A thermos bottle, in it's simplest form, is a vacuum space between two thermally conductive spaces and keeps hot foods hot and cold foods cold precisely because it allows heat loss only through radiation and not through conduction and convection. Radiation is much less efficient at removing heat than the other methods.Originally posted by Malenfant:
I'm a bit rusty on this side of physics, but vacuum isn't an insulator - it's actually fantastic at removing heat by radiation but just sucky at conduction and convection (because there's nothing there to conduct into or material to to convect around).
You don't really need to 'work' to remove heat at all - you just have a radiator that has the hot stuff going through it (either heated directly or having hot water going through pipes) and a lot of surface area to radiate the heat away into space and that cools things down. Though for best results the radiator itself has to be in the shade so it's not itself being heated by the sun.
Radiators are precisely how a contemporary space craft “works” at removing heat. If the radiators on the ISS failed, the occupants would die of heat and not from cold. The people and electronics generate too much heat for human comfort. Survival depends on adding equipment to radiate the excess heat. ... And THAT is ironic given how cold space is (in the shade).