Hydrogen Induction in a Dual-Fuel Mode Common Rail Direct Injection Compression Ignition Engine Running on Ethanol–Diesel Blends: Combustion, Performance, and Emission Characteristics

Abstract This study investigates the simultaneous incorporation of ethanol and hydrogen (H2) as a potential alternative to conventional diesel in a common rail direct injection compression ignition engine. Ethanol was blended with diesel in varying proportions (10–40%) and investigated at three H2 flowrates (5, 10, and 15 LPM). The results reveal a complex interplay between combustion characteristics, performance, and emissions. Increasing ethanol content reduced peak cylinder pressure and net heat release rate across all H2 flowrates, while higher H2 flowrates improved these metrics for specific blends. The brake thermal efficiency (BTE) improved with increasing H2 flowrates. Additionally, brake-specific fuel consumption (BSFC), carbon monoxide (CO), unburnt hydrocarbon (HC), and smoke emissions decreased with the addition of H2. However, at a specific H2 rate, these parameters increased with higher ethanol percentages, while nitrogen oxide (NOx) emissions followed an opposite trend. Overall, substituting 30% diesel with ethanol and incorporating 15 lpm H2 (D70E30 + 15 LPM H2) resulted in higher BTE and reduced BSFC, CO, HC, smoke emissions, and NOx emissions comparable to that of neat diesel.