To heat milk flowing at 1.5 kg/s from 30 °C to 90 °C using a counterflow double-tube heat exchanger, the heating process will be done with a fluid at 160 °C with a mass flow rate of 2 kg/s. The inner tube is thin-walled with a diameter of 1.5 cm. The overall heat transfer coefficient of the heat exchanger is 600 W/m².K. Using the effectiveness-NTU method, calculate the required length of the heat exchanger to achieve the expected heating. (Cpmilk = 4.20 KJ/kg.K, Cpfluid = 4.31 KJ/kg.K)