Prototype Testing Procedures:

Prototype Organizer #1:

 

Prototype Organizer #2:

  

Prototype Organizer #3:

Temperature vs Time Prototypes Graph:

Final Product:

Materials:

• 1 glass jar (0.8W/m.k)
• 1 plastic lid (0.03W/m.k)
• 39.86 sq in of foam insulation (0.03W/m.k)
• 1/6 sheet of paper (0.05W/m.k)
• 4 dimes of glue (0.14W/m.k)
• 2 googly eyes (0.03W/m.k)

Results:

Total Cost = $3.00

Starting Temperature = 86.1°C

Final Temperature = 62.0°C

Change in Temperature = –24.1°C

Explanation and Justification:

The materials and ideas used to create this thermos were thoughtfully chosen. First off, we had to take into consideration thermal energy, this being the idea of a total amount of molecules in a specific amount of material and how these molecules interact. The faster the mocleules either vibrate, rotate, or translate the more friction there will be which results in more thermal enegery allowing there to be a higher temperature because of the average movement of kinetic energy of molecules. Therefore, with this idea in mind we worked together to find materials with a low thermal conductivity to be able to maintain this kinetic energy in the thermos. We decided to use foam insulation as our primary defense against heat loss as it has a low thermal conductivity of 0.03W/m.k – the lower the thermal conductivity the better it is as an insulator. As a result the foam was able to insulate the glass jar which also had a relatively small thermal conductivity of 0.8W/m.k. With both products and the plastic lid (0.03W/m.k – thermal conductivity) we were able to insulate the water and keep it’s heat. After learning from our first prototype we knew we needed to cover the top and bottom of the thermos due to conduction, convection, and radiation. As we do not want to lose heat, choosing to add insulation to the bottom of the glass jar elimated direct contact to a possibly colder surface which helped minimize heat loss. In addition, cold air/water is more dense meaning it would be at the bottom of the jar which is why we insultated the bottom even more to keep this needed heat inside. Also, by adding foam insulation to the top, we were eliminating further heat loss of the water’s heat through convection, since hot air/water is less dense allwoing it to rise. On the other hand, we weren’t able to minimize additionnal heat loss due to radiation because our budget would not allow it; however, if it had been possible, we would have added a refelctive layer on the inside so the heat wouldn’t have been able to radiate out as easily. While conducting our final experiment with the thermos we also took into account the law of conservation of energy. With this in mind we decided to warm up our thermos ahead of time to ensure we minimized as much heat loss as possible, as heat travels from hot to cold showing that the boiling water’s heat could travel to the cold jar’s “heat”. Furthermore, before measuring the final temperature of our thermos, we quickly warmed up the thermometer so that the thermometer wouldn’t cause us to lose a lot of heat as the water’s heat would travel to the thermometer. Overall, we worked to create a “vaccum” to seal in heat by using various products and techniques that would minimize heat loss while also creating an appealing, adorable appearance of a bear. In the end, our thermos accomplished it’s goal, and was a success because multiple aspects were considered throughout the design process and execution.