SPP 1141: Analysis, Modeling and Calculation of Mixing Processes with and without Chemical Reaction
Thermal Engineering/Process Engineering
Final Report Abstract
The homogenization of single phase gases or liquids with chemical reactive components by mixing belongs to one of the oldest basic operations applied in chemical engineering. Improved modern methods for experimental research and visualization, for simulations and numerical calculations of mixing and chemical reactions in micro and macro scale of time and local coordinates stimulated the cooperation of 17 research groups. The objective of the investigations was to improve the prediction of efficiencies and selectivity’s of chemical reactions on macroscopic scale. The results should give an understanding of the influence of the design of different mixing equipment on to the momentum, heat and mass transfer as well as reaction processes running on microscopic scales of time and local coordinates. The careful analysis of the previous existing results for mixing processes in equipment with different velocity fields revealed 1. a lack in measurement methods for three dimensional concentration and temperature fields giving a high accuracy in time and spacial coordinates, 2. a very limited set of closure equations derived from experiments inter relating velocityand concentration profiles with simultaneously running homogeneous chemical reactions, 3. large deficiencies in extended knowledge for the derivation of models predicting relations between the different scales for mixing processes in macroscopic single phase flows with simultaneous mass transport and chemical reactions. Based on these deficiencies in our basic knowledge in micro and macro-mixing, the scientific objectives for the Priority Program were derived. As results newly developed methods of measurement are adjusted to the scales of the selected special transport and conversion processes. They allow a more detailed modelling of the mixing processes by the formulation of an appropriate set of momentum-, heat- and mass balance equations as well as boundary conditions in time and spacial coordinates together with constitutive equations and reaction kinetics equations as closure laws for numerical and analytical calculations. The improved and more detailed modelling leads to a major progress in predicting mixing processes on the different scales adjusted to transport and reaction processes in molecular, micro- and macro dimensions. As a consequence improved numerical calculations are performed on the basis of newly derived experimental, measurement and modelling methods which are the basis for the prediction of mixing time as well as conversion rates and selectivity’s of chemical reactions during the mixing process.
