Inside the chamber is a horizontal long resistor wire having a diameter of 2.5 mm. The...
Inside the chamber is a horizontal long resistor wire having a diameter of 2.5 mm. The chamber the internal surfaces have a constant temperature of 280 K and the temperature of the air inside the chamber is 300 K. The emissivity of the outer surface of the resistor is ε = 0.3 and the specific resistance R '= 2.162 Ω/ m. The resistance the maximum surface temperature must not exceed 1500 K. Calculate the current flowing through the resistor maximum value if heat transfer from the resistor surface occurs
a) by free convection and radiation
b) forced convection (air velocity 20 m / s) and radiation.
Homework Answers
Answer :
Given that
diameter of 2.5 mm
constant temperature of 280 K
the chamber is 300 K
the resistor is 
=0.3
specific resistance is R' =2.162 
/m
the maximum surface temperature must not exceed 1500 K
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