What is Selective Catalytic Reduction?
Selective Catalytic Reduction or SCR is an elegantly simple process which bestows several major benefits to a diesel engine. The SCR system provides both increased engine efficiency and superior exhaust emissions control, whilst reducing the engines complexity and the lifetime service requirements for the engine. The result, reduced engine lifetime running costs.
Engine performance
The SCR system is based around maximised efficiency during the combustion process, ensuring maximum fuel economy and performance. When an engine is optimised to ensure maximum efficiency we see elevated combustion temperatures, leading to the formation of NOx compounds. The SCR system controls NOx emissions by a simple chemical process in the exhaust system, leaving the engine designers to concentrate on optimum performance and fuel economy. SCR engines have shown significant fuel savings over existing technologies, which lead to reduced engine operating costs.
Excellent emissions control
SCR provides outstanding control of diesel engine emissions, particularly NOx and PM. This technology can also be adopted quite simply to meet any further emissions control measures required to meet the proposed Tier 4 standards. Many of the existing emissions control systems will be incapable of meeting future standards without the adoption of SCR technology.
Reduced soot formation
Because the combustion process is optimised for efficiency and performance, the formation of soot during the engines power stroke is minimised. The resultant reduction in soot formation leads to a cleaner running engine and potentially increased engine oil drain intervals.
Cooler running
During the process of combustion a significant amount of heat energy is released. Due to its enhanced combustion an SCR equipped engine ensures this heat is not rejected into the vehicle cooling system, any surplus heat not used in creating power is rejected into the exhaust system. The SCR system reduces the need for additional or larger engine cooling packages and reduces working temperatures underneath any enclosures or shielding.
Simplicity
The SCR system significantly reduces the number of external engine components required to meet engine emissions legislation, whilst providing increased fuel efficiency and performance. Alternative emissions control technologies require complex cooling systems and external valves to control exhaust gas flow. These systems are in place to ensure combustion temperatures are closely controlled to minimise NOx formation. The SCR system reduces the need for exhaust gas flow and control, thereby reducing the complexity of the engines installation.
