3. A counter flow double pipe heat exchanger using super heated steam is used to heat water at the rate of 10500 kg/hr. The steam enters the heat exchanger at 180C and leaves at 130C. The inlet and exit temperature of water are 30C and 80C respectively. If the overall heat transfer coefficient from steam to water is 814 W/m2 K, calculate the heat transfer area. What would be the increase in area if the fluid flow were parallel?