Abstract
A three dimensional numerical investigation of turbulent forced convection of Alumina/dowtherm-A nanofluid inside a non-uniformly heated parabolic trough solar collector receiver equipped by two longitudinal fins for improving heat transfer by single and two-phase modeling has been carried out. The heat flux around the absorber tube was obtained applying Monte Carlo ray trace technique. The numerical results were validating with the empirical correlations existing in literatures and good agreement was obtained. The calculated results demonstrate that two-phase models predict a higher convective heat transfer coefficient however the predictions of Darcy friction factor by single and two-phase approaches are essentially the same. Two-phase mixture model has been used to investigate the influence of nanoparticles mean diameter on heat transfer phenomena; it found that a smaller nanoparticles increase better convective heat transfer.DOI: http://dx.doi.org/10.5755/j01.mech.23.1.14053
Highlights
Recent advancement in nanotechnology have allowed development of a new class of fluids called nanofluid, which is considered of nanoparticles suspended in base fluid
Bianco et al [11] focused the laminar flow of alumina/water nanofluid under constant wall heat flux by using the single phase and two-phase models; they declared that the two approaches give considerably the same results when the change on thermo-physical properties as function of temperature is taken into consideration
The use of compound enhancement technique based on using nanofluid and the two longitudinal fins in tube side of PTC offers better heat transfer which dues to the beneficial effect of fins and the higher thermal conductivity of nanoparticles
Summary
Recent advancement in nanotechnology have allowed development of a new class of fluids called nanofluid, which is considered of nanoparticles (oxide ceramics, metals, nonmetals, nitrides...) suspended in base fluid (water, oils, coolants, bio-fluids...). Bianco et al [11] focused the laminar flow of alumina/water nanofluid under constant wall heat flux by using the single phase and two-phase models; they declared that the two approaches give considerably the same results when the change on thermo-physical properties as function of temperature is taken into consideration. Duangthongsuk and Wongwises [4] investigated experimentally the forced convective heat transfer in a horizontal double-tube, their results shows that the heat transfer coefficient of nanofluid augments 26% and the pressure drop increases with increasing volume fraction. Akbari et al [15] presented numerical modeling of laminar mixed convection of alumina/ water inside horizontal tube with uniform heat flux using single phase and two-phase approach; they concluded that two-phase model results are closer to the experimental data but very different than that obtained by homogenous phase. The impact of particle diameter on heat transfer enhancement using two-phase mixture model has been studied
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