Effects of graphene quantum dots on droplet combustion of ternary diesel/palm-oil biodiesel/waste plastic oil blends
Year: 2026
Type: article
Abstract: Reducing diesel reliance while valorizing plastic waste presents a dual challenge in sustainable fuels research. This study investigates, for the first time to the authors' knowledge, the droplet-scale combustion behavior of ternary diesel/palm oil biodiesel (POB)/waste plastic oil (WPO) blends comprising 80% B20 (80% diesel +20% POB) and 20% WPO by volume doped with graphene quantum dots (GQDs). Droplets containing 20, 40, and 80 ppm GQDs were characterized using shadowgraph imaging and in-situ temperature measurements. All experiments were conducted at ambient conditions (≈25 °C, 1 atm) using suspended droplets with an initial diameter of approximately 1.8 mm. Combustion progressed through repeatable stages: ignition, unsteady burning, quasi-linear regression, and final steady shrinkage. GQD addition significantly modified the unsteady burning phase by intensifying bubble growth and micro-explosions at moderate loading (notably 40 ppm), shortening burning duration by 24.9% and increasing the mean effective combustion rate constant by up to 38.1% compared with the undoped blend. Ignition delay showed a non-linear trend, increasing by 35.8% at 40 ppm due to nanoparticle-induced thermal resistance before slightly decreasing at 80 ppm as internal heat retention promoted vaporization. Post-ignition temperature gradients increased sharply across all blends, while GQDs moderated these surges through improved thermal conductivity and volatile transport, producing more stable heat release within the droplet. These findings highlight GQDs as an effective additive for multicomponent fuels, offering mechanistic insight into promoting controlled micro-explosions and stronger post-ignition combustion at the droplet scale, with implications for spray combustion.
Authors: Chee Choy Chow, Yew Mun Hung, Jong Boon Ooi
Institution: Monash University Malaysia
Language: English
Subfield: Fluid Flow and Transfer Processes
Field: Chemical Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,560
OpenAlex ID: W7163044071