We discuss diffusion (including sedimentation) and thermal diffusion in the critical region (both for liquid‐liquid and vapour‐liquid equilibria) of binary fluid systems. In particular, we present diagrams and discussions of experimental values of diffusion coefficients, sedimentation coefficients, and thermal diffusion factors for the liquid systems n‐hexane + nitrobenzene (with upper consolute point) and water + triethylamine (with lower consolute point), both at 1 bar, and for the fluid system methane + propane at about 73°C in the critical vaporization region. In the last case, we check a formula proposed by the author in 1950.
The most common and reliable technique used for flame stabilization of industrial combustors with high thermal loads is the application of strongly swirling flows. In addition to stabilization, swirl flames offer the possibility to influence emission characteristics by simply changing the swirl intensity or the type of swirl generation. Despite of these major advantages, swirling flows tend to evolve flow instabilities, that considerably constitute a significant source of noise. In general, noise generation is substantially enhanced, when such a swirling flow is employed for flames. Thus, the minimization of the resulting noise emissions under conservation of the benefit of high ignition stability is one major design challenge for the development of modern swirl stabilized combustion devices. The present investigation makes an attempt to determine mechanisms and processes to influence the noise generation of flames with underlying swirling flows. Therefore, a new burner has been designed, that offers the possibility to vary geometrical parameters as well as the type of swirl generation, typically applied in industrial devices. Experimental data has been acquired for the isothermal flow as well as swirl flames by means of 3-D-LDV-diagnostics comprising the components of long-time averaged mean and rmsvelocities as well as spectrally resolved velocity fluctuations for all components. The noise emission data was acquired with microphone probes resulting in sound pressure levels outside the zone of the perceptible fluid flow. Along to the experiments, numerical simulations using RANS and LES have been carried out for isothermal cases with different burner outlet geometries. The results of the measurements show a distinct rise of the sound pressure level, obtained by changing both the test setup from the isothermal into the flame configuration as well as the geometrical parameters. This is also resembled by the LES simulation results. Furthermore, a physical model has been developed from experiments and verified by the LES simulation, that
Messungen an unterstöchiometrischen Übergangsmetallcarbiden (Gruppe IV, V) im Hinblick auf deren Eignung als Katalysatoren für den Dehydrierungsprozeß Äthylbenzol ‐ Styrol zeigen eine Abhängigkeit der Dehydrierungsrate von der Konzentration des Kohlenstoffs im Metallgitter und von der Struktur der Carbidphase.
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