What is thermal expansion, their types and equations

by

Thermal expansion: Thermal Expansion refers to the condition, if there is a change in the temperature of the body (either heated or cooled), there is a resultant change in length, width, and height, Volume of the body.

In this article, we will learn about the types of thermal expansion.

  • Linear Expansion
  • Volume Expansion
  • Area Expansion

Coefficient of linear thermal expansion: The coefficient of linear thermal expansion is defined as the ratio of the relative expansion of the body to the change in temperature. The coefficient of thermal expansion is the property that varies with temperature parameters (temperature-dependent property).

Please refer to the below article for the Linear expansion coefficient and volumetric expansion coefficient value for calculation purposes.

Types of thermal expansion (linear, Area, and Volume) with their equations are described below:

Linear Expansion: Linear Expansion refers to the change in the length of the body due to change in temperature. The operation may be heating or cooling.

The equation used for linear Expansion calculation is indicated below:

ΔL = αLᵢΔT                   (Linear Expansion)

Where,

ΔL = Change in Length of the body due to expansion

α = coefficient of length (Linear) expansion coefficient,

Lᵢ = Initial Length of the object or body

ΔT = Change in temperature of the body

Thus, the Final length after the thermal expansion is equal to the

Lբ = Lᵢ + ΔL

Try the linear thermal expansion tool

Lᵢ (Initial length of object)
α - linear expansion coefficient (refer below table)
m/m°C
Tᵢ (Initial Temperature of object)
°C
Tf (Final Temperature of object)
°C

Volume Expansion: Volume Expansion refers to the change in the volume of the body due to change in temperature.

The equation used for Volume or volumetric Expansion calculation is indicated below:

ΔV = βVᵢΔT                   (Volume Expansion)

Where,

ΔV = Change in Volume of the body due to expansion

β = Volume expansion coefficient,

Generally Volume expansion coefficient (β) is 3 times the length or Linear expansion coefficient (α). {I.e. β = 3α}.

Vᵢ = Initial Volume of the object or body

ΔT = Change in temperature of the body

Thus, the Final volume after the thermal expansion is equal to the

Vբ = Vᵢ + ΔV

Try the Volumetric thermal expansion tool

Vᵢ (Initial Volume of object)
m³
β (Volumetric expansion coefficient)
m³/m³°C
Tᵢ (Initial Temperature of object)
°C
Tf (Final Temperature of object)
°C

Area Expansion: Area Expansion refers to the change in the area of the body due to change in temperature.

The equation used for Area Expansion calculation is indicated below:

ΔA = αAᵢΔT                   (Area Expansion)

Where,

ΔA = Change in area of the body due to expansion

α = Area expansion coefficient,

Aᵢ = Initial area of the object or body

ΔT = Change in temperature of the body

Thus, the Final volume after the thermal expansion is equal to the

Aբ = Aᵢ + ΔA

Reference Table: Thermal Expansion coefficient at 20 °C.

Table: Thermal Expansion coefficient at 20 °C.

Leave a Comment