Influence of Different Core Mechanisms on Low-Temperature Combustion Characteristics of Large Hydrocarbon Fuels

The
core mechanism is the cornerstone of combustion reaction kinetic
models and has a crucial impact on the prediction accuracy of large
hydrocarbon combustion mechanisms. At present, there remains no systematic
method to compare the effect of different core mechanisms on the combustion
mechanisms of large hydrocarbons. In this work, the effects of popular
core mechanisms such as AramcoMech1.3, USC Mech II, AramcoMech3.0,
and Foundational Fuel Chemistry Model (FFCM-1) on the combustion mechanisms
of a large hydrocarbon were compared. Based on these core mechanisms,
the low-temperature combustion mechanisms of the large hydrocarbon
(taking n-heptane as an example) have been developed.
Meanwhile, the detailed numerical simulation and analysis of these
mechanisms have been carried out. Concretely, using automatic generation
software ReaxGen, coupled with AramcoMech1.3, USC Mech II, AramcoMech3.0,
and FFCM-1, the detailed mechanisms named Mechanism-1­(AramcoMech1.3),
Mechanism-2­(USC Mech II), Mechanism-3­(AramcoMech3.0), and Mechanism-4­(FFCM-1)
for low-temperature combustion of n-heptane have
been developed. Among them, the Mechanism-2­(USC Mech II) can be referred
to our previous work (http://www.cnki.com.cn/Article/CJFDTotal-GCRB201411041.htm).
These mechanisms were validated by the ignition delay time and concentration
profiles of important species. Numerically predicted results show
that Mechanism-1­(AramcoMech1.3) is in better agreement with available
experimental data than those of other mechanisms. Finally, the sensitivity
analysis of these mechanisms was carried out to find the key reactions
to ignition sensitivity under low-temperature combustion conditions,
and to better understand the models’ predicted performance,
the differences in reaction pathway analysis of n-heptane were discussed.