NUMERICAL STUDY ON A NATURAL GAS-FUELED ENGINE UNDER LOW TEMPERATURE COMBUSTION MODE

Abstract

Natural gas, which is also referred to as eco-friendly fuel, is being seen as a potential solution to challenge the decline of crude oil resources and the deteriorating air quality in urban areas. This fuel has been verified to emit less CO, HC, and PM compared to other fuels. A potential approach to reducing NOx and soot emissions while also achieving low fuel consumption is the low temperature combustion process. In this study, internal combustion engines were simulated under various conditions. The objective was to investigate the effect of different operating variables on the low temperature combustion mode. To begin with, a natural gas powered engine was modeled using complex chemical kinetics software. The outcomes of the simulation were then compared to experimental data, demonstrating a high level of agreement. Subsequently, the impacts of key variables, including the air-fuel ratio, compression ratio, and engine speed, were analyzed using a cycle simulation code. Increasing the compression ratio improves engine performance, and the specific fuel consumption decreases. However, it leads to a significant increase in NOx emissions until a certain value. Thereafter, it changes the trend. Engine speed indirectly affects performance by increasing fuel consumption and changing ignition timing. A leaner air fuel ration may be used to produce more power and keep the temperature of combustion below a certain value (low-temperature combustion), ensuring low NOx emissions.