Dirk Ziegenbalg

Getting the Most out of Solar Irradiation: Efficient Use of Polychromatic Light for Water Splitting

To increase the fraction of utilizable polychromatic light, a new reactor concept was developed and manufactured by using rapid prototyping technologies. Investigation of the prototypes revealed enhancements of the photocurrent by up to one order of magnitude, when TiO2 was used as the photoanode in combination with commercially available photovoltaic cells. The reported concept is scalable and an easy transfer to technical scale is expected from a technological as well as an economical perspective. Experimental results underline the conclusion that to achieve efficient overall use of solar irradiation both the material as well as the reactor/process must be considered. Combining these complementary approaches allows largest possible optimization potential. With respect to ongoing research, the concept also breaks ground for the development of catalysts.

Evaluation of different micromixers by CFD simulations for the anionic polymerisation of styrene

Abstract To ensure a sufficient reaction control, including fast mixing and heat removal, microstructured devices were chosen to conduct anionic polymerisations. To decrease the experimental effort and the resulting costs, a numerical approach was followed to apply decision support during experimental planning. Semi-quantitative CFD calculations were used to determine the best suited micromixer out of a collection of different devices. Using the numerical investigated micromixers for experimental investigations, the general order gained from CFD calculations was confirmed. It could be shown that CFD calculations can beneficially be used to rank micromixing devices for specific process conditions and synthesis tasks.