A process industry employs a counter-flow heat exchanger to cool 0.8 kg/s of oil (CP = 2.5 kJ/kg K) from 120°C to 40°C by the use of water entering at 20°C. The overall heat transfer coefficient is estimated to be 1600 W/m2K. It is assumed that the exit temperature of water will not exceed 80°C. Using NTU method and taking NTU = 4 in this case, calculate the following:
(i) Mass flow rate of water.
(ii) Surface area required.
(iii) Effectiveness of heat exchanger.