Premium
Numerical studies on heat and fluid flow of nanofluid in a partially heated vertical annulus
Author(s) -
Ahmad Khan Suhail,
Altamush Siddiqui M.
Publication year - 2020
Publication title -
heat transfer
Language(s) - English
Resource type - Journals
eISSN - 2688-4542
pISSN - 2688-4534
DOI - 10.1002/htj.21672
Subject(s) - nanofluid , nusselt number , prandtl number , materials science , rayleigh number , heat transfer coefficient , heat transfer , thermodynamics , annulus (botany) , reynolds number , mechanics , heat flux , heat transfer enhancement , volume fraction , natural convection , physics , turbulence , composite material
Abstract A numerical investigation on natural convective heat transfer of nanofluid (Al 2 O 3 +water) inside a partially heated vertical annulus of high aspect ratio (352) has been carried out. The computational fluid dynamics solver Ansys Fluent is used for simulation and results are presented for various volume fraction of nanoparticles (0‐0.04) at different heat flux values (3‐12 kW/m 2 ). Two well‐known correlations for evaluating thermal conductivity and viscosity have been used. Thus different combinations of the available correlations have been set to form four models (I, II, III, and IV). Therefore, a detailed analysis has been executed to identify effects of thermophysical properties on heat transfer and fluid flow of nanofluids using different models. The results show enhancement in heat transfer coefficient with volume fraction of nanoparticles. Highest enhancement achieved is found to be 14.17% based on model III, while the minimum is around 7.27% based on model II. Dispersion of nanoparticles in base fluid declines the Nusselt number and Reynolds number with different rates depending on various models. A generalized correlation is proposed for Nusselt number of nanofluids in the annulus in terms of volume fraction of nanoparticles, Rayleigh number, Reynolds number, and Prandtl number.