Computational Fluid Dynamics of Catalytic Reactors

Today, the challenge in chemical and material synthesis is not only the development of new catalysts and supports to synthesize a desired product, but also the understanding of the interaction of the catalyst with the surrounding flow field. Computational Fluid Dynamics or CFD is the analysis of fluid flow, heat and mass transfer and chemical reactions by means of computer-based numerical simulations. CFD has matured into a powerful tool with a wide range of applications in industry and academia. From a reaction engineering perspective, main advantages are reduction of time and costs for reactor design and optimization, and the ability to study systems where experiments can hardly be performed, e.g., hazardous conditions or beyond normal operation limits. However, the simulation results will always remain a reflection of the uncertainty in the underlying models and physicochemical parameters so that in general a careful experimental validation is required. This chapter introduces the application of CFD simulations in heterogeneous catalysis. Catalytic reactors can be classified by the geometrical design of the catalyst material (e.g. monoliths, particles, pellets, washcoats). Approaches for modeling and numerical simulation of the various catalyst types are presented. Focus is put on the principal concepts for coupling the physical and chemical processes on different levels of details, and on illustrative applications. Models for surface reaction kinetics and turbulence are described and an overview on available numerical methods and computational tools is provided

Analytische und numerische Untersuchungen der Dynamik von Vormischflammen sowie deren Interaktion mit Ringwirbelstrukturen

Die Verwendung des Konzeptes der Vormischverbrennung in technischen Verbrennungsanlagen fördert die Ausbildung von selbsterregten Instabilitäten.Der Schwerpunkt der Arbeit liegt in der Berechnung des dynamischen Verhaltens bzw. des Frequenzgangs von pulsierten turbulenten vorgemischten Axialstrahlflammen. Dieses steht unter dem Einfluss der Bildung von kohärenten Ringwirbelstrukturen an der Brennermündung. Es werden sowohl instationäre Flammen als auch Ringwirbelströmungen numerisch untersucht

Analytische und numerische Untersuchungen der Dynamik von Vormischflammen sowie deren Interaktion mit Ringwirbelstrukturen

Die Verwendung des Konzeptes der Vormischverbrennung in technischen Verbrennungsanlagen fördert die Ausbildung von selbsterregten Instabilitäten. Der Schwerpunkt der Arbeit liegt in der Berechnung des dynamischen Verhaltens bzw. des Frequenzgangs von pulsierten turbulenten vorgemischten Axialstrahlflammen. Dieses steht unter dem Einfluss der Bildung von kohärenten Ringwirbelstrukturen an der Brennermündung. Es werden sowohl instationäre Flammen als auch Ringwirbelströmungen numerisch untersucht

Accelerating reactor development with accessible simulation and automated optimization tools

Methane CPOX is a common route to syngas, while monolith reactors are a common type of process intensified reactor. Given the general need in process intensified systems to extract improved performance, a proof-of-concept optimization study was conducted to maximize hydrogen productivity and minimize peak reactor temperature for methane CPOX on a coated metallic monolith reactor. In this study, DAKOTA (optimization toolkit), DETCHEM\u2122 (surface reaction and thermodynamics toolkit), and OpenFOAM (multiphysics simulation software) are newly integrated to optimize non-linear reactive configurations. Using an automated derivative-free multi-objective optimization method, the hydrogen productivity per volume (kg H2/m3/s) can be substantially increased while concurrently reducing the peak reaction temperature. Specifically, by allowing the coupled simulation framework to change the distribution and amount of catalyst, along with channel diameter, feed flow rate and inlet temperature, hydrogen productivity can be increased up to 1.8 times over previous literature values with a reduction in peak metal temperature of about 40\u202f\ub0C, or increased by about 1.6 times with a reduction in peak reactor metal temperature of about 120\u202f\ub0C, from a previously reported 818\u202f\ub0C down to below 700\u202f\ub0C. The presented results demonstrate the potential for design optimization in reactive systems in general, and in particular for process intensified components