Question

It is planned to insulated the shell of a heat exchanger. The outside diameter of the shell is $30cm,$ its outer surface temperature is at ${280}^{\circ }C$ and it may be assumed to be remains constant even after applying insulation on the shell.

If the outside surface heat transfer coefficient is 2, what is the maximum thermal conductivity of insulating material for effectively reducing heat transfer from shell

• A. 0.3
• B. 0.24
• C. 1.2
• D. 2.4

Answer 1

The correct option is A 0.3

$\frac{k_{ins}}{h}=r_c{k}_{ins}=r_c\times h=0.15\times 2=0.3W/mK$