Question

A pipe of 0.3 m outer diameter at a temperature of 160°C is insulated with a material having a thermal conductivity of k = 0.055 (1 + 2.8 × 10–3T) W/mK where T is in °C. The outside surface temperature is 40°C. Determine the heat flow/m length and the temperature at the mid radius

Answer 1

Q=0.95 W/m

Step-by-step explanation:

Given that

Outer diameter = 0.3 m

Thermal conductivity of material

`K= 0.055(1+2.8* 10^(-3)T)(W)/(mK)`

So the mean conductivity

`K_m=0.055\left ( 1+2.8* 10^(-3)T_m \right )`

`T_m=(160+273+40+273)/(2)`

`T_m=373 K`

`K_m=0.055\left ( 1+2.8* 10^(-3)* 373 \right )`

`K_m=0.112 (W)/(mK)`

So heat conduction through cylinder

`Q=kA(\Delta T)/(L)`

`Q=0.112* \pi * 0.15^2* 120`

Q=0.95 W/m