CFD Evaluation of In Situ Probe Techniques for Catalytic Honeycomb Monoliths

• Published in: Emission control science and technology (Online) 2016-10, Vol.2 (4), p.188-203
• Main Authors: Hettel, Matthias, Antinori, Claudia, Deutschmann, Olaf
• Format: Article
• Language: English
• Subjects: 13 – 15 September 2015; Axial diffusion; Bad Herrenalb; Carbon monoxide; Catalysts; Computational fluid dynamics; Computer applications; Computer simulation; Design optimization; Earth and Environmental Science; Earth Sciences; Environmental Science and Engineering; Error analysis; Fluid dynamics; Germany; Hydrodynamics; Industrial Chemistry/Chemical Engineering; Insertion; Mathematical models; Monolithic materials; Oxidation; Palladium; Reduction; Rhodium; Special Article from MODEGAT IV; Suction; Surfaces and Interfaces; Thin Films; Upstream; Vapor phases
• ISSN: 2199-3629; 2199-3637
• DOI: 10.1007/s40825-016-0043-1

Collecting spatially resolved gas phase concentration profiles in catalytic monoliths by applying suction probe techniques has become an important tool for understanding the reaction sequence and for optimizing the design of structured catalysts. The impact of the capillary on the data is investigated by means of computational fluid dynamics (CFD) simulations using the exemplary cases of catalytic partial oxidation of methane over rhodium and oxidation of carbon monoxide over palladium. The influence of a suction probe inside a rectangular channel of a monolith on flow field and concentration profiles are discussed. Four different configurations were investigated: probe in center or corner of the channel with insertion from upstream or downstream in each case. If the capillary is located in the corner of the channel, the influence on the data is negligible. For a position in the center, a noticeable impact was observed. A simple analytical model can predict the reduction of the mass flux due to the insertion of the probe. The worst case exhibits a reduction >50 %. The measuring error is dependent on the direction of insertion of the capillary into the channel (upstream or downstream). Additionally, axial diffusion plays a significant role. For any interpretation of the data, the influence of the probe on the measured data has to be considered. The quantification of the error requires three-dimensional CFD simulations.