Thermal Augmentation of Double-tube Heat Exchangers Using Tailored Al₂O₃ Nanoparticle Suspensions
J. Environ. Nanotechnol., Volume 15, No 1 (March 2026) pp. 48-58
Abstract
This study investigates the thermal–hydraulic performance of a counter-flow double-tube heat exchanger employing Al₂O₃–water nanofluids at varying nanoparticle volume concentrations (0.01%, 0.1%, 0.2%, and 0.3%) and compares their performance with that of the base fluid (water). Experiments were conducted over a mass flow rate range of 0.012–0.026 kg/s to evaluate the influence of nanoparticle concentration and flow rate on key thermal and hydraulic parameters, including Reynolds number (Re), logarithmic mean temperature difference (LMTD), overall heat transfer coefficient (OHTC), number of transfer units (NTU), friction factor, effectiveness, and convective heat transfer coefficient (CHTC). The results revealed that increasing nanoparticle concentration enhances the heat transfer characteristics of the system while inducing only a minor rise in flow resistance. The Reynolds number decreases slightly with nanoparticle addition due to increased viscosity, whereas the OHTC and CHTC show significant improvements up to 30–35% at a concentration of 0.3 vol.%. The NTU and effectiveness also increase, indicating enhanced heat exchange performance. Although a small increase in friction factor was observed, the gain in thermal efficiency far outweighs the hydraulic penalty. Overall, the findings demonstrate that Al₂O₃–water nanofluids are an effective working medium for enhancing the energy efficiency and compactness of double-tube heat exchangers used in cooling, thermal management, and sustainable energy systems.
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Reference
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