Twenty-species and 15-species chemical kinetic mechanisms for cyclohexane using the local self-similarity tabulation method

Abstract

The 1081 species cyclohexane‐oxidation elementary reaction mechanism of Silke et al. (DOI:10.1021/jp067592d) is reduced in the number of species by a O(10²) factor using the local self‐similarity tabulation (LS2T) method. Reduced‐species mechanisms of both 20 (R20) and 15 (R15) species are created in the high‐pressure combustion regime typical of diesel engines. To evaluate the performance of R20 and R15 against the elementary kinetics, simulations are performed for cyclohexane/air mixtures at initial temperatures of 1150, 900, 750, and 680 K and constant pressures of 20 and 40 bar for a variety of equivalence ratios Φ (Φ = 0.5, 1.0, and 2 for 1150 and 900 K; Φ = 1 for 750 K; Φ = 0.5 for 680 K). Very good agreement between R20 and R15 with the elementary kinetics mechanism is demonstrated at 1150 and 900 K for which the self‐similarity is very well obeyed; however, only fair agreement is obtained at 750 and 680 K, a fact which is traced to the less faithful adherence to the self‐similarity due to the one order of magnitude increase in ignition time over the range 750‐680 K. These results are found to be quasi‐independent of the tabulation grid. Future work is proposed to improve the reduction in the cold‐ignition, high‐pressure regime.

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