One-way radiant heat panels

[Jim_Mich]

What if there was a way to make a panel that let radiant heat pass one direction while blocking it in the reverse direction. It would act like a heat diode. Imagine a panel full of lenses. Each lens focuses visible and infared light and passes it through a tiny hole. Any reverse radiant energy is reflected back. This would cause one side of the panel to be warmer while the other side cooler. I've toyed with a number of ideas such as lenses and fiber optics.

There would be many uses for such panels, such as heating and cooling building, coolers to keep food cold or hot, and if coupled to low temperature heat engines with generators might even produce electricity. Might even be able to make self cooling soda and beer cans or self heating soup cans?

Jim_Mich

[fleebell]

If you think about for a moment there would be alot more applications for something like that... It would probably be a stirling engines designers dream come true among other uses
Lee B

[Charlie Brown ARN]

A panel of black material with a lot of conical depressions on its surface may radiate more thermal background than a smooth flat surface because the surface area is greater. It may then overwhelm the flat backside of the next layer in a cascade. A surface with many small conical depressions will have the same surface area as a surface with one large conical depression but the layer with the smaller features will be thinner, allowing a more compact cascade. Electromagnetic radiation can go through pores one tenth its wavelength if there is no gap at its target. Heat conduction in the area outside the conical depression should be avoided because this degrades the desired heat pass forward effect. Maybe insulating posts can be used. A millimeter of cascaded layers will contain a hundred ten micrometer layers or a thousand one micrometer layers, the probable most interesting range of size for 10 micrometer infrared, the infrared peak at room temperature. This effect may be useful at high temperatures because thermal radiation increases with the fourth power of the temperature and the peak wavelength decreases with increased temperature. My estimate is that this is worth trying but probably not practical at room temperature. I was stimulated by your question in this forum so this is a group idea.

[kenbo0422]

Glass



Greenhouses use it, although heat can escape.  The key would be frequency attenuation, i.e. infrared passes in one direction, but looking at it from the other direction, the 'color' is different and won't let it back through.   How's that for a half baked idea?

[dracozny]

a solar oven would work on similar principles on one side of the panel is reflective surface such as a white color and on the other side is black. some heat will escape but it will still get extrememly hot. just like all you people with black cars