Experimental Investigation of Thermal–Hydraulic Performance of Nanofluids in a Heat Exchanger

The present study experimentally investigates the thermal-hydraulic performance of TiO₂-water nanofluid in a concentric double-tube heat exchanger.TiO₂ nanoparticles with an average size of 20 nm were dispersed in distilled water using a two-step preparation method with magnetic stirring and sonication to ensure stability.Nanofluids were prepared at volume concentrations of 0.1% and 0.125%.The thermophysical properties were evaluated, and experiments were conducted under varying hot water flow rates of 400, 600, and 800 LPH while maintaining a constant cold fluid flow rate.The effects of nanoparticle concentration and flow rate on heat transfer coefficient and Nusselt number were analyzed and compared with distilled water.Results indicate that the incorporation of TiO₂ nanoparticles enhances the heat transfer performance significantly.The maximum heat transfer coefficient was observed at 0.1% volume concentration and 800 LPH flow rate, showing notable improvement compared to the base fluid.However, enhancement in heat transfer was accompanied by a moderate increase in viscosity and pressure drop.The findings demonstrate that TiO₂-water nanofluid can effectively improve the performance of heat exchangers, and an optimal nanoparticle concentration exists for achieving maximum thermal efficiency with acceptable hydraulic performance.