“…Operation in HCCI offers substantial improvements in fuel economy over traditional spark ignition (SI) combustion, as well as the potential for ultra-low NOx emissions [1]. Several methods exist for enabling HCCI operation, such as intake air heating [2,3], exhaust gas recirculation (EGR) [4,5], or variable compression ratio [6]. This paper focuses on the EGR method, in which hot exhaust gases are mixed with the fresh charge to manipulate the charge's thermodynamic state, so that when compressed, the mixture auto-ignites with desirable combustion phasing.…”