In addition to the normal vaccuum insulation layer, it has a layer that does a (constant-temperature) phase change at ~140F. If your drink is hotter than this, energy flows out of the drink, cooling it and liquifying the layer. If you drink is cooler, energy flows into the drink, solidifying the layer.
Just a quick, non-hostile technical nitpick: I don't believe that at any point, energy will actually be flowing back into the drink. If the drink is cooler, the insulator layer will become a significantly worse conductor, preventing heat from flowing outward as well as from the liquid-phase insulator, but thermodynamics/the law of entropy shouldn't really allow for the energy to flow back into the liquid, even when the insulator does re-solidify.
When the "insulator layer" (a phase change material or PCM) is between phases, it can absorb or emit energy without changing temperature.
The drink on the other hand will change temperature as it looses energy.
The drink will lose energy through the lid, leading to a small temperature gradient between the PCM and the drink. This gradient should allow energy to flow back from the PCM into the drink.
Its „Temperfect insulation“ is most likely a PCM i.e. a phase changing material storing heat in a phase transition. It absorbs or releases heat depending on the outer temperature by means of a physical phase transition (not sure if this is really liquid-solid but perhaps a crystal reconfiguration).
Sigh, anywhere I can buy this for my wife and I in Australia? The shipping for 2 cups is $60 USD, and it all totals out to something like $250 AUD which is completely unjustifiable.
Insulated keep cup on display at any cafe is around $15-25 AUD.
qchris|2 years ago
eru|2 years ago
(I mean that's not a crazy notion: if you have any warm mug and fill it with cold stuff, the warm mug will heat up your cold stuff.)
You are right that if you keep your mug closed, there shouldn't be any energy flowing back into your drink.
newaccount74|2 years ago
The drink on the other hand will change temperature as it looses energy.
The drink will lose energy through the lid, leading to a small temperature gradient between the PCM and the drink. This gradient should allow energy to flow back from the PCM into the drink.
G3rn0ti|2 years ago
aetherspawn|2 years ago
Insulated keep cup on display at any cafe is around $15-25 AUD.