A tube bank employs tubes that are 1.30 cm in outside diameter at S_T = S_L = 1.625 cm. There are eight rows of tubes, which are held at a surface temperature of 90°C. Air, at atmospheric pressure and a bulk temperature 27°C, flows normal to the tubes with a free-stream velocity of 1.25 m/s. The tube bank is eight rows deep, and the tubes are 1.8 m long. Estimate the heat-transfer coefficient.