A radiative heater consists of a bank of ceramic tubes with internal heating elements. The tubes art of diameter D = 20 mm and are separated by a distance s = 50 mm . A reradiating surface is positioned behind the heating tubes as shown in the schematic. Determine the net radiative heat flux to the heated material when the heating tubes ( ε h = 0.87 ) are maintained at 1000 K. The heated material ( ε m = 0.26 ) is at a temperature of 500 K.
A radiative heater consists of a bank of ceramic tubes with internal heating elements. The tubes art of diameter D = 20 mm and are separated by a distance s = 50 mm . A reradiating surface is positioned behind the heating tubes as shown in the schematic. Determine the net radiative heat flux to the heated material when the heating tubes ( ε h = 0.87 ) are maintained at 1000 K. The heated material ( ε m = 0.26 ) is at a temperature of 500 K.
Solution Summary: The author explains the net radiative heat flux to the heated material when the heating tubes. The expression for radiation heat transfer is given by Q_1=-
A radiative heater consists of a bank of ceramic tubes with internal heating elements. The tubes art of diameter
D
=
20
mm
and are separated by a distance
s
=
50
mm
. A reradiating surface is positioned behind the heating tubes as shown in the schematic. Determine the net radiative heat flux to the heated material when the heating tubes
(
ε
h
=
0.87
)
are maintained at 1000 K. The heated material
(
ε
m
=
0.26
)
is at a temperature of 500 K.
A short brass cyclinder (denisty=8530 kg/m^3, cp=0.389 kJ/kgK, k=110 W/mK, and alpha=3.39*10^-5 m^2/s) of diameter 4 cm and height 20 cm is initially at uniform temperature of 150 degrees C. The cylinder is now placed in atmospheric air at 20 degrees C, where heat transfer takes place by convection with a heat transfer coefficent of 40 W/m^2K. Calculate (a) the center temp of the cylinder, (b) the center temp of the top surface of the cylinder, and (c) the total heat transfer from the cylinder 15 min after the start of the cooling. Solve this problem using the analytical one term approximation method.
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