Combustion of ammonia under application-relevant conditions: a case study to improve thermal radiation models and reactivity prediction

• Applicant: Dr.-Ing. Joachim Beeckmann
• Subject Area: Technical Thermodynamics
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 469834263

The main objective of this project is two-fold: First, new experimental data of ammonia flames measured at high pressures and temperatures will be provided; second, a robust methodology to accurately measure laminar flame speeds using the optical and the pressure rise methods with special emphasis on radiation and buoyancy effects will be developed. To achieve this goal, laminar flame speeds of ammonia mixtures will be measured in two complementary experimental setups at conditions most relevant to applications, including high temperatures and pressures never explored before. Representative measurements in a spherical combustion vessel using optical imaging methods (Schlieren and Particle Image Velocimetry-PIV techniques) under normal gravity will be performed at ITV-RWTH Aachen to assess radiation effects. Complementary laminar flame speed measurements using a newly developed experimental setup allowing to record the pressure increase due to the flame propagation in the closed chamber and the evolution of the flame radius throughout the entire chamber will be conducted in a collaborative approach at ICARE-CNRS in Orléans, France. This technique was recently successfully used to obtain laminar flame speeds of methane/air mixtures at high-pressure and temperature. The method has the advantage of not being affected by radiation heat losses. Ammonia is well known for having low flame speeds and being thus subject to buoyancy effects. It is also planned to perform experiments under microgravity in the drop tower facility ZARM in Bremen with the ITV, RWTH Aachen chamber to suppress the influence of buoyancy while obtaining measurements for slow ammonia/air flames strongly impacted by radiation. The flame speeds measured under normal gravity, using both setups, and those measured under microgravity will then be used to provide a methodology to better account for heat losses by radiation of extremely slow burning flames.

• DFG Programme: Research Grants