Investigation of piston bowl geometry, injection timing, and EGR mass fraction to improve the performance of ISM 370 diesel engine

Abstract

In addition to the high price of clean fuels such as hydrogen and bio-propane, redesigning a diesel engine for clean fuels can be a costly task. It seems an affordable option is to improve the baseline engine specifications by slight changes in the injection strategy or piston bowl shape. In this paper, the emission and combustion characteristics of the ISM 370 heavy-duty diesel engine were numerically investigated by evaluating three distinct piston bowls (P1, P2, and P3), different injection timings, and an exhaust gas recirculation (EGR) system. After that, the outcomes were compared with previous works related to the use of clean fuels in the ISM 370 engine. The simulation was performed at 1200 rpm engine speed and full load state. The rate of heat released and the mean in-cylinder pressure results were compared with experimental data and an appropriate accord was obtained. The results showed that the best injection timing considering a balanced state between the emission and combustion characteristics was determined 2 deg before the top dead center (BTDC). The same carbon dioxide (CO2) mass fraction was predicted for all considered piston bowls at almost the exhaust valve opened. P2 had better thermal efficiency and internal power by around 12% and the same nitrogen monoxide (NO) emissions as well as lesser soot emission by 10.5% compared to P1. A more complete combustion reaction was detected for the engine equipped with P2 led to reducing the CO mass fraction by 20% compared to P1. In addition, a 10% EGR mass fraction reduced the NO by 37% and increased the CO2 by 6.4%. It was found that the use of P2 had better peak pressure compared to the use of methanol fuel by 20.9% and was competitive with dimethyl ether fuel at almost equal peak pressure and 30% lesser soot emission.