In‐situ‐Stoffübergangsmessungen mit Computertomographie: Auswahl des Testsystems

For the in‐situ measurement of the mass transfer of a gas phase into a liquid film on a packing using X‐ray computed tomography, a substance combination is needed. The thickness of the liquid film was measured using computed tomography, to ensure that enough pixels in the film are available for the mass transfer experiments. In order to decide if the substance combination is distinguishable in the CT images, the X‐ray activity of gases and of dissolved gas in the liquid phase was investigated. For the determination of the maximum solubility the quantum chemical model COSMO‐RS was used to simulate the vapor‐liquid equilibria.     

Meßmethoden konvektiver Stoffübertragung

Methods of measuring convective mass transfer . The principal methods of measuring convective transfer of momentum, heat, and mass are surveyed on the basis of the three-fold analogy existing between the transfer of momentum, heat, and mass. The most simple and most sensitive method is the mass transfer technique based on the principle of absorption with chemical reaction and coupled colour reaction. It is shown by selected examples that this measuring technique is already developed to the point where it serves adequately for the solution of most complex problems met with in practice. It is distinguished by its high accuracy of measurement, simple application, high local resolution, and its utilizability both for developable as well as for undevelopable surfaces. By way of the local mass transfer observable as colour-intensity distribution it also affords a simple and illustrative means of making flow processes on solid surfaces visible. The quantitative evaluation is accomplished by reflectance photometry; quantitative image processing methods are available for complex distributions. In addition, it is shown that the mass transfer technique is also suitable for practical utilization as a method for measuring turbulence. The measuring principle is based on the extremely high dependence of the length of transitional separation bubbles in the nose section of flat plates of finite thickness in longitudinal flow on the turbulence intensity.     

Stoffübergang in hochviskosen Gemischen

Mass Transfer in High-Viscous Media High-viscous media are processed in a number of industries like chemical, petrochemical as well as food industries. Design of mass transfer equipment for such media is very difficult because of the rather limited data. Therefore, the absorption of oxygen from air into glycerol-water mixtures has been studied experimentally with different sieve trays and operating conditions. Furthermore, the results of supplementary absorption experiments of oxygen into squalane or water show that the results with the system oxygenglycerol-water mixtures are transferable to other systems.     

Stoffübergang in hochviskosen Gemischen

Migration in High Viscous Mixtures Although high viscous media often occur in the chemical, petrochemical, pharmaceutical and food industry, the optimal layout of material exchange plants to separate such mixtures is only possible in a limited way because of missing data. To improve the knowledge of material exchange processes in high viscous mixtures, tests for fluid dynamics and materials exchange processes in high viscous mixtures, test for fluid dynamics and materials migration were carried out with various sieve bottoms. Hereby absorption tests with the material system of oxygen-glycerol/water were carried out during changes of the processing and material parameters as well as of the sieve bottom geometry. The measuring results show that the separation capacity of a sieve bottom can be significantly increased by suitable choice of processing conditions and the sieve bottom geometries.     

Stoffübergang in hochviskosen Gemischen

Mass Transfer in Highly Viscous Media Chemical, pharmaceutical, and petrochemical as well as food industry has to deal increasingly with processes where mass transfer in highly viscous media is involved. Design of mass transfer equipment for such media is very difficult because of the rather limited experimental data. Therefore, the evaporation of pure cyclohexanol into air as well as the absorption of oxygen from air into glycerol-water solutions has been studied experimentally on a single sieve tray. The results show that the mass transfer efficiency of such trays is greatly enhanced by choosing the proper operating conditions and an optimised design.