Enhancement of thermal performance of a wickless gravity heat pipe with hybrid nanofluid including graphene and MgO nanoparticles: an experimental study

摘要

Graphene nanoplatelets (GNPs) have gained a popularity nowadays thanks to their unique properties. The usage of GNPs with other nanoparticles in thermal systems (like heat exchangers, heat pipes, etc.) may further increase the performance of the system. A hybrid nanofluid containing GNPs and MgO nanoparticles was utilized to enhance the heat transfer characteristic of a wickless gravity heat pipe in this experimental study. The heat pipe was tested in vertical position. The nanofluids including GNPs, MgO, their mixture (50:50) and water were utilized as working fluids and results were compared. Wall temperature, thermal resistance and thermal efficiency values were calculated for working fluids. Maximum efficiency value was achieved as 68.97 when GNPs + MgO/Water hybrid nanofluid was used. The mass flow rate and heating power were 9 g/s and 300 W, respectively. Maximum enhancement rate in thermal efficiency has been found as 57 when the working fluid was GNPs + MgO/Water hybrid nanofluid compared to the base fluid. Utilizing of nanofluid also decreased both evaporator temperature and evaporator and condenser sections' temperature difference. So, heat pipe thermal resistance was decreased by using nanofluids. The results were also compared with other results in literature. This comparison showed that the presence of GNPs in nanofluid has a considerable effect on heat transfer rate of a heat pipe.