Optimization of CNG injection duration on combustions and emissions characteristics on CNG-CPO biodiesel dual fuel engine with load variations

Abstract

The number of CNG substitution on dual fuel engine affects engine performances and emissions. Thermal efficiency and air fuel ratio (AFR) decreased significantly with the addition of CNG quantity, and also increased emissions of carbon monoxide and hydrocarbon. The injection duration acts as a controller for the amount of CNG injected into the cylinder, so that the right injection duration was needed to get better engine performances and emissions, taking into account the percentage of CNG substitution. The study was carried out experimentally on a dual fuel CNG-CPO biodiesel engine by varying the duration of CNG injection from 70°-150° CA with 20° intervals on all engine loads (low, medium, and high). The results showed that the injection duration of 70° CA was more optimally used under lower load, and in the medium load obtained the injection duration of 90° CA, and the duration of injection of 110° CA was more appropriately used under high load, this was evidenced by increased combustion performances and emissions were better than other variations.