Abstract
In this paper, 3D Simulation of turbulent Fe3O4/Nanofluid annular flow and heat transfer in sudden expansion are presented. k-ε turbulence standard model and FVM are applied with Reynolds number different from 20000 to 50000, enlargement ratio (ER) varied 1.25, 1.67, and 2, , and volume concentration of Fe3O4/Nanofluid ranging from 0 to 2% at constant heat flux of 4000 W/m2. The main significant effect on surface Nusselt number found by increases in volume concentration of Fe3O4/Nanofluid for all cases because of nanoparticles heat transport in normal fluid as produced increases in convection heat transfer. Also the results showed that suddenly increment in Nusselt number happened after the abrupt enlargement and reach to maximum value then reduction to the exit passage flow due to recirculation flow as created. Moreover the size of recirculation region enlarged with the rise in enlargement ratio and Reynolds number. Increase of volume Fe3O4/nanofluid enhances the Nusselt number due to nanoparticles heat transport in base fluid which raises the convection heat transfer. Increase of Reynolds number was observed with increased Nusselt number and maximum thermal performance was found with enlargement ratio of (ER=2) and 2% of volume concentration of Fe3O4/nanofluid. Further increases in Reynolds number and enlargement ratio found lead to reductions in static pressure.
Highlights
Due to annular fluid flow and heat transfer characteristics are commonly used in condensers, heat exchangers, nuclear reactors, evaporator,..etc many experimental and numerical investigation have been achieved to improve efficiency of thermal and cooling systems
The results found that increase in Nusselt number with increased of volume concentrations of nanofluids, step height, and Reynolds number
The results revealed that sudden increases in Nusselt number occurred after the abrupt enlargement and extent to maximum value decrease to the exit passage flow due to recirculation flow as created
Summary
Due to annular fluid flow and heat transfer characteristics are commonly used in condensers, heat exchangers, nuclear reactors, evaporator,..etc many experimental and numerical investigation have been achieved to improve efficiency of thermal and cooling systems. Safaei et al [33] applied shear stress transport K-ω model to study thermal performance by using (FMWCNT) nanofluids flow over FFS. They noticed that increases in Reynolds number and volume fractions lead to rises in heat transfer coefficient. Few studies adopted effects volume fractions of nanofluids with enlargement ratio and Reynolds number in annular flow passage on enhancement heat transfer rate. The purpose of the current research is to investigate numerically the enrichment of heat transfer in abrupt enlargement of annular flow passage and the influences of volume concentrations of nanofluids, Reynolds numbers and enlargement ratio on thermal performance
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
