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.