Flame burning speeds and combustion characteristics of undiluted and nitrogen-diluted hydrogen–nitrous oxide mixtures

Abstract

In the present study, some explosive properties of undiluted and nitrogen diluted H 2-N 2 O mixtures were characterized. Laminar burning speeds and the explosioninduced pressure rises were determined experimentally for a range of mixture equivalence ratios (φ = 0.15 − 1.0), dilutions (0 − 55% N 2), and initial pressures (20 − 80 kPa). The measured burning speeds were used to validate laminar burning speed computations using a detailed chemical kinetic mechanism. The computations were then used to estimate burning speeds at high initial pressure and low dilution conditions that could not be measured experimentally. The results demonstrate that hydrogennitrous oxide mixtures exhibit laminar burning speeds as large as 350 cm/s and pressure rise coefficients (K g) as large as 35 MPa•m/s. Also, flames in lean mixtures are shown to be highly unstable which can lead to flame acceleration and possible deflagration-to-detonation transition.

Assessing the predictions of a NO x kinetic mechanism on recent hydrogen and syngas experimental data

“…To investigate these processes at a more fundamental level, a number of studies involving the pyrolysis of N2O and the oxidation of hydrogen/NOx and syngas/NOx have been performed in shock tubes [8,[16][17][18][19][20][21][22][23][24][25][26][27], jet-stirred reactors (JSR) [28][29][30], flow reactors (FR) [9,10,31,32] and spherical expanding laminar flames [33,34]. Simultaneously, many relative kinetic mechanisms [9,10,13,28,32,[35][36][37][38][39][40][41][42][43] have also been proposed to improve our understanding of NOx formation and to develop NOx control strategies.…”

“…Comparison of experiments and model predictions for the laminar flame speeds in H2/N2O/dilution system; lines denote model simulation with the current mechanism. Symbols represent experimental measurements for (a) H2/N2O diluted by 60% Ar at 1.0 atm and 300 K taken from Mével et al[33] and for (b) H2/N2O undiluted at 0.2 atm and 298 K taken from Bane et al[34].…”

Detonation in hydrogen–nitrous oxide–diluent mixtures: An experimental and numerical study

“…Previous studies on hydrogen-nitrous oxide mixtures have generated data sets on the ignition delay time [15,16,17,18,19,20,21,22,23,24,25,26], the laminar burning speed [27,28,29,30,31,32,33,34,35], and the minimum ignition energy [36]. Concerning detonation, Zhang et al measured the critical energy for direct initiation [37] and the cell sizes have been measured [38,39] in the frame work of nuclear waste storage risk assessment.…”

Assessing the Predictions of A NOx Kinetic Mechanism on Recent Hydrogen and Syngas Experimental Data

“…To investigate these processes at a more fundamental level, a number of studies involving the pyrolysis of N2O and the oxidation of hydrogen/NOx and syngas/NOx have been performed in shock tubes [8,[16][17][18][19][20][21][22][23][24][25][26][27], jet-stirred reactors (JSR) [28][29][30], flow reactors (FR) [9,10,31,32] and spherical expanding laminar flames [33,34]. Simultaneously, many relative kinetic mechanisms [9,10,13,28,32,[35][36][37][38][39][40][41][42][43] have also been proposed to improve our understanding of NOx formation and to develop NOx control strategies.…”