Homogeneous Charge Compression Ignition (HCCI) Engines

1. Homogeneous Charge Compression Ignition (HCCI) Engines Gajendra Singh

2. Contents • Need of HCCI • HCCI Engine Concept • Advantage & Challenges related to HCCI • Future Aspects.

3. Urban Pollution The Challenges Facing Us… • Emission (NOx & Soot) • Fuel Economy Fuel Consumption is increased by more than 10 % in last 7 years

4. Solution • Hybrid Vehicles • Fuel Cells • HCCI Engines • GDI Engine • Low Emissions Technologies • New Materials • Advanced Design Simulations • Efficient Electronics and Electrical Devices

5. What is an HCCI Engine? • HCCI is a form of internal combustion in which the Homogeneous Charge is compressed to the point of auto ignition. • HCCI incorporates the best features of both spark ignition (SI) and compression ignition (CI) • As in an SI engine, the charge is well mixed, which minimizes particulate emissions. • As in a CI engine, the charge is compression ignited and has no throttling losses, which leads to high efficiency.

6. Traditional combustion (left) uses a spark to ignite the mixture. HCCI (right) uses piston compression for a more complete ignition. SI Engine HCCI • Unlike conventional engines, the combustion occurs simultaneously throughout the volume rather than in a flame front. • This important attribute of HCCI allows combustion to occur at much lower temperatures, dramatically reducing engine-out emissions of NOx

7. Working

9. Advantage • Relative to SI gasoline engines, HCCI engines are more efficient, approaching the efficiency of a CIDI engine. Reason for Improved Efficiency • Elimination of throttling losses. • High compression ratios • Shorter combustion duration (No Flame front, so distance to travel) • Fuel-Flexibility

10. Emission • HCCI engines also have lower engine-out NOx. • HCCI engines have substantially lower emissions of PM. The low emissions of PM and NOx in HCCI engines are a result of the dilute homogeneous air and fuel mixture. The charge in an HCCI engine may be made dilute by being very lean by EGR. • HCCI engines may be lower cost since use lower-pressure fuel-injection equipment.

11. Challenges • Controlling Ignition Timing over a Range of Speeds and Load . • varying the amount of hot EGR. • using a VCR mechanism. • using a VVT mechanism. • Extending the Operating Range to High Load • Dual Mode Operation • Cold-Start Capability • Using glow plugs. • Start the engine in spark-ignition mode. • Hydrocarbon and Carbon Monoxide Emission • Using Oxidation Catalysts.

12. Research Aspects • Ignition Timing Control • Engine Cold-Start • Heat release rate • Multi-Cylinder Engine Effects • Fuel System • Engine Control Strategies and Systems • Engine Transient Operation Prototype HCCI car from Saturn

13. pHCCI (Partial Homogeneous Charge Compression Ignition ) • In Partial HCCI mode the engine is cold-started as an SI or CI engine, then switched to HCCI mode for idle and low- to mid-load operation to obtain the benefits of HCCI in this regime. For high-load operation, the engine would again be switched to SI or CI operation.

14. The Future of HCCI • The future of HCCI looks promising specially with partial HCCI mode. • Major companies such as GM, Mercedes-Benz, Honda, and Volkswagen have invested in HCCI research.

15. Conclusion • HCCI is a combustion concept which is developed in response to the need of lower NOx & soot emission and Efficiency. • It can substantially overcome both the problems but still it needs a lot of development.

16. Thanks