Experimental and Numerical Investigation of Combustion Chamber Modification on Combustion and Exhaust Emission in Non-Road Diesel Engine

This study compares the standart (STD) piston with a specially designed MR-1 piston that better meets modern requirements. Firstly, the experimental comparison was conducted at 3000 rpm, with static fuel injection timing advance (ITA) of (30°, 25°, 20°, 17.5°) CA BTDC, and engine load conditions of 100%, 75%, 50%, 25%. Subsequently, the combustion chambers (CCs) were simulated at the same ITA to examine in-cylinder phenomena in more detail. Analysis was performed at full load, where emissions are critical. Reducing the ITA to decrease combustion temperature and NOx emissions resulted in higher soot and UHC emissions, particularly for the STD chamber. However, this trend was not observed with the MR-1 chamber. NOx was reduced further thanks to the lower local peak temperatures, and there was no increase in soot without a significant loss in performance. The increase in UHC was negligible compared to the STD, while CO decreased. The advantages of the MR-1 can be attributed to its ability to increase air movement in the vertical direction, which is better suited for the bowl geometry and spray direction. This results in improved mixture formation in the cylinder by increasing turbulent kinetic energy (TKE) to an optimal level. Additionally, the temperature distribution is more uniform when considering dimensions, heat release duration is shortened and lower pressure and pressure rise rate are achieved.