Sharif Digital Repository

In the present work, the spray characteristics of bio-ethanol and its blends have been experimentally and theoretically investigated. To have a comprehensive study, the effects of ambient condition and injection pressure on the spray of different blends have been considered. Macroscopic and microscopic characteristics of spray such as tip penetration length, cone angle, projected area, volume, Sauter Mean Diameter (SMD), and Ohnesorge number are investigated precisely. Besides, air entrainment and atomization analyses have been carried out to improve mixture formation process. Using curve fitting and least squares method, theoretical correlations have been suggested in such a way to predict... 

Reactivity controlled compression ignition has been introduced to implement controllable, clean, and high thermal efficiency without undermining the advantages of premixed combustion. However, simultaneous auto-ignition introduced by reactivity controlled combustion challenges the combustion under higher load operations. This experimental study incorporates a dual phase heat release concept with the purpose of improving the performance of reactivity controlled compression ignition engine. Different ratios of ethanol/diethyl-ether blends (from 0% to 40% diethyl ether and 70% premixed ratio) were applied to a light duty diesel engine at various combustion timings and engine loads. The diesel... 

Unfortunately, energy demands and destruction of the environment from uncontrolled manipulation of fossil fuels have increased. Climate change concerns have resulted in the rapid use of new, alternative combustion technologies. In this study, reactivity controlled compression ignition (RCCI) combustion, which can simply be exploited in internal combustion (IC) engines, is investigated. To introduce and identify extra insightful information, an exergy-based study was conducted to classify various irreversibility and loss sources. Multidimensional models were combined with the primary kinetics mechanism to investigate RCCI combustion, incorporating the second law of thermodynamics. The... 

Reactivity Controlled Compression Ignition can be extended over a wide spectrum of fuels and is anticipated as a promising strategy in meeting current and future emission regulations. In this study, the effect of n-butanol addition on combustion characteristics and emissions in a reactivity controlled engine was investigated experimentally. Different ratios of butanol-diesel blends at different settings of EGR and premixed ratios were applied to a light duty diesel engine. The butanol-diesel blends were directly injected into the combustion chamber while gasoline was injected at the intake port. Combustion phasing was maintained at 2.7 °CA for all of test points by adjusting fuel injection... 

Low temperature combustion potentially can improve engine efficiency coupled with the benefits of low nitrogen oxides, and particulate matter emissions, and vice versa high unburned hydrocarbon and carbon oxide emissions through in-cylinder fuel reactions. In this survey, the experiments were carried out using a modified one-cylinder reactivity controlled compression ignition engine, dual-fueled diesel/compressed natural gas and biodiesel/CNG, to investigate the effects of direct injection strategies on the engine combustion efficiency and emission characteristics. Different ratios of biodiesel blends at different premixed ratios were applied to the dual-fuel engine. The results showed that... 

A single‐cylinder marine diesel engine was modified to be operated in reactivity controlled compression ignition (RCCI) combustion mode. The engine fueling system was upgraded to a common rail fuel injection system. Natural gas (NG) was used as port fuel injection, and a die-sel/sunflower methyl ester biodiesel mixture was used for direct fuel injection. The fraction of bio-diesel in the direct fuel injection was changed from 0% (B0; 0% biodiesel and 100% diesel) to 5% (B5) and 20% (B20) while keeping the total energy input into the engine constant. The objective was to understand the impacts of the increased biodiesel fraction on the combustion characteristics and stability, emissions, and...