4. (25 points) We have a shell and tube heat exchanger with 100 tubes as one shell pass and two tube passes. The shell side heat transfer coefficient is 200 W/ mK and resistance of walls can be neglected. The oil is sent to the tubes of the exchanger at flow rate of 120 C and leaves at 50 The water is sent to the shell side at 20 C and exits at 40C. Property Conductivity (W/m K) Density (kg/m) Heat capacity (kJ/kg K) Kinematic viscosity (m/s) Oil 0.15 900 2.0 2x10-5 a. The heat transfer coefficient on the tube side. b. The overall heat transfer coefficient if there is a fouling layer with Rf of 0.0004 K/W. The heat transfer area required. C