Answer Happy

Calculate the overall heat transfer coefficient and the mean temperature of the tank wall in which is the water steam at temperature 142°C. At the outside of tank of 300 mm diameter is the air at temperature 25°C. The heat transfer coefficient from the steam side is 12000 W/(m²K) and from the air side is 1500 W/(m²K). The tank wall has 5 mm thickness (thermal conductivity 43 W/(m K)) and is insulated from outside by the mineral wool of thickness 30 mm (thermal conductivity 0.35 W/(mK)) and polystyrene of thickness 20 mm (thermal conductivity 0.5 W/(m K). Assume, that the tank is coated inside by a 1 mm layer of pollutions (thermal conductivity 1.2 W/(m K)).