Sustainable Transport using New Generations Engine and Fuels: An Experimental Study of Emissions with Biodiesel as Fuel in RCCI Engine

The increasing environmental concerns and depletion of fossil fuel reserves have necessitated the transition towards sustainable transport solutions. Biodiesel, derived from renewable sources, presents a viable alternative due to its carbon-neutral nature and compatibility with existing diesel engines. However, conventional diesel engines operating on high-temperature combustion cycles contribute significantly to nitrogen oxides (NOx) and particulate matter (soot) emissions, posing serious environmental and health challenges. To address these limitations, this study explores the use of biodiesel in a Reactivity Controlled Compression Ignition (RCCI) engine configuration, aimed at achieving cleaner combustion. A conventional compression ignition (CI) engine was retrofitted in the laboratory to function as an RCCI engine. This was accomplished by integrating a Multi-Point Fuel Injection (MPFI) system for port injection of gasoline, while biodiesel was directly injected into the combustion chamber. The experiments were conducted at three different compression ratios—16:1, 17:1, and 18:1—to evaluate the influence of compression on combustion and emissions. A programmable open-source Engine Control Unit (ECU) was employed to control the port fuel injection durations, varied at zero, three, four, and five milliseconds. The emission analysis revealed a marked reduction in NOx and unburned hydrocarbons (HC), indicating more efficient and cleaner combustion with the RCCI strategy. The dual-fuel approach facilitated better control over combustion phasing and temperature, thereby minimizing the formation of NOx while retaining the advantages of biodiesel usage. Emissions including NOx, CO, HC, CO2, and O2 were analyzed. Results indicate that NOx emissions increase sharply with load and compression ratio, while CO and HC emissions decrease, suggesting improved combustion. Fuel type significantly influences emission profiles, with some blends yielding notably higher HC and NOx. These findings help identify optimal operating conditions and highlight the tradeoffs between efficiency and emissions. These findings demonstrate the potential of RCCI engines as a transitional solution in the move towards sustainable transportation. The combination of biodiesel and advanced combustion strategies can pave the way for cleaner, lowemission engines without major alterations to existing engine platforms, thereby offering a practical and scalable pathway toward carbon-neutral mobility.