Uticaj različitih vrsta goriva na vučni koeficijent korisnosti traktora / Effects of different types of fuel on tractor power delivery efficiency

Increased energy use wordwide has created a need to find alternative energy sources that can meet basic quality criteria such as renewability, ecological acceptability and reliability of use. The alternative implies the possibility of use of different fuel without any changes made to the engine design. Compatibility of biodiesel with fossil fuel makes it an adequate solution; its production is based on renewable raw material and it is ecologically more acceptable than fossil fuel. The aim of this dissertation was to investigate the influence of biodiesel, and different blends of biodiesel and eurodiesel on engine performances, tractor traction characteristics, and exhaust gas emission. During the research, biodiesel made from sunflower oil was blended with fossil diesel (euro diesel quality). John Deere 6820 tractor model was used to analyze the effects of biodiesel, fossil diesel, and blends of fossil diesel with 7, 14, 20, 40, 60 and 80%v/v of biodiesel on engine performances, tractor traction characteristics and exhaust gas emission. The tractor had a six cylinder engine PowerTech 4V-CR with 99 kW power at 2100 min-1 optimal number of rotations and maximum torque of 602 Nm at 1365 min-1. The engine belongs to the Stage II category. The experiment was conducted in compliance with OECD test CODE 2. The results of engine performances tested in laboratory showed that increased share of biodiesel in the blend reduced engine power by up to 5.61% and increased specific fuel consumption up to 10.78%, which was less than expected. By using ED, tractor had maximum power of 90.45 kW, and use of BD40, BD60, BD80 and BD100 fuels resulted in linear reduction of maximum power with increased share of biodiesel in the blend. Maximum engine power measured with different types of fuel was lower compared to ED by 1.35, 2.59, 4.06 and 5.61%, respectively. Slight increase in viscosity of fossil diesel achieved by adding up to 20% of biodiesel had positive effects on engine performances (1.06%). The results of tested traction characteristics showed that the use of biodiesel reduced traction by 5.58%, and increased specific fuel consumption by up to 11.95%. Increased biodiesel share reduced the CO emission by 27.45%, CO2 emission slightly increased by 3.58%, and the emission of NOx increased by 10.14%.