Modelling the efficiency of a low-profile nanofluid-based direct absorption parabolic trough solar collector

This paper compares the performance of three variations to a novel low-profile nanofluid-based direct absorption parabolic trough solar collector design. More specifically, we propose a steady state, three-dimensional model for the efficiency of such a collector subject to laminar flow. The model consists of a system of two partial differential equations describing the conservation of energy and momentum, and a radiative transport equation describing the propagation of radiation through the nanofluid. We non-dimensionalise the model revealing seven controlling dimensionless numbers: two describing different rates of thermal diffusion to advection, another two describing Newton cooling at the boundaries, and the remaining three describing black-body emissions at the boundaries. The system is solved via a modified Crank-Nicolson method which is optimised to cater for non-linearities in the radiative transport equation. A realistic parameter space exploration is conducted to investigate the optimal collector design variation. (C) 2018 Elsevier Ltd. All rights reserved.