In this study, the sunflowers oil was utilized as for producing biodiesel via a chemical operation, which is called trans-esterification reaction. Iraqi diesel fuel suffers from high sulfur content, which makes it one of the worst fuels in the world. This study is an attempt to improve the fuel specifications by reducing the sulfur content of the addition of biodiesel fuel to diesel where this fuel is free of sulfur and has a thermal energy that approaches to diesel.20%, 30% and 50% of Biodiesel fuel were added to the conventional diesel. Performance tests and pollutants of a four-stroke single-cylinder diesel engine were performed. The results indicated that the brake thermal efficiency a decreased by (4%, 16%, and 22%) for the B20, B30 and B50, respectively. The increase in specific fuel consumption was (60%, 33%, and 11%) for the B50, B30, and B20 fuels, respectively for the used fuel blends compared to neat diesel fuel. The engine exhaust gas emissions measures manifested a decreased of CO and HC were CO decreased by (13%), (39%) and (52%), and the HC emissions were lower by (6.3%), (32%), and (46%) for B20, B30 and B50 respectively, compared to diesel fuel. The reduction of exhaust gas temperature was (7%), (14%), and (32%) for B20, B30 and B50 respectively. The NOx emission increased with the increase in biodiesel blends ratio. For B50, the raise was (29.5%) in comparison with diesel fuel while for B30 and B20, the raise in the emissions of NOx was (18%) and...

??investigation of performance and emission of conventional a four-stroke, single-cylinder direct injection (DI) diesel engine at variable engine speed range from (1500 to 3000 rpm), carried out at steady-state tests conditions with diesel fuel and biodiesel which is produced from sun flower oil mixed with the higher alcohol. The blends effects on the performance and emission for the blended fuels measured and compared. 10% and 15% of Pentanol, Octanol added to the biodiesel blended with diesel for various test conditions. The experimental results showed an approximately 2–9% increase in the brake-specific fuel consumption (BSFC) for the prepared blends of pentanol and octanol due to the lower heating value (LHV), with higher brake thermal efficiency compared to diesel fuel. With expressively reduction of (9.8-21% vol.) in carbon monoxide (CO), and total unburned hydrocarbons (THCs) of (65-78.3% ppm), and nitric oxides (NOx) (44.4–52.9% ppm). The combustion analyses showed that the addition of biodiesel to conventional diesel fuel decreased the ignition delay and reduced the properties. These results indicated that biodiesel and higher alcohol could be used without any engine modifications as an alternative and environmentally friendly fuel.