Tileable 3D compound parabolic concentrator (CPC)

thingiverse

This is similar to the trough CPC, but it is closer to a 3D version (rotate the CPC profile around an axis to get a true 3D version), so the concentration ratio is higher. This enables higher temperatures. It has a collection angle of 45 degrees, so only a concentration ratio of 2. It is meant to heat a small jar. Alternatively, you can use it to cool things as well. The infrared radiation leaving the jar gets pointed up to the most transparent part of the sky and therefore radiatively transfers with an effectively colder atmosphere, thereby being able to cool below ambient [ Heat energy transferred = emissivity Area ( temperature difference) ^ 4]. See the picture with the thermocouples, 85 is ambient, the jar is at 77 (this is in the evening in the summer). Instructions Filing is required for the inserts, but I figure it is probably better to error on the side of a tight fit when printing rather than not have enough material. I just used aluminized mylar for the reflective surfaces, but aluminum foil would probably be just fine. If you use a white painted jar, you can cool below ambient temperature (with low sun or at night). In the autumn, you can even make ice when the air is above freezing (depending on local humidity).