Towards low-carbon mobility through 0D phenomenological modelling of oxy-fuel combustion in internal combustion engines

Oxy-fuel combustion in internal combustion engines is gaining attention as a promising technology for carbon capture and achieving near-zero nitrogen oxides emissions, addressing global warming concerns. Recent experimental and simulation studies evaluated this unconventional combustion mode in internal combustion engines under various dilution strategies, but current models are not yet appropriately customized to describe in-cylinder processes with highly enriched oxygen atmospheres. This study aims to validate a Zero-Dimensional engine model, consisting of a predictive combustion model, a dedicated laminar flame speed correlation, and emission sub-models, embedded in a One-Dimensional simulation code, and to assess its capability to describe the behaviour of a gasoline-fuelled single-cylinder engine under premixed oxy-fuel combustion conditions. The experimental campaign tested the engine at medium load (from 8.3 bar to 10.1 bar of Indicated Mean Effective Pressure) and a rotational speed of 3000 rpm, varying the oxygen/fuel proportions (relative oxygen/fuel ratio from 1.0 to 1.2), exhaust gas recirculation ratios (from 66 to 75 %), and intake temperatures (70 °C and to 80 °C), and the data are used for the model calibration and validation, defining a single set of tuning constants. The combustion model replicated in-cylinder pressures and burn rates, resulting in an average error of 1.3 crank angle degrees for the combustion phasing, while the emission model replicated exhaust pollutant concentrations, with average errors with respect to experiments of 23.6 % and 13.6 % for carbon monoxide and unburned hydrocarbon, respectively. The predictive capability of the model discloses the potential applicability in the context of engine and system calibration and optimization.