Enhancing performance and emission characteristics of a diesel engine using waste plastic oil enriched with carbon nanotubes

Abstract This investigation assesses the viability of utilizing medical/Personal Protective Equipment (PPE)‐derived waste plastic oil (WPO) amalgamated with neat diesel fuel (NDF) and augmented with carbon nanotubes (CNTs) as a substitute fuel in a single‐cylinder diesel engine. WPO was synthesized through ZSM‐5 facilitated catalytic pyrolysis under a nitrogen environment, and test fuels were formulated as NDF10WPO, NDF20WPO, and NDF20WPOC (20% WPO + 100 ppm CNTs). Engine trials were conducted at 1500 rpm under various load conditions to evaluate performance, emissions, and combustion characteristics. An increase in WPO content reduced brake thermal efficiency (BTE) and increased brake‐specific fuel consumption (BSFC) due to a lower heating value (LHV) and delayed ignition, while decreasing the fraction of incomplete combustion products. Compared with NDF, NDF20WPO reduced unburned hydrocarbons (HC) and carbon monoxide (CO) emissions by 16.4% and 14.9%, respectively, but increased nitrogen oxides (NOx) emissions by 23.5%. The incorporation of CNTs improved combustion performance, increasing BTE by approximately 5.6% (relative) and reducing BSFC compared with NDF20WPO, while further reducing HC (17.6%) and CO (20.2%) emissions and slightly decreasing NOx (~1.3%). Combustion analysis revealed improved in‐cylinder pressure and heat‐release characteristics with CNT supplementation. The investigation illustrates a novel medical‐plastic waste‐to‐fuel pathway with enhanced combustion efficiency and emission performance.