Emitted NOx from a Spark Ignition Engine Fueled With Natural Gas

Gaseous fuels are widely accepted as an alternative to gasoline because it reduces emissions from the engine after burning. Iraq today is considered one of the most countries with a large stock of natural gas and has begun to produce and export to the world. So, using this gas as a vehicle fuel has become a matter of time. In this study, we investigated the NOx exhaust pollutants emitted by a single-cylinder spark ignition engine. The results showed that natural gas can act as a fuel in spark ignition engines with no change in engine design with low NOx levels. If the compression ratio of the engine is increased to the higher useful compression ratio of natural gas, the NOx concentrations increase. These concentrations are also increased by advancing the spark timing away from the optimal timing. The results showed that the most significant parameter that affects the increase of NOx is the equivalent ratio. NOx levels rise at an equivalence ratio of 0.95 and reduce in the lean and rich sides.