Answer Happy

-1 A composite tank wall with negligible curvature and total area 5 m² consists of an internal steel layer and an external insulator layer with thermal conductivities 50 and 0.04 W m-- K-?, respectively. The steel layer is 10 mm thick and is in contact with a process fluid, while the insulator is in contact with air. The temperature of the steel wall in contact with the process fluid is 200 °C. And the temperature of the insulator surface which is in contact with the air should not exceed 35 °C. The temperature on the internal steel wall is 199 °C, while the thermal resistance between the steel and the insulator layers is negligible. a) What is the minimum thickness of the insulator for the tank to be safe? [11] b) For the minimum thickness of the insulator layer calculate the rate of heat losses to the environment. [4]