Effect of nano additives and compression ratio on diesel engine performance and emission characteristics using co-pyrolytic fuel with diesel blends: An energy recovery approach towards circular economy

UNDP's 2030 Agenda faces hurdles in achieving clean energy goals due to excessive plastic waste production and insufficient public awareness, endangering the environment. Co-pyrolysis efficiently recycles plastic waste, converting it into useful energy, reducing environmental risks, and aiding ecosystem restoration. This study explores the use of Co-pyrolyzed oil from waste polypropylene and Delonix regia (WPD) as a sustainable solution to fossil fuel depletion and alternate energy source for diesel engines, addressing plastic waste and energy challenges. The engine performance analysis was conducted in a single-cylinder direct injection variable compression ignition engine with varying compression ratios from 16 to 18 by using 50 ppm, 70 ppm and 100 ppm of nanographene by mass emulsified in 20% WPD without any engine modification. The performance characteristic of fuel mixture 80D20WPD100G (20% WPD +100 ppm Graphene) is compared with that of neat diesel by supercharging the engine with nanographene at different compression ratios. The results show that the brake thermal efficiency of 80D20WPD100G fuel is increased by 2.8% at a compression ratio of 18:1 compared to standard diesel. The CO, HC, NO x emissions also dropped significantly by adding 100 ppm graphene to copyrolysis as compared to the other combinations of fuels. The study found that 20% WPD–diesel blend with 100 ppm nanographene at an 18:1 compression ratio enhanced brake thermal efficiency by 25.99% and reduced CO, HC, and NOx emissions as compared to diesel. Nanographene acted as an oxygen buffer catalyst, improving combustion and supporting a sustainable solution for plastic waste utilization. These findings offer a pathway to reduce plastic pollution and fossil fuel dependence while showcasing the novel use of graphene nano-additives in fuel blends from waste plastics to enhance engine efficiency and reduce emissions. • Co-pyrolysis of waste polypropylene and Delonix regia. • Physico-chemical characterization of obtained liquid fuel. • Engine test for performance and emission analyses with fuel blend. • Socio-economic impacts of co-pyrolytic liquid fuel.