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Project No. 104

Plasma flow reactor

Experimental investigation of plasma assisted ammonia combustion using multi-scalar laser diagnostics

Dr.-Ing. Tao Li, Prof. Andreas Dreizler
Technical University Darmstadt, Department of Mechanical Engineering, Institute of Reactive Flows and Diagnostics
 
  
The urgent need for sustainable and clean energy sources has never been more critical due to the escalating impacts of climate change caused by fossil fuel consumption. Climate-friendly chemicals for temporary energy storage present opportunities to reduce greenhouse gas emissions, aligning with the common interests of international collaborations under the Kyoto Protocol and the Paris Agreement. In Germany, the use of hydrogen (H2) has been prioritized under the National Hydrogen Strategy of 2020 to achieve the national carbon-neutrality target and enhance energy security by reducing the dependency on fossil fuel imports.

 
One major challenge of using H2 is storage and transportation due to its high diffusivity, low volumetric energy density, and high flammability. Among all storage materials, ammonia (NH3) stands out with a gravimetric H2 density of 17.8 wt% and efficient liquefication by compression at 10 bar and room temperature. NH3 exhibits the highest volumetric H2 density, approximately 1.6 times that of liquid H2 and three times that of H2 compressed at 700 bar. With the existing production capacity and distribution infrastructure, NH3 is a perfect H2 and energy storage. Burning NH3 or NH3 blends in a stationary gas turbine reveals huge potential to produce carbon-free electricity and retrofit existing infrastructure.

Project Objectives

To enhance NH3 oxidation reactions in turbulent flows, non-thermal plasma technology has a high potential to accelerate the low-temperature kinetics and improve flame stability. However, fundamental processes in plasma-assisted combustion of NH3 are largely unexplored. The proposed research project aims to:1) develop multi-species and temperature measurements to probe the thermochemical states of premixed NH3 combustion and 2) conduct detailed investigations of plasma-assisted NH3 flames, which are potentially enhanced by intermediate species and low-temperature chemistry. These investigations, enabled by applying advanced in situ spectroscopic measurement techniques, can provide novel insights and a deeper understanding of plasma-flame interactions, essential for large-scale applications.
Overarching objectives are summarized as follows.

  • Design and establish suitable reactor configurations for PAC
  • Develop the simultaneous multi-scalar laser diagnostics
  • Develop the methodology to quantify the NO emission
  • Investigate the plasma effect on combustion intermediates and temperature
  • Prepare the method to determine burning velocity and extinction limits
  • Generate novel data sets for developing simulation tools and chemical kinetics
Methods and Technology
  • A laminar flame reactor assisted by a DBD (see Figure)
  • Quantitative NO-LIF measurements
  • Multi-scalar LIF imaging of NH3/NH/OH and quantitative temperature measurements
  • Flame and flow visualization using simultaneous OH-LIF/PIV measurements
  • Laminar burning velocity and extinction strain rate measurements