Evaluation of wavy direct absorption solar collector (DASC) performance using different nanofluids

In this paper, thermal performance of a wavy nanofluid-based direct absorption solar collector (DASC) is evaluated using finite element method (FEM) by FlexPDE commercial package software. After presenting the governing equations and solving them by FEM, TiO2, Al2O3 and CuO nanoparticles are considered to make water-based nanofluid in the collector. Due to three different wall types in the problem (bottom wavy wall, flat top wall and vertical side walls) and three different boundary condition types (insulated, constant heat flux and constant temperature), the problem is solved for the more appropriate conditions. For all tested nanofluids, the effect of nanoparticles volume fraction is also investigated on the local/average Nusselt numbers. Results show that wavy collectors have larger maximum Nusselt number compared to flat plate collectors. Furthermore, the most Nusselt numbers are reported for TiO2 nanoparticles in the little volume fractions. (C) 2016 Elsevier B.V. All rights reserved.