A new model for predicting antiknock quality of hydrocarbon fuel blends

• Published in: Fuel (Guildford) 2019-01, Vol.235, p.208-217
• Main Authors: Santos, Dinarte, Bassani, Irionson Antônio, da Silva, Claudio Ávila, Velásquez, José Antonio
• Format: Article
• Language: English
• Subjects: Combustion chambers; Compression; Compression ratio; Critical compression ratio; Cylinders; Engines; Fuel antiknock quality; Fuel-air ratio; Fuels; Hydrocarbons; Kinetics; Knock; Knock in spark ignition engines; Liquefied petroleum gas; Mixtures; Octane blending rule; Octane number; Physical properties; Reaction kinetics; Thermodynamic models; Thermodynamics
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2018.07.068

•A blending rule to compute CCRs and ONs of fuel blends was developed.•The developed model is based on the underlying physics of the knocking phenomenon.•Fuel knocking propensity was expressed as a power-law function of the CCR.•MONs of paraffinic fuel blends were predicted with standard error less than 0.5.•RONs of LPG mixtures were predicted with standard error of 0.7 ON-units. A procedure for predicting the Critical Compression Ratio (CCR) and the Octane Number (ON) of hydrocarbon fuel blends is presented in this work. Compositional data as well as antiknock characteristics and thermo-physical properties of the constituent hydrocarbons are taken as input parameters for this calculation. The proposed methodology was developed by considering single-step kinetics for the pre-flame reactions taking place within the combustion chamber of the CFR engine, which is the standard apparatus used in ON evaluation tests. Furthermore, a thermodynamic model was used to describe the relevant processes the in-cylinder fuel-air mixture undergoes prior to the occurrence of knock. In order to validate the proposed method, CCRs of Primary Reference Fuel (PRF) mixtures; Motor ONs (MONs) of paraffinic fuels; and Research ONs (RONs) of Liquefied Petroleum Gas (LPG) fuels were computed and compared with experimental data reported in literature. The maximal absolute error and the root mean square deviation found were, respectively, 0.084 and 0.047 for the CCR of PRF mixtures; 1.6 and 0.60 for the MONs of paraffinic fuels; and 1.45 and 0.70 for the RONs of LPG fuels.