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G. Ogus
KU Leuven, Department of Mechanical Engineering, 3000, Leuven, Belgium

Maarten Vanierschot
KU Leuven, Department of Mechanical Engineering, 3000, Leuven, Belgium

DOI: 10.1615/TFESC1.cmd.012656
pages 365-378

KEY WORDS: CFD, Swirling flow, Reactor Clogging Prevention


Solar thermal methane cracking reactors offer emission free production of hydrogen and carbon black both of which are crucial commodities in industry. However, carbon agglomeration and deposition during methane conversion remain as the main problems preventing the reactor from continuous operation. It is well known that the flow dynamics has an influence on the carbon particle behavior inside the reactor. However, a thorough study on the particle-gas interaction and impact of flow pattern must be conducted to reduce carbon deposition. There have been significant previous studies done on carbon deposition reduction via turbulent flow in the form of a tornado or vortex. In most of these studies, vortex flow is generated either by controlling the flow rate, or by making changes in the reactor design intuitively. A very limited number of studies investigates the impact of solar reactor geometry on flow pattern and velocity distribution by underlying the driving physical phenomenon. There is also limited number of novel solar reactor design to generate specific flow patterns. This study targets to fill up these gaps by bringing a novel approach inspired from flow control effects of annular nozzles in swirl burners. A nozzle jet that is successful in creating swirl flows in swirl burners has been adapted to a solar reactor. This paper presents the effect of this swirl generating nozzle jet on the flow inside the reactor via Computational Fluid Dynamics analysis. Although swirling flow is controllable and it has the potential to avoid carbon deposition, it has some drawbacks such as vortex breakdown and precessing vortex core that may affect the mixing and reaction kinetics. It is observed that the swirl jet behavior in the reactor is very similar to that of a swirl burner. Recirculation structures for the swirl flow zone and instabilities are discussed per CFD simulations obtained for various cases. Also, the instabilities are identified in terms of frequency and magnitude. It is seen that particle behavior, thus deposition is a potentially controllable phenomenon.

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