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Prediction of Cetane Number from the Molecular Structure of Pure and Oxygenated Hydrocarbon Fuels
ISSN: 0148-7191, e-ISSN: 2688-3627
To be published on September 22, 2021 by SAE International in United States
Cetane number (CN) signifies the auto-ignition quality of fuel and access the suitability of a fuel for compression ignition (CI) engine operation. Experimental estimation of CN by CFR engine (ASTM D 613), IQT (ASTM D 6890) and CID (ASTM D7170) involve higher cost and time. Hence, a novelregression model was developed in the current study to predict the cetane number of pure and oxygenated hydrocarbon fuels. From the earlier studies, it was understood that the molecular structure has a strong dependence on CN. In this study, CN predictionwas carried out using multiple linear regression (MLR) analysis and considering various molecular structure parameters of fuel compounds. The molecular structure parameters considered for regression analysis were molecular weight percentage of C, CH, CH2 and CH3, number of single bonds (C-C) and number of double bonds (C=C). Experimental CN of 127 pure and oxygenated hydrocarbon fuel species such as alkanes, iso-alkanes, cycloalkanes, alkenes, aromatics, alcohols, ketones, esters and furans, as collected from the literature, was considered for the current analysis. CN increases with the increase in carbon number, whereas CN decreases with branching, double bonds and functional groups. Further, CN is also influenced by the position of the branching, double bond and functional groups. New parameters such as branching factor (BF), position factor (PF) and oxy factor (OF) was defined in this study, and a new regression model was developed. The predicted CN showed good agreement with the experimental CN with highaccuracy (R2: 0.987), and the mean absolute deviation (MAD) was noted to be less than 4. The impact of various molecular structure parameters on CN was analyzed, and its significance was discussed in detail. It was observed that CN decreases with an increase in molecular weight percentage of the CH3group and CH2group in the main carbon chain.