Thermodynamic analysis of CNG DI engine operating with different spray angle

Implementation of natural gas as the fuel of internal combustion engine is increasing in order to discover the environmental friendly technology. However, there is a drawback in implementing natural gas as fuel which is engine power output. To overcome this drawback, improving combustion process of natural gas by regulating spray parameter is a way to increase the engine power output and reduce emission. In this experiment, the spray parameter that is focused on is the injector spray angle. This investigation used a direct injection CNG system in a dedicated single cylinder research engine with 14 compression ratio. While, two injector spray angle were investigated, wide angle injector (WAI) and narrow angle injector (NAI). Both injector angles were investigated on its effect on three injection timings; 300 BTDC, 180 BTDC and 120 BTDC, for the engine speed 2000 RPM. It was observed that the NAI has higher overall combustion performance compared to WAI for all injection timing as shown by higher maximum pressure, faster combustion duration, and higher NOx emission. While on the other hand, WAI has more stable combustion which is indicated by lower COV at all injection timing. Furthermore, injector spray angle has less effect to the combustion on the injection timing of 180 BTDC where both angles show similar combustion behavior.