U.S. researchers have gotten closer to biomass sourced DMF. DMF is the anagram for 2.5-Dymethylfuran. The U.S results while novel are thought efficient triggering questions about DMF combustion and the effluent effects on the environment. Little is known in the engine community about DMF’s combustion and emission characteristics, especially about the specific chemical emissions from combustion in engines.
The Brits and the Chinese have been collaborating in an investigation of the outstanding issues of DMF as base fuel with studies through developing and validating the spray, combustion, emissions and engine models and by conducting systematic experiments.
The results directly benefit the UK and Chinese motor industries and academia. The project’s outcome should help to increase the market size of British and China’s biofuel industries and will thus have impact on the development of the UK’s and China’s economy by increasing the opportunities for employment and profitability of agriculture and obviously will contribute to the reduction of carbon footprint of fuels for transportation.
DMF can be a substitute for petroleum-based gasoline, because DMF and gasoline share very similar physicochemical properties. University of Birmingham researchers have experimented on a single-cylinder gasoline direct-injection research engine to study the performance of DMF benchmarked against gasoline and what is considered to be the current biofuel leader, ethanol. Initial results are very promising for DMF as a new biofuel; not only is the combustion performance similar to commercial gasoline, but the regulated emissions are also comparable.
The Birmingham researchers claim that theirs is the first investigation on the use of DMF as a biofuel in a direct injection spark-ignition engine. The test fuels were 95 research octane number (RON) gasoline, bioethanol (both supplied by Shell Global Solutions UK), and DMF (99.8% purity from Shijiazhuang Lida Chemical Co., Ltd., China).
The results are significant:
The fuel consumption is very similar to gasoline, which is largely due to the similar gravimetric calorific values and relatively high density and the indicated thermal efficiency of DMF is similar to gasoline.
However, the initial combustion duration of DMF is shorter than that of gasoline. In addition at a constant ignition timing of 34° BTDC induced severe engine knock for DMF at 7.1 bar and gasoline at 6.5 bar while ethanol showed no signs of knock, and ethanol’s load could be extended safely to 8.5 bar. The onset of knock for DMF at loads similar to gasoline was somewhat unexpected, the authors say, and this finding justifies a further study into the real octane number for DMF, which is given in early studies as higher than that of ethanol. DMF isn’t going to be the high octane presupposed or compete with ethanol for high compression high efficiency applications.
DMF’s emissions across the range from carbon monoxide on to nitrous oxide are similar to gasoline. Both DMS and gasoline emit relatively higher emissions compared to ethanol in the test engine. Ethanol’s elements ratio (see chart) offer high hydrogen and oxygen content compared to carbon. Plus ethanol evaporates quickly and absorbs some combustion chamber heat that cools the in cylinder temperatures.
The study concludes to no surprise, that “DMF may be suitable to use as an existing gasoline-type engine fuel and that no major modifications and adjustments would be needed to produce an equivalent engine performance and emissions level.”
Research will continue with modeling and optical studies of the injection spray behavior and chemical kinetics of the oxidation reactions of DMF and will explore in more detail the in-cylinder combustion initiation and development. Additionally, a critical issue for biofuels and automotive fuels in general is the presence of any toxic components in the combustion emissions. Therefore, further tests determining the chemistry of emissions for DMF are already underway.
One doesn’t expect any nasty chemicals in the exhaust, but best to check. Meanwhile . . .
The ethanol industry has a fight on trying to get to 15% of the U.S. gasoline market with most everyone making claims in the vein of ‘Oh No!’ mostly due to the oxygen content ethanol brings along. This writer hasn’t posted much about DMF as it too is going add oxygen to the fuel side of combustion – something that will drive everyone with oxidize-able fuel handling equipment a little crazy in moving up the component quality ladder to resist corrosion.
For vehicles with an E-85 rating DMF will be a wonderful fuel, contributing to recycling carbon, hydrogen and oxygen making the thoughtful environmentalist quite happy.
But the griping and moaning would just reach further as much of the gasoline powered engine fleet is going to need a little shop time for upgrades.
The jury is still very much out on the production of DMF for now, but it’s looking more and more as a viable fuel that is fully biomass sourced.
More on this at GreenCarCongress, but no press release from the University of Birmingham.