Numerical simulation of flat plate solar collector equipped with a turbulator containing water/copper-graphene hybrid nanofluid utilizing a two-phase model

Abstract

The use of solar systems has been broadly considered in various industries due to less environmental pollution. Flat plate solar collectors (FPSC) are a very useful device for collecting low to moderate heat from the sun. They can be used for various applications in engineering industries. In this study, the effect of an innovative turbulator with different geometric shapes and two-phase Cu-GO/water hybrid nanofluid on thermal-hydraulic performance, exergy efficiency, and energy efficiency of a FPSC is examined in a turbulent flow regime. The QUICK algorithm is also utilized to discretize the governing equations. The Reynolds number (Re) alters from 17,000 to 47,000 and the volume fraction (φ) varies from 1 and 4%. The flow is turbulent and the turbulence model is RNG k-ε and the mixture two-phase method is used for modeling the turbulent flow. Also, different geometries of the turbulator (γ = 0.5, 1, 1.5, and 2) are considered inside the absorber tube of the FPSC. The results demonstrate that the use of the turbulator in the absorber tube of the FPSC results in better thermal-hydraulic performance than the absorber tube without the turbulator. Also, increasing the curvature angle (γ) significantly affects heat transfer (HT) rate and pressure drop (Δp) enhancement. Energy efficiency is affected by φ, inlet velocity, turbulator geometric shape, and FPSC boundary conditions. By increasing Re, φ, and γ, the energy efficiency is enhanced. The exergy efficiency is influenced by φ, inlet velocity, turbulator geometric shape, and FPSC boundary conditions. Exergy efficiency is upgraded with Re and φ and is diminished with γ. The results reveal that the maximum exergy efficiency corresponds to Re = 47,000.