Optimization of pilot diesel injection timing on load variation dual fuel diesel-CNG engine on combustions and emissions characteristics

The use of CNG fuel in a dual fuel diesel-CNG engine as an alternative decreases the engine performance and increases emission. Pilot injection timing acts as an ignition delay controller by controlling the initial diesel fuel injection. This research is conducted on a single cylinder dual fuel diesel-CNG engine by advancing the pilot injection timing by 11°, 13°, 15°, 17° and 19° BTDC at different loads in order to optimize diesel pilot injection timing. The results have showed that the optimal pilot injection timing has shifted from 17° BTDC to 15° BTDC along with the addition of loads from low to high, marked by an increase in maximum thermal efficiency of 25.27% and a minimum reduction of HC and CO emissions of 23.07% and 26.6% respectively. In addition, it causes an increase in ignition delay of 23.53% and a decrease in combustion duration of 35.3%, which is indicated by an increase in the maximum cylinder pressure value of 30.05% and a heat release rate of 54.85%.