Abstract
Solar thermal systems have low efficiency due to the working fluid's weak thermophysical characteristics. Thermo-physical characteristics of base fluid depend on particle concentration, diameter, and shapes. To assess a nanofluid's thermal performance in a solar collector, it is important to first understand the thermophysical changes that occur when nanoparticles are introduced to the base fluid. The aim of this study is, therefore, to analyze the hydrodynamic and heat characteristics of two different water-based hybrid nanofluids (used as a solar energy absorber) with varied particle shapes in a porous medium. As the heat transfer surface is exposed to the surrounding environment, the convective boundary condition is employed. Additionally, the flow of nanoliquid between two plates (in parallel) is observed influenced by velocity slip, non-uniform heat source-sink, linear thermal radiation. To make two targeted hybrid nanofluids, graphene is added as a cylindrical particle to water to make a nanofluid, and then silver is added as a platelet particle to the graphene/water nanofluid. For the second hybrid nanofluid, CuO spherical shape particles are introduced to the graphene/water nanofluid. The entropy of the system is also assessed. The Tiwari-Das nanofluid model is used. The translated mathematical formulations are then solved numerically. The physical and graphical behavior of significant parameters is studied.
Highlights
Solar thermal systems have low efficiency due to the working fluid’s weak thermophysical characteristics
The current study involves the three-dimensional flow of a steady, laminar and incompressible hybrid nanofluid confined by two parallel plates spaced δ apart in a rotating frame
It is found that the primary velocity dwindled for mounting values of Ro, whereas secondary velocity first increases decreases in the channel
Summary
Solar thermal systems have low efficiency due to the working fluid’s weak thermophysical characteristics. Cp nf Effective heat capacity of nanofluid h1 Heat transfer coefficient ρhnf Density of hybrid nanofluid kg m−3 Ro Rotation parameter a, b, c Subscripts for spherical, cylindrical, and platelet ρs Density of particle Rex Local Reynold number δ Distance between the plates ρnf Density of nanofluid kg m−3 f (η) Dimensionless primary velocity φ Particle volume fraction Br Brinkman number k Permeability of porous medium μnf Dynamic viscosity of nanofluid kf Thermal conductivity of the fluid W K−1m−1 Q0, Q1 Nonuniform heat source and sink parameters Cf Skin friction Nu Nusselt number Cp f Effective heat capacity of fluid J kg−1K−1 e Stretching rate of the lower plate To Upper wall temperature p Pressure (Pa) αnf Thermal diffusivity of nanofluid νhnf Kinematic viscosity of hybrid nanofluid η Similarity variable νnf Kinematic viscosity of nanofluid k∗ Mean absorption coefficient ρf Density of working fluid Bi Biot number σ ∗ Stefan–Boltzmann constant kg/s3K4 αf Thermal diffusivity fluid θ (η) Dimensionless temperature qw Heat flux Porosity parameter knf Thermal conductivity of nanofluid W K−1m−1 τw Wall shear stress Reδ Reynold number ω Non-dimensional temperature difference
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