A Holistic Approach to Reactivity-Controlled Compression Ignition Engine Performance: ۴E Analysis (Evaporation, Energy, Emissions, Exergy) and Multidimensional Efficiency Metrics under Varying Engine Speed

This study investigates the performance of Reactivity-Controlled Compression Ignition (RCCI) engines under varying engine speeds using a ۴E approach (Evaporation, Energy, Emissions, Exergy) and introduces innovative multidimensional efficiency indices. A ۱.۹-liter TDI Volkswagen engine was modeled in CONVERGE CFD software to analyze spray dynamics, combustion processes, and emissions across different engine speeds. New indices, including Evaporation-Energy Performance Index (EvEPI), Emission-Energy Synergy Index (EmESI), and Exergy-Emission Balance Index (ExEmBI), were developed to evaluate engine performance comprehensively. Results reveal that optimal performance occurs within ۱۶۰۰–۲۲۰۰ RPM, where fuel evaporation, combustion efficiency, and exergy utilization are maximized while emissions are minimized. For instance, at ۳۱۰۰ RPM, EvEPI increases sharply to ۹۸۵۷.۱۷ mg/ms, reflecting enhanced evaporation but also highlighting risks of non-uniform fuel-air mixing at high speeds. Conversely, EmESI for HC rises from ۳۳.۰۴ gr/kW.h at ۱۰۰۰ RPM to ۲۸۴.۹۰ gr/kW.h at ۳۱۰۰ RPM, indicating increased unburned hydrocarbons due to incomplete combustion. NOx emissions decrease from ۱۱.۵۱ gr/kW.h at ۱۶۰۰ RPM to ۲.۲۸ gr/kW.h at ۳۱۰۰ RPM, aligning with reduced combustion temperatures. Higher speeds lead to elevated HC and CO emissions due to shorter mixing times, while lower speeds increase NOx due to prolonged combustion durations. Exergy analysis shows total and second-law efficiencies peak at lower speeds, emphasizing the importance of optimizing operational parameters. These findings provide valuable insights for designing efficient, low-emission RCCI engines.

کلیدواژه ها:

RCCI Engine ، Engine Speed ، Multidimensional Efficiency Indices ، Exergy Analysis ، Emissions