Question

A sugar solution (? = 1080 kg/m³, cp = 3601 J/kg ? K, kf = 0.5764 W/m ? K, ? = 1.3 × 10–3 N ? s/m²) flows at rate of 60,000 kg/hr and is to be heated from 25°C to 50°C. Water at 95°C is available at a flow rate of 75,000 kg/hr (cp = 4004 J/kg ? K). It is proposed to use a one shell pass and two tubes pass shell-and-tube heat exchanger containing 3/4 in. OD, 16 BWG tubes. The velocity of the sugar solution through the tube is 1.5 m/s, and the length of the heat exchanger should not be more than 3 m because of the space limitations. Assume that the shell-side heat transfer coefficient is 700 W/m² ? K. Thermal conductivity of the tube material is 52 W/m ? K. a. Calculate the number of tubes and the tube-side (sugar) heat transfer coefficient. b. Calculate the overall heat transfer coefficient. c. Calculate the length of this heat exchanger. Is this heat exchanger acceptable?

Answer 1