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At least 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

The Most Distant H i Galaxies Discovered by the 500 m Dish FAST

Abstract Neutral hydrogen (Hi) is the primary component of the cool interstellar medium (ISM) and is the reservoir of fuel for star formation. Owing to the sensitivity of existing radio telescopes, our understanding of the evolution of the ISM in galaxies remains limited, as it is based on only a few hundred galaxies detected in Hibeyond the local Universe. With the high sensitivity of the Five-hundred-meter Aperture Spherical radio Telescope (FAST), we carried out a blind Hisearch, the FAST Ultra-Deep Survey, which extends to redshifts up to 0.42 and a sensitivity of 50μJy beam −1 . Here, we report the first discovery of six galaxies in Hi atz> 0.38. For these galaxies, the FAST angular resolution of ∼4′ corresponds to a mean linear size of ∼ 1.3 h 70 − 1 Mpc. These galaxies are among the most distant Hiemission detections known, with one having the most massive Hicontent ( 10 10.93 ± 0.04 h 70 − 2 M ⊙ ). Using recent data from the DESI survey and new observations with the Hale, Big Telescope Alt-azimuth, and Keck telescopes, optical counterparts are detected for all galaxies within the 3σpositional uncertainty ( 0.5 h 70 − 1 Mpc) and 200 km s −1 in recession velocity. Assuming that the dominant source of Hiis the identified optical counterpart, we find evidence of evolution in the Hicontent of galaxies over the last 4.2 Gyr. Our new high-redshift Higalaxy sample provides the opportunity to better investigate the evolution of cool gas in galaxies. A larger sample size in the future will allow us to refine our knowledge of the formation and evolution of galaxies.

Astronomy & Astrophysics↗
NASA NTRS1991

Implanted 3He, 4He, and Xe in further studies of diamonds from Western Australia

In measurements of the noble gases in additional samples of diamonds from the Argyle and Ellendale lamproites in Western Australia we have failed to encounter any neon-rich stones such as showed solar-like isotopic compositions in earlier work. No neon was detected above the relatively high blank levels in our glass apparatus. White and brown diamonds showed no differences in noble gas content, nor did samples segregated by the color of long-wave UF fluorescence. The rare gas patterns in the 1.2 Ga Argyle pipe are largely consistent with implanted 3He, 4He, and fissiogenic Xe from U/Th in the matrix rock in which the diamonds have been stored for so long. These implanted species are absent in diamonds from the much younger (approximately 20 Ma) Ellendale pipe. We give implantation formulae for several models of inhomogeneously distributed U/Th. Differences in 3He content between pipe and alluvial Argyle samples are consistent with expected cosmogenic production in the latter. An expanded data base for helium and carbon isotopic data on the same samples supports a negative [4He]-delta 13C correlation seen earlier in work from our group, but if the Argyle samples, which contain light carbon, are corrected for implanted 4He, the correlation is considerably weakened. We no longer see an earlier 3He/4He-delta 13C correlation.

NASA Discipline Number 52-10↗
NASA NTRS1992

Hydrogen leak detection in the Space Shuttle

This study focuses on a helium gas jet flowing into room air. Measurements of helium concentration and velocity in the jet-air mixture are reported. The objective is to learn about jet characteristics so that dynamically similar hydrogen leaks may be located in the Space Shuttle. The hazardous gas detection system (HGDS) in the mobile launch pad uses mass spectrometers to monitor the shuttle environment for leaks. The mass spectrometers are fed by long sample tubes which draw gas from the payload bay, mid body, aft engine compartment and external tank. The overall purpose of this study is to improve the HGDS especially in its potential for locating hydrogen leaks. A rapid-response leak detection experiment was designed, built, and tested, following on the work done in this program last summer. The apparatus included a Perkin Elmer MGA-1200 mass spectrometer and air velocity transducer, both monitored by a Macintosh IIFX computer using LabVIEW software. A jet of helium flowing into the lab air simulated a gas leak. Steady helium or hydrogen-nitrogen jets were logged for concentration and velocity, and the power spectral density of each was computed. Last year, large eddies and vortices were visually seen with Schlieren imaging, and they were detected in the time plots of the various instruments. The response time of the MGA-1200 was found in the range of 0.05 to 0.1 sec. Pulsed concentration waves were clearly detected at 25 cycles per sec by spectral analysis of MGA data. No peaks were detected in the power spectrum, so in the present study, 10 Hz bandwidth-averaged power levels were examined at regular frequency intervals. The practical consequences of last year's study are as follows: sampling frequency should be increased above the present rate of 1 sample per second so that transients could be observed and analyzed with frequency response methods. Many more experiments and conditions were observed in this second summer, including the effects of orifice diameter, jet velocity, sample tube design, radial effects, vertical flow, and low hydrogen concentrations (1 percent). A frequent observation was that the power spectrum, calculated from the Fourier transform of concentration fluctuations, gives a separate piece of information from concentration. Many of the tests suggest that power is high where mixing occurs at the helium-air interface. This fact is apparently independent of the concentration level, which could be high or low, but depends on the sample location relative to the jet (leak) origin, whereas high concentration may be due to a strong leak far away or a small leak close to the sample tube. If the power is low for any concentration level, this would signify helium is arriving at the sample tube by diffusion, not chaotic mixing caused by the jet interaction with air. The practical result is to propose a modification of the HGDL mass spectrometer data sampling and software so that sampling rates could be capable of observing at least 25 Hz fluctuations.

Barile, Ronald G↗
NASA NTRS2017

Sample Curation in Support of the OSIRIS-REx Asteroid Sample Return Mission

The OSIRIS-REx asteroid sample return mission launched to asteroid Bennu Sept. 8, 2016. The spacecraft will arrive at Bennu in late 2019, orbit and map the asteroid, and perform a touch and go (TAG) sampling maneuver in July 2020. After sample is stowed and confirmed the spacecraft will return to Earth, and the sample return capsule (SRC) will land in Utah in September 2023. Samples will be recovered from Utah [2] and then transported and stored in a new sample cleanroom at NASA Johnson Space Center in Houston [3]. The materials curated for the mission are described here. a) Materials Archive and Witness Plate Collection: The SRC and TAGSAM were built between March 2014 and Summer of 2015, and instruments (OTES,OVIRS, OLA, OCAMS, REXIS) were integrated from Summer 2015 until May 2016. A total of 395 items were received for the materials archive at NASA-JSC, with archiving finishing ~30 days after launch (with the final archived items being related to launch operations)[4]. The materials fall into several general categories including metals (stainless steel, aluminum, titanium alloys, brass and BeCu alloy), epoxies, paints, polymers, lubricants, non-volatile-residue samples (NVR), sapphire, and various miscellaneous materials. All through the ATLO process (from March 2015 until late August 2016) contamination knowledge witness plates (Si wafer and Al foil) were deployed in the various cleanrooms in Denver and KSC to provide an additional record of particle counts and volatiles that is archived for current and future scientific studies. These plates were deployed in roughly monthly increments with each unit containing 4 Si wafers and 4 Al foils. We archived 128 individual witness plates (64 Si wafers and 64 Al foils); one of each witness plate (Si and Al) was analyzed immediately by the science team after archiving, while the remaining 3 of each are archived indefinitely. Information about each material archived is stored in an extensive database at NASA-JSC, and key summary information for each will be presented in an online catalog. b) Bulk Asteroid sample: The Touch and Go Sampling Mechanism (TAGSAM) head will contain up to 1.5 kg of asteroid material. Upon return to Earth, the TAGSAM head with the sample canister will be subjected to a nitrogen purge and then opened in a nitrogen cabinet in Houston. Once the TAGSAM head is removed from the canister, it will be dis-assembled slowly and carefully under nitrogen until the sample can be removed for processing in a dedicated nitrogen glovebox. Bennu surface samples are expected to be sub-cm sized, based on thermal infrared and radar polarization ratio measurements [1]. The upper limit on material collected by the TAGSAM head is ~2 cm. Therefore, we will be prepared to handle, subdivide, and characterize materials of a wide grain size (from ~10 m to 2 cm), and for both organic (UV fluorescence) and inorganic (SEM, FTIR, optical) properties. Representative portions of the bulk sample will be prepared for JAXA (0.5 %; see also [5]) and Canadian Space Agency (4%), with the remaining divided between the science team (<25%) and archived for future studies (NASA) (>75%). c) Contact Pad samples: The base of the TAGSAM head contains 24 contact pads that are designed to trap the upper surface layer of material and thus offer an opportunity to study asteroid samples that have resided at the very top surface of the regolith. Asteroid material is trapped on the pads in spring steel Velcro hooks, and material will have to be removed from these pads by curation specialists in the lab. d) Hardware: Some canister and SRC hardware items will contain information that will be important to understanding the collected samples, including the canister gas filter, temperature strips, flight witness plates, and the TAGSAM and canister parts that might have adhering dust grains. Some challenges remaining for both bulk sample and contact pad samples include: i) working with intermediate size range (200 to 500 micron) samples - a size range NASA has not previously worked in such detail; ii) techniques for removal of contact pad material from the spring steel hooks, iii) static electrical effects of dust sized particles during sample handling and curation is likely to be significant, and iv) the TAGSAM head and associated canister hardware will undoubtedly be coated with fine adhering dust grains from Bennu. In the case of collection of a large bulk sample mass, the adhering dust grains may be of lower priority. If a small sample mass is returned, the adhering dust may attain a higher priority, so recovery of adhering dust grains is an additional challenge to consider. In the year leading up to sample return we plan a variety of sample handling rehearsals that will enables the curation team to be prepared for many new aspects posed by this sample suite.

Righter, Kevin↗
DOE OSTI2025

In situ Gas Cell TEM Investigation of Nanoporous and Zeolite-based Nanocatalysts

A crucial application of in situ transmission electron microscopy is the understanding of nanocatalysts and the effect of the environment on their structure. Pre-treatments, such as calcination or annealing, can dramatically impact the catalytic properties by modifying the morphology and composition of nanostructures. Zeolites and nanoporous structures are particularly sensitive to reactive environments as the porosity or the chemical state can substantially change during the interaction with gases at elevated temperatures.[1] For instance, it has been shown that heating in air causes redispersion of sintered Cu clusters on zeolite, improving the catalytic properties.[2] These observations are possible though innovative in situ TEM gas holders, where the samples are enclosed into a small cell with SiNx windows, isolating the reactive environment from the rest of the column. [3] Here, we present in situ gas cell experiments of sensitive nanoporous structure and zeolite-based nanocatalysts. Scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy were used to understand migration of Al during calcination. In situ diagnostics also help distinguish Al as Bronsted sites, extra-framework Lewis sites, or bulk alumina. More broadly, in situ gas-heating TEM experiments are useful to determine chemical changes and modification of morphology of sensitive nanocatalysts upon pre-treatment (Figure 1).[4] Detailed in situ STEM and energy-dispersive X-ray spectroscopy (EDS) demonstrated compositional changes in nanoporous CuAlTi structures for hydrogen-deuterium exchange (H2-D2) reaction. Coarsening due to annealing at high temperature, a necessary steps for the preparation of catalysts, can be reversed by applying a redox cycle. Using the wide range of gases and temperature, the diagnostics are helpful to derive fundamental understanding of these catalysts at the atomic scale and also provide general guidelines to improve their design.

Foucher, Alexandre [ORNL] (ORCID:0000000150424002)↗
NASA NTRS2015

Analysis of Process Gases and Trace Contaminants in Membrane-Aerated Gaseous Effluent Streams.

In membrane-aerated biofilm reactors (MABRs), hollow fibers are used to supply oxygen to the biofilms and bulk fluid. A pressure and concentration gradient between the inner volume of the fibers and the reactor reservoir drives oxygen mass transport across the fibers toward the bulk solution, providing the fiber-adhered biofilm with oxygen. Conversely, bacterial metabolic gases from the bulk liquid, as well as from the biofilm, move opposite to the flow of oxygen, entering the hollow fiber and out of the reactor. Metabolic gases are excellent indicators of biofilm vitality, and can aid in microbial identification. Certain gases can be indicative of system perturbations and control anomalies, or potentially unwanted biological processes occurring within the reactor. In confined environments, such as those found during spaceflight, it is important to understand what compounds are being stripped from the reactor and potentially released into the crew cabin to determine the appropriateness or the requirement for additional mitigation factors. Reactor effluent gas analysis focused on samples provided from Kennedy Space Center's sub-scale MABRs, as well as Johnson Space Center's full-scale MABRs, using infrared spectroscopy and gas chromatography techniques. Process gases, such as carbon dioxide, oxygen, nitrogen, nitrogen dioxide, and nitrous oxide, were quantified to monitor reactor operations. Solid Phase Microextraction (SPME) GC-MS analysis was used to identify trace volatile compounds. Compounds of interest were subsequently quantified. Reactor supply air was examined to establish target compound baseline concentrations. Concentration levels were compared to average ISS concentration values and/or Spacecraft Maximum Allowable Concentration (SMAC) levels where appropriate. Based on a review of to-date results, current trace contaminant control systems (TCCS) currently on board the ISS should be able to handle the added load from bioreactor systems without the need for secondary mitigation.

Gaseous Effluent Streams↗
DOE OSTI2023

In-situ measurement of moist flue gas under high pressure using a nafion dryer and FTIR

The formation of the main flue gas species (NOx, SOx, CO2, and CO) in pressurized oxy-fuel combustion can be fundamentally different from oxy-fuel combustion at atmospheric pressure. To accurately obtain the concentration of these gas species in a pressurized oxy-fuel combustor, a gas measurement which maintains the sampling pressure is needed. Very few published studies have accomplished this, and never under the conditions reported herein. In this work, we fire PRB coal in a 100 kWth staged pressurized oxy-fuel combustor (SPOC) under a pressure 15 bara. We utilize a state-of-the-art FTIR (Thermo Scientific Nicolet iS20) with a novel high-pressure gas cell that is under process pressure to measure the in-situ flue-gas concentration in a sampled flow. However, water vapor can significantly interfere with the FTIR measurement, particularly under pressure. To address this problem, we have developed a high-pressure nafion dryer to selectively remove the water vapor from the flue gas while retaining the flue gas species. This approach can significantly increase the signal-noise ratio for the FTIR. By integrating the nafion dryer and the high-pressure gas cell, we were able to successfully measure flue gas species at system pressure with the FTIR.

Cheng, Mao↗
NASA NTRS1980

Stark cell optoacoustic detection of constituent gases in sample

An optoacoustic detector for gas analysis is implemented with Stark effect cell modulation for switching a beam in and out of coincidence with a spectral line of a constituent gas in order to eliminate the heating effect of laser energy in the cell as a source of background noise. By using a multiline laser, and linearly sweeping the DC bias voltage while exciting the cell with a multiline laser, it is possible to obtain a spectrum from which to determine the combinations of excited constituents and determine their concentrations in parts per million.

Margolis, J. S.↗
NASA NTRS1983

Measurements of stratospheric SO2 after the EL Chichon eruptions

Samples of stratospheric trace gases were obtained on eight flights of NASA high-altitude aircraft from April 16 through December 13, 1982. The sampling occurred at altitudes from 15 to 22 km, latitudes from 23 to 52 deg N, and longitudes from 108 to 130 deg W. The cryogenically concentrated samples were analyzed by gas chromatography for SO2, a primary precursor of the gas-to-particle conversion process. The measured mixing ratio of SO2 varied between 8 and 132 pptv. Evidence from aerosol measurements indicates that a few of our early samples may have been collected in the fringes of the volcanic cloud from El Chichon. Samples obtained on some later flights may have been from the eruption cloud but were taken at times when most of the volcanically injected SO2 should have been converted to H2SO4.

Vedder, J. F.↗
NASA NTRS1989

Modified Technique For Chemisorption Measurements

In measurements of chemisorption of CO on Pt/SnO2 catalyst observed that if small numbers of relatively large volumes of adsorbate gas are passed through sample, very little removal of CO detected. In these cases little or no CO has been chemisorbed on Pt/SnO2. Technique of using large number of small volumes of adsorbate gas to measure chemisorption applicable to many gas/material combinations other than CO on Pt/SnO2. Volume used chosen so that at least 10 percent of adsorbate gas removed during each exposure.

Schryer, David R.↗
NASA NTRS1985

Measurements of CCl3F, CCl2F2, CCl4, N2O and SF6 in the Northern Hemisphere stratosphere

An overview of the Department of Energy's High Altitude Sampling Program and some recent trace gas measurement results are presented. Analysis of whole air samples, collected in pressurized bottles, provides information on stratospheric inventories and distributions for CCl3F, CCl2F2, CCl4, N2O and SF6 in the Northern Hemisphere. Based on a linear regression analysis of the data the estimated mean Northern Hemisphere stratospheric concentration of each gas increased as follows: CCl3F changed from 54 to 142 p1/1 (4/74-11/83); CCl2F2 changed from 133 to 268 p1/1 (4/76-11/83); SF6 changed from 160 to 480 f1/1 (4/74-11/83); CC1, changed from 58 to 91 p1/1 (4/75-11/83); N2O changed from 246 to 261 n1/1 (4/76-11/83). The calculated mean Northern Hemisphere stratospheric concentrations of N2O, CCl3F, CCl2F2, and CCl4 after 1980 show larger than expected fluctuations with time. Recent volcanic activity may be a partial cause for these fluctuations through induced changes in stratospheric dynamical processes.

Leifer, R.↗
NASA NTRS2014

Performance of the Linear Ion Trap Mass Spectrometer for the Mars Organic Molecule Analyzer (MOMA) Investigation on the 2018 Exomars Rover

The 2018 ExoMars rover mission includes the Mars Organic Molecule Analyzer (MOMA) investigation. MOMA will examine the chemical composition of samples acquired from depths of up to two meters below the martian surface, where organics may be protected from degradation derived from cosmic radiation and/or oxidative chemical reactions. When combined with the complement of instruments in the rover's Pasteur Payload, MOMA has the potential to reveal the presence of a wide range of organics preserved in a variety of mineralogical environments, and to begin to understand the structural character and potential origin of those compounds. The MOMA investigation is led by the Max Planck Institute for Solar System Research (MPS) with the mass spectrometer subsystem provided by NASA GSFC. MOMA's linear ion trap mass spectrometer (ITMS) is designed to analyze molecular composition of: (i) gas evolved from pyrolyzed powder samples and separated in a gas chromatograph; and, (ii) ions directly desorbed from crushed solid samples at Mars ambient pressure, as enabled by a pulsed UV laser system, fast-actuating aperture valve and capillary ion inlet. Breadboard ITMS and associated electronics have been advanced to high end-to-end fidelity in preparation for flight hardware delivery to Germany in 2015.

linear ion trap mass spectrometer↗
DOE OSTI2022

SDSS IV MaNGA - star-formation driven biconical outflows in face-on galaxies

ABSTRACT We find 132 face-on and low inclination galaxies with central star formation driven biconical gas outflows (FSFB) in the SDSS MaNGA (Mapping Nearby Galaxies at APO) survey. The FSFB galaxies show either double peaked or broadened emission line profiles at their centres. The peak and maximum outflow velocities are 58 and 212 km s−1, respectively. The gas velocity dispersion reveals a mild dependence on the central star formation surface density compatible with models of gas dispersion powered by the Jeans instability in gas clumps or by gas turbulence dissipation. We estimate the gas outflow rate and conclude that the central gas depletion time does not depend on galactic mass. In turn, the ratio of the gas outflow rate to the gas consumption rate by the star formation is low in massive galaxies and high in low mass objects, while the star formation is a more rapid process of the gas consumption. We compare properties of the FSFB galaxies with a control sample of 375 comparison galaxies and find that the FSFB objects have high central concentration of star formation and also younger central stellar population with respect to their periphery. We analysed the environment of the galaxies and identified nearby satellites and elements of low surface brightness structure. We see that many tidal-enhanced features that can be assigned to early and intermediate stages of galactic interaction are much more frequent in the FSFB galaxies with respect to the comparison sample. We conclude that the gas should be replenished via the accretion from small satellites.

Bizyaev, D. (ORCID:000000023601133X)↗
NASA NTRS1983

In situ aircraft measurements of enhanced levels of N2O associated with thunderstorm lightning

A series of measurements of enhanced levels of atmospheric N2O associated with thunderstorm lightning are reported. The data were gathered by instrumentation on-board an aircraft operated as part of the NASA Storm Hazards Project. Air samples were taken both during storms and in clear conditions to have a basis for comparisons; sample bottles were filled at altitudes from 11,000-40,000 ft. Gas chromatography was employed for sample composition analyses, revealing clear air N2O concentrations of about 310 ppbv, while storm concentrations reached, for example, 490, 729, and 393 ppbv. Although the measurements did not precisely characterize the actual lightning contributions, the enhancements being present during electrically active storms did confirm that trace gases are produced by lightning. Calculations are presented to demonstrate that the 3 to greater than 12 keV X rays detected in storm clouds are of sufficient energy to drive the production of N2O from the reaction of metastable nitrogen with molecular oxygen.

Levine, J. S.↗
NASA NTRSDate not supplied

An Overview of Nuclear Thermal Rocket Element Environmental Simulator (NTREES) Capabilities, Upgrades, and Overlaps in Advanced Material Testing Areas

The Nuclear Thermal Rocket Element Environmental Simulator (NTREES) was designed to perform non-nuclear testing of nuclear thermal rocket (NTR) fuel elements and materials. NTREES can simulate the thermal hydraulic environment within the reactor of an NTR and has been leveraged to provide data on the thermochemical, thermomechanical and thermohydraulic performance of components and materials. Active upgrades to the NTREES facility include installing a DC power supply for DC powered joule heating, a supply gas chiller for a cryogenically cool gas supply, gas pre-heaters with sample holders for testing samples too small to be inductively heated by bathing them in hot gas, and a high temperature digital image correlation (DIC) capability for measuring high temperature strains real time. In addition to NTR testing, given the commonality of high enthalpy flow environments between the reactor of an NTP engine and the aerothermal heating of high-speed flight, the unique capabilities of NTREES to provide high temperature gas flows at high pressure without combustion or electrode spallation byproducts may lend itself to additional usage of the facility beyond the original intent.

Michael P Schoenfeld↗
NASA NTRS1990

Cation distributions on rapidly solidified cobalt ferrite

The cation distributions in two rapidly solidified cobalt ferrites have been determined using Moessbauer spectroscopy at 4.2 K in an 8-T magnetic field. The samples were obtained by gas atomization of a Co0-Fe2O3-P2O5 melt. The degree of cation disorder in both cases was greater than is obtainable by cooling unmelted cobalt ferrite. The more rapidly cooled sample exhibited a smaller departure from the equilibrium cation distribution than did the more slowly cooled sample. This result is explained on the basis of two competing effects of rapid solidification: high cooling rate of the solid, and large undercooling.

De Guire, Mark R.↗
NASA NTRS2017

Evolved Gas Analyses of the Murray Formation in Gale Crater, Mars: Results of the Curiosity Rover's Sample Analysis at Mars (SAM) Instrument

The Sample Analysis at Mars (SAM) instrument aboard the Mars Science Laboratory rover has analyzed 13 samples from Gale Crater. All SAM-evolved gas analyses have yielded a multitude of volatiles (e.g., H2O, SO2, H2S, CO2, CO, NO, O2, HCl) [1- 6]. The objectives of this work are to 1) Characterize recent evolved SO2, CO2, O2, and NO gas traces of the Murray formation mudstone, 2) Constrain sediment mineralogy/composition based on SAM evolved gas analysis (SAM-EGA), and 3) Discuss the implications of these results relative to understanding the geological history of Gale Crater.

Sutter, B.↗
NASA NTRS2010

Regolith Volatile Characterization (RVC) in RESOLVE

Resource investigation in the lunar poles is of importance to the potential impact of in-situ resource utilization (ISRU). The RESOLVE project developed a payload to investigate the permanently shadowed areas of the lunar poles and demonstrate ISRU technology. As a part of the RESOLVE project, the regolith volatile characterization (RVC) subsystem was designed to examine the release of volatiles from sample cores. The test sample was heated in the reactor to release the volatiles where they were analyzed with gas chromatography. Subsequently, the volatile sample was introduced into the lunar water resource demonstration (LWRD) subsystem where the released hydrogen and water were selectively captured. The objective of the Regolith Volatile Characterization (RVC) subsystem was to heat the crushed core sample and determine the desorption of volatile species of interest. The RVC subsystem encompasses the reactor and the system for volatile analysis. The system was designed to analyze H2, He, CO, CO2, N2, 02, CH4, H2S and H2O. The GC chosen for this work is a Siemens MicroSAM process GC with 3 columns and 8 TCD detectors. Neon was chosen as the carrier gas to enhance the analysis of hydrogen and helium.The limit of detection for the gases is approx.1000ppm for H2, CO. CO2 , N2, O2 and H2 S. The limit of detection for CH4 is approx.4000ppm and the water limit of detection is -10000 ppm with a sample analysis time of 2-3 minutes. These values (with the exception of water and H2S) were determined by dilution of a six gas mixture from Scott Gas (5% CO2, CO, O2, N2, 4% CH4 and H2) using mass flow controllers (MFC5). Water was calibrated at low levels using an in house relative humidity (RH) generator. H 2S and high concentrations of H2 were calibrated by diluting a pure stream of gas with MFCs. Higher concentrations of N2 and 02 were calibrated using Air again diluting with MFCs. There were three modification goals for the GC in EBU2 that would allow this process GC to be used in the field demo for RESOLVE. The first modification was to decrease the weight associated with the GC, this included eliminating the explosion proof case (Figure 1) and replacing it with a lightweight case as well as using an on board COPV tank for the neon carrier gas. The next goal was to add a second oven for the molecular sieve column to allow for dual temperature control during GC operation; the separation of hydrogen and helium is optimum at lower temperatures while the water analysis required higher temperatures creating a competing design requirement. The second oven also allows a lower limit of detection for water quantification and avoids the possibility of water condensing in the GC which could ruin the column characteristics. The final goal was to modify the column arrangement to optimize the system for our specific application. Figure 2 shows the internal details of the module optimized optimized for our field application. The modifications and performance of the gas analysis system will be discussed in detail.

Captain, Janine↗