he presence of nanoparticles enhances heat transfer in heat exchangers. The degree of enhancement depends on the type, size, and shape of nanoparticles, as well as temperature conditions. Therefore, this study aims to improve thermal conductivity in a hybrid nanofluid by incorporating a nanocomposite. Due to their high thermal conductivity, spherical-shaped silver nanoparticles are suitable for synthesizing composites with cylindrical-shaped functionalized multi-wall carbon nanotubes. The characteristics of the synthesized nanocomposite were investigated via UV-Vis spectrophotometer, SEM, and TEM analyses. Also, the effects of Ag concentrations and temperature on thermal conductivity were investigated. The thermal conductivity can be enhanced by 15%, increasing Ag concentration from 0.05-0.5 wt.% and temperature in the 20-45 C range. The stability of the synthesized MWCNT/Ag nanofluid was evaluated after more than 90 days. The results indicated that the nanofluids with lower concentrations of Ag nanoparticles preserved their stability without using a surfactant.
