Development and Implementation of a Novel Element Tracing Method for a Reaction Path Analysis and its Application on a NOx Path Analysis for Deflagration and Detonation Processes
Creators: name: Coulmann, Oliver
Publisher: name: Zenodo
Year: 2021
Subjects: Combustion Kinetics, Reaction Path Analysis, NOx Formation, Algorithm, Python

description: As pollutant emissions limits are reduced, and a greater thermal efficiency of technical<br> combustion systems is desired, knowledge of the underlying kinetic formation mechanisms<br> of pollutants will continue to gain in importance. The development of new combustion<br> concepts, such as pulsed detonation combustion (PDC), and the viability of such<br> concepts as feasible technical systems further increases the need for reliable pollutant<br> formation prediction. This work examines pollutant formation within combustion processes.<br> In particular, the underlying kinetic mechanisms for the formation of nitrogen<br> monoxide (NO) in such processes are investigated. Over time, as more NO formation<br> mechanisms have been identified, and experimental measurements and estimates of reaction<br> rates have improved, chemical kinetic reaction mechanisms have become increasingly<br> detailed. Due to the increased size and complexity of these chemical kinetic reaction<br> mechanisms, differentiating between contributions to total NO formation from various<br> sub-mechanisms has become increasingly difficult. The differentiation of contributions<br> from various sub-mechanisms is further complicated by the fact that many reactions critical<br> to NO formation do not belong exclusively to one sub-mechanism, but are instead<br> shared between many.<br> An algorithm was developed which implements and expands on a novel element tracing<br> method for determining the total formation of a user defined target species, as well<br> as the contributions from individual formation sub-mechanisms. In this work, the algorithm<br> was used to predict NO formation. By tracing the flux of nitrogen from initiation<br> reactions, through all nitrogen containing intermediate species and subsequently to the<br> oxidation to NO, the net flux to and from NO can be determined and distributed among<br> the individual sub-mechanisms accordingly. The developed algorithm traces the flux<br> through all intermediate species at each flame position, resulting in a reaction path analysis<br> of the simulated combustion process. The algorithm was validated using results<br> from the literature for a range of deflagration flames, including freely propagating, stoichiometric<br> methane and propane flames, and burner stabilised flat flames at different<br> equivalence ratios. The results demonstrated an improved performance for capturing<br> total NO formation and the determination of sub-mechanism contributions compared<br> to results from the literature. The applicability of the algorithm for the analysis of detonation<br> processes was also examined and confirmed, and a reaction path analysis of a<br> stoichiometric methane detonation wave conducted. The developed algorithm presents<br> a useful tool for the investigation of pollutant formation in a wide range of combustion<br> processes.