Experimental study of syngas combustion at engine-like conditions in a rapid compression machine

As the world energy demand and environmental concern continue to grow, syngas is expected to play an important role in future energy production. It represents a viable energy source, particularly for stationary power generation, since it allows for a wide flexibility in fossil fuel sources, and since most of the harmful contaminants and pollutants can be removed in the post-gasification process prior to combustion. In this work, two typical mixtures of H2, CO, CH4, CO2 and N2 have been considered as representative of the producer gas coming from wood gasification, and its turbulent combustion at engine-like conditions is made in a rapid compression machine in order to improve current knowledge and provide reference data for modeling and simulation of internal combustion engines. Methane as main constituent of the natural gas is used as reference fuel for comparison reasons. Single compression and compression- expansion events were performed as well direct light visualizations from chemiluminescence emission. There is an opposite behavior of the in-cylinder pressure between single compression and compression–expansion strokes. For single compression, peak pressure decreases as the ignition delay increases. In opposite, for compression–expansion the peak pressure increases as the ignition delay increases. This opposite behavior has to do with the combustion duration under constant volume conditions. Conclusion can be drawn that higher pressures are obtained with methane–air mixture in comparison to both typical syngas compositions. These results could be endorsed to the heat of reaction of the fuels, air to fuel ratio and burning velocity. Another major finding is that syngas typical compositions are characterized by high ignition timings due to its low burning velocities. This could compromise the use of typical syngas compositions on high rotation speed engines.

► In-cylinder pressure has an opposite behavior between single compression and compression-expansion strokes.
► Lower pressures are obtained with typical syngas compositions by comparison with methane.
► Syngas typical compositions are characterized by high ignition timings.
► Syngas typical compositions have dissimilar behavior in laminar conditions versus turbulent conditions.