Numerical assessment of polyoxymethylene dimethyl ether (OME₃) injection timing in compression ignition engine

This research encompasses the numerical analysis of trioxymethylene dimethyl ether (OME₃) e-fuel on an industrial compression ignition engine, as a viable replacement for diesel fuel. The performed simulations examined single injection and multi-injection operating conditions of OME₃, varying injection rates and timing. The combustion process is modeled employing two approaches: three-dimensional extended coherent flame model (ECFM-3Z) and general gas phase reactions (GGPR) with a reduced chemical kinetic mechanism. ECFM-3Z gives a faster convergence, where pretabulated autoignition and laminar flame speed databases are integrated into the model to decrease computational time. The GGPR approach is validated on the experimental values for mean pressure, temperature, and rate of released heat in the same engine with diesel fuel and then again employed on an OME₃. Both approaches confirmed that a higher amount of OME₃ and a prolonged injection time is needed to achieve the same released heat per cycle as diesel fuel since OME₃ has a lower net calorific value. It is established that combusting OME₃, a 15% higher mean pressure peak can be achieved in multi-injection case compared to the diesel fuel, by adapting the injection timing. Additionally, nitrogen oxides emissions for OME₃ are also compared to the diesel case for both combustion modeling approaches. Under the context of multi-injection, the OME₃ fuel results show equivalent or lesser nitrogen oxides emissions than those of diesel fuel. The outcomes yielded by the GGPR model utilizing the Lin mechanism revealed decreased temperatures, leading to correspondingly diminished concentrations of nitrogen oxide emissions in comparison with the ECFM-3Z model.