Answer:
Q=112.31 W/m
Explanation:
Given that
Oil temperature Tâ= 150°C
Air  temperature Tâ= 20°C
Heat transfer coefficient h= 11 W/m²K
Diameter ,d= 25 mm
The heat loss given as
Q= h A ÎT
A= ÏdL
Q= h ( ÏdL)ÎT
Heat loss per unit length
Q= h ( Ïd)ÎT
Now by putting the values
[tex]Q=11\times \pi \times 0.025\times (150 - 20)\ W/m[/tex]
Q=112.31 W/m
Therefore heat loos will be 112.31 W/m