24-MCE-36

Experiment # 2
To Find the Coefficient of Linear Thermal Expansion of
Aluminium Due to Steam

2.1. Apparatus
 Aluminium Rod
 Digital Multi meter
 Dial Indicator
 Steam Generator

2.2. Parts
 Thermocouple
 Scale
 Screw clump
 Gauge holder
 Wood bas
 Hoses pipe
 Support barrier

2.3. Theory
Most material expand when heated through a temperature change (that does not produce
a change in phase). The added heat is increases the average amplitude of vibration of
atoms in the material, which increases the average separation between the atoms.
Coefficient of linear thermal expansion economically and accurately demonstrates the
coefficient of thermal expansion of different metals with an easy to read scale. This
apparatus contains 3 removable rods (aluminium, Copper & steel) each measuring is
71cm in original length.

Apparatus of Coefficient of linear thermal expansion

Figure 2.1
Linear Coefficient of Thermal Expansion

2.3.1. Definition
THE COEFFICIENT OF LINEAR thermal expansion (CTE) is a material property that
is indicative of the extent to which a material expands upon heating. In order to compare the
abilities of different solids to expand on heating it is necessary to refer to a table of coefficient
of linear thermal expansion as shown in Fig 2.1

2.3.2. Properties of Aluminium

⮚ Aluminum is solid, non-magnetic, non-lustrous, and silvery-white with a slight

bluish tint.

⮚ Aluminum has a face-centered cubic (FCC) structure that remains stable up to its
melting point.

⮚ The surface of aluminum can be highly reflective.

⮚ Commercially pure aluminum is soft but becomes stronger when alloyed and
tempered.

⮚ Aluminum has high ductility, making it very capable of being shaped or bent.

⮚ It also has high malleability, allowing it to be beaten into very thin sheets.

⮚ Aluminum has a thermal expansion coefficient of 22.4 × 10⁻⁶ per kelvin which is
greater than steel but less than zinc.

⮚ The melting point of commercially pure aluminum is approximately 1220°F, and its
boiling point is around 4478°F, though these values change when aluminum is alloyed.

2.3.3. Equation

∆𝐿
𝛼 = 𝑙×∆𝑇

Where,
α = coefficient of linear expansion
∆𝐿 = change in length
l =original length
∆T= change in temperature
2.4. Parts Explanation

2.4.1. Digital Multi-Meter

A digital multi meter is a test tool used to measure two or more electrical values-
principally voltage (volts), current (Amps), resistance (ohms). It is a standard diagnostic
tool for technicians in the electrical/electronic industries.

Digital Multi meter

Figure 2.2

2.4.2. Dial Indicator

Dial indicator are flexible devices which can be used in many different fields such as
industry and research, as well as for a wide variety of measurement works. Digital
indicators allow the user to view diverse parameters such as temperature, humidity,
vibration, normalized signals etc.

Dial indicator
Figure 2.3
2.4.3. Thermocouple
A thermocouple is an electrical device consisting of two dissimilar electrical conductor
forming electrical junctions at different temperatures. A thermocouple produces a
temperature-dependent voltage as a result of the thermocouple effect, and this voltage
can be interpreted to measure temperature

Thermocouple
Figure 2.4

2.4.4. Steam Generator

A steam generator is a form of low water-content boiler, similar to a flash steam boiler.
The usual construction is as a spiral coil of water-tube, arranged as a single, or mono-
tube coil. Circulation is once through and pumped under pressure as a forced-circulation
boiler.

Steam generator
Figure 2.5
2.4.5. Hose Tube
A hose is a long, flexible pipe made of rubber or plastic. Water is directed through a hose in
order to do things such as put out fires, clean cars, or water.

Hose Tube
Figure 2.6

2.5. Procedure
⮚ Firstly, measure the initial length of the aluminium rod from one to the other end
by using a meter rod.
⮚ Set up aluminium rod and attach the dial indicator to the aluminium rod and
rotate it to the zero.
⮚ Now attach the thermocouple to the rod and then attach its other end to the digital
multi meter. And measure the reading on the digital multi meter. We have to
calculate both the initial readings.
⮚ Now attach the rubber tubing to the rod of which the end is attached to the steam
generator.
⮚ Gradually, the temperature of the rod increases, calculate the increasing
temperature and length.
⮚ After getting the final reading, calculate the coefficient of linear thermal
expansion by using formula.
2.6. Observation and calculation

Material Initial Final Original Change Change in Coefficient

Temperature Temperature length in length Temperature of linear
T1 (K) T2 (K) L (cm) ∆𝐿 (cm) ∆𝑇 (𝐾) thermal
expansion
∆𝐿
𝛼=𝑙×∆𝑇 (K⁻¹)

Aluminium

2.6.1. Sample Calculation

2.7. Conculsion
It is concluded that thermal expansion refers to the increase in the
volume of a material as its temperature rises. It is expressed as the fractional change in length or
volume per unit of temperature change.

The linear thermal expansion coefficient (α) of aluminum is approximately:

{22.4 × 10⁻⁶ K⁻¹}

It is concluded that for every degree Kelvin (or Celsius) change in temperature, the length of
aluminum will change by approximately 22.4 × 10⁻⁶ K⁻¹.