Question

A piece of bread can be modeled as a gray surface e = 0.9 having dimensions of 10 cm x 10 cm x 1 cm. A slot in an electric toaster has a width of 4 cm, leaving a gap of 1.5 cm between the face of the bread and the heating elements of the toaster. Assuming the heating elements are modeled as an equal-area gray surface (e = 0.95) coplanar to the bread at a temperature of 1200 K, determine the radiation heat transfer to the bread (W) assuming all radiation not directly incident on the bread is reflected out of the cavity.

man S SURA Line of symmetry

Answer 1

Giveni Co= 0.9 A = 0.1X Ool= 0.01 m² en=0.95 Th= 1200k Assumption Temperature of bread, To 298 K gray body Radatton beat transfer b/w 2 (element & bread) AT" To ti stefen-Boltzman l-Eh Constant + I-Eb En Є, a = 5.67 X10-8 W/m²K 15.69X100 x 200 x (1800" - 2929) 1-0.9 y I-0.95 + 0.95 0.9 11 1171.26 0.053 t Oolll 7153.05 W) [qi