Natural nanofluid-based cooling of a protuberant heat source in a partially-cooled enclosure

This work investigates a two-dimensional natural convection in a square enclosure with a protuberant heat source that may resemble an electrical transformer. It is a laminar and non-steady regime. The finite element method is used to approximate solutions. Linear quadrilateral elements are employed to spatially discretize the domain. Several validations are carried out with numerical and experimental results. Water-based nanofluids have copper or alumina or titanium oxide as their nanoparticles. Lateral vertical cold walls have variable heights and they are referred to fins, which could be considered to be part of the cooling system to refrigerate electrical transformers, for example. Ten heights are studied for these cold walls. Rayleigh number ranges from 103 to 106 and the volume fraction from 0 to 0.016, totaling 9 suspension concentrations. By combining all geometrical and physical parameters, 1080 cases are run. Just part of the temperature and velocity behavior is shown here. The concentrations are very small in order to be in agreement with the correlations used for thermal viscosity and thermal conductivity. In a general view, nanofluids proved to smoothly enhance heat transfer as the concentration increases for the range adopted. However, nanoparticle materials play an important role on Nusselt number, being that the highest heat transfer values are for copper.