**Author details**

*Numerical and Experimental Studies on Combustion Engines and Vehicles*

findings are identical to the findings of Ref. [126].

**6. Conclusion**

to the others.

These findings seem to show that there is a correlation between the alcohol content in the fuel and peak flame temperatures, content of nitrogen, and oxygen availability [123]. Increased NOX concentration is attributed to the presence of nitrogen from the cetane number improver ENH and other contaminants from the WPPO composition. Additionally, it could be due to the generation of radicals of hydrocarbon through molecular unsaturation being identical to the findings of Refs. [124, 125]. However, the NOX levels are still low, attributed to high CNs of the tested biodiesels in **Table 3** and increased oxygen content due to the blend ratios. These

• This study thus makes a strong case for alternative fuels to replace petroleumbased fossil fuels like diesel commonly used as the primary propulsion fuel in transport and power generation. This work looks at the concept of waste to energy and waste resource utilization in an era when environmental concerns

and awareness are at the pick of development agenda across the globe.

• Lower blend ratios 90/WPPO5/E5 and 80/WPPO10/E10 exhibit identical brake-specific fuel consumption (BSFC) of conventional diesel test fuel compared to the other blends. These blends show the lowest BSFC values compared

• The brake thermal efficiency of blend 90/WPPO5/E5 (90% conventional

• There was a reduction in unburnt hydrocarbon (UHC) concentration with the use of WPPO blends, ethanol, and 2-ethyl hexyl nitrate (EHN), with a notable reduction in oxides of nitrogen concentration especially for the blend 90/WPPO5/E (90% conventional diesel, waste plastic pyrolysis oil 5%, and ethanol 5% by volume). This was a clear indication that this blend performed

• Although there was indicated increase in the concentration of CO, CO2 NOX and UHC, for all the blends of WPPO, ethanol and EHN. There was a clear indication that the emission levels were notably lower than the emission levels of conventional petroleum diesel, based on the ASTM measurements used in this study. However, when comparisons for overall values of concentration are compared to concentration standards, the WPPO blend performed well.

• The blends of WPPO, ethanol, and EHN have identical temperature characteristics to those of the conventional diesel test fuel especially as the engine speeds hit 75% heading to full engine speed. This was attributed to the presence of ethanol responsible for decreased ignition delay. The presence of high oxygen enrichment was a factor of decreased CO concentration for the tested biodiesels compared with conventional diesel fuel, although there was an increase in CO concentration as fuel CN and blend ratio increased. This is due to deterioration of the combustion characteristics, as the cetane numbers (CNs) and the

well when compared with petroleum conventional diesel.

diesel, waste plastic pyrolysis oil 5%, an ethanol 5% by volume) showed values, which were very close to the values of conventional diesel fuel values. This was attributed to close density values and the gross calorific values of waste plastic pyrolysis oil (WPPO) blends, which showed marginal differences. This case was apparent especially at lower blend ratios of all the mixtures and blends tested.

**58**

Semakula Maroa1 \* and Freddie Inambao2

1 College of Agriculture Science and Engineering, University of KwaZulu-Natal, Durban, South Africa

2 Discipline of Mechanical Engineering, Green Energy Group, Durban, South Africa

\*Address all correspondence to: ssemakulamaroa@gmail.com

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
