An initial investigation of the thermal-fluid characterization of a visualized loop thermosyphon

A initial investigation on the thermal-fluid performance of the visualized glass-water loop thermosyphon (LTS) with an U-turn compensation tube is reported in this article. The U-turn compensation tube may contribute to the unidirectional flow of the working fluid in the LTS. The results show that the favorable working fluid filling ratio is within the range of 43% to 70%. Fast startup of 10~40 s and thermal resistance of 0.625~0.7 °C/W of the LTS at the favorable filling ratio is achieved. The bulk boiling position in the evaporator moves away from the inlet of the evaporator with the increase of the filling ratio. When the value of charge ratio is up to 83%, the oscillation of the working fluid occurs in the loop cycle. The inclination angle within the range of 0~50° has a slight impact on the thermal performance of the LTS.