Performance and Emission Analysis of Single Cylinder Diesel Engine Utilizing a Blend of Waste Cooking Oil and Non-edible Oil with Al2O3 and DEE Additives using Response Surface Methodology

Abstract

This study examines the performance, combustion, and emission characteristics of a single-cylinder diesel engine powered by various blends of waste cooking oil (WCO) and neem oil biodiesel (B0 to B40). The biodiesel blends were enhanced with aluminium oxide (Al₂O₃) nanoparticles synthesized via a precipitation technique and characterized using TEM analysis. These nano-additives were dispersed using magnetic stirring followed by ultrasonication. Diethyl ether (DEE) was also introduced as an additive at varying levels (0–100 ml), along with Al₂O₃ concentrations ranging from 0 to 100 ppm. The experiments were conducted at a constant engine speed and compression ratio under five different load conditions (0–12 kg). Response Surface Methodology (RSM) based on Central Composite Design (CCD) was used to analyze the influence of blend ratio, DEE, Al₂O₃ concentration, and load on brake thermal efficiency (BTE), brake specific fuel consumption (BSFC), in-cylinder pressure, and exhaust emissions (CO, HC, NOₓ, and smoke opacity).

The developed RSM models showed strong statistical significance (p < 0.05, R² > 0.95), identifying optimal operating conditions with moderate DEE (~10 % vol) and Al₂O₃ levels ,(25–50 ppm). Under these conditions, BTE improved by 3–6%, BSFC was reduced by 4%, and combustion efficiency increased with an 8% rise in peak pressure and heat release rate. Emission levels of CO and HC dropped by 37%, NOₓ by 4%, and smoke opacity by 12%. These findings suggest that biodiesel blends enhanced with DEE and Al₂O₃, when optimized through RSM, provide a viable pathway for cleaner and more efficient diesel engine operation.