An air-cooled steam condenser is operated with air in cross flow over a square, in-line array of 400 tubes ( 20), with an outside tube diameter of 20 mm and longitudinal and transverse pitches of 60 mm and 42 mm, respectively. Saturated steam at a pressure of 2.455 bars enters the tubes, and a uniform tube outer surface temperature of 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 300 K and 7 m/s, what is the temperature of the air that leaves the array