Question

A mountain climber wears a goose down jacket 3.4cm thick with total surface area 1.2m². The temperature at the surface of the clothing is -18^oC and at the skin is 34 ^oC.

Part A

Determine the rate of heat flow by conduction through the jacket assuming it is dry and the thermal conductivity k is that of down.

Q/t= ______W

Part B

Determine the rate of heat flow by conduction through the jacket assuming the jacket is wet, so k is that of water and the jacket has matted to 0.44cm thickness.

Q/t= ______W

Answer 1

The rate of heat flow by conduction through the jacket assuming it is dry is

Q/t = kA del T /L         ( k is thermal condictivity )

     = ( 0.025 ) ( 1.2 m^2) ( 34 C - ( -18 C) /0.034 m

    = 45.88 W

the rate of heat flow by conduction through the jacket assuming the jacket is wet,

Q/t = kA del T /L         ( k is thermal condictivity )

     = ( 0.56) ( 1.2 m^2) ( 34 C - ( -18 C) /0.0044 m

    = 7.94 * 10 ^3W