Influence of fatty acid unsaturation degree over exhaust and noise emissions through biodiesel combustion

► Biodiesel chemical composition affects engine performance and emissions. ► Biodiesel/diesel fuel blends reduce the emissions of CO and noise. ► Biodiesel/diesel fuel blends improve the sound quality, although, NOx increases. ► The higher the unsaturation degree the higher the NOx and the lower the CO emissions. ► A linear correlation between fatty acid unsaturation degree and sound pressure level was found.