A stream of hydrocarbon (cp = 2.2 kJ/kgK) is cooled at a rate of 720 kg/h from 150°C to 40°C in the tube side of a double-pipe counter-flow heat exchanger. Water (cp = 4.18 kJ/kgK) enters the heat exchanger at 10°C at a rate of 540 kg/h. The outside diameter of the inner tube is 2.5 cm, and its length is 6.0 m. Calculate the overall heat transfer coefficient.

answer (2.31 kW/m2K)