OVERALL ANALYSIS

[Click image to enlarge]

• Test 1 : Efficiency = 85%
• Test 2: Efficiency = 76%

We lost majority of our heat from around the bottle, this may be because of the insulators we choose. Less heat was being transmitted from the bottom, and that was because we had the support of the rice preventing the bottom part of the bottle from touching the outer layer. We could've improved our materials by looked at the heat capacity of each material so we could get an idea of how much they generally insulates. I would've changed some of the materials for future versions and do more testing/improvements so we could compare results with a thermos that has a better efficiency than ours.

Laws of thermodynamics are the principles that govern heat transfer and thermal energy. The first law of thermodynamics state that, "Energy can be transformed into another form, but can't be created or destroyed." If you were to experiment with volatile heat sources you could have seen that liquid forms into gas when the temperature rises. When you lift the lid off of the thermos, gas will come out because of the hot temperature making the liquid evaporate. If we look at the heat capacity of plastic  which is, c = 39.6K Jkg-1 K-1 we can find out how much heat is measured to heat up a gram of plastic, or any other material thus finding out if the heat source if volatile. The equation for relating heat energy to a specific heat capacity in terms of mass is; Q = m c ΔT.

• Q : Heat energy input or output of the substance
• m : Mass of substance
• c : Specific heat capacity
•  ΔT: Temperature differential

The second law of thermodynamics states that," In all energy exchange  if no energy enters or leaves the system, the potential energy of the state will always be less than that of the initial state."  or in other words no process can be 100% efficient because some energy will always remain in the form on thermal energy. An example of this would be when a car runs out of gas in the middle of the desert and will not run again until you walk 10-15 miles to a gas station and refuel the car. When energy exchange occurs some energy is transfer into thermal energy;  Our project is evidence that this is true, as heat can be felt (meaning it's not 100% efficient).

http://answers.yahoo.com/question/index?qid=20071215081939AALhW4z
http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookener1.html
http://wiki.answers.com/Q/What_is_plastic's_specific_heat_capacity