Question

a) What is the Damkohler number? b) What is the significance of a system with a low Damkohler number?

Answer 1

Step-by-step explanation:

Damkohler numbers are mainly used in chemistry. It is a dimensionless number. It denotes the timescale at which the reaction takes place with relation to the transport phenomenon.

There are two Damkohler numbers

First Damkohler number is the ratio of reaction rate to the convective mass transport rate.

`Da=\frac{\text{Reaction rate or chemical reaction timescale}}{\text{Convective mass transport rate}}`

Second Damkohler number is the ratio of reaction rate to the diffusive mass transfer rate

`Da_(II)=\frac{\text{Reaction rate or chemical reaction timescale}}{\text{Diffusive mass transfer rate}}`

It can be seen from the equations that if the numerator is greater than the denominator then Da>1 and vice versa.

So,

When Da>1, the diffusion rate distribution is lower than the reaction rate.

When Da<1, the reaction rate is lower than the diffusion rate.