Impact of compression ratio on combustion behavior of hydrogen enriched biogas-diesel operated CI engine

• Published in: Fuel (Guildford) 2022-02, Vol.310, p.122321, Article 122321
• Main Authors: Rosha, Pali, Kumar, Sandeep, Senthil Kumar, P., Kowthaman, C.N., Kumar Mohapatra, Saroj, Dhir, Amit
• Format: Article
• Language: English
• Subjects: Alternative gaseous fuel; Biogas; Brakes; Carbon monoxide; Co-combustion; Compression; Compression ratio; Compression tests; Diesel engines; Dual fuel engine; Emissions; Energy-efficient gaseous fuel; Engine characteristics; Exhaust pipes; Experimentation; Fumigation; Gaseous fuels; Hydrogen; Hydrogen enrichment; Ignition; Nitrogen oxides; Opacity; Pressure; Smoke
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2021.122321

•Engine characteristics were analyzed at different compression ratio.•Hydrogen enriched biogas consist of H2, CO, CH4 and traces of N2.•Engine performance is improved with respect to compression ratio.•NOx emission increased with increasing compression ratio. This experimental study investigated hydrogen-enriched biogas (gaseous fuel) and diesel (pilot fuel) in a compression ignition engine at variable compression ratios. Afumigation technique was employed to inject simulated hydrogen-enriched biogas (0.5 kg/h) in a 3.5 kW dual-fuel compression ignition engine. Experimentation was carried out by varying the brake mean effective pressure in the range between 0 and 3.5 bar at engine speed of 1500 rpm. Results illustrated that the ignition period decreased from 22.9 to 18.5 °CA with an increased compression ratio (16:1 to 18:1), specifically at brake mean effective pressure of 3.5 bar. Under the same loading conditions, the peak cylinder pressure and thermal brake efficiency continuously increasing w.r.t. compression ratio and attained a maximum value of 54.1 bar and 36.1 %, respectively, at a compression ratio of 18:1. Contrary, the continual decrement in HC, CO, and smoke opacity was identified concerning compression ratio; however, NOx formation was found to be higher at elevated compression ratio. Further, at 3.5 bar (BMEP), the tailpipe emissions assessed were: HC (8.2 g/kWh), CO (0.09 %), smoke opacity (37 %), and NOx (16.5 g/kWh), corresponding to the compression ratio of 18:1. It is inferred from this study that using hydrogen-enriched biogas at a higher compression ratio improves the engine performance to a great extent, along with emissions reduction.