in HCCI engine,compression ignition is attained so high compression ratios are maintained to get auto-ignition of fuel-air mixture as this engine is combination of petrol and diesel engine. At high temperatures, NOx is formed as in case of diesel engine due to oxidation of N but I have studied that in HCCI engine NOx emission is lowered. How?
Firstly, the temperature inside the HCCI engine is bound to be at a low level. Compared with the diesel engine, the compression ratio is higher so that the petrol can be ignited (the ignition pressure is higher). Under higher pressure, the concentration limitation of petrol - air mixture is lower than usual conditions. As a result, the temperature is lower than traditional engines which helps reduce the NOX emission.
On the other hand, HCCI is the abbr for Homogeneous Charge Compression Ignition. Due to the "homogeneous", no local high temperature can be found during the combustion process. Hence, less NOX is produced.
What's more, in order to control the combustion process EGR is used which also contribute to decrease the temperature inside the combustion chamber.
Hope this helps~
Firstly, the temperature inside the HCCI engine is bound to be at a low level. Compared with the diesel engine, the compression ratio is higher so that the petrol can be ignited (the ignition pressure is higher). Under higher pressure, the concentration limitation of petrol - air mixture is lower than usual conditions. As a result, the temperature is lower than traditional engines which helps reduce the NOX emission.
On the other hand, HCCI is the abbr for Homogeneous Charge Compression Ignition. Due to the "homogeneous", no local high temperature can be found during the combustion process. Hence, less NOX is produced.
What's more, in order to control the combustion process EGR is used which also contribute to decrease the temperature inside the combustion chamber.
Hope this helps~
- Badges
- Science topic
- Similar topics
- Engineering
- Mechanical Engineering