Abstract:
Nanofluids inherently have high emissivity in the mid-infrared region making them unsuitable for
satisfying the conditions of solar selectivity required for direct absorbers. In this study, a layer of silicone
oil is located above nanofluid comprising of graphite nanoparticles and deionized water. Silicone oil layer
is shown to act as a barrier against the infrared emissions from the nanofluid. High transparency of
silicone oil in the visible solar spectrum and high absorptivity in the mid-infrared wavelength range
made it an excellent candidate for this study. Solar selectively was achieved by using two different liquid
layers (nanofluid and silicone oil) in direct thermal contact. Silicone oil layer on the top of the nanofluid
resulted in an approximately 17% higher temperature rise in the nanofluid.
