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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 541 records · Page 30
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Ligand‐Based Control of Single‐Site vs. Multi‐Site Reactivity by a Trichromium Cluster

Abstract The trichromium cluster ( tbs L)Cr 3 (thf) ([ tbs L] 6− =[1,3,5‐C 6 H 9 (NC 6 H 4 ‐ o ‐NSi t BuMe 2 ) 3 ] 6− ) exhibits steric‐ and solvation‐controlled reactivity with organic azides to form three distinct products: reaction of ( tbs L)Cr 3 (thf) with benzyl azide forms a symmetrized bridging imido complex ( tbs L)Cr 3 ( μ 3 ‐NBn); reaction with mesityl azide in benzene affords a terminally bound imido complex ( tbs L)Cr 3 ( μ 1 ‐NMes); whereas the reaction with mesityl azide in THF leads to terminal N‐atom excision from the azide to yield the nitride complex ( tbs L)Cr 3 ( μ 3 ‐N). The reactivity of this complex demonstrates the ability of the cluster‐templating ligand to produce a well‐defined polynuclear transition metal cluster that can access distinct single‐site and cooperative reactivity controlled by either substrate steric demands or reaction media.

Bartholomew, Amymarie K.↗
DOE OSTI2019

Ligand-Based Control of Single-Site vs. Multi-Site Reactivity by a Trichromium Cluster

The trichromium cluster ( tbs L)Cr 3 (thf) ([ tbs L] 6– =[1,3,5-C 6 H 9 (NC 6 H 4 - o -NSi t BuMe 2 ) 3 ] 6– ) exhibits steric- and solvation-controlled reactivity with organic azides to form three distinct products: reaction of ( tbs L)Cr 3 (thf) with benzyl azide forms a symmetrized bridging imido complex ( tbs L)Cr 3 ( μ 3 -NBn); reaction with mesityl azide in benzene affords a terminally bound imido complex ( tbs L)Cr 3 ( μ 1 -NMes); whereas the reaction with mesityl azide in THF leads to terminal N-atom excision from the azide to yield the nitride complex ( tbs L)Cr 3 ( μ 3 -N). We report the reactivity of this complex demonstrates the ability of the cluster-templating ligand to produce a well-defined polynuclear transition metal cluster that can access distinct single-site and cooperative reactivity controlled by either substrate steric demands or reaction media.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Predicting wind farm operations with machine learning and the P2D‐RANS model: A case study for an AWAKEN site

Abstract The power performance and the wind velocity field of an onshore wind farm are predicted with machine learning models and the pseudo‐2D RANS model, then assessed against SCADA data. The wind farm under investigation is one of the sites involved with the American WAKE experimeNt (AWAKEN). The performed simulations enable predictions of the power capture at the farm and turbine levels while providing insights into the effects on power capture associated with wake interactions that operating upstream turbines induce, as well as the variability caused by atmospheric stability. The machine learning models show improved accuracy compared to the pseudo‐2D RANS model in the predictions of turbine power capture and farm power capture with roughly half the normalized error. The machine learning models also entail lower computational costs upon training. Further, the machine learning models provide predictions of the wind turbulence intensity at the turbine level for different wind and atmospheric conditions with very good accuracy, which is difficult to achieve through RANS modeling. Additionally, farm‐to‐farm interactions are noted, with adverse impacts on power predictions from both models.

17 WIND ENERGY↗
DOE OSTI2016

CO 2 Accounting and Risk Analysis for CO 2 Sequestration at Enhanced Oil Recovery Sites

Using CO2 in enhanced oil recovery (CO2-EOR) is a promising technology for emissions management because CO2-EOR can dramatically reduce sequestration costs in the absence of emissions policies that include incentives for carbon capture and storage. This study develops a multiscale statistical framework to perform CO2 accounting and risk analysis in an EOR environment at the Farnsworth Unit (FWU), Texas. A set of geostatistical- based Monte Carlo simulations of CO2-oil/gas-water flow and transport in the Morrow formation are conducted for global sensitivity and statistical analysis of the major risk metrics: CO2/water injection/production rates, cumulative net CO2 storage, cumulative oil/gas productions, and CO2 breakthrough time. The median and confidence intervals are estimated for quantifying uncertainty ranges of the risk metrics. A response-surface-based economic model has been derived to calculate the CO2-EOR profitability for the FWU site with a current oil price, which suggests that approximately 31% of the 1000 realizations can be profitable. If government carbon-tax credits are available, or the oil price goes up or CO2 capture and operating expenses reduce, more realizations would be profitable. The results from this study provide valuable insights for understanding CO2 storage potential and the corresponding environmental and economic risks of commercial-scale CO2- sequestration in depleted reservoirs.

Dai, Zhenxue↗