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Design of Heating Element

The document discusses the design of a heating element. It provides equations to calculate the length and diameter of a circular heating element wire based on the input voltage and power. The heating power produced by the element is equal to the electrical power input. This can be used to relate the voltage, resistivity of the wire material, and the length and diameter of the wire. Specifically, equations 3 and 4 allow calculating the length and diameter respectively given the voltage and power.

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Sandip Mondal
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1K views3 pages

Design of Heating Element

The document discusses the design of a heating element. It provides equations to calculate the length and diameter of a circular heating element wire based on the input voltage and power. The heating power produced by the element is equal to the electrical power input. This can be used to relate the voltage, resistivity of the wire material, and the length and diameter of the wire. Specifically, equations 3 and 4 allow calculating the length and diameter respectively given the voltage and power.

Uploaded by

Sandip Mondal
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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Design of Heating Element

The device which receives electrical energy as input and converts it into the heat energy is
known as a heating element.

The wire employed for the heating element may be circular or rectangular. By determining the
electrical input and its voltage, the size (or diameter) and length of the wire required as the
heating element to produce the given temperature can be calculated.

Design of Heating Element


Consider the heating element is in the circular shape. Therefore, the length and diameter of
the heating element can be calculated as follows −

According to the Stefan's law, the heat dissipated is given by,

4 4
T1 T2
2
H = 5.72 Ke[( ) − ( ) ] Watt/ m ⋅ ⋅ ⋅ (1)
100 100

2
V
Input electric power,P =
R

Where,

V is the supply voltage, and

R is the resistance of heating element

2
ρl πd
∵ R = and a =
a 4

Where, 'ρ' is the resistivity of the wire material, 'l' is the length of the wire and 'd' is the
diameter of the circular wire.
2 2 2
V a πd V
∴ P = =
ρl 4ρl

If

2
Surface area of element = π × d × l m

Thus, the heat input per m2 of the surface area is

2 2 2
πd V 1 V d
2
Heat input per m = × = ⋅ ⋅ ⋅ (2)
2
4ρl π × d × l 4ρl

The temperature of the heating element at the initial stage will raise gradually but after
certain time it becomes constant. At this instant, the heat dissipated from the surface of the
heating element is equal to input of the electrical energy. Therefore, equating eqns. (1) and
(2), we get,

2
V d
H =
2
4ρl

2 2
l V
⇒ = ⋅ ⋅ ⋅ (3)
d 4ρH

2
V ρl
∵ P = and R =
R a

2
V ρl
∴ = R =
2
P (πd /4)

2
V 4ρl
⇒ =
2
P πd
2
1 πV
∴ = ⋅ ⋅ ⋅ (4)
2
d 4ρP

Hence, for the given voltage and power, the length and diameter of the heating element can
be determined by using the eqns. (3) and (4).

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