Combustion control strategies to achieve low temperature combustion in PCCI engines - A comprehensive review

Low-temperature combustion (LTC) has emerged as a pivotal solution for modern compression ignition engines, effectively breaking the traditional nitrogen oxide (NOx) and soot emission trade-off. Among LTC variants, Premixed Charge Compression Ignition (PCCI) stands out for its capacity to reduce in-cylinder emissions with minimal structural modifications. This review evaluates alternative fuel integration within PCCI regimes by shifting from isolated, single-variable engine tuning to a unified multi-parameter coupling framework. Utilizing a data-driven methodology evaluating findings from over 225 recent experimental and computational studies, this paper synthesizes the simultaneous, interdependent interactions between injection pressure (IP), split injection timing (IT), compression ratio (CR), and exhaust gas recirculation (EGR). Quantitative assessments demonstrate that alcohol blends achieve a 40–60% reduction in NOx and a 70–90% reduction in soot due to their high latent heat of vaporization, while ether additives elevate brake thermal efficiency (BTE) by 2–5% at light loads but accelerate peak pressure rise rates (PRR) by 25–40%. For zero-carbon applications, pure ammonia (NH 3 ) systems require strategic hydrogen (H 2 ) blending to support auto-ignition species kinetics. Finally, this review highlights the engineering challenges of managing steady-state combustion regimes under dynamic driving cycles, bridging laboratory discoveries with practical transient powertrain controller strategies for hybrid electric vehicles (HEVs).