A double layered wall has outer layer ${}_{\text{o}\text{u}\text{t}\text{e}\text{r}}=0\mathrm{.}85,$ and inner layer ${}_{\text{i}\text{n}\text{n}\text{e}\text{r}}=0\mathrm{.}46.$ The wall temperature is $110F$ and the temperature inside the room surroundings is $60F.$

Compute:

a$)$ the radiant heat flux $"$as is$"$

b$)$ the radiant heat flux when an aluminum radiation shield having $$ shield $=0\mathrm{.}05$ is used.

c$)\%$ reduction in heat flux when using the shield

ANS.

NO SHIELD: q$/$A $=23\mathrm{.}64$ BTU$/$hr$-$ft$^2$

WITH SHIELD: $\frac{q}{A}=1\mathrm{.}36BT\frac{U}{h}r=f{t}^{{?}^{?}}2$

$\%$ REDUCTION $=94\%$