- #1
blazerman
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Homework Statement
A Heating Element rated 1400Watt Supply 220V
Current : 6.36 Amperes
Resistance = 34.57 Ohms
Area to be heated L X B X H = 4inches X 4inches X 9inches
From Temperature 35 Deg.C to 1000 Deg.C
All under standard/normal pressure
2. Relevant Question
How long would it take to heat from 35 Deg.C to 1000 Deg.C
The Attempt at a Solution
Joules = Mass(Kg) X Heat Capacity on kJ/Kg.DegC X Delta T
Inch(s) -> to Meter(s)
4 -> 0.1016
4 -> 0.1016
9 -> 0.2286
Therefore Volume of Air = 0.00235974 Mt^3
Density of Air @ 35. Deg C = 1.1455 Kg/Mt^3
Amount of Air @ 35. Deg C = 0.00235974 X 1.1455 = 0.0027031 Kg
Heat Capacity of Air = 1.06 kJ/kg Deg.C
Delta T = 1000 - 35 = 965 Deg.C
Joules to be consumed = 0.0027031 x 1.06 X 965 = 2.76499 kJ = 2764.99 Joules
Joules = Current^2 X resistance X time(Seconds)
Then 27466.99 = (6.36)^2 X 34.57 X T(Seconds)
or, T = 1.97 Seconds (Something is wrong)
Time=? (to raise the temperature from 35 Deg.C to 1000 Deg.C)
The Attempt at a Solution
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