Abstract

MAROA, Semakula  and  INAMBAO, Freddie. The effect of cetane number and oxygen content in the performance and emissions characteristics of a diesel engine using biodiesel blends. J. energy South. Afr. [online]. 2019, vol.30, n.2, pp.1-13. ISSN 2413-3051.  http://dx.doi.org/10.17159/2413-3051/2019/v30i2a5337.

The growth in demand for power generation and energy from alternative fuels at low cost and friendly to the natural environment is increasing. This study used waste plastic pyrolysis oil (WPPO) and ethanol to apply direct blending of conventional diesel, WPPO and ethanol with 2-ethyl hexyl nitrate (EHN). The purpose was to improve the combustion and performance characteristics of the WPPO blends. The EHN has the potential to reduce emissions of carbon dioxide, carbon monoxide, unburnt hydrocarbon, oxides of nitrogen and particulate matter. Ethanol improves viscosity, miscibility, and the oxygen content of WPPO. Five mixing ratios were selected. The mixing ratio with EHN was based on total quantity of blended fuel at 0.01%. At 50% engine load, the brake specific fuel consumption was 0.043 g/kWh compared with CD at 0.04 g/kWh. The blend 90/WPPO5/E5 had the highest value of 14% for brake thermal efficiency, while on NO_X emissions three blends 90/WPPO5/E5, 80/WPPO10/E10, 70/WPPO15/E15, had the lowest values of 384 ppm, 395 ppm, 414 ppm, compared with CD fuel at 424 ppm. The implication was that ethanol and WPPO blends can be used in diesel engine power generators as an alternative fuel with modification, as their respective densities of 792 kg/m³ and 825 kg/m³ are close to CD fuel's at 845 kg/m³. Additionally, these combinations with EHN reduced emissions more than earlier thought and improved engine performance, equalling that of conventional diesel fuel.

Keywords : 2-ethyl hexyl nitrate; ethanol; oxygen content; ignition quality; waste plastic pyrolysis oil; cetane index.

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