Experimental study of EGR rate on gasoline-diesel and biofueled medium load stationary single-cylinder RCCI engine

Abstract

Reactivity-controlled compression ignition (RCCI) combustion has reasonable control over combustion duration and phasing, resulting in a drastic reduction in particulate matter and oxides of nitrogen (NOx). Exhaust gas recirculation (EGR) is an important one that greatly influences in-cylinder combustion processes and related thermodynamics. This work experimentally analyzed the effect of the % EGR rate on various parameters of the modified single-cylinder RCCI engine when running on different fuels, including gasoline and diesel, E20-B20, and E10-B10, with medium loads. It uses a comprehensive methodology that optimizes key injection parameters and focuses on EGR levels to achieve optimum thermal efficiency and minimize NOx emissions. Gasoline and blends of gasoline ethanol (E10, E20) are used as low-reactivity fuels transferred through ports, while diesel and blends of diesel-biodiesel (B10, B20) are employed as high-reactivity fuels injected directly. Direct injection is split into SOI1 and SOI2. Initially, for gasoline-diesel, E10-B10, and E20-B20, injection pressure, mass of SOI1 injection, injection timing of SOI2, injection pressure, and % EGR are optimized for maximum thermal efficiency and minimum NOx. After that, only the percentage of EGR varied. From the results, it has been observed that as compared to gasoline-diesel, for a 15% EGR rate, there is an 80% reduction in NOx for E20B20, a 9.7% reduction in HC for E10B10, an 11% rise in CO for E20B20 blends, a 71% increase in smoke opacity for the E20-B20 blend and a 3% reduction in thermal efficiency for the E10-B10 blend.