Steam condition on the outer surface of a thin-walled circular tube of 50 mm. diameter and 6 m. length maintains a unifrom surface temperature of 100 c water flows through the tube at a rate of m = 0.25 kg/s, and its inlet and outlet temperatures are Tm,i = 15 c and Tm,o = 57 c. What is the average convection coefficient associated with the water flow?