Water at 50°C flows in a 2.5 cm diameter tube with a heat transfer coefficient (h;). The tube has a wall thickness of 0.
Posted: Thu May 05, 2022 5:48 pm
Water at 50°C flows in a 2.5 cm diameter tube with a heat transfer coefficient (h;). The tube has a wall thickness of 0.8 mm with a thermal conductivity of 16 W/mK. The external surface of the tube loses heat by free convection to surrounding air at 20°C with a heat transfer coefficient (ho). Based on the data given below, determine: (i) the heat transfer coefficients h; and ho; (ii) the overall heat transfer coefficient; and (iii) the heat loss per unit length to surrounding air. The following data can be used for your calculation. All symbols have their usual meanings. Water in tube: Nu = 135; k = 0.644 W/mK Surrounding air: Nu = 7; k= 0.02625 W/mK The following equation for estimating the thermal resistance of the tube wall may be used for your calculation. R In (ro/ri) 2πkL