Experiment 1
Thermal Expansion: Copper VS Aluminum
ENGL 21007
Writing for Engineering
Instructor: Suzanne Weyn
Author’s Name: Diego Julca
Experiment Contacted on: 04/01/2023
Report Submitted on: 04/20/2023
OBJECTIVES
- Provide extra information about thermal expansion of cooper vs aluminum.
- Make other students familiar with thermal expansion
- Run several tests run and observe the outcomes to come up with an answer to which metal is better to implement in a power grid copper or aluminum
BACKGROUND THEORY (INTRODUCTION)
Firstly, what is thermal expansion? Thermal expansion is when matter changes shape and volume in reaction to a shift in temperature. When the temperature of matter increases, its atoms or molecules gain kinetic energy, which causes them to vibrate and occupy more space. Thus, resulting in the expansion of the material.
Although thermal expansion is caused by temperature it has several factors, which include the material’s chemical composition, physical properties, and magnitude of temperature change. Different materials have different coefficients of thermal expansion, which tells us how much they expand or contract with temperature. For example, metals usually have a higher coefficient of thermal. This means that metals tend to expand more with temperature changes. To add on, the direction in which the thermal expansion occurs can also be anisotropic. This means that the expansion may be different in different directions.
Thermal expansion is used in different ways depending on the field, including engineering and construction. For example, it is used when designing a bridge and buildings that can resist temperature changes without becoming damaged. Another way it is used when designing engines, the main purpose for it is to use the expansion and contraction of the metal components to harness it and generate power.
However, thermal expansion can cause challenges in certain situations. For example, it can cause cracks and distortion in materials that are exposed to large temperature changes, including pipes or electrical wires. It could also create problems with precision instruments
that require tight tolerance. To overcome the challenges caused by thermal expansion, engineers often use techniques such as selecting materials with low coefficients of thermal expansion, they also design their own components out of multiple materials that must compensate for thermal expansion characteristics, or simply by using specialized coating or layers to protect against temperature changes.
EQUIPMENT and COMPONENTS USED
- Thermometer
- Steam generator
- Battery
- Voltmeter
- Micrometer
- Hollow metal tube
PROCEDURE
By simply putting a rod of copper or aluminum inside a hollow tube. Then using the steam generator to fill the hollow tube and raising the temperature of the rod. Finally, by attaching an electrical contact the ends of the rod. This can be used to check if the circuit is complete by reading, the voltage of the battery, if the circuit is interrupted the voltmeter will read zero. One of the ends of the rod is attached to a small micrometer. Allowing to record its setting when contact is made for a cool and hot rod, thus making the measure change of the rod’s length know for a known temperature change. By using the thermal expansion formula.
In which thermal expansion, is the particular length measurement, is the change in length and is the change in temperature.
- Record the length of the copper or aluminum rod. Make sure the rod and hollow tube is at room temperature.
- Use the micrometer whistle observing the voltmeter. When contact is barely made record the micrometer setting.
- Repeat step two several times
- By using the steam generator to create steam in the hollow tube and observe as the temperature of the rod increases.
- Record the temperature of the rod once it’s become stable for several minutes.
- Repeat the same procedure as shown in step two.
Figure 1. Copper, Ductile Iron, Carbon Steel, Stainless Steel and Aluminum Piping Materials – Temperature Expansion. Source: https://www.engineeringtoolbox.com/thermal-expansion-pipes-d_931.html
RESULTS
Table 1. Linear temperature expansion copper and aluminum tubes.
| Temperature Change (°F) | Linear Temperature Expansion (in/100 ft) | |
| Copper | Aluminum | |
| 0 | 0.0 | 0.0 |
| 10 | 0.1 | 0.2 |
| 20 | 0.2 | 0.3 |
| 40 | 0.5 | 0.6 |
| 50 | 0.6 | 0.8 |
| 60 | 0.7 | 1.0 |
| 70 | 0.8 | 1.1 |
| 80 | 0.9 | 1.3 |
| 90 | 1.1 | 1.4 |
| 100 | 1.2 | 1.9 |
| 140 | 1.6 | 2.2 |
| 200 | 2.4 | 3.2 |
| 240 | 2.8 | 3.8 |
| 300 | 3.5 | 4.8 |
| 340 | 4.0 | 5.4 |
| 400 | 4.7 | 6.3 |
As shown in Figure 1. As the temperature change goes up so does the thermal expansion. The table clearly shows the same results, copper starts at a much slower rate than aluminum when it comes to thermal expansion, thus making aluminum weaker material for heat resistance. Since copper has a lower thermal coefficient, it means that it is able to withstand more pressure and stress without creating any failure into any system.
Although, its shown that aluminum has a higher thermal coefficient, aluminum is still a popular material due to its lightweight and resistance to corrosion. Unlike copper that reacts to carbon dioxide and water, thus creating a coat of iconic blue green patina color, which most of the times its harmless in some scenario it could become a factor.
CONCLUSION
Lastly, both copper and aluminum have their own unique advantages, but in terms of thermal coefficient copper is superior to aluminum. Simply because it is able to withstand more pressure and stress making it perfect. The main purpose of this report was to analyze both metals with greater detail to allow for a better comparison between each other. However, copper is much better it’s a better conductor, has a lower thermal coefficient and its much cheaper. Making it the best material for a power grid.
