Abstract
The optimization of the poor heat transfer characteristics of fluids conventionally employed in solar devices are at present one of the main topics for system efficiency and compactness. In the present work we investigated the optical and thermal properties of nanofluids consisting in aqueous suspensions of single wall carbon nanohorns. The characteristics of these nanofluids were evaluated in view of their use as sunlight absorber fluids in a solar device. The observed nanoparticle-induced differences in optical properties appeared promising, leading to a considerably higher sunlight absorption. We found that the thermal conductivity of the nanofluids was higher than pure water. Both these effects, together with the possible chemical functionalization of carbon nanohorns, make this new kind of nanofluids very interesting for increasing the overall efficiency of the sunlight exploiting device.
Highlights
Solar thermal collectors are heat exchangers that transform solar radiation energy to internal energy of the transport medium
In the present work we investigated the optical and thermal properties of nanofluids consisting in aqueous suspensions of single wall carbon nanohorns
The single-wall CNH (SWCNH) dispersions with concentrations varying from 0.002 to 0.1 g/l in water were prepared by the following procedure: the SWCNHs were mechanically dispersed in a water solution containing sodium dodecyl sulfate (SDS) as surfactant (SWCNH:SDS=1:1 by weight)
Summary
Solar thermal collectors are heat exchangers that transform solar radiation energy to internal energy of the transport medium. The use of black particles suspended in gases [2] or in liquids as both solar radiation absorbers and heat transfer medium has found a significant development. The use of nanosized solid additives to base fluids is an innovative technique which is being studied to enhance the overall heat transfer Different materials, such as Aluminium [6], Copper [7] and multiwall carbon nanotubes [8,9,10,11] have been added to different base fluids and characterized in terms of their performances for improving heat transfer efficiency. Carbon nanotubes (CNTs), which are characterized themselves by a very high thermal conductivity [8,13,14], appear very promising in enhancing heat transfer when suspended in fluids as well [10,11]. The measurement of the spectrally-resolved optical properties allowed us to evaluate the stored optical energy in the fluid and its spatial distribution, providing a very useful information for the collector and absorber design and for system optimization
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
