A cooling coil consists of a bank of aluminum (k = 237 W/m ∙ K) finned tubes having the core configuration of figure and an inner diameter of 13.8 mm. The tubes are installed in a plenum whose square cross section is 0.4 m on a side, thereby providing a frontal area of 0.16 m². Atmospheric air at 1.5 kg/s is in cross flow over the tubes, while saturated refrigerant-134a at 1 atm experiences evaporation in the tubes. If the air enters at 37°C and its exit temperature must not exceed 17°C, what is the minimum allowable number of tube rows in the flow direction? A convection coefficient of 5000 W/m² ∙ K is associated with evaporation in the tubes.