THE INFLUENCE OF CETANE NUMBER AND OXYGEN CONTENT IN THE PERFORMANCE AND EMISSIONS CHARACTERISTICS OF A DIESEL ENGINE USING BIODIESEL BLENDS

Waste plastic pyrolysis oil (WPPO) and ethanol are attractive renewable energy sources, as ethanol has a high content of oxygen. However, for this particular study, direct blending of conventional diesel, WPPO, ethanol and 2-ethyl hexyl nitrate (EHN) was attempted. The purpose was, firstly, to improve the combustion, ignition quality, performance and emission characteristics of the WPPO blends. Secondly, EHN has the potential to reduce emissions of CO, CO2, UHC, NOX and PM. Thirdly, ethanol improves viscosity and miscibility of biodiesel blends, besides increasing the oxygen content of WPPO. Five mixing ratios were used in the following order, 50/WPPO25/E25, 60/WPPO20/E20, 70/WPPO15/E15, 80/WPPO10/E10 and 90/WPPO5/E5 for conventional diesel (CD), WPPO and ethanol and respectively. However, for EHN the mixing ratio was determined by the total quantity of blended fuel and put at 0.01 %. Complete miscibility was observed with no phase separation allowed from the blended mixtures throughout the experiment. Performance and emission characteristics of a stationary single cylinder water-cooled diesel power generator were evaluated. The results obtained were compared carefully to ASTM standards and discussed using tables and graph figure curves. The conclusion was that ethanol and EHN can be used in diesel engine power generators as an alternative fuel to help improve cetane numbers and to increase the oxygen content without or with modification with WPPO blends. This is due to the densities 792 kg/m3 , 963 kg/m3 , 825 kg/m3 for WPPO, ethanol and EHN respectively, which are close to CD fuel at 845 kg/m3 . The addition of EHN, reduced emissions and improved engine performance so that it equalled that of CD fuel.