Numerical Transition from Diesel to Hydrogen in CI Engines: Kinetics, Emissions, and Optimization with EGR

A Cantera-based combustion-kinetics framework that maps the operating space of hydro-gen compression-ignition (H₂-CI) engines and establishes a structured charter to guide experiments. Beginning from a diesel (n-dodecane) baseline at an intake temperature of 300 K, the model is virtually converted to neat hydrogen and evaluated across intake tem-peratures 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 equiva-lence ratio window (ϕ = 0.45–2.1), achieving power outputs of 16–22 kW and higher effi-ciencies with substantially lower fuel mass than diesel. The optimal operating region is identified at approximately 400 K intake temperature, CR = 28, and EGR between 5% and 10%, where power remains high (20–18 kW), efficiency increases (56–57%), 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 frame-work thus provides a systematic and validated roadmap for experimental calibration, re-placing empirical trial-and-error with numerically defined performance and emissions targets.