Heat transfer enhancement using CNT-water nanofluids and two stages of seawater supply in the triangular solar still

Abstract

This work represents a three-dimensional numerical study of doubly diffusive convection of the air-vapor mixture inside a triangular solar still. A new seawater feed design is studied as well as the impact of nanofluid addition. The governing equations of the model are formulated on the basis of the three-dimensional formulation of the potential-vorticity vector and discretized using the finite element method. The parametric study was performed by varying the buoyancy ratio, Rayleigh number between 103 and 106, the volume fraction of the nanoparticles (0 ≤ φ ≤ 10%) and the length, Lp, of a second seawater feed stage between 0.1 and 0.5. The main results obtained show that this new design improves the heat and mass transfer rates for specific dimensions. The second-stage seawater supply dimensions Hp=0.2 and LP=0.5 improved the thermal performance by 38% and the mass performance by 55% at the evaporating surface and condensing surface. The impact of the nanofluid concentration on the heat transfer enhancement depends on the operating conditions of the solar still.

Keywords

• Solar still
• Triangular pyramid shape
• 3D-double diffusive convection
• CNT-Water nanofluids