Optical Properties and Radiation-Enhanced Evaporation of Nanofluid Fuels Containing Carbon-Based Nanostructures

Abstract

The present paper experimentally determined the evaporation characteristics of nanofluid fuels with stable suspension of carbon-based nanostructures under radiation absorption in the ultraviolet–visible range. The results show that the evaporation rates of the ethanol-based nanofluids containing multiwalled carbon nanotubes (MWCNTs) or carbon nanoparticles (CNPs) are both higher than the evaporation rate of pure ethanol. Additionally, ethanol fuel with the addition of MWCNTs has a higher droplet temperature and a higher evaporation rate than the one with the addition of CNPs or aluminum (Al). To determine the optical properties of various nanofluids, which can help to explain the observed evaporation behavior, we measured the transmission spectrum for each nanofluid, and the extinction coefficient was determined accordingly. The optical properties were also modeled using Rayleigh approximation. The importance of radiation absorption and scattering by the suspended nanostructures was identified for various nanofluids. The results show that MWCNTs are more effective than Al and CNPs for radiation absorption in nanofluid because less energy is scattered away.