PEROXIDE-CLUSTER MECHANISM OF THE AUTOIGNITION INITIATION

Abstract

The paper examines the peroxide nature influence of the autoignition on this process phasing and the necessary changes in the method of the autoignition temperature calculation forecasting. The study is based on the assumption that the first elementary act that leads to autoignition is the supramolecular structure formation in the
peroxide-type cluster form. The work aim is to model the smallest supramolecular peroxide structure of hydrocarbons that occurs at the first stage of autognition in order to clarify the peroxide mechanism of the combustion this type development and increase the convergence of the autognition temperature calculated prediction. N-alkanes were chosen as the basic homologous series for modeling such structures. Non-linearity with the oscillations presence for autoignition temperatures in this homologous series was established, which is a sign of the supramolecular structures existence with different principles of its organization for different compounds, that is observed for the condensed state of matter. For the first moment of the autoignition processes initiation, the formation mechanism of the relationship between the the autoignition temperature nonlinearity change and the structure of the smallest possible peroxide-type clusters is determined. The alkyl peroxide cluster formation with a dimeric structure is foreseen, and for methane – additionally with a hexa- and for ethane – with a trimeric structure. Average equivalent lengths of these structures for a mixture of linear and cyclic alkyl peroxides were calculated. This dependence modulates the non-linearity of the autoignition temperature change. An analytical dependence of an approximate nature was developed to describe the autognition temperature, which works with a correlation coefficient of R=0.977 and an average deviation of 5.5 ^oС. The work novelty is the predicted cluster mechanism of the autoignition initiation and the corresponding variants of possible peroxide-type supramolecular structures, which made it possible to develop a new analytical dependence for predicting the autoignition temperature based on the values of these structures equivalent lengths and the stoichiometric coefficient of the substance combustion reaction.