Gas engines for cars are generally based on spark-ignition engines. Contrastingly, for large and stationary engines, an injection and combustion process similar to that found in diesel engines is more suitable and also enables a degree of efficiency of almost 50%. However, a high-pressure gas injection system is complex: despite multiple research projects over the last few years, there is still a lack of basic understanding of the injection, ignition and combustion process. Among other things, researchers from the Universität der Bundeswehr in Munich have developed flow simulation tools which were then validated in the Aerothermochemistry and Combustion Systems Laboratory at ETH Zurich. The researchers experimented with various injection pressures and durations in order to predict how a high-pressure injection procedure could be realised for gas engines.
» FVV’s research is helping us realise the full potential of gas engines when it comes to minimising greenhouse gases. «
Bringing a high-pressure gas injection system for gas engines to commercial maturity is no simple task
A clever combination: direct injection of diesel and methane
Heated constant volume chamber with side-mounted injector
Large and stationary engines powered with gas have the potential to emit around one third less CO2 than a diesel engine with a comparable output. However, this can only be achieved with an injection and combustion process similar to the one used in a diesel engine, during which gas is injected directly into the combustion chamber at high pressure. In contrast to the external carburation process, the benefit of this approach is that almost no unburnt methane is generated, a gas which is extremely harmful as a greenhouse gas.
» This project enabled us to deepen the scientific understanding of what exactly happens in the combustion chambers of large gas engines with a high-pressure gas injection system. «
A heated constant volume chamber at the Institute of Energy Technology at ETH Zurich enables the simulation of conditions similar to those in an engine. Here, researchers experimented with various injection pressures and compression ratios. They observed the propagation of gas in the combustion chamber via an optical access port and using various measurement procedures. Furthermore, the methane concentration in the gas jet was quantitatively recorded. At the Universität der Bundeswehr in Munich, comprehensive simulations on the processes in the area close to the jet in the combustion chamber had been performed in advance.
The simulations showed that, under certain conditions, methane condensates to a liquid. In realistic conditions, the researchers in Zurich were, however, able to prove that no condensation is to be expected in engine applications. In addition, ignition modelling showed that an additional ignition source is required, as the spark from a spark plug does not last long enough due to the very high gas velocities. The simulation results gained from the research project will also help improve the design of the complex injectors in the future in order to optimise gas injection and ignition.
2016-05-31 to 2019-09-29
Dr.-Ing. Michael Willmann
ABB Schweiz AG
(former Woodward L'Orange GmbH)
1 | Energy Science Center (IET), Aerothermochemistry and Combustion Systems Laboratory (LAV) - ETH Zurich
Head of research:
Prof. Dr. Konstantinos Boulouchos
2 | Institut für Thermodynamik (LRT-10) | Universität der Bundeswehr München
Head of research:
Univ.-Prof. Dr. rer. nat. Michael Pfitzner
Research & Technology Performers
Research Association for Combustion Engines eV
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