Insulating material is used to reduce heat loss from the heating furnace walls to the room. The surface temperature of the insulating material is 100 ° C and the other surfaces 25 ° C. Allowable heat loss up to 160 W / m2 from the wall. If the thermal conductivity of the insulation material is 0.05 W / (m ° C), calculate the required thickness of insulation. insulation thickness = Answer cm

A furnace of 70- by 60- by 90-cm inside dimensions is constructed of a material having athermal conductivity of 1.05 kJ/kg °C. The wall thickness is 15 cm. The inner and outersurface temperatures are 500 and 100 °C, respectively. Calculate the heat loss through thefurnace wall.

A plane wall has a thermal conductivity of 20 W/(m-K) and generates heat at 0.5 MW/m3. The wall is 0.2 meters thick and is perfectly insulated on one side. The other side is exposed to fluid at 100 °C. The convective heat transfer coefficient between the wall and the fluid is 400 W/(m2 K). Determine the maximum temperature in the wall.

The exhaust duct from a heater has an inside diameter of 114.3 mm with ceramic walls 6.4 mm thick. The average k=1.52 W/m· K. Outside this wall, an insulation or rock wool 102 mm thick is installed. The thermal conductivity of the rock wool is k= 0.046+ 1.56 x 104 T°C (W/m · K). The inside surface * = temperature of the ceramic is T1 = 588.7 K, and the outside surface temperature of the insulation is 311 K. Calculate the heat loss for 1.5 m of duct and the interface temperature T2 between the ceramic and the insulation. [Hint: The correct value of km for the insulation is that evaluated at the mean temperature of (T2 + T3)/2. Hence, for the first trial assume a mean temperature of, say, 448 K. Then calculate the heat loss and T2 Using this new T2, calculate a new mean temperature and proceed as before.]