Efficient convective heat transfer enhancement in heat exchanger tubes with water based novel hybrid nanofluids: experimental investigation.

An experimental investigation on the influence of hybrid nanofluids (HNFs) on heat transfer and flow performance of a heat exchanger tube is presented in this paper. A custom-made thermo-hydraulic loop containing a 1200 mm long copper tube with 12 mm internal diameter is used for the present purpose. The tube was exposed to a constant heat flux of 4530 W m⁻². Water-based novel HNFs of SiO₂-MgO, SiO₂-ZnO, SiO₂-TiO₂ and SiO₂-ZrO₂ at 0.05 mass % and pure Deionized (DI) water are used as working fluids. The test-fluids are fed into the loop at a varying mass flow rate from 0.03 to 0.27 kg s⁻¹. Significant enhancement in heat transfer of the tube is obtained with the HNFs when compared to DI-water. The heat transfer performance is enhanced up to 94% with the application of HNFs. The SiO₂–MgO exhibits the best heat transfer performance as compared to the other HNFs. The SiO₂-ZrO₂ HNF shows the worst performance, even worse than DI-water. The rise in friction factor caused by HNFs is identical and very limited as compared to DI-water. Finally, thermo-hydraulic performance of HNFs is analyzed by drawing Figure of Merit (FOM). Based on the FOM analysis, an optimum flow rate of 0.13 kgs⁻¹ and SiO₂–MgO HNF are recommended for future heat transfer applications. [ABSTRACT FROM AUTHOR]