Effect of concentration and sedimentation on boiling heat transfer coefficient of GNPs-SiO2/deionized water hybrid Nanofluid: An experimental investigation

Abstract One of the most investigated and broadly used heat transfer processes in the industry is the boiling heat transfer. In this research, an experimental investigation concerning the boiling heat transfer of the silicon oxide-graphene hybrid nanofluid in the deionized water, as the basefluid, was done. The nanofluid employed in this study was produced by a two-step method having very high stability. For the deionized water, the repeatability and accuracy of the experimental setup were performed four times, which has a perfect overlap to the available results in research history. The results showed that the boiling heat transfer coefficient (BHTC) of the nanofluid decreases by increasing concentration. This heat transfer coefficient decrease was observed in high heat fluxes. The surface roughness of the boiling changes by increasing concentration. Moreover, through increasing the concentration of the nanofluid, its surface tension also enhances, which has a great influence on the boiling process. Furthermore, it was reported that the boiling heat transfer is inversely related to the surface tension so that it decreases by increasing the surface tension. BHTC of DW, 0.1 vol%, and 0.8 vol% nanofluid was around 18.2, 11.6, 11.6 kW/m2.K at about 140 kW/m2 Heat Flux that enhanced to 44.2, 31.9, and 29.9 kW/m2.K at about 700 kW/m2 Heat Flux, respectively. The highest uncertainties of 3.4% and 7.5% were calculated for the heat flux and BHTC.