A Predictive Model for Natural Gas and Comparative Study with Gasoline Fuel for a Spark Ignition Engine

The purpose of this work was to obtain a detailed comparison of engine performance and exhaust emissions from compressed natural gas and gasoline fueled Spark Ignition (SI) engines. This research deals with a quasi-dimensional, two-zone, thermodynamic simulation of four-stroke SI engine fueled with a wide range of liquid and gaseous fuels. The results show that the power output of the engine was reduced when fueled by natural gas due to its low volumetric efficiency, but both fuels exhibited nearly equal thermal efficiency. Significant lowering of flame propagation rates with the lower hydrocarbons (methane, ethane, propane) of natural gas fueled spark ignition engine is observed with the corresponding increases in the average length of the combustion duration and ignition delay times. The validity of the model has been carried out with reliable data obtained under same engine setup and yields satisfactory agreement with the corresponding predicted values.