The height of a cooling tower is $0\mathrm{.}4m.$ It is operating at $1$ atmospheric pressure with air flowing upward through the column and warm water flowing in a counter$-$current flow fashion.

$\backslash$table$[[$inlet water T$($C$),45\mathrm{.}6],[$wet bulb inlet air T$($C$),19],[$dry bulb inlet air T$($C$),25\mathrm{.}2],[$wet bulb outlet air T$($C$),31\mathrm{.}5],[$dry bulb outlet air T$($C$),34\mathrm{.}5],[$outlet water T$($C$),31\mathrm{.}6]]$

If the overall mass transfer coefficient is $150mo\frac{l}{at{m}^{**}{m}^{3**}(s)}$ and the number of a transfer unit is $0\mathrm{.}5,$ determine:

A$.$ The mass flow rate of dry air per unit area of cross section. $($Molecular weight of air $=29k\frac{g}{k}$mol points$)$

B$.$ The height of transfer units.$(3$ points$)$

Solution: