O₂/CO₂ 氛围下正庚烷的燃烧机理研究

In order to study the combustion characteristics of n-heptane under O₂/CO₂ atmosphere, a C-H combustion mechanism based on the detailed reaction paths of CO₂ and H· was proposed. The possible reaction paths of CO₂ and H· were analyzed by using density functional theory, and the calculation grids were established according to the actual size of constant volume combustion chamber. The combustion processes of n-heptane under different atmospheres (air, 53%O₂/47%CO₂, 61%O₂/39%CO₂) were calculated through C-H mechanism. A constant volume incendiary bomb visualization experiment platform was built to measure the combustion process of n-heptane in different atmospheres. The reaction site of CO₂, the reaction energy barrier of CO₂+H→ CO+·OH, and the flame length were analyzed. The results show that the C-H mechanism can well predict the combustion flame length of n-heptane under O₂/CO₂ atmosphere, and the maximum error and the average error are 9.60% and 2.42% respectively under 50%O₂/ 50%CO₂. The reactivity of oxygen atom of CO₂ is higher than that of carbon atom, and the average local ionization energy and molecular surface electrostatic potential at the oxygen ends are 297.72 and -13.08 kcal/mol, respectively. H· can combine with carbon atom and oxygen atom of CO₂, the reaction energy barrier are 26.71 and 11.07 kcal/mol, respectively.