A method and apparatus for operation of an internal combustion engine running
under
a homogeneous charge compression ignition (HCCI) mode with fuel partially reformed
by an onboard fuel reformer. In one embodiment, the onboard fuel reformer is a
plasmatron fuel converter. The temperature and composition of the gaseous charge
into the cylinders of the engine can be adjusted by mixing the charge into the
cylinder (which contains air, exhaust gas and/or unreformed fuel) with hydrogen
rich gas from the onboard reformer. The fuel reformer transforms the fuel to a
mixture of hydrogen, CO and other light hydrocarbons. By adjusting operation in
the reformer, the composition of the reformate can be altered. In addition to thermal
management of the cylinder charge, the reformate can be used as a fuel blending
agent in order to adjust the octane/cetane number of the air charge and thus control
the ignition timing of the overall fuel/air charge to the cylinder.