Evaluation of Rapeseed Oil and Methyl Ester Blends for Enhancing Environmental and Performance Characteristics of Diesel Engines

This research presents a comparative assessment of rapeseed oil blends and Rapeseed Methyl Ester (RME) as alternative fuels, analyzing their impact on engine performance metrics, specific fuel consumption, and exhaust emission profiles in agricultural tractors. The experimental investigation employed a John Deere 6930 Premium tractor featuring a High-Pressure Common Rail (HPCR) injection system. Performance evaluations were executed under dynamic operating regimes, encompassing a broad spectrum of load and speed profiles. Results showed that blending diesel fuel with up to 50% rapeseed oil reduced nitrogen oxide emissions by approximately 9.3%, while particulate emissions increased slightly. Using rapeseed methyl ester with bioethanol further reduced NOx emissions to 4.90 g/kWh but increased unburned hydrocarbons and fuel consumption to 275 g/kWh. Field trials found that partial diesel substitution increased specific energy consumption by up to 12% and slightly reduced tractor productivity. Long-term operation of biofuel mixtures did not cause critical failures but required more frequent fuel filter maintenance. Despite a marginal decrement in the aggregate performance metric, the study validates the feasibility of rapeseed-based blends as a partial substitute for diesel. This approach sustains satisfactory engine stability while delivering significant environmental mitigation.