An evaporative cooling tower $($see the figure below$)$ is used to cool water from $110$ to $81F.$ Water enters the tower at a rate of $m_1^{}=270000lb\frac{m}{h}r.$ Dry air $($no water vapor$)$ flows into the tower at a rate of $m_3^{}=130000lb\frac{m}{h}r.$ If the rate of wet air flow out of the tower is $m_2^{}=135900lb\frac{m}{h}r,$ determine

$($a$)$ the rate of water evaporation in $lb\frac{m}{h}r,$

$($b$)$ the rate of cooled water flow in $Ib\frac{m}{h}r.$

$($a$)m_w^{}=$

$!lb\frac{m}{h}r$

$($b$)m^{}=$ i

$!$

$lb\frac{m}{h}r$