Performances of a Cylindrical Heat Pipe Using Ferrofluid as the Working Liquid at Different Inclination Angles

In this research, the thermal performance of a cylindrical heat pipe filled with a ferrofluid as the working liquid was tested at different inclination angles: 0, 60, and 90o. The ferrofluid was synthesized from magnetite particles and water as the base fluid. The heat pipe was manufactured from a copper container, and copper fibers were used as the wick structure inside the heat pipe. The magnetite particles had an average diameter of 13 nm, as was yielded by the transmission electron microscopy (TEM). The zeta potential value (30.25 mV) and visual analysis showed that the ferrofluid was stable for nine months and could be used as the working liquid in cylindrical heat pipes. The thermal conductivity and specific heat of the ferrofluid were 0.605 W/(m·K) and 4090 J/(kg∙K), respectively. The performances of the heat pipe at different inclination angles allowed the conclusion about a relatively stable thermal resistance and temperature distribution, particularly at a higher heat input of 15 W.