Abstract
In the present investigation, the free convection energy transport was studied in a C-shaped tilted chamber with the inclination angle α that was filled with the MWCNT (MultiWall Carbon Nanotubes)-Fe3O4-H2O hybrid nanofluid and it is affected by the magnetic field and thermal flux. The control equations were numerically resolved by the finite element method (FEM). Then, using the artificial neural network (ANN) combined with the particles swarm optimization algorithm (PSO), the Nusselt number was predicted, followed by investigating the effect of parameters including the Rayleigh number (Ra), the Hartmann number (Ha), the nanoparticles concentration (φ), the inclination angle of the chamber (α), and the aspect ratio (AR) on the heat transfer rate. The results showed the high accuracy of the ANN optimized by the PSO algorithm in the prediction of the Nusselt number such that the mean squared error in the ANN model is 0.35, while in the ANN model, it was optimized using the PSO algorithm (ANN-PSO) is 0.22, suggesting the higher accuracy of the latter. It was also found that, among the studied parameters with an effect on the heat transfer rate, the Rayleigh number and aspect ratio have the greatest impact on the thermal transmission intensification. The obtained data also showed that a growth of the Hartmann number illustrates a reduction of the Nusselt number for high Rayleigh numbers and the heat transfer rate is almost constant for low Rayleigh number values.
Highlights
Particles with micrometer size were traditionally added to fluids to increase their thermal conductivity coefficient
The results demonstrated that the impact of particles size and concentration of nanoparticles is higher than the influence of temperature factor on thermal conductivity of nanoparticles
The results of the obtained governing equations are presented in the form of charts and tables
Summary
Particles with micrometer size were traditionally added to fluids to increase their thermal conductivity coefficient. These particles did not have the required stability in the suspension and was quickly deposited, leading to the blockage of the fluid passageway. Nano-sized particles form a much more stable suspension and the problem of channel chocking and blocking is minimized due to lower sedimentation rates. Nanoparticles are produced for the size range of 1 nm to 100 nm, depending on the type of operation. Nanofluids were first prepared by Choi in 1995 [1]. Since they have been considered by many researchers in engineering and Energies 2019, 12, 2807; doi:10.3390/en12142807 www.mdpi.com/journal/energies
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