Abstract
The method of quantum chemistry was used to calculate
the activation energy of key elementary reactions in the natural gas mechanism
under the condition of low temperature combustion, so as to modify the
activation energy data in the original mechanism, and therefore improve the accuracy of natural gas mechanism to
predict the ignition delay time. Under different working conditions
(temperature of 900-1 200 K, pressures of 0.5, 1, 1.5
MPa, equivalent ratios of 0.5, 1.0, 1.5), three widely-used
detailed mechanisms (San Diego 2016, GRI 3.0, Aramco Mech 3.0) were compared
and analyzed. The Aramco Mech 3.0 mechanism which could predict the ignition
delay time accurately was determined as the research object, and the largest
sensitivity coefficient of reaction was
identified as the key fundamental reaction based on analysis of the sensitivity
of ignition delay time. Five quantitative calculation methods B3LYP, PM7, M06-2X, CBS-QB3 and W1RO were used to calculate
the activation energy of fundamental reaction. The activation energies
calculated by B3LYP, CBS-QB3 and W1RO were selected,
and the activation energies of key elementary reactions in the original
mechanism were updated, and three different new mechanisms were hence obtained.
The ignition delay time obtained by coupling calculation of the three
mechanisms and detailed mechanisms with the closed homogeneous reactor model
were compared with the experimental values. The results show that the average
activation energy calculated by B3LYP method is 212.34 kJ/mol when the
temperature is 900-1 200 K. Using the data to correct
the activation energy in the original mechanism, the corrected new mechanism
can predict the ignition delay time more accurately, and is more suitable for
low-temperature combustion conditions.
Key words
natural gas /
quantum chemical calculation /
activation
energy /
chemical reaction mechanism
Cite this article
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ZHANG Jun, MAO Gongping, QI Hong.
Prediction Accuracy Improvement of Natural Gas
Combustion Mechanisms for Ignition Delay Time[J]. Vehicle Engine. 2025, 0(2): 73 https://doi.org/10.3969/j.issn.1001-2222.2025.02.011
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