Counter Flow Heat Exchanger Analysis of Copper–Silica Hybrid Nanofluids under Laminar Flow

The study focuses on the preparation of Cu–SiO2 hybrid nanofluids in a glycerol and water base at different volume loadings. Thermophysical properties of the nanoparticles are measured at 20–80°C and characterized using FESEM, EDX, and XRD. Thermal conductivity and viscosity are tested using a TPS-500S hot disk thermal constants analyzer and a Brookfield Viscometer. The study finds that temperature and concentration both increase thermal conductivity, while viscosity increases with concentration and falls as temperatures rise. The highest thermal conductivity enhancement is found with 1% concentration at 80°C, while viscosity is least at 0.2% concentration. Heat transfer experiments are conducted in a double tube heat exchanger, showing that 1% concentration increases overall and convective heat transfer coefficients by 26.3 and 49.4% over base liquid at 36°C.