The first Damkohler number and its importance for characterizing the influence of mixing on competitive chemical reactions

The first Damkohler number, Da(I), is a widely-used P group for characterizing the influence of mixing on competitive chemical reactions (CCRs). Although numerous different definitions of Da(I) are present in lit-erature, there has been little discussion on how these definitions vary in terms of application areas. In this work, we overcome this issue by deriving Da(I) for three examples of different complexity. We find that defining Da(I) by physical meaningful time scales has no advantage over a definition by characteristic time scales only. Furthermore, we identify that several issues regarding Da(I) usage are due that two different types of Da(I) numbers should be discriminated: The equation-based Da(eb) and the mechanistic Da(mech). Da(eb) is part of a P group series with the Reynolds number and enables the scale-up of geometrically similar reactors. Alternatively, Da(mech) enables to transfer results between differently shaped micro-mixing reactors but is limited to micro mixing dominated reactors. (c) 2020 Elsevier Ltd. All rights reserved.

Automated summary

In this study, we discuss the variations in application areas of different definitions of the Damkohler number, concluding that defining Da(I) by physical meaningful time scales has no advantage over a definition by characteristic time scales only. We also identify the need to discriminate between two different types of Da(I) numbers: equation-based Da(eb) and mechanistic Da(mech).