A team at Chalmers University (Sweden) has tested blends of OME_3-5, HVO and RME in a light- and heavy-duty CI engine. For the study, which is published in an open-access paper in the journal Fuel, OME_3-5 was blended with hydrotreated vegetable oil (HVO), rapeseed methyl ester (RME) and the C₈-alcohol 2-ethylhexanol (an isomer of n-octanol) to ensure miscibility.

Three blends were designed with an oxygen content of 6.4, 12.8 and 17.8% by mass. Performance and emissions were compared to the reference fuels fossil diesel and HVO in a single-cylinder light duty and heavy duty compression ignition engine at different loads.

Preuß et al.

Interest in poly(oxymethylene)dimethyl ether (OME_3-5) as an alternative to fossil fuels in compression ignition engines has increased owing to its potential for soot reduction. The high oxygen content of the polymer and lack of carbon–carbon bonds and aromatic structures can help to reduce engine out soot emissions. However, OME_3-5 is potentially damaging to engine components, and thus engine modifications are required when using neat OME_3-5.

—Preuß et al.

The team found that the indicated thermal efficiency was slightly higher for the oxygenated fuel and the combustion duration shorter compared to diesel. Due to the lower heating value of the blends, the indicated specific fuel combustion increased with increasing share of OME_3-5 in the blend.

For both engines, engine-out soot emissions were decreased strongly, whereas NO_x emissions were slightly increased. Analysis of the particle size distribution showed a decrease in the particle number of agglomerated particles (>30 nm) for the blends. For the heavy duty engine, an increase in nucleation mode particles (<30 nm) was measured.

Resources

• Josefine Preuß, Karin Munch, Ingemar Denbratt (2021) “Performance and emissions of renewable blends with OME3-5 and HVO in heavy duty and light duty compression ignition engines,” Fuel, Volume 303 doi: 10.1016/j.fuel.2021.121275