Investigating Thermal Conductivity: Overview of an Experiment

Abstract

Thermal conductivity is an important material property in industry and daily situations like knowing what to choose in cookware or the proper clothing worn to leave house. The thermal conductivity plays a significant role the colling of electronics equipment. This property is described in units of Watts per meter Kelvin and at steady sate can be calculated via a measurement of thermal resistance. Both thermal conductivity and thermal resistance will affect the amount of heat which passes through a system. In this experiment a simple set up will be employed to observe the change in heat flow. In this research a circular wooden frame has four different metals, copper, aluminum, brass, and iron. Which is fixed opposite each other with the strips meeting at the Centre. Thermal conductivity is not only affected by changes in thickness and orientation, but temperature also influences the overall magnitude. Because of the material temperature increase, the internal particle velocity increases and so does thermal conductivity. This increased velocity transfers heat with less resistance. This is thermal conductive essay in which will be discussed and analyzed the experiment data. 

Introduction

A circular wooden frame is a type of perspective of the experiment and its relevance to thermal conductivity and expansion of thermal conductivity material. Its use the bimetallic strip thermometer because it is made of metal and it is very good at controlling things. The principle behind a bimetallic strip thermometer relies on the fat that different metals expand at different rates as they warm up. The purpose of this experiment is to demonstrate the effect which varying thermal conductivity have on the heat flow through a given material. At the end this will provide a better understanding of both thermal conductivity and thermal resistance.

Thermal conductivity is an important parameter in representing the ability of strips to transfer heat. thermal conductivity of composite materials and revealed the influence of different factors on thermal conductivity. Temperature as an external condition has an important effect on thermal conductivity of strips. We as a group tested the strips thermal conductivities of four strips materials under various temperature and timing conditions. We timed the temperature after 20 sec, 40 sec and 60 sec. we found that the thermal conductivity of iron materials becomes larger with an increase in temperature. A circular wooden frame has four different metals strips are copper, aluminium, brass, and steel. The outer ends of the metal’s strips have small recesses for holding a small amount of wax and for each deposit of wax should be the same weight approx. 0.2 to 0.3g. by using the electronic precision scales and the melting of the wax can then be observed to compare heat conductivities between each metal. The table and the description of the development of this experiment shows the conclusion that the aluminium heats faster than copper. The fasten the aluminium, copper Brass and then Iron. The disadvantages of this experiment are that it is more time required and it will take about at least 20 to half and hours. And the advantages of this experiment are that the possibility to go without the thermosensitive films.

We used and measured each strip with a steel rule. It is now a common to measure temperature with electronics and the most common sensor is a thermistor. Practically we measured the temperature by using an infra-red temperature thermometer near the recess just to be done as accurate as possible.

We trained and learned before we started the science lab. We heated the strips at the central meeting point by using a methylated burner and used the results table to time and calculate for each element. Moreover, health and safety and timing management was important part of this experiment. We had to start the clock when the burner is lit and pointing at up to the central meeting point. After all we started the second temperature measurement that had to be the measurement of the length. After the strips had to be get cold the length of the iron had changed slightly. The experiment could be improved in terms of reliability if we repeat it and get the same or a similar answer repeatedly and the experiment is reliable if the same result we get when we repeat the experiment.

Materials are Used for Experiment Lab:

• The experiment Introduction booklet;
• Thermal conductivity apparatus (copper, aluminium, steel, Iron);
• Infrared thermometer;
• Methylated burner;
• Ruler;
• Stopwatch;
• Matches.

The Examination and Result

Thermal conductivity is a basic physical parameter used to characterize the heat transfer performance of materials. The heat conduction mechanism is different for different substances. The free flow of electrons in the solid and lattice vibration are the two main independent heat transfer mechanisms of solid. It is mainly the elastic wave (or lattice wave) that, produced from the lattice vibration at the place of higher temperature, drives the adjacent lattice vibration to transfer heat in inorganic nonmetal solid materials.

Conclusion

A thermal conductivity prediction model that considered the influence of temperature was established based on a modified thermal conductivity model of the dispersed phase volume. Also, the predicted results were verified using experimental data to prove its accuracy. It is important to note that the model is only applicable for the prediction of thermal conductivity under the condition of an outdoor ambient temperature, and the determination of the temperature correction coefficient was not unique. When a bi metallic strip such as a combination of either iron and brass or steel and copper. Brass or copper expands more on heating than iron or steel. And it also copper is usually considered to the best thermal conductivity on a thermal conductivity to price ratio.

References

• Understanding Thermal Conductivity | Advanced Thermal Solutions. [online] 
• Comparing Thermal Conductivity of Copper, Aluminium and Brass — Collection of Experiments. [online] 
• Thermal Conductivity of Solids and Metals. [online] 
• Thermal Conductivity Experiments – Resistance: Materials | Thermtest Inc. [online] 
• Thermal Conductivity Experiments. [online] 
• Physics Energy Transfer Wk4. [online]
• Thermal Conductivity (2 Experiments). [online] 
• Transfer of thermal energy. [online] 
• Heat Conductivity Ring - 4 Different Metals. [online]