Synergistic role of water and di-n-butyl ether in Jatropha curcas biodiesel-fueled diesel engine

• Jatropha biodiesel blends improve combustion with higher peak pressure. • Water emulsification lowers NOx but increases HC, CO, and reduces BTE. • DnBE addition enhances cetane value, efficiency, and lowers fuel use. • Ternary blends cut HC, CO, NOx, and smoke emissions effectively. • Proposed blend offers balanced performance for sustainable diesel engines. This study aims to enhance diesel engine efficiency and reduce emissions through the combined use of Jatropha curcas biodiesel, water emulsification, and di-n-butyl ether (DnBE). Biodiesel was produced via base-catalyzed transesterification and blended with diesel to form a 20% biodiesel-diesel mixture (DF20JCOB). To mitigate NOx and improve combustion stability, 10% water and 10% DnBE were sequentially incorporated, yielding the ternary blend DF20JCOB10WE. Engine tests on a single-cylinder diesel engine were conducted to evaluate performance, combustion, and emission characteristics. Results showed that the baseline biodiesel blend improved peak cylinder pressure by 5% and reduced hydrocarbon (HC) and carbon monoxide (CO) by 7.8% and 3.8%, though nitrogen oxides (NOx) rose slightly. Water addition lowered NOx by 8% but reduced brake thermal efficiency (BTE) by 5%. The inclusion of DnBE countered these drawbacks, increasing BTE by 8%, lowering brake specific fuel consumption by 7%, and reducing HC, CO, NOx, and smoke by 8.6%, 6%, 4.8%, and 7.8%, respectively. Overall, the ternary Jatropha biodiesel–water–DnBE blend demonstrates a practical pathway for cleaner, more efficient, and economically viable diesel operation.