Engine oil (raffinate) with a flow rate of 5 kg/s will be cooledfrom 60°C to 40°C by sea water at 20°C in a double-pipe heatexchanger. The water flows through the inner tube, whose outlet isheated to 30°C. The inner tube outside and inside diameters are do= 1.315 in. (= 0.0334 m) and di = 1.049 in. (= 0.02664 m),respectively. For the annulus, Do = 4.5 in. (= 0.1143 m) and Di =4.206 in. (= 0.10226 m). The length of the hairpin is fixed at 3 m.The wall temperature is 35°C. The number of the tubes in theannulus is 3. The thermal conductivity of the tube wall is 43 W/m ?K. Calculate: a. The heat transfer coefficient in the annulus b.The overall heat transfer coefficient c. The pressure drop in theannulus and inner tube (only straight sections will be considered)d. What is your decision as an engineer? How can you improve thedesign?
