Numerical simulation of natural gas/diesel dual-fuel engine for investigation of performance and emission

Due to global concerns about the emissions, limited hydrocarbon fuel resources and high fuel prices, a lot of researches have been done to improve the process of combustion in the internal combustion engines. Natural gas (NG) is one of the best available fuels because of its price and accessibility. On the other hand, the studies show dual-fuel combustion engines improve the reactivity of the fuel-air mixture and also increase the ignition delay (ID). In this study, NG/diesel dual-fuel engine has been simulated using AVL FIRE coupled with the kinetic mechanism and the effect of temperature and pressure at inlet valve closing (IVC) has been investigated. The results showed that with increasing the pressure and temperature at IVC, the maximum in-cylinder pressure increases, while the ID decreases. With higher pressure and temperature, the carbon monoxide (CO) level decreases. Moreover, higher pressure decreases the start of combustion temperature and carbon dioxide (CO2) while with a higher temperature at IVC both of them will be increased. It was also observed that with a higher temperature at IVC, the ringing intensity (RI) increases while with higher pressure, the RI reduces. Besides, increasing both temperature and pressure at IVC raises the thermal efficiency.