Heat Transfer Basics Quiz

Which one of the following is not a property of the material ?

What is the order of magnitude of thermal conductivity for (a) metals (b) solid
insulating materials (c) liquids (d) gases?

What is the order of magnitude for the convection heat transfer coefficient in free
convection? Forced convection? Boiling?

A solid aluminium sphere of emissivity ε is initially at an elevated temperature and is cooled
by placing it in chamber. The walls of the chamber are maintained at a lower temperature and
a cold gas is circulated through the chamber. Obtain an equation that could be used to predict
the variation of the aluminium temperature with time during the cooling process. Do not
attempt to solve.

Problem : In an orbiting space station, an electronic package is housed in a compartment
having surface area As = 1m2 which is exposed to space. Under normal operating conditions,
the electronics dissipate 1 kW, all of which must be transferred from the exposed surface to
space. If the surface emissivity is 1.0 and the surface is not exposed to the sun, what is its
steady- state temperature? If the surface is exposed to a solar flux of 750W/m2 and its
absorptivity to solar radiation is 0.25, what is its steady –state temperature?

Find: surface temperature without and with incident solar radiation.