Warm water at $318K$ is to be cooled to $303K$ by countercurrent contact with air in a tower packed with wood slats. The inlet air has a dry$-$bulb temperature of $304K$ and a wet$-$bulb temperature of $295K.$ The mass flow rate of water is $100\frac{kg}{m^2}$min and the air used is $1\mathrm{.}3$ the minimum.

Consider that hLa $\frac{?}{k{r}_r},a=-12\mathrm{.}61$

Calculate:

a$.$ The dry air flow rate to be used.

b$.$ The height of packing if $H_{tG}=0\mathrm{.}54m$