Interstitial-scale modeling of catalytic foam reactors: partial oxidation of methane
Gregor Wehinger, Matthias Kraume
Chemical and Process Engineering, Technische Universitšt Berlin, Fraunhoferstr. 33-36, 10587 Berlin, Germany
Catalytic foams represent a promising alternative to conventional ﬁxed-bed reactors in many applications in the chemical and process industry. They are characterized by their low speciﬁc pressure drop, high mechanical stability at relatively low speciﬁc weight, enhanced radial transport, as well as a high geometric surface area. Designing and planning of foam reactors can be supported by computational ﬂuid dynamics (CFD) simulations. However, the actual shape of a catalytic foam is highly complex and therefore difficult to model.
In this work we present a fully automatic workﬂow (catalytic Foam Modeler: catFM) with which it is possible to model a realistic foam structure ready for CFD simulations without using data from time consuming image analysis. The modeler is based on a random distribution of points in space followed by the Voronoi tessellations. It applies common foam characteristics, i.e., porosity, speciﬁc surface area and strut dimensions, as input parameters to generate artiﬁcially the foam structure. Typical morphological parameters such as speciﬁc surface area, as well as pressure drop predictions can be reproduced with a high accuracy. Finally, the performance of the tool catFM is illustrated by modeling a catalytic partial oxidation reformer of methane in a foam coated with a rhodium catalyst from literature . Two sets of simulations are performed, one with a ﬁxed surface temperature profile obtained from experiment, the other takes heat transfer inside the solid material into account. On the surface a detailed reaction mechanism is implemented . For both cases, the experimental species proﬁles can be well reproduced. However, only the second set allows a ﬂexible utilization without knowing the temperature proﬁle a priori. With this modeler it is possible to plan and design catalytic foams by predicting temperature and species concentrations without relying on transport correlations.
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