A tube bank uses an aligned arrangement of 10-mm-diameter tubes with ST = SL = 20 mm. There are 10 rows of tubes with 50 tubes in each row. Consider an application for which cold water flows through the tubes, maintaining the outer surface temperature at 27C, while flue gases at 427C and a velocity of 5 m/s are in cross flow over the tubes. The properties of the flue gas may be approximated as those of atmospheric air at 427C. What is the total rate of heat transfer per unit length of the tubes in the bank?