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An Analysis of Mixing in a Typical Experimental Set‐up to Measure Nnucleation Rates of Precipitation Processes
Author(s) -
Roelands C.P.M.,
Derksen J.J.,
ter Horst J.H.,
Kramer H.J.M.,
Jansens P.J.
Publication year - 2003
Publication title -
chemical engineering and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.403
H-Index - 81
eISSN - 1521-4125
pISSN - 0930-7516
DOI - 10.1002/ceat.200390045
Subject(s) - mixing (physics) , micromixing , dispersion (optics) , supersaturation , turbulence , nucleation , mechanics , dissipation , precipitation , chemistry , residence time (fluid dynamics) , thermodynamics , residence time distribution , measure (data warehouse) , flow (mathematics) , analytical chemistry (journal) , physics , chromatography , optics , meteorology , geotechnical engineering , quantum mechanics , database , computer science , engineering
Mixing in a typical experimental setup to measure nucleation rates in precipitation processes was assessed. To determine these rates as a function of the driving force for concomitant polymorphs, it is necessary to perform these experiments at constant supersaturation. Therefore, the mixing time must be shorter than the time for the first nuclei to appear. For fast precipitation processes complete mixing has to be achieved within milliseconds. The mixing performance of a wide angle Y‐mixer was studied to see whether this is possible. An analysis of characteristic mixing times as a function of the average energy dissipation rate showed that turbulent dispersion of the feed streams determined the rate of the mixing process. The characteristic time for turbulent dispersion was of the same order as an arbitrarily set residence time in the Y‐mixer. However, CFD simulations of the flow showed large variation in the spatial distribution of the dissipation rate and revealed unsatisfying macromixing.