关键词: 热管, 弯曲, 热阻, 传热性能

Abstract:

Heat transfer was experimentally investigated in a sintered flat heat pipe. The shell of the heat pipe was fabricated from oxygen-free copper, and the working medium was a mixture of water and ethanol. The wick of the heat pipe was a sintered copper ball. The sintered flat heat pipe was 3.2 mm thick, 8 mm wide, and 400 mm long. Its bending radius was 20 mm, and its bending angle was varied as 30°, 50°, 70°, and 90°. The heat transfer performance of the pipe was evaluated for heat sources of different temperatures (50 ℃, 60 ℃, 70 ℃, and 80 ℃), generated by heating quantitative cold water. In a preliminary test, the temperature difference in each part of the heat pipe was not significantly affected by the bending angle. Even the pipe bent at 90° showed good isothermal properties. In a further study, the thermal resistance of the heat pipe was reduced by increasing the source temperature and reducing the bending angle. The heat resistance performance of the heat pipe mainly depended on the bending angle. When the bending angle increased from 30° to 90°, the thermal resistance increased by more than 60% because the bend crushed the liquid core and deformed the flow of the absorption liquid working medium. Consequently, the fluid flow was hindered and the heat transfer performance declined. Moreover, changing the temperature of the heat source altered the heat transfer capacity in the evaporation section of the heat pipe. As the source temperature increased, the heat resistance of the heat pipe decreased. Finally, sensitive heat storage was investigated in a bent flat heat pipe. At higher source temperatures and lower bending angles of the heat pipe, the time of the sensible heat storage was lowered and the rate of sensible heat storage increased.

Key words: heat pipe, bending, thermal resistance, the heat transfer performance