Investigation of heat transfer performance of hybrid nanofluids made of carbon and metal oxide based particles in the use of thermosiphon heat pipes

In this thesis study, the effectiveness of the thermosyphon heat pipe was investigated for a single metal oxide-based nanofluid and a hybrid nanofluid consisting of two different carbon nanoparticles at five different concentrations and for five different filling ratios for the most efficient concentration level. Distilled water was used as the working fluid due to its low cost and widespread use in practice. Titanium dioxide -Distilled Water (TiO2/DS), one of the nanofluids with single particles, was chosen as the control group due to its widespread applications. Graphene Nano Plates (GNP)+Multi-Walled Carbon Nano Tubes (MSNCT)/DS hybrid nanofluid was used as the hybrid nanofluid. Although it is known that carbon group nanoparticles significantly increase nanofluid thermal conductivity in nanofluid applications; There are a limited number of studies addressing the performance of hybrid nanofluids obtained from carbon-based nanoparticles consisting of two-dimensional and three-dimensional particles in a thermal system. In general, nanofluids are known to significantly improve the thermal properties of TIB by reducing thermal resistance and increasing the thermal efficiency of Thermosyphon Heat Pipe (TIB). In contrast, the thermal performance of TIB is tightly dependent on operating variables, especially parameters such as the type of nanoparticles, their concentration and filling ratio. As a result of this thesis study, it has been understood that carbon-based nano-hybrid nanofluids show superior thermal performance compared to single nanofluids. On the other hand, it was understood that the concentration value at which the single nanofluid TiO2-DS showed the highest performance and the concentration value at which the GNP+MDKNT/DS hybrid nanofluid showed the maximum performance were different from each other. It has been observed that the performance response of carbon-based hybrid nanofluids and single metal oxide-based nanofluids against changing filling rates is different from each other..