Heat Transfer
Moving atoms and molecules create kinetic energy that can be stored within a material. The stored energy is called heat. Most people will refer to an object's temperature as being either hot or cold; when in reality temperature is a measurement of the amount of kinetic energy (movement) the atoms are producing (Woodford, 2018). When atoms move they bump into or collide with other atoms. The faster the atoms move; the more collisions occur and in return create more heat to be stored in the material. Heat can be transferred form one material into another material. Heat transfer occurs in three different ways; convection, conduction, and radiation. Convection occurs in liquid and gases by warmer atoms being less dense so they rise up and then sink once the atom cools. Conduction occurs when materials are in direct contact with each other. Conduction happens best when two solids are in direct contact with each other, but can also take place in liquids and gases. Radiation transfers heat through gases or empty space. Each type of heat transfer is essentially trying to achieve the same thing; create balance between the amount of heat within two or more materials (objects).
Materials and Design
The purpose of an insulator is to minimize the passage of heat and to limit rapid temperature changes. Insulators have a wide range of applications and are composed of different materials serving a specific purpose. For example, corrugated cardboard is used as a sleeve for hot beverage cups to protect consumers hands from heat transfer while holding the hot beverage. Fiberglass is used as a building insulator inside of the walls and ceilings to slow the loss or gain of heat depending on the season (Pisupati, 2018).
For this experiment I selected four different materials (plastic, closed cell styrofoam, heavy duty tin foil, and cardboard) to test which material has the greatest resistance to heat loss. The materials I chose are readily available and had a variety of textures and chemical compositions. Each material was placed on top of a coffee mug and held in place with a rubber band for 30 minutes. Since I only had 3 identical mugs to use, I needed to perform two separate trials to test all four materials. Because of this I used one of the mugs each time as a control group (no cover was placed on this mug). This also allowed me to record the starting temperature of the hot water (72 C). Each test group mug; was identical size, shape, and material; was tested in the same location; tested at the same time of day (air temperature was 28 C); was filled with 1 cup of hot water (See appendix A). Test group mugs were filled, immediately secured the test material on top of each mug, and started a 30 minute timer. After the 30 minutes the water temperature inside of each mug was recorded by slightly moving the material to create a small enough opening to place the thermometer into the water (See appendix B).
My prediction was that the closed cell styrofoam would be the best insulator.
Results
The experiment was able to produce reliable results to connect to the course content and real world.
I was surprised to see that tin foil turn out to the best insulator I tested, smallest temperature change or held the temperature the closest to the starting temperature, during the experiment. Tin foil is made from aluminum, which is the third best conductor (Tillery, Enger, & Ross, 2019). One possible explanation for tin foil holding the warmest temperature (16 C temperature change in 30 minutes) could be due to the reflective characteristics that tin foil possesses. The tin foil reflected the radiation heat waves back into the water to help keep the water at a warmer temperature. This is unlike the other materials which absorbed some of the heat through conduction. Cardboard was the second best material for insulating the water temperature with only an 18 C degree change. My prediction was that the closed cell styrofoam would have been the best insulator. This prediction was generated from the idea that some new homes are being insulated with closed cell spray foam to increase the insulation R-value. Closed cell spray foam has twice the R-value of fiberglass batt insulation. The higher the R-value the more thermal resistant the insulation is to conductive heat transfer (Tigerfoam, 2018).
References
Neese, B. (2019). Three Types of Heat Transfers. Retrieved September 29, 2019, from https:// sciencing.com/three-types-heat-transfers-5422262.html.
Pisupati, S. (2018). Mechanisms of Heat Loss or Transfer. Retrieved September 29, 2019, from https://www.e-education.psu.edu/egee102/node/2053.
TeachEngineering. (2019). Stop Heat from Escaping: Testing Insulation Materials. Retrieved September 29, 2019, from https://www.teachengineering.org/activities/view/cub_energy2_lesson02_activity2.
Tillery, B. W., Enger, E. D., & Ross, F. C. (2019). Integrated science (7th ed.). New York, NY: McGraw-Hill.
Woodford, C. (2018). Heat - A simple introduction to the science of heat energy. Retrieved September 29, 2019, from https://www.explainthatstuff.com/heat.html.
Understanding R-Values. (2018). Retrieved September 29, 2019, from https://tigerfoam.com/sprayfoaminsulation/inch-by-inch-an-in-depth-look-at-r-values/.
