Design Calculations For The Heating Element

Designing a Tape Element

 

Here is how the design calculations for the heating element are done:

1.  To calculate the tape size and length required for a specific heating element in heater, operating at a maximum temperature of °C, the total resistance of the element at operating temperature (Rt) will be:

R_t = V² / W

Where:

·         V = Voltage (Volts)

·         W = Power (Watts)

2.  Using specific heating element alloy wire, find the Temperature Resistance Factor at °C operating temperature as F thus the total resistance of the element at 20°C (R) will be:

R_t = R_t / F

Where:

·         R_t = Element Resistance at Operating Temperature (ohms)

·         F = Temperature-Resistance Factor

3.  Knowing the dimensions of the heater, the length of the tape that may be wound round it may be estimated. Thus, the resistance required per metre of tape will be:

A = R / L

Where:

·         A = Resistance per meter (ohms/m)

·         R = Element Resistance at 20°C (ohms)

·         L = Total Element Length (m)

4.  Find a heating element tape of standard size of b mm x t mm having a standard resistance per metre of stock size which is near to A ohms/m.

Where:

·         b = Tape width (mm)

·         t = Tape thickness (mm)

5.  To verify the actual tape length (L)

L = R / A

Where:

·         L = Total Element Length (m)

·         R = Element Resistance at 20°C (ohms)

·         A = Resistance per meter (ohms/m)

A change in tape length may mean altering the pitch of the tape to achieve the total resistance value required.

6.  To verify the surface area loading (S):

S = W / 20 x (b + t) x L

Where:

·         W = Power (Watts)

·         b = Tape width (mm)

·         t = Tape thickness (mm)

·         L = Total Element Length (m)

 

Reference: www.heating-element-alloy.com/heating_element_design_factors.html