Answer to Question #223909 in Chemical Engineering for Lokika

Question

A chamber for heat curing large aluminium sheets, lacquered black on both sides, operates by passing the sheets vertically between two steel plates 150mm apart. One of the steel plates is at 300°C and the other plate is at 25°C. The emissivity of steel plates is 0.56 and the Stefan-Boltzmann constant is 5.67x108 W/(m²-K4). What is the heat transfer rate per unit area between the plates?

Answer 1

$Q_{1,2} = \dfrac{\sigma(T_1⁴-T_2⁴)}{(\dfrac1{\epsilon_1}+\dfrac1{\epsilon_2}-1)+(\dfrac1{\epsilon_{3,1}}+\dfrac1{\epsilon_{3,2}}-1)}$

$= \dfrac{5.67×10⁸(673⁴-298⁴)}{0+(\dfrac1{0.56}+\dfrac1{0.56}-1)}$

$= 4349.6\ J$