Contributions of Experimental Data Obtained in Concentrated Mixtures to Kinetic Studies: Application to Monomethylhydrazine Pyrolysis

Abstract

Experimental, numerical and theoretical studies are performed to understand the explosive thermal decomposition of monomethylhydrazine/argon mixtures. Ignition delays of concentrated MMH/Ar mixtures (20-30%) have been measured behind a reflected shock wave around 1000 K and 1 atm.Although several detailed chemical kinetic models have predictive abilities for diluted and highly diluted mixtures, none of them showed predictive for concentrated mixtures. A new kinetic model is proposed, in which numerous rate constants and thermochemical data are reassessed based on theoretical calculations, with the purpose to determine whether,or to what extent, trends derived from diluted or highly diluted MMH/Ar mixtures can explain observations in concentrated MMH mixtures. The present kinetic model is found to predict speciation experimental profiles in diluted MMH/Ar mixtures and is a significant improvement in predicting theinduction delays of concentrated MMH/Ar mixtures.

New reactions of diazene and related species for modelling combustion of amine fuels

“…respectively. Similar results were recently obtained by Dievart and Catoire [46] and so we did not analyze the thermal rate constants further. These pathways, in the reverse direction, are also important for the decomposition of chemically activated N 2 H 3 formed from the addition of NH to NH 2 at energies, measured from v=0 for N 2 H 2 , of E ≥ 312.8 kJ mol −1 [37].…”

“…by Ruscic [37] and supported by a recent theoretical study [46]. This large error may have had implications for the earlier modeling studies.…”

“…Under conditions where the cis and trans isomers are equilibrated, E HNNH is predominant, but at combustion temperatures the cis form accounts for about 20 to 30% of total diazene [46].…”

“…Earlier work on H-abstraction from HNNH has focused on the trans isomer or assumed the E and Z isomers to be equilibrated [46,54,55,5759]. However, Dievart and Catoire [46] reported that the energy barriers for cis-isomer are consistently lower than those of the trans-isomer, by 6.3, 10.…”

Experimental and numerical analyses of nitrogen oxides formation in a high ammonia-low hydrogen blend using a tangential swirl burner

“…The thermodynamic data of nitrogen-related radicals, especially NH, NH 2 , NNH, and N 2 H 2 , were updated based on the work published by [49]. Also, the rate kinetics of the most important reactions, particularly those related to NO X formation, have been evaluated based on some experimental [50,51] and theoretical [43,49,[52][53][54][55] studies. Along with that, the numerical data from model prediction have been validated with JSR experimental measurements of oxidation on NH 3 -H 2 blended flames at atmospheric pressure, low -moderate temperatures (800-1280 K), different H 2 contents, 0-70VOL% in the fuel, and various equivalence ratios.…”