Numerical Transition from Diesel to Hydrogen in Compression Ignition Engines: Kinetics, Emissions, and Optimization with Exhaust Gas Recirculation

A Cantera-based combustion-kinetics framework that maps the operating space of hydrogen compression ignition (H2-CI) engines and establishes a structured charter to guide experiments. Beginning with a diesel (n-dodecane) baseline at an intake temperature of 300 K, the model is virtually converted to neat hydrogen and evaluated across intake temperatures of 400–600 K, compression ratios (CR) of 20–28, and exhaust gas recirculation (EGR) levels of 0–15%. Hydrogen demonstrates stable operation across a broad equivalence ratio window (ϕ = 0.45–2.1), achieving power outputs of 16–22 kW and higher efficiencies with substantially lower fuel mass than diesel. The optimal operating region is identified at an approximately 400 K intake temperature, CR = 24–28, and EGR between 5% and 10%, where power remains high (20–18 kW), efficiency increases (above 50%), and NOx emissions are markedly reduced (from 332 ppm at zero EGR to 48 ppm at 5% EGR and 10 ppm at 10% EGR), with only modest hydrogen slip (0.07–0.11). The kinetics-based framework thus provides a systematic and validated roadmap for experimental calibration, research, and development of compression ignition engines working on pure hydrogen.