Strategies to achieve controlled auto-ignition (CAI) combustion: A review

Conventional gasoline engines suffer from low performance and NOx emissions. Controlled auto-ignition (CAI), sometimes referred to as homogeneous charge compression ignition (HCCI), is a promising concept solve such problems. CAI has the potential improve spark (SI) engine fuel economy while at same time solving trade-off of NOx-soot emissions found in (CI) engines. The can reach comparable that conventional diesel with ultra-low negligible soot However, controlling remains biggest difficulty hinders implementation commercial engine. Research towards cleaner more efficient driven by progressively stringent emission regulation imposed worldwide. Therefore, was developed meet target maintaining performance. works on principle lean mixture auto-ignition. To obtain combustion, temperatures cylinder must be sufficient initiate Without use plug or injector, suffers direct control mechanism start combustion. most practical approach initiation diluting intake either trapping residual gas recirculating exhaust gas. Both approaches enable achieve combustion without requiring significant modifications onset phase.