Answer:
Step-by-step explanation:
surface area of furnace = 6 x .6²
=2.16 m²
Rate of heat loss = k A ( θ₂ -θ₁ ) / t where k is coefficient of thermal conductivity , A is surface involved , θ₂ -θ₁ is temperature difference and t is thickness .
For fire clay thermal conductivity
= .05 W / m . K
.05 x 2.16 x ( 630 - 70 ) / .04
= 1512 W
= 1.5 kW .