Nitromethane pyrolysis in shock tubes and a micro flow reactor with a controlled temperature profile

Nitromethane has many applications, such as in racing, as a gasoline fuel additive, and as a monopropellant. Despite a large number of studies and the small size of the molecule, the combustion chemistry of nitromethane is still not well understood. To improve models, the pyrolysis of nitromethane (CH 3 NO 2 ) was investigated experimentally in shock tubes and in a micro flow reactor with a controlled temperature profile (MFR), under dilute conditions. Several spectroscopic diagnostics were used in the shock tubes to follow the concentration time histories of CO, H 2 O (both using IR laser absorption), and CH 3 NO 2 (UV light absorption). A quadrupole mass spectrometer was used to measure CH 3 NO 2 , NO 2 , CH 4 , C 2 H 4 , and C 2 H 2 at various temperatures with the MFR. These unique experimental results were compared to modern, detailed kinetics models from the literature, and no mechanism was able to reproduce these data over the wide range of conditions investigated. Predictions for the CO and H 2 O levels were generally inaccurate, and the CH 4 , C 2 H 4 , and C 2 H 2 predictions were poor in most cases for the MFR data. Importantly, all models largely differ in their predictions. A numerical analysis was performed to identify ways to improve the next generation of nitromethane models. Results indicate that nitromethane decomposition needs to be improved below 1050 K, and that hydrocarbon-NOx interactions still need to be further investigated. (c) 2020 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

Automated summary

Nitromethane is widely used in various applications, but its combustion chemistry remains poorly understood. Experimental studies show that existing models struggle to accurately predict nitromethane decomposition, highlighting the need for improvement in nitromethane models to enhance prediction accuracy.