It is proposed to cool oil in a counter-current, concentric tube heat exchanger composed of a thin-walled inner tube of 0.02 m diameter carrying oil and thin-walled, perfectly insulated outer tube of 0.05 m diameter carrying water. The oil flow rate is 50.0 kg min- and it has to be cooled from 90C to 40C using 60 kg min- water at 20C. (i) Calculate the heat load and the outlet water temperature. (ii) Can the method of main resistance be used to determine the length of this heat exchanger? Heat transfer coefficients can be calculated from appropriate correlations shown below in the data section for this question. (iii) Determine the length required for the heat exchanger. Comment on the practicality of this length. (iv) Calculate the convective heat losses to the surrounding air at 20C after the insulation is removed. You can assume that the temperature of the outer surface of the pipe is the same as the temperature of the water.