What are good thermal insulators for a lunchbox?

Question

I have to make an effective thermal lunchbox out of a cardboard box for a school project. My lunchbox has 2 compartments one side is for hot and the other for cold. I'm supposed to keep both sides hot and cold. What are some good thermal insulators? (Tin foil, bubble wrap etc.)

Answer 1

You should use a couple strategy.



First tinfoil is a good conductor so is not a good insulator . But if you have the shiny part of tinfoil pointed toward the hot. Food it will reflect the heat back to the food.



If you insulate around the outside of the tinfoil the small amount of conducting heat will be kept from moving away



The bubble wrap might be good. For this



Air trapped in crinkled paper is good insulator too.



The cold side could be done in reverse with shiny part of tinfoil surrounding the. Insulation this would reflect most of the infrared or heat away from the cold food helping to keep it cool

Answer 2

Alternate layers of bubblewrap and foil. The foil reflects radiant heat but conducts heat well.

The bubblewrap blocks a lot of conducted heat.



Between the two, you have a good overall insulator.

Answer 3

Aluminum foil. It traps the temperature within an object.

Answer 4

FOAM.