Feasibility of IoT technology was evaluated by,

  • Learning Python to program an ESP32 kit (M5stickC)

  • Creating a closed-loop system with a temperature sensor

  • Linking to an app for remote control

Testing the Peltier module for designing a lunchbox with compartments for cold and warm meals.
It was disregarded due to its energy inefficiency.

CES Edupack to narrow down materials with,

  • Low thermal conductivity

  • High service temperature (up to 200 °C)

  • Recyclable

  • Safe for food contact

  • Ability to use molding & thermoforming

Effective battery choice
(size vs weight)

Power requirements of the self-heating lunch-box were estimated by calculating the energy needed to heat up 850mL water from 5°C to 70°C. i.e. 66.6Wh with a 100W heating element powered for 40min.

 

Since 70Wh energy is available in 21700 x 4 cells or 18650 x 6 cells, either combination can be used.