question_answer

Upto the critical radius of insulation:

A) Added insulation increases heat loss.

B) Added insulation decreases heat loss.

C) Convection heat loss is less than conduction heat loss.

D) Heat flux decreases.

Correct Answer: C

Solution :

\[Q=\frac{2\pi L({{t}_{1}}-{{t}_{0}})}{\left[ \frac{In\,\left( \frac{{{r}_{2}}}{{{r}_{1}}} \right)}{k}+\frac{1}{{{h}_{0}}{{r}_{2}}} \right]}\] Conductive thermal resistance increases with increasing \[{{r}_{2}}\] and convective thermal resistance decreases with increasing\[{{r}_{2}}\]. \[Thus\,\,{{Q}_{convective}}<{{Q}_{conductive}}\]