H$2-$TRAY DRYER

The air at a temperature of $40C$ and having a humidity $H=0\mathrm{.}015kg$ water $\frac{?}{kg}$ dry air is

used to dry a sample of solids saturated with water. Its rate of drying curve is given

below. The heat transfer is by convection only.

What is the critical moisture content, Xc$,$ of the solid?

ii$.$ What is the rate of drying in the constant rate period, Rc$?$

iii. If the rate of drying in the falling rate period can be assumed to be linear as

$R=ax,$ determine the constant $\text{'}a\text{'}.$

Free moisture, $x$

$(kg{H}_2\frac{O}{k}g$ dry solid$)$