Exhaust Emissions of an Engine Fuelled by Petrol and Liquefied Petroleum Gas with Control Algorithm Adjustment

It has been shown that appropriate regulation of parameters of the gas supply system control algorithm allows to reduce the emission of selected components of the exhaust gas (carbon monoxide [CO], hydrocarbon [HC], and oxides of nitrogen [NOx]). The test engine met the Euro 6 standard on petrol and was equipped with an additional alternative multipoint fuelling system for multipoint injection (MPI) of the gaseous phase liquefied petroleum gas (LPG). The tests are comparative in nature. The first test to compare LPG petrol fuelling was carried out in the New European Driving Cycle (NEDC) where small differences in emissions were shown. The second part of the test compared emissions in the Worldwide harmonized Light vehicles Test Cycle (WLTC), wherein the initial phase there was a significant difference in emissions to the detriment of the gas supply. An innovative approach was therefore proposed to correct settings in the gas system control algorithm. In the first option, the settings for the multiplier of the opening time of LPG and petrol injectors were adjusted, resulting in a decrease in HC and NOx emissions with an increase in CO. In the second variant, the connection between the reducer and the engine intake manifold was removed, which increased the HC and NOx emissions, with a decrease in CO compared to the previous variant. In the third variant, the connection between the reducer and the engine intake manifold was restored and several coolant temperature threshold adjustments were made when switching from petrol to LPG. As a result of the corrections made in the gas system control algorithm during WLTC implementation, HC emissions were lower by 10.2%, CO by 21.2%, and NOx by 68.2% compared to the initial test.