Enhancing Rapeseed Oil Diesel Fuel Blends with Polyhydric Alcohols and Butyl Ether for Improved Engine Performance

This study investigates the impact of polyhydric alcohols and butyl rapeseed oil ether as functional additives in fuel blends containing high proportions of rapeseed oil. Experimental fuel mixtures were prepared with 70% rapeseed oil and varying concentrations of ethylene glycol and butyl ether, resulting in a significant reduction in viscosity from 14.3 to 5.9 mm²/s at 40 °C and improved cold-flow properties down to –18 °C. Engine tests using a Perkins 1104A-44T diesel engine were comparable to those of the base blend. The introduction of additives also led to reduced ignition delay, higher indicator efficiency, and lower emissions of nitrogen oxides and carbon monoxide. Tribological assessments confirmed that lubricating properties remained stable or slightly improved. Storage stability tests indicated a slower increase in the acid value over 45 days. The results show that incorporating these additives effectively enhances fuel performance, combustion efficiency, and environmental characteristics without requiring engine modifications. Quantitatively, the indicated efficiency increased by 3.1 percentage points (from 39.2% to 42.3%) under 75% load, while NOx and CO emissions decreased by ≈11% (1480→1320 ppm) and ≈19% (0.42→0.34%), respectively.