1. Discuss the mechanism of thermal conduction in gases and solids.
2. Discuss the mechanism of heat convection.
3. Two infinite black plates at 500 and 100◦C exchange heat by radiation. Calculate
the heat-transfer rate per unit area. If another perfectly black plate is placed
between the 500 and 100◦C plates, by how much is the heat transfer reduced? What
is the temperature of the center plate?
4. One side of a plane wall is maintained at 100◦C, while the other side is exposed
to a convection environment having T =10◦C and h=10 W/m2 · ◦C. The wall has k
=1.6W/m· ◦C and is 40 cm thick. Calculate the heat-transfer rate through the wall.
5. What is meant by the term one-dimensional when applied to conduction
problems?
6. In the section illustrated in Figure below the surface 1-4-7 is insulated. The
convection heat transfer coefficient at surface 1-2-3 is 28 W/m2 · ◦C. The thermal
conductivity of the solid material is 5.2 W/m · ◦C. Using the numerical technique,
compute the temperatures at nodes 1, 2, 4, and 5.
7. Find the heat transfer per unit area through the composite wall in Figure P2-4.
Assume one-dimensional heat flow.
8.
8.
9. The composite strip in Figure below is exposed to the convection environment at
300◦C and h = 40 W/m2 · ◦C. The material properties are kA = 20 W/m · ◦C, kB =
1.2 W/m · ◦C, and kC = 0.5 W/m · ◦C. The strip is mounted on a plate maintained
at the constant temperature of 50◦C. Calculate the heat transfer from the strip to
plate per unit length of strip. Assume two-dimensional heat flow.
10. A certain building wall consists of 6.0 in of concrete [k =1.2 W/m· ◦C], 2.0 in
of fiberglass insulation, and 38 in of gypsum board [k =0.05 W/m· ◦C]. The inside
and outside convection coefficients are 2.0 and 7.0 Btu/h · ft2 · ◦F, respectively.
The outside air temperature is 20◦F, and the inside temperature is 72◦F. Calculate
the overall heat-transfer coefficient for the wall, the R value, and the heat loss per
unit.
11. Two pipes are buried in an insulating material having k =0.8 W/m.◦C. One pipe
is 10 cm in diameter and carries a hot fluid at 300 ◦C while the other pipe is 2.8 cm
in diameter and carries a cool fluid at 15◦C. The pipes are parallel and separated by
a distance of 12 cm on centers. Calculate the heat-transfer rate between the pipes
per meter of length.