Abstract
In the present work, we investigated the scattering and spectrally resolved absorption properties of nanofluids consisting in aqueous and glycol 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 with respect to the pure base fluids. Scattered light was found to be not more than about 5% with respect to the total attenuation of light. 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.PACS78.40.Ri, 78.35.+c, 78.67.Bf, 88.40.fh, 88.40.fr, 81.05.U.
Highlights
Heat exchange devices suffer a serious limitation due to the relatively low thermal conductivity of conventional fluids
single-wall carbon nanohorn (SWCNH) were mechanically dispersed in water and ethylene glycol by a high pressure homogenizer
Long-term stability was assured to the dispersions, as demonstrated by long-term stability measurements performed for the water dispersions [41] and by size measurements performed in glycol dispersion 6 months after the preparation (Sani E et al, Potentialities of carbon nanohorn-based suspensions for solar thermal collectors, submitted )
Summary
Heat exchange devices suffer a serious limitation due to the relatively low thermal conductivity of conventional fluids. A very important property in view of their potential use with respect to CNTs arises from the metal-free structure of nanohorns that makes their cytotoxicity negligible, as has been widely confirmed by experiments on mice and rats [34] This makes the use of SWCNH very appealing in all applications where the handling by operators is needed or when accidental leakages into the environment are possible. As nanofluids appear promising for thermal solar energy applications, it is important to carry out investigation of their optical properties allowing to assess their potentialities as direct sunlight absorbers. To evaluate the relative weight of scattering processes over the overall light extinction phenomenon, the absorption and scattering coefficients of SWCNH aqueous suspensions were separately measured with the utilization of a simple and precise technique This allowed to assess the reliability of the measured transmittance data. This extensive analysis of SWCNH nanofluids can optimize their use, providing useful information for the system dimensioning
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
