Researchers at Annamalai University of Tamil Nadu, India have worked out how to blend ethanol and dimethyl ether, both renewable chemicals, with diesel to produce a significantly improved fuel.  M. P. Ashok of Annamalai University reports the American Chemical Society’s journal Energy & Fuels that adding dimethyl ether (DME) to an ethanol/diesel emulsion results in an increase in brake thermal efficiency and a decrease in specific fuel consumption (SFC), particulate matter, smoke density, and oxides of nitrogen compared to either the emulsion or a base diesel fuel.

Diesel Ethanol DME Mix Brake Power. Click image for the largest view.

The study of the fuel mixture offers impressive results.  On the basis of the best performance and lowest emissions a 50% diesel and 50% ethanol at 100% proof was been selected as the best emulsified fuel ratio for comparison to the other emulsified fuel ratios.  In the study’s second phase oxygen-enriched additive dimethyl ether was added to the selected best ratio of 50% Diesel / 50% Ethanol (50D/50E) emulsified fuel.

Ashok conducted performance and emission tests for diesel, 50D/50E emulsified fuel ratio, and oxygen-enriched additive-added emulsified fuel. It was found that the oxygen-enriched additive-added emulsified fuel has the best performance and lower emissions when compared to the other fuel mix ratios.

Emulsification of diesel with ethanol is one of the possible approaches to improve fuel economy and reduce emissions of pollutants from diesel engines.  Ashok notes ethanol added to diesel results in different physicochemical changes in diesel fuel properties, particularly a reduction in cetane number, viscosity, and heating value.

Ashok started the project by first examining the performance of different diesel and ethanol blends: 90D/10E, 80D/20E, 70D/30E, 60D/40E, and 50D/50E, all prepared on the basis of the water-in-oil (W/O)-type emulsion method.  Ashok found the 50D/50E ratio as the best of the emulsified blends due to its increase in brake thermal efficiency and decrease in specific fuel consumption, smoke density (SD) and particulate matter (PM).  But nitrous oxide went up.

Diesel Ethanol DME Combined Performance Graph. Click image for the largest view.

Ashok says in the study, “Even though this emulsified fuel gives better brake thermal efficiency and gives less SFC, SD, and PM based on the performance and emissions, respectively, in comparison to diesel no. 2, there is a significant increase in NOx emission over diesel no. 2. This is due to the lower cetane number of ethanol, which causes high temperatures, resulting in a longer ignition delay. . .   This emission of NOx can be controlled by adding a suitable additive, which must have the property of a high cetane number. This leads to a reduction of the temperature, resulting in a smaller ignition delay, thus reducing emission of NOx.”

Ashok added DME on a 7% by volume basis with the selected emulsified fuel ratio of 50D/50E and then carried out performance, emission, and combustion tests, along with performance and emission tests with diesel no. 2 and emulsified fuel 50D/50E for reporting the study results.

For the record the testing was done in a one-cylinder, four-stroke 5.2 kW engine with a compression ratio of 17.5:1. Speed was constant 1500 rpm, injection timing was 23° before TDC, and injection pressure was 220 kgf/cm2 (215 bar).

The highlights of the results are:

  • Brake thermal efficiency increases from 35.6% (emulsified fuel) to 38.1% (DME-added emulsified fuel).
  • The best decrease in the Smoke Density value was obtained for DME-added emulsified fuel compared to the other two fuels. The value for DME-added emulsified fuel and the
  • emulsified fuels are 9.8 and 14.9 HSU, respectively.
  • Particulate Matter emission is low at lower outputs and equal to the emulsified fuel values at higher outputs for DME-added emulsified fuel.
  • The NOx (nitrous oxide) value is reduced because of the additive DME; it is usually higher for the emulsified fuel using the normal surfactant. NOx was reduced from 3.68 to 2.856 g/kWh for 50D/50E emulsified fuel and DME-added emulsified fuel, respectively.
  • Ignition delay is decreased for DME-added emulsified fuel compared to the other two fuels. At lower output, the difference in value is 4.9° of crankshaft angle.
  • The peak pressure and the maximum rate of pressure rise decrease because of the reduction in ignition delay.
  • The heat release rate is higher for the emulsified fuel than the diesel and additive DME-added emulsified fuels. The maximum value obtained by the emulsified fuel is 106.591 kJ m-3 deg-1, and the minimum value attained by the additive DME-added emulsified fuel is 53.81 kJ m-3 deg-1.

The sum of the results is impressive.

On the other hand, the combination of ethanol and water with their corrosive properties is quite different from a pure diesel fuel, and it’s going to horrify some diesel engine fuel system engineers.  Yet the fuel savings are impressive and well worth further research.  From what we saw last week with a combined diesel with gasoline diesel fuel delivery system the total fossil fuel use isn’t reduced so dramatically.  Ashok has given the world a very new path with great potential to extend the diesel fuel supply.  How it works out will be intensely interesting.


3 Comments so far

  1. MattMusson on August 5, 2011 7:22 AM

    Clearly the result of mixing water and ethanol with diesel is a less energy dense product. However, with more oxygen it burns more efficiently and cleaner.

    In simple terms you are just adding oxygen which makes me wonder if diesel fuel could not somehow be whipped and emulsified so that it includes more oxygen without having to add the water and alcohol.

  2. diesel fuel - OIL WORLD 2011 – OIL WORLD 2011 on August 12, 2011 5:13 PM

    […] A Diesel Fuel Extender That's a Better Fuel | New Energy and Fuel From India comes an impressive fuel mixture that could substitute for pure diesel with renewable fuels for over half the volume with better performance. .. […]

  3. SRINIVASAN GOPALAKRISHNAN on August 16, 2011 10:10 PM

    The cost is an important factor.Sufficient volume of Ethanol is first of all not available for the quantum of diesel consumed all over the country.Again cost of ethanol and dimethyl ether is a factor to be considered.

    All these problems have already been overcome by an Indian Invention patented in India, u.k, canada, philippines and put into use in which upto 30-40% water in the diesel not only reduce NOx by 70%, soot by 80% but also save diesel by 30% and costs 25% lower than the conventional diesel.The power is also enhanced as the process makes the emulsified fuel a hydrogen carrier fuel.


    The Former President of India and Space,Missile Scientist-Dr.A.P.J.Abdul Kalam had visited to see the ONDEMAND EMULSIFICATION SYSTEM and had appreciated the Indian Innovation that emulsifies th diesel without the use of surfactants through MOLECULAR ENGINEERING OF WATER


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