Effect of Premixing Ratio on the Deterministic Characteristics of Combustion Dynamics Butanol-Diesel RCCI Engine

The rising demand for vehicles has increased CO and HC emissions, worsening air quality and contributing to climate change, key issues under the clean development mechanism and UN SDG 13: Climate Action. Reactivity-Controlled Compression Ignition (RCCI) offers a promising solution to reduce PM and NOx while maintaining fuel efficiency. However, the cyclic variation of the RCCI engine remains an underexplored area in control strategies, necessitating further research for optimization in line with sustainable development goals. This study explores the impact of premixing ratios on RCCI engines fueled with butanol and the nature of cyclic variation to know the controllability. Tests were conducted on a single-cylinder diesel engine at 1500 rpm and constant engine load. The experiments reveal that increasing the premixing ratio from 45% to 60% decreases the heat release rate by 15%, Pmax by 10%, and IMEP by 12%. Recurrence Quantitative Analysis (RQA) confirmed strong deterministic combustion patterns, with determinism exceeding 85%. Multifractal Detrended Fluctuation Analysis (MFDFA) indicated that the Total Heat Release (THR) time series exhibited the least multifractality (∆α = 0.15) compared to Pmax and IMEP. These findings provide essential insights for optimizing RCCI control systems, enabling improved performance across varying operating conditions.