Critical insights into the effects of plastic pyrolysis oil on emission and performance characteristics of CI engine

Pyrolysis is an encouraging solution considering the facts of energy demand and waste plastic management as it produces liquid fuel for compression ignition engine application. This study provides critical insights into the effects of waste plastic oil on the emission and performance characteristics of compression ignition engines. Though most of the studies have shown a negative influence, promising outcomes have been noticed in a few specific cases. A maximum of 71%, 80%, 76%, 71%, 21%, and 13% decrease in nitrogen oxide emission, carbon monoxide emission, unburnt hydrocarbon emission, smoke emission, exhaust gas temperature, and brake-specific fuel consumption, respectively, have been noticed with waste plastic oil or its blends at certain operating conditions. Nevertheless, the presence of long carbon chains, higher aromatic content, and non-homogeneous air-fuel mixture owing to the wide product distribution in plastic oil are the few reasons which affected the emission and performance characteristics of the engines. More rigorous investigations are needed to improve the quality of the fuel and to establish correlations between the fuel properties and pyrolysis parameters. In addition, the effects of incorporating exhaust gas recirculation, emulsification process, and use of additives with waste plastic oil need to be explored more for reducing the emissions with satisfactory engine performance, and in this regard, the use of bio-additives with waste plastic oil can provide a new direction to this research field. Further, studies on the economic feasibility and the impact of waste plastic oil on engine materials are also required.