Experimental Design for Discrimination of Chemical Kinetic Models for Oxy-Methane Combustion

Abstract

The concept of combustion under oxy-fuel conditions has the potential to reduce greenhouse gas emissions. For the design of combustion devices operating under these conditions, a good understanding of fuel oxidation behavior in terms of chemical kinetic mechanisms is useful. For the oxidation of the main component of natural gas and coal devolatilization products, i. e. methane, various chemical mechanisms are available in the literature validated mostly with experiments using air, and none of them is developed particularly or has been validated extensively for oxy-methane combustion. An important prerequisite for model assessment is high-quality data typically obtained from resource-and time-consuming measurements. The aim of this study is to identify the best methane mechanism for oxy-fuel combustion from a set of models available in the literature with a minimum number of measurements. Five chemical models, which have been validated for the oxidation of methane/air mixtures, are compared in terms of their performance for extinction strain rates, ignition delay times, and laminar burning velocities of oxy-methane mixtures. A model-based experimental design method, i. e. Akaike Weights Design Criterion, is applied to determine the optimal potential measurements. Ideally, at the conditions of designed experiments, model predictions are nicely separated and thus the best model can be identified by comparison with these measurements. It is shown that the employed experimental design strategy identifies informative experiments for model discrimination efficiently. While measurements of extinction strain rates are proposed to be carried out for flames with small methane mass fractions of the fuel stream and oxygen mass fractions of the oxidizer stream, shock tube experiments are evaluated as equally useful for model discrimination over the investigated range of conditions. Measurements of flame speeds are designed at very small and very large equivalence ratios particularly at relatively high pressures.

Molecular Dynamics Study of Combustion Reactions in Supercritical Environment. Part 3: Boxed MD Study of CH3 + HO2 → CH3O + OH Reaction Kinetics

“…Oxy-fuel combustion technology, where CO 2 replaces nitrogen as diluent to control the flame temperature, holds a great promise of increased energy efficiency, reduced nitroxide pollution, , and an opportunity for carbon sequestration. , In many studies the standard combustion mechanisms are presumed to be valid at CO 2 -reach conditions for data interpretation and modeling the flame composition, , or turbine design . Although several kinetic models for the methane combustion mechanism were developed, none of them was designed for oxy-combustion specifically. , These mechanisms involve a large number of elementary reactions, and some of them may be altered by the presence of carbon dioxide in large concentrations and high pressures …”

“…8 Although several kinetic models for the methane combustion mechanism were developed, none of them was designed for oxy-combustion specifically. 9,10 These mechanisms involve a large number of elementary reactions, and some of them may be altered by the presence of carbon dioxide in large concentrations and high pressures. 11 Recently we extended our efforts toward development and validation of kinetic mechanisms specific for oxy-fuel combustion.…”

The significance of beam steering on laser-induced incandescence measurements in laminar counterflow flames

“…The counterflow burner used in this study has been described previously [25]. A schematic of the counterflow setup is shown in Fig.…”

Analysis of the Ignition Behavior Based on Similarity Factor Method

“…At present, almost all mechanisms are verified by the experimental data from shock tubes and other basic reactors [19], which are considered the conventional mechanism. However, the recognition scope of such mechanisms is limited [20]. At the same time, there are few mechanisms constructed based on CVB experiments, so the ignition behavior of fuels in CVB usually cannot be accurately described by the conventional mechanism.…”

“…The specific reasons for the differences in the performance of the mechanisms in two reactors, and how to use the basic experiments to guide the mechanism construction while also considering the role of other experimental platforms such as the CVB, have not been fully investigated. How to identify informative experiments for mechanism discrimination efficiently [20]? That is the key, which needs to be considered at the beginning of the mechanism construction.…”