# Mass Transfer

Tags:
1. Jan 3, 2019

### Rahulx084

I have studied that mass transfer is of two types
1. Molecular mass transfer(diffusion)
2. Eddy diffusion
then in later portion of the book I found that there is convective mass transfer too, I wanted to ask if both convective mass transfer and eddy diffusion are same ?
I read this equation N_i = J_i + C_i V_m
where J_i = molar diffusive flux of component i related to molar average velocity
N_i =Total molar flux of component i
C_i V_m = convective flux of species i due to molar average velocity

lets take an example of a fluid flowing in pipe with some velocity x and I drop some ink in the flowing fluid , so now this is a binary mixture of fluid and ink . My question is what are absolute velocities of both species and what is the molar average velocity , if concentration is C1 and C2 respectively .I'm confused in the definition of these velocities .

• Why this equation is used in proving D_AB=D_BA , like in a ethanol water system where only diffusion is taking place and this equation have convective term too.
• convective diffusion term of particular species=(mole fraction)(N) , is this term and N_A = K_c (concentration difference) are same ? where K_c =convective mass transfer coefficient