Experimental Study on GDI In-Cylinder Combustion Quality of Ethanol and Lemon Peel Oil

A Gasoline Direct Injection (GDI) engine’s performance and emissions are greatly impacted by the fuel injection phenomena. It is critical to understand biofuel’s spray structure and combustion quality before using it in a GDI engine. This study investigates the combustion quality at different Start of Injection (SOI) timings using an optical GDI engine. Lemon Peel Oil (LPO) and ethanol are prepared on a volume basis, and three different SOI timing are selected to study the spray effect on combustion. Two binary blends and one ternary blend are prepared in different volume bases for this purpose: G60L40 (60% gasoline and 40% LPO), G80E20 (80% gasoline and 20% ethanol), and G40E20L40 (40% gasoline, 20% ethanol, and 40% LPO), and the effect of the thermophysical properties of the fuel blends on combustion characteristics are evaluated. In-cylinder combustion imaging revealed that injection timing significantly impacts combustion. The addition of ethanol improves the combustion, but LPO blends showed higher residence of diffusion burning due to poor evaporation characteristics.