Analysis of RCCI engine characteristics with n-butanol/gasoline as low reactive fuel and biodiesel blend as high reactive fuel.

The rising demand for energy and environmental challenges posed by fossil fuel reliance necessitate innovative solutions in internal combustion engines. RCCI combustion has emerged as a promising strategy to address these issues by utilizing dual fuels with distinct reactivities to achieve efficient and cleaner engine operation. This study examines the performance metrics, combustion, and emission profiles of an RCCI engine, leveraging the synergistic effects of renewable and oxygenated fuels; n-butanol and gasoline as the LRF, alongside a biodiesel blend (B20) as the HRF. The experiments were conducted on a modified single-cylinder CI engine specifically adapted for RCCI operation, where the LRF was introduced through port injection and the HRF was injected directly. The experiments were conducted at a maximum load of 80%, varying speeds, and different fuel blend ratios. The port-injected fuel mixture was composed of varying volume fractions: 5% gasoline and 15% n-butanol (G25n-b75), 10% gasoline and 10% n-butanol (G50E50) and 15% gasoline and 5% n-butanol (G75n-b25). The mixtures were blended and made up 20% of the total fuel, while the remaining 80% was the biodiesel-diesel blend (B20) used in direct injection for RCCI engine mode investigation. The findings indicate that the B20+G50n-b50 configuration achieved the highest cylinder pressure of 92.25 bar, significantly exceeding the baseline fuel's 57.24 bar at 2800 rpm. Among tested configurations, B20+G50n-b50 demonstrated the optimal performance, achieving the highest brake power (4.35 kW). The lowest NOx (150 ppm) and CO (3.7 vol%) emissions were achieved with engine operated B20+G25n-b75 configurations at 2800 rpm. The CO and HC emissions rise with B20+G25n-b75 and B20+G50n-b50, whereas B20+G75n-b25 achieves the lowest emissions. This can be considered a novel finding, demonstrating CO and HC emissions reduction through RCCI in this study. The study highlights the capability of RCCI engines to attain exceptionally low emissions levels when utilizing renewable fuel blends. These findings provide important insights into fuel optimization and emission reduction methods for RCCI applications, advancing cleaner and more sustainable engine technologies.