NOx reduction

NOx Reduction

Reduction of NOx emissions has been our major development focus for over 20 years. To comply with currently valid and future emission standards we offer a variety of primary and secondary measures. With MAN Energy Solutions technology, ship owners and operators can adopt NOx reduction systems in their fleets at an early date. 

Primary measures for NOx reduction

Primary measures are fully integrated into the engine design and reduces NOx formation during the combustion process. They provide an advantage to shipyards via simplicity of the propulsion system and benefit operators with no additional consumables. Improved engine efficiency and ideal dynamic operating parameters are achieved by:  

  • Optimized combustion-chamber geometry for superior combustion and avoidance of temperature peaks that produce NOx formation
  • Optimized fuel injection, including Common Rail Technology (CR), developed by MAN to decrease combustion temperature and NOx formation while improving engine performance, reducing emissions and minimizing fuel consumption
  • The Miller cycle, plus MAN-developed Variable Valve Timing System, reduces temperature peaks and NOx formation, eliminating particle matter during part load operation
  • High-efficiency turbochargers ensure unrestricted quantity of combustion air entering the cylinder for high engine performance and efficiency

Turbocharger with variable Turbine Area

VTA technology can be retrofitted for turbochargers already in the field
 common rail fuel injection system

The common rail fuel injection system

allows a very precise and flexible control of injection pressure, timing and duration throughout an engine’s entire operating range. 

Secondary measures for maximal NOx reduction: Selective Catalytic Reduction

As there is only a limited scope to reduce NOx emissions solely through optimized combustion, MAN Energy Solutions offers its customers technically sophisticated secondary measures which can be readily added to the basic engine configuration in order to meet tighter emissions regulations.

Selective Catalytic Reduction (SCR) is MAN’s core NOx reduction technology for four-stroke engines to reach IMO Tier III limits. NOx emissions can be reduced up to 90%. The Tier III conformity of a MAN 8L21/31 four-stroke engine with a SCR system has already been officially certificated by the classification society DNV GL. As a leading engine builder in the marine sector, MAN Energy Solutions designs and delivers highly efficient SCR systems for new engines. SCR systems can be retrofitted on engines already in the field.


SCR technology

The next step on the road to Tier III 

All data provided on this site is for information purposes only, explicitly non-binding and subject to changes without further notice.