Design methods transfer unit concept

Another and in some ways a more useful design method of packed towers is the use of the transfer unit concept. For the most common case of A diffusing through stagnant and nondiffusing B, Eqs. (10,6-14)- 10.6-17) can be rewritten as... 

Mass-transfer calculations, such as the analysis or design of separation units, can be solved by two distinctly different methods, based on either the concept of (1) Equilibrium stage processes or (2) Diffusional rate processes. 

A considerable amount of data on absorption-colunm performance is presented in terms of the height of the transfer unit (HTU), and design procedures based on this concept are preferred by many because of their simplicity and similarity to plate-column calculation methods. The basic concept which was originally introduced by Chilton and Colburn (1935) is that the calculation of column height invariably requires the integration of a relationship such as (from equation 1-9)... 

---