Investigation of optical properties and radiative transfer of TiO2 nanofluids with the consideration of scattering effects

The optical properties of nanofluids need to be specified accurately to determine the effectiveness of nanofluids in photocatalytic reactions. In this study, the Monte Carlo method combined with the Mie scattering phase function was developed to calculate the optical properties and radiative transfer of TiO2 nanofluids. The scattering effects caused by the directional scattering properties of the nanoparticles were considered during radiative transfer analysis of nanofluids. Size parameter (chi) was adopted as the criteria to divide the nanoparticles into two categories: small particle (chi < 1) and large particle (chi >> 1). The spectral transmissivity, absorption coefficient, extinction coefficient, and scattering characteristics of TiO2 nanofluids were theoretically analyzed. The numerical results indicate that the optical properties of nanofluids with small particles vary smoothly with wavelength, while the optical properties of nanofluids with large particles oscillate with wavelength due to diffraction peaks. This study concluded that the scattering effects need to be considered during investigation of optical properties and radiative transfer of nanofluids. (C) 2017 Elsevier Ltd. All rights reserved.