Question

A large plate of thickness 2L is at a uniform temperature of $T_i={200}^{0}C,$ when it is suddenly quenched by dipping it in a liquid bath of temperature $T_{\infty }={20}^{0}C$. If heat transfer coefficient (h) =100 $W/m^2-K$ and thermal conductivity (k)=50 W/m.K. What is the heat flux (kW) at x =L and time (t) =0?

• A. 0
• B. 9
• C. 36
• D. 18

Answer 1

The correct option is A 0

Due to symmetry, at $x=L,\frac{\partial T}{\partial X}=0$

Heat flux$\left(q\right)=-k{\frac{\partial T}{\partial X}|}_{x=L}=-50\times 0$

$\Rightarrow$ q = 0