Selective surface

<p>In <a href="/facts/Solar_thermal_collector/sR9KzYbL">solar thermal collectors</a>, a selective surface or selective <a href="/facts/Absorption_(electromagnetic_radiation)/xBYKt7yS">absorber</a> is a means of increasing its operation temperature and/or efficiency. The selectivity is defined as the <a href="/facts/Ratio/mFmhQt7T">ratio</a> of <a href="/facts/Solar_radiation/SI26I7aD">solar radiation</a> <a href="/facts/Absorption_(electromagnetic_radiation)/xBYKt7yS">absorption</a> (αsol) to <a href="/facts/Thermal_infrared_radiation/44XdJNcc">thermal infrared radiation</a> <a href="/facts/Emission_(electromagnetic_radiation)/fxumR717">emission</a> (εtherm).
</p><p>Selective surfaces take advantage of the differing wavelengths of incident solar radiation and the emissive radiation from the absorbing surface:
</p>
<ul><li>Solar radiation covers approximately the wavelengths 350 nm to 4000 nm; <a href="/facts/UV-A/kncBUqn5">UV-A</a>, <a href="/facts/Visible_light/jeofpMn4">visible</a> and <a href="/facts/Near_infrared/44XdJNcc">near infrared</a> (<a href="/facts/Near_infrared/44XdJNcc">NIR</a>, or <a href="/facts/IR-A/44XdJNcc">IR-A</a> plus <a href="/facts/IR-B/44XdJNcc">IR-B</a>).</li>
<li>Thermal <a href="/facts/Infrared_radiation/44XdJNcc">infrared radiation</a>, from materials with temperatures approximately in the interval -40 to 100 °C, covers approximately the wavelengths 4000 nm to 40,000 nm = 4 um to 40 um; The thermal infrared radiation interval being named or covered by: <a href="/facts/Mid-infrared/44XdJNcc">MIR</a>, <a href="/facts/LWIR/44XdJNcc">LWIR</a> or <a href="/facts/IR-C/44XdJNcc">IR-C</a>.</li></ul>

Selective surface open-in-new

Selective surface