Thermal Analysis and Performance Characteristics of Double Pipe Heat Exchanger Using Aluminium Oxide Al2O3 and Iron Oxide Fe2O3 Nanofluid

Abstract

Heat exchangers are widely used in industrial applications. The aim of this study was to investigate the thermal conductivity, heat transfer coefficient, Nusselt number, and Reynolds number of baseline water, Fe₂O₃, and Al₂O₃ nanofluids at different volume concentrations and flow rates using a double-pipe heat exchanger. The results were compared between baseline water and the two nanofluids. The test rig was operated at a temperature of 60 °C, suitable for industrial applications. Experiments were conducted at flow rates ranging from 1 to 2 L/min, corresponding to Reynolds numbers between 1500 and 3400, with volume concentrations from 0.10% to 0.175%.

The study showed that increasing the nanoparticle volume concentration enhanced the density, viscosity, thermal conductivity, heat transfer rate, and convective heat transfer coefficient of the Nano fluids at different flow rates. The density and viscosity of Al₂O₃ and Fe₂O₃ Nano fluids increased by 2.2%, 3.32% and 13.92%, 25.5%, respectively, compared to baseline water. The average heat transfer coefficient improved by approximately 28% to 37% in counter-flow configuration when using iron oxide and aluminum oxide nanofluids. This improvement is attributed to the higher thermal conductivity of Al₂O₃ compared to Fe₂O₃ nanofluid and water. The results suggest that Al₂O₃ nanofluid at 0.175% concentration can perform more effectively as a working fluid than Fe₂O₃ nanofluid and conventional water for industrial applications.