الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Different approaches are usually followed to face depletion of fossil fuel. Among them, the utilization of biofuels in neat form or binary mixture with diesel that has drawn the attention of researchers for many years. The high viscosity and low heating value of biodiesel are the main drawbacks along with high nitrogen oxides (NOx) emissions. Adding of a ternary component to relax these drawbacks is widely considered. The focus of this study is to illustrate the effect of a novel ternary component to a diesel-biodiesel blend on combustion characteristics, performance and emissions of compression ignition engine. This third component is the cracked naphtha that usually used with straight-run naphtha (from refineries) to increase the gasoline production yield. Cracked naphtha is a low cetane/ low octane fuel produced by vacuum distillation of heavy oil products. Refinery and production of naphtha are relatively low-cost processes that emit low amount of carbon dioxide (CO2) which promote its use as a promising additive to conventional fossil fuels. Experiments were carried out using a single cylinder, 4-stroke, air-cooled compression ignition (CI) engine with a compression ratio of 21.5. This was performed at a constant engine speed of 2000 rpm and different engine loads. This work may be considered the first that considered the utilization of the cracked naphtha in CI engine operating at high compression ratio. The used commercial diesel and biodiesel fuels, and cracked naphtha were used and characterized by Fourier Transform Infrared Spectroscopy (FT-IR), Gas chromatography- Mass Spectroscopy (GC-MS) and Gas chromatography- Flame Ionization Detector (GC-FID) techniques. Different naphtha concentrations (5%, 10% and 15% by volume) were considered and added to neat diesel D100 and diesel-biodiesel blend B30 (70% diesel - 30% biodiesel by volume). The engine performance results revealed that 10% and 5% are the maximum allowable percentages of naphtha to be applied with D100 and B30, respectively. These optimal blends achieved the minimum fuel consumption and reasonable emissions production while meeting acceptable fuel standards such as density, viscosity, flash and fire temperatures. Further increase in naphtha concentrations above these values was shown to lead to misfire at high loads. A reduction in brake specific fuel consumption (bsfc) of 6.28% and 11.7% was achieved for 5% and 10% naphtha addition to diesel, respectively. However, negligible effect was observed for naphtha on bsfc for B30-N5 (65% diesel- 30% biodiesel- 5% naphtha by volume). Naphtha has also decreased NOx emissions for B30-N5 at all considered loads and for diesel-naphtha blends at high and medium loads. CO emission has been reduced for diesel-naphtha blends, while for B30-N5, an increase in CO emission was monitored compared to B30. It could be concluded that addition of cracked naphtha is a promising approach to improve CI engine performance and emissions running with B30 or neat diesel. This also assures the possibility to convert spark ignition engines to work on gasoline compression ignition (GCI) combustion mode by using cracked naphtha as low-octane fuel.