Exergetic performance optimization and thermoeconomic analysis of a variable compression ratio diesel engine fueled with distilled plastic oil and diesel doped with nanographene

Due to the fast depletion of fossil fuels, enormous concerns about environmental pollution, and advocacy for waste-to-energy drives from the global perspective, compression ignition engines need a sustainable alternative fuel source. Enormous plastic wastes were generated in health sectors, particularly during post-pandemic. In this context, the study intends to introduce a reasonable solution for such waste plastics recycling by converting them into liquid oil by pyrolysis followed by the distillation process. Distilled waste plastic oil (DPO) extracted from medical plastic waste is a potential alternative diesel source. The performance of the engine significantly increases when nanographene is added with DPO/diesel blends, which act as a combustion improviser. The energy efficiency (η1), exergy efficiency (η2), and brake-specific fuel consumption (BSFC), which are regarded as key performance indicators, exhibited promising results when operated with 20% DPO +100 ppm nanographene (20DPO100G) emulsified fuel mixture as compared to normal diesel. When compared to diesel and other fuel combinations, the energy efficiency (η1) and exergy efficiency (η2) for 20DPO100G fuel mixture were found enhanced by 5.78% and 10.9%, respectively, and lowest by 14.7% for BSFC in comparison to diesel. The optimum energy efficiency, exergy efficiency, and minimum BSFC were obtained for the test engine from response surface methodology multi-objective optimization analysis as 31.44%, 22.12%, and 0.32 kg/kW-hr, respectively, for the composite desirability, D of 0.974. The 100 ppm nanographene emulsified distilled waste plastic pyrolysis oil and diesel blend has the lowest relative cost variation of −14.583.