GATE Mechanical Engineering (ME) 2017 Shift 2 Solved Paper

In a counter-flow heat exchanger, water is heated at the rate of 1.5 kg/s from 40° C to 80° C and oil entering at 120°C and leaving 60°C. The specific heats of water and oil are 4.2 kJ/kg-K and 2 kJ/kg-K, respectively. The overall heat transfer coefficient is 400 W/m².K. The required heat transfer surface area (in m²) is