Power and efficiency improvement of SI engine fueled with boosted producer gas-methane blends and LIVC-miller cycle strategy: Thermodynamic and optimization studies

An appealing alternative solution for lowering both reliance on power grid and pollution is by adopting decentralized power generation using gasifier-engine integrated systems. However, the utilization of gasification-derived producer gas (PG) leads to low engine power output and efficiency as compared to conventional fuels. This pertains to its low Calorific value(CV) and low flame-speed. Therefore, this simulation study aims to simulate and investigate the improvements in these parameters by inspecting various boosted-intake pressures and blends of high-CV methane with PG as inputs along with the implementation of Late inlet valve close(LIVC)-Miller cycle strategy on a 1500 RPM Dual-fuel(DF) SI engine model. Quasi-dimensional thermodynamic modelling (QDTM) was applied to simulate this performance and emission investigation by considering Sewage sludge-based PG (SSPG) as the PG variant. Best operational input settings were found using the Response Surface Methodology(RSM)-based multi-objective optimization. These optimal inputs were 3 bars of Pressure at intake valve closure (PIVC), 76.94 % SSPG-blend, and 77.32⁰ (ABDC) LIVC. The responses were correspondingly predicted as 40.46 % ITE, 21.35 bars IMEP, 16.8 kW BP, 20.04 bars BMEP, 9.48 MJ/kWh BSEC, with 0.08 V% CO and 3094 ppm NO emissions. Finally, with the ANOVA-based analysis, a 0.712 composite desirability was achieved with 95 % confidence level.