Problem $2.(30$ pt$)$ Spent cooling water is recovered by evaporative cooling to reduce the

temperature of the water. If $100$mo$($l$)/($m$)$in of liquid water at $87\backslash$deg C needs to be cooled to $70\backslash$deg C$,$ what

is the required flow rate for the air stream assuming that the process is adiabatic, the vapor exit is

saturated air and the feed air is:

$($a$)20\backslash$deg C$,80\%$ relative humidity

$($b$)25\backslash$deg C$,50\%$ relative humidity

$($c$)30\backslash$deg C$,10\%$ relative humidity

Explain the results in terms of the relative importance of the air temperature and the humidity.