Synergistic effects of graphene quantum dot additives in waste plastic oil blends: Combustion stability and emission reductions analysis
S. Gopinath, Chidambaranathan Bibin, Ashok Kumar R, S. Arunkumar, K. Rajesh, Yuvarajan Devarajan, Ruby Mishra
Abstract
• GQD additives significantly improve combustion efficiency in waste plastic oil blends. • ULDP20G40 achieves a 5.71 % higher BTE than ULDP20, with reduced emissions. • GQD integration reduces CO and HC emissions compared to diesel. • ULDP20G40 demonstrates balanced performance with 40 % GQD concentration. • Findings support GQDs as a viable enhancement for sustainable fuel technologies. This research examines the combined effects of incorporating Graphene Quantum Dot (GQD) additives into waste plastic oil blends (ULDP20) on their performance, combustion behavior, and emission characteristics in a diesel engine. The experimental study involved testing ULDP20G30, ULDP20G40, and ULDP20G50 blends, with ULDP20G40, containing 40 % GQD, identified as the most effective formulation. The ULDP20G40 blend displayed enhanced combustion stability and achieved a 5.71 % increase in Brake Thermal Efficiency (BTE) compared to ULDP20, though it remained 2.83 % lower than that of standard diesel fuel. On the emissions front, the addition of GQDs notably reduced Nitrogen Oxide (NOx) and smoke emissions when compared to ULDP20. Specifically, ULDP20G40 exhibited a 1.63 % reduction in NOx and a 2.33 % decrease in smoke emissions compared to ULDP20. However, compared to diesel, NOx and smoke emissions were slightly higher by 1.43 % and 7.69 %, respectively. The superior oxidation properties of GQDs also contributed to significant decreases in Carbon Monoxide (CO) and Unburned Hydrocarbon (UHC) emissions across all tested blends, demonstrating their effectiveness in achieving cleaner combustion processes. The experimental approach involved systematically varying the GQD concentration to identify the optimal blend, followed by an in-depth evaluation of its combustion and emission properties. These results establish GQD-enhanced ULDP20 blends, particularly ULDP20G40, as viable alternatives for sustainable fuel applications. Future work will focus on optimizing key engine parameters such as injection timing, injection pressure, and Exhaust Gas Recirculation (EGR) to further improve the performance and emissions profiles of GQD-enriched blends using advanced multi-objective optimization strategies.