In this study, numerical investigation has been carried out for a range of system and operating parameters in order to analyze the effect of protrusion obstacles on heat and fluid flow characteristics of nanopartical Al2O3 with concentration 4.0% and diameter 30 nm in square mini channel. The square mini channel has, stream wise spacing (Xs/dp) range of 1.4–2.6, span wise spacing (Ys/dp) range of 1.4–2.6, ratio of protrusion height to print diameter (ep/dp) of 1.67 and Reynolds number (Ren) ranges from 4000 to 18,000. Simulations were carried out to obtain heat and fluid flow behaviour of smooth and rough tube, using commercial CFD software, ANSYS 16.0 (Fluent). Renormalization k−ε model was employed to assess the influence of protrusion on turbulent flow and velocity field. Simulation results show that, the enhancement of 3.73 times in heat transfer and 4.25 times enhancement in pressure drop as a function of Xs/dp and Ys/dp of 1.8 respectively

In this article, turbulent heat transfer of nanofluid flow in square passage with protruded rib shape is numerically and experimentally studied over Reynolds number ranges of 4000â18000. Different nanoparticles (Al2O3, CuO, and ZnO), with different concentration (Ï) range of 1â4% and different nanoparticle diameter (dnp) range of 30â45 nm are disperse in water (base fluid). Several parameters such as stream wise distance (Xs/dp) range of 1.4â2.6, span wise distance (Ys/dp) range of 1.4â2.6, ratio of protruded height to print diameter (ep/dp) range of 0.83â1.67 also studied to find the consequence on thermal and hydrodynamic characteristics. Simulations were carried out to obtain heat and fluid flow behaviour of smooth and ribbed square channel using commercial CFD software, ANSYS 15.0 (Fluent). Renormalization k-ε model was employed to assess the influence of protruded ribs on turbulent flow and velocity field. The outcome indicates that Al2O3 nanofluid has the highest value of average Nusselt number as compare to other nanofluids. The average Nusselt number increases as the concentration increases and it decreases as nanoparticle diameter increases. The thermal hydrodynamic performance parameter based on equal pumping power, average Nusselt number and average friction factor were found to be highest for Al2O3, Ï = 0.04, dnp = 30 nm, Xs/dp = 1.8, Ys/dp=1.8 and ep/dp=1.0. The numerical data are compared with the corresponding experimental data. Comparison between CFD and experimental analysis results showed that good agreement as the data fell within ±7.0% error band. Keywords: Nanofluid, Turbulent heat transfer, Stream and span wise spacing, Flow channel, Protruded ri