Work

Performance–Emission Trade‐Offs in RCCI Engines Using High‐Viscosity Alcohol–Diesel Blends Under Variable Injection Pressures

Year: 2026

Type: article

Abstract: ABSTRACT This study experimentally investigates the performance, combustion, and emission characteristics of a Reactivity‐Controlled Compression Ignition (RCCI) engine fueled with diesel and the high‐viscosity oxygenated alcohol 2‐Methyl‐1‐butanol. Experiments were conducted on a single‐cylinder common‐rail direct injection engine operating at brake mean effective pressures of 3 and 5 bar and fuel injection pressures of 400, 600, and 800 bar. Diesel was directly injected as the high‐reactivity fuel, while 2‐Methyl‐1‐butanol was port‐injected to establish RCCI combustion. Fuel blends containing 10%, 20%, and 30% alcohol were evaluated and compared with neat diesel operation. Results indicate that increasing injection pressure improves fuel atomization, advances combustion phasing, and enhances heat release characteristics. At full load and 800 bar injection pressure, the D70MB30 blend achieved the highest brake thermal efficiency of 37.4%, compared to 26.0% for neat diesel. Significant emission reductions were also observed, with NO x decreasing from 4.5 ppm (diesel) to 3.1 ppm and smoke opacity showing a consistent declining trend due to improved charge homogeneity and oxygen availability. However, higher alcohol content resulted in increased CO and HC emissions at part‐load conditions because of low‐temperature combustion and evaporative cooling effects. These penalties were substantially mitigated at higher injection pressures. Overall, the D70MB30 blend at 800 bar provided the best trade‐off between performance and emissions, demonstrating the potential of 2‐Methyl‐1‐butanol as a sustainable alternative fuel for advanced RCCI engine operation.

Source: Engineering Reports

DOI: 10.1002/eng2.70619