Nitrogen Oxides (NOx) are the most difficult exhaust pollutants to control. They are not fuel based but are produced by the oxidation of nitrogen in the combustion air and their formation requires high temperatures (2500°F—1370°C and above). The higher the temperature, the more NOx is produced, thus, NOx output is directly proportioned to engine power and efficiency.

Ammonia is a unique and effective reducing agent for oxides of nitrogen (NOx). It reacts far more rapidly than hydrogen or carbon monoxide, and most importantly, unlike these other choices, is effective even in the presence of oxygen.

In the KleenAir Systems approach, a very small amount of gaseous ammonia is metered in to the exhaust system in proportion to the NOx being formed.

• Cut NOx output
• Lowest cost
• Least Maintenance
• Achieves local air quality legislations

The temperature range for effective reduction of NOx with ammonia is 1200ºF to 1800ºF (650°C—980°C). Above 980C, ammonia is itself oxidised (to NOx). Between 1200°F and 1800°F provides a window where NOx is reduced without the ammonia being oxidised. With the presence of an SCR catalyst, this temperature can be significantly lower—as low as 350°F (176°C)
In an operational NOxMaster system, KleenAir uses gaseous ammonia which is metered into the exhaust system via a valve or pulsed solenoid. The amount of ammonia required is quite small—in the range of 1Kg per 1000 litres of fuel consumed for heavy duty engines.
To optimise NOx reduction and minimise the quantity of ammonia needed, the NOxMaster system introduces ammonia in direct relationship to the concentration of NOx in the exhaust. This requires a knowledge of both the concentration of NOx in the exhaust, and also the quantity of exhaust gas.
It was discovered that there was one engine parameter that would combine both the concentration function and the amount function of NOx in the exhaust. This is simply the fuel flow rate. The NOxMaster system therefore, injects ammonia in proportion to NOx as measured by the fuel flow to the engine.
The NOxMaster can be adapted to a variety of engine types and sizes by variation of the pulse rate, valve orifice and or ammonia supply pressure providing a unique and flexible system.