DMC+ as Particulate Free and Potentially Sustainable Fuel for DI SI Engines

Authors

Dr.-Ing. M. Härtl, A. Stadler MSc, S. Blochum MSc, D. Pélerin MSc, Dipl.-Phys. T. Maier MSc, Dipl.-Phys. V. Berger, Prof. Dr.-Ing. G. Wachtmeister, Technical University of Munich; Dr.-Ing. P. Seidenspinner, Dr. T. Wilharm, ASG Analytik Service GmbH, Neusäß; Dr. E. Jacob, Emissionskonzepte Motoren, Krailling

Year

2018

Print Info

Fortschritt-Berichte VDI, Series 12, No 807

Summary

C1 fuels can be sustainably produced from CO2 and H2 via a simple procedure; they are characterised by their high oxygen content and the absence of C-C bonds; and they lead to extremely low particulate emissions during combustion. In comparison to the use of hydrocarbon-based fuels, C1 oxygenates – with the exception of methanol – reduce the potential danger to human health and the environment. While in the case of diesel engines, the substance class of oxymethylene ethers (OME) has been studied over recent years as a low-emission option for sustainably-produced synthetic fuels, there are a lack of appropriate solutions for spark-ignition engines.
The reduction in the limit values for particle number (PN) with Euro 6c/d is advancing the search for such fuels for spark-ignition engines. The C1 oxygenates DMC and MeFo are characterised by a high octane number and favourable mixture-formation properties. They can be sustainably produced as e-fuels.
While the use of pure DMC or MeFo involves disadvantages with regard to low temperature stability and/or vaporisation properties, the presented work will demonstrate the route towards the application of these two oxygenates. The development of DMC+ (dimethyl carbonate + methyl formate + ethanol) on the basis of C1 chemistry opens up the opportunity for emission-free mobility using spark-ignition engines.
The methodology involved in defining a target-oriented formulation for DMC+ is presented, as well as the results from experiments using DMC+ in a DI SI single-cylinder engine. A decrease in PN emissions by two orders of magnitude, as well as a significant reduction in the emission of NOx and organic compounds (VOC) in the exhaust gases, is demonstrated. A three-way catalytic converter is used, enabling the lowest of pollutant emissions in stoichiometric operation. Special attention is given to the emission of sub-23 nm particles, which is also significantly reduced by the oxygenate fuel.