3 ms·
This would not work in your thermos! This material is reflective in the visible but emissive in the infrared. The only thing that matters in the thermos is bein
by twarge 3y ago
This would not work in your thermos! This material is reflective in the visible but emissive in the infrared. The only thing that matters in the thermos is being reflective in the infrared.
Thermodynamics does not permit a thermal diode to exist.
- hinkley 3y agoI think it's even simpler than that. Any black body that is colder than its surroundings heats up. Any black body warmer than its surroundings will cool down. This thermos would only keep your coffee hot if you dropped it into a furnace.
- nyanpasu64 3y agoYou could make a colored flask which absorbs visible light (from the sun) but reflects thermal wavelengths (from the drink). But due to infrared leakage and thermal conduction, I don't know if it would keep drinks above 100 degrees F for anywhere near as long as a standard vacuum flask.
- eternauta3k 3y agoWhat about real materials, e.g. not a black body?
- hinkley 3y agoThe neat thing about wearing white in the desert is that it keeps you cool during the day and warm at night. Wearing black does the opposite. A perfect black surface on a spacecraft can do more than charcoal black paint, but only by a matter of degrees. If memory serves its less than a 2x multiplier between off the shelf and exotic materials. But when ounces cost thousands of dollars, you’re going to go exotic.