Effects of injection strategies coupled with gasoline-hydrogenated catalytic biodiesel blends on combustion and emission characteristics in GCI engine under low loads

The Gasoline Compression Ignition (GCI) engine is one among the most advanced combustion mode engines, having high thermal efficiency with lower nitrogen oxides and particle emissions simultaneously targeted for upcoming emission regulations. The engine's practical applications are limited by its igniting difficulty and combustion stability at low loads. In order to address these issues, a novel type of high reactive fuel known as hydrogenated catalytic biodiesel is mixed with gasoline as fuel in various ratios (20-40%) and its combustion and emission parameters are studied at low loads. Experiments were carried out in single and double injection mode to find out optimum engine conditions by varying start of injection timings (-7 to-13 deg. CA aTDC). Further, in double injection mode with different pilot fuel injection ratios from 20 to 40% and pilot fuel injection timings from-60 to-40 deg. CA aTDC. The experimental results show that stable combustion is achieved at low loads by using this test fuel without having any ignition difficulty or combustion assistance. The findings of the single-injection mode show that delaying the injection timing resulted in lower maximum pressure rise rate, nitrogen oxide emissions and nucleation mode number concentration emissions under low load conditions. The double injection mode controls the maximum pressure rise rate and cyclic variations within the controlled range under all conditions. From different test conditions, a lower pilot injection ratio (20%) during the advanced start of injection (-60 deg. CA aTDC) condition is recommended because it shows better combustion and emission results. Overall, the gasoline-hydrogenated catalytic biodiesel blend could be the fuel for GCI engines and it is effective at tackling low load difficulties.

Automated summary

The Gasoline Compression Ignition (GCI) engine is an advanced combustion mode engine that achieves high thermal efficiency while meeting upcoming emission regulations. However, it faces difficulties in igniting and maintaining stable combustion at low loads. To address these issues, a new high reactive fuel called hydrogenated catalytic biodiesel is mixed with gasoline in various ratios and its combustion and emission parameters are studied. The experimental results show that stable combustion can be achieved at low loads using this fuel blend. Delaying the injection timing in the single injection mode results in lower nitrogen oxide emissions and nucleation mode number concentration emissions under low load conditions. The double injection mode controls the maximum pressure rise rate and cyclic variations within a controlled range. From the different test conditions, it is recommended to use a lower pilot injection ratio (20%) during advanced start of injection (-60 deg. CA aTDC) as it yields better combustion and emission results. Overall, the gasoline-hydrogenated catalytic biodiesel blend shows promise for GCI engines in tackling low load difficulties.