Reactivity controlled compression ignition
Reactivity controlled compression ignition (RCCI) is a form of internal combustion developed at the Engine Research Center, University of Wisconsin–Madison, United States, by the research group of Wisconsin Distinguished Professor Rolf Reitz. During RCCI combustion, well-mixed low-reactivity fuel and oxidizer (typically air) are compressed but not reaching auto-ignition.
Source: Wikipedia — Reactivity controlled compression ignition (CC BY-SA 4.0)