An estimate of Sandia resources for underground nuclear weapons effects testing.

We conducted a study of the time and resources that would be required for Sandia National Laboratories to once again perform nuclear weapons effects experiments of the sort that it did in the past. The study is predicated on the assumptions that if underground nuclear weapons effects testing (UG/NWET) is ever resumed, (1) a brief series of tests (i.e., 2-3) would be done, and (2) all required resources other than those specific to SNL experiments would be provided by others. The questions that we sought to answer were: (1) What experiments would SNL want to do and why? (2) How much would they cost? (3) How long would they take to field? To answer these questions, we convened panels of subject matter experts first to identify five experiments representative of those that SNL has done in the past, and then to determine the costs and timelines to design, fabricate and field each of them. We found that it would cost $76M to$84M to do all five experiments, including 164 to 174 FTEs to conduct all five experiments in a single test. Planning and expenditures for some of the experiments needed to start as early as 5.5 years prior to zero-day, and some work would continue up to 2 years beyond the event. Using experienced personnel as mentors, SNL could probably field such experiments within the next five years. However, beyond that time frame, loss of personnel would place us in the position of essentially starting over

Insights into nitromethane combustion from detailed kinetic modeling – Pyrolysis experiments in jet-stirred and flow reactors

International audienceThe pyrolysis of nitromethane highly diluted in helium was studied in a plug flow reactor and in a jet-stirred reactor at 1.07 bar and over the temperature range from 500 to 1100 K. Mole fraction profiles of major products and of intermediates were identified with gas chromatography and Fourier transform infrared spectroscopy. Using these experimental data, as well as published ones, we have developed a newly compiled model for the prediction of the pyrolysis and of the oxidation of nitromethane in jet-stirred and flow reactors, freely propagating, and burner-stabilized premixed flames, as well as in shock-tubes. The experimental results from the present work and from the literature are interpreted with the help of the kinetic model derived here. This study mainly focuses on the analysis of speciation in different reactors. Among the nitrogenous species, NO is found to be a major product for pyrolysis and oxidation. The model suggests that for nitromethane pyrolysis and oxidation the thermal dissociation channel to CH3 and NO2 is the main reaction path for the nitromethane degradation followed by the H-atom abstraction channel. The most sensitive reactions for nitromethane pyrolysis in a flow reactor and during pyrolysis and oxidation in a jet-stirred reactor are found to be CH3NO2(+M) ⇋ CH3 + NO2(+M) and CH3 + NO2 ⇋ CH3O + NO. The reaction CH3 + NO2 ⇋ CH3O + NO is found to be the most important reaction for all conditions studied. In a burner-stabilized premixed flame, as the mixture gets richer, the thermal dissociation channel CH3NO2(+M) ⇋ CH3 + NO2(+M) becomes more important as the contribution of the H-atom abstraction channel is decreased. Furthermore, in the burner-stabilized premixed flames, it was found that NO is mainly formed via NO2: NO2 + H ⇋ NO + OH, NO2 + CH3 ⇋ CH3O + NO. The model provided an overall reasonable agreement with the experimental data. However, for pyrolysis conditions, future work is desirable to improve predictions of intermediate species. This work extends the kinetic database and helps to improve the understanding of nitromethane chemistry. The kinetic model presented in this work can serve as a base model for hydrocarbons and oxygenated fuels higher than C2 and nitrogen-containing compounds higher than C1 as well as for pure nitrogen compounds

PROPERTIES OF SIZE SELECTED SODIUM DOPED SOLVENT CLUSTERS

Author Institution: Max-Planck-Institut fur Dynamik und Selbstorganisation, Bunsenstr. 10, D-37073 Gottingen, Germany; Institut fur Physikalische Chemie, Universitat Gottingen, Tammannstr. 6, D-37077 Gottingen, GermanyThe properties of hydrogen bonded solvent clusters are investigated with a size selective molecular beam experiment. The doped solvent clusters were generated in a continuous supersonic pinhole expansion and were photoionized by a tunable dye laser system, follwed by mass analysis in a reflectron time-of-flight mass spectrometer.\\ Sodium doped ammonia clusters show a strong size dependence of the ionization potential (IP). It decreases with the size of the clusters} \textbf{122}, 2005, 134301.}. The IPs of sodium doped water clusters $\mathrm{Na(H_2O)_n}$ only show a size dependent decrease for clusters up to n=4. For larger clusters a constant IP is found} \textbf{67}, 1991, 1767-1770.}.\\ The IPs provide important information on the cluster structures. Currently, size selective properties of sodium doped methanol clusters are being investigated, to learn more about the structures of these clusters and the solvated electrons.\

Reaction Kinetics of Combustion Processes in the Gas Phase: Spectroscopic Studies of Reaction Rates, Products and Mechansims of Elementary Reactions and the Modeling of the Oxidation of Hydrocarbons with Detailed Reaction Mechanisms

Die Verbrennung von Kohlenwasserstoffen stellt nach wie vor die mit Abstand wichtigste Energiequelle dar. Die Optimierung der Verbrennungsprozesse bezüglich Wirkungsgrad und Schadstoffemissionen sind aktuelle Forschungsschwerpunkte. Für ein detailliertes Verständnis ist eine Charakterisierung der zugrundeliegenden chemischen Elementarreaktionen erforderlich. In dieser Arbeit werden die Reaktionen verschiedener Alkylradikale mit Sauerstoff-Atomen in der Gasphase bezüglich Primärprodukten, Mechanismen und Geschwindigkeiten untersucht. Die kinetischen Daten wurden in einer quasi-statischen Reaktor mittels Nachweis über Laserinduzierte Fluoreszenz gewonnen. Die Reaktanten wurden durch Laserphotolyse erzeugt. Die Produktkanalverteilungen wurden durch FT-IR-Produktanalyse stabiler Endprodukte in einer statischen Reaktionszelle bestimmt. Auch hier erfolgte die Erzeugung der Radikale und O-Atome über Laserphotolyse geeigneter Vorläufersubstanzen.Zur Untersuchung der Oxidation von Kohlenwasserstoffen und der Bildung des Russvorläufers Benzol wurde ein detaillierter Reaktionsmechanismus erstellt und zur Berechnung von Flammengeschwindigkeiten, Zündverzugszeiten und Flammenstrukturen eingesetzt. Dabei wurden die Ergebnisse der Untersuchungen der Elementarreaktionen in den Gesamtmechanismus eingebaut.Die Möglichkeit, chemische Reaktionen zeitaufgelöst (5 µs) mittels FT-IR-Step-Scan- Absorptionsspektroskopie zu verfolgen, wurde am Beispiel der Reaktion von Ethylradikalen mit molekularem Sauerstoff demonstriert

Detailed mass spectrometric and modeling study of isomeric butene flames

Schenk M, Leon L, Moshammer K, et al. Detailed mass spectrometric and modeling study of isomeric butene flames. COMBUSTION AND FLAME. 2013;160(3):487-503

The effect of diluents on the formation rate of nitrogen oxide in a premixed laminar flame

New high-efficiency power cycles and environmentally friendly cycles have introduced combustion atmospheres that differ from the traditional hydrocarbon-air mixtures. Wet cycles, solid oxide fuel cell with a gas turbine (SOFC-GT), CO2 separation/capture and biogas combustion are processes that involve high concentrations of inert gases such as H 2O, CO2 and N2. These new combustion atmospheres have not been well characterized for premixed flames, hence greater interest is attached how NOX formation is affected. At combustion temperatures above 1800 K, NOX emission is dominated by thermal NOX. The thermal NOX mechanism consists of three elementary reactions. The process is known to be exponential in combustion temperature, but it is also comparably slow and thus dependent on the residence time and the temperature in the post-flame zone. To model the flame, code for a one-dimensional flame with detailed chemistry was used. The flame code solves the combustion evolvement for a one-dimensional, premixed laminar flame. Detailed chemistry was used to model the chemical kinetics. NOX production was described by a NOX mechanism, including thermal, prompt and N2O intermediate. Altogether, the mechanisms consisted of 116 species and 713 reactions. The cases investigated were all premixed flames, diluted with either H2O, CO2, N2 or Ar. The cases used a constant combustion temperature of 2000 K and different pressure levels. All cases were investigated at constant inlet air-fuel temperature and varying equivalence ratio. The rate of formation of NO was investigated for both natural gas and hydrogen flames. The rate of formation of NO is reduced by the addition of any diluents at constant combustion temperature if the O-atom concentration is reduced in the high temperature post-flame zone. The computations show equilibrium between O and O2, and the reduced rates of formation of NO (at constant temperature) are thus simply the result of reduction in the product [O2]0.5[N2] in the post-flame zone

Modeling of NO x Formation and Consumption during Oxidation of Small Alcohols

This work presents a newly developed kinetic mechanism extending our recent work (Shrestha et al. [1]) for the oxidation of methanol and ethanol and their fuel interaction with NO x chemistry in jet-stirred reactors, flow reactors, and burner-stabilized premixed flames. The work mainly focuses on fuel interaction with nitrogen chemistry and NO formation in laminar premixed flames. It is found that for methanol oxidation in jet-stirred reactor doping of the fuel blends with NO increase the reactivity of the system by increasing the net production of OH radicals. The increased amount of OH is formed via NO/NO 2 interconversion reaction channels NO+HO 2 ⇋NO 2 +OH, NO 2 +H⇋NO+OH, NO 2 +HO 2 ⇋HONO+O 2, followed by the thermal decomposition of HONO producing NO and OH. In burner-stabilized premixed flames studied here for methanol/air and ethanol/air, NO is mainly formed via the NCN route (CH+N 2 ⇋NCN+H) and minor contribution comes from the NNH route (NNN⇋N 2 +H)

Modeling of NO x Formation and Consumption during Oxidation of Small Alcohols

This work presents a newly developed kinetic mechanism extending our recent work (Shrestha et al. [1]) for the oxidation of methanol and ethanol and their fuel interaction with NO x chemistry in jet-stirred reactors, flow reactors, and burner-stabilized premixed flames. The work mainly focuses on fuel interaction with nitrogen chemistry and NO formation in laminar premixed flames. It is found that for methanol oxidation in jet-stirred reactor doping of the fuel blends with NO increase the reactivity of the system by increasing the net production of OH radicals. The increased amount of OH is formed via NO/NO 2 interconversion reaction channels NO+HO 2 ⇋NO 2 +OH, NO 2 +H⇋NO+OH, NO 2 +HO 2 ⇋HONO+O 2, followed by the thermal decomposition of HONO producing NO and OH. In burner-stabilized premixed flames studied here for methanol/air and ethanol/air, NO is mainly formed via the NCN route (CH+N 2 ⇋NCN+H) and minor contribution comes from the NNH route (NNN⇋N 2 +H)