Alcohol-Diesel blends fueled Off-Road CI engine Development: Part 3 − Evaluating the influence of Butanol-Diesel blends on Performance, Combustion, and emissions

• Butanol-diesel blends produced equivalent torque/ power without hardware modifications. • Higher BTE was observed for butanol-diesel blends than baseline diesel. • Butanol-diesel blend combustion reduced the CO emission significantly at high loads. • Butanol-diesel blends resulted in lower COV IMEP than baseline diesel. • Butanol-diesel blends exhibited lower cycle-by-cycle variation than baseline diesel. Conventional diesel-fuelled vehicles have been widely used for decades in the transport sector. The exhaustible nature of crude oil-based fuels and the irreparable damage caused by fossil-fueled powered vehicles have led to the urgency of adopting cleaner engine technologies and green biofuels. A four-carbon chain alcohol, namely butanol (C 4 H 10 O), is an emerging fuel that can partially replace baseline diesel by forming butanol-diesel blends. Butanol is completely soluble in diesel, thus eliminating the need for a co-solvent, which is not the case for methanol and ethanol. This experimental study aims to investigate the combustion, performance, emission characteristics, and cyclic variations for three different butanol-diesel blends. Three n-butanol-diesel blended fuels (But10, But20, But30) were prepared, and the baseline diesel was used as the reference fuel. At low loads, But20 (1.67 % at 1.14 and 3.5 % at 2.28 bar BMEP) and But30 (7.8 % at 1.14 and 8.5 % at 2.28 bar BMEP) exhibited higher brake thermal efficiency, but But10 (7.8 % at 1.14 and 1.17 % at 2.28 bar BMEP) exhibited lower brake thermal efficiency than the baseline diesel. All butanol-diesel blends exhibited higher brake thermal efficiency than the baseline diesel at the rest of the test loads. At 5.71 bar BMEP, ∼13.6 % higher brake thermal efficiency was observed for But30 than baseline diesel. The exhaust gas temperature of butanol-diesel blends was more than the baseline diesel for all engine test loads. At 4.57 bar BMEP, the highest (∼13.47 %) exhaust temperature was observed for But20 than for the baseline diesel. However, the exhaust gas temperature decreased with the increase in the percentage of butanol in the butanol-diesel blends. Also, butanol-diesel blends consumed comparable and lower energy to produce diesel-equivalent torque/ power output at low and high loads, respectively. Butanol-diesel-fueled engines generated higher in-cylinder pressure and heat release rates than baseline diesel. A higher rate of pressure rise than baseline diesel was observed using butanol-diesel blends. The butanol-diesel blends showed lower cyclic variations than baseline diesel. Compared to baseline diesel, CO emissions were reduced for But10 (∼63.2 % at 5.71 bar BMEP) and But30 (∼58.4 % at 5.71 bar BMEP). Nitrogen Oxides were higher at low loads, comparable at mid loads, and lower at high loads for butanol-diesel blends than baseline diesel. Smoke opacity was lower for butanol-diesel blends than baseline diesel. But10 showed higher smoke opacity reduction compared to baseline diesel. However, hydrocarbon emissions were significantly higher for butanol-diesel blends than baseline diesel.