What is the reason of NOx emissions in the engine?

Why are NOx gases produced? High temperature combustion of fuels where the temperature is hot enough (above about 1300°C/ 2370°F) to oxidise some of the nitrogen in air to NOx gases. This includes burning hydrogen, as it burns at a very high temperature. Comments on diesel engines are shown below.

At what air fuel ratio are NOx emissions maximum for spark ignition engines and why?

In spark ignition petrol engines maximum emission of NOx takes place when the air fuel ratio (A/F) is. rich mixture and A/F ratio about 13.

How does air fuel ratio affect CO emissions?

CO emissions drop sharply when air/fuel mixture changed from rich to lean operation. The CO value between λs is not mainly due to which reaction is in favor, but due to the amount of its precursors. • Almost all the NO is produced by the thermal-NO mechanism.

Why is stoichiometric air fuel ratio important?

The air–fuel ratio is a significant indicator and very important measure for gasoline engine performance controlling and tuning, and anti vehicles exhaust emissions pollution reasons. The AFR called or known as stoichiometric mixture when the provided air is exactly enough to completely burn all of the gasoline fuel.

What AFR is lean?

When there is not enough fuel, it is lean. An AFR higher than stoich = lean. An AFR lower than stoich = rich. A lambda value higher than 1 = lean. A Lambda value lower than 1 = rich.

What is the stoichiometric air/fuel ratio?

about 14.7:1
Engine management systems For gasoline fuel, the stoichiometric air–fuel mixture is about 14.7:1 i.e. for every one gram of fuel, 14.7 grams of air are required.

How does the emission of CO carbon monoxide vary with the increase of air to fuel ratio?

Carbon monoxide correlates with the oxygen content in the flue gases. Low excess oxygen increases CO formation. The higher the air ratio and the better the mixing, the lower is the CO emission.

What is the reason for increasing the air fuel ratio of a mixture?

Higher compression ratio and larger piston bore in an engine produce higher power and torque. The higher compression in a combustion chamber makes the air and fuel particles compressed in larger density and in high pressure. Larger piston geometry (bore) will let more air passing through the combustion chamber.