Introduction of Characteristic Numbers

A chemical process is a combination of a chemical substance transition and a technical apparatus. The main factors which are influenced by thermodynamics, kinetics and design properties of the apparatus can be combined in three characteristic numbers. These are  

ATad provides direct information on the exothermic effect of the chemical reaction. Therefore it is of special importance for the safety assessment of chemical processes. Typical values range from 10 K for either highly diluted syntheses or for reactions with a very small exothermicity, up to 400 K for highly concentrated or strongly exothermic reactions. Decompositions may even have significantly higher values. 

The Damkoehler number Da represents the ratio of a characteristic reaction time to the kinetic time constant of the reaction and is therefore a measure for the reaction time. The attribute characteristic refers to the individual definition necessary for each 

The third characteristic number, which was first introduced by Westerterp as a modified Stanton number, combines all relevant parameters which determine the cooling capacity of a chemical reactor. This characteristic number is equivalent to the time constant of cooling in the dimension bearing domain 

This group of characteristic numbers is supplemented by the so-called thermal reaction number 

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