Question

A steel pipe (k = 50 W/mK) of 100 mm ID and 110 mm
O.D is to be covered with two layers of insulation each
having thickness of 50 mm. The thermal conductivity
of first insulation material is 0.06 W/mK and that of the
second is 0.12 W/mK. Estimate heat loss per metre
length of pipe when temperature of inside tube surface
is 523 K and that of outer surface is 323 K. If order of
insulation is reversed, calculate change in heat loss
with all other conditions kept unchanged. Comment on
the results.​

Answer 1

Explanation:

A steel pipe (k = 50 W/mK) of 100 mm ID and 110 mm

O.D is to be covered with two layers of insulation each

having thickness of 50 mm. The thermal conductivity

of first insulation material is 0.06 W/mK and that of the

second is 0.12 W/mK. Estimate heat loss per metre

length of pipe when temperature of inside tube surface

is 523 K and that of outer surface is 323 K. If order of

insulation is reversed, calculate change in heat loss

with all other conditions kept unchanged. Comment on

the results.