Combustion Characteristics of C5 Alcohols and a Skeletal Mechanism for Homogeneous Charge Compression Ignition Combustion Simulation

C-5 alcohols are considered alternative fuels because they emit less greenhouse gases and fewer harmful pollutants. In this study, the combustion characteristics of 2-methylbutanol (2-methyl-1-butanol) and isopentanol (3-methyl-1-butanol) and their mixtures with primary reference fuels (PRFs) were studied using a detailed chemical kinetic model obtained from merging previously published mechanisms. Ignition delay times of the C-5 alcohol/air mixtures were compared to PRFs at 20 and 40 atm. Reaction path analyses were conducted at intermediate and high temperatures to identify the most influential reactions controlling ignition of C-5 alcohols. The direct relation graph with expert knowledge methodology was used to eliminate unimportant species and reactions in the detailed mechanism, and the resulting skeletal mechanism was tested at various homogeneous charge compression ignition (HCCI) engine combustion conditions. These simulations were used to investigate the heat release characteristics of the methyl-substituted C-5 alcohols, and the results show relatively strong reactions at intermediate temperatures prior to hot ignition. C-5 alcohol blending in PRF75 in HCCI combustion leads to a significant decrease of low-temperature heat release (LTHR) and a delay of the main combustion. The heat release features demonstrated by C-5 alcohols can be used to improve the design and operation of advanced engine technologies.