Experimental investigation on isothermal performance of the micro-grooved heat pipe

The micro-grooved heat pipe (MGHP), which has grooves in the inner wall, is widely used in electronic heat dissipation at high heat flux. It was made via the technology of vacuuming and filling working fluid. The isothermal performance of MGHP was analyzed in the first vacuuming, filling rate of working fluid and second vacuuming. The experimental results show the following conclusions: firstly, the MGHP in low vacuum degree has more remarkable temperature drop than that in high vacuum degree. The maximum slope of temperature distribution curve of the MGHP in low vacuum degree moves to gas-gathering section with the increase of the heating temperature. Secondly, increasing the first vacuuming time does not always improve the isothermal performance remarkably. There exists optimal first vacuuming time, such as 30 s in this study. Thirdly, at high working temperature, with increasing the filling rate of working fluid (ranges from 80% to 120%), the temperature difference between the evaporator and the end of condenser generally increases. Fourthly, second vacuuming has a remarkable influence on the isothermal performance of the MGHP. After second vacuuming, the MGHP has a small value of temperature difference that is nearly half of the initial value between the evaporator and the end of condenser. In this experiment, a second vacuuming time at 30 s and a second vacuuming temperature at 100 °C are preferred parameters.