Numerical investigation of efficiency enhancement in a direct absorption parabolic trough collector occupied by a porous medium and saturated by a nanofluid

In this study, a numerical investigation of the solar parabolic trough collector with an area of 0.856 m2 by combination of Monte Carlo Ray‐Trace (MCRT) and finite volume method (FVM) has been carried out using the FLUENT software. The purpose of this study is to investigate the effect of metal foams and nanofluids on the thermal performance of a direct absorption parabolic trough collector (DAPTC). For this purpose, three‐dimensional fully developed laminar convection heat transfer of Al2O3 and TiO2/water nanofluids is examined by 0.1, 0.2, and 0.3 vol %. Furthermore, 64 cm copper‐filled porous media in a volumetric absorbent tube are applied. The obtained results of numerical simulations are compared with the experimental data. The results demonstrate a good agreement between the numerical simulations and experimental data. The results indicate that the maximum efficiency was 34.51% for TiO2/water at 0.3 vol %. Furthermore, using porous media with high absorption coefficient and scattering coefficient that could absorb more incoming radiation and transfer to heat transfer fluid can result in increasing the efficiency of the collector. © 2018 American Institute of Chemical Engineers Environ Prog, 38: 727–740, 2019