Damk�hler numbers
The Damköhler numbers (Da) are dimensionless numbers used in chemical engineering to relate chemical reaction timescale to other phenomena occurring in a system.
There are several Damköhler numbers, and their definition varies according to the system under consideration.
For a general chemical reaction A → B of n-th kinetic rate constant
- C0 = initial concentration
- n = residence time.
In reacting systems that include also interphase mass transport, the second Damköhler number (DaII) is defined as the ratio of the chemical rate to the mass transfer rate
<math>DaII = \frac{k C_0^{n-1}}{k_g a}<math>
where
- k_g is the global mass transport coefficient
- a is the interfacial area
