Nanofluid, the suspension of nanoparticles in fluids (water, ethylene glycol, propylene glycol), has been widely promised as a medium for heat transfer in recent years. It is essential, however, to be familiar with the physical method of heat transfer in such fluids. In the present study, the improvement of heat transfer by natural convection in a vertical cylindrical shell using nanofluids with one end heated and the other end cooled is reported. The experimental study highlighted a presumably inconsistent behavior of the heat transfer declination. The study examined the nature of this declination and its dependence on parameters such as the concentration of the particles, the configuration of the cavity containing them and the material of the particles. Miniaturization has become a trend in the modern world as the saying “bigger is better” paves the way for “smaller is better”. Industries need compact equipment that reduces space consumption and works efficiently even in heat transfer applications. Heat transfer in a closed chamber has numerous engineering applications, for example in automotive, aerospace, boiler systems, electronics cooling, heat exchangers and much more. Heat buildup in a particular spot will cause discomfort and lead to poor performance. Many methods and experiments have been conducted to remove the excess heat generated. Natural convection is a heat transfer mechanism used in several applications. One-phase suspensions dispersed as small particles in the basic liquid phase play a vital role in the food and beverage, pharmaceutical and refrigeration industries. Years ago it was observed that the improvement of the thermal properties of liquids could be achieved with one of the characteristics of suspensions. Many micro and......half of paper......e.g., maximum heat transfer rate at Ra=109 and L/D=75mm. Figure b explains that the greater the heat transfer at a higher concentration level of the nanoparticle. The improvement of convective heat transfer over water-based nanofluid in a closed cylindrical chamber is experimentally analyzed in the present study. This study presents the experimental details for the silver/water nanofluid with water and at different concentration levels. It is obvious that the heat transfer rate can be increased by adding nanoparticles at a higher volume concentration. The observed results show that the silver/water nanofluid has better heat transfer characteristics than water. With the given heat input, the nanoparticles showed an increase in heat transfer of 47% at a concentration of 0.01% and 55% at a concentration of 0.03%. It is shown that the chosen nanoparticles depend on Nusselt proliferation.