Homogeneous charge compression ignition (HCCI) combustion of polyoxymethylene dimethyl ethers (PODE).

Polyoxymethylene dimethyl ethers (PODE) are a promising alternative fuel for diesel engines. PODE have high volatility, high ignitability and high oxygen content, and is thus also an ideal additive fuel for blend and dual-fuel combustion due to its low-temperature chemistry. In this work, the characteristics of PODE homogenous charge compression ignition (HCCI) combustion are investigated for the first time. The effects of charge mass equivalence ratio ( Φ m ) and exhaust gas recirculation (EGR) on PODE HCCI are studied. The results indicate that PODE HCCI exhibits two-stage ignition with a strong low temperature heat release (LTHR) before the high temperature heat release (HTHR). HTHR switches from one-stage to two-stage with an increase of Φ m due to rapid CO oxidation. At a specific EGR rate, with an increase of Φ m , the end-of-compression charge temperature decreases, the ignition timing of LTHR delays. With an increase of Φ m , the ignition timing of the HTHR advances at the EGR lower than 42%, but it delays at the EGR of 52% in general. For a specific Φ m , with an increase of EGR, the end-of-compression charge temperature decreases, the ignition timing of both LTHR and HTHR delays, and the combustion duration of the HTHR increases. CO emissions decrease with an increase of Φ m and a decrease of EGR. Φ m and EGR have only a slight effect on HC emissions. This work also provides fundamental data of PODE combustion characteristics for the future development of PODE reaction mechanisms. [ABSTRACT FROM AUTHOR]