Chapter 5, Problem 5.93P

Standards for firewalls may be based on their thermal response to a prescribed radiant heat flux. Consider a 0.25 -In-thickconcrete wall $\left(\rho =2300{\text{kg/m}}^{\text{3}},c=880\text{J/kg}\cdot \text{K,}k=1.4\text{W/m}\cdot \text{K}\right),$ which is at an initial temperature of $T_i=25°\text{C}$ and irradiated at one surface by lamps that provide a uniform heat flux of $q_x^n={10}^4{\text{W/m}}^{\text{2}}.$ The absorptivity of the surface to the irradiation is $a_s=\mathrm{1.0.}$ If building code requirements dictate that the temperatures of the irradiated and back surfaces must not exceed $325°\text{C}$ and $25°\text{C,}$ respectively, after 30 min of heating, will the requirements be met?