Investigation of the effects of the use of biodiesel (B20) and diesel fuel in agricultural tractors on the wear parts of the engine

In this study, the effects of fuel blend of 20% biodiesel + 80% diesel (B20) on engine performance, engine main parts and injectors were investigated in comparison with diesel fuel. For this purpose, two different 55 kW powered agricultural tractors of the same brand and model were operated for 1000 hours under similar agricultural field conditions using both diesel fuel and B20. In the performance tests, it has been determined that there is a 3% power, 2% torque decrease and 5% increase in specific fuel consumption compared to diesel fuel in the use of B20. It was observed that values decreased for carbon monoxide (CO) 40%, hydrocarbon (HC) 19%, particulate matter (PM) 46% and increased for nitrogen oxide (NOx) 7% in emissions. In the sample analyses of the engine oils taken at the maintenance intervals of 200 hours during the working of the tractors in the field, significant wear metals in the engine oil and no negativity in the chemical analysis results were found. Visual inspection of the main parts of both engines, which were disassembled after 1000 hours, also supports the engine oil analysis results. After 1000 h of operation, each injector needle and nozzle tip was examined in terms of a functional evaluation of the injector nozzle via visual inspection, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX). According to results of these analyses, B20 fuel blend's C content was determined to be 73.47% and O content 23.34%, quantity of other elements was determined to be lower than 1%. Similarly, as for diesel fuel, C content was determined to be 50.49% and O 19.95% and other elements are in trace amounts. Furthermore, Fourier-transform infrared spectroscopy (FTIR) spectral analysis was also used to examine the deposits on the injector nozzle tips and needles. Polyisobutylene succinimide (PIBSI) and inorganic components were observed on the injector needles and aging products and inorganic components on the injector nozzle tips. No significant difference was found between the results of the diesel fuel and B20 fuels in terms of injector nozzle function.