1. TUTORIAL 1
7/3/2016

2. QUESTION 1 (2-27)
A house wall may be approximated as two 1.2 cm layers of fiber insulating board, an 8.0 cm layer of loosely packed asbestos, and a 10 cm layer of common brick. Assuming convection heat transfer coefficient of 12 W/m2 .°C on both sides of the wall, calculate the overall heat transfer coefficient for this arrangement.

3. QUESTION 2 (2-31)
A 5-cm diameter steel pipe is covered with a 1-cm layer of insulating material having k= 0.22 W/m.°C followed by a 3- cm thick layer of another insulating material having k=0.06 W/m.°C. The entire assembly is exposed to a convection around surrounding condition of h= 60 W/m2.°C and T =15°C. The outside surface temperature of the steel pipe is 400 °C. Calculate the heat lost by the pipe-insulation assembly for a pipe length of 20 m. Express in Watts.

4. QUESTION 3 (2-62)
A wall consists of a 1-mm layer of copper, a 4-mm layer of 1% carbon steel, a 1-cm layer of asbestos sheet, and 10-cm of fiberglass blanket. Calculate a heat-transfer coefficient for this arrangement. If the two outside surfaces are at 10 and 150 °C, calculate each of the interface temperatures.

5. QUESTION 4 (2-34)
A plane wall 6.0 cm thick generates heat internally at the rate of 0.3 MW/m3 . One side of the wall is insulated, and the other side is exposed to an environment at 93 °C. The heat- transfer coefficient between the wall and the environment is 570 W/m2 . °C. The thermal conductivity of the wall is 21 W/m. °C. calculate the maximum temperature in the wall.