Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “N2”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 559 records · Page 31
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on CeP2N2O9 by Materials Project

(Ce(PO4)2)2(N2)2O2 crystallizes in the orthorhombic Imma space group. The structure is three-dimensional and consists of eight ammonia molecules, four water molecules, and one Ce(PO4)2 framework. In the Ce(PO4)2 framework, Ce4+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ce–O bond distances ranging from 2.23–2.58 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded in a tetrahedral geometry to four O2- atoms. There is two shorter (1.53 Å) and two longer (1.57 Å) P–O bond length. In the second P5+ site, P5+ is bonded in a tetrahedral geometry to four O2- atoms. There is two shorter (1.54 Å) and two longer (1.56 Å) P–O bond length. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to one Ce4+ and one P5+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one Ce4+ and one P5+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to one Ce4+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ce4+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ZnMo(NO2)4 by Materials Project

ZnMoO8(N2)2 crystallizes in the tetragonal I-4 space group. The structure is zero-dimensional and consists of eight ammonia molecules, two MoO8 clusters, and two zinc dust molecules. In each MoO8 cluster, Mo6+ is bonded in a distorted hexagonal bipyramidal geometry to eight O2- atoms. There are four shorter (1.99 Å) and four longer (2.02 Å) Mo–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to one Mo6+ and one O2- atom. The O–O bond length is 1.42 Å. In the second O2- site, O2- is bonded in a 1-coordinate geometry to one Mo6+ and one O2- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ir2Os(NCl)10 by Materials Project

OsCl6(IrN3Cl2)2(N2)2 crystallizes in the monoclinic C2/m space group. The structure is zero-dimensional and consists of two hexachloroosmium molecules, four nitrogen molecules, and four IrN3Cl2 clusters. In each IrN3Cl2 cluster, Ir4+ is bonded in a tetrahedral geometry to three N+0.60- and one Cl1- atom. There is two shorter (1.73 Å) and one longer (2.00 Å) Ir–N bond length. The Ir–Cl bond length is 2.27 Å. There are two inequivalent N+0.60- sites. In the first N+0.60- site, N+0.60- is bonded in a bent 120 degrees geometry to one Ir4+ and one Cl1- atom. The N–Cl bond length is 1.67 Å. In the second N+0.60- site, N+0.60- is bonded in a single-bond geometry to one Ir4+ atom. There are two inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one N+0.60- atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one Ir4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SnN2Cl4O by Materials Project

N2(SnCl4)2(NO)2 crystallizes in the orthorhombic Pna2_1 space group. The structure is one-dimensional and consists of four ammonia molecules; four nitroxyl molecules; and two SnCl4 ribbons oriented in the (1, 0, 0) direction. In each SnCl4 ribbon, Sn4+ is bonded to six Cl1- atoms to form edge-sharing SnCl6 octahedra. There are a spread of Sn–Cl bond distances ranging from 2.38–2.63 Å. There are four inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Sn4+ atom. In the second Cl1- site, Cl1- is bonded in a distorted L-shaped geometry to two equivalent Sn4+ atoms. In the third Cl1- site, Cl1- is bonded in an L-shaped geometry to two equivalent Sn4+ atoms. In the fourth Cl1- site, Cl1- is bonded in a single-bond geometry to one Sn4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on OsIN5Cl2O by Materials Project

OsICl2(N2)2NO crystallizes in the tetragonal I4mm space group. The structure is two-dimensional and consists of eight ammonia molecules; two nitroxyl molecules; and two OsICl2 sheets oriented in the (0, 0, 1) direction. In each OsICl2 sheet, Os4+ is bonded in a 2-coordinate geometry to one I1- atom. The Os–I bond length is 2.76 Å. I1- is bonded in a 5-coordinate geometry to one Os4+ and four equivalent Cl1- atoms. All I–Cl bond lengths are 3.15 Å. Cl1- is bonded in a distorted linear geometry to two equivalent I1- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on S(NO)2 by Materials Project

N2(SO2N)2 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four 1,3,5,2,4,6-trithiatriazinane 1,1,3,3,5,5-hexaoxide molecules and twelve ammonia molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on O2 by Materials Project

O2 is Cubic alpha N2-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is zero-dimensional and consists of two hydrogen peroxide molecules. O is bonded in a single-bond geometry to one O atom. The O–O bond length is 1.23 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ReRu2(NCl)10 by Materials Project

ReCl6(RuN3Cl2)2(N2)2 crystallizes in the monoclinic C2/m space group. The structure is one-dimensional and consists of two hexachlororhenium molecules; four nitrogen molecules; and two RuN3Cl2 ribbons oriented in the (0, 1, 0) direction. In each RuN3Cl2 ribbon, Ru+4.50+ is bonded in a trigonal non-coplanar geometry to three N+0.60- atoms. There is two shorter (1.71 Å) and one longer (1.82 Å) Ru–N bond length. There are two inequivalent N+0.60- sites. In the first N+0.60- site, N+0.60- is bonded in a single-bond geometry to one Ru+4.50+ and one Cl1- atom. The N–Cl bond length is 3.32 Å. In the second N+0.60- site, N+0.60- is bonded in a bent 150 degrees geometry to one Ru+4.50+ and one Cl1- atom. The N–Cl bond length is 1.60 Å. There are two inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a 1-coordinate geometry to two equivalent N+0.60- and one Cl1- atom. The Cl–Cl bond length is 1.99 Å. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one N+0.60- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Discovery of Innovative Polymers for Next-Generation Gas-Separation Membranes using Interpretable Machine Learning

Polymer membranes perform innumerable separations with far-reaching environmental implications. Despite decades of research on membrane technologies, design of new membrane materials remains a largely Edisonian process. To address this shortcoming, we demonstrate a generalizable, accurate machine-learning (ML) implementation for the discovery of innovative polymers with ideal separation performance. Specifically, multitask ML models are trained on available experimental data to link polymer chemistry to gas permeabilities of He, H2, O2, N2, CO2, and CH4. Here, we interpret the ML models and extract chemical heuristics for membrane design, through Shapley Additive exPlanations (SHAP) analysis. We then screen over nine million hypothetical polymers through our models and identify thousands of candidates that lie well above current performance upper bounds. Notably, we discover hundreds of never-before-seen ultrapermeable polymer membranes with O2 and CO2 permeability greater than 104 and 105 Barrer, respectively. These hypothetical polymers are capable of overcoming undesirable trade-off relationship between permeability and selectivity, thus significantly expanding the currently limited library of polymer membranes for highly efficient gas separations. High-fidelity molecular dynamics simulations confirm the ML-predicted gas permeabilities of the promising candidates, which suggests that many can be translated to reality.

Yang, Jason↗
DOE OSTI2022

Allosteric control of electron transfer in nitrogenase and nitrogenase-like enzymes (Final Report)

More than a third of all known proteins to date are either oxidoreductases or metalloproteins. The diversity of metal cofactors and redox centers in these proteins make them attractive candidates for engineering protein-based biocatalysts, biosensors, and biofuel cells, among other necessary tools for the bioeconomy. Many of these enzymes function as large multi-subunit complexes arranged as symmetric or asymmetric assemblies, and the purpose of this architecture is unclear. The goal of the project was to address this fundamental question by investigating the mechanism of action of two oxidoreductases: Nitrogenase and DPOR (Dark-Operative Protochlorophyllide Oxidoreductase, a nitrogenase-like oxidoreductase). Nitrogenase and DPOR play key roles in nitrogen fixation and photosynthesis, processes essential to sustaining life. Both proteins are arranged as two symmetrical halves with each half capable of substrate reduction. For more than half a century, substrate reduction by nitrogenase has been presumed to occur independently within the two identical halves. Funded by this DOE grant we have now shown that both nitrogenase and DPOR function asymmetrically. Electron transfer in one half suppresses activity in the other. Thus, we have demonstrated that the two halves do not function in an independent manner; rather, catalytic events in one-half allosterically suppress activity and electron transfer (ET) in the other. This alternating-site mechanism has significant implications on our current understanding of substrate reduction by these enzymes and offers a new mechanistic paradigm for the reactions they catalyze. Our work now provides a mechanistic map of the how the two symmetric catalytic halves work together to establish and maintain the sequential-site mechanism through multiple ET cycles to achieve substrate reduction. There is substantive need for bio-inspired tools that enable reduction of nitrogen and other substrates, as well as photosynthesis, for energy and food production. Understanding the workings of enzymes like nitrogenase and DPOR that mediate multi-electron redox chemistry is vital for designing such synthetic tools. The timing of our research coincides with the biotechnological breakthrough of light-driven artificial N2 reduction by nitrogenase, achieved using the native enzyme with both halves arranged in a mirror-like architecture as catalyst. Together with such discoveries, our research now reveal unknown facets of the reaction mechanism and hold promise for designing more effective catalysts.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Step Catalysis to Synthesize Fossil-Free Ammonia at Atmospheric Pressure (Final Technical Report)

Affordable fossil-free ammonia synthesis will enable high-yield sustainable crop production for a growing world population while preserving the planet and making the best use of water and land. Simple technology amenable to intermittent operation using renewable energy will be made available through step catalysis activating dinitrogen at atmospheric pressure by nitride formation. Project objectives: (1) At the single particle level, quantify and analyze N2 activation by doped or alloyed manganese macroscopic- and nano particles at atmospheric pressure, (2) Quantify and analyze ammonia synthesis from doped or alloyed metal nitride particles when contacting them with hydrogen at atmospheric pressure, and (3) Integrate experimental data and atomic-level computational models to predict the behavior of metal alloys in nitrogen activation and subsequent ammonia synthesis.

10 SYNTHETIC FUELS↗
DOE OSTI2022

Foam Fracturing Study for Stimulation Development of Enhanced Geothermal Systems

The large thermal gradients and high subsurface temperatures of the western region of the U.S. hold great potential for the implementation of enhanced geothermal systems (EGS). The development of these potential EGS resources requires stimulation of the reservoir to enhance permeability and it has been widely reported that a substantial amount of water will be required should conventional hydraulic stimulation be used. This presents a huge challenge and a high risk to the geothermal development because the water stress1 in these areas is already high or extremely high. The use of foam, a gas/liquid mixture predominantly composed of gas, in fracturing is considered and explored in this project as a potential approach to address water concerns with hydraulic stimulation in the development of EGS. This project, led by Oak Ridge National Laboratory (ORNL) in collaboration with Temple University, was awarded in an open lab call in 2018, and was part of the DOE GTO waterless stimulation initiative. The goal of the project was to demonstrate the feasibility of foam fracturing for EGS development through two primary tasks: Task 1: Laboratory study of the effectiveness of foam fracturing for representative geological materials, including cyclic pressurization using foam (led by ORNL) and Task 2: High temperature foam material selection and characterization (led by Temple University). In FY19, ORNL finished the critical review on serval issues associated with foam fracturing and the implementation of the proposed tasks in a lab study (Wang, et al., 2019), and completed the foam fracturing testing using cement as a model material (Wang, et al, 2020a). The work at ORNL was geared up to develop a brand-new foam testing system in FY20. The purchase of main components for the new system was finished in the first half of the FY20. The assembly of the foam testing system and foam fracturing testing were completed in the second half of the FY20 (Wang, et al., 2021a). Task 1 required the development of a test system which can be used to perform hydraulic fracturing of geological specimens with both water and foamed liquids at pressure up to 6,000 psi (41.4 MPa). The system possesses several capabilities that conventional injection systems lack for hydraulic fracturing. In addition to its ability to generate foam with controlled quality, it is capable of cycling pressure levels between specified values up to frequencies of 50 Hz. The latter capability was developed to evaluate the hypothesis that cyclic loading of samples would produce enhanced fracturing. The system consists of two sections: one for foam generation and another for foam injection. The foam is generated through separate control and pressurization of liquid and gas phases with controlled flow rates. The injection section is equipped with a low-flow Coriolis flow that monitors the density of foam to ensure the injection is in the range of target foam quality2. Experimental results of foam fracturing are reported for cylindrical granite specimens using water and aqueous N2 foam as the fracturing fluids. All experiments were performed for unconfined conditions. The effects of injection mode (i.e., monotonic vs cyclic pressurization) on breakdown pressure and failure response sample were investigated using water alone as a fracturing fluid and foams with a range of compositions. It was found that in the case of monotonic injection, the breakdown pressure of granite specimens tended to be slightly higher when fracturing with foam. Additionally, with a foam quality of 90%, the water use can be reduced by 50 to 84%, depending on hole size. On the other hand, it was observed that the breakdown pressure can be brought down to 70% of the monotonic breakdown pressure by using low cycle fatigue. Finally, discussions are presented regarding injectivity and water use reduction.

15 GEOTHERMAL ENERGY↗
DOE OSTI2024

Connecting Nitrogen Transformations Mediated by the Rhizosphere Microbiome to Perennial Cropping System Productivity in Marginal Lands

The demand for energy from biofuel production is increasing, prompting concerns about the environmental impact and long-term sustainability of bioenergy cropping systems. These cropping systems will make up much of our future landscapes, and threaten to take the place of food cropping systems. Many life cycle analyses of bioenergy sustainability focus on carbon accrual and budgets, since they want to maximize carbon accrual while producing alternative fuel. Less attention has been given to nitrogen (N) dynamics in these systems. N is the most commonly limiting nutrient for plants, but applying nitrogen fertilizer- as we do for most cropping systems – is harmful to the environment, energetically costly, and produces greenhouse gases. In other words, adding nitrogen by fertilizer bioenergy systems could add to the very problems (climate change) it is trying to address. This is especially true for the areas that are proposed for bioenergy systems: marginal lands. These more degraded lands do not complete with food crops, but do have limited nitrogen. If we are to use these marginal lands for bioenergy, we need to understand the mechanisms regulating nutrient acquisition, and identify ways that bioenergy crops can get nitrogen in sustainable ways. Nutrient acquisition in the soil is performed by microbes in the root zone, or rhizosphere. Microbes can either mineralize nitrogen in the soil (from organic forms) or fix nitrogen from the air, in a process called nitrogen fixation. The goal of our project was thus to understand how the rhizosphere microbiome provides nutrients to bioenergy crops on marginal lands. We focus especially on the process of nitrogen fixation, since it has potential to get “fertilizer for free” that has much less environmental harm. We investigated this goal using sites from the DOE Great Lakes Bioenergy Research Center (GLBRC) in the upper Midwest, and associated lab and ‘omics methods. We group our findings into three major areas. First, we showed that nitrogen fixation, the conversion of N2 gas from the air to ammonium that is usable by plants, is performed in bioenergy soils, and benefits switchgrass crops. While more well-studied in leguminous plants, free-living nitrogen fixation can occur in some systems, and represents a potential opportunity to gain ‘free’ sustainable nitrogen source. We identified the nitrogen fixing bacteria that were most active in providing switchgrass with N, and showed that the drivers of nitrogen fixation occurred at a microscale; it is not well-predicted by bulk variables like soil moisture or plant phenology. Second, we showed that nitrogen fixation is not suppressed by long-term fertilizer. We expected that plentiful nitrogen would reduce the symbiotic relationship between nitrogen fixers and plants, and ‘downregulate’ fixation. We did not find evidence for this, either after long-term fertilizer in the field, or short-term fertilizer in the greenhouse. Finally, we identified the root exudates, carbon compounds that are emitted from the root, that best stimulate nitrogen fixation. We found that carbohydrates were better at stimulating fixation than organic acids. We expected these exudates to be emitted from the plant in periods of high N demand, but we found they are emitted when N is plentiful. This suggests that the stimulation of N fixation by plants is a passive process. Overall, we show that nitrogen fixation has potential to support bioenergy cropping system, and future management could develop ways to maximize it. However, this may not be best achieved via the plant – we found very little evidence of a ‘transactional’ system by which plants are controlling when and where nitrogen fixation is stimulated. It will be better to understand how management practices like planting and fertilizer application affect the microscale soil dynamics, which will determine nitrogen fixation rates.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Fabrication and Testing of Micro Flux Monitors in the High Flux Isotope Reactor

Neutron dosimetry is a critical technique to measure the neutron flux, fluence, and energy spectrum of nuclear reactors and can be used to indicate fuel reloading, high-power operations, or changes in cycle length. This work presents results of a novel device named the micro flux monitor, which is a miniaturized neutron dosimeter made from small quantities (100s of nanograms) of Ti, Al, Ni, and Au metals deposited on Si and high-purity fused silica substrates using standard semiconductor fabrication techniques. Approximately 1,250 of these devices were produced, and 40 were irradiated in the pneumatic tube facility of the Neutron Activation Analysis Laboratory at the High Flux Isotope Reactor. Testing demonstrated that dosimeter metals can be deposited predictably and repeatedly in multiple geometries, including as quick response (QR) codes. Neutron flux measurements with these devices were within 3% of measurements made using standard flux monitors, demonstrating the efficacy of these devices. Devices were also tested at 500°C under a N2 atmosphere and showed minimal degradation, suggesting they could be deployed for neutron dosimetry measurements in high-temperature advanced reactors.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2025

Calculating the Effects of Solids Input and Removal as a Temperature Control in the Advanced Scale Up Reactor Experiment (ASURE) Facility at NETL Using Aspen

The Advanced Scale Up Reactor Experiment (ASURE) facility at NETL is being designed to be a fuel-flexible multi-purpose reactor that can be used for pyrolysis/gasification or evaluation of other high pressure “circulating fluidized bed” (CFB) chemical processes. The initial system design calculations for pyrolysis/gasification are presented in this work showing the expected performance of the ASURE facility when used as a biomass conversion reactor. Several other areas of application include gasification of any carbonaceous fuel including biomass, coal, plastics, and other waste materials. The reactor can therefore be used to produce SYNGAS of various compositions and hydrogen as well as other high value chemicals resulting from a typical tuned gasification process. This paper discusses an ASPEN model of the facility, focusing on the riser of the CFB reactor and the solids recirculation loop. The ASPEN model divides the riser into two sections. A bottom section which receives ash, char and sand which have been recirculated from a return loop. In this section an inert fluidization gas, (N2 or CO2), is introduced which acts as the primary mover of the solids through the system. The bottom section is equipped with a restricted air feed so that the recirculated char can be partially oxidized. This oxidation process along with the inventory of recirculating sand are used to effectively control the temperature in the following two chemical conversion sections of the reactor which are the pyrolysis zone followed by a tar cracking zone. Fresh fuel is added to the pyrolysis zone and undergoes drying and devolatilization. The products ash, char, volatile matter, and water vapor exit the pyrolysis zone and enter the reaction block for tar cracking. Steam and CO2 gasification reactions will be incorporated into the tar cracking zone, however at the design operating temperature, conversion from these reactions is expected to be essentially zero. The unit when completed in 2026 will test mixtures of biomass, plastics, and waste coal. This presentation discusses the basic ASPEN engineering design model for this project and provides preliminary sensitivity studies to determine how the various parts of the reactor will perform.

ASSURE↗
DOE OSTI2025

Combined TDLAS and chemiluminescence imaging in a flat flame burner operated with NH3/H2 blends

Ammonia is viewed as a viable hydrogen carrier due to favorable storage and transport characteristics. While it can be re-converted to hydrogen at point-of-use via thermal catalytic cracking, direct utilization in combustion systems can result in reduced costs and improved efficiency. A major barrier to this approach is the low flammability and potential for high nitrogen oxide emissions, driven by fuel-bound nitrogen and complex kinetic pathways. While a number of kinetic mechanisms currently exist for simulating ammonia combustion, a major need continues to be direct information about species profiles in easy-to-model systems capable of isolating chemical kinetics from multi-dimensional fluid dynamic effects. This paper reports on recent species measurements made in a flat flame burner using a combined tunable-diode-laser-absorption-spectroscopy (TDLAS) and chemiluminescence imaging approach. Three flame conditions were included representative of NH3/H2 blends, partially cracked NH3 (inc. N2), and 100% NH3 with enhanced air (30% oxygen). Two NIR distributed feedback (DFB) laser diodes were used to determine H2O concentration and temperature (via ratio thermometry) at various radial and axial positions, after which an inverse Abel transform was used to infer centerline values. Companion images were collected using a Princeton Instrument PI-MAX intensified camera equipped with a 105mm UV lens and multiple filter sets targeting OH*, NH*, and NH2* emission. Results were compared to companion Cantera burner-stabilized flame simulations using various kinetic mechanisms. A recent mechanism including excited species chemistry was also included, to investigate whether excited and ground state profiles exhibit significant differences.

ammonia combustion↗
DOE OSTI2025

Improving Stability of an Optical Fiber pH Sensor with a Calcined Polyethylenimine-Coating at High Pressures and Temperatures

With an increased interest in subsurface gas storage technology for various energy applications, monitoring wellbore structural stability and subsurface geochemistry has become more pressing, and pH is a key parameter to measure. As high pressure and elevated temperatures in subsurface conditions are comparatively harsh relative to that expected for most standard pH sensor designs, any pH monitoring hardware must be designed for extended exposure to high pressures and temperatures. We previously reported that an optical fiber pH sensor functionalized with a calcined polyethylenimine coating had shown some promise as a high temperature and pressure pH sensor but with some drifting when operating for longer than 8 hours. In this paper, we investigated the coating composition and potential cause of the drifting and improved the stability of the prepared coating to minimize sensor drift under simulated wellbore conditions. Scanning electron microscopy (SEM) had previously shown moderate cracking at high pressures over short tests. By applying X-ray photoelectron spectroscopy (XPS) to characterize the sensor coating before and after one week of testing in an H2/CH4 gas blend at 80 °C and 900 psi, a compositional change in the coating was observable, which may indicate susceptibility to alteration by subsurface gas storage conditions. Non-reducing (CH4, N2) environments were also tested, and confirmed that both temperature and pressure were also contributing to the drift.

energy infrastructure↗