Optimization of Combustion, Performance, and Emission Characteristics of a Reactivity Controlled Compression Ignition Engine Fueled with Hemp Oil Methyl Ester and Pine Oil Blends using Response Surface Methodology

Abstract

This study investigates the performance, combustion, and emission characteristics of a single-cylinder diesel engine in dual-fuel Reactivity Controlled Compression Ignition (RCCI) mode, using pine oil as the low-reactivity fuel (LRF) and hept seed oil methyl ester (HOME) as the high-reactivity fuel (HRF). Tests were conducted at 1500 rpm on a 5.2 kW engine with pine oil energy shares of 10%, 20%, and 30%. Response Surface Methodology (RSM) was used to optimize parameters and predict outcomes. The optimum was found at 52.88% load and 30% pine oil, where the 30P-HOME blend delivered a brake thermal efficiency (BTE) of 33.98% and brake specific fuel consumption (BSFC) of 0.24 kg/kWh. Compared to diesel, this blend increased peak in-cylinder pressure by 1.8% and heat release rate (HRR) by 8.2%, while reducing NOx and smoke emissions by 6.25% and 9.35%, respectively. The ignition delay extended to 13.6° crank angle (CA), promoting better fuel-air mixing, and the combustion duration shortened to 43.2° CA, enhancing energy release. RSM predictions closely matched experimental data with deviations within ±5%. The findings point to the prospect of pine oil and HOME blends as a sustainable and efficient alternative for RCCI engine operation.