Abstract
Gas-to-liquid (GTL) fuel exhibits potential as a clean alternative diesel fuel, suitable for addressing problems of energy security and environmental pollution. The main objective of this research was to provide fundamental data for the ignition and combustion of GTL fuels. Experiments were conducted in a constant-volume combustion vessel to investigate the effects of ambient temperature on ignition delay and combustion characteristics for various ambient pressures. Three kinds of GTL fuels with different distillation properties and their blends in gas-oil (conventional diesel fuel) were tested. The obtained results showed that all tested fuels exhibited similar ignition-delay trends: ignition delay increased as ambient temperature and ambient pressure decreased. The variation of ignition-delay values was small at higher temperatures but large at lower temperatures. In addition, the results showed that the ignition-delay trend of GTL fuels depended significantly on distillation properties. GTL fuels with high cetane number corresponded to shorter ignition delay and smoother heat-release rate than those for gas-oil at the same temperature and pressure. The results of shadowgraph images demonstrated that GTL fuels evaporated and mixed with the hot air quicker than gas-oil. Furthermore, GTL fuels showed suitability for pre-mixed charge compression-ignition operations owing to ignitability at low temperature. Moreover, the blend GTL fuel helped improve ignition quality and combustion efficiency compared to standard gas-oil. The obtained results should contribute to find the optimal condition of design and operation in diesel engines fuelled by GTL fuels.
Keywords: Gas-to-liquid, Ignition and Combustion Characteristics, Constant-Volume Vessel, Distillation Properties, Ambient Temperature, Ambient Pressure