Homogeneous Charge Compression Ignition (HCCI) Engines

Joseph Simon Clark

What is an HCCI Engine?

• HCCI is a form of internal combustion in which the fuel and air are compressed to the point of auto ignition.

• That means no spark is required to ignite the fuel/air mixture

• Creates the same amount of power as a traditional engine, but uses less fuel.

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

How Does It Work?

• A given concentration of fuel and air will spontaneously ignite when it reaches its auto-ignition temperature.

• The concentration/temperature can be controlled several ways:– High compression ratio– Preheating of induction gases– Forced induction– Retaining or reintroducing exhaust

gases

Click here for a nice animation of an HCCI engine in action!

Advantages

• Can achieve up to 15% fuel savings

• Lower peak temperature leads to cleaner combustion/lower emissions

• Can use gasoline, diesel, or most alternative fuels

HCCI automobiles could reduce greenhouse gas emissions

Disadvantages

• Higher cylinder peak pressures may damage the engine

• Auto-ignition is difficult to control

• HCCI Engines have a smaller power range

Prototype HCCI car from Saturn

The Future of HCCI

• The future of HCCI looks promising

• Major companies such as GM, Mercedes-Benz, Honda, and Volkswagen have invested in HCCI research.

• Preliminary prototype figures show that HCCI cars can achieve in the area of 43 mpg

Works Cited• “Homogeneous Charge Compression Ignition”

http://en.wikipedia.org/wiki/Homogeneous_Charge_Compression_Ignition November, 2008.

• “New HCCI Engine” http://videos.howstuffworks.com/multivu/3284-new-hcci-engine-video.htm November, 2008

• “GM Takes New Combustion Technology Out of the Lab and Onto the Road” http://www.gm.com/experience/fuel_economy/news/2007/adv_engines/new-combustion-technology-082707.jsp