Georg Baumgartner successfully defended his Ph.D. thesis with the project title “Flame Flashback in Premixed Hydrogen-Air Combustion Systems” on December 12, 2014, in Munich, Germany. He has experimentally investigated the flashback behavior of turbulent hydrogen-air flames using advanced optical measurement techniques. His studies involved various geometrical burner configurations and different operating conditions such that the decisive influential parameters on the flashback propensity could be identified. Based on the experimental findings he has also developed an improved theoretical model to describe the flashback process of unconfined flames.
This doctoral work has been performed at the Lehrstuhl für Thermodynamik of the Technical University of Munich (TUM), Germany, with Professor Thomas Sattelmayer as supervisor. The Evaluation Committee consisted of Prof. Julien Provost (TU Munich), Prof. Thomas Sattelmayer (TU Munich), and Prof. Jens Klingmann (University of Lund, Sweden). The research was funded by the BIGCCS Centre, performed under the Norwegian research program Centers for Environment-friendly Energy Research (FME). An abstract of the thesis can be found below the photo.
Abstract of the thesis
Sustainable power generation from the remaining fossil fuel resources on our planet is one of the key challenges to satisfy the world’s energy demand while simultaneously minimizing the negative impacts on the environment. Regarding the reduction of carbon dioxide (CO2) emissions, Carbon Capture and Storage (CCS) technologies are a promising concept. In the pre-combustion CO2 capture route, natural gas reforming or coal gasification processes are deployed to produce gases with very high hydrogen content, which can then be used as carbon-free energy sources in industrial applications, e.g. for firing a gas turbine. In the gas turbine industry, the development trend is toward lean premixed combustion in order to reduce nitrogen oxide (NOx) emissions. This implies that fuel and oxidizer are premixed before the mixture is burnt in the combustion chamber. Therefore, there is a risk for the flame to propagate upstream into the premixing section, which is referred to as flame flashback.
The potential occurrence of flame flashback is a critical safety hazard in premixed combustion systems as it can lead to combustion instabilities and hardware damage due to overheating of machine components, which in turn can even result in catastrophic failure of the whole machine. This applies in particular to highly reactive fuels, such as hydrogen, and to low-velocity flow regions, such as wall boundary layers.
In this work, flashback was investigated both on a macroscopic and on a microscopic scale for turbulent hydrogen-air flames using advanced optical measurement techniques. The flashback behavior was determined for various burner geometries and operating conditions, and the decisive influential parameters on flashback propensity were identified. In addition, an improved theoretical model describing the flashback process of unconfined flames was developed, which eliminates the shortcomings of the existing model.