We have two formulas to define the width and thickness of strip heating element.
t—thickness of strip (mm)
Kt—coefficient of thickness
b—width of strip
Kb—coefficient of width
P—capacity/power (W)
ω—surface area loading (W/cm2)
U—Voltage (V)
Ct—Temperature-Resistance Factor
Use following two formulas to calculate Kt and Kb:
n=b/t is the ratio of width and thickness
So Kb=n·Kt
You can find common used figure of Kt and Kb in the following table:
| n | 5 | 8 | 10 | 12 | 15 |
|---|---|---|---|---|---|
Kt |
0.119 | 0.0886 |
0.0769 |
0.0684 |
0.0593 |
| Kb | 0.593 | 0.708 |
0.769 |
0.821 |
0.889 |
For Example:
Material: Nichrome 80/20, Ct of Nichrome 80
Power: 10KW
Voltage: 220V
Surface area loading: 1.05W/cm2
Temperature: 1100℃
According to the formula above:
b=Kb×13
According to the table, choose b/t=8:
b=0.708×13=9.20
t=9.20÷8=1.15
so the size of strip is 9.20mm×1.15mm which is not regular size,
we can change b/t to b/t=10
then:
b=0.769×13=10
t=10÷10=1
The strip size is 1mm×10mm
