A shell and tube counter flow heat exchanger is used to heat liquid water from 50 C to 70 C by oil that flows through the tube side. The mass flow rate of water is 2 kg/s. The specific heat of the oil is 1.5 kJ/kg.K, and the water is 4.2 kJ/kg.K. The oil enters at 110 C and leaves at 70 C. The overall heat transfer coefficient is 350 W/m?K. Calculate the mass flow rate (kg/s) of the oil and the heat exchanger area required for the process.