N$\_($L$)=$N$\_($T$)=20$ S$\_($L$)=60$mm and S$\_($T$)=30$mm$,$ respectively.

Saturated steam at a pressure of $2\mathrm{.}455$ bars enters the tubes, and a uniform tube outer surface temperature of T$\_($s$)=390$K may be assumed to be maintained as condensation occurs within the tubes.

$($a$)$ If the temperature and velocity of the air upstream of the array are T$\_($i$)=300$K and V$=4($m$)/($s$),$ what is the temperature T$\_(0)$ of the air that leaves the array? As a first approximation, evaluate the properties of air at $300$ K $.$

$($b$)$ If the tubes are $2$ m long, what is the total heat transfer rate for the array? What is the rate at which steam is condensed in k$($g$)/($s$)?$

$($c$).$Cl Assess the effect of increasing N$\_($L$)$ by a factor of $2,$ while reducing S$\_($L$)$ to $30$ mm $.$ For this configuration, explore the effect of changes in the air velocity.