|30||Electric Thermos Box
|Project Members: Zerui An (zeruian2), Tingfeng Yan (ty7), Celine Chung (mwchung2)
Normal thermos cups preserve the temperature of the liquid inside by using proper physical structure to slow the dissipation of thermal energy, but we often find the liquid too hot or too cold when we are using them. Usually, if we find the liquid too hot to drink, we might let the cup open or add some same kind of liquid at a lower temperature. These methods either take long or cannot be performed due to limited conditions. This situation is even worse when we want the liquid to be hotter since we hardly have any ways to heat up the liquid.
# Solution Overview:
We can design an electric thermos cup. This cup can heat up or cool down the drink inside by simply pressing a button, or by setting a desired temperature using the provided buttons.
# Solution Components:
- Subsystem 1 (heating): This module starts heating up the drink once the heating button is pressed (or when desired temp. is higher than current temp.), changing the light color to red at the same time.
- Subsystem 2 (cooling): This module starts cooling down the drink once the cooling button is pressed (or when desired temp. is lower than current temp.), changing the light color to blue at the same time.
- Subsystem 3 (control): This module heats/cools the drink to a user-specified temperature (by sending control signals to subsystem 1 & 2). In case we decide to add a pause button, this module is also responsible for stopping the heating/cooling process when the pause button is pressed.
- Subsystem 4 (display): A screen displaying current liquid temperature, which is measured by a temperature sensor.
- Subsystem 5 (power): Power supply of all the other subsystems.
- Subsystem 6 (safety): This subsystem will take in the data of the temperature sensor and force the system to pause when the temperature is too high or too low. Also activated when the circuit is behaving abnormally (e.g. when the current goes too high)
We now have 3 possible ideas for subsystem 1 (heating subsystem):
(1) By Joule’s Law p = I^2*R, we could use resistors to generate heat. The main challenge of this approach is how we could supply enough power while keeping the voltage and current under control (avoid burning the circuit).
(2) We could run a heat engine in reverse (as a heat pump). Compared to approach (1), this approach requires less power (the exact amount is determined by the efficiency of the heat pump). The main challenge of this approach is to build an efficient yet small heat pump.
(3) We could make use of some reversible chemical reaction that absorbs/releases a fair amount of heat. The main challenge of this approach is to find a satisfying reaction and to build a control system for it.
Approach (2) and (3) can also be applied to subsystem 2 (cooling subsystem)
# Criterion for Success:
Portable size and weight. Heat up and cool down some water in a reasonable amount of time and consume a reasonable amount of energy.