Development of skeletal oxidation mechanisms for linear alcohols from C4 to C10 based upon reaction rate rules

• Published in: Combustion and flame 2022-11, Vol.245, p.112351, Article 112351
• Main Authors: Chang, Yachao, Jia, Ming, Huang, Shuai, Zhang, Hongda, Cai, Liming
• Format: Article
• Language: English
• Subjects: Decoupling methodology; Higher linear alcohols; Hydroxyl functional group; Reaction rate rules; Skeletal oxidation mechanism
• ISSN: 0010-2180; 1556-2921
• DOI: 10.1016/j.combustflame.2022.112351

Higher alcohols are potential surrogate fuels for engines because of their large cetane number and multiple sources from non-food crops. The detailed chemical mechanisms of higher alcohols are usually constructed based on reaction rate rules. In the present study, reaction rate rules are utilized to construct the skeletal mechanisms of the linear alcohols from C4 to C10 under the framework of the decoupling methodology. Because of the existence of the OH group in alcohol, the low-temperature oxidation paths are different for different fuel radicals. To accurately characterize the dynamics of the competing low-temperature oxidation paths involving different fuel radicals, the isomer lumping method is utilized to compute the reaction rates of the retained reactions to establish the skeletal mechanism of the base fuel. Moreover, the rate constants of the retained reactions for n-butanol are different from that of other higher linear alcohols because of its shorter carbon chain, which is also considered in the procedure of the skeletal mechanism deduction using the reaction rate rules. The final skeletal mechanism contains ∼50 species and ∼210 reactions (8 irreversible reactions) for each alcohol. The performance of the series of skeletal mechanisms is evaluated by comparing the measured and calculated data in shock tube, jet-stirred reactor (JSR), premixed and opposed flame for all the investigated fuels over T = 298–2000 K, p = 0.04–80 atm, and φ=0.35–3.5. Considering the experimental uncertainties, the present skeletal mechanism is capable of satisfactorily reproducing the measured data, especially for ignition delay time and laminar flame speed, which verifies the rationality of the present method. However, some discrepancies still exist in the concentrations of the C2 and C3 species because of the extremely reduced C2–C3 sub-mechanism being employed in the present skeletal mechanism.