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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

A carbon dioxide/methane greenhouse atmosphere on early Mars

One explanation for the formation of fluvial surface features on early Mars is that the global average surface temperature was maintained at or above the freezing point of water by the greenhouse warming of a dense CO2 atmosphere; however, Kasting has shown that CO2 alone is insufficient because the formation of CO2 clouds reduces the magnitude of the greenhouse effect. It is possible that other gases, such as NH3 and CH4, were present in the early atmosphere of Mars and contributed to the greenhouse effect. Kasting et al. investigated the effect of NH3 in a CO2 atmosphere and calculated that an NH3 mixing ratio of approximately 5 x 10 (exp -4) by volume, combined with a CO2 partial pressure of 4-5 bar, could generate a global average surface temperature of 273 K near 3.8 b.y. ago when the fluvial features are believed to have formed. Atmospheric NH3 is photochemically converted to N2 by ultraviolet radiation at wavelengths shortward of 230 nm; maintenance of sufficient NH3 concentrations would therefore require a source of NH3 to balance the photolytic destruction. We have used a one-dimensional photochemical model to estimate the magnitude of the NH3 source required to maintain a given NH3 concentration in a dense CO2 atmosphere. We calculate that an NH3 mixing ratio of 10(exp -4) requires a flux of NH3 on the order of 10(exp 12) molecules /cm-s. This figure is several orders of magnitude greater than estimates of the NH3 flux on early Mars; thus it appears that NH3 with CO2 is not enough to keep early Mars warm.

Brown, L. L.↗
NASA NTRS2017

Very Large Array Ammonia Observations of the HH 111/HH 121 Protostellar System: A Detection of a New Source with a Peculiar Chemistry

We present the results of Very Large Array NH3 (J, K) = (1, 1) and (2, 2) observations of the HH 111/HH 121 protostellar system. HH 111, with a spectacular collimated optical jet, is one of the most well-known Herbig-Haro objects. We report the detection of a new source, NH3-S, in the vicinity of HH 111/HH 121 (approximately 0.03 parsecs from the HH 111 jet source) in two epochs of the ammonia observations. This constitutes the first detection of this source, in a region that has been thoroughly covered previously by both continuum and spectral line interferometric observations. We study the kinematic and physical properties of HH 111 and the newly discovered NH3-S. We also use HCO plus and HCN (J=4-3) data obtained with the James Clerk Maxwell Telescope and archival Atacama Large Millimeter/submillimeter Array (sup 13) CO, (sup 12) CO, and C (sup 18) O (J=2-1), N2D plus (J=3-2), and (sup 13) CS (J=5-4) data to gain insight into the nature of NH3-S. The chemical structure of NH3-S shows evidence for "selective freeze-out," an inherent characteristic of dense cold cores. The inner part of NH3-S shows subsonic nonthermal velocity dispersions indicating a "coherent core," while they increase in the direction of the jets. Archival near- to far-infrared data show no indication of any embedded source in NH3-S. The properties of NH3-S and its location in the infrared dark cloud suggest that it is a starless core located in a turbulent medium, with the turbulence induced by Herbig-Haro jets and associated outflows. More data are needed to fully understand the physical and chemical properties of NH3-S and if/how its evolution is affected by nearby jets.

James Clerk Maxwell Telescop↗
DOE OSTI2020

Chemical influence of ammonia on suppressing soot formation pathways

There is interest in mixing ammonia (NH3) with hydrocarbons, as this decreases overall CO2 emissions from the fuel mixture when burned. Co-firing NH3 with hydrocarbons like methane (CH4) also enables stable combustion over a larger set of operating conditions in engines and gas turbines than firing only NH3 permits. When NH3 is co-fired with hydrocarbons, the influence of NH3 on soot formation chemistry becomes relevant. In this work, soot concentrations in laminar nonpremixed co-flow flames of NH3/CH4 and N2/CH4 were analyzed using color-ratio pyrometry. The concentrations of combustion species (CH4, CO2, H2O, O2, C2H2, C6H6, HCN) across the different flames were also determined using on-line electron-impact mass spectrometry. The flames were also interrogated with 2D CFD simulations, which employ a detailed chemical mechanism tailored to capturing fuel-nitrogen chemistry. Addition of NH3 to CH4 flames was found to decrease soot concentrations more significantly than N2-addition (Fig. 1). The NH3/CH4 flames were found to have higher flame temperatures than the N2/CH4 flames, implying the suppression of soot afforded by NH3 is due to a chemical influence of NH3, as opposed to thermal or dilution effects. Based on experimental and simulated soot volume fractions and species concentrations, soot formation pathways affected by NH3 are postulated.

10 SYNTHETIC FUELS↗
DOE OSTI2025

Magnesium‐Mediated Electrochemical Synthesis of Ammonia

Metal-mediated electrochemical synthesis of ammonia (NH3) is a promising method to activate N2 at room temperature. While a Li-mediated approach has been optimized to produce NH3 at high current density and selectivity, Li's scarcity and its highly negative plating potential limit scalability and energy efficiency. Alternative mediators have been proposed, but only Ca has shown some promise, achieving ≈50% Faradaic efficiency (FE), though requiring voltages beyond -3 V. Here, we report a Mg-mediated nitrogen reduction reaction (Mg-NRR), where N2 is activated on Mg to form Mg3N2, followed by protolysis to release NH3 and regenerate Mg. A notable NH3 FE of 25.28 ± 3.80% is achieved at a current density of -45 mA cm-2, corresponding to an NH3 partial current density of -11.30 ± 1.77 mA cm-2 under 6 bar N2. Isotope-labeled experiments confirm that NH3 originates from N2, with similar FE (25.15 ± 1.01%). Importantly, NH3 production is demonstrated at a total cell potential as low as -3 V. This Li-free Mg-NRR system offers key advantages, including lower energy input and use of earth-abundant materials, making it a scalable route for sustainable NH3 synthesis.

Goyal, Ishita↗
DOE OSTI2021

Mitigation of Acute Hydrogen Sulfide and Ammonia Emissions from Swine Manure during Three-Hour Agitation Using Pelletized Biochar

The risk of inhalation exposure to elevated concentrations of hydrogen sulfide (H2S) and ammonia (NH3) during the agitation of stored swine manure is high. Once or twice a year, farmers agitate manure before pump-out and application to fields. Agitation of the swine manure causes the short-term releases of highly toxic levels of H2S and NH3. In our previous pilot-scale studies, the biochar powder showed significant mitigation of H2S and NH3 emissions when it was surficially applied to manure immediately before agitation. However, fine biochar powder application poses hazards by itself and may not be practical to apply on a farm scale, especially when livestock and workers are present. We hypothesized that applying pelletized biochar to manure surfaces is just as effective as applying powder to protect farmers and animals from excessive exposure to H2S and NH3. This work reports on the lab-scale proof-of-the-concept trials with biochar pellets on the lab scale. The objective was to compare the biochar pellets and biochar powder on their effectiveness of mitigation on H2S and NH3 gases during 3-h-long swine manure agitation. Three scenarios were compared in (n = 3) trials: (i) control, (ii) 12.5 mm thick surficial application to manure surface of biochar powder, and (iii) an equivalent (by mass) dose of pelletized biochar applied to the manure surface. The biochar powder was bound with 35% (wt) water into ~5 × 10 mm (dia × length) pellets. The biochar powder was significantly (p < 0.05) more effective than the biochar pellets. Still, pellets reduced total H2S and NH3 emissions by ~72% and ~68%, respectively (p = 0.001), compared with ~99% by powder (p = 0.001). The maximum H2S and NH3 concentrations were reduced from 48.1 ± 4.8 ppm and 1810 ± 850 ppm to 20.8 ± 2.95 ppm and 775 ± 182 ppm by pellets, and to 22.1 ± 16.9 ppm and 40.3 ± 57 ppm by powder, respectively. These reductions are equivalent to reducing the maximum concentrations of H2S and NH3 during the 3-h manure agitation by 57% and 57% (pellets) and 54% and 98% (powder), respectively. Treated manure properties hinted at improved nitrogen retention, yet they were not significant due to high variability. We recommend scaling up and trials on the farm-scale level using biochar pellets to assess the feasibility of application to large manure surfaces and techno-economic evaluation.

Chen, Baitong (ORCID:0000000266071253)↗
NASA NTRS2014

Solar Metal Sulfate-Ammonia Based Thermochemical Water Splitting Cycle for Hydrogen Production

Two classes of hybrid/thermochemical water splitting processes for the production of hydrogen and oxygen have been proposed based on (1) metal sulfate-ammonia cycles (2) metal pyrosulfate-ammonia cycles. Methods and systems for a metal sulfate MSO.sub.4--NH3 cycle for producing H2 and O2 from a closed system including feeding an aqueous (NH3)(4)SO3 solution into a photoctalytic reactor to oxidize the aqueous (NH3)(4)SO3 into aqueous (NH3)(2)SO4 and reduce water to hydrogen, mixing the resulting aqueous (NH3)(2)SO4 with metal oxide (e.g. ZnO) to form a slurry, heating the slurry of aqueous (NH4)(2)SO4 and ZnO(s) in the low temperature reactor to produce a gaseous mixture of NH3 and H2O and solid ZnSO4(s), heating solid ZnSO4 at a high temperature reactor to produce a gaseous mixture of SO2 and O2 and solid product ZnO, mixing the gaseous mixture of SO2 and O2 with an NH3 and H2O stream in an absorber to form aqueous (NH4)(2)SO3 solution and separate O2 for aqueous solution, recycling the resultant solution back to the photoreactor and sending ZnO to mix with aqueous (NH4)(2)SO4 solution to close the water splitting cycle wherein gaseous H2 and O2 are the only products output from the closed ZnSO4--NH3 cycle.

Huang, Cunping↗
NASA NTRS1986

Hot hydrogen atom reactions moderated by H2 and He

Photolysis experiments were performed on the H2-CD4-NH3 and He-CD4-NH3 systems. The photolysis (1849 A) involved only NH3. Mixtures of H2:CD4:NH3 included all combinations of the ratios (200,400,800):(10,20,40):4. Two He:CD4:NH3 mixtures were examined where the ratios equalled the combinations 100:(10,20):4. Abstraction of a D from CD4 by the photolytically produced hot hydrogen from ammonia was monitored by mass spectrometric determination of HD. Both experiment and semiempirical hot-atom theory show that H2 is a very poor thermalizer of hot hydrogens with excess kinetic energy of about 2 eV. Applications of the hard-sphere collision model to the H2-CD4-NH3 system resulted in predicted ratios of net HD production to NH3 decomposition that were two orders of magnitude smaller than the experimental ratios. On the other hand, helium is found to be a very efficient thermalizer; here, the classical model yields reasonable agreement with experiments. Application of a semiempirical hot-atom program gave quantitative agreement with experiment for either system.

Aronowitz, S.↗
NASA NTRS2011

Ammonia Offgassing from SA9T

NH3 is a degradation product of SA9T, a solid-amine sorbent developed by Hamilton Sundstrand, that is continually emitted into the gas stream being conditioned by this sorbent. NH3 offgassing rates were measured using FTIR spectroscopy using a packed bed at similar contact times as offgassing tests conducted at Hamilton Sundstrand and at the Ames Research Center. The bed was challenged with moist air at several flow rates and humidities and NH3 concentration of the effluent was measured for several hours. The NH3 offgassing rates in open-loop testing were calculated from the steady state outlet NH3 concentration and flow rate. NH3 offgassing rates from SA9T were found to be influenced by the contact time with the adsorbent (flow rate) and by the humidity of the inlet gas stream, which are consistent with previous studies. Closed-loop vacuum-swing adsorption cycling rates verified that NH3 offgassing continues when a constant source of water vapor is present.

Monje, Oscar↗
NASA NTRS2011

Quantifying Spatial and Seasonal Variability in Atmospheric Ammonia with In Situ and Space-Based Observations

Ammonia plays an important role in many biogeochemical processes, yet atmospheric mixing ratios are not well known. Recently, methods have been developed for retrieving NH3 from space-based observations, but they have not been compared to in situ measurements. We have conducted a field campaign combining co-located surface measurements and satellite special observations from the Tropospheric Emission Spectrometer (TES). Our study includes 25 surface monitoring sites spanning 350 km across eastern North Carolina, a region with large seasonal and spatial variability in NH3. From the TES spectra, we retrieve a NH3 representative volume mixing ratio (RVMR), and we restrict our analysis to times when the region of the atmosphere observed by TES is representative of the surface measurement. We find that the TES NH3 RVMR qualitatively captures the seasonal and spatial variability found in eastern North Carolina. Both surface measurements and TES NH3 show a strong correspondence with the number of livestock facilities within 10 km of the observation. Furthermore, we find that TES H3 RVMR captures the month-to-month variability present in the surface observations. The high correspondence with in situ measurements and vast spatial coverage make TES NH3 RVMR a valuable tool for understanding regional and global NH3 fluxes.

Pinder, Robert W.↗
DOE OSTI2024

A synthetic co-culture for bioproduction of ammonia from methane and air

Abstract Fixed nitrogen fertilizers feed 50% of the global population, but most fixed nitrogen production occurs using energy-intensive Haber–Bosch-based chemistry combining nitrogen (N2) from air with gaseous hydrogen (H2) from methane (CH4) at high temperatures and pressures in large-scale facilities sensitive to supply chain disruptions. This work demonstrates the biological transformation of atmospheric N2 into ammonia (NH3) using CH4 as the sole carbon and energy source in a single vessel at ambient pressure and temperature, representing a biological “room-pressure and room-temperature” route to NH3 that could ultimately be developed to support compact, remote, NH3 production facilities amenable to distributed biomanufacturing. The synthetic microbial co-culture of engineered methanotroph Methylomicrobium buryatense (now Methylotuvimicrobium buryatense) and diazotroph Azotobacter vinelandii converted three CH4 molecules to l-lactate (C3H6O3) and powered gaseous N2 conversion to NH3. The design used division of labor and mutualistic metabolism strategies to address the oxygen sensitivity of nitrogenase and maximize CH4 oxidation efficiency. Media pH and salinity were central variables supporting co-cultivation. Carbon concentration heavily influenced NH3 production. Smaller-scale NH3 production near dispersed, abundant, and renewable CH4 sources could reduce disruption risks and capitalize on untapped energy resources. One-Sentence Summary Co-culture of engineered microorganisms Methylomicrobium buryatense and Azotobacter vinelandii facilitated the use of methane gas as a sole carbon feedstock to produce ammonia in an ambient temperature, atmospheric pressure, single-vessel system.

Biotechnology & Applied Microbiology↗
DOE OSTI2025

Dual-Fuel Ammonia Equivalence Ratio Sweep Data

Ammonia (NH3) has garnered significant interest as an alternative fuel for meeting international emissions reduction mandates in sectors with high weight and distance requirements, such as shipping. Technical barriers and unanswered questions remain on the combustion strategies that can maximize ammonia utilization and minimize emissions. Prior research studies at the US Department of Energy’s Oak Ridge National Laboratory have shown strong performance with NH3 under dual-fuel mode using conventional diesel combustion (CDC) manifold air pressure settings. Diesel airflow was initially used to simplify retrofitting (no turbocharger modification), which resulted in air-fuel equivalence ratios (λ) greater than 1.5. To characterize potential improvements in dual-fuel NH3 combustion performance at richer in-cylinder conditions, a global λ sweep compared the use of early (E-pilot) and late (L-pilot) single diesel injections. The experiments were conducted at 1200 RPM and 12.8 ± 0.2 bar (75 % load), and λ was varied by decreasing the commanded air flow to the engine at greater than 90 % ammonia energy substitution level. A diesel injection timing sweep was conducted for both the injection strategies at fixed λ, and the timing with the lowest engine-out N2O emissions was identified. The results indicated an optimal balance between CO2,eq and thermal efficiency benefits both E-pilot and L-pilot injection strategy cases compared with CDC at a λ of 1.4. The indicated nitrogen-based emissions exhibited a strong correlation to the ratio of CA5–50 and ignition delay for L-pilot, but no apparent trend emerged for the E-pilot injection strategy at the tested boundary conditions. This dataset includes the raw experimental data and documentation of the experiment conditions and methods.

30 DIRECT ENERGY CONVERSION↗
NASA NTRS1975

Photosynthesis of organic compounds in the atmosphere of Jupiter

An efficient conversion of CH4 to hydrocarbons and HCN takes place when NH3 is photolysed in the presence of CH4, H2, and He using a 184.9 nm light source. The extent of NH3 decomposition after a 1 hr exposure was determined spectrophotometrically; CH4, N2, and C2 and C3 hydrocarbons were detected and analyzed by mass spectrometry. Photolysis of one molar equivalent of NH3 results in the loss of 0.84 molar equivalent of CH4, which apparently reacts with hot hydrogen atoms produced by photolysis. The 8% of the NH3 which is not converted to N2 probably is converted to organic amines and nitrile derivatives. The results indicate that NH3 photolysis is a highly probable mechanism for the conversion of methane to more complex hydrocarbons in the upper atmosphere of Jupiter, and predict the occurrence of HCN, NH2NH2, and higher hydrocarbons in the Jovian atmosphere above the NH3 clouds.

Ferris, J. P.↗
NASA NTRS1976

Reaction of NH2 with NO and O2

Experiments were performed on the photooxidation of NH3 at room temperature and the photolysis of NH3-NO mixtures in order to determine the reaction paths of NH2 with O2. NH3 was photolyzed (NH3 + E yields NH2 + H) in the presence of O2 above 0.6 torr at 213.9 nm and 25 C, producing N2 and N2O. Only N2 and N2O were produced with any significant quantum yield, and their quantum yield was invariant with reaction conditions, which imposes a great number of constraints reducing the number of possible reactions greatly. It is argued that the N2 must be produced from the NH2O2 radical which was produced by the reaction between NH2 and O2. Subsequent reactions leading to N2 and N2O are speculative. In the photolysis of NH3 in the presence of NO and NO-O2 mixtures, the products identified were N2, H2, and N2O. Without the presence of O2, the reaction scheme after photolysis is (2) NH2 + NO yields N2 + H2O, (3) H + NO + M yields HNO + M, (4) H + HNO yields H2 + NO, and (5) 2HNO yields N2O + H2O. The average value for the ratio k3 times the square root of k5 divided by k4 was computed to be (1.6 plus or minus 0.6) times 10 to the minus 28th cm to the exponent 9/2 per square root sec. In addition, the presence of 113 mtorr of O2 had no effect on the quantum yields of N2 or H2, so it appears that it does not deactivate electronically excited NH3.

Jayanty, R. K. M.↗
NASA NTRS1981

The infrared spectrum of ammonia hydrate - Explanation for a reported ammonia phase

A number of anomalous spectra of solid NH3 deposited from the vapor phase have appeared in the literature. These spectra have been ascribed to a new phase of NH3. In the experiment reported here these anomalous spectra were reproduced by depositing a thin film from a mixture of gaseous NH3 and H2O and annealing this film at a temperature of 162 K. The thin film spectra showed excellent agreement with recent data on NH3.H2O. The anomalous 'NH3' spectra are, therefore, seen to be caused by H2O contamination of solid NH3 with formation of NH3 hydrate.

Still, G.↗
NASA NTRS1992

State-to-state rotational energy-transfer measurements in the nu(2) = 1 state of ammonia by infrared-infrared double resonance

The state-resolved rotational (R-R, R-T) energy transfer in (N-14)H3 (for NH3-NH3 and NH3-Ar collisions) was studied using an IR double-resonance laser spectroscopic technique. Measurements of both the total rate of depopulation by collisions, and the rates of transfer into specific final rovibrational states (v,J,K) were performed using time-resolved tunable diode laser absorption spectroscopy. A kinetic master-equation analysis of time-resolved level populatons was carried out, yielding state-to-state rate constants and propensity rules for NH3-NH3 and NH3-Ar collisions.

Abel, Bernd↗
NASA NTRS1999

The Spatial Variation of Water and Ammonia near Jupiter's Great Red Spot

The CSHELL spectrometer at NASA's Infrared Telescope Facility was used in August 1996 to observe Jupiter at 5.18 microns. This wavelength sounds the 3-8 bar region in Jupiter's deep troposphere. A 1-arcsec-wide slit was aligned east-west on Jupiter and stepped from north to south across the Great Red Spot (GRS). Within our spectral bandpass are absorption lines of NH3 and a hot band of CH4. Radiative transfer models indicate that the strength of the CH4 feature is anti-correlated with gaseous H2O between 3 and 6 bars. The CH4 feature is predicted to be very strong for H2O abundances less than 10ppm and it should vanish when H2O > 300ppm. The depths of the observed CH4 and NH3 absorption features varied dramatically near the GRS. The center and east side (planetocentric) of the GRS is dry in both volatiles as indicated by strong CH4 absorption and a weak NH3 line. The CH4 line vanishes and the NH3 feature grows stronger on the west side of the GRS. We interpret this as due to a real variation in both volatiles - H2O and NH3 - due to a common dynamical mechanism. Water clouds are expected to be accompanied by saturated gaseous H2O profiles between 3 and 5 bars. The Galileo imaging team (Banfield et al 1998 Icarus 135, p230) deduced the presence of a cloud near the 4-bar level northwest of the GRS. Our data indicate that this same region is volatile rich; thus the combination of the two datasets provides a compelling case for a water cloud at this location. The deep volatile abundance does not correlate with 5-micron continuum opacity near the GRS. This suggests that the spatial variation of the 5-micron flux near the GRS is due primarily to NH3 clouds, rather than H2O clouds.

Bjoraker, G. L.↗
NASA NTRS1996

Evolutionary status of the pre-protostellar core L1498

L1498 is a classic example of a dense cold pre-protostellar core. To study the evolutionary status, the structure, dynamics, and chemical properties of this core we have obtained high spatial and high spectral resolution observations of molecules tracing densities of 10(3)-10(5) cm-3. We observed CCS, NH3, C3H2, and HC7N with NASA's DSN 70 m antennas. We also present large-scale maps of C18O and 13CO observed with the AT&T 7 m antenna. For the high spatial resolution maps of selected regions within the core we used the VLA for CCS at 22 GHz, and the Owens Valley Radio Observatory (OVRO) MMA for CCS at 94 GHz and CS (2-1). The 22 GHz CCS emission marks a high-density [n(H2) > 10(4) cm -3] core, which is elongated with a major axis along the SE-NW direction. NH3 and C3H2 emissions are located inside the boundary of the CCS emission. C18O emission traces a lower density gas extending beyond the CCS boundary. Along the major axis of the dense core, CCS, NH3 and C3H2 emission show evidence of limb brightening. The observations are consistent with a chemically differentiated onion-shell structure for the L1498 core, with NH3 in the inner and CCS in the outer parts of the core. The high angular resolution (9"-12") spectral line maps obtained by combining NASA Goldstone 70 m and VLA data resolve the CCS 22 GHz emission in the southeast and northwest boundaries into arclike enhancements, supporting the picture that CCS emission originates in a shell outside the NH3 emitting region. Interferometric maps of CCS at 94 GHz and CS at 98 GHz show that their emitting regions contain several small-scale dense condensations. We suggest that the differences between the CCS, CS, C3H2, and NH3 emission are caused by a time-dependent effect as the core evolves slowly. We interpret the chemical and physical properties of L1498 in terms of a quasi-static (or slowly contracting) dense core in which the outer envelope is still growing. The growth rate of the core is determined by the density increase in the CCS shell resulting from the accretion of the outer low-density gas traced by C18O. We conclude that L1498 could become unstable to rapid collapse to form a protostar in less than 5 x 10(6) yr.

NASA Discipline Exobiology↗
NASA NTRSDate not supplied

In Situ Measurements of Ammonia In Plumes Emitted From Wildfires And Agricultural Fires in the US

Emissions of trace gases and particles from fires have a major impact on climate, visibility, air quality, and public health. Biomass burning emissions include reactive nitrogen gases, among which ammonia (NH3) plays a prominent role. NH3 is a short-lived gas that acts as precursor for secondary inorganic aerosols. This process is still poorly constrained in downwind fire plumes. In summer 2019, NASA and NOAA carried out the joint airborne FIREX-AQ (Fire Influence on Regional to global Environments and Air Quality) mission over the continental US to sample plumes from wildfires and agricultural fires. On board the NASA DC-8, we used a modified PTR-ToF-MS instrument for measuring NH3 in situ and at high time resolution. Over the course of the mission, we collected a large set of NH3 data in plumes emitted from fires differing in fuel type and burning stage. Herein, we will present the measured NH3 emissions ratios and factors, compare them with the literature, and investigate the dependence of NH3 emissions on fuel type and burning conditions.

ammonia↗