Diesel−palm biodiesel blend could be an attractive fuel for diesel vehicles owing to its better physicochemical properties compared to those of fossil diesel. This study comprehensively investigates the combustion behavior of diesel droplet blended with palm biodiesel at 20% v/v, 40% v/v, and 60% v/v (i.e., B20, B40, and B60, respectively). Droplet combustion experimental results show that the B60 and palm biodiesel droplets exhibit a more prominent blue flame and less sooty flame compared to diesel droplet. Compared to those of diesel droplet, the ignition delay and burn-rate constant for B60 droplet increase by 27.0 and 56.3%, respectively, whereas, the burning duration of B60 droplet decreases significantly by 17.7%. Overall, this study suggests that B60 could be an effective fuel for improving the combustion and emission characteristics of diesel engines and has the potential to be utilized for other combustion-related applications.

Malaysian palm biodiesel is one of the attractive biofuels for petroleum diesel due to its zero-sulphur content (i.e., non-toxic), renewable capability, and similar physicochemical properties. Recent studies have reported significant improvement in the performance and emission characteristics of diesel engines by leveraging the blending composition between palm biodiesel and diesel. However, the fundamental aspects of combustion performance due to the blending effects of Malaysian palm biodiesel remain unexplored. This study aims to investigate the isolated droplet combustion behaviour of palm biodiesel-diesel blends at various blending compositions through a time-based image capturing method. Experimental results show that palm biodiesel-diesel blend with 60% palm biodiesel content (B60) and above produce a more prominent blue flame, which indicates cleaner and more complete combustion. The ignition delay (ID) increased when the palm biodiesel content is increased. Similarly, the burn rate constant for palm biodiesel-diesel blends increased with increasing palm biodiesel content. The combustion duration of palm biodiesel-diesel blends increased slightly when the palm biodiesel content is raised to 40% (B40) but decreased significantly when the palm biodiesel content is at 60% and above. Overall results suggest B60 is the optimum blend, which could potentially improve the performance and emissions of diesel-powered vehicles.