Study On Heat Transfer Performance In Closed Gravity Heat Pipe

Gravity heat pipe is widely applied in the fileds of space, military as well as thecivil industries for their excellent performance of heat transfer and simple structure.The technology of three-phase flow for energy saving and antiscale does well inenhancing heat transmition as well as the antiscale and descaling, which can help tosolve the relevant problems of heat transfer devices. Applying the technology ofthree-phase flow to the thermosyphons can not only broaden the application fields ofit, but also help to study how to enhance heat transmition of thermosyphons.In order to broaden the application fields of using three-phase flow technology toenhance heat transmition and descaling and improve the thermosyphon’s performanceas well, studies are done to investigate the performance of two-phase flow gravityheat pipe and the three-phase one by designing a closed gravity heat pipe made ofmetal and a visual heat pipe, in which the influence of the filling ratio, heating power,solid-holdup and particle properties on the two-phase flow and three-phase flowgravity heat pipe’s heat transfer performance was tested. The result shows that heattransfer coefficient of three-phase flow gravity heat pipe gets increasing as the powerincreases, while decreases with the filling rate increasing. While the three-phase flowthermosyphons can enhance the heat transmition, the particle properties play animportant part in it. Compared with the two-phase flow heat pipe, the heat transferenhancement with30%PA66performs is best, and the evaporator section’s heattransfer coefficient increases by1.098~1.463when20%PA66is1.04~1.356andPOM2.5is1.088~1.241. The performance of the evaporator section fluctuates withthe solid holdup increasing, while there’s always a point on which it performs the bestin different conditions. And the performance of the condensation section varies withthe evaporator section. As the particle diameter increases, the heat transfer coefficientof the evaporation section first decreases and then increases, but the change of heattransfer coefficient in condensation section goes the opposite.