[will_lam]

I think the idea is quite brilliant - being an avid coffee drinker - many a time I wished my coffee was still warm while travelling on public transit.

[ghshephard]

The keeping coffee "Hot" problem is easily solved with a good, insulated, transit mug. High quality ones will keep your coffee very hot for a couple hours.

What the Joulies do is _cool_ the coffee by initiating a phase change in their PCM, but then don't drop it too far down.

[georgieporgie]

but then don't drop it too far down.

They actually actively maintain the temperature until their internal substance has turned back into a solid (which may or may not be what you meant).