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A mass transfer model is developed using the volume-of-fluid (VOF) method with a piecewise linear interface calculation (PLIC) scheme in ANSYS FLUENT for a free-rising bubble. The mass flow rate is defined via the interface by Fick's law and added into the species equation as a source term in the liquid phase using the user-defined functions (UDFs) in ANSYS FLUENT. The interfacial concentration field for the mass flow rate is discretized by two numerical methods. One of them is based on the calculation of the discretization length between the centroid of the liquid volume and the interface using the liquid void fraction and interface normal vectors at the interface cells, while in the second method the discretization length is approximated using only the liquid void fraction at the interface cells. The influence of mesh size, schemes, and different Schmidt numbers on the mass transfer mechanism is numerically investigated for a free-rising bubble. Comparison of the developed mass transfer model with the theoretical results shows reasonable and consistent results with a smaller time-step size and with cell size.

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Most processes for the manufacturing of ceramic components have in common that they are based on a powder-technological shaping process using a negative mold and subsequent thermal compaction. For microcomponents these processes require special adjustments especially when high aspect ratio structures have to be fabricated. Shaping methods that allow the application of silicone rubber molds, like low-pressure injection molding (LPIM) or centrifugal casting, not only have the potential to fabricate ceramic components with high aspect ratios but also offer a possibility for the rapid manufacturing of ceramic microcomponents.

Additive manufacturing (AM) as a novel technique for generating complex geometries is attracting interest in R&D. Besides the vast opportunities in rapid prototyping and manufacturing, especially in the chemical industry, the extended possibilities of producing devices highly adapted to specific tasks are opening new avenues for process intensification and miniaturization. In this work 3D-structured components for fluidic devices manufactured by selective laser melting are presented. Fluid guiding elements (FGE) structured with precisely defined fluid passages in the submillimeter range for absorption processes were additively manufactured. The elements were characterized and evaluated for CO 2 absorption in water and NaOH solution. In general, the FGE structures show enhanced gas−liquid mass transfer in CO 2 absorption. The absorption coefficient k l for CO 2 in water is in the same range as reported for microstructured falling film devices. This example demonstrates the opportunity of using AM to produce innovative fluidic devices.