Thermos Challenge 

Procedure

• Step 1: fill a 150 mL glass beaker with tap water of any temperature
• Step 2: place beaker on top of hot plater set at the highest temperature setting
• Step 3: bring water to a boil and keep it until the thermometer reaches 100 degrees celsius
• Step 4: using tongs, pour water into the prototype and immediately record its temperature using the thermometer
• Step 5: seal prototype and let sit
• Step 6: set timer for 10 minutes
• Step 7: after 10 minutes record temperature with the thermometer
• Step 8: repeat steps 5 to 7
• Step 9: record the water’s final temperature after 20 minutes has elapsed

 

Prototype 1:

 

 

Our first prototype was composed of a styrofoam cup stacked on top of a pringles can, with a plastic bottle wrapped in aluminum foil inside. This prototype had many components that worked quite well together and gave us results we were happy with. It out performed our second prototype, however, the build of it was not stable enough to use for our final result and thus we continued using the idea to improve. Although it was not the most stable in terms of the bottle inside relying on the lid attached to the cup for support, the conductivity inside helped keep heat, while the cups insulation and the reflection inside the pringles can worked to keep any heat trying to escape inside. To improve this prototype, we should have made the bottle more stable so that the lid was not the only thing holding it up. This would ensure the lid could fully close and that there would be no gaps releasing air. This prototype, gave us a better understanding for the remaining prototypes.

 

Prototype 2:

Our second prototype had very similar results to the first, however, it was not an improvement and did not have enough structural stability to use. It was composed of a metal can without a lid, two paper cups, paper towel, cotton balls and styrofoam packing chips. The fault in this thermos came from the structure itself. The cups were too big for the can and therefore, allowed more air to escape. On top of this, we had stacked the cans in such a way that we had no way to access the water to test the temperature so in order to do that we had to either take the top cup off and then place it back on once we had recorded the temperature after the first 10 minutes or we could make a hole at the top and through the paper towel to allow the thermometer through. We tried both options and included a flap at the top to close the hole, however both allowed quite a bit of heat to escape more rapidly than the first prototype. To improve this prototype, we should have considered smaller cups and a more convenient way of measuring the temperature.

 

Prototype 3:

For our third prototype we ended up reducing the amount of materials we were using and the design itself was very simple. The reason for this is that making the first and second we were planning to build up to using a glass bottle on the inside to hold in heat, because it is an insulator. That idea did not end up working because the sizes of the bottles didn’t match as well as we predicted and therefore we ended up with air escaping from the glass one and into the plastic bottle we had inside. We then switched to using a jar, however that failed as well. From that we decided to test out how a glass jar wrapped in Foam Insulation would work. We were able to achieve the results we wanted using this prototype. Although it is a drastic change in structure and design from our previous prototypes, the idea originated from the glass bottle we were using to improve our prototypes. Our final product was a glass jar with a lid and rubber stopper that acted as a seal, wrapped in foam insulation with glitter for design quality on top. Once we tested this prototype, we achieved the best results and decided to further improve this prototype for the final product. To do so, we carefully wrapped the insulation more tightly around the outside to ensure no air space and use as much as possible within the price to cover the entire thermos.

 

Prototypes Graph

 

Final Thermos

 

Materials

• Thermometer
• 150 mL tap water (any temperature)
• Hot plate
• 150 mL glass beaker
• Tongs
• Funnel
• Timer
• Glass jar with lid
• Foam Insulator
• Scotch Tape
• Glitter (decoration)

 

Results

Temperature Initial: 85 degrees celsius

Temperature Final: 60 degrees celsius

 

Our main material for our thermos is glass. Glass is a poor conductor because it doesn’t allow the flow of electrons easily from atom to atom in the glass which means it’s great at keeping heat in. By using a glass jar, the heat from the boiling hot water was not transferred, through conduction, to the glass, and instead was being kept inside the thermos as a result from the glass.

At the top of our glass jar was a rubber stopper lining the lid of the jar and providing a tighter seal. This is an important aspect to the jar because hot air molecules speed up causing it to expand, so it becomes less dense and, a result, rises. Therefore, having something that stopped it from escaping from the top was a key aspect of the thermos. Rubber is also an insulator so, just like the glass, the heat was not transferred to the rubber through conduction, but instead, the rubber held it in the thermos.

Surrounding the outside of the glass jar was the flooring underlay. The underlay is a thin layer of cushioning made out of materials such as sponge, rubber, foam, felt, or crumb rubber. These materials when laid beneath carpeting tend to provide insulation against sound, moisture, and heat. We used the concept of it providing insulation to heat for use in our thermos. We believed that if by any chance heat escaped from any part of the glass jar then the insulator would keep the heat from transferring to the air and transfer it back to the water. After thinking about it, even if the heat did escape from the glass, the foam insulator wouldn’t have done anything to help return it to the water because it would’ve just held the heat between the foam and the glass jar because glass isn’t a conductor, it’s an insulator. It wouldn’t have made a difference to the water because no heat would be transferred back to the water. As a result, the water had a lower temperature.

Our temperature also  could’ve been lower because the glass, although it has low conduction, still has the ability to have its atoms move faster and transfer heat. It’s just at a lower rate than other materials such as metal.

In an ideal situation, the temperature of the water would have stayed the same. The thermal energy of the water that we placed into the thermos, would have remained the same if it was in fact a perfectly isolated thermos, and as a result the waters temperature would also remain the same throughout the procedure. According to the law of conservation of energy, energy is not lost or destroyed, so the thermal energy from the water shouldn’t have changed.