Greifswald 2024 – scientific programme

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P: Fachverband Plasmaphysik

P 16: Atmospheric Pressure Plasmas and their Applications III

P 16.3: Talk

Wednesday, February 28, 2024, 14:45–15:00, WW 1: HS

CFD and Heat Transfer Modeling of a Microwave Atmospheric Plasma Torch for CO₂ Conversion — •Stefan Merli, Katharina Wiegers, Marc Bresser, Andreas Schulz, Matthias Walker, and Günter Tovar — IGVP, University of Stuttgart, Stuttgart, Germany

Microwave plasma torches at atmospheric pressure offer an interesting way to split CO₂ and convert it to O₂ and CO, the latter of which is an important base material for chemical synthesis. The investigated microwave plasma torch creates a CO₂ plasma inside a quartz tube via two resonators. To protect the quartz tube from the hot plasma of around 6000 K, tangential gas inlets generate a rotational cold gas flow around the tube surface. The hot gas from the plasma and the cold gas are then mixed in a nozzle to increase the amount of converted gas. The nozzle and the subsequent expansion zone also cause the gas to cool quickly, which quenches back reactions from CO and O₂ to CO₂. Since the gas flow conditions and the temperature distribution are of great importance for a high conversion efficiency, CFD and heat transfer simulations were carried out in Comsol Multiphysics. The aim is to improve the conversion efficiency by optimizing geometry of the torch and the nozzle with regard to hot/cold gas mixing and effective quenching. A comparison of simulations and experiment reveals different flow regimes of the effluent for different gas flows which are attributed to increasing turbulences in the expasion zone. Since the turbulences increase cooling and the contact with the wall, they are beneficial for quenching and therefore for a high conversion efficiency.

Keywords: Microwave plasma torch; CO2 conversion; Modeling