säteilyjäähdyttimen

Säteilyjäähdytin, known in English as a radiative cooler, is a passive cooling technology that allows an object to cool down to temperatures below the ambient air temperature by emitting thermal radiation into outer space. This process works by exploiting the fact that the Earth's atmosphere is largely transparent to certain wavelengths of infrared radiation, particularly in the atmospheric window between 8 and 13 micrometers. Objects emitting radiation in this spectral range can therefore effectively lose heat directly to the coldness of outer space, which acts as a heat sink at approximately 3 Kelvin.

The performance of a säteilyjäähdytin depends on several factors, including the emissivity of the radiating surface, its view of the sky, and atmospheric conditions such as cloud cover and humidity. Materials with high emissivity in the infrared spectrum are ideal for radiative cooling surfaces. These coolers do not require any external power source or moving parts, making them a sustainable and cost-effective cooling solution. Applications range from cooling buildings and vehicles to keeping food and medical supplies cold in off-grid locations. Advanced designs incorporate specialized coatings and structures to maximize radiative heat loss while minimizing heat gain from the surroundings and the atmosphere.