Feed air at $90C$ and $1\mathrm{.}00$atm $($absolute$)$ contains $0\mathrm{.}5$ mole $\%$ water. A continuous stream of this

air at $2,500k\frac{g}{h}r$ enters a compressor$-$condenser integrated unit, in which the temperature is

lowered, and the pressure is raised to $3\mathrm{.}5$atm. The air leaving the integrated unit is then heated

isobarically to $130C.$

$($a$)$ Assuming the condensing temperature is equal to the coolant temperature, predict either

cooling$-$tower water $(H_{2}O)$ at $20\mathrm{.}5C$ or refrigerant $A($with a vapour pressure of $4\mathrm{.}962$

$mmHg))$ at $1\mathrm{.}1C$ is a more suitable coolant for the condenser and determine the

percentage of water that is condensed from the feed air of the chosen coolant.

$($b$)$ Based on the chosen coolant in $($a$),$ estimate the relative humidity of the air leaving the

heater and the ratio of $($exit air volume at $130C/$feed air volume at $90C).$