Autoignition delay times of propane mixtures under MILD conditions at atmospheric pressure

The aim of the present work was to obtain experimental reference data in controlled, simple systems collected under MILD combustion. The combustion processes evolving under such conditions show behaviors specific to unique ranges of operating conditions that are not predictable using the available kinetic mechanisms. Experimental tests were conducted in a tubular flow reactor for propane/oxygen mixtures diluted in nitrogen under MILD combustion conditions by varying the mixture composition (from fuel-lean to fuel-rich conditions) and the dilution level over a wide range of temperatures (850-1250 K) at atmospheric pressure. Several combustion regimes were identified as a function of these external parameters. Auto-ignition delay times were evaluated, and they showed different levels of dependence on the system inlet temperature for intermediate to high temperatures. Under MILD combustion conditions, numerical simulations based on several available kinetic models predicted results with weak correlations to the experimental data, especially under fuel-rich, highly diluted conditions. To identify the controlling reaction pathways that should be tuned to extend the validity of models to wider operating conditions, sensitivity and reaction flux analyses were used. However, this topic is outside of the scope of the present work This study provides reproducible experimental data for a reference system under novel conditions. (C) 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved.