Browsing by Author "Leigh, David Ken"
Now showing 1 - 1 of 1
Results Per Page
- ItemCharacterisation of synergestic and antagonistic petrol component chemical class effects on octane blending behaviour(Stellenbosch : Stellenbosch University, 2020-03) Leigh, David Ken; Haines, R.; Floweday, G.; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.ENGLISH ABSTRACT: Knock free operation has influenced the development of internal combustion (IC) engine technology and spark ignition (SI) fuels. Knock is the noise associated with the harmful and abnormal combustion phenomenon known as autoignition. For a given engine configuration, the propensity of knock in IC engines depends primarily on the anti-knock quality of the fuel. Research octane number (RON) and motor octane number (MON) are measured fuel properties indicating a fuel s resistance to autoignition. Fuel producers ultimately seek to produce fuels with RON and MON values suitable for modern IC engines, however, the highly complex non-linear blending interactions between the constituents of the fuel recipe make this challenging. The present research was undertaken to characterise the non-linear synergistic and antagonistic octane blending behaviours between important common chemical class components, carefully selected to represent the SI fuel recipe on a fundamental level. The RON and MON values for all binary combinations of these components at various blend ratios were measured using Stellenbosch University’s uniquely modified Cooperative Fuels Research engine. All octane experiments were performed in accordance with the American Society for Testing and Materials D2699 and D2700 standards. The measured RON and MON data showed results consistent with the literature and highlighted a shortage of research data for some binary blends. The project hypothesis was supported, showing that non-linearities do exist in octane blending between binary combinations and that more than one non-linearity can exist in a binary blend. Using this and the measured data, conclusions were drawn on the links between the various chemical classes, blending ratios and the non-linearities in octane number. It was demonstrated that octane sensitivity is a function of blend ratio and provides insight into improving fuel recipes for modern SI engines. The octane boosting capabilities of a non-metallic octane booster, was shown to significantly boost the octane of some of the selected components and had no significant effect on others. It was found to influence the RON value more than the MON value of a blend. The suitability of two well established empirical octane prediction models were investigated for use in predicting octane. The predicted data was compared to the measured data and deficiency in the better performing model was identified and then optimised to improve the octane predictions for the binary blends.