ABSTRACT To study the diesel combustion characteristics under CO 2 /O 2 atmosphere, the C─H mechanism for diesel surrogate fuel (DSF, 30% toluene + 70% n‐heptane) is proposed. Firstly, the potential energy surfaces of the carbon and oxygen atoms in CO 2 attacked by H radical are calculated using density functional theory (DFT), and the C─H mechanism is proposed by coupling the new paths with the simplified mechanism. Secondly, a constant volume combustion chamber (CVCC) experiment platform is set up, and the flame images are captured under four combustion atmospheres (air, 50% CO 2 /50% O 2 , 47% CO 2 /53% O 2 , 39% CO 2 /61% O 2 ). Finally, the reaction sites of CO 2 , the free energy barrier, the temperature sensitivity, the species concentration changes, the flame temperature cloud diagrams, and the combustion flame length (CFL) are analyzed. The results show that the C─H mechanism is suitable for studying the combustion characteristics of DSF under CO 2 /O 2 atmosphere and the maximum error of CFL is 6.93%. There are two reaction paths for CO 2 +H•→CO+•OH at high temperature and pressure, and the free energy barriers for binding to carbon and oxygen atoms are 26.71 kcal/mol and 11.07 kcal/mol, which indicates that Path 1 is more likely than Path 2.
Liu et al. (2026) studied this question.