| The use of kerosene in direct injection compression ignition (DICI) engines is fundamentally due to the introduction of the Single Fuel Concept (SFC) as highlighted in Chapter 1. As conventional DICI diesel engines are made specifically to use diesel fuel, the usage of kerosene will have adverse effects on engine emissions and combustion characteristics. As a result, in order for kerosene to be properly and efficiently used in diesel engines, a comprehensive literature review was carried out in Chapter 2 to identify the research gaps. Through the literature review, it was noted that much experimental work was done for kerosene combustion in DICI engines. However, reliable and compact chemical reaction mechanisms for kerosene combustion under DICI diesel engine conditions are sorely lacking and, as a result, negligible numerical simulation has been carried out in this area. Hence, the primary objective of this thesis is to develop suitable kerosene reaction mechanisms which are small and yet robust enough to be used for DICI engine simulations which are capable of predicting the major emissions such as soot, carbon monoxide (CO) and nitrogen oxide (NO). The secondary objective is to investigate the potential of kerosene in reducing emissions through different injection rate-shapes and bowl geometries. The background, motivation, research gaps, objectives as well as the thesis organization are mentioned in Chapter 1. Moreover, Chapter 3 gives an overview of the experimental setup and the numerical code used in this thesis.;A validated C12H24 kerosene reaction mechanism, containing only 122 species and 585 reactions, with embedded soot chemistry for diesel engine simulations was developed in Chapter 4. The C12H24 kerosene reaction mechanism was validated for its ignition delay times under different initial shock tube conditions. Constant volume heat-release rate as well as ignition delay validations were also carried out under different ambient conditions. Furthermore, the reaction mechanism is able to predict the combustion characteristics and soot trends of kerosene reasonably under real engine conditions.;In order to further reduce computational time, a more compact reaction mechanism was developed in Chapter 5. The new kerosene-diesel reaction mechanism consists only of 48 species and 152 reactions. Furthermore, the kerosene sub-mechanism is validated for its ignition delay times under different initial shock tube conditions and constant volume combustion conditions. The predicted and experimental constant volume heat-release rates as well as flame lift-off lengths (FLOLs) are also similar. Overall, this new kerosene-diesel reaction mechanism is proven to be robust and practical for diesel engine simulations.;In Chapter 6, parametric studies were carried out using the mechanism developed in Chapter 5. Chapter 6 Part A investigates the combustion and emissions characteristics of a DICI engine fueled with kerosene-diesel blends, using different piston bowl geometries together with varying injection rate-shapes were investigated. On the other hand, Chapter 6 Part B investigates the effects of boot injection rate-shapes on the combustion process and emissions formation of a direct injection compression ignition engine fueled with kerosene and diesel. A phenomenological soot model and the adjusted and enhanced kerosene-diesel reaction mechanism were used to study the combustion process and emissions formation. From Chapter 6, it can be seen that by using kerosene together with the appropriate injection rate-shape, one is able to reduce DICI diesel engine emissions relative to diesel fuel combustion.;Finally, Chapter 7 sums up the contributions of this thesis and recommends possible future work. |
