Marine Engineering

There are two methods to reduce NOx emissions; Primary and secondary measures.  Primary measure aim at reducing the amount of NOx formed during combustion by optimizing engine parameters with respect to emissions. As read in previous article , the  main factors influencing NOx formation  are the concentrations of oxygen and  nitrogen and the local temperature in  the combustion process. Therefore,the  primary measures focus on lowering the  concentrations, peak temperature and the  amount of time in which the combustion  gases remain at high temperatures. Miller cycle is employed in 4-stroke  engines. It uses higher than normal  pressure turbocharger. The inlet valve is  closed before the piston reaches bottom  dead center on the intake stroke. The  charge air then expands inside the engine  cylinder resulting in reduced temperature. On the other hand, secondary measures remove NOx from the exhaust ga...