Question

When Biot number tends to zero in the unsteady heat conduction, which one of the following is correct?

• A. Convection resistance is very small compared to conduction resistance in this problem.
• B. Internal temperature of solid will not be uniform in this problem.
• C. Lumped capacity analysis can be used
• D. Heisler chart is required for analysis of such problem.

Answer 1

The correct option is C Lumped capacity analysis can be used

Biot number

$\left(Bi\right)=\frac{conductiveresistanceinsidethesolidbody}{convectiveresistanceonthesolidsurface}$
$[\because Bi\to 0]$

$\therefore$ Conductive resistance inside the solid body $\approx$ 0 (Uniform temperature inside solid body)

$\therefore$ Lumped capacity analysis can be used.