Oxygenated fuel can effectively reduce soot emission and Tri-Propylene Glycol Monomethyl Ether (TPGME) is a promising oxygenated fuel for diesel engines. However, a suitable chemical kinetic model for TPGME is not available that covers both low to high temperature chemistry regimes to simulate the combustion process and for soot prediction in multi-dimensional computational fluid dynamics (CFD) calculations.
In this work, a comprehensive reduced chemical reaction mechanism was developed for modeling the combustion process and soot emissions for an oxygenated hydrocarbon. Using a combination of the Directed Relation Graph with Error Propagation (DRGEP) method, flux analysis, isomer lumping, and limited reaction rate adjustment for the sensitive reactions, a detailed TPGME mechanism was reduced and combined with a reduced n-hexadecane mechanism to investigate the effects of oxygenated fuel on the combustion process and soot emissions. A reduced poly-aromatic hydrocarbon (PAH) mechanism was also embedded into the reduced TPGME and n-hexadecane mechanisms to describe the soot formation in terms of PAH up to four rings (pyrene). The final mechanism consists of 143 species and 730 reactions, which makes it an appropriate size for multi-dimensional CFD simulations. The mechanism was validated with experiments in shock tubes, and in constant volume combustion chambers.
The results show that simulations with the combined mechanism give reliable predictions of combustion characteristics and general soot formation under diesel-like fuel jet conditions in the constant volume combustion chamber.