ISSN:
0032-3888
Keywords:
Chemistry
;
Chemical Engineering
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
The striation thickness distribution developed in an impingment T-mixer is predicted using the statistical theory of turbulent diffusion. The predicted distribution is independent of the mixing nozzle Reynolds number, in agreement with some experiments, and is primarily a function of the mixing head geometry, the ratio of the reagent flow rates and the residence time distribution of the flow in the mixing head. Mixing is described as the result of fluid deformation in the intertial subrange of turbulent flow. The relationship of deformation to time and energy dissipation rate ∊ is examined. In the impingement T-mixer ∊ is related to the kinetic energies of the streams entering and leaving the head. (There are no surface tension effects and pressure is relatively uniform in the mixing head, so that the kinetic energy is dissipated by viscous forces.) The distribution of residence times of fluid elements in the T-mixer is responsible for varying degrees of deformation and hence a distribution of striation thickness. This residence time distribution does not seem to have been studied and the flow pattern was thus modeled as perfect macromixing, having an exponential distribution. The procedure developed in this paper to calculate the distribution of striation thickness allows reasonable estimates of its parameters from fluid mechanical information and showed good agreement with experimental values, without having to fit any quantities. This new approach to striation thickness distribution is worth further evaluation.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pen.760231005
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