Performance, Emission and Combustion analysis of a Hydrogen enriched methanol fueled SI Engine

Abstract

The study of potentially high rated alternative fuel (Methanol) for the IC engines is an exciting topic in the recent research advancement. The characteristics of methanol are distinct yet promising in terms of combustion, renewability, and sustainability. The experimental trials were conducted in wide-open throttle conditions (WOT) for different speeds ranging from 1200 rpm to 1800 rpm at an interval of 200 on a single-cylinder four-stroke variable compression ratio (VCR) SI engine. Initially, the quantitative analysis of different methanol/gasoline blends ratios was conducted to study the engine characteristics. Later, a quantitative analysis of the M50 fuel blend was done for different ignition timing (18° BTDC - 24° BTDC) and compression ratio (8, 9 & 10). The study of high fraction methanol blends fueled in the standard SI engine model provides the convenience of the use of methanol in IC engines with small operating changes. It also guides the researchers to explore the effect of change of operating parameters with a small modification to the existing engine that can operate with neat methanol. The present investigation's main objective is to study the performance, combustion, and emission characteristics of methanol fueled SI engine and further enrich with hydrogen fuel. The experimentation was conducted for four different compression ratios (11,12,13 and 14) at a different speed range of 1400 rpm to 1800 rpm, and the engine operated with WOT condition. The experimental data reveal that SI engine fuelled with neat methanol works smoothly and showed good results with compression ratio CR14. Further, the experiments were conducted by fixing the Compression ratio to CR14, and the ignition timing was optimized for a better outcome. Hence trials were conducted for different ignition timings (18° BTDC to 26° BTDC with a 2° crank angle difference). The performance evaluation suggests that neat methanol showed a difference of nearly 30 % improvement in BTE with CR14 and 8% further enhancement with the ignition timing of 20° BTDC. Methanol with lower energy content has a lower power output than gasoline and susceptible to an increase in specific fuel consumption. In this present case, neat methanol is operated with a higher compression ratio, which has a big impact on increased power output compared to lower CR (an increase of BP by 21% with CR14 compared to CR11). Undoubtedly, the low carbon composition of methanol is expected viii to produce fewer oxides of carbon, HC. In addition to this, reduced in-cylinder temperature, directly reflecting on the reduction of NOx emissions. The effect of enriching methanol-fueled SI engine with hydrogen gas is studied in the present work. In the experiments for a different set of trials, including hydrogen enrichment ranging between 5% to 20% in volume with a 2.5% increment, the engine is operated with wide-open throttle (WOT) condition for different speeds. The percentage increase in performance is between 20-30%, and an increase in hydrogen beyond 12.5% would affect the volumetric efficiency, and thus performance declines after that. The exhaust emissions have a huge impact on hydrogen enrichment; CO, HC, and CO2 emission are reduced by 30-40%, whereas an increase in cylinder temperature due to rapid combustion slightly increases the NOx emission. Finally, this research project aimed to study the feasible techniques related to the use of methanol in the SI engine and ensure smooth working capability without compromising efficiency and exhaust emission. The intention was also to focus on new combustion engine technology concepts, which can be co-developed with alternative renewable fuels. It was a conscious effort to work towards securing energy resources and provide a viable option for sustainable transportation technology. It also suggests the creation of a huge opportunity in the field of production and supply of sustainable alternative fuel.