AN IMPACT OF COMBUSTION CHAMBER GEOMETRY ON CHARARACTERSTICS OF A DIESEL ENGINE FUELLED WITH GARCINIA GUMMI-GUTTA METHYL ESTER (GGGME)

Environmentally sustainable and renewable fuels present clear advantages over conventional petroleum-based fuels, offering improved energy utilization and helping to alleviate environmental and socioeconomic concerns. Their adoption in transport and power production supports cleaner energy transitions and assists in addressing emission-driven climate change challenges. In this investigation, combustion performance and emission characteristics were improved by redesigning the piston bowl geometry to intensify air–fuel interaction and in-cylinder turbulence. Three combustion chamber configurations were examined: a toroidal re-entrant combustion chamber (TRCC), a standard toroidal combustion chamber (TCC), and a shallow re-entrant combustion chamber (SRCC). The results obtained with diesel fuel were compared against those achieved using an optimized best fuel (BF) blend. The TRCC configuration exhibited the most favorable performance. It delivered a 4.85 % increase in brake thermal efficiency (BTE) and achieved significant emission reductions, including 41.6 % lower hydrocarbon (HC) emissions, 52.4 % reduction in carbon monoxide (CO), and 68.9% decrease in smoke opacity compared with diesel operation. These outcomes highlight the effectiveness of combustion chamber modification in enhancing engine efficiency while substantially reducing exhaust pollutants.