Homogeneous Charge Compression Ignition


We are exploring an innovative engine concept—Homogeneous Charge Compression Ignition (HCCI)—that promises to operate at high efficiency (greater than 40%) with low NOx and particulate-matter emissions. In an HCCI engine, the fuel is premixed with air, as in a spark-ignited engine, but in a very “lean” mixture that has a high proportion of air to fuel. When the piston reaches its highest point, the fuel autoignites from compression, as in a diesel engine.

We have developed the capability to do very accurate analysis of HCCI combustion. We can predict all combustion parameters with good accuracy, and can also generate predictions for HCCI engine emissions. We also have an ongoing experimental effort at the University of California Berkeley to explore the operating range and the efficiency of the engine.


HCCI combustion
Temperature distribution before combustion in the combustion chamber of a Volkswagen TDI engine that has been converted to Homogeneous Charge Compression Ignition, at top dead center with the piston all the way up. For HCCI engines, temperature distribution in the cylinder is important in determining the burn duration and the emissions of hydrocarbons and carbon monoxide.


For more information, contact Dan Flowers at:

Lawrence Livermore National Laboratory
P.O. Box 808, L-644
Livermore, CA 94551

Phone: (925) 422-0529
Fax: (925) 423-7914
flowers4@llnl.gov

Link to UC Berkeley's HCCI web site

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This page was prepared by: Michael Loomis, loomis3@llnl.gov and Helen Magann, magann2@llnl.gov
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