into the laser in a controlled manner in response to the pressure therein for maintaining the laser pressure at a particular value, for example 40 torr. The system also includes a gas output assembly including a vacuum pump and a capillary tube arrangement which operates within both a viscous flow region and a molecular flow region for drawing gas out of the laser in a controlled manner.

Flow chemistry: intelligent processing of gas-liquid transformations using a tube-in-tube reactor.

PubMed

Brzozowski, Martin; O'Brien, Matthew; Ley, Steven V; Polyzos, Anastasios

2015-02-17

CONSPECTUS: The previous decade has witnessed the expeditious uptake of flow chemistry techniques in modern synthesis laboratories, and flow-based chemistry is poised to significantly impact our approach to chemical preparation. The advantages of moving from classical batch synthesis to flow mode, in order to address the limitations of traditional approaches, particularly within the context of organic synthesis are now well established. Flow chemistry methodology has led to measurable improvements in safety and reduced energy consumption and has enabled the expansion of available reaction conditions. Contributions from our own laboratories have focused on the establishment of flow chemistry methods to address challenges associated with the assembly of complex targets through the development of multistep methods employing supported reagents and in-line monitoring of reaction intermediates to ensure the delivery of high quality target compounds. Recently, flow chemistry approaches have addressed the challenges associated with reactions utilizing reactive gases in classical batch synthesis. The small volumes of microreactors ameliorate the hazards of high-pressure gas reactions and enable improved mixing with the liquid phase. Established strategies for gas-liquid reactions in flow have relied on plug-flow (or segmented flow) regimes in which the gas plugs are introduced to a liquid stream and dissolution of gas relies on interfacial contact of the gas bubble with the liquid phase. This approach confers limited control over gas concentration within the liquid phase and is unsuitable for multistep methods requiring heterogeneous catalysis or solid supported reagents. We have identified the use of a gas-permeable fluoropolymer, Teflon AF-2400, as a simple method of achieving efficient gas-liquid contact to afford homogeneous solutions of reactive gases in flow. The membrane permits the transport of a wide range of gases with significant control of the stoichiometry of reactive gas in a given reaction mixture. We have developed a tube-in-tube reactor device consisting of a pair of concentric capillaries in which pressurized gas permeates through an inner Teflon AF-2400 tube and reacts with dissolved substrate within a liquid phase that flows within a second gas impermeable tube. This Account examines our efforts toward the development of a simple, unified methodology for the processing of gaseous reagents in flow by way of development of a tube-in-tube reactor device and applications to key C-C, C-N, and C-O bond forming and hydrogenation reactions. We further describe the application to multistep reactions using solid-supported reagents and extend the technology to processes utilizing multiple gas reagents. A key feature of our work is the development of computer-aided imaging techniques to allow automated in-line monitoring of gas concentration and stoichiometry in real time. We anticipate that this Account will illustrate the convenience and benefits of membrane tube-in-tube reactor technology to improve and concomitantly broaden the scope of gas/liquid/solid reactions in organic synthesis.

A mechanistic model of heat transfer for gas-liquid flow in vertical wellbore annuli.

PubMed

Yin, Bang-Tang; Li, Xiang-Fang; Liu, Gang

2018-01-01

The most prominent aspect of multiphase flow is the variation in the physical distribution of the phases in the flow conduit known as the flow pattern. Several different flow patterns can exist under different flow conditions which have significant effects on liquid holdup, pressure gradient and heat transfer. Gas-liquid two-phase flow in an annulus can be found in a variety of practical situations. In high rate oil and gas production, it may be beneficial to flow fluids vertically through the annulus configuration between well tubing and casing. The flow patterns in annuli are different from pipe flow. There are both casing and tubing liquid films in slug flow and annular flow in the annulus. Multiphase heat transfer depends on the hydrodynamic behavior of the flow. There are very limited research results that can be found in the open literature for multiphase heat transfer in wellbore annuli. A mechanistic model of multiphase heat transfer is developed for different flow patterns of upward gas-liquid flow in vertical annuli. The required local flow parameters are predicted by use of the hydraulic model of steady-state multiphase flow in wellbore annuli recently developed by Yin et al. The modified heat-transfer model for single gas or liquid flow is verified by comparison with Manabe's experimental results. For different flow patterns, it is compared with modified unified Zhang et al. model based on representative diameters.

Bidirectional Pressure-Regulator System

NASA Technical Reports Server (NTRS)

Burke, Kenneth; Miller, John R.

2008-01-01

A bidirectional pressure-regulator system has been devised for use in a regenerative fuel cell system. The bidirectional pressure-regulator acts as a back-pressure regulator as gas flows through the bidirectional pressure-regulator in one direction. Later, the flow of gas goes through the regulator in the opposite direction and the bidirectional pressure-regulator operates as a pressure- reducing pressure regulator. In the regenerative fuel cell system, there are two such bidirectional regulators, one for the hydrogen gas and another for the oxygen gas. The flow of gases goes from the regenerative fuel cell system to the gas storage tanks when energy is being stored, and reverses direction, flowing from the storage tanks to the regenerative fuel cell system when the stored energy is being withdrawn from the regenerative fuel cell system. Having a single bidirectional regulator replaces two unidirectional regulators, plumbing, and multiple valves needed to reverse the flow direction. The term "bidirectional" refers to both the bidirectional nature of the gas flows and capability of each pressure regulator to control the pressure on either its upstream or downstream side, regardless of the direction of flow.

Method for determining waveguide temperature for acoustic transceiver used in a gas turbine engine

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

DeSilva, Upul P.; Claussen, Heiko; Ragunathan, Karthik

A method for determining waveguide temperature for at least one waveguide of a transceiver utilized for generating a temperature map. The transceiver generates an acoustic signal that travels through a measurement space in a hot gas flow path defined by a wall such as in a combustor. The method includes calculating a total time of flight for the acoustic signal and subtracting a waveguide travel time from the total time of flight to obtain a measurement space travel time. A temperature map is calculated based on the measurement space travel time. An estimated wall temperature is obtained from the temperaturemore » map. An estimated waveguide temperature is then calculated based on the estimated wall temperature wherein the estimated waveguide temperature is determined without the use of a temperature sensing device.« less

Effect of gas flow ratio on the microstructure and mechanical properties of boron phosphide films prepared by reactive magnetron sputtering

NASA Astrophysics Data System (ADS)

Jia, Z. C.; Zhu, J. Q.; Jiang, C. Z.; Shen, W. X.; Han, J. C.; Chen, R. R.

2011-10-01

Boron phosphide films were grown on silicon substrate by radio frequency reactive magnetron sputtering using boron target and hydrogen phosphine at different gas flow ratios (PH 3/Ar) at lower temperature. The chemical composition, microstructure and mechanical properties were characterized by X-ray photoelectron spectroscopy, X-ray diffraction, Raman spectrum, FTIR spectrum, surface profilometer and nano-indenter. The results indicate that the atomic ratio (P/B) rises from 1.06 up to 1.52 with the gas flow ratio increasing from 3/50 to 15/50. Simultaneously, the hardness and Young's modulus decrease from 25.4 GPa to 22.5 GPa, and 250.4 GPa to 238.4 GPa, respectively. Microstructure transforms from microcrystalline state to amorphous state along with the gas flow ratio increasing. Furthermore higher gas flow ratio leads to lower stress. The BP film prepared at the gas flow ratio of 3/50 can be contributed with the best properties.

Method and apparatus for enhancing reactor air-cooling system performance

DOEpatents

Hunsbedt, Anstein

1996-01-01

An enhanced decay heat removal system for removing heat from the inert gas-filled gap space between the reactor vessel and the containment vessel of a liquid metal-cooled nuclear reactor. Multiple cooling ducts in flow communication with the inert gas-filled gap space are incorporated to provide multiple flow paths for the inert gas to circulate to heat exchangers which remove heat from the inert gas, thereby introducing natural convection flows in the inert gas. The inert gas in turn absorbs heat directly from the reactor vessel by natural convection heat transfer.

The radial-azimuthal stability of accretion disks - Gas pressure contributions

NASA Technical Reports Server (NTRS)

Mckee, M. R.

1991-01-01

A radial-azimuthal stability analysis of a thin, alpha disk accretion flow is presented. The proportion of radiation pressure, Pr, of the unperturbed flow is allowed to vary according to the parameter beta = Pr/P, where P is the total pressure. As is the case for a purely radial analysis, the disk is stable for beta equal to or less than 0.6. However, the coupling of radial and azimuthal perturbations eliminates the viscous instability for such nonradial modes for all values of beta. The group velocity of the retrograde thermal mode is calculated as a function of beta.

Generalized second-order slip boundary condition for nonequilibrium gas flows

NASA Astrophysics Data System (ADS)

Guo, Zhaoli; Qin, Jishun; Zheng, Chuguang

2014-01-01

It is a challenging task to model nonequilibrium gas flows within a continuum-fluid framework. Recently some extended hydrodynamic models in the Navier-Stokes formulation have been developed for such flows. A key problem in the application of such models is that suitable boundary conditions must be specified. In the present work, a generalized second-order slip boundary condition is developed in which an effective mean-free path considering the wall effect is used. By combining this slip scheme with certain extended Navier-Stokes constitutive relation models, we obtained a method for nonequilibrium gas flows with solid boundaries. The method is applied to several rarefied gas flows involving planar or curved walls, including the Kramers' problem, the planar Poiseuille flow, the cylindrical Couette flow, and the low speed flow over a sphere. The results show that the proposed method is able to give satisfied predictions, indicating the good potential of the method for nonequilibrium flows.

Gaseous oxygen uptake in porous media at different moisture contents and airflow velocities.

PubMed

Sharma, Prabhakar; Poulsen, Tjalfe G; Kalluri, Prasad N V

2009-06-01

The presence and distribution of water in the pore space is a critical factor for flow and transport of gases through unsaturated porous media. The water content also affects the biological activity necessary for treatment of polluted gas streams in biofilters. In this research, microbial activity and quantity of inactive volume in a porous medium as a function of moisture content and gas flow rate were investigated. Yard waste compost was used as a test medium, and oxygen uptake rate measurements were used to quantify microbial activity and effective active compost volume using batch and column flow-through systems. Compost water contents were varied from air-dry to field capacity and gas flows ranged from 0.2 to 2 L x min(-1). The results showed that overall microbial activity and the relative fraction of active compost medium volume increased with airflow velocity for all levels of water content up to a certain flow rate above which the oxygen uptake rate assumed a constant value independent of gas flow. The actual value of the maximum oxygen uptake rate was controlled by the water content. The oxygen uptake rate also increased with increasing water content and reached a maximum between 42 and 48% volumetric water content, above which it decreased, again likely because of formation of inactive zones in the compost medium. Overall, maximum possible oxygen uptake rate as a function of gas flow rate across all water contents and gas flows could be approximated by a linear expression. The relative fraction of active volume also increased with gas flow rate and reached approximately 80% for the highest gas flows used.

Pressure-Drop Considerations in the Characterization of Dew-Point Transfer Standards at High Temperatures

NASA Astrophysics Data System (ADS)

Mitter, H.; Böse, N.; Benyon, R.; Vicente, T.

2012-09-01

During calibration of precision optical dew-point hygrometers (DPHs), it is usually necessary to take into account the pressure drop induced by the gas flow between the "point of reference" and the "point of use" (mirror or measuring head of the DPH) either as a correction of the reference dew-point temperature or as part of the uncertainty estimation. At dew-point temperatures in the range of ambient temperature and below, it is sufficient to determine the pressure drop for the required gas flow, and to keep the volumetric flow constant during the measurements. In this case, it is feasible to keep the dry-gas flow into the dew-point generator constant or to measure the flow downstream the DPH at ambient temperature. In normal operation, at least one DPH in addition to the monitoring DPH are used, and this operation has to be applied to each instrument. The situation is different at high dew-point temperatures up to 95 °C, the currently achievable upper limit reported in this paper. With increasing dew-point temperatures, the reference gas contains increasing amounts of water vapour and a constant dry-gas flow will lead to a significant enhanced volume flow at the conditions at the point of use, and therefore, to a significantly varying pressure drop depending on the applied dew-point temperature. At dew-point temperatures above ambient temperature, it is also necessary to heat the reference gas and the mirror head of the DPH sufficiently to avoid condensation which will additionally increase the volume flow and the pressure drop. In this paper, a method is provided to calculate the dry-gas flow rate needed to maintain a known wet-gas flow rate through a chilled mirror for a range of temperature and pressures.

Frozen Chemistry Effects on Nozzle Performance Simulations

NASA Technical Reports Server (NTRS)

Yoder, Dennis A.; Georgiadis, Nicholas J.; O'Gara, Michael R.

2009-01-01

Simulations of exhaust nozzle flows are typically conducted assuming the gas is calorically perfect, and typically modeled as air. However the gas inside a real nozzle is generally composed of combustion products whose thermodynamic properties may differ. In this study, the effect of gas model assumption on exhaust nozzle simulations is examined. The three methods considered model the nozzle exhaust gas as calorically perfect air, a calorically perfect exhaust gas mixture, and a frozen exhaust gas mixture. In the latter case the individual non-reacting species are tracked and modeled as a gas which is only thermally perfect. Performance parameters such as mass flow rate, gross thrust, and thrust coefficient are compared as are mean flow and turbulence profiles in the jet plume region. Nozzles which operate at low temperatures or have low subsonic exit Mach numbers experience relatively minor temperature variations inside the nozzle, and may be modeled as a calorically perfect gas. In those which operate at the opposite extreme conditions, variations in the thermodynamic properties can lead to different expansion behavior within the nozzle. Modeling these cases as a perfect exhaust gas flow rather than air captures much of the flow features of the frozen chemistry simulations. Use of the exhaust gas reduces the nozzle mass flow rate, but has little effect on the gross thrust. When reporting nozzle thrust coefficient results, however, it is important to use the appropriate gas model assumptions to compute the ideal exit velocity. Otherwise the values obtained may be an overly optimistic estimate of nozzle performance.

The effects of gas humidification with high-flow nasal cannula on cultured human airway epithelial cells.

PubMed

Chidekel, Aaron; Zhu, Yan; Wang, Jordan; Mosko, John J; Rodriguez, Elena; Shaffer, Thomas H

2012-01-01

Humidification of inspired gas is important for patients receiving respiratory support. High-flow nasal cannula (HFNC) effectively provides temperature and humidity-controlled gas to the airway. We hypothesized that various levels of gas humidification would have differential effects on airway epithelial monolayers. Calu-3 monolayers were placed in environmental chambers at 37°C with relative humidity (RH) < 20% (dry), 69% (noninterventional comparator), and >90% (HFNC) for 4 and 8 hours with 10 L/min of room air. At 4 and 8 hours, cell viability and transepithelial resistance measurements were performed, apical surface fluid was collected and assayed for indices of cell inflammation and function, and cells were harvested for histology (n = 6/condition). Transepithelial resistance and cell viability decreased over time (P < 0.001) between HFNC and dry groups (P < 0.001). Total protein secretion increased at 8 hours in the dry group (P < 0.001). Secretion of interleukin (IL)-6 and IL-8 in the dry group was greater than the other groups at 8 hours (P < 0.001). Histological analysis showed increasing injury over time for the dry group. These data demonstrate that exposure to low humidity results in reduced epithelial cell function and increased inflammation.

The Effects of Gas Humidification with High-Flow Nasal Cannula on Cultured Human Airway Epithelial Cells

PubMed Central

Chidekel, Aaron; Zhu, Yan; Wang, Jordan; Mosko, John J.; Rodriguez, Elena; Shaffer, Thomas H.

2012-01-01

Humidification of inspired gas is important for patients receiving respiratory support. High-flow nasal cannula (HFNC) effectively provides temperature and humidity-controlled gas to the airway. We hypothesized that various levels of gas humidification would have differential effects on airway epithelial monolayers. Calu-3 monolayers were placed in environmental chambers at 37°C with relative humidity (RH) < 20% (dry), 69% (noninterventional comparator), and >90% (HFNC) for 4 and 8 hours with 10 L/min of room air. At 4 and 8 hours, cell viability and transepithelial resistance measurements were performed, apical surface fluid was collected and assayed for indices of cell inflammation and function, and cells were harvested for histology (n = 6/condition). Transepithelial resistance and cell viability decreased over time (P < 0.001) between HFNC and dry groups (P < 0.001). Total protein secretion increased at 8 hours in the dry group (P < 0.001). Secretion of interleukin (IL)-6 and IL-8 in the dry group was greater than the other groups at 8 hours (P < 0.001). Histological analysis showed increasing injury over time for the dry group. These data demonstrate that exposure to low humidity results in reduced epithelial cell function and increased inflammation. PMID:22988501

Fluid Flow Patterns During Production from Gas Hydrates in the Laboratory compared to Field Settings: LARS vs. Mallik

NASA Astrophysics Data System (ADS)

Strauch, B.; Heeschen, K. U.; Priegnitz, M.; Abendroth, S.; Spangenberg, E.; Thaler, J.; Schicks, J. M.

2015-12-01

The GFZ's LArge Reservoir Simulator LARS allows for the simulation of the 2008 Mallik gas hydrate production test and the comparison of fluid flow patterns and their driving forces. Do we see the gas flow pattern described for Mallik [Uddin, M. et al., J. Can. Petrol Tech, 50, 70-89, 2011] in a pilot scale test? If so, what are the driving forces? LARS has a network of temperature sensors and an electric resistivity tomography (ERT) enabling a good spatial resolution of gas hydrate occurrences, water and gas distribution, and changes in temperature in the sample. A gas flow meter and a water trap record fluid flow patterns and a backpressure valve has controlled the depressurization equivalent to the three pressure stages (7.0 - 5.0 - 4.2 MPa) applied in the Mallik field test. The environmental temperature (284 K) and confining pressure (13 MPa) have been constant. The depressurization induced immediate endothermic gas hydrate dissociation until re-establishment of the stability conditions by a consequent temperature decrease. Slight gas hydrate dissociation continued at the top and upper lateral border due to the constant heat input from the environment. Here transport pathways were short and permeability higher due to lower gas hydrate saturation. At pressures of 7.0 and 5.0 MPa the LARS tests showed high water flow rates and short irregular spikes of gas production. The gas flow patterns at 4.2 MPa and 3.0MPa resembled those of the Mallik test. In LARS the initial gas surges overlap with times of hydrate instability while water content and lengths of pathways had increased. Water production was at a minimum. A rapidly formed continuous gas phase caused the initial gas surges and only after gas hydrate dissociation decreased to a minimum the single gas bubbles get trapped before slowly coalescing again. In LARS, where pathways were short and no additional water was added, a transport of microbubbles is unlikely to cause a gas surge as suggested for Mallik.

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

Duke, Daniel J.; Kastengren, Alan L.; Swantek, Andrew B.

The dynamics of dissolved gas and cavitation are strongly coupled, yet these phenomena are difficult to measure in-situ. Both create voids in the fluid that can be difficult to distinguish. In this paper, we present an application of X-ray fluorescence in which liquid density and total noncondensible gas concentration (both dissolved and nucleated) are simultaneously measured. The liquid phase is doped with 400 ppm of a bromine tracer, and dissolved air is removed and substituted with krypton. Fluorescent emission at X-ray wavelengths is simultaneously excited from the Br and Kr with a focused monochromatic X-ray beam from a synchrotron source.more » We measure the flow in a cavitating nozzle 0.5 mm in diameter. From Br fluorescence, total displacement of the liquid is measured. From Kr fluorescence, the mass fraction of both dissolved and nucleated gas is measured. Volumetric displacement of liquid due to both cavitation and gas precipitation can be separated through estimation of the local equilibrium dissolved mass fraction. The uncertainty in the line of sight projected densities of the liquid and gas phases is 4–6 %. The high fluorescence yields and energies of Br and Kr allow small mass fractions of gas to be measured, down to 10 -5, with an uncertainty of 8 %. Finally, these quantitative measurements complement existing optical diagnostic techniques and provide new insight into the diffusion of gas into cavitation bubbles, which can increase their internal density, pressure and lifetimes by orders of magnitude.« less

Behavior and dynamics of bubble breakup in gas pipeline leaks and accidental subsea oil well blowouts.

PubMed

Wang, Binbin; Socolofsky, Scott A; Lai, Chris C K; Adams, E Eric; Boufadel, Michel C

2018-06-01

Subsea oil well blowouts and pipeline leaks release oil and gas to the environment through vigorous jets. Predicting the breakup of the released fluids in oil droplets and gas bubbles is critical to predict the fate of petroleum compounds in the marine water column. To predict the gas bubble size in oil well blowouts and pipeline leaks, we observed and quantified the flow behavior and breakup process of gas for a wide range of orifice diameters and flow rates. Flow behavior at the orifice transitions from pulsing flow to continuous discharge as the jet crosses the sonic point. Breakup dynamics transition from laminar to turbulent at a critical value of the Weber number. Very strong pure gas jets and most gas/liquid co-flowing jets exhibit atomization breakup. Bubble sizes in the atomization regime scale with the jet-to-plume transition length scale and follow -3/5 power-law scaling for a mixture Weber number. Copyright © 2018 Elsevier Ltd. All rights reserved.

Turbine exhaust diffuser with region of reduced flow area and outer boundary gas flow

DOEpatents

Orosa, John

2014-03-11

An exhaust diffuser system and method for a turbine engine. The outer boundary may include a region in which the outer boundary extends radially inwardly toward the hub structure and may direct at least a portion of an exhaust flow in the diffuser toward the hub structure. At least one gas jet is provided including a jet exit located on the outer boundary. The jet exit may discharge a flow of gas downstream substantially parallel to an inner surface of the outer boundary to direct a portion of the exhaust flow in the diffuser toward the outer boundary to effect a radially outward flow of at least a portion of the exhaust gas flow toward the outer boundary to balance an aerodynamic load between the outer and inner boundaries.

Noble gas storage and delivery system for ion propulsion

NASA Technical Reports Server (NTRS)

Back, Dwight Douglas (Inventor); Ramos, Charlie (Inventor)

2001-01-01

A method and system for storing and delivering a noble gas for an ion propulsion system where an adsorbent bearing a noble gas is heated within a storage vessel to desorb the noble gas which is then flowed through a pressure reduction device to a thruster assembly. The pressure and flow is controlled using a flow restrictor and low wattage heater which heats an adsorbent bed containing the noble gas propellant at low pressures. Flow rates of 5-60 sccm can be controlled to within about 0.5% or less and the required input power is generally less than 50 W. This noble gas storage and delivery system and method can be used for earth orbit satellites, and lunar or planetary space missions.

Velocimetry using scintillation of a laser beam for a laser-based gas-flux monitor

NASA Astrophysics Data System (ADS)

Kagawa, Naoki; Wada, Osami; Koga, Ryuji

1999-05-01

This paper describes a velocimetry system using scintillation of a laser-beam with spatial filters based on sensor arrays for a laser- based gas flux monitor. In the eddy correlation method, gas flux is obtained by mutual relation between the gas density and the flow velocity. The velocimetry system is developed to support the flow velocity monitor portion of the laser-based gas flux monitor with a long span for measurement. In order to sense not only the flow velocity but also the flow direction, two photo diode arrays are arranged with difference of a quarter period of the weighting function between them; the two output signals from the sensor arrays have phase difference of either (pi) /2 or -(pi) /2 depending on the sense of flow direction. In order to obtain the flow velocity and the flow direction instantly, an electronic apparatus built by the authors extracts frequency and phase from crude outputs of the pair of sensors. A feasibility of the velocimetry was confirmed indoors by measurement of the flow- velocity vector of the convection. Measured flow-velocity vector of the upward flow agreed comparatively with results of an ultrasonic anemometer.

Using noble gases measured in spring discharge to trace hydrothermal processes in the Norris Geyser Basin, Yellowstone National Park, U.S.A.

USGS Publications Warehouse

Gardner, W.P.; Susong, D.D.; Solomon, D.K.; Heasler, H.P.

2010-01-01

Dissolved noble gas concentrations in springs are used to investigate boiling of hydrothermal water and mixing of hydrothermal and shallow cool water in the Norris Geyser Basin area. Noble gas concentrations in water are modeled for single stage and continuous steam removal. Limitations on boiling using noble gas concentrations are then used to estimate the isotopic effect of boiling on hydrothermal water, allowing the isotopic composition of the parent hydrothermal water to be determined from that measured in spring. In neutral chloride springs of the Norris Geyser Basin, steam loss since the last addition of noble gas charged water is less than 30% of the total hydrothermal discharge, which results in an isotopic shift due to boiling of ?? 2.5% ??D. Noble gas concentrations in water rapidly and predictably change in dual phase systems, making them invaluable tracers of gas-liquid interaction in hydrothermal systems. By combining traditional tracers of hydrothermal flow such as deuterium with dissolved noble gas measurements, more complex hydrothermal processes can be interpreted. ?? 2010 Elsevier B.V.

Natural gas flow through critical nozzles

NASA Technical Reports Server (NTRS)

Johnson, R. C.

1969-01-01

Empirical method for calculating both the mass flow rate and upstream volume flow rate through critical flow nozzles is determined. Method requires knowledge of the composition of natural gas, and of the upstream pressure and temperature.

Slip length measurement of gas flow.

PubMed

Maali, Abdelhamid; Colin, Stéphane; Bhushan, Bharat

2016-09-16

In this paper, we present a review of the most important techniques used to measure the slip length of gas flow on isothermal surfaces. First, we present the famous Millikan experiment and then the rotating cylinder and spinning rotor gauge methods. Then, we describe the gas flow rate experiment, which is the most widely used technique to probe a confined gas and measure the slip. Finally, we present a promising technique using an atomic force microscope introduced recently to study the behavior of nanoscale confined gas.

Gas Flow in the Capillary of the Atmosphere-to-Vacuum Interface of Mass Spectrometers

NASA Astrophysics Data System (ADS)

Skoblin, Michael; Chudinov, Alexey; Soulimenkov, Ilia; Brusov, Vladimir; Kozlovskiy, Viacheslav

2017-10-01

Numerical simulations of a gas flow through a capillary being a part of mass spectrometer atmospheric interface were performed using a detailed laminar flow model. The simulated interface consisted of atmospheric and forevacuum volumes connected via a thin capillary. The pressure in the forevacuum volume where the gas was expanding after passing through the capillary was varied in the wide range from 10 to 900 mbar in order to study the volume flow rate as well as the other flow parameters as functions of the pressure drop between the atmospheric and forevacuum volumes. The capillary wall temperature was varied in the range from 24 to 150 °C. Numerical integration of the complete system of Navier-Stokes equations for a viscous compressible gas taking into account the heat transfer was performed using the standard gas dynamic simulation software package ANSYS CFX. The simulation results were compared with experimental measurements of gas flow parameters both performed using our experimental setup and taken from the literature. The simulated volume flow rates through the capillary differed no more than by 10% from the measured ones over the entire pressure and temperatures ranges. A conclusion was drawn that the detailed digital laminar model is able to quantitatively describe the measured gas flow rates through the capillaries under conditions considered. [Figure not available: see fulltext.

Gas Flow in the Capillary of the Atmosphere-to-Vacuum Interface of Mass Spectrometers.

PubMed

Skoblin, Michael; Chudinov, Alexey; Soulimenkov, Ilia; Brusov, Vladimir; Kozlovskiy, Viacheslav

2017-10-01

Numerical simulations of a gas flow through a capillary being a part of mass spectrometer atmospheric interface were performed using a detailed laminar flow model. The simulated interface consisted of atmospheric and forevacuum volumes connected via a thin capillary. The pressure in the forevacuum volume where the gas was expanding after passing through the capillary was varied in the wide range from 10 to 900 mbar in order to study the volume flow rate as well as the other flow parameters as functions of the pressure drop between the atmospheric and forevacuum volumes. The capillary wall temperature was varied in the range from 24 to 150 °C. Numerical integration of the complete system of Navier-Stokes equations for a viscous compressible gas taking into account the heat transfer was performed using the standard gas dynamic simulation software package ANSYS CFX. The simulation results were compared with experimental measurements of gas flow parameters both performed using our experimental setup and taken from the literature. The simulated volume flow rates through the capillary differed no more than by 10% from the measured ones over the entire pressure and temperatures ranges. A conclusion was drawn that the detailed digital laminar model is able to quantitatively describe the measured gas flow rates through the capillaries under conditions considered. Graphical Abstract ᅟ.

Rarefied gas electro jet (RGEJ) micro-thruster for space propulsion

NASA Astrophysics Data System (ADS)

Blanco, Ariel; Roy, Subrata

2017-11-01

This article numerically investigates a micro-thruster for small satellites which utilizes plasma actuators to heat and accelerate the flow in a micro-channel with rarefied gas in the slip flow regime. The inlet plenum condition is considered at 1 Torr with flow discharging to near vacuum conditions (<0.05 Torr). The Knudsen numbers at the inlet and exit planes are ~0.01 and ~0.1, respectively. Although several studies have been performed in micro-hallow cathode discharges at constant pressure, to our knowledge, an integrated study of the glow discharge physics and resulting fluid flow of a plasma thruster under these low pressure and low Knudsen number conditions is yet to be reported. Numerical simulations of the charge distribution due to gas ionization processes and the resulting rarefied gas flow are performed using an in-house code. The mass flow rate, thrust, specific impulse, power consumption and the thrust effectiveness of the thruster are predicted based on these results. The ionized gas is modelled using local mean energy approximation. An electrically induced body force and a thermal heating source are calculated based on the space separated charge distribution and the ion Joule heating, respectively. The rarefied gas flow with these electric force and heating source is modelled using density-based compressible flow equations with slip flow boundary conditions. The results show that a significant improvement of specific impulse can be achieved over highly optimized cold gas thrusters using the same propellant.

Boosting devices with integral features for recirculating exhaust gas

DOEpatents

Wu, Ko-Jen

2015-12-22

According to one embodiment of the invention, a turbine housing includes a turbine inlet in fluid communication with a turbine volute configured to house a turbine wheel, the turbine inlet configured to direct an exhaust gas flow from an engine to the turbine wheel. The turbine housing also includes a turbine outlet in fluid communication with the turbine volute, the turbine outlet configured to direct the exhaust gas flow to an exhaust gas conduit and a first exhaust gas recirculation supply port located on and in fluid communication with the turbine outlet, the first exhaust gas recirculation supply port being configured to direct a portion of the exhaust gas flow to an exhaust gas recirculation supply conduit.

Gas flow path for a gas turbine engine

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

Montgomery, Matthew D.; Charron, Richard C.; Snyder, Gary D.

A duct arrangement in a can annular gas turbine engine. The gas turbine engine has a gas delivery structure for delivering gases from a plurality of combustors to an annular chamber that extends circumferentially and is oriented concentric to a gas turbine engine longitudinal axis for delivering the gas flow to a first row of blades A gas flow path is formed by the duct arrangement between a respective combustor and the annular chamber for conveying gases from each combustor to the first row of turbine blades The duct arrangement includes at least one straight section having a centerline thatmore » is misaligned with a centerline of the combustor.« less

Plane Poiseuille flow of a rarefied gas in the presence of strong gravitation.

PubMed

Doi, Toshiyuki

2011-02-01

Plane Poiseuille flow of a rarefied gas, which flows horizontally in the presence of strong gravitation, is studied based on the Boltzmann equation. Applying the asymptotic analysis for a small variation in the flow direction [Y. Sone, Molecular Gas Dynamics (Birkhäuser, 2007)], the two-dimensional problem is reduced to a one-dimensional problem, as in the case of a Poiseuille flow in the absence of gravitation, and the solution is obtained in a semianalytical form. The reduced one-dimensional problem is solved numerically for a hard sphere molecular gas over a wide range of the gas-rarefaction degree and the gravitational strength. The presence of gravitation reduces the mass flow rate, and the effect of gravitation is significant for large Knudsen numbers. To verify the validity of the asymptotic solution, a two-dimensional problem of a flow through a long channel is directly solved numerically, and the validity of the asymptotic solution is confirmed. ©2011 American Physical Society

Experimental perfect-gas study of expansion-tube flow characteristics

NASA Technical Reports Server (NTRS)

Shinn, J. L.; Miller, C. G., III

1978-01-01

Results of an experimental investigation of expansion tube flow characteristics performed with helium test gas and acceleration gas are presented. The use of helium, eliminates complex real gas chemistry in the comparison of measured and predicted flow quantities. The driver gas was unheated helium at a nominal pressure of 33 MN sq m. The quiescent test gas pressure and quiescent acceleration gas pressure were varied from 0.7 to 50 kN/sq m and from 2.5 to 53 N/sq m, respectively. The effects of tube-wall boundary layer growth and finite secondary diaphragm opening time were examined through the variation of the quiescent gas pressures and secondary diaphragm thickness. Optimum operating conditions for helium test gas were also defined.

Non-contact ultrasonic gas flow metering using air-coupled leaky Lamb waves.

PubMed

Fan, Zichuan; Jiang, Wentao; Wright, William M D

2018-04-23

This paper describes a completely non-contact ultrasonic method of gas flow metering using air-coupled leaky Lamb waves. To show proof of principle, a simplified representation of gas flow in a duct, comprising two separated thin isotropic plates with a gas flowing between them, has been modelled and investigated experimentally. An airborne compression wave emitted from an air-coupled capacitive ultrasonic transducer excited a leaky Lamb wave in the first plate in a non-contact manner. The leakage of this Lamb wave crossed the gas flow at an angle between the two plates as a compression wave, and excited a leaky Lamb wave in the second plate. An air-coupled capacitive ultrasonic transducer on the opposite side of this second plate then detected the airborne compression wave leakage from the second Lamb wave. As the gas flow shifted the wave field between the two plates, the point of Lamb wave excitation in the second plate was displaced in proportion to the gas flow rate. Two such measurements, in opposite directions, formed a completely non-contact contra-propagating Lamb wave flow meter, allowing measurement of the flow velocity between the plates. A COMSOL Multiphysics® model was used to visualize the wave fields, and accurately predicted the time differences that were then measured experimentally. Experiments using different Lamb wave frequencies and plate materials were also similarly verified. This entirely non-contact airborne approach to Lamb wave flow metering could be applied in place of clamp-on techniques in thin-walled ducts or pipes. Copyright © 2018 Elsevier B.V. All rights reserved.

40 CFR 86.1320-90 - Gas meter or flow instrumentation calibration; particulate, methanol, and formaldehyde measurement.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 20 2012-07-01 2012-07-01 false Gas meter or flow instrumentation... instrumentation calibration; particulate, methanol, and formaldehyde measurement. (a) Sampling for particulate, methanol and formaldehyde emissions requires the use of gas meters or flow instrumentation to determine...

40 CFR 86.1320-90 - Gas meter or flow instrumentation calibration; particulate, methanol, and formaldehyde measurement.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 20 2013-07-01 2013-07-01 false Gas meter or flow instrumentation... instrumentation calibration; particulate, methanol, and formaldehyde measurement. (a) Sampling for particulate, methanol and formaldehyde emissions requires the use of gas meters or flow instrumentation to determine...

40 CFR 86.1320-90 - Gas meter or flow instrumentation calibration; particulate, methanol, and formaldehyde measurement.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 19 2010-07-01 2010-07-01 false Gas meter or flow instrumentation... instrumentation calibration; particulate, methanol, and formaldehyde measurement. (a) Sampling for particulate, methanol and formaldehyde emissions requires the use of gas meters or flow instrumentation to determine...

40 CFR 86.1320-90 - Gas meter or flow instrumentation calibration; particulate, methanol, and formaldehyde measurement.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 19 2011-07-01 2011-07-01 false Gas meter or flow instrumentation... instrumentation calibration; particulate, methanol, and formaldehyde measurement. (a) Sampling for particulate, methanol and formaldehyde emissions requires the use of gas meters or flow instrumentation to determine...

Gas turbine engine with radial diffuser and shortened mid section

DOEpatents

Charron, Richard C.; Montgomery, Matthew D.

2015-09-08

An industrial gas turbine engine (10), including: a can annular combustion assembly (80), having a plurality of discrete flow ducts configured to receive combustion gas from respective combustors (82) and deliver the combustion gas along a straight flow path at a speed and orientation appropriate for delivery directly onto the first row (56) of turbine blades (62); and a compressor diffuser (32) having a redirecting surface (130, 140) configured to receive an axial flow of compressed air and redirect the axial flow of compressed air radially outward.

The evolution of cooling flows. I - Self-similar cluster flows. [of gas in intergalactic medium

NASA Technical Reports Server (NTRS)

Chevalier, Roger A.

1987-01-01

The evolution of a cooling flow from an initial state of hydrostatic equilibrium in a cluster of galaxies is investigated. After gas mass and energy are injected into the cluster at an early phase, the gas approaches hydrostatic equilibrium over most of the cluster and cooling becomes important in the dense central regions. As time passes, cooling strongly affects an increasing amount of gas. The effects of mass removal from the flow, the inclusion of magnetic or cosmic-ray pressure, and heat conduction are considered individually.

Schlieren flow visualization of helium atmospheric plasma jet and influence of the gas flow rate and applied voltage frequency

NASA Astrophysics Data System (ADS)

Borghei, S. M.; Vaziri, N.; Alibabaei, S.

2018-03-01

We used schlieren photography to visualize the influence of gas flow rates of 1, 2.5, 5, 10 L/min and of the applied voltage frequency on a helium atmospheric plasma jet induced at the nozzle of a capillary tube. The expansion of the gas in the surrounding medium (air) was analyzed in the two different modes – plasma on/plasma off. Changes in the above parameters affect the gas flow regime and the hydrodynamics of the jet.

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

White, D.B.

This paper reports on experiments to examine gas migration rates in drilling muds that were performed in a 15-m-long, 200-mm-ID inclinable flow loop where air injection simulates gas entry during a kick. These tests were conducted using a xanthum gum (a common polymer used in drilling fluids) solution to simulate drilling muds as the liquid phase and air as the gas phase. This work represents a significant extension of existing correlations for gas/liquid flows in large pipe diameters with non- Newtonian fluids. Bubbles rise faster in drilling muds than in water despite the increased viscosity. This surprising result is causedmore » by the change in the flow regime, with large slug-type bubbles forming at lower void fractions. The gas velocity is independent of void fraction, thus simplifying flow modeling. Results show that a gas influx will rise faster in a well than previously believed. This has major implications for kick simulation, with gas arriving at the surface earlier than would be expected and the gas outflow rate being higher than would have been predicted. A model of the two-phase gas flow in drilling mud, including the results of this work, has been incorporated into the joint Schlumberger Cambridge Research (SCR)/BP Intl. kick model.« less

Study of Gas Flow Characteristics in Tight Porous Media with a Microscale Lattice Boltzmann Model

PubMed Central

Zhao, Jianlin; Yao, Jun; Zhang, Min; Zhang, Lei; Yang, Yongfei; Sun, Hai; An, Senyou; Li, Aifen

2016-01-01

To investigate the gas flow characteristics in tight porous media, a microscale lattice Boltzmann (LB) model with the regularization procedure is firstly adopted to simulate gas flow in three-dimensional (3D) digital rocks. A shale digital rock and a sandstone digital rock are reconstructed to study the effects of pressure, temperature and pore size on microscale gas flow. The simulation results show that because of the microscale effect in tight porous media, the apparent permeability is always higher than the intrinsic permeability, and with the decrease of pressure or pore size, or with the increase of temperature, the difference between apparent permeability and intrinsic permeability increases. In addition, the Knudsen numbers under different conditions are calculated and the results show that gas flow characteristics in the digital rocks under different Knudsen numbers are quite different. With the increase of Knudsen number, gas flow in the digital rocks becomes more uniform and the effect of heterogeneity of the porous media on gas flow decreases. Finally, two commonly used apparent permeability calculation models are evaluated by the simulation results and the Klinkenberg model shows better accuracy. In addition, a better proportionality factor in Klinkenberg model is proposed according to the simulation results. PMID:27587293

Silicon etching of difluoromethane atmospheric pressure plasma jet combined with its spectroscopic analysis

NASA Astrophysics Data System (ADS)

Sung, Yu-Ching; Wei, Ta-Chin; Liu, You-Chia; Huang, Chun

2018-06-01

A capacitivly coupled radio-frequency double-pipe atmospheric-pressure plasma jet is used for etching. An argon carrier gas is supplied to the plasma discharge jet; and CH2F2 etch gas is inserted into the plasma discharge jet, near the silicon substrate. Silicon etchings rate can be efficiently-controlled by adjusting the feeding etching gas composition and plasma jet operating parameters. The features of silicon etched by the plasma discharge jet are discussed in order to spatially spreading plasma species. Electronic excitation temperature and electron density are detected by increasing plasma power. The etched silicon profile exhibited an anisotropic shape and the etching rate was maximum at the total gas flow rate of 4500 sccm and CH2F2 concentration of 11.1%. An etching rate of 17 µm/min was obtained at a plasma power of 100 W.

Experimental Evaluation of a Subscale Gaseous Hydrogen/gaseous Oxygen Coaxial Rocket Injector

NASA Technical Reports Server (NTRS)

Smith, Timothy D.; Klem, Mark D.; Breisacher, Kevin J.; Farhangi, Shahram; Sutton, Robert

2002-01-01

The next generation reusable launch vehicle may utilize a Full-Flow Stage Combustion (FFSC) rocket engine cycle. One of the key technologies required is the development of an injector that uses gaseous oxygen and gaseous hydrogen as propellants. Gas-gas propellant injection provides an engine with increased stability margin over a range of throttle set points. This paper summarizes an injector design and testing effort that evaluated a coaxial rocket injector for use with gaseous oxygen and gaseous hydrogen propellants. A total of 19 hot-fire tests were conducted up to a chamber pressure of 1030 psia, over a range of 3.3 to 6.7 for injector element mixture ratio. Post-test condition of the hardware was also used to assess injector face cooling. Results show that high combustion performance levels could be achieved with gas-gas propellants and there were no problems with excessive face heating for the conditions tested.

Modeling of static and flowing-gas diode pumped alkali lasers

NASA Astrophysics Data System (ADS)

Barmashenko, Boris D.; Auslender, Ilya; Yacoby, Eyal; Waichman, Karol; Sadot, Oren; Rosenwaks, Salman

2016-03-01

Modeling of static and flowing-gas subsonic, transonic and supersonic Cs and K Ti:Sapphire and diode pumped alkali lasers (DPALs) is reported. A simple optical model applied to the static K and Cs lasers shows good agreement between the calculated and measured dependence of the laser power on the incident pump power. The model reproduces the observed threshold pump power in K DPAL which is much higher than that predicted by standard models of the DPAL. Scaling up flowing-gas DPALs to megawatt class power is studied using accurate three-dimensional computational fluid dynamics model, taking into account the effects of temperature rise and losses of alkali atoms due to ionization. Both the maximum achievable power and laser beam quality are estimated for Cs and K lasers. The performance of subsonic and, in particular, supersonic DPALs is compared with that of transonic, where supersonic nozzle and diffuser are spared and high power mechanical pump (needed for recovery of the gas total pressure which strongly drops in the diffuser), is not required for continuous closed cycle operation. For pumping by beams of the same rectangular cross section, comparison between end-pumping and transverse-pumping shows that the output power is not affected by the pump geometry, however, the intensity of the output laser beam in the case of transverse-pumped DPALs is strongly non-uniform in the laser beam cross section resulting in higher brightness and better beam quality in the far field for the end-pumping geometry where the intensity of the output beam is uniform.

Effects of oxygen partial pressure, deposition temperature, and annealing on the optical response of CdS:O thin films as studied by spectroscopic ellipsometry

NASA Astrophysics Data System (ADS)

Junda, Maxwell M.; Grice, Corey R.; Subedi, Indra; Yan, Yanfa; Podraza, Nikolas J.

2016-07-01

Ex-situ spectroscopic ellipsometry measurements are made on radio frequency magnetron sputtered oxygenated cadmium sulfide (CdS:O) thin films. Films are deposited onto glass substrates at room temperature and at 270 °C with varying oxygen to total gas flow ratios in the sputtering ambient. Ellipsometric spectra from 0.74 to 5.89 eV are collected before and after annealing at 607 °C to simulate the thermal processes during close-space sublimation of overlying cadmium telluride in that solar cell configuration. Complex dielectric function (ɛ = ɛ1 + iɛ2) spectra are extracted for films as a function of oxygen gas flow ratio, deposition temperature, and post-deposition annealing using a parametric model accounting for critical point transitions and an Urbach tail for sub-band gap absorption. The results suggest an inverse relationship between degree of crystallinity and oxygen gas flow ratio, whereas annealing is shown to increase crystallinity in all samples. Direct band gap energies are determined from the parametric modeling of ɛ and linear extrapolations of the square of the absorption coefficient. As-deposited samples feature a range of band gap energies whereas annealing is shown to result in gap energies ranging only from 2.40 to 2.45 eV, which is close to typical band gaps for pure cadmium sulfide.

Gas dynamic improvement of the axial compressor design for reduction of the flow non-uniformity level

NASA Astrophysics Data System (ADS)

Matveev, V. N.; Baturin, O. V.; Kolmakova, D. A.; Popov, G. M.

2017-01-01

Circumferential nonuniformity of gas flow is one of the main problems in the gas turbine engine. Usually, the flow circumferential nonuniformity appears near the annular frame located in the flow passage of the engine. The presence of circumferential nonuniformity leads to the increased dynamic stresses in the blade rows and the blade damage. The goal of this research was to find the ways of the flow non-uniformity reduction, which would not require a fundamental changing of the engine design. A new method for reducing the circumferential nonuniformity of the gas flow was proposed that allows the prediction of the pressure peak values of the rotor blades without computationally expensive CFD calculations.

Low NO sub x heavy fuel combustor concept program phase 1A gas tests

NASA Technical Reports Server (NTRS)

Cutrone, M. B.; Beebe, K. W.; Cutrone, M. B.

1982-01-01

The emissions performance of a rich lean combustor (developed for liquid fuels) for combustion of simulated coal gases ranging in heating value from 167 to 244 Btu/scf were assessed. The 244 Btu/scf gas is typical of the product gas from an oxygen blown gasifier, while the 167 Btu/scf gas is similar to that from an air blown gasifier. Although meeting NOx goals for the 167 Btu/scf gas, NOx performance of the rich lean combustor did not meet program goals with the 244 Btu/scf gas because of high thermal NOx, similar to levels expected from conventional lean burning combustors. The NOx emissions are attributed to inadequate fuel air mixing in the rich stage resulting from the design of the large central fuel nozzle delivering 71% of the total gas flow. NOx generation from NH3 was significant at ammonia concentrations significantly less tha 0.5%. These levels occur depending on fuel gas cleanup system design, However, NOx yield from ammonia injected into the fuel gas decreased rapidly with increasing ammonia level, and is projected to be less than 10% at NH3 levels of 0.5% or higher.

Study of the coupling between real gas effects and rarefied effects on hypersonic aerodynamics

NASA Astrophysics Data System (ADS)

Chen, Song; Hu, Yuan; Sun, Quanhua

2012-11-01

Hypersonic vehicles travel across the atmosphere at very high speed, and the surrounding gas experiences complicated physical and chemical processes. These processes produce real gas effects at high temperature and rarefied gas effects at high altitude where the two effects are coupled through molecular collisions. In this study, we aim to identify the individual real gas and rarefied gas effects by simulating hypersonic flow over a 2D cylinder, a sphere and a blunted cone using a continuum-based CFD approach and the direct simulation Monte Carlo method. It is found that physical processes such as vibrational excitation and chemical reaction will reduce significantly the shock stand-off distance and flow temperature for flows having small Knudsen number. The calculated skin friction and surface heat flux will decrease when the real gas effects are considered in simulations. The trend, however, gets weakened as the Knudsen number increases. It is concluded that the rarefied gas effects weaken the real gas effects on hypersonic flows.

Selective Catalytic Combustion Sensors for Reactive Organic Analysis

NASA Technical Reports Server (NTRS)

Innes, W. B.

1971-01-01

Sensors involving a vanadia-alumina catalyst bed-thermocouple assembly satisfy requirements for simple, reproducible and rapid continuous analysis or reactive organics. Responses generally increase with temperature to 400 C and increase to a maximum with flow rate/catalyst volume. Selectivity decreases with temperature. Response time decreases with flow rate and increases with catalyst volume. At chosen optimum conditions calculated response which is additive and linear agrees better with photochemical reactivity than other methods for various automotive sources, and response to vehicle exhaust is insensitive to flow rate. Application to measurement of total reactive organics in vehicle exhaust as well as for gas chromatography detection illustrate utility. The approach appears generally applicable to high thermal effect reactions involving first order kinetics.

The effect of floating vegetation on denitrification and greenhouse gas production in wetland mesocosms

NASA Astrophysics Data System (ADS)

Jacobs, A. E.; Harrison, J. A.

2012-12-01

Anthropogenic intensification of nitrogen (N) loading to aquatic ecosystems is widespread and can lead to the degradation of these systems. Wetlands are important sites for N removal via denitrification, the microbially mediated reduction of reactive nitrate to inert N2 gas, but they can also produce high levels of greenhouse gases. Floating plants play an important role in encouraging denitrification, since they create low oxygen conditions that may favor denitrification. We investigated whether wetland sediments with floating plant cover had higher denitrification and greenhouse gas production rates than wetland sediments without floating plants. Replicate flow-through mesocosms with wetland sediment and water were constructed in a growth chamber to mimic the wetland where the sediment and water were collected. Mesocosm treatments were covered with floating vegetation (duckweed), an opaque tarp, or no cover to determine how cover type affects denitrification and greenhouse gas production and whether biotic or abiotic factors are likely responsible for observed differences. Denitrification and greenhouse gas production rates were calculated by measuring excess N2 gas, methane, and nitrous oxide concentrations in the water column and measuring the gas exchange rates between the water column and the atmosphere. Gas exchange rates were measured using an inert volatile tracer added to the water column and accumulation of gas in the mesocosm headspace. Additional mesocosm experiments were performed to determine how duckweed-dominated wetland systems respond to nitrogen loading and which mechanism for lowering dissolved oxygen concentrations is important in affecting denitrification under floating vegetation. Mesocosms with floating vegetation had lower dissolved oxygen than no cover or tarp-covered mesocosms, which is consistent with field and literature observations. Water flowing out of the mesocosms had statistically lower total nitrogen and nitrate concentrations compared to inflow water, and calculated denitrification was statistically higher in the floating vegetation treatments compared to the other treatments. Greenhouse gas production, measured in CO2 equivalents for N2O and CH4, was highly variable and not statistically different between the treatments. Denitrification in the tarp covered mesocosms was similar to the no-cover treatment, indicating that biotic effects in the floating vegetation treatment may be important in lowering water column oxygen levels and increasing denitrification. Understanding how floating vegetation affects total nitrogen loss, denitrification, and greenhouse gas production can be used to weigh ecological costs and benefits of different vegetation types, especially in constructed and managed wetlands.

Growth and biochemical characteristics of an indigenous freshwater microalga, Scenedesmus obtusus, cultivated in an airlift photobioreactor: effect of reactor hydrodynamics, light intensity, and photoperiod.

PubMed

Sarat Chandra, T; Aditi, S; Maneesh Kumar, M; Mukherji, S; Modak, J; Chauhan, V S; Sarada, R; Mudliar, S N

2017-07-01

The freshwater green algae, Scenedesmus obtusus, was cultivated in a 3.4 L airlift photobioreactor. The hydrodynamic parameters were estimated at different inlet gas flow rates (1, 2, 3, and 4 LPM) and their subsequent impact on the growth and biochemical characteristics of microalgae was studied. The biomass concentration and productivity increased with an increase in flow rates from 1 to 4 LPM. A maximum of 0.07 g L -1  day -1 productivity of biomass was attained at 3 LPM. An increase of total carbohydrate content from 19.6 to 26.4% was noticed with increment in the inlet flow rate of gas from 1 to 4 LPM. Major variations in total fatty acid content were not observed. The impact of light irradiance on growth and biochemical characteristics of S. obtusus was also evaluated. A maximum biomass productivity of 0.103 g L -1  day -1 was attained at an illumination of 150 μmol m -2  s -1 under continuous light. The major fatty acids reported were palmitic acid (C16:0), α-linolenic acid (C18:3), linoleic acid (C18:2), and oleic acid (C18:1). Biodiesel properties of the microalgae were estimated under various culture conditions. The light profile inside the airlift reactor was experimentally measured and the predictive modelling of light profile was also attempted.

Gas flows in radial micro-nozzles with pseudo-shocks

NASA Astrophysics Data System (ADS)

Kiselev, S. P.; Kiselev, V. P.; Zaikovskii, V. N.

2018-07-01

In the present paper, results of an experimental and numerical study of supersonic gas flows in radial micro-nozzles are reported. A distinguishing feature of such flows is the fact that two factors, the nozzle divergence and the wall friction force, exert a substantial influence on the flow structure. Under the action of the wall friction force, in the micro-nozzle there forms a pseudo-shock that separates the supersonic from subsonic flow region. The position of the pseudo-shock can be evaluated from the condition of flow blockage in the nozzle exit section. A detailed qualitative and quantitative analysis of gas flows in radial micro-nozzles is given. It is shown that the gas flow in a micro-nozzle is defined by the complicated structure of the boundary layer in the micro-nozzle, this structure being dependent on the width-to-radius ratio of the nozzle and its inlet-to-outlet pressure ratio.

Solution of weakly compressible isothermal flow in landfill gas collection networks

NASA Astrophysics Data System (ADS)

Nec, Y.; Huculak, G.

2017-12-01

Pipe networks collecting gas in sanitary landfills operate under the regime of a weakly compressible isothermal flow of ideal gas. The effect of compressibility has been traditionally neglected in this application in favour of simplicity, thereby creating a conceptual incongruity between the flow equations and thermodynamic equation of state. Here the flow is solved by generalisation of the classic Darcy-Weisbach equation for an incompressible steady flow in a pipe to an ordinary differential equation, permitting continuous variation of density, viscosity and related fluid parameters, as well as head loss or gain due to gravity, in isothermal flow. The differential equation is solved analytically in the case of ideal gas for a single edge in the network. Thereafter the solution is used in an algorithm developed to construct the flow equations automatically for a network characterised by an incidence matrix, and determine pressure distribution, flow rates and all associated parameters therein.

Carbon dioxide and methane emissions from the Yukon River system

USGS Publications Warehouse

Striegl, Robert G.; Dornblaser, Mark M.; McDonald, Cory P.; Rover, Jennifer R.; Stets, Edward G.

2012-01-01

Carbon dioxide (CO2) and methane (CH4) emissions are important, but poorly quantified, components of riverine carbon (C) budgets. This is largely because the data needed for gas flux calculations are sparse and are spatially and temporally variable. Additionally, the importance of C gas emissions relative to lateral C exports is not well known because gaseous and aqueous fluxes are not commonly measured on the same rivers. We couple measurements of aqueous CO2 and CH4 partial pressures (pCO2, pCH4) and flux across the water-air interface with gas transfer models to calculate subbasin distributions of gas flux density. We then combine those flux densities with remote and direct observations of stream and river water surface area and ice duration, to calculate C gas emissions from flowing waters throughout the Yukon River basin. CO2emissions were 7.68 Tg C yr−1 (95% CI: 5.84 −10.46), averaging 750 g C m−2 yr−1 normalized to water surface area, and 9.0 g C m−2 yr−1 normalized to river basin area. River CH4 emissions totaled 55 Gg C yr−1 or 0.7% of the total mass of C emitted as CO2 plus CH4 and ∼6.4% of their combined radiative forcing. When combined with lateral inorganic plus organic C exports to below head of tide, C gas emissions comprised 50% of total C exported by the Yukon River and its tributaries. River CO2 and CH4 derive from multiple sources, including groundwater, surface water runoff, carbonate equilibrium reactions, and benthic and water column microbial processing of organic C. The exact role of each of these processes is not yet quantified in the overall river C budget.

Smart Application of Direct Gas Injection using a new conceptual model on Coherent and Incoherent Flow: From Bench Scale to Field Scale.

NASA Astrophysics Data System (ADS)

Geistlinger, H.; Samani, S.; Pohlert, M.; Martienssen, M.; Engelmann, F.; Hüttmann, S.

2008-12-01

Within the framework of the OXYWALL field experiment we developed the direct gas injection (DGI) of oxygen as a remediation technology, which allows the cost-efficient and large-scale cleaning of groundwater contaminated with organic contaminants. That technology can be used as wide-banded, unselective remediation method for complex contaminant mixtures. Particularly, it could be proofed in field experiments that mineral oil hydrocarbons, aromatic hydrocarbons (BTEX), the rather persistent gasoline component Methyl tertiary-butyl ether (MTBE), and chlorinated aliphatic and aromatic hydrocarbons, like Trichloroethene and Monochlorobenzene, can be aerobically metabolized by autochthon microorganisms. Over the last 8 years the field site was investigated and a dense monitoring network was installed using Geoprobe direct- push technology and standard hydrogeological investigations were conducted, like EC-Logs, Injections-Logs, Gamma-Logs, TDR-probes, oxygen measurements with in-situ optodes, and tracer test with test gases SF6, Ar, and Oxygen. The key parameter for controling and regulating the DGI is the spatial and temporal distribution of the gas phase. High-resolution optical bench scale experiments were conducted in order to investigate local gas flow pattern and integral flow properties caused by point-like gas injection into water-saturated glass beads and natural sands. We observed a grain-size (dk)- and flow-rate (Q) dependent transition from incoherent to coherent flow. Conceptualizing the stationary tortuous gas flow as core-annulus flow and applying Hagen- Poiseuille flow for a straight capillary, we propose a flow-rate- and grain-size dependent stability criterion that could describe our experimental results and was used for classifying the experiments in a dk-Q-diagram (flow chart). Since DGI simulations are mainly based on continuum models, we also test the validity of the continuum approach for two-fluid flow in macroscopic homogeneous media by comparing our experimental flow pattern with the theoretical ones. It was found that a pulse-like function yields the best fit for the lateral gas saturation profile. This strange behaviour of a relatively sharp saturation transition is in contradiction to the widely anticipated picture of a smooth Gaussian-like transition, which is obtained by the continuum approach. Based on lab experiments, the proposed flow chart, and computer simulations the DGI-technology will be advanced and optimized at the field scale. A proper application of continuum models to direct gas injection should check, whether stable coherent flow is achieved; estimate the coherence length, and account for the channelized flow pattern by a realistic capillary pressure - saturation relationship. Further research is needed for modeling of direct gas injection to include appropriate stability criteria, the transition from coherent to incoherent flow, and bubble trapping. Geistlinger, H., Krauss, G., Lazik, D., and Luckner, L. (2006) Direct gas injection into saturated glass beads: transition from incoherent to coherent gas flow pattern. Water Resour. Res., 42 (7) W07403. Lazik, D., G. Krauss, H. Geistlinger, and H.-J. Vogel (2008) Multi-scale optical analyses of dynamic gas saturation during air sparging into glass beads, Transp. Porous Media. 74, 87-104.

Modeling of liquid and gas flows in the horizontal layer with evaporation

NASA Astrophysics Data System (ADS)

Lyulin, Yuri; Rezanova, Ekaterina

2017-10-01

Mathematical modeling of two-layer flows in the "ethanol-nitrogen" system on the basis of the exact solutions of a special type is carried out. The influence of the gas flow, temperature and Soret effect on the flow patterns and evaporating processes at the interface is investigated. The results of comparison of the experimental and theoretical data are presented; the dependence of the evaporation intensity at interface of the gas flow rate and temperature is studied.

Method and apparatus for enhancing reactor air-cooling system performance

DOEpatents

Hunsbedt, A.

1996-03-12

An enhanced decay heat removal system is disclosed for removing heat from the inert gas-filled gap space between the reactor vessel and the containment vessel of a liquid metal-cooled nuclear reactor. Multiple cooling ducts in flow communication with the inert gas-filled gap space are incorporated to provide multiple flow paths for the inert gas to circulate to heat exchangers which remove heat from the inert gas, thereby introducing natural convection flows in the inert gas. The inert gas in turn absorbs heat directly from the reactor vessel by natural convection heat transfer. 6 figs.

Magnetic resonance imaging of convection in laser-polarized xenon

NASA Technical Reports Server (NTRS)

Mair, R. W.; Tseng, C. H.; Wong, G. P.; Cory, D. G.; Walsworth, R. L.

2000-01-01

We demonstrate nuclear magnetic resonance (NMR) imaging of the flow and diffusion of laser-polarized xenon (129Xe) gas undergoing convection above evaporating laser-polarized liquid xenon. The large xenon NMR signal provided by the laser-polarization technique allows more rapid imaging than one can achieve with thermally polarized gas-liquid systems, permitting shorter time-scale events such as rapid gas flow and gas-liquid dynamics to be observed. Two-dimensional velocity-encoded imaging shows convective gas flow above the evaporating liquid xenon, and also permits the measurement of enhanced gas diffusion near regions of large velocity variation.

Internally-cooled centrifugal compressor with cooling jacket formed in the diaphragm

DOEpatents

Moore, James J.; Lerche, Andrew H.; Moreland, Brian S.

2014-08-26

An internally-cooled centrifugal compressor having a shaped casing and a diaphragm disposed within the shaped casing having a gas side and a coolant side so that heat from a gas flowing though the gas side is extracted via the coolant side. An impeller disposed within the diaphragm has a stage inlet on one side and a stage outlet for delivering a pressurized gas to a downstream connection. The coolant side of the diaphragm includes at least one passageway for directing a coolant in a substantially counter-flow direction from the flow of gas through the gas side.

Numerical simulations of the Macondo well blowout reveal strong control of oil flow by reservoir permeability and exsolution of gas

PubMed Central

Oldenburg, Curtis M.; Freifeld, Barry M.; Pruess, Karsten; Pan, Lehua; Finsterle, Stefan; Moridis, George J.

2012-01-01

In response to the urgent need for estimates of the oil and gas flow rate from the Macondo well MC252-1 blowout, we assembled a small team and carried out oil and gas flow simulations using the TOUGH2 codes over two weeks in mid-2010. The conceptual model included the oil reservoir and the well with a top boundary condition located at the bottom of the blowout preventer. We developed a fluid properties module (Eoil) applicable to a simple two-phase and two-component oil-gas system. The flow of oil and gas was simulated using T2Well, a coupled reservoir-wellbore flow model, along with iTOUGH2 for sensitivity analysis and uncertainty quantification. The most likely oil flow rate estimated from simulations based on the data available in early June 2010 was about 100,000 bbl/d (barrels per day) with a corresponding gas flow rate of 300 MMscf/d (million standard cubic feet per day) assuming the well was open to the reservoir over 30 m of thickness. A Monte Carlo analysis of reservoir and fluid properties provided an uncertainty distribution with a long tail extending down to 60,000 bbl/d of oil (170 MMscf/d of gas). The flow rate was most strongly sensitive to reservoir permeability. Conceptual model uncertainty was also significant, particularly with regard to the length of the well that was open to the reservoir. For fluid-entry interval length of 1.5 m, the oil flow rate was about 56,000 bbl/d. Sensitivity analyses showed that flow rate was not very sensitive to pressure-drop across the blowout preventer due to the interplay between gas exsolution and oil flow rate. PMID:21730177

Regeneration of an aqueous solution from an acid gas absorption process by matrix stripping

DOEpatents

Rochelle, Gary T [Austin, TX; Oyenekan, Babatunde A [Katy, TX

2011-03-08

Carbon dioxide and other acid gases are removed from gaseous streams using aqueous absorption and stripping processes. By replacing the conventional stripper used to regenerate the aqueous solvent and capture the acid gas with a matrix stripping configuration, less energy is consumed. The matrix stripping configuration uses two or more reboiled strippers at different pressures. The rich feed from the absorption equipment is split among the strippers, and partially regenerated solvent from the highest pressure stripper flows to the middle of sequentially lower pressure strippers in a "matrix" pattern. By selecting certain parameters of the matrix stripping configuration such that the total energy required by the strippers to achieve a desired percentage of acid gas removal from the gaseous stream is minimized, further energy savings can be realized.

Multi-Scale Long-Range Magnitude and Sign Correlations in Vertical Upward Oil-Gas-Water Three-Phase Flow

NASA Astrophysics Data System (ADS)

Zhao, An; Jin, Ning-de; Ren, Ying-yu; Zhu, Lei; Yang, Xia

2016-01-01

In this article we apply an approach to identify the oil-gas-water three-phase flow patterns in vertical upwards 20 mm inner-diameter pipe based on the conductance fluctuating signals. We use the approach to analyse the signals with long-range correlations by decomposing the signal increment series into magnitude and sign series and extracting their scaling properties. We find that the magnitude series relates to nonlinear properties of the original time series, whereas the sign series relates to the linear properties. The research shows that the oil-gas-water three-phase flows (slug flow, churn flow, bubble flow) can be classified by a combination of scaling exponents of magnitude and sign series. This study provides a new way of characterising linear and nonlinear properties embedded in oil-gas-water three-phase flows.

Biological hydrogen production by Clostridium acetobutylicum in an unsaturated flow reactor.

PubMed

Zhang, Husen; Bruns, Mary Ann; Logan, Bruce E

2006-02-01

A mesophilic unsaturated flow (trickle bed) reactor was designed and tested for H2 production via fermentation of glucose. The reactor consisted of a column packed with glass beads and inoculated with a pure culture (Clostridium acetobutylicum ATCC 824). A defined medium containing glucose was fed at a flow rate of 1.6 mL/min (0.096 L/h) into the capped reactor, producing a hydraulic retention time of 2.1 min. Gas-phase H2 concentrations were constant, averaging 74 +/- 3% for all conditions tested. H2 production rates increased from 89 to 220 mL/hL of reactor when influent glucose concentrations were varied from 1.0 to 10.5 g/L. Specific H2 production rate ranged from 680 to 1270 mL/g glucose per liter of reactor (total volume). The H2 yield was 15-27%, based on a theoretical limit by fermentation of 4 moles of H2 from 1 mole of glucose. The major fermentation by-products in the liquid effluent were acetate and butyrate. The reactor rapidly (within 60-72 h) became clogged with biomass, requiring manual cleaning of the system. In order to make long-term operation of the reactor feasible, biofilm accumulation in the reactor will need to be controlled through some process such as backwashing. These tests using an unsaturated flow reactor demonstrate the feasibility of the process to produce high H2 gas concentrations in a trickle-bed type of reactor. A likely application of this reactor technology could be H2 gas recovery from pre-treatment of high carbohydrate-containing wastewaters.

Measurements of the Ice Water Content of Cirrus in the Tropics and Subtropics. I; Instrument Details and Validation

NASA Technical Reports Server (NTRS)

Weinstock, E. M.; Smith, J. B.; Sayres, D.; Pittman, J. V.; Allen, N.; Demusz, J.; Greenberg, M.; Rivero, M.; Anderson, J. G.

2003-01-01

We describe an instrument mounted in a pallet on the NASA WB-57 aircraft that is designed to measure the sum of gas phase and solid phase water, or total water, in cirrus clouds. Using an isokinetic inlet, a 600-watt heater mounted directly in the flow, and Lyman-alpha photofragment fluorescence technique for detection, accurate measurements of total water have been made over almost three orders of magnitude. Isokinetic flow is achieved with an actively controlled roots pump by referencing aircraft pressure, temperature, and true air speed, together with instrument flow velocity, temperature, and pressure. During CRYSTAL FACE, the instrument operated at duct temperatures sufficiently warm to completely evaporate particles up to 150 microns diameter. In flight diagnostics, intercomparison with water measured by absorption in flight, as well as intercomparisons in clear air with water vapor measured by the Harvard water vapor instrument and the JPL infrared tunable diode laser hygrometer validate the detection sensitivity of the instrument and illustrate minimal hysteresis from instrument surfaces. The simultaneous measurement of total water and water vapor in cirrus clouds yields their ice water content.

Development of braided rope seals for hypersonic engine applications: Flow modeling

NASA Technical Reports Server (NTRS)

Mutharasan, Rajakkannu; Steinetz, Bruce M.; Tao, Xiaoming; Du, Guang-Wu; Ko, Frank

1992-01-01

A new type of engine seal is being developed to meet the needs of advanced hypersonic engines. A seal braided of emerging high temperature ceramic fibers comprised of a sheath-core construction was selected for study based on its low leakage rates. Flexible, low-leakage, high temperature seals are required to seal the movable engine panels of advanced ramjet-scramjet engines either preventing potentially dangerous leakage into backside engine cavities or limiting the purge coolant flow rates through the seals. To predict the leakage through these flexible, porous seal structures new analytical flow models are required. Two such models based on the Kozeny-Carman equations are developed herein and are compared to experimental leakage measurements for simulated pressure and seal gap conditions. The models developed allow prediction of the gas leakage rate as a function of fiber diameter, fiber packing density, gas properties, and pressure drop across the seal. The first model treats the seal as a homogeneous fiber bed. The second model divides the seal into two homogeneous fiber beds identified as the core and the sheath of the seal. Flow resistances of each of the main seal elements are combined to determine the total flow resistance. Comparisons between measured leakage rates and model predictions for seal structures covering a wide range of braid architectures show good agreement. Within the experimental range, the second model provides a prediction within 6 to 13 percent of the flow for many of the cases examined. Areas where future model refinements are required are identified.

DWPF Melter Off-Gas Flammability Assessment for Sludge Batch 9

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

Choi, A. S.

2016-07-11

The slurry feed to the Defense Waste Processing Facility (DWPF) melter contains several organic carbon species that decompose in the cold cap and produce flammable gases that could accumulate in the off-gas system and create potential flammability hazard. To mitigate such a hazard, DWPF has implemented a strategy to impose the Technical Safety Requirement (TSR) limits on all key operating variables affecting off-gas flammability and operate the melter within those limits using both hardwired/software interlocks and administrative controls. The operating variables that are currently being controlled include; (1) total organic carbon (TOC), (2) air purges for combustion and dilution, (3)more » melter vapor space temperature, and (4) feed rate. The safety basis limits for these operating variables are determined using two computer models, 4-stage cold cap and Melter Off-Gas (MOG) dynamics models, under the baseline upset scenario - a surge in off-gas flow due to the inherent cold cap instabilities in the slurry-fed melter.« less

Scaling analysis of gas-liquid two-phase flow pattern in microgravity

NASA Technical Reports Server (NTRS)

Lee, Jinho

1993-01-01

A scaling analysis of gas-liquid two-phase flow pattern in microgravity, based on the dominant physical mechanism, was carried out with the goal of predicting the gas-liquid two-phase flow regime in a pipe under conditions of microgravity. The results demonstrated the effect of inlet geometry on the flow regime transition. A comparison of the predictions with existing experimental data showed good agreement.

Effects of particle mixing and scattering in the dusty gas flow through moving and stationary cascades of airfoils

NASA Astrophysics Data System (ADS)

Tsirkunov, Yu. M.; Romanyuk, D. A.; Panfilov, S. V.

2011-10-01

Time-dependent two-dimensional (2D) flow of dusty gas through a set of two cascades of airfoils (blades) has been studied numerically. The first cascade was assumed to move (rotor) and the second one to be immovable (stator). Such a flow can be considered, in some sense, as a flow in the inlet stage of a turbomachine, for example, in the inlet compressor of an aircraft turbojet engine. Dust particle concentration was assumed to be very low, so that the interparticle collisions and the effect of the dispersed phase on the carrier gas were negligible. Flow of the carrier gas was described by full Navier-Stokes equations. In calculations of particle motion, the particles were considered as solid spheres. The particle drag force, transverse Magnus force, and damping torque were taken into account in the model of gas-particle interaction. The impact interaction of particles with blades was considered as frictional and partly elastic. The effects of particle size distribution and particle scattering in the course of particle-blade collisions were investigated. Flow fields of the carrier gas and flow patterns of the particle phase were obtained and discussed.

Quantitative tomographic measurements of opaque multiphase flows

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

GEORGE,DARIN L.; TORCZYNSKI,JOHN R.; SHOLLENBERGER,KIM ANN

2000-03-01

An electrical-impedance tomography (EIT) system has been developed for quantitative measurements of radial phase distribution profiles in two-phase and three-phase vertical column flows. The EIT system is described along with the computer algorithm used for reconstructing phase volume fraction profiles. EIT measurements were validated by comparison with a gamma-densitometry tomography (GDT) system. The EIT system was used to accurately measure average solid volume fractions up to 0.05 in solid-liquid flows, and radial gas volume fraction profiles in gas-liquid flows with gas volume fractions up to 0.15. In both flows, average phase volume fractions and radial volume fraction profiles from GDTmore » and EIT were in good agreement. A minor modification to the formula used to relate conductivity data to phase volume fractions was found to improve agreement between the methods. GDT and EIT were then applied together to simultaneously measure the solid, liquid, and gas radial distributions within several vertical three-phase flows. For average solid volume fractions up to 0.30, the gas distribution for each gas flow rate was approximately independent of the amount of solids in the column. Measurements made with this EIT system demonstrate that EIT may be used successfully for noninvasive, quantitative measurements of dispersed multiphase flows.« less

Gas and Oil Flow through Wellbore Flaws

NASA Astrophysics Data System (ADS)

Hatambeigi, M.; Anwar, I.; Reda Taha, M.; Bettin, G.; Chojnicki, K. N.; Stormont, J.

2017-12-01

We have measured gas and oil flow through laboratory samples that represent two important potential flow paths in wellbores associated with the Strategic Petroleum Reserve (SPR): cement-steel interfaces (microannuli) and cement fractures. Cement fractures were created by tensile splitting of cement cores. Samples to represent microannuli were created by placing thin steel sheets within split cement cores so flow is channeled along the cement-steel interface. The test sequence included alternating gas and oil flow measurements. The test fluids were nitrogen and silicone oil with properties similar to a typical crude oil stored in the SPR. After correcting for non-linear (inertial) flow when necessary, flows were interpreted as effective permeability and hydraulic aperture using the cubic law. For both samples with cement fractures and those with cement-steel interfaces, initial gas and oil permeabilities were comparable. Once saturated with oil, a displacement pressure had to be overcome to establish gas flow through a sample, and the subsequent gas permeability were reduced by more than 50% compared to its initial value. Keywords: wellbore integrity, leakage, fracture, microannulus, SPR. Sandia National Laboratories is a multi-mission laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of NTESS/Honeywell, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. SAND2017-8168 A

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

Pak, S.; Sites, J.R.

A Kaufman-type broad beam ion source, used for sputtering and etching purposes, has been operated with Ar, Kr,O/sub 2/ and N/sub 2/ gas inputs over a wide range of beam energies (200-1200 eV) and gas flow rates (1-10 sccm). The maximum ion beam current density for each gas saturates at about 2.5 mA/sq. cm. as gas flow is increased. The discharge threshold voltage necessary to produce a beam and the beam efficiency (beam current/molecular current), however, varied considerably. Kr had the lowest threshold and highest efficiency, Ar next, then N/sub 2/ and O/sub 2/. The ion beam current varied onlymore » weakly with beam energy for low gas flow rates, but showed a factor of two increase when the gas flow was higher.« less

A parametric study of the microwave plasma-assisted combustion of premixed ethylene/air mixtures

NASA Astrophysics Data System (ADS)

Fuh, Che A.; Wu, Wei; Wang, Chuji

2017-11-01

A parametric study of microwave argon plasma assisted combustion (PAC) of premixed ethylene/air mixtures was carried out using visual imaging, optical emission spectroscopy and cavity ringdown spectroscopy as diagnostic tools. The parameters investigated included the plasma feed gas flow rate, the plasma power, the fuel equivalence ratio and the total flow rate of the fuel/air mixture. The combustion enhancement effects were characterized by the minimum ignition power, the flame length and the fuel efficiency of the combustor. It was found that: (1) increasing the plasma feed gas flow rate resulted in a decrease in the flame length, an increase in the minimum ignition power for near stoichiometric fuel equivalence ratios and a corresponding decrease in the minimum ignition power for ultra-lean and rich fuel equivalence ratios; (2) at a constant plasma power, increasing the total flow rate of the ethylene/air mixture from 1.0 slm to 1.5 slm resulted in an increase in the flame length and a reduction in the fuel efficiency; (3) increasing the plasma power resulted in a slight increase in flame length as well as improved fuel efficiency with fewer C2(d) and CH(A) radicals present downstream of the flame; (4) increasing the fuel equivalence ratio caused an increase in flame length but at a reduced fuel efficiency when plasma power was kept constant; and (5) the ground state OH(X) number density was on the order of 1015 molecules/cm3 and was observed to drop downstream along the propagation axis of the flame at all parameters investigated. Results suggest that each of the parameters independently influences the PAC processes.

Flow and criticality in the open cycle gas core.

NASA Technical Reports Server (NTRS)

Kunze, J. F.; Lofthouse, J. H.

1971-01-01

A series of flowing gas experiments using air, argon, and freon has been conducted in Idaho. The purpose is to study methods of obtaining flow patterns which would create maximum possible system reactivity consistent with an acceptably low uranium to coolant-gas loss ratio. These have been conducted on both ?two-dimensional' and truly three-dimensional spherical configurations of diameters 18 to 42 inches. The larger diameter is that proposed for a minimum cost flowing gas critical experiment, and the size extremes make extrapolations to the large 6 and 8 foot diameter configurations more reliable. Results show that large enough inner gas (fuel) volume fractions can be achieved to attain criticality.

Gas flow means for improving efficiency of exhaust hoods

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

Gadgil, A.J.

1994-01-11

Apparatus is described for inhibiting the flow of contaminants in an exhaust enclosure toward an individual located adjacent an opening into the exhaust enclosure by providing a gas flow toward a source of contaminants from a position in front of an individual to urge said contaminants away from the individual toward a gas exit port. The apparatus comprises a gas manifold which may be worn by a person as a vest. The manifold has a series of gas outlets on a front face thereof facing away from the individual and toward the contaminants to thereby provide a flow of gasmore » from the front of the individual toward the contaminants. 15 figures.« less

TiCl4 as a source of TiO2 particles for laser anemometry measurements in hot gas

NASA Technical Reports Server (NTRS)

Weikle, Donald H.; Seasholtz, Richard G.; Oberle, Lawrence G.

1990-01-01

A method of reacting TiCl4 with water saturated gaseous nitrogen (GN2) at the entrance into a high temperature gas flow is described. The TiO2 particles formed are then entrained in the gas flow and used as seed particles for making laser anemometry (LA) measurements of the flow velocity distribution in the hot gas. Scanning electron microscope photographs of the TiO2 particles are shown. Data rate of the LA processor was measured to determine the amount of TiO2 formed. The TiCl4 and mixing gas flow diagram is shown. This work was performed in an open jet burner.

Dynamic measurement of temperature, velocity, and density in hot jets using Rayleigh scattering

NASA Astrophysics Data System (ADS)

Mielke, Amy F.; Elam, Kristie A.

2009-10-01

A molecular Rayleigh scattering technique is utilized to measure gas temperature, velocity, and density in unseeded gas flows at sampling rates up to 10 kHz, providing fluctuation information up to 5 kHz based on the Nyquist theorem. A high-power continuous-wave laser beam is focused at a point in an air flow field and Rayleigh scattered light is collected and fiber-optically transmitted to a Fabry-Perot interferometer for spectral analysis. Photomultiplier tubes operated in the photon counting mode allow high-frequency sampling of the total signal level and the circular interference pattern to provide dynamic density, temperature, and velocity measurements. Mean and root mean square velocity, temperature, and density, as well as power spectral density calculations, are presented for measurements in a hydrogen-combustor heated jet facility with a 50.8-mm diameter nozzle at NASA John H. Glenn Research Center at Lewis Field. The Rayleigh measurements are compared with particle image velocimetry data and computational fluid dynamics predictions. This technique is aimed at aeronautics research related to identifying noise sources in free jets, as well as applications in supersonic and hypersonic flows where measurement of flow properties, including mass flux, is required in the presence of shocks and ionization occurrence.

Superamphiphobic Silicon-Nanowire-Embedded Microsystem and In-Contact Flow Performance of Gas and Liquid Streams.

PubMed

Ko, Dong-Hyeon; Ren, Wurong; Kim, Jin-Oh; Wang, Jun; Wang, Hao; Sharma, Siddharth; Faustini, Marco; Kim, Dong-Pyo

2016-01-26

Gas and liquid streams are invariably separated either by a solid wall or by a membrane for heat or mass transfer between the gas and liquid streams. Without the separating wall, the gas phase is present as bubbles in liquid or, in a microsystem, as gas plugs between slugs of liquid. Continuous and direct contact between the two moving streams of gas and liquid is quite an efficient way of achieving heat or mass transfer between the two phases. Here, we report a silicon nanowire built-in microsystem in which a liquid stream flows in contact with an underlying gas stream. The upper liquid stream does not penetrate into the lower gas stream due to the superamphiphobic nature of the silicon nanowires built into the bottom wall, thereby preserving the integrity of continuous gas and liquid streams, although they are flowing in contact. Due to the superamphiphobic nature of silicon nanowires, the microsystem provides the best possible interfacial mass transfer known to date between flowing gas and liquid phases, which can achieve excellent chemical performance in two-phase organic syntheses.

40 CFR 63.1415 - Monitoring requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... recorder shall be located at the scrubber influent for liquid flow. Gas stream flow shall be determined using one of the following procedures: (A) The owner or operator may determine gas stream flow using the... regulations in 40 CFR parts 264 through 266 that required a determination of the liquid to gas (L/G) ratio...

40 CFR 63.1415 - Monitoring requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... recorder shall be located at the scrubber influent for liquid flow. Gas stream flow shall be determined using one of the following procedures: (A) The owner or operator may determine gas stream flow using the... regulations in 40 CFR parts 264 through 266 that required a determination of the liquid to gas (L/G) ratio...

Catalytic Microtube Rocket Igniter

NASA Technical Reports Server (NTRS)

Schneider, Steven J.; Deans, Matthew C.

2011-01-01

Devices that generate both high energy and high temperature are required to ignite reliably the propellant mixtures in combustion chambers like those present in rockets and other combustion systems. This catalytic microtube rocket igniter generates these conditions with a small, catalysis-based torch. While traditional spark plug systems can require anywhere from 50 W to multiple kW of power in different applications, this system has demonstrated ignition at less than 25 W. Reactants are fed to the igniter from the same tanks that feed the reactants to the rest of the rocket or combustion system. While this specific igniter was originally designed for liquid methane and liquid oxygen rockets, it can be easily operated with gaseous propellants or modified for hydrogen use in commercial combustion devices. For the present cryogenic propellant rocket case, the main propellant tanks liquid oxygen and liquid methane, respectively are regulated and split into different systems for the individual stages of the rocket and igniter. As the catalyst requires a gas phase for reaction, either the stored boil-off of the tanks can be used directly or one stream each of fuel and oxidizer can go through a heat exchanger/vaporizer that turns the liquid propellants into a gaseous form. For commercial applications, where the reactants are stored as gases, the system is simplified. The resulting gas-phase streams of fuel and oxidizer are then further divided for the individual components of the igniter. One stream each of the fuel and oxidizer is introduced to a mixing bottle/apparatus where they are mixed to a fuel-rich composition with an O/F mass-based mixture ratio of under 1.0. This premixed flow then feeds into the catalytic microtube device. The total flow is on the order of 0.01 g/s. The microtube device is composed of a pair of sub-millimeter diameter platinum tubes connected only at the outlet so that the two outlet flows are parallel to each other. The tubes are each approximately 10 cm long and are heated via direct electric resistive heating. This heating brings the gasses to their minimum required ignition temperature, which is lower than the auto-thermal ignition temperature, and causes the onset of both surface and gas phase ignition producing hot temperatures and a highly reacting flame. The combustion products from the catalytic tubes, which are below the melting point of platinum, are injected into the center of another combustion stage, called the primary augmenter. The reactants for this combustion stage come from the same source but the flows of non-premixed methane and oxygen gas are split off to a secondary mixing apparatus and can be mixed in a near-stoichiometric to highly lean mixture ratio. The primary augmenter is a component that has channels venting this mixed gas to impinge on each other in the center of the augmenter, perpendicular to the flow from the catalyst. The total crosssectional area of these channels is on a similar order as that of the catalyst. The augmenter has internal channels that act as a manifold to distribute equally the gas to the inward-venting channels. This stage creates a stable flame kernel as its flows, which are on the order of 0.01 g/s, are ignited by the combustion products of the catalyst. This stage is designed to produce combustion products in the flame kernel that exceed the autothermal ignition temperature of oxygen and methane.

3D motion picture of transparent gas flow by parallel phase-shifting digital holography

NASA Astrophysics Data System (ADS)

Awatsuji, Yasuhiro; Fukuda, Takahito; Wang, Yexin; Xia, Peng; Kakue, Takashi; Nishio, Kenzo; Matoba, Osamu

2018-03-01

Parallel phase-shifting digital holography is a technique capable of recording three-dimensional (3D) motion picture of dynamic object, quantitatively. This technique can record single hologram of an object with an image sensor having a phase-shift array device and reconstructs the instantaneous 3D image of the object with a computer. In this technique, a single hologram in which the multiple holograms required for phase-shifting digital holography are multiplexed by using space-division multiplexing technique pixel by pixel. We demonstrate 3D motion picture of dynamic and transparent gas flow recorded and reconstructed by the technique. A compressed air duster was used to generate the gas flow. A motion picture of the hologram of the gas flow was recorded at 180,000 frames/s by parallel phase-shifting digital holography. The phase motion picture of the gas flow was reconstructed from the motion picture of the hologram. The Abel inversion was applied to the phase motion picture and then the 3D motion picture of the gas flow was obtained.