CNGDiesel – Development of natural gas diesel Dual-fuel combustion engine in order to reduce CO² reduction for passenger car propulsion

The tenor of the project is the development of a CO²-optimal gas-diesel dual-fuel combustion process based on a passenger car diesel engine taking into account the global emissions legislation. Thereby, the aim was to realise CO² savings of up to 25% w without worsening the characteristics regarding emissions and acoustics.

Short Description

Starting point / motivation

The automotive industry is meeting great intermediate challenges regarding the fulfillment of the legal emissions-requirements. It is rather probable that the actual emission-limit for passenger cars of 95 g CO²-/km will be tightened to 75 g CO²-/km from 2020 on, thus requiring enormous efforts in the further development of existing drive units with liquid fuels.

Besides the electrification of the driving train also of more efficient combustion engins as well as the use of alternative fuels have to be developed to achieve these requirements. A key alternative fuel is natural gas. Despite the limited availability of natural gas vehicles in the national fleet, it should be noted that with hardly any other individual measure, such real CO2 emissions in short term can be achieved from an economical and technical point of view, apart from standardized driving cycles.

In addition to the electrification with hybrid systems and all-electric vehicles, the use of natural gas offers a very attractive, short-term viable alternative to significantly reduce CO² emissions due to the lower C/H ratio.

Contents and goals

In this research project, the dual-fuel operation with natural gas and diesel was tested on a diesel engine. The aim of the presented concept is to combine the high efficiency of the diesel engine with the CO² savings potential of natural gas.


The basis for the experimental tests was a 4-cylinder series diesel engine from BMW. By means of extensive adaptations, this engine was used to display the dual-fuel operation with diesel and gaseous natural gas (CNG-Compressed Natural Gas).

As it is the case with the standard engines the diesel was injected directly into the combustion chamber, and was used as a "trigger" for combustion. For the introduction of the natural gas, both the outer and the inner carbureation formation were examined. In addition to the experimental investigations, various simulation tools were applied.

Results and Conclusion

The analyses of study showed that, apart from large engine and commercial vehicle applications, the natural gas diesel combustion process also delivers promising results in the passenger car sector. The obtained knowledge enables further investigations of natural gas-diesel combustion processes in mobility-applications. An essential key question, however, is the exhaust gas after treatment, especially with regard to methane emissions in the partial load.


Project Partners

  • Univ.-Prof. DI Dr. Helmut Eichlseder, TU Graz – Institute of Internal Combustion Engines and Thermodynamics
  • DI Peter Raschl, BMW Motoren GmbH
  • Ao.Univ.-Prof. Dr. Peter Sturm, Research Institute for Combustion Engines and Thermodynamics mbH

Contact Address

TU Graz – Institute of Internal Combustion Engines and Thermodynamics
Univ.-Prof. DI Dr. Helmut Eichlseder
Tel.: +43 (316) 873-30001