A comparative analysis of the engine performance, exhaust emissions and combustion behaviors of a compression ignition engine fuelled with biodiesel/diesel/1-butanol (C4 alcohol) and biodiesel/diesel/n-pentanol (C5 alcohol) fuel blends

In this study, engine performance, exhaust emissions and combustion behaviors of a single-cylinder, four-stroke, direct-injection diesel engine running on biodiesel/diesel/1-butanol and biodiesel/diesel/n-pentanol fuel blends were investigated and compared with diesel fuel under different engine speeds and full load operating conditions. Test fuels were prepared with 5 and 10 vol% 1-butanol and n-pentanol. Engine test results indicated that brake powers and torques decreased as the amount of alcohol increased, while BSFC increased between 0.77% and 8.07%. Alcohol blended fuels acquired lower EGT and CO2, while observing higher O2 emission due to high oxygen content of alcohol compared to diesel fuel. Alcohol treated blends also diminished NOX by 0.56–2.65%, CO by 6.90–32.40%, and smoke by 10.47–44.43%. Moreover, n-pentanol blended fuels showed better performance and emission results than 1-butanol blends. Maximum in-cylinder pressure of higher alcohol blended fuels found between 94.55 and 95.82 bar at 371-372oCA for 1400 rpm, and between 78.19 and 82.19 bar at 375-376oCA for 2600 rpm. Alcohol addition into the blends increased maximum in-cylinder pressure up to 1.38% at low speed, whereas it decreased up to 3.75% at high speed. Furthermore, higher HRR values up to 8.5% were observed with the alcohol mixed fuels. Consequently, higher alcohols (n-pentanol and 1-butanol) can be utilized as alternative additives in biodiesel/diesel blends for diesel engines to improve emissions, although they adversely influence engine performance.