CT1-3: Difference of Reaction Schemes on Low Initial Temperature Conditions with LTO Reactions and High Initial Temperature Conditions Skipping Them(CT: Combustion, Thermal and Fluid Science,General Session Papers)

Abstract

By using "Contribution Matrices", the authors had clarified that a major reaction path during thermal ignition preparation phases of DME and n-heptane was a set of reactions named "H_2O_2 reaction loop", and suggested that it may be a universal rule that the heat accumulated by this loop plays a dominant role in preparing the thermal ignition. In the present study, this suggestion was confirmed by using a higher octane number fuel, iso-octane, and by changing the initial temperature. It was confirmed that in all cases, an ignition delay, a period of the thermal ignition preparation phase, depends on the H_2O_2 concentration at the beginning of this phase. Reaction path analyses on higher initial temperature conditions skipping reactions in LTO (cool flame) and NTC ranges result in lower H_2O_2 concentrations and lower heat release during thermal ignition preparation phases. Low and high octane number fuels show similar ignition characteristics when the initial temperature is higher than NTC range temperatures. When a low octane number fuel reacts at a lower initial temperature than NTC range temperatures, the fuel is given an "H_2O_2 bonus by LTO".