Experimental study on metallic water nanofluids flow inside rectangular duct equipped with circular pins (pin channel)

• Flow of metallic nanofluids in pin channels is studied experimentally.
• Cu–water, Fe–water, and Ag–water nanofluids are applied as working fluid.
• Effects of flow rate, pins diameter, and pins spacing are examined.
• Heat transfer improves by using nanofluids.
• Ag–water nanofluid shows a better thermal–hydraulic performance.

An experimental investigation is performed to study the performance of three metallic nanofluids on fluid flow and heat transfer characteristics of a rectangular duct equipped with circular pins, i.e. pin channel. Tests are performed using 0.1 % weight concentration of Cu–water, Fe–water, and Ag–water nanofluids. Prior to the experiments, the required thermo-physical properties of nanofluids are measured. Effects of the flow rate (4–10 l/min), pins diameter (d = 1.0, 3.8, 4.8, and 6.0 mm), and longitudinal spacing of pins (p = 20, 40, and 60 mm) are investigated. Experimental results indicate that the use of pins inside the duct can noticeably improve the heat transfer performance. The maximum rise of 84.1% in the heat transfer coefficient is observed for the water flow inside the pin channel with d = 6.0 mm & p = 20 mm compared to the empty duct. Also, the results show that addition of small amounts of metallic nanoparticles to the base fluid augments the heat transfer coefficient of pin channels remarkably. It is found that based on the considered performance evaluation criterion, the Ag–water nanofluid yields best thermal–hydraulic performance (maximum value of 1.98). Correlations are also proposed for Nusselt number and friction factor which fit the experimental data within ±15%.

Arrays of pins.Figure optionsDownload as PowerPoint slide