Calculate the rate at which heat is being lost to the surrounding per unit length of an insulated steam pipe having the following dimensions and specifications: Innner diameter ofpipe=25mm, Thickness of pipe=2mm, Thickness of insulation=10mm, heat transfer coefficient on the inside surface=11.63W/sq.m.K; Temperature of steam=373K; temperature of surrounding3298K, thermal conductivity of pipe metal= 17.44W/mK; thermal conductivity of insulation= 0.58W/mK

Air at 25 ° C blows over the hot steel plate whose surface temperature is maintained at 200 ° C. The plates have dimensions of 50 cm x 50 cm and a thickness of 2.5 cm. The convection heat transfer coefficient on the upper surface is 25 W / (m² ° C). The thermal conductivity of steel is 45 W / (m ° C). Calculate the hourly heat loss from the plate surface. a. heat loss per hour = AnswerkJ. b. If the reverse side surface temperature is maintained, specify hourly heat loss = AnswerkJ.

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.]