$3-34.$ A building has a calculated cooling load of $20$ tons, of which $5$ tons is latent load. The space

is to be maintained at $72$ F db and $50$ percent relative humidity. Ten percent by volume of the

air supplied to the space is outdoor air at $100$ F db and $50$ percent relative humidity. The air

supplied to the space cannot be less that $55$ F db $.$ Assume barometric pressure at sea level, and

using the program PSYCH$,$ find $($a$)$ the minimum amount of air supplied to the space in cfm$,$

$($b$)$ the amounts of return air and outdoor air in cfm$,($c$)$ the conditions and volume flow rate

of the air entering the cooling coil, and $($d$)$ the capacity and SHF for the cooling coil. $($Hint:

Estimate the amount of outdoor air and supply relative humidity and iterate.$).$ Assuming the supply temperature is $55$F$,$ convert to SI UNIT and solve.