Structural Analysis and Design of Foundations: A Comprehensive Handbook for S...
ย
Applications of Thermal Expansion
1. APPLICATIONS OF THERMAL EXPANSION
OBJECT
To explore various applications of
thermal expansion.
2. ๏ We shall take a look at the following
applications of thermal expansion
1. Consideration during constructions
2. The bimetallic strip
3. Thermometers
4. Engine Coolant
5. The Charlesโs Law
6. Jar lids and power lines
3. 1. CONSIDERATION DURING CONSTRUCTIONS
๏ The expansion or contraction of a materials
must be kept in mind while designing large
structures.
4. 2. THE BIMETALLIC STRIP
๏ A bimetallic strip can be used to control
thermostats and can also be used in fire
alarms.
5. 3. THERMOMETERS
๏ A thermometer is also constructed on the
principle of thermal expansion.
7. 5. THE CHARLESโS LAW
๏ Charles's law states that when pressure is
kept constant, there is a direct relationship
between volume and temperature.
8. 6. JAR LIDS AND POWER LINES
๏ It is an everyday experience that tight metal
lids are easy to remove after passage of hot
water over them.
๏ Sagging of electrical power lines is another
example of thermal expansion.
Editor's Notes
The most common and important application of thermal expansion is that the expansion and contraction of materials must be considered when designing large
structures, when using tape or chain to measure distances for land surveys, when designing
molds for casting hot material, and in other engineering applications when large changes in
dimension due to temperature are expected.
In the figure is shown bridge in which joints are made such that gaps are left between the joints so that thermal stress may not develop due to thermal expansion.
A bimetallic strip is one in which two different materials are joined together whose rates of expansion are different.
Therefore, when this strip is heated it bends. This allows us to use this strip in thermostats or fire alarms as switch.
This use of thermal expansion is also very important. A thermometer actually makes use of thermal expansion of the material inside its tube to measure the temperature.
Now this is basically an example or a problem car owners face due to thermal expansion. Suppose an engineโs radiator is completely filled with the coolant, now if the temperature of the radiator rises, it will cause the coolant inside to expand and as a result the coolant will overflow.
In the past, this produced a problem for car owners, becauseย car enginesย released the excess volume of coolant onto the ground, requiring periodic replacement of the fluid.
To avoid this problem, later-model cars, however, have an overflow container to collect fluid released as a result of volume expansion. As the engine cools down again, the container returns theย excess fluidย to the radiator.
