Homogeneous Charge Compression Ignition (HCCI) Engines Gajendra Singh

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

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

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

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.

Traditional combustion (left) uses a spark to ignite the mixture. HCCI (right) uses piston compression for a more complete ignition. 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 SI EngineHCCI

Working

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

 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.

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.

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

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.

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. Company Technology Estimated Year of Commercialization General Motors Saturn-AurapHCCITest Vehicle is on the Road. Opel-VectrapHCCI2015 MercedesDies-ottoPHCCITest Vehicle is on the Road. VolkswagenTouranCCS(Combined Combustion Spark)2015 GCI(Gasoline Compression Ignition) FordpHCCI2015

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.

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