الفهرس 
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Abstract
The comparative spray characteristics of petroleum diesel, biodiesel blends andbiodiesel-ethanol blends were reported. 25%, 50% and 75% by volume biodiesel–diesel
blends were used to examine the effect of varying the biodiesel content on the
performance and emissions of a single-cylinder naturally- aspirated direct injection (DI)
compression ignition engine at various engine loads. 50 % biodiesel fuel was used to determine the effect of varying both of alcohol concentration on the engine performance.
The spray angle was found to decrease by about 45 % while its tip penetration
distance increased by about 22 % upon switching from diesel to biodiesel. No significant changes in the spray pattern were found by blending the diesel/biodiesel mixture with
ethanol.
Brake specific fuel consumption (BSFC), exhaust gas temperature (EGT), nitrogen
oxides (NOx) and carbon dioxide emissions (CO2) increased by about 24, 11, 10 and15 %
respectively in addition to a reduction in the brake thermal efficiency (BTE), carbon monoxide (CO) and unburned hydrocarbons (HC) emissions by 11, 50 and 51 %
respectively upon switching from pure diesel to pure biodiesel.
Reduction in BTE, EGT, NOx, CO and HC by about 5, 7, 10, 11 and 39 %
respectively and an increase in CO2 and BSFC by about 10 and 9 % respectively were identified when ethanol was blended with biodiesel-diesel mixture. Increasing the injection pressure enhanced the engine performance by increasing the BTE and reducing
BSFC, CO and HC emissions.