Steam pipes are sometimes careless buried in the earth without insulation. Consider a 10-cm diameter pipe carrying steam at 150 degrees C buried at a depth of 18 cm to the surface of the pipe. the pipe length is 100m.
a.) assuming the earth thermal conductivity is 1.2 W/m K and the surface temperature is 15 degress C estimate the heat loss from the pipe.
b.) what is the heat loss if it is insulated with a layer of cellular glass 5 cm thick and thermal conductivity of 0.38 W/m C?