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Polyoxymethylene dimethyl ether (POMDME) is a synthetic fuel from alternative energy sources, which can be blended in any ratio with petroleum diesel fuel. The regulated and non-regulated emissions, especially polyaromatic hydrocarbons (PAH) and particle number size distribution (PNSD), from an old Euro-3 diesel engine fueled with a 7,5% blend of POMDME in commercial diesel fuel were measured and compared to the base diesel fuel, after adjusting exhaust gas ratio (EGR) in order to match the level of NOx emission. The experimental results show a significant reduction in soot and particulate matter (PM) emissions. The number of particles smaller than 30 nm is slightly increased at low speed and low load operating conditions, while at high speed the number concentration of particles larger than 30 nm is reduced. The PAH emissions were found higher for the oxygenated fuel blend than for the base fuel.

Polyoxymethylene dimethyl ether (POMDME) is a new alternative fuel that can be produced from waste biomasses and tailored through the distribution of oligomers to fit into the distillation range of diesel fuel. Since one potential advantage of alternative fuels is that they could reduce emissions also from old in-use vehicles without waiting for their replacement, we have measured and evaluated the emission performance of neat POMDME and a blend of 10% POMDME and 90% commercial diesel fuel in an old Euro-2 diesel car over the NEDC driving cycle. As compared to the reference diesel fuel, the experimental results show a significant reduction in PM emissions already with the 10% blend, i.e., −18%, and even more pronounced with the neat POMDME, i.e., −77%. With this latter the PM emission reached below the Euro 4 limit. The composition of PM was quite different for the two extreme fuels; being mostly VOF from lube oil for the neat POMDME, while mostly soot in the case of diesel fuel.

The combustion behaviour, the mechanisms of soot formation, and the emission performance of a mixture of polyoxymethylene dimethyl ethers (POMDME) oligomers with a number of oxymethylene units ranging from 3 to 5, both neat and blended at 12.5% and 50% levels with commercial diesel fuel have been investigated. The goals were a first evaluation of the POMDME impact on the diesel injector behaviour, on the combustion process as well as on the emission performance of a light duty engine. Then a brief screening on the capability to improve the NOx-PM trade-off using POMDME by means of the exhaust gas recirculation (EGR) rate increment was also assessed.