Nucleation Damkoehler number

An adaptation of the Damkochicr number (Da) is a useful concept for evaluation of mixing effects in crystallization. It is the ratio of the characteristic mixing time to its corresponding process time (nucleation induction time, crystal growth/supersaturation release time, or reaction time). Studies of these times and the resulting predicted Damkoehler number in a laboratory setting can provide evidence of possible scale-up problems. 

It is helpful to visualize the relationship between mixing and nucleation rates through an analogy with the reaction Damkoehler number (Da). The Da number for reaction is defined as Da for reaction = mixing time/reaction time... 

Sections 6.3.1.4 and 6.4 on the use of the Damkoehler number concept, the need for effective location of a feed line may be evaluated from a comparison of nucleation and mixing rates. 

The importance of the feed location for chemical reactions has been clearly established by the work referenced above and many others. The literature contains less data on crystallization. However, undesired nucleation is potentially present for all crystallization systems, depending on the nucleation rate and the degree of local supersaturation. The analogy between reaction sensitivity and supersaturation sensitivity can be visualized through the concepts represented by the Damkoehler number, as discussed in Section 6.3.1.4 above. 

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