Insights into combustion and performance of HCCI engine fed with PODE₁and H₂-rich PODE₁-reformate

A transition to sustainable energy sources, carbon- free/neutral energy carriers and efficient combustion technologies is intensively discussed as a key pathway in achieving a greener, more secure energy future. In particular, enhancement of internal combustion engine (ICE) performance using promising alternative carbon- neutral propellants, waste heat recovery (WHR) and state-of-the-art combustion methods has gained high research attention. Polyoxymethylene dimethyl ethers (PODEn, OMEn), well-suited for compression-ignition (CI) combustion, arouse strong interest as potentially sustainable and cleaner alternatives to diesel fuel. This study reports for the first-time numerically examined combustion performance characteristics of reforming- controlled compression ignition (RefCCI) ICE engine, managed by mixing of polyoxymethylene dimethyl ether 1 (PODE1) and its hydrogen-rich reforming products (PODE1-reformate) obtained through thermo- chemical recuperation. The results showed that the RefCCI combustion-control is possible by maintaining an appropriate H2/PODE1 ratio in the process of in- cylinder mixing of PODE1 and PODE1-reformate prior to auto-ignition. Beneficial high engine efficiencies of 40.6-48.4% and reduced NOx and CO emissions were achieved at the examined compression ratio of 16.