Experimental investigation of glass heat pipes

A heat pipe is a passive heat transfer device that transfers heat from one environment to another. Similar to the commonly used copper and aluminum heat pipes, glass heat pipes are also used in solar power systems. Although there are many studies on conventional heat pipes, studies on glass heat pipes are scarcely any. In this study, the surface temperatures and total thermal resistance of a 37 mm diameter and 1850 mm long heat pipe made entirely of glass were experimentally investigated. Four separate glass heat pipes were vacuumed and closed by charging "3 ml ethanol", "4 ml ethanol", "2 ml ethanol +2 ml water" and "3 ml ethanol + 1 ml water". Electrical heat flux was given to the evaporator region of the heat pipe and water was drawn from the condenser region. The heat pipe was investigated at different heat fluxes and different angles of inclination. In the experiments, when the heat pipe is started for the first time, the surface temperature increases rapidly and becomes stable after a certain period of time. These temperature fluctuations are more visible at low powers and large inclination angles. In the time-dependent experiments of the heat pipe, it takes a long time for the heat pipe to stabilize. As the heat flux applied from the evaporator region increases, the stabilization time also decreases. It has been observed that the heat pipe gives the best performance at all heat loads and different working fluids at an angle of inclination of 30°. It was determined that the best working fluid was ethanol, which was used alone. By creating different working fluids and different experimental conditions, it will contribute to the improvement of working performance.