3. A 2-shell passes and 4-ube passes HX is used to heat glycerin from 20C to 40C by hot water which enters the thin-walled 2-cm diameter tubes at 90 C and leaves at 50 C. The total length of the tubes in HX is 50 m. The convection heat transfer coefficient is 25 W/m K on the shell side and 150 W/mKon tube side. Determine the heat transfer rate after fouling with a fouling factor of 0.0008 m2K/W occurs on the outer surface of the tubes? (50 points)