Combustion Optimisation of 2.5 litre IDI Engine To meet Euro-II Norms 2001-26-0026
Vehicle exhaust pollutants are hazardous to mankind. An engine with low exhaust pollutants is the need of clean environment. Hence, progressively more stringent emission legislations are being enforced to ensure that future engines are less polluting.
Scope of this work is to re-design and re-optimise the combustion system of 2.5 litre indirect Injection (IDI) Naturally Aspirated (NA) engine to comply with Euro-II norms.
This was possible by redesign of pre-combustion chamber, re-orientation of glow plug in pre-combustion chamber, redistribution of main chamber to pre-combustion chamber volume, piston cavity, ring pack and introduction of valve stem seals on intake valve to reduce oil consumption.
A three-step process was used to optimise emission performance of the engine. In step one, steady state optimisation was done on engine dynamometer. Low target smoke and PM were achieved by optimisation of fuel injection equipment (FIE) hydraulics. In second step, specific emission optimisation was done on engine dynamometer using Ricardo CYSIM 9 Key point software. CYSIM software simulates chassis dynamometer cycle into a steady state points. Additional features like Cold Advance Solenoid (CAS), Progressive Light Load Advance (PLLA) were added in fuel injection pump during this stage. Different Exhaust Gas Recirculation (EGR) flow rates were tried to reduce NOx emissions. EGR flow rate was measured by SPINDT correlation method. In third stage, specific emission optimisation was done on chassis dynamometer for 8-seater multi utility passenger vehicle. By optimising CAS activation duration, EGR setting point and its duration, final emission targets were achieved.
The engine was successfully upgraded to meet Bharat Stage-II norms with minimum cost penalty. Simultaneously improvements in power and fuel consumption were also achieved.