rate of heat transfer from hot end to cold cold end $\alpha=\frac{k}{\rho c_p}$ it is seen in $\frac{\partial T}{\partial t} = \alpha \nabla^2 T$ for air $k$=0.025 W/mK $c_p$=1004 W/kg-K $\rho$ =1.2013 kg/m$^3$ at 18°C $\alpha$ = 2.705e-5 m$^2$/s $\alpha$ = 2.231e-4 ft$^2$/s $\alpha$ = 0.8033 ft$^2$/hr