Wet solids are dried in a tray$-$type batch dryer, shown below, using hot air at temperature T$1=$

$97\mathrm{.}5$o

C and humidity H$1=0\mathrm{.}01[$kg H$2$O$/$kg dry air$].$ The hot air flows with the velocity of $1$

m$/$s parallel to the tray resulting in the convective heat transfer coefficient of $14\mathrm{.}7$ W$/$m$2$ K$.$

The initial moisture content in the solids is X $=0\mathrm{.}40[$kg H$2$O$/$kg dry solids$],$ while the critical

moisture content is Xc $=0\mathrm{.}05[$kg H$2$O$/$kg dry solids$].$ The density of solids is $\backslash$rho $=1,500[$kg dry

solids $/$m$3$

$].$ The length, the spacing and the height of the trays are Lt $=1\mathrm{.}8$ m$,$ b $=0\mathrm{.}05$ m$,$ and

x$1=0\mathrm{.}05$ m$,$ respectively. Assuming that the solids are at the wet bulb temperature of hot inlet

air, determine:

a$)$ The temperature of the solids;

b$)$ The outlet temperature $($T$2)$ and humidity $($H$2)$ of the air;

c$)$ What will be the moisture content in the solids after $2$ hours of drying?